Method and apparatus for sidelink communication over a license-exempt frequency band

Abstract

The present disclosure provides methods and apparatuses for sidelink (SL) communication in a license-exempt band. In one novel aspect, a combination of a SL resource selection procedure and a listen-before-talk (LBT) procedure is used for resource selection in a license-exempt band. In one embodiment, the LBT procedure is performed after the SL resource selection procedure. In one embodiment, a candidate resource selected by the SL resource selection procedure is configured to have an oversubscription resource size that is greater than or equal to a resource size required for SL data transmission and reception. In another embodiment, the oversubscription resource size is dynamically determined based on one or more preconfigured conditions including a LBT failure probability, channel load status information, and channel congestion control information. In yet another embodiment, the candidate resource is a multi-continuous slot (MCSt) resource having a plurality of contiguous resource blocks configured.

Description

Technical Field

[0001] This invention relates generally to wireless communication. In particular, it relates to sidelink communication over an unlicensed frequency band. Background Technology

[0002] Unless otherwise stated, the methods described in this section are not considered prior art to the claims listed below, nor are they considered prior art by virtue of their inclusion in this section.

[0003] Sidelink (SL) communication was introduced to enable direct transmission between two user equipments (UEs), also known as device-to-device (D2D) communication. With the progress of 3GPP specification work, the application scenarios of sidelink have been expanded to include UE-to-network relay, public safety, and vehicle-to-everything (V2X) communication. The crucial role of sidelink in Long Term Evolution (LTE) and New Radio (NR) makes it an essential remedy for supporting various use cases of future wireless communications.

[0004] To meet the increasing demand for wireless data, the use of unlicensed spectrum in the wireless industry to improve the capacity of future wireless communication systems has attracted considerable attention. Utilizing unlicensed spectrum for sidelink communication is considered the most promising direction for its further development. However, some radio access technologies (RATs), such as NR-U communication and Wi-Fi, already operate in unlicensed spectrum. One of the most critical issues in allowing sidelink communication to operate in unlicensed spectrum is ensuring its fair and harmonious coexistence with other RATs.

[0005] Therefore, it is necessary to improve the allocation of sidelink resources in unlicensed frequency bands to ensure harmonious coexistence with other RATs. Summary of the Invention

[0006] The following summary is illustrative only and is not intended to be limiting in any way. That is, it is provided to introduce the concepts, key points, benefits, and advantageous effects of the novel and non-obvious techniques described herein. Selected embodiments are further described in the detailed description below. Therefore, the following summary is not intended to identify the essential features of the claimed subject matter, nor is it intended to define the scope of the claimed subject matter.

[0007] This invention provides apparatus and method for sidelink resource selection in unlicensed frequency bands. In one novel aspect, a combination of a SL resource selection process and a Listen-Before-Speak (LBT, also known as a "pre-transmit search") process is used for resource selection in unlicensed frequency bands. In one embodiment, the LBT process executes after the SL resource selection process. In one embodiment, candidate resources selected by the SL resource selection process are configured with an oversubscribed resource size greater than or equal to the resource size required for SL data transmission and reception. In another embodiment, the oversubscribed resource size is dynamically determined based on one or more pre-configured conditions including LBT failure probability, channel load state information, and channel congestion control information. In yet another embodiment, the candidate resources are multi-contiguous time slot (MCSt) resources with a configured plurality of contiguous resource blocks. In one embodiment, type 1 LBT is configured when LBT is performed outside of Channel Occupied Time (COT) or when LBT starts / initializes COT, and type 2A, type 2B, or type 2C LBT is configured when LBT is performed within COT. In another embodiment, one or more configuration parameters are dynamically configured, including the maximum number of resources to be configured, the maximum number of resources indicated by the Level 1 side-link channel information (SCI), and the LBT trigger time. In one embodiment, a selection window is configured, wherein the SL resource selection process is executed within the selection window, and the listen-before-speak process is executed before the selected candidate resource for transmission and reception on that side-link is triggered in the start time slot n, wherein the start time slot of the selection window is time slot n plus processing time T1, and the transmission time slot of the selection window is time slot n plus packet delay budget (PDB). In yet another embodiment, a new selection window is dynamically configured when an LBT process failure is detected before the end of the selection window. In one embodiment, the SL resource selection process excludes one or more candidate resources in the selection window based on predetermined rules. Attached Figure Description

[0008] The accompanying drawings are provided to further illustrate the invention and are incorporated in and constitute a part of this invention. The drawings depict embodiments of the invention and, together with the description, serve to explain the principles of the invention. It is understood that, in order to clearly illustrate the concepts of the invention, the drawings are not necessarily drawn to scale, and some components shown may be depicted at a scale greater than that in the actual embodiments.

