Sidelink unauthorized resource reservation

Abstract

According to an embodiment, a user equipment (UE) performs a first type of sensing within a sensing window to detect one or more first SL transmissions using sidelink (SL) radio access technology (RAT). The UE performs a second type of sensing to detect one or more second transmissions using a non-SL RAT different from the first type. Based on the first and second types of sensing, the UE selects SL resources in an unlicensed frequency band within an SL transmission selection window. The UE uses the SL RAT to transmit the SL transmissions through the SL resources.

Description

[0001] Cross-reference to related applications

[0002] This application claims priority to U.S. Provisional Patent Application No. 63 / 336,083, filed April 28, 2022, entitled “Sidelink Unlicensed Resource Reservation,” the entire contents of which are incorporated herein by reference. Technical Field

[0003] This disclosure generally relates to methods and apparatus for wireless communication, and in certain embodiments, to methods and apparatus for unlicensed resource reservation for sidelinks (SL). Background Technology

[0004] LTE introduced support for vehicle-to-vehicle (V2V) and vehicle-to-everything (V2X) services in Releases 14 and 15 to extend the 3GPP platform to the automotive industry (TR 36.885, TR 38.885). Work items (RP-152293, RP-172293) define LTE sidelinks (SL) suitable for vehicular applications and supplemental enhancements to cellular infrastructure. Examples of V2X use case scenarios include the following.

[0005] - Vehicle platooning enables vehicles to dynamically form a queue and travel together.

[0006] - Extended sensor support enables the exchange of raw or processed data collected via local sensors or real-time video images between vehicles, roadside units (RSUs), pedestrian equipment, and V2X application servers.

[0007] - Advanced driving supports semi-autonomous or fully autonomous driving.

[0008] - Remote driving enables remote drivers or V2X applications to operate remote vehicles for passengers who cannot drive themselves or for remote vehicles in hazardous environments. Summary of the Invention

[0009] The methods and apparatus for reserving unlicensed resources for sidelinks (SL) as described in the embodiments of this disclosure generally offer technical advantages.

[0010] According to an embodiment, a user equipment (UE) performs a first type of sensing within a sensing window to detect one or more first SL transmissions in an unlicensed frequency band using radio access technology (RAT). The UE performs a second type of sensing to detect one or more second transmissions in the unlicensed frequency band using a non-SL RAT different from the first type. Based on the first and second types of sensing, the UE selects SL resources in the unlicensed frequency band within an SL transmission selection window. The UE uses the SL RAT to transmit the SL transmissions through the SL resources.

[0011] In some embodiments, the non-SL RAT may include a wireless fidelity (Wi-Fi) RAT.

[0012] In some embodiments, to perform the first type of sensing, the UE receives sidelink control information (SCI); decodes the SCI; and measures reference signal received power (RSRP) based on the SCI to determine one or more first occupied resources in the unlicensed frequency band. In some embodiments, the UE may exclude the one or more first occupied resources from a resource set used for candidate selection.

[0013] In some embodiments, to perform the second type of sensing, the UE may detect a decoding failure during the execution of the first type of sensing; perform a clear channel assessment (CCA) procedure; and measure a received signal strength indicator (RSSI) during the CCA procedure to identify one or more second occupied resources in the unlicensed frequency band sensed by the CCA procedure. In some embodiments, the UE may exclude the one or more second occupied resources from the resource set used for candidate selection based on the decoding failure and the RSSI. In some embodiments, the UE may exclude the one or more second occupied resources from the resource set used for candidate selection based on the decoding failure and the RSSI being below a threshold. In some embodiments, to measure the RSSI, the UE may measure the RSSI in at least one symbol in the SL time slot or for a portion of the time of each of the at least one symbol in the SL time slot.

[0014] In some embodiments, the selection window may be no earlier than the LBT duration of the listen before talk (LBT) process.

[0015] In some embodiments, the UE can determine possible future resources that can be occupied based on the first type of perception and the second type of perception. The UE can exclude the possible future resources from the resource set used for candidate selection.

[0016] In some embodiments, the UE can determine the channel access busy ratio (CABR), which corresponds to a portion of the SL sub-channels in the SL resource pool that are occupied only by the one or more first SL transmissions or only by the one or more second transmissions. The UE can perform SL congestion control based on the CABR.

[0017] In some embodiments, the UE can determine the channel busy ratio (CBR), which corresponds to a portion of the SL sub-channels in the SL resource pool that are occupied only by the one or more first SL transmissions or only by the one or more second transmissions. The UE can perform SL congestion control based on the CBR.

[0018] In some embodiments, the UE may collect statistics on the availability of one or more resources in the unlicensed frequency band occupied by RAT transmissions. The results of these statistics are used to select at least one of preferred or non-preferred resources to be used during Inter-UE Coordination (IUC) procedures. In some embodiments, the UE may collect the RSRP of one or more symbols of the sensing window. The UE may decode the SCI. The collection of the statistics on the availability of the one or more resources may be performed when the UE fails to decode the SCI and the RSSI is greater than a threshold. Attached Figure Description

[0019] To gain a more complete understanding of this disclosure and its advantages, reference is now made to the following description taken in conjunction with the accompanying drawings, in which:

[0020] Figure 1A An exemplary communication system 100 according to an embodiment is shown;

[0021] Figure 1B Examples of SLUEs in coverage, partial coverage, and out of coverage (OOC) according to some embodiments are shown;

[0022] Figure 2 The basic sensing and resource selection timing is illustrated according to some embodiments;

[0023] Figure 3 Examples of inferring non-SL RAT transports based on some embodiments are shown;

[0024] Figure 4 An example of slot-based SL transmission according to some embodiments is shown;

[0025] Figure 5 An example of a Channel Access Busy Ratio (CABR) measurement window is shown;

[0026] Figure 6A A flowchart illustrating resource reservation for SL UE according to some embodiments is shown;

[0027] Figure 6B A flowchart is shown illustrating a method performed by a UE for SL resource reservation according to some embodiments;

[0028] Figure 7 An exemplary communication system according to some embodiments is shown;

[0029] Figure 8A and Figure 8B An exemplary device is shown that can implement the methods and teachings provided in this disclosure;

[0030] Figure 9 A block diagram of a computing system that can be used to implement the devices and methods disclosed herein, according to some embodiments, is shown.

[0031] Unless otherwise stated, corresponding numbers and symbols in the different figures generally refer to corresponding parts. The figures are drawn to clearly illustrate relevant aspects of the embodiments and are therefore not necessarily drawn to scale. Detailed Implementation

[0032] The following section discusses in detail the making and use of embodiments of this disclosure. However, it should be understood that the concepts disclosed herein can be embodied in a wide range of specific contexts, and the specific embodiments discussed herein are merely illustrative and not intended to limit the scope of the claims. Furthermore, it should be understood that various changes, substitutions, and modifications can be made to this document without departing from the spirit and scope of this disclosure as defined by the appended claims.

[0033] Figure 1AAn exemplary communication system 100 according to an embodiment is illustrated. The communication system 100 includes an access node 110 that serves user equipment (UE), such as UE 120, having a coverage area 101. In a first operating mode, 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 connecting to the Internet, performing operations and management, etc. In a second operating mode, communication to and from the UE does not pass through the access node 110; however, the access node 110 typically allocates resources for communication by the UE when certain conditions are met. Communication between a pair of UEs 120 can use a sidelink connection (shown as two separate unidirectional connections 125). Figure 1A In this context, sidelink communication occurs between two UEs operating within coverage area 101. However, sidelink communication can also typically occur when both UEs 120 are outside coverage area 101; both UEs are within coverage area 101; or one UE is within coverage area 101 and the other is outside. Communication between the UE and the access node pair is conducted via a unidirectional communication link, where the communication link between the UE and the access node is called the uplink 130, and the communication link between the access node and the UE is called the downlink 135.

[0034] Access nodes are also commonly referred to as NodeB, evolved NodeB (eNB), next generation (NG) NodeB (gNB), master eNB (MeNB), secondary eNB (SeNB), master gNB (MgNB), secondary gNB (SgNB), network controller, control node, base station, access point, transmission point (TP), transmission-reception point (TRP), cell, carrier, macro cell, femtocell, picocell, etc., while UEs are also commonly referred to as mobile stations, mobile terminals, terminals, users, subscribers, sites, etc. Access nodes can provide wireless access according to one or more wireless communication protocols, such as 3GPP Long Term Evolution (LTE), LTE Advanced (LTE-A), 5G, 5G LTE, 5G NR, Sixth Generation (6G), High Speed ​​Packet Access (HSPA), and IEEE 802.11 series standards, such as 802.11a / b / g / n / ac / ad / ax / ay / be, etc. While it is understood that a communication system could employ multiple access nodes capable of communicating with multiple UEs, for simplicity, only one access node and two UEs are shown.

[0035] Within the Technical Specification Group (TSG) radioaccess network (RAN), TR 37.885 and TR 38.913 define a set of corresponding 5G RAN requirements, channel models, and other specifications for the new radio (NR).

[0036] Although NR sidelinks were initially developed for V2X applications, there is a growing industry focus on extending their applicability to commercial use cases. Two requirements have been identified for commercial sidelink applications:

[0037] -(1) Increased side link data rate;

[0038] -(2) Support for new carrier frequencies for side links.

