Contention Window Size Adjustment Procedure for Sidelink GroupCast

Abstract

An apparatus, method, and system for a contention window size adjustment procedure for a sidelink groupcast is disclosed. The apparatus (500) includes a processor (505) and a memory (510). The processor (505) is configured to transmit a physical shared control channel ("PSCCH") and a physical shared sidelink channel ("PSSCH") corresponding to a groupcast data transmission. The processor (505) is configured to receive a physical shared feedback channel ("PSFCH") including hybrid automatic repeat request ("HARQ") feedback after a predetermined number of slots of the corresponding groupcast transmission. The processor (505) is configured to determine a contention window size adjustment for the groupcast PSSCH based on the transmitted groupcast HARQ feedback associated with the PSSCH within a reference duration.

Description

[Technical field]

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS This application claims the benefit of U.S. Provisional Patent Application No. 63 / 249,758, entitled "Contention window size adjustment procedure for sidelink groupcast," to Karthikeyan Ganesan et al., filed September 29, 2021, which is incorporated herein by reference.

[0002] The subject matter disclosed herein relates generally to wireless communications, and more particularly, to a contention window size adjustment procedure for sidelink groupcast. [Background technology]

[0003] In wireless networks, devices may connect directly to each other using a technique called sidelink communication, which is a communication paradigm that allows cellular devices to communicate their data without relaying it through the network. [Prior art documents] [Non-patent literature]

[0004] [Non-Patent Document 1] 3GPP(registered trademark) TS 37.213 Summary of the Invention [Means for solving the problem]

[0005] An apparatus, method, and system for a contention window size adjustment procedure for sidelink groupcast are disclosed.

[0006] In one embodiment, a first apparatus includes a processor and a memory coupled to the processor. In one embodiment, the processor is configured to cause the apparatus to transmit a physical shared control channel ("PSCCH") and a physical shared sidelink channel ("PSSCH") corresponding to a groupcast data transmission. In one embodiment, the processor is configured to cause the apparatus to receive a physical shared feedback channel ("PSFCH") including hybrid automatic repeat request ("HARQ") feedback after a predetermined number of slots of a corresponding groupcast transmission. In one embodiment, the processor is configured to cause the apparatus to determine a contention window size adjustment for the groupcast PSSCH based on the transmitted groupcast HARQ feedback associated with the PSSCH within a reference duration.

[0007] In one embodiment, the first method transmits a PSCCH and a PSSCH corresponding to a groupcast data transmission. In one embodiment, the first method receives a PSFCH including HARQ feedback a predetermined number of slots after the corresponding groupcast transmission. In one embodiment, the first method determines a contention window size adjustment for the groupcast PSSCH based on the transmitted groupcast HARQ feedback associated with the PSSCH within a reference duration.

[0008] In one embodiment, the second device includes a processor and a memory coupled to the processor. In one embodiment, the processor is configured to cause the device to receive a PSCCH and a PSSCH corresponding to a groupcast data transmission. In one embodiment, the processor is configured to cause the device to transmit a PSFCH including HARQ feedback after a predetermined number of slots of a corresponding groupcast transmission to determine a contention window size adjustment for the groupcast PSSCH based on the transmitted groupcast HARQ feedback related to the PSSCH within a reference duration.

[0009] In one embodiment, the second method receives a PSCCH and a PSSCH corresponding to a groupcast data transmission. In one embodiment, the second method transmits a PSFCH including HARQ feedback a predetermined number of slots after the corresponding groupcast transmission to determine a contention window size adjustment for the groupcast PSSCH based on the transmitted groupcast HARQ feedback associated with the PSSCH within a reference duration.

[0010] A more particular description of the embodiments briefly described above will be made by reference to specific embodiments that are illustrated in the accompanying drawings, in which the embodiments will be described and explained with more specificity and detail, with the understanding that these drawings illustrate only some embodiments and therefore should not be considered limiting in scope. [Brief description of the drawings]

[0011] [Figure 1] FIG. 1 is a schematic block diagram illustrating an embodiment of a wireless communication system for a contention window size adjustment procedure for sidelink groupcast. [Diagram 2] A diagram showing an example of channel access in New Radio ("NR")-U. [Diagram 3]FIG. 1 illustrates user equipment ("UE")-to-UE relaying. [Figure 4] FIG. 1 illustrates one embodiment of an NR protocol stack. [Diagram 5] FIG. 1 is a block diagram illustrating an embodiment of a user equipment device that may be used for a contention window size adjustment procedure for sidelink groupcast. [Figure 6] FIG. 1 is a schematic block diagram illustrating an embodiment of a network device that may be used for a contention window size adjustment procedure for sidelink groupcast. [Figure 7] 1 is a flow diagram illustrating an embodiment of a method for a contention window size adjustment procedure for sidelink groupcast. [Figure 8] 1 is a flow diagram illustrating an embodiment of a method for a contention window size adjustment procedure for sidelink groupcast. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0012] As will be appreciated by one skilled in the art, aspects of the embodiments may be embodied as a system, apparatus, method or program product. Accordingly, the embodiments may take the form of an all-hardware embodiment, an all-software embodiment (including firmware, resident software, microcode, etc.) or an embodiment combining software and hardware aspects.

[0013] For example, the disclosed embodiments may be implemented as a hardware circuit comprising custom very large scale integrated ("VLSI") circuits or gate arrays, off-the-shelf semiconductors such as logic chips, transistors, or other discrete components. The disclosed embodiments may also be implemented in programmable hardware devices such as field programmable gate arrays, programmable array logic, programmable logic devices, etc. As another example, the disclosed embodiments may include one or more physical or logical blocks of executable code which may be organized, for example, as an object, procedure, or function.

[0014] Furthermore, embodiments may take the form of a program product embodied in one or more computer readable storage devices storing machine readable code, computer readable code, hereinafter referred to as code, and / or program code. The storage devices may be tangible, non-transitory, and / or non-transmitting. The storage devices may not embody signals. In certain embodiments, the storage devices employ only signals to access the code.

[0015] Any combination of one or more computer readable media may be utilized. A computer readable medium may be a computer readable storage medium. A computer readable storage medium may be a storage device that stores the code. A storage device may be, for example, but not limited to, an electronic, magnetic, optical, electromagnetic, infrared, holographic, micro-mechanical, or semiconductor system, apparatus, or device, or any suitable combination thereof.

[0016] More specific examples (non-exhaustive list) of storage devices include the following: an electrical connection having one or more wires, a portable computer diskette, a hard disk, a random access memory ("RAM"), a read-only memory ("ROM"), an erasable programmable read-only memory ("EPROM" or flash memory), a portable compact disk read-only memory ("CD-ROM"), an optical storage device, a magnetic storage device, or any suitable combination thereof. In the context of this specification, a computer-readable storage medium may be any tangible medium that can contain or store a program for use by or in connection with an instruction execution system, apparatus, or device.

[0017] The code for carrying out the operations of the embodiments may be any number of lines and may be written in any combination of one or more programming languages, including object-oriented programming languages ​​such as Python, Ruby, Java, Smalltalk, C++, ordinary procedural programming languages ​​such as the "C" programming language, and / or machine code such as assembly language. The code may run entirely on the user's computer, partially on the user's computer as a standalone software package, partially on the user's computer and partially on a remote computer, or entirely on a remote computer or server. In the latter scenario, the remote computer may be connected to the user's computer via any type of network, including a local area network ("LAN"), wireless LAN ("WLAN"), or wide area network ("WAN"), or a connection to an external computer may be made (e.g., via the Internet using an Internet Service Provider ("ISP").

[0018] Furthermore, the described features, structures, or characteristics of the embodiments may be combined in any suitable manner. In the following description, numerous specific details, such as examples of programming, software modules, user selections, network transactions, database queries, database structures, hardware modules, hardware circuits, hardware chips, and the like, are provided to provide a thorough understanding of the embodiments. However, one skilled in the art will recognize that the embodiments may be implemented without one or more of the specific details, or with other methods, components, materials, and the like. In other cases, well-known structures, materials, or operations are not shown or described in detail to avoid obscuring aspects of the embodiments.

[0019] Reference throughout this specification to "one embodiment," "an embodiment," or similar language means that a particular feature, structure, or characteristic described in connection with an embodiment is included in at least one embodiment. Thus, throughout this specification, the appearance of the phrases "in one embodiment," "in an embodiment," and similar language may, but do not necessarily, all refer to the same embodiment and may mean "one or more, but not all, embodiments" unless otherwise specified. The terms "including," "comprising," "having," and variations thereof mean "including, but not limited to," unless otherwise specified. An enumerated list of items does not imply that any or all of the items are mutually exclusive, unless otherwise specified. Additionally, the terms "a," "an," and "the" refer to "one or more," unless otherwise specified.

[0020] As used herein, a list using the conjunction "and / or" includes any single item in the list or a combination of items in the list. For example, a list of A, B, and / or C includes only A, only B, only C, a combination of A and B, a combination of B and C, a combination of A and C, or a combination of A, B, and C. As used herein, a list using the term "one or more of" includes any single item in the list or a combination of items in the list. For example, one or more of A, B, and C includes only A, only B, only C, a combination of A and B, a combination of B and C, a combination of A and C, or a combination of A, B, and C. As used herein, a list using the term "one of" includes only one of any single item in the list. For example, "one of A, B, and C" includes only A, only B, or only C, and excludes the combination of A, B, and C. As used herein, "a member selected from the group consisting of A, B, and C" includes only one of A, B, or C, and excludes the combination of A, B, and C. As used herein, "a member selected from the group consisting of A, B, and C and combinations thereof" includes only A, only B, only C, the combination of A and B, the combination of B and C, the combination of A and C, or the combination of A, B, and C.

[0021] Aspects of the embodiments are described below with reference to schematic flow charts and / or schematic block diagrams of methods, apparatus, systems, and program products according to the embodiments. It will be understood that each block of the schematic flow charts and / or schematic block diagrams, and combinations of blocks in the schematic flow charts and / or schematic block diagrams, may be implemented by code. This code may be provided to a processor of a general purpose computer, a special purpose computer, or other programmable data processing apparatus to generate a machine, such that the instructions executed by the processor of the computer or other programmable data processing apparatus create means for performing the functions / acts specified in the flow charts and / or block diagrams.

[0022] The code may be stored in a storage device that can instruct a computer, other programmable data processing apparatus, or other device to function in a particular manner, such that the instructions stored in the storage device produce an article of manufacture that includes instructions that implement the functions / acts specified in the flow charts and / or block diagrams.

[0023] The code may be loaded into a computer, other programmable data processing apparatus, or other device to cause a series of operational steps to be performed on the computer, other programmable apparatus, or other device to generate a computer-implemented process such that the code executing on the computer or other programmable apparatus provides a process for performing the functions / operations specified in the flow charts and / or block diagrams.

[0024] The flowcharts and / or block diagrams in the Figures illustrate the architecture, functionality, and operation of possible implementations of apparatus, systems, methods, and program products according to various embodiments. In this regard, each block in the flowcharts and / or block diagrams may represent a module, segment, or portion of code that includes one or more executable instructions of code for implementing the specified logical function(s).

[0025] It should also be noted that in some alternative implementations, the functions noted in the blocks may occur out of the order noted in the figures. For example, two blocks shown in succession may in fact be executed substantially concurrently, or the blocks may be executed in the reverse order, depending on the functionality involved. Other steps and methods may be conceived that are equivalent in function, logic, or effect to one or more blocks of the illustrated figures, or portions thereof.