[0009] Figure 1A This is a schematic system diagram of an example wireless network for sidelink data communication with other coexisting RATs in an unlicensed frequency band, as described in an embodiment of the present invention.

[0010] Figure 1B An exemplary flowchart of on-side link communication using LBT sensing and selection of unlicensed spectrum is described in accordance with embodiments of the present invention.

[0011] Figure 2 An exemplary flowchart for SL resource selection based on predetermined rules for excluding some candidate resources is described in an embodiment of the present invention.

[0012] Figure 3 An example diagram for determining the LBT type is described according to an embodiment of the present invention.

[0013] Figure 4 An example diagram for determining the LBT configuration is described according to an embodiment of the present invention.

[0014] Figure 5 An example diagram of a configurable number of selected candidate resources for sidelink transceiver in an unlicensed frequency band is described according to an embodiment of the present invention.

[0015] Figure 6 An example diagram illustrating the configurable position of a new selection window is described according to an embodiment of the present invention.

[0016] Figure 7 An example diagram of dynamic configuration for SL resource selection based on configuration or predetermined conditions is described in an embodiment of the present invention.

[0017] Figure 8 An exemplary flowchart for resource selection for sidelink communication in an unlicensed frequency band is described in accordance with embodiments of the present invention. Detailed Implementation

[0018] Reference will now be made in detail to some embodiments of the invention, examples of which are shown in the accompanying drawings.

[0019] Figure 1AThis is a schematic system diagram of an example wireless network for sidelink data communication with other coexisting RATs in an unlicensed frequency band, as described in embodiments of the present invention. Wireless network 100 includes multiple communication devices or mobile stations, such as user equipment (UEs) 111, 112, 113, 114, and 115, which are configured with sidelinks in an unlicensed frequency band. Exemplary mobile devices in wireless network 100 have sidelink capabilities. Sidelink communication involves direct communication between terminal nodes or UEs without data traversing the network. For example, UE 113 communicates directly with UE 114 without a link to a network element. The range of sidelink transmission also supports UE-to-network relay to extend the service range of an eNB, where the UE acts as a relay node between the eNB and UEs outside the coverage area. For example, UE 112 is connected to base station 101 via an access link. UE 112 provides network access to UE 111 outside the coverage area via sidelink relay. Base stations such as base station 101 may also be referred to as access points, access terminals, base stations, Node Bs, enhanced Node Bs (eNBs), gNBs, or other terms used in the art. Networks can be homogeneous or heterogeneous, and can be deployed on the same frequency or different frequencies. Base station 101 is an exemplary base station. With the increasing demand for greater capacity and the development of sidelink communication, it becomes crucial for sidelink devices to use unlicensed frequency bands and coexist harmoniously with other RAT devices operating on the same unlicensed frequency bands. For example, adjacent UEs 116 and 117 communicate with base station 102 via other RATs (e.g., WiFi), sharing the same unlicensed frequency band. Adjacent UEs 118 and 119 communicate with base station 103 via other RATs, such as NRs, also sharing the same unlicensed frequency band.

[0020] For sidelink transmissions on unlicensed spectrum (SL-U), efficient resource allocation is one of the most critical issues ensuring reasonable coexistence with other RATs (e.g., NR-U and Wi-Fi) operating in the unlicensed spectrum. Two resource allocation schemes have been identified for NR sidelinks. The first is designated Mode 1 (Mode-1), and the second is designated Mode 2 (Mode-2). For Mode 1, resource allocation is scheduled by the gNB using the Uu interface. This mode is only applicable to sidelink UEs within network coverage. For Mode 2, the sidelink UE can automatically select resources from a (pre)configured resource pool based on a channel sensing mechanism on the PC5 interface. In this case, the sidelink UE can operate both within and outside coverage. When a transmitting sidelink UE attempts to select / reserve resources using Mode 2, it should perform a resource selection / reservation process consisting of two phases: resource sensing and resource selection / reservation. Typically, during the resource sensing phase, potential candidate resources available for sidelink transmission and reception are identified to avoid interfering with existing sidelink transmissions operated by other sidelink UEs. Next, during the resource selection phase, the sidelink UE can select candidate resources for transmission block (TB) transmission with the assistance of sensing results. In a novel aspect, listen-before-talk (LBT) is used in the selection phase of unlicensed frequency band resources. LBT is a spectrum sharing technology in which the device must perform a clear channel assessment (CCA) check before commencing transmission. Under the LBT mechanism, multiple UEs can share a single channel, ensuring fair coexistence among different RATs. In another novel aspect, a combined design of sidelink sensing and LBT is provided for the resource allocation scheme to ensure harmonious coexistence between the sidelink and other radio systems.

