Multi-subchannel sidelink resource selection in unlicensed spectrum

Abstract

In one example, a system, method, and circuit for a user equipment (UE) performing sidelink (SL) communications in an unlicensed spectrum is provided, the system including one or more processors configured to: cause the UE to receive a configuration of pre-assigned resources in a plurality of subchannels for sidelink (SL) communications; perform a clear subchannel assessment (CCA) process on at least one of the plurality of subchannels; determine a resource selection window comprising candidate resources in a subset of the pre-assigned resources; perform a resource selection process on the candidate resources in the resource selection window to determine transmission resources in at least two of the plurality of subchannels; and transmit data using the transmission resources based on results of the CCA process.

Description

[Technical Field]

[0001] The present disclosure relates generally to wireless communications, and more particularly to multi-subchannel sidelink resource selection in unlicensed spectrum. [Background technology]

[0002] Sidelink communications are carried out between user equipment (UE) devices with limited assistance from the network and form the basis of "vehicle-to-everything" (V2X) communications systems. Sidelink communications are distinct from downlink communications (from a network access point (AP) to a UE) and uplink communications (from a UE to an AP).

[0003] One of the limiting factors in wireless technology innovation is spectrum availability. To mitigate this, unlicensed spectrum has been an area of ​​interest for extending the availability of Long Term Evolution (LTE) and New Radio (NR). In this context, recent releases of 3GPP specifications support LTE and NR uplink / downlink operation in unlicensed spectrum.

[0004] Some examples of circuits, devices and / or methods are described below, by way of example only, and in this context, reference is made to the accompanying figures. [Brief explanation of the drawings]

[0005] [Figure 1] FIG. 1 illustrates an overview of sidelink (SL) communication in an unlicensed spectrum (SL-U) in a single subchannel, in accordance with various aspects disclosed herein.

[0006] [Figure 2]1 illustrates example timing diagrams for clear subchannel assessment and transmission resource selection in SL-U for multiple subchannels in accordance with various aspects disclosed.

[0007] [Figure 3] 1 illustrates example timing diagrams for clear subchannel assessment and transmission resource selection in SL-U for multiple subchannels in accordance with various aspects disclosed.

[0008] [Figure 4] 1 illustrates example timing diagrams for clear subchannel assessment and transmission resource selection in SL-U for multiple subchannels in accordance with various aspects disclosed.

[0009] [Figure 5] 1 illustrates example timing diagrams for clear subchannel assessment and transmission resource selection in SL-U for multiple subchannels in accordance with various aspects disclosed.

[0010] [Figure 6] 1 illustrates example timing diagrams for clear subchannel assessment and transmission resource selection in SL-U for multiple subchannels in accordance with various aspects disclosed.

[0011] [Figure 7] 1 illustrates example timing diagrams for clear subchannel assessment and transmission resource selection in SL-U for multiple subchannels in accordance with various aspects disclosed.

[0012] [Figure 8] 1 is a flow diagram outlining a method for a UE to perform clear subchannel assessment and resource selection in SL-U on multiple subchannels, in accordance with various disclosed aspects.

[0013] [Figure 9] FIG. 1 illustrates an example of a UE in accordance with various aspects disclosed herein. DETAILED DESCRIPTION OF THE INVENTION

[0014] The present disclosure is described with reference to the accompanying drawings. The figures are not drawn to scale and are provided solely to explain the present disclosure. Several aspects of the present disclosure are described below with reference to exemplary uses for illustration. Numerous specific details, relationships, and methods are set forth to provide an understanding of the present disclosure. The present disclosure is not limited to the illustrated order of acts or events, as some acts may occur in different orders and / or contemporaneously with other acts or events. Furthermore, not all illustrated acts or events are required to implement selected methodologies in accordance with the present disclosure.

[0015] Sidelink (SL) communications continue to develop with many additional features being provided in specific releases of the 3GPP specifications. As currently configured, sidelink communications do not include some features supported in UL / DL communications (i.e., communications between a UE and a base station over a Uu link, for example).

[0016] Certain 3GPP releases support UL / DL communications in unlicensed spectrum (NR-U). In some cases, sidelink communications in unlicensed spectrum may also be supported. Similar to UL / DL, for sidelink communications in NR-U, devices may contend for access to the unlicensed frequency band by performing Clear Subchannel Assessment (CCA) and Listen-Before-Talk (LBT) procedures before transmission. There are two types of CCA procedures. Type 1 CCA uses a random sensing period, while Type 2 CCA senses the subchannel for a predetermined period of time. In one example, the sensing window for Type 2 CCA is either 25 μs or 34 μs.

[0017] FIG. 1 is a block diagram of a wireless communication network in which UEs perform sidelink communications on a single pre-assigned subchannel. Each UE in the network includes baseband circuitry including one or more processors configured to enable various types of sidelink communications. For purposes of this description, when a "UE" or "device" is described as performing a function, it should be understood that in some examples, it is the processor(s) in the baseband circuitry that performs that function in conjunction with instructions stored in memory and / or transceiver(s). An exemplary wireless communication device, including its baseband circuitry, is shown in more detail in FIG. 9.

[0018] Sidelink communications can be performed according to one of two modes. In Mode 1, the network controls resource allocation and receives feedback about transport blocks (TBs) transmitted between UEs (e.g., by signals transmitted or received by the base station or network node 100). In one example, resources for sidelink transmissions are signaled to the transmitting UE as a transmission grant. When the network determines, based on a hybrid automatic repeat request (HARQ) acknowledgment / negative acknowledgement (ACK / NACK) signal received from the RX UE, that a TB was not decoded by the receiving (RX) UE, the network sends a retransmission grant to the transmitting (TX) UE indicating the resources to be used to retransmit the TB.

[0019] In Mode 2, the network pre-configures a pool of pre-allocated sidelink resources from which TX UEs select transmission resources without requiring a specific allocation from the network. In Mode 2, feedback for TB is provided to TX UEs by a HARQ-ACK signal transmitted on the physical sidelink feedback sub-channel (PSFCH). SL resources may be allocated on a subchannel basis. The frequency resources constituting a subchannel may be configured as a specific number of physical resource blocks (PRBs). CCA may be performed per RB set (e.g., 20 MHz bandwidth). Therefore, SL resources may be allocated with a finer granularity than the CCA granularity. The SL resource pool may include multiple RB sets and subchannels.

[0020] When a transmission is to occur in an unlicensed spectrum, the TX UE first identifies that the subchannel(s) associated with resources allocated by the network (Mode 1) or selected from a pre-allocated resource pool (Mode 2) are clear before performing the sidelink transmission.

