WO2022147810A1

WO2022147810A1 - Ue triggered repeated (re) transmission of msg3 pusch

Info

Publication number: WO2022147810A1
Application number: PCT/CN2021/070992
Authority: WO
Inventors: Jing Dai; Chao Wei; Jing LEI
Original assignee: Qualcomm Incorporated
Priority date: 2021-01-09
Filing date: 2021-01-09
Publication date: 2022-07-14

Abstract

Systems and method for providing support for indicating a request for coverage enhancement are disclosed. In embodiments, a UE indicates a request for coverage enhancement to a base station. The base station, in response to receiving the indication, applies coverage enhancement to subsequent communications between the UE and the base station. Indicating the request for coverage enhancement may include transmitting a physical random access channel (PRACH) message in a portion of a set of frequency domain resources granted to the UE for the transmission of the PRACH message, transmitting a demodulation reference signal in a first set of resource elements different than the standard set of resource elements, transmitting the DMRS using a first set of cyclic shifts different than the standard set of cyclic shifts, and/or scheduling and/or transmitting a sounding reference signal (SRS) as a substitute for the PRACH message.

Description

UE TRIGGERED REPEATED (RE) TRANSMISSION OF MSG3 PUSCH

BACKGROUND Field

Aspects of the present disclosure relate generally to wireless communication systems, and more particularly, to indications of a request for coverage enhancement.

Background

Wireless communication networks are widely deployed to provide various communication services such as voice, video, packet data, messaging, broadcast, and the like. These wireless networks may be multiple-access networks capable of supporting multiple users by sharing the available network resources. Such networks, which are usually multiple access networks, support communications for multiple users by sharing the available network resources. One example of such a network is the Universal Terrestrial Radio Access Network (UTRAN) . The UTRAN is the radio access network (RAN) defined as a part of the Universal Mobile Telecommunications System (UMTS) , a third generation (3G) mobile phone technology supported by the 3rd Generation Partnership Project (3GPP) . Examples of multiple-access network formats include Code Division Multiple Access (CDMA) networks, Time Division Multiple Access (TDMA) networks, Frequency Division Multiple Access (FDMA) networks, Orthogonal FDMA (OFDMA) networks, and Single-Carrier FDMA (SC-FDMA) networks.

A wireless communication network may include a number of base stations or node Bs that can support communication for a number of user equipments (UEs) . A UE may communicate with a base station via downlink and uplink. The downlink (or forward link) refers to the communication link from the base station to the UE, and the uplink (or reverse link) refers to the communication link from the UE to the base station.

A base station may transmit data and control information on the downlink to a UE and/or may receive data and control information on the uplink from the UE. On the downlink, a transmission from the base station may encounter interference due to transmissions from neighbor base stations or from other wireless radio frequency (RF) transmitters. On the uplink, a transmission from the UE may encounter interference from uplink transmissions of other UEs communicating with the neighbor base stations or from other wireless RF transmitters. This interference may degrade performance on both the downlink and uplink.

As the demand for mobile broadband access continues to increase, the possibilities of interference and congested networks grows with more UEs accessing the long-range wireless communication networks and more short-range wireless systems being deployed in communities. Research and development continue to advance wireless technologies not only to meet the growing demand for mobile broadband access, but to advance and enhance the user experience with mobile communications.

SUMMARY

The following summarizes some aspects of the present disclosure to provide a basic understanding of the discussed technology. This summary is not an extensive overview of all contemplated features of the disclosure and is intended neither to identify key or critical elements of all aspects of the disclosure nor to delineate the scope of any or all aspects of the disclosure. Its sole purpose is to present some concepts of one or more aspects of the disclosure in summary form as a prelude to the more detailed description that is presented later.

In one aspect of the disclosure, a method of wireless communication includes determining, by a user equipment (UE) , to indicate a request for coverage enhancement to a base station, generating an indication of the request for coverage enhancement, and sending the indication of the request for coverage enhancement to the base station.

In an additional aspect of the disclosure a method of wireless communication includes receiving, by a base station from a UE, an indication of a request for coverage enhancement, applying coverage enhancement, in response to receiving the indication of the request for coverage enhancement, to at least one data transmission to the UE, and transmitting the enhanced at least one data transmission to the UE.

In an additional aspect of the disclosure, an apparatus configured for wireless communication includes means for determining, by a UE, to indicate a request for coverage enhancement to a base station, means for generating an indication of the request for coverage enhancement, and means for sending the indication of the request for coverage enhancement to the base station.

In an additional aspect of the disclosure, an apparatus configured for wireless communication includes means for receiving, by a base station from a UE, an indication of a request for coverage enhancement, means for applying coverage enhancement, in response to receiving the indication of the request for coverage enhancement, to at least one data transmission to the UE, and means for transmitting the enhanced at least one data transmission to the UE.

In an additional aspect of the disclosure, a non-transitory computer-readable medium having program code recorded thereon. The program code includes code to determine, by a UE, to indicate a request for coverage enhancement to a base station, to generate an indication of the request for coverage enhancement, and to send the indication of the request for coverage enhancement to the base station.

In an additional aspect of the disclosure, a non-transitory computer-readable medium having program code recorded thereon. The program code includes code to receive, by a base station from a UE, an indication of a request for coverage enhancement, to apply coverage enhancement, in response to receiving the indication of the request for coverage enhancement, to at least one data transmission to the UE, and to transmit the enhanced at least one data transmission to the UE.

In an additional aspect of the disclosure, an apparatus configured for wireless communication is disclosed. The apparatus includes at least one processor, and a memory coupled to the processor. The processor is configured to determine, by a UE, to indicate a request for coverage enhancement to a base station, to generate an indication of the request for coverage enhancement, and to send the indication of the request for coverage enhancement to the base station.

In an additional aspect of the disclosure, an apparatus configured for wireless communication is disclosed. The apparatus includes at least one processor, and a memory coupled to the processor. The processor is configured to receive, by a base station from a UE, an indication of a request for coverage enhancement, to apply coverage enhancement, in response to receiving the indication of the request for coverage enhancement, to at least one data transmission to the UE, and to transmit the enhanced at least one data transmission to the UE.

The foregoing has outlined rather broadly the features and technical advantages of examples according to the disclosure in order that the detailed description that follows may be better understood. Additional features and advantages will be described hereinafter. The conception and specific examples disclosed may be readily utilized as a basis for modifying or designing other structures for carrying out the same purposes of the present disclosure. Such equivalent constructions do not depart from the scope of the appended claims. Characteristics of the concepts disclosed herein, both their organization and method of operation, together with associated advantages will be better understood from the following description when considered in connection with the accompanying figures. Each of the figures is provided for the purpose of illustration and description, and not as a definition of the limits of the claims.

BRIEF DESCRIPTION OF THE DRAWINGS

A further understanding of the nature and advantages of the present disclosure may be realized by reference to the following drawings. In the appended figures, similar components or features may have the same reference label. Further, various components of the same type may be distinguished by following the reference label by a dash and a second label that distinguishes among the similar components. If just the first reference label is used in the specification, the description is applicable to any one of the similar components having the same first reference label irrespective of the second reference label.

FIG. 1 is a block diagram illustrating details of a wireless communication system.

FIG. 2 is a block diagram illustrating a design of a base station and a UE configured according to one aspect of the present disclosure.

FIG. 3 is a block diagram of an example wireless communications system that supports indication of a request for coverage enhancement from a user equipment to a base station according to one or more aspects of the present disclosure.

FIGS. 4A-4C are diagrams illustrating example operations for indicating a request for coverage enhancement by transmission of a message in a portion of a set of frequency domain resources granted to a UE for transmission of the message according to one or more aspects of the present disclosure.

FIGS. 5A and 5B are diagrams illustrating example operations for indicating a request for coverage enhancement by transmission of a DMRS in a different set of resource elements according to one or more aspects of the present disclosure.

FIG. 6 is a diagram illustrating an example of a triggering condition for indicating a request for coverage enhancement in accordance with aspects of the present disclosure.

FIG. 7 is a block diagram illustrating example blocks executed to implement one or more aspects of the present disclosure.

FIG. 8 is a block diagram illustrating example blocks executed to implement one or more aspects of the present disclosure

FIG. 9 is a block diagram conceptually illustrating a design of a UE configured according to some embodiments of the present disclosure.

FIG. 10 is a block diagram conceptually illustrating a design of a base station configured according to some embodiments of the present disclosure.

DETAILED DESCRIPTION

The detailed description set forth below, in connection with the appended drawings, is intended as a description of various configurations and is not intended to limit the scope of the disclosure. Rather, the detailed description includes specific details for the purpose of providing a thorough understanding of the inventive subject matter. It will be apparent to those skilled in the art that these specific details are not required in every case and that, in some instances, well-known structures and components are shown in block diagram form for clarity of presentation.

This disclosure relates generally to providing or participating in authorized shared access between two or more wireless communications systems, also referred to as wireless communications networks. In various embodiments, the techniques and apparatus may be used for wireless communication networks such as code division multiple access (CDMA) networks, time division multiple access (TDMA) networks, frequency division multiple access (FDMA) networks, orthogonal FDMA (OFDMA) networks, single-carrier FDMA (SC-FDMA) networks, LTE networks, GSM networks, 5 ^th Generation (5G) or new radio (NR) networks, as well as other communications networks. As described herein, the terms “networks” and “systems” may be used interchangeably.

An OFDMA network may implement a radio technology such as evolved UTRA (E-UTRA) , IEEE 802.11, IEEE 802.16, IEEE 802.20, flash-OFDM and the like. UTRA, E-UTRA, and Global System for Mobile Communications (GSM) are part of universal mobile telecommunication system (UMTS) . In particular, long term evolution (LTE) is a release of UMTS that uses E-UTRA. UTRA, E-UTRA, GSM, UMTS and LTE are described in documents provided from an organization named “3rd Generation Partnership Project” (3GPP) , and cdma2000 is described in documents from an organization named “3rd Generation Partnership Project 2” (3GPP2) . These various radio technologies and standards are known or are being developed. For example, the 3rd Generation Partnership Project (3GPP) is a collaboration between groups of telecommunications associations that aims to define a globally applicable third generation (3G) mobile phone specification. 3GPP long term evolution (LTE) is a 3GPP project which was aimed at improving the universal mobile telecommunications system (UMTS) mobile phone standard. The 3GPP may define specifications for the next generation of mobile networks, mobile systems, and mobile devices. The present disclosure is concerned with the evolution of wireless technologies from LTE, 4G, 5G, NR, and beyond with shared access to wireless spectrum between networks using a collection of new and different radio access technologies or radio air interfaces.

In particular, 5G networks contemplate diverse deployments, diverse spectrum, and diverse services and devices that may be implemented using an OFDM-based unified, air interface. In order to achieve these goals, further enhancements to LTE and LTE-A are considered in addition to development of the new radio technology for 5G NR networks. The 5G NR will be capable of scaling to provide coverage (1) to a massive Internet of things (IoTs) with an ultra-high density (e.g., ～1M nodes/km ²) , ultra-low complexity (e.g., ～10s of bits/sec) , ultra-low energy (e.g., ～10+ years of battery life) , and deep coverage with the capability to reach challenging locations; (2) including mission-critical control with strong security to safeguard sensitive personal, financial, or classified information, ultra-high reliability (e.g., ～99.9999%reliability) , ultra-low latency (e.g., ～ 1 ms) , and users with wide ranges of mobility or lack thereof; and (3) with enhanced mobile broadband including extreme high capacity (e.g., ～ 10 Tbps/km ²) , extreme data rates (e.g., multi-Gbps rate, 100+ Mbps user experienced rates) , and deep awareness with advanced discovery and optimizations.

