Sidelink Unlicensed Priority for Channel Access and Resource Reservation

Abstract

According to an embodiment, a user equipment (UE) starts a channel occupation time (COT) following a successful listen-before-talk (LBT) procedure. The UE transmits COT information to a second UE indicating that the COT is shareable. The UE transmits a sidelink (SL) transmission in an unlicensed band within the COT.

Description

[Technical field]

[0001] [CROSS REFERENCE TO RELATED APPLICATIONS] This application claims priority to U.S. Provisional Patent Application No. 63 / 336,020, entitled “Sidelink Unlicensed Priorities for Channel Access and Resource Reservation,” filed April 28, 2022, which is incorporated by reference in its entirety herein.

[0002] The present disclosure relates generally to methods and apparatus for wireless communications and, in particular embodiments, to methods and apparatus for sidelink (SL) unlicensed priority for channel access and resource reservation. [Background technology]

[0003] Support for Vehicle-to-Vehicle (V2V) and Vehicle-to-Everything (V2X) services was introduced in LTE during Releases 14 and 15, extending the 3GPP platform to the automotive industry (TR 36.885, TR 38.885). Work items (RP-152293, RP-172293) specified the LTE Sidelink (SL) appropriate for vehicular applications, and complementary enhancements to the cellular infrastructure. Examples of V2X use case scenarios include: - Vehicles Platooning allows vehicles to dynamically form groups that travel together. -Extended Sensors enable the exchange of raw or processed data collected via local sensors or live video images between vehicles, Road Site Units (RSUs), pedestrian devices, and V2X application servers. - Advanced Driving enables semi- or fully automated driving. - Remote Driving allows remote drivers or V2X applications to operate remote vehicles for passengers who are unable to drive themselves or located in hazardous environments. Summary of the Invention

[0004] Technical advantages are generally achieved by embodiments of the present disclosure that describe methods and apparatus for sidelink (SL) unlicensed priority of channel access and resource reservation.

[0005] According to an embodiment, a user equipment (UE) starts a channel occupation time (COT) following a successful listen-before-talk (LBT) procedure. The UE transmits COT information to a second UE indicating that the COT is shareable. The UE transmits a sidelink (SL) transmission in an unlicensed band within the COT.

[0006] In some embodiments, to transmit COT information, the UE may transmit the COT information in sidelink control information (SCI) to the second UE.

[0007] In some embodiments, the COT information may further indicate an energy detection threshold (EDT) for sharing the COT and a remaining duration of the COT. In some embodiments, the EDT and the remaining duration of the COT may be indicated in additional fields of SCI format 2.

[0008] In some embodiments, the COT information may further indicate at least one of: that the first UE should extend a transmission at the end of the SL transmission into a guard symbol of an SL slot; or that the second UE should extend its second transmission into the last guard symbol of the SL slot.

[0009] In some embodiments, the first UE may receive a second transmission from the second UE, the second transmission starting during the last guard symbol of the preceding slot.

[0010] According to an embodiment, a user equipment (UE) obtains a PC5 5QI (PQI), where PC5 refers to a reference point at which a UE directly communicates with another UE over a direct channel, and 5QI refers to a 5G Quality of Service (QoS) indicator. The UE converts the PQI into a Channel Access Priority Class (CAPC). The UE performs a Listen Before Talk (LBT) procedure based on the CAPC. The UE transmits a Sidelink (SL) transmission in an unlicensed band based on a result of the LBT procedure.

[0011] In some embodiments, to obtain the PQI, the UE may obtain the PQI from a higher layer of the UE, which may be an application layer.

[0012] In some embodiments, the UE may convert the PQI into a SL priority. The UE may determine candidate SL resources in a selection window based on the SL priority. The UE may select an SL resource from the candidate SL resources for the SL transmission.

[0013] In some embodiments, converting the PQI to the CAPC may be based on a pre-configured mapping table mapping from PQI values ​​to CAPC values, in some embodiments, the pre-configured mapping table may include a first mapping from at least one of PQI values ​​21, 22, 23, 55, 90, or 91 to a CAPC value of 1, and a second mapping from PQI value 59 to a CAPC value of 3. [Brief description of the drawings]

[0014] For a more complete understanding of the present disclosure, and the advantages thereof, reference is now made to the following descriptions taken in conjunction with the accompanying drawings, in which:

[0015] [Figure 1A] 1 illustrates an exemplary communication system 100 according to an embodiment.

[0016] [Figure 1B] 1 illustrates examples of SL UEs in coverage, partial coverage, and OOC according to some embodiments.

[0017] [Diagram 2] 1 illustrates basic sensing and resource selection timing according to some embodiments.

[0018] [Figure 3A] 1 illustrates an example of a channel access procedure using Type 1 transmission according to some embodiments. [Figure 3B] 1 illustrates an example of a channel access procedure using Type 1 transmission according to some embodiments.

[0019] [Figure 4] 1 illustrates an example of Mode 1 SL operation according to some embodiments.

[0020] [Diagram 5] 1 illustrates an example of Mode 2 SL operation according to some embodiments.

[0021] [Figure 6] 1 illustrates an example of a selection window transmission sharing the same COT according to some embodiments.

[0022] [Figure 7] 1 illustrates an example of a first COT initiation with a transmission error of a first UE and a second UE initiating a second COT transmission according to some embodiments.

[0023] [Figure 8] 1 illustrates an example of a SL slot using a PSFCH according to some embodiments.

[0024] [Figure 9A] 13 illustrates a flow chart of COT allowing SL transmission during guard symbols according to some embodiments.

[0025] [Figure 9B] 13 shows a flow chart for SL transmission without guard symbols conditioned by an existing subsequent reservation according to some embodiments.

[0026] [Figure 10A] 1 illustrates a flowchart of a method performed by a UE for SL unlicensed priority of channel access and resource reservation in accordance with some embodiments.

[0027] [Figure 10B] 1 illustrates a flowchart of a method performed by a UE for SL COT sharing according to some embodiments.

[0028] [Figure 11] 1 illustrates an exemplary communication system according to some embodiments.

[0029] [Figure 12A] 1 illustrates an example device that may implement the methods and teachings of the present disclosure. [Figure 12B] 1 illustrates an example device that may implement the methods and teachings of the present disclosure.

[0030] [Figure 13] FIG. 1 is a block diagram of a computing system that can be used to implement the devices and methods disclosed herein.

[0031] Corresponding numbers and symbols in the different figures generally refer to corresponding parts unless otherwise indicated. The figures are drawn to clearly illustrate relevant aspects of the embodiments and are not necessarily drawn to scale. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0032] The making and using of the embodiments of the present disclosure will be described in detail below. However, it should be understood that the concepts disclosed herein can be embodied in a variety of specific situations, and the specific embodiments described herein are merely illustrative and do not serve to limit the scope of the claims. Furthermore, it should be understood that various changes, substitutions, and alterations can be made herein without departing from the spirit and scope of the present disclosure, as defined by the appended claims.

[0033] FIG. 1A illustrates an exemplary communication system 100 according to some embodiments. The communication system 100 includes an access node 110 serving a user equipment (UE) having a coverage area 101, such as a UE 120. In a first mode of operation, communication to and from the UE passes through the access node 110 having the coverage area 101. The access node 110 is connected to a backhaul network 115 for connection to the Internet, operation, management, etc. In a second mode of operation, communication to and from the UE does not pass through the access node 110; however, the access node 110 typically allocates resources for the UE to use to communicate when certain conditions are met. Communication between a pair of UEs 120 may use a sidelink connection (shown as two separate unidirectional connections 125). In FIG. 1A, sideline communication occurs between two UEs operating within the coverage area 101. However, sidelink communications may occur generally when both UEs 120 are outside the coverage area 101, both are inside the coverage area 101, or one is inside the coverage area 101 and the other is outside the coverage area 101. Communications between a pair of UEs and access nodes occur via a unidirectional communications link, where the communications link between the UE and the access node is referred to as an uplink 130 and the communications link between the access node and the UE is referred to as a downlink 135.