[0021] In the example of FIG. 1, sidelink resources are pre-allocated in a single subchannel according to Type 2. In the illustrated example, the pre-allocated pool of resources includes a subchannel (e.g., 10 PRBs) that spans less than an RB set (e.g., 20 MHz). TX UE 101 attempts to transmit data (e.g., one or more TBs) to RX UEs 102 and 109. The timing of operations performed by the TX device to perform sidelink transmission in a single subchannel is outlined in FIG. 1. When data traffic arrives for transmission by the TX UE (e.g., arrives in a transmit buffer), the UE performs Type 1 CCA on each RB set that overlaps with the subchannel before selecting transmission resources for the data. In FIG. 1, the CCA process occurs over a frequency range (e.g., 20 MHz) that is larger than the pre-allocated subchannel (e.g., 10 PRBs). If a subchannel overlaps with two different RB sets, two different CCAs may be performed, one for each RB set. When all CCAs for all RB sets overlapping with the subchannel are successfully completed, the CCA process for the subchannel is considered successful.

[0022] For each CCA Type 1 procedure performed by the TX device, an N counter for the RB set is started with N, a randomly generated number bounded by the current contention window size CWS. During interval 130 (light gray shading), subchannel sensing is performed for successive slot durations in the RB set, and for each idle slot, the N counter is decremented. When the N counter reaches 0, the counter is stopped or frozen, and the Type 1 CCA is considered successful. If there were any other RB sets that overlapped with the subchannel, CCA in those RB sets must also be completed for the subchannel to be cleared.

[0023] The UE performs resource selection during a preconfigured resource selection window 140 (dark gray shading) to determine selected transmission resources 160 (hash fill). The selected transmission resources may include candidate resources occurring at any time during the resource selection window 140. The selected transmission resources may be reserved to prevent other devices from scheduling on the selected transmission resources.

[0024] If the time interval between the end of Type 1 CCA and the selected transmission resource is greater than a threshold, immediately before transmission, the TX UE performs a confirmation LBT during interval 150 (black shading). In one example, the confirmation LBT is Type 2 CCA. If the confirmation LBT is successful, the TX UE 101 may send sidelink control information (SCI) using a PSCCH resource associated with an L1 destination ID for the RX UEs 102 and 109. The SCI instructs the RX UEs 102 and 109 how to continue receiving one or more transport blocks (TBs) of data from the TX UE 101. For example, the SCI identifies the selected transmission resources to be used to transmit the TB(s). This indication may include an indication of time resources, such as slots and / or symbols, as well as frequency resources, such as subchannel indexes and / or resource block (RB) set indexes. The TX UE then transmits the data (e.g., TB(s)) to the RX UEs 102 and 109. When new data traffic arrives, a new random value of N is generated for the subsequent Type 1 CCA.

[0025] Although the example of FIG. 1 shows Type 1 CCA being used to determine that an RB set or subchannel is clear, any type of CCA may be used with the techniques described herein.

[0026] Multi-subchannel sidelink communication in unlicensed spectrum poses challenges in determining appropriate sensing and resource selection procedures that balance performance, power consumption, etc. Disclosed herein are different methods for a TX device to select resources in sidelink mode 2 in unlicensed multi-subchannel operation scenarios.

[0027] Figures 2 to 7 illustrate various techniques for performing Mode 2 sidelink transmissions in unlicensed spectrum using multiple subchannels based on adaptations of the single-subchannel example of Figure 1. In the illustrated example, the CCA is Type 1 CCA, although any other type of CCA may be used. For purposes of the examples of Figures 2 to 7, the pre-allocated resources include five different subchannels (which may or may not be adjacent to each other), and the PSCCH / PSSCH transmission requires two subchannels.

[0028] As described with reference to FIG. 1 , a separate CCA may be performed for each RB set overlapping with a subchannel, and when all CCAs are successful (e.g., all N counters = 0), the overall CCA for the subchannel may be considered successful. For simplicity, in FIGS. 2 to 7 , there are five pre-allocated subchannels, each spanning one entire RB set (e.g., 20 MHz per RB set, or a total pre-allocation of 100 MHz), such that only one CCA is performed per subchannel. One or more subchannels may be used for sidelink transmissions. It should be understood that when a subchannel spans more than one RB set, CCA is performed on each of the RB sets before the CCA is considered successful. This performance of potentially multiple parallel CCAs on all RB sets overlapping with a subchannel may be referred to herein as a “CCA process” for the subchannel. In one example, the transmission resources must include adjacent RB sets, and in another example, the transmission resources may include non-adjacent RB sets.

[0029] In a first set of techniques shown in Figures 2 and 3, CCA is performed on at least one of the pre-assigned subchannels before performing transmission resource selection. In the example of Figure 2, in response to data traffic arriving at the UE, CCA is performed on all of the subchannels during the light gray shaded interval 230 based on a randomly generated N counter value for the subchannel. Candidate resources in a first subchannel for completing CCA (subchannel 2 in Figure 2) and a second subchannel for completing CCA (subchannel 3 in Figure 2) are selected for a resource selection window 240. In some examples, the first subchannel and the second subchannel used for the resource selection window need not be adjacent to each other. In some examples, the first subchannel and the second subchannel must be adjacent to each other, in which case the first adjacent subchannel for completing CCA is selected as the second subchannel for the resource selection window.

[0030] A resource selection process is performed on the candidate resources within the resource selection window to determine a transmission resource 260. Once the transmission resource is determined, the transmission resource may be reserved.

[0031] If sufficient time has elapsed between the end of the CCA process in either subchannel and the transmission resource, a confirmation LBT 250 (e.g., Type 2 CCA) may be performed in the first subchannel and / or the second subchannel. If the confirmation LBT 250 is successful, the TX UE transmits either or both the PSCCH and PSSCH using the transmission resource 260.

[0032] When new data traffic arrives in the UE buffer for transmission, new random values ​​of N are generated for the first and second subchannels. In one example, all N counters are reset and new random values ​​of N are generated for all subchannels in the pre-allocated resources, while in another example, the N counters are not reset for other subchannels and the counters continue to run in subsequent CCAs.

[0033] In the example of FIG. 3, in response to data traffic arriving at the UE, CCA is performed in a randomly selected subchannel (subchannel 3 in FIG. 3) during the light gray shaded interval 330 based on a randomly generated N counter value for the subchannel. Once CCA in the selected subchannel is completed, transmission resources 360 in a first subchannel (subchannel 1 in FIG. 3) and a second subchannel (subchannel 2 in FIG. 3) are selected from a resource selection window 340 that includes candidate resources in all five subchannels. In some examples, the first subchannel and the second subchannel for the transmission resources do not need to be adjacent to each other. In some examples, the first subchannel and the second subchannel must be adjacent to each other. In one example (not shown), either the first subchannel or the second subchannel is the subchannel on which CCA was performed (subchannel 3 in FIG. 2). Once the transmission resources are determined, the transmission resources may be reserved.

[0034] If sufficient time has elapsed between the end of the CCA process in any subchannel and the transmission resource, a confirmation LBT 350 (e.g., Type 2 CCA) may be performed in the first subchannel and / or the second subchannel. If the confirmation LBT 350 is successful, the TX UE transmits the PSCCH (optional) and PSSCH using the transmission resource 360. When new data traffic arrives, a new random value of N is generated for the subchannel on which CCA was performed.