[0039] The increased sidelink data rate is driven by applications such as sensor information (e.g., video) sharing between vehicles with high levels of driving automation. Commercial use cases may demand data rates exceeding those required in Rel-17. This increased data rate can be achieved by supporting sidelink carrier aggregation and sidelinks on unlicensed spectrum. Furthermore, enhanced data rates can be supported more efficiently on FR2 by improving frequency range 2 (FR2) sidelink operation. While support for new carrier frequencies and larger bandwidths can also improve sidelink data rates, the primary benefit comes from making sidelinks more suitable for a wider range of applications. More specifically, with support for unlicensed spectrum and enhancements to FR2, sidelinks are likely to be implemented in commercial equipment, as the use of the Intelligent Transport System (ITS) band is limited to ITS safety-related applications.

[0040] 3GPP defines two resource allocation modes for sidelinks: Mode 1 and Mode 2 (TR 38.885).

[0041] In Mode 1, the base station schedules one or more SL resources for the UE to use for SL transmission. In Mode 1 (NR Uu link), the base station can allocate NR SL resources for: (i) licensed carriers shared between NR Uu and NR SL (PC5 link); (ii) dedicated NR SL carriers. Mode 1 can be used within coverage area but not outside coverage area. Resource allocation Mode 1 (within coverage area) supports the following technologies:

[0042] -Dynamic resource allocation;

[0043] - Configure authorization type 1 and type 2.

[0044] In Mode 2, the UE determines (i.e., the base station does not schedule) one or more SL transmission resources within the SL resources configured by the base station / network or pre-configured SL resources. Mode 2 can be used both within and outside coverage (OOC).

[0045] The definition of SL resource allocation mode 2 includes:

[0046] (a) The UE autonomously selects SL resources for transmission;

[0047] (b) The UE assists one or more other UEs in selecting SL resources, which may be a part of (a), (c), or (d);

[0048] (c) The UE is configured with SL transport grant (type 1, etc.) configured by NR;

[0049] (d) The UE schedules the SL transmission of other UEs.

[0050] Resource allocation mode 2 supports the processes of sensing and (re)selecting resources.

[0051] Figure 1B Examples of SL UEs in coverage, partial coverage, and out-of-coverage (OOC) according to some embodiments are shown. UE 151a is within the coverage of gNB 161. UE 151a and gNB 161 can communicate with each other via the Uu interface. UE 151b is within the coverage of road side unit (RSU) 162 and RSU 163, and can communicate with RSU 162 and / or RSU 163 via the PC5 interface. UE 151c is within the coverage of RSU 163.

[0052] UE 152a, UE 152b, and UE 152c are OOC SL UEs. Additionally, UE 153 is within partial coverage. UEs can communicate with each other using the PC5 interface (e.g., between UE 151a and UE 151b).

[0053] Each transport block (TB) has an associated sidelink control information (SCI) message. The SCI is divided into two phases: Phase 1 SCI, carried on the Physical Sidelink Control Channel (PSCCH); and Phase 2 SCI, carried on the Physical Sidelink Shared Channel (PSSCH).

[0054] The PSCCH can carry SCI. The source UE uses the SCI to schedule data transmission on the PSSCH or to reserve resources for data transmission on the PSSCH. The SCI can transmit time and frequency resources of the PSSCH and / or parameters of the hybrid automatic repeat request (HARQ) procedure, such as redundancy version, procedure ID, new data indicator, and / or resources of the Physical Sidelink Feedback Channel (PSFCH). The time and frequency resources of the PSSCH can be referred to as resource allocation and can be indicated in the time resource allocation field and / or frequency resource allocation field (i.e., resource location). The PSFCH carries HARQ feedback from the UE, which is the intended recipient of the PSSCH transmission, to the UE performing the transmission via the sidelink.

[0055] HARQ feedback is called HARQ-ACK. HARQ-ACK carries either ack or nack, indicating whether the destination UE has correctly decoded the payload carried on the PSSCH. The SCI can also carry bit fields indicating or identifying the source UE. Additionally, the SCI can carry bit fields indicating or identifying the destination UE. The SCI can also include other fields to carry information, such as the modulation and coding scheme used to encode the payload and modulate the encoded payload bits, the demodulation reference signal (DMRS) mode, antenna port, payload (transmission) priority, etc. The sensing UE performs sidelink sensing (i.e., receives PSSCHs sent by other UEs) and decodes the SCI carried in the PSSCH to obtain information on resources reserved by other UEs, determining the resources for sidelink transmission by the sensing UE.

[0056] The perception process is defined as decoding SCI and / or SL measurements from other UEs. Decoding one or more SCIs during this process provides at least information about the SL resources indicated by the UE sending the SCI. When decoding the corresponding SCI, the perception process uses L1 SL RSRP measurements based on SL DMRS. The considered resource (re)selection process uses the results of the perception process to determine one or more resources for SL transmission.

[0057] Figure 2 The basic sensing and resource selection timing is illustrated according to some embodiments. proc,0 T is the time required for the UE to complete the perception process. proc,1 It is the maximum time required for the UE to identify candidate resources and select new sidelink resources.

[0058] During perception window 202, the SL UE decodes one or more SCIs from other UEs and performs SL measurements. The information provided in Phase 1 of the SCI format carried in PSSCH (SCI Format 1-A) (TS 38.212) is as follows:

[0059] - Priority—The three digits specified in Clause 5.4.3.3 (12, TS23.287) and Clause 5.22.1.3.1 (8, TS 38.321). The value “000” in the “Priority” field corresponds to the priority value “1”, the value “001” in the “Priority” field corresponds to the priority value “2”, and so on.

[0060] The lower the priority value, the higher the priority; the higher the priority value, the lower the priority.

[0061] - Frequency resource allocation;

[0062] - Time resource allocation;

[0063] -Resource reservation period;

[0064] -DMRS mode;

[0065] - Phase 2 SCI format; and / or

[0066] - Number of DMRS ports, Modulation Coding Scheme (MCS).

[0067] For SL PC5, priority level values ​​are provided by the upper layer. A quality of service (QoS) model similar to that defined for the Uu reference point in TS23.501 is used, based on the PC5 QoS Indicator (PQI) value. Table 1 shows the correspondence between priority levels and PQI values.

[0068] Table 1 (Normalized PQI to QoS Feature Mapping)

[0069]

[0070]

[0071] -Note 1: For the standardized PQI to QoS feature mapping, this table will be expanded / updated to support the service requirements of other identified V2X services.

[0072] Note 2: PQI can be used for services other than V2X.

[0073] -Note 3: PQI can be used with application-indicated priorities to override the default priority level of PQI.

[0074] Priority levels are used to select which PC5 service data are prioritized for QoS requirements, so that PC5 service data packets with a priority level value of N take precedence over PC5 service data packets with higher priority level values ​​(i.e., N+1, N+2, etc.). Lower numbers indicate higher priorities.

[0075] The PC5 priority level (also known as SL reservation priority, data priority (where data priority defines reservation priority) or SL priority) provided in SCI is used to determine the subset of resources to be reported to higher layers in PSSCH resource selection in sidelink resource allocation mode 2 (TS 38.214).

[0076] To trigger this process, the higher layer provides the following parameters for the PSSCH / PSCCH transmission in time slot n:

[0077] - The resource pool to be reported;

[0078] -L1 priority, prio TX ;

[0079] - Remaining package delay budget;

[0080] - The number of sub-channels used for PSSCH / PSCCH transmission in a time slot, L subCH ;

[0081] -Optionally, resource reservation interval P rsvp_TX , in milliseconds.

[0082] - If the higher layer requests the UE to determine a subset of resources as part of a reassessment or preemption process, the higher layer will select resources from that subset for PSSCH / PSCCH transmission. The higher layer will provide a set of resources that may be reassessed (r0,r1,r2,...) and a set of resources that may be preempted (r0',r1',r2',...).

[0083] - Determined by the UE in time slot r i "-A subset of resources requested by higher layers before or after T3, where r" i "T3 is the slot with the smallest slot index among (r0,r1,r2,...) and (r0',r1',r2',...), and T3 equals..." in Defined in the time slots in Table 2, where μ SL This is the subcarrier spacing (SCS) configuration of the SL BWP.

[0084] Table 2 Depends on subcarrier spacing

[0085]

[0086] - Optionally, an instruction for one or more resource selection mechanisms (such as allowedResourceSelectionConfig) may include fully aware only, partially aware only, random resource selection only, or any one or more combinations thereof.

[0087] During the sensing process, the monitoring UE detects the SCI transmitted in each SL time slot within the sensing window 202 and measures the reference signal received power (RSRP) of the resource indicated in the SCI. The monitoring UE can also receive data transmissions simultaneously with sensing (i.e., it is also a receiving UE). For periodic services, i.e., resource reservations for sidelink transmission, if the UE occupies time slot s... k If the UE uses the resources on the s, then the UE will also occupy the time slot s. k +q*RRI m Resources on, where q is an integer, RRI m It is the UE detected by the sensing UE. m Resource reservation interval. Detection includes the steps of receiving and decoding the PSCCH and processing the SCI within the PSCCH.