[0034] An access node may also be commonly referred to as a Node B, Evolved Node B (eNB), Next Generation (NG) Node B (gNB), Master eNB (MeNB), Secondary eNB (SeNB), Master gNB (MgNB), Secondary gNB (SgNB), network controller, control node, base station, access point, transmission point (TP), transmit / receive point (TRP), cell, carrier, macro cell, femto cell, pico cell, etc., while a UE may also be commonly referred to as a mobile station, mobile, terminal, user, subscriber, station, etc. An access node may provide wireless access according to one or more wireless communication protocols, e.g., 3rd Generation Partnership Project (3GPP) Long Term Evolution (LTE), LTE-Advanced (LTE-A), 5G, 5G LTE, 5G NR, 6th Generation (6G), High Speed ​​Packet Access (HSPA), IEEE 802.11 family of standards, such as 802.11a / b / g / n / ac / ad / ax / ay / be, etc. It will be appreciated that a communications system may employ multiple access nodes capable of communicating with multiple UEs, however, for simplicity, only one access node and two UEs are illustrated.

[0035] The Technical Specification Group (TSG) Radio Access Network (RAN) has defined a set of corresponding 5G RAN requirements, channel models, etc. for New Radio (NR).

[0036] Although NR sidelink was initially developed for V2X applications, there is growing industry interest in extending the applicability of NR sidelink to commercial use cases. For commercial sidelink applications, two requirements have been identified: (1) increased sidelink data rates, and - (2) Support for new carrier frequencies for sidelink.

[0037] Increased sidelink data rates are motivated by applications such as sensor information (e.g., video) sharing between vehicles with a high degree of driving automation. Commercial use cases may require more data rates than are possible in Rel-17. Increased data rates can be achieved with support for sidelink carrier aggregation and sidelink over unlicensed spectrum. Furthermore, by enhancing Frequency Range 2 (FR2) sidelink operation, increased data rates can be supported more efficiently over FR2. While support for new carrier frequencies and larger bandwidths also enable improvements to data rates on the sidelink, the main benefits come from making the sidelink more applicable to a wider range of applications. More specifically, with support for unlicensed spectrum and enhancements in FR2, sidelink may become easier to implement in commercial devices since utilization of Intelligent Transportation Systems (ITS) bands is limited to its safety-related applications.

[0038] There are two 3GPP defined resource allocation modes, Mode 1 and Mode 2, for sidelink resource allocation.

[0039] In Mode 1, the base station schedules SL resources to be used by the UE for SL transmission. In Mode 1 (NR Uu link), the base station may allocate NR SL resources in the following cases: (i) licensed carriers shared between NR Uu and NR SL (PC5 link); and (ii) NR SL dedicated carriers. Mode 1 may be used in-coverage but not out-of-coverage. The following techniques are supported for resource allocation Mode 1 (in-coverage): - Dynamic resource allocation, and - Pre-configured grant types 1 and 2.

[0040] In Mode 2, the UE determines the SL transmission resources within the SL resources configured by the base station / network or pre-configured SL resources (i.e., the base station does not perform scheduling). Mode 2 can be used in coverage or out-of-coverage (OOC).

[0041] The SL resource allocation mode 2 provisions cover: a) The UE autonomously selects SL resources for transmission; b) The UE assists in SL resource selection for other UEs, which is a function that may be part of a), c), d); c) The UE is configured with an NR configured grant (similar to Type 1) for SL transmission; and d) The UE schedules SL transmissions of other UEs.

[0042] Sensing and resource (re)selection related procedures are supported for resource allocation mode 2.

[0043] 1B illustrates examples of SL UEs in coverage, partial coverage, and out-of-coverage (OOC) according to some embodiments. UE 151a is in the coverage of gNB 161. UE 151a and gNB 161 may communicate with each other using a Uu interface. UE 151b is in the coverage of roadside unit (RSU) 162 and RSU 163 and may use a PC5 interface to communicate with RSU 162 and / or RSU 163. UE 151c is in the coverage of RSU 163.

[0044] UEs 152a, 152b, and 152c are OOC SL UEs. Additionally, UE 153 is in partial coverage. The UEs may communicate with each other using a PC5 interface (e.g., between UE 151a and UE 151b).

[0045] Each transport block (TB) has an associated sidelink control information (SCI) message. The SCI is divided into two stages: a first stage SCI carried in the physical sidelink control channel (PSCCH) and a second stage SCI carried in the physical sidelink shared channel (PSSCH).

[0046] The PSCCH may carry the SCI. The source UE uses the SCI to schedule the transmission of data on the PSSCH or to reserve resources for the transmission of data on the PSSCH. The SCI may convey time and frequency resources of the PSSCH and / or parameters for a hybrid automatic repeat request (HARQ) process, such as redundancy version, process id (or ID), new data indicator, and / or resources for a physical sidelink feedback channel (PSFCH). The time and frequency resources of the PSSCH may be referred to as resource assignments or allocations and may be indicated in a time resource assignment field and / or a frequency resource assignment field (i.e., resource location). The PSFCH carries HARQ feedback over the sidelink from UEs that are intended recipients of the PSSCH transmission to the UE that performed the transmission.

[0047] The HARQ feedback is called HARQ-ACK. HARQ-ACK carries an ack or nack indicating whether the destination UE has correctly decoded the payload carried in the PSSCH or not. The SCI may also carry a bit field indicating or identifying the source UE. In addition, the SCI may carry a bit field indicating or identifying the destination UE. The SCI may further include other fields to carry information such as the modulation coding scheme used to encode the payload and modulate the coded payload bits, the demodulation reference signal (DMRS) pattern, the antenna port, the priority of the payload (transmission), etc. The detecting UE performs detecting in the sidelink (i.e., receiving the PSCCH transmitted by another UE), decoding the SCI carried in the PSCCH to obtain the information of the resources reserved by the other UE, and determining the resources for the detecting UE's sidelink transmission.

[0048] The detection procedure is defined as decoding the SCI from other UEs and / or SL measurements. Decoding the SCI in this procedure provides information on at least the SL resources indicated by the UE transmitting the SCI. The detection procedure uses L1 SL RSRP measurements based on the SL DMRS if the corresponding SCI is decoded. The resource (re)selection procedure considered uses the result of the detection procedure to determine the resources for SL transmission.

[0049] Basic sensing and resource selection timing is illustrated in FIG. proc,0 is the time required for the UE to complete the detection process, and T proc,1 is the maximum time required for the UE to identify candidate resources and select new sidelink resources.

[0050] During the sensing window 202, the SL UE decodes the SCI from other UEs and performs SL measurements. Among the information provided by the first stage of the SCI format (SCI format 1-A) (TS 38.212) carried in the PSSCH, there is the following: Priority - 3 bits specified in clause 5.4.3.3 of (12, TS 23.287) and clause 5.22.1.3.1 of (8, TS 38.321). A value of "000" in the priority field corresponds to a priority value of "1", a value of "001" in the priority field corresponds to a priority value of "2", and so on. Lower priority values ​​correspond to higher priority and higher priority values ​​correspond to lower priority. - Frequency resource allocation - Time resource allocation -Resource reservation period -DMRS pattern - 2nd stage SCI format, and / or - number of DMRS ports, modulation coding scheme (MCS). The priority level is used to select for which PC5 service data the QoS requirements are prioritized, so that a PC5 service data packet with a priority level value N is prioritized over PC5 service data packets with higher priority level values ​​(i.e. N+1, N+2, etc.) with lower numbers signifying higher priorities.

[0051] The PC5 priority level provided in the SCI (also known as SL reservation priority, data priority (where data priority specifies the priority of the reservation) or SL priority) is used to determine the subset of resources to be reported to higher layers in the PSSCH resource selection in sidelink resource allocation mode 2.

[0052] To trigger this procedure, in slot n, higher layers provide the following parameters for this PSSCH / PSCCH transmission: - the resource pool the resource reports to; - L1 priority, prio TX ; - remaining packet delay budget; - the number of subchannels used for PSSCH / PSCCH transmission in a slot, L subCH ; - optionally a resource reservation interval in msec, P rsvp_TX ; - If the higher layers have requested the UE to determine a subset of resources from which the higher layers will select resources for PSSCH / PSCCH transmission as part of a re-evaluation or pre-emption procedure, the higher layers provide a set of resources that may be subject to re-evaluation (r0, r1, r2, ...) and a set of resources that may be subject to pre-emption (r0', r1', r2', ...). - Slot r i It is up to the UE implementation to determine the subset of resources according to a request by higher layers before or after T3, where r i '' is the slot with the smallest slot index among (r0, r1, r2, ...) and (r0', r1', r2', ...), and T3 is

number

number

[0053] During the sensing procedure, the monitoring UE detects the SCI transmitted in each SL slot in the sensing window 202 and measures the Reference Signal Reception Power (RSRP) of the resource indicated in the SCI. The monitoring UE may receive the data transmission while sensing (it may be the receiving UE). In case of periodic traffic, the resource reservation for sidelink transmission is performed when the UE detects the SCI in slot s k If the resource above is occupied, slot s k +q*RRI m also occupies the resource above, where q is an integer and RRI m The detection UE is the UE that is detected m The detecting includes receiving and decoding the PSCCH and processing the SCI in the PSCCH.