[0035] 2 and 3, a Layer 1 (L1) LBT failure indication may be triggered when either a CCA (e.g., Type 1 CCA) or a confirmation LBT (e.g., Type 2 CCA) for any RB set in a selected subchannel is not successful before a selected transmission resource. An L1 LBT failure indication may be provided only for subchannels that overlap with the RB set for which the CCA or LBT failed, or an L1 LBT failure indication may be provided for all selected subchannels or all pre-assigned subchannels. When transmission resources are selected after CCA completion, the likelihood of CCA failure is relatively low, so the LBT failure timer / threshold used to trigger the selection of new pre-assigned SL resources may be set to a relatively small value.

[0036] For PSFCH transmission, a UE may transmit PSFCH to different UEs in different RB sets. In one option, PSFCH transmission may follow the same rules as PSSCH and PSCCH, and PSFCH transmission in one slot is canceled if any of the RB sets fails CCA. In this case, an L1 LBT failure indication may be triggered similarly to PSSCH or PSCCH. In another option, PSFCH transmission may proceed in RB sets where CCA is successful, but PSFCH transmission is canceled in RB sets where CCA is not successful. In this case, an L1 LBT failure indication may be triggered if any of the RB sets does not clear CCA.

[0037] When Mode 1 SL transmission is used, a Layer 1 (L1) LBT failure indication may be triggered when either a CCA (e.g., Type 1 CCA) or a confirmed LBT (e.g., Type 2 CCA) for any RB set is not successful before the selected transmission resource.

[0038] In a second set of example techniques shown in Figures 4 and 5, resource selection of candidate resources in selected subchannels (e.g., two subchannels in this example) is performed before performing CCA on at least one of the selected subchannels. In the example of Figure 4, a resource selection window 440 including two subchannels (subchannels 2 and 3 in Figure 4) is randomly selected. In one example, the first and second subchannels must be adjacent to each other. In one example, the first and second subchannels do not need to be adjacent to each other. Transmission resources 460 are selected using a resource selection process over the resource selection window 440. Once the transmission resources are determined, the transmission resources may be reserved.

[0039] The CCA process 430 is initiated on the selected first and second subchannels after the transmission resource 460 is selected. If either of the CCA processes does not complete sufficiently before the transmission resource (N=0), the PSSCH may be dropped and a Layer 1 (L1) LBT failure indication to the media access control (MAC) layer may be triggered.

[0040] If sufficient time has passed between the end of the CCA process and the transmission resources in any subchannel, a confirmation LBT 450 (e.g., Type 2 CCA) may be performed in the first subchannel and / or the second subchannel. If the confirmation LBT 450 is successful, the TX UE transmits the PSCCH (optional) and PSSCH using the transmission resources 460. When new data traffic arrives, a new random value of N is generated for the subchannel on which CCA was performed.

[0041] In the example of Figure 5, a resource selection window 540 containing two subchannels (subchannels 2 and 3 in Figure 4) is randomly selected. In one example, the first and second subchannels must be adjacent to each other. In one example, the first and second subchannels do not need to be adjacent to each other. A transmission resource 560 is selected using a resource selection process over the resource selection window 540. Once the transmission resource is determined, the transmission resource may be reserved.

[0042] The CCA process 530 is initiated in the selected one of the first and second subchannels (subchannel 3 in FIG. 5) after the transmission resource 560 is selected. If the CCA process is not completed sufficiently before the transmission resource (N=0), the PSSCH is dropped and a Layer 1 (L1) LBT failure indication to the media access control (MAC) layer is triggered.

[0043] If sufficient time has elapsed between the end of the CCA process and the transmission resource, a confirmation LBT 550 (e.g., Type 2 CCA) may be performed on the first subchannel and / or the second subchannel. If the confirmation LBT 550 is successful, the TX UE transmits the PSCCH (optional) and PSSCH using the transmission resource 560. When new data traffic arrives, a new random value of N is generated for the subchannel on which CCA was performed.

[0044] 4 and 5, a Layer 1 (L1) LBT failure indication may be triggered when either a CCA (e.g., Type 1 CCA) or a confirmed LBT (e.g., Type 2 CCA) for any RB set in a selected subchannel is not successful before a selected transmission resource. Because the likelihood of CCA failure is relatively high when a transmission resource is selected before CCA completion, the LBT failure timer / threshold used to trigger the selection of a new pre-allocated SL resource may be set to a relatively large value to avoid frequent LBT failure recovery procedures.

[0045] In a third set of techniques shown in FIGS. 6 and 7, CCA is performed in at least one of the pre-assigned subchannels, and a transmission resource is selected when at least one of the CCAs reaches a threshold level of completion or progress (e.g., an N counter reaches a threshold number that is a percentage of its initial value “T”). In the example of FIG. 6, in response to data traffic arriving at the UE, CCA is performed in all of the subchannels during the light gray shaded interval 630 based on randomly generated N counter values ​​for each of the subchannels. Candidate resources in the first subchannel (subchannel 2 in FIG. 6) and the second randomly selected subchannel (subchannel 3 in FIG. 6) in which CCA reaches a threshold level of completion are selected for the resource selection window 640. In some examples, the first subchannel and the second subchannel used for the resource selection window need not be adjacent to each other. In some examples, the first subchannel and the second subchannel must be adjacent to each other.

[0046] While the CCA process is ongoing in the first and second subchannels, a resource selection process is performed on the candidate resources in the resource selection window to determine a transmission resource 660. Once the transmission resource is determined, the transmission resource may be reserved. If any of the CCA processes are not completed sufficiently before the transmission resource (N=0), the PSSCH is dropped and a Layer 1 (L1) LBT failure indication to the media access control (MAC) layer is triggered.

[0047] If sufficient time has elapsed between the end of the CCA process in either subchannel and the transmission resource, a confirmation LBT 650 (e.g., Type 2 CCA) may be performed in the first subchannel and / or the second subchannel. If the confirmation LBT 650 is successful, the TX UE transmits the PSCCH (optional) and the PSSCH using the transmission resource 660.

[0048] When new data traffic arrives, new random values ​​of N are generated for the first and second subchannels. In one example, the N counter is reset and new random values ​​of N are generated for all subchannels in the pre-allocated resource, while in another example, the N counters in other subchannels are not reset and the counters continue to run in subsequent CCAs.

[0049] In the example of FIG. 7, in response to data traffic arriving at the UE, CCA is performed in a randomly selected subchannel (subchannel 3 in FIG. 3) during the light gray shaded interval 730 based on a randomly generated N counter value for the subchannel. Once CCA in the selected subchannel reaches a threshold level of completion, transmission resources 760 in a first subchannel (subchannel 1 in FIG. 3) and a second subchannel (subchannel 5 in FIG. 3) are selected from a resource selection window 740 that includes candidate resources in all five subchannels. In some examples, the first subchannel and the second subchannel for the transmission resources need not be adjacent to each other. In some examples, the first subchannel and the second subchannel must be adjacent to each other. In one example (not shown), either the first subchannel or the second subchannel is the subchannel on which CCA was performed (subchannel 3 in FIG. 2). Once the transmission resources are determined, the transmission resources may be reserved. If the CCA process is not completed sufficiently before the transmission resource (N=0), the PSSCH is dropped and a Layer 1 (L1) LBT failure indication to the media access control (MAC) layer is triggered.

