WO2024040461A1

WO2024040461A1 - Stage two sidelink control information (sci-2) for partial transmission during wideband operation in unlicensed spectrum

Info

Publication number: WO2024040461A1
Application number: PCT/CN2022/114470
Authority: WO
Inventors: Luanxia YANG; Changlong Xu; Jing Sun; Xiaoxia Zhang; Chih-Hao Liu; Shaozhen GUO; Siyi Chen; Hao Xu
Original assignee: Qualcomm Incorporated
Priority date: 2022-08-24
Filing date: 2022-08-24
Publication date: 2024-02-29

Abstract

A method for wireless communication by a sidelink transmitting device includes performing a clear channel assessment (CCA) for each of a number of unlicensed sub-bands in a wideband carrier. The method also includes determining whether at least one of the unlicensed sub-bands is occupied. The method further includes transmitting a partial physical sidelink shared channel (PSSCH) along with a stage two sidelink control information (SCI-2) across the wideband carrier based on the determining.

Description

STAGE TWO SIDELINK CONTROL INFORMATION (SCI-2) FOR PARTIAL TRANSMISSION DURING WIDEBAND OPERATION IN UNLICENSED SPECTRUM

FIELD OF THE DISCLOSURE

The present disclosure relates generally to wireless communications, and more specifically to a stage two sidelink control information (SCI-2) enhancement for partial transmission during wideband operation in unlicensed sidelink spectrum (SL-U) .

BACKGROUND

Wireless communications systems are widely deployed to provide various telecommunications services such as telephony, video, data, messaging, and broadcasts. Typical wireless communications systems may employ multiple-access technologies capable of supporting communications with multiple users by sharing available system resources. Examples of such multiple-access technologies include code division multiple access (CDMA) systems, time division multiple access (TDMA) systems, frequency division multiple access (FDMA) systems, orthogonal frequency division multiple access (OFDMA) systems, single-carrier frequency division multiple access (SC-FDMA) systems, and time division synchronous code division multiple access (TD-SCDMA) systems. In some cases, a wireless communications system may support communications using an unlicensed radio frequency spectrum band.

These multiple access technologies have been adopted in various telecommunications standards to provide a common protocol that enables different wireless devices to communicate on a municipal, national, regional, and even global level. An example telecommunications standard is fifth generation (5G) new radio (NR) . 5G NR is part of a continuous mobile broadband evolution promulgated by Third Generation Partnership Project (3GPP) to meet new requirements associated with latency, reliability, security, scalability (e.g., with Internet of Things (IoT) ) , and other requirements. 5G NR includes services associated with enhanced mobile broadband (eMBB) , massive machine type communications (mMTC) , and ultra-reliable low latency communications (URLLC) . Some aspects of 5G NR may be based on the fourth generation (4G) long term evolution (LTE) standard. Narrowband (NB) -IoT and enhanced machine-type communications (eMTC) are a set of enhancements to LTE for machine type communications. There exists a need for further improvements in 5G NR technology. These improvements may also be applicable to other multi-access technologies and the telecommunications standards that employ these technologies.

Wireless communications systems may include or provide support for various types of communications systems, such as vehicle related cellular communications systems (e.g., cellular vehicle-to-everything (CV2X) communications systems) . Vehicle related communications systems may be used by vehicles to increase safety and to help prevent collisions of vehicles. Information regarding inclement weather, nearby accidents, road conditions, and/or other information may be conveyed to a driver via the vehicle related communications system. In some cases, sidelink user equipment (UEs) , such as vehicles, may communicate directly with each other using device-to-device (D2D) communications over a D2D wireless link. These communications can be referred to as sidelink communications.

SUMMARY

In aspects of the present disclosure, a method for wireless communication by a sidelink transmitting device includes performing a clear channel assessment (CCA) for each of a number of unlicensed sub-bands in a wideband carrier. The method also includes determining whether at least one of the unlicensed sub-bands is occupied. The method further includes transmitting a partial physical sidelink shared channel (PSSCH) along with a stage two sidelink control information (SCI-2) across the wideband carrier based on the determining.

Other aspects of the present disclosure are directed to an apparatus. The apparatus has a memory and one or more processors coupled to the memory. The processor (s) is configured to perform a clear channel assessment (CCA) for each of a number of unlicensed sub-bands in a wideband carrier. The processor (s) is also configured to determine whether at least one of the unlicensed sub-bands is occupied. The processor (s) is further configured to transmit a partial physical sidelink shared channel (PSSCH) along with a stage two sidelink control information (SCI-2) across the wideband carrier based on the determining.

Other aspect of the present disclosure are directed to an apparatus. The apparatus includes means for performing a clear channel assessment (CCA) for each of a number of unlicensed sub-bands in a wideband carrier. The apparatus also includes means for determining whether at least one of the unlicensed sub-bands is occupied. The apparatus further includes means for transmitting a partial physical sidelink shared channel (PSSCH) along with a stage two sidelink control information (SCI-2) across the wideband carrier based on the determining.

Aspects generally include a method, apparatus, system, computer program product, non-transitory computer-readable medium, user equipment, base station, wireless communications device, and processing system as substantially described with reference to and as illustrated by the accompanying drawings and specification.

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. 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, 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 purposes of illustration and description, and not as a definition of the limits of the claims.

BRIEF DESCRIPTION OF THE DRAWINGS

So that features of the present disclosure can be understood in detail, a particular description may be had by reference to aspects, some of which are illustrated in the appended drawings. It is to be noted, however, that the appended drawings illustrate only certain aspects of this disclosure and are therefore not to be considered limiting of its scope, for the description may admit to other equally effective aspects. The same reference numbers in different drawings may identify the same or similar elements.

FIGURE 1 illustrates an example of a wireless communications system that supports techniques for partial sidelink transmission using wideband operations in accordance with one or more aspects of the present disclosure.

FIGURE 2 illustrates an example of a network architecture that supports techniques for partial sidelink transmission using wideband operations in accordance with one or more aspects of the present disclosure.

FIGURE 3 illustrates an example of a wireless communications system that supports techniques for partial sidelink transmission using wideband operations in accordance with one or more aspects of the present disclosure.

FIGURES 4-6, 7A, and 7B each illustrate an example of a wideband carrier diagram that supports techniques for partial sidelink transmission using wideband operations in accordance with one or more aspects of the present disclosure.

FIGURE 8 is a block diagram illustrating sidelink time/frequency structures, in accordance with one or more aspects of the present disclosure.

FIGURE 9 is a block diagram illustrating stage two sidelink control information (SCI-2) transmission with a lower coding rate, in accordance with one or more aspects of the present disclosure.

FIGURE 10 is a table illustrating an example of a mapping between coding rate and maximum number of allowed listen-before-talk (LBT) failures, in accordance with one or more aspects of the present disclosure.

FIGURES 11A and 11B show block diagrams illustrating stage two sidelink control information (SCI-2) transmission with a redefined mapping, in accordance with one or more aspects of the present disclosure.

FIGURES 12A and 12B are block diagrams illustrating stage two sidelink control information (SCI-2) transmission with a redefined mapping and a higher coding rate for the SCI-2, in accordance with one or more aspects of the present disclosure.

FIGURE 13 is a block diagram illustrating stage two sidelink control information (SCI-2) transmission with a distributed mapping for the SCI-2, in accordance with one or more aspects of the present disclosure.

FIGURE 14 is a block diagram illustrating stage two sidelink control information (SCI-2) transmission with a distributed mapping for the SCI-2, in accordance with one or more aspects of the present disclosure.

FIGURE 15 is a flow diagram illustrating an example process performed, for example, by a sidelink transmitting device, in accordance with one or more aspects of the present disclosure.

DETAILED DESCRIPTION

Various aspects of the disclosure are described more fully below with reference to the accompanying drawings. This disclosure may, however, be embodied in many different forms and should not be construed as limited to any specific structure or function presented throughout this disclosure. Rather, these aspects are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the disclosure to those skilled in the art. Based on the teachings, one skilled in the art should appreciate that the scope of the disclosure is intended to cover any aspect of the disclosure disclosed, whether implemented independently of or combined with any other aspect of the disclosure. For example, an apparatus may be implemented or a method may be practiced using any number of the aspects set forth. In addition, the scope of the disclosure is intended to cover such an apparatus or method, which is practiced using other structure, functionality, or structure and functionality in addition to or other than the various aspects of the disclosure set forth. It should be understood that any aspect of the disclosure disclosed may be embodied by one or more elements of a claim.

Several aspects of telecommunications systems will now be presented with reference to various apparatuses and techniques. These apparatuses and techniques will be described in the following detailed description and illustrated in the accompanying drawings by various blocks, modules, components, circuits, steps, processes, algorithms, and/or the like (collectively referred to as “elements” ) . These elements may be implemented using hardware, software, or combinations thereof. Whether such elements are implemented as hardware or software depends upon the particular application and design constraints imposed on the overall system.

It should be noted that while aspects may be described using terminology associated with 5G wireless technologies, aspects of the present disclosure can be applied in later generations, including for 6G wireless technologies, or in other wireless communications systems.

In cellular communications networks, wireless devices may generally communicate with each other via access links with one or more network entities such as a base station or scheduling entity. Some cellular networks may also support device-to-device (D2D) communications that enable discovery of, and communications among, nearby devices using direct links between devices (for example, without passing through a base station, relay, or other network entity) . D2D communications may also be referred to as point-to-point (P2P) or sidelink communications. D2D communications may be implemented using licensed or unlicensed bands. Using D2D communications, devices can avoid some of the overhead that would otherwise be involved with routing to and from a network entity. D2D communications can also enable mesh networking and device-to-network relay functionality.

Vehicle-to-everything (V2X) communication is an example of D2D communication that is specifically geared toward automotive use cases. V2X communications may enable autonomous vehicles to communicate with each other. In some examples, V2X communications may enable a group of autonomous vehicles to share respective sensor information. For example, each autonomous vehicle may include multiple sensors or sensing technologies (for example, light detection and ranging (LiDAR) , radar, cameras, etc. ) . In most cases, an autonomous vehicle’s sensors are limited to detecting objects within the sensors’ line of sight. In contrast, based on the sensor information shared via V2X communications, one or more autonomous vehicles in the group of autonomous vehicles may be made aware of an out of sight object. In such examples, the object may be within a line of sight of sensors associated with another autonomous vehicle in the group of autonomous vehicles. Additionally, or alternatively, based on the sensor information shared via V2X communications, two or more autonomous vehicle in the group of autonomous vehicles may coordinate one or more actions, such as avoiding the object or maintaining a pre-determined distance between the two or more autonomous vehicles.

Sidelink (SL) communication is another example of D2D communication that enables a user equipment (UE) to communicate with another UE without tunneling through a base station and/or a core network. Sidelink communications can be communicated over a physical sidelink control channel (PSCCH) and a physical sidelink shared channel (PSSCH) . The PSCCH and PSSCH are similar to a physical downlink control channel (PDCCH) and a physical downlink shared channel (PDSCH) in downlink (DL) communications between a base station and a UE. For instance, the PSCCH may carry sidelink control information (SCI) and the PSCCH may carry sidelink data (for example, user data) . Each PSCCH is associated with a corresponding PSSCH, where SCI in a PSCCH may carry reservation and/or scheduling information for a sidelink data transmission in the associated PSSCH. Use cases for sidelink communications may include, among others, V2X, industrial Internet of Things (IoT) (IIoT) , and/or NR-lite.

In some examples, the wireless communications system may support communications using an unlicensed radio frequency spectrum band that may be shared with one or more other radio access technologies (RATs) , such as one or both of Wi-Fi or Bluetooth, among other examples. In such examples, prior to transmitting communications using the unlicensed radio frequency spectrum band, a communication device (e.g., a network entity, a UE) may perform a channel access procedure to gain access to a communication channel (e.g., frequency resources) of the unlicensed radio frequency spectrum band. The communication device may support wideband operations in which a carrier (e.g., a wideband carrier) of the unlicensed radio frequency spectrum band may include multiple bandwidths. In some examples, the communication device may perform wideband operations using a network access link (e.g., a Uu interface) . In such examples, the communication device may perform a channel access procedure for multiple bandwidths of the carrier and may transmit communications using bandwidths in which the respective channel access procedure is successful.

In some other examples, the communication device may perform wideband operations using a sidelink (e.g., a PC5 interface) . In such examples, the communication device may transmit sidelink control information (SCI) that may include information regarding resource allocation for subsequent sidelink transmissions (e.g., data transmissions) . For example, the SCI may include an indication (e.g., a reservation announcement) of one or more resources that the UE may intend to use (e.g., may have reserved) for transmitting one or more portions of sidelink message using one or more bandwidths of the carrier. In some examples, the communication device may use a particular bandwidth of the wideband carrier to transmit the SCI. As such, if a channel access procedure performed for the bandwidth in which the SCI is to be transmitted fails, the SCI may not be transmitted at the communication device. In such examples, another communication device (e.g., a receiving device) may be incapable of determining which resources are to be used at the communication device for transmitting the one or more portions of the sidelink message.

A physical sidelink shared channel (PSSCH) may be multiplexed with a second stage sidelink control information message (SCI-2) . In some implementations, an SCI-2 is mapped to contiguous resource blocks (RBs) in the physical sidelink shared channel (PSSCH) starting from a first symbol carrying the PSSCH demodulation references signal (DMRS) . Blind decoding is not utilized because the SCI-2 format is indicated in the SCI-1, the number of resource elements (REs) is derived from SCI-1 content, and the starting location is known.

For wideband operation in unlicensed new radio (NR-U) , a network device, such as a base station, may transmit a partial physical downlink shared channel (PDSCH) . Because the PDSCH is a downlink transmission, the UE does not need to take special action to receive the partial PDSCH. The network device may transmit the PDSCH on a portion of or across the entire active bandwidth part (BWP) where the network device has performed a successful clear channel assessment (CCA) . A UE may receive a PDSCH scheduled within a listen-before-talk (LBT) bandwidth or over multiple LBT bandwidths.

Because NR allows for wider carriers (e.g., up to 100 MHz with 30 kHz sub-carrier spacing (SCS) ) , unlicensed sidelink communications (SL-U) may specify wideband operation when a carrier consists of multiple LBT bandwidths. For example, an LBT bandwidth may be 20 MHz in the 5 GHz/6 GHz unlicensed band. If multiple LBT bandwidths are assigned to a transmission, it is possible that the device may fail one or more LBT procedures and the device will perform partial transmission to improve resource utilization. As a result, the SCI-2 will be punctured. According to aspects of the present disclosure, to ensure the SCI-2 can be correctly decoded by the receiver, the coding rate of SCI-2 for wideband operation may be lowered, and/or the mapping rules of the SCI-2 may be redefined.

In some aspects, if there are N subbands in the wideband, the coding rate of the SCI-2 may then be reduced by N times (e.g., Beta_offset/N) , where Beta_offset is the coding rate. By lowering the coding rate in this manner, the likelihood of a receiving UE correctly decoding the SCI-2 increases, in case one or more LBT operations fail. That is, if a partial transmission occurs, the receiver should be able to successfully decode the SCI-2.

In other aspects, the SCI-2 mapping rules may be redefined. In a first option for redefining the mapping rule of SCI-2, the transmitting device maps the SCI-2 in increasing order of, first, a frequency index within one resource block (RB) set including the SCI-1 and then a time index with a starting symbol at the first physical sidelink shared channel (PSSCH) symbol carrying an associated demodulation references signal (DMRS) . In a second option, the SCI-2 is uniformly distributed over the wideband carrier. In these aspects, the SCI-2 is divided into the number of LBT subbands segments. Each segment is then mapped into an LBT subband.

FIGURE 1 illustrates an example of a wireless communications system 100 that supports techniques for partial sidelink transmission using wideband operations in accordance with one or more aspects of the present disclosure. The wireless communications system 100 may include one or more network entities 105, one or more UEs 115, and a core network 130. In some examples, the wireless communications system 100 may be an LTE network, an LTE-Advanced (LTE-A) network, an LTE-APro network, an NR network, or a network operating in accordance with other systems and radio technologies, including future systems and radio technologies not explicitly mentioned.