The 5G NR may be implemented to use optimized OFDM-based waveforms with scalable numerology and transmission time interval (TTI) ; having a common, flexible framework to efficiently multiplex services and features with a dynamic, low-latency time division duplex (TDD) /frequency division duplex (FDD) design; and with advanced wireless technologies, such as massive multiple input, multiple output (MIMO) , robust millimeter wave (mmWave) transmissions, advanced channel coding, and device-centric mobility. Scalability of the numerology in 5G NR, with scaling of subcarrier spacing, may efficiently address operating diverse services across diverse spectrum and diverse deployments. For example, in various outdoor and macro coverage deployments of less than 3GHz FDD/TDD implementations, subcarrier spacing may occur with 15 kHz, for example over 1, 5, 10, 20 MHz, and the like bandwidth. For other various outdoor and small cell coverage deployments of TDD greater than 3 GHz, subcarrier spacing may occur with 30 kHz over 80/100 MHz bandwidth. For other various indoor wideband implementations, using a TDD over the unlicensed portion of the 5 GHz band, the subcarrier spacing may occur with 60 kHz over a 160 MHz bandwidth. Finally, for various deployments transmitting with mmWave components at a TDD of 28 GHz, subcarrier spacing may occur with 120 kHz over a 500 MHz bandwidth.

The scalable numerology of the 5G NR facilitates scalable TTI for diverse latency and quality of service (QoS) requirements. For example, shorter TTI may be used for low latency and high reliability, while longer TTI may be used for higher spectral efficiency. The efficient multiplexing of long and short TTIs to allow transmissions to start on symbol boundaries. 5G NR also contemplates a self-contained integrated subframe design with uplink/downlink scheduling information, data, and acknowledgement in the same subframe. The self-contained integrated subframe supports communications in unlicensed or contention-based shared spectrum, adaptive uplink/downlink that may be flexibly configured on a per-cell basis to dynamically switch between uplink and downlink to meet the current traffic needs.

Various other aspects and features of the disclosure are further described below. It should be apparent that the teachings herein may be embodied in a wide variety of forms and that any specific structure, function, or both being disclosed herein is merely representative and not limiting. Based on the teachings herein one of an ordinary level of skill in the art should appreciate that an aspect disclosed herein may be implemented independently of any other aspects and that two or more of these aspects may be combined in various ways. For example, an apparatus may be implemented or a method may be practiced using any number of the aspects set forth herein. In addition, such an apparatus may be implemented or such a method may be practiced using other structure, functionality, or structure and functionality in addition to or other than one or more of the aspects set forth herein. For example, a method may be implemented as part of a system, device, apparatus, and/or as instructions stored on a computer readable medium for execution on a processor or computer. Furthermore, an aspect may comprise at least one element of a claim.

FIG. 1 is a block diagram illustrating an example of a wireless communications system 100 that supports indicating a request for coverage enhancement in accordance with aspects of the present disclosure. The wireless communications system 100 includes base stations 105, UEs 115, and a core network 130. In some examples, the wireless communications system 100 may be a Long Term Evolution (LTE) network, an LTE-Advanced (LTE-A) network, an LTE-A Pro network, or NR network. In some cases, wireless communications system 100 may support enhanced broadband communications, ultra-reliable (e.g., mission critical) communications, low latency communications, or communications with low-cost and low-complexity devices.

Base stations 105 may wirelessly communicate with UEs 115 via one or more base station antennas. Base stations 105 described herein may include or may be referred to by those skilled in the art as a base transceiver station, a radio base station, an access point, a radio transceiver, a NodeB, an eNodeB (eNB) , a next-generation NodeB or giga-NodeB (either of which may be referred to as a gNB) , a Home NodeB, a Home eNodeB, or some other suitable terminology. Wireless communications system 100 may include base stations 105 of different types (e.g., macro or small cell base stations) . The UEs 115 described herein may be able to communicate with various types of base stations 105 and network equipment including macro eNBs, small cell eNBs, gNBs, relay base stations, and the like.

Each base station 105 may be associated with a particular geographic coverage area 110 in which communications with various UEs 115 is supported. Each base station 105 may provide communication coverage for a respective geographic coverage area 110 via communication links 125, and communication links 125 between a base station 105 and a UE 115 may utilize one or more carriers. Communication links 125 shown in wireless communications system 100 may include uplink transmissions from a UE 115 to a base station 105, or downlink transmissions from a base station 105 to a UE 115. Downlink transmissions may also be referred to as forward link transmissions while uplink transmissions may also be referred to as reverse link transmissions.

The geographic coverage area 110 for a base station 105 may be divided into sectors making up a portion of the geographic coverage area 110, and each sector may be associated with a cell. For example, each base station 105 may provide communication coverage for a macro cell, a small cell, a hot spot, or other types of cells, or various combinations thereof. In some examples, a base station 105 may be movable and, therefore, provide communication coverage for a moving geographic coverage area 110. In some examples, different geographic coverage areas 110 associated with different technologies may overlap, and overlapping geographic coverage areas 110 associated with different technologies may be supported by the same base station 105 or by different base stations 105. The wireless communications system 100 may include, for example, a heterogeneous LTE/LTE-A/LTE-A Pro or NR network in which different types of base stations 105 provide coverage for various geographic coverage areas 110.

The term “cell” refers to a logical communication entity used for communication with a base station 105 (e.g., over a carrier) , and may be associated with an identifier for distinguishing neighboring cells (e.g., a physical cell identifier (PCID) , a virtual cell identifier (VCID) ) operating via the same or a different carrier. In some examples, a carrier may support multiple cells, and different cells may be configured according to different protocol types (e.g., machine-type communication (MTC) , narrowband Internet-of-things (NB-IoT) , enhanced mobile broadband (eMBB) , or others) that may provide access for different types of devices. In some cases, the term “cell” may refer to a portion of a geographic coverage area 110 (e.g., a sector) over which the logical entity operates.

UEs 115 may be dispersed throughout the wireless communications system 100, and each UE 115 may be stationary or mobile. A UE 115 may also be referred to as a mobile device, a wireless device, a remote device, a handheld device, or a subscriber device, or some other suitable terminology, where the “device” may also be referred to as a unit, a station, a terminal, or a client. A UE 115 may also be a personal electronic device such as a cellular phone (UE 115a) , a personal digital assistant (PDA) , a wearable device (UE 115d) , a tablet computer, a laptop computer (UE 115g) , or a personal computer. In some examples, a UE 115 may also refer to a wireless local loop (WLL) station, an Internet-of-things (IoT) device, an Internet-of-everything (IoE) device, an MTC device, or the like, which may be implemented in various articles such as appliances, vehicles (UE 115e and UE 115f) , meters (UE 115b and UE 115c) , or the like.

Some UEs 115, such as MTC or IoT devices, may be low cost or low complexity devices, and may provide for automated communication between machines (e.g., via machine-to-machine (M2M) communication) . M2M communication or MTC may refer to data communication technologies that allow devices to communicate with one another or a base station 105 without human intervention. In some examples, M2M communication or MTC may include communications from devices that integrate sensors or meters to measure or capture information and relay that information to a central server or application program that can make use of the information or present the information to humans interacting with the program or application. Some UEs 115 may be designed to collect information or enable automated behavior of machines. Examples of applications for MTC devices include smart metering, inventory monitoring, water level monitoring, equipment monitoring, healthcare monitoring, wildlife monitoring, weather and geological event monitoring, fleet management and tracking, remote security sensing, physical access control, and transaction-based business charging.

Some UEs 115 may be configured to employ operating modes that reduce power consumption, such as half-duplex communications (e.g., a mode that supports one-way communication via transmission or reception, but not transmission and reception simultaneously) . In some examples, half-duplex communications may be performed at a reduced peak rate. Other power conservation techniques for UEs 115 include entering a power saving “deep sleep” mode when not engaging in active communications, or operating over a limited bandwidth (e.g., according to narrowband communications) . In other cases, UEs 115 may be designed to support critical functions (e.g., mission critical functions) , and a wireless communications system 100 may be configured to provide ultra-reliable communications for these functions.

In certain cases, a UE 115 may also be able to communicate directly with other UEs 115 (e.g., using a peer-to-peer (P2P) or device-to-device (D2D) protocol) . One or more of a group of UEs 115 utilizing D2D communications may be within the geographic coverage area 110 of a base station 105. Other UEs 115 in such a group may be outside the geographic coverage area 110 of a base station 105, or be otherwise unable to receive transmissions from a base station 105. In some cases, groups of UEs 115 communicating via D2D communications may utilize a one-to-many (1∶M) system in which each UE 115 transmits to every other UE 115 in the group. In some cases, a base station 105 may facilitate the scheduling of resources for D2D communications. In other cases, D2D communications may be carried out between UEs 115 without the involvement of a base station 105.

Base stations 105 may communicate with the core network 130 and with one another. For example, base stations 105 may interface with the core network 130 through backhaul links 132 (e.g., via an S1, N2, N3, or other interface) . Base stations 105 may communicate with one another over backhaul links 134 (e.g., via an X2, Xn, or other interface) either directly (e.g., directly between base stations 105) or indirectly (e.g., via core network 130) .

The core network 130 may provide user authentication, access authorization, tracking, Internet Protocol (IP) connectivity, and other access, routing, or mobility functions. The core network 130 may be an evolved packet core (EPC) , which may include at least one mobility management entity (MME) , at least one serving gateway (S-GW) , and at least one packet data network (PDN) gateway (P-GW) . The MME may manage non-access stratum (e.g., control plane) functions such as mobility, authentication, and bearer management for UEs 115 served by base stations 105 associated with the EPC. User IP packets may be transferred through the S-GW, which itself may be connected to the P-GW. The P-GW may provide IP address allocation as well as other functions. The P-GW may be connected to the network operators IP services. The operators IP services may include access to the Internet, Intranet (s) , an IP multimedia subsystem (IMS) , or a packet-switched (PS) streaming service.

At least some of the network devices, such as a base station 105, may include subcomponents such as an access network entity, which may be an example of an access node controller (ANC) . Each access network entity may communicate with UEs 115 through a number of other access network transmission entities, which may be referred to as a radio head, a smart radio head, or a transmission/reception point (TRP) . In some configurations, various functions of each access network entity or base station 105 may be distributed across various network devices (e.g., radio heads and access network controllers) or consolidated into a single network device (e.g., a base station 105) .

Wireless communications system 100 may operate using one or more frequency bands, typically in the range of 300 megahertz (MHz) to 300 gigahertz (GHz) . Generally, the region from 300 MHz to 3 GHz is known as the ultra-high frequency (UHF) region or decimeter band, since the wavelengths range from approximately one decimeter to one meter in length. UHF waves may be blocked or redirected by buildings and environmental features. However, the waves may penetrate structures sufficiently for a macro cell to provide service to UEs 115 located indoors. Transmission of UHF waves may be associated with smaller antennas and shorter range (e.g., less than 100 km) compared to transmission using the smaller frequencies and longer waves of the high frequency (HF) or very high frequency (VHF) portion of the spectrum below 300 MHz.

Wireless communications system 100 may also operate in a super high frequency (SHF) region using frequency bands from 3 GHz to 30 GHz, also known as the centimeter band. The SHF region includes bands such as the 5 GHz industrial, scientific, and medical (ISM) bands, which may be used opportunistically by devices that may be capable of tolerating interference from other users.

Wireless communications system 100 may also operate in an extremely high frequency (EHF) region of the spectrum (e.g., from 30 GHz to 300 GHz) , also known as the millimeter band. In some examples, wireless communications system 100 may support millimeter wave (mmW) communications between UEs 115 and base stations 105, and EHF antennas of the respective devices may be even smaller and more closely spaced than UHF antennas. In some cases, this may facilitate use of antenna arrays within a UE 115. However, the propagation of EHF transmissions may be subject to even greater atmospheric attenuation and shorter range than SHF or UHF transmissions. Techniques disclosed herein may be employed across transmissions that use one or more different frequency regions, and designated use of bands across these frequency regions may differ by country or regulating body.

Wireless communications system 100 may include operations by different network operating entities (e.g., network operators) , in which each network operator may share spectrum. In some instances, a network operating entity may be configured to use an entirety of a designated shared spectrum for at least a period of time before another network operating entity uses the entirety of the designated shared spectrum for a different period of time. Thus, in order to allow network operating entities use of the full designated shared spectrum, and in order to mitigate interfering communications between the different network operating entities, certain resources (e.g., time) may be partitioned and allocated to the different network operating entities for certain types of communication.