[0050] If sufficient time has elapsed between the end of the CCA process in any subchannel and the transmission resource, a confirmation LBT 750 (e.g., Type 2 CCA) may be performed in the first subchannel and / or the second subchannel. If the confirmation LBT 750 is successful, the TX UE transmits the PSCCH (optional) and PSSCH using the transmission resource 760. When new data traffic arrives, a new random value of N is generated for the subchannel on which CCA was performed.

[0051] 8 is a flow chart outlining an example method 800 that may be performed by a UE performing sidelink (SL) communications in an unlicensed spectrum. The method includes, at 810, receiving a configuration of pre-allocated resources in a plurality of subchannels for sidelink (SL) communications. At 820, a clear subchannel assessment (CCA) process is performed in at least one of the plurality of subchannels. At 830, a resource selection window including candidate resources in a subset of the pre-allocated resources is determined, and a resource selection process is performed on the candidate resources in the resource selection window to determine transmission resources in at least two of the plurality of subchannels. At 840, data is transmitted using the transmission resources based on results of the CCA process.

[0052] In one example of method 800, the operations performed at 820 may be performed before the operations performed at 830, as disclosed with reference to Figures 2 and 3. In this example, a CCA process is performed on at least one of a plurality of pre-assigned subchannels, then a resource selection window is determined and a transmission resource is selected.

[0053] In one example of method 800, the operations performed at 830 may be performed before the operations performed at 820, as disclosed with reference to Figures 4 and 5. In this example, resource selection of candidate resources in selected subchannels (e.g., two subchannels in this example) is performed before performing CCA on at least one of the selected subchannels.

[0054] In one example of method 800, the operations performed at 820 may be performed during (e.g., at least partially overlapping with) the operations performed at 830, as disclosed with reference to Figures 6 and 7. In this example, CCA is performed on at least one of the pre-assigned subchannels, and a transmission resource is selected when at least one of the CCAs reaches a threshold level of completion or progress (e.g., an N counter reaches a threshold number that is a percentage of its initial value "T").

[0055] From the foregoing disclosure, it can be seen that many different techniques can be employed to perform sidelink transmissions in unlicensed spectrum.

[0056] FIG. 9 illustrates an example of an apparatus 900 for a UE according to various aspects. In various aspects, the apparatus 900 may be suitable for use as the UEs 101, 102, and 109 of FIG. 1 and / or any other elements / devices described herein. The apparatus 900 may include any combination of the components shown in this example. The components of the apparatus 900 may be implemented as an integrated circuit (IC), a portion thereof, a separate electronic device, or other module, logic, hardware, software, firmware, or a combination thereof adapted to the apparatus 900, or as components otherwise integrated within the chassis of a larger system. The block diagram of FIG. 9 is intended to illustrate a high-level view of the components of the apparatus 900. However, some of the components shown may be omitted, additional components may be present, and different arrangements of the components shown may occur in other embodiments.

[0057] The application circuitry 905 includes, but is not limited to, one or more processors (or processor cores), cache memory, and circuits such as one or more LDOs, an interrupt controller, a serial interface such as SPI, I2C, or a universal programmable serial interface module, a timer counter including an RTC, interval and watchdog timers, a general-purpose I / O, a memory card controller such as SD MMC, a USB interface, a MIPI interface, and a JTAG test access port. The processors (or cores) of the application circuitry 905 may be coupled to or include memory / storage elements and may be configured to execute instructions stored in the memory / storage elements to enable various applications or operating systems to run on the system 900. In some implementations, the memory / storage elements may be on-chip memory circuits, which may include any suitable volatile and / or non-volatile memory, such as DRAM, SRAM, EPROM, EEPROM, flash memory, solid-state memory, and / or any other type of memory device technology as described herein.

[0058] By way of example, the processor(s) of application circuit 905 may include a general-purpose or special-purpose processor, such as an A-series processor (e.g., A13 Bionic) available from Apple® Inc. (Cupertino, CA), or any other such processor. The processor of the application circuit 905 may also be one or more of an Advanced Micro Devices (AMD) Ryzen® processor or accelerated processing unit (APU), Intel® Inc.'s core processor(s), Qualcomm® Technologies Inc.'s Snapdragon™ processor(s), Texas Instruments, Inc.'s Open Multimedia Application Platform (OMAP)™ processor(s), or MIPS-based designs from MIPS Technologies, Inc., such as the MIPS Warrior M-class, Warrior I-class, and Warrior P-class processors, ARM-based designs licensed from ARM Holdings, Ltd., such as the ARM Cortex-A, Cortex-R, and Cortex-M family of processors, etc. In some implementations, the application circuit 905 may be part of a system on a chip (SoC) in which the application circuit 905 and other components are formed on a single integrated circuit or package.

[0059] The baseband circuit or processor 910 may be implemented, for example, as a soldered board containing one or more integrated circuits, a single packaged integrated circuit soldered to a main circuit board, or a multi-chip module containing two or more integrated circuits. The memory circuit 920 may store executable instructions that, when executed by the baseband processor, cause the UE to perform CCA or LBT in the unlicensed spectrum, select multi-subchannel transmission resources, and transmit data to one or more other UEs using an SL communication protocol (e.g., unicast, groupcast, broadcast) on the multiple subchannels based on the CCA or LBT.

[0060] Device 900 may also include interface circuitry (not shown) used to connect external devices with device 900. External devices connected to device 900 via the interface circuitry include sensor circuitry 921 and electro-mechanical components (EMC) 922, as well as a removable memory device coupled to removable memory circuit 923. Battery 930 may provide power to device 900, although in some examples device 900 may be mounted and deployed at a fixed location and may have a power source coupled to a power grid.

[0061] In this description and the appended claims, the use of the term "determine" with respect to certain entities (e.g., parameters, variables, etc.) in describing method steps or functions should be interpreted broadly. For example, "determine" should be interpreted to encompass, for example, receiving and analyzing a communication encoding the entity or a value of the entity. "Determine" should be interpreted to encompass accessing and reading a memory (e.g., a lookup table, a register, a device memory, a remote memory, etc.) that stores the entity or a value of the entity. "Determine" should be interpreted to encompass calculating or deriving the entity or a value of the entity based on other quantities or entities. "Determine" should be interpreted to encompass any method of inferring or identifying the entity or a value of the entity.

[0062] As used herein, the term "identify," when used with respect to any entity or entity value, should be interpreted broadly to encompass any method of determining the entity or entity value. For example, the term "identify" should be interpreted to encompass, for example, receiving and analyzing a communication that encodes the entity or entity value. The term "identify" should be interpreted to encompass accessing and reading a memory (e.g., a device queue, lookup table, register, device memory, remote memory, etc.) that stores the entity or entity value.

[0063] As used herein, the term encode, when used with respect to any entity or value of an entity, should be interpreted broadly to encompass any method or technique for producing a data sequence or signal that conveys the entity to another entity.