The network entities 105 may be dispersed throughout a geographic area to form the wireless communications system 100 and may include devices in different forms or having different capabilities. In various examples, a network entity 105 may be referred to as a network element, a mobility element, a radio access network (RAN) node, or network equipment, among other nomenclature. In some examples, network entities 105 and UEs 115 may wirelessly communicate via one or more communication links 125 (e.g., a radio frequency access link) . For example, a network entity 105 may support a coverage area 110 (e.g., a geographic coverage area) over which the UEs 115 and the network entity 105 may establish one or more communication links 125. The coverage area 110 may be an example of a geographic area over which a network entity 105 and a UE 115 may support the communication of signals according to one or more RATs.

The UEs 115 may be dispersed throughout a coverage area 110 of the wireless communications system 100, and each UE 115 may be stationary, or mobile, or both at different times. The UEs 115 may be devices in different forms or having different capabilities. Some example UEs 115 are illustrated in FIGURE 1. The UEs 115 described may be capable of supporting communications with various types of devices, such as other UEs 115 or network entities 105, as shown in FIGURE 1.

As described, a node of the wireless communications system 100, which may be referred to as a network node, or a wireless node, may be a network entity 105 (e.g., any network entity described) , a UE 115 (e.g., any UE described) , a network controller, an apparatus, a device, a computing system, one or more components, or another suitable processing entity configured to perform any of the techniques described. For example, a node may be a UE 115. As another example, a node may be a network entity 105. As another example, a first node may be configured to communicate with a second node or a third node. In one aspect of this example, the first node may be a UE 115, the second node may be a network entity 105, and the third node may be a UE 115. In another aspect of this example, the first node may be a UE 115, the second node may be a network entity 105, and the third node may be a network entity 105. In yet other aspects of this example, the first, second, and third nodes may be different relative to these examples. Similarly, reference to a UE 115, network entity 105, apparatus, device, computing system, or the like may include disclosure of the UE 115, network entity 105, apparatus, device, computing system, or the like being a node. For example, disclosure that a UE 115 is configured to receive information from a network entity 105 also discloses that a first node is configured to receive information from a second node.

In some examples, network entities 105 may communicate with the core network 130, or with one another, or both. For example, network entities 105 may communicate with the core network 130 via one or more backhaul communication links 120 (e.g., in accordance with an S1, N2, N3, or other interface protocol) . In some examples, network entities 105 may communicate with one another via a backhaul communication link 120 (e.g., in accordance with an X2, Xn, or other interface protocol) either directly (e.g., directly between network entities 105) or indirectly (e.g., via a core network 130) . In some examples, network entities 105 may communicate with one another via a midhaul communication link 162 (e.g., in accordance with a midhaul interface protocol) or a fronthaul communication link 168 (e.g., in accordance with a fronthaul interface protocol) , or any combination thereof. The backhaul communication links 120, midhaul communication links 162, or fronthaul communication links 168 may be or include one or more wired links (e.g., an electrical link, an optical fiber link) , one or more wireless links (e.g., a radio link, a wireless optical link) , among other examples or various combinations thereof. A UE 115 may communicate with the core network 130 via a communication link 155.

One or more of the network entities 105 described may include or may be referred to as a base station 140 (e.g., a base transceiver station, a radio base station, an NR base station, an access point, a radio transceiver, a NodeB, an eNodeB (eNB) , a next-generation NodeB or a giga-NodeB (either of which may be referred to as a gNB) , a 5G NB, a next-generation eNB (ng-eNB) , a Home NodeB, a Home eNodeB, or other suitable terminology) . In some examples, a network entity 105 (e.g., a base station 140) may be implemented in an aggregated (e.g., monolithic, standalone) base station architecture, which may be configured to utilize a protocol stack that is physically or logically integrated within a single network entity 105 (e.g., a single RAN node, such as a base station 140) .

In some examples, a network entity 105 may be implemented in a disaggregated architecture (e.g., a disaggregated base station architecture, a disaggregated RAN architecture) , which may be configured to utilize a protocol stack that is physically or logically distributed among two or more network entities 105, such as an integrated access backhaul (IAB) network, an open RAN (O-RAN) (e.g., a network configuration sponsored by the O-RAN Alliance) , or a virtualized RAN (vRAN) (e.g., a cloud RAN (C-RAN) ) . For example, a network entity 105 may include one or more of a central unit (CU) 160, a distributed unit (DU) 165, a radio unit (RU) 170, a RAN Intelligent Controller (RIC) 175 (e.g., a Near-Real Time RIC (Near-RT RIC) , a Non-Real Time RIC (Non-RT RIC) ) , a Service Management and Orchestration (SMO) 180 system, or any combination thereof. An RU 170 may also be referred to as a radio head, a smart radio head, a remote radio head (RRH) , a remote radio unit (RRU) , or a transmission reception point (TRP) . One or more components of the network entities 105 in a disaggregated RAN architecture may be co-located, or one or more components of the network entities 105 may be located in distributed locations (e.g., separate physical locations) . In some examples, one or more network entities 105 of a disaggregated RAN architecture may be implemented as virtual units (e.g., a virtual CU (VCU) , a virtual DU (VDU) , or a virtual RU (VRU) ) .

The split of functionality between a CU 160, a DU 165, and an RU 170 is flexible and may support different functionalities depending on which functions (e.g., network layer functions, protocol layer functions, baseband functions, radio frequency (RF) functions, and any combinations thereof) are performed at a CU 160, a DU 165, or an RU 170. For example, a functional split of a protocol stack may be employed between a CU 160 and a DU 165 such that the CU 160 may support one or more layers of the protocol stack and the DU 165 may support one or more different layers of the protocol stack. In some examples, the CU 160 may host upper protocol layer (e.g., layer 3 (L3) , layer 2 (L2) ) functionality and signaling (e.g., Radio Resource Control (RRC) , service data adaption protocol (SDAP) , Packet Data Convergence Protocol (PDCP) ) . The CU 160 may be connected to one or more DUs 165 or RUs 170, and the one or more DUs 165 or RUs 170 may host lower protocol layers, such as layer 1 (L1) (e.g., physical (PHY) layer) or L2 (e.g., radio link control (RLC) layer, medium access control (MAC) layer) functionality and signaling, and may each be at least partially controlled by the CU 160. Additionally, or alternatively, a functional split of the protocol stack may be employed between a DU 165 and an RU 170 such that the DU 165 may support one or more layers of the protocol stack and the RU 170 may support one or more different layers of the protocol stack. The DU 165 may support one or multiple different cells (e.g., via one or more RUs 170) . In some cases, a functional split between a CU 160 and a DU 165, or between a DU 165 and an RU 170 may be within a protocol layer (e.g., some functions for a protocol layer may be performed by one of a CU 160, a DU 165, or an RU 170, while other functions of the protocol layer are performed by a different one of the CU 160, the DU 165, or the RU 170) . A CU 160 may be functionally split further into CU control plane (CU-CP) and CU user plane (CU-UP) functions. A CU 160 may be connected to one or more DUs 165 via a midhaul communication link 162 (e.g., F1, F1-c, F1-u) , and a DU 165 may be connected to one or more RUs 170 via a fronthaul communication link 168 (e.g., open fronthaul (FH) interface) . In some examples, a midhaul communication link 162 or a fronthaul communication link 168 may be implemented in accordance with an interface (e.g., a channel) between layers of a protocol stack supported by respective network entities 105 that are in communication via such communication links.

In wireless communications systems (e.g., wireless communications system 100) , infrastructure and spectral resources for radio access may support wireless backhaul link capabilities to supplement wired backhaul connections, providing an IAB network architecture (e.g., to a core network 130) . In some cases, in an IAB network, one or more network entities 105 (e.g., IAB nodes 104) may be partially controlled by each other. One or more IAB nodes 104 may be referred to as a donor entity or an IAB donor. One or more DUs 165 or one or more RUs 170 may be partially controlled by one or more CUs 160 associated with a donor network entity 105 (e.g., a donor base station 140) . The one or more donor network entities 105 (e.g., IAB donors) may be in communication with one or more additional network entities 105 (e.g., IAB nodes 104) via supported access and backhaul links (e.g., backhaul communication links 120) . IAB nodes 104 may include an IAB mobile termination (IAB-MT) controlled (e.g., scheduled) by DUs 165 of a coupled IAB donor. An IAB-MT may include an independent set of antennas for relay of communications with UEs 115, or may share the same antennas (e.g., of an RU 170) of an IAB node 104 used for access via the DU 165 of the IAB node 104 (e.g., referred to as virtual IAB-MT (vIAB-MT) ) . In some examples, the IAB nodes 104 may include DUs 165 that support communication links with additional entities (e.g., IAB nodes 104, UEs 115) within the relay chain or configuration of the access network (e.g., downstream) . In such cases, one or more components of the disaggregated RAN architecture (e.g., one or more IAB nodes 104 or components of IAB nodes 104) may be configured to operate according to the techniques described.

In the case of the techniques described applied in the context of a disaggregated RAN architecture, one or more components of the disaggregated RAN architecture may be configured to support techniques for partial sidelink transmission using wideband operations as described. For example, some operations described as being performed by a UE 115 or a network entity 105 (e.g., a base station 140) may additionally, or alternatively, be performed by one or more components of the disaggregated RAN architecture (e.g., IAB nodes 104, DUs 165, CUs 160, RUs 170, RIC 175, SMO 180) .

A UE 115 may include or may 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, among other examples. A UE 115 may also include or may be referred to as a personal electronic device such as a cellular phone, a personal digital assistant (PDA) , a tablet computer, a laptop computer, or a personal computer. In some examples, a UE 115 may include or be referred to as a wireless local loop (WLL) station, an Internet of Things (IoT) device, an Internet of Everything (IoE) device, or a machine type communications (MTC) device, among other examples, which may be implemented in various objects such as appliances, or vehicles, meters, among other examples.

The UEs 115 described may be able to communicate with various types of devices, such as other UEs 115 that may sometimes act as relays as well as the network entities 105 and the network equipment including macro eNBs or gNBs, small cell eNBs or gNBs, or relay base stations, among other examples, as shown in FIGURE 1.

The UEs 115 and the network entities 105 may wirelessly communicate with one another via one or more communication links 125 (e.g., an access link) using resources associated with one or more carriers. The term “carrier” may refer to a set of RF spectrum resources having a defined physical layer structure for supporting the communication links 125. For example, a carrier used for a communication link 125 may include a portion of a RF spectrum band (e.g., a bandwidth part (BWP) ) that is operated according to one or more physical layer channels for a given radio access technology (e.g., LTE, LTE-A, LTE-A Pro, or NR) . Each physical layer channel may carry acquisition signaling (e.g., synchronization signals, system information) , control signaling that coordinates operation for the carrier, user data, or other signaling. The wireless communications system 100 may support communication with a UE 115 using 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 frequency division duplexing (FDD) and time division duplexing (TDD) component carriers. Communication between a network entity 105 and other devices may refer to communication between the devices and any portion (e.g., entity, sub-entity) of a network entity 105. For example, the terms “transmitting, ” “receiving, ” or “communicating, ” when referring to a network entity 105, may refer to any portion of a network entity 105 (e.g., a base station 140, a CU 160, a DU 165, a RU 170) of a RAN communicating with another device (e.g., directly or via one or more other network entities 105) .

In some examples, such as in a carrier aggregation configuration, a carrier may also have acquisition signaling or control signaling that coordinates operations for other carriers. A carrier may be associated with a frequency channel (e.g., an evolved universal mobile telecommunication system terrestrial radio access (E-UTRA) absolute RF channel number (EARFCN) ) and may be identified according to a channel raster for discovery by the UEs 115. A carrier may be operated in a standalone mode, in which case initial acquisition and connection may be conducted by the UEs 115 via the carrier, or the carrier may be operated in a non-standalone mode, in which case a connection is anchored using a different carrier (e.g., of the same or a different radio access technology) .

The communication links 125 shown in the wireless communications system 100 may include downlink transmissions (e.g., forward link transmissions) from a network entity 105 to a UE 115, uplink transmissions (e.g., return link transmissions) from a UE 115 to a network entity 105, or both, among other configurations of transmissions. Carriers may carry downlink or uplink communications (e.g., in an FDD mode) or may be configured to carry downlink and uplink communications (e.g., in a TDD mode) .

A carrier may be associated with a particular bandwidth of the RF 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 set of bandwidths for carriers of a particular radio access technology (e.g., 1.4, 3, 5, 10, 15, 20, 40, or 80 megahertz (MHz) ) . Devices of the wireless communications system 100 (e.g., the network entities 105, the UEs 115, or both) may have hardware configurations that support communications using a particular carrier bandwidth or may be configurable to support communications using one of a set of carrier bandwidths. In some examples, the wireless communications system 100 may include network entities 105 or UEs 115 that support concurrent communications using carriers associated with multiple carrier bandwidths. In some examples, each served UE 115 may be configured for operating using portions (e.g., a sub-band, a BWP) or all of a carrier bandwidth.

Signal waveforms transmitted via a carrier may be made up of multiple subcarriers (e.g., using multi-carrier modulation (MCM) techniques such as orthogonal frequency division multiplexing (OFDM) or discrete Fourier transform spread OFDM (DFT-S-OFDM) ) . In a system employing MCM techniques, a resource element may refer to resources of one symbol period (e.g., a duration of one modulation symbol) and one subcarrier, in which case the symbol period and subcarrier spacing may be inversely related. The quantity of bits carried by each resource element may depend on the modulation scheme (e.g., the order of the modulation scheme, the coding rate of the modulation scheme, or both) , such that a relatively higher quantity of resource elements (e.g., in a transmission duration) and a relatively higher order of a modulation scheme may correspond to a relatively higher rate of communication. A wireless communications resource may refer to a combination of an RF spectrum resource, a time resource, and a spatial resource (e.g., a spatial layer, a beam) , and the use of multiple spatial resources may increase the data rate or data integrity for communications with a UE 115.

One or more numerologies for a carrier may be supported, and a numerology may include a subcarrier spacing (Δf) and a cyclic prefix. A carrier may be divided into one or more BWPs having the same or different numerologies. In some examples, a UE 115 may be configured with multiple BWPs. In some examples, a single BWP for a carrier may be active at a given time and communications for the UE 115 may be restricted to one or more active BWPs.

The time intervals for the network entities 105 or the UEs 115 may be expressed in multiples of a basic time unit which may, for example, refer to a sampling period of T _s=1/ (Δf _max·N _f) seconds, for which Δf _max may represent a supported subcarrier spacing, and N _f may represent a supported discrete Fourier transform (DFT) size. Time intervals of a communications resource may be organized according to radio frames each having a specified duration (e.g., 10 milliseconds (ms) ) . Each radio frame may be identified by a system frame number (SFN) (e.g., ranging from 0 to 1023) .

Each frame may include multiple consecutively-numbered subframes or slots, and each subframe or slot may have the same duration. In some examples, a frame may be divided (e.g., in the time domain) into subframes, and each subframe may be further divided into a quantity of slots. Alternatively, each frame may include a variable quantity of slots, and the quantity of slots may depend on subcarrier spacing. Each slot may include a quantity of symbol periods (e.g., depending on the length of the cyclic prefix prepended to each symbol period) . In some wireless communications systems 100, a slot may further be divided into multiple mini-slots associated with one or more symbols. Excluding the cyclic prefix, each symbol period may be associated with one or more (e.g., N _f) sampling periods. The duration of a symbol period may depend on the subcarrier spacing or frequency band of operation.

A subframe, a slot, a mini-slot, or a symbol may be the smallest scheduling unit (e.g., in the time domain) of the wireless communications system 100 and may be referred to as a transmission time interval (TTI) . In some examples, the TTI duration (e.g., a quantity of symbol periods in a TTI) may be variable. Additionally, or alternatively, the smallest scheduling unit of the wireless communications system 100 may be dynamically selected (e.g., in bursts of shortened TTIs (sTTIs) ) .