[0021] Figure 1AA simplified block diagram of a mobile device / UE operating in an unlicensed frequency band is further described. UE 111 is used as an example. UE 111 has an antenna 125 for transmitting and receiving radio signals. An RF transceiver circuit 123 coupled to the antenna receives RF signals from the antenna 125, converts them into baseband signals, and sends them to a processor 122. In one embodiment, the RF transceiver may include two RF modules (not shown). The RF transceiver 123 also converts the baseband signals received from the processor 122 into RF signals and sends them to the antenna 125. The processor 122 processes the received baseband signals and invokes different functional modules to perform functions in UE 111. Memory 121 stores program instructions and data 126 to control the operation of UE 111. The antenna 125 transmits uplink transmissions to and receives downlink transmissions from the base station.

[0022] UE 111 also includes a set of control modules that perform functional tasks. These control modules can be implemented through circuitry, software, firmware, or a combination thereof. Selection module 191 executes a side-link (SL) resource selection process, wherein the SL resource selection process selects candidate resources in the unlicensed band for the UE's SL transmission and reception. LBT module 192 executes an LBT process before SL transmission and reception, wherein the LBT process determines channel selection with other coexisting radio systems in the unlicensed band. When both the SL resource selection process and the LBT process are successful, transceiver controller 193 transmits and receives SL packets on the selected candidate resources. Selection window module 194 configures the selection, wherein the SL resource selection process is executed within the selection window, and the LBT process is executed before the selected resources for SL transmission and reception are triggered in the start time slot n, wherein the start time slot of the selection window is time slot n plus processing time T1, and the transmission time slot of the selection window is n plus packet delay budget (PDB). Dynamic configuration module 195 dynamically configures configuration parameters including the maximum number of resources and LBT trigger time indicated in the Phase 1 side-link channel information (SCI).

[0023] Figure 1B An exemplary flowchart of sidelink communication on unlicensed spectrum using LBT sensing and selection is described according to embodiments of the present invention. In step 151, the UE is in an idle state. When the sidelink UE is no longer transmitting, it continues to listen for unlicensed channel resources to identify available candidate resources. In step 152, the UE selects or reselects new candidate resources. In a novel aspect, SL resource selection in the unlicensed band uses a combination of an SL resource selection process (e.g., mode 2RA) and an LBT process.

[0024] In step 161, the UE collects sensing information. During the sensing process, the sidelink UE decodes the first-stage SCI from other sidelink UEs on an unlicensed channel. By decoding the first-stage SCI, the sidelink UE can determine the resources that other sidelink UEs have reserved for TB initial transmissions and retransmissions. During the sensing process, the sidelink UE also measures the sidelink reference signal received power (RSRP) for transmission from other sidelink UEs. The information element (IE) sl-RS-ForSensing from the higher layer indicates whether the RSRP of the physical sidelink control channel (PSCCH) or the RSRP of the PSSCH is being measured. The RSRP can be measured by the demodulation reference signal (DMRS) of the physical sidelink control channel (PSCCH) and / or by the DMRS of the physical sidelink shared channel (PSSCH). This sensing information, including the first-stage SCI and RSRP, can be stored by the sidelink UE and will be used in subsequent resource selection processes. In step 162, when one or more predetermined conditions are detected, the sidelink UE can select, reselect, or reserve a new resource. These predetermined conditions include generating a new resource bucket (TB), the new TB being unsuitable for a previously selected / reserved resource, the reselection counter (RC) decreasing to zero, and other situations requiring a new resource bucket (SL). If resource (re)selection / reservation is triggered in time slot n, the sidelink UE should first, within a certain period [n-T0, nT]... proc，0 Sensing information is collected in the [window], where T0 is an integer defined by the number of time slots and equal to x milliseconds (e.g., 1100 milliseconds or 100 milliseconds), which is determined by the upper-layer IE sl-Sensing Window. T proc，0 This is the time required to complete the sensing process. In one embodiment, the selected resource is an oversubscription candidate resource, wherein the oversubscription resource size can be configured to be greater than or equal to the resource size required for SL data transmission and reception. In another embodiment, the candidate resource is a multi-consecutive-slot (MCSt) resource with a configured plurality of contiguous resource blocks.