[0026] Although various types of arrows and lines may be used in the flow charts and / or block diagrams, they are understood not to limit the scope of the corresponding embodiments. Indeed, some arrows or other connecting lines may be used to indicate only the logical flow of the illustrated embodiments. For example, arrows may indicate waiting or monitoring periods of unspecified duration between recited steps of the illustrated embodiments. It should also be noted that each block of the block diagrams and / or flow charts, and combinations of blocks in the block diagrams and / or flow charts, may be implemented by dedicated hardware-based systems that perform the specified functions or operations, or a combination of dedicated hardware and code.

[0027] The description of the elements in each figure may refer to the elements in the procedure figures. Like numbers refer to like elements in all figures (including alternative embodiments of like elements).

[0028] Generally, the present disclosure describes systems, methods, and apparatus for a contention window size adjustment procedure for sidelink groupcast. In certain embodiments, the method may be performed using computer code embodied in a computer readable medium. In certain embodiments, the apparatus or system may include a computer readable medium including computer readable code that, when executed by a processor, causes the apparatus or system to perform at least a portion of the solutions described below.

[0029] The Type 1 channel access describing the contention window size adaptation procedure described in 3GPP TS 37.213 (herein incorporated by reference) is for the Uu interface and, more specifically, is designed for the unicast physical downlink shared channel ("PDSCH"), the physical uplink shared channel ("PUSCH"), and for transport block ("TB") and code block group ("CBG") based transmissions. However, such contention window size ("CWS") adjustment procedures may require further consideration of groupcast or multicast traffic, given the different HARQ feedback types in groupcast support, e.g., groupcast HARQ feedback option 1 (common NACK), groupcast HARQ feedback option 2 (dedicated ACK / NACK) defined in NR Rel16 Sidelink.

[0030] FIG. 1 illustrates a wireless communication system 100 supporting CSI enhancement for higher frequencies according to an embodiment of the present disclosure. In one embodiment, the wireless communication system 100 includes at least one remote unit 105, a radio access network ("RAN") 120, and a mobile core network 130. The RAN 120 and the mobile core network 130 form a mobile communication network. The RAN 120 may be comprised of a base unit 121 with which the remote unit 105 communicates using a wireless communication link 115. Although a specific number of remote units 105, base units 121, wireless communication links 115, RAN 120, and mobile core network 130 are illustrated in FIG. 1, one skilled in the art should recognize that any number of remote units 105, base units 121, wireless communication links 115, RAN 120, and mobile core network 130 may be included in the wireless communication system 100.

[0031] In one implementation, the RAN 120 complies with a 5G system defined in the 3rd Generation Partnership Project ("3GPP") specifications. For example, the RAN 120 may be a new generation radio access network ("NG-RAN") that implements a NR RAT and / or a 3GPP Long Term Evolution ("LTE") RAT. In another example, the RAN 120 may include a non-3GPP RAT (e.g., a Wi-Fi or a WLAN compliant with the Institute of Electrical and Electronics Engineers ("IEEE") 802.11 family). In another implementation, the RAN 120 complies with an LTE system defined in the 3GPP specifications. However, more broadly, the wireless communication system 100 may implement any other open or proprietary communication network, such as the Worldwide Interoperability for Microwave Access ("WiMAX") or IEEE 802.16 family of standards, among other networks. This disclosure is not intended to be limited to any particular wireless communication system architecture or protocol implementation.

[0032] In one embodiment, the remote unit 105 may include a computing device such as a desktop computer, a laptop computer, a personal digital assistant ("PDA"), a tablet computer, a smartphone, a smart television (e.g., a television connected to the Internet), a smart appliance (e.g., an appliance connected to the Internet), a set-top box, a game console, a security system (including security cameras), an in-vehicle computer, a network device (e.g., a router, a switch, a modem), etc. In some embodiments, the remote unit 105 includes a wearable device such as a smart watch, a fitness band, an optical head mounted display, etc. Additionally, the remote unit 105 may be referred to as a UE, a subscriber unit, a mobile phone, a mobile station, a user, a terminal, a mobile terminal, a fixed terminal, a subscriber station, a user terminal, a wireless transmit / receive unit ("WTRU"), a device, or by other terms used in the art. In various embodiments, the remote unit 105 includes a subscriber identity and / or identification module ("SIM") and a mobile equipment ("ME") that provides mobile terminal functions (e.g., wireless transmission, handover, voice encoding and decoding, error detection and correction, signaling, and access to the SIM). In particular embodiments, the remote unit 105 may include terminal equipment ("TE") and / or may be incorporated into a home appliance or device (e.g., a computing device as described above).

[0033] The remote units 105 may communicate directly with one or more of the base units 121 in the RAN 120 by uplink ("UL") and downlink ("DL") communication signals. Additionally, the UL and DL communication signals may be transmitted over a wireless communication link 123, where the RAN 120 is an intermediate network that provides the remote units 105 with access to the mobile core network 130.

[0034] In some embodiments, the remote unit 105 communicates with an application server via a network connection with the mobile core network 130. For example, an application 107 (e.g., a web browser, a media client, a telephony and / or a voice over Internet protocol ("VoIP") application) in the remote unit 105 may trigger the remote unit 105 to establish a protocol data unit ("PDU") session (or other data connection) with the mobile core network 130 via the RAN 120. The mobile core network 130 then relays traffic between the remote unit 105 and the application server (e.g., a content server 151 in the packet data network 150) using the PDU session. The PDU session represents a logical connection between the remote unit 105 and the user plane function ("UPF") 131.

[0035] To establish a PDU session (or PDN connection), the remote unit 105 needs to be registered with the mobile core network 130 (also referred to as being "attached to the mobile core network" in the context of fourth generation ("4G") systems). It should be noted that the remote unit 105 may establish one or more PDU sessions (or other data connections) with the mobile core network 130. Thus, the remote unit 105 may have at least one PDU session for communicating with the packet data network 150, which may represent, for example, the Internet. The remote unit 105 may establish additional PDU sessions for communicating with other data networks and / or other communication peers.

[0036] In the context of 5G systems ("5GS"), the term "PDU session" refers to a data connection that provides end-to-end ("E2E") user plane ("UP") connectivity between a remote unit 105 and a particular data network ("DN") via the UPF 131. A PDU session supports one or more Quality of Service ("QoS") flows. In certain embodiments, there may be a one-to-one mapping between QoS flows and QoS profiles such that all packets belonging to a particular QoS flow have the same 5G QoS Identifier ("5QI").

[0037] In the context of 4G / LTE systems, such as the Evolved Packet System ("EPS"), a Packet Data Network ("PDN") connection (also called an EPS session) provides an E2E UP connection between a remote unit and the PDN. The PDN connection procedure establishes an EPS bearer, i.e., a tunnel between the remote unit 105 and a Packet Gateway ("PGW", not shown) in the mobile core network 130. In certain embodiments, there is a one-to-one mapping between EPS bearers and QoS profiles, such that all packets belonging to a particular EPS bearer have the same QoS Class Identifier ("QCI").

[0038] The base units 121 may be distributed across a geographic region. In certain embodiments, the base units 121 may be referred to as an access terminal, an access point, a base, a base station, a Node B ("NB"), an evolved Node B (abbreviated as eNodeB or "eNB" and also known as an evolved Universal Terrestrial Radio Access Network ("E-UTRAN") Node B), a 5G / NR Node B ("gNB"), a home Node B, a relay node, a RAN node, or any other terminology used in the art. The base units 121 are generally part of a RAN, such as the RAN 120, which may include one or more controllers communicatively coupled to one or more corresponding base units 121. These and other elements of a radio access network are not shown, but are generally familiar to those skilled in the art. The base units 121 connect to a mobile core network 130 via the RAN 120.

[0039] The base unit 121 may serve multiple remote units 105 in a serving area, e.g., a cell or a sector of a cell, via a wireless communication link 123. The base unit 121 may directly communicate with one or more of the remote units 105 by communication signals. In general, the base unit 121 transmits DL communication signals to serve the remote units 105 in the time, frequency, and / or space domains. Furthermore, the DL communication signals may be transmitted over the wireless communication link 123. The wireless communication link 123 may be any suitable carrier of a licensed or unlicensed radio spectrum. The wireless communication link 123 facilitates communication between one or more of the remote units 105 and / or one or more of the base units 121. It should be noted that during NR-U operation, the base unit 121 and the remote units 105 communicate over an unlicensed radio spectrum.

[0040] In one embodiment, a sidelink 125 connection allows direct communication between two devices without the base station participating in the transmission and reception of data traffic.

[0041] In one embodiment, the mobile core network 130 is a 5GC or evolved packet core ("EPC") that may be coupled to a packet data network 150, such as the Internet and private data networks, among other data networks. The remote units 105 may have a subscription or other account with the mobile core network 130. Each mobile core network 130 belongs to a single public land mobile network ("PLMN"). This disclosure is not intended to be limited to any particular wireless communications system architecture or protocol implementation.

[0042] The mobile core network 130 includes several network functions ("NFs"). As shown, the mobile core network 130 includes at least one UPF 131. The mobile core network 130 also includes multiple control plane ("CP") functions, including but not limited to an Access and Mobility Management Function ("AMF") 133 that serves the RAN 120, a Session Management Function ("SMF") 135, a Network Exposure Function ("NEF"), a Policy Control Function ("PCF") 137, a Unified Data Management function ("UDM"), and a User Data Repository ("UDR").

[0043] The UPF 131 is responsible for packet routing and forwarding, packet inspection, QoS handling, and external PDU sessions for interconnecting data networks ("DNs") in the 5G architecture. The AMF 133 is responsible for NAS signaling termination, NAS encryption and integrity protection, registration management, connection management, mobility management, access authentication and authorization, and security context management. The SMF 135 is responsible for session management (i.e., session establishment, modification, release), remote unit (i.e., UE) IP address allocation and management, DL data notification, and traffic steering configuration of the UPF for proper traffic routing.

[0044] The NEF is responsible for making network data and resources easily accessible to customers and network partners. Service providers may activate new capabilities and expose them through APIs. These APIs allow third-party authorized applications to monitor and configure the network behavior for many different subscribers (i.e. connected devices with different applications). The PCF 137 is responsible for the unified policy framework, providing policy rules to the CP function, and access subscription information for policy decisions in the UDR.

[0045] The UDM is responsible for Authentication and Key Agreement ("AKA") credential generation, user identification, access authorization, and subscription management. The UDR is a repository of subscriber information and may be used to provide services to several network functions. For example, the UDR may store subscription data, policy related data, subscriber related data that is allowed to be exposed to third party applications, etc. In some embodiments, the UDM is co-located with the UDR and is depicted as a combined entity "UDM / UDR" 139.

[0046] In various embodiments, the mobile core network 130 may also include an Authentication Server Function ("AUSF") (acting as an authentication server), a Network Repository Function ("NRF") (providing registration and discovery of NF services, allowing NFs to identify appropriate services to each other and communicate with each other via application programming interfaces ("APIs"), or other NFs defined for 5GC. In particular embodiments, the mobile core network 130 may include an Authentication, Authorization, and Accounting ("AAA") server.