Physical channels may be multiplexed for communication using a carrier according to various techniques. A physical control channel and a physical data channel may be multiplexed for signaling via a downlink carrier, for example, using one or more of time division multiplexing (TDM) techniques, frequency division multiplexing (FDM) techniques, or hybrid TDM-FDM techniques. A control region (e.g., a control resource set (CORESET) ) for a physical control channel may be defined by a set of symbol periods and may extend across the system bandwidth or a subset of the system bandwidth of the carrier. One or more control regions (e.g., CORESETs) may be configured for a set of the UEs 115. For example, one or more of the UEs 115 may monitor or search control regions for control information according to one or more search space sets, and each search space set may include one or multiple control channel candidates in one or more aggregation levels arranged in a cascaded manner. An aggregation level for a control channel candidate may refer to an amount of control channel resources (e.g., control channel elements (CCEs) ) associated with encoded information for a control information format having a given payload size. Search space sets may include common search space sets configured for sending control information to multiple UEs 115 and UE-specific search space sets for sending control information to a specific UE 115.

In some examples, a network entity 105 (e.g., a base station 140, an RU 170) may be movable and therefore provide communication coverage for a moving coverage area 110. In some examples, different coverage areas 110 associated with different technologies may overlap, but the different coverage areas 110 may be supported by the same network entity 105. In some other examples, the overlapping coverage areas 110 associated with different technologies may be supported by different network entities 105. The wireless communications system 100 may include, for example, a heterogeneous network in which different types of the network entities 105 provide coverage for various coverage areas 110 using the same or different radio access technologies.

The wireless communications system 100 may be configured to support ultra-reliable communications or low-latency communications, or various combinations thereof. For example, the wireless communications system 100 may be configured to support ultra-reliable low-latency communications (URLLC) . The UEs 115 may be designed to support ultra-reliable, low-latency, or critical functions. Ultra-reliable communications may include private communication or group communication and may be supported by one or more services such as push-to-talk, video, or data. Support for ultra-reliable, low-latency functions may include prioritization of services, and such services may be used for public safety or general commercial applications. The terms ultra-reliable, low-latency, and ultra-reliable low-latency may be used interchangeably.

In some examples, a UE 115 may be configured to support communicating directly with other UEs 115 via a device-to-device (D2D) communication link 135 (e.g., in accordance with a peer-to-peer (P2P) , D2D, or sidelink protocol) . In some examples, one or more UEs 115 of a group that are performing D2D communications may be within the coverage area 110 of a network entity 105 (e.g., a base station 140, an RU 170) , which may support aspects of such D2D communications being configured by (e.g., scheduled by) the network entity 105. In some examples, one or more UEs 115 of such a group may be outside the coverage area 110 of a network entity 105 or may be otherwise unable to or not configured to receive transmissions from a network entity 105. In some examples, groups of the UEs 115 communicating via D2D communications may support a one-to-many (1: M) system in which each UE 115 transmits to each of the other UEs 115 in the group. In some examples, a network entity 105 may facilitate the scheduling of resources for D2D communications. In some other examples, D2D communications may be carried out between the UEs 115 without an involvement of a network entity 105.

In some systems, a D2D communication link 135 may be an example of a communication channel, such as a sidelink communication channel, between vehicles (e.g., UEs 115) . In some examples, vehicles may communicate using vehicle-to-everything (V2X) communications, vehicle-to-vehicle (V2V) communications, or some combination of these. A vehicle may signal information related to traffic conditions, signal scheduling, weather, safety, emergencies, or any other information relevant to a V2X system. In some examples, vehicles in a V2X system may communicate with roadside infrastructure, such as roadside units, or with the network via one or more network nodes (e.g., network entities 105, base stations 140, RUs 170) using vehicle-to-network (V2N) communications, or with both.

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) or 5G core (5GC) , which may include at least one control plane entity that manages access and mobility (e.g., a mobility management entity (MME) , an access and mobility management function (AMF) ) and at least one user plane entity that routes packets or interconnects to external networks (e.g., a serving gateway (S-GW) , a Packet Data Network (PDN) gateway (P-GW) , or a user plane function (UPF) ) . The control plane entity may manage non-access stratum (NAS) functions such as mobility, authentication, and bearer management for the UEs 115 served by the network entities 105 (e.g., base stations 140) associated with the core network 130. User IP packets may be transferred through the user plane entity, which may provide IP address allocation as well as other functions. The user plane entity may be connected to IP services 150 for one or more network operators. The IP services 150 may include access to the Internet, Intranet (s) , an IP Multimedia Subsystem (IMS) , or a Packet-Switched Streaming Service.

The wireless communications system 100 may operate using one or more frequency bands, which may be 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 because the wavelengths range from approximately one decimeter to one meter in length. UHF waves may be blocked or redirected by buildings and environmental features, which may be referred to as clusters, but the waves may penetrate structures sufficiently for a macro cell to provide service to the UEs 115 located indoors. Communications using UHF waves may be associated with smaller antennas and shorter ranges (e.g., less than 100 kilometers) compared to communications using the smaller frequencies and longer waves of the high frequency (HF) or very high frequency (VHF) portion of the spectrum below 300 MHz.

The wireless communications system 100 may utilize both licensed and unlicensed RF spectrum bands. For example, the wireless communications system 100 may employ License Assisted Access (LAA) , LTE-Unlicensed (LTE-U) radio access technology, or NR technology using an unlicensed band such as the 5 GHz industrial, scientific, and medical (ISM) band. While operating using unlicensed RF spectrum bands, devices such as the network entities 105 and the UEs 115 may employ carrier sensing for collision detection and avoidance. In some examples, operations using unlicensed bands may be based on a carrier aggregation configuration in conjunction with component carriers operating using a licensed band (e.g., LAA) . Operations using unlicensed spectrum may include downlink transmissions, uplink transmissions, P2P transmissions, or D2D transmissions, among other examples.

A network entity 105 (e.g., a base station 140, an RU 170) or a 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. The antennas of a network entity 105 or a UE 115 may be located within one or more antenna arrays or antenna panels, 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 examples, antennas or antenna arrays associated with a network entity 105 may be located at diverse geographic locations. A network entity 105 may include an antenna array with a set of rows and columns of antenna ports that the network entity 105 may use to support beamforming of communications with a UE 115. Likewise, a UE 115 may include one or more antenna arrays that may support various MIMO or beamforming operations. Additionally, or alternatively, an antenna panel may support RF beamforming for a signal transmitted via an antenna port.

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 network entity 105, a UE 115) to shape or steer an antenna beam (e.g., a transmit beam, a 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 some signals propagating along 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 amplitude offsets, phase offsets, or both to signals carried via 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) .

The wireless communications system 100 may support a framework for transmitting one or more portions of a sidelink message using one or more portions of a wideband carrier. For example, a UE 115 may perform a clear channel assessment (CCA) for each of a set of unlicensed sub-bands in a wideband carrier. The UE 115 may also determine whether at least one of the unlicensed sub-bands is occupied. Transmitting a partial physical sidelink shared channel (PSSCH) along with a stage two sidelink control information message (SCI-2) across the wideband carrier based on the determining may lead to increased resource utilization within the wireless communications system 100, among other possible benefits.

FIGURE 2 illustrates an example of a network architecture 200 (e.g., a disaggregated base station architecture, a disaggregated RAN architecture) that supports techniques for partial sidelink transmission using wideband operations in accordance with one or more aspects of the present disclosure. The network architecture 200 may illustrate an example for implementing one or more aspects of the wireless communications system 100. The network architecture 200 may include one or more CUs 160-a that may communicate directly with a core network 130-a via a backhaul communication link 120-a, or indirectly with the core network 130-a through one or more disaggregated network entities 105 (e.g., a Near-RT RIC 175-b via an E2 link, or a Non-RT RIC 175-a associated with an SMO 180-a (e.g., an SMO Framework) , or both) . A CU 160-a may communicate with one or more DUs 165-a via respective midhaul communication links 162-a (e.g., an F1 interface) . The DUs 165-a may communicate with one or more RUs 170-a via respective fronthaul communication links 168-a. The RUs 170-a may be associated with respective coverage areas 110-a and may communicate with UEs 115-a via one or more communication links 125-a. In some implementations, a UE 115-a may be simultaneously served by multiple RUs 170-a.

Each of the network entities 105 of the network architecture 200 (e.g., CUs 160-a, DUs 165-a, RUs 170-a, Non-RT RICs 175-a, Near-RT RICs 175-b, SMOs 180-a, Open Clouds (O-Clouds) 205, Open eNBs (O-eNBs) 210) may include one or more interfaces or may be coupled with one or more interfaces configured to receive or transmit signals (e.g., data, information) via a wired or wireless transmission medium. Each network entity 105, or an associated processor (e.g., controller) providing instructions to an interface of the network entity 105, may be configured to communicate with one or more of the other network entities 105 via the transmission medium. For example, the network entities 105 may include a wired interface configured to receive or transmit signals over a wired transmission medium to one or more of the other network entities 105. Additionally, or alternatively, the network entities 105 may include a wireless interface, which may include a receiver, a transmitter, or transceiver (e.g., an RF transceiver) configured to receive or transmit signals, or both, over a wireless transmission medium to one or more of the other network entities 105.

In some examples, a CU 160-a may host one or more higher layer control functions. Such control functions may include RRC, PDCP, SDAP, or the like. Each control function may be implemented with an interface configured to communicate signals with other control functions hosted by the CU 160-a. A CU 160-a may be configured to handle user plane functionality (e.g., CU-UP) , control plane functionality (e.g., CU-CP) , or a combination thereof. In some examples, a CU 160-a may be logically split into one or more CU-UP units and one or more CU-CP units. A CU-UP unit may communicate bidirectionally with the CU-CP unit via an interface, such as an E1 interface when implemented in an O-RAN configuration. A CU 160-a may be implemented to communicate with a DU 165-a, as necessary, for network control and signaling.

A DU 165-a may correspond to a logical unit that includes one or more functions (e.g., base station functions, RAN functions) to control the operation of one or more RUs 170-a. In some examples, a DU 165-a may host, at least partially, one or more of an RLC layer, a MAC layer, and one or more aspects of a PHY layer (e.g., a high PHY layer, such as modules for forward error correction (FEC) encoding and decoding, scrambling, modulation and demodulation, or the like) depending, at least in part, on a functional split, such as those defined by the 3rd Generation Partnership Project (3GPP) . In some examples, a DU 165-a may further host one or more low PHY layers. Each layer may be implemented with an interface configured to communicate signals with other layers hosted by the DU 165-a, or with control functions hosted by a CU 160-a.

In some examples, lower-layer functionality may be implemented by one or more RUs 170-a. For example, an RU 170-a, controlled by a DU 165-a, may correspond to a logical node that hosts RF processing functions, or low-PHY layer functions (e.g., performing fast Fourier transform (FFT) , inverse FFT (iFFT) , digital beamforming, physical random access channel (PRACH) extraction and filtering, or the like) , or both, based at least in part on the functional split, such as a lower-layer functional split. In such an architecture, an RU 170-a may be implemented to handle over the air (OTA) communication with one or more UEs 115-a. In some implementations, real-time and non-real-time aspects of control and user plane communication with the RU (s) 170-a may be controlled by the corresponding DU 165-a. In some examples, such a configuration may enable a DU 165-a and a CU 160-a to be implemented in a cloud-based RAN architecture, such as a vRAN architecture.

The SMO 180-a may be configured to support RAN deployment and provisioning of non-virtualized and virtualized network entities 105. For non-virtualized network entities 105, the SMO 180-a may be configured to support the deployment of dedicated physical resources for RAN coverage requirements which may be managed via an operations and maintenance interface (e.g., an O1 interface) . For virtualized network entities 105, the SMO 180-a may be configured to interact with a cloud computing platform (e.g., an O-Cloud 205) to perform network entity life cycle management (e.g., to instantiate virtualized network entities 105) via a cloud computing platform interface (e.g., an O2 interface) . Such virtualized network entities 105 can include, but are not limited to, CUs 160-a, DUs 165-a, RUs 170-a, and Near-RT RICs 175-b. In some implementations, the SMO 180-a may communicate with components configured in accordance with a 4G RAN (e.g., via an O1 interface) . Additionally, or alternatively, in some implementations, the SMO 180-a may communicate directly with one or more RUs 170-a via an O1 interface. The SMO 180-a also may include a Non-RT RIC 175-a configured to support functionality of the SMO 180-a.

The Non-RT RIC 175-a may be configured to include a logical function that enables non-real-time control and optimization of RAN elements and resources, Artificial Intelligence (AI) or Machine Learning (ML) workflows including model training and updates, or policy-based guidance of applications/features in the Near-RT RIC 175-b. The Non-RT RIC 175-a may be coupled to or communicate with (e.g., via an A1 interface) the Near-RT RIC 175-b. The Near-RT RIC 175-b may be configured to include a logical function that enables near-real-time control and optimization of RAN elements and resources via data collection and actions over an interface (e.g., via an E2 interface) connecting one or more CUs 160-a, one or more DUs 165-a, or both, as well as an O-eNB 210, with the Near-RT RIC 175-b.

In some examples, to generate AI/ML models to be deployed in the Near-RT RIC 175-b, the Non-RT RIC 175-a may receive parameters or external enrichment information from external servers. Such information may be utilized by the Near-RT RIC 175-b and may be received at the SMO 180-a or the Non-RT RIC 175-a from non-network data sources or from network functions. In some examples, the Non-RT RIC 175-a or the Near-RT RIC 175-b may be configured to tune RAN behavior or performance. For example, the Non-RT RIC 175-a may monitor long-term trends and patterns for performance and employ AI or ML models to perform corrective actions through the SMO 180-a (e.g., reconfiguration via O1) or via generation of RAN management policies (e.g., A1 policies) .

In some examples, the aforementioned operations of the network entity (e.g., a CU 160-a, a DU 165-a, an RU 170-a) may be performed in accordance with the network architecture 200. For example, higher layer parameters (e.g., RRC parameters) indicative of the wideband operations (e.g., indicative of the one or more rules for partial sidelink transmissions using a wideband carrier) may be determined (e.g., selected, configured) by the CU 160-a and communicated to the DU 165-a (e.g., via a midhaul communication link 162-a) . In some examples, the DU 165-a may execute control signaling (e.g., RRC signaling) according to the parameters (or other rules associated with wideband communications, or sidelink communications, or both) communicated to the DU 165-a from the CU 160-a (e.g., via the higher layer parameters) . For example, the DU 165-a may generate a control signal used to indicate the parameters to the one or more UEs 115-a. The DU 165-a may communicate the control signal (or one or more aspects of the control signal) to the RU 170-a, for example via a fronthaul communication link 168-a. In some examples, and in response to obtaining the control signal generated by the DU 165-a, the RU 170-a may transmit the control signal (e.g., OTA) to the one or more UEs 115-a via a communication link 125-a. Such techniques may lead to increased reliability of wireless communications between the UEs 115-a and the network.

FIGURE 3 illustrates an example of a wireless communications system 300 that supports techniques for partial sidelink transmission using wideband operations in accordance with one or more aspects of the present disclosure. In some examples, the wireless communications system 300 may implement aspects of the wireless communications system 100 and the network architecture 200. For example, the wireless communications system 300 may include a network entity 305, a UE 315-a, and a UE 315-b, which may be examples of the corresponding devices as described with reference to FIGURES 1 and 2. The network entity 305 and the UEs 315 may communicate within a coverage area 310, which may be an example of a coverage area 110 described with reference to FIGURES 1 or 2.

