User equipment and channel access method for sidelink communication

Abstract

A channel access method for a user equipment (UE) for sidelink (SL) communication includes accessing, by the UE, a channel for SL transmission based on a reference duration having a duration from a start of channel occupancy to an end of a first slot of a first type of physical sidelink shared channel (PSSCH) transmission, the reference duration having a duration from a start of channel occupancy to an end of a second slot of the first type of physical sidelink shared channel (PSSCH) transmission. Or until the end of the PSSCH transmission burst of the first type, or until the end of the PSSCH transmission burst of the second type.

Description

Technical Field

[0001] The present disclosure relates to the field of communication systems, and more specifically, to a user equipment (UE) and a channel access method for sidelink (SL) communication, which can provide good communication performance and / or high reliability. Background Art

[0002] In the evolution of direct radio wireless transmission and reception between two devices, which is commonly referred to as device-to-device (D2D) communication, D2D communication was first developed by the 3rd generation partnership project (3GPP) and introduced in Release 12 (formally defined as sidelink communication) and improved in Release 13 for public safety emergency purposes, such as mission-critical communications, to mainly support low data rates and voice-type connections. In 3GPP Releases 14, 15, and 16, sidelink technology was developed to additionally support vehicle-to-everything (V2X) communications as part of the global development of intelligent transportation systems (ITS) to improve road safety and advanced / autonomous driving use cases. To further expand the support of sidelink technology to a wider range of applications and devices with limited power / battery, the technology was further enhanced in Release 17 in terms of power saving and transceiver link reliability. In Release 18, 3GPP further evolved the wireless technology and extended its services to unlicensed spectrum. This is to achieve greater available bandwidth, faster data rates, and make it easier for the market to adopt D2D communications using sidelinks without requiring any mobile cellular operator to be involved in allocating and configuring part of their large amounts of valuable radio spectrum for data services that do not go through their mobile networks.

[0003] There is no base station control or assistance when a sidelink SL UE accesses one or more unlicensed channels. Even in resource allocation (RA) mode 1 under gNB scheduling, the UE may attempt to access the channel at different times and using different listen-before-talk (LBT) channel access procedures with different channel idle period requirements. In this operation scenario, there is no way to coordinate in advance between multiple UEs transmitting in the same time slot to avoid blocking / denying access to the unlicensed channels.

[0004] Therefore, there is a need for a user equipment (UE) and a channel access method for SL communication, which can solve the problems in the prior art and other problems. Summary of the invention

[0005] In a first aspect of the present disclosure, a channel access method for a user equipment (UE) to perform sidelink (SL) communication includes: the UE accesses a channel for SL transmission based on a reference duration, wherein the reference duration has a duration from the start of channel occupancy until the end of a first time slot of a first type of physical sidelink shared channel (PSSCH) transmission, or until the end of a first type of PSSCH transmission burst, or until the end of a second type of PSSCH transmission burst.

[0006] In a second aspect of the present disclosure, a user equipment (UE) includes an accessor configured to access a channel for SL transmission based on a reference duration, wherein the reference duration has a duration from the start of channel occupancy until the end of a first time slot of a first type of physical sidelink shared channel (PSSCH) transmission, or until the end of a first type of PSSCH transmission burst, or until the end of a second type of PSSCH transmission burst.

[0007] In a third aspect of the present disclosure, a user equipment (UE) includes a memory, a transceiver, and a processor coupled to the memory and the transceiver. The UE is configured to execute the above method.

[0008] In a fourth aspect of the present disclosure, a non-transitory machine-readable storage medium has instructions stored thereon, which, when executed by a computer, cause the computer to perform the above method.

[0009] In a fifth aspect of the present disclosure, a chip includes a processor, wherein the processor is configured to call and run a computer program stored in the memory so that a device equipped with the chip executes the above method.

[0010] In a sixth aspect of the present disclosure, a computer-readable storage medium is provided, in which a computer program is stored, so that a computer executes the above method.

[0011] In a seventh aspect of the present disclosure, a computer program product includes a computer program, and the computer program enables a computer to execute the above method.

[0012] In an eighth aspect of the present disclosure, a computer program causes a computer to execute the above method. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] In order to more clearly illustrate the embodiments or related technologies of the present disclosure, the following briefly introduces the drawings to be described in the embodiments. Obviously, the drawings are only some embodiments of the present disclosure, and ordinary technicians in this field can obtain other drawings based on these drawings without paying any price.

[0014] Figure 1 is a block diagram of a user equipment (UE) communicating in a communication network system according to an embodiment of the present disclosure.

[0015] Figure 2 is a schematic diagram showing a user plane protocol stack according to an embodiment of the present disclosure.

[0016] Figure 3 is a schematic diagram showing a control plane protocol stack according to an embodiment of the present disclosure.

[0017] Figure 4 is a flowchart illustrating a channel access method for sidelink (SL) communication between user equipments (UEs) according to an embodiment of the present disclosure.

[0018] Figure 5 It is a schematic diagram showing a channel access method for SL communication proposed according to an embodiment of the present disclosure.

[0019] Figure 6 is a block diagram of a UE for wireless communication according to an embodiment of the present disclosure.

[0020] Figure 7 is a block diagram of an example of a computing device according to an embodiment of the present disclosure.

[0021] Figure 8 is a block diagram of a wireless communication system according to an embodiment of the present disclosure. DETAILED DESCRIPTION

[0022] The technical content, structural features, objectives and effects of the embodiments of the present disclosure are described in detail below in conjunction with the accompanying drawings. Specifically, the terms in the embodiments of the present disclosure are only for the purpose of describing specific embodiments, and are not intended to limit the present disclosure.