[0054] In case of aperiodic or dynamic transmission, the transmitting UE reserves multiple resources and indicates the next resource in the SCI. Thus, based on the sensing result, the monitoring UE may determine which resources may be occupied in the future and may avoid them for its own transmission if the measured RSRP on the occupied resources is greater than the RSRP threshold during the sensing period.

[0055] If resource selection is triggered on slot N in FIG. 2, then the number of times the resource selection is triggered is determined based on the number of times the resource selection is triggered in the detection window 202 (i.e., slots [n-T0, nT proc,0 Based on the sensing result (on slot [n+T1, n+T2]), the transmitting UE selects resources on the resource selection window 204 (i.e., on slot [n+T1, n+T2]), where: T0: Number of slots with value determined by resource pool configuration: T proc,0 : the time required for the UE to complete the sensing process; T1: Identification of candidate resources and resource selection T1≦T proc,1 the processing time required; T2: It was left to the UE implementation, but [T 2min,PDB] is the last slot in the resource pool for resource selection, where T 2min is the minimum value of T2, which denotes the PDB, packet delay budget, the remaining time for the UE to transmit a data packet; T proc,1 : The maximum time required for the UE to identify candidate resources and select new sidelink resources.

[0056] To select resources, the transmitting UE needs to identify candidate resources by eliminating occupied resources with measured RSRPs above a configured RSRP threshold. Then, the transmitting UE compares the proportion of available resources to all resources within the selection window 204.

[0057] If the percentage of available resources is greater than the threshold X%, the UE randomly selects a resource from the candidate resources.

[0058] The SL priority level is used to determine the percentage of available resources as follows: If the percentage is smaller, the transmitting UE increases the RSRP threshold by 3 dB and checks the percentage of available resources until the percentage of available resources is equal to or greater than X%, where X is selected from a list, i.e., sl-TxPercentageList, and its value is determined by the data priority (SL priority level). sl-TxPercentageList: Given prio TX The inner parameter X is the percentage converted to a proportion, sl-TxPercentageList(prio TX ) is defined as

[0059] Possible values ​​of X in sl-TxPercentageList are 20, 35, and 50 (corresponding to 20%, 35%, and 50%, respectively), as specified in TS 38.331 below. SL-TxPercentageList-r16::=Sequence of SL-TxPercentageConfig-r16 (size (8)) SL-TxPercentageConfig-r16::=Sequence { sl-Priority-r16 integer(1..8), sl-TxPercentage-r16 Enumeration {p20,p35,p50} }

[0060] NR channel access procedures in shared (unlicensed) spectrum are specified in TS 37.213. The document specifies several types of channel access based on Listen-Before-Talk (LBT). A device (UE) before transmitting may perform a Channel Assessment (CA) detection to determine if the channel is idle or in use. If the channel is determined to be idle, some channel access schemes may require that a random backoff procedure follow the initial CA.

[0061] SL resource selection is done in two stages. In the first stage, the sidelink specification in the shared spectrum (SL-U) UE monitors the sensing window 202 and builds a candidate resource list from the resource candidates in the selection window 204 based on the decoded SCI and the measured RSRP as described above. The candidate resource list is then provided to higher layers. In the second stage, the higher layers select from the candidate resource list a list of selected resources provided to the PHY layer.

[0062] In the definition of the selection window 204 in FIG. 2, the selection of T1 is:

number

[0063] The set S used for candidate selection Ais initialized for the set of all candidate single-slot resources.

[0064] A UE belongs to a set S if all of the following conditions are met: A From any candidate single slot resource R X,Y shall be excluded. -UE is a slot

number

number

[0065] Congestion control in SL is used to limit access and avoid possible collisions. For this purpose, two measures are specified in TS 38.215. - Channel Busy Fraction (CBR): measured in slot n is defined as the fraction of subchannels of the resource pool for which the SL RSSI measured by the UE exceeds a (pre)configured threshold detected over the CBR measurement window [na,n-1]; - Channel Occupancy Ratio (CR): evaluated in slot n is defined as the total number of subchannels granted in slot [n,n+b] used for its transmission in slot [na,n-1] divided by the total number of subchannels configured in the transmission pool over [na,n+b].

[0066] Higher layers via the IE sl-CBR-PriorityTxConfigList indicate the mapping between the PSSCH transmission parameters (MCS, PRB number, retransmission number, CR limit, etc.) set by using the index of the configuration provided in the sl-CBR-PSSCH-TxConfigList, the CBR range by index to the CBR range configuration entry in the sl-CBR-RangeConfigList, and the priority range.

[0067] Therefore, CR and CBR are used for: - if configured by Radio Resource Control (RRC), select the number of HARQ retransmissions from the allowed number in sl-MaxTxTransNumPSSCH included in sl-PSSCH-TxConfigList, and if configured by RRC, select the number of HARQ retransmissions from the overlapping allowed number in sl-MaxTxTransNumPSSCH indicated in sl-CBR-PriorityTxConfigList of the highest priority of the logical channel allowed on the carrier and the CBR measured by the lower layers, - if configured by RRC, select the amount of frequency resources in the range between sl-MinSubChannelNumPSSCH and sl-MaxSubchannelNumPSSCH included in sl-PSSCH-TxConfigList, and if configured by RRC, select the amount of frequency resources in the overlapping range between MinSubChannelNumPSSCH and MaxSubchannelNumPSSCH indicated in sl-CBR-PriorityTxConfigList of the highest priority of logical channels allowed on the carrier and the CBR measured by the lower layer; - if configured by RRC, select an MCS in the range between sl-MinMCS-PSSCH and sl-MaxMCS-PSSCH associated with the selected MCS table included in sl-PSSCH-TxConfigList (if configured), and if configured by RRC, select an MCS in the overlapping range between sl-MinMCS-PSSCH and sl-MaxMCS-PSSCH associated with the selected MCS table indicated in sl-CBR-PriorityTxConfigList of the highest priority of the sidelink logical channel in the MAC PDU and the CBR measured by the lower layers.

[0068] Congestion control is specified for each transmission pool as follows: o Stage 1: Configuration parameters are in place. Note: parameters can be pre-configured or received over a network. o Step 2: Receive an upper layer packet with its associated ProSe per-packet priority (PPPP). o Step 3: From the configuration, determine the PDB of this packet for this PPPP value. 〇Step 4: Calculate the current CBR. o Step 5: Calculate the CRlimit for this PPPP based on the CBR. o Step 6: Select transmission resources for the packet so that the CR limit can be met.

[0069] Here, the channel occupancy ratio (CR) limit values ​​corresponding to the CBR measurement ranges are specified in Table 1 as follows: The CR limit or CRlimit is a limit on the maximum channel occupancy ratio. [Table 1] Table 1 (CR limit values)

[0070] Inter-UE coordination (IUC) is part of the SL design to address the hidden node problem and the half-duplex constraint. For IUC, three categories of resources are identified: - The preferred resources exclude those resources that overlap with reserved resources indicated by a received SCI format 1-A for which the RSRP measurement is higher than the RSRP threshold (i.e., resources including those reserved by a received SCI for which the RSRP measurement is lower than the RSRP threshold). - Undesirable resources include: o resources by half-duplex UEs intending to receive on those resources, or Resources designated by SCI Format 1-A that meet at least one of the following: When received (SCI format 1-A), the performed RSRP measurement is higher than some threshold Th(prio_RX), where prio_RX is the value of the priority field in the received (SCI format 1-A); or The UE is the destination UE of a TB associated with the received (SCI format 1-A) and the RSRP measurement performed on the received (SCI format 1-A) is lower than Th'(prio_RX), where prio_RX is the value of the priority field in the received (SCI format 1-A). NOTE 1: The set of preferred and non-preferred resources may differ for transmitters and receivers, as it reflects the local view. NOTE 2: The assumption is that UE-A's transmission reservations are already known by UE-B and are excluded from the selection window. - Conflicted Resources: 〇Reservation is the second strongest SCI>Th(prio2,prio1) where prio2 and prio1 are within the received SCI. o The UE has two reservation destinations |RSRP1-RSRP2|>(pre)configured threshold; * Reservations that overlap with half-duplex situations. (NR Channel Access in Shared Spectrum)

[0071] License-exempt spectrum, also known as unlicensed spectrum, has attracted a lot of interest from cellular operators in the past few years. LTE-LAA (Licensed Assisted Access) is specified in 3GPP LTE releases 13 and 14. More recently, in New Radio Unlicensed (NR-U), operation in unlicensed spectrum (shared spectrum) is specified in release 16 (TS 38.213).