The wireless communications system 300 may support wireless communications using an unlicensed (e.g., shared) radio frequency spectrum. For example, to transmit a communication using the unlicensed radio frequency spectrum, a communication device (e.g., the UE 315-a, the UE 315-b, the network entity 305) may perform a channel access procedure (e.g., a clear channel access procedure (CCA) , also referred to as a clear channel assessment) to gain access to a communication channel of the unlicensed radio frequency spectrum during a duration. In such an example, the communication device may transmit the communication in response to successfully completing the CCA procedure. Additionally, or alternatively, the communication device may refrain from transmitting the communication in response the CCA procedure failing.

In some examples, the wireless communications system 300 may support wideband operations using the unlicensed radio frequency spectrum. For example, the network entity 305 (e.g., a gNB) may transmit partial downlink messages (e.g., partial physical downlink shared channel (PDSCH) messages) to the UE 315-a or the UE 315-b (or both) using wideband operations. In such an example, the UE 315-a or the UE 315-b (or both) may perform one or more default operations (e.g., non-wideband operations) . As described, wideband operations may refer to communications using a bandwidth (e.g., a set of radio frequencies) that exceeds a threshold bandwidth (e.g., about 100 MHz or some other suitable bandwidth) . Additionally, or alternatively, as described, a bandwidth (e.g., a set of frequencies that exceeds the threshold bandwidth) may be referred to as a wideband carrier. In some examples, the network entity 305 may transmit a PDSCH message using a wideband carrier (e.g., across a single active bandwidth) or using one or more portions of the wideband carrier in which a CCA procedure, such as an LBT procedure, may be successful (e.g., at the network entity 305) .

For example, a wideband carrier may include multiple portions (e.g., different portions, such as different bandwidth parts) and each portion may be associated with an LBT procedure. That is, the network entity 305 (or another communication device) may transmit a portion of the PDSCH message (e.g., a partial PDSCH message) using a portion of a wideband carrier if an LBT procedure associated with the portion of the wideband carrier is successful. In some examples, the UE 315-a or the UE 315-b (or both) may receive the PDSCH message (e.g., scheduled to be transmitted from the network entity 305) using the wideband carrier or one or more portions of the wideband carrier. As described, a portion of a wideband carrier (e.g., that may be associated with an LBT procedure) may be referred to as an LBT sub-band. Although an LBT sub-band is referred to throughout the disclosure, it is to be understood that the techniques described may also apply to other sets of frequencies, such as other bandwidths, sub-bands, or carriers, and the examples described should not be considered limiting to the scope covered by the claims or the disclosure.

In some examples, the UE 315-a or the UE 315-b (or both) may be scheduled to transmit an uplink message (e.g., a physical uplink shared channel (PUSCH) message) to the network entity 305 using a wideband carrier. In such examples, the UE 315-a or the UE 315-b (or both) may transmit the PUSCH message using the wideband carrier (e.g., of the scheduled PUSCH message) , for example if LBT procedures (e.g., each LBT procedure) associated with the LBT sub-bands are successful. That is, the UE 315-a or the UE 315-b (or both) may refrain from transmitting the PUSCH message (e.g., one or more portions of the PUSCH message) if an LBT procedure associated with one or more LBT sub-bands of the wideband carrier fails. In some examples, the network entity 305 may refrain from transmitting (e.g., and the UE 315-a or the UE 315-b may not expect to receive) resource allocations in discontinuous LBT sub-bands within the wideband carrier.

Additionally, or alternatively, the wireless communications system 300 may support V2X communications. For example, one or both of the UE 315-a and the UE 315-b may be examples of vehicles. In some examples of V2X communications (or other types of sidelink communications) , frequency domain allocations (e.g., allocation of communication resources in the frequency domain, allocation of frequency resources) may be indicated using SCI (e.g., SCI stage 1) . For example, a resource allocation unit in the frequency domain may include a sub-channel. Additionally, or alternatively, a sub-channel assignment for a sidelink transmission may be determined (e.g., at the UE 315-a and the UE 315-b) using a frequency resource assignment field (e.g., a frequency domain resource assignment (FDRA) field) in an associated SCI. In some examples, the FDRA may provide a frequency resource indication value (FRIV) associated with the sidelink transmission (e.g., a PSSCH transmission) . That is, one or more frequency domain resources for transmission of the PSSCH message may be determined using an SCI (e.g., transmitted using a PSCCH) associated with the PSSCH message (e.g., associated with a PSSCH used for transmission of the PSSCH message) .

In some examples, a relatively lowest sub-channel, of multiple sub-channels to be used for a sidelink transmission (e.g., transmission of a PSSCH message) , may be associated with a sub-channel used for transmission of a PSCCH message that may include SCI associated with the PSSCH message. For example, the relatively lowest sub-channel may correspond to a relatively lowest resource (e.g., a physical resource block (PRB) including a relatively lowest frequency of multiple frequencies included in the multiple sub-channels) of multiple resources in which the associated PSCCH message may be transmitted. That is, one or more resources (e.g., one or more frequency domain resources) to be used for transmission of a PSSCH message may be determined based on (e.g., relative to) one or more resources used for transmission of the PSCCH message including the SCI (e.g., indicating an FRIV for the PSSCH message) . In such an example, a quantity of sub-channels allocated for transmission of the PSSCH message (e.g., contiguously allocated sub-channels) may be determined based on a quantity of resources reserved (e.g., at the UE 315-a or the UE 315-b) for transmission of the PSSCH message (e.g., including the one or more resources) and the FDRA field (e.g., indicating the FRIV) .

In an example in which two resources (e.g., up to about two time domain resources) may be reserved (e.g., as may be indicated using a sl-MaxNumPerReserve information element (IE) ) , the FDRA field may indicate (e.g., cover) a beginning (e.g., starting) sub-channel for a second resource (e.g., a second resource of the two resources reserved for transmission of the PSSCH message) and a quantity of sub-channels included in a first resource and the second resource (e.g., both of the resources reserved for transmission of the PSSCH message) . In examples in which three resources (e.g., up to about three time domain resources) may be reserved (e.g., as may be indicated using the sl-MaxNumPerReserve IE) , the FDRA field may indicate a beginning sub-channel for a second resource (e.g., a second resource of the three resources reserved for transmission of the PSSCH message) , a beginning sub-channel for a third resource (e.g., a third resource of the three resources reserved for transmission of the PSSCH message) and a quantity of sub-channels included in a first resource, the second resource, and the third resource (e.g., each of the three resources reserved for transmission of the PSSCH message) . In such examples (e.g., examples in with two or three resources may be reserved for transmission of the PSSCH message) , the first resource may correspond to the relatively lowest resource (e.g., the PRB including the relatively lowest frequency of the multiple frequencies included in the reserved resources) . That is, the relatively lowest sub-channel for the PSSCH transmission may correspond to a sub-channel in which the relatively lowest PRB of the associated PSCCH message (e.g., including the SCI) may be transmitted. It is to be understood that the names of IEs described may change based on implementation of one or more devices (e.g., the UE 315-a, the UE 315-b, or the network entity 305, or any combination thereof) , and the examples described should not be considered limiting to the scope covered by the claims or the disclosure.

As illustrated in the example of FIGURE 3, the wireless communications system 300 may support wideband operations for sidelink communications using the unlicensed radio frequency spectrum band. In an example in which a carrier (e.g., a wideband carrier) includes multiple LBT sub-bands 320 (e.g., 20 MHz bandwidths in the 5 GHz or 6 GHz unlicensed radio frequency spectrum band) , the wireless communications system 300 may support sidelink communications using the wideband carrier (e.g., using bandwidths up to 100 MHz with 30 kHz subcarrier spacing (SCS) ) . In such examples, the UE 315-a may perform multiple LBT procedures 340 to gain access to the channel for sidelink transmissions, such as a sidelink transmission using the PSCCH (e.g., a PSCCH message including an SCI message 330) and one or more partial sidelink transmissions using the PSSCH (e.g., a partial sidelink message 335-a, a partial sidelink message 335-b) , using one or more LBT sub-bands 320 (e.g., an LBT sub-band 320-a, an LBT sub-band 320-b, an LBT sub-band 320-c) .

In some examples, one or more of the LBT procedures 340 associated with the LBT sub-bands 320 may fail. For example, the LBT sub-band 320-a may include the relatively lowest PRB of multiple PRBs included the PSSCH (e.g., the PRB in which the SCI message 330 may be transmitted) and, in some examples, an LBT procedure 340-a associated with the LBT sub-band 320-a may fail. In such an example, if the UE 315-a (e.g., a transmitting communication device) transmits one or more portions of a PSSCH message using other LBT sub-band (e.g., LBT sub-bands in which the associated LBT procedure was successful) the UE 315-b (e.g., a receiving communication device) may fail to receive the SCI message 330-a (e.g., due to the LBT procedure 340-a associated with the LBT sub-band 320-a failing) . In some examples, if the UE 315-b fails to receive the SCI message 330-a, the UE 315-b may be incapable of determining a frequency location of the partial sidelink messages 335 (e.g., a starting position of resources reserved for the partial sidelink messages 335, a starting sub-channel of resources reserved for the partial sidelink messages 335) .

In some examples, techniques for partial sidelink transmissions using wideband operations, as described, may provide one or more enhancements for transmission of partial sidelink messages (e.g., one or more portions of a sidelink message, one or more portions of a PSSCH message) using one or more LBT sub-bands. For example, some techniques for partial sidelink transmissions using wideband operations, as described, may enable transmission of one or more portions of a PSSCH message based on an LBT procedure corresponding to a relatively lowest PRB of an associated PSSCH (e.g., a PSSCH to be used for transmission of the PSSCH message) . Additionally, or alternatively, some techniques for partial sidelink transmissions using wideband operations, as described, may enable decoupling of PSSCH frequency allocation with PSCCH frequency location. That is, such techniques may provide for the determination of resources (e.g., frequency domain resources) to be used for transmission of a PSSCH message or one or more portions of a PSSCH message irrespective of a frequency location of an associated PSCCH (e.g., a PSCCH used to transmit a PSCCH message including SCI) .

For example, as illustrated in the example of FIGURE 3, the UE 315-a may receive a control message from the network entity 305 (e.g., using the carrier 321) . The control message may include a wideband operation indication 325 that indicates, to the UE 315-a, to perform wideband operations for partial sidelink messages using a carrier of an unlicensed radio frequency spectrum band (e.g., a wideband carrier) . In some examples, the wideband carrier may include multiple LBT sub-bands. For example, the wideband carrier may include the LBT sub-band 320-a, the LBT sub-band 320-b, and the LBT sub-band 320-c (e.g., and one or more other sub-bands) . Additionally, or alternatively, in some examples, the wideband operations may be associated with communications (e.g., sidelink communications or any other type of communications) using a bandwidth that exceeds the threshold bandwidth (e.g., about 100 MHz or some other suitable bandwidth) . In some examples, the UE 315-a may perform multiple LBT procedures for the multiple LBT sub-bands (e.g., for the LBT sub-band 320-a, the LBT sub-band 320-b, and the LBT sub-band 320-c) . For example, the UE 315-a may perform the LBT procedure 340-a that may be associated with the LBT sub-band 320-a, an LBT procedure 340-b that may be associated with the LBT sub-band 320-b, and an LBT procedure 340-c that may be associated with the LBT sub-band 320-c.

In some examples, one or more LBT procedures (e.g., of the multiple LBT procedures) may fail. For example, the LBT procedure 340-c (e.g., associated with the LBT sub-band 320-c) may fail. In such examples, the UE 315-a may transmit one or more partial sidelink messages 335 using one or more LBT sub-bands (e.g., of the multiple LBT sub-bands) . For example, the UE 315-a may transmit, to the UE 315-b, a partial sidelink message 335-a using the LBT sub-band 320-a and a partial sidelink message 335-b using the LBT sub-band 320-b. In some examples, the UE 315-a may transmit the partial sidelink message 335-a and the partial sidelink message 335-b based on the SCI message 330-a (e.g., an SCI message associated with the partial sidelink message 335-a, the partial sidelink message 335-b, and one or more other partial sidelink messages) being transmitted using the LBT sub-band 320-a (e.g., using a PSCCH associated with the LBT sub-band 320-a) . That is, the UE 315-a may transmit the partial sidelink message 335-a and the partial sidelink message 335-b based on the LBT procedure 340-c (e.g., the LBT procedure that failed) being associated with the LBT sub-band 320-c (e.g., an LBT sub-band different from the LBT sub-band 320-a used for transmission of the SCI message 330-a) .

In some examples, the UE 315-a may transmit the SCI message 330-a and the SCI message 330-b based on the LBT procedure 340-a and the LBT procedure 340-b being successful. The SCI message 330-a may indicate one or more frequency resources of the LBT sub-band 320-a to be used for transmitting the partial sidelink message 335-a and the SCI message 330-b may indicate one or more frequency resources of the LBT sub-band 320-b to be used for transmitting the partial sidelink message 335-b. The one or more frequency resources (e.g., of the LBT sub-band 320-a and the LBT sub-band 320-b, respectively) may be based on the wideband operations. In some examples, the UE 315-a may transmit, to the UE 315-b, the partial sidelink message 335-a using the one or more frequency resources indicated using the SCI message 330-a and the partial sidelink message 335-b using the one or more frequency resources indicated using the SCI message 330-b. In some examples, transmitting the SCI message 330-a and the SCI message 330-b based on the LBT procedure 340-a and the LBT procedure 340-b being successful may improve throughput and reliability within the wireless communications system 300.

FIGURE 4 illustrates an example of a wideband carrier diagram 400 that supports techniques for partial sidelink transmission using wideband operations in accordance with one or more aspects of the present disclosure. In some examples, the wideband carrier diagram 400 may implement aspects of the wireless communications system 100, the network architecture 200, and the wireless communications system 300. For example, the wideband carrier diagram 400 may be implemented at a network entity or a UE, or both, which may be examples of the corresponding devices as described with reference to FIGURES 1 through 3.

In some examples, a wireless communications system may support wideband operations for sidelink communications using the unlicensed radio frequency spectrum band. For example, the wireless communications system may support sidelink communications using a wideband carrier 410 that includes multiple LBT sub-bands (e.g., an LBT sub-band 420-a, an LBT sub-band 420-b, and an LBT sub-band 420-c) . In such examples, a first UE may perform multiple LBT procedures to gain access to the channel for sidelink transmissions using the multiple LBT sub-bands. For example, the first UE may perform a first LBT procedure associated with the LBT sub-band 420-a, a second LBT procedure for the LBT sub-band 420-b, and a third LBT procedure for LBT sub-band 420-c. In some examples, the LBT sub-band 420-a may be used to transmit SCI-1 425. In the example of FIGURE 4, the SCI-1 425 may correspond to first type of SCI (e.g., SCI stage 1) . For example, the LBT sub-band 420-a with SCI-1 425 (e.g., a primary LBT bandwidth) may corresponds to a relatively lowest PRB (e.g., may include a PRB with a relatively lowest frequency of multiple frequencies included in the wideband carrier 410) . In some examples, the relatively lowest PRB may be associated with a PSSCH 415 (e.g., a physical channel including one or more time-frequency resources for sidelink data transmissions) . For example, the relatively lowest PRB may be used to transmit the SCI-1 425, which may be associated with (e.g., include resource allocation information for) the PSSCH 415.

In some examples, the first LBT procedure (e.g., the LBT procedure associated with the LBT sub-band 420-a, an LBT procedure associated with the primary LBT bandwidth) may fail. In such examples, the first UE may refrain from transmitting (e.g., may drop) one or more portions of a PSSCH message (e.g., one or more portions of a message to be transmitted using the PSSCH 415) . Additionally, or alternatively, as illustrated in the example of FIGURE 4, the first UE may successfully complete the first LBT procedure (e.g., the first LBT procedure may be successful, the primary LBT bandwidth may pass the associated LBT procedure) . In such an example, the first UE may transmit, to a second UE, the SCI-1 425. In some examples, the first UE may transmit the SCI-1 425 using a sidelink control channel (e.g., a PSCCH) . In some examples, the SCI-1 425 may be used (e.g., in accordance with one or more default procedures) to determine a frequency resource allocation of the PSSCH 415. That is, the second UE may use the SCI-1 425 to determine one or more frequency resources of the PSSCH 415 to be used (e.g., at the first UE) for transmission of one or more portions of a PSSCH message. For example, the SCI-1 425 may include a FDRA field that may indicate, to the second UE, a portion (e.g., one or more frequency resources) of the PSSCH 415 associated with the LBT sub-band 420-a and a portion of the PSSCH 415 associated with the LBT sub-band 420-c to be used for transmitting one or more portions of the PSSCH message.