[0025] In a novel aspect, the sidelink UE performs the LBT process in conjunction with the SL resource selection process. In step 163, the UE selects the LBT type based on one or more conditions, including LBT type configuration and service type / QoS. In step 164, the selected LBT process is executed before each selected / reserved resource transmission. In one embodiment, the LBT process initiates channel occupancy time (COT). If the LBT is used to initiate COT or is outside of COT, type 1 LBT is configured. If the LBT is used in an initiated / shared COT, the LBT type is (pre-)configured as type 2A LBT, type 2BLBT, and type 2C LBT. In step 165, the UE determines whether it is in an idle state. If step 165 determines yes, the UE begins transmission or retransmission in step 166. If step 165 determines no, the UE moves to step 167 and determines whether this is the last selected or reserved resource. If step 167 determines yes, the process ends. If step 167 determines that it is not, the UE moves to step 168 and waits for the next resource. Once the next resource becomes available, the UE performs LBT before using the selected / reserved resource for transmission and reception.

[0026] Figure 2 An exemplary flowchart for SL resource selection based on predetermined rules, excluding some candidate resources, is described according to an embodiment of the present invention. After the sidelink UE collects sensing information, it selects resources from a selection window (SW) defined in the range [n+T1, n+T2], where T1 is the processing time and T2 is the time between T1 and T2. 2，min The range is ≤T2≤PDB, where T 2，minThe priority of the TB and SCS is determined; PDB is the packet delay budget (PDB) in the time slot, which indicates the transmission deadline before which the TB must be transmitted. When the SL resource selection or reselection process is triggered, the selection window is determined. The sidelink UE first excludes some candidate resources in the selection window. Excluded resources may include resources reserved by other sidelink UEs, which can be indicated by reservation information in the Phase 1 SCI. In this case, resources are excluded only if the sidelink UE measures that the RSRP of the reserved resource is higher than an RSRP threshold, which is determined by the higher-layer parameter sl-Thres-RSRP-List. In step 201, the UE excludes candidate resources that do not meet one or more requirements. In step 202, after the exclusion process, the sidelink UE checks whether the percentage of remaining candidate resources in the selection window meets the requirements, i.e., equal to or greater than x%. The value of x depends on the priority of the TB, which is indicated by the higher-layer parameter SL-TxPercentageConfig. If the requirements are not met, the RSRP threshold is increased in step 211. In one embodiment, the threshold is increased by 3 dB. The process then proceeds to step 201, iterating until the percentage of remaining candidate resources in the selection window meets the requirement. Once the requirement is met, in step 203, the sidelink UE can randomly select N resources from the remaining available candidate resources in the selection window for transmission.

[0027] Figure 3 An example diagram for LBT type determination is described according to an embodiment of the present invention. In one embodiment, after the SL resource selection process, the sidelink UE determines the LBT type based on (pre)configuration and / or data type / QoS. The UE performs LBT on candidate resources. A selection window ranging from [n+T1, n+T2] is determined, where T1 is the processing time and T2 is within the range of T... 2，min The range is ≤T2≤PDB, where T 2，minThe priority of TB and SCS is determined; PDB is the packet delay budget (PDB) in the time slot, which indicates the transmission deadline before which TB must be transmitted. SL transmission and reception are triggered at time 301 in time slot n. After processing time T1, at time 302, the selection window begins. The selection window ends at time n+T2 303 before n+PDB 304. In a novel aspect, the UE first selects SL candidate resources and performs an LBT process before using these selected candidate resources for transmission. The LBT process 311 is executed. In one embodiment, the LBT process initiates COT. COT is initiated 331. Resources 321 are selected in the SL resource selection process, and candidate resources are selected based on sensing results. In one embodiment, the selected resources 321 for initial transmission are multiple consecutive resources. LBT 311 is the LBT process that initiates COT, where the LBT is a type 1 LBT. Within the selection window 300, retransmission is selected using the SL resource selection process. Resources 322 are selected for retransmission. Before retransmitting using the selected retransmission resource 322, perform LBT 312. Perform LBT 312 outside of COT 332. Select type 1 LBT for LBT 312 to retransmit using retransmission resource 322. Before performing retransmission using retransmission resource 323, perform LBT 313. Perform LBT 313 within COT 332. LBT 313 performed within COT can be configured as type 2A, type 2B, or type 2C LBT.