[0023] Shared / Unlicensed Spectrum

[0024] Wi-Fi and Bluetooth wireless technologies typically use shared (also called unlicensed or license-free) radio spectrum in the 2.4 GHz and 5 GHz bands for short-range communications (from a few meters to tens of meters). It is often claimed that the unlicensed bands carry more traffic than any other radio bands because anyone can use the spectrum freely / for free as long as the communication equipment complies with certain local technical regulations. Other radio access technologies (RATs) besides Wi-Fi and Bluetooth, such as licensed-assisted access (LAA) based on 4G-LTE according to 3GPP and new radio unlicensed (NR-U) based on 5G-NR mobile systems, also operate in the same unlicensed bands. In order to enable devices of different RATs (Wi-Fi, Bluetooth, LAA, NR-U, and possibly others) to operate simultaneously and coexist fairly in the same geographic area without causing significant interference and disruption to each other's transmissions, clear channel access (CCA) protocols such as listen-before-talk (LBT) used in LAA and NR-U and carrier sense multiple access / collision avoidance (CSMA / CA) used in Wi-Fi and Bluetooth are employed before any wireless transmission to ensure that another radio wave is not transmitted on the same channel when one is already transmitting.

[0025] For sidelink radio technologies, in order to operate and coexist with existing RATs already operating in unlicensed bands, LBT-based schemes can be adopted to ensure that there is no ongoing activity on the radio channel before attempting to access the channel for transmission. For example, when a sidelink user equipment (UE) successfully performs type 1 LBT, the UE has the right to access and occupy the unlicensed channel for the duration of the channel occupancy time (COT). However, during the obtained COT, if the COT initiating sidelink UE or the COT responding sidelink UE does not perform a wireless transmission within an idle period of more than 25μs, a device of another RAT may still access the channel. Therefore, access to the channel may be lost until another successful LBT is performed. A potential solution to the problem of losing access to the channel may be back-to-back (B2B) transmission.

[0026] B2B transmission / Multi-consecutive slots transmission (MCSt)

[0027] The main purpose of B2B transmission (also known as "burst transmission" or "multiple consecutive time slot transmission") is to enable a sidelink (SL) communication UE to continuously occupy an unlicensed channel for a longer period of time (i.e., more than one time slot) without the risk of losing access to the channel to radio transmission (Tx) devices of other radio access technologies (RATs). This is particularly important and useful for the following SL Tx-UEs operating in the unlicensed wireless spectrum: the SL Tx-UE has a larger size of data transmission block (TB) or medium access control (MAC) packet data unit (PDU), requires multiple retransmissions, sidelink hybrid automatic repeat request (SL-HARQ) feedback is disabled, and / or has short delay requirements (small packet delay budget (PDB)). When the unlicensed radio channel is busy / congested (e.g., many devices attempt to access the channel for transmission at the same time), gaining access to the channel may be difficult and take a long time due to the random backoff timer and priority class in the LBT process. Therefore, the UE eventually has a chance to gain access to the radio channel within the length of the channel occupation time (COT) which may last for several milliseconds (e.g., 4ms, 8ms, or 10ms).

[0028] Some embodiments of the present disclosure aim to retain channel access as long as possible (e.g., the entire or most of the COT length), thereby sending as much data as possible by continuously transmitting in an unlicensed channel so that wireless devices of other RATs have no chance to access the channel.

[0029] Unauthorized channel access and occupation

[0030] As previously described, the UE may perform a Type 1 LBT procedure before any SL transmission to first acquire access to the unlicensed channel and initiate a COT. In addition, B2B transmissions may be used to avoid larger transmission intervals to preserve the COT and access to the channel. In addition to Type 1 LBT, the UE may use Type 2 LBT during a COT or shared COT, as required by unlicensed spectrum regulations with intervals of 25 μs or less. For example, in Type 2A LBT, a COT initiating UE is allowed to resume its transmission and / or a COT sharing UE is allowed to start its transmission within the COT if the unlicensed channel is heard to be idle for 25 μs or more. In Type 2B LBT, the allowed transmission interval is 16 μs, and the interval for Type 2C LBT (for which the UE is not required to perform channel sensing) is less than 16 μs.

[0031] In NR-U and LAA systems, due to the propagation delay between gNB / gNB to UE when sending scheduling control information, UE switching from receive mode (RX) to transmit mode (TX), and data information encoding and modulation for actual uplink (UL) transmission, there are inevitable / unavoidable transmission gaps before the UE occupies the unlicensed channel. Sometimes, these gaps may be greater than 25μs, and the cyclic prefix extension may be transmitted first in the UL to avoid the unlicensed channel being taken over by other devices operating in the same spectrum band due to excessive channel idle time. The duration of the cyclic prefix extension (CPE) transmission in the UL is determined by the base station (gNB / eNB) to avoid any access blocking / denial issues between different UEs, and the duration of the cyclic prefix extension (CPE) transmission in the UL is indicated to each scheduled UE, and the UE only needs to follow the indication and perform the UL transmission accordingly.

[0032] In SL communications, especially in resource allocation (RA) mode 2, the UE will determine and select all transmission resources on its own without any intervention, assistance, and coordination from the base station to avoid transmission conflicts. In addition, the SL system is able to perform frequency domain multiplexing (FDM) on transmissions from multiple UEs in the same time slot, thereby maximizing the efficiency of wireless resource utilization while also reducing communication latency. However, since there is no base station control and assistance when the SL UE accesses one or more unlicensed channels, even in RA mode 1 scheduled by the gNB, the UE may attempt to access the channel at different times and using different LBT channel access procedures with different channel idle period requirements. In this operating scenario, there is no way to coordinate in advance between UEs transmitting in the same time slot to avoid blocking / rejection of access to unlicensed channels.

[0033] Competition Window Adjustment

[0034] As part of the Type 1 LBT channel access procedure, the range of LBT listening time lengths required before the UE is able to obtain access to a shared / unlicensed channel is different depending on the channel access priority class (CAPC) level (p) of the data packet, physical channel and / or signal to be transmitted. In order to determine the exact LBT listening time length within this range for a given CAPC level (p) and a specific transmission, the maximum allowed value of the channel listening time is further adjusted based on the "channel contention status", which is measured based on the hybrid automatic repeat request-acknowledgement (HARQ-ACK) feedback from the data receiving node. In NR-U, the contention window adjustment process is mainly based on the number of 'ACK' feedbacks received related to the reference duration and unicast transmission.

[0035] However, in NR sidelink communications, the cast type and HARQ-ACK feedback mechanism of the physical sidelink shared channel (PSSCH) transmission carrying information packets may be very different from NR-U (for example, code block group transmission is not supported and HARQ-ACK feedback is not always enabled / available in SL). Therefore, a new definition and adjustment process for the SL-U contention window is necessary.