The first UE may transmit one or more portions of the PSSCH message using the indicated frequency resources (e.g., the indicated portions of the PSSCH 415) , for example in the LBT sub-bands in which the associated LBT procedure was successful. For example, the first UE may transmit one or more portions of the PSSCH message using the LBT sub-band 420-a and the LBT sub-band 420-c based on the first and third LBT procedures being successful and may refrain from transmitting a portion of the PSSCH message using the LBT sub-band 420-b based on the second LBT procedure failing. In some examples, transmitting one or more portions of the PSSCH message using the LBT sub-band 420-a and the LBT sub-band 420-c based on the first and third LBT procedures being successful may increase the resource utilization between the first UE and the second UE, among other benefits.

FIGURE 5 illustrates an example of a wideband carrier diagram 500 that supports techniques for partial sidelink transmission using wideband operations in accordance with one or more aspects of the present disclosure. In some examples, the wideband carrier diagram 500 may implement aspects of the wireless communications system 100, the network architecture 200, the wireless communications system 300, and the wideband carrier diagram 400. For example, the wideband carrier diagram 500 may be implemented at a network entity or a UE, or both, which may be examples of the corresponding devices as described with reference to FIGURES 1 through 4.

In some examples, a wireless communications system may support wideband operations for sidelink communications using the unlicensed radio frequency spectrum band. For example, the network entity may configure one or more UEs (or the one or more UEs may be otherwise configured) for wideband operations, such that the UEs may support sidelink communications using a wideband carrier 510 that includes multiple LBT sub-bands (e.g., an LBT sub-band 520-a, an LBT sub-band 520-b, and an LBT sub-band 520-c) . In some examples, a first UE (e.g., a transmitting UE) may indicate resources (e.g., frequency domain resources) to be used for transmission of a PSSCH message or portions of a PSSCH message irrespective of a frequency location of an associated PSCCH (e.g., a PSCCH message including an SCI) . That is, a frequency resource allocation of a PSSCH 515 (e.g., to be used for transmitting PSSCH messages) may be decoupled from a PSCCH frequency location.

For example, as illustrated in the example of FIGURE 5, the first UE may perform multiple LBT procedures to gain access to the channel for sidelink transmissions using one or more LBT sub-bands 520 of the wideband carrier 510. In some examples, the first UE may perform a first LBT procedure for (e.g., associated with) the LBT sub-band 520-a, a second LBT procedure for the LBT sub-band 520-b, and a third LBT procedure for LBT sub-band 520-c. In such examples, the second LBT procedure associated with the LBT sub-band 520-b may fail. Additionally, or alternatively, the first LBT procedure (e.g., associate with the LBT sub-band 520-a) and the second LBT procedure (e.g., associated with the LBT sub-band 520-c) may be successful. In such an example, the first UE may transmit SCI-1 525-a using the LBT sub-band 520-a and SCI-1 525-b using the LBT sub-band 520-c. The SCI-1 525-a may indicate one or more frequency resources of the LBT sub-band 520-a to be used for transmitting a portion of a PSSCH message (e.g., using the PSSCH 515 associated with the LBT sub-band 520-a) and the SCI-1 525-b may indicate one or more frequency resources of the LBT sub-band 520-c to be used for transmitting another portion of the PSSCH message (e.g., using the PSSCH 515 associated with the LBT sub-band 520-c) . In the example of FIGURE 5, the SCI-1 525-a and the SCI-1 525-b may correspond to first type of SCI (e.g., SCI stage 1) .

In some examples, the SCI-1 525-a and the SCI-1 525-b may indicate the one or more frequency resources (e.g., of the LBT sub-band 520-a and the LBT sub-band 520-c, respectively) using a quantity of bits that may be based on the wideband operations and a FRIV associated with the respective one or more frequency resources. For example, the first UE (e.g., a device configured for wideband operation) may reserve (e.g., be configured to reserve) a quantity of frequency resources (e.g., up to 2 frequency resource) that may be configured (e.g., indicate to a second UE) using a quantity of bits. In some examples, the first UE may use a higher layer parameter (e.g., a sl-MaxNumPerReserve IE) configured to 1 to reserve a resource (e.g., one resource) for transmission of one or more portions of a PSSCH message using the PSSCH 515. In such an example, the first UE may indicate the frequency resources using a quantity of bits (e.g., transmitted using the SCI-1 525-a or the SCI-1 525-b, or both) in accordance with the following Equation 1:

in which

may correspond to a quantity of sub-channels in a resource pool (e.g., provided according to another higher layer parameter, such as a numSubchannel IE) . In some examples, such as examples in which the higher layer parameter is configured to 1, the SCI-1 525-a or the SCI-1 525-b (or both) may include a FRIV determined in accordance with the following Equation 2:

in which

may correspond to a beginning (e.g., starting) sub-channel index for the resource and L _subCH may correspond to a quantity of sub-channels (e.g., a quantity of contiguous sub-channels) within the resource pool. Additionally, or alternatively, the first UE may use the higher layer parameter (e.g., the sl-MaxNumPerReserve IE) configured to 2 to reserve two resource for transmission of one or more portions of a PSSCH message using the PSSCH 515. In such an example, the first UE may indicate the frequency resources using another quantity of bits (e.g., transmitted using the SCI-1 525-a or the SCI-1 525-b, or both) in accordance with the following Equation 3:

In some examples, such as examples in which the higher layer parameter is configured to 2, the SCI-1 525-a or the SCI-1 525-b (or both) may include a FRIV determined in accordance with the following Equation 4:

in which

may correspond to a beginning sub-channel index for a first resource of the two resources and

may correspond to a beginning sub-channel index for a second resource of the two resources.

In some examples, the first UE or second UE (or both) may receive an indication of whether a frequency resource allocation (e.g., whether frequency resource allocation information provided to the respective UE) is to be used in accordance with (e.g., applies to, is associated with) wideband operations. For example, the network entity may indicate, to the first UE or the second UE, or both, that a frequency resource allocation (e.g., for transmission of one or more portions of a PSSCH message) is for wideband operations using control signaling, such as RRC signaling (e.g., via an RRC configuration message) . Additionally, or alternatively, the first UE may transmit another SCI message (e.g., a second type of SCI message, such as SCI stage 2) that may include one or more bits (e.g., a bit field) that indicate, to the second UE, that a frequency resource allocation (e.g., for transmission of one or more portions of a PSSCH message) is for wideband operations. For example, the other SCI message may indicate whether a switch may occur between a default operation and a wideband operation for a subsequent (e.g., next) sidelink transmission (e.g., a transmission of one or more portions of a PSSCH message) . That is, if the first UE is operating in a default operation mode (e.g., a non-wideband operation mode) , the UE first UE may transmit, to the second UE, the other SCI that may include a bit field with a value 0. Additionally, or alternatively, the first UE may switch the value of the bitfield to 1 to indicate, to the second UE, a switch from the default operation mode to a wideband operation mode for a subsequent transmission. That is, the first UE may use a bitfield set to 0 (e.g., and included in the other SCI) to indicate that a frequency resource allocation may be for a default operation and a bitfield set to 1 to indicate that a frequency resource allocation may be for wideband operations. In some examples, indicating whether a frequency resource allocation is to be used in accordance with wideband operations may lead to increased resource utilization with a wireless communications system, among other possible benefits.

FIGURE 6 illustrates an example of a wideband carrier diagram 600 that supports techniques for partial sidelink transmission using wideband operations in accordance with one or more aspects of the present disclosure. In some examples, the wideband carrier diagram 600 may implement aspects of the wireless communications system 100, the network architecture 200, the wireless communications system 300, the wideband carrier diagram 400, and the wideband carrier diagram 500. For example, the wideband carrier diagram 600 may be implemented at a network entity or a UE, or both, which may be examples of the corresponding devices as described with reference to FIGURES 1 through 5.

In some examples, the network entity may configure one or more UEs (or the one or more UEs may be otherwise configured) for wideband operations. In such examples, the UEs may support sidelink communications using a wideband carrier 610 that include multiple LBT sub-bands (e.g., an LBT sub-band 620-a, an LBT sub-band 620-b, and an LBT sub-band 620-c) . In some examples, a first of the one or more UEs (e.g., a transmitting UE) may indicate, to a second of the one or more UEs (e.g., a receiving UE) , frequency domain resources to be used for transmission of one or more portions of a PSSCH message irrespective of a frequency location of an associated PSCCH (e.g., including an SCI) . That is, a frequency resource allocation of a PSSCH 615 (e.g., to be used for transmitting PSSCH messages) may be decoupled from a PSCCH frequency location.

For example, as illustrated in the example of FIGURE 6, the first UE may perform multiple LBT procedures to gain access to the channel for sidelink transmissions using one or more LBT sub-bands of the wideband carrier 610. In some examples, the first UE may perform a first LBT procedure for the LBT sub-band 620-a, a second LBT procedure for the LBT sub-band 620-b, and a third LBT procedure for LBT sub-band 620-c. In such examples, the first LBT procedure associated with the LBT sub-band 620-a may fail. Additionally, or alternatively, the second LBT procedure (e.g., associate with the LBT sub-band 620-b) and the third LBT procedure (e.g., associated with the LBT sub-band 620-c) may be successful. In such an example, the first UE may transmit SCI-1 625-a using the LBT sub-band 620-b and SCI-1 625-b using the LBT sub-band 620-c. Additionally, or alternatively, the first UE may transmit SCI-2 630-a using the LBT sub-band 620-b and SCI-2 630-b using the LBT sub-band 620-c. In the example of FIGURE 6, the SCI-1 625-a and the SCI-1 625-b may correspond to a first type of SCI (e.g., SCI stage 1) and the SCI-2 630-a and the SCI-2 630-b may correspond to a second type of SCI (e.g., SCI stage 2) . In some examples, the SCI-1 625-a and the SCI-1 625-b may indicate a quantity of subchannels (e.g., a quantity of contiguous sub-channels) within a resource pool (e.g., may indicate the parameter L _subCH) , while the SCI-2 630-a and the SCI-2 630-b may indicate a beginning subchannel index of a first resource (e.g., of one or more resources reserved for transmission of a PSSCH message using the PSSCH 615) associated with the respective LBT sub-band (e.g., may indicate the parameter

for the respective LBT sub-band) .

In some examples, the network may configure the first UE and the second UE (or the first UE and the second UE may be otherwise configured or preconfigured, such as with one or more rules) with one or more mapping rules associated with the SCI-2 630-a and the SCI-2 630-b. In some examples, a mapping rule (e.g., of the one or more mapping rules configured at the first UE and the second UE) may indicate that a mapping (e.g., an indication of a beginning subchannel index of a first resource of one or more resources reserved for transmission of the PSSCH message using the PSSCH 615) indicated using an SCI stage 2 (e.g., the SCI-2 630-a, the SCI-2 630-b) may correspond to one LBT sub-band (e.g., the LBT sub-band 620-b or the LBT sub-band 620-c) . Additionally, or alternatively, the mapping rule (or another mapping rule) may indicate that the mapping provided using the SCI stage 2 may be repeated for multiple (e.g., each) LBT sub-band (e.g., the LBT sub-band 620-b and the LBT sub-band 620-c) . For example, a mapping associated with (e.g., provided using, indicated using) the SCI-2 630-a may correspond to the LBT sub-band 620-b and a mapping associated with the SCI-2 630-b may correspond to the LBT sub-band 620-c.

In some examples, the mapping between the SCI-2s 630 and the respective LBT sub-bands 620 may be provided (e.g., indicated, determined) using a bit field. For example, the SCI-2s 630 may include a bit field that indicates, for the respective LBT sub-band 620 (e.g., the LBT sub-band in which the respective SCI-2 630 may be transmitted) , the beginning subchannel index of the first resource of one or more resources reserved for transmission of the PSSCH message using the PSSCH 615 (e.g., associated with the LBT sub-band in which the respective SCI-2 630 may be transmitted) . In some examples, the beginning subchannel index of the first resource may be determined in accordance with the following Equation 5:

in which

may correspond to the beginning subchannel index of the first resource of an LBT sub-band in which the respective SCI-2 630 may have been transmitted and B _LBT may correspond to an index associated with the LBT sub-band. The index associated with the LBT sub-band may be based on a respective order (e.g., or frequency position) of the LBT sub-band relative to one or more other LBT sub-bands. For example, the LBT sub-band 620-a may include a relatively lowest frequency of multiple frequencies included in the wideband carrier 610. Accordingly, an index associated with the LBT sub-band 620-a may correspond to a relatively lowest value among multiple indices associated with the LBT sub-bands 620 included in the wideband carrier 610. As an illustrative example, the index associated with the LBT sub-band 620-a may correspond to value of 0 (e.g., B _LBT may be configured with a value of 0 for the LBT sub-band 620-a) , the index associated with the LBT sub-band 620-b may correspond to a value of 1 (e.g., B _LBT may be configured with a value of 1 for the LBT sub-band 620-b) , and the index associated with the LBT sub-band 620-c may correspond to a value of 2 (e.g., B _LBT may be configured with a value of 2 for the LBT sub-band 620-c) .

Additionally, or alternatively, the mapping between the SCI-2s 630 and the respective LBT sub-band 620 may be indicated using a bit field. For example, the SCI-2s 630 (e.g., the SCI-2 630-a, the SCI-2 630-b) may include a bitmap that indicates a status of an LBT procedure associated with the LBT sub-band in which the respective SCI-2 630 may have be transmitted. In some examples, the status of the LBT procedure may indicate whether the LBT procedure of the respective LBT sub-band failed. For example, the SCI-2 630-a may include a bitmap that indicates the status of an LBT procedure associated with the LBT sub-band 620-b and the SCI-2 630-b may include a bitmap that indicates the status of an LBT procedure associated with the LBT sub-band 620-c. In some examples, the first UE (e.g., and the second UE) may be configured with another mapping rule that may indicate that a bitmap value of 1 corresponds to an LBT procedure success and a bitmap value of 0 corresponds to an LBT procedure failure. In such an example, the one or more frequency resources may be determined (e.g., at the second UE) based on the bitmap value. In some examples, configuring the first UE and the second UE with one or more rules associated with the SCI-2 630-a and the SCI-2 630-b may provide one or more enhancements for partial sidelink transmissions using a wideband carrier (e.g., the wideband carrier 610) .

FIGURES 7A and 7B illustrate examples of a wideband carrier diagrams 700 (e.g., a wideband carrier diagram 700-a and a wideband carrier diagram 700-b) that supports techniques for partial sidelink transmission using wideband operations in accordance with one or more aspects of the present disclosure. In some examples, the wideband carrier diagrams 700 may implement aspects of the wireless communications system 100, the network architecture 200, the wireless communications system 300, the wideband carrier diagram 400, the wideband carrier diagram 500, and the wideband carrier diagram 600. For example, the wideband carrier diagrams 700 may be implemented at a network entity or a UE, or both, which may be examples of the corresponding devices as described with reference to FIGURES 1 through 6.