For example, a network operating entity may be allocated certain time resources reserved for exclusive communication by the network operating entity using the entirety of the shared spectrum. The network operating entity may also be allocated other time resources where the entity is given priority over other network operating entities to communicate using the shared spectrum. These time resources, prioritized for use by the network operating entity, may be utilized by other network operating entities on an opportunistic basis if the prioritized network operating entity does not utilize the resources. Additional time resources may be allocated for any network operator to use on an opportunistic basis.

Access to the shared spectrum and the arbitration of time resources among different network operating entities may be centrally controlled by a separate entity, autonomously determined by a predefined arbitration scheme, or dynamically determined based on interactions between wireless nodes of the network operators.

In various implementations, wireless communications system 100 may use both licensed and unlicensed radio frequency spectrum bands. For example, wireless communications system 100 may employ license assisted access (LAA) , LTE-unlicensed (LTE-U) radio access technology, or NR technology in an unlicensed band (NR-U) , such as the 5 GHz ISM band. In some cases, UE 115 and base station 105 of the wireless communications system 100 may operate in a shared radio frequency spectrum band, which may include licensed or unlicensed (e.g., contention-based) frequency spectrum. In an unlicensed frequency portion of the shared radio frequency spectrum band, UEs 115 or base stations 105 may traditionally perform a medium-sensing procedure to contend for access to the frequency spectrum. For example, UE 115 or base station 105 may perform a listen before talk (LBT) procedure such as a clear channel assessment (CCA) prior to communicating in order to determine whether the shared channel is available.

A CCA may include an energy detection procedure to determine whether there are any other active transmissions on the shared channel. For example, a device may infer that a change in a received signal strength indicator (RSSI) of a power meter indicates that a channel is occupied. Specifically, signal power that is concentrated in a certain bandwidth and exceeds a predetermined noise floor may indicate another wireless transmitter. A CCA also may include message detection of specific sequences that indicate use of the channel. For example, another device may transmit a specific preamble prior to transmitting a data sequence. In some cases, an LBT procedure may include a wireless node adjusting its own backoff window based on the amount of energy detected on a channel and/or the acknowledge/negative-acknowledge (ACK/NACK) feedback for its own transmitted packets as a proxy for collisions.

In general, four categories of LBT procedure have been suggested for sensing a shared channel for signals that may indicate the channel is already occupied. In a first category (CAT 1 LBT) , no LBT or CCA is applied to detect occupancy of the shared channel. A second category (CAT 2 LBT) , which may also be referred to as an abbreviated LBT, a single-shot LBT, or a 25-μs LBT, provides for the node to perform a CCA to detect energy above a predetermined threshold or detect a message or preamble occupying the shared channel. The CAT 2 LBT performs the CCA without using a random back-off operation, which results in its abbreviated length, relative to the next categories.

A third category (CAT 3 LBT) performs CCA to detect energy or messages on a shared channel, but also uses a random back-off and fixed contention window. Therefore, when the node initiates the CAT 3 LBT, it performs a first CCA to detect occupancy of the shared channel. If the shared channel is idle for the duration of the first CCA, the node may proceed to transmit. However, if the first CCA detects a signal occupying the shared channel, the node selects a random back-off based on the fixed contention window size and performs an extended CCA. If the shared channel is detected to be idle during the extended CCA and the random number has been decremented to 0, then the node may begin transmission on the shared channel. Otherwise, the node decrements the random number and performs another extended CCA. The node would continue performing extended CCA until the random number reaches 0. If the random number reaches 0 without any of the extended CCAs detecting channel occupancy, the node may then transmit on the shared channel. If at any of the extended CCA, the node detects channel occupancy, the node may re-select a new random back-off based on the fixed contention window size to begin the countdown again.

A fourth category (CAT 4 LBT) , which may also be referred to as a full LBT procedure, performs the CCA with energy or message detection using a random back-off and variable contention window size. The sequence of CCA detection proceeds similarly to the process of the CAT 3 LBT, except that the contention window size is variable for the CAT 4 LBT procedure.

Use of a medium-sensing procedure to contend for access to an unlicensed shared spectrum may result in communication inefficiencies. This may be particularly evident when multiple network operating entities (e.g., network operators) are attempting to access a shared resource. In wireless communications system 100, base stations 105 and UEs 115 may be operated by the same or different network operating entities. In some examples, an individual base station 105 or UE 115 may be operated by more than one network operating entity. In other examples, each base station 105 and UE 115 may be operated by a single network operating entity. Requiring each base station 105 and UE 115 of different network operating entities to contend for shared resources may result in increased signaling overhead and communication latency.

In some cases, operations in unlicensed bands may be based on a carrier aggregation configuration in conjunction with component carriers operating in a licensed band (e.g., LAA) . Operations in unlicensed spectrum may include downlink transmissions, uplink transmissions, peer-to-peer transmissions, or a combination of these. Duplexing in unlicensed spectrum may be based on frequency division duplexing (FDD) , time division duplexing (TDD) , or a combination of both.

In some examples, base station 105 or UE 115 may be equipped with multiple antennas, which may be used to employ techniques such as transmit diversity, receive diversity, multiple-input multiple-output (MIMO) communications, or beamforming. For example, wireless communications system 100 may use a transmission scheme between a transmitting device (e.g., a base station 105) and a receiving device (e.g., a UE 115) , where the transmitting device is equipped with multiple antennas and the receiving device is equipped with one or more antennas. MIMO communications may employ multipath signal propagation to increase the spectral efficiency by transmitting or receiving multiple signals via different spatial layers, which may be referred to as spatial multiplexing. The multiple signals may, for example, be transmitted by the transmitting device via different antennas or different combinations of antennas. Likewise, the multiple signals may be received by the receiving device via different antennas or different combinations of antennas. Each of the multiple signals may be referred to as a separate spatial stream, and may carry bits associated with the same data stream (e.g., the same codeword) or different data streams. Different spatial layers may be associated with different antenna ports used for channel measurement and reporting. MIMO techniques include single-user MIMO (SU-MIMO) where multiple spatial layers are transmitted to the same receiving device, and multiple-user MIMO (MU-MIMO) where multiple spatial layers are transmitted to multiple devices.

Beamforming, which may also be referred to as spatial filtering, directional transmission, or directional reception, is a signal processing technique that may be used at a transmitting device or a receiving device (e.g., a base station 105 or a UE 115) to shape or steer an antenna beam (e.g., a transmit beam or receive beam) along a spatial path between the transmitting device and the receiving device. Beamforming may be achieved by combining the signals communicated via antenna elements of an antenna array such that signals propagating at particular orientations with respect to an antenna array experience constructive interference while others experience destructive interference. The adjustment of signals communicated via the antenna elements may include a transmitting device or a receiving device applying certain amplitude and phase offsets to signals carried via each of the antenna elements associated with the device. The adjustments associated with each of the antenna elements may be defined by a beamforming weight set associated with a particular orientation (e.g., with respect to the antenna array of the transmitting device or receiving device, or with respect to some other orientation) .

In one example, a base station 105 may use multiple antennas or antenna arrays to conduct beamforming operations for directional communications with a UE 115. For instance, some signals (e.g. synchronization signals, reference signals, beam selection signals, or other control signals) may be transmitted by a base station 105 multiple times in different directions, which may include a signal being transmitted according to different beamforming weight sets associated with different directions of transmission. Transmissions in different beam directions may be used to identify (e.g., by the base station 105 or a receiving device, such as a UE 115) a beam direction for subsequent transmission and/or reception by the base station 105.

Some signals, such as data signals associated with a particular receiving device, may be transmitted by a base station 105 in a single beam direction (e.g., a direction associated with the receiving device, such as a UE 115) . In some examples, the beam direction associated with transmissions along a single beam direction may be determined based at least in in part on a signal that was transmitted in different beam directions. For example, a UE 115 may receive one or more of the signals transmitted by the base station 105 in different directions, and the UE 115 may report to the base station 105 an indication of the signal it received with a highest signal quality, or an otherwise acceptable signal quality. Although these techniques are described with reference to signals transmitted in one or more directions by a base station 105, a UE 115 may employ similar techniques for transmitting signals multiple times in different directions (e.g., for identifying a beam direction for subsequent transmission or reception by the UE 115) , or transmitting a signal in a single direction (e.g., for transmitting data to a receiving device) .

A receiving device (e.g., a UE 115, which may be an example of a mmW receiving device) may try multiple receive beams when receiving various signals from the base station 105, such as synchronization signals, reference signals, beam selection signals, or other control signals. For example, a receiving device may try multiple receive directions by receiving via different antenna subarrays, by processing received signals according to different antenna subarrays, by receiving according to different receive beamforming weight sets applied to signals received at a plurality of antenna elements of an antenna array, or by processing received signals according to different receive beamforming weight sets applied to signals received at a plurality of antenna elements of an antenna array, any of which may be referred to as “listening” according to different receive beams or receive directions. In some examples a receiving device may use a single receive beam to receive along a single beam direction (e.g., when receiving a data signal) . The single receive beam may be aligned in a beam direction determined based at least in part on listening according to different receive beam directions (e.g., a beam direction determined to have a highest signal strength, highest signal-to-noise ratio, or otherwise acceptable signal quality based at least in part on listening according to multiple beam directions) .

In certain implementations, the antennas of a base station 105 or UE 115 may be located within one or more antenna arrays, which may support MIMO operations, or transmit or receive beamforming. For example, one or more base station antennas or antenna arrays may be co-located at an antenna assembly, such as an antenna tower. In some cases, antennas or antenna arrays associated with a base station 105 may be located in diverse geographic locations. A base station 105 may have an antenna array with a number of rows and columns of antenna ports that the base station 105 may use to support beamforming of communications with a UE 115. Likewise, a UE 115 may have one or more antenna arrays that may support various MIMO or beamforming operations.

In additional cases, UEs 115 and base stations 105 may support retransmissions of data to increase the likelihood that data is received successfully. HARQ feedback is one technique of increasing the likelihood that data is received correctly over a communication link 125. HARQ may include a combination of error detection (e.g., using a cyclic redundancy check (CRC) ) , forward error correction (FEC) , and retransmission (e.g., automatic repeat request (ARQ) ) . HARQ may improve throughput at the MAC layer in poor radio conditions (e.g., signal-to-noise conditions) . In some cases, a wireless device may support same-slot HARQ feedback, where the device may provide HARQ feedback in a specific slot for data received in a previous symbol in the slot, while in other cases, the device may provide HARQ feedback in a subsequent slot, or according to some other time interval.

Time intervals in LTE or NR may be expressed in multiples of a basic time unit, which may, for example, refer to a sampling period of T _s = 1/30,720,000 seconds. Time intervals of a communications resource may be organized according to radio frames each having a duration of 10 milliseconds (ms) , where the frame period may be expressed as T _f= 307,200 T _s. The radio frames may be identified by a system frame number (SFN) ranging from 0 to 1023. Each frame may include 10 subframes numbered from 0 to 9, and each subframe may have a duration of 1 ms. A subframe may be further divided into 2 slots each having a duration of 0.5 ms, and each slot may contain 6 or 7 modulation symbol periods (e.g., depending on the length of the cyclic prefix prepended to each symbol period) . Excluding the cyclic prefix, each symbol period may contain 2048 sampling periods. In some cases, a subframe may be the smallest scheduling unit of the wireless communications system 100, and may be referred to as a transmission time interval (TTI) . In other cases, a smallest scheduling unit of the wireless communications system 100 may be shorter than a subframe or may be dynamically selected (e.g., in bursts of shortened TTIs (sTTIs) or in selected component carriers using sTTIs) .

In some wireless communications systems, a slot may further be divided into multiple mini-slots containing one or more symbols. In some instances, a symbol of a mini-slot or a mini-slot may be the smallest unit of scheduling. Each symbol may vary in duration depending on the subcarrier spacing or frequency band of operation, for example. Further, some wireless communications systems may implement slot aggregation in which multiple slots or mini-slots are aggregated together and used for communication between a UE 115 and a base station 105.