[0028] Figure 4 Example diagrams for determining LBT configuration are described according to embodiments of the present invention. In one embodiment, when the configuration type is 1 LBT, the energy detection / sensing duration of the LBT is determined by the channel access priority class (CAPC). In another embodiment, when the configuration type is 1 LBT, the COT duration is the period after the LBT is successfully determined by CAPC. In step 401, the UE determines the configuration type is 1 LBT. In step 402, the UE configures the LBT sensing period and / or COT duration based on CAPC. In step 403, the UE obtains CAPC through mapping. The value of CAPC is determined by predefined or preconfigured direct or indirect mapping rules derived from the 5G Quality of Service (QoS) identifier (5QI) or PC5 QoS identifier (PQI) of the data. In configuration 411, CAPC is directly mapped from the 5QI of the data (traffic). In configuration 412, CAPC is directly mapped from the PQI of the data. In configuration 413, the 5QI of the data is first mapped to the PQI, and then the PQI is mapped to CAPC. In configuration 414, the PQI of the data is first mapped to 5QI, and then 5QI is mapped to CAPC.

[0029] Figure 5 An example diagram illustrating a configurable number of selected candidate resources for sidelink transmission and reception in an unlicensed frequency band is described according to embodiments of the present invention. In a novel aspect, the candidate resources are selected using an SL resource selection process. An LBT process is performed before transmission using the selected candidate resources. When the LBT succeeds, the UE transmits SL data in the unlicensed frequency band using the selected SL resources. When the LBT fails, the sidelink cannot perform transmission on the selected candidate resources. In one embodiment, the UE waits for the next selected / reserved resource to perform the LBT process.

[0030] Data transmission is triggered in time slot n 501. In time slot n+T1 502, selection window 500 begins. Selection window 500 ends in time slot n+T2 503, where time n+T2 503 precedes time n+PDB 504. During the selection process, the sidelink UE selects N candidate resources 510 within the selection window for the initial transmission of TB and subsequent N-1 blind retransmissions or HARQ retransmissions. The value of N can be pre-configured or dynamically updated. The selected resources 510 include exemplary resources 511, 512, 513, 514, and 515. Within selection window 500, LBT 551 is successfully executed for resource 561. LBT 552 fails for resource 562. LBT 553 is executed after waiting for the next resource 563. LBT 554 is successfully executed for resource 564. LBT 555 fails for resource 565. In one embodiment, the next resource is selected when LBT fails. In the example, resources 561, 562, 563, 564, and 565 correspond to resources 511, 512, 513, 514, and 515, respectively. In one embodiment, the selected resource 510 has an oversubscription size larger than the resource size required for SL data transmission and reception. In another embodiment, the candidate resources are multiple consecutive time slots. In one embodiment, the process iterates from the first selected / reserved resource to the last.

[0031] Figure 6An example diagram illustrating the configurable location of a new selection window is described according to an embodiment of the present invention. In one embodiment, the initial selection window SW can be dynamically configured based on the LBT failure probability (e.g., derived / determined based on the ratio of the number of failures to the total number of LBT sensings in the past X milliseconds / slot, or the consecutive number of LBT failures) and / or channel load state information and / or channel congestion control information. If an LBT fails before an initial selection / reservation of a resource, the sidelink UE defines a new selection window SW′, and the sidelink UE can then select / reserve a new resource in the new selection window SW′. Data transmission is triggered in time slot n 601. In time slot n+T1 602, selection window 601 begins. Selection window 601 ends in time slot n+T2 603, where time n+T2 603 is before time n+PDB 604. LBTs 651 and 652 are performed for resources 661 and 662, respectively. LBTs 651 and 652 are both successful. LBT 653 fails. In time slot n′611, LBT 653 fails. The new selection window SW′610 begins in time slot n′+T1′612 and ends in time slot n′+T2′613, where T1′ is the processing time required for the sidelink UE to sense resource selection / reservation from the LBT. T2′ must be within the range of T2′≤PDB-(n′-n) to ensure that the new resource selection / reservation in the new selection window can terminate before the data PDB requirement. It should be noted that the sidelink UE may have already initially selected / reserved N resources in the initial selection window SW. Therefore, the sidelink UE may detect a subset N of the initially selected / reserved resources. sub (0≤N sub ≤N) is no longer available due to multiple LBT failures. In this case, the sidelink UE will select N in a new selection window SW' under the PDB requirement constraint. sub A new resource.