[0088] For non-periodic or dynamic transmissions, the sending UE reserves multiple resources and indicates the next resource in the SCI. Therefore, based on the sensing results, the monitoring UE can determine which resources it may occupy in the future, and if the measured RSRP on the occupied resources during the sensing period is greater than the RSRP threshold, it can avoid using those resources for its own transmission.

[0089] When in Figure 2 When resource selection is triggered in time slot n, it is based on the perception result in perception window 202 (i.e., in time slot [n–T0, n–T)). proc,0 On the [n+T1, n+T2] slot, the UE selects the resource in the resource selection window 204 (i.e., on the slot [n+T1, n+T2]), where

[0090] T0: The number of time slots with a defined value for the resource pool configuration;

[0091] T proc,0 The time required for the UE to complete the perception process;

[0092] T1: Processing time required for candidate resource identification and resource selection, T1≤T proc,1 ;

[0093] T2: The last time slot of the resource pool used for resource selection, which is reserved for the UE implementation, but in [T 2min, Within the range of PDB], where T 2min It is the minimum value of T2. PDB represents the packet delay budget, which is the remaining time for the UE to send data packets.

[0094] T proc,1 The maximum time required for a UE to identify candidate resources and select a new sidelink resource.

[0095] To select resources, the transmitting UE needs to identify candidate resources by excluding those with occupied RSRPs exceeding the configured RSRP threshold. The transmitting UE then compares the ratio of available resources to all resources in selection window 204.

[0096] If the available resource ratio is greater than the threshold X%, the UE randomly selects a resource from the candidate resources.

[0097] The SL priority level is used to determine the available resource ratio, as shown below. If the ratio is low, the transmitting UE then increases the RSRP threshold by 3dB and checks the available resource ratio until it is equal to or greater than X%, where X is selected from the list sl-TxPercentageList according to TS38.214, and its value is determined by the data priority (SL priority level):

[0098] sl-TxPercentageList: Given a prio TX The internal parameter X is defined as sl-TxPercentageList(prio) which converts percentages to ratios. TX ).

[0099] According to TS38.331 below, the possible values ​​of X in sl-TxPercentageList are 20, 35, and 50 (corresponding to 20%, 35%, and 50%, respectively):

[0100]

[0101]

[0102] SL resource selection is performed in two steps. In the first step, the UE monitoring and awareness window 202 in the shared spectrum (SL-U) is used, and a candidate resource list is constructed 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 the upper layer. In the second step, the upper layer selects the selected resource from the candidate resource list, and the selected resource list is provided to the PHY layer.

[0103] It is worth noting that, in Figure 2 In the selection window 204 definition, the selection of T1 depends on the UE's... The implementation method below.

[0104] The set S for candidate selection A It is initialized as a set of all candidate single-slot resources.

[0105] If the UE meets all of the following conditions, it should be removed from set S. A Exclude any candidate single-slot resource R x,y :

[0106] -UE has no monitoring slots

[0107] - For any periodic value allowed by the high-level parameter sl-ResourceReservePeriodList and in time slots The received SCI format 1-A is assumed, where the “Resource Reservation Period” field is set to the periodic value and indicates all sub-channels of the resource pool in the time slot, which overlaps with the existing reservations in selection window 204.

[0108] Congestion control in SL is used to limit access and avoid potential conflicts. Two metrics are defined in TS 38.215 for this purpose.

[0109] - Channel Busy Ratio (CBR): Measured in slot n, it is defined as a portion of the sub-channels in the resource pool whose SLRSSI measured by the UE exceeds a (pre-)configured threshold sensed on the CBR measurement window [na, n-1].

[0110] - Channel Occupancy Ratio (CR): Evaluated at time slot n, it is defined as the total number of sub-channels used for transmission in time slot [na,n-1] and licensed in time slot [n,n+b] divided by the total number of sub-channels configured in the transmission pool on [na,n+b].

[0111] Through IE SL-CBR-PriorityTxConfigList, the higher layer uses the index of the configuration provided in sl-CBR-PSSCH-TxConfigList to indicate the mapping between sets of PSSCH transmission parameters (e.g., MCS, PRB number, retransmission count, CR limit), and uses the index of the CBR range configuration entry in sl-CBR-RangeConfigList to indicate the CBR range and the priority range.

[0112] Therefore, CR and CBR are used for:

[0113] - Select the number of HARQ retransmissions from the allowed number, if the allowed number is configured by RRC, then in sl-MaxTxTransNumPSSCH included in sl-PSSCH-TxConfigList; if the allowed number is configured by RRC, then in sl-CBR-PriorityTxConfigList indicated by sl-MaxTxTransNumPSSCH, to obtain the highest priority of one or more logical channels allowed on the carrier and the CBR measured by the lower layer;

[0114] - Select the number of frequency resources within the range. If the range is configured by RRC, then between sl-MinSubChannelNumPSSCH and sl-MaxSubchannelNumPSSCH included in sl-PSSCH-TxConfigList; if the range is configured by RRC, then between MinSubChannelNumPSSCH and MaxSubchannelNumPSSCH indicated in sl-CBR-PriorityTxConfigList, to obtain the highest priority of one or more logical channels allowed on the carrier and the CBR measured by the lower layer.

[0115] - Select an MCS within the range (if configured). If the range is configured by RRC, it overlaps between sl-MinMCS-PSSCH and sl-MaxMCS-PSSCH associated with the selected MCS table included in sl-PSSCH-TxConfigList; if the range is configured by RRC, it overlaps between sl-MinMCS-PSSCH and sl-MaxMCS-PSSCH associated with the selected MCS table indicated in sl-CBR-PriorityTxConfigList to obtain the highest priority of one or more sidelink logical channels in the MAC PDU and the CBR measured by the lower layer.

[0116] Congestion control for each transmission pool is defined as follows:

[0117] Step 1: Configuration parameters are in place. Note: Parameters can be pre-configured or received via the network.

[0118] Step 2: Receive upper-layer packets with the associated Prose Per Packet Priority (PPPP) of each packet in the proximity service.

[0119] Step 3: Determine the PDB of the data packet with the PPPP value according to the configuration.

[0120] Step 4: Calculate the current CBR.

[0121] Step 5: Calculate the CR limit of the PPPP based on CBR.

[0122] Step 6: Select a sending resource for the data packet to satisfy the CR limit.

[0123] The CR limits corresponding to the CBR measurement range are defined in Table 3 as follows.

[0124] Table 3

[0125]

[0126] Inter-UE coordination (IUC) is part of the SL design to address hidden node issues and half-duplex constraints. For IUC, three categories of resources are defined.

[0127] - One or more preferred resources do not include one or more resources that overlap with one or more reserved resources indicated by SCI Format 1-A whose RSRP measurement is above the RSRP threshold (i.e., resources reserved by SCI whose RSRP is below the RSRP threshold).

[0128] -Non-preferred resources include:

[0129] ○Resources that the UE should receive on these resources due to half-duplex operation; or

[0130] ○ Resources indicated by SCI Format 1-A that satisfy at least one of the following:

[0131] ■ The RSRP measurement performed on the received content (SCI format 1-A) exceeds a certain threshold Th(prio_RX), where prio_RX is the value of the priority field in the received content (SCI format 1-A); or

[0132] ■The UE is the destination UE of the TB associated with the received content (SCI format 1-A) and the RSRP measurement performed on the received content (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).

[0133] Note 1: The set of one or more preferred and non-preferred resources is different for the transmitter and receiver because they reflect the local view.

[0134] Note 2: It is assumed that UE-A's transmission reservation has been known to UE-B and excluded from the selection window.

[0135] - Conflicting Resources:

[0136] ○ Reserve overlap through the second strong SCI > Th(prio2,prio1), where prio2 and prio1 are in the received SCI;

[0137] ○The UE is the destination reserved twice |RSRP1-RSRP2| > (pre-)configured threshold;

[0138] ○ Reservation for overlap with half-duplex scenarios.

[0139] NR channel access under shared spectrum

[0140] Unlicensed spectrum (also known as unlicensed spectrum) has attracted significant interest from cellular operators. LTE-licensed assisted access (LAA) 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).

[0141] 3GPP and IEEE technologies operating in unlicensed spectrum use a listen-before-talk (LBT) channel access. In some regions, such as the EU and Japan, LBT rules are enforced by spectrum regulators to reduce interference risks and provide a fair coexistence mechanism. The LBT mechanism requires transmitters to check if the channel is occupied before transmission; if so, transmission is postponed.

[0142] Specifically, the LBT rules for EUs in ETSI EN 301.893 for the 5GHz band use Clear Channel Assessment (CCA) to determine whether a channel is available for transmission. CCA checks if the received energy exceeds a threshold. If the energy exceeds the CCA threshold, the channel is considered to be in use (busy); otherwise, the channel is considered idle. If the channel is idle, the transmitter can transmit for the duration of the channel occupancy time (COT) within the bandwidth, for example, at least 80% of the total channel bandwidth. ETSI EN 301.893 also specifies the maximum COT (MCOT) duration for transmission bursts. The maximum COT duration adopted in 3GPP NR-URel 16 (TS 37.213) is a function of the channel access priority class (CAPC). As defined in TS 37.213, when determining channel occupancy time (COT), if the transmission gap is less than or equal to 25 µs, the duration of that gap is included in the channel occupancy time. A transmission burst is defined as a group of transmissions with a gap of no more than 16 µs; if the gap is greater than 16 µs, these transmissions are considered independent.