[0064] As used herein, the term "select," when used with respect to any entity or entity value, should be interpreted broadly to encompass any method of determining the entity or entity value from among multiple or a range of possible choices. For example, the term "select" should be interpreted to encompass accessing and reading a memory (e.g., a lookup table, a register, a device memory, a remote memory, etc.) that stores the entity or entity values ​​and returning an entity or entity value from among the stored entity or entity values. The term "select" should be interpreted as applying one or more constraints or rules to a set of input parameters to determine an appropriate entity or entity value. The term "select" should be interpreted broadly to encompass any method of selecting an entity based on one or more parameters or conditions.

[0065] As used herein, the term derive should be interpreted broadly when used with respect to any entity or value of an entity. "Derive" should be interpreted to encompass accessing and reading memory (e.g., lookup table, register, device memory, remote memory, etc.) that stores some initial or base value, and performing processing and / or logical / mathematical operations on one or more values ​​to produce a derived entity or value of the entity. The term "derive" should be interpreted to encompass calculating or computing the value of the entity or entity based on other quantities or entities. The term "derive" should be interpreted to encompass any method of inferring or identifying the entity or value of the entity.

[0066] As used herein, the term indicate, when used with respect to any entity (e.g., a parameter or setting) or value of the entity, should be interpreted broadly to encompass any method of reaching the entity or value of the entity, whether explicit or implicit. For example, a bit in a transmitted message may be used to explicitly encode the indicated value, or may encode an index or other indicator that maps to a value indicated by a previous configuration. The absence of a field in a message may implicitly indicate a value of the entity based on the previous configuration. Example

[0067] Example 1 is an apparatus for user equipment (UE) operating in an unlicensed spectrum, including one or more processors, configured to: cause the UE to receive a configuration of pre-assigned resources in a plurality of subchannels for sidelink (SL) communication; perform a clear subchannel assessment (CCA) process on at least one of the plurality of subchannels; determine a resource selection window including candidate resources in a subset of the pre-assigned resources; perform a resource selection process on the candidate resources in the resource selection window to determine transmission resources in at least two of the plurality of subchannels; and transmit data using the transmission resources based on results of the CCA process.

[0068] Example 2 includes the subject matter of Example 1, and may include or omit any element, wherein the one or more processors are configured to perform a CCA process on at least one of the plurality of subchannels before performing the resource selection process.

[0069] Example 3 includes the subject matter of Example 1, and may include or omit optional elements, wherein the one or more processors are configured to perform a resource selection process to select at least two sub-channels, and then perform a CCA process on at least one of the selected at least two sub-channels.

[0070] Example 4 includes the subject matter of Example 1, and may include or omit any element, wherein the one or more processors are configured to initiate a resource selection process while performing a CCA process for one or more of the plurality of subchannels.

[0071] Example 5 is an apparatus for user equipment (UE) operating in an unlicensed spectrum, including one or more processors, configured to: cause the UE to receive a configuration of pre-assigned resources in a plurality of subchannels for sidelink (SL) communication; perform a clear subchannel assessment (CCA) process on at least one of the plurality of subchannels; after performing the CCA process, determine a resource selection window including candidate resources in a subset of the pre-assigned resources; perform a resource selection process on the candidate resources in the resource selection window to determine transmission resources in at least two of the plurality of subchannels; and transmit data using the transmission resources based on results of the CCA process.

[0072] Example 6 includes the subject matter of Example 5, and may include or omit any element, wherein the one or more processors are configured to: perform a CCA process on each of a plurality of subchannels in response to data arriving for SL transmission; select, for a resource selection window, a candidate resource in a first subchannel of the plurality of subchannels for which the corresponding CCA process is successfully completed; select, for the resource selection window, a candidate resource in a second subchannel of the plurality of subchannels based on the successful completion of the corresponding CCA process in the second subchannel; and, if the resource selection window does not include candidate resources in other subchannels of the plurality of subchannels, perform a resource selection process on the candidate resources in the resource selection window to determine the transmission resource.

[0073] Example 7 includes the subject matter of Example 5, and may include or omit any element, wherein the one or more processors are configured to: in response to data arriving for SL transmission, perform a CCA process on a selected one of the plurality of subchannels; in response to successful completion of the CCA process, select candidate resources in all of the plurality of subchannels for a resource selection window; and perform a resource selection process in the resource selection window to determine transmission resources in a first subchannel and a second subchannel of the plurality of subchannels.

[0074] Example 8 includes the subject matter of Example 5, and may include or omit any element, wherein the one or more processors are configured to select a subchannel on which CCA is performed as the first subchannel or the second subchannel of the transmission resource.

[0075] Example 9 is an apparatus for user equipment (UE) operating in an unlicensed spectrum, including one or more processors, configured to: cause the UE to receive a configuration of pre-assigned resources in a plurality of subchannels for sidelink (SL) communication; determine a resource selection window including candidate resources in a subset of the pre-assigned resources; perform a resource selection process on the candidate resources in the resource selection window to determine transmission resources in at least two of the plurality of subchannels; perform a clear subchannel assessment (CCA) process on at least one of the plurality of subchannels after determining the transmission resources; and transmit data using the transmission resources based on results of the CCA process.

[0076] Example 10 includes the subject matter of Example 9, and may include or omit any element, wherein the one or more processors are configured to: select a resource selection window including candidate resources in a first subchannel and a second subchannel of the plurality of subchannels in response to data arriving for SL transmission; perform a resource selection process in the resource selection window to determine transmission resources; perform a CCA process in the first subchannel and the second subchannel; and transmit the data on the transmission resources in response to successful completion of the CCA process in the first subchannel and the second subchannel prior to the transmission resources.

[0077] Example 11 includes the subject matter of Example 9, and may include or omit any element, wherein the one or more processors are configured to: select a resource selection window including candidate resources in a first subchannel and a second subchannel of the plurality of subchannels in response to data arriving for SL transmission; perform a resource selection process in the resource selection window to determine a transmission resource; initiate a CCA process in the selected one of the first subchannel and the second subchannel; and transmit the data on the transmission resource in response to successful completion of the CCA process in the selected one of the first subchannel and the second subchannel prior to the transmission resource.

[0078] Example 12 is an apparatus for user equipment (UE) operating in an unlicensed spectrum, including one or more processors, configured to: cause the UE to receive a configuration of pre-assigned resources in a plurality of subchannels for sidelink (SL) communication; perform a clear subchannel assessment (CCA) process on at least one of the plurality of subchannels; determine, during the CCA process, a resource selection window including candidate resources in a subset of the pre-assigned resources; perform a resource selection process on the candidate resources in the resource selection window to determine transmission resources in at least two of the plurality of subchannels; and transmit data using the transmission resources based on results of the CCA process.

[0079] Example 13 includes the subject matter of Example 12, and may include or omit any element, wherein the one or more processors are configured to: perform a CCA process in each of a plurality of subchannels in response to data arriving for SL transmission; select, for a resource selection window, candidate resources in a first subchannel of the plurality of subchannels for which the corresponding CCA reaches a threshold level for completion; select, for the resource selection window, candidate resources in a second subchannel of the plurality of subchannels; and, where the resource selection window does not include candidate resources in other subchannels of the plurality of subchannels, perform a resource selection process on the candidate resources in the resource selection window to determine the transmission resources.