[0047] In various embodiments, the mobile core network 130 supports different types of mobile data connections and different types of network slices, with each mobile data connection utilizing a particular network slice, where a "network slice" refers to a portion of the mobile core network 130 optimized for a particular traffic type or communication service. A network instance is specified by single-network slice selection assistance information ("S-NSSAI"), while a set of network slices that the remote unit 105 is authorized to use is specified by network slice selection assistance information ("NSSAI").

[0048] Here, "NSSAI" refers to a vector value that includes one or more S-NSSAI values. In certain embodiments, various network slices may include separate instances of network functions, such as SMF 135 and UPF 131. In some embodiments, different network slices may share some common network functions, such as AMF 133. For ease of illustration, different network slices are not shown in FIG. 1, but their support is assumed. When different network slices are deployed, the mobile core network 130 may include a network slice selection function ("NSSF") that is responsible for selecting a network slice instance to serve the remote unit 105, determining the allowed NSSAIs, and determining the AMF set used to serve the remote unit 105.

[0049] 1, one skilled in the art should recognize that any number and type of network functions may be included in the mobile core network 130. Furthermore, in variants of LTE in which the mobile core network 130 includes an EPC, the depicted network functions may be replaced by appropriate EPC entities, such as a Mobility Management Entity ("MME"), a Serving Gateway ("SGW"), a PGW, a Home Subscriber Server ("HSS"), etc. For example, the AMF 133 may be mapped to the MME, the SMF 135 may be mapped to the control plane portion of the PGW and / or the MME, the UPF 131 may be mapped to the SGW and the user plane portion of the PGW, the UDM / UDR 139 may be mapped to the HSS, etc.

[0050] Although FIG. 1 shows components of a 5G RAN and a 5G core network, the described embodiments apply to other types of communication networks and RATs, including variants of IEEE 802.11, Global System for Mobile Communications ("GSM" i.e., 2G digital cellular networks), General Packet Radio Service ("GPRS"), UMTS, variants of LTE, CDMA 2000, Bluetooth, ZigBee, Sigfox, etc.

[0051] In the following description, the term "gNB" is used for a base station, but it may be replaced by any other radio access node, e.g., RAN node, eNB, base station ("BS"), access point ("AP"), NR, etc. Furthermore, the operation is primarily described in the context of 5G NR. However, the proposed solutions / methods are equally applicable to other mobile communication systems supporting enhanced CSI for higher frequencies.

[0052] By way of background, in NR-U, both DL and UL channel access rely on listen before talk ("LBT"). Before every transmission, the gNB and / or UE first sense the channel to determine if there is any ongoing communication. When the communication channel is a wideband unlicensed carrier, the clear channel assessment ("CCA") procedure relies on detecting the energy levels in multiple sub-bands of the communication channel, as shown in Figure 2. With regard to LBT in Rel.16 NR-U, beamforming is not considered and only omnidirectional LBT is envisaged.

[0053] [Table 1]

[0054] In Rel.16 NR-U, regarding CW adjustment for transmissions including PDSCH and PUSCH, If new HARQ feedback is available for the previous CW update, the feedback for the latest COT at which the new feedback is received is used. If the HARQ feedback is ACK, CW is set to CWmin. If the HARQ feedback is a NACK (or if the gNB or UE retransmits the TB without feedback within the window defined below), CW is set to min(CW×2 + 1, CWmax). · The window starts at the end of the reference duration and has a duration of max(Xms, duration of the transmit burst from the beginning of the reference duration + 1ms). If the absence of other technologies cannot be guaranteed (same conditions as in the existing spec for the other cases), then X = 5. Otherwise, X = 10. Otherwise, if no new HARQ feedback is available, the CW remains the same. NOTE: HARQ feedback includes any implicit method of HARQ feedback determination.

[0055] For HARQ feedback based on TBs in a single LBT subband, the CW is reset if at least one "ACK" is received or at least one NDI is toggled for a TB transmitted within the reference duration. Note: HARQ feedback includes any implicit method of HARQ feedback determination.

[0056] For HARQ feedback based on CBGs in a single LBT subband, the CW is reset if an "ACK" is received for at least 10% of the CBGs within the reference duration when all CBGs remain within the LBT subband. For the purposes of CWS coordination, a CBG TI set to 0 is considered an ACK. NOTE: HARQ feedback includes any implicit method of HARQ feedback determination.

[0057] A channel without explicit feedback uses the CWS last updated by a channel with explicit feedback and using the same CAPC if such a channel exists, otherwise it uses the minimum CWS corresponding to the CAPC.

[0058] For CWS adjustment for an LBT subband when a single contention window is maintained per LBT subband, the CBGs (if any) and TBs that overlap partially or completely with that LBT subband are taken into account. The CW is reset if an "ACK" is received for at least 10% of the CBGs or at least one TB within the reference duration. NOTE: Other procedures for contention window adjustment in an LBT subband are also applicable. The UE may choose to apply only TB-based feedback for CW adjustment.

[0059] For CWS adjustment for DL, when a single contention window is maintained for multiple LBT subbands, CBGs (if present) and TBs that overlap partially or completely with those multiple LBT subbands are taken into account. The CW is reset if an "ACK" is received for at least 10% of the CBGs or at least one TB within the reference duration. NOTE: Other procedures for contention window adjustment within an LBT subband are also applicable.

[0060] According to 3GPP TS 37.213, Contention Window Adjustment Procedures (herein incorporated by reference), when an eNB / gNB transmits a transmission on a channel that includes a PDSCH associated with a channel access priority class p, the eNB / gNB shall adjust the contention window value CW p and maintain the CW before step 1 of the procedure described in this section for their transmission, as described in section 4.1.1. p Adjust.

[0061] When the eNB sends a transmission on a channel that includes a PDSCH associated with a channel access priority class p, the eNB shall select a contention window value CW p and for their transmission, prior to step 1 of the procedure described in section 4.1.1, use the following steps to p Adjust. For every priority class p∈{1,2,3,4}, CW p = CW min,p Set it as If at least Z = 80% of the HARQ-ACK values ​​corresponding to the PDSCH transmissions in reference subframe k are determined as NACKs, then the CW p Increase x to the next highest allowed value and stay in step 2, else go to step 1.

[0062] The reference subframe k is the starting subframe of the most recent transmission on the channel made by the eNB for which at least some HARQ-ACK feedback is expected to be available.

[0063] The eNB calculates the CW frame for every priority class p ∈ {1, 2, 3, 4} based on a given reference subframe k. p Adjust the value once.

[0064] Regarding the determination of Z, If an eNB transmission for which HARQ-ACK feedback is available starts in the second slot of subframe k, then in addition to the HARQ-ACK value corresponding to the PDSCH transmission in subframe k, the HARQ-ACK value corresponding to the PDSCH transmission in subframe k + 1 is also used. If the HARQ-ACK value corresponds to a PDSCH transmission on an LAA SCell that is allocated by an (E)PDCCH transmitted on the same LAA SCell, · If no HARQ-ACK feedback is detected by the eNB for a PDSCH transmission, or if the eNB detects “DTX”, “NACK / DTX”, or “any” state, it is counted as a NACK. If the HARQ-ACK value corresponds to a PDSCH transmission on an LAA SCell that is allocated by an (E)PDCCH transmitted on another serving cell, · If HARQ-ACK feedback for a PDSCH transmission is detected by the eNB, then a “NACK / DTX” or “any” state is counted as a NACK and a “DTX” state is ignored. If no HARQ-ACK feedback is detected by the eNB for a PDSCH transmission, If PUCCH format 1b with channel selection is expected to be used by the UE, the "NACK / DTX" states corresponding to "no transmission" as described in subclause 10.1.2.2.1, subclause 10.1.3.1 and subclause 10.1.3.2.1 are counted as NACK and the "DTX" state corresponding to "no transmission" is ignored. Otherwise, the HARQ-ACK for the PDSCH transmission is ignored. If a PDSCH transmission has two codewords, the HARQ-ACK value for each codeword is considered separately. A bundled HARQ-ACK spanning M subframes is considered as M HARQ-ACK responses.

[0065] When the eNB transmits on a channel starting at time t0 a transmission that includes a PDCCH / EPDCCH using DCI format 0A / 0B / 4A / 4B and does not include a PDSCH associated with a channel access priority class p, the eNB shall determine the contention window value CW p and for their transmission, prior to step 1 of the procedure described in section 4.1.1, use the following steps to p Adjust. For every priority class p∈{1,2,3,4}, CW p = CW min,p Set it as t0 to t0+ T CO If less than 10% of the UL transport blocks scheduled by the eNB using the Type 2 channel access procedure (described in clause 4.2.1.2) are successfully received in the time interval between p Increase x to the next highest allowed value and stay in step 2, else go to step 1.

[0066] T CO is calculated as described in Section 4.2.1.0.3.

[0067] When the gNB sends a transmission on a channel that includes a PDSCH associated with a channel access priority class p, the gNB shall select a contention window value CW p and for their transmission, prior to step 1 of the procedure described in section 4.1.1, use the following steps to p Adjust. 1) For every priority class p∈{1,2,3,4}, CW p = CW min,p Set it as follows. 2) HARQ-ACK feedback is sent to the CW p If it is available after the last update of CW, proceed to step 3. Otherwise, if the gNB's transmission after the procedure described in clause 4.1.1 does not include retransmissions or pfor duration T from the end of the reference duration corresponding to the earliest DL channel occupancy after the last update of w If so, proceed to step 5; otherwise, proceed to step 4. 3) The HARQ-ACK feedback corresponding to the PDSCH within the reference duration of the most recent DL channel occupancy for which HARQ-ACK feedback is available is used as follows: a. If at least one HARQ-ACK feedback is an “ACK” for a PDSCH with transport block based feedback or at least 10% of the HARQ-ACK feedbacks are “ACK” for a PDSCH CBG that was at least partially transmitted on a channel with code block group based feedback, go to step 1, else go to step 4. 4) CW for every priority class p∈{1,2,3,4} p to the next highest permitted value. 5) For every priority class p∈{1,2,3,4}, CW p Keep it as is and go to step 2.

[0068] The reference duration and duration T in the above procedure w is defined as follows: The reference duration corresponding to a gNB initiated channel occupation including a PDSCH transmission is defined in this clause as the duration starting from the start of the channel occupation to the end of the first slot in which at least one unicast PDSCH is transmitted on all resources allocated for PDSCH or to the end of the first transmission burst by the gNB including a unicast PDSCH transmitted on all resources allocated for PDSCH, whichever occurs first. If the channel occupation includes a unicast PDSCH but does not include any unicast PDSCH transmitted on all resources allocated for that PDSCH, the duration of the first transmission burst by the gNB in ​​the channel occupation including a unicast PDSCH is the reference duration for CWS adjustment. T w = max(T A , T B + 1ms), where T B is the duration of the transmission burst from the beginning of the reference duration expressed in ms, and T A = 5ms, otherwise T A = 10ms.

[0069] If the gNB transmits a transmission on a channel using a type 1 channel access procedure associated with channel access priority class p and the transmission is not associated with an explicit HARQ-ACK feedback by the corresponding UE, the gNB shall, prior to step 1 of the procedure described in subclause 4.1.1, determine the last CW used for any DL transmission on the channel using a type 1 channel access procedure associated with channel access priority class p. p Using CW p If the corresponding channel access priority class p was not used for any DL transmission on the channel, p = CW min,p is used.