The term “carrier, ” as may be used herein, refers to a set of radio frequency spectrum resources having a defined physical layer structure for supporting communications over a communication link 125. For example, a carrier of a communication link 125 may include a portion of a radio frequency spectrum band that is operated according to physical layer channels for a given radio access technology. Each physical layer channel may carry user data, control information, or other signaling. A carrier may be associated with a pre-defined frequency channel (e.g., an evolved universal mobile telecommunication system terrestrial radio access (E-UTRA) absolute radio frequency channel number (EARFCN) ) , and may be positioned according to a channel raster for discovery by UEs 115. Carriers may be downlink or uplink (e.g., in an FDD mode) , or be configured to carry downlink and uplink communications (e.g., in a TDD mode) . In some examples, signal waveforms transmitted over a carrier may be made up of multiple sub-carriers (e.g., using multi-carrier modulation (MCM) techniques such as orthogonal frequency division multiplexing (OFDM) or discrete Fourier transform spread OFDM (DFT-S-OFDM) ) .

The organizational structure of the carriers may be different for different radio access technologies (e.g., LTE, LTE-A, LTE-A Pro, NR) . For example, communications over a carrier may be organized according to TTIs or slots, each of which may include user data as well as control information or signaling to support decoding the user data. A carrier may also include dedicated acquisition signaling (e.g., synchronization signals or system information, etc. ) and control signaling that coordinates operation for the carrier. In some examples (e.g., in a carrier aggregation configuration) , a carrier may also have acquisition signaling or control signaling that coordinates operations for other carriers.

Physical channels may be multiplexed on a carrier according to various techniques. A physical control channel and a physical data channel may be multiplexed on a downlink carrier, for example, using time division multiplexing (TDM) techniques, frequency division multiplexing (FDM) techniques, or hybrid TDM-FDM techniques. In some examples, control information transmitted in a physical control channel may be distributed between different control regions in a cascaded manner (e.g., between a common control region or common search space and one or more UE-specific control regions or UE-specific search spaces) .

A carrier may be associated with a particular bandwidth of the radio frequency spectrum, and in some examples the carrier bandwidth may be referred to as a “system bandwidth” of the carrier or the wireless communications system 100. For example, the carrier bandwidth may be one of a number of predetermined bandwidths for carriers of a particular radio access technology (e.g., 1.4, 3, 5, 10, 15, 20, 40, or 80 MHz) . In some examples, each served UE 115 may be configured for operating over portions or all of the carrier bandwidth. In other examples, some UEs 115 may be configured for operation using a narrowband protocol type that is associated with a predefined portion or range (e.g., set of subcarriers or RBs) within a carrier (e.g., “in-band” deployment of a narrowband protocol type) .

In a system employing MCM techniques, a resource element may consist of one symbol period (e.g., a duration of one modulation symbol) and one subcarrier, where the symbol period and subcarrier spacing are inversely related. The number of bits carried by each resource element may depend on the modulation scheme (e.g., the order of the modulation scheme) . Thus, the more resource elements that a UE 115 receives and the higher the order of the modulation scheme, the higher the data rate may be for the UE 115. In MIMO systems, a wireless communications resource may refer to a combination of a radio frequency spectrum resource, a time resource, and a spatial resource (e.g., spatial layers) , and the use of multiple spatial layers may further increase the data rate for communications with a UE 115.

Devices of the wireless communications system 100 (e.g., base stations 105 or UEs 115) may have a hardware configuration that supports communications over a particular carrier bandwidth, or may be configurable to support communications over one of a set of carrier bandwidths. In some examples, the wireless communications system 100 may include base stations 105 and/or UEs 115 that support simultaneous communications via carriers associated with more than one different carrier bandwidth.

Wireless communications system 100 may support communication with a UE 115 on multiple cells or carriers, a feature which may be referred to as carrier aggregation or multi-carrier operation. A UE 115 may be configured with multiple downlink component carriers and one or more uplink component carriers according to a carrier aggregation configuration. Carrier aggregation may be used with both FDD and TDD component carriers.

In some cases, wireless communications system 100 may utilize enhanced component carriers (eCCs) . An eCC may be characterized by one or more features including wider carrier or frequency channel bandwidth, shorter symbol duration, shorter TTI duration, or modified control channel configuration. In certain instances, an eCC may be associated with a carrier aggregation configuration or a dual connectivity configuration (e.g., when multiple serving cells have a suboptimal or non-ideal backhaul link) . An eCC may also be configured for use in unlicensed spectrum or shared spectrum (e.g., where more than one operator is allowed to use the spectrum, such as NR-shared spectrum (NR-SS) ) . An eCC characterized by wide carrier bandwidth may include one or more segments that may be utilized by UEs 115 that are not capable of monitoring the whole carrier bandwidth or are otherwise configured to use a limited carrier bandwidth (e.g., to conserve power) .

In additional cases, an eCC may utilize a different symbol duration than other component carriers, which may include use of a reduced symbol duration as compared with symbol durations of the other component carriers. A shorter symbol duration may be associated with increased spacing between adjacent subcarriers. A device, such as a UE 115 or base station 105, utilizing eCCs may transmit wideband signals (e.g., according to frequency channel or carrier bandwidths of 20, 40, 60, 80 MHz, etc. ) at reduced symbol durations (e.g., 16.67 microseconds) . A TTI in eCC may consist of one or multiple symbol periods. In some cases, the TTI duration (that is, the number of symbol periods in a TTI) may be variable.

Wireless communications system 100 may be an NR system that may utilize any combination of licensed, shared, and unlicensed spectrum bands, among others. The flexibility of eCC symbol duration and subcarrier spacing may allow for the use of eCC across multiple spectrums. In some examples, NR shared spectrum may increase spectrum utilization and spectral efficiency, specifically through dynamic vertical (e.g., across the frequency domain) and horizontal (e.g., across the time domain) sharing of resources.

FIG. 2 shows a block diagram of a design of a base station 105 and a UE 115, which may be one of the base station and one of the UEs in FIG. 1. At base station 105, a transmit processor 220 may receive data from a data source 212 and control information from a controller/processor 240. The control information may be for the PBCH, PCFICH, PHICH, PDCCH, EPDCCH, MPDCCH etc. The data may be for the PDSCH, etc. The transmit processor 220 may process (e.g., encode and symbol map) the data and control information to obtain data symbols and control symbols, respectively. The transmit processor 220 may also generate reference symbols, e.g., for the PSS, SSS, and cell-specific reference signal. A transmit (TX) multiple-input multiple-output (MIMO) processor 230 may perform spatial processing (e.g., precoding) on the data symbols, the control symbols, and/or the reference symbols, if applicable, and may provide output symbol streams to the modulators (MODs) 232a through 232t. Each modulator 232 may process a respective output symbol stream (e.g., for OFDM, etc. ) to obtain an output sample stream. Each modulator 232 may further process (e.g., convert to analog, amplify, filter, and upconvert) the output sample stream to obtain a downlink signal. Downlink signals from modulators 232a through 232t may be transmitted via the antennas 234a through 234t, respectively.

At UE 115, the antennas 252a through 252r may receive the downlink signals from the base station 105 and may provide received signals to the demodulators (DEMODs) 254a through 254r, respectively. Each demodulator 254 may condition (e.g., filter, amplify, downconvert, and digitize) a respective received signal to obtain input samples. Each demodulator 254 may further process the input samples (e.g., for OFDM, etc. ) to obtain received symbols. A MIMO detector 256 may obtain received symbols from all the demodulators 254a through 254r, perform MIMO detection on the received symbols if applicable, and provide detected symbols. A receive processor 258 may process (e.g., demodulate, deinterleave, and decode) the detected symbols, provide decoded data for the UE 115 to a data sink 260, and provide decoded control information to a controller/processor 280.

On the uplink, at the UE 115, a transmit processor 264 may receive and process data (e.g., for the PUSCH) from a data source 262 and control information (e.g., for the PUCCH) from the controller/processor 280. The transmit processor 264 may also generate reference symbols for a reference signal. The symbols from the transmit processor 264 may be precoded by a TX MIMO processor 266 if applicable, further processed by the modulators 254a through 254r (e.g., for SC-FDM, etc. ) , and transmitted to the base station 105. At the base station 105, the uplink signals from the UE 115 may be received by the antennas 234, processed by the demodulators 232, detected by a MIMO detector 236 if applicable, and further processed by a receive processor 238 to obtain decoded data and control information sent by the UE 115. The processor 238 may provide the decoded data to a data sink 239 and the decoded control information to the controller/processor 240.

The controllers/

processors

240 and 280 may direct the operation at the base station 105 and the UE 115, respectively. The controller/processor 240 and/or other processors and modules at the base station 105 may perform or direct the execution of various processes for the techniques described herein. The controllers/processor 280 and/or other processors and modules at the UE 115 may also perform or direct the execution of the functional blocks illustrated in FIGS. 3, and 7-10, and/or other processes for the techniques described herein. The

memories

242 and 282 may store data and program codes for the base station 105 and the UE 115, respectively. A scheduler 244 may schedule UEs for data transmission on the downlink and/or uplink.

In current implementations of wireless communication systems, special emphasis is put on support of premium devices (e.g., UEs using the eMBB protocol, such as smartphones, etc. ) and other devices using protocols such as ultra-reliable low-latency communication (URLLC) and/or vehicle-to-everything (V2X) protocols, among others. Nonetheless, communication systems need to be scalable and deployable in a more efficient and cost-effective way. For example, peak throughput, latency, reliability requirements, etc., should be able to be relaxed in these systems. In addition, a greater emphasis should be put on efficiency (e.g. power consumption, system overhead, etc. ) as well as cost improvements, which may be obtained by implementing an improved form factor (e.g. smaller supported bandwidth, fewer antennas, etc. ) .

One particular case in which the limitations of current systems is significant relates to physical uplink shared channel (PUSCH) transmissions. PUSCH transmissions, including PUSCH transmissions from normal UEs (and including physical random access channel (PRACH) message 3 (Msg3) PUSCH transmissions) , are identified as bottleneck channel for coverage. Current implementations attempt to address this issue by providing coverage enhancement that includes support of PUSCH repetition. For example, in some implementations, Msg3 PUSCH repetition may be used to provide coverage enhancement. Msg3 PUSCH repetition includes retransmitting the Msg3 PUSCH repeatedly, or transmitting a number of repetitions of the Msg3 PUSCH retransmission. In these cases, rather than merely transmitting a single Msg3 PUSCH retransmission, the Msg3 PUSCH retransmission is repeated a number of times. In some cases, the modulation and coding scheme (MCS) and resource allocation for the repetitions to be sent by the UE may be indicated by the base station in an associated scheduling downlink control information (DCI) message, and the MCS and resource allocation may be common over successive slots. In some cases, for each slot of a multi-slot PUSCH, the transmission block (TB) of each repetition may be the same, but the encoded bits of each repetition may differ (e.g., the redundancy version (RV) of each slot may be different) .

Another case in which the limitations of current systems is significant is with regards to reduced capabilities (RedCap) UEs, also known as NR-light UEs. A RedCap UE may be a device that has or is configured with limited capabilities when compared with a normal UE. RedCap UEs may include wearable device (e.g. smart watches, etc. ) , industrial wireless sensor networks (IWSN) , surveillance cameras, IoT devices, sensors, etc. In current implementations of wireless communication systems, there are coverage issues associated with RedCap UEs. For example, due to the reduced capabilities of a RedCap UE (e.g. fewer antennas, smaller antenna size, smaller bandwidth etc. ) , a link budget for some uplink/downlink channels may degrade considerably. In one particular case, with respect to coverage recovery, transmission of the message 3 (Msg3) physical uplink shared channel (PUSCH) message by a RedCap UE is one of the bottleneck channels that has a relatively large gap for coverage compensation.

In current implementations, the capabilities of a UE may be signaled to a base station after a radio resource control (RRC) connection. For a RedCap UE, early indication of the UE’s capabilities is especially important as there may be coverage issues during initial access (e.g. coverage-limited common PDCCH, Msg3 PUSCH, and/or message 4 (Msg4) or message 2 (Msg2) physical downlink shared channel (PDSCH) , during a random access channel (RACH) procedure) . In aspects, an early indication that the UE is a RedCap UE may allow a base station to schedule transmissions with appropriate coverage compensation (e.g. repetition, low-SE MCS, higher aggregation level, etc. ) . In some cases, the Redcap UE indication may be a 1-bit indication indicating whether the UE is a RedCap or not. In some cases the indication may include an indication of the type of RedCap UE from multiple RedCap UE types. In some cases, an indication that the UE requires coverage enhancement/recovery for one or more RACH channels may be made.