[0080] Example 14 includes the subject matter of Example 12, and may include or omit any element, wherein the one or more processors are configured to: initiate a CCA process in a selected one of the plurality of subchannels in response to data arriving for SL transmission; select candidate resources in all of the plurality of subchannels for a resource selection window in response to the CCA process reaching a threshold level of completion; and perform a resource selection process in the resource selection window to determine transmission resources in a first subchannel and a second subchannel of the plurality of subchannels.

[0081] Example 15 includes the subject matter of Example 14, and may include or omit any element, wherein the one or more processors are configured to select a subchannel on which CCA is performed as the first subchannel or the second subchannel.

[0082] Example 16 includes the subject matter of any one of Examples 1 to 15, and may include or omit any element, wherein the one or more processors are configured to select candidate resources in a first subchannel and a second subchannel as transmission resources, the second subchannel being adjacent to the first subchannel.

[0083] Example 17 includes the subject matter of any one of Examples 1 to 15, and may include or omit any element, wherein the one or more processors are configured to select candidate resources in a first subchannel and a second subchannel as transmission resources, wherein the second subchannel may or may not be adjacent to the first subchannel.

[0084] Example 18 includes the subject matter of any one of Examples 1 to 15, and may include or omit any element, wherein the one or more processors are configured to determine that the CCA process in the subchannel is successful when a separate CCA process in each resource block set of the subchannel is successfully completed.

[0085] Example 19 includes the subject matter of any one of Examples 1 to 15, and may include or omit any element, wherein the one or more processors are configured to select adjacent resource block sets within each of at least two subchannels of the plurality of subchannels for transmission resources.

[0086] Example 20 includes the subject matter of any one of Examples 1 to 15, and may include or omit any element, wherein the one or more processors are configured to select, for transmission resources, a set of adjacent resource blocks or non-adjacent resource blocks within each of at least two subchannels of the plurality of subchannels.

[0087] Example 21 includes the subject matter of any one of Examples 1 to 15, and may include or omit any element, wherein the one or more processors are configured to, in response to arrival of new data traffic for SL transmission, reset an N counter associated with the CCA process corresponding to the subchannel selected for the transmission resource.

[0088] Example 22 includes the subject matter of any one of Examples 1 to 15, and may include or omit any element, wherein the one or more processors are configured to reset N counters associated with CCA processes corresponding to all of the plurality of subchannels in response to arrival of new data traffic for SL transmission.

[0089] Example 23 includes the subject matter of any one of Examples 1 to 15, and may include or omit any element, wherein the one or more processors are configured to, in response to arrival of new data traffic for SL transmission, generate a new random value for N and reset an N counter associated with the CCA process corresponding to the subchannel selected for the transmission resource.

[0090] Example 24 includes the subject matter of any one of Examples 1 to 15, and may include or omit any element, wherein the one or more processors are configured to, in response to arrival of new data traffic for SL transmission, generate a new random value for N and reset N counters associated with CCA processes corresponding to all of the plurality of subchannels.

[0091] Example 25 includes the subject matter of any one of Examples 1 to 15, and may include or omit any element, wherein the one or more processors are configured to perform a confirmation listen-before-talk (LBT) on a frequency resource of the transmission resource before transmitting the data.

[0092] Example 26 includes the subject matter of Example 25, including or omitting optional elements, and includes a CCA where the confirmation LBT is Type 2.

[0093] Example 27 includes the subject matter of Example 25, and may include or omit any element, wherein the one or more processors are configured to trigger a Layer 1 (L1) LBT failure indication when the confirmation LBT fails.

[0094] Example 28 includes the subject matter of any one of Examples 1 to 15, and may include or omit any element, wherein the one or more processors are configured to trigger an L1 LBT failure indication in response to a failure of the CCA process in one sub-channel.

[0095] Example 29 includes the subject matter of any one of Examples 1 to 15, and may include or omit any element, wherein the one or more processors are configured to trigger an L1 LBT failure indication in all selected subchannels in response to a failure of the CCA process in one selected subchannel.

[0096] Example 30 includes the subject matter of any one of Examples 1 to 15, including or omitting any element, and wherein the CCA process includes Type 1 CCA.

[0097] Example 31 includes the subject matter of any one of Examples 1 to 15, and may include or omit any element, wherein the one or more processors are configured to: cancel the PSFCH in the first subchannel and transmit the PSFCH in the second subchannel when the transmission includes a physical sidelink feedback channel (PSFCH) in a first subchannel and a second subchannel; and when the CCA process in the first subchannel fails and the CCA process in the second subchannel succeeds.

[0098] Example 32 includes the subject matter of any one of Examples 1 to 15, and may include or omit any element, wherein the one or more processors are configured to: cancel the PSFCH in the first subchannel and the PSFCH in the second subchannel when the transmission includes a physical sidelink feedback channel (PSFCH) in a first subchannel and a second subchannel; and when the CCA process in the first subchannel fails and the CCA process in the second subchannel succeeds;

[0099] Example 33 is an apparatus for user equipment (UE) operating in an unlicensed spectrum, including one or more processors, configured to: cause the UE to receive an allocation of sidelink (SL) resources in response to data arriving for an SL transmission to another UE, the assigned SL resources including candidate resources in a plurality of subchannels; perform at least one clear subchannel assessment (CCA) process in at least one of the plurality of subchannels; perform a resource selection process based on the candidate resources in a resource selection window corresponding to at least a subset of the assigned SL resources to determine transmission resources including frequency resources in at least two of the plurality of subchannels; and trigger an L1 LBT failure indication in response to the CCA process failing in at least one subchannel.

[0100] Example 34 includes the subject matter of Example 34, and includes or omits any element, wherein the at least one CCA process includes Type 1 CCA or Type 2 CCA, or both Type 1 CCA and Type 2 CCA.

[0101] Example 35 is a user equipment (UE) configured to operate in an unlicensed spectrum, the user equipment (UE) including: a memory; and one or more processors, which, when executing instructions stored in the memory, are configured to: cause the UE to receive a configuration of pre-assigned resources in a plurality of sub-channels for sidelink (SL) communications; perform a clear sub-channel assessment (CCA) process in at least one of the plurality of sub-channels; after performing the CCA process, determine a resource selection window including candidate resources in a subset of the pre-assigned resources; perform a resource selection process on the candidate resources in the resource selection window to determine transmission resources in at least two of the plurality of sub-channels; and transmit data using the transmission resources based on results of the CCA process.

[0102] Example 36 includes the subject matter of Example 35, and may include or omit any element, wherein the one or more processors are configured to: cause the UE, in response to data arriving for SL transmission, to perform a CCA process on each of a plurality of subchannels; select, for a resource selection window, candidate resources in a first subchannel of the plurality of subchannels for which the corresponding CCA process is successfully completed; select, for the resource selection window, candidate resources in a second subchannel of the plurality of subchannels based on the successful completion of the corresponding CCA process in the second subchannel; and perform a resource selection process on the candidate resources in the resource selection window to determine the transmission resources.