[0143] 3GPP (TS 37.213) defines several channel access types for downlink (DL) and uplink (UL).

[0144] Type 1 UL Channel Access Procedure

[0145] This clause describes the UE's channel access procedure, where the duration spanned by the sensing slots that are perceived to be idle before one or more UL transmissions is random. This clause applies to the following transmissions:

[0146] -eNB / gNB schedules or configures one or more PUSCH / SRS transfers; or

[0147] -gNB schedules or configures one or more PUCCH transmissions; or

[0148] - One or more transmissions associated with the random access procedure.

[0149] The channel was first perceived to have a delay of T. dAfter being idle for the duration of the time slot, and after the counter N reaches zero in step 4, the UE can use the Type 1 channel access procedure to transmit. The counter N is adjusted by sensing one or more additional time slot durations of the channel, according to the steps described below.

[0150] (1) Set N = N init , where N init It is in 0 and CW p Once a random number is uniformly distributed between the given numbers, proceed to step 4.

[0151] (2) If N > 0 and the UE chooses to decrease the counter, then set N = N - 1;

[0152] (3) Sensing the additional time slot duration of the channel. If the additional time slot duration is idle, proceed to step 4; otherwise, proceed to step 5.

[0153] (4) If N = 0, stop; otherwise, go to step 2;

[0154] (5) Sensing the channel until the additional delay time T d A busy time slot was detected, or an additional delay duration T was detected. d All time slots are in an idle state;

[0155] (6) If the additional delay time T d If the channel is detected to be idle within all time slot durations, proceed to step 4; otherwise, proceed to step 5.

[0156] If the UE has not yet transmitted a UL transmission on the channel on which one or more UL transmissions were performed after step 4 in the above process, the UE may transmit a transmission on that channel, provided that when the UE is ready to transmit the transmission, at least for the sensing time slot duration T. sl The system detects that the channel is idle, and the delay T immediately preceding the transmission... d The UE detects that the channel is idle for the entire duration of the time slot. If the UE first detects the channel after being ready to transmit, the detection time slot duration T... sl The channel is not yet perceived to be idle, or if the delay T immediately preceding the expected transmission... d If the UE has not detected that the channel is idle within any sensing time slot duration, then the UE will remain idle for a delay duration T. d After detecting that the channel is in an idle state within the time slot duration, proceed to step 1.

[0157] Delay duration T d Including m that followed p The duration T of a consecutive time slot f=16us, where the duration of each time slot is T sl =9us, and T f Including T f Initial idle time slot duration T sl .

[0158] CW min,p ≤CW p ≤CW max,p It's a competitive window. CW p The adjustment is described in Clause 4.2.2.

[0159] CW min,p and CW max,p It was selected before step 1 of the above process.

[0160] m p CW min,p and CW max,p Based on the channel access priority level p for sending signal notifications to the UE as shown in Table 4.

[0161] Table 4: CAPC for UL

[0162]

[0163] Type 2 UL Channel Access Procedure

[0164] This clause describes the UE's channel access procedure, in which the duration spanned by the sensing slots that are perceived to be in an idle state before one or more UL transmissions is deterministic.

[0165] If the eNB instructs the UE to perform a Type 2 UL channel access procedure, the UE shall follow the procedure described in the following clause (“Type 2 AUL channel access procedure”).

[0166] Type 2A UL Channel Access Procedure

[0167] If the UE is instructed to perform a Type 2A UL channel access procedure, the UE will use the Type 2A UL channel access procedure for UL transmission. The UE can perform UL transmissions if it is aware of the channel for at least a sensing interval T. short_ul = This transmission will be sent immediately after the device has been idle for 25µs. T short_ul Including the duration T of the following sensing time slot f =16us, and T f Including T f The initial perception time slot. If T short_ul If two sensing time slots are detected to be in an idle state, then the channel is considered to be in T. short_ul The internal storage is currently idle.

[0168] Type 2B UL Channel Access Procedure

[0169] If the UE is instructed to perform a Type 2B UL channel access procedure, the UE will use the Type 2B UL channel access procedure for UL transmission. The UE can detect when the channel is in T... f =The transmission will be sent immediately after the device has been idle for 16µs. T f Included in T f The sensing time slots occur within the last 9 µs. If the channel is sensed to be idle for a total of at least 5 µs, with at least 4 µs of the sensed time slots occurring within the sensing time slots, then the channel is considered to be idle for duration T. f The internal storage is currently idle.

[0170] Type 2C UL Channel Access Procedure

[0171] If the UE is instructed to perform a Type 2C UL channel access procedure for a UL transmission, the UE will not be aware of the channel prior to the transmission. The maximum duration of the corresponding UL transmission is 584µs.

[0172] Type 1DL channel access is used before starting a new COT, where the COT duration can be up to 10ms, depending on the service priority.

[0173] Type 2DL channel access includes a deterministic duration of channel awareness, where the channel needs to be perceived as being in an idle state.

[0174] - If the channel is detected to be idle within a sensing interval of at least 25 µs before transmission, then Type 2A channel access is permitted to transmit.

[0175] - If the channel is detected to be idle within a sensing interval of at least 16 µs before transmission, then Type 2B channel access is permitted to transmit.

[0176] - If channel awareness is not performed before transmission and the duration does not exceed 584µs, then Type 2C channel access is permitted for transmission.

[0177] Type 2A DL channel access procedure is applicable to shared COT after UE transmission, as well as transmissions that include discovery bursts with a duration of up to 1 ms and a duty cycle of up to 1 / 20.

[0178] Type 2B or Type 2C DL channel access procedures are applicable to one or more subsequent transmissions performed by the UE after a gap of 16µs or at most 16µs during shared channel occupancy.

[0179] Similar to DL access channel types, in UL channel access, Type 1 UL access is based on the perception that the channel is idle for a delay duration Td and a random backoff counter N (as in Type 1A DL). Type 2 UL includes a deterministic duration of idle channel before transmission. Type 2A UL includes a channel idle for at least 25µs. Type 2B UL includes a channel idle for at least 16µs. Type 2C performs a transmission of up to 584µs without perception.

[0180] There is currently no sidelink specification for shared spectrum (SL-U) in the system. SL-U is expected to follow the NR-U channel access specified in TS 37.213. Furthermore, SL-U is expected to reuse SL resource allocation methods as much as possible.

[0181] The SL resource selection specification does not consider the necessary LBT (channel assessment, CA) before transmission, nor does it consider the situation where LBT fails before transmission, thus preventing transmission from being performed.

[0182] In this disclosure, the term SL-U UE can be used to identify a sidelink UE operating in unlicensed (shared) spectrum. More precisely, embodiments of this disclosure identify and address the technical limitations of LBT on SL resource selection and reservation, the impact of external interference and transmission (specific to shared spectrum) on SL resource selection, and the impact of external interference on congestion control used in SL.

[0183] In Mode 2, the SL-U UE autonomously selects the resources used for transmission and can assist other SL-U UEs in their resource selection (e.g., using inter-UE coordination (IUC)). In this mode, the upper layer provides the CAPC value of the channel access priority used in the adaptive channel access mechanism to the lower layer.

[0184] First, regarding the use of CAPC and SL priorities, they are used for different purposes and have different time scales.

[0185] CAPC is used to determine the maximum duration of the COT for LBT sensing. For the 5 GHz band, the timing of LBT (based on the CAPC value) is very short, approximately tens to no more than a few hundred microseconds, which may be equivalent to the duration of one or several OFDM symbols. For example, when the CAPC value = 1, the LBT duration (when successful) corresponds to the sensing slot duration (9 µs) plus the backoff period duration (between 3 x 9 µs and 7 x 9 µs), which is less than 73 µs. Subcarrier spacing values ​​of {15, 30, 60, 120} kHz correspond to OFDM symbol durations of {66.7, 33.3, 16.7, 8.33} µs.

[0186] The purpose of SL resource reservation is to reserve resources for future transmissions. It should be noted that these reservations are made only within SL resources (a subset of UL resources) and are only decoded and complied with by SL UE devices, which can decode sidelink control information (SCI). The reservation method is specified by 3GPP protocols and is followed only by 3GPP devices implementing this feature. However, channel access (based on CAPC) is mandatory for any type of device operating in the EU 5GHz unlicensed band (and therefore non-3GPP) and is specified by ETSI.

[0187] The duration of the SL resource reservation window is much longer than that of the channel access LBT; the SL sensing window 202 is as long as 100ms, while the duration of the resource selection window 204 is T2-T1 (for example, in...). Figure 2 (In the context of the time interval), where T1 can be as low as zero, and the minimum value of T2 includes {1,5,10,20}*2^mu time slots, where the mu value {0,1,2,3} corresponds to the SCS value of {15,30,60,120} kHz. This results in a duration equal to {1,5,10,20} ms.

[0188] The main difference between licensed spectrum and shared spectrum (or unlicensed spectrum) is that in shared spectrum, out-of-network transmissions are possible. These transmissions may occur under different Radio Access Technologies (RATs) and therefore may not be decoded. Therefore, during the SL Awareness Window 202, some transmissions (e.g., Wi-Fi) may occur, and the SL-U UE may not be able to decode the transmissions or measure the corresponding RSRP. This situation may affect how the candidate list is constructed. Unlicensed spectrum / bands can be spectrum / bands used for Wi-Fi, Bluetooth, or NR-U (e.g., 5 unlicensed bands, 6 GHz spectrum, etc.).