In current implementations, there may be four options for indicating that a UE is a RedCap UE. In a first option, a UE may indicate to a base station that the UE is a RedCap UE during transmission of the PRACH message 1 (Msg1) . For example, the UE may transmit the indication via a separate initial uplink bandwidth part (BWP) , a separate PRACH resource, or a PRACH preamble partitioning. In a second option, a UE may indicate to a base station that the UE is a RedCap UE during the Msg3 PUSCH transmission. In a third option, a UE may indicate to a base station that the UE is a RedCap UE in a PRACH message 4 (Msg4) acknowledgment (e.g., during PRACH message 5 (Msg5) transmission, or as part of the UE capability reporting) . In a fourth option, a UE may indicate to a base station that the UE is a RedCap UE during a transmission of the PRACH message A (MsgA) , but this is subject to support of a 2-step RACH procedure.

However, the options for indicating that a UE is a RedCap UE discussed above have limitations and give rise to various problems. For example, implementing the first option may have a negative impact on the PRACH capacity of a system, as it adds to the complexity and overhead requirements. This may be problematic for a UE, especially a RedCap UE. Implementing the second option may also cause problems, as Msg3 PUSCH is itself a coverage-limited channel. For example, before the RedCap indication in the Msg3 PUSCH indication from a UE, a base station may not know whether the UE needs coverage enhancement, and/or whether the UE is a RedCap UE. If the initial transmission of the Msg3 PUSCH by the UE is decoded incorrectly by the base station, the base station may not know the UE requires coverage enhancement for the Msg3 PUSCH, since the base station has not obtained the coverage enhancement indication by decoding Msg3 PUSCH. In this case, a retransmission of the Msg3 PUSCH scheduled by the base station may assume the UE has or requires normal coverage, which may then case more retransmissions of the Msg3 PUSCH to be scheduled than otherwise, and increase the UE’s RACH latency and power consumption.

Various aspects of the present disclosure are directed to systems and methods that support indicating a request for coverage enhancement. In particular, aspects of the present disclosure provide techniques and systems for a UE to determine to request coverage enhancement from a base station, and for indicating the request for coverage enhancement to the base station. In aspects, the request for coverage enhancement may include an indication to the base station that the UE is a RedCap UE. In these aspects, the base station, in response to receiving the indication, may provide coverage enhancement, such as by scheduling transmissions to the UE using coverage compensation. The coverage enhancement provided by the base station may be based on the indication that the UE is a RedCap UE and/or may be based on the lower capabilities of the RedCap UE. In aspects, the request for coverage enhancement may include a request from the UE for one or more retransmission grants of a PRACH message transmitted to the base station. In some aspects, the PRACH message may be a Msg3 PUSCH message. In some aspects, the request from the UE for one or more retransmission grants of the PRACH message may include a request to the base station for a grant to transmit, from the UE, a number of repetitions of a retransmission of the PRACH message.

In aspects, indicating the request for coverage enhancement may include scheduling and/or transmitting a random access response (RAR) scheduled message (e.g., a PRACH message such as a Msg3 PUSCH message) in a portion of the frequency domain resources granted to the UE, by the base station, for the transmission of the PRACH message. In aspects, the UE may receive a RAR message (e.g., a RAR Msg2) from the base station including a grant for (or scheduling) a transmission of the PRACH message in a particular set of frequency domain resources. The UE may determine to indicate the request for coverage enhancement by transmitting the PRACH message in a subset, or a portion, of the set of frequency domain resources that the base station scheduled or granted for the transmission of the PRACH message. In aspects, the subset, or portion, may be smaller than the set of frequency domain resources.

In aspects, the partial transmission of the RAR scheduled message by the UE may indicate to the base station that the UE is requesting coverage enhancement. In some aspects, the location of the portion of the set of frequency domain resources in which the RAR scheduled message is transmitted by the UE may indicate the level of coverage enhancement requested by the UE. In these cases, transmitting the RAR scheduled message in a portion located in a first location of the set of frequency domain resources may indicate a request for a first level of coverage enhancement, and transmitting the RAR scheduled message in a portion located in a second location of the set of frequency domain resources may indicate a request for a second level of coverage enhancement.

In aspects, the UE may indicate the request for coverage enhancement by scheduling and/or transmitting a demodulation references signal (DMRS) in a first set of resource elements of the DMRS symbol. In aspects, the first set of resource elements may include different resource elements than a standard set of resource elements in which the DMRS is typically sent (e.g., transmitted in accordance with the standard 5G NR configuration) . In some aspects, the UE may indicate the request for coverage enhancement by scheduling and/or transmitting the DMRS using a first set of cyclic shifts. The first set of cyclic shifts may include different cyclic shifts than a standard set of cyclic shifts used for standard transmission of the DMRS (e.g., a DMRS transmission in accordance with a standard 5G NR configuration) .

In aspects, the UE may indicate the request for coverage enhancement by scheduling and/or transmitting a sounding reference signal (SRS) as a substitute for a PRACH PUSCH transmission (e.g., a Msg3 PUSCH transmission) . In these cases, for example after a RAR Msg2 message is received by the UE, the UE may schedule and/or transmit and SRS instead of scheduling and/or transmitting the Msg3 PUSCH. The scheduling and/or transmission of the SRS instead of the Msg3 PUSCH may indicate to the base station that the UE is requesting coverage enhancement.

In aspects, the UE may be triggered to request coverage enhancement by various conditions and/or events. In some aspects, the UE may receive a transmit power control (TPC) command in a RAR message (e.g., RAR Msg2) from the base station, and the TPC command may include a power offset. The UE may determine to indicate a request for coverage enhancement to the base station based on a determination that applying the power offset to the PRACH PUSCH transmission (e.g., the Msg3 PUSCH transmission) may result in a transmission power for the PRACH message transmission exceeding a maximum power supported by the UE. In this case, the UE may decide to request coverage enhancement (e.g., retransmission grants and/or transmission compensation) from the base station. In some aspects, the UE may measure a reference signal received power (RSRP) for a transmission (e.g., a RAR message such as a RAR Msg2) received from the base station. The UE may determine to indicate a request for coverage enhancement to the base station based on a determination that the RSRP measurement is below a threshold.

FIG. 3 is a block diagram of an example wireless communications system 300 that supports indication of a request for coverage enhancement from a UE to a base station according to one or more aspects of the present disclosure. In particular, wireless communications system 300 may implement aspects of the present disclosure in which a UE determines to indicate a request for coverage enhancement to a base station, generates the indication and transmits the indication a base station. The base station may receive the indication of the request for coverage enhancement from the UE, and may provide coverage enhancement in response.

In some examples, wireless communications system 300 may implement aspects of wireless network 100. Wireless communications system 300 includes UE 115 and base station 105. Although one UE 115 and one base station 105 are illustrated, in some other implementations, wireless communications system 300 may generally include multiple UEs 115 and may include more than one base station 105.

UE 115 may include a variety of components (such as structural, hardware components) used for carrying out one or more functions described herein. For example, these components may include one or more processors 302 (hereinafter referred to collectively as “processor 302” ) , one or more memory devices 304 (hereinafter referred to collectively as “memory 304” ) , one or more transmitters 316 (hereinafter referred to collectively as “transmitter 316” ) , and one or more receivers 318 (hereinafter referred to collectively as “receiver 318” ) . Processor 302 may be configured to execute instructions stored in memory 304 to perform the operations described herein. In some implementations, processor 302 includes or corresponds to one or more of receive processor 258, transmit processor 264, and controller 280, and memory 304 includes or corresponds to memory 282. Memory 304 includes or is configured to store coverage enhancement request logic 305.

Transmitter 316 is configured to transmit reference signals, control information and data to one or more other devices, and receiver 318 is configured to receive references signals, synchronization signals, control information and data from one or more other devices. For example, transmitter 316 may transmit signaling, control information and data to, and receiver 318 may receive signaling, control information and data from base station 105. In some implementations, transmitter 316 and receiver 318 may be integrated in one or more transceivers. Additionally or alternatively, transmitter 316 or receiver 318 may include or correspond to one or more components ofUE 115 described with reference to FIG. 2.

In aspects, coverage enhancement request logic 305 may be configured to determine to indicate a request for coverage enhancement to a base station, to generate the indication, and to transmit the indication to base station 105. In aspects, generating the indication of the request for coverage enhancement to be transmitted to base station 105 may include transmitting a RAR scheduled message (e.g., a Msg3 PUSCH message) in a portion of the set of frequency domain resources granted to the UE for the transmission of the PRACH message, scheduling and/or transmitting a DMRS in a first set of resource elements different than the standard set of resource elements, scheduling and/or transmitting the DMRS using a first set of cyclic shifts different than the standard set of cyclic shifts, and/or scheduling and/or transmitting an SRS as a substitute for a PRACH PUSCH transmission (e.g., a Msg3 PUSCH transmission) .

Base station 105 may include a variety of components (such as structural, hardware components) used for carrying out one or more functions described herein. For example, these components may include one or more processors 352 (hereinafter referred to collectively as “processor 352” ) , one or more memory devices 354 (hereinafter referred to collectively as “memory 354” ) , one or more transmitters 356 (hereinafter referred to collectively as “transmitter 356” ) , and one or more receivers 358 (hereinafter referred to collectively as “receiver 358” ) . Processor 352 may be configured to execute instructions stored in memory 354 to perform the operations described herein. In some implementations, processor 352 includes or corresponds to one or more of receive processor 238, transmit processor 220, and controller 240, and memory 354 includes or corresponds to memory 242. Memory 354 includes or is configured to store coverage enhancement logic 460.

Transmitter 356 is configured to transmit reference signals, synchronization signals, control information and data to one or more other devices, and receiver 358 is configured to receive reference signals, control information and data from one or more other devices. For example, transmitter 356 may transmit signaling, control information and data to, and receiver 358 may receive signaling, control information and data from UE 115. In some implementations, transmitter 356 and receiver 358 may be integrated in one or more transceivers. Additionally or alternatively, transmitter 356 or receiver 358 may include or correspond to one or more components of base station 105 described with reference to FIG. 2.

In aspects, coverage enhancement logic 360 may be configured to provide, in response to receiving an indication of a request for coverage enhancement from UE 115, coverage enhancement to transmissions to UE 115. In aspects, base station 105 may provide coverage enhancement by scheduling transmissions to the UE using coverage compensation (e.g. repetition, low-SE MCS, higher aggregation level, etc. ) .

In some implementations, wireless communications system 300 implements a 5G NR network. For example, wireless communications system 300 may include multiple 5G-capable UEs 115 and multiple 5G-capable base stations 105, such as UEs and base stations configured to operate in accordance with a 5G NR network protocol such as that defined by the 3GPP.

During operation of wireless communications system 300, UE 115 transmits indication of coverage enhancement request 370 to base station 105. In aspects, indication of coverage enhancement 370 is an indication to base station 105 of a request for coverage enhancement to be provided by base station 105. A discussion of further aspects related to indication of coverage enhancement request 370 now follows.

In aspects, UE 115 may determine to indicate a request for coverage enhancement to base station 105 based on various situations, conditions, and/or configurations. Specific details and/or examples related to the determination to indicate the request for coverage enhancement by UE 115 will be discussed below with respect to FIG. 6. In some aspects, the indication of the request for coverage enhancement to base station 105 may include indicating whether UE 115 is a RedCap UE or not, or may include indicating what type of RedCap UE the UE 115 is. As noted above, indicating whether UE 115 is a RedCap UE is important as this may allow base station to provide coverage enhancement to subsequent communications between base station 105 and UE 115. For example, base station 105 may perform transmissions to UE 115 using coverage compensation, such as retransmission repetition, low-SE MCS, higher aggregation level, etc. For example, in one particular example, base station 105 may provide coverage enhancement by configuring UE 115 (e.g., using Msg3 PUSCH transmission grants) to repeat a Msg3 PUSCH transmission a number of times. The number of repetitions may be based on the capabilities of the RedCap UE, as indicated in the request for coverage enhancement, or based on a predetermined configuration based on the type of RedCap UE.