[0036] Figure 1It is shown that, in some embodiments, one or more user equipments (UE) 10 (e.g., a first UE) and one or more user equipments (UE) 20 (e.g., a second UE) communicating in a communication network system 30 according to an embodiment of the present disclosure are provided. The communication network system 30 includes one or more UEs 10 and one or more UEs 20. The UE 10 may include a memory 12, a transceiver 13, and a processor 11 coupled to the memory 12 and the transceiver 13. The UE 20 may include a memory 22, a transceiver 23, and a processor 21 coupled to the memory 22 and the transceiver 23. The processor 11 or 21 may be configured to implement the proposed functions, processes, and / or methods described in this specification. A wireless interface protocol layer may be implemented in the processor 11 or 21. The memory 12 or 22 is operably coupled to the processor 11 or 21 and stores various information to operate the processor 11 or 21. The transceiver 13 or 23 is operably coupled to the processor 11 or 21 and transmits and / or receives radio signals.

[0037] The processor 11 or 21 may include an application-specific integrated circuit (ASIC), other chipsets, logic circuits and / or data processing devices. The memory 12 or 22 may include a read-only memory (ROM), a random access memory (RAM), a flash memory, a memory card, a storage medium and / or other storage devices. The transceiver 13 or 23 may include a baseband circuit for processing radio frequency signals. When the various embodiments are implemented in software, the techniques described herein may be implemented using modules (e.g., programs, functions, etc.) that perform the functions described herein. These modules may be stored in the memory 12 or 22 and executed by the processor 11 or 21. The memory 12 or 22 may be implemented within the processor 11 or 21, or may be implemented outside the processor 11 or 21. When implemented outside the processor 11 or 21, the memory 12 or 22 may be communicatively coupled to the processor 11 or 21 in various ways known in the art.

[0038] According to the sidelink technology developed under the 3rd Generation Partnership Project (3GPP) long term evolution (LTE) and new radio (NR) versions 17, 18 and higher, the communication between multiple UEs involves vehicle-to-everything (V2X) communication, which V2X communication includes vehicle-to-vehicle (V2V), vehicle-to-pedestrian (V2P) and vehicle-to-infrastructure / network (V2I / N). Multiple UEs communicate directly with each other through a sidelink interface (e.g., a PC5 interface). Some embodiments of the present disclosure relate to sidelink communication technology in 3GPP NR versions 19 and higher, for example, providing cellular vehicle-to-everything (C-V2X) communication.

[0039] In some embodiments, UE 10 may be a sidelink packet transport block (TB) transmitting UE (Tx-UE). UE 20 may be a sidelink packet TB receiving UE (Rx-UE) or a peer UE. A sidelink packet TB Rx-UE may be configured to send ACK / NACK feedback to a packet TB Tx-UE. Peer UE 20 is another UE communicating with Tx-UE 10 in the same SL unicast or multicast session.

[0040] Figure 2 An exemplary user plane protocol stack according to an embodiment of the present disclosure is shown. Figure 2It is shown that, in some embodiments, in the user plane protocol stack, the service data adaptation protocol (SDAP), the packet data convergence protocol (PDCP), the radio link control (RLC) and the medium access control (MAC) sublayers and the physical (PHY) layer (also referred to as the first layer or layer 1 (L1) layer) can be terminated at the UE 10 and the base station 40 (e.g., gNB) on the network side. In an example, the PHY layer provides transmission services to higher layers (e.g., MAC, RRC, etc.). In one example, the services and functions of the MAC sublayer may include: mapping between logical channels and transport channels; multiplexing MAC service data units (SDUs) belonging to one or different logical channels into / demultiplexing MAC SDUs belonging to one or different logical channels from / to a transport block (TB), which is delivered to / from the PHY layer; scheduling information reporting; error correction through hybrid automatic repeat request (HARQ) (e.g., one HARQ entity per carrier in the case of carrier aggregation (CA); priority handling between multiple UEs through dynamic scheduling; priority handling between multiple logical channels of a UE through logical channel priorities; and / or padding. The MAC entity may support one or more parameter sets and / or transmission timings. In one example, mapping restrictions in logical channel priorities may control the parameter sets and / or transmission timings that may be used by logical channels. In one example, the RLC sublayer may support a transparent mode (TM) transmission mode, an unacknowledged mode (UM) transmission mode, and an acknowledged mode (AM) transmission mode. The RLC configuration may be for each logical channel, independent of the parameter set and / or the transmission time interval (TTI) duration. In one example, an automatic repeat request (ARQ) may operate on any parameter set and / or TTI duration configured for the logical channel. In one example, the services and functions of the PDCP layer of the user plane may include sequence numbering, header compression and decompression, user data transmission, reordering and duplicate detection, PDCP PDU routing (in the case of split bearer), retransmission, encryption, decryption and integrity protection of PDCP SDU, PDCP SDU discard, PDCP reconstruction and data recovery of RLC AM, and / or duplication of PDCP PDU.In one example, the services and functions of SDAP may include mapping between QoS flows and data radio bearers. In one example, the services and functions of SDAP may include mapping quality of service indicators (QFI) in downlink (DL) and uplink (UL) packets. In one example, the protocol entities of SDAP may be configured for separate PDU sessions.

[0041] Figure 3 An exemplary control plane protocol stack according to an embodiment of the present disclosure is shown. Figure 3 It is shown that in some embodiments, in the control plane protocol stack, the PDCP, RLC and MAC layers and the PHY layer can be terminated in the UE 10 and the base station 40 (e.g., gNB) on the network side, and perform the above services and functions. In one example, the radio resource control (RRC) is used to control the radio resources between the UE and the base station (e.g., gNB). In one example, the RRC can be terminated in the UE and the gNB on the network side. In one example, the services and functions of RRC may include: broadcasting of system information related to the access stratum (AS) and non-access stratum (NAS); paging initiated by the 5G core network (5GC) or the radio access network (RAN); establishment, maintenance and release of the RRC connection between the UE and the RAN; security functions (including key management, establishment, configuration, maintenance and release of signaling radio bearers (SRB) and data radio bearers (DRB)); mobility functions; QoS management functions; UE measurement reporting and reporting control; detection and recovery of radio link failures; and / or non-access stratum (NAS) message transmission from the UE to the NAS / from the NAS to the UE. In one example, the NAS control protocol may terminate at the AMF on the UE and network side, and may perform functions such as authentication, mobility management between the UE and the access and mobility management function (AMF) for 3GPP access and non-3GPP access, and session management between the UE and the SMF for 3GPP access and non-3GPP access.