[0072] 3GPP and IEEE technologies operating in unlicensed spectrum use Listen-Before-Talk (LBT) channel access. In certain regions, such as the European Union and Japan, LBT rules are enforced by spectrum regulators to reduce interference risks and provide a fair coexistence mechanism. The LBT mechanism requires a transmitter to check before transmitting to see if there are other occupants of the channel and to postpone transmission if the channel is occupied.

[0073] In particular, the LBT rules for the 5 GHz band use Clear Channel Assessment (CCA) to determine whether a channel is available for transmission. CCA checks whether the received energy is above a threshold. If the detected energy is above the CCA threshold, the channel is considered to be in use (busy), otherwise it is considered to be idle. If the channel is idle, the transmitter may transmit with a bandwidth of at least, for example, 80% of the total channel bandwidth for the duration of the Channel Occupancy Time (COT). The maximum COT duration of a transmission burst may refer to ETSI EN 301893. The maximum COT (MCOT) duration is a function of the Channel Access Priority Class (CAPC). To determine the Channel Occupancy Time (COT), if the transmission gap is less than or equal to 25us, the gap duration is counted in the channel occupation time. A transmission burst is defined as a set of transmissions with a gap of 16us or less, and if the gap is greater than 16us, the transmissions are considered to be separate.

[0074] There may be several types of channel access for each of the downlink (DL) and uplink (UL). Type 1 UL Channel Access Procedure

[0075] This section describes a channel access procedure by a UE, where the duration spanned by sensed slots sensed as idle prior to a UL transmission is random. This section is applicable to the following transmissions: - PUSCH / SRS transmissions scheduled or configured by the eNB / gNB, or - PUCCH transmissions scheduled or configured by the gNB, or - Transmission regarding the random access procedure.

[0076] The UE may send a transmission using the Type 1 channel access procedure after the UE first senses the channel as idle for a slot duration of the deferral time Td and after the counter N reaches zero in step 4. The counter N is adjusted by sensing the channel for additional slot durations according to the steps described below. 1)N=N init Set N init 0 and CW P , and proceed to step 4. 2) If N>0 and the UE chooses to decrement the counter, set N=N-1. 3) Sense the channel for the additional slot duration and if the additional slot duration is idle go to step 4, otherwise go to step 5. 4) If N=0, stop; else go to step 2. 5) The busy slot is postponed for an additional time T d or until it is detected within an additional delay time T d The channel is sensed until all slots of are detected as idle. 6) The channel is delayed for an additional time T d If the ,slot is detected as being idle for all slot durations, go to step 4; otherwise, go to step 5.

[0077] If the UE does not transmit a UL transmission on a channel on which a UL transmission is performed after step 4 in the above procedure, the channel must be stable for at least the sensing slot duration T when the UE is ready to transmit a transmission. sl If the channel is detected as idle at d The UE may transmit a transmission on a channel if it is sensed as idle for all slot durations T. The UE may transmit a transmission on a channel if it senses the channel for the first time after it is ready to transmit. slIf the channel is not detected as idle in d If the UE is not sensed as idle during any of the sensing slot durations, the UE waits for the channel to be deferred for a deferral time T d After detecting that the node is idle for the slot duration, it proceeds to step 1.

[0078] postponement time T d m p A time period T in which consecutive slot durations immediately follow each other f = 16 μs, where each slot duration is T sl = 9 μs, T f is T f At the beginning of the idle slot duration T sl Includes.

[0079] CW min,p ≦CW p ≦CW max,p is the contention window. CW p The adjustments are explained in Section 4.2.2. min,p and C.W. max,p was selected prior to step 1 of the procedure above.

[0080] m p , C.W. min,p , and C.W. max,p is based on the channel access priority class signaled to the UE, as shown in Table 4.2.1-1. Type 2 UL Channel Access Procedure

[0081] This section describes the channel access procedure by a UE, where the duration spanned by sensed slots sensed as idle prior to UL transmission is deterministic.

[0082] If the UE is instructed by the eNB to perform a Type 2 UL Channel Access procedure, the UE shall follow the procedure described in the following section (Type 2A UL Channel Access Procedure). Type 2A UL Channel Access Procedure

[0083] If the UE is instructed to perform a Type 2A UL channel access procedure, the UE uses the Type 2A UL channel access procedure for UL transmission. The UE determines whether the channel is stable for at least the sensing interval T short_ul A transmission may be sent immediately after it has been detected as idle for T = 25 μs. short_ul is the duration T f = 16 μs, T f is T f The channel includes a sensing slot at the beginning of T short_ul If both of the detection slots of T are detected as idle, short_ul is considered idle during Type 2B UL Channel Access Procedure

[0084] If the UE is instructed to perform a Type 2B UL channel access procedure, the UE uses the Type 2B UL channel access procedure for UL transmission. The UE f A transmission may be sent immediately after detecting idleness within T = 16 μs. f is T f If the channel is sensed as idle for at least a total of 5 μs and at least 4 μs of sensing occurs in a sensing slot, the channel is sensed as idle for a duration of T f is considered to be idle within Type 2C UL Channel Access Procedure

[0085] If the UE is instructed to perform a Type 2C UL channel access procedure for an UL transmission, the UE does not sense the channel before transmission. The duration of the corresponding UL transmission is up to 584 μs.

[0086] Based on the flowcharts in FIG. 3A and FIG. 3B, the UE determines the deferral time Td After first sensing that the channel is idle for a sensing slot duration, and after counter N reaches zero, the channel access procedure is sent using Type 1. Counter N is the minimum contention window (CW min ) and the maximum contention window value (CW max ) and is decremented if it senses that the channel is idle for an additional sensing slot duration Ts. min and C.W. max The value of is based on the Channel Access Priority Class (CAPC) signaled to the UE. After a successful LBT procedure, the device may transmit continuously without another LBT procedure for a maximum channel occupancy time (COT), which is also based on the CAPC.

[0087] In this clause, the total channel occupancy time of the autonomous uplink transmission obtained by the channel access procedure (including the following DL transmission when the UE sets the "COT sharing indication" of the AUL-UCI to "1" in a subframe within the autonomous uplink transmission) is T ulm cot,p Not more than 100, where T ulm cot,p are given in Table 2 below. [Table 2] Table 2

[0088] When using a higher CAPC, devices on average access the channel faster (CW max ), accessing for a shorter duration (due to the limitation of the maximum COT duration, T ulm cot,p A lower CAPC value means higher priority and a higher CAPC value means lower priority.

[0089] The Channel Access Priority Class (CAPC) of a Radio Bearer and a Medium Access Control (MAC) Control Element (CE) is either fixed or configurable: - Padding Buffer Status Report (BSR) and Recommended Bit Rate MAC CE are fixed to the lowest priority; - fixed to the highest priority when signaling radio bearer (SRB) 0, SRB1, SRB3 and other MAC CEs; - For SRB2 and Data Radio Bearer (DRB), they are configured by the gNB.

[0090] When selecting the CAPC for the DRB, the gNB takes into account the 5G QoS Indicator (5QI) of all QoS flows multiplexed in the DRB, taking into account different traffic types and fairness between transmissions. The table below shows which CAPC should be used for which standardized 5QI (i.e., which CAPC to use for a given QoS flow).

[0091] A QoS flow corresponding to a non-standardized 5QI (ie, an operator-specific 5QI) should use the CAPC of the standardized 5QI that best matches the QoS characteristics of the non-standardized 5QI.

[0092] 5QI is a scalar used as a measure of 5G QoS characteristics, i.e., access node specific parameters that control the QoS forwarding treatment for QoS flows (e.g., scheduling weights, admission thresholds, queue management thresholds, link layer protocol configurations, etc.). Standardized 5QI values ​​have a one-to-one mapping to standardized combinations of 5G QoS characteristics, which may refer to Table 5.7.4-1 of TS 23.501 V17.4.0(2022-03).