[0070] When a UE sends a transmission using a type 1 channel access procedure associated with a channel access priority class p on a channel, the UE shall set a contention window value CW p and for their transmission prior to step 1 of the procedure described in subsection 4.2.1.1, the CW p Adjust. When the UE receives an UL grant or AUL-DFI, the contention window sizes for all priority classes are adjusted as follows: If the NDI value of at least one HARQ process associated with HARQ_ID_ref is toggled, or ref If the HARQ-ACK value of at least one of the HARQ processes associated with the HARQ_ID_ref received within the earliest AUL-DFI after +3 indicates ACK, For every priority class p∈{1,2,3,4}, CW p = CW min,p Set it as follows. Otherwise, CW for every priority class p∈{1,2,3,4} p to the next highest permitted value. One or more previous transmissions {T0, ... ,T n} exists, N or more subframes have elapsed since the start subframe of the previous transmission, and neither a UL grant nor an AUL-DFI has been received, where each transmission T i For contentionWindowSizeTimer > 0, N = max(contentionWindowSizeTimer, T i burst length + 1), otherwise N = 0, then CW p is adjusted as follows: · CW for every priority class p∈{1,2,3,4} p to the next highest permitted value. · CW pis adjusted once. Otherwise, if the UE sends a transmission using a Type 1 channel access procedure before N subframes have elapsed since the start of the previous UL transmission burst using the Type 1 channel access procedure and neither a UL grant nor an AUL-DFI is received; · CW p remains the same. The UE receives an UL grant or the AUL-DFI uses a type 1 channel access procedure for one or more previous transmissions {T0, ... ,T n} feedback, and N or more subframes have passed since the start subframe of the previous transmission, and neither UL grant nor AUL-DFI has been received, where N = max(contentionWindowSizeTimer, T i If N = 0, the UE shall use the CW p may be recalculated as follows: UE is CW p , using the Type 1 channel access procedure T0 The value returned is the value used to send the UE is CW p Send {T0, ... ,T n} and update them sequentially. HARQ_ID_ref' is toggled, or n Ti if the HARQ-ACK value of at least one of the HARQ processes associated with HARQ_ID_ref' received within the earliest AUL-DFI after HARQ_ID_ref'+3 indicates ACK; For every priority class p∈{1,2,3,4}, CW p = CW min,p Set it as follows. Otherwise, CW for every priority class p∈{1,2,3,4} p to the next highest permitted value. If the UE sends a transmission using the Type 1 channel access procedure before N subframes have elapsed since the start of the previous UL transmission burst using the Type 1 channel access procedure and neither a UL grant nor an AUL-DFI is received; · CW p remains the same.

[0071] HARQ_ID_ref is the reference subframe n ref is the HARQ process ID of the UL-SCH in the reference subframe n ref is determined as follows: The UE is in subframe n g If a UL grant or AUL-DFI is received in subframe n w is the subframe n in which the UE transmitted the UL-SCH using the Type 1 channel access procedure. g - This is the latest subframe before 3. The UE starts at subframe n0 and continues through subframes n0, n1, . . . , n w If the UL-SCH in subframe n0 is not PUSCH mode 1 starting in the second slot of the subframe, then the UL-SCH in subframe n0 is PUSCH mode 1 starting in the second slot of the subframe. ref is subframe n0. The UE starts in the second slot of subframe n0 and continues to transmit across subframes n0, n1, . . . , n w When transmitting a transmission including PUSCH mode 1 without gaps in reference frame n ref are subframes n0 and n1. Otherwise, reference subframe n ref is the subframe n w It is.

[0072] HARQ_ID_ref' is the reference subframe n Ti is the HARQ process ID of the UL-SCH in the reference subframe n Tiis a transmission T that uses a Type 1 channel access procedure and has had N subframes elapse and has not received either a UL grant or an AUL-DFI. i The starting subframe of the

[0073] When an AUL-DFI using DCI format 0A is indicated to a UE that is activated for AUL transmission and transmission mode 2 is configured for the UE for grant-based uplink transmission, spatial HARQ-ACK bundling is performed by a logical OR operation over multiple codewords for HARQ processes that are not configured for autonomous UL transmission.

[0074] CW during an ongoing channel access procedure p If N changes, the UE increments the counter N init and applies it to the ongoing channel access procedure.

[0075] The UE uses the Type 1 channel access procedure in subframes n0, n1, . . . , n w-1 , , and if no transmission including PUSCH can be transmitted in the set of subframes, then CW p You may keep the value of as it is.

[0076] The UE checks whether the reference subframe of the last scheduled transmission is n ref If p∈{1,2,3,4}, then CW p The value of {overscore (R)} may remain the same as for the last scheduled transmission involving a PUSCH that uses a Type 1 channel access procedure.

[0077] When a UE sends a transmission using a type 1 channel access procedure associated with a channel access priority class p on a channel, the UE shall set a contention window value CWp and for their transmission prior to step 1 of the procedure described in subsection 4.2.1.1, the CW p Adjust. 1) For every priority class p∈{1,2,3,4}, CW p = CW min,p Set it as follows. 2) HARQ-ACK feedback is sent to the CW p If the UE's transmissions after the procedure described in subclause 4.2.1.1 do not include retransmissions or the CW transmitted after the procedure described in subclause 4.1.1 are available after the last update of the UE's transmissions, proceed to step 3. p The duration T from the end of the reference duration corresponding to the earliest UL transmission burst after the last update of w If so, proceed to step 5; otherwise, proceed to step 4. 3) The HARQ-ACK feedback corresponding to the PUSCH within the reference duration of the latest UL transmission burst for which HARQ-ACK feedback is available is used as follows: a. If at least one HARQ-ACK feedback is “ACK” for a PUSCH with Transport Block (TB) based transmission or at least 10% of the HARQ-ACK feedbacks are “ACK” for a PUSCH with Code Block Group (CBG) based transmission, go to step 1, else go to step 4. 4) CW for every priority class p∈{1,2,3,4} p to the next highest permitted value. 5) For every priority class p∈{1,2,3,4}, CW p Keep it as is and go to step 2.

[0078] The HARQ-ACK feedback, reference duration, and duration T w is defined as follows: HARQ-ACK feedback for PUSCH transmissions is expected to be provided to the UE either explicitly or implicitly, where the implicit HARQ-ACK feedback for the purpose of contention window adjustment in this subclause is determined based on an indication of a new transmission or a retransmission in the DCI scheduling the PUSCH as follows: · If a new transmission is indicated, then “ACK” is assumed for the transport block or code block group in the corresponding PUSCH for TB-based and CBG-based transmissions, respectively. · If a retransmission is indicated for a TB based transmission, a "NACK" is assumed for the corresponding transport block in the PUSCH. If a retransmission is indicated for a CBG based transmission, then if the bit value of the code block group transmission information (CBGTI) field is '0' or '1' then 'ACK' or 'NACK' respectively is assumed for the corresponding CBG in the corresponding PUSCH. The reference duration corresponding to a UE initiated occupancy of a channel including a PUSCH transmission is defined in this subclause as the duration starting from the start of the occupancy of the channel to the end of the first slot in which at least one unicast PUSCH is transmitted on all resources allocated for PUSCH or to the end of the first transmission burst by the gNB including a unicast PUSCH transmitted on all resources allocated for PDSCH, whichever occurs first. If the occupancy of a channel includes a unicast PDSCH but does not include any unicast PDSCH transmitted on all resources allocated for that PUSCH, the duration of the first transmission burst by the UE in the occupancy of the channel including a PUSCH is the reference duration for CWS adjustment. T w = max(T A , T B + 1ms), where T Bis the duration of the transmission burst from the beginning of the reference duration expressed in ms, and T A = 5ms, otherwise T A = 10ms.

[0079] If the UE transmits a transmission on a channel using a type 1 channel access procedure associated with channel access priority class p, and the transmission is not associated with an explicit or implicit HARQ-ACK feedback as described above in this subclause, the UE shall, prior to step 1 of the procedure described in subclause 4.2.1.1, determine the most recent CW used for any UL transmission on the channel using a type 1 channel access procedure associated with channel access priority class p. p Using CW p If the corresponding channel access priority class p is not for any UL transmission on the channel, then the CW p = CW min,p is used.

[0080] In general, the subject matter described herein is directed to sidelink channel access procedures for CWS coordination of groupcast data transmissions including different SL groupcast HARQ feedback options. · CWS adjustment for Groupcast HARQ Feedback Option 1 involves that NACK feedback received from group member UEs within the reference duration is taken into account for the CWS adjustment procedure. · CWS adjustment for Groupcast HARQ Feedback Option 2 involves the number of NACK feedbacks received from group member UEs within a reference duration being taken into account for the CWS adjustment procedure. A different definition of the PSSCH reference duration is proposed that takes groupcast into account.

[0081] In a first embodiment directed to CWS adjustment for groupcast HARQ feedback option 2 (dedicated ACK / NACK), the decision of CWS adjustment for PSSCH transmission based on sidelink groupcast may be based on the configured / signaled sidelink groupcast HARQ feedback option 2, and the transmitting ("Tx") UE may have transmitted the PSSCH using sidelink groupcast HARQ feedback option 2 by transmitting SCI format 2A with the cast type indicator set to "01".

[0082] The CWS coordination procedure for Groupcast HARQ Feedback Option 2 includes a number of ACK or NACK feedbacks received from one or more group member UEs within a reference duration, where the reference duration corresponds to a channel occupancy initiated by a Tx UE including a transmission of a groupcast PSSCH (associated with Groupcast HARQ Feedback Option 2) as the duration starting from the start of the channel occupancy to the end of the first slot in which at least one groupcast PSSCH (associated with Groupcast HARQ Feedback Option 2) is transmitted on all resources allocated for the groupcast PSSCH or to the end of the first transmission burst by the Tx UE including a groupcast PSSCH (associated with Groupcast HARQ Feedback Option 2) transmitted on all resources allocated for the groupcast PSSCH, whichever occurs first. If the occupancy of a channel includes a groupcast PSSCH (associated with Groupcast HARQ Feedback Option 2) but does not include any groupcast PSSCH (associated with Groupcast HARQ Feedback Option 2) transmitted on resources allocated for that groupcast PSSCH, the duration of the first transmission burst by the UE in the occupancy of the channel including the groupcast PSSCH (associated with Groupcast HARQ Feedback Option 2) is the reference duration for CWS adjustment.

[0083] Another example for the reference duration corresponds to a channel occupancy initiated by a Tx UE including a groupcast PSSCH transmission (associated with groupcast HARQ feedback option 2) as the duration starting from the start of the channel occupancy until at least HARQ-ACK feedback is expected or received from at least one PSFCH reception opportunity of several PSFCH reception opportunities in the PSFCH resources (associated with groupcast PSSCH) from member UEs of one or more groups belonging to the same L2 destination ID.

[0084] In one embodiment, for every channel access priority class p∈{1,2,3,4}, set CWp = CWmin,p. If the UE receives a PSFCH associated with groupcast HARQ feedback option 2, and if at least Z=X% of the HARQ-ACK feedback values ​​are determined to be "NACK" corresponding to groupcast PSSCH transmission within the reference duration from at least one PSFCH reception opportunity out of several PSFCH reception opportunities in the PSFCH resources corresponding to every identity M_"ID" of the UE where the UE expects to receive a corresponding PSSCH, increase the CWS of every priority class to the next highest allowed value or min(CWp×2 + 1, CWmax,p).