[0042] When a specific application is executed in the UE and the specific application requires a data communication service, the application layer responsible for executing the specific application provides the NAS layer with application-related information, that is, application grouping / category / priority information / ID. In this case, the above application-related information can be pre-configured / defined in the UE. (Alternatively, the application-related information is received from the network to be provided from the AS (RRC) layer to the application layer, and when the application layer starts the data communication service, the application layer requests the AS (RRC) layer that receives the information to provide the information.)

[0043] In some embodiments, the processor 11 is configured to access a channel for SL transmission based on a reference duration, wherein the reference duration has a duration from the start of channel occupancy until the end of the first time slot of a first type of physical sidelink shared channel (PSSCH) transmission, or until the end of a first type of PSSCH transmission burst, or until the end of a second type of PSSCH transmission burst. This can solve the problems in the prior art and other technical problems, and / or improve the performance and reliability of SL communication.

[0044] Figure 4 A method 410 for channel access and occupancy in a shared spectrum between user equipment (UE) according to an embodiment of the present disclosure is shown. In some embodiments, the method 410 includes: operation 412, accessing a channel for SL transmission by the UE based on a reference duration, wherein the reference duration has a duration from the start of channel occupancy until the end of the first time slot of a first type of physical sidelink shared channel (PSSCH) transmission, or until the end of a first type of PSSCH transmission burst, or until the end of a second type of PSSCH transmission burst. This can solve problems in the prior art and other problems, and / or improve the performance and reliability of SL communications.

[0045] In some embodiments, the first type of PSSCH transmission includes a PSSCH transmission with hybrid automatic repeat request (HARQ) enabled. In some embodiments, an enable / disable indicator for HARQ feedback is located in the second-order sidelink control information (SCI) that indicates the enablement of HARQ for scheduling the first type of PSSCH transmission. In some embodiments, the first type of PSSCH transmission includes a unicast PSSCH transmission. In some embodiments, the first type of PSSCH transmission includes a multicast PSSCH transmission. In some embodiments, the multicast PSSCH transmission includes a multicast option 2 transmission with acknowledgement (ACK) feedback or negative acknowledgement (NACK) feedback, or a multicast option 1 transmission with NACK-only feedback.

[0046] In some embodiments, a bit field in a second-order SCI for scheduling a first type of PSSCH transmission is: a first value indicating a multicast option 2 transmission with ACK feedback or NACK feedback, a second value indicating a unicast transmission, or a third value indicating a multicast option 1 transmission with only NACK feedback. In some embodiments, the first value is 01, the second value is 10, and / or the third value is 11. In some embodiments, the first type of PSSCH transmission is transmitted in a resource pool, and the resource pool is configured with a physical sidelink feedback channel (PSFCH) resource. In some embodiments, channel occupancy is initiated by the UE using a type 1 channel access procedure.

[0047] In some embodiments, the channel occupancy is used to transmit PSSCH transmissions. In some embodiments, a first type of PSSCH transmission burst includes one or more first type of PSSCH transmissions. In some embodiments, one or more first type of PSSCH transmissions include one or more unicast PSSCH transmissions, one or more multicast PSSCH transmissions, or one or more broadcast PSSCH transmissions. In some embodiments, a second type of PSSCH transmission burst includes one or more second type of PSSCH transmissions. In some embodiments, one or more second type of PSSCH transmissions include one or more broadcast PSSCH transmissions.

[0048] In some embodiments, a bit field in a second-order SCI for scheduling a second type of PSSCH transmission is a fourth value indicating a broadcast transmission. In some embodiments, the fourth value is 00. In some embodiments, one or more second-type PSSCH transmissions include one or more HARQ-disabled PSSCH transmissions. In some embodiments, an enable / disable indicator for HARQ feedback is located in a second-order SCI indicating HARQ disabled that schedules one or more second-type PSSCH transmissions. In some embodiments, one or more second-type PSSCH transmissions are transmitted in a resource pool, and the resource pool is not configured with PSFCH resources.

[0049] In some embodiments, the term " / " may be interpreted as meaning "and / or". The term "configured" may refer to "pre-configured" and "configured by the network". The term "predefined" or "predefined rules" in the present disclosure may be implemented by pre-storing corresponding codes, tables or other methods for indicating relevant information in a device (e.g., including UE and network equipment). The present disclosure does not limit the specific implementation. For example, "predefined" may refer to content defined in a protocol. It should also be understood that the "protocol" in the present disclosure may refer to a standard protocol in the field of communications, which may include, for example, LTE protocols, NR protocols, and related protocols used in future communication systems, and the present disclosure does not limit this.

[0050] Example:

[0051] Figure 5 A channel access method for SL communication proposed according to an embodiment of the present disclosure is shown. Figure 5 It is shown that, in some embodiments, in an inventive method for accessing a non-licensed / shared channel in a sidelink (SL) communication, the method proposes a reference duration defined as customized for the sidelink, taking into account all possible hybrid automatic repeat request-acknowledgement (HARQ-ACK) feedback scenarios in SL communications.

[0052] As mentioned earlier, the code block group (CBG) based transmission and HARQ-ACK feedback scheme used in the fifth generation (5G) new radio (NR) is not adopted in NR SL communications. In addition, for NR systems operating in unlicensed carriers (NR-U), most of the traffic (e.g., more than 95%) in downlink (DL) transmissions and uplink (UL) transmissions are unicast in nature. Sometimes, broadcast transmissions such as synchronization signal blocks (SSBs) and system information blocks (SIBs) are provided in DL, and random-access channels (RACHs) are provided in UL. As a special case, SSBs can be transmitted using only type 2A channel access procedures. Therefore, for unicast transmissions, type 1 channel access procedures are performed in almost all cases, and these unicast transmissions always require HARQ-ACK feedback of "ACK" or "NACK" from the receiving UE / gNB.