[0093] Table 3 below shows the mapping between CAPC and 5QI (lower CAPC means higher priority). [Table 3] Table 3

[0094] When performing Type 1 LBT for uplink TB transmission (see TS 37.213, clause 4.2.1.1) and if CAPC is not indicated in the DCI, the UE shall select CAPC as follows: - if only MAC CEs are included in the TB, the highest priority CAPC of those MAC CEs is used; or - if a Common Control Channel (CCCH) Service Data Unit (SDU) is included in the TB, the highest priority CAPC is used; or - if a dedicated control channel (DCCH) SDU is included in the TB, the highest priority CAPC of the DCCH is used; or - Otherwise, the lowest priority CAPC of a logical channel having MAC SDUs multiplexed in the TB is used.

[0095] If the UE uses a type 1 channel access procedure for a physical uplink shared channel (PUSCH) transmission on the configured resources, the UE determines the corresponding UL channel access priority p in Table 4.2.1-1 of 3GPP TS 38.300.

[0096] If the UE uses the Type 1 channel access procedure for a PUSCH transmission with user plane data indicated by the UL grant or for a random access procedure where no corresponding UL channel access priority p is indicated, the UE shall determine p in Table 4.2.1-1 of 3GPP TS 38.300 following the same procedure as for a PUSCH transmission on configured resources using the Type 1 channel access procedure.

[0097] The CAPC value is provided to the UE via the ChannelAccess-CPext field in downlink control information (DCI) format 0_0, DCI format 0_1 ​​and format 0_2, format 1_0, format 1_1 and format 1_2 specified in TS 38.212.

[0098] DCI format 0_1 ​​is used for scheduling one or more PUSCHs in one cell or for indicating CG downlink feedback information (CG-DFI) to a UE. DCI format 0_2 and DCI format 0_0 are used for scheduling PUSCHs in one cell.

[0099] DCI format 1_0 is used for scheduling a PDSCH in one DL cell, DCI format 1_1 is used for scheduling one or more PDSCHs in one cell, and DCI format 1_2 is used for scheduling a PDSCH in one cell.

[0100] TS 38.212 specifies the permitted entries of the channel access values ​​for dynamic and semi-static modes.

[0101] A flow chart for channel access based on CAPC(p) is specified in ETSI 301.893, Annex F, and is shown herein in Figures 3A and 3B.

[0102] In the current system, there is no sidelink specification in shared spectrum (SL-U).

[0103] SL-U is expected to follow the NR-U channel access specified in TS 37.213. Also, SL-U is expected to reuse the SL resource allocation method as much as possible. First, CAPC is not specified for all possible values ​​of SL priority used for resource reservation, and vice versa. Therefore, one possible problem that may arise when CAPC and SL resource priority for unlicensed channel access are used independently and based on existing specifications is that some combinations of CAPC and SL priority may not match. For example, it may happen that a CAPC class with a high priority (e.g., 1) is used to access a reservation made with a SL resource reservation with a low priority (e.g., 8), and vice versa. This may result in unfair channel access and resource allocation, which may be detrimental to the QoS of various flows.

[0104] In some examples, in the case of SL for video sharing application for cooperative collision avoidance (PQI=90), the SL priority is fairly high (3 on a scale of 1-8) and the delay is critical (10 ms packet delay budget). If the corresponding CAPC entry used for video sharing is video buffer streaming (5QI=4), this translates to an undesirable lower priority and higher latency of channel access, respectively, CAPC=4, and the delay range is 300 ms.

[0105] For Mode 1 resource allocation, one problem is that DCI format 3_0 does not provide the necessary parameters for SL unlicensed access, such as CAPC. DCI format 3_0 is specified in TS 38.212 and is used for scheduling NR PSCCH and NR PSSCH in one cell. DCI format 3_1 is specified in the same document and is used for scheduling LTE PSCCH and LTE PSSCH in one cell.

[0106] For Mode 2 resource allocation, one problem is that CAPC and SL priority levels do not cover the same type of traffic. The problem to be solved is to accommodate different types of priorities (channel access and resource selection).

[0107] Another technical problem addressed by this disclosure is the signaling of CAPC and SL priority levels of SL-U.

[0108] This disclosure proposes channel access support and signaling necessary for SL-U UE operation in Mode 1 and Mode 2. In this disclosure, the term SL-U UE may be used to identify a Sidelink (SL) UE operating in an unlicensed (shared) spectrum.

[0109] First, regarding the use of CAPC and SL priorities, they are used for different purposes and have different time scales.

[0110] CAPC is used for LBT to detect the COT maximum duration. The LBT timing (based on the CAPC value) is very short, on the order of tens to hundreds of microseconds or less for the 5 GHz band, which can be equivalent to one or several OFDM symbol durations. For example, for CAPC=1, the LBT duration (if successful) corresponds to the detection slot duration (9 us) plus the duration of the backoff period (between 3×9 and 7×9 μs), i.e., less than 73 us. Subcarrier spacing values ​​of {15, 30, 60, 120} kHz correspond to OFDM symbol durations of {66.7, 33.3, 16.7, 8.33} us.

[0111] The purpose of SL resource reservation is to reserve some resources for future transmissions. These reservations are made only on SL resources (which are a subset of UL resources when sidelink and uplink are on the same carrier) and the reservations are decoded and honored only by SL UE devices that are able to decode the Sidelink Control Information (SCI). The reservation methodology is specified by 3GPP and followed only by 3GPP devices that implement this feature. However, channel access (based on CAPC) is mandatory for any type of device (hence non-3GPP) operating in the EU 5GHz unlicensed band and is specified by ETSI.

[0112] The duration of the SL resource reservation window is much longer than the channel access LBT. The SL detection window is up to 100 ms, while the resource selection window duration is T2-T1 (Fig. 2), where T1 can be as low as zero and T2 min contains {1,5,10,20}*2^mu slots, where mu values ​​{0,1,2,3} correspond to SCS values ​​of {15,30,60,120} kHz. This results in T2 min values ​​equivalent to {1,5,10,20} ms.

[0113] In some embodiments, the 5QI-based CAPC table may be extended to include PQI values. One example of such an extension is provided in Table 4 below. [Table 4] Table 4

[0114] The extensions provided herein, or other possible similar extensions, may be mapped together to the same CAPC, 5QI and PQI values ​​corresponding to similar or similar QoS requirements, such as packet delay budget, maximum packet error rate, flow category (Guaranteed Bit Rate (GBR), non-GBR, delay-critical GBR), etc.

[0115] In some embodiments, the mapping need not be one-to-one, for example PQI22 may be mapped to both CAPC1 and CAPC2, leaving it up to the implementation which CAPC value is actually used for channel access.

[0116] In some embodiments, there may be a mapping rule between 5QI and PQI values, for example, all delay-severe GBR traffic corresponds to the same CAPC value as in the GBR case, but non-GBR type traffic corresponds to a different CAPC value.

[0117] In some embodiments, CAPC values ​​may be constrained to be available or unavailable to be used for certain priority levels, for example traffic at priority levels 6, 7 or 8 may not use CAPC value 1, or priority levels higher than 3 may be mapped to CAPC value 4, or several overlapping ranges of SL priority levels may be assigned different CAPC values ​​and left for implementation to decide the actual selection of CAPC when channel access occurs.

[0118] In some embodiments, a further rule may be considered: the CAPC value corresponds to the two most significant bits (MSBs) of the SL priority level encoded in a 3-bit field. For example, CAPC1 may correspond to a (000,001) value of SL priority (0 and 1). CAPC2 may correspond to SL priority 2 and 3 (010,011 binary).

[0119] In yet some other embodiments, the mapping between CAPC values ​​and SL priority levels may be provided via (pre-)configuration as an index in a table entry.

[0120] In some embodiments, the PHY layer may be provided with both CAPC and SL priority levels via scheduling downlink control information (DCI) or radio resource control (RRC) configuration.

[0121] For each transmission, the SL-U UE uses CAPC to gain channel access, and for each resource selection corresponding to that transmission, the SL-U UE uses the corresponding SL priority level.

[0122] 4 illustrates an example of Mode 1 SL operation according to some embodiments. In Mode 1 of SL operation, the gNB 402 allocates SL resources across a Uu link via a DCI. The resources are used by a SL-U UE (e.g., UE 404) for exchange over a PC5 link with another SL-U UE (e.g., UE 406). For Mode 1 of operation in embodiments, the DCI dedicated to SL-U resources also carries the CAPC priority of SL unlicensed access or an index into a table that maps CAPC to 5QI and PQI values.