[0189] Another difference is that the LBT process can be initiated before transmission, which may affect latency.

[0190] In one embodiment, T in window 204 is selected. proc,1 (It can be zero now) cannot be less than (minimum or maximum) LBT duration.

[0191] Before transmission can proceed, an LBT (Local Level-By) process may need to be performed. In another embodiment, this could trigger a re-evaluation of resource selection if the LBT fails.

[0192] In some embodiments, another way to handle LBT failure is to allow multiple resource selections (reservations) for the same transmission. In this case, if the LBT is successful, the SL-U UE can cancel (cancel) future reservations via SCI. For example, bits in SCI format 1-A can indicate the cancellation of all (or a limited number) future reservations corresponding to the resource reservation period, making these resources available for other SL-U UEs to select. Future reservations can only be cancelled after the receiver acknowledges the completion of the transmission. This process is expected to be used more for unicast communications, but it can also be applied to multicast communications. For example, future retransmissions can be cancelled when a minimum number of acknowledgments (HARQ ACK / NACK) are received.

[0193] In some embodiments, where multiple reserved resources exist for retransmission, an LBT failure will only trigger a re-evaluation process for resource selection if all LBTs fail before transmission and retransmission reservations.

[0194] LBT failures can be an important measure that can be used for resource selection and reservation.

[0195] In one embodiment, if an SL UE observes (determines) a consistent LBT failure on a resource set (frequency channel, time slot, periodic resource, etc.), those resources can be excluded from the resource selection set or considered for selection of resources with lower priority. In some embodiments, these resources can be considered as non-preferred resources in the inter-UE coordination process.

[0196] For example, consistent LBT failures on certain resources can be defined when the number of LBT failures on those resources exceeds a certain (pre-)configured threshold during the most recent past observation (measurement) window. The observation window can be a single (pre-configured) window, equal to a (pre-configured) sensing or resource selection window, equal to a multiple of a (pre-configured) sensing or resource selection window or other functions, or equal to the maximum or minimum sensing or resource selection window or a multiple thereof.

[0197] In some embodiments, if the number of successful LBT processes on certain resources in the recent observation window exceeds a threshold, these resources may be considered for resource selection with higher priority, or these resources may be considered as part of a preferred resource list in the IUC process.

[0198] In some embodiments, the SL-U UE is able to monitor the received signal energy indication (RSSI) in each symbol of the time slot during the sensing window 202. When the RSSI is high but the SL-U UE cannot decode the SCI, the SL-U UE determines that a non-SL RAT transmission has been received. Figure 3In this context, there is no non-SL RAT (e.g., Wi-Fi). The Uu link between gNB 302 and UE 304 is non-SL. However, transmissions between gNB 302 and UE 304, which is controlled by gNB 302, do not interfere with SL transmissions between UE 304 and UE 306, which operate in a subset of UL time slots. There is no PC5 link between gNB and UE. However, a PC5 link can be used between roadside unit (RSU) and UE. Non-SL RAT transmissions can be any RAT transmission other than SL-RAT transmissions, such as Wi-Fi transmissions, Bluetooth transmissions, NR-U transmissions, etc.

[0199] In one embodiment, the SL-U UE monitors the sensing window 202 and collects the RSSI for each time slot (symbol), decodes the SCI (if any), and measures the RSRP (if possible). If the SL-U UE fails to decode the SCI, but the measured RSSI is greater than a (pre-)configured threshold (e.g., CABR_Threshold, which will be described in detail below), the UE will collect (long-term) statistics on the availability of one or more resources in the unlicensed band / spectrum (over time) for further use in selecting preferred and / or non-preferred resources that can be used during Inter-UE Coordination (IUC) procedures. For example, resources continuously occupied by other RAT transmissions can be defined as non-preferred resources and sent to other UEs during the IUC procedure.

[0200] In some embodiments, the statistical data is used by the SL-U UE for resource selection in unlicensed frequency bands / spectrums. For example, if a resource is occasionally occupied by other RAT transmissions (or is simply strong noise), it can be used as a selected resource for future reservation. However, if the same resource is consistently occupied by other RAT transmissions (or noise), it can be excluded from the list of selected resources. These other RATs can be one or more RATs in the unlicensed frequency band that are different from the SL unlicensed transmissions. For example, these other RATs may include Wi-Fi, NR-U, Bluetooth, etc.

[0201] Furthermore, no candidate corresponding to any periodic value allowed by higher-level parameters within the resource reservation period of the assumed SCI format 1-A received in that time slot will be excluded from the potential candidate list.

[0202] The UE may or may not need to perform LBT before transmitting on reserved resources or without reservations.

[0203] Examples of transmissions that may not require the LBT (channel-aware) process:

[0204] - If a short control transmission exists (with a short duration as specified in the 3GPP NR-U and ETSI BRAN specifications) (Type 2C);

[0205] - If the shared COT memory is a transfer that immediately follows other transfers within the same COT.

[0206] It should be noted that SL transmission is time-slot based. According to some embodiments, examples of this transmission are found in... Figure 4 (respectively in the side link synchronization signal / physical broadcast channel block (S-SSB) and PSSCH).

[0207] Figure 4 Two examples of traditional SL time slots are shown. Time slot 402 shows the S-SSB time slot format, and time slot 404 shows the SL data (PSCCH and PSSCH) time slot format. Figure 4 In this context, the SL time slot (e.g., time slot 402 or 404) ends with a guard symbol, during which no transmission occurs. Therefore, it appears that there is always a gap (one time slot) between two consecutive transmissions. To avoid LBT between consecutive transmissions, embodiments of this disclosure provide schemes based on transmitting during the guard symbol period to avoid the gap.

[0208] When the same SL UE reserves two or more consecutive time slots for continuous transmission, the SL UE can retransmit one of the previous symbols in the last symbol, thus avoiding gaps.

[0209] When the SL UE reserves (schedules) PSFCH transmission before the last symbol (e.g.) Figure 4 As shown, the initiating SL UE can instruct the responding SL UE that it will send PSFCH during the protection symbol period to extend its transmission, thereby achieving continuity of transmission to the next time slot.

[0210] In another embodiment, for the same scenario, the initiating SL UE can also instruct that the protection symbols between PSSCH and PSFCH be filled with some duplicates, so the responder does not need to perform LBT.

[0211] In some embodiments, when the SL UE initiating the COT shares the COT with the responding SL UE, it can instruct the responding SL UE to extend its transmission at the end of its transmission during its protection symbol period, or the responding SL UE should extend its transmission at the end of its time slot during its protection symbol period.

[0212] However, in some embodiments, instead of the initiating or COT initiating UE extending the transmission during the protection symbol period, the receiving or responding UE can start its transmission with a symbol earlier to avoid performing LBT.

[0213] Examples of transmissions that may require the LBT (channel-aware) process:

[0214] - When the transmission requires initiating a COT (Type 1);

[0215] - When transmitting within a shared COT, there is a gap relative to previous transmissions (e.g., Type 1, Type 2A, Type 2B);

[0216] If the LBT fails before transmission, transmission will be impossible. In this case, the SL UE waits for the next transmission opportunity. The next transmission opportunity can be the next resource reservation (which can be a periodic reservation or a retransmission reservation) or a dynamic transmission opportunity (which does not require reservation).

[0217] As mentioned above, CBR and CR are important measures for congestion management and transmission parameter selection. CBR and CR definitions assume that the only transmission occurring is an SL (Single-Level) transmission. However, this is not the case in shared spectrum, where other RAT (Random Access Request) transmissions, such as Wi-Fi, can be received. These off-network RAT transmissions can negatively impact the parameter selection for further transmissions.

[0218] This disclosure provides a technical solution for distinguishing strong signals (energy) received from SL-U transmission and non-SL-U transmission.

[0219] To identify non-SL RAT transmissions, the SL UE can observe the SL resource pool.

[0220] This disclosure distinguishes between several situations:

[0221] (1) SL transmission is identified (e.g., by decoding SCI).

[0222] (2) SL transmissions are not identified and the energy received in the channel (e.g., non-SL RSSI) is low.

[0223] (3) SL transmissions are not recognized and the received energy (e.g., non-SL RSSI) is high.

[0224] For case (3), observing the SL UE leads to the conclusion that there are non-SL RAT transmissions. That is, even the resource pool is allocated to SL transmissions there, rather than to SL devices that transmit within those resources.

[0225] In the above scenario, this disclosure identifies two parts. The first part is identifying the SL transmission, which can be achieved by monitoring only the first two symbols of the time slot. The second part is measuring the received non-SL RSSI, which is done when a non-SL transmission is present. This received non-SL RSSI is not an SL RSSI; the SL RSSI is measured based on the SL RS intensity.

[0226] Received non-SL RSSIs can be measured in several ways. For example, they can be measured only in the first two symbols, and the entire time slot can be determined as an opportunity to be removed from the SL pool based on their values. Another option is to measure the non-SL RSSIs in each time slot symbol and determine whether there is a non-SL RAT transmission in that time slot. Yet another option is to measure the RSSIs in a subset of symbols in the time slot, or to measure the RSSIs only in specific symbols (e.g., guard symbols).