In some examples, the network entity may configure one or more UEs (or the one or more UEs may be otherwise configured or preconfigured, such as with one or more rules) for wideband operations, such that the one or more UEs may support sidelink communications using wideband carriers 710 (e.g., a wideband carrier 710-a and a wideband carrier 710-b) that may each include multiple LBT sub-bands. For example, the wideband carrier 710-a may include an LBT sub-band 720-a, an LBT sub-band 720-b, and an LBT sub-band 720-c. Additionally, or alternatively, the wideband carrier 710-b may include an LBT sub-band 720-d, an LBT sub-band 720-e, and an LBT sub-band 720-f. In some examples, a first UE (e.g., a transmitting UE) may indicate to a second UE (e.g., a receiving UE) one or more frequency resources to be used for transmission of a PSSCH message or portions of a PSSCH message (e.g., at the first UE) irrespective of a frequency location of an associated PSCCH (e.g., including an SCI) . That is, a frequency resource allocation of a PSSCH 715 (e.g., to be used for transmitting PSSCH messages) may be decoupled from a PSCCH frequency location. In some examples, the first UE may indicate one or more frequency resources of an LBT sub-band to be used for transmission of the PSSCH message (or one or more portions of the PSSCH message) using a CRC mask or a scrambling indication, or both. In some examples, the scrambling indication may indicate a scrambling identifier (e.g., a radio network temporary identifier (RNTI) or another scrambling identifier associated with the RNTI) or an index associated with the LBT sub-band (e.g., B _LBT) , or both.

For example, the first UE may scramble a quantity of bits included in an SCI (e.g., an SCI-1 725-a, an SCI-1 725-b, an SCI-1 725-c, an SCI-1 725-d) that may indicate one or more frequency resources of the LBT sub-band in which the SCI may be transmitted. In some examples, the first UE may scramble the quantity of bits using an RNTI (or using some other suitable scrambling mechanism) . In such examples, the second UE may determine the one or more resources based on a mapping between multiple LBT sub-bands and the scrambled bits (e.g., a CRC bit mask) or the scrambling indication, or both. The network may configure the first UE and the second UE with the mapping or the mapping may be otherwise configured at the first UE and the second UE. For example, the network may transmit, to the first UE and the second UE, control signaling (e.g., RRC signaling) that may indicate (e.g., configure the UEs with) one or more CRC masks or scrambling identifiers (e.g., RNTIs) , or both, to apply to the multiple LBT sub-bands (e.g., sequentially or in some other suitable order) . In such an example, the second UE (e.g., the sidelink receiver) may determine the one or more resources (e.g., the PSSCH frequency allocation) based on the detected CRC mask or the scrambling indication, or both.

For example, as illustrated in the example of FIGURE 7A, the first UE may perform multiple LBT procedures to gain access to the channel for sidelink transmissions using one or more LBT sub-bands of the wideband carrier 710-a. In some examples, the first UE may perform a first LBT procedure for (e.g., associated with) the LBT sub-band 720-a, a second LBT procedure for the LBT sub-band 720-b, and a third LBT procedure for LBT sub-band 720-c. In such examples, the second LBT procedure associated with the LBT sub-band 720-b may fail. Additionally, or alternatively, the first LBT procedure (e.g., associate with the LBT sub-band 720-a) and the second LBT procedure (e.g., associated with the LBT sub-band 720-c) may be successful. In such an example, the first UE may transmit SCI-1 725-a using the LBT sub-band 720-a and a SCI-1 725-b using the LBT sub-band 720-c.

In the example of FIGURE 7A, the SCI-1 725-a and the SCI-1 725-b may correspond to a first type of SCI (e.g., SCI stage 1) . The SCI-1 725-a may indicate one or more frequency resources of the LBT sub-band 720-a to be used for transmitting a portion of a PSSCH message (e.g., using the PSSCH 715 of the LBT sub-band 720-a) . For example, the SCI-1 725-a may include a scrambling indication (or CRC mask) that may indicate a beginning subchannel index (e.g., starting point) associated with the SCI-1 725-a (e.g., a beginning subchannel index of the first resource of one or more resources reserved for transmission of the PSSCH message using the PSSCH 715) . In some examples, the SCI-1 725-a may indicate the beginning subchannel index using a scrambling indication that identifies a scrambling ID and an index associated with the LBT sub-band 720-a (e.g., a parameter B _LBT that may be configured with a value of 0) . That is, a value of the parameter

for LBT sub-band 720-a may correspond to a beginning subchannel index of the SCI-1 725-a. Additionally, or alternatively, The SCI-1 725-b may indicate one or more frequency resources of the LBT sub-band 720-c to be used for a portion of a PSSCH message (e.g., transmitted using the PSSCH 725 of the LBT sub-band 720-c) . For example, the SCI-1 725-b may include a scrambling indication (or CRC mask) that may indicate a beginning sub-carrier index (e.g., starting point) associated with the SCI-1 725-b (e.g., beginning subchannel index of the first resource of one or more resources reserved for transmission of the PSSCH message using the PSSCH 715) . In some examples, the SCI-1 725-b may indicate the beginning sub-carrier index using a scrambling indication that identifies a scrambling ID and an index associated with the LBT sub-band 720-c (e.g., a parameter B _LBT that may be configured with a value of 2) .

Additionally, or alternatively, as illustrated in the example of FIGURE 7B, the first UE may perform multiple LBT procedures to gain access to the channel for sidelink transmissions using one or more LBT sub-bands of the wideband carrier 710-b. In some examples, the first UE may perform a first LBT procedure for (e.g., associated with) the LBT sub-band 720-d, a second LBT procedure for the LBT sub-band 720-e, and a third LBT procedure for LBT sub-band 720-f. In such examples, the UE first LBT procedure associated with the LBT sub-band 720-d may fail. Additionally, or alternatively, the second LBT procedure (e.g., associate with the LBT sub-band 720-e) and the third LBT procedure (e.g., associated with the LBT sub-band 720-f) may be successful. In such an example, the first UE may transmit SCI-1 725-c using the LBT sub-band 720-e and SCI-1 725-d using the LBT sub-band 720-f.

In the example of FIGURE 7B, the SCI-1 725-c and the SCI-1 725-d may correspond to a first type of SCI (e.g., SCI stage 1) . The SCI-1 725-c may indicate one or more frequency resources of the LBT sub-band 720-e to be used for transmitting a portion of a PSSCH message (e.g., using the PSSCH 725 of the LBT sub-band 720-e) . For example, the SCI-1 725-c may include a scrambling indication (or CRC mask) that may indicate a beginning sub-carrier index (e.g., starting point) associated with the SCI-1 725-c (e.g., beginning subchannel index of the first resource of one or more resources reserved for transmission of the PSSCH message using the PSSCH 715) . In some examples, the SCI-1 725-c may indicate the beginning sub-carrier index using a scrambling indication that identifies a scrambling ID and an index associated with the LBT sub-band 720-e (e.g., a parameter B _LBT that may be configured with a value of 1) . That is, a value of the parameter

for LBT sub-band 720-e may correspond to a difference between a beginning sub-carrier index (e.g., a starting point) of the SCI-1 725-c and the parameter B _LBT that may be configured with a value of 1.

Additionally, or alternatively, the SCI-1 725-d may indicate one or more frequency resources of the LBT sub-band 720-f to be used for a portion of a PSSCH message (e.g., transmitted using the PSSCH 725 of the LBT sub-band 720-f) . For example, the SCI-1 725-d may include a scrambling indication (or CRC mask) that may indicate a beginning sub-carrier index (e.g., starting point) associated with the SCI-1 725-d (e.g., beginning subchannel index of the first resource of one or more resources reserved for transmission of the PSSCH message using the PSSCH 715) . In some examples, the SCI-1 725-d may indicate the beginning sub-carrier index using a scrambling indication that identifies a scrambling ID and an index associated with the LBT sub-band 720-f (e.g., a parameter B _LBT that may be configured with a value of 2) . In some examples, configuring the first UE and the second UE with one or more mapping rules may provide increased resource utilization within the wireless communications system, among other possible benefits.

A physical sidelink shared channel (PSSCH) may be multiplexed with a second stage sidelink control information message (SCI-2) . In some implementations, an SCI-2 is mapped to contiguous resource blocks (RBs) in the physical sidelink shared channel (PSSCH) starting from a first symbol carrying the PSSCH demodulation references signal (DMRS) . The SCI-2 is scrambled separately from data, such as a sidelink shared channel (SL-SCH) . The SCI-2 is modulated with quadrature phase shift keying (QPSK) . Blind decoding is not utilized because the SCI-2 format is indicated in the stage one sidelink control information (SCI-1) , the number of resource elements (REs) is derived from SCI-1 content, and the starting location is known. When SL-SCH transmission is on two layers, SCI-2 modulation symbols are copied to both layers.

FIGURE 8 is a block diagram illustrating sidelink time/frequency structures, in accordance with aspects of the present disclosure. In a first structure 800, a first automatic gain control (AGC) symbol 802 is followed by three symbols carrying the PSSCH 804 and SCI-1 806. A fourth symbol carries multiplexed DMRS and SCI-2 information 808. Additional PSSCH symbols 810 and a DMRS symbol 812 are followed by a gap 814. In a second structure 850, the multiplexed DMRS and SCI-2 information 808 follows the AGC symbol 802. If additional symbols are needed (as in the second structure 850) , the SCI-2 818 is mapped to consecutive symbols.

To simplify UE behavior, transmission of the physical uplink shared channel is an all or nothing transmission. The UE transmits the PUSCH only if the CCA is successful at the UE in all LBT bandwidths of the scheduled PUSCH. The UE is not expected to receive resource allocations in discontinuous LBT bandwidths within a wideband carrier.

Because NR allows for wider carriers (e.g., up to 100 MHz with 30 kHz sub-carrier spacing (SCS) ) , unlicensed sidelink communications (SL-U) may specify wideband operation when a carrier consists of multiple LBT bandwidths. For example, an LBT bandwidth may be 20 MHz in the 5 GHz/6 GHz unlicensed band. If multiple LBT bandwidths are assigned to a transmission, it is possible that the device may fail one or more LBT procedures and the device will perform partial transmission to improve resource utilization. As result, the SCI-2 will be punctured. According to aspects of the present disclosure, to ensure the SCI-2 can be correctly decoded by the receiver, the coding rate of SCI-2 for wideband operation may be lowered, and/or the mapping rules of the SCI-2 may be redefined.

Lowering the coding rate of the SCI-2 for wideband operation is now discussed in more detail. If there are N subbands in the wideband, the coding rate of the SCI-2 may then be reduced by N times (e.g., Beta_offset/N) , where Beta_offset is the coding rate. In other words, the coding rate of the SCI-2 is proportional to 1/the number of LBT subbands. It is possible that the SCI-2 may only map to one or two LBT subbands of the wideband, even with the lower coding rate. If the LBT subbands carrying the SCI-2 fail the LBT operation, the SCI-2 may not be decodable.

FIGURE 9 is a block diagram 900 illustrating stage two sidelink control information (SCI-2) transmission with a lower coding rate, in accordance with aspects of the present disclosure. In some examples, the block diagram 900 may implement aspects of the wireless communications system 100, the network architecture 200, or the wireless communications system 300. For example, the block diagram 900 may be implemented at a network entity or a UE, or both, which may be examples of the corresponding devices as described with reference to FIGURES 1 through 8.

In some examples, the network entity may configure one or more UEs (or the one or more UEs may be otherwise configured or preconfigured, such as with one or more rules) for wideband operations, such that the one or more UEs may support sidelink communications using a wideband carrier 910 that may include multiple LBT sub-bands. For example, the wideband carrier 910 may include a first LBT sub-band 920-a, a second LBT sub-band 920-b, a third LBT sub-band 920-c, and a fourth LBT sub-band 920-d.

In some examples, a first UE (e.g., a transmitting UE) may indicate to a second UE (e.g., a receiving UE) one or more frequency resources to be used for transmission of an SCI-2 902, a demodulation reference signal (DMRS) 904, a PSSCH message 906, and an SCI-1 908. According to aspects of the present disclosure, a coding rate of the SCI-2 is reduced. Possible frequency patterns for multiplexing the SCI-2 902, the DMRS 904, and the PSSCH message 906 to reduce the coding rate include: a DMRS and PSSCH pattern 915, a DMRS and SCI-2 pattern 925, and a DMRS multiplexed with both SCI-2 and PSSCH pattern 935. In the example of FIGURE 9, a coding rate of the SCI-2 902 has been reduced such that the first UE transmits the DMRS 904 and the SCI-2 902 with the DMRS and SCI-2 pattern 925 in the first LBT sub-band 920-a. In the second LBT sub-band 920-b, the first UE transmits the SCI-2 902, the DMRS 904, and the PSSCH message 906 with the DMRS multiplexed with both SCI-2 and PSSCH pattern 935. The first UE transmits the DMRS 904 and PSSCH message 906 in the third LBT sub-band 920-c and the fourth LBT sub-band 920-d with the DMRS and PSSCH pattern 915. By lowering the coding rate in this manner, the likelihood of the second UE correctly decoding the SCI-2 902 increases, in case one or more LBT operations fail. That is, if a partial transmission occurs, the receiver should be able to successfully decode the SCI-2 902.

Resource consumption increases if a lower coding rate is used. Thus, a tradeoff between resource consumption and partial transmission may be considered. According to aspects of the present disclosure, a mapping rule is defined between a coding rate and a maximum number of allowed punctured LBT bandwidths. In these aspects, a network element (e.g., gNB) (for sidelink mode 1) or the transmitting UE (for sidelink mode 2) may select a coding rate. After selecting the coding rate, the network element or transmitting UE determines whether a number of LBT failures is less than a number of allowed LBT failures for the selected coding rate. If so, then partial transmission may be performed. Otherwise, the whole transmission may be dropped.

FIGURE 10 is a table illustrating an example of a mapping between coding rate and a maximum number of allowed LBT failures, in accordance with aspects of the present disclosure. It is noted that the values shown in FIGURE 10 are exemplary. Other values are also contemplated. In FIGURE 10, four coding rates (e.g., R0, R1, R2, and R3) are shown. For each coding rate, a maximum number of allowed LBT failures is shown. In the example of FIGURE 10, if the transmitting device selects coding rate R0, no LBT failures are allowed if partial transmission is to be permitted. If the transmitting device selects coding rate R1, less than 1/4 of the LBT failures are allowed if the partial transmission is to be permitted. For example, if five LBT sub-bands are present, partial transmission is permitted if one or none of the LBT operations fails. If the transmitting device selects coding rate R2, between 1/4 and 1/2 of the LBTs are allowed to fail if the partial transmission is to be permitted. If the transmitting device selects coding rate R3, between 1/2 and 3/4 of the LBTs are allowed to fail if partial transmission is to be permitted.

According to aspects of the present disclosure, the SCI-2 mapping rules may be redefined. In a first option for redefining the mapping rule of SCI-2, the transmitting device maps the SCI-2 in increasing order of, first, a frequency index within one resource block (RB) set including the SCI-1 and then a time index with a starting symbol at the first physical sidelink shared channel (PSSCH) symbol carrying an associated demodulation references signal (DMRS) .

If the length of the SCI-2 is greater than a total amount of available resource elements (REs) in one resource block (RB) set, the rest of the SCI-2 may be mapped into the next following RB set. The rest of the SCI-2 may be mapped following the above mapping rule, where the SCI-2 is mapped in increasing order of, first, the frequency index within this RB set and then the time index, starting at the first PSSCH symbol carrying an associated DMRS.

FIGURE 11A is a block diagram 1100 illustrating stage two sidelink control information (SCI-2) transmission with a redefined mapping, in accordance with aspects of the present disclosure. In some examples, the block diagram 1100 may implement aspects of the wireless communications system 100, the network architecture 200, or the wireless communications system 300. For example, the block diagram 1100 may be implemented at a network entity or a UE, or both, which may be examples of the corresponding devices as described with reference to FIGURES 1 through 10.

In some examples, the network entity may configure one or more UEs (or the one or more UEs may be otherwise configured or preconfigured, such as with one or more rules) for wideband operations, such that the one or more UEs may support sidelink communications using a wideband carrier 1110 that may include multiple LBT sub-bands. For example, the wideband carrier 1110 may include a first LBT sub-band 1120-a, a second LBT sub-band 1120-b, and a third LBT sub-band 1120-c.