[0123] For example, DCI format 3_0 may be extended to cover SL-U allocations for Mode 1 with a bit field dedicated to CAPC when the resource pool index indicates a shared spectrum transmission. In another embodiment, the DCI may have a bit field indicating that the resource pool index is used for shared spectrum access.

[0124] In different embodiments, the gNB 402 via the DCI may provide a channel occupation duration (COT) that a SL-U UE (e.g., UE 404) may use for transmission, which may be less than the maximum COT allowed by the provided CAPC channel access rules.

[0125] COT is specific to shared spectrum (unlicensed) channel access.

[0126] The UE may or may not be required to perform an LBT prior to its transmission, which may be made either with reserved resources or without reservation.

[0127] The following list shows examples where a transmission may not require the LBT procedure (channel sensing): - if there is a short control transmission (with short duration as specified by the 3GPP NR-U and ETSI BRAN specifications) (Type 2C); - When there is a transmission in a shared COT that immediately follows another transmission in the same COT.

[0128] The following list shows examples where a transmission may require the LBT procedure (channel sensing): If the transmission needs to start a COT (type 1); - In case of a transmission in a shared COT with a gap to the previous transmission (eg type 1, type 2A, type 2B).

[0129] In the following section, a SL UE that initiates a COT (e.g., an initiating UE) is a SL UE that transmits after successfully performing a Type 1 LBT, which is not in a shared COT. A UE that initiates a COT may or may not share its COT with other UEs. Those UEs that share a COT with the initiating UE may be referred to as "responder UEs."

[0130] Additionally, in Mode 1, DCI format 3_0 used for SL-U resource allocation may indicate whether the SL-U UE transmission should be within the SL-U UE that initiated COT or can be within a shared COT transmission. The DCI may also indicate the Energy Detection Threshold (EDT) to use for its LBT procedure if the SL-U UE initiates COT, or the EDT if the SL-U UE uses shared COT.

[0131] For example, in DCI format 3_0, the gNB402 may provide two EDT values: one that the COT initiator uses for channel sensing when initiating COT, and the other EDT that the SL-U UE COT initiator provides to the SL-U UE responder for COT sharing purposes.

[0132] 5 illustrates an example of SL operation in Mode 2 according to some embodiments. In Mode 2, an SL-U UE (e.g., UE 502) may autonomously select resources for transmission and assist other SL-U UEs (e.g., UEs 504, 506 and / or 508) for their resource selection (e.g., using IUC). For this mode, the priority level for channel access (CAPC) is derived by the SL-U UE by the method proposed above. Higher layers provide CAPC values ​​for channel access to lower layers.

[0133] COT sharing is also supported in mode 2. In this mode, the essential information for COT sharing is provided in the SCI.

[0134] In the next section, COT sharing solutions for SL are provided for different resource reservation and LBT results.

[0135] FIG. 6 illustrates an example of selection window transmission sharing the same COT according to some embodiments. In FIG. 6, after a successful LBT, UE1 initiates a COT and informs UE2 and UE3 that the COT can be shared, as well as the EDT and remaining COT duration required for sharing the COT. UE2 may share the UE1 initiated COT, and UE2 is not required to initiate its own COT. However, depending on the gap duration, it may be necessary to perform an LBT procedure prior to transmission. If the gap is short (e.g., less than 16us between UE1 and UE2 transmissions), no LBT procedure is required. If the gap is between 16 and 25us, UE2 LBT may be shorter (LBT type 2). If the gap is larger than 25us, LBT type 1 may be required while sharing the COT. These LBTs for COT sharing use the EDT indicated by the COT initiator. UE3 shares the same COT as UE2 and UE1. However, UE3's transmission does not require the execution of an LBT since it occurs immediately after UE2's transmission. Additionally, UE3 may need to listen to the channel to ensure that UE2's transmission occurs on time and is not canceled by a failed LBT.

[0136] Examples of possible gaps between UE1 and UE2 may be one or more slots, or even a single symbol if UE1 transmission carries a PSFCH followed by a flexible symbol.

[0137] If the LBT fails, the following are some possible scenarios: 1) If a reservation for retransmission already exists, the UE may wait for the next opportunity to retransmit and determine whether the retransmission is in a new starting COT or a shared COT of the existing COT. 2) If there is no reservation, a new reservation may be necessary, or a reservationless transmission (opportunistic) is performed if unreserved resources exist.

[0138] For the second scenario, the time for retransmission required by the packet budget delay may be limited. For example, assume that there are periodic transmissions of configured grants with some resources reserved periodically. If one of the transmissions fails due to LBT failure, the transmitter UE may have some new retransmission time limit specified to find resources to retransmit. If these resources are not found, the transmitter UE may need to wait for the next configured grant period. The packet delay budget is greater than the duration from the arrival of the packet at the PHY layer to the first reserved resource (first transmission) and the retransmission time limit during which the retransmission of the first transmission may occur.

[0139] FIG. 7 illustrates an example of a first COT start with a transmission error of a first UE and a second UE starting a second COT transmission according to some embodiments. In FIG. 7, UE1 transmission may fail due to LBT, and therefore the first COT (COT1) cannot start. UE2 may start a second COT (COT2), which is a shared COT. UE1 may attempt to retransmit if there are non-occupied reserved resources (UE1R) before the retransmission time limit expires from the initial UE1 attempt. If no such opportunity is found, the next transmission opportunity may be the next grant period. The packet delay budget is typically less than the selection window limit of 31 slots.

[0140] When the SL-U UE initiates COT, if indicated in higher layer parameters, it may inform the responding device of the remaining duration of the COT via one or more fields in SCI format 2. The SCI may also indicate whether sharing of the COT is allowed or not. In addition, if indicated by higher layers, the SL-U UE may indicate via SCI format 2 the EDT value to be used by the responding device for COT sharing purposes.

[0141] Figure 8 shows an example of a SL slot with PSFCH according to some embodiments. Figure 8 shows that the SL slot ends the guard symbol when there is no transmission. Therefore, it may appear that there is always a time gap (one slot) between two consecutive transmissions. To avoid the LBT procedure between consecutive transmissions, the embodiments in the present disclosure provide the following solution, which is based on transmitting during the guard symbol to avoid the gap.

[0142] If the same SL UE reserves two or more consecutive slots for consecutive transmission, the SL UE may retransmit in one symbol at the end of the previous symbol, thus avoiding the gap.

[0143] If an SL UE reserves (schedules) a PSFCH transmission before the last symbol (as in FIG. 8), the initiating SL UE may indicate to the responding SL UE that it intends to transmit a PSFCH to extend its transmission into the guard symbol so that continuity of transmission into the next slot is achieved.

[0144] In different embodiments, if the initiating SL UE shares a COT with the responding SL UE, it may instruct the responding SL UE either that the initiating SL UE extends its transmission at the end of its transmission during its guard symbol, or that the responding SL UE should extend its transmission at the end of its slot during the guard symbol.

[0145] 9A shows a flowchart 900 of COT allowing SL transmission during guard symbols according to some embodiments. At operation 902, a new packet for transmission in slot N arrives at a SL UE (UE1). At operation 904, UE1 determines whether the COT is repeated in the guard symbol. If so, at operation 906, UE1 transmits in slot N repeatedly in the guard symbol of slot N. If not, at operation 908, the UE transmits in slot N using the guard symbol of slot N.

[0146] 9B illustrates a flow chart 950 for SL transmission without guard symbols conditioned by an existing subsequent reservation according to some embodiments. At operation 952, a new packet for transmission in slot N arrives at a SL UE (UE1). At operation 954, UE1 determines whether a reservation in slot N exists. If so, at operation 956, UE1 transmits in slot N with symbol repetition in the guard symbol of slot N. If not, at operation 958, the UE transmits in slot N with the guard symbol of slot N.

[0147] FIG. 10A illustrates a flow chart of a method 1000 performed by a UE for sidelink (SL) unlicensed priority of channel access and resource reservation according to some embodiments. The UE may include computer readable code or instructions executed in one or more processors of the UE. Coding of software to execute or implement the method 1000 is well within the scope of one of ordinary skill in the art in view of this disclosure. The method 1000 may include additional or fewer operations than those shown and described and may be executed or performed in a different order. The computer readable code or instructions of the software executable by one or more processors may be stored in a non-transitory computer readable medium, such as, for example, a memory of the UE.