[0103] Example 37 includes the subject matter of Example 35, and may include or omit any element, wherein the one or more processors are configured to: cause the UE to perform a CCA process on a selected one of the plurality of subchannels in response to data arriving for an SL transmission; and, in response to successful completion of the CCA process, cause the UE to select candidate resources in all of the plurality of subchannels for a resource selection window; and perform a resource selection process in the resource selection window to determine transmission resources in a first subchannel and a second subchannel of the plurality of subchannels.

[0104] Example 86 includes the subject matter of Example 35, and may include or omit any element, wherein the one or more processors are configured to cause the UE to select a subchannel on which CCA is performed as a first subchannel or a second subchannel of the transmission resource.

[0105] Example 39 is a method for a user equipment (UE) operating in an unlicensed spectrum, the method including: receiving a configuration of pre-assigned resources in a plurality of subchannels for sidelink (SL) communication; determining a resource selection window including candidate resources in a subset of the pre-assigned resources; performing a resource selection process on the candidate resources in the resource selection window to determine transmission resources in at least two of the plurality of subchannels; performing a clear subchannel assessment (CCA) process on at least one of the plurality of subchannels after determining the transmission resources; and transmitting data using the transmission resources based on results of the CCA process.

[0106] Example 40 includes the subject matter of Example 39, and may include or omit any element, and includes selecting, in response to data arriving for SL transmission, a resource selection window including candidate resources in a first subchannel and a second subchannel of the plurality of subchannels; performing a resource selection process in the resource selection window to determine transmission resources; performing a CCA process in the first subchannel and the second subchannel; and transmitting the data in the transmission resources in response to successful completion of the CCA process in the first subchannel and the second subchannel prior to the transmission resources.

[0107] Example 41 includes the subject matter of Example 39, and may include or omit any element, and includes: in response to data arriving for SL transmission, selecting a resource selection window including candidate resources in a first subchannel and a second subchannel of the plurality of subchannels; performing a resource selection process in the resource selection window to determine a transmission resource; initiating a CCA process in the selected one of the first subchannel and the second subchannel; and transmitting the data in the transmission resource in response to successful completion of the CCA process in the selected one of the first subchannel and the second subchannel prior to the transmission resource.

[0108] Example 42 is an apparatus for user equipment (UE) operating in an unlicensed spectrum, the apparatus including: a memory; and one or more processors, wherein the one or more processors, when executing instructions stored in the memory, are configured to: cause the UE to receive a configuration of pre-assigned resources in a plurality of sub-channels for sidelink (SL) communication; perform a clear sub-channel assessment (CCA) process in at least one of the plurality of sub-channels; determine, during the execution of the CCA process, a resource selection window including candidate resources in a subset of the pre-assigned resources; perform a resource selection process on the candidate resources in the resource selection window to determine transmission resources in at least two of the plurality of sub-channels; and transmit data using the transmission resources based on results of the CCA process.

[0109] Example 43 includes the subject matter of Example 42, and may include or omit any element, wherein the one or more processors are configured to: cause the UE, in response to data arriving for SL transmission, to perform a CCA process on each of a plurality of subchannels; select, for a resource selection window, candidate resources in a first subchannel of the plurality of subchannels for which the corresponding CCA reaches a threshold level for completion; select, for the resource selection window, candidate resources in a second subchannel of the plurality of subchannels; and, where the resource selection window does not include candidate resources in other subchannels of the plurality of subchannels, perform a resource selection process on the candidate resources in the resource selection window to determine the transmission resources.

[0110] Example 44 includes the subject matter of Example 42, and may include or omit optional elements, wherein the one or more processors are configured to: cause the UE to initiate a CCA process in a selected one of the plurality of subchannels in response to data arriving for an SL transmission; select candidate resources in all of the plurality of subchannels for a resource selection window in response to the CCA process reaching a threshold level of completion; and perform a resource selection process in the resource selection window to determine transmission resources in a first subchannel and a second subchannel of the plurality of subchannels.

[0111] Example 45 includes the subject matter of Example 42, and may include or omit any element, wherein the one or more processors are configured to cause the UE to select a subchannel on which CCA is performed as the first subchannel or the second subchannel.

[0112] Example 46 is a method that includes any action or combination of actions substantially as described in the detailed description herein.

[0113] Example 47 is a method substantially as described with reference to each and any combination of the figures contained herein, or with reference to each and any combination of the paragraphs of the detailed description herein.

[0114] Example 48 is a user equipment configured to perform any of the actions or any combination of actions substantially described as being included in the user equipment in the detailed description of the present specification.

[0115] Example 49 is a network node configured to perform any of the actions or any combination of actions substantially as described herein as being included in the network node in the detailed description of the invention.

[0116] Example 50 is a non-transitory computer-readable medium storing instructions that, when executed, result in the performance of any action or combination of actions substantially as described in the detailed description of the present specification.

[0117] While the method is illustrated and described above as a series of acts or events, it is understood that the illustrated order of such acts or events should not be construed in a limiting sense. For example, some acts may occur in a different order and / or concurrently with other acts or events other than those illustrated and / or described herein. In addition, not all illustrated acts are required to implement one or more aspects or embodiments of the present disclosure. Also, one or more of the acts depicted herein may be performed in one or more separate acts and / or phases. In some embodiments, the above-described method may be implemented on a computer-readable medium using instructions stored in a memory. Many other embodiments and variations are possible within the scope of the claimed disclosure.

[0118] The term "couple" is used throughout this specification. This term can encompass any connection, communication, or signal path that enables a functional relationship consistent with the description of this disclosure. For example, in a first example, device A is coupled to device B when device A generates a signal to control device B to perform an action, or in a second example, device A is coupled to device B through an intervening component C such that device B is controlled by device A via a control signal generated by device A, where intervening component C does not substantially change the functional relationship between device A and device B.

[0119] It is well understood that use of personally identifiable information should comply with generally recognized privacy policies and practices that meet or exceed industry or government requirements for maintaining user privacy. In particular, personally identifiable information data should be managed and handled in a manner that minimizes the risk of unintended or unauthorized access or use, and the nature of authorized use should be clearly indicated to users.

Claims

1. 1. An apparatus for user equipment (UE) operating in an unlicensed spectrum, comprising: one or more processors, the one or more processors causing the UE to: receiving a configuration of pre-allocated resources in a plurality of sub-channels for sidelink (SL) communications; performing a clear subchannel assessment (CCA) process on at least one of the plurality of subchannels; determining a resource selection window comprising candidate resources in the subset of pre-allocated resources; performing a resource selection process on the candidate resources in the resource selection window to determine transmission resources for at least two of the plurality of subchannels; An apparatus configured to cause data to be transmitted using the transmission resource based on a result of the CCA process.

2. The apparatus of claim 1 , wherein the one or more processors are configured to perform the CCA process on at least one of the plurality of sub-channels before performing the resource selection process.

3. 2. The apparatus of claim 1, wherein the one or more processors are configured to perform the resource selection process to select at least two subchannels, and then perform the CCA process for at least one of the selected at least two subchannels.

4. The apparatus of claim 1 , wherein the one or more processors are configured to initiate the resource selection process while performing the CCA process for the one or more of the plurality of sub-channels.