[0085] Otherwise, if at least Z=Y% of the HARQ-ACK feedback values ​​are determined to be “ACK” corresponding to a group-cast PSSCH transmission within the reference duration corresponding to every UE identity M_“ID” for which the UE expects to receive a corresponding PSSCH, then CWS is set to CWmin,p (go to step 1 described in the first bullet point (e.g., step 1 described in TS 37.213)).

[0086] If no HARQ-ACK feedback is detected for a groupcast PSSCH transmission corresponding to any UE identity M_"ID" from which the UE expects to receive a corresponding PSSCH belonging to the same L2 destination ID, or if a Tx UE detects "DTX", it is counted as a NACK corresponding to the receiving ("Rx") UE identity M_"ID". If at least Z=X% of the HARQ-ACK values ​​are determined to be "NACKs" from one or more group member UEs belonging to the same L2 destination ID, then the above steps are followed.

[0087] The values ​​of Z=X% and / or Z=Y% for NACK and / or ACK, respectively, may be configured per resource pool or per UE or per destination group or carrier, or may be fixed values ​​defined in the standard. These values ​​may depend on the number of UEs transmitting PSFCH feedback corresponding to the groupcast PSSCH transmission.

[0088] In a second embodiment directed to CWS adjustment for groupcast HARQ feedback option 1 (common NACK feedback resource), the decision of contention window size (CWS) adjustment for sidelink groupcast based PSSCH transmission may be based on the configured / signaled sidelink groupcast HARQ feedback option 1, and when the UE is configured to transmit SCI Format 2B or SCI Format 2A with the cast type indicator set to '11', the UE may be configured with sidelink groupcast HARQ feedback option 1 using one of the following methods:

[0089] In a first implementation, the CWS coordination procedure for groupcast HARQ feedback option 1 (common NACK) includes NACK feedback received from group member UEs on the common NACK feedback resource within a reference duration, where the reference duration corresponds to channel occupancy initiated by a Tx UE including transmission of a groupcast PSSCH (associated with groupcast HARQ feedback option 1) as the duration starting from the start of channel occupancy to the end of the first slot in which at least one groupcast PSSCH (associated with groupcast HARQ feedback option 1) is transmitted on resources allocated for the groupcast PSSCH or to the end of the first transmission burst by the Tx UE including a groupcast PSSCH (associated with groupcast HARQ feedback option 1) transmitted on all resources allocated for the groupcast PSSCH, whichever occurs first. If the occupancy of a channel includes a groupcast PSSCH (associated with Groupcast HARQ Feedback Option 1) but does not include any groupcast PSSCH (associated with Groupcast HARQ Feedback Option 1) transmitted on all resources allocated for that groupcast PSSCH, the duration of the first transmission burst by the UE in the occupancy of the channel including the groupcast PSSCH (associated with Groupcast HARQ Feedback Option 1) is the reference duration for CWS adjustment.

[0090] In one embodiment, for every channel access priority class p∈{1,2,3,4}, set CWp = CWmin,p, and if the UE receives a PSFCH associated with groupcast HARQ feedback option 1, and if the HARQ-ACK feedback value corresponding to the groupcast PSSCH transmission within the reference duration is determined to be “NACK”, increase the CWS for every priority class to the next highest allowed value or min(CWp×2 + 1, CWmax,p).

[0091] Otherwise, if the UE receives a PSFCH associated with groupcast HARQ feedback option 1, and if the HARQ-ACK feedback value corresponding to the groupcast PSSCH transmission within the reference duration is determined to be “ACK”, then proceed to the first step above.

[0092] Otherwise, if no PSFCH reception is detected for a PSFCH reception opportunity for a PSSCH transmission within the reference duration, it is considered an "ACK" response and CWS is set to CWmin,p.

[0093] In a second implementation, reference signal received power ("RSRP") measurement from PSFCH reception may be used as another metric to determine the CWS adjustment procedure, where the threshold may be set based on at least one of the maximum number of UEs (meeting the minimum communication range ("MCR"), communication range requirement) that transmit PSFCH to Tx UEs that started occupying the channel within the reference duration, the target received power parameter Po, and the fractional path-loss compensation parameter α. When the measured RSRP of the received PSFCH exceeds the threshold, increase the CWS of every priority class to the next allowed value or min(CWp×2 + 1, CWmax,p). When the measured RSRP of the received PSFCH is below the threshold, the CWS is set to CWmin,p.

[0094] In a third implementation, the CWS adjustment procedure for groupcast HARQ feedback option 1 (common NACK) includes the number of NACK feedbacks received from group member UEs within a reference duration, where the reference duration corresponds to a channel occupation initiated by a Tx UE including a PSSCH transmission as a duration starting from the start of the channel occupation until at least HARQ-ACK feedback is expected from PSFCH reception of a number of slots in which at least one groupcast PSSCH (associated with groupcast HARQ feedback option 1) is transmitted on all resources allocated for the groupcast PSSCH. Another example for the reference duration corresponds to a channel occupation initiated by a Tx UE including a groupcast PSSCH transmission (associated with groupcast HARQ feedback option 1) as a duration starting from the start of the channel occupation until at least HARQ-ACK feedback is expected from at least one PSFCH reception opportunity of a number of PSFCH reception opportunities in PSFCH resources associated with the groupcast PSSCH.

[0095] In one embodiment, for every channel access priority class p∈{1,2,3,4}, set CWp = CWmin,p, and if the UE receives a PSFCH associated with groupcast HARQ feedback option 1, and if at least Z = X% of the HARQ-ACK feedback values ​​(e.g., the count includes one HARQ-ACK feedback value per PSFCH reception opportunity) are determined to be "NACK" corresponding to groupcast PSSCH transmission within the reference duration, or the RSRP threshold of the received PSFCH exceeds a predefined value for X% of the PSFCH reception opportunities, increase the CWS of every priority class to the next higher allowed value or min(CWp×2 + 1, CWmax,p).

[0096] Otherwise, if no PSFCH reception is detected for a PSFCH reception opportunity for a PSSCH transmission within the reference duration, it is considered as an "ACK" response and if at least Z = Y% of the HARQ-ACK feedback values ​​are determined to be "ACK" corresponding to a groupcast PSSCH transmission within the reference duration or the RSRP threshold of the received PSFCH is less than a predefined value for Y% of the PSFCH reception opportunities, the CWS is set to CWmin,p (go to step 1 described in the first bullet point (e.g., step 1 described in TS 37.213)). The values ​​of Z=X% and / or Z=Y% can be configured per resource pool, per UE, per destination group, per carrier, or be fixed values ​​specified in the standard.

[0097] In a third embodiment directed to blind retransmissions and / or mixed retransmissions including both HARQ-based and blind retransmissions, if the channel occupation includes unicast or groupcast based PSSCH transmissions but does not include any HARQ feedback enabled PSSCH transmitted on all resources allocated for PSSCH (e.g., the HARQ enable bit is not set to "enable" in the sidelink control information ("SCI")), the duration of the first transmission burst by the UE within the channel occupation that is enabled and transmitted with HARQ feedback PSSCH is the reference duration for CWS adjustment.

[0098] For example, when a Tx UE decides to transmit a transport block ("TB") using blind retransmission in an occupied channel, the CWS adjustment remains the same. In another example, when a Tx UE decides to transmit a TB using a mix of blind retransmission and HARQ feedback enabled transmission, the reference duration (and thus the CWS) is set according to the first HARQ feedback enabled PSSCH transmission within the reference duration.

[0099] In one embodiment, when only broadcast-based PSSCH is transmitted during the reference duration, the CWS adjustment for broadcast is always set to be the same, but the duration of the first transmission burst by the UE in the channel occupation enabled and transmitted in the HARQ feedback PSSCH is the reference duration for all cast-type CWS adjustments.

[0100] In the fourth embodiment directed to UE-UE relaying, the term eNB / gNB is used for base station but can be replaced by any other radio access node, e.g., BS, eNB, gNB, AP, NR, etc. Furthermore, the proposed method is primarily described in the context of 5G NR. However, the proposed solution / method is equally applicable to other mobile communication systems supporting serving cells / carriers configured for sidelink communication over a PC5 interface.

[0101] As used herein, the following terms are used:

[0102] UE-Network Relay: N relays

[0103] UE-UE Relay: UE Relay

[0104] Relay = Any of the above relays

[0105] Tx Remote UE (UE1) 302 is a UE that has some application data to be transmitted to another remote UE, shown in Figure 3 as Rx Remote UE (UE3) 306, via Relay (UE2) 304. At a different time, UE3 306 may have data to transmit to UE1 302 via UE2 304, and in this context UE3 306 plays the role of a transmitter UE. The terms and roles shown in Figure 3 relate only to specific data packets.

[0106] In the fourth embodiment, the relay UE 304 may have multiple unicast connections with one or more UE1 302 (Tx remote UEs) using a first interface and with one or more Rx remote UEs using a second interface. The contention window size adjustment procedure decision for the relay UE (UE2 304 in FIG. 3) may depend on HARQ feedback received from one or more Rx remote UEs in the second interface by reusing the procedures described in the first and second embodiments, but those same procedures may be equally applicable to unicast PSSCH transmissions occurring in the second interface with one or more Rx remote UEs. These Rx remote UEs are not necessarily part of the same destination ID as described in the first and second embodiments. A transport block may have multiplexed data for multiple Rx remote UEs, and in one example, the contention window size adjustment decision depends on HARQ feedback received from one or more Rx remote UEs belonging within the reference duration.

[0107] In another embodiment, a Tx remote UE may have connections with multiple relay UEs for transmitting the same or different TBs belonging to the same destination ID. In such a case, the contention window size determination depends on the HARQ feedback received from one or more relay UEs configured to transmit data towards the same destination, as described in the first and second embodiments, for all cast types.

[0108] FIG. 4 illustrates an NR protocol stack 400 according to an embodiment of the present disclosure. FIG. 4 illustrates a remote unit 105, a base unit 121, and a mobile core network 130, which represent a set of UEs interacting with RAN nodes and NFs (e.g., AMFs) in the core network. As shown, the protocol stack 400 includes a user plane protocol stack 405 and a control plane protocol stack 410. The user plane protocol stack 405 includes a physical ("PHY") layer 415, a medium access control ("MAC") sublayer 420, a radio link control ("RLC") sublayer 425, a packet data convergence protocol ("PDCP") sublayer 430, and a service data adaptation protocol ("SDAP") layer 435. The control plane protocol stack 410 also includes the physical layer 415, the MAC sublayer 420, the RLC sublayer 425, and the PDCP sublayer 430. The control plane protocol stack 410 also includes a radio resource control (“RRC”) sublayer 440 and a non-access stratum (“NAS”) layer 445 .

[0109] The AS protocol stack of the control plane protocol stack 410 consists of at least the RRC, PDCP, RLC, and MAC sublayers, and a physical layer. The AS protocol stack of the user plane protocol stack 405 consists of at least the SDAP, PDCP, RLC, and MAC sublayers, and a physical layer. Layer 2 ("L2") is divided into the SDAP, PDCP, RLC, and MAC sublayers. Layer 3 ("L3") includes the RRC sublayer 440 and the NAS layer 445 of the control plane, e.g., the Internet Protocol ("IP") layer or the PDU layer (not shown) of the user plane. L1 and L2 are referred to as "lower layers", such as PUCCH / PUSCH or MAC CE, while L3 and above (e.g., transport layer, application layer) are referred to as "higher layers" or "upper layers", such as RRC.