[0032] In a novel aspect, configuration parameters / values ​​for SL resource selection are dynamically determined, including N SCI N is related to the number of candidate resources selected. max as well as For unlicensed spectrum used for SL-U communication, other radio systems such as NR-U and Wi-Fi may be involved. LBT (Local Bypass Test) before resource selection / reservation may fail, meaning the corresponding transmission cannot proceed. This situation affects the SL-U resource allocation scheme. Furthermore, LBT failure may result in the actual available resources for sidelink TB (re)transmission being less than the originally selected / reserved number N. In this case, sidelink TB (re)transmission may also fail due to insufficient resources. During the resource (re)selection / reservation process, the sidelink UE should also consider the size limitation of the first-stage SCI. Specifically, the first-stage SCI can only indicate selected / reserved resources within 32 time slots, limiting the maximum gap between two consecutive selected / reserved resources. Moreover, the first-stage SCI can only indicate a maximum of N. SCI One option / reserved resource. N SCI The maximum number is (pre-configured) for each resource pool and can be equal to one of the numbers in the range of 2-20.

[0033] Figure 7 An example diagram of dynamic configuration for SL resource selection based on configuration or predetermined conditions is described according to embodiments of the present invention. In a novel aspect 700, the UE dynamically determines configuration values ​​for SL resource selection in an unlicensed frequency band. Exemplary configuration values ​​include N related to the number of selected candidate resources. max 710, N SCI 720 and N 730.

[0034] In one embodiment 710, N max It can be predefined or dynamically configured. During the selection process, the sidelink UE selects N candidate resources within the selection window for the initial transmission of TB and the subsequent N-1 blind retransmissions or HARQ retransmissions. The value of N is left to the UE to implement, but should satisfy N≤N max The range. In one embodiment 711, N max It is (pre-)configured within a range, for example, 1≤N max The value should be ≤32, and this value should be selected based on one or more conditions, including channel utilization or load. Furthermore, the number N of resources selected / reserved should not exceed the number of available candidate resources.

[0035] In another embodiment 712, N max Configured as The new range. Furthermore, to avoid an insufficient number of candidate selection / reservation resources actually available for TB (retransmission) due to potential LBT failures, one approach is, for example, for the SL-U UE to select / reserve a maximum number of resources, i.e., N. max , can New range of N configurationmax ,in, The value can be configured to be greater than 32. Typically, The value can also be dynamically configured based on the LBT failure probability (e.g., derived / determined from the ratio of failures in the past X milliseconds / slots to the total number of LBT sensing attempts, or the consecutive number of LBT failures) and / or channel loading status information and / or channel congestion control information. For example, as channel traffic increases, and / or the probability of channel collisions increases, It can be configured to be larger to combat a higher LBT failure probability. For example, if the channel data load and / or the channel collision probability exceeds a threshold Th″. i ,but The value can be configured to the corresponding value N. max，i , where 1≤i≤I″ max and I″ max express Size of the configuration set.

[0036] In Example 720, N is dynamically determined. SCI To mitigate the impact of potential LBT failures and ensure continuous reserved information transmission, in the first phase SCI (i.e., N... SCI The maximum number of selected / reserved resources indicated in the code can be increased by more than three or more than the number without LBT operation. In Example 721, N SCI It is dynamically configured based on factors such as channel traffic load and / or channel collision probability. Specifically, as channel traffic load and / or channel collision probability increase, N can be increased. SCI The value is adjusted to counteract a higher LBT failure probability. For example, in embodiment 722, if the channel traffic load and / or channel collision probability exceeds a threshold Th... i Then N can be SCI The value is configured to the corresponding value N. SCI，i Where 1≤i≤I max and I max N represents SCI，i The size of the configuration set or the total number of resources in a packet. For cases where more resources are selected / reserved in the first-stage SCI, the time resource allocation field in the first-stage SCI will also be increased. In Example 723, if the increased bits are greater than the threshold Th... sci Then it can be carried in the first-stage SCI in a new format. If the added bits are less than the threshold Th sciIf the maximum number of selected / reserved resources indicated in the first-stage SCI is configured to be greater than four, then the first-stage SCI with the new format can be used. Otherwise, the first-stage SCI in its original format can be used.

