CN117321955A - Method and apparatus for reference signal transmission - Google Patents

Abstract

Methods, apparatus, systems, and/or programs for Reference Signal (RS) transmission and reception in wireless communications (e.g., 5G NR) are disclosed. For example, a method implemented by a wireless transmit/receive unit (WTRU) includes: receiving configuration information indicating a set of RS resources, a set of candidate RS resources, and a threshold; receiving a first RS in an RS resource of the set of RS resources; selecting a candidate RS resource from the set of candidate RS resources based on a determination that the received measurement of the first RS is less than or equal to the threshold; and receiving a second RS in the selected candidate RS resources.

Description

Method and apparatus for reference signal transmission

Cross Reference to Related Applications

The present application claims priority and benefit from U.S. provisional application No. 63/168,111, filed 3/30/2021, and U.S. provisional application No. 63/249,271, filed 9/2021, both of which are hereby incorporated by reference in their entireties as if fully set forth below for all useful purposes.

Disclosure of Invention

The present disclosure relates generally to the field of wireless and/or wired communication networks. For example, one or more embodiments disclosed herein relate to methods, apparatuses, systems, and/or programs for Reference Signal (RS) transmission and reception in wireless communications (e.g., 5G NR).

In one embodiment, a method for wireless communication implemented by a wireless transmit/receive unit (WTRU) includes: receiving configuration information indicating a set of RS resources, a set of candidate RS resources, and a threshold; receiving a first RS in an RS resource of the set of RS resources; selecting a candidate RS resource from the set of candidate RS resources based on a determination that the received measurement of the first RS is less than or equal to the threshold; and receiving a second RS in the selected candidate RS resources.

In another embodiment, a method implemented by a WTRU for wireless communication includes: receiving configuration information indicating a set of RS resources and a set of candidate RS resources; determining a Listen Before Talk (LBT) failure for one or more RSs associated with the set of RS resources; determining one or more candidate RS resources from the set of candidate RS resources based on the configuration information and the determined LBT failure; and receiving an RS transmission using the determined one or more candidate RS resources.

In one embodiment, a WTRU including a processor, a transmitter, a receiver, and/or a memory is configured to implement one or more methods disclosed herein. For example, the WTRU is configured to receive configuration information indicating a set of RS resources, a set of candidate RS resources, and a threshold; receiving a first RS in an RS resource of the set of RS resources; selecting (or determining) a candidate RS resource from the set of candidate RS resources based on a determination that the received measurement of the first RS is less than or equal to the threshold; and receiving a second RS in the selected candidate RS resources.

Drawings

A more detailed understanding can be obtained from the following detailed description, which is given by way of example in connection with the accompanying drawings. As with the detailed description, the drawings in such figures are examples. Accordingly, the drawings and detailed description are not to be regarded as limiting, and other equally effective examples are possible and contemplated. Additionally, like reference numerals ("ref") in the drawings denote like elements, and wherein:

FIG. 1A is a system diagram illustrating an exemplary communication system in which one or more disclosed embodiments may be implemented;

fig. 1B is a system diagram illustrating an exemplary wireless transmit/receive unit (WTRU) that may be used within the communication system shown in fig. 1A;

fig. 1C is a system diagram illustrating an exemplary Radio Access Network (RAN) and an exemplary Core Network (CN) that may be used within the communication system shown in fig. 1A;

fig. 1D is a system diagram illustrating a further exemplary RAN and a further exemplary CN that may be used within the communication system shown in fig. 1A;

FIG. 2 is a table showing frequencies of 52.6GHz to 71GHz for use in different countries, in accordance with one or more embodiments;

FIG. 3 is a table showing frequencies of 71GHz to 100GHz used in different countries in accordance with one or more embodiments;

FIG. 4 is a diagram illustrating exemplary operations of Reference Signal (RS) transmission in accordance with one or more embodiments;

fig. 5 is a diagram illustrating exemplary operation of an RS transmission in one or more RS candidates when Listen Before Talk (LBT) of the one or more RSs fails in accordance with one or more embodiments;

fig. 6 is a slot diagram each illustrating an example of a quasi co-location (QCL) hypothesis determination for multiple Physical Downlink Shared Channels (PDSCH) in accordance with one or more embodiments;

fig. 7 is a diagram illustrating an example of dynamic RS resource determination based on measured quality, transmission type, and/or number of antenna ports in accordance with one or more embodiments; and is also provided with

Fig. 8 is a flow diagram illustrating exemplary operations of dynamic RS resource determination and RS transmission/reception in accordance with one or more embodiments.

Detailed Description

In the following detailed description, numerous specific details are set forth in order to provide a thorough understanding of the embodiments and/or examples disclosed herein. However, it should be understood that such embodiments and examples may be practiced without some or all of the specific details set forth herein. In other instances, well-known methods, procedures, components, and circuits have not been described in detail so as not to obscure the description below. Furthermore, embodiments and examples not specifically described herein may be practiced in place of or in combination with embodiments and other examples that are explicitly, implicitly, and/or inherently described, disclosed, or otherwise provided (collectively, "provided"). Although various embodiments are described and/or claimed herein, wherein an apparatus, system, device, etc., and/or any element thereof, performs an operation, procedure, algorithm, function, etc., and/or any portion thereof, it is to be understood that any embodiment described and/or claimed herein assumes that any apparatus, system, device, etc., and/or any element thereof, is configured to perform any operation, procedure, algorithm, function, etc., and/or any portion thereof.

Exemplary communication System and apparatus

The methods, apparatus and systems provided herein are well suited for communications involving both wired and wireless networks. Wired networks are well known. An overview of various types of wireless devices and infrastructure is provided with respect to fig. 1A-1D, wherein various elements of a network may utilize, perform, and/or adapt and/or configure the methods, apparatuses, and systems provided herein.

Fig. 1A is a diagram of an exemplary communication system 100 in which one or more disclosed embodiments may be implemented. The exemplary communication system 100 is provided for illustrative purposes only and is not limiting of the disclosed embodiments. Communication system 100 may be a multiple-access system that provides content, such as voice, data, video, messages, broadcasts, etc., to a plurality of wireless users. Communication system 100 may enable multiple wireless users to access such content through the sharing of system resources, including wireless bandwidth. For example, communication system 100 may employ one or more channel access methods, such as Code Division Multiple Access (CDMA), time Division Multiple Access (TDMA), frequency Division Multiple Access (FDMA), orthogonal FDMA (OFDMA), single carrier FDMA (SC-FDMA), zero Tail (ZT) Unique Word (UW) Discrete Fourier Transform (DFT) spread OFDM (ZT UW DTS-s OFDM), unique word OFDM (UW-OFDM), resource block filtered OFDM, filter Bank Multicarrier (FBMC), and the like.

As shown in fig. 1A, the communication system 100 may include wireless transmit/receive units (WTRUs) 102a, 102b, 102c, 102d, radio Access Networks (RANs) 104/113, core Networks (CNs) 106/115, public Switched Telephone Networks (PSTN) 108, the internet 110, and other networks 112, although it should be understood that the disclosed embodiments contemplate any number of WTRUs, base stations, networks, and/or network elements. Each of the WTRUs 102a, 102b, 102c, 102d may be any type of device configured to operate and/or communicate in a wireless environment. As an example, the WTRUs 102a, 102b, 102c, 102d (any of which may be referred to as a "station" and/or a "STA") may be configured to transmit and/or receive wireless signals and may include (or be) User Equipment (UE), mobile stations, fixed or mobile subscriber units, subscription-based units, pagers, cellular telephones, personal Digital Assistants (PDAs), smartphones, laptops, netbooks, personal computers, wireless sensors, hotspots or Mi-Fi devices, internet of things (IoT) devices, watches or other wearable devices, head Mounted Displays (HMDs), vehicles, drones, medical devices and applications (e.g., tele-surgery), industrial devices and applications (e.g., robots and/or other wireless devices operating in an industrial and/or automated processing chain environment), consumer electronics devices, devices operating on a commercial and/or industrial wireless network, and the like. Any of the WTRUs 102a, 102b, 102c, and 102d may be interchangeably referred to as a WTRU.

Communication system 100 may also include base station 114a and/or base station 114b. Each of the base stations 114a, 114b may be any type of device configured to wirelessly interface with at least one of the WTRUs 102a, 102b, 102c, 102d, for example, to facilitate access to one or more communication networks, such as the CN 106/115, the internet 110, and/or the network 112. As an example, the base stations 114a, 114B may be any of a Base Transceiver Station (BTS), a Node B (NB), an evolved node B (eNB), a Home Node B (HNB), a home evolved node B (HeNB), a g node B (gNB), an NR node B (NR NB), a site controller, an Access Point (AP), a wireless router, and the like. Although the base stations 114a, 114b are each depicted as a single element, it should be appreciated that the base stations 114a, 114b may include any number of interconnected base stations and/or network elements.

Base station 114a may be part of RAN 104/113 that may also include other base stations and/or network elements (not shown), such as Base Station Controllers (BSCs), radio Network Controllers (RNCs), relay nodes, and the like. Base station 114a and/or base station 114b may be configured to transmit and/or receive wireless signals on one or more carrier frequencies, which may be referred to as cells (not shown). These frequencies may be in a licensed spectrum, an unlicensed spectrum, or a combination of licensed and unlicensed spectrum. A cell may provide coverage of wireless services to a particular geographic area, which may be relatively fixed or may change over time. The cell may be further divided into cell sectors. For example, a cell associated with base station 114a may be divided into three sectors. Thus, in an embodiment, the base station 114a may include three transceivers, i.e., one for each sector of a cell. In an embodiment, the base station 114a may employ multiple-input multiple-output (MIMO) technology and may utilize multiple transceivers for each or any sector of a cell. For example, beamforming may be used to transmit and/or receive signals in a desired spatial direction.

The base stations 114a, 114b may communicate with one or more of the WTRUs 102a, 102b, 102c, 102d over an air interface 116, which may be any suitable wireless communication link (e.g., radio Frequency (RF), microwave, centimeter wave, millimeter wave, infrared (IR), ultraviolet (UV), visible light, etc.). The air interface 116 may be established using any suitable Radio Access Technology (RAT).

More specifically, as noted above, communication system 100 may be a multiple access system and may employ one or more channel access schemes, such as CDMA, TDMA, FDMA, OFDMA, SC-FDMA, or the like. For example, a base station 114a in the RAN 104/113 and the WTRUs 102a, 102b, 102c may implement a radio technology such as Universal Mobile Telecommunications System (UMTS) terrestrial radio access (UTRA), which may use Wideband CDMA (WCDMA) to establish the air interfaces 115/116/117.WCDMA may include communication protocols such as High Speed Packet Access (HSPA) and/or evolved HSPA (hspa+). HSPA may include High Speed Downlink Packet Access (HSDPA) and/or High Speed Uplink Packet Access (HSUPA).

In an embodiment, the base station 114a and the WTRUs 102a, 102b, 102c may implement a radio technology such as evolved UMTS terrestrial radio access (E-UTRA), which may use Long Term Evolution (LTE) and/or LTE-advanced (LTE-a) and/or LTE-advanced Pro (LTE-a Pro) to establish the air interface 116.

In other embodiments, the base station 114a and the WTRUs 102a, 102b, 102c may implement radio technologies such as IEEE 802.16 (i.e., worldwide Interoperability for Microwave Access (WiMAX)), CDMA2000 1X, CDMA EV-DO, tentative standard 2000 (IS-2000), tentative standard 95 (IS-95), tentative standard 856 (IS-856), global system for mobile communications (GSM), enhanced data rates for GSM evolution (EDGE), GSM EDGE (GERAN), and the like.

In an embodiment, the base station 114a and the WTRUs 102a, 102b, 102c may implement a radio technology such as NR radio access that may use a new air interface (NR) to establish the air interface 116.

In embodiments, the base station 114a and the WTRUs 102a, 102b, 102c may implement multiple radio access technologies. For example, the base station 114a and the WTRUs 102a, 102b, 102c may implement LTE radio access and NR radio access together, e.g., using a Dual Connectivity (DC) principle. Thus, the air interface utilized by the WTRUs 102a, 102b, 102c may be characterized by multiple types of radio access technologies and/or transmissions sent to/from multiple types of base stations (e.g., enbs and gnbs).

In other embodiments, the base station 114a and the WTRUs 102a, 102b, 102c may implement radio technologies such as IEEE 802.11 (i.e., wireless fidelity (Wi-Fi)), IEEE 802.16 (i.e., worldwide Interoperability for Microwave Access (WiMAX)), CDMA2000 1X, CDMA EV-DO, tentative standard 2000 (IS-2000), tentative standard 95 (IS-95), tentative standard 856 (IS-856), global system for mobile communications (GSM), enhanced data rates for GSM evolution (EDGE), GSM EDGE (GERAN), and the like.

The base station 114B in fig. 1A may be, for example, a wireless router, home node B, home evolved node B, or access point, and may utilize any suitable RAT to facilitate wireless connections in local areas such as businesses, homes, vehicles, campuses, industrial facilities, air corridors (e.g., for use by drones), roads, and the like. In an embodiment, the base station 114b and the WTRUs 102c, 102d may implement a radio technology such as IEEE 802.11 to establish a Wireless Local Area Network (WLAN). In an embodiment, the base station 114b and the WTRUs 102c, 102d may implement a radio technology such as IEEE 802.15 to establish a Wireless Personal Area Network (WPAN). In an embodiment, the base station 114b and the WTRUs 102c, 102d may utilize a cellular-based RAT (e.g., WCDMA, CDMA2000, GSM, LTE, LTE-A, LTE-a Pro, NR, etc.) to establish any of a micro-cell, pico-cell, or femto-cell. As shown in fig. 1A, the base station 114b may have a direct connection with the internet 110. Thus, the base station 114b may not need to access the Internet 110 via the CN 106/115.

The RANs 104/113 may communicate with the CNs 106/115, which may be any type of network configured to provide voice, data, application, and/or voice over internet protocol (VoIP) services to one or more of the WTRUs 102a, 102b, 102c, 102 d. The data may have different quality of service (QoS) requirements, such as different throughput requirements, delay requirements, error tolerance requirements, reliability requirements, data throughput requirements, mobility requirements, and the like. The CN 106/115 may provide call control, billing services, mobile location based services, prepaid calls, internet connections, video distribution, etc., and/or perform advanced security functions such as user authentication. Although not shown in fig. 1A, it should be appreciated that the RANs 104/113 and/or CNs 106/115 may communicate directly or indirectly with other RANs that employ the same RAT as the RANs 104/113 or a different RAT. For example, in addition to being connected to the RAN 104/113 that may utilize NR radio technologies, the CN 106/115 may also communicate with another RAN (not shown) employing any of GSM, UMTS, CDMA, wiMAX, E-UTRA, or Wi-Fi radio technologies.

The CN 106/115 may also act as a gateway for the WTRUs 102a, 102b, 102c, 102d to access the PSTN 108, the Internet 110, and/or other networks 112.PSTN 108 may include circuit-switched telephone networks that provide Plain Old Telephone Services (POTS). The internet 110 may include a global system for interconnecting computer networks and devices using common communication protocols, such as Transmission Control Protocol (TCP), user Datagram Protocol (UDP), and Internet Protocol (IP) in the TCP/IP internet protocol suite. Network 112 may include a wired or wireless communication network owned and/or operated by other service providers. For example, network 112 may include another CN connected to one or more RANs, which may employ the same RAT as RANs 104/114 or a different RAT.

Some or all of the WTRUs 102a, 102b, 102c, 102d in the communication system 100 may include multi-mode capabilities (e.g., the WTRUs 102a, 102b, 102c, 102d may include multiple transceivers for communicating with different wireless networks over different wireless links). For example, the WTRU 102c shown in fig. 1A may be configured to communicate with the base station 114a, which may employ a cellular-based radio technology, and with the base station 114b, which may employ an IEEE 802 radio technology.

Fig. 1B is a system diagram of an exemplary WTRU 102. The exemplary WTRU 102 is provided for illustration purposes only and is not limiting of the disclosed embodiments. As shown in fig. 1B, the WTRU 102 may include a processor 118, a transceiver 120, a transmit/receive element 122, a speaker/microphone 124, a keypad 126, a display/touchpad 128, non-removable memory 130, removable memory 132, a power source 134, a Global Positioning System (GPS) chipset 136, and other peripherals 138, etc. It should be appreciated that the WTRU 102 may include any sub-combination of the foregoing elements while remaining consistent with an embodiment.

The processor 118 may be a general purpose processor, a special purpose processor, a conventional processor, a Digital Signal Processor (DSP), a plurality of microprocessors, one or more microprocessors in association with a DSP core, a controller, a microcontroller, application Specific Integrated Circuits (ASICs), field Programmable Gate Arrays (FPGAs) circuits, any other type of Integrated Circuit (IC), a state machine, or the like. The processor 118 may perform signal coding, data processing, power control, input/output processing, and/or any other functions that enable the WTRU 102 to operate in a wireless environment. The processor 118 may be coupled to a transceiver 120, which may be coupled to a transmit/receive element 122. Although fig. 1B depicts the processor 118 and the transceiver 120 as separate components, it should be understood that the processor 118 and the transceiver 120 may be integrated together, for example, in an electronic package or chip.

The transmit/receive element 122 may be configured to transmit signals to and receive signals from a base station (e.g., base station 114 a) over the air interface 116. For example, in one embodiment, the transmit/receive element 122 may be an antenna configured to transmit and/or receive RF signals. In one embodiment, the transmit/receive element 122 may be an emitter/detector configured to emit and/or receive, for example, IR, UV, or visible light signals. In an embodiment, the transmit/receive element 122 may be configured to transmit and receive both RF signals and optical signals. It should be appreciated that the transmit/receive element 122 may be configured to transmit and/or receive any combination of wireless signals.

Further, although the transmit/receive element 122 is depicted as a single element in fig. 1B, the WTRU 102 may include any number of transmit/receive elements 122. For example, the WTRU 102 may employ MIMO technology. Thus, in one embodiment, the WTRU 102 may include two or more transmit/receive elements 122 (e.g., multiple antennas) for transmitting and receiving wireless signals over the air interface 116.

The transceiver 120 may be configured to modulate signals to be transmitted by the transmit/receive element 122 and demodulate signals received by the transmit/receive element 122. As noted above, the WTRU 102 may have multi-mode capabilities. For example, therefore, the transceiver 120 may include multiple transceivers to enable the WTRU 102 to communicate via multiple RATs (such as NR and IEEE 802.11).