In some examples, a first UE (e.g., a transmitting UE) may indicate to a second UE (e.g., a receiving UE) one or more frequency resources to be used for transmission of an SCI-2 1102, a PSSCH message 1106, and an SCI-1 1108. According to aspects of the present disclosure, if the length of the SCI-2 1102 is greater than a total amount of available resource elements (REs) in one resource block (RB) set, the rest of the SCI-2 1102 may be mapped into the next following RB set. More specifically, the SCI-2 1102 of FIGURE 11A is split into two parts 1102-a and 1102-b. A first part of the SCI-2 1102-a is transmitted in the first LBT sub-band 1120-a in more than one RB set, that is, the initial RB set and the next following RB set. The second part of the SCI-2 1102-b is transmitted in the second LBT sub-band 1120-b.

To ensure the receiver may correctly decode the SCI-2 with partial transmission, the LBT subband containing the SCI-1 and SCI-2 may be defined as the primary LBT subband. According to aspects of the present disclosure, if this LBT subband fails the LBT operation, then the whole transmission may be dropped. Otherwise, partial transmission is allowed.

If the SCI-2 is mapped to more than one RB set, for example, as described with respect to FIGURE 11A, multiple options are available. In a first option, if the LBT subband containing both the SCI-1 and SCI-2 passes, then partial transmission is allowed. In a second option, only if all LBT subbands containing the SCI-2 pass, then partial transmission is allowed.

FIGURE 11B shows three block diagrams 1150, 1160, and 1170 illustrating stage two sidelink control information (SCI-2) transmission with a redefined mapping, in accordance with aspects of the present disclosure. In some examples, the block diagrams 1150, 1160, and 1170 may implement aspects of the wireless communications system 100, the network architecture 200, or the wireless communications system 300. For example, the block diagrams 1150, 1160, and 1170 may be implemented at a network entity or a UE, or both, which may be examples of the corresponding devices as described with reference to FIGURES 1 through 11A.

In some examples, the network entity may configure one or more UEs (or the one or more UEs may be otherwise configured or preconfigured, such as with one or more rules) for wideband operations, such that the one or more UEs may support sidelink communications using a wideband carrier that may include multiple LBT sub-bands. For example, the wideband carrier may include a first LBT sub-band 1120-a, a second LBT sub-band 1120-b, and a third LBT sub-band 1120-c.

In some examples, a first UE (e.g., a transmitting UE) may indicate to a second UE (e.g., a receiving UE) one or more frequency resources to be used for transmission of an SCI-2, a PSSCH message, and an SCI-1. As seen in the block diagram 1150, the first LBT sub-band 1120-a containing the SCI-1 and SCI-2 fails the LBT operation. Thus, the whole transmission may be dropped. The third LBT sub-band 1120-c passes in this block diagram 1150.

As seen in the block diagram 1160, the first LBT sub-band 1120-acontaining both the SCI-1 and SCI-2 passes. Thus, partial transmission is allowed, even though the second LBT sub-band 1120-b carrying a portion of the SCI-2 fails. The third LBT sub-band 1120-c also passes in the example shown in this block diagram 1160.

As seen in the block diagram 1170, the second LBT sub-band containing all of the SCI-2 fails. Thus, partial transmission is not allowed and the transmission is dropped. The first LBT sub-band 1120-a and the third LBT sub-band 1120-c pass in the example shown in this block diagram 1170.

According to a second mapping option, if the length of the SCI-2 is greater than a total amount of available resource elements (REs) in one resource block (RB) set, a higher coding rate, for example Beta_offset, may be used to ensure the SCI-2 can fit into one RB set. The techniques described with respect to the table in FIGURE 10 may apply when implementing this option. That is, based on a selected coding rate, a maximum number of LBT failures determines whether partial transmission is permitted.

FIGURES 12A and 12B are block diagrams 1200 and 1250, 1260, respectively illustrating stage two sidelink control information (SCI-2) transmission with a redefined mapping and a higher coding rate for the SCI-2, in accordance with aspects of the present disclosure. In some examples, the block diagrams 1200, 1250, 1260 may implement aspects of the wireless communications system 100, the network architecture 200, or the wireless communications system 300. For example, the block diagrams 1200, 1250, 1260 may be implemented at a network entity or a UE, or both, which may be examples of the corresponding devices as described with reference to FIGURES 1 through 11B.

In some examples, the network entity may configure one or more UEs (or the one or more UEs may be otherwise configured or preconfigured, such as with one or more rules) for wideband operations, such that the one or more UEs may support sidelink communications using a wideband carrier 1210 that may include multiple LBT sub-bands. For example, the wideband carrier 1210 may include a first LBT sub-band 1220-a, a second LBT sub-band 1220-b, and a third LBT sub-band 1220-c.

In some examples, a first UE (e.g., a transmitting UE) may indicate to a second UE (e.g., a receiving UE) one or more frequency resources to be used for transmission of an SCI-2 1202, a PSSCH message, and an SCI-1. According to aspects of the present disclosure, if the length of the SCI-2 1202 is greater than a total amount of available resource elements (REs) in one resource block (RB) set, a higher coding rate is used to ensure the SCI-2 1202 can fit into one RB set. In the example of FIGURE 12A, the coding rate is increased, such that the SCI-2 1202 fits into the first LBT sub-band 1220-a.

In some aspects of the present disclosure, the SCI-2 may be repeated in each LBT subband if the SCI-1 is repeated in each LBT subband and the SCI-2 can fit into one RB set. According to these aspects, if any LBT sub-band passes, partial transmission may be performed. These aspects may apply if the PSSCH location is decoupled from the SCI-1 location. In the example of FIGURE 12B, a first block diagram 1250 shows both the SCI-1 and the SCI-2 repeated in each of the first LBT sub-band 1220-a, the second LBT sub-band 1220-b, and the third LBT sub-band 1220-c. The LBT operation fails for the first LBT sub-band 1220-a. Nevertheless, partial transmission occurs because the LBT operation passes for both the second LBT sub-band 1220-b and the third LBT sub-band 1220-c. The second block diagram 1260 of FIGURE 12B illustrates the SCI-1 and the SCI-2 in the first LBT sub-band 1220-a. Because the LBT operation for the first LBT sub-band 1220-a fails, the transmission is dropped.

In other aspects of the present disclosure, the SCI-2 is uniformly distributed over the wideband carrier 1210. In these aspects, the SCI-2 is divided into the number of LBT subbands segments. Each segment is then mapped into an LBT subband. In one option, the mapping is in accordance with legacy rules. In another option, the frequency mapping rule of SCI-2 is redefined, where the SCI-2 is mapped in increasing order of first the frequency index through the whole wideband and then the time index, starting at the first PSSCH symbol carrying an associated DMRS.

FIGURE 13 is a block diagram 1300 illustrating stage two sidelink control information (SCI-2) transmission with a distributed mapping for the SCI-2, in accordance with aspects of the present disclosure. In some examples, the block diagram 1300 may implement aspects of the wireless communications system 100, the network architecture 200, or the wireless communications system 300. For example, the block diagram 1300 may be implemented at a network entity or a UE, or both, which may be examples of the corresponding devices as described with reference to FIGURES 1 through 12B.

In some examples, the network entity may configure one or more UEs (or the one or more UEs may be otherwise configured or preconfigured, such as with one or more rules) for wideband operations, such that the one or more UEs may support sidelink communications using a wideband carrier 1310 that may include multiple LBT sub-bands. For example, the wideband carrier 1310 may include a first LBT sub-band 1320-a, a second LBT sub-band 1320-b, a third LBT sub-band 1320-c, and a fourth LBT sub-band 1320-d.

In some examples, a first UE (e.g., a transmitting UE) may indicate to a second UE (e.g., a receiving UE) one or more frequency resources to be used for transmission of an SCI-2 1302, a DMRS 1304, a PSSCH message 1306, and an SCI-1 1308. According to aspects of the present disclosure, the SCI-2 1302 is divided into the number of LBT segments and mapped into each segment, for example, uniformly distributed over the wideband carrier 1310. In the example of FIGURE 13, four LBT sub-bands are present. Thus, the SCI-2 1302 is divided into four segments. Each segment is mapped to one of the LBT sub-bands 1320-a, 1320-b, 1320-c, and 1320-d. The mapping may follow legacy rules. A segment may be mapped into the first PSSCH symbol carrying an associated DMRS within the LBT subband. If the length is greater than the available REs at this symbol, the SCI-2 maps to the following PSSCH symbol within the corresponding LBT subband.

Possible frequency patterns to implement the mapping involve multiplexing the SCI-2 1302, the DMRS 1304, and the PSSCH message 1306. The patterns include a DMRS and PSSCH pattern 1315, a DMRS and SCI-2 pattern 1325, and a DMRS multiplexed with both SCI-2 and PSSCH pattern 1335. In the example of FIGURE 13, each SCI-2 segment is mapped with the DMRS multiplexed with both SCI-2 and PSSCH pattern 1335. More specifically, a first segment of the SCI-2 1302 is mapped to the first LBT sub-band 1320-a, a second segment of the SCI-2 1302 is mapped to the second LBT sub-band 1320-b, a third segment of the SCI-2 1302 is mapped to the third LBT sub-band 1320-c, and a fourth segment of the SCI-2 1302 is mapped to the fourth LBT sub-band 1320-d.

FIGURE 14 is a block diagram 1400 illustrating stage two sidelink control information (SCI-2) transmission with a distributed mapping for the SCI-2, in accordance with aspects of the present disclosure. In some examples, the block diagram 1400 may implement aspects of the wireless communications system 100, the network architecture 200, or the wireless communications system 300. For example, the block diagram 1400 may be implemented at a network entity or a UE, or both, which may be examples of the corresponding devices as described with reference to FIGURES 1 through 13.

In some examples, the network entity may configure one or more UEs (or the one or more UEs may be otherwise configured or preconfigured, such as with one or more rules) for wideband operations, such that the one or more UEs may support sidelink communications using a wideband carrier 1410 that may include multiple LBT sub-bands. For example, the wideband carrier 1410 may include a first LBT sub-band 1420-a, a second LBT sub-band 1420-b, a third LBT sub-band 1420-c, and a fourth LBT sub-band 1420-d.

In some examples, a first UE (e.g., a transmitting UE) may indicate to a second UE (e.g., a receiving UE) one or more frequency resources for transmission of an SCI-2 1402, a DMRS 1404, a PSSCH message 1406, and an SCI-1 1408. According to aspects of the present disclosure, the SCI-2 1402 is uniformly distributed over the wideband carrier 1410. In the example of FIGURE 14, four LBT sub-bands are present. The SCI-2 1402 views the wideband carrier 1410 as a single band and is mapped across the wideband carrier 1410.

If the SCI-2 1402 has a length greater than a number of available REs at the PSSCH symbol carrying the DMRS, available REs at the next following PSSCH symbol may be used. For the first symbol, the SCI-2 will use all available REs at the first PSSCH symbol carrying an associated DMRS. A frequency pattern 1425 multiplexing the DMRS 1404 and SCI-2 1402 may be used. For the next following PSSCH symbol, a frequency pattern 1445 with a frequency step size of

is used. In the example of FIGURE 14, the step size is four. Thus, a first SCI-2 is mapped, then three PSSCH portions are mapped to the next three REs, and then another SCI-2 portion, and so on.

If the SCI-2 has a length less than a number of available REs at the first PSSCH symbol carrying an associated DMRS, a frequency step size of the SCI-2 is

The number of REs carrying SCI-2 in each RB is denoted as

In this case, a frequency step size for the SCI-2 may be in accordance with a frequency pattern 1465 or a frequency pattern 1475 shown in FIGURE 14. For example, if the number of REs for the SCI-2 in each RB is three, the frequency pattern 1465 is used with a step size of two. If the number of REs for the SCI-2 in each RB is four, the frequency pattern 1475 is used with a step size of one, where the DMRS 1404 and SCI-2 1402 alternate for the first eight REs, and then the DMRS 1404 and PSSCH message 1406 alternate for the remaining REs of the RB.

Although the preceding description was primarily described with respect to a single layer, the present disclosure applies to multi-layer communications. In this case, the same operations may be performed for each of the layers.

FIGURE 15 is a flow diagram illustrating an example process 1500 performed, for example, by a sidelink transmitting device, in accordance with various aspects of the present disclosure. The example process 1500 is an example of a stage two sidelink control information (SCI-2) enhancement for partial transmission during wideband operation in unlicensed sidelink spectrum (SL-U) .

As shown in FIGURE 15, in some aspects, the process 1500 may include performing a clear channel assessment (CCA) for each of a number of unlicensed sub-bands in a wideband carrier (block 1502) . In some aspects, the process 1500 may also include determining whether at least one of the number of unlicensed sub-bands is occupied (block 1504) .

In some aspects, the process 1500 may further include transmitting a partial physical sidelink shared channel (PSSCH) along with a stage two sidelink control information (SCI-2) across the wideband carrier based on the determining (block 1506) . For example, in some asepcts the transmitting may include decreasing a coding rate for the SCI-2 based on a total quantity of unlicensed sub-bands in the wideband carrier, and multiplexing the partial PSSCH with the SCI-2. The transmitting may occur when a quantity of occupied unlicensed sub-bands is less than a threshold failure rate mapped to a selected coding rate. In some asepcts, the transmitting may include mapping the SCI-2 to resource elements (REs) , starting at a frequency within an initial resource block (RB) set including a stage one sidelink control information message (SCI-1) , and at a time of a first PSSCH symbol carrying an associated demodulation reference signal (DMRS) . A remaining portion of the SCI-2 may be mapped to a subsequent RB set in response to a length of the SCI-2 being greater than a total amount of available REs in the initial RB set. In other aspects, the transmitting may comprise uniformly distributing the SCI-2 over the wideband carrier, with a mapping of the SCI-2 starting: at a first frequency within the wideband carrier; and at a time of a first PSSCH symbol carrying an associated demodulation reference signal (DMRS) . The transmitting may occur when a quantity of occupied unlicensed sub-bands is less than a threshold failure rate mapped to a selected coding rate.

Example Aspects

Aspect 1: A method of wireless communication by a sidelink transmitting device, comprising: performing a clear channel assessment (CCA) for each of a plurality of unlicensed sub-bands in a wideband carrier; determining whether at least one of the plurality of unlicensed sub-bands is occupied; and transmitting a partial physical sidelink shared channel (PSSCH) along with a stage two sidelink control information (SCI-2) across the wideband carrier based on the determining.

Aspect 2: The method of Aspect 1, in which the transmitting comprises: decreasing a coding rate for the SCI-2 based on a total quantity of unlicensed sub-bands in the wideband carrier; and multiplexing the partial PSSCH with the SCI-2.

Aspect 3: The method of

Aspect

1 or 2, in which the transmitting occurs when a quantity of occupied unlicensed sub-bands is less than a threshold failure rate mapped to a selected coding rate.

Aspect 4: The method of any of the preceding Aspects, in which: the transmitting comprises mapping the SCI-2 to resource elements (REs) ; the REs starting: at a frequency within an initial resource block (RB) set including a stage one sidelink control information message (SCI-1) , and at a time of a first PSSCH symbol carrying an associated demodulation reference signal (DMRS) .

Aspect 5: The method of any of the preceding Aspects, further comprising mapping a remaining portion of the SCI-2 to a subsequent RB set in response to a length of the SCI-2 being greater than a total amount of available REs in the initial RB set.

Aspect 6: The method of any of the preceding Aspects, further comprising increasing a coding rate for the SCI-2 in response to a length of the SCI-2 being greater than a total amount of available REs in the initial RB set.

Aspect 7: The method of any of the preceding Aspects, further comprising dropping transmission of the SCI-2 in response to determining an unlicensed sub-band containing the SCI-2 and a stage one sidelink control information message (SCI-1) is occupied.