[0053] Figure 5It is shown that in sidelink communications, various transmission propagation types and HARQ-ACK feedback schemes are supported, for example, broadcast transmissions that do not require HARQ-ACK feedback; multicast transmissions with full HARQ-ACK feedback ("ACK and NACK") and "only NACK" feedback; and unicast with full HARQ-ACK feedback ("ACK and NACK"). In addition, the SL transmission resource pool can be configured to have no physical sidelink feedback channel (PSFCH) resources, in which case all transmissions in the resource pool do not require / receive any HARQ-ACK feedback. To make SL operation more complex, sidelink HARQ-ACK feedback can be enabled / disabled in the second-order sidelink control information (SCI) of the scheduling physical sidelink shared channel (PSSCH) for both multicast and unicast transmissions. It can be seen that there is more than one HARQ-ACK scenario supported in SL communications. Therefore, the existing contention window adjustment for type 1 channel access procedures is not appropriate and cannot be applied to SL communications accessing unlicensed / shared channels.

[0054] Proposed reference duration definition

[0055] In order to consider all possible SL operation scenarios, it is proposed to define the reference duration (or SL-specific reference duration) as:

[0056] In some embodiments, the reference duration of the SL has a duration from the beginning of the channel occupancy time (COT) until the end of the first time slot of the first type of PSSCH transmission, or until the end of the first type of PSSCH transmission burst, or until the end of the second type of PSSCH transmission burst. Optionally, the first type of PSSCH can be a unicast PSSCH or a groupcast PSSCH. Optionally, the first type of PSSCH can be a unicast PSSCH.

[0057] In some embodiments, the first type of PSSCH may be a multicast PSSCH based on one of the following. Exemplarily, the multicast PSSCH may be multicast option 2 with ACK feedback or NACK feedback, or multicast option 1 with only NACK feedback. Exemplarily, the multicast PSSCH may be multicast option 2 with ACK feedback or NACK feedback. Exemplarily, the multicast PSSCH may be multicast option 1 with only NACK feedback. Exemplarily, the bit field of the propagation type in the second-order SCI for scheduling the first type of PSSCH is 01 (multicast option 2 with ACK feedback or NACK feedback) or 10 (unicast) or 11 (multicast option 1 with only NACK feedback). Optionally, the first type of PSSCH may be a HARQ-enabled PSSCH. Exemplarily, the enable / disable indicator of HARQ feedback is located in the second-order SCI indicating the enablement of HARQ for scheduling the first type of PSSCH. Optionally, the resource pool for transmitting the first type of PSSCH is (pre) configured with PSFCH resources. Optionally, COT is initiated by the UE through a type 1 channel access procedure. Optionally, COT is used to transmit PSSCH.

[0058] Optionally, the first type of PSSCH transmission burst includes one or more first type of PSSCHs. Exemplarily, the first type of PSSCH transmission burst includes one or more unicast or multicast PSSCH transmissions, and one or more broadcast PSSCH transmissions.

[0059] Optionally, the second type of PSSCH transmission burst includes one or more second type PSSCHs. Exemplarily, the second type of PSSCH transmission burst includes only broadcast PSSCH. Optionally, the second type of PSSCH is a broadcast PSSCH. Exemplarily, the bit field of the propagation type in the second-order SCI for scheduling the second type of PSSCH is 00 (broadcast). Optionally, the second type of PSSCH is a HARQ disabled PSSCH. Exemplarily, the enable / disable indicator of HARQ feedback is located in the second-order SCI for scheduling the second type of PSSCH indicating the disabling of HARQ. Optionally, the resource pool for transmitting the second type of PSSCH is not (pre) configured with PSFCH resources.

[0060] It should be noted that the term "predefined" or "predefined rules" in the present disclosure can be implemented by pre-storing corresponding codes, tables or other methods for indicating relevant information in devices (for example, including UEs and network devices). The present disclosure does not limit the specific implementation. For example, "predefined" may refer to the content defined in the protocol. It should also be understood that the "protocol" in the present disclosure may refer to a standard protocol in the field of communications, which may include, for example: (Long Term Evolution) LTE protocol, (New Radio) NR protocol and related protocols used in future communication systems, and the present disclosure does not limit this.

[0061] Figure 6 A UE 600 for wireless communication according to an embodiment of the present disclosure is shown. The UE 600 includes an accessor 601 configured to access a channel for SL transmission based on a reference duration, wherein the reference duration has a duration from the start of channel occupancy until the end of the first time slot of a first type of physical sidelink shared channel (PSSCH) transmission, or until the end of a first type of PSSCH transmission burst, or until the end of a second type of PSSCH transmission burst. This can solve the problems in the prior art and other technical problems, and / or improve the performance and reliability of SL communication.

[0062] In some embodiments, the first type of PSSCH transmission includes a PSSCH transmission with hybrid automatic repeat request (HARQ) enabled. In some embodiments, an enable / disable indicator for HARQ feedback is located in the second-order sidelink control information (SCI) indicating the enablement of HARQ that schedules the first type of PSSCH transmission. In some embodiments, the first type of PSSCH transmission includes a unicast PSSCH transmission. In some embodiments, the first type of PSSCH transmission includes a multicast PSSCH transmission. In some embodiments, the multicast PSSCH transmission includes a multicast option 2 transmission with acknowledgement (ACK) feedback or negative acknowledgement (NACK) feedback, or a multicast option 1 transmission with NACK-only feedback.

[0063] In some embodiments, the bit field in the second-order SCI for scheduling the first type of PSSCH transmission is: a first value indicating a multicast option 2 transmission with ACK feedback or NACK feedback, a second value indicating a unicast transmission, or a third value indicating a multicast option 1 transmission with only NACK feedback. In some embodiments, the first value is 01, the second value is 10, and / or the third value is 11. In some embodiments, the first type of PSSCH transmission is transmitted in a resource pool, and the resource pool is configured with a physical sidelink feedback channel (PSFCH) resource. In some embodiments, the channel occupancy is initiated by the UE using a type 1 channel access procedure.