The processor 118 of the WTRU 102 may be coupled to and may receive user input data from a speaker/microphone 124, a keypad 126, and/or a display/touchpad 128, such as a Liquid Crystal Display (LCD) display unit or an Organic Light Emitting Diode (OLED) display unit. The processor 118 may also output user data to the speaker/microphone 124, the keypad 126, and/or the display/touchpad 128. Further, the processor 118 may access information from and store data in any type of suitable memory, such as the non-removable memory 130 and/or the removable memory 132. The non-removable memory 130 may include Random Access Memory (RAM), read Only Memory (ROM), a hard disk, or any other type of memory storage device. Removable memory 132 may include a Subscriber Identity Module (SIM) card, a memory stick, a Secure Digital (SD) memory card, and the like. In other embodiments, the processor 118 may never physically locate memory access information on the WTRU 102, such as on a server or home computer (not shown), and store the data in that memory.

The processor 118 may receive power from the power source 134 and may be configured to distribute and/or control power to other components in the WTRU 102. The power source 134 may be any suitable device for powering the WTRU 102. For example, the power source 134 may include one or more dry battery packs (e.g., nickel cadmium (NiCd), nickel zinc (NiZn), nickel metal hydride (NiMH), lithium ion (Li-ion), etc.), solar cells, fuel cells, and the like.

The processor 118 may also be coupled to a GPS chipset 136, which may be configured to provide location information (e.g., longitude and latitude) regarding the current location of the WTRU 102. In addition to or in lieu of information from the GPS chipset 136, the WTRU 102 may receive location information from base stations (e.g., base stations 114a, 114 b) over the air interface 116 and/or determine its location based on the timing of signals received from two or more nearby base stations. It should be appreciated that the WTRU 102 may obtain location information by any suitable location determination method while remaining consistent with an embodiment.

The processor 118 may also be coupled to other peripheral devices 138, which may include one or more software modules/units and/or hardware modules/units that provide additional features, functionality, and/or wired or wireless connections. For example, the peripheral devices 138 may include accelerometers, electronic compasses, satellite transceivers, digital cameras (e.g., for photos or videos), universal Serial Bus (USB) port, vibration device, television transceiver, hands-free headset, portable electronic device, and electronic device,Modules, frequency Modulation (FM) radio units, digital music players, media players, video game player modules, internet browsers, virtual reality and/or augmented reality (VR/AR) devices, activity trackers, and the like. The peripheral device 138 may include one or more sensors, which may be one or more of the following: gyroscopes, accelerometers, hall effect sensors, magnetometers, orientation sensors, proximity sensors, temperature sensors, time sensors; a geographic position sensor; altimeters, light sensors, touch sensors, magnetometers, barometers, gesture sensors, biometric sensors, and/or humidity sensors.

WTRU 102 may include a full duplex radio for which transmission and reception of some or all signals (e.g., associated with a particular subframe for UL (e.g., for transmission) and downlink (e.g., for reception)) may be concurrent and/or simultaneous. The full duplex radio station may include an interference management unit for reducing and/or substantially eliminating self-interference via hardware (e.g., choke) or via signal processing by a processor (e.g., a separate processor (not shown) or via processor 118). In one embodiment, the WTRU 102 may include a half-duplex radio for which transmission and reception of some or all signals (e.g., associated with a particular subframe for UL (e.g., for transmission) or downlink (e.g., for reception)).

Fig. 1C is a system diagram of a RAN 104 and a CN 106 according to another embodiment. As noted above, the RAN 104 may communicate with the WTRUs 102a, 102b, and 102c over the air interface 116 using an E-UTRA radio technology. RAN 104 may also communicate with CN 106.

RAN 104 may include enode bs 160a, 160B, 160c, but it should be understood that RAN 104 may include any number of enode bs while remaining consistent with an embodiment. The enode bs 160a, 160B, 160c may each include one or more transceivers to communicate with the WTRUs 102a, 102B, 102c over the air interface 116. In one embodiment, the evolved node bs 160a, 160B, 160c may implement MIMO technology. Thus, the enode B160 a may use multiple antennas to transmit wireless signals to and receive wireless signals from the WTRU 102a, for example.

Each of the evolved node bs 160a, 160B, and 160c may be associated with a particular cell (not shown) and may be configured to process radio resource management decisions, handover decisions, user scheduling in the Uplink (UL) and/or Downlink (DL), and so on. As shown in fig. 1C, eNode-bs 160a, 160B, 160C may communicate with each other through an X2 interface.

The core network 106 shown in fig. 1C may include a mobility management gateway (MME) 162, a Serving Gateway (SGW) 164, and a Packet Data Network (PDN) gateway 166. Although each of the foregoing elements are depicted as part of the CN 106, it should be understood that any of these elements may be owned and/or operated by an entity other than the CN operator.

MME 162 may be connected to each of evolved node bs 160a, 160B, and 160c in RAN 104 via an S1 interface and may function as a control node. For example, the MME 162 may be responsible for authenticating the user of the WTRUs 102a, 102b, 102c, bearer activation/deactivation, selecting a particular serving gateway during initial attach of the WTRUs 102a, 102b, 102c, and the like. MME 162 may also provide control plane functionality for switching between RAN 104 and other RANs (not shown) employing other radio technologies, such as GSM or WCDMA.

SGW 164 may be connected to each of the evolved node bs 160a, 160B, 160c in RAN 104 via an S1 interface. The SGW 164 may generally route and forward user data packets to/from the WTRUs 102a, 102b, 102 c. The SGW 164 may also perform other functions such as anchoring user planes during inter-enode B handover, triggering paging when DL data is available to the WTRUs 102a, 102B, 102c, managing and storing the contexts of the WTRUs 102a, 102B, 102c, etc.

The SGW 164 may also be connected to a PDN gateway 166 that may provide the WTRUs 102a, 102b, and 102c with access to a packet switched network, such as the internet 110, to facilitate communications between the WTRUs 102a, 102b, 102c and IP-enabled devices.

The CN 106 may facilitate communications with other networks. For example, the CN 106 may provide the WTRUs 102a, 102b, 102c with access to a circuit-switched network (such as the PSTN 108) to facilitate communications between the WTRUs 102a, 102b, 102c and legacy landline communication devices. For example, the CN 106 may include or may communicate with an IP gateway (e.g., an IP Multimedia Subsystem (IMS) server) that serves as an interface between the CN 106 and the PSTN 108. In addition, the CN 106 may provide the WTRUs 102a, 102b, 102c with access to other networks 112, which may include other wired or wireless networks owned and/or operated by other service providers.

Although the WTRU is depicted in fig. 1A-1D as a wireless terminal, it is contemplated that in some representative embodiments such a terminal may use a wired communication interface with a communication network (e.g., temporarily or permanently).

In representative embodiments, the other network 112 may be a WLAN.

A WLAN in an infrastructure Basic Service Set (BSS) mode may have an Access Point (AP) for the BSS and one or more Stations (STAs) associated with the AP. The AP may have access or interface to a Distribution System (DS) or another type of wired/wireless network that carries traffic to and/or from the BSS. Traffic originating outside the BSS and directed to the STA may arrive through the AP and may be delivered to the STA. Traffic originating from the STA and leading to a destination outside the BSS may be sent to the AP to be delivered to the respective destination. Traffic between STAs within the BSS may be sent through the AP, for example, where the source STA may send traffic to the AP and the AP may pass the traffic to the destination STA. Traffic between STAs within a BSS may be considered and/or referred to as point-to-point traffic. Point-to-point traffic may be sent between (e.g., directly between) the source and destination STAs using Direct Link Setup (DLS). In certain representative embodiments, the DLS may use 802.11e DLS or 802.11z Tunnel DLS (TDLS). A WLAN using an Independent BSS (IBSS) mode may not have an AP, and STAs (e.g., all STAs) within or using the IBSS may communicate directly with each other. The IBSS communication mode may sometimes be referred to herein as an "ad-hoc" communication mode.

When using the 802.11ac infrastructure mode of operation or similar modes of operation, the AP may transmit beacons on a fixed channel, such as a primary channel. The primary channel may be a fixed width (e.g., 20MHz wide bandwidth) or a width dynamically set by signaling. The primary channel may be an operating channel of the BSS and may be used by STAs to establish a connection with the AP. In certain representative embodiments, carrier sense multiple access/collision avoidance (CSMA/CA) may be implemented, for example, in an 802.11 system. For CSMA/CA, STAs (e.g., each STA), including the AP, may listen to the primary channel. If the primary channel is listened to/detected by a particular STA and/or determined to be busy, the particular STA may backoff. One STA (e.g., only one station) may transmit at any given time in a given BSS.

High Throughput (HT) STAs may communicate using 40MHz wide channels, for example, via a combination of a primary 20MHz channel with an adjacent or non-adjacent 20MHz channel to form a 40MHz wide channel.

Very High Throughput (VHT) STAs may support channels that are 20MHz, 40MHz, 80MHz, and/or 160MHz wide. 40MHz and/or 80MHz channels may be formed by combining consecutive 20MHz channels. The 160MHz channel may be formed by combining 8 consecutive 20MHz channels, or by combining two non-consecutive 80MHz channels (this may be referred to as an 80+80 configuration). For the 80+80 configuration, after channel coding, the data may pass through a segment parser that may split the data into two streams. An Inverse Fast Fourier Transform (IFFT) process and a time domain process may be performed on each stream separately. These streams may be mapped to two 80MHz channels and data may be transmitted by the transmitting STA. At the receiver of the receiving STA, the operations described above for the 80+80 configuration may be reversed and the combined data may be sent to a Medium Access Control (MAC).

The 802.11af and 802.11ah support modes of operation below 1 GHz. Channel operating bandwidth and carrier are reduced in 802.11af and 802.11ah relative to those used in 802.11n and 802.11 ac. The 802.11af supports 5MHz, 10MHz, and 20MHz bandwidths in the television white space (TVWS) spectrum, and the 802.11ah supports 1MHz, 2MHz, 4MHz, 8MHz, and 16MHz bandwidths using non-TVWS spectrum. According to representative embodiments, 802.11ah may support meter type control/Machine Type Communication (MTC), such as MTC devices in macro coverage areas. MTC devices may have certain capabilities, such as limited capabilities, including supporting (e.g., supporting only) certain bandwidths and/or limited bandwidths. MTC devices may include batteries with battery lives above a threshold (e.g., to maintain very long battery lives).

WLAN systems that can support multiple channels, and channel bandwidths such as 802.11n, 802.11ac, 802.11af, and 802.11ah, include channels that can be designated as primary channels. The primary channel may have a bandwidth equal to the maximum common operating bandwidth supported by all STAs in the BSS. The bandwidth of the primary channel may be set and/or limited by STAs from all STAs operating in the BSS (which support a minimum bandwidth mode of operation). In the example of 802.11ah, for STAs (e.g., MTC-type devices) that support (e.g., only) 1MHz mode, the primary channel may be 1MHz wide, even though the AP and other STAs in the BSS support 2MHz, 4MHz, 8MHz, 16MHz, and/or other channel bandwidth modes of operation. Carrier sensing and/or Network Allocation Vector (NAV) settings may depend on the state of the primary channel. If the primary channel is busy, for example, because the STA (supporting only 1MHz mode of operation) is transmitting to the AP, the entire available frequency band may be considered busy even though most of the frequency band remains idle and possibly available.

The available frequency band for 802.11ah in the united states is 902MHz to 928MHz. In korea, the available frequency band is 917.5MHz to 923.5MHz. In Japan, the available frequency band is 916.5MHz to 927.5MHz. The total bandwidth available for 802.11ah is 6MHz to 26MHz, depending on the country code.

Fig. 1D is a system diagram illustrating a RAN 113 and a CN 115 according to an embodiment. As noted above, RAN 113 may employ NR radio technology to communicate with WTRUs 102a, 102b, 102c over an air interface 116. RAN 113 may also communicate with CN 115.

RAN 113 may include gnbs 180a, 180b, 180c, but it should be understood that RAN 113 may include any number of gnbs while remaining consistent with an embodiment. Each of the gnbs 180a, 180b, 180c may include one or more transceivers to communicate with the WTRUs 102a, 102b, 102c over the air interface 116. In an embodiment, the gnbs 180a, 180b, 180c may implement MIMO technology. For example, gnbs 180a, 180b may utilize beamforming to transmit signals to and/or receive signals from gnbs 180a, 180b, 180 c. Thus, the gNB 180a may use multiple antennas to transmit wireless signals to and/or receive wireless signals from the WTRU 102a, for example. In an embodiment, the gnbs 180a, 180b, 180c may implement carrier aggregation techniques. For example, the gNB 180a may transmit multiple component carriers to the WTRU 102a (not shown). A subset of these component carriers may be on the unlicensed spectrum while the remaining component carriers may be on the licensed spectrum. In embodiments, the gnbs 180a, 180b, 180c may implement coordinated multipoint (CoMP) techniques. For example, WTRU 102a may receive coordinated transmissions from gNB 180a and gNB 180b (and/or gNB 180 c).

The WTRUs 102a, 102b, 102c may communicate with the gnbs 180a, 180b, 180c using transmissions associated with the scalable parameter sets. For example, the OFDM symbol interval and/or OFDM subcarrier interval may vary from transmission to transmission, from cell to cell, and/or from part of the wireless transmission spectrum. The WTRUs 102a, 102b, 102c may communicate with the gnbs 180a, 180b, 180c using various or scalable length subframes or Transmission Time Intervals (TTIs) (e.g., including different numbers of OFDM symbols and/or continuously varying absolute time lengths).

The gnbs 180a, 180b, 180c may be configured to communicate with the WTRUs 102a, 102b, 102c in an independent configuration and/or in a non-independent configuration. In a standalone configuration, the WTRUs 102a, 102B, 102c may communicate with the gnbs 180a, 180B, 180c while also not accessing other RANs (e.g., such as the enode bs 160a, 160B, 160 c). In an independent configuration, the WTRUs 102a, 102b, 102c may use one or more of the gnbs 180a, 180b, 180c as mobility anchor points. In an independent configuration, the WTRUs 102a, 102b, 102c may use signals in unlicensed frequency bands to communicate with the gnbs 180a, 180b, 180 c. In a non-standalone configuration, the WTRUs 102a, 102B, 102c may communicate or connect with the gnbs 180a, 180B, 180c, while also communicating or connecting with other RANs (such as the enode bs 160a, 160B, 160 c). For example, the WTRUs 102a, 102B, 102c may implement DC principles to communicate with one or more gnbs 180a, 180B, 180c and one or more enodebs 160a, 160B, 160c substantially simultaneously. In a non-standalone configuration, the enode bs 160a, 160B, 160c may serve as mobility anchors for the WTRUs 102a, 102B, 102c, and the gnbs 180a, 180B, 180c may provide additional coverage and/or throughput for serving the WTRUs 102a, 102B, 102 c.

Each of the gnbs 180a, 180b, 180c may be associated with a particular cell (not shown) and may be configured to handle radio resource management decisions, handover decisions, scheduling of users in UL and/or DL, support of network slices, dual connectivity, interworking between NR and E-UTRA, routing of user plane data towards User Plane Functions (UPFs) 184a, 184b, routing of control plane information towards access and mobility management functions (AMFs) 182a, 182b, and so on. As shown in fig. 1D, gnbs 180a, 180b, 180c may communicate with each other through an Xn interface.

The CN 115 shown in fig. 1D may include at least one AMF 182a, 182b, at least one UPF 184a, 184b, at least one Session Management Function (SMF) 183a, 183b, and possibly at least one Data Network (DN) 185a, 185b. Although each of the foregoing elements are depicted as part of the CN 115, it should be understood that any of these elements may be owned and/or operated by entities other than the CN operator.

AMFs 182a, 182b may be connected to one or more of gNB 180a, 180b, 180c in RAN 113 via an N2 interface and may function as a control node. For example, the AMFs 182a, 182b may be responsible for authenticating users of the WTRUs 102a, 102b, 102c, support for network slices (e.g., handling of different Packet Data Unit (PDU) sessions with different requirements), selection of a particular SMF 183a, 183b, management of registration areas, termination of NAS signaling, mobility management, etc. The AMFs 182a, 182b may use network slices to customize CN support for the WTRUs 102a, 102b, 102c, e.g., based on the type of service used by the WTRUs 102a, 102b, 102 c. For example, different network slices may be established for different use cases, such as services relying on ultra high reliability low latency (URLLC) access, services relying on enhanced large-scale mobile broadband (eMBB) access, services for MTC access, etc. AMF 162 may provide control plane functionality for switching between RAN 113 and other RANs (not shown) employing other radio technologies, such as LTE, LTE-A, LTE-a Pro, and/or non-3 GPP access technologies, such as Wi-Fi.

The SMFs 183a, 183b may be connected to AMFs 182a, 182b in the CN 115 via an N11 interface. The SMFs 183a, 183b may also be connected to UPFs 184a, 184b in the CN 115 via an N4 interface. SMFs 183a, 183b may select and control UPFs 184a, 184b and configure traffic routing through UPFs 184a, 184b. The SMFs 183a, 183b may perform other functions such as managing and assigning UE IP addresses, managing PDU sessions, controlling policy enforcement and QoS, providing downlink data notifications, etc. The PDU session type may be IP-based, non-IP-based, ethernet-based, etc.

UPFs 184a, 184b may be connected to one or more of the gnbs 180a, 180b, 180c in the RAN 113 via an N3 interface, which may provide the WTRUs 102a, 102b, 102c with access to a packet-switched network, such as the internet 110, for example, to facilitate communications between the WTRUs 102a, 102b, 102c and IP-enabled devices. UPFs 184, 184b may perform other functions such as routing and forwarding packets, enforcing user plane policies, supporting multi-host PDU sessions, handling user plane QoS, buffering downlink packets, providing mobility anchoring, and the like.

The CN 115 may facilitate communications with other networks. For example, the CN 115 may include or may communicate with an IP gateway (e.g., an IP Multimedia Subsystem (IMS) server) that serves as an interface between the CN 115 and the PSTN 108. In addition, the CN 115 may provide the WTRUs 102a, 102b, 102c with access to other networks 112, which may include other wired and/or wireless networks owned and/or operated by other service providers. In one embodiment, the WTRUs 102a, 102b, 102c may connect to the local Data Networks (DNs) 185a, 185b through the UPFs 184a, 184b through an N3 interface to the UPFs 184a, 184b and an N6 interface between the UPFs 184a, 184b and the DNs 185a, 185b.

In view of fig. 1A-1D and the corresponding descriptions of fig. 1A-1D, one or more or all of the functions described herein with reference to any one of the following may be performed by one or more emulation elements/devices (not shown): the WTRUs 102a-102d, base stations 114a-114B, eNodeBs 160a-160c, MME 162, SGW 164, PGW 166, gNB 180a-180c, AMFs 182a-182B, UPFs 184a-184B, SMFs 183a-183B, DNs 185a-185B, and/or any other elements/devices described herein. The emulated device may be one or more devices configured to emulate one or more or all of the functions described herein. For example, the emulation device may be used to test other devices and/or analog network and/or WTRU functions.