In additional or alternative aspects, the indication of the request for coverage enhancement may include a request from UE 115 for one or more retransmission grants of a PRACH message (e.g., Msg3 PUSCH) transmitted to base station 105. For example, the indication of the request for coverage enhancement may indicate to base station 105 that UE 115 desires, or requests, to repeatedly retransmit the PRACH message (e.g., repeated retransmission) to enhance coverage. In some aspects, the indication of the request for coverage enhancement may indicate that UE 115 requests to repeat the retransmission of the PRACH message a specific number of times. The number of requested repetitions of the retransmission of the PRACH message may be indicated in the indication of the request for coverage enhancement transmitted to base station 105.

During operation, base station 105 transmits compensated data transmission 372 to UE 115. As noted above, base station 105 may provide coverage enhancement to communications between base station 105 and UE 115. Coverage enhancement by base station 105 may include transmitting data transmissions to UE 115 using coverage compensation, such as retransmission repetition, low-SE MCS, higher aggregation level, etc. For example, in one particular example, base station 105 may provide coverage enhancement by configuring UE 115 (e.g., using Msg3 PUSCH transmission grants) to repeat a Msg3 PUSCH transmission a number of times. The number of repetitions may be based on the capabilities of the UE, as indicated in the request for coverage enhancement, or may be based on a predetermined configuration based on the type of RedCap UE, or the level of enhancement requested in the indication for coverage enhancement.

Aspects of the present disclosure provide various techniques for indicating the request for coverage enhancement to the base station. FIGS. 4A-4C are diagrams illustrating an indication of a request for coverage enhancement by transmission of a PRACH message in a portion of a set of frequency domain resources available to the UE for transmission of a PRACH message. In these aspects, a UE may indicate a request for coverage enhancement to a base station by transmitting a message (e.g., a Msg3 PUSCH message) in a portion of the set of frequency domain resources granted to the UE by the base station for the transmission of the PRACH message. In some aspects, the location of the portion in the set of frequency domain resources used to transmit the message may be used to provide the indication.

FIG. 4A is a diagram illustrating a transmission of a RAR scheduled message (e.g., a Msg3 PUSCH message) in a typical case, such as in a transmission according to the current 5G NR standards. As shown in FIG. 4A, Msg3 PUSCH 400, which includes payload portion 412 and DMRS 410, may be transmitted in the entirety of set of frequency domain resources 416. In aspects, the set of frequency domain resources 416 may be the set of resource granted to the UE, such as in a RAR grant (e.g., receiving in a RAR Msg2) , by the base station for the transmission of Msg3 PUSCH. This is a standard configuration for a transmission of a Msg3 PUSCH from the UE to the base station.

FIG. 4B is a diagram illustrating an example of a transmission of a RAR scheduled message to indicate a request for coverage enhancement in accordance with aspects of the present disclosure. In particular, Msg3 PUSCH transmission 401 may be transmitted in a portion 412 of the set of frequency domain resources 416. As shown, portion 412 may be the second half of the set of frequency domain resources 416. By transmitting Msg3 PUSCH transmission 401 in portion of the set of frequency domain resources granted to the UE, the UE may indicate to the base station that the UE is requesting coverage enhancement from the base station. In these cases, when the base station receives the partial transmission of the Msg3 PUSCH transmission 401, the base station may determine that UE is requesting coverage enhancement.

In some aspects, the portion of the set of frequency domain resources 416 in which Msg3 PUSCH transmission 401 may be selected by the UE so as to indicate to the base station that the UE is requesting a specific level of coverage enhancement. For example, as shown, portion 412 in which Msg3 PUSCH transmission 401 may be transmitted may be the second half of the set of frequency domain resources 416. By scheduling Msg3 PUSCH transmission 401 in the second half of the set of frequency domain resources 416, the UE may indicate a request for a specific level of coverage enhancement. For example, scheduling Msg3 PUSCH transmission 401 in the second half of the set of frequency domain resources 416 may indicate that the UE is requesting a grant from the base station for a first number of Msg3 PUSCH retransmissions (e.g., any of 2, 4, 6, 8, etc. ) . In some aspects, scheduling Msg3 PUSCH transmission 401 in the second half of the set of frequency domain resources 416 may indicate to the base station that the UE is a particular type of RedCap UE. Further still, in some aspects, scheduling Msg3 PUSCH transmission 401 in the second half of the set of frequency domain resources 416 may indicate to the base station that the UE is a RedCap UE, while scheduling Msg3 PUSCH transmission 401 in the entire set of frequency domain resources 416 may indicate to the base station that the UE is not a RedCap UE.

In aspects, scheduling the Msg3 PUSCH transmission in a different half of the set of frequency domain resources 416 may indicate a different level of requested coverage enhancement. FIG. 4C is a diagram illustrating another example of a transmission of a RAR scheduled message to indicate a request for coverage enhancement in accordance with aspects of the present disclosure. In particular, Msg3 PUSCH transmission 402 may be transmitted in a portion 413 of the set of frequency domain resources 416. As shown, portion 413 in which Msg3 PUSCH transmission 402 may be transmitted may be the first half of the set of frequency domain resources 416, which is a different portion of the set of frequency domain resources than portion 412. By scheduling Msg3 PUSCH transmission 402 in the first half of the set of frequency domain resources 416, the UE may indicate a request for a specific level of coverage enhancement, different than the level of coverage enhancement requested in the example illustrated in FIG. 4B. For example, scheduling Msg3 PUSCH transmission 402 in the first half of the set of frequency domain resources 416 may indicate that the UE is requesting a grant from the base station for a second number of Msg3 PUSCH retransmission repetitions (e.g., any of 2, 4, 6, 8, etc. ) , the second number being different than the first number described with respect to FIG. 4B. In some aspects, scheduling Msg3 PUSCH transmission 402 in the first half of the set of frequency domain resources 416 may indicate to the base station that the UE is a particular type of RedCap UE, different than the type of RedCap indicated by the partial Msg3 PUSCH transmission 401 described with respect to FIG. 4B.

Although the discussion above has been focused on a partial transmission of the Msg3 PUSCH transmission using two halves of the set of frequency domain resources granted to the UE, it should be appreciated that more than two portion of the set of frequency domain resources may be used to indicate requests for different levels of enhancement. For example, the set of frequency domain resources may be divided into more than two portions and each portion may be used to indicate a different level of enhancement (e.g., a different number of requested repetitions and/or a different type of RedCap UE) .

In aspects, the requested level of coverage enhancement may be based on an estimate of a coverage-gap required relative to an initial transmission of the PRACH message. For example, the UE may transmit an initial transmission of a Msg3 PUSCH with a particular MCS. In aspects, the UE may determine a number of repetitions of a retransmission of the Msg3 PUSCH transmission based on the particular MCS used in the initial Msg3 PUSCH transmission. In aspects, a benefit of transmitting the Msg3 PUSCH in a portion of the set of frequency domain resources is that the PSD may be increased, which may cause an increase of the SNR for a power-limited uplink, and may be beneficial for soft combining with retransmissions.

In aspects of the present disclosure, a UE may indicate a request for coverage enhancement to a base station by scheduling and/or transmitting DMRS in a set of resources element that are different than the set of resource elements in which the DMRS is typically sent (e.g., transmitted in accordance with the standard 5G NR configuration) . FIGS. 5A and 5B are diagrams illustrating an indication of a request for coverage enhancement by transmission of a DMRS in a different set of resource elements. As shown in FIG. 5A, Msg3 PUSCH 501 includes payload portion 520. In addition, Msg3 PUSCH 501 may also include DMRS symbol 512 in which the DMRS is transmitted in resource element. In the example illustrated in FIG. 5A, the DMRS is scheduled and/or transmitted in a set of resource elements that includes DMRS resource elements 511. In this example, the set of resource elements in which the DMRS is scheduled and/or transmitted does not include, or excludes, DMRS resource elements 510. This is a standard configuration for a transmission of a DMRS of a Msg3 PUSCH from the UE to the base station.

FIG. 5B is a diagram illustrating an example of a transmission of a DMRS in a resource set configured to indicate a request for coverage enhancement in accordance with aspects of the present disclosure. As shown in FIG. 5B, DMRS 502 may be scheduled and/or transmitted in a set of resource elements that includes DMRS resource elements 510, instead of DMRS resource elements 511 as in the standard example illustrated in FIG. 5A. In this example, the set of resource elements in which the DMRS is scheduled and/or transmitted does not include, or excludes, DMRS resource elements 511. By transmitting the DMRS in a resource element set that is different than the resource set used on the standard DMRS transmission, the UE may indicate that the UE is requesting coverage enhancement from the base station. In these cases, when the base station receives the Msg3 PUSCH transmission with the DMRS in a different resource element set, the base station may determine that UE is requesting coverage enhancement.

In some aspects, the DMRS may be transmitted in a resource element set that is configured to include particular resource elements of the DMRS symbol. In this case, different resource element sets may be configured, for example, more than two different resource element sets, and each resource element set may be configured to indicate a different level of coverage enhancement requested. In these aspects, the UE may indicate a request for a particular level of coverage enhancement by transmitting the DMRS in a corresponding resource element set. In these cases, when the base station receives the Msg3 PUSCH transmission with the DMRS in the particular resource element set, the base station may determine that UE is requesting the corresponding level of coverage enhancement.

In aspects of the present disclosure, a UE may indicate a request for coverage enhancement to a base station by scheduling and/or transmitting the DMRS using a set of cyclic shifts that are different than the set of cyclic shifts typically used for DMRS transmission (e.g., a DMRS transmission in accordance with the standard 5G NR configuration) . In these aspects, the UE may indicate a request for coverage enhancement by using a cyclic shift for transmitting the DMRS that is different than the cyclic shifts typically used for DMRS transmission. In this case, when the base station receives the Msg3 PUSCH transmission with the DMRS encoded with a different cyclic shift than the cyclic shifts used in standard transmissions, the base station may determine that UE is requesting coverage enhancement.

In some aspects, different cyclic shifts may be configured to indicate different levels of coverage enhancement requested. In these cases, each of the different cyclic shifts may correspond to a different level of coverage enhancement. In these aspects, the UE may indicate a request for a particular level of coverage enhancement by transmitting the DMRS using a corresponding cyclic shift. In these cases, when the base station receives the Msg3 PUSCH transmission with the DMRS encoded with the particular cyclic shift, the base station may determine that UE is requesting the corresponding level of coverage enhancement.

In particular aspects, for example where an indication of a request for coverage enhancement includes an indication of more than one bit (e.g., where a level of coverage enhancement is requested rather than a binary request or no request) , multiple cyclic shifts may be used for transmitting the DMRS. In this manner, the level of coverage enhancement requested may correspond to the particular cyclic shift used. In aspects, the use of different cyclic shifts may be combined with the use of different resource elements, as discussed above with respect to FIGS. 5A and 5B to provide further flexibility for indicating not only a request for coverage enhancement, but also indicating requests for different levels of coverage enhancement.

In aspects, from a base station perspective, in order to determine the coverage enhancement request indication from the UE, the base station may have to correlate DMRS with different hypotheses, which may require a much lower SNR than decoding the DMRS, since non-coherent detection is sufficient for correlation, while decoding requires coherent detection and a higher SNR.

In aspects of the present disclosure, a UE may indicate a request for coverage enhancement to a base station by scheduling and/or transmitting an SRS as a substitute for a PRACH transmission (e.g., a Msg3 PUSCH transmission) . For example, the UE may indicate to the base station that the UE is requesting coverage enhancement by, instead of transmitting a Msg3 PUSCH transmission, the UE transmits an SRS. In this case, when the base station receives an SRS instead of the expected Msg3 PUSCH transmission, the base station may determine that UE is requesting coverage enhancement.

In some aspects, the UE may receive a RAR Msg2 from the base station. In the standard procedure, the UE is expected to transmit a Msg3 PUSCH in response. However, in accordance with aspects of the present disclosure. The UE may instead transmit an SRS to indicate to the base station a request for coverage enhancement. In aspects, the SRS may be configured based on system information and/or based on the grant content of the Msg2 transmission. For example, shown below in Table 1 is content of a RAR grant.