[0227] SL decoding and non-SL RSSI measurements of the channel can be performed at the same symbol or in consecutive symbols.

[0228] One objective of embodiments of this disclosure is to identify non-SL RAT transmissions (which are considered to consume resources) and exclude them from congestion control measures.

[0229] Therefore, embodiments of this disclosure provide two thresholds and define additional metrics for CBR.

[0230] More precisely, embodiments of this disclosure exclude time slots or resources occupied by transmissions other than the SL UE RAT, such as Wi-Fi, from the CBR metric. The newly described metric, called Channel Access Busy Ratio (CABR), corresponds to a portion of the SL subchannels in the resource pool where SL transmissions or non-SL transmissions exist, where the RSSI is below CABR_Threshold. The threshold required for this metric can be (pre-)configured. This threshold can be the same as or different from the energy detection threshold (EDT) required for previous LBT transmissions.

[0231] New measurements from the CABR can be configured, requested, and reported to one or more higher layers of the gNB or SL-U UE for channel statistics and resource selection, such as as a non-preferred resource.

[0232] The measurement window of CABR can be the same as or different from that of CBR. For example... Figure 5 As shown, for example, the measurement (observation) window is 100ms.

[0233] Based on the same technology, new metrics (indicators) for CR can be defined for unlicensed SL deployments.

[0234] In one embodiment, the existing CR and CBR definitions are modified to exclude those resources that are "damaged" by other RAT transmissions or strong noise.

[0235] For example, the definition of CR in TS 38.215

[0236] The sidelink channel occupancy ratio (SLCR), evaluated at time slot n, is defined as the total number of subchannels used for transmission in time slot [na,n-1] and licensed in time slot [n,n+b] divided by the total number of subchannels configured in the transmission pool on [na,n+b].

[0237] It can be changed to

[0238] Sidelink Channel Occupancy Ratio (SL CR), evaluated at time slot n, is defined as the total number of subchannels used for transmission in time slot [na, n-1], where the number of subchannels that receive SL transmissions or whose average non-SL RSSI is less than CABR_Threshold and are licensed in time slot [n, n+b] is divided by the total number of subchannels configured in the transmission pool on [na, n+b], where the number of subchannels that receive SL transmissions or whose average non-SL RSSI is less than CABR_Threshold.

[0239] Without changing the CR definition, the SL CR metric might incorrectly count transmissions from other RATs in a shared channel as unused (empty) resources. For example, if 20% of the slots in the [na,n-1] slot interval are occupied by other RATs (non-SLUE RATs), it means there are no SL UE transmissions in those 20% of resources; however, according to the existing definition, they would be counted as unused SL slots, resulting in a smaller CR. If the CR is inaccurate, resource allocation may be overly aggressive, which could conflict with other RAT transmissions (e.g., Wi-Fi). Therefore, these non-SL UE RAT transmission slots should be removed from the count in the CR definition.

[0240] In some embodiments, new metrics can be defined based on the foregoing notes. Embodiments of this disclosure define a new metric, CR-U (CR Unlicensed), where CR-U is evaluated at time slot n and is defined as the total number of subchannels used for transmission in time slot [na, n-1] and licensed in time slot [n, n+b] divided by the total number of subchannels configured in the transmission pool on [na, n+b], excluding time slots occupied by non-SLRAT transmissions.

[0241] As mentioned above, the time slots occupied by non-SL RAT transmissions can be defined as those time slots where the non-SL RSSI is higher than CABR_Threshold and the SL-U UE decodes the transmission as SL transmission failure.

[0242] Similar to CR, an example of CBR definition is as follows:

[0243] SL Channel Busy Ratio (SL CBR), measured in time slot n, is defined as a portion of subchannels in the resource pool whose SL RSSI measured by the UE exceeds a (pre-)configured threshold sensed on the CBR measurement window [na, n-1], where a equals 100 or 100.2 according to the higher-layer parameter sl-TimeWindowSizeCBR. μ Each time slot. When the UE is used to perform partial awareness through higher layers (including when SL DRX is configured), SL RSSI is measured in the time slots during which the UE performs partial awareness and in the time slots during which the UE performs PSCCH / PSSCH reception within the CBR measurement window. The calculation of SL CBR is limited to the time slots during which SL RSSI is measured. If the number of SL RSSI measurement time slots within the CBR measurement window is less than a (pre-)configured threshold, the (pre-)configured SL CBR value is used.

[0244] It can be changed to

[0245] SL Channel Busy Ratio (SL CBR), measured in time slot n, is defined as a portion of subchannels in the resource pool whose SL RSSI measured by the UE exceeds a (pre-)configured threshold sensed on the CBR measurement window [na, n-1], where a equals 100 or 100.2 according to the higher-layer parameter sl-TimeWindowSizeCBR. μ There are several time slots. The resource pool is defined as the pool of resources that perform SL transmissions or receive non-SL RSSI values ​​less than CABR_Threshold. When the UE performs partial awareness through higher layers (including when SL DRX is configured), SL RSSI is measured in the time slots during which the UE performs partial awareness and in the time slots during which the UE performs PSCCH / PSSCH reception within the CBR measurement window. The calculation of SL CBR is limited to the time slots during which SL RSSI is measured. If the number of SL RSSI measurement time slots within the CBR measurement window is less than a (pre-)configured threshold, the (pre-)configured SL CBR value is used.

[0246] The existing definition of SL CBR may contain the same bias. SL CBR may be inaccurate if it considers a proportion (partial) relative to the SL resource pool, without considering resources occupied by non-SL. Therefore, resources occupied by other types of transport (non-SL) can be excluded.

[0247] CABR and CR-U are calculated over a (pre-)configured time window of the selected SL resource, such as over the perception window 202 and / or the selection window 204.

[0248] In one embodiment, the newly defined CR-U metric / indicator is used to update the CR table defined above, wherein the CR limit value is replaced with the CR-U limit value and resource allocation is performed using the new limit.

[0249] The IUC of SL-U should take into account the use of the newly defined channel occupancy index and long-term statistics on the resources occupied by other RAT transmissions.

[0250] During the IUC process, the preferred resource list does not include resources that overlap with one or more reserved resources indicated by SCI Format 1-A whose received RSRP measurement is higher than the RSRP threshold.

[0251] In one embodiment, in addition to the above, preferred resources may also exclude resources corresponding to non-SL RAT transmissions that satisfy certain long-term statistical data constraints.

[0252] For example, preferred resources can exclude those resources where non-SLRAT transmissions are detected with an average non-SL RSSI greater than a preferred non-SL RSSI threshold, where the threshold can be (pre-)configured. This threshold can be the same as or different from CABR_Threshold.

[0253] Furthermore, in one embodiment, for conditions already defined in the specification, resources identified as satisfying some long-term statistical constraints for non-SL RAT transmissions can be added to the non-preferred resource set. For example, such long-term statistical data could be a condition that the average non-SL RSSI is greater than a non-preferred non-SL RSSI threshold, which could be (predefined).

[0254] For conflicting resources, the list may include those resources reserved for the future that will overlap with some non-preferred resources identified based on long-term statistics of non-SL RSSI from received non-SL RAT transmissions.

[0255] In some embodiments, resources can be sorted with different priorities based on the number of non-SL RAT transmissions observed during the observation window (occurrence frequency) and / or the non-SL RSSI received for such transmissions, and these priorities can be used for resource selection.

[0256] For example, if the non-SL RSSI used for non-SL transmission is greater than threshold 1, then the resource has a very low priority in resource selection; if the non-SL RSSI used for non-SL transmission is greater than threshold 2 and less than threshold 1, then these resources have a medium priority in resource selection, and so on. For example, these thresholds can be (pre-)configured by the gNB.

[0257] The above concepts can be directly extended to partial sensing and periodic partial sensing, for which a new non-SL RSSI threshold is defined for use in long-term statistical data calculations.

[0258] All of the above measurements and statistics can be reported to the gNB upon request or when certain conditions are met. For example, if the CABR or CR-U metric becomes higher or lower than certain thresholds.

[0259] Furthermore, in some embodiments, the SL UE can track and measure resources occupied by non-SL transmissions and report these resources by request or triggered by certain events. The configuration used to obtain these measurements and statistics (e.g., collection window, symbol and resource set, or threshold for non-SL RSSI) can be (pre-)configured.

[0260] Non-SL RSSI measurements can be performed in various ways. In one approach, the measurement is implemented in a manner similar to channel sensing during LBT. For example, 9µs of sensing slots (Ts) are used in the 5GHz band. For instance, NL-SLRSSI measurements can be performed at the beginning of each symbol for a duration of multiple sensing slots (Ts). The so-called sensing slots Ts are much shorter than the duration of an OFDM symbol, and obviously much shorter than the duration of an NR slot (14 OFDM symbols). However, in some embodiments, non-SL RSSI measurements can be performed continuously for multiple sensing slots (Ts) at any point during the OFDM slots, where their positions can be uniformly distributed, or at the end of the slots, or left to be implemented.