[0064] In some embodiments, the channel occupancy is used to transmit PSSCH transmissions. In some embodiments, a first type of PSSCH transmission burst includes one or more first type of PSSCH transmissions. In some embodiments, one or more first type of PSSCH transmissions include one or more unicast PSSCH transmissions, one or more multicast PSSCH transmissions, or one or more broadcast PSSCH transmissions. In some embodiments, a second type of PSSCH transmission burst includes one or more second type of PSSCH transmissions. In some embodiments, one or more second type of PSSCH transmissions include one or more broadcast PSSCH transmissions.

[0065] In some embodiments, a bit field in a second-order SCI for scheduling a second type of PSSCH transmission is a fourth value indicating a broadcast transmission. In some embodiments, the fourth value is 00. In some embodiments, one or more second-type PSSCH transmissions include one or more HARQ-disabled PSSCH transmissions. In some embodiments, an enable / disable indicator for HARQ feedback is located in a second-order SCI indicating HARQ disabled that schedules one or more second-type PSSCH transmissions. In some embodiments, one or more second-type PSSCH transmissions are transmitted in a resource pool, and the resource pool is not configured with PSFCH resources.

[0066] In some embodiments, the term " / " may be interpreted as meaning "and / or". The term "configured" may refer to "pre-configured" and "configured by the network". The terms "predefined" or "predefined rules" in the present disclosure may be implemented by pre-storing corresponding codes, tables or other methods for indicating relevant information in a device (e.g., including UE and network equipment). The present disclosure does not limit the specific implementation. For example, "predefined" may refer to content defined in a protocol. It should also be understood that the "protocol" in the present disclosure may refer to a standard protocol in the field of communications, which may include, for example, LTE protocols, NR protocols, and related protocols used in future communication systems, and the present disclosure does not limit this.

[0067] In summary, in some embodiments, in order to consider all possible SL operation scenarios, it is proposed to define a reference duration (or SL-specific reference duration) as: In some embodiments, the SL reference duration has a duration from the start of channel occupancy until the end of the first time slot of the first type of PSSCH transmission, or until the end of the first type of PSSCH transmission burst, or until the end of the second type of PSSCH transmission burst. Optionally, the first type of PSSCH can be a unicast PSSCH or a groupcast PSSCH. Optionally, the first type of PSSCH can be a unicast PSSCH.

[0068] The commercial benefits of some embodiments are as follows. 1. Solve the problems in the prior art and other problems. 2. Improve the sidelink (SL) communication performance. 3. Maintain access to the unlicensed channel for the intended SL transmission. 4. Avoid SL transmission conflicts when the intended SL transmission occupies at least the entire bandwidth of the channel based on priority access. 5. Some embodiments of the present disclosure can be used in the following aspects: 5G-NR chipset suppliers, V2X communication system development suppliers, automobile manufacturers (including cars, trains, trucks, buses, bicycles, motorcycles and helmets, etc.), drones (unmanned aerial vehicles), smartphone manufacturers, smart watches, wireless earbuds, wireless headphones, communication devices, remote control vehicles and robots for public safety, augmented reality (AR) / virtual reality (VR) device manufacturers (for example, for games, conferences / seminars, educational purposes), smart home appliances (including TVs, stereos, speakers, lights, doorbells, locks, cameras and conference headsets, etc.), smart factory and warehouse equipment (including Industrial Internet of Things (IIoT) devices, robots, robotic arms) and equipment between production machines only. In some embodiments, the commercial benefits and commercial importance of the disclosed invention include: reducing the power consumption of wireless communication means longer operation time of the device, and / or better user experience and product satisfaction brought by longer operation time of the device between battery charges and the next charge. Some embodiments of the present disclosure are combinations of "technology / processes" that can be adopted in 3GPP specifications to produce terminal products. Some embodiments of the present disclosure are related to 3GPP NR versions 17, 18, 19 and higher versions of mobile cellular communication technology for providing direct device-to-device (D2D) wireless communication services.

[0069] Figure 7 is a block diagram of an example of a computing device according to an embodiment of the present disclosure. Any suitable computing device may be used to perform the operations described herein. For example, Figure 7 It is shown that any suitably configured hardware and / or software implementation may be used Figures 1 to 6An example of a computing device 1100 of some embodiments of the present invention. In some embodiments, the computing device 1100 may include a processor 1112 that is communicatively coupled to a memory 1114 and executes computer executable program code and / or accesses information stored in the memory 1114. The processor 1112 may include a microprocessor, an application-specific integrated circuit ("ASIC"), a state machine, or other processing device. The processor 1112 may include any processing device of a plurality of processing devices (including one). The above-mentioned processor may include a computer-readable medium storing instructions or may communicate with the computer-readable medium, and the instructions, when executed by the processor 1112, cause the processor to perform the operations described herein.

[0070] Memory 1114 may include any suitable non-transitory computer-readable medium. Computer-readable media may include any electronic storage device, optical storage device, magnetic storage device, or other storage device capable of providing computer-readable instructions or other program codes to the processor. Non-limiting examples of computer-readable media include disks, memory chips, read-only memory (ROM), random access memory (RAM), application-specific integrated circuits (ASICs), configured processors, optical storage, tapes or other magnetic storage, or any other medium from which a computer processor can read instructions. These instructions may include processor-specific instructions generated by a compiler and / or interpreter based on a code written in any suitable computer programming language, including, for example, C, C++, C#, visual basic, java, python, perl, javascript, and actionscript.

[0071] The computing device 1100 may also include a bus 1116. The bus 1116 may be communicatively coupled to one or more components of the computing device 1100. The computing device 1100 may also include a plurality of external or internal devices, such as input or output devices. For example, the computing device 1100 is shown with an input / output ("I / O") interface 1118, which may receive input from one or more input devices 1120 or provide output to one or more output devices 1122. One or more input devices 1120 and one or more output devices 1122 may be communicatively coupled to the I / O interface 1118. The communicatively coupled may be achieved by any suitable means (e.g., connection via a printed circuit board, connection via a cable, communication via wireless transmission, etc.). Non-limiting examples of the input device 1120 include a touch screen (e.g., one or more cameras for imaging a touch area or a pressure sensor for detecting pressure changes caused by a touch), a mouse, a keyboard, or any other device that may be used to generate input events in response to physical actions of a user of the computing device. Non-limiting examples of output device 1122 include a liquid crystal display (LCD) screen, an external monitor, speakers, or any other device that can be used to display or otherwise present output generated by the computing device.