RAR grant field	Number of bits
Frequency hopping nag	1
PUSCH frequency resource allocation	14

PUSCH time resource allocation	4
MCS	4
TPC command for PUSCH	3
CSI Request (reserved)	1

Table 1 -RAR grant content

In aspects, the reserved CSI request field in the RAR grant may be re-interpreted as an SRS triggering and the configuration may be used to transmit the SRS.

In some aspects, the base station may obtain the uplink CSI and may use it to schedule a Msg3 PUSCH retransmission. If channel reciprocity holds, the uplink CSI may be used by the base station for PDCCH scheduling as well, which may provide an improvement to the reliability of Msg3 retransmission PDCCH, and Msg4 PDCCH/PDSCH.

In aspects, the UE (e.g., UE 115) may determine to indicate a request for coverage enhancement to a base station (e.g., base station 105) based on various situations, conditions, and/or configurations. In some aspects, the UE may determine to indicate a request for coverage enhancement to the base station based on the capabilities of the UE. For example, a RedCap UE may determine to indicate a request for coverage enhancement (e.g., to indicate that the UE is a RedCap UE, to indicate a type of RedCap UE, and/or to request PRACH message retransmission repetition) . Similarly a normal UE may determine to indicate a request for coverage enhancement to request retransmission repetition of a PRACH PUSCH message.

In some aspects, the UE may determine to indicate a request for coverage enhancement to a base station based on a triggering condition. FIG. 6 is a diagram illustrating an example of a triggering condition for indicating a request for coverage enhancement in accordance with aspects of the present disclosure. FIG. 6 illustrates communication between UE 115 and base station 105. In particular, a RAR message (e.g., RAR Msg2) may be transmitted by base station 105 to UE 115. The RAR message may include a RAR grant for a PRACH PUSCH transmission (e.g., Msg3 PUSCH) from UE 115. The RAR grant contents are described in Table 1 above. In particular, the RAR grant may include a TPC command indicating a power offset to be used by UE 115 in the Msg3 PUSCH transmission. In aspects, the power offset may be a power offset relative to a transmission power of the PRACH preamble (Msg1) 611. UE 115 may determine whether to indicate a request for coverage enhancement to the base station based on whether applying the power offset to the Msg3 PUSCH transmission results in a transmission power for the Msg3 PUSCH transmission that exceeds a maximum power (P _CMAX) supported by UE 115. For example, as shown in FIG. 6, UE 115 may have a P _CMAX 610.

In one example, the power offset may be offset 630. In aspects, UE 115 may determine that application of offset 630 to PRACH preamble transmission power 611 would result in total transmission power 620 for the Msg3 PUSCH transmission, and this transmission power 620 would exceed PCMAX 610. Accordingly, UE 115 determines that offset 630 may not be applied as a transmission from UE 115 may not exceed PCMAX 610. As a result of transmission power 620 exceeding P _CMAX 610, UE 115 may determine to indicate a request for coverage enhancement to base station 105.

In other examples, the power offset indicated in the TPC may be offset 631 or offset 632. UE 115 may determine that applying offset 631 to PRACH preamble transmission power 611 results in total transmission power 621 which is the same as P _CMAX 610, and that applying offset 632 to PRACH preamble transmission power 611 results in total transmission power 622 which is less than P _CMAX 610. In both cases, the UE 115 does not determine to indicate a request for coverage enhancement to base station 105.

In some aspects, the triggering condition may be the UE determining that an RSRP measurement is below a predetermined threshold. In this cases, a UE may obtain a measurement of an RSRP for a transmission (e.g., a RAR message such as a RAR Msg2) received from a base station. The UE may compare the measured RSRP against the predetermined threshold. In aspects, in response to a determination that the RSRP measurement is below the predetermined threshold, the UE may determine to indicate a request for coverage enhancement to the base station. In aspects, in response to a determination that the RSRP measurement is not below the predetermined threshold, the UE may not determine to indicate a request for coverage enhancement to the base station.

FIG. 7 is a flow diagram illustrating an example process 700 that supports indication of a request for coverage enhancement from a UE to a base station according to one or more aspects of the present disclosure. Operations of process 700 may be performed by a UE, such as UE 115 described above with reference to FIGs. 1-6, or a UE described with reference to FIG. 9. For example, example operations (also referred to as “blocks” ) of process 700 may enable UE 115 to support indication of a request for coverage enhancement from a UE to a base station in accordance with aspects of the present disclosure.

FIG. 9 is a block diagram illustrating UE 115 configured according to one aspect of the present disclosure. UE 115 includes the structure, hardware, and components as illustrated for UE 115 of FIG. 2. For example, UE 115 includes controller/processor 280, which operates to execute logic or computer instructions stored in memory 282, as well as controlling the components ofUE 115 that provide the features and functionality ofUE 115. UE 115, under control of controller/processor 280, transmits and receives signals via wireless radios 901a-r and antennas 252a-r. Wireless radios 901a-r includes various components and hardware, as illustrated in FIG. 2 for UE 115, including modulator/demodulators 254a-r, MIMO detector 256, receive processor 258, transmit processor 264, and TX MIMO processor 266.

At block 702, UE 115 determines to indicate a request for coverage enhancement to a base station. In order to implement the functionality for such operations, UE 115, under control of controller/processor 280, executes coverage enhancement request logic 902, stored in memory 282. The functionality implemented through the execution environment of coverage enhancement request logic 902 allows for UE 115 to perform coverage enhancement request indication operations according to the various aspects herein.

In aspects, determining to indicate the request for coverage enhancement may include determining whether a triggering condition exists. In aspects, a triggering condition may be determined by the UE when the UE determines that applying a power offset received in a TPC command from the base station to a scheduled PRACH PUSCH transmission (e.g., the Msg3 PUSCH transmission) would result in a transmission power for the PRACH message transmission that would exceed the maximum power supported by the UE. In this case, the UE may decide to request coverage enhancement (e.g., retransmission grants and/or transmission compensation) from the base station.

In some aspects, a triggering condition may be determined by the UE when the UE determines an RSRP measurement is below a predetermined threshold. For example, as noted above, the UE may measure the RSRP of a RAR transmission received from a base station. The UE may determine that the measured RSRP is below a predetermined threshold. In aspects, in response to a determination that the RSRP measurement is below the predetermined threshold, the UE may determine to indicate a request for coverage enhancement to the base station. In aspects, in response to a determination that the RSRP measurement is not below the predetermined threshold, the UE may not determine to indicate a request for coverage enhancement to the base station.

In aspects, the UE may be a RedCap UE, and the indication of the request for coverage enhancement may include an indication to the base station that the UE is a RedCap UE. In some aspects, the indication of the request for coverage enhancement may include an indication indicating which type of RedCap UE the UE is. In aspects, the requested enhanced coverage may include coverage compensation that may include one or more of: message repetition, a low SE MCS, and/or a higher aggregation level. In some aspects, the indication of the request for coverage enhancement includes a request for a grant of at least one repetition of a retransmission of a PRACH transmission (e.g., the Msg3 PUSCH transmission) .

At block 704, UE 115 generates an indication of the request for coverage enhancement. In order to implement the functionality for such operations, UE 115, under control of controller/processor 280, executes coverage enhancement request logic 902, stored in memory 282. The functionality implemented through the execution environment of coverage enhancement request logic 902 allows for UE 115 to perform coverage enhancement request indication generation operations according to the various aspects herein.

In aspects, generating the indication of the request for coverage enhancement may include transmitting a message (e.g., a RAR scheduled PRACH message) in a portion of the set of frequency domain resources granted to the UE, by the base station, for the transmission of the PRACH message. In aspects, the portion of the set of frequency domain resources may be selected based on the request for coverage enhancement. For example, the partial transmission of the RAR scheduled message by the UE may indicate to the base station that the UE is requesting coverage enhancement. In some aspects, the location of the portion of the set of frequency domain resources in which the RAR scheduled message is transmitted by the UE may indicate the level of coverage enhancement requested by the UE. In these cases, transmitting the RAR scheduled message in a portion located in a first location of the set of frequency domain resources may indicate a request for a first level of coverage enhancement, and transmitting the RAR scheduled message in a portion located in a second location of the set of frequency domain resources may indicate a request for a second level of coverage enhancement.

In some aspects, generating the indication of the request for coverage enhancement may include scheduling and/or transmitting a DMRS in a set of resource elements different than the standard set of resource elements. In some aspects, generating the indication of the request for coverage enhancement may include scheduling and/or transmitting the DMRS using a set of cyclic shifts different than the standard set of cyclic shifts, and/or scheduling and/or transmitting an SRS as a substitute for a PRACH PUSCH transmission (e.g., a Msg3 PUSCH transmission) .

At block 706, UE 115 sends the indication of the request for coverage enhancement to the base station. In order to implement the functionality for such operations, UE 115, under control of controller/processor 280, executes transmission logic 904, stored in memory 282. The functionality implemented through the execution environment of transmission logic 904 allows for UE 115 to perform indication of the request for coverage enhancement transmission operations according to the various aspects herein.

FIG. 8 is a flow diagram illustrating an example process 800 that supports indication of a request for coverage enhancement from a UE to a base station according to one or more aspects of the present disclosure. Operations of process 800 may be performed by a base station, such as base station 105 described above with reference to FIGs. 1-6 or a base station as described above with reference to FIG. 10. For example, example operations of process 800 may enable base station 105 to supports indication of a request for coverage enhancement from a UE to a base station according to one or more aspects of the present disclosure.

FIG. 10 is a block diagram illustrating base station 105 configured according to one aspect of the present disclosure. Base station 105 includes the structure, hardware, and components as illustrated for base station 105 of FIG. 2. For example, base station 105 includes controller/processor 240, which operates to execute logic or computer instructions stored in memory 242, as well as controlling the components of base station 105 that provide the features and functionality of base station 105. Base station 105, under control of controller/processor 240, transmits and receives signals via wireless radios 1001a-t and antennas 234a-t. Wireless radios 1001a-t includes various components and hardware, as illustrated in FIG. 2 for base station 105, including modulator/demodulators 232a-t, MIMO detector 236, receive processor 238, transmit processor 220, and TX MIMO processor 230.

At block 802, base station 105 receives an indication of a request for coverage enhancement from UE 115. In order to implement the functionality for such operations, base station 115, under control of controller/processor 240, executes transmission and reception logic 1004, stored in memory 242. The functionality implemented through the execution environment of transmission and reception logic 1004 allows for base station 105 to perform indication of the request for coverage enhancement transmission operations according to the various aspects herein. In aspects, the indication of a request for coverage enhancement may be an indication as described above with respect to FIGS. 3-7.

At block 804, base station 105 applies coverage enhancement to at least one data transmission to the UE in response to receiving the indication of the request for coverage enhancement from the UE. In order to implement the functionality for such operations, base station 115, under control of controller/processor 240, executes coverage enhancement logic 1002, stored in memory 242. The functionality implemented through the execution environment of coverage enhancement logic 1002 allows for base station 105 to perform coverage enhancement application operations according to the various aspects herein.

In aspects, base station 105 may apply coverage enhancement by enhancing communications between base station 105 and UE 115. In aspects, coverage enhancement by may include transmitting data transmissions to UE 115 using coverage compensation, such as retransmission repetition, low-SE MCS, higher aggregation level, etc. For example, in one particular example, base station 105 may provide coverage enhancement by configuring UE 115 (e.g., using Msg3 PUSCH transmission grants) to repeat a Msg3 PUSCH transmission a number of times. The number of repetitions may be based on the capabilities of the UE, as indicated in the request for coverage enhancement, or may be based on a predetermined configuration based on the type of RedCap UE, or the level of enhancement requested in the indication for coverage enhancement.

At block 806, base station 105 transmits the enhanced at least one data transmission to UE 115. In order to implement the functionality for such operations, base station 115, under control of controller/processor 240, executes transmission and reception logic 1004, stored in memory 242. The functionality implemented through the execution environment of transmission and reception logic 1004 allows for base station 105 to perform enhanced data transmission operations according to the various aspects herein.