[0261] As described in this disclosure, the UE may need to perform an LBT procedure before transmission. During the LBT procedure, channel busy may be detected (e.g., the LBT awareness procedure is described in TS 37.213, as above). When channel busy is detected or transmission is available, the UE performing the LBT procedure can collect this information and include it in long-term statistics associated with SL resource pool availability. In other words, the non-SL RSSI measurement defined above is not only... Figure 2 It is collected in the perception window 202 used for resource pool evaluation, and also in the selection window 204 where the transmission will take place.

[0262] Figure 6AA flowchart 600 illustrating resource reservation for an SL UE according to some embodiments is shown. At operation 601, the UE measures the RSSI within a (pre-)configured window. At operation 602, the UE determines whether the SCI can be decoded. If yes, at operation 603, one or more resources are counted as occupied by SL-U RAT transmissions. If no, at operation 604, the UE determines whether the measured RSSI is greater than a CBAR threshold. If the measured RSSI is greater than the CBAR threshold, at operation 605, one or more resources are counted as occupied by non-SL-U RAT transmissions; otherwise, at operation 606, the resources are counted as unused.

[0263] Figure 6B A flowchart of method 650 executed by a UE for SL resource reservation according to some embodiments is shown. The UE may include computer-readable code or instructions that execute on one or more processors of the UE. Those skilled in the art will understand that this disclosure can decode the software used to implement or perform method 650. Method 650 may include more 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 the memory of the UE.

[0264] Method 650 begins at operation 652, where the UE performs a first type of sensing within a sensing window to detect one or more first SL transmissions in an unlicensed frequency band using sidelink (SL) radio access technology (RAT). At operation 654, the UE performs a second type of sensing to detect one or more second transmissions in the unlicensed frequency band using a non-SL RAT different from the first type. At operation 656, based on the first and second types of sensing, the UE selects an SL resource in the unlicensed frequency band within an SL transmission selection window. At operation 658, the UE uses the SL RAT to transmit an SL transmission via the SL resource.

[0265] In some embodiments, non-SL RATs may include wireless fidelity (Wi-Fi) RATs.

[0266] In some embodiments, to perform the first type of sensing, the UE receives sidelink control information (SCI); decodes the SCI; and measures the reference signal received power (RSRP) based on the SCI to determine one or more first occupied resources in the unlicensed frequency band. In some embodiments, the UE may exclude one or more first occupied resources from the resource set used to select SL resources.

[0267] In some embodiments, to perform the second type of sensing, the UE may detect a decoding failure during the first type of sensing; perform a clear channel assessment (CCA) procedure; and measure the received signal strength indicator (RSSI) during the CCA procedure to identify one or more second occupied resources in the unlicensed frequency band sensed by the CCA procedure. In some embodiments, the UE may exclude one or more second occupied resources from a resource set used for candidate selection based on decoding failure and RSSI. The resource set used to select SL resources may be a set of candidate resources or a list of candidate resources. In some embodiments, the UE may exclude one or more second occupied resources from the resource set used for candidate selection based on decoding failure and RSSI being below a threshold. In some embodiments, to measure RSSI, the UE may measure RSSI in at least one symbol in the SL time slot or for a portion of the time in each symbol of at least one symbol in the SL time slot.

[0268] In some embodiments, the selection window may be no earlier than the LBT duration of the listen before talk (LBT) process.

[0269] In some embodiments, the UE can determine possible future resources that can be occupied based on a first type of perception and a second type of perception. The UE can exclude possible future resources from the resource set used for candidate selection.

[0270] In some embodiments, the UE can determine the channel access busy ratio (CABR), which corresponds to a portion of the SL sub-channels in the SL resource pool that are occupied by only one or more first SL transmissions or only one or more second SL transmissions. The UE can perform SL congestion control based on the CABR.

[0271] In some embodiments, the UE can determine the channel busy ratio (CBR), which corresponds to a portion of the SL sub-channels in the SL resource pool that are occupied by only one or more first SL transmissions or only one or more second SL transmissions. The UE can perform SL congestion control based on the CBR.

[0272] In some embodiments, the UE may collect statistics on the availability of resources occupied by RAT transmissions. The results of these statistics are used to select at least one of preferred and non-preferred resources to be used during the IUC process. In some embodiments, the UE may collect the RSRP of one or more symbols of the sensing window. The UE may decode the SCI. The collection of statistics on the availability of one or more resources may be performed when the UE fails to decode the SCI and the RSSI is greater than a threshold.

[0273] Figure 7 An exemplary communication system 700 is illustrated. Typically, system 700 enables multiple wireless or wired users to send and receive data and other content. System 700 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).

[0274] In this example, the communication system 700 includes electronic devices (EDs) 710a-710c, radio access networks (RANs) 720a-720b, a core network 730, a public switched telephone network (PSTN) 740, the Internet 750, and other networks 760. Although Figure 7 A specific number of these components or elements are shown, but the system 700 may include any number of these components or elements.

[0275] ED 710a-710c are used for operation or communication in system 700. For example, ED 710a-710c are used for transmitting or receiving via wireless or wired communication channels. ED 710a-710c respectively represent any suitable end-user equipment and may include (or be referred to as) devices such as: user equipment (UE), wireless transmit or receive unit (WTRU), mobile station, fixed or mobile subscriber unit, cellular phone, personal digital assistant (PDA), smartphone, laptop computer, computer, touchpad, wireless sensor, or consumer electronics device.

[0276] RAN 720a-720b here includes base stations 770a-770b. Base stations 770a-770b are used to establish wireless connections with one or more EDs (Electronic Devices) among EDs 710a-710c, enabling access to the core network 730, PSTN 740, Internet 750, or other networks 760. For example, base stations 770a-770b may include (or) one or more well-known devices, such as a base transceiver station (BTS), Node-B (NodeB), evolved NodeB (eNodeB), next-generation (NG) NodeB (gNB), home NodeB, home eNodeB, site controller, access point (AP), or wireless router. EDs 710a-710c are used for connection and communication with the Internet 750 and can access the core network 730, PSTN 740, or other networks 760.

[0277] exist Figure 7 In the illustrated embodiment, base station 770a forms part of RAN 720a, which may include other base stations, components, or devices. Similarly, base station 770b forms part of RAN 720b, which may include other base stations, components, or devices. Base stations 770a-770b are respectively used to transmit or receive radio signals within a specific geographical area or region (sometimes referred to as a "cell"). In some embodiments, multiple-input multiple-output (MIMO) technology may be used to enable each cell to have multiple transceivers.

[0278] Base stations 770a-770b communicate with one or more EDs 710a-710c via one or more air interfaces 790 using a wireless communication link. Air interface 790 can use any suitable wireless access technology.

[0279] It is conceivable that System 700 can use multi-channel access capabilities, including the schemes described above. In specific embodiments, the base station and ED implement 5G New Radio (NR), LTE, LTE-A, or LTE-B. Of course, other multiple access schemes and radio protocols can also be used.

[0280] RANs 720a-720b communicate with the core network 730 to provide voice, data, application, Voice over Internet Protocol (VoIP), or other services to EDs 710a-710c. It is understood that RANs 720a-720b or the core network 730 can communicate directly or indirectly with one or more other RANs (not shown). The core network 730 can also serve as a gateway for other networks (e.g., PSTN 740, Internet 750, and other networks 760). Furthermore, some or all of the EDs in EDs 710a-710c can communicate with different wireless networks via different wireless links using different wireless technologies or protocols. EDs can communicate with service providers or switches (not shown) and Internet 750 via wired communication channels, rather than wirelessly (or otherwise).

[0281] Although Figure 7 An example of a communication system is shown, but it is possible to... Figure 7 Various modifications can be made. For example, in any suitable configuration, the communication system 700 can include any number of EDs, base stations, networks, or other components.

[0282] Figure 8A and Figure 8B Exemplary devices are shown that can implement the methods and teachings provided in this disclosure. Specifically, Figure 8A An exemplary ED 810 is shown. Figure 8B An exemplary base station 870 is shown. These components can be used in system 700 or any other suitable system.

[0283] like Figure 8AAs shown, ED 810 includes at least one processing unit 800. The processing unit 800 implements various processing operations of ED 810. For example, the processing unit 800 can perform signal encoding, data processing, power control, input / output processing, or any other function that enables ED 810 to operate in system 700. The processing unit 800 also supports the methods and teachings described in detail above. Each processing unit 800 includes any suitable processing device or computing device for performing one or more operations. Each processing unit 800 may include a microprocessor, microcontroller, digital signal processor, field-programmable gate array, or application-specific integrated circuit, etc.

[0284] ED 810 also includes at least one transceiver 802. Transceiver 802 is used to modulate data or other content for transmission via at least one antenna or network interface controller (NIC) 804. Transceiver 802 is also used to demodulate data or other content received via at least one antenna 804. Each transceiver 802 includes any suitable structure for generating signals for wireless or wired transmission, or for processing signals for wireless or wired reception. Each antenna 804 includes any suitable structure for transmitting or receiving wireless or wired signals. One or more transceivers 802 and one or more antennas 804 may be used in ED 810. Although transceiver 802 is shown as a single functional unit, it can also be implemented using at least one transmitter and at least one separate receiver.