[0110] The physical layer 415 provides transport channels to the MAC sublayer 420. The MAC sublayer 420 provides logical channels to the RLC sublayer 425. The RLC sublayer 425 provides RLC channels to the PDCP sublayer 430. The PDCP sublayer 430 provides radio bearers to the SDAP sublayer 435 and / or the RRC layer 440. The SDAP sublayer 435 provides QoS flows to the mobile core network 130 (e.g., 5GC). The RRC layer 440 provides carrier aggregation and / or dual connectivity addition, modification, and release. The RRC layer 440 also manages the establishment, configuration, maintenance, and release of signaling radio bearers ("SRBs") and data radio bearers ("DRBs"). In a particular embodiment, the RRC entity functions for detection of and recovery from radio link failures.

[0111] FIG. 5 illustrates a user equipment device 500 that may be used for a contention window size adjustment procedure for sidelink groupcast according to an embodiment of the disclosure. In various embodiments, the user equipment device 500 is used to implement one or more of the solutions described above. The user equipment device 500 may be an embodiment of a UE, such as the remote unit 105 and / or the UE 205 described above. Furthermore, the user equipment device 500 may include a processor 505, a memory 510, an input device 515, an output device 520, and a transceiver 525. In some embodiments, the input device 515 and the output device 520 are combined into a single device, such as a touch screen. In certain embodiments, the user equipment device 500 may not include any input device 515 and / or output device 520. In various embodiments, the user equipment device 500 may include one or more of the processor 505, the memory 510, and the transceiver 525, and may not include the input device 515 and / or the output device 520.

[0112] As shown, the transceiver 525 includes at least one transmitter 530 and at least one receiver 535, where the transceiver 525 communicates with one or more base units 121. In addition, the transceiver 525 may support at least one network interface 540 and / or an application interface 545. The application interface 545 may support one or more APIs. The network interface 540 may support 3GPP reference points, such as Uu and PC5. As will be appreciated by one skilled in the art, other network interfaces 540 may be supported.

[0113] The processor 505, in one embodiment, may include any known controller capable of executing computer-readable instructions and / or performing logical operations. For example, the processor 505 may be a microcontroller, a microprocessor, a central processing unit ("CPU"), a graphics processing unit ("GPU"), an auxiliary processing unit, a field programmable gate array ("FPGA"), a digital signal processor ("DSP"), a co-processor, an application specific processor, or a similar programmable controller. In some embodiments, the processor 505 executes instructions stored in the memory 510 to perform the methods and routines described herein. The processor 505 is communicatively coupled to the memory 510, the input device 515, the output device 520, and the transceiver 525. In a particular embodiment, the processor 505 may include an application processor (also known as a "main processor") that manages application domains and operating system ("OS") functions, and a baseband processor (also known as a "baseband radio processor") that manages radio functions.

[0114] Memory 510, in one embodiment, is a computer-readable storage medium. In some embodiments, memory 510 includes a volatile computer storage medium. For example, memory 510 may include RAM, including dynamic RAM ("DRAM"), synchronous dynamic RAM ("SDRAM"), and / or static RAM ("SRAM"). In some embodiments, memory 510 includes a non-volatile computer storage medium. For example, memory 510 may include a hard disk drive, a flash memory, or any other suitable non-volatile computer storage device. In some embodiments, memory 510 includes both volatile and non-volatile computer storage media.

[0115] In some embodiments, memory 510 stores data related to enhancing CSI for higher frequencies. For example, memory 510 may store the parameters, configurations, resource allocations, policies, etc. described above. In particular embodiments, memory 510 also stores program code and associated data, such as an operating system or other controller algorithms and one or more software applications operating on user equipment device 500.

[0116] The input device 515, in one embodiment, may include any known computer input device, including a touch panel, buttons, a keyboard, a stylus, a microphone, etc. In some embodiments, the input device 515 may be integrated with the output device 520, for example as a touch screen or similar touch-sensitive display. In some embodiments, the input device 515 includes a touch screen, such that text may be entered using a virtual keyboard displayed on the touch screen and / or by handwriting on the touch screen. In some embodiments, the input device 515 includes two or more different devices, such as a keyboard and a touch panel.

[0117] The output device 520, in one embodiment, is designed to output visual, auditory, and / or tactile signals. In some embodiments, the output device 520 includes an electronically controllable display or display device capable of outputting visual data to a user. For example, the output device 520 may include, but is not limited to, an LCD display, an LED display, an OLED display, a projector, or similar display device capable of outputting images, text, and the like to a user. As another non-limiting example, the output device 520 may include a wearable display that is separate from but communicatively coupled to the remainder of the user equipment device 500, such as a smart watch, smart glasses, a head-up display, and the like. Additionally, the output device 520 may be a component of a smartphone, a personal digital assistant, a television, a table computer, a notebook (laptop) computer, a personal computer, a vehicle dashboard, and the like.

[0118] In certain embodiments, output device 520 includes one or more speakers for generating sound. For example, output device 520 may generate an audible alert or notification (e.g., a beep or chime). In some embodiments, output device 520 includes one or more haptic devices for generating vibration, movement, or other haptic feedback. In some embodiments, all or a portion of output device 520 may be integrated with input device 515. For example, input device 515 and output device 520 may form a touchscreen or similar touch-sensitive display. In other embodiments, output device 520 may be located near input device 515.

[0119] The transceiver 525 includes at least one transmitter 530 and at least one receiver 535. The transceiver 525 may be used to provide UL communication signals to the base unit 121 and receive DL communication signals from the base unit 121 as described herein. Similarly, the transceiver 525 may be used to transmit and receive SL signals (e.g., V2X communications) as described herein. Although only one transmitter 530 and one receiver 535 are shown, the user equipment device 500 may have any suitable number of transmitters 530 and receivers 535. Furthermore, the transmitters 530 and receivers 535 may be any suitable type of transmitter and receiver. In one embodiment, the transceiver 525 includes a first transmitter / receiver pair used to communicate with a mobile communication network over a licensed radio spectrum and a second transmitter / receiver pair used to communicate with a mobile communication network over an unlicensed radio spectrum.

[0120] In certain embodiments, a first transmitter / receiver pair used to communicate with a mobile communications network over a licensed radio spectrum and a second transmitter / receiver pair used to communicate with a mobile communications network over an unlicensed radio spectrum may be combined into a single transceiver unit, e.g., a single chip that performs functions for use in both the licensed and unlicensed radio spectrum. In some embodiments, the first transmitter / receiver pair and the second transmitter / receiver pair may share one or more hardware components. For example, a particular transceiver 525, transmitter 530, and receiver 535 may be implemented as physically separate components that access shared hardware and / or software resources, such as, for example, a network interface 540.

[0121] In various embodiments, one or more transmitters 530 and / or one or more receivers 535 may be implemented and / or integrated in a single hardware component, such as a multi-transceiver chip, a system-on-chip, an ASIC, or other type of hardware component. In certain embodiments, one or more transmitters 530 and / or one or more receivers 535 may be implemented and / or integrated in a multi-chip module. In some embodiments, other components, such as a network interface 540 or other hardware components / circuits, may be integrated in a single chip with any number of transmitters 530 and / or receivers 535. In such embodiments, the transmitters 530 and receivers 535 may be logically configured as a transceiver 525 using one or more common control signals, or as modular transmitters 530 and receivers 535 implemented in the same hardware chip or multi-chip module.

[0122] In one embodiment, the processor 505 transmits a PSCCH and a PSSCH corresponding to a groupcast data transmission. In one embodiment, the processor 505 receives a PSFCH including HARQ feedback a predetermined number of slots after the corresponding groupcast transmission. In one embodiment, the processor 505 determines a contention window size adjustment for the groupcast PSSCH based on the transmitted groupcast HARQ feedback associated with the PSSCH within the reference duration.

[0123] In one embodiment, the processor 505 determines a contention window size adjustment for devices transmitting a groupcast PSSCH using HARQ feedback option 2 based on a proportion of ACK / NACK HARQ feedback received from member UEs of one or more groups belonging to the same L2 destination ID.

[0124] In one embodiment, the processor 505 adjusts the contention window size of the priority class to the next highest allowed value or the calculated value min(CW×2+1, C ... max ), where CW is the contention window size.

[0125] In one embodiment, the processor 505 sets the contention window size of the priority class to a minimum in response to at least Z=Y% of the HARQ-ACK values ​​determined to be “ACK” from one or more group member UEs belonging to the same destination ID within the reference duration.

[0126] In one embodiment, not detecting a PSFCH reception at a PSFCH reception opportunity for a PSSCH transmission within a reference duration indicates a "NACK" response.

[0127] In one embodiment, the processor 505 is configured to, in response to detecting no reception of a PSFCH in a PSFCH reception opportunity for a PSSCH transmission within a reference duration, adjust the contention window size to CW min,p Set to.

[0128] In one embodiment, the values ​​of Z=X% and / or Z=Y% for the NACK and / or ACK, respectively, are configurable or fixed per resource pool, per UE, per destination group or carrier, or some combination thereof.

[0129] In one embodiment, the processor 505 determines a contention window size adjustment for a transmitting UE transmitting a groupcast PSSCH using HARQ feedback option 1 based on a count of the number of NACKs received or based on no PSFCH feedback being detected from multiple PSFCH opportunities corresponding to the groupcast PSSCH.

[0130] In one embodiment, the reference duration corresponds to occupancy of the channel initiated by the transmitting UE as the duration starting from the start of occupancy of the channel to the end of the first slot in which at least one groupcast PSSCH is transmitted on resources allocated for the groupcast PSSCH, or to the end of the first transmission burst by the transmitting UE that includes a groupcast PSSCH transmitted on resources allocated for the groupcast PSSCH.

[0131] In one embodiment, the processor 505 adjusts the contention window size of the priority class to the next highest allowed value or a calculated value min(CW×2+1, C ... max ), where CW is the contention window size.

[0132] In one embodiment, the processor 505 is configured to, in response to detecting no reception of a PSFCH in a plurality of PSFCH reception opportunities for a PSSCH transmission within a reference duration, adjust the contention window size to CW min,p Set to.

[0133] In one embodiment, the reference duration corresponds to the occupancy of the channel initiated by the transmitting UE as the duration starting from the start of the occupancy of the channel until at least HARQ-ACK feedback is expected from at least one PSFCH reception opportunity of several PSFCH reception opportunities in the PSFCH resource from one or more group member UEs belonging to the same L2 destination ID.

[0134] In one embodiment, the processor 505 maintains the contention window size adjustment constant in response to transmission of a transport block by the transmitting UE using blind retransmission, broadcast, HARQ disabled transmission in an occupied channel, or any combination thereof.

[0135] In one embodiment, the processor 505 sets the reference duration according to the first HARQ feedback enabled PSSCH transmission within the reference duration in response to a transmission of a transport block by the transmitting UE using a mixture of blind retransmissions and HARQ feedback enabled transmissions.