Those of skill in the art would understand that information and signals may be represented using any of a variety of different technologies and techniques. For example, data, instructions, commands, information, signals, bits, symbols, and chips that may be referenced throughout the above description may be represented by voltages, currents, electromagnetic waves, magnetic fields or particles, optical fields or particles, or any combination thereof.

The functional blocks and modules in FIGS. 3, and 7-10 may comprise processors, electronics devices, hardware devices, electronics components, logical circuits, memories, software codes, firmware codes, etc., or any combination thereof. Software shall be construed broadly to mean instructions, instruction sets, code, code segments, program code, programs, subprograms, software modules, application, software applications, software packages, routines, subroutines, objects, executables, threads of execution, procedures, and/or functions, among other examples, whether referred to as software, firmware, middleware, microcode, hardware description language or otherwise.

Those of skill would further appreciate that the various illustrative logical blocks, modules, circuits, and algorithm steps described in connection with the disclosure herein may be implemented as electronic hardware, computer software, or combinations of both. To clearly illustrate this interchangeability of hardware and software, various illustrative components, blocks, modules, circuits, and steps have been described above generally in terms of their functionality. Whether such functionality is implemented as hardware or software depends upon the particular application and design constraints imposed on the overall system. Skilled artisans may implement the described functionality in varying ways for each particular application, but such implementation decisions should not be interpreted as causing a departure from the scope of the present disclosure. Skilled artisans will also readily recognize that the order or combination of components, methods, or interactions that are described herein are merely examples and that the components, methods, or interactions of the various aspects of the present disclosure may be combined or performed in ways other than those illustrated and described herein.

The various illustrative logical blocks, modules, and circuits described in connection with the disclosure herein may be implemented or performed with a general-purpose processor, a digital signal processor (DSP) , an application specific integrated circuit (ASIC) , a field programmable gate array (FPGA) or other programmable logic device, discrete gate or transistor logic, discrete hardware components, or any combination thereof designed to perform the functions described herein. A general-purpose processor may be a microprocessor, but in the alternative, the processor may be any conventional processor, controller, microcontroller, or state machine. A processor may also be implemented as a combination of computing devices, e.g., a combination of a DSP and a microprocessor, a plurality of microprocessors, one or more microprocessors in conjunction with a DSP core, or any other such configuration.

The steps of a method or algorithm described in connection with the disclosure herein may be embodied directly in hardware, in a software module executed by a processor, or in a combination of the two. A software module may reside in RAM memory, flash memory, ROM memory, EPROM memory, EEPROM memory, registers, hard disk, a removable disk, a CD-ROM, or any other form of storage medium known in the art. An exemplary storage medium is coupled to the processor such that the processor can read information from, and write information to, the storage medium. In the alternative, the storage medium may be integral to the processor. The processor and the storage medium may reside in an ASIC. The ASIC may reside in a user terminal. In the alternative, the processor and the storage medium may reside as discrete components in a user terminal.

In one or more exemplary designs, the functions described may be implemented in hardware, software, firmware, or any combination thereof. If implemented in software, the functions may be stored on or transmitted over as one or more instructions or code on a computer-readable medium. Computer-readable media includes both computer storage media and communication media including any medium that facilitates transfer of a computer program from one place to another. Computer-readable storage media may be any available media that can be accessed by a general purpose or special purpose computer. By way of example, and not limitation, such computer-readable media can comprise RAM, ROM, EEPROM, CD-ROM or other optical disk storage, magnetic disk storage or other magnetic storage devices, or any other medium that can be used to carry or store desired program code means in the form of instructions or data structures and that can be accessed by a general-purpose or special-purpose computer, or a general-purpose or special-purpose processor. Also, a connection may be properly termed a computer-readable medium. For example, if the software is transmitted from a website, server, or other remote source using a coaxial cable, fiber optic cable, twisted pair, or digital subscriber line (DSL) , then the coaxial cable, fiber optic cable, twisted pair, or DSL, are included in the definition of medium. Disk and disc, as used herein, includes compact disc (CD) , laser disc, optical disc, digital versatile disc (DVD) , floppy disk and blu-ray disc where disks usually reproduce data magnetically, while discs reproduce data optically with lasers. Combinations of the above should also be included within the scope of computer-readable media.

As used herein, including in the claims, the term “and/or, ” when used in a list of two or more items, means that any one of the listed items can be employed by itself, or any combination of two or more of the listed items can be employed. For example, if a composition is described as containing components A, B, and/or C, the composition can contain A alone; B alone; C alone; A and B in combination; A and C in combination; B and C in combination; or A, B, and C in combination. Also, as used herein, including in the claims, “or” as used in a list of items prefaced by “at least one of” indicates a disjunctive list such that, for example, a list of “at least one of A, B, or C” means A or B or C or AB or AC or BC or ABC (i.e., A and B and C) or any of these in any combination thereof.

The previous description of the disclosure is provided to enable any person skilled in the art to make or use the disclosure. Various modifications to the disclosure will be readily apparent to those skilled in the art, and the generic principles defined herein may be applied to other variations without departing from the spirit or scope of the disclosure. Thus, the disclosure is not intended to be limited to the examples and designs described herein but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

WHAT IS CLAIMED IS:

Claims

A method of wireless communication, comprising:

determining, by a user equipment (UE) , to indicate a request for coverage enhancement to a base station;

generating, by the UE, an indication of the request for coverage enhancement; and

sending the indication of the request for coverage enhancement to the base station.
The method of claim 1, wherein the enhanced coverage includes coverage compensation including one or more of: message repetition, a low spectral efficiency (SE) modulation and coding scheme (MCS) , and a higher aggregation level.
The method of any of claims 1 and 2, wherein the indication of the request for coverage enhancement includes a request for at least one retransmission grant of a physical random access channel (PRACH) message.
The method of claim 3, wherein the PRACH message is a message 3 (Msg3) physical uplink shared channel (PUSCH) message.
The method of any of claims 1-4, wherein generating the indication of the request for coverage enhancement includes:

receiving, by the UE, a random access response (RAR) message from the base station, the RAR message including a grant for a transmission of physical random access channel (PRACH) message in a set of frequency domain resources, and

transmitting, by the UE, the PRACH message in a portion of the set of frequency domain resources, wherein the portion of the set of frequency domain resources is selected based on the request for coverage enhancement.
The method of claim 5, wherein transmitting the PRACH message in the portion of the set of frequency domain resources includes transmitting the PRACH message with a maximum transmission power supported by the UE.
The method of any of claims 5 and 6, wherein a location of the portion of the set of frequency domain resources selected for transmitting the PRACH message indicates a level of coverage enhancement requested.
The method of any of claims 5-7, wherein selecting a first portion in a first location of the set of frequency domain resources for transmitting the PRACH message indicates a request for a first level of coverage enhancement, and selecting a second portion in a second location of the set of frequency domain resources different than the first location for transmitting the PRACH message indicates a request for a second level of coverage enhancement.
The method of any of claims 5-8, wherein the request for coverage enhancement includes a request for at least one retransmission grant of the PRACH message, and wherein the level of coverage enhancement requested indicates a number of repetitions of the at least one retransmission grant of the PRACH message requested from the base station.
The method of any of claims 5-9, further comprising:

calculating, by the UE, the number of repetitions of the at least one retransmission grant of the PRACH message requested from the base station based on an estimate of a coverage-gap required relative to an initial transmission of the PRACH message.
The method of any of claims 1-10, wherein generating the indication of the request for coverage enhancement includes one or more of:

transmitting a demodulation references signal (DMRS) in a first set of resource elements of the DMRS symbol, wherein the first set of resource elements includes different resource elements than a standard set of resource elements in which the DMRS is sent; and

transmitting the DMRS using a first set of cyclic shifts, wherein the first set of cyclic shifts include different cyclic shifts than a standard set of cyclic shifts used for standard transmission of the DMRS.
The method of any of claims 1-11, wherein generating the indication of the request for coverage enhancement includes:

transmitting a sounding reference signal (SRS) as a substitute for a transmission of a physical random access channel (PRACH) message, wherein receiving the SRS indicates to the base station that the UE is requesting coverage enhancement.
The method of claim 12, wherein a resource for the SRS is configured by one of:

a system information message;

a random access response (RAR) message.
The method of any of claims 1-13, wherein determining to indicate a request for coverage enhancement to the base station includes:

receiving a transmit power control (TPC) command in a random access response (RAR) message from the base station, the TPC command indicating a power offset; and

determining that applying the power offset to a transmission of a physical random access channel (PRACH) message results in a transmission power for the PRACH message transmission exceeding a maximum power supported by the UE.
The method of any of claims 1-14, wherein determining to indicate a request for coverage enhancement to the base station includes:

measuring a reference signal received power (RSRP) for a transmission received from the base station; ; and

determining that the RSRP measurement is below a threshold.
The method of any combination of claims 1-15.
A method of wireless communication, comprising:

receiving, by a base station from a user equipment, an indication of a request for coverage enhancement;

applying coverage enhancement, by the base station, in response to receiving the indication of the request for coverage enhancement, to at least one data transmission to the UE;

transmitting, by the base station, the enhanced at least one data transmission to the UE.
The method of claim 17, wherein applying coverage enhancement to the at least one data transmission to the UE includes:

scheduling the at least one data transmission using one or more of: message repetition, a low spectral efficiency (SE) modulation and coding scheme (MCS) , and a higher aggregation level.
The method of any of claims 17 and 18, wherein the indication of the request for coverage enhancement includes a request for at least one retransmission grant of a physical random access channel (PRACH) message.
The method of claim 19, wherein the PRACH message is a message 3 (Msg3) physical uplink shared channel (PUSCH) message.
The method of any of claims 17-20, further comprising:

transmitting, by the base station, a random access response (RAR) message including a grant for a transmission of physical random access channel (PRACH) message in a set of frequency domain resources to the UE, wherein receiving the indication of the request for coverage enhancement includes receiving the PRACH message in a portion of the set of frequency domain resources, the portion being a subset of the set of frequency domain resources.
The method of claim 21, wherein a location of the portion of the set of frequency domain resources in which the PRACH message is received indicates a level of coverage enhancement requested by the UE.
The method of any of claims 21 and 22, wherein receiving the PRACH message in a first portion in a first location of the set of frequency domain resources indicates a request for a first level of coverage enhancement, and wherein receiving the PRACH message in a second portion in a second location of the set of frequency domain resources different than the first location indicates a request for a second level of coverage enhancement.
The method of any of claims 21-23, includes a request for at least one retransmission grant of the PRACH message, and wherein the level of coverage enhancement requested indicates a number of repetitions of the at least one retransmission grant of the PRACH message requested by the UE.
The method of any of claims 21-24, wherein the number of repetitions of the at least one retransmission grant of the PRACH message requested by the UE is calculated based on an estimate of a coverage-gap required relative to an initial transmission of the PRACH message.
The method of any of claims 17-25, wherein receiving the indication of the request for coverage enhancement includes one or more of:

receiving a demodulation references signal (DMRS) in a first set of resource elements of the DMRS symbol, wherein the first set of resource elements includes different resource elements than a standard set of resource elements in which the DMRS is received in a standard transmission;

receiving the DMRS, wherein the DMRS is transmitted by the UE using a first set of cyclic shifts, wherein the first set of cyclic shifts include different cyclic shifts than a standard set of cyclic shifts used for standard transmission of the DMRS; and

receiving a sounding reference signal (SRS) as a substitute for a physical random access channel (PRACH) message, wherein receiving the SRS indicates to the base station that the UE is requesting coverage enhancement.
The method of any combination of claims 17-26.
An apparatus configured for wireless communication, the apparatus comprising:

at least one processor; and

a memory coupled to the at least one processor, wherein the at least one processor is configured to perform each of the steps of any one of the method claims 1–27.
An apparatus configured for wireless communication, comprising means for implementing each of the steps of any one of the method claims 1–27.
A non-transitory computer-readable medium having program code recorded thereon, the program code comprising instructions executable by a processor to cause the processor to perform each of the steps of any one of the method claims 1–27.