The simulation device may be designed to enable one or more tests of other devices in a laboratory environment and/or an operator network environment. For example, the one or more emulation devices can perform one or more or all of the functions while being fully or partially implemented and/or deployed as part of a wired and/or wireless communication network in order to test other devices within the communication network. The one or more emulation devices can perform one or more functions or all functions while being temporarily implemented/deployed as part of a wired and/or wireless communication network. The emulation device may be directly coupled to another device for testing purposes and/or may perform testing using over-the-air wireless communications.

The one or more emulation devices can perform one or more (including all) functions while not being implemented/deployed as part of a wired and/or wireless communication network. For example, the simulation device may be used in a test laboratory and/or a test scenario in a non-deployed (e.g., test) wired and/or wireless communication network in order to enable testing of one or more components. The one or more simulation devices may be test equipment. Direct RF coupling and/or wireless communication via RF circuitry (e.g., which may include one or more antennas) may be used by the emulation device to transmit and/or receive data.

Embodiments disclosed herein relate generally to wireless and/or wired communication networks. For example, one or more embodiments disclosed herein relate to methods, apparatuses, systems, and/or programs for Reference Signal (RS) transmission in wireless communications (e.g., using shared spectrum and/or unlicensed frequency bands in high frequencies).

Introduction to the invention

In 5G New Radios (NRs), reference Signal (RS) transmission and/or measurement by a network entity (e.g., a gNB) and one or more WTRUs are critical to wireless communications and operation. In one example, a channel state information-reference signal (CSI-RS) (e.g., a tracking reference signal or TRS) for tracking may be transmitted by a network entity, and the WTRU may implement fine time/frequency tracking based on the transmitted (or received) TRS. In another example, the WTRU may measure one or more transmitted RSs and determine one or more CSI parameters (e.g., one or more CSI-RS resource indicators (CRI), rank Indicator (RI), layer Indicator (LI), precoding Matrix Indicator (PMI), and/or wideband/sub-band Channel Quality Indicator (CQI)). The WTRU may report the determined one or more CSI parameters to the network entity. However, shared spectrum operation in the unlicensed band may require Listen Before Talk (LBT) for RS transmissions as well as for other channels and signals. For example, the network entity may evaluate (or determine) whether the channel is idle prior to RS transmission. The network entity may transmit one or more RSs to the WTRU if the channel is idle. The network entity may not transmit one or more RSs to the WTRU if the channel is not idle. If no RS is transmitted, incorrect operation based on measurement of the RS that is not transmitted may occur. For example, if the WTRU determines channel quality for one or more of the following based on the non-transmitted RSs: beam management, CSI reporting, beam failure recovery, and/or RRM/RLM, an RS with high channel quality may be determined to be of low channel quality due to the absence of transmitted or received signals. In another example, if the WTRU tracks time/frequency synchronization based on an RS that is not transmitted, the WTRU may lose time/frequency tracking for the network entity and may need to switch to other network entities (e.g., one or more other gnbs).

NR exceeding 52.6GHz

In New Radios (NRs) exceeding 52.6GHz, according to research project investigation, a minimum of 5GHz spectrum (57 GHz to 64 GHz) is available for unlicensed operation, and up to 14GHz spectrum (57 GHz to 71 GHz) is available for unlicensed operation in some countries. Furthermore, the investigation has found that a minimum of 10GHz of frequency spectrum (71 GHz to 76GHz and 81GHz to 86 GHz) is available for licensed operation worldwide, and that up to 18GHz of frequency spectrum (71 GHz to 114.25 GHz) is available for licensed operation in some countries. Although the frequency range above 52.6GHz may contain greater spectrum allocations and greater bandwidths that are not available for the lower 52.6GHz band, the physical layer channels of NR are designed to be optimized for use below 52.6 GHz.

Operation in shared spectrum

Referring to fig. 2 and 3, most of the available frequencies from 52.6GHz to 71GHz are unlicensed spectrum that requires shared spectrum operation. Channel access in the unlicensed band typically uses a Listen Before Talk (LBT) mechanism. LBT is typically enforced independent of whether the channel is occupied or not.

For frame-based systems, LBT may be characterized by a Clear Channel Assessment (CCA) time (e.g., about 20 μs), a channel occupancy time (e.g., minimum 1ms, maximum 10 ms), an idle period (e.g., minimum 5% channel occupancy time), a fixed frame period (e.g., equal to channel occupancy time plus idle period), a short control signaling transmission time (e.g., 5% maximum duty cycle within a 50ms observation period), and a CAA energy detection threshold.

For a load-based system (e.g., the transmit/receive structure may not be fixed in time), LBT may be characterized by a number N corresponding to the number of idle slots in the extended CCA instead of a fixed frame period. N may be randomly selected within a certain range.

Deployment scenarios may include different independent NR-based operations, different variants of dual connectivity operations (e.g., 1) EN-DC with at least one carrier operating according to LTE Radio Access Technology (RAT) or 2) different variants with at least two sets of NR DC with one or more carriers operating according to NR RAT) and/or Carrier Aggregation (CA) (e.g., different combinations of zero or more carriers may also be included, and each carrier may use LTE RAT or NR RAT).

For example, for LTE, listen-before-talk (for clear channel assessment) is considered for LAA systems. The Listen Before Talk (LBT) procedure is defined as a mechanism by which equipment applies a Clear Channel Assessment (CCA) check before using the channel. CCA utilizes at least energy detection to determine the presence or absence of other signals on the channel in order to determine whether the channel is occupied or idle, respectively. European and japanese regulations require the use of LBT in unlicensed frequency bands. In addition to regulatory requirements, carrier sensing via LBT is one method of fairly sharing unlicensed spectrum and is considered an important feature of fair and friendly operation in unlicensed spectrum (e.g., in a single global solution framework).

SUMMARY

In NR, reference Signal (RS) transmission and/or measurement performed by a network entity (e.g., a gNB) and/or one or more WTRUs is critical to any of the following operations:

● Time/frequency tracking. For example, CSI-RS (TRS) for tracking may be transmitted by the network entity, and the WTRU may implement fine time/frequency tracking based on the TRS received from the network entity.

● And (5) beam management. For example, the WTRU may measure one or more transmitted RSs and determine one or more optimized beams based on L1-RSRP and/or L1-SINR. The WTRU may report the determined one or more optimized beams based on CSI reports with one or more of CRI, L1-RSRP, and/or L1-SINR.

● CSI reporting. For example, the WTRU may measure one or more transmitted RSs and determine one or more CSI parameters (e.g., one or more of CRI, RI, LI, PMI and wideband/sub-band CQI). The WTRU may report the determined one or more CSI parameters to the network entity.

● Beam Failure Recovery (BFR). For example, the WTRU may monitor the quality of PDCCH reception based on measurements of one or more transmitted RSs. If the measured quality (e.g., the hypothesized PDCCH block error rate (BLER)) of one or more transmitted RSs is below a threshold, the WTRU may report a beam failure to the network entity using the candidate/new beam determined based on the measured quality (e.g., L1-RSRP).

● Radio Resource Management (RRM) and/or Radio Link Monitoring (RLM). For example, the WTRU may measure one or more RSs (e.g., SSBs) and evaluate channel quality for multiple cells. Based on the channel quality, the WTRU may handover from the current cell to the new cell.

However, shared spectrum operation in the unlicensed band may require LBT for RS transmissions as well as for other channels and signals. For example, referring to fig. 4, LBT is performed before RS transmission in the shared spectrum. In this example, the gNB may evaluate/determine whether the channel is idle prior to RS transmission. If the channel is idle, the gNB may transmit one or more RSs to the WTRU. If the channel is not idle, the gNB may not transmit one or more RSs to the WTRU. For example, if an RS resource with a configured periodicity (e.g., the configured periodic RS resource and/or an active semi-persistent RS resource) is not transmitted when the channel is not idle, the WTRU may need to wait for the configured periodicity until the next RS transmission instance. In some cases, measurement of delay may degrade system performance due to delayed updating of channel related information (e.g., one or more of CSI, RRM, RLM and/or BFR).

In one example, PDSCH/PUSCH performance may be degraded due to MCS inaccuracy for PDSCH/PUSCH transmissions due to delayed measurements. In another example, the BFR may not be triggered due to a measurement of delay (e.g., delay detection based on a beam failure instance).

In one example, if the RS resources are triggered dynamically (e.g., via aperiodic RS resources/resource sets of the DCI) and the RS resources are not successfully transmitted when the channel is not idle, an increased DCI overhead may occur because the WTRU may need to receive another DCI trigger (e.g., to receive the RS resources) when the channel is idle.

In addition, if the RS is not transmitted, system performance may be degraded due to incorrect information based on the measurement of the RS that is not transmitted. For example, if the WTRU determines channel quality for one or more of the following based on the non-transmitted RSs: beam management, CSI reporting, beam failure recovery and/or RRM/RLM, then a channel/link with high channel quality may be determined to be of low channel quality due to the absence of the transmitted signal. In another example, if the WTRU tracks time/frequency synchronization based on an RS that is not transmitted, the WTRU may lose time/frequency tracking for the gNB and may need to switch to other gnbs.

Representative procedure for Reference Signal (RS) configuration and transmission

Various embodiments disclosed herein relate to methods, apparatuses, and/or procedures for Reference Signal (RS) configuration and transmission (e.g., using shared spectrum) in a wireless communication network. In one embodiment, candidate RS configurations/activations may be used or enabled, and if LBT for RS transmission fails, the WTRU may receive one or more RSs based on the candidate RS configurations/activations. In one embodiment, the LBT type may be configured or determined based on priority. For example, the procedure may increase the RS transmission probability by changing LBT type and/or priority of the RS (e.g., one or more failed RS transmissions). In one embodiment, accurate operation may be achieved by determining, by the gNB and/or the WTRU, that the RS transmission failed. In one embodiment, rate matching of one or more RSs may be performed/used on channels (or signals) transmitted in candidate RS slots/opportunities/resources. In one embodiment, the RS transmission scheme may be enabled by changing the beam for the corresponding RS transmission. In one embodiment, receiver-assisted LBT operation for RS transmissions may be enabled/used and hidden node problems for RS transmissions may be solved.

Definition of beams

In various embodiments, the WTRU may transmit or receive a physical channel (or reference signal) in accordance with at least one spatial domain filter. The term "beam" may be used to refer to a spatial domain filter.

The WTRU may transmit a physical channel or signal using the same spatial domain filter used to receive the RS (e.g., CSI-RS) or SS block. The WTRU transmissions may be referred to as a "target" and the received RS or SS blocks may be referred to as "reference" or "source". In such cases, the WTRU may be considered to transmit the target physical channel or signal according to a spatial relationship referencing such RS or SS blocks.

The WTRU may transmit the first physical channel or signal based on the same spatial domain filter used to transmit the second physical channel or signal. The first transmission and the second transmission may be referred to as "target" and "reference" or "source", respectively. In such cases, the WTRU may be considered to transmit a first (target) physical channel or signal according to a spatial relationship referencing a second (reference) physical channel or signal.

The spatial relationship may be implicit, configured by RRC, or signaled by MAC CE or DCI. For example, the WTRU may implicitly transmit PUSCH and DM-RS for PUSCH based on the same spatial domain filter as SRS indicated by an SRS Resource Indicator (SRI) (e.g., indicated in DCI or configured by RRC). In another example, the spatial relationship may be configured by RRC for SRI or signaled by MAC CE for PUCCH. Such spatial relationships may also be referred to as "beam pointing".

The WTRU may receive the first (target) downlink channel or signal based on the same spatial domain filter or spatial reception parameters as the second (reference) downlink channel or signal. For example, such an association may exist between physical channels such as PDCCH or PDSCH and/or their respective DM-RSs. Such an association may exist when the WTRU is configured with a quasi-parity (QCL) hypothesis type D between corresponding antenna ports, at least when the first signal and the second signal are reference signals. Such association may be configured to transmit a configuration indicator (TCI) state. The WTRU may indicate/signal the association between CSI-RS (or SS block) and DM-RS by an index to a set of TCI states (configured by RRC and/or signaled by MAC CE). Such indications may also be referred to as "beam indications".

Configuration and/or activation/deactivation of RS candidates

In various embodiments, RS resources may be used interchangeably with RS, RS resource sets, and/or RS configurations. In various embodiments, receiving an RS may be used interchangeably with transmitting an RS and/or measuring an RS and/or determining an RS quality. In various embodiments, RS presence may be used interchangeably with RS being successfully transmitted/received. In various embodiments, RS absence ("absense" or "non presence") may be used interchangeably with RS not being successfully transmitted/received and RS being blocked, but are consistent with the present invention.

Use of one or more candidate RS resources

In one embodiment, the WTRU may be configured with one or more RS resources and one or more candidate RS resources (e.g., via an RRC message). Based on the LBT operation, it may be determined whether to use one or more RS resources or one or more candidate RS resources for RS transmission. In one example, the WTRU may use LBT and/or identify/determine that an RS exists prior to its RS transmission (e.g., based on the gNB indication and/or WTRU blind detection). Based on the LBT and/or the identity, the WTRU may determine whether a channel for RS transmission is occupied. For example, if the channel is determined to be unoccupied, the WTRU may determine to receive one or more RS resources for RS measurements. If the channel is determined to be occupied, the WTRU may determine to receive one or more candidate RS resources for RS measurements instead of receiving the RS in the one or more RS resources.

In one example, referring to fig. 5, when an LBT failure occurs for one or more RSs, the WTRU may receive (or monitor or detect) an RS transmission in one or more candidate RS resources.

The WTRU may use LBT and/or identify/determine the presence of an RS for one or more candidate RS resources prior to receiving the one or more candidate RS resources for RS measurement. Based on the LBT and/or the identity, the WTRU may determine whether a channel for RS transmission is occupied. For example, if the channel is unoccupied, the WTRU may determine to receive one or more candidate RS resources for RS measurement. The WTRU may wait (e.g., preconfigured) for a duration if the channel is occupied. After waiting (e.g., duration), the WTRU may use LBT and/or identify RS presence for one or more candidate RS resources. The WTRU may determine not to receive one or more candidate RS resources if one or more conditions are met. The determination may be based on meeting one or more conditions (e.g., the number of LBT failures and/or the number of RS presence identification failures being greater than a threshold). The determination may be based on the number of LBT failures and/or the number of RS presence identification failures. For example, if the number of LBT failures (and/or the number of RS presence identification failures) is less than (or equal to) a threshold (e.g., a pre-configured threshold), the WTRU may determine to reuse LBT and/or RS identification. If the number of LBT failures (and/or the number of RS presence identification failures) is greater than a threshold, the WTRU may determine/perform one or more of:

● The WTRU may not use LBT for one or more candidate RS resources;

● The WTRU may not use the identification of RS presence for one or more candidate RS resources;

● The WTRU may not receive one or more candidate RS resources; and/or

● The WTRU may report LBT failure and/or identification failure (e.g., to the gNB).

The threshold values discussed herein may be based on, for example, one or more of the following: 1) A predefined value; 2) Values configured/indicated semi-statically or dynamically by the gNB (e.g., by using one or more of RRC, MAC CE, and/or DCI); and/or 3) WTRU reported values (e.g., by reporting WTRU capabilities).

Configuration/activation and indication of candidate RS resources

In one embodiment, the WTRU may determine to use one or more candidate RS resources based on one or more of: 1) At least one RS resource in the RS resource set fails; 2) If the number of failed RS resources in the RS resource set is greater than a threshold (K); and/or 3) only if all of the RS resources in the RS resource set fail.

In various embodiments, one or more of the following methods/procedures may be used for candidate RS resources with one or more of configuration/activation/indication.

Semi-static configuration of candidate RS resources

In one embodiment, the WTRU may be configured with one or more candidate RS resources via RRC signaling. One or more candidate RS resources may be independently configured. In one example, the first configuration of the one or more candidate RS resources may be independent of the second configuration of the one or more reference RS resources. For example, one or more candidate RS resources may be configured with one or more (or a set of) individual Information Elements (IEs). In this case, the association between one or more RS resources or CSI reporting configurations may be supported based on one or more of the following:

explicit indication. The WTRU may semi-statically and/or dynamically receive an ID (e.g., one or more of RRC, MAC CE, and DCI) of an associated candidate RS resource of the one or more candidate RS resources.

Implicit indication. The WTRU may identify associated candidate RS resources based on the implicit indication. For example, the WTRU may identify/determine the associated candidate RS resources based on one or more of:

● Order of candidate RS resources. In one embodiment, the candidate RS resources may be paired with the RS resources based on the order of the candidate RS resources and the RS resources. For example, a first one of the RS resources may be paired with a first one of the candidate RS resources.

● Slot/symbol offset of candidate RS resources. In one embodiment, the candidate RS resources may be paired with the RS resources based on the candidate RS resources and slot/symbol offsets of the RS resources. For example, if the first offset of the RS resources and the second offset of the candidate RS resources satisfy a given condition (e.g., the same offset, first offset > second offset+x (symbol/slot), first offset < second offset+x (symbol/slot), distance between first offset and second offset < X (symbol/slot), etc.), then the RS resources of the RS resources may be paired with the candidate RS resources of the candidate RS resources.

● Frequency location of candidate RS resources. In one embodiment, the candidate RS resources may be paired with the RS resources based on the candidate RS resources and the frequency locations of the RS resources. For example, if a first frequency resource of an RS resource and a second frequency resource of candidate RS resources satisfy a given condition (e.g., the same frequency resource, first frequency resource > second frequency resource+x (RE/RB), first frequency resource < second frequency resource+x (RE/RB), distance between first frequency resource and second frequency resource < X (RE/RB), etc.), then an RS resource of these RS resources may be paired with a candidate RS resource of these candidate RS resources.

In one embodiment, one or more candidate RS resources may be configured within an RS resource. For example, if one or more candidate RS resources are configured within the first RS resource, the one or more candidate RS resources may be used when LBT for the first RS resource fails.

Activation/deactivation of candidate RS resources

In one embodiment, the WTRU may receive one or more activation messages from the gNB (e.g., via a MAC CE) based on a semi-statically configured set of candidate RS resources. For example, the WTRU may receive one or more activation messages that activate one or more candidate RS resources in the set of candidate RS resources. Based on the one or more activation messages, the WTRU may receive one or more candidate RS resources if the LBT fails for RS transmission.