[0037] In one embodiment 730, the value of the selected / reserved resource N can be configured to have an oversubscription size greater than or equal to the original demand for (re)transmission in TB, for example, N ori Supported by this principle, the SL-U UE can be configured to select / reserve more resources, meaning the SL-U UE has more opportunities to perform LBT and (re)transmit TB. In one embodiment 731, the value of N can also be dynamically indicated / configured based on the LBT failure probability (e.g., derived / determined based on the ratio of the number of failures to the total number of LBT sensings in the past X milliseconds / slots, or the number of consecutive LBT failures) and / or channel load status information and / or channel congestion control information. For example, as channel traffic increases, and / or the probability of channel collisions increases, N can be configured to be larger to counteract a higher probability of LBT failures. If the channel data load and / or the probability of channel collisions exceeds a threshold Th′, N can be configured to be larger. i Then the value of N can be configured as the corresponding value N. i , where 1≤i≤I′ max and I′ max N represents i Size of the configuration set.

[0038] In embodiment 740, the LBT trigger time can be dynamically indicated / configured based on the actual resource oversubscription quantity and / or LBT failure probability. In embodiment 741, the LBT trigger time is derived / determined based on the ratio of the number of failures in the past X milliseconds / slots to the total number of LBT sensings, or the consecutive number of LBT failures, and / or channel loading status information and / or channel congestion control information. For example, the potential sensing slot (e.g., 9 microseconds) failure time can be assumed to be n, which is related to the actual resource oversubscription quantity, and / or LBT failure probability, and / or channel loading status information, etc. If the selected / reserved resource location is assumed to be T, and the original LBT required time is assumed to be ΔT1, then the original LBT trigger time is T-ΔT1. However, with the proposed scheme, the actual LBT trigger time can be configured to be ΔT2 earlier than the original LBT trigger time, i.e., T-ΔT1-ΔT2, where ΔT2=n×T d T dThis represents the delay duration in the traditional LBT process. Next, when LBT succeeds, if the gap between the successful LBT location and the selected / reserved resource location is greater than one symbol, the UE should implement an LBT self-delay mechanism. Then, immediately before selecting / reserving the resource location, the UE can perform a relatively simple LBT to access the corresponding resource. If the gap does not exceed one symbol, the UE can utilize CP extension to align the boundary between the successful LBT location and the selected / reserved resource location. Through this scheme, the sidelink UE has more time and / or opportunities to attempt LBT, further increasing the probability of LBT success.

[0039] Figure 8 An exemplary flowchart for resource selection for sidelink communication in an unlicensed frequency band is described according to an embodiment of the present invention. In step 801, the UE performs a sidelink (SL) resource selection process in the radio network, wherein the SL resource selection process selects candidate resources in the unlicensed frequency band for the UE's SL transmission and reception. In step 802, the UE performs a Listen-Before-Tell (LBT) process before SL transmission and reception, wherein the LBT process determines the channel selection with other coexisting radio systems in the unlicensed frequency band. In step 803, when the SL resource selection process and the LBT process are successful, the UE transmits and / or receives SL packets on the selected candidate resources.

[0040] Although the invention has been described with reference to certain specific embodiments for illustrative purposes, the invention is not limited thereto. Therefore, various modifications, adaptations, and combinations of the various features of the described embodiments can be practiced without departing from the scope of the invention as set forth in the claims.

Claims

1. A side-link communication method, comprising: The user equipment performs a sidelink resource selection process in the wireless network, wherein the sidelink resource selection process selects candidate resources in the unlicensed frequency band for the sidelink transmission and reception of the user equipment, wherein the candidate resources are multi-continuous time slot resources with multiple configured contiguous resource blocks, and wherein one or more configuration parameters are dynamically configured, the configuration parameters including the maximum number of resources to be configured. Before transmitting and receiving on this side link, a listen-before-speak process is executed, wherein the listen-before-speak process determines the channel selection with other coexisting radio systems in the unlicensed frequency band; and When the sidelink resource selection process and the listen-before-speak process are successful, sidelink packets are sent and received on the selected candidate resources.