[0136] 6 illustrates an embodiment of a network device 600 that may be used for a contention window size adjustment procedure for sidelink groupcast according to an embodiment of the disclosure. In some embodiments, the network device 600 may be an embodiment of a RAN node and its supporting hardware, such as the base unit 121 and / or gNB described above. Additionally, the network device 600 may include a processor 605, a memory 610, an input device 615, an output device 620, and a transceiver 625. In certain embodiments, the network device 600 does not include any input device 615 and / or output device 620.

[0137] As shown, the transceiver 625 includes at least one transmitter 630 and at least one receiver 635, where the transceiver 625 communicates with one or more remote units 105. In addition, the transceiver 625 may support at least one network interface 640 and / or application interface 645. The application interface 645 may support one or more APIs. The network interface 640 may support 3GPP reference points, such as Uu, N1, N2, N3, N5, N6, and / or N7 interfaces. As will be appreciated by one skilled in the art, other network interfaces 640 may be supported.

[0138] When implementing the NEF, the network interface 640 may include an interface for communicating with application functions (i.e., N5) and at least one network function (e.g., UDR, SFC function, UPF) in a mobile communications network such as the mobile core network 130.

[0139] The processor 605, in one embodiment, may include any known controller capable of executing computer-readable instructions and / or performing logical operations. For example, the processor 605 may be a microcontroller, a microprocessor, a CPU, a GPU, an auxiliary processing unit, an FPGA, a DSP, a co-processor, an application specific processor, or a similar programmable controller. In some embodiments, the processor 605 executes instructions stored in the memory 610 to perform the methods and routines described herein. The processor 605 is communicatively coupled to the memory 610, the input device 615, the output device 620, and the transceiver 625. In a particular embodiment, the processor 605 may include an application processor (also known as a "main processor") that manages application domain and OS functions, and a baseband processor (also known as a "baseband radio processor") that manages radio functions. In various embodiments, the processor 605 controls the network device 600 to implement the above-mentioned network entity behaviors (e.g., of a gNB) for the contention window size adjustment procedure for sidelink groupcast.

[0140] Memory 610, in one embodiment, is a computer-readable storage medium. In some embodiments, memory 610 includes a volatile computer storage medium. For example, memory 610 may include RAM, including DRAM, SDRAM, and / or SRAM. In some embodiments, memory 610 includes a non-volatile computer storage medium. For example, memory 610 may include a hard disk drive, a flash memory, or any other suitable non-volatile computer storage device. In some embodiments, memory 610 includes both volatile and non-volatile computer storage media.

[0141] In some embodiments, memory 610 stores data related to enhancing CSI for higher frequencies. For example, memory 610 may store the parameters, configurations, resource allocations, policies, etc. described above. In particular embodiments, memory 610 also stores program code and associated data, such as an OS or other controller algorithms and one or more software applications operating on network device 600.

[0142] The input device 615, in one embodiment, may include any known computer input device including a touch panel, buttons, a keyboard, a stylus, a microphone, etc. In some embodiments, the input device 615 may be integrated with the output device 620, for example as a touch screen or similar touch-sensitive display. In some embodiments, the input device 615 includes a touch screen such that text may be entered using a virtual keyboard displayed on the touch screen and / or by handwriting on the touch screen. In some embodiments, the input device 615 includes two or more different devices, such as a keyboard and a touch panel.

[0143] The output device 620, in one embodiment, may include any known electronically controllable display or display device. The output device 620 may be designed to output visual, auditory, and / or tactile signals. In some embodiments, the output device 620 includes an electronic display capable of outputting visual data to a user. Additionally, the output device 620 may be a component of a smartphone, a personal digital assistant, a television, a table computer, a notebook (laptop) computer, a personal computer, a vehicle dashboard, and the like.

[0144] In certain embodiments, the output device(s) 620 include one or more speakers for generating sound. For example, the output device(s) 620 may generate an audible alert or notification (e.g., a beep or chime). In some embodiments, the output device(s) 620 include one or more haptic devices for generating vibration, movement, or other haptic feedback. In some embodiments, all or a portion of the output device(s) 620 may be integrated with the input device(s) 615. For example, the input device(s) 615 and the output device(s) 620 may form a touchscreen or similar touch-sensitive display. In other embodiments, all or a portion of the output device(s) 620 may be located proximate the input device(s) 615.

[0145] As described above, the transceiver 625 may communicate with one or more remote units and / or with one or more interconnection functions that provide access to one or more PLMNs. The transceiver 625 may communicate with one or more network functions (e.g., in the mobile core network 130). The transceiver 625 operates under the control of the processor 605 to transmit messages, data, and other signals and to receive messages, data, and other signals. For example, the processor 605 may selectively activate the transceiver (or a portion thereof) at a particular time to transmit and receive messages.

[0146] The transceiver 625 may include one or more transmitters 630 and one or more receivers 635. In certain embodiments, the one or more transmitters 630 and / or the one or more receivers 635 may share transceiver hardware and / or circuitry. For example, the one or more transmitters 630 and / or the one or more receivers 635 may share antennas, antenna tuners, amplifiers, filters, oscillators, mixers, modulators / demodulators, power supplies, etc. In one embodiment, the transceiver 625 implements multiple logical transceivers that use different communication protocols or protocol stacks while using common physical hardware.

[0147] In one embodiment, the processor 605 transmits a PSCCH and a PSSCH corresponding to a groupcast data transmission. In one embodiment, the processor 605 transmits a PSFCH including HARQ feedback a predetermined number of slots after the corresponding groupcast transmission to determine a contention window size adjustment for the groupcast PSSCH based on the transmitted groupcast HARQ feedback associated with the PSSCH within the reference duration.

[0148] 7 is a flow diagram of a method 700 for a contention window size adjustment procedure for sidelink groupcast. The method 700 may be performed by a UE described herein, e.g., a remote unit 105 and / or a user equipment device 500. In some embodiments, the method 700 may be performed by a processor executing program code, e.g., a microcontroller, a microprocessor, a CPU, a GPU, an auxiliary processing unit, an FPGA, etc.

[0149] In one embodiment, the method 700 begins by transmitting 705 a PSCCH and a PSSCH corresponding to a groupcast data transmission. In one embodiment, the method 700 receives 710 a PSFCH including HARQ feedback a predetermined number of slots after the corresponding groupcast transmission. In one embodiment, the method 700 determines 715 a contention window size adjustment for the groupcast PSSCH based on the transmitted groupcast HARQ feedback associated with the PSSCH within the reference duration, and the method 700 ends.

[0150] 8 is a flow diagram of a method 800 for a contention window size adjustment procedure for sidelink groupcast. The method 800 may be performed by a network device described herein, e.g., a base unit 121, a gNB, and / or a network equipment device 600. In some embodiments, the method 800 may be performed by a processor executing program code, e.g., a microcontroller, a microprocessor, a CPU, a GPU, an auxiliary processing unit, an FPGA, etc.

[0151] In one embodiment, the method 800 begins by receiving a PSCCH and a PSSCH corresponding to a groupcast data transmission 805. In one embodiment, the method 800 transmits a PSFCH including HARQ feedback a predetermined number of slots after the corresponding groupcast transmission to determine a contention window size adjustment for the groupcast PSSCH based on the transmitted groupcast HARQ feedback associated with the PSSCH within a reference duration 810, and the method 800 ends.

[0152] A first apparatus for a contention window size adjustment procedure for sidelink groupcast is disclosed. The first apparatus may include a UE described herein, e.g., a remote unit 105 and / or a user equipment device 500. In some embodiments, the first apparatus includes a processor that executes program code, e.g., a microcontroller, a microprocessor, a CPU, a GPU, an auxiliary processing unit, an FPGA, etc.

[0153] In one embodiment, a first device includes a processor and a memory coupled to the processor. In one embodiment, the processor is configured to cause the device to transmit a PSCCH and a PSSCH corresponding to a groupcast data transmission. In one embodiment, the processor is configured to cause the device to receive a PSFCH including HARQ feedback after a predetermined number of slots of the corresponding groupcast transmission. In one embodiment, the processor is configured to cause the device to determine a contention window size adjustment for the groupcast PSSCH based on the transmitted groupcast HARQ feedback associated with the PSSCH within a reference duration.

[0154] In one embodiment, the processor is configured to determine a contention window size adjustment for devices transmitting a groupcast PSSCH using HARQ feedback option 2 based on a proportion of ACK / NACK HARQ feedback received from member UEs of one or more groups belonging to the same L2 destination ID.

[0155] In one embodiment, the processor adjusts the contention window size of the priority class to the next highest allowed value or the calculated value min(CW×2+1, C ... max), where CW is the contention window size.

[0156] In one embodiment, the processor is configured to set a contention window size for a priority class to a minimum in response to at least Z=Y% of HARQ-ACK values ​​determined to be “ACK” from one or more group member UEs belonging to the same destination ID within the reference duration.

[0157] In one embodiment, not detecting a PSFCH reception at a PSFCH reception opportunity for a PSSCH transmission within a reference duration indicates a "NACK" response.

[0158] In one embodiment, the processor, in response to detecting no reception of a PSFCH in a PSFCH reception opportunity for a PSSCH transmission within a reference duration, adjusts a contention window size to a CW min,p The ipv4_address setting is configured to be set to .

[0159] In one embodiment, the values ​​of Z=X% and / or Z=Y% for the NACK and / or ACK, respectively, are configurable or fixed per resource pool, per UE, per destination group or carrier, or some combination thereof.

[0160] In one embodiment, the processor is configured to determine a contention window size adjustment for a transmitting UE transmitting a groupcast PSSCH using HARQ feedback option 1 based on a count of a number of received NACKs or based on no PSFCH feedback being detected from multiple PSFCH opportunities corresponding to the groupcast PSSCH.

[0161] In one embodiment, the reference duration corresponds to occupancy of the channel initiated by the transmitting UE as the duration starting from the start of occupancy of the channel to the end of the first slot in which at least one groupcast PSSCH is transmitted on resources allocated for the groupcast PSSCH, or to the end of the first transmission burst by the transmitting UE that includes a groupcast PSSCH transmitted on resources allocated for the groupcast PSSCH.

[0162] In one embodiment, the processor adjusts the contention window size of the priority class to the next highest allowed value or a calculated value min(CW×2+1, C ... max ), where CW is the contention window size.

[0163] In one embodiment, the processor, in response to detecting no reception of a PSFCH in a plurality of PSFCH reception opportunities for a PSSCH transmission within a reference duration, adjusts a contention window size to a CW min,p The ipv4_address setting is configured to be set to .

[0164] In one embodiment, the reference duration corresponds to the occupancy of the channel initiated by the transmitting UE as the duration starting from the start of the occupancy of the channel until at least HARQ-ACK feedback is expected from at least one PSFCH reception opportunity of several PSFCH reception opportunities in the PSFCH resource from one or more group member UEs belonging to the same L2 destination ID.

[0165] In one embodiment, the processor is configured to maintain a constant contention window size adjustment in response to transmission of a transport block by a transmitting UE using blind retransmission, broadcast, HARQ disabled transmission in an occupied channel, or any combination thereof.

[0166] In one embodiment, the processor is configured to, in response to a transmission of a transport block by a transmitting UE using a mixture of blind retransmissions and HARQ feedback enabled transmissions, set the reference duration according to a PSSCH transmission with a first HARQ feedback enabled within the reference duration.