Dynamic indication of candidate RS resources

In one embodiment, the WTRU may receive one or more indication messages (e.g., via MAC CE and/or DCI) from the gNB based on a semi-static configuration and/or an activated set of candidate RS resources. For example, the WTRU may receive one or more indication messages indicating one or more candidate RS resources in the set of candidate RS resources. Based on the one or more indication messages, the WTRU may receive one or more candidate RS resources if the LBT fails for the RS transmission.

Identical configuration between candidate RS resources and reference RS resources

In one embodiment, the same configuration may be supported/used for one or more RS resources and one or more candidate RS resources. The same configuration may be based on one or more of the following:

bandwidth part (BWP). In one embodiment, the RS resource and the associated candidate RS resource may be configured with the same BWP ID.

Resource type. In one embodiment, the RS resources and associated candidate RS resources may be configured with the same configuration for the resource type. For example, if an RS resource is configured with a first resource type (e.g., aperiodic, semi-persistent, or periodic), then the associated candidate RS resource may be configured with the first resource type (e.g., aperiodic, semi-persistent, or periodic). If the RS resources are configured with a second resource type (e.g., aperiodic, semi-persistent, or periodic), the associated candidate RS resources may be configured with the second resource type (e.g., aperiodic, semi-persistent, or periodic).

And (5) resource mapping. In one embodiment, the RS resources and associated candidate RS resources may be configured with the same resource map.

Power control offset. In one embodiment, the RS resources and associated candidate RS resources may be configured with the same power control offset and/or power control offset SS.

Scrambling the ID. In one embodiment, the RS resources and associated candidate RS resources may be configured with the same scrambling identity.

Periodic and/or offset (e.g., periodic and/or aperiodic triggeringoffset). In one embodiment, the RS resources and associated candidate RS resources may be configured with the same periodicity and/or offset.

The on/off is repeated. In one embodiment, the RS resources and associated candidate RS resources may be configured with the same configuration for repeated on/off. For example, if an RS resource is configured with a repeat on, the associated candidate RS resource may be configured with a repeat on. If the RS resources are configured with repeated shutdown, the associated candidate RS resources may be configured with repeated shutdown.

RS for QCL. In one embodiment, the RS resources and associated candidate RS resources may be configured with the same reference RS (e.g., one or more of CSI-RS, SSB, and SRS) for one or more of the QCL types (e.g., one or more of QCL types A, B, C and D). For example, if the RS resources are configured with a first CSI-RS for QCL type a (e.g., for tracking) and a second CSI-RS for QCL type D, the associated candidate RS resources may be configured with a first CSI-RS for QCL type a and a second CSI-RS for QCL type D.

Number of RS resources. In one embodiment, the number of one or more RS resources and the number of one or more candidate RS resources may be the same.

TRS info. In one embodiment, the RS resources and associated candidate RS resources may be configured with the same configuration for trs-Info. For example, if an RS resource is configured with trs-Info, the associated candidate RS resource may be configured with trs-Info. If the RS resource is configured without trs-Info, the associated candidate RS resource may be configured without trs-Info.

Possible RS types for candidate RS resources

In one embodiment, the WTRU may configure, activate and/or indicate with candidate RS resources and may receive an RS transmission (e.g., a failed RS transmission) based on the candidate RS resources if LBT fails. One or more of the following RSs may be used for candidate RS resources:

● Synchronization signal/physical broadcast channel (SSB/PBCH);

● Channel state information-reference signal (CSI-RS). For example, CSI-RS for one or more of CSI, beam management with repeated on/off, and/or tracking may be used;

● Sounding Reference Signals (SRS). For example, SRS for one or more of codebook-based, non-codebook-based, beam management, and/or antenna switching may be used;

● Positioning Reference Signals (PRS);

● Demodulation reference signal (DM-RS); and/or

● Phase tracking reference signal (PT-RS).

RS candidates based on candidate RS resource sets

In one embodiment, the WTRU may be configured, activated and/or instructed with one or more candidate RS resource sets in addition to the reference RS resource set used for transmission. The candidate RS resource set may be associated with one or more of the reference RS resource sets used for transmission. The WTRU may assume an explicit or implicit mapping between the reference RS resource set and the candidate RS resource set. Thus, in the event that the reference RS resource set transmission is not completed due to LBT failure at the gNB, the WTRU may expect to receive the associated candidate RS in the earliest consecutive RS transmission occasion within the candidate RS resource set configuration.

In one example, the WTRU may be configured with one or more of the following in candidate CSI-RS resource configurations (e.g., CSI-resource config):

● RS downlink BWP (e.g., BWP-Id) for channel measurement, where it may be based on an associated reference RS resource set.

● A list of RS resource sets, e.g., CSI-IM-resource estlist, of references to CSI-IM resources for beam management and reporting.

● The RS resource set ID used in the corresponding RS reporting configuration to refer to the candidate CSI-RS resource set, e.g., CSI-ResourceConfigId.

● A list of RS resource sets, e.g., csi-SSB-resource list, of references to SSB resources for beam management and reporting.

● A list of RS resource sets, e.g., NZP-CSI-RS-resource estlist, for reference to NZP CSI-RS resources for beam management and reporting. And/or

● RS time domain behavior of candidate RS resource set configuration, e.g., resource type.

In another example, the WTRU may be configured with one or more of the following in a candidate RS resource set (e.g., NZP-CSI-RS-resource set):

● RS Resources associated with the RS resource set, e.g., nzp-CSI-RS-Resources.

● An indication of the repeated application, such as repetition.

● An indication of a mapping of antenna ports for the RS resources within the corresponding RS resource set, e.g., trs-Info.

● An offset, e.g., an aperiodic triggeringoffset, between the time slot of the set of aperiodic candidate RS resources and the time slot of the set of transmit candidate RS resources is triggered.

The o offset may be a relative offset based on a set of reference RS resources. For example, if the WTRU is configured with a first offset for a reference RS resource set and a second offset for a candidate RS resource set. The actual offset of the candidate RS resource set may be a function of the first offset and the second offset, e.g., actual offset = first offset + second offset.

In some examples, the WYTRU may assume the same configuration as the reference RS resource set if the WTRU does not receive one or more of the configurations for the candidate RS resource set.

In one embodiment, the WTRU may identify a configuration of a candidate set of RS resources associated with a reference set of RS resources. The configuration and/or indication may be based on one or more of the following:

● Explicit indication.

The WTRU may identify the associated set of candidate RS resources based on the explicit indication. For example, for the RS resource set, the ID of the candidate RS resource set may be configured/activated or indicated by the gNB (e.g., via one or more of RRC, MACCE, and/or DCI). The WTRU may use a candidate RS resource or a candidate set of RS resources if the associated set of RS resources fails. Parameters (e.g., one or more of RRC, MAC CE, and/or DCI) in the candidate RS resource set that are different from the reference RS resource set may be semi-statically and/or dynamically configured. In one example, the antenna ports and/or repeated mappings may be configured in a different set of candidate RS resources than the set of reference RS resources, so they may be explicitly configured. In another example, the offset between the time slot triggering the set of aperiodic candidate RS resource sets and the time slot transmitting the reference RS resource set can be explicitly configured.

● Implicit indication.

The WTRU may identify an associated set of candidate RS resources based on the implicit indication. For example, the WTRU may identify the associated candidate set of RS resources based on one or more of the operations/methods discussed herein. The WTRU may identify the same parameters in the candidate RS resource set based on corresponding parameters in the reference RS resource set. In one example, the RS resources associated with the candidate RS resource set can be implicitly identified based on the RS resources in the corresponding reference RS resource set. In another example, the antenna ports and/or repeated mappings may be configured in the same set of candidate RS resources as the set of reference RS resources, so the WTRU may implicitly identify them. In one example, the WTRU may identify an associated set of candidate RS resources if one or more of the configured parameters in the set of candidate RS resources are the same as one or more configured parameters in the set of reference RS resources. The one or more configured parameters may include any of the following:

■ Repeating on/off;

■ Periodically triggering an offset;

■TRS-info；

■ QCL type and reference RS; and/or

■ The number of configured RS resources for the RS resource set.

In one embodiment, the WTRU may be configured with one or more of the following in the RS resources of the candidate RS Resource set (e.g., NZP-CSI-RS-Resource):

● For defining the number, density, CDM type, OFDM symbol and RS resource mapping occupied by subcarriers, such as resource mapping, of the RS resource ports.

● RS resource power control offset, e.g., powerControlOffset and/or powerControlOffsetSS. The power control offset may be a relative offset based on the reference RS resource. For example, if the WTRU is configured with a first power control offset for reference RS resources and a second power control offset for candidate RS resources. The actual power control offset of the candidate RS resource may be a function of the first offset and the second offset, e.g., actual power control offset = first power control offset + second power control offset.

● RS resources scramble IDs, e.g., scramblingID.

● RS resource periodicity and slot offset, e.g., periodic and semi-persistent CSI-RS resources. The periodicity and/or slot offset may be based on relative values of the reference RS resources. For example, the WTRU may be configured with a first slot offset for reference RS resources and a second slot offset for candidate RS resources. The actual slot offset of the candidate RS resource may be a function of the first slot offset and the second slot offset, e.g., actual slot offset = first slot offset + second slot offset. In another example, the WTRU may be configured with a first periodicity for reference RS resources and a second periodicity for candidate RS resources. The actual periodicity of the candidate RS resources may be a function of the first periodicity and the second periodicity. In one example, the WTRU may receive the configured slot offset without periodicity. In this case, the WTRU may apply the periodicity of the reference RS resources.

● RE resources including the TCI status of the QCL source RS and the corresponding QCL type are indexed, such as QCL-InfoPeriodacCSI-RS.

In some examples, the WTRU may assume the same configuration as the reference RS resources if the WTRU does not receive one or more of the configurations for the candidate RS resources.

In one embodiment, the WTRU may identify a configuration of RS resources of a candidate RS resource set configuration associated with RS resources of a reference RS resource set. The configuration and/or indication may be based on one or more of the following:

● Explicit indication.

The WTRU may identify the associated RS resources in the candidate RS resource set based on the explicit indication. For example, for an RS resource set in the associated RS resource set, the IDs of candidate RS resources of the candidate RS resource set may be configured/activated or indicated by the gNB (e.g., via one or more of RRC, MAC CE, and/or DCI). The WTRU may use the candidate RS resource or the set of candidate RS resources if the associated RS resource or the associated set of RS resources fails. Parameters (e.g., one or more of RRC, MAC CE, and/or DCI) of the RS resources of the candidate RS resource set that are different from the RS resources of the reference RS resource set may be semi-statically and/or dynamically configured. In one example, the resource map in time and frequency can be configured for RS resources in the candidate RS resource set that are different from the RS resources in the reference RS resource set, so they can be explicitly configured. In another example, periodicity and offset of RS resources in the candidate RS resource set can be explicitly configured.

● Implicit indication.

The WTRU may identify the associated RS resources in the candidate RS resource set based on the implicit indication. For example, the WTRU may identify RS resources configured in the candidate set of RS resources based on one or more operations/methods discussed herein. In one example, the WTRU may be based on RS resources in a reference RS resource setIs configured with a QCL source and a TCI state of QCL type for providing RS resources in the candidate RS resource set. Thus, the WTRU may implicitly identify the TCI state of the RS resources in the candidate RS resource set. At the position ofIn another example, the periodicity and offset of the RS resources in the candidate RS resource set may be implicitly and based on a predefined/calculated/determined relative delay from the RS resources in the reference RS resource set. In one example, the WTRU may identify the associated RS resources based on the configured order. For example, a first candidate RS resource of the candidate RS resource set may be associated with a first reference RS resource of the associated reference RS resource set, and a second candidate RS resource of the candidate RS resource set may be associated with a second reference RS resource of the associated reference RS resource set.

RS candidates based on candidate RS resources

In various embodiments, the configurations discussed herein may be used interchangeably with one or more of the following: BWP, resource type, resource mapping, power control offset, scrambling ID, periodicity and/or offset (e.g., periodic and/or aperiodic triggeringoffset), repetition on/off, reference RS for QCL type (e.g., one or more of QCL type A, B, C and/or D), number of RS resources, and/or TRS info.

In one embodiment, the WTRU may be configured, activated and/or instructed with one or more candidate RS resources in addition to the reference RS resource set used for transmission. The candidate RS resources may be associated with one or more of the reference RS resources for transmission. The WTRU may assume an explicit or implicit mapping between the reference RS resource and the candidate RS resource. Thus, in the event that the RS resource transmission is not completed due to LBT failure at the gNB, the WTRU may expect to receive the associated candidate RS resource in the earliest consecutive RS transmission occasion within the candidate RS resource configuration.

In one example, the WTRU may be configured with one or more of the following in candidate RS resources (e.g., NZP-CSI-RS-Resource):

● For defining the number, density, CDM type, OFDM symbol and RS resource mapping occupied by subcarriers, such as resource mapping, of the RS resource ports.

● RS resource power control offset, e.g., powerControlOffset and/or powerControlOffsetSS.

● RS resources scramble IDs, e.g., scramblingID.

● RS resource periodicity and slot offset, e.g., periodic and semi-persistent CSI-RS resources.

● RE resources including the TCI status of the QCL source RS and the corresponding QCL type are indexed, such as QCL-InfoPeriodacCSI-RS.

Candidate RS association

In one embodiment, the WTRU may identify a configuration of candidate RS resources associated with the reference RS resource. The configuration and/or indication may be based on one or more of the following:

● Explicit indication.

The WTRU may identify the associated candidate RS resources based on the explicit indication. Parameters (e.g., one or more of RRC, MAC CE, and/or DCI) of the candidate RS resources that are different from the reference RS resources may be semi-statically and/or dynamically configured. In one example, the resource map in time and frequency can be configured for candidate RS resources that are different from the reference RS resources, so they can be explicitly configured. In another example, periodicity and offset of RS resources in the candidate RS resource set can be explicitly configured.

● Implicit indication.

The WTRU may identify the associated candidate RS resources based on the implicit indication. For example, the WTRU may identify candidate RS resources based on one or more of the operations/methods discussed herein. In one example, the WTRU may be configured with a QCL source and a QCL type of TCI state for providing candidate RS resources based on the TCI state of the reference RS resources. Thus, the WTRU may implicitly identify the TCI state of the candidate RS resource. In another example, the periodicity and offset of the candidate RS resources may be implicitly configured and based on a predefined/calculated/determined relative delay from the reference RS resources.

Dynamic determination of one or more configurations

In one embodiment, the WTRU may not be configured with one or more of the configurations for one or more candidate RS resources associated with multiple RS resources/resource sets. If one or more of the plurality of RS resources/resource sets' associated RS resources fail, the WTRU may apply or assume the same configuration for one or more candidate RS resources and one or more associated RS resources. For example, if the reference RS resource configured with the first configuration fails, the WTRU may receive candidate RS resources with the first configuration.

In one embodiment, a WTRU may be configured with candidate RS resources having multiple configurations for multiple reference RS resources. For example, the WTRU may be configured with candidate RS resources having a first configuration for a first reference RS resource and a second configuration for a second reference RS resource. Based on the failed resources, the WTRU may determine to use the first configuration or the second configuration to receive candidate RS resources. For example, if the first reference RS resource fails, the WTRU may receive candidate RS resources with a first configuration. The WTRU may receive candidate RS resources with a second configuration if the second reference RS resource fails.

In one embodiment, the WTRU may apply the relative configuration of the candidate RSs over the configuration of the reference RS. For example, the relative offset of candidate RS resources may be determined based on one or more operations/methods discussed herein.

In one example, the relative offset of the candidate RS resources can be semi-statically configured. Thus, the actual offset of the candidate RS resource may be calculated/determined based on successive failures of the RS resource transmission. For example, if the WTRU is configured with a first slot offset for reference RS resources and a second slot offset for candidate RS resources. The actual slot offset of the candidate RS resource may be a function of the first slot offset and the second slot offset, e.g., actual slot offset = first slot offset + second slot offset.

In another example, the relative offsets of candidate RS resources can be dynamically configured based on the offset configured for each RS resource. For example, the WTRU may be configured with candidate RS resources having a first relative offset for a first reference RS resource having a first offset and a second relative offset for a second reference RS resource having a second offset. Based on the failed resources, the WTRU may determine to use the first offset/first relative offset or the second offset/second relative offset to receive the candidate RS resources. For example, if the first reference RS resource fails, the WTRU may receive candidate RS resources with an offset determined based on the first offset and the first relative offset (e.g., offset = first offset + first relative offset). If the second reference RS resource fails, the WTRU may receive candidate RS resources having an offset determined based on the second offset and the second relative offset (e.g., offset = second offset + second relative offset).

Dynamic determination based on number of failures

In one embodiment, the WTRU may be configured/indicated with candidate RS resources having multiple configurations for the number of RS/LBT failures. For example, the WTRU may be configured with candidate RS resources having a first configuration and a second configuration. Based on the number of failures, the WTRU may determine to use the first configuration or the second configuration to receive candidate RS resources. For example, if the number of failures is less than (or equal to) M, the WTRU may receive candidate RS resources with a first configuration. If the number of failures is greater than M, the WTRU may receive candidate RS resources with a second configuration. M may be predefined, configured, and/or indicated by the gNB (e.g., based on one or more of RRC, MAC CE, and/or DCI).

Dynamic determination based on reference RS configuration

In one embodiment, the WTRU may be configured/indicated with multiple candidate RS resources for multiple reference RSs. For example, the WTRU may be configured with a first candidate RS resource with/for a first configuration.

In one example, the WTRU may be configured with a second candidate RS resource with/for a second configuration. Based on the failed reference RS resource, the WTRU may determine to use the first candidate RS resource or the second candidate RS resource for measurement. For example, if the failed RS resource is configured/indicated with a first configuration, the WTRU may determine to use a first candidate RS resource with the first configuration. If the failed RS resource is configured/indicated with a second configuration, the WTRU may determine to use a second candidate RS resource with the second configuration.

In another example, the WTRU may be configured with a first candidate RS resource and a second candidate RS resource. Based on the failed reference RS resource, the WTRU may determine to use the first candidate RS resource or the second candidate RS resource for measurement. For example, if the failed RS resources are configured/indicated with a first configuration (e.g., a first number of antenna ports) that is less than (or equal to) a threshold (e.g., 8), the WTRU may determine to use the first candidate RS resources. The WTRU may determine to use a second candidate RS resource if the failed RS resource is configured/indicated with a second configuration (e.g., a second number of antenna ports) that is greater than a threshold (e.g., 8). The threshold may be based on one or more of the following: a predefined value, a value configured/indicated semi-statically or dynamically by the gNB (e.g., by using one or more of RRC, MAC CE, and DCI), and a WTRU reported value (e.g., by WTRU capabilities). Multiple thresholds may be used to determine candidate RS resources of the multiple candidate RS resources.