Aspect 8: The method of any of the preceding Aspects, further comprising repeating the transmitting of the SCI-2 in each of the plurality of unlicensed sub-bands in response to repeating transmission of a stage one sidelink control information message (SCI-1) in each of the plurality of unlicensed sub-bands when the SCI-2 fits into a single RB set and performing the transmitting if any of the plurality of unlicensed sub-bands is determined to be unoccupied.

Aspect 9: The method of Aspect 1, in which the transmitting comprises uniformly distributing segments of the SCI-2 over the wideband carrier.

Aspect 10: The method of Aspect 1, in which the transmitting comprises uniformly distributing the SCI-2 over the wideband carrier, with a mapping of the SCI-2 starting: at a first frequency within the wideband carrier; and at a time of a first PSSCH symbol carrying an associated demodulation reference signal (DMRS) .

Aspect 11: The method of Aspect 10, further comprising mapping a first portion of the SCI-2 to all REs in the first PSSCH symbol and mapping a remaining portion of the SCI-2 to a subsequent PSSCH symbol, in response to a length of the SCI-2 being greater than a quantity of available resource elements in the wideband carrier.

Aspect 12: The method of Aspect 10, further comprising mapping the SCI-2 with a frequency step size based on a ratio between a first quantity of available REs and a second quantity of REs needed for the SCI-2, the mapping occurring in response to a length of the SCI-2 being less than the first quantity of available REs.

Aspect 13: The method of any of the preceding Aspects 9-12, in which the transmitting occurs when a quantity of occupied unlicensed sub-bands is less than a threshold failure rate mapped to a selected coding rate.

Aspect 14: An apparatus for wireless communication, comprising: a memory; and at least one processor coupled to the memory, the at least one processor configured: to perform a clear channel assessment (CCA) for each of a plurality of unlicensed sub-bands in a wideband carrier; to determine whether at least one of the plurality of unlicensed sub-bands is occupied; and to transmit a partial physical sidelink shared channel (PSSCH) along with a stage two sidelink control information (SCI-2) across the wideband carrier based on the determining.

Aspect 15: The apparatus of Aspect 14, in which the at least one processor is configured to transmit by: decreasing a coding rate for the SCI-2 based on a total quantity of unlicensed sub-bands in the wideband carrier; and multiplexing the partial PSSCH with the SCI-2.

Aspect 16: The apparatus of Aspect 14 or 15, in which the at least one processor is configured to transmit when a quantity of occupied unlicensed sub-bands is less than a threshold failure rate mapped to a selected coding rate.

Aspect 17: The apparatus of any of the Aspects 14-16, in which: the at least one processor is configured to transmit by mapping the SCI-2 to resource elements (REs) ; the REs starts: at a frequency within an initial resource block (RB) set including a stage one sidelink control information message (SCI-1) , and at a time of a first PSSCH symbol carrying an associated demodulation reference signal (DMRS) .

Aspect 18: The apparatus of any of the Aspects 14-17, in which the at least one processor is further configured to map a remaining portion of the SCI-2 to a subsequent RB set in response to a length of the SCI-2 being greater than a total amount of available REs in the initial RB set.

Aspect 19: The apparatus of any of the Aspects 14-18, in which the at least one processor is further configured to increase a coding rate for the SCI-2 in response to a length of the SCI-2 being greater than a total amount of available REs in the initial RB set.

Aspect 20: The apparatus of any of the Aspects 14-19, in which the at least one processor is further configured to drop transmission of the SCI-2 in response to determining an unlicensed sub-band containing the SCI-2 and a stage one sidelink control information message (SCI-1) is occupied.

Aspect 21: The apparatus of any of the Aspects 14-20, in which the at least one processor is further configured to repeat the transmitting of the SCI-2 in each of the plurality of unlicensed sub-bands in response to repeating transmission of a stage one sidelink control information message (SCI-1) in each of the plurality of unlicensed sub-bands when the SCI-2 fits into a single RB set and perform the transmitting if any of the plurality of unlicensed sub-bands is determined to be unoccupied.

Aspect 22: The apparatus of Aspect 14, in which the at least one processor transmits by uniformly distributing segments of the SCI-2 over the wideband carrier.

Aspect 23: The apparatus of Aspect 14, in which the at least one processor transmits by distributing the SCI-2 over the wideband carrier, with a mapping of the SCI-2 starting: at a first frequency within the wideband carrier; and at a time of a first PSSCH symbol carrying an associated demodulation reference signal (DMRS)

Aspect 24: The apparatus of Aspect 23, in which the at least one processor is further configured to map a first portion of the SCI-2 to all REs in the first PSSCH symbol and map a remaining portion of the SCI-2 to a subsequent PSSCH symbol, in response to a length of the SCI-2 being greater than a quantity of available resource elements in the wideband carrier.

Aspect 25: The apparatus of Aspect 23, in which the at least one processor is further configured to map the SCI-2 with a frequency step size based on a ratio between a first quantity of available REs and a second quantity of REs needed for the SCI-2, the at least one processor is configured to map in response to a length of the SCI-2 being less than the first quantity of available REs.

Aspect 26: The apparatus of any of the Aspects 22-25, in which the at least one processor is configured to transmit when a quantity of occupied unlicensed sub-bands is less than a threshold failure rate mapped to a selected coding rate.

Aspect 27: An apparatus for wireless communication, comprising: means for performing a clear channel assessment (CCA) for each of a plurality of unlicensed sub-bands in a wideband carrier; means for determining whether at least one of the plurality of unlicensed sub-bands is occupied; and means for transmitting a partial physical sidelink shared channel (PSSCH) along with a stage two sidelink control information (SCI-2) across the wideband carrier based on the determining.

Aspect 28: The apparatus of Aspect 27, in which the means for transmitting comprises: means for decreasing a coding rate for the SCI-2 based on a total quantity of unlicensed sub-bands in the wideband carrier; and means for multiplexing the partial PSSCH with the SCI-2.

Aspect 29: The apparatus of Aspect 27 or 28, in which the means for transmitting is based on a quantity of occupied unlicensed sub-bands is less than a threshold failure rate mapped to a selected coding rate.

Aspect 30: The apparatus of any of the Aspects 27-29, in which the means for transmitting comprises means for mapping the SCI-2 to resource elements (REs) ; at a frequency within an initial resource block (RB) set including a stage one sidelink control information message (SCI-1) , and at a time of a first PSSCH symbol carrying an associated demodulation reference signal (DMRS) .

The foregoing disclosure provides illustration and description, but is not intended to be exhaustive or to limit the aspects to the precise form disclosed. Modifications and variations may be made in light of the above disclosure or may be acquired from practice of the aspects.

As used, the term “component” is intended to be broadly construed as hardware, firmware, and/or a combination of hardware and software. As used, a processor is implemented in hardware, firmware, and/or a combination of hardware and software.

Some aspects are described in connection with thresholds. As used, satisfying a threshold may, depending on the context, refer to a value being greater than the threshold, greater than or equal to the threshold, less than the threshold, less than or equal to the threshold, equal to the threshold, not equal to the threshold, and/or the like.

It will be apparent that systems and/or methods described may be implemented in different forms of hardware, firmware, and/or a combination of hardware and software. The actual specialized control hardware or software code used to implement these systems and/or methods is not limiting of the aspects. Thus, the operation and behavior of the systems and/or methods were described without reference to specific software code-it being understood that software and hardware can be designed to implement the systems and/or methods based, at least in part, on the description.

Even though particular combinations of features are recited in the claims and/or disclosed in the specification, these combinations are not intended to limit the disclosure of various aspects. In fact, many of these features may be combined in ways not specifically recited in the claims and/or disclosed in the specification. Although each dependent claim listed below may directly depend on only one claim, the disclosure of various aspects includes each dependent claim in combination with every other claim in the claim set. A phrase referring to “at least one of” a list of items refers to any combination of those items, including single members. As an example, “at least one of: a, b, or c” is intended to cover a, b, c, a-b, a-c, b-c, and a-b-c, as well as any combination with multiples of the same element (e.g., a-a, a-a-a, a-a-b, a-a-c, a-b-b, a-c-c, b-b, b-b-b, b-b-c, c-c, and c-c-c or any other ordering of a, b, and c) .

No element, act, or instruction used should be construed as critical or essential unless explicitly described as such. Also, as used, the articles “a” and “an” are intended to include one or more items, and may be used interchangeably with “one or more. ” Furthermore, as used, the terms “set” and “group” are intended to include one or more items (e.g., related items, unrelated items, a combination of related and unrelated items, and/or the like) , and may be used interchangeably with “one or more. ” Where only one item is intended, the phrase “only one” or similar language is used. Also, as used, the terms “has, ” “have, ” “having, ” and/or the like are intended to be open-ended terms. Further, the phrase “based on” is intended to mean “based, at least in part, on” unless explicitly stated otherwise.

Claims

A method of wireless communication by a sidelink transmitting device, comprising:

performing a clear channel assessment (CCA) for each of a plurality of unlicensed sub-bands in a wideband carrier;

determining whether at least one of the plurality of unlicensed sub-bands is occupied; and

transmitting a partial physical sidelink shared channel (PSSCH) along with a stage two sidelink control information (SCI-2) across the wideband carrier based on the determining.
The method of claim 1, in which the transmitting comprises:

decreasing a coding rate for the SCI-2 based on a total quantity of unlicensed sub-bands in the wideband carrier; and

multiplexing the partial PSSCH with the SCI-2.
The method of claim 1, in which the transmitting occurs when a quantity of occupied unlicensed sub-bands is less than a threshold failure rate mapped to a selected coding rate.
The method of claim 1, in which:

the transmitting comprises mapping the SCI-2 to resource elements (REs) ;

the REs starting:

at a frequency within an initial resource block (RB) set including a stage one sidelink control information message (SCI-1) , and

at a time of a first PSSCH symbol carrying an associated demodulation reference signal (DMRS) .
The method of claim 4, further comprising mapping a remaining portion of the SCI-2 to a subsequent RB set in response to a length of the SCI-2 being greater than a total amount of available REs in the initial RB set.
The method of claim 4, further comprising increasing a coding rate for the SCI-2 in response to a length of the SCI-2 being greater than a total amount of available REs in the initial RB set.
The method of claim 1, further comprising dropping transmission of the SCI-2 in response to determining an unlicensed sub-band containing the SCI-2 and a stage one sidelink control information message (SCI-1) is occupied.
The method of claim 1, further comprising repeating the transmitting of the SCI-2 in each of the plurality of unlicensed sub-bands in response to repeating transmission of a stage one sidelink control information message (SCI-1) in each of the plurality of unlicensed sub-bands when the SCI-2 fits into a single RB set and performing the transmitting if any of the plurality of unlicensed sub-bands is determined to be unoccupied.
The method of claim 1, in which the transmitting comprises uniformly distributing segments of the SCI-2 over the wideband carrier.
The method of claim 1, in which the transmitting comprises uniformly distributing the SCI-2 over the wideband carrier, with a mapping of the SCI-2 starting: at a first frequency within the wideband carrier; and at a time of a first PSSCH symbol carrying an associated demodulation reference signal (DMRS) .
The method of claim 10, further comprising mapping a first portion of the SCI-2 to all REs in the first PSSCH symbol and mapping a remaining portion of the SCI-2 to a subsequent PSSCH symbol, in response to a length of the SCI-2 being greater than a quantity of available resource elements in the wideband carrier.
The method of claim 10, further comprising mapping the SCI-2 with a frequency step size based on a ratio between a first quantity of available REs and a second quantity of REs needed for the SCI-2, the mapping occurring in response to a length of the SCI-2 being less than the first quantity of available REs.
The method of claim 10, in which the transmitting occurs when a quantity of occupied unlicensed sub-bands is less than a threshold failure rate mapped to a selected coding rate.
An apparatus for wireless communication, comprising:

a memory; and

at least one processor coupled to the memory, the at least one processor configured:

to perform a clear channel assessment (CCA) for each of a plurality of unlicensed sub-bands in a wideband carrier;

to determine whether at least one of the plurality of unlicensed sub-bands is occupied; and

to transmit a partial physical sidelink shared channel (PSSCH) along with a stage two sidelink control information (SCI-2) across the wideband carrier based on the determining.
The apparatus of claim 14, in which the at least one processor is further configured to transmit by:

decreasing a coding rate for the SCI-2 based on a total quantity of unlicensed sub-bands in the wideband carrier; and

multiplexing the partial PSSCH with the SCI-2.
The apparatus of claim 14, in which the at least one processor is further configured to transmit when a quantity of occupied unlicensed sub-bands is less than a threshold failure rate mapped to a selected coding rate.
The apparatus of claim 14, in which:

the at least one processor is further configured to transmit by mapping the SCI-2 to resource elements (REs) ;

the REs starting:

at a frequency within an initial resource block (RB) set including a stage one sidelink control information message (SCI-1) , and

at a time of a first PSSCH symbol carrying an associated demodulation reference signal (DMRS) .
The apparatus of claim 17, in which the at least one processor is further configured to map a remaining portion of the SCI-2 to a subsequent RB set in response to a length of the SCI-2 being greater than a total amount of available REs in the initial RB set.
The apparatus of claim 17, in which the at least one processor is further configured to increase a coding rate for the SCI-2 in response to a length of the SCI-2 being greater than a total amount of available REs in the initial RB set.
The apparatus of claim 14, in which the at least one processor is further configured to drop transmission of the SCI-2 in response to determining an unlicensed sub-band containing the SCI-2 and a stage one sidelink control information message (SCI-1) is occupied.
The apparatus of claim 14, in which the at least one processor is further configured to repeat the transmitting of the SCI-2 in each of the plurality of unlicensed sub-bands in response to repeating transmission of a stage one sidelink control information message (SCI-1) in each of the plurality of unlicensed sub-bands when the SCI-2 fits into a single RB set and perform the transmitting if any of the plurality of unlicensed sub-bands is determined to be unoccupied.
The apparatus of claim 14, in which the at least one processor is further configured to transmit by uniformly distributing segments of the SCI-2 over the wideband carrier.
The apparatus of claim 14, in which the at least one processor is further configured to transmit by distributing the SCI-2 over the wideband carrier, with a mapping of the SCI-2 starting: at a first frequency within the wideband carrier; and at a time of a first PSSCH symbol carrying an associated demodulation reference signal (DMRS) .
The apparatus of claim 23, in which the at least one processor is further configured to map a first portion of the SCI-2 to all REs in the first PSSCH symbol and map a remaining portion of the SCI-2 to a subsequent PSSCH symbol, in response to a length of the SCI-2 being greater than a quantity of available resource elements in the wideband carrier.
The apparatus of claim 23, in which the at least one processor is further configured to map the SCI-2 with a frequency step size based on a ratio between a first quantity of available REs and a second quantity of REs needed for the SCI-2, the at least one processor is configured to map in response to a length of the SCI-2 being less than the first quantity of available REs.
The apparatus of claim 14, in which the at least one processor is further configured to transmit when a quantity of occupied unlicensed sub-bands is less than a threshold failure rate mapped to a selected coding rate.
An apparatus for wireless communication, comprising:

means for performing a clear channel assessment (CCA) for each of a plurality of unlicensed sub-bands in a wideband carrier;

means for determining whether at least one of the plurality of unlicensed sub-bands is occupied; and

means for transmitting a partial physical sidelink shared channel (PSSCH) along with a stage two sidelink control information (SCI-2) across the wideband carrier based on the determining.
The apparatus of claim 27, in which the means for transmitting comprises:

means for decreasing a coding rate for the SCI-2 based on a total quantity of unlicensed sub-bands in the wideband carrier; and

means for multiplexing the partial PSSCH with the SCI-2.
The apparatus of claim 27, in which the means for transmitting transmits based on whether a quantity of occupied unlicensed sub-bands is less than a threshold failure rate mapped to a selected coding rate.
The apparatus of claim 27, in which the means for transmitting comprises means for mapping the SCI-2 to resource elements (REs) ;

at a frequency within an initial resource block (RB) set including a stage one sidelink control information message (SCI-1) , and

at a time of a first PSSCH symbol carrying an associated demodulation reference signal (DMRS) .