[0148] The method 1000 begins at operation 1002, where the UE obtains a PC5 5QI (PQI). At operation 1004, the UE converts the PQI into a Channel Access Priority Class (CAPC). At operation 1006, the UE performs a Listen Before Talk (LBT) procedure based on the CAPC. At operation 1008, the UE transmits a Sidelink (SL) transmission in the unlicensed band based on the result of the LBT procedure.

[0149] In some embodiments, to obtain the PQI, the UE may obtain the PQI from a higher layer of the UE, which may be an application layer.

[0150] In some embodiments, the UE may convert the PQI to a SL priority. The UE may determine candidate SL resources in a selection window based on the SL priority. The UE may select an SL resource from the candidate SL resources for SL transmission.

[0151] In some embodiments, converting the PQI to CAPC may be based on a mapping table mapping from PQI values ​​to CAPC values. The mapping table may be pre-configured locally in the UE when the UE accesses the network or may be configured by a network device (e.g., a base station) via a control message such as an RRC. In some embodiments, the mapping table may include a first mapping from at least one of PQI values ​​of 21, 22, 23, 55, 90, or 91 to a CAPC value of 1, and a second mapping from PQI value 59 to a CAPC value of 3.

[0152] When the UE performs an LBT procedure based on CAPC, the QoS parameters in Table 2 may be used to meet the channel access requirements.

[0153] FIG. 10B illustrates a flow chart of a method 1050 performed by a UE for sidelink (SL) COT sharing according to some embodiments. The UE may include computer readable code or instructions executed in one or more processors of the UE. Coding software to execute or implement the method 1050 is well within the scope of one of ordinary skill in the art in light of this disclosure. The method 1050 may include additional or fewer operations than those shown and described and may be executed or performed in a different order. The computer readable code or software instructions executable by one or more processors may be stored in a non-transitory computer readable medium, such as, for example, a memory of the UE.

[0154] The method 1050 begins at operation 1052, where the UE starts a channel occupation time (COT) following a successful listen-before-talk (LBT) procedure. At operation 1054, the UE transmits COT information to a second UE indicating that the COT is shareable. At operation 1056, the UE transmits a sidelink (SL) transmission in an unlicensed band within the COT.

[0155] In some embodiments, to transmit COT information, the UE may transmit the COT information in sidelink control information (SCI) to the second UE.

[0156] In some embodiments, the COT information may further indicate an energy detection threshold (EDT) for sharing the COT and a remaining duration of the COT. In some embodiments, the EDT and the remaining duration of the COT may be indicated in one or more fields of the SCI format 2.

[0157] In some embodiments, the COT information may further indicate at least one of: that the first UE should extend its transmission at the end of its SL transmission into the guard symbol of the SL slot; or that the second UE should extend its second transmission into the last guard symbol of the SL slot.

[0158] In some embodiments, the first UE may receive a second transmission from the second UE, the second transmission starting during the last guard symbol of the preceding slot.

[0159] 11 illustrates an exemplary communications system 1100 according to some embodiments. In general, the system 1100 enables multiple wireless or wireline users to transmit and receive data and other content. The system 1100 may implement one or more channel access methods, such as Code Division Multiple Access (CDMA), Time Division Multiple Access (TDMA), Frequency Division Multiple Access (FDMA), Orthogonal FDMA (OFDMA), Single Carrier FDMA (SC-FDMA), or Non-Orthogonal Multiple Access (NOMA).

[0160] In this example, the communications system 1100 includes electronic devices (EDs) 1110a-1110c, radio access networks (RANs) 1120a-1120b, a core network 1130, a public switched telephone network (PSTN) 1140, the Internet 1150, and other networks 1160. Although a limited number of these components or elements are shown in FIG.

[0161] The EDs 1110a-1110c are configured to operate or communicate in the system 1100. For example, the EDs 1110a-1110c are configured to transmit or receive via wireless or wired communication channels. Each ED 1110a-1110c represents any suitable end-user device, which may include (or may be referred to as) a user equipment or device (UE), a wireless transmit or receive unit (WTRU), a mobile station, a fixed or mobile subscriber unit, a mobile phone, a personal digital assistant (PDA), a smartphone, a laptop, a computer, a touchpad, a wireless sensor, or a home electronic device.

[0162] Here, the RANs 1120a-1120b include base stations 1170a-1170b, respectively. Each base station 1170a-1170b is configured to wirelessly interface with one or more of the EDs 1110a-1110c to enable access to a core network 1130, a PSTN 1140, the Internet 1150, or other networks 1160. For example, the base stations 1170a-1170b may include (or may be) one or more of several well-known devices, such as a base transceiver station (BTS), a Node B (NodeB), an evolved Node B (eNodeB), a next generation (NG) Node B (gNB), a home Node B, a home eNodeB, a site controller, an access point (AP), or a wireless router. The EDs 1110a-1110c are configured to interface and communicate with the Internet 1150 and may access a core network 1130, a PSTN 1140, or other networks 1160.

[0163] In the embodiment shown in FIG. 11, base station 1170a forms part of the RAN 1120a, which may include other base stations, elements, or devices. Base station 1170b also forms part of the RAN 1120b, which may include other base stations, elements, and / or devices. Each base station 1170a-1170b operates to transmit or receive wireless signals within a particular geographic region or area, sometimes referred to as a "cell." In some embodiments, multiple-input multiple-output (MIMO) technology may be employed having multiple transceivers for each cell.

[0164] The base stations 1170a-1170b communicate using wireless communication links with one or more of the EDs 1110a-1110c over one or more air interfaces 1190. The air interfaces 1190 may utilize any suitable wireless access technology.

[0165] The system 1100 is believed to obtain using multiple channel access functions including such schemes as described above. In a particular embodiment, the base station and the ED implement 5G New Radio (NR), LTE, LTE-A, or LTE-B. Of course, other multiple access schemes and wireless protocols may be utilized.

[0166] The RANs 1120a-1120b are in communication with the core network 1130 to provide voice, data, application, voice over Internet Protocol (VoIP), or other services to the EDs 1110a-1110c. Of course, the RANs 1120a-1120b or the core network 1130 may communicate directly or indirectly with one or more other RANs (not shown). The core network 1130 may also serve as a gateway access for other networks (such as the PSTN 1140, the Internet 1150, and other networks 1160). In addition, some or all of the EDs 1110a-1110c may include functionality for communicating with different wireless networks using different wireless technologies or protocols over different wireless links. Instead of (or in addition to) wireless communication, the EDs may communicate with a service provider or switch (not shown) and the Internet 1150 by wired communication channels.

[0167] Although Figure 11 illustrates one example of a communications system, various changes may be made to Figure 11. For example, communications system 1100 may include any number of EDs, base stations, networks, or other components in any suitable configuration.

[0168] 12A and 12B illustrate example devices that may implement the methods and teachings of the present disclosure. In particular, FIG. 12A illustrates an example ED 1210, and FIG. 12B illustrates an example base station 1270. These components may be used in the system 1100 or in any other suitable system.

[0169] As shown in FIG. 12A, the ED 1210 includes at least one processing unit 1200. The processing unit 1200 implements various processing operations of the ED 1210. For example, the processing unit 1200 may perform signal coding, data processing, power control, input / output processing, or any other function that enables the ED 1210 to operate in the system 1100. The processing unit 1200 also supports the methods and teachings described in more detail above. Each processing unit 1200 includes any suitable processing or computing device configured to perform one or more operations. Each processing unit 1200 may include, for example, a microprocessor, a microcontroller, a digital signal processor, a field programmable gate array, or an application specific integrated circuit.

[0170] The ED 1210 also includes at least one transceiver 1202. The transceiver 1202 is configured to modulate data or other content for transmission by at least one antenna or NIC (Network Interface Controller) 1204. The transceiver 1202 is also configured to demodulate data or other content received by the at least one antenna 1204. Each transceiver 1202 includes any suitable structure for generating a signal for wireless or wired transmission or processing a wireless or wired received signal. Each antenna 1204 includes any suitable structure for transmitting or receiving a wireless or wired signal. One or more transceivers 1202 may be used in the ED 1210, and one or more antennas 1204 may be used in the ED 1210. Although shown as a single functional unit, the transceiver 1202 may also be implemented using at least one transmitter and at least one separate receiver.

[0171] The ED 1210 further includes one or more input / output devices 1206 or interfaces, such as a wired interface to the Internet 1150. The input / output devices 1206 facilitate interaction with a user or other devices in a network (network communications). Each input / output device 1206 has any suitable structure, including a network interface communications, such as a speaker, microphone, keypad, keyboard, display, or touch screen, for providing information to or receiving information from a user.