Prioritization of failed RS resources

In one embodiment, if the number of one or more failed RS resources exceeds N (e.g., the number of candidate RS resources), the WTRU may determine to receive one or more candidate RS resources based on one or more of:

● The RS is not received/transmitted. For example, if the number of one or more failed RS resources exceeds N (e.g., the number of candidate RS resources), the WTRU may not receive one or more candidate RS resources associated with the one or more failed RS resources.

● An RS for a portion of the failed RS resources is received/transmitted (e.g., by selecting a portion of one or more failed RS resources). For example, if the number of one or more failed RS resources exceeds N (e.g., the number of candidate RS resources), the WTRU may receive candidate RS resources for a portion of the one or more failed RS resources. The WTRU (and/or the gNB) may determine a set of failed RS resources of the one or more failed RS resources. The WTRU may determine a set of failed RS resources of the one or more failed RS resources based on one or more of:

RS ID. In one example, failed RS resources with lower or higher RS resource IDs may be determined. For example, if a first RS resource with a first resource ID and a second RS resource with a second resource ID fail, the WTRU may determine the first RS resource based on the first resource ID and receive candidate RS resources for the first RS resource.

RS order. In one example, the first (or last) configured RS resources may be prioritized over other RS resources. For example, if a first RS resource having a first order and a second RS resource having a second order fail, the WTRU may determine the first RS resource based on the first order and receive candidate RS resources for the first RS resource.

Transmission type. In one example, the first transmission type (e.g., periodic and/or semi-persistent) may be prioritized over the second transmission type (e.g., semi-persistent and/or non-periodic). For example, if a first RS resource having a first transmission type and a second RS resource having a second transmission type fail, the WTRU may determine the first RS resource based on the first transmission type and receive candidate RS resources for the first RS resource.

BWP ID, scrambling ID, serving cell ID and/or physical cell ID. In one example, RS resources with lower or higher BWP IDs, scrambling IDs, serving cell IDs, and/or physical cell IDs may be prioritized. For example, if the first RS resource with the first BWPID and the second RS resource with the second BWP ID fail, the WTRU may determine the first RS resource based on the first BWP ID and receive candidate RS resources for the first RS resource.

Port number. In one example, a larger/smaller number of first RS resources with antenna ports may be prioritized over a smaller/larger number of second RS resources with antenna ports. For example, if a first number of first RS resources with antenna ports and a second number of second RS resources with antenna ports (which may be less than the first number of antenna ports) fail, the WTRU may determine the first RS resources based on the first number of antenna ports and receive candidate RS resources for the first RS resources.

Link type. In one example, a first RS resource having a first link type (e.g., DL or UL) may be prioritized over a second RS resource having a second link type (e.g., UL or DL). For example, if a first RS resource having a first link type and a second RS resource having a second link type fail, the WTRU may determine the first RS resource based on the first link type and receive candidate RS resources for the first RS resource.

Time/frequency resources. In one example, a first RS resource with a larger/smaller time/frequency resource may be prioritized over a second RS resource with a smaller/larger number of time/frequency resources.

Periodicity/offset. For example, a first RS resource with a larger/smaller periodicity/offset may be prioritized over a second RS resource with a smaller/larger periodicity/offset.

N may be predefined, configured, and/or indicated by the gNB (e.g., based on one or more of RRC, MAC CE, and/or DCI).

Supplementary cell for RS transmission

In various embodiments, PCell may be used interchangeably with SCell and PScell, but are consistent with this invention.

In one embodiment, the WTRU may be configured, activated, and/or indicated using one or more RS resources in the first frequency resource and one or more candidate RS resources in the second frequency resource. Based on the LBT operation, it may be determined whether to use one or more RS resources or one or more candidate RS resources for RS transmission. In one example, the WTRU may use LBT before its RS transmission. Based on LBT, the WTRU may determine whether a channel for RS transmission is occupied. For example, if the channel is unoccupied, the WTRU may determine to receive one or more RS resources in the first frequency resource. If the channel is occupied, the WTRU may determine to receive one or more candidate RS resources in the second frequency resource instead of receiving the RS in the one or more RS resources. The first frequency resource and the second frequency resource may be one or more of:

Unlicensed bands and licensed bands. In one embodiment, the first frequency resource may be an unlicensed frequency band and the second frequency resource may be a licensed frequency band. For example, if the channel is unoccupied, the WTRU may receive one or more RS resources in an unlicensed frequency band. The WTRU may receive one or more candidate RS resources in the licensed band if the channel is occupied.

Normal links and supplemental links. In one embodiment, the first frequency resource may be a normal link and the second frequency resource may be a supplemental link. For example, if the channel is unoccupied, the WTRU may receive one or more RS resources in the normal link. The WTRU may receive one or more candidate RS resources in the supplemental link if the channel is occupied.

A first cell and a second cell. In one embodiment, the first frequency resource may be a first cell and the second frequency resource may be a second cell. For example, if the channel is unoccupied, the WTRU may receive one or more RS resources in the first cell. The WTRU may receive one or more candidate RS resources in the second cell if the channel is occupied. In some cases, the first cell may be an SCell or a PScell, and the second cell may be a PScell or a PCell. The WTRU may be configured with one or more serving cell IDs and/or one or more physical cell IDs to indicate the first cell and/or the second cell. The configuration or indication may be per WTRU, RS resource set, and/or RS resource. The indication may include one or more of the following:

● Semi-static configuration. For example, the WTRU may be configured with a serving cell ID and/or a physical cell ID (e.g., via RRC) in a configuration of one or more RS resources. Based on the serving cell ID and/or the physical cell ID, the WTRU may receive one or more candidate RS resources in a cell with the serving cell ID and/or the physical cell ID.

● Dynamic indication. For example, the WTRU may be indicated (e.g., via MAC CE and/or DCI) with a serving cell ID and/or physical cell ID for one or more candidate RS resources. Based on the serving cell ID and/or the physical cell ID, the WTRU may receive one or more candidate RS resources in a cell with the serving cell ID and/or the physical cell ID.

A first BWP and a second BWP. In one embodiment, the first frequency resource may be a first cell and the second frequency resource may be a second cell. For example, if the channel is unoccupied, the WTRU may receive one or more RS resources in the first cell. The WTRU may receive one or more candidate RS resources in the second cell if the channel is occupied. The WTRU may be configured with one or more BWP IDs to indicate the first BWP and/or the second BWP. The configuration or indication may be per WTRU, RS resource set, and/or RS resource. The indication may be one or more of the following:

● Semi-static configuration. For example, the WTRU may be configured with a BWP ID (e.g., via RRC) in the configuration of one or more RS resources. Based on the BWP ID, the WTRU may receive one or more candidate RS resources in the BWP with the BWP ID.

● Dynamic indication. For example, the WTRU may be indicated (e.g., via MAC CE and/or DCI) using BWPID for one or more candidate RS resources. Based on BWPID, the WTRU may receive one or more candidate RS resources in BWP with BWP ID.

Adaptation of LBT for RS transmission

In one embodiment, the WTRU and/or the gNB may support (or use, or be configured with) one or more of the following channel access priority levels:

table 1 channel access priority class and related parameters

In one example, as shown in table 1, the channel access priority level may indicate a respective (or different) duration (e.g., a sensing time slot duration) for LBT operation.

In one embodiment, the WTRU and the gNB may support one or more of the following LBT categories for unlicensed band operation. For example, the LBT class may indicate a corresponding (or different) LBT behavior (e.g., LBT with or without random backoff).

● Category 1: transmission immediately after a short switching gap

This class is used for the transmitter to transmit immediately after the switching gap inside the COT.

The switching gap from the reception of the transmission is adapted to the transceiver turn-around time and is not longer than 16 mus.

● Category 2: LBT without random back-off

The duration of time that the channel is sensed as idle before the transmitting entity transmits is deterministic.

● Category 3: LBT with random backoff of contention window of fixed size

The LBT program has the following program as one of its components. The transmitting entity extracts the random number N within the contention window. The size of the contention window is specified by the minimum and maximum values of N. The size of the contention window is fixed. The random number N is used in the LBT procedure to determine the duration of time that the channel is sensed to be idle before the transmitting entity transmits on the channel.

● Category 4: LBT with random backoff of contention window of variable size

The LBT program has the following as one of its components. The transmitting entity extracts the random number N within the contention window. The size of the contention window is specified by the minimum and maximum values of N. The transmitting entity may change the size of the contention window when extracting the random number N. The random number N is used in the LBT procedure to determine the duration of time that the channel is sensed to be idle before the transmitting entity transmits on the channel.

In one embodiment, the WTRU and/or the gNB may apply different channel access priority levels and/or LBT categories to utilize smaller sensing time slot durations and/or smaller contention window sizes based on one or more of the following:

RS type. For example, if the WTRU receives RS transmissions via one or more RS resources, the WTRU may apply a first priority level and/or a first LBT class. The WTRU may apply a second priority level and/or a second LBT class if the WTRU receives RS transmissions via candidate RS resources.

Number of LBT failures. For example, if the WTRU receives RS transmissions without LBT failure or with X LBT failures less than (or equal to) Y, the WTRU may apply the first priority level and/or the first LBT class. If the WTRU receives an RS transmission with X LBT failures greater than Y, the WTRU may apply a second priority level and/or a second LBT class. In one example, only consecutive LBT failures may be used to determine X. In some cases, Y may be based on a predetermined value and/or a value indicated by gNB.

A priority indication. For example, if the WTRU receives an RS transmission with a first priority indication, the WTRU may apply a first priority level and/or a first LBT class. The WTRU may apply a second priority level and/or a second LBT class if the WTRU receives an RS transmission with a second priority indication. In another example, if the WTRU receives one or more PDSCH with a first priority indication, the WTRU may apply a first priority level and/or a first LBT class. The WTRU may apply a second priority level and/or a second LBT class if the WTRU receives one or more PDSCH with a second priority indication.

RS transmission failure indication or identification

In various implementations, an RS instance may refer to an RS in a particular time symbol or set thereof or within a particular time interval.

Presence of RS instances and associated behavior

In one embodiment, the WTRU may use at least one of the solutions described below to determine whether an RS is present in at least one instance or time interval. Upon determining whether an RS is present for at least one instance, the WTRU may use the determination for at least one of:

● RS-based measurements (e.g., CSI, L1-RSRP, L1-SINR, RSRP, RSRQ, SINR);

● Synchronization and tracking (e.g., frequency domain or time domain);

● QCL determination;

● A synchronization or out-of-synchronization determination for radio link monitoring;

● Start or stop a timer and/or update or reset a counter for radio link monitoring; and/or

● Start or stop timers and/or update or reset counters for beam failure recovery and/or contention/non-contention based RACH procedure.

In various embodiments, for any of the above purposes, the WTRU may perform any of the following:

● Only including measurements from RS instances that it determines to exist and excluding RS instances that it determines to not exist;

● Replacing an RS instance determined to be absent with at least one instance of an RS candidate (e.g., as described above);

● Any of the previous measurements on the past RS instances are not considered (e.g., memory is erased) when filtering and/or averaging over multiple RSs is performed;

● Restarting or stopping a timer and/or resetting a counter (e.g., T310, N310) for detecting a radio link problem when synchronization or out-of-sync cannot be detected for an RS instance determined to be absent; and/or

● When the RS instance is determined to be absent, the timer is restarted or stopped and/or a counter for beam failure recovery and/or contention-based/non-contention-based RACH procedure is reset.

RS presence determination based on explicit indication

In one embodiment, the WTRU may determine whether an RS is present based on an explicit indication. The indication may be received from a MAC CE or a UE-specific DCI or a group-common DCI. The indication may include at least one of:

● At least one time interval during which the WTRU should consider the RS to be absent (or present). The time interval may be defined by a start symbol or slot and an end symbol or slot. The start symbol and/or the end symbol may be indicated relative to a timing of a PDCCH carrying DCI containing the indication. Alternatively, the start and/or end symbols may be indicated relative to a time window explicitly included in the signaling.

● At least one frequency interval within which the WTRU should consider the RS to be absent (or present). The frequency interval may be defined by a starting RB, RBG, or subband and an ending RB, RBG, or subband. The starting RB, RBG, or subband and/or ending RB, RBG, or subband may be indicated relative to a frequency location of the PDCCH carrying the DCI containing the indication. Alternatively, the starting and/or ending RBs, RBGs, or subbands may be indicated with respect to frequency resources explicitly included in the signaling.

● Type of RS;

● At least one resource ID;

● At least one resource set ID; and/or

● An RS does not exist (or exists) as a set of instances. For example, a set of instances may be indicated by the number of instances that occur until the time signaling is received (e.g., a starting symbol of a PDCCH carrying DCI containing the indication).

The explicit indication may indicate whether an RS is present for more than one RS. For example, a first value of the explicitly indicated field may indicate that the first RS is present and the second RS is absent, a second value may indicate that the first RS is absent and the second RS is present, and so on. For example, the second RS may be one of the candidate RS resources used by the WTRU when replacing the RS indicated as absent.

RS presence determination based on measurement or implicit indication

In one embodiment, the WTRU may determine whether a first instance of the first RS exists based on at least one measurement. The WTRU may make at least one measurement of at least one of: resources corresponding to a first instance of a first RS, and/or resources corresponding to a second instance of a second RS associated with the first RS.

In one embodiment, the determination based on the measurement of the second RS may enable the network to implicitly signal that the first RS is not transmitted by transmitting the second RS.

In various embodiments, the measurements discussed herein (e.g., RS measurements) may include any of the following: reference Signal Received Power (RSRP) or received quality (RSRQ) for a corresponding RS including L1-RSRP; signal to interference plus noise ratio (SINR), including L1-SINR; and/or a Received Signal Strength Indicator (RSSI).

In various embodiments, the WTRU may determine that the first RS instance is present (or not present) based on at least one of the following conditions: measurements made on resources of the first instance of the first RS are above (or below) a first threshold; and/or the measurement made on the resources of the instance of the second RS is below (or above) the second threshold. In one example, the first threshold and/or the second threshold may be predefined, or configured by higher layers, or a function of another measurement. For example, the first threshold may be a function of the RSSI of the carrier/network entity.

In various embodiments, the association or relationship between the first RS and the second RS may be configured or predefined by higher layers. For example, such configurations may include any of the following:

● The first RS and the second RS may be on the first serving cell and the second serving cell (and/or bandwidth portion), respectively;

● The first RS and the second RS may be scrambled using the first scrambling identity and the second scrambling identity, respectively;

● The first RS and the second RS may be of a first type and a second type, respectively;

● For a given type, the first RS and the second RS may be quasi-co-located with a first reference (or synchronization) signal and a second reference (or synchronization) signal, respectively; and/or

● The time difference between the first RS and the second RS instance may be configured to a certain value or within a range of possible values. For example, if the time of the first RS instance is within a time interval, the first RS instance may be associated with the second RS instance. The time interval may depend on the time T2 of the second RS instance. For example, the time interval may begin at time T2-Td and end at time T2, where Td is a duration that may be predefined or configured for the second RS instance.

In one embodiment, the WTRU may perform RSRP measurements for the second RS scrambled using parameter S2 and received at time T2. If the RSRP measurement of the second RS is above the threshold, the WTRU determines that the first RS is scrambled using a parameter S1 and that any instance of the first RS received at a time T1 (where T1 is between T2-Td and Td) does not exist. The parameters S1, S2 and Td may be configured by higher layers.

Measurement reset indication

In one embodiment, the WTRU may determine to reset WTRU measurements. The reset may be applied to one or more of the following:

CSI measurement. For example, the WTRU may not consider previous RS measurements for CSI before determining the reset.

RRM/RLM measurements. For example, the WTRU may not consider previous RS measurements for RRM/RLM before determining the reset.

Beam failure monitoring. For example, the WTRU may disregard previous RS measurements for beam failure detection and beam failure recovery for new beam selection before determining the reset.

A counter and/or a timer associated with beam failure recovery. For example, the WTRU may reset a counter and/or timer associated with beam failure recovery after determining the reset.

A counter and/or timer associated with a contention-based or non-contention-based RACH procedure. For example, the WTRU may reset a counter and/or timer associated with the contention-based/non-contention-based RACH procedure after determining the reset.

In various implementations, the reset (e.g., a measurement reset) may be based on one or more of the following:

explicit indication from the network entity. For example, the gNB may instruct the WTRU to reset WTRU measurements due to LBT. The indication may be based on one or more of MAC CE and/or DCI. The indication may include one or more of the following:

● One or more of the RS resource/resource set IDs;

● One or more of the CSI reporting configuration IDs; and/or

● One or more of the resource configuration IDs.

The WTRU determines. For example, the WTRU may determine to reset WTRU measurements. The WTRU determination may be based on one or more of the following:

● RS type. For example, the WTRU may not determine the reset if the WTRU receives an RS transmission via one or more RS resources. The WTRU may determine a reset if the WTRU receives an RS transmission via the candidate RS resources; and/or

● RS exists. For example, if the WTRU does not detect the presence of an RS in X resources that are less than (or equal to) Y, the WTRU may not determine a reset. The WTRU may determine a reset if the WTRU does not detect the presence of an RS in X resources that are greater than Y. For example:

only consecutive RS resources can be used to determine X; and/or

The o Y may be based on a predetermined value and/or a value indicated by gNB.

Rate matching for RS candidates of other WTRUs

When a Resource Element (RE) for or configured for a Reference Signal (RS) candidate resource (RSCR) collides with a RE for or scheduled for a downlink (e.g., PDSCH) or uplink transmission (e.g., PUSCH), the RE may be punctured or rate matched for the downlink or uplink transmission. In various embodiments, REs that may be punctured or rate matched may be referred to as muted REs, RE muting, and/or zero power REs.

A set of REs for RE muting of downlink or uplink transmissions may be determined based on one or more of the following, wherein the set of muted REs may be configured based on units of at least one of reference signal resources, REs, resource Blocks (RBs), symbols, OFDM symbols, and/or slots. A set of REs for RE muting may be used interchangeably with RE muting pattern and a set of muted REs.

● Higher layer configuration

A set of REs for RE muting may be configured for a set of time resources. For example, a first set of REs for RE muting may be associated with a first set of time resources (e.g., a first set of time slots) and a second set of REs for RE muting may be associated with a second set of time resources (e.g., a second set of time slots).

● Dynamic indication

One or more groups of mute REs may be configured and one of the groups of mute REs may be indicated in the associated DCI for the PDSCH or PUSCH, wherein each group of mute REs may be associated with an index and the index may be indicated in the associated DCI

■ The index may be explicitly indicated in the DCI

■ The index may implicitly indicate via RNTI that may be used for DCI transmission

● Implicit determination

One or more groups of mute REs may be configured and one of the groups of mute REs may be determined based on a time index, wherein the time index may be at least one of a slot index, an OFDM symbol index, and/or a frame index

A group of mute REs may be configured or determined based on the RSCR configuration. For example, the configured RSCR REs may be determined as mute REs for PDSCH or PUSCH transmissions.