[0072] The computing device 1100 can execute program code that configures the processor 1112 to perform the above-mentioned reference Figures 1 to 6 The program code may be stored in the memory 1114 or any suitable computer-readable medium and may be executed by the processor 1112 or any other suitable processor.

[0073] The computing device 1100 may also include at least one network interface device 1124. The network interface device 1124 may include any device or group of devices suitable for establishing a wired or wireless data connection to one or more data networks 1128. Non-limiting examples of the network interface device 1124 include an Ethernet network adapter and / or a modem, etc. The computing device 1100 may transmit messages as electrical or optical signals through the network interface device 1124.

[0074] Figure 8 7 is a block diagram of an example system 700 for wireless communications according to an embodiment of the present disclosure. The embodiments described herein may be implemented into a system using any suitably configured hardware and / or software. Figure 8A system 700 is shown, which includes at least a radio frequency (RF) circuit 710, a baseband circuit 720, an application circuit 730, a memory / storage device 740, a display 750, a camera 760, a sensor 770, and an input / output (I / O) interface 780 coupled to each other as shown.

[0075] The application circuit 730 may include circuits such as, but not limited to, one or more single-core or multi-core processors. The processor may include any combination of general-purpose processors and special-purpose processors, such as graphics processors and application processors. The processor may be coupled to a memory / storage device and configured to execute instructions stored in the memory / storage device to enable various applications and / or operating systems to run on the system.

[0076] The baseband circuit 720 may include circuits such as, but not limited to, one or more single-core or multi-core processors. The processor may include a baseband processor. The baseband circuit may handle various radio control functions to enable communication with one or more radio networks through the RF circuit. The radio control functions may include, but are not limited to, signal modulation, encoding, decoding, radio frequency shift, etc. In some embodiments, the baseband circuit may provide communications compatible with one or more radio technologies. For example, in some embodiments, the baseband circuit may support communications with the Evolved Universal Terrestrial Radio Access Network (EUTRAN) and / or other wireless metropolitan area networks (WMAN), wireless local area networks (WLAN), and wireless personal area networks (WPAN). An embodiment in which the baseband circuit is configured to support radio communications of more than one wireless protocol may be referred to as a multimode baseband circuit.

[0077] In various embodiments, baseband circuitry 720 may include circuitry for operating on signals that are not strictly considered to be at baseband frequencies. For example, in some embodiments, baseband circuitry may include circuitry for operating on signals having an intermediate frequency (which is between the baseband frequency and the radio frequency).

[0078] RF circuitry 710 may enable communication with a wireless network using modulated electromagnetic radiation through a non-solid medium. In various embodiments, the RF circuitry may include switches, filters, amplifiers, etc. to facilitate communication with a wireless network.

[0079] In various embodiments, RF circuitry 710 may include circuitry for operating on signals that are not strictly considered radio frequencies. For example, in some embodiments, RF circuitry may include circuitry for operating on signals having an intermediate frequency (which is between baseband frequency and radio frequency).

[0080] In various embodiments, the transmitter circuitry, control circuitry, or receiver circuitry discussed above with respect to user equipment, eNBs, or gNBs may be embodied in whole or in part in one or more of the RF circuitry, baseband circuitry, and / or application circuitry. As used herein, "circuitry" may refer to, be part of, or include: an application specific integrated circuit (ASIC), an electronic circuit, a (shared, dedicated, or group) processor, and / or (shared, dedicated, or group) memory that executes one or more software or firmware programs; combinatorial logic circuitry; and / or other suitable hardware components that provide the described functionality. In some embodiments, electronic device circuitry may be implemented in one or more software or firmware modules, or circuit-related functionality may be implemented by one or more software or firmware modules.

[0081] In some embodiments, some or all components of the baseband circuit, application circuit and / or memory / storage device may be implemented together on a system on a chip (SOC).

[0082] The memory / storage device 740 can be used, for example, to load and store data and / or instructions for the system. The memory / storage device of one embodiment can include any combination of suitable volatile memory (e.g., dynamic random access memory (DRAM)) and / or non-volatile memory (e.g., flash memory).

[0083] In various embodiments, the I / O interface 780 may include one or more user interfaces designed to implement interaction between a user and the system, and / or a peripheral component interface designed to implement interaction between a peripheral component and the system. The user interface may include, but is not limited to, a physical keyboard or keypad, a touch pad, a speaker, a microphone, etc. The peripheral component interface may include, but is not limited to, a non-volatile memory port, a universal serial bus (USB) port, an audio jack, and a power interface.

[0084] In various embodiments, the sensor 770 may include one or more sensing devices for determining environmental conditions and / or location information related to the system. In some embodiments, the sensor may include, but is not limited to, a gyroscope sensor, an accelerometer, a proximity sensor, an ambient light sensor, and a positioning unit. The positioning unit may also be part of the baseband circuit and / or RF circuit, or interact with the baseband circuit and / or RF circuit to communicate with components of a positioning network (e.g., a global positioning system (GPS) satellite).

[0085] In various embodiments, the display 750 may include a display, such as a liquid crystal display and a touch screen display. In various embodiments, the system 700 may be a mobile computing device, such as but not limited to a notebook computing device, a tablet computing device, a netbook, an ultrabook, a smart phone, AR / VR glasses, etc. In various embodiments, the system may have more or fewer components and / or different architectures. Where appropriate, the methods described herein may be implemented as a computer program. The computer program may be stored on a storage medium (e.g., a non-transitory storage medium).

[0086] It can be understood by those skilled in the art that each of the units, algorithms and steps described and disclosed in the embodiments of the present disclosure is implemented using electronic hardware, or a combination of computer software and electronic hardware. Whether these functions are run on hardware or software depends on the application conditions and the design requirements of the technical solution.

[0087] A person skilled in the art may implement the function in different ways for each specific application, and such implementation should not exceed the scope of the present disclosure. A person skilled in the art may understand that since the workflows of the above-mentioned systems, devices and units are substantially the same, he / she may refer to the workflows of the systems, devices and units in the above-mentioned embodiments. For ease of description and simplicity, these workflows will not be described in detail.