[0172] In addition, the ED 1210 includes at least one memory 1208. The memory 1208 stores instructions and data used, generated, or collected by the ED 1210. For example, the memory 1208 may store software or firmware instructions executed by the processing unit 1200 and data used to reduce or remove interference in an incoming signal. Each memory 1208 includes any suitable volatile or non-volatile storage and retrieval device. Any suitable type of memory may be used, such as a random access memory (RAM), a read-only memory (ROM), a hard disk, an optical disk, a subscriber identity module (SIM) card, a memory stick, a secure digital (SD) memory card, and the like.

[0173] As shown in FIG. 12B, the base station 1270 includes at least one processing unit 1250, at least one transceiver 1252 including transmitter and receiver functionality, one or more antennas 1256, at least one memory 1258, and one or more input / output devices or interfaces 1266. A scheduler, as understood by one skilled in the art, is coupled to the processing unit 1250. The scheduler may be included within the base station 1270 or may operate separately therefrom. The processing unit 1250 implements various processing operations of the base station 1270, such as signal coding, data processing, power control, input / output processing, or any other function. The processing unit 1250 may also support the methods and teachings described in more detail above. Each processing unit 1250 includes any suitable processing or computing device configured to perform one or more operations. Each processing unit 1250 may include, for example, a microprocessor, a microcontroller, a digital signal processor, a field programmable gate array, or an application specific integrated circuit.

[0174] Each transceiver 1252 includes any suitable structure for generating signals for wireless or wired transmission to one or more EDs or other devices. Each transceiver 1252 further includes any suitable structure for processing signals received wirelessly or wired from one or more EDs or other devices. Although illustrated combined as a transceiver 1252, the transmitter and receiver may be separate components. Each antenna 1256 includes any suitable structure for transmitting or receiving wireless or wired signals. Although a common antenna 1256 is illustrated here as being coupled to the transceiver 1252, one or more antennas 1256 may be coupled to the transceiver 1252 to permit separate antennas 1256 to be coupled to a transmitter and a receiver when mounted on separate components. Each memory 1258 includes any suitable volatile or non-volatile storage and retrieval device. Each input / output device 1266 facilitates interaction (network communication) with a user device or other devices in the network. Each input / output device 1266 includes any suitable structure for providing information to a user or receiving / providing information from a user, including a network interface communication.

[0175] 13 is a block diagram of a computing system 1300 that may be used to implement the devices and methods disclosed herein. For example, the computing system may be a UE, an access network (AN), a mobility management (MM), a session management (SM), a user plane gateway (UPGW), or any entity of an access stratum (AS). A particular device may utilize all components shown, or only a subset of components, and the level of integration may vary from device to device. Furthermore, a device may include multiple instances of components, such as multiple processing units, processors, memories, transmitters, receivers, etc. The computing system 1300 includes a processing unit 1302. The processing unit may include a central processing unit (CPU) 1314, a memory 1308, and may further include a mass storage device 1304, a video adapter 1310, and an I / O interface 1312 connected to a bus 1320.

[0176] The bus 1320 may be one or more of any type of several bus architectures including a memory bus or memory controller, a peripheral bus, or a video bus. The CPU 1314 may include any type of electronic data processor. The memory 1308 may include any type of non-transitory system memory, such as static random access memory (SRAM), dynamic random access memory (DRAM), synchronous DRAM (SDRAM), read only memory (ROM), or a combination thereof. In one embodiment, the memory 1308 may include ROM for use during startup and DRAM for storing programs and data for use during program execution.

[0177] Mass storage 1304 may include any type of non-transitory storage device configured to store data, programs, and other information and make the data, programs, and other information accessible via bus 1320. Mass storage 1304 may include, for example, one or more of a solid state drive, a hard disk drive, a magnetic disk drive, or an optical disk drive.

[0178] Video adapter 1310 and I / O interface 1312 provide an interface to couple external input and output devices to processing unit 1302. As illustrated, examples of input and output devices include a display 1318 coupled to video adapter 1310, and a mouse, keyboard, or printer 1316 coupled to I / O interface 1312. Other devices may be coupled to processing unit 1302 and additional or fewer interface cards may be utilized. For example, a serial interface such as a universal serial bus (USB) (not shown) may be used to provide an interface to external devices.

[0179] The processing unit 1302 also includes one or more network interfaces 1306, which may have a wired link, e.g., an Ethernet cable and / or a wireless link, for accessing nodes or different networks. The network interface 1306 allows the processing unit 1302 to communicate with remote units over a network. For example, the network interface 1306 may provide wireless communication with one or more transmitters / transmitting antennas and one or more receivers / receiving antennas. In one embodiment, the processing unit 1302 is coupled to a local area network 1322 or a wide area network for data processing and communication with remote devices, such as other processing units, the Internet, or remote storage facilities.

[0180] It should be understood that one or more steps of the method of the embodiments provided herein may be performed by a corresponding unit or module. Each unit or module may be hardware, software, or a combination thereof. For example, one or more of the units or modules may be an integrated circuit, such as a field programmable gate array (FPGA) or an application specific integrated circuit (ASIC).

[0181] Although the description has been set forth in detail, it should be understood that various changes, substitutions and alterations can be made therein without departing from the spirit and scope of the present disclosure, as defined by the appended claims. Moreover, the scope of the disclosure is not intended to be limited to the specific embodiments described herein. Those skilled in the art will readily appreciate from this disclosure that currently existing or to be later developed processes, machines, manufactures, compositions of matter, means, methods or steps may perform substantially the same function or achieve substantially the same result as the corresponding embodiments described herein. Accordingly, the appended claims are intended to include within their scope such processes, machines, manufactures, compositions of matter, means, methods or steps.

Claims

1. a first user equipment (UE) initiating a channel occupation time (COT) according to a successful listen-before-talk (LBT) procedure; The first UE transmitting COT information to a second UE indicating that the COT is shareable; and The first UE transmits a sidelink (SL) transmission in an unlicensed band within the COT. A method comprising:

2. The step of transmitting the COT information comprises: The first UE transmits the COT information in sidelink control information (SCI) to the second UE. The method of claim 1 , comprising:

3. The method of claim 1 , wherein the COT information further indicates an energy detection threshold (EDT) for sharing the COT and a remaining duration of the COT.

4. The method of claim 3 , wherein the remaining durations of the EDT and the COT are indicated in one or more fields of SCI Format 2.

5. The COT information further comprises: the first UE extending a transmission at the end of the SL transmission in a guard symbol of a SL slot; or The second UE should extend its second transmission into the last guard symbol of the SL slot. The method according to claim 1 , further comprising:

6. receiving a second transmission of the second UE from the first UE, the second transmission starting during the last guard symbol of a previous slot; The method of claim 1 , further comprising:

7. A user equipment (UE) acquires a PC5 5QI (PQI); the UE converting the PQI into a Channel Access Priority Class (CAPC); the UE performing a Listen Before Talk (LBT) procedure based on the CAPC; and The UE transmits a sidelink (SL) transmission in an unlicensed band based on a result of the LBT procedure. A method comprising:

8. the UE converting the PQI into an SL priority; the UE determining candidate SL resources in a selection window based on the SL priority; and the UE selecting an SL resource from the candidate SL resources for the SL transmission. The method of claim 7 further comprising:

9. The UE receiving a mapping between CAPC values ​​and SL priority levels via a Downlink Control Information (DCI) or a Radio Resource Control (RRC) configuration. The method of claim 7 further comprising:

10. The step of converting the PQI to the CAPC is based on a mapping table that maps PQI values ​​to CAPC values.

10. The method according to any one of claims 7 to 9.

11. The mapping table may include: a first mapping from at least one of the PQI values ​​of 21, 22, 23, 55, 90, or 91 to a CAPC value of 1; or A second mapping of PQI value 59 to a CAPC value of 3 The method of claim 10, comprising at least one of:

12. The step of the UE acquiring the PQI comprises: The UE obtaining the PQI from an application layer. The method of any one of claims 7 to 11, comprising:

13. A user equipment (UE), At least one processor; and A non-transitory computer readable storage medium storing programming, the programming including instructions that, when executed by the at least one processor, cause the UE to perform a method according to any one of claims 1 to 6. A UE comprising:

14. A user equipment (UE), At least one processor; and A non-transitory computer readable storage medium storing programming, the programming including instructions that, when executed by the at least one processor, cause the UE to perform a method according to any of claims 7 to 12. A UE comprising:

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