In one embodiment, a set of muted REs may be configured, used, triggered, or determined for PDSCH or PUSCH based on LBT failure (or state of LBT) in an associated slot, symbol, and/or time window. For example, the status of the LBT (e.g., LBT success or LBT failure) of the first slot may determine whether the set of mute REs may be triggered in the second slot. LBT failure may be used interchangeably with DTX, dropped signal, no signal transmission, and zero power signal. One or more of the following may apply:

● The second time slot may be located at a later position than the first time slot, wherein the time slots may be used interchangeably with time opportunities

● The first time slot may include a measurement reference signal (e.g., a periodic RS) and the second time slot may include an associated Reference Signal Candidate Resource (RSCR)

● Periodic measurement signals (e.g., SSB, CSI-RS, TRS) may be configured for measurement, and the WTRU determines LBT failure of the periodic measurement signal at each occasion. If the WTRU determines that LBT of the periodic measurement signal fails at a first time occasion (e.g., symbol or slot), the WTRU may trigger, activate, or use a set of mute REs for signal transmission (e.g., PDSCH or PUSCH) at the associated time occasion

● The WTRU may determine the LBT status (e.g., LBT failure or LBT success) based on one or more of the following:

reception of PDCCH. For example, if the WTRU detects at least one DCI in one time occasion (e.g., symbol or slot), the WTRU may determine "LBT success". Otherwise, the WTRU may determine an "LBT failure" for the time occasion "

■ Common DCI for LBT failure detection may be transmitted at each time occasion, where the common DCI may be monitored in a common search space

Reception of reference signal for example, if the WTRU detects that the energy level of the reference signal is above a threshold at one time occasion, the WTRU may determine that the LBT was successful. Otherwise, the WTRU determines a "LBT failure" for the time occasion, where the reference signal may be a reference signal configured or indicated as being transmitted at the time occasion

■ The threshold may be determined based on a reference signal type (e.g., CSI-RS for CSI feedback or CSI-RS for beam management)

And o. For example, the gNB or WTRU may indicate LTB failure of a time occasion (e.g., a first time occasion) in a later time occasion (e.g., a second time occasion)

■ LBT failure may be explicitly indicated in DCI (e.g., group DCI). For example, a group common PDCCH may be used for the indication

■ LBT failure may be implicitly indicated based on an indication of channel occupancy indication. For example, the WTRU or the gNB may indicate a channel occupancy indication at the beginning of a time slot of a time window occupied by the WTRU or the gNB.

In one embodiment, the WTRU may receive an indication of RE muting pattern for PDSCH reception or PUSCH transmission.

● Indication may be received by the WTRU in the associated DCI for PDSCH and PUSCH scheduling

● The indication may be received by the WTRU in a group common PDCCH that may be received in an associated time slot for PDSCH or PUSCH

The time slot associated may be different from the time slot in which PDSCH may be received or PUSCH may be transmitted.

Multi-QCL type D configuration

In various embodiments, RS reception may be used interchangeably with RS transmission, control channel (e.g., PDCCH, PUCCH, or physical side link control channel (PSCCH)) reception/transmission, and/or shared channel (e.g., PDSCH, PUSCH, or physical side link shared channel (PSSCH)) reception/transmission, but still be consistent with the present invention.

● When transmission of an RS is blocked due to LBT failure, the WTRU may expect to receive the RS on a different spatial beam. For example, the WTRU may expect to receive P-TRS transmissions that are blocked due to LBT failure on a different pre-configured beam.

● The use of different spatial beams may be activated by RRC signaling or MAC CE signaling (e.g., when RS transmissions are blocked due to LBT failure). Alternatively, the spatial beam switching operation may be configured by RRC signaling and/or dynamically indicated by DCI or MAC-CE to activate (considering the possibility of preventing RS transmissions due to LBT failure). In one embodiment, the WTRU may implicitly indicate that use of a different spatial beam for RS transmission is enabled (blocked due to LBT failure) with the beam-based LBT procedure enabled.

● Beam switching for RS reception may be performed by configuring a WTRU with multiple QCL type D source RSs for the desired RS transmission (e.g., by the gNB).

For example, the WTRU may be configured with two QCL types dbs for RS reception, i.e., one primary QCL type dbs and a secondary QCL type dbs. In the event that one or several RS transmission attempts are blocked due to LBT failure, a WTRU or group of WTRUs may expect to receive RSs with different beams identified by the auxiliary QCL type dbrs configured by the WTRU or group of WTRUs.

For example, the WTRU may be configured with two QCL types dbs for RS reception, i.e., one primary QCL type dbs and a secondary QCL type dbs. The WTRU may measure the primary QCL type dbs. Based on the measurements, the WTRU may determine whether to use the primary RS or the secondary RS.

■ For example, if the WTRU measurement is greater than (or equal to) the threshold Z, the WTRU may apply the primary RS as QCL type D reference for RS reception. If the WTRU measurements are less than the threshold Z, the WTRU may apply the secondary RS as a QCL type D reference for RS reception.

■ The measurement may be based on one or more of the following:

●CQI；

● RSRP and/or L1-RSRP;

● SINR and/or L1-SINR;

● RSSI; and/or

●RSRQ。

■ The primary RS may take precedence over the secondary RS. For example, the measured mass X and added value Y may be added for comparison of the primary RS (e.g., if x+y > Z). For the measurement of the secondary RS, the measured mass X 'may be used without Y, or the measured mass X' with a different value Y 'may be used with the same threshold Z or different thresholds Z' (e.g., X '+y' > Z, X '> Z, X' +y '> Z' or X '> Z').

■ The threshold Z and/or Z' may be based on one or more of a predefined value, a value configured/indicated by the gNB, and a value reported by the WTRU (e.g., WTRU capabilities).

● To configure a primary QCL type D RS and a secondary QCL type D RS for RS reception (e.g., RS reception) of a WTRU, the RSs that are expected to be received may be configured with two TCI states. Each TCI state indicates a different RS as QCL type D source or reference RS. For example, two different SSBs may be configured as source RSs in each TCI state. The WTRU may determine whether to use the primary TCI state or the secondary TCI state based on whether the RS is blocked and/or WTRU measurements.

● In one embodiment, the WTRU may expect to receive periodic RSs that are prevented from being transmitted due to LBT failure as aperiodic RS type D QCLed with secondary source RSs. For example, upon detecting that transmission of periodic RSs is blocked due to LBT failure, the WTRU may expect to receive an aperiodic RS type D QCLed with a secondary source RS. The WTRU may determine whether to use the periodic RS or the aperiodic RS based on whether the periodic RS is blocked and/or WTRU measurements of the periodic RS.

● In one embodiment, the WTRU may be configured to receive RSs transmitted at multiple transmission opportunities when RS transmissions are prevented due to LBT failure. A subset of the plurality of transmission opportunities is expected to be type D QCLed with a primary QCL type D source RS, and the remaining transmission opportunities are expected to be type D QCLed with a secondary QCL type D RS.

Receiver assisted LBT type configuration/indication

In one embodiment, the WTRU may be configured/instructed from the gNB to measure interference. The WTRU may report measurement interference back to the gNB prior to the LBT procedure at the gNB. The gNB request may be based on one or more of the following:

● Transmission type

For example, the WTRU may be configured/indicated with one or more of the transmission types for receiver assisted LBT operation. Based on one or more of the configured/indicated transmission types, the WTRU may evaluate the channel and report the channel evaluation to the gNB. One or more of the transmission types may be based on one or more of the following:

■ One or more of the control channels (PDCCH, PUCCH, PSCCH);

■ One or more of the shared channels (PDSCH, PUSCH, PSSCH);

■ RS transmissions (DL RS (possibly including SS/PBCH blocks) and/or UL RS); possibly including one or more RS types; and/or

■ Random Access Channel (PRACH).

● Link type

For example, the WTRU may be configured/indicated with one or more of the link types for receiver assisted LBT operation. Based on one or more of the configured/indicated link types, the WTRU may evaluate the channel and report the channel evaluation to the gNB. One or more of the link types may be based on one or more of the following:

■ Downlink link

■ Uplink channel

■ Side link

● Time and/or frequency resources for receiver assisted LBT

For example, the WTRU may be configured/indicated with one or more of the time and/or frequency resources for receiver assisted LBT operation. Based on the configured/indicated time/frequency resources, the WTRU may evaluate the channel and report the channel evaluation to the gNB. One or more of the time and/or frequency resources may be determined based on one or more of:

■ Explicit indication

● For example, a WTRU may be configured with one or more sets of time/frequency resources. One of the one or more sets of time/frequency resources may be indicated to the WTRU for receiver assisted LBT operation

■ Implicit indication

● The WTRU may be configured with a set of time/frequency resources for each transmission type. For example, based on the configured/indicated transmission types, the WTRU may determine an associated set of time/frequency resources for each transmission type. The association between time/frequency resources and transmission type may be based on one or more of the following:

a set of time/frequency resources may be configured in a channel/signal configuration. For example, a first set of time/frequency resources may be configured in a first channel/signal configuration and a second set of time/frequency resources may be configured in a second channel/signal configuration. The WTRU may use a first set of time/frequency resources if the WTRU receives an indication of a first channel/signal for receiver assisted LBT. If the WTRU receives an indication of a second channel/signal for receiver assisted LBT, the WTRU may use a second set of time/frequency resources

A set of time/frequency resources may be configured as dedicated time/frequency resources for a particular channel/signal configuration. If a particular channel/signal is used for receiver assisted LBT, the set of time/frequency resources may be used

● LBT class

For example, the WTRU may be configured/indicated with one or more of the LBT categories for receiver assisted LBT operation. Based on the configured/indicated LBT class, the WTRU may evaluate the channel and report the channel evaluation to the gNB

● Channel access priority class

For example, the WTRU may be configured/indicated with one or more of the channel access priority classes for receiver assisted LBT operation. Based on the configured/indicated channel access priority level, the WTRU may evaluate the channel and report the channel evaluation to the gNB

Based on the gNB request, the WTRU may report the channel estimation result to the gNB. The WTRU report may be based on one or more of the following:

● Channel estimation results

In one embodiment, the WTRU may report the channel estimation result. For example, the WTRU may report whether the channel is occupied

The WTRU may report one or more channel estimation results for multiple hypotheses of channel estimation. For example, the WTRU may report a first channel estimation result for a first hypothesis and a second channel estimation result for a second hypothesis. The assumption may be based on one or more of the following:

■ A transmission type;

■ A link type;

■ Time and/or frequency resources for receiver assisted LBT;

■ LBT class; and/or

■ Channel access priority class.

● Preferred parameters

In one embodiment, the WTRU may report one or more preferred parameters based on the channel assessment results of the UE. For example, the WTRU may be configured/indicated with multiple parameters for LBT. Based on the one or more parameters, the WTRU may select one or more of the plurality of parameters for transmission based on the channel estimation result of the UE. The parameters may be based on one or more of the following:

■ A transmission type;

■ A link type;

■ Time and/or frequency resources for receiver assisted LBT

■ LBT class

■ Channel access priority class

The WTRU may report the channel estimation result implicitly and/or explicitly. For example, the WTRU may explicitly report the channel estimation results and may indicate (e.g., via reporting) whether one or more channels are idle. Explicit reports may be transmitted using any of PUCCH (or PSCCH), PUSCH (or PSSCH), and/or Physical Random Access Channel (PRACH).

In another example, the WTRU may implicitly report based on one or more of the following:

● CSI reporting

For example, if the channel is idle, the WTRU may report calculated values of CSI parameters, such as one or more of CRI, RI, PMI, PRI and CQI. The WTRU may report a specific value of the CSI parameter if the channel is not idle. For example, the WTRU may report one or more of cri=0, ri=0, pmi=0, pri=0, and/or cqi=0.

■ Based on the CSI report, the WTRU may receive an acknowledgement indication from the gNB (possibly using configured DL resources for acknowledgement). The acknowledgement may be based on one or more of PDCCH, PDSCH, and DL RS transmissions.

● RS transmission

For example, if the channel is idle, the WTRU may transmit an RS in the configured/activated RS resources (possibly configured for channel assessment reporting). The WTRU may not transmit the RS if the channel is not idle.

For example, if the channel is idle, the WTRU may transmit the RS using the first scrambling sequence. The WTRU may transmit the RS using the second scrambling sequence if the channel is not idle.

● PRACH transmission

For example, if the channel is idle, the WTRU may transmit PRACH in the configured/activated PRACH resources (possibly configured for channel assessment reporting). The WTRU may not transmit the PRACH if the channel is not idle.

For example, if the channel is idle, the WTRU may transmit PRACH in the first PRACH resource. The WTRU may transmit PRACH in the second PRACH resource if the channel is not idle.

In one embodiment, a method for candidate RS resource determination for shared spectrum operation may include: the WTRU receives a plurality of reference RS resources and a plurality of candidate RS resources; each candidate RS resource of the plurality of candidate RS resources is associated with a particular number of antenna ports (e.g., 1, 2, 4, or 8 ports) and/or transmission type (e.g., periodic, semi-persistent, or aperiodic). When the plurality of reference RS resources are configured in the unlicensed frequency band, the plurality of candidate RS resources are configured in the licensed frequency band. The WTRU receives a threshold (e.g., CQI, RSRP, RSRQ or SINR) for RS presence determination. The WTRU measures a plurality of reference RS resources and determines an RS presence in the plurality of reference RS resources based on the threshold. If the measured quality of the one or more reference RS resources is less than (or equal to) the threshold, the WTRU determines that the RS transmission of the one or more RS resources fails (e.g., does not exist).

The WTRU determines a candidate RS resource of the plurality of candidate RS resources associated with the one or more reference RS resources based on a number of antenna ports and/or a transmission type of the one or more reference RS resources. If the failed RS resource is configured with the first number of antenna ports and/or the first transmission type, the WTRU determines an associated candidate RS resource having the first number of antenna ports and/or the first transmission type. If the number of the one or more reference RS resources is greater than the number of associated candidate RS resources, the WTRU determines a set of RSs for the one or more reference RS resources based on a resource ID and/or a resource set ID for the one or more reference RS resources.

The WTRU measures RS transmissions based on the determined candidate RS resources. The WTRU uses the beams of the set of RSs to measure the determined candidate RS resources. The determined actual time offset of the candidate RS resources is determined based on the time offset of the set of RSs and the determined relative time offset of the candidate RS resources. For example, actual time offset = time offset #1 (configured for the set of RSs) +time offset #2 (configured for the candidate RSs).

In one embodiment, a method of RS preemption indication by a gNB may include: the WTRU receives a plurality of RS resources with a plurality of RS resource IDs via RRC. The WTRU receives an indication (e.g., via a MAC CE or a group common DCI) with one or more time intervals or one or more of a plurality of RS resource IDs. The WTRU determines one or more of the plurality of RS resources for RS preemption based on one or more time intervals or one or more RS resource IDs. If one or more RS resources are used for radio link monitoring, the WTRU restarts/stops a timer and/or a counter for radio link monitoring. The WTRU may exclude the one or more RS resources.

In one embodiment, a method for rate matching of RS candidates for other WTRUs may include: the WTRU receives multiple RS resources in a first time slot and multiple REs for RE muting in a second time slot via RRC. The WTRU receives one or more CORESET configurations or thresholds for RS presence determination. The WTRU determines the RS presence of the first time slot based on one or more of: if the WTRU does not detect a PDCCH transmission in one or more CORESET configurations, the WTRU determines that the RS fails; if the WTRU measures an RS quality less than (equal to) the threshold, the WTRU determines that the RS failed. Assuming that multiple REs are muted or punctured, the WTRU receives PDSCH in the second slot.

In another embodiment, a method of receiver assisted LBT with LBT type indication may comprise: the WTRU receives multiple sets of LBT configurations based on one or more of a transmission type (e.g., control, shared, or RS transmission), a link type (DL, UL, or SL), time/frequency resources, LBT class, or LBT priority. The WTRU receives a receiver assisted LBT request indicating one or more of the plurality of groups of LBT configurations. The WTRU reports one or more channel assessment results, wherein each channel assessment result is associated with a set of LBT configurations.

QCL hypothesis determination for multiple PDSCH

In various embodiments, QCL hypotheses may be used interchangeably with beams, receiver beams for PDSCH, QCL hypotheses for PDSCH, and TCI states. In addition, timeduration for qcl may refer to the time it takes to process a control channel (e.g., PDCCH) received by a WTRU and configure a receiver according to the indicated beam.

When multiple PDSCH are scheduled by a single DCI (e.g., received in PDCCH), one or a combination of the embodiments described herein may be used in order for the WTRU to determine the received beam for each PDSCH (e.g., QCL hypothesis to be applied to each PDSCH reception). Referring to fig. 6, the application of each embodiment is described with reference to three different cases, which are identified based on the time it takes to process the received control channel and configure the receiver according to the indicated beam (e.g., timeduration for qcl) and the corresponding PDSCH scheduling offset. For example, each of three cases (shown in fig. 6) is determined based on a comparison of PDSCH scheduling offset and timeduration forqcl of the first PDSCH:

● Case 1: the scheduling offset of all PDSCHs is equal to or greater than timeDurationForQCL.

● Case 2: the scheduling offset of all PDSCH < timeduration forqcl.

● Case 3: the scheduling offset of a subset of all scheduled PDSCH < timeduration forqcl.

When the control channel indicates the receiver beam to be used

When the WTRU is instructed on the receiver beam to use, the following procedure may be followed for each case. For example, in release 16 procedure, when the WTRU is configured with higher layer parameters TCI-PresentInDCI set to 'enable' of CORESET for scheduling PDSCH, the WTRU may assume that the TCI field is present in DCI format 1_1 of PDCCH transmitted on CORESET.

● Case 3: scheduling offset of subset of PDSCH < timeduration for single transmission/reception point (TRP) communication.

In one embodiment, the WTRU may follow the following alternatives to update the QCL assumption of the PDSCH between the reception of the first and last scheduled PDSCH. Until the QCL hypothesis update occurs, the WTRU may apply a default QCL hypothesis determined for the first PDSCH based on release 15/16 procedure or the like.

In one embodiment, QCL assumes that the update procedure can be triggered by the end of timeduration forqcl. The WTRU may choose to continue to receive all scheduled PDSCH without updating the QCL assumption or changing the QCL assumption to the beam indicated by the DCI based on one or more of the following configurations:

■ The number of scheduled PDSCH yet to be received. For example, if the number of PDSCHs remaining to be received is higher than a preconfigured value or a value of MCA-CE/DCI indication, the WTRU may change the QCL assumption to a DCI indication beam. Otherwise, the WTRU may continue to use the same default beam applied to the previous PDSCH reception.