[0285] ED 810 also includes one or more input / output devices 806 or interfaces (e.g., a wired interface to the Internet 750). Input / output devices 806 facilitate interaction with users or other devices on the network (network communication). Each input / output device 806 includes any suitable structure for providing or receiving information from a user, such as a speaker, microphone, keypad, keyboard, display, or touchscreen, including network interface communication.

[0286] In addition, ED 810 includes at least one memory 808. Memory 808 stores instructions and data used, generated, or collected by ED 810. For example, memory 808 may store software or firmware instructions executed by one or more processing units 800, as well as data for reducing or eliminating interference in incoming signals. Each memory 808 includes any suitable one or more volatile or non-volatile storage and retrieval devices. Any suitable type of memory can be used, such as random access memory (RAM), read-only memory (ROM), hard disk, optical disk, subscriber identity module (SIM) card, memory stick, secure digital (SD) card, etc.

[0287] like Figure 8B As shown, base station 870 includes at least one processing unit 850, at least one transceiver 852 (including transmitter and receiver functions), one or more antennas 856, at least one memory 858, and one or more input / output devices or interfaces 866. A scheduler, as will be understood by those skilled in the art, is coupled to processing unit 850. The scheduler may be included within base station 870 or operate independently of the base station. Processing unit 850 implements various processing operations of base station 870, such as signal encoding, data processing, power control, input / output processing, or any other functions. Processing unit 850 may also support the methods and teachings described in detail above. Each processing unit 850 includes any suitable processing or computing device for performing one or more operations. Each processing unit 850 may include a microprocessor, microcontroller, digital signal processor, field-programmable gate array, or application-specific integrated circuit, etc.

[0288] Each transceiver 852 includes any suitable structure for generating signals to transmit wirelessly or wiredly to one or more EDs or other devices. Each transceiver 852 also includes any suitable structure for processing signals received wirelessly or wiredly from one or more EDs or other devices. Although shown as a combined transceiver 852, the transmitter and receiver may also be separate components. Each antenna 856 includes any suitable structure for transmitting or receiving wireless or wired signals. Although a shared antenna 856 is shown herein coupled to transceiver 852, one or more antennas 856 may be coupled to one or more transceivers 852, thus supporting separate antennas 856 coupled to transmitters and receivers (when the transmitter and receiver are separate components). Each memory 858 includes any suitable one or more volatile or non-volatile storage and retrieval devices. Each input / output device 866 facilitates interaction with users or other devices in the network (network communication). Each input / output device 866 includes any suitable structure for providing information to or receiving / from a user, including network interface communication.

[0289] Figure 9 This is a block diagram of a computing system 900, which can be used to implement the devices and methods disclosed herein. For example, the computing system can be any entity of a UE, access network (AN), mobility management (MM), session management (SM), user plane gateway (UPGW), or access stratum (AS). A particular device may use all of the components shown or only a subset of the components, and the level of integration will vary from device to device. Furthermore, the device may include multiple instances of components, such as multiple processing units, processors, memories, transmitters, receivers, etc. The computing system 900 includes a processing unit 902. The processing unit includes a central processing unit (CPU) 914, a memory 908, and may also include a mass storage 904 connected to a bus 920, a video adapter 910, and an I / O interface 912.

[0290] Bus 920 can be one or more of several bus architectures of any type, including a memory bus or memory controller, a peripheral bus, or a video bus. CPU 914 can include any type of electronic data processor. Memory 908 can 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 combinations thereof. In one embodiment, memory 908 can include ROM for use at boot time and DRAM for storing programs and data for use during program execution.

[0291] Mass storage 904 may include any type of non-transitory storage device for storing data, programs, and other information, and allows access to the data, programs, and other information via bus 920. Mass storage 904 may include one or more of solid-state drives, hard disk drives, disk drives, or optical disk drives.

[0292] Video adapter 910 and I / O interface 912 provide interfaces for coupling external input and output devices to processing unit 902. As shown, examples of input and output devices include a display 918 coupled to video adapter 910 and a mouse, keyboard, or printer 916 coupled to I / O interface 912. Other devices may be coupled to processing unit 902, and more or fewer interface cards may be used. For example, a serial interface such as Universal Serial Bus (USB) (not shown) may be used to provide interfaces for external devices.

[0293] The processing unit 902 also includes one or more network interfaces 906, which may include wired links such as Ethernet cables to access nodes or different networks, or wireless links. The network interface 906 enables the processing unit 902 to communicate with remote units over a network. For example, the network interface 906 may provide wireless communication via one or more transmitter / transmit antennas and one or more receiver / receive antennas. In one embodiment, the processing unit 902 is coupled to a local area network 922 or a wide area network for data processing and communication with remote devices (e.g., other processing units, the Internet, or remote storage facilities).

[0294] It should be understood that one or more steps in the methods of the embodiments provided herein can be performed by corresponding units or modules. The corresponding units / modules can be hardware, software, or a combination thereof. For example, one or more of these units or modules can be integrated circuits, such as field-programmable gate arrays (FPGAs) or application-specific integrated circuits (ASICs).

[0295] Although the specification has been described in detail, it should be understood that various changes, substitutions, and modifications can be made without departing from the spirit and scope of this disclosure as defined by the appended claims. Furthermore, the scope of this disclosure is not intended to be limited to the specific embodiments described herein, and as will be readily understood by those skilled in the art from this disclosure, processes, machines, articles of manufacture, compositions of matter, components, methods, or steps (existing or to be developed in the future) can perform substantially the same functions or produce substantially the same results as the corresponding embodiments described herein. Therefore, the appended claims are intended to encompass such processes, machines, articles of manufacture, compositions of matter, modules, methods, or steps within their scope.

Claims

1. A communication method, characterized in that, include: User equipment (UE) performs first-type sensing within the sensing window to detect one or more first SL transmissions in the unlicensed frequency band using side-link SL radio access technology (RAT). The UE performs a second type of sensing to detect one or more second transmissions in the unlicensed frequency band using a non-SL RAT that is different from the first type; Based on the first type of perception and the second type of perception, the UE selects SL resources in the unlicensed frequency band in the SL transmission selection window; The UE uses the SL RAT to send the SL transmission through the SL resources.

2. The method according to claim 1, characterized in that, The non-SL RAT includes Wireless Fidelity Wi-Fi RAT.

3. The method according to claim 1 or 2, characterized in that, The execution of the first type of perception includes: The UE receives the line link control information (SCI) on the receiving side. The UE decodes the SCI; The UE determines one or more first occupied resources in the unlicensed frequency band based on the SCI measurement reference signal received power RSRP.

4. The method according to claim 3, characterized in that, Also includes: The UE excludes the one or more first occupied resources from the resource set used for candidate selection.

5. The method according to any one of claims 1 to 4, characterized in that, The execution of the second type of perception includes: The UE detects a decoding failure during the execution of the first type of perception; The UE performs the Free Channel Assessment (CCA) procedure. The UE measures Received Signal Strength Indication (RSSI) during the CCA process to identify one or more second occupied resources in the unlicensed frequency bands sensed by the CCA process.

6. The method according to claim 5, characterized in that, Also includes: The UE excludes one or more second occupied resources from the resource set used for candidate selection based on the decoding failure and the RSSI.

7. The method according to claim 5, characterized in that, The measurement of the RSSI includes: The UE measures the RSSI during at least one symbol in the SL time slot or during a portion of the time of each of the at least one symbol in the SL time slot.

8. The method according to any one of claims 1 to 7, characterized in that, The selection window is no earlier than the LBT duration of the Listen-The-After LBT process.

9. The method according to any one of claims 1 to 8, characterized in that, Also includes: The UE determines the possible future resources that can be occupied based on the first type of perception and the second type of perception; The UE excludes the possible future resources from the resource set used for candidate selection.

10. The method according to any one of claims 1 to 9, characterized in that, Also includes: The UE determines the Channel Access Busy Rate (CABR), and the CABR corresponds to a portion of the SL sub-channels in the SL resource pool that are occupied only by the one or more first SL transmissions or only by the one or more second transmissions. The UE performs SL congestion control based on the CABR.

11. The method according to any one of claims 1 to 10, characterized in that, Also includes: The UE determines the Channel Busy Rate (CBR), and the CBR corresponds to a portion of the SL sub-channels in the SL resource pool that are occupied only by the one or more first SL transmissions or only by the one or more second transmissions. The UE performs SL congestion control based on the CBR.

12. The method according to any one of claims 1 to 11, characterized in that, Also includes: The UE collects statistics on the availability of one or more resources in the unlicensed frequency band occupied by RAT transmissions. The results of these statistics are used to select at least one of preferred or non-preferred resources to be used in the IUC coordination process between UEs.

13. The method according to claim 12, characterized in that, Also includes: The UE collects the RSRP of one or more symbols of the sensing window; The UE decodes the SCI. The collection of statistics on the availability of the resources is performed when the UE fails to decode the SCI and the RSSI is greater than a threshold, wherein the RSSI is measured during the CCA procedure.

14. A user equipment (UE), characterized in that, include: At least one processor; A non-transient computer-readable storage medium storing a program, the program comprising instructions that, when executed by the at least one processor, cause the UE to perform the method according to any one of claims 1 to 13.

15. A non-transient computer-readable medium, characterized in that, The non-transient computer-readable medium stores instructions that, when executed by a user equipment (UE), cause the UE to perform the method according to any one of claims 1 to 13.

Images