[0088] It is to be understood that the systems, devices and methods disclosed in the embodiments of the present disclosure may also be implemented in other ways. The above embodiments are exemplary only. The division of the units is based only on logical functions, and there are other divisions in the implementation. It is possible for multiple units or components to be combined or integrated into another system. It is also possible to omit or skip some features. On the other hand, the coupling, direct coupling or communicative coupling shown or discussed is operated indirectly or communicatively through some ports, devices or units in electrical, mechanical or other forms.

[0089] For the purpose of explanation, the units of the separated components are physically separated or not separated. The display unit is a physical unit or not a physical unit, that is, the display unit is located in one place or distributed on multiple network units. Some or all of the multiple units are used according to the purpose of the embodiment. In addition, each functional unit in each embodiment can be integrated into a processing unit, or each functional unit is physically independent, or two or more units are integrated into a processing unit.

[0090] If the software functional unit is implemented and used and sold as a product, the software functional unit can be stored in a readable storage medium in a computer. Based on this understanding, the technical solution proposed in the present disclosure can be implemented in whole or in part in the form of a software product. Alternatively, a part of the technical solution that is beneficial to traditional technology can be implemented in the form of a software product. The software product in the computer is stored in a storage medium, and the software product includes a plurality of commands for a computing device (e.g., a personal computer, a server, or a network device) to run all or part of the steps disclosed in the embodiment of the present disclosure. The above-mentioned storage medium includes: a USB disk, a mobile hard disk, a read-only memory (ROM), a random access memory (RAM), a floppy disk or other types of media capable of storing program code.

[0091] While the present disclosure has been described in connection with what are considered to be the most practical and preferred embodiments, it is to be understood that the disclosure is not limited to the disclosed embodiments but is intended to cover various arrangements made without departing from the scope of the broadest interpretation of the appended claims.

Claims

1. A channel access method for a user equipment UE to perform sidelink SL communication, comprising: The UE accesses a channel for SL transmission based on a reference duration, wherein the reference duration has a duration from the start of channel occupancy until the end of the first time slot of a first type of physical sidelink shared channel PSSCH transmission, or until the end of a first type of PSSCH transmission burst, or until the end of a second type of PSSCH transmission burst.

2. The method according to claim 1, wherein: The first type of PSSCH transmission includes a hybrid automatic repeat request (HARQ) enabled PSSCH transmission.

3. The method according to claim 2, wherein: The enable / disable indicator of the HARQ feedback is located in the second order sidelink control information SCI indicating enabling of HARQ that schedules the first type of PSSCH transmission.

4. The method according to any one of claims 1 to 3, wherein: The first type of PSSCH transmission comprises a unicast PSSCH transmission.

5. The method according to any one of claims 1 to 3, wherein: The first type of PSSCH transmission comprises a multicast PSSCH transmission.

6. The method according to claim 5, wherein: The multicast PSSCH transmission includes a multicast option 2 transmission with an ACK feedback or a NACK feedback, or a multicast option 1 transmission with only a NACK feedback.

7. The method according to claim 5, wherein: The bit field in the second-order SCI for scheduling the first type of PSSCH transmission is: a first value indicating multicast option 2 transmission with ACK feedback or NACK feedback, a second value indicating unicast transmission, or a third value indicating multicast option 1 transmission with only NACK feedback.

8. The method according to claim 7, wherein: The first value is 01, the second value is 10, and / or the third value is 11.

9. The method according to any one of claims 1 to 8, wherein: The first type of PSSCH transmission is transmitted in a resource pool, and the resource pool is configured with physical sidelink feedback channel PSFCH resources.

10. The method according to any one of claims 1 to 9, wherein: The channel occupation is initiated by the UE using a type 1 channel access procedure.

11. The method according to any one of claims 1 to 10, wherein: The channel occupancy is used for transmitting PSSCH transmission.

12. The method according to claim 1, wherein: The first type of PSSCH transmission burst includes one or more first type of PSSCH transmissions.

13. The method according to claim 12, wherein: The one or more first type PSSCH transmissions include one or more unicast PSSCH transmissions, one or more groupcast PSSCH transmissions, or one or more broadcast PSSCH transmissions.

14. The method according to claim 1, wherein: The second type of PSSCH transmission burst includes one or more second type of PSSCH transmissions.

15. The method according to claim 14, wherein: The one or more PSSCH transmissions of the second type include one or more broadcast PSSCH transmissions.

16. The method according to claim 14 or 15, wherein: The bit field in the second order SCI that schedules the second type of PSSCH transmission is a fourth value indicating a broadcast transmission.

17. The method according to claim 16, wherein: The fourth value is 00.

18. The method according to any one of claims 14 to 17, wherein: The one or more second type PSSCH transmissions include one or more HARQ disabled PSSCH transmissions.

19. The method according to claim 18, wherein: The enable / disable indicator of the HARQ feedback is located in a second order SCI indicating disabling of HARQ that schedules the one or more second type PSSCH transmissions.

20. The method according to any one of claims 14 to 19, wherein: The one or more second type PSSCH transmissions are transmitted in a resource pool, and the resource pool is not configured with PSFCH resources.

21. A user equipment UE, comprising: The access device is configured to: Accessing a channel for sidelink SL transmission based on a reference duration, wherein the reference duration has a duration from the start of channel occupancy until the end of the first time slot of a first type of physical sidelink shared channel PSSCH transmission, or until the end of a first type of PSSCH transmission burst, or until the end of a second type of PSSCH transmission burst.

22. A user equipment UE, comprising: Memory; Transceiver; as well as a processor coupled to the memory and the transceiver; The UE is configured to perform the method according to any one of claims 1 to 20.

23. A non-transitory machine-readable storage medium having instructions stored thereon, which, when executed by a computer, cause the computer to perform the method according to any one of claims 1 to 20.

24. A chip, comprising: A processor, wherein the processor is configured to call and run a computer program stored in a memory so as to enable a device equipped with the chip to perform a method according to any one of claims 1 to 20.

25. A computer-readable storage medium having a computer program stored therein, wherein: The computer program causes a computer to execute the method according to any one of claims 1 to 20.

26. A computer program product comprising a computer program, wherein: The computer program causes a computer to execute the method according to any one of claims 1 to 20.

27. A computer program, wherein: The computer program causes a computer to execute the method according to any one of claims 1 to 20.

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