[0167] A first method for a contention window size adjustment procedure for sidelink groupcast is disclosed. The first method may be performed by a UE described herein, e.g., a remote unit 105 and / or a user equipment device 500. In some embodiments, the first method may be performed by a processor executing program code, e.g., a microcontroller, a microprocessor, a CPU, a GPU, an auxiliary processing unit, an FPGA, etc.

[0168] In one embodiment, the first method transmits a PSCCH and a PSSCH corresponding to a groupcast data transmission. In one embodiment, the first method receives a PSFCH including HARQ feedback a predetermined number of slots after the corresponding groupcast transmission. In one embodiment, the first method determines a contention window size adjustment for the groupcast PSSCH based on the transmitted groupcast HARQ feedback associated with the PSSCH within a reference duration.

[0169] In one embodiment, the first method determines a contention window size adjustment for devices transmitting a groupcast PSSCH using HARQ feedback option 2 based on a proportion of ACK / NACK HARQ feedback received from member UEs of one or more groups belonging to the same L2 destination ID.

[0170] In one embodiment, the first method includes adjusting the contention window size of the priority class to the next highest allowed value or the calculated value min(CW×2 + 1, C ... max ), where CW is the contention window size.

[0171] In one embodiment, the first method sets the contention window size of a priority class to a minimum in response to at least Z=Y% of HARQ-ACK values ​​determined to be “ACK” from one or more group member UEs belonging to the same destination ID within a reference duration.

[0172] In one embodiment, not detecting a PSFCH reception at a PSFCH reception opportunity for a PSSCH transmission within a reference duration indicates a "NACK" response.

[0173] In one embodiment, the first method includes, in response to detecting no reception of a PSFCH in a PSFCH reception opportunity for a PSSCH transmission within a reference duration, adjusting a contention window size to a CW min,p Set to.

[0174] In one embodiment, the values ​​of Z=X% and / or Z=Y% for the NACK and / or ACK, respectively, are configurable or fixed per resource pool, per UE, per destination group or carrier, or some combination thereof.

[0175] In one embodiment, the first method determines a contention window size adjustment for a transmitting UE transmitting a groupcast PSSCH using HARQ feedback option 1 based on counting the number of NACKs received or based on no PSFCH feedback being detected from multiple PSFCH opportunities corresponding to the groupcast PSSCH.

[0176] In one embodiment, the reference duration corresponds to occupancy of the channel initiated by the transmitting UE as the duration starting from the start of occupancy of the channel to the end of the first slot in which at least one groupcast PSSCH is transmitted on resources allocated for the groupcast PSSCH, or to the end of the first transmission burst by the transmitting UE that includes a groupcast PSSCH transmitted on resources allocated for the groupcast PSSCH.

[0177] In one embodiment, the first method is to adjust the contention window size of the priority class to the next highest allowed value or a calculated value min(CW×2+1, C ... max ), where CW is the contention window size.

[0178] In one embodiment, the first method includes, in response to detecting no reception of a PSFCH in a plurality of PSFCH reception opportunities for a PSSCH transmission within a reference duration, adjusting a contention window size to a CW min,p Set to.

[0179] In one embodiment, the reference duration corresponds to the occupancy of the channel initiated by the transmitting UE as the duration starting from the start of the occupancy of the channel until at least HARQ-ACK feedback is expected from at least one PSFCH reception opportunity of several PSFCH reception opportunities in the PSFCH resource from one or more group member UEs belonging to the same L2 destination ID.

[0180] In one embodiment, a first method keeps the contention window size adjustment constant in response to transmission of a transport block by the transmitting UE using blind retransmission, broadcast, HARQ disabled transmission in an occupied channel, or any combination thereof.

[0181] In one embodiment, the first method is responsive to a transmitting UE transmitting a transport block using a mix of blind retransmissions and HARQ feedback enabled transmissions to set the reference duration according to the first HARQ feedback enabled PSSCH transmission within the reference duration.

[0182] A second apparatus for a contention window size adjustment procedure for sidelink groupcast is disclosed. The second apparatus may include a network device described herein, such as a base unit 121, a gNB, and / or a network equipment device 600. In some embodiments, the second apparatus may include a processor that executes program code, such as a microcontroller, a microprocessor, a CPU, a GPU, an auxiliary processing unit, an FPGA, etc.

[0183] In one embodiment, the second device includes a processor and a memory coupled to the processor. In one embodiment, the processor is configured to cause the device to receive a PSCCH and a PSSCH corresponding to a groupcast data transmission. In one embodiment, the processor is configured to cause the device to transmit a PSFCH including HARQ feedback after a predetermined number of slots of a corresponding groupcast transmission to determine a contention window size adjustment for the groupcast PSSCH based on the transmitted groupcast HARQ feedback related to the PSSCH within a reference duration.

[0184] A second method for a contention window size adjustment procedure for sidelink groupcast is disclosed. The second method may be performed by a network device described herein, e.g., a base unit 121, a gNB, and / or a network equipment device 600. In some embodiments, the second method may be performed by a processor executing program code, e.g., a microcontroller, a microprocessor, a CPU, a GPU, an auxiliary processing unit, an FPGA, etc.

[0185] In one embodiment, the second method receives a PSCCH and a PSSCH corresponding to a groupcast data transmission. In one embodiment, the second method transmits a PSFCH including HARQ feedback a predetermined number of slots after the corresponding groupcast transmission to determine a contention window size adjustment for the groupcast PSSCH based on the transmitted groupcast HARQ feedback associated with the PSSCH within a reference duration.

[0186] The embodiments may be embodied in other specific forms. The described embodiments are to be considered in all respects only as illustrative and not restrictive. The scope of the invention is therefore indicated by the appended claims rather than by the above description. All changes that come within the meaning and range of equivalency of the claims are to be embraced within their scope. [Explanation of symbols]

[0187] 100 Wireless communication system 105 Remote Unit 107 Applications 115 Wireless Communication Links 120 RAN 121 Base Unit 123 Wireless Communication Links 125 Side Link 130 Mobile Core Network 131 UPF 133 AMF 135 SMF 137 PCF 139 UDM / UDR 150 Packet Data Network 151 Content Server 205 UE 302 Tx Remote UE (UE1) 304 Repeater (UE2) 306 Rx Remote UE (UE3) 400 NR Protocol Stack 405 User Plane Protocol Stack 410 Control Plane Protocol Stack 415 Physical Layer 420 MAC Sublayer 425 RLC Sublayer 430 PDCP Sublayer 435 SDAP Layer 440 RRC Sublayer 445 NAS Layer 500 User Equipment Device 505 Processor 510 Memory 515 Input Devices 520 Output Device 525 Transceiver 530 Transmitter 535 Receiver 540 Network Interface 545 Application Interface 600 Network Equipment 605 Processor 610 Memory 615 Input Devices 620 Output Device 625 Transceiver 630 Transmitter 635 Receiver 640 Network Interface 645 Application Interface 700 methods 800 ways

Claims

1. A user equipment ("UE"), comprising: A processor; a memory coupled to the processor; and wherein the processor causes the UE to: transmitting a Physical Shared Control Channel ("PSCCH") and a Physical Shared Sidelink Channel ("PSSCH") for groupcast data transmission; receiving a physical shared feedback channel ("PSFCH") including groupcast hybrid automatic repeat request ("HARQ") feedback several slots after the groupcast data transmission; determining a contention window size adjustment for a groupcast data transmission based on the groupcast HARQ feedback associated with the PSSCH within a reference duration; A UE configured as follows.

2. 2. The UE of claim 1, wherein the processor is configured to cause the UE to determine the contention window size adjustment based on a proportion of HARQ feedback received from one or more UEs belonging to a same Layer 2 (L2) destination identifier (ID).

3. The UE of claim 2, wherein the processor is configured to cause the UE to set a contention window size based on a priority class value or based on min(CW×2+1, CW max ), depending on the proportion of HARQ feedback received from the one or more UEs that are NACK within the reference duration, where CW is the contention window size.

4. 4. The UE of claim 3, wherein the processor is configured to cause the UE to set the contention window size of the priority class to a minimum in response to the proportion of the HARQ feedback received from the one or more UEs belonging to the same L2 destination ID.

5. 5. The UE of claim 4, wherein the absence of a PSFCH during a PSFCH opportunity within the reference duration indicates a NACK response.

6. The UE of claim 4, wherein the percentage value of the HARQ feedback is configured per resource pool, per UE, per destination group or carrier, or a combination thereof.

7. 4. The UE of claim 3, wherein the processor is configured to cause the UE to determine a contention window size adjustment for a transmitting UE of a groupcast PSSCH based on counting a number of received NACKs or based on not detecting a PSFCH feedback on multiple PSFCH opportunities.

8. 3. The UE of claim 2, wherein the reference duration corresponds to occupancy of a channel starting from a start of occupancy of the channel to an end of a first slot allocated for at least one groupcast PSSCH transmission or to an end of a first transmission burst including a groupcast PSSCH.

9. The processor may provide the UE with a priority class value based on the priority class value or a calculated value min(CW×2+1, CW max 10. The UE of claim 8, configured to cause a contention window size to be set based on CW, where CW is the contention window size.

10. The processor causes the UE to, in response to detecting an absence of a PSFCH for a plurality of PSFCH opportunities within the reference duration, adjust a contention window size to a CW min,p The UE of claim 8, configured to cause a

11. 3. The UE of claim 2, wherein the reference duration corresponds to an occupancy of a channel starting from a start of occupancy of the channel during at least one PSFCH opportunity of a number of PSFCH opportunities and until a HARQ-ACK feedback is expected from one or more UEs belonging to the same L2 destination ID.

12. The UE of claim 1 , wherein the processor is configured to cause the UE to maintain the contention window size adjustment constant.

13. The UE of claim 1 , wherein the processor is configured to cause the UE to set the reference duration according to a PSSCH transmission for which a first HARQ feedback within the reference duration is enabled.

14. A method performed by a user equipment ("UE"), comprising: transmitting a physical shared control channel ("PSCCH") and a physical shared sidelink channel ("PSSCH") for groupcast data transmission; receiving a Physical Shared Feedback Channel ("PSFCH") including groupcast Hybrid Automatic Repeat Request ("HARQ") feedback after a number of slots of groupcast data transmission; determining a contention window size adjustment for groupcast data transmission based on the groupcast HARQ feedback associated with the PSSCH within a reference duration; The method includes:

15. A user equipment ("UE"), comprising: A processor; a memory coupled to the processor; and wherein the processor causes the UE to: receiving a physical shared control channel ("PSCCH") and a physical shared sidelink channel ("PSSCH") for groupcast data transmission; transmitting a Physical Shared Feedback Channel ("PSFCH") including groupcast Hybrid Automatic Repeat Request ("HARQ") feedback after a predetermined number of slots of a groupcast transmission, wherein a contention window size adjustment for groupcast data transmissions is based on the groupcast HARQ feedback associated with the PSFCH within a reference duration; UE configured to:

16. A method performed by a user equipment ("UE"), comprising: receiving a physical shared control channel ("PSCCH") and a physical shared sidelink channel ("PSSCH") for groupcast data transmission; transmitting a Physical Shared Feedback Channel ("PSFCH") including groupcast Hybrid Automatic Repeat Request ("HARQ") feedback after a predetermined number of slots of groupcast transmission, wherein a contention window size adjustment for groupcast data transmission is based on the groupcast HARQ feedback associated with the PSFCH within a reference duration; The method includes:

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