■ Total number of PDSCH scheduled.

■ A time gap between the first scheduled PDSCH and the last scheduled PDSCH.

■ The number of PDSCH or duration since the last update of QCL hypothesis.

■ The number of beam switches that a WTRU can perform within a given duration (e.g., within a time slot).

■SCS。

■ Availability of sufficient time slots between scheduled transmissions/receptions.

● In one embodiment, the WTRU may use a Time Domain Resource Allocation (TDRA) configuration to determine the availability of sufficient time slots between scheduled transmissions/receptions.

● In another embodiment, the WTRU may use the symbol level gaps to re-interpret the TDRA configuration to accommodate beam switching. The re-interpretation procedure may be enabled or disabled by higher layer signaling, MAC-CE, or DCI.

In another embodiment, the QCL assumption may be updated at preconfigured/indicated intervals. That is, the WTRU may switch to the QCL hypothesis indicated by the DCI or to a new default QCL hypothesis after a preconfigured/indicated number of slots/OFDM symbols since the last QCL hypothesis update.

■ Switching to a new QCL assumption may be subject to availability of sufficient time slots to perform beam switching or based on RRC signaling, MAC-CE or DCI indication.

■ When the QCL hypothesis change occurs before the timeduration forqcl ends, the WTRU may select the default QCL for the latest PDSCH determined based on the release 15/16 procedure.

■ The WTRU may switch to the TCI state indicated in the DCI when a QCL hypothesis change occurs after the timeduration for QCL ends. In this case, the WTRU may use the new QCL assumption to receive all remaining PDSCH.

In another embodiment, the WTRU may switch to the beam indicated by the gNB or to a new default beam based on the experienced quality of the received signal. For example, the WTRU may measure one or more transmitted RSs and make beam switching decisions based on L1-RSRP and/or L1-SINR. The WTRU may also decide to switch QCL hypotheses based on the BLER of one or more of the scheduled PDSCH that have been received.

If beam switching occurs after timeduration for QCL, the WTRU may switch to the QCL assumption indicated by DCI. In this case, the WTRU may use the new QCL assumption to receive all remaining PDSCH.

If the experienced SINR/channel quality drops below the threshold before the timeDurationForQCL, the WTRU may switch QCL hypotheses based on the default QCL hypothesis of the latest PDSCH.

● Case 3: scheduling offset of subset of PDSCH < timeduration for multi-TRP communication.

In one embodiment, the WTRU may follow one or a combination of the following alternatives to update the QCL assumption of the PDSCH between the reception of the first and last scheduled PDSCH. Until a change in QCL assumption occurs, the WTRU may apply a default QCL assumption determined for the first PDSCH based on release 15/16 procedure or the like. That is, for multiple TRP based on a single DCI, the WTRU may use the TCI state corresponding to the lowest of the TCI code points that contain two different TCI states activated by the MAC-CE. For multi-DCI based multi-TRP, the WTRU assumes that the DM-RS port of PDSCH is QCL with the RS for the QCL parameter for the lowest CORESET index of CORESETs configured with the same coresetpoolndex value.

In one embodiment, QCL assumes that the update procedure can be triggered by the end of timeduration forqcl. The WTRU may choose to continue to receive all scheduled PDSCH without updating the QCL assumption or changing the QCL assumption to the beam indicated by the DCI based on one or more of the following configurations:

■ The number of scheduled PDSCH yet to be received.

■ Total number of PDSCH scheduled.

■ A time gap between the first scheduled PDSCH and the last scheduled PDSCH.

■ The number of PDSCH or duration since the last update of QCL hypothesis.

■ The WTRU may perform the number of beam switches for a given duration (e.g., in a time slot).

■ Subcarrier spacing (SCS).

■ Availability of sufficient time slots between scheduled transmissions/receptions.

● In one embodiment, the WTRU may use the TDRA configuration to determine the availability of sufficient time slots between scheduled transmissions/receptions.

● In another embodiment, the WTRU may use the symbol level gaps to re-interpret the TDRA configuration to accommodate beam switching. The re-interpretation procedure may be enabled or disabled by higher layer signaling, MAC-CE, or DCI.

In another embodiment, the QCL hypothesis for each TRP may be updated at preconfigured/indicated intervals. That is, the WTRU may switch to the indicated QCL hypothesis for each TRP or to a new default QCL hypothesis after a preconfigured or indicated number of slots or OFDM symbols since the last QCL hypothesis update. Switch to the indicated beam or to a new default beam after a preconfigured/indicated number of slots or OFDM symbols since the last QCL hypothesis update.

■ Switching to a new QCL assumption may be subject to availability of sufficient time slots to perform beam switching or based on RRC signaling, MAC-CE or DCI indication.

■ When the QCL hypothesis change occurs before the timeduration forqcl ends, the WTRU may select a default QCL for each TRP based on the following procedure:

● For multi-DCI based multi-TRP, it is contemplated that the WTRU may follow the release 16 default QCL determination procedure for each TRP separately based on the latest PDSCH.

● For a single DCI based multi-TRP, the TCI state corresponds to the next lowest code point containing the two TCI states activated by the MAC-CE (the nth lowest code point containing the two TCI states if this is the nth attempt to change the default QCL assumption).

■ When a QCL hypothesis change occurs after the timeduration forqcl ends, a switch is made to the QCL hypothesis indicated by the TCI state indicated by the DCI for each TRP. In this case, the WTRU may continue to use the new QCL assumption to receive all remaining PDSCH scheduled by the DCI.

In another embodiment, the WTRU may switch to the beam indicated by the gNB or to a new default beam for each TRP based on the experienced quality of the signal received from each TRP. For example, the WTRU may measure one or more transmitted RSs from each TRP and make beam switching decisions based on L1-RSRP and/or L1-SINR. The WTRU may also decide to switch QCL hypotheses based on the BLER of one or more of the scheduled PDSCH that have been received.

If beam switching occurs after timeduration for QCL, the WTRU may switch to the QCL assumption indicated by DCI. In this case, the WTRU may use the new QCL assumption to receive all remaining scheduled PDSCH.

If beam switching occurs after timeduration for QCL, the WTRU may update the QCL assumption for each TRP based on the following procedure:

● For multi-DCI based multi-TRP, it is contemplated that the WTRU may follow the release 16 default QCL determination procedure for each TRP separately based on the latest PDSCH.

● For multi-TRP based on a single DCI, a TCI state corresponding to the next lowest code point containing two TCI states activated by MAC-CE may be applied (the nth lowest code point containing two TCI states if this is the nth attempt to change the default QCL assumption).

When the control channel does not indicate a receiver beam to be used

When the WTRU is not instructed on the receiver beam to use, the following procedure may be followed to determine QCL assumptions for all cases. For example, in release 16 procedure, when there is no TCI-presentlndci field, the WTRU may assume that there is no TCI field in DCI format 1_1 of PDCCH transmitted on CORESET.

● Single TRP transmission

In one embodiment, the WTRU may apply a default QCL assumption based on the monitored CORESET with the lowest ID in the first slot in which PDSCH is scheduled for all PDSCH.

In another embodiment, the WTRU may determine QCL hypotheses at regular intervals based on the monitored CORESET with the lowest ID in the slot carrying the most recently received PDSCH, e.g., after a certain number of OFDM symbols/slots since the last QCL update. Once the QCL hypothesis is updated, the WTRU may apply the new QCL hypothesis to one or more PDSCH received before performing the next QCL hypothesis update. Whether to determine and apply the new QCL assumption to PDSCH reception may be based on one or a combination of the following conditions:

total number of scheduled PDSCH. For example, if the total number of scheduled PDSCH is greater than the indicated/configured number, the WTRU may attempt to update the QCL assumption at regular intervals. Otherwise, the WTRU may continue to use the same QCL assumption.

The duration between the first scheduled PDSCH and the last scheduled PDSCH. For example, if the gap between the first and last PDSCH is below a certain duration, the WTRU may continue to use the same QCL assumption. Otherwise, the WTRU may update the QCL assumption at certain intervals.

WTRU capability in beam switching.

○SCS。

Availability of sufficient time gap between scheduled transmissions/receptions.

In one embodiment, the WTRU may use the TDRA configuration to determine the availability of sufficient time gaps between scheduled transmissions/receptions.

In another embodiment, the WTRU may use the symbol level gaps to re-interpret the TDRA configuration to accommodate beam switching. The re-interpretation procedure may be enabled or disabled by higher layer signaling, MAC-CE, or DCI.

● For multi-TRP transmission

In one embodiment, the WTRU may apply a default QCL assumption for all TRPs based on the monitored CORESET with the lowest ID in the first slot in which PDSCH is scheduled for all PDSCH.

In another embodiment, a new default QCL assumption is determined at regular intervals for each TRP (e.g., after a configured/indicated number of OFDM symbols/slots). This update procedure is repeated until all PDSCH is received. Whether to determine and apply the new QCL assumption to PDSCH reception may be based on the same conditions outlined for the single TRP case.

■ For multi-DCI based multi-TRP, it is contemplated that the WTRU may follow the release 16 default QCL determination procedure for each TRP separately based on the latest PDSCH.

■ For multi-TRP based on a single DCI, a TCI state corresponding to the next lowest code point containing two TCI states activated by MAC-CE may be applied (the nth lowest code point containing two TCI states if this is the nth attempt to change the default QCL assumption).

For cross-carrier scheduling

● For cross-carrier scheduling, when TCI-presentingii is not present, the WTRU may determine a default QCL hypothesis or a single QCL hypothesis based on the monitored CORESET with the lowest TCI state ID.

In one embodiment, the WTRU obtains a default QCL assumption for the first scheduled PDSCH from the active TCI state, with the lowest ID applicable to PDSCH in the active BWP of the scheduled cell.

In another embodiment, if MAC-CE activation occurs during reception of PDSCH, the WTRU may delay MAC-CE activation to keep one default beam for reception of all scheduled PDSCH.

■ Applicable to case 2 and/or case 3.

For unified TCI frame with multiple PDSCH

● For a unified TCI framework with multiple PDSCH, when TCI-presentingii is not present, the WTRU determines a default QCL assumption based on the monitored CORESET with the lowest TCI state ID.

In one embodiment, the WTRU may maintain the default QCL assumption for the first PDSCH for all scheduled PDSCH.

In another embodiment, if MAC-CE activation occurs during reception of PDSCH, the WTRU may delay application of the DCI-based TCI status indication to keep one default beam for reception of all scheduled PDSCH.

■ Applicable to case 2 and/or case 3.

In accordance with the foregoing, the WTRU may determine QCL hypotheses for multiple PDSCH in various ways. For example, the WTRU may apply default QCL hypotheses and/or DCI indicated QCL hypotheses for PDSCH reception. In a particular example, the WTRU may apply a default QCL assumption for multiple PDSCH before reaching timeduration for QCL and apply a DCI indicated QCL assumption for reception of the remaining PDSCH. In addition, the WTRU may update the QCL assumption at regular intervals. In a particular example, when the DCI does not indicate a QCL assumption for PDSCH reception, the WTRU may update the QCL assumption based on a default QCL assumption level. Further, the WTRU may determine QCL hypotheses for cross-carrier scheduling. In a particular example, the WTRU may obtain a default QCL assumption for the first scheduled PDSCH from the active TCI state. Further, the WTRU may determine the QCL assumption using a unified TCI frame with multiple PDSCH. In a particular example, the WTRU may determine a default QCL assumption for the first PDSCH and use it for all PDSCH. Then, when MAC-CE activation occurs during reception of PDSCH, the WTRU may delay application of MAC-CE to maintain one default beam for reception of all scheduled PDSCH.

Dynamic RS resource determination and RS transmission/reception

In one embodiment, a WTRU (e.g., WTRU 102) may be configured to determine or select one or more RS resources (e.g., candidate RS resources) based on, for example, measured quality, transmission type, and/or number of antenna ports. In one example, the WTRU receives configuration information for a set of RS resources, a threshold, and one or more candidate RS resources. Each candidate RS resource is associated with a respective number of antenna ports, a respective transmission type, and/or a respective time offset (e.g., a time offset of a received/measured RS transmission).

Referring to fig. 7, an example of dynamic RS resource determination based on measured quality, transmission type, and/or number of antenna ports is provided. In this example, the WTRU receives and measures a first RS in the RS resources of the set of RS resources (e.g., number of antenna ports = X ports, transmission type = aperiodic RS). The WTRU determines a measurement (measured quality) of the first RS and compares the measurement result (measured quality) to a threshold (e.g., a threshold indicated in the received configuration information). If the WTRU determines that the measured RS quality is met (or not met, or triggered by) under one or more pre-configured conditions (e.g., less than or equal to a threshold), the WTRU may select or determine candidate RS resources based on the number of antenna ports and the transmission type of the first RS and the set of candidate RSs. The WTRU may be configured to receive/measure a second RS in the selected/determined candidate RS resources.

As shown in fig. 7, the WTRU may select (or determine to use) the same number of candidate RS resources with the same transmission type and antenna port of the first received/measured RS. In this example, candidate RS resources with the same number of antenna ports (X ports) and the same transmission type (aperiodic RS or AP-RS) are selected for later (e.g., second or next) RS transmission/reception. In some cases, the candidate RS resources may be configured with (or associated with) a time offset from the time of the first RS transmission (e.g., the first RS is transmitted or received). The WTRU may be configured to receive the second RS in the selected/determined candidate RS resources using the time offset of the determined candidate RS resources. In one example, the WTRU may be configured to use beam information or QCL information (e.g., QCL type D) of the first RS to receive the second RS in the selected/determined candidate RS resources.

In one embodiment, referring to fig. 8, a WTRU (e.g., WTRU 102) may be configured to determine or select one or more RS resources (e.g., candidate RS resources) based on, for example, measured quality, transmission type, and/or number of antenna ports. In the example shown in fig. 8, operations of dynamic RS resource determination and RS transmission are provided. In this example, the WTRU may receive configuration information indicating a set of RS resources, a threshold, and one or more candidate RS resources. Each candidate RS resource may be associated with 1) a respective number of antenna ports, 2) a respective transmission type, and/or 3) a respective time offset. The configuration information may indicate one or more configured purposes. For example, the configured purpose may include any of Channel State Information (CSI) reporting (e.g., with RS transmission type), beam failure recovery, beam management, and/or time/frequency tracking (e.g., fine time/frequency tracking). The CSI report may be a periodic, aperiodic, or semi-periodic CSI report. The RS transmission type may be periodic, aperiodic or semi-periodic.

Still referring to fig. 8, in this example, the WTRU may receive and measure a first RS transmission in a first RS resource (of the configured set of RS resources), and the first RS is associated with a number of antenna ports and a transmission type. In one example, if the measured quality of the first RS is less than (or equal to) a pre-configured threshold (e.g., indicated in the received configuration information), the WTRU may select (or determine) a candidate RS resource from one or more candidate RS resources based on: i) A transmission type; and ii) the number of antenna ports of the first RS (and each of the candidate RS resources). The WTRU may receive a second RS transmission in the selected candidate RS resource using a time offset associated with the selected candidate RS resource. In some cases, the candidate RS resources may be configured with (or associated with) a time offset from the time of the first RS transmission (e.g., the first RS is transmitted or received). The WTRU may receive a second RS transmission in the selected/determined candidate RS resources using the time offset of the candidate RS resources. In one example, the WTRU may receive the second RS transmission in the selected/determined candidate RS resources using beam information or QCL information (e.g., QCL type D) of the first RS transmission. The WTRU may measure the second RS transmission and use the measurement of the second RS transmission for the configured purpose (e.g., CSI reporting). As described above, the received configuration information may indicate at least a configured purpose (e.g., CSI reporting, beam failure recovery, and/or fine time/frequency tracking).

In another example, if the measured quality of the first RS is above (greater than) a pre-configured threshold, the WTRU may determine that the first RS transmission was successfully received (e.g., a successful RS transmission), and the WTRU may use the measurement of the first RS transmission for the configured purposes discussed above (e.g., indicated in the received configuration information).

In one embodiment, a method implemented by a WTRU for wireless communication includes: receiving configuration information indicating a set of RS resources, a set of candidate RS resources, and a threshold; receiving a first reference signal in an RS resource of the set of RS resources; selecting a candidate RS resource from the set of candidate RS resources based on a determination that the measurement of the received first reference signal is less than or equal to the threshold; and receiving a second reference signal in the selected candidate RS resource. Each candidate RS resource of the set of candidate RS resources may be associated with 1) a respective number of antenna ports, 2) a respective transmission type, and/or 3) a respective time offset. The first reference signal is associated with 1) a first number of antenna ports and a first transmission type.

In one example, the candidate RS resources are selected from the set of candidate RS resources based further on: 1) A first number of antenna ports associated with a first reference signal and a first transmission type, and 2) a respective number of antenna ports associated with each candidate RS resource of the set of candidate RS resources and a respective transmission type.

In another example, the candidate RS resources are selected from the set of candidate RS resources based further on: 1) The first number of antenna ports associated with the first reference signal is equal to the second number of antenna ports associated with the candidate RS resource, and 2) the first transmission type associated with the first reference signal is the same as the second transmission type associated with the candidate RS resource.

In one example, the second reference signal is received in the selected candidate RS resource using a time offset associated with the selected candidate RS resource.

In one example, the method further includes determining quasi-parity (QCL) information of the first reference signal, and receiving the second reference signal in the selected candidate RS resources using the QCL information of the first reference signal.

In one example, each candidate RS resource in the set of candidate RS resources is mapped to a respective RS resource in the set of RS resources for transmission.

In one example, the method further includes determining a time offset of the second reference signal based on the candidate RS resources and/or the reference RS resources.

In one example, the configuration information indicates at least the purpose for which the configuration is to be performed. The configured purpose may include any of the following: channel State Information (CSI) reporting, beam failure recovery, beam management, and/or time/frequency tracking.

In one example, the method further comprises measuring a second reference signal; determining that the configured purpose is CSI reporting; and performing CSI reporting using the measurements of the second reference signal.

In one example, the configuration information includes one or more of the following: semi-static configuration of the set of candidate RS resources; activation/deactivation based on DCI and/or MAC CE; a power control offset; scrambling the ID; periodicity; repeating the on/off indication; RS for QCL types a and D; and/or different time offsets.