2. The sidelink communication method of claim 1, wherein, The listen-before-speak process is executed after the cross-link resource selection process on this side.

3. The sidelink communication method of claim 1, wherein, Configure the candidate resource selected by the side-link resource selection process to have an oversubscribed resource size that is greater than or equal to the resource size required for data transmission and reception on the side-link.

4. The side-link communication method as described in claim 3, characterized in that, The oversubscription resource size is dynamically determined based on one or more pre-configured conditions, including the probability of failure of listening before speaking, channel load status information, and channel congestion control information.

5. The side-link communication method as described in claim 3, characterized in that, Pre-configure the oversubscription resource size.

6. The side-link communication method as described in claim 1, characterized in that, When the Listen Before Talk process is executed outside of the channel occupancy time or when the Listen Before Talk process starts the channel occupancy time, the configuration type is Listen Before Talk (Type 1).

7. The side-link communication method as described in claim 6, characterized in that, Based on the channel access priority classification of the crosslink transmission and reception on this side, the sensing period of type 1, "listen before speaking", is determined.

8. The side-link communication method as described in claim 6, characterized in that, The duration of channel occupancy is determined by classifying the channel access priority of the cross link on this side.

9. The side-link communication method as described in claim 6, characterized in that, When the listen-before-speak process is executed during the channel occupancy period, configure type 2A, type 2B, or type 2C to listen-before-speak.

10. The side-link communication method as described in claim 1, characterized in that, This configuration parameter includes the maximum number of resources and the "listen before you speak" trigger time indicated in the Phase 1 side crosslink channel information.

11. The side-link communication method as described in claim 1, characterized in that, It further includes: a configuration selection window, wherein the side link resource selection process is executed within the selection window, and the listen-before-speak process is executed before the candidate resources for the selection of the side link are triggered in the start time slot n, wherein the start time slot of the selection window is the time slot n plus the processing time T1, and the transmission time slot of the selection window is the time slot n plus the packet delay budget.

12. The side-link communication method as described in claim 11, characterized in that, If the Listen-then-Speak process fails before the selection window closes, a new selection window is dynamically configured and resources are selected again.

13. The side-link communication method as described in claim 11, characterized in that, The sidelink resource selection process excludes one or more candidate resources in the selection window based on predetermined rules.

14. A user equipment for sidelink communication, comprising: A transceiver is used in a wireless system to send and receive radio frequency signals. The selection module is used to execute the side-link resource selection process, wherein... The sidelink resource selection process selects candidate resources in the unlicensed frequency band for the sidelink transceiver of the user equipment. The candidate resources are multi-continuous time slot resources with multiple configured contiguous resource blocks. One or more configuration parameters are dynamically configured, which include the maximum number of resources to be configured. The listen-before-speak module is used to execute a listen-before-speak process before crosslink transmission and reception on this side, wherein the listen-before-speak process determines the channel selection with other coexisting radio systems in the unlicensed frequency band; and A transceiver controller is used to transmit and receive side-link packets on the selected candidate resources when the side-link resource selection process and the listen-before-speak process are successful.

15. The user equipment for side-link communication as described in claim 14, characterized in that, The listen-before-speak process is executed after the cross-link resource selection process on this side.

16. The user equipment for side-link communication as described in claim 14, characterized in that, Configure the candidate resource selected by the side-link resource selection process to have an oversubscribed resource size that is greater than or equal to the resource size required for data transmission and reception on the side-link.

17. The user equipment for side-link communication as described in claim 16, characterized in that, When the Listen-After-Speak process is executed outside of the channel occupancy period or when the Listen-After-Speak process initiates the channel occupancy period, the configuration type is Listen-After-Speak (Type 1). When the Listen-After-Speak process is executed within the channel occupancy period, the configuration type is Listen-After-Speak (Type 2A, Type 2B, or Type 2C).

18. The user equipment for side-link communication as described in claim 14, characterized in that, This configuration parameter includes the maximum number of resources and the "listen before you speak" trigger time indicated in the Phase 1 side crosslink channel information.

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