In one embodiment, a method implemented by a WTRU for wireless communication includes: receiving configuration information indicating a set of RS resources and a set of candidate RS resources; determining LBT failure for one or more RSs associated with the set of RS resources; determining one or more candidate RS resources from the set of candidate RS resources based on the configuration information and the determined LBT failure; and receiving an RS transmission using the determined one or more candidate RS resources. In one example, the configuration information includes one or more of the following: semi-static configuration of the set of candidate RS resources; activation/deactivation based on DCI and/or MAC CE; a power control offset; scrambling the ID; periodicity; repeating the on/off indication; RS for QCL types a and D; and/or different offsets.

In one example, the method may include determining a transmission time or time offset associated with an RS transmission based on the determined LBT failure for one or more RSs. In another example, the method may include determining a quasi-parity (QCL) hypothesis for a plurality of Physical Downlink Shared Channels (PDSCH) by any one of: applying a default QCL hypothesis and a Downlink Control Information (DCI) indicated QCL hypothesis to PDSCH reception; updating the QCL hypothesis at regular intervals; determining QCL hypotheses for cross-carrier scheduling; and/or when multiple PDSCH are scheduled over a single Physical Downlink Control Channel (PDCCH) or one PDCCH per transmission/reception point (TRP), determining QCL hypotheses with a unified Transmission Configuration Indicator (TCI) framework.

Conclusion(s)

Although features and elements are provided above in particular combinations, one of ordinary skill in the art will understand that each feature or element can be used alone or in any combination with other features and elements. The present disclosure is not limited to the specific embodiments described in this patent application, which are intended as illustrations of various aspects. Many modifications and variations may be made without departing from the spirit and scope of the invention, as will be apparent to those skilled in the art. No element, act, or instruction used in the description of the present application should be construed as critical or essential to the invention unless explicitly described as such. Functionally equivalent methods and apparatus, other than those enumerated herein, which are within the scope of the present disclosure, will be apparent to those skilled in the art from the foregoing description. Such modifications and variations are intended to fall within the scope of the appended claims. The present disclosure is to be limited only by the terms of the appended claims, along with the full scope of equivalents to which such claims are entitled. It should be understood that the present disclosure is not limited to a particular method or system.

For simplicity, the foregoing embodiments are discussed with respect to the terminology and structure of infrared-capable devices (i.e., infrared emitters and receivers). However, the embodiments discussed are not limited to these systems, but may be applied to other systems using other forms of electromagnetic waves or non-electromagnetic waves (such as acoustic waves).

It is also to be understood that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting. As used herein, the term "video" or the term "image" may mean any of a snapshot, a single image, and/or multiple images that are displayed on a temporal basis. As another example, as referred to herein, the term "user equipment" and its abbreviation "UE", the term "remote" and/or the term "head mounted display" or its abbreviation "HMD" may mean or include (i) a wireless transmit and/or receive unit (WTRU); (ii) Any of a number of embodiments of the WTRU; (iii) Devices with wireless capabilities and/or with wired capabilities (e.g., tethered) are configured with some or all of the structure and functionality of a WTRU, in particular; (iii) Wireless capability and/or wireline capability devices configured with less than the full structure and functionality of the WTRU; or (iv) etc. Details of an exemplary WTRU, which may represent any of the WTRUs described herein, are provided herein with reference to fig. 1A-1D. As another example, various disclosed embodiments herein are described above and below as utilizing a head mounted display. Those skilled in the art will recognize that devices other than head mounted displays may be utilized and that some or all of the present disclosure and various disclosed embodiments may be modified accordingly without undue experimentation. Examples of such other devices may include drones or other devices configured to stream information to provide an adapted real-world experience.

Additionally, the methods provided herein may be implemented in a computer program, software, or firmware incorporated in a computer readable medium for execution by a computer or processor. Examples of computer readable media include electronic signals (transmitted over a wired or wireless connection) and computer readable storage media. Examples of computer readable storage media include, but are not limited to, read-only memory (ROM), random-access memory (RAM), registers, cache memory, semiconductor memory devices, magnetic media (such as internal hard disks and removable disks), magneto-optical media, and optical media (such as CD-ROM disks and Digital Versatile Disks (DVDs)). A processor associated with the software may be used to implement a radio frequency transceiver for a WTRU, UE, terminal, base station, RNC, or any host computer.

Variations of the methods, apparatus, and systems provided above are possible without departing from the scope of the invention. In view of the various embodiments that may be employed, it should be understood that the illustrated embodiments are examples only and should not be taken as limiting the scope of the following claims. For example, embodiments provided herein include a handheld device that may include or be used with any suitable voltage source (such as a battery or the like) that provides any suitable voltage.

Furthermore, in the embodiments provided above, processing platforms, computing systems, controllers, and other devices including processors are indicated. These devices may include at least one central processing unit ("CPU") and memory. References to actions and symbolic representations of operations or instructions may be performed by various CPUs and memories in accordance with practices of persons skilled in the art of computer programming. Such acts and operations, or instructions, may be considered to be "executing," computer-executed, "or" CPU-executed.

Those of ordinary skill in the art will appreciate that the acts and symbolically represented operations or instructions include the manipulation of electrical signals by the CPU. The electrical system represents data bits that may result in a final transformation of the electrical signal or a reduction of the electrical signal and a retention of the data bits at memory locations in the memory system, thereby reconfiguring or otherwise altering the operation of the CPU and performing other processing of the signal. The memory location holding the data bit is a physical location having a particular electrical, magnetic, optical, or organic attribute corresponding to or representing the data bit. It should be understood that embodiments are not limited to the above-described platforms or CPUs, and that other platforms and CPUs may also support the provided methods.

The data bits may also be maintained on computer readable media including magnetic disks, optical disks, and any other volatile (e.g., random access memory ("RAM")) or non-volatile (e.g., read only memory ("ROM")) mass storage system readable by the CPU. The computer readable media may comprise cooperating or interconnected computer readable media that reside exclusively on the processing system or are distributed among a plurality of interconnected processing systems, which may be local or remote relative to the processing system. It should be understood that embodiments are not limited to the above-described memories, and that other platforms and memories may support the provided methods.

In an exemplary embodiment, any of the operations, processes, etc. described herein may be implemented as computer readable instructions stored on a computer readable medium. The computer readable instructions may be executed by a processor of the mobile unit, the network element, and/or any other computing device.

There is little distinction between hardware implementations and software implementations of aspects of the system. The use of hardware or software is often (but not always, as in some contexts the choice between hardware and software may become important) a design choice representing a tradeoff between cost and efficiency. There may be various media (e.g., hardware, software, and/or firmware) that may implement the processes and/or systems and/or other techniques described herein, and the preferred media may vary with the context in which the processes and/or systems and/or other techniques are deployed. For example, if the implementer determines that speed and accuracy are paramount, the implementer may opt for a medium of mainly hardware and/or firmware. If flexibility is paramount, the implementer may opt for a particular implementation of mainly software. Alternatively, the implementer may opt for some combination of hardware, software, and/or firmware.

The foregoing detailed description has set forth various embodiments of the devices and/or processes via the use of block diagrams, flowcharts, and/or examples. Where such block diagrams, flowcharts, and/or examples contain one or more functions and/or operations, it will be understood by those skilled in the art that each function and/or operation within such block diagrams, flowcharts, or examples can be implemented, individually and/or collectively, by a wide range of hardware, software, firmware, or virtually any combination thereof. In an embodiment, portions of the subject matter described herein may be implemented via an Application Specific Integrated Circuit (ASIC), a Field Programmable Gate Array (FPGA), a Digital Signal Processor (DSP), and/or other integrated format. However, those skilled in the art will recognize that some aspects of the embodiments disclosed herein, in whole or in part, can be equivalently implemented in integrated circuits, as one or more computer programs running on one or more computers (e.g., as one or more programs running on one or more computer systems), as one or more programs running on one or more processors (e.g., as one or more programs running on one or more microprocessors), as firmware, or as virtually any combination thereof, and that designing the circuitry and/or writing the code for the software and/or firmware would be well within the skill of one of skill in the art in light of this disclosure. In addition, those skilled in the art will appreciate that the mechanisms of the subject matter described herein are capable of being distributed as a program product in a variety of forms, and that an illustrative embodiment of the subject matter described herein applies regardless of the particular type of signal bearing media used to actually carry out the distribution. Examples of signal bearing media include, but are not limited to, the following: recordable type media (such as floppy disks, hard disk drives, CDs, DVDs, digital tapes, computer memory, etc.); and transmission type media such as digital and/or analog communications media (e.g., fiber optic cable, waveguide, wired communications link, wireless communications link, etc.).

Those skilled in the art will recognize that it is common in the art to describe devices and/or processes in the manner set forth herein, and thereafter use engineering practices to integrate such described devices and/or processes into data processing systems. That is, at least a portion of the devices and/or processes described herein may be integrated into a data processing system via a reasonable amount of experimentation. Those skilled in the art will recognize that a typical data processing system may generally include one or more of the following: a system unit housing; a video display device; memories such as volatile memories and nonvolatile memories; a processor, such as a microprocessor and a digital signal processor; computing entities such as operating systems, drivers, graphical user interfaces, and applications; one or more interactive devices, such as a touch pad or screen; and/or a control system comprising a feedback loop and a control motor (e.g. feedback for sensing position and/or speed, a control motor for moving and/or adjusting components and/or amounts). Typical data processing systems may be implemented using any suitable commercially available components, such as those typically found in data computing/communication and/or network computing/communication systems.

The subject matter described herein sometimes illustrates different components contained within, or connected with, different other components. It is to be understood that such depicted architectures are merely examples, and that in fact many other architectures can be implemented which achieve the same functionality. In a conceptual sense, any arrangement of components to achieve the same functionality is effectively "associated" such that the desired functionality is achieved. Thus, any two components herein combined to achieve a particular functionality can be seen as "associated with" each other such that the desired functionality is achieved, irrespective of architectures or intermedial components. Likewise, any two components so associated can also be viewed as being "operably connected," or "operably coupled," to each other to achieve the desired functionality, and any two components capable of being so associated can also be viewed as being "operably couplable," to each other to achieve the desired functionality. Specific examples of operably couplable include, but are not limited to, physically mateable and/or physically interactable components and/or wirelessly interactable components and/or logically interactable components.

With respect to substantially any plural and/or singular terms used herein, those having skill in the art can translate from the plural to the singular and/or from the singular to the plural as is appropriate to the context and/or application. For clarity, various singular/plural permutations may be explicitly listed herein.

It will be understood by those within the art that, in general, terms used herein, and especially in the appended claims (e.g., bodies of the appended claims) are generally intended as "open" terms (e.g., the term "including" should be interpreted as "including but not limited to," the term "having" should be interpreted as "having at least," the term "comprising" should be interpreted as "including but not limited to," etc.). It will be further understood by those with skill in the art that if a specific number of an introduced claim recitation is intended, such intent will be explicitly recited in the claim, and in the absence of such recitation no such intent is present. For example, where only one item is contemplated, the term "single" or similar language may be used. To facilitate understanding, the following appended claims and/or the description herein may contain usage of the introductory phrases "at least one" and "one or more" to introduce claim recitations. However, the use of such phrases should not be construed to imply that the introduction of a claim recitation object by the indefinite articles "a" or "an" limits any particular claim containing such introduced claim recitation object to embodiments containing only one such recitation object. Even when the same claim includes the introductory phrases "one or more" or "at least one" and indefinite articles such as "a" or "an" (e.g., "a" and/or "an" should be interpreted to mean "at least one" or "one or more"). The same holds true for the use of definite articles used to introduce claim recitations. In addition, even if a specific number of an introduced claim recitation is explicitly recited, those skilled in the art will recognize that such recitation should be interpreted to mean at least the recited number (e.g., the bare recitation of "two recitations," without other modifiers, means at least two recitations, or two or more recitations). In addition, in those instances where a convention analogous to "at least one of A, B and C, etc." is used, in general such a construction has the meaning that one having skill in the art would understand the convention (e.g., "a system having at least one of A, B and C" would include but not be limited to systems that have a alone, B alone, C alone, a and B together, a and C together, B and C together, and/or A, B and C together, etc.). In those instances where a convention analogous to "at least one of A, B or C, etc." is used, in general such a construction has the meaning that one having skill in the art would understand the convention (e.g., "a system having at least one of A, B or C" would include but not be limited to systems having a alone, B alone, C alone, a and B together, a and C together, B and C together, and/or A, B and C together, etc.). It should also be understood by those within the art that virtually any separate word and/or phrase presenting two or more alternative terms, whether in the specification, claims, or drawings, should be understood to contemplate the possibilities of including one of the terms, either of the terms, or both terms. For example, the phrase "a or B" will be understood to include the possibilities of "a" or "B" or "a and B". In addition, as used herein, the term "…" followed by listing a plurality of items and/or a plurality of item categories is intended to include items and/or item categories "any one of", "any combination of", "any multiple of" and/or any combination of multiples of "alone or in combination with other items and/or other item categories. Furthermore, as used herein, the term "group" is intended to include any number of items, including zero. Furthermore, as used herein, the term "number" is intended to include any number, including zero. Also, as used herein, the term "multiple" is intended to be synonymous with "multiple".

Additionally, where features or aspects of the disclosure are described in terms of markush groups, those skilled in the art will recognize thereby that the disclosure is also described in terms of any individual member or subgroup of members of the markush group.

As will be understood by those skilled in the art, for any and all purposes (such as in terms of providing a written description), all ranges disclosed herein also encompass any and all possible sub-ranges and combinations of sub-ranges thereof. Any listed range can be readily identified as sufficiently descriptive and so that the same range can be divided into at least equal halves, thirds, quarters, fifths, tenths, etc. As a non-limiting example, each range discussed herein can be readily divided into a lower third, a middle third, an upper third, and the like. As will also be understood by those skilled in the art, all language such as "up to", "at least", "greater than", "less than", etc., include the recited numbers and refer to ranges that may be subsequently divided into sub-ranges as described above. Finally, as will be understood by those skilled in the art, the scope includes each individual number. Thus, for example, a group having 1 to 3 units refers to a group having 1, 2, or 3 units. Similarly, a group having 1 to 5 units refers to a group having 1, 2, 3, 4, or 5 units, or the like.

Furthermore, the claims should not be read as limited to the order or elements provided, unless stated to that effect. In addition, use of the term "means for …" in any claim is intended to invoke 25U.S. C. ≡112,6 or device plus function claims format, and any claims without the term "device for …" are not intended to be so. />

Claims (20)

1. A method implemented by a wireless transmit/receive unit (WTRU) for wireless communication, the method comprising:

receiving configuration information indicating a set of Reference Signal (RS) resources, a set of candidate RS resources, and a threshold;

receiving a first reference signal in an RS resource of the set of RS resources;

selecting a candidate RS resource from the set of candidate RS resources based on a determination that the measurement of the received first reference signal is less than or equal to the threshold; and

a second reference signal is received in the selected candidate RS resource.

2. The method of claim 1, wherein each candidate RS resource of the set of candidate RS resources is associated with 1) a respective number of antenna ports, 2) a respective transmission type, and/or 3) a respective time offset.

3. The method of claim 1, wherein the first reference signal is associated with 1) a first number of antenna ports and a first transmission type.

4. The method of claim 1, wherein the candidate RS resources are selected from the set of candidate RS resources based further on: 1) A first number of antenna ports and a first transmission type associated with the first reference signal, and 2) a respective number of antenna ports and a respective transmission type associated with each candidate RS resource of the set of candidate RS resources.

5. The method of claim 1, wherein the candidate RS resources are selected from the set of candidate RS resources based further on: 1) A first number of antenna ports associated with the first reference signal is equal to a second number of antenna ports associated with the candidate RS resource, and 2) a first transmission type associated with the first reference signal is the same as a second transmission type associated with the candidate RS resource.

6. The method of claim 1, wherein the second reference signal is received in the selected candidate RS resources using the time offset associated with the selected candidate RS resources.

7. The method of claim 1, further comprising determining quasi-parity (QCL) information for the first reference signal.

8. The method of claim 7, wherein the second reference signal is received in the selected candidate RS resources using the QCL information of the first reference signal.

9. The method of claim 1, wherein each candidate RS resource in the set of candidate RS resources is mapped to a respective RS resource in the set of RS resources for transmission.

10. The method of claim 1, further comprising determining a time offset of the second reference signal based on the candidate RS resources and/or reference RS resources.

11. The method of claim 1, wherein the configuration information indicates at least a configured purpose.

12. The method of claim 11, wherein the configured purpose comprises any one of: channel State Information (CSI) reporting, beam failure recovery, beam management, and/or time/frequency tracking.

13. The method of claim 11, the method further comprising:

measuring the second reference signal;

determining that the configured purpose is Channel State Information (CSI) reporting; and

CSI reporting is performed using the measurements of the second reference signal.

14. The method of any of claims 1 to 13, wherein the configuration information comprises any of: semi-static configuration of the set of candidate RS resources; activation/deactivation based on DCI and/or MAC CE; a power control offset; scrambling the ID; periodicity; repeating the on/off indication; RS for QCL types a and D; and/or different offsets.

15. A method implemented by a wireless transmit/receive unit (WTRU) for wireless communication, the method comprising:

receiving configuration information indicating a set of Reference Signal (RS) resources and a set of candidate RS resources;

determining a Listen Before Talk (LBT) failure for one or more RSs associated with the set of RS resources;

determining one or more candidate RS resources from the set of candidate RS resources based on the configuration information and the determined LBT failure; and

the RS transmission is received using the determined one or more candidate RS resources.

16. The method of claim 15, wherein the configuration information comprises any one of: semi-static configuration of the set of candidate RS resources; activation/deactivation based on DCI and/or MAC CE; a power control offset; scrambling the ID; periodicity; repeating the on/off indication; RS for QCL types a and D; and/or different offsets.

17. The method of any of claims 1-16, further comprising determining a transmission time or time offset associated with the RS transmission based on the determined LBT failure for the one or more RSs.

18. The method of any of claims 1-17, further comprising determining a quasi-parity (QCL) hypothesis for a plurality of Physical Downlink Shared Channels (PDSCH) by any of: applying a default QCL hypothesis and a Downlink Control Information (DCI) indicated QCL hypothesis to PDSCH reception; updating the QCL hypothesis at regular intervals; determining QCL hypotheses for cross-carrier scheduling; and/or when multiple PDSCH are scheduled over a single Physical Downlink Control Channel (PDCCH) or one PDCCH per transmission/reception point (TRP), determining QCL hypotheses with a unified Transmission Configuration Indicator (TCI) framework.

19. A wireless transmit/receive unit (WTRU) comprising a processor, a receiver, a transmitter, and a memory that implement the method of any of claims 1-18.

20. An apparatus comprising circuitry including a transmitter, a receiver, a processor, and a memory, the apparatus configured to implement the method of any one of claims 1-18 for wireless communication.