5. 2. The apparatus of claim 1, wherein the one or more processors are configured to select candidate resources in a first subchannel and a second subchannel as the transmission resource, the second subchannel being adjacent to the first subchannel.

6. 2. The apparatus of claim 1, wherein the one or more processors are configured to select candidate resources in a first subchannel and a second subchannel as the transmission resource, the second subchannel being adjacent or non-adjacent to the first subchannel.

7. 2. The apparatus of claim 1, wherein the one or more processors are configured to determine that a CCA process in a subchannel is successful when a separate CCA process in each resource block set of the subchannel is successfully completed.

8. 2. The apparatus of claim 1, wherein the one or more processors are configured to select a set of adjacent resource blocks within each of the at least two subchannels of the plurality of subchannels for the transmission resources.

9. 2. The apparatus of claim 1, wherein the one or more processors are configured to select for the transmission resources a set of adjacent resource blocks or non-adjacent resource blocks within each of the at least two subchannels of the plurality of subchannels.

10. 2. The apparatus of claim 1, wherein the one or more processors are configured to reset an N counter associated with the CCA process corresponding to a subchannel selected for the transmission resource in response to arrival of new data traffic for SL transmission.

11. 2. The apparatus of claim 1, wherein the one or more processors are configured to reset an N counter associated with the CCA process corresponding to all of the plurality of subchannels in response to arrival of new data traffic for SL transmission.

12. 2. The apparatus of claim 1, wherein the one or more processors are configured to, in response to arrival of new data traffic for SL transmission, generate a new random value for N and reset an N counter associated with the CCA process corresponding to the subchannel selected for the transmission resource.

13. 2. The apparatus of claim 1, wherein the one or more processors are configured to generate a new random value for N and reset N counters associated with the CCA processes corresponding to all of the plurality of subchannels in response to arrival of new data traffic for SL transmission.

14. 2. The apparatus of claim 1, wherein the one or more processors are configured to perform a confirmatory listen-before-talk (LBT) on a frequency resource of the transmission resource before transmitting the data.

15. The apparatus of claim 14 , wherein the confirmation LBT includes a Type 2 CCA.

16. 15. The apparatus of claim 14, wherein the one or more processors are configured to trigger a Layer 1 (L1) LBT failure indication when the confirmation LBT fails.

17. The apparatus of claim 1 , wherein the one or more processors are configured to trigger an L1 LBT failure indication in response to a failure of a CCA process in one subchannel.

18. 2. The apparatus of claim 1, wherein the one or more processors are configured to trigger an L1 LBT failure indication in all selected subchannels in response to a failure of a CCA process in one selected subchannel.

19. The apparatus of claim 1 , wherein the CCA process comprises a Type 1 CCA.

20. 2. The apparatus of claim 1, wherein the one or more processors are configured to: cancel the PSFCH in the first subchannel and transmit the PSFCH in the second subchannel when the transmission includes a physical sidelink feedback channel (PSFCH) in a first subchannel and a second subchannel; and when a CCA process in the first subchannel fails and a CCA process in the second subchannel succeeds.

21. 2. The apparatus of claim 1, wherein the one or more processors are configured to: cancel the PSFCH in the first subchannel and the PSFCH in the second subchannel when the transmission includes a physical sidelink feedback channel (PSFCH) in a first subchannel and a second subchannel; and when a CCA process in the first subchannel fails and a CCA process in the second subchannel succeeds.

22. 1. A user equipment (UE) configured to operate in an unlicensed spectrum, comprising: Memory and One or more processors that, when executing instructions stored in the memory, cause the UE to: receiving a configuration of pre-allocated resources in a plurality of sub-channels for sidelink (SL) communications; performing a clear subchannel assessment (CCA) process on at least one of the plurality of subchannels; After performing the CCA process, determining a resource selection window comprising candidate resources in the subset of pre-allocated resources; performing a resource selection process on the candidate resources in the resource selection window to determine transmission resources for at least two of the plurality of subchannels; and one or more processors configured to cause data transmission using the transmission resources based on a result of the CCA process.

23. The one or more processors, in response to the data arriving for SL transmission at the UE, performing the CCA process on each of the plurality of sub-channels; selecting, for the resource selection window, a candidate resource in a first sub-channel of the plurality of sub-channels for which a corresponding CCA process is successfully completed; selecting, for the resource selection window, a candidate resource in a second sub-channel of the plurality of sub-channels based on a successful completion of a corresponding CCA process in the second sub-channel; the resource selection window does not include candidate resources in other sub-channels of the plurality of sub-channels; 23. The UE of claim 22, configured to cause the resource selection process to be performed on the candidate resources in the resource selection window to determine the transmission resource.

24. The one or more processors, in response to the data arriving for SL transmission at the UE, performing the CCA process on a selected one of the plurality of sub-channels; responsive to successful completion of the CCA process, causing the resource selection window to select candidate resources in all of the plurality of subchannels; 23. The UE of claim 22, configured to cause the resource selection process to run in the resource selection window to determine the transmission resources in a first subchannel and a second subchannel of the plurality of subchannels.

25. 23. The UE of claim 22, wherein the one or more processors are configured to cause the UE to select the subchannel on which the CCA is performed as a first subchannel or a second subchannel of the transmission resource.

26. 1. A method for a user equipment (UE) operating in an unlicensed spectrum, comprising: receiving a configuration of pre-allocated resources in a plurality of sub-channels for sidelink (SL) communication; determining a resource selection window that includes candidate resources in the subset of pre-allocated resources; performing a resource selection process on the candidate resources in the resource selection window to determine transmission resources for at least two of the plurality of subchannels; performing a clear subchannel assessment (CCA) process on at least one of the plurality of subchannels after determining the transmission resource; and transmitting data using the transmission resource based on a result of the CCA process.

27. In response to the data arriving for SL transmission, selecting a resource selection window including candidate resources in a first subchannel and a second subchannel of the plurality of subchannels; performing the resource selection process in the resource selection window to determine the transmission resources; performing the CCA process in the first sub-channel and the second sub-channel; and transmitting the data on the transmission resource in response to successful completion of the CCA process on the first sub-channel and the second sub-channel prior to the transmission resource.

28. In response to the data arriving for SL transmission, selecting a resource selection window including candidate resources in a first subchannel and a second subchannel of the plurality of subchannels; performing the resource selection process in the resource selection window to determine the transmission resources; initiating the CCA process in a selected one of the first sub-channel and the second sub-channel; and transmitting the data on the transmission resource in response to successful completion of the CCA process on the selected one of the first subchannel and the second subchannel prior to the transmission resource.

29. 1. An apparatus for user equipment (UE) operating in an unlicensed spectrum, comprising: Memory and One or more processors that, when executing instructions stored in the memory, cause the UE to: receiving a configuration of pre-allocated resources in a plurality of sub-channels for sidelink (SL) communications; performing a clear subchannel assessment (CCA) process on at least one of the plurality of subchannels; determining, during the CCA process, a resource selection window that includes candidate resources in the subset of pre-allocated resources; performing a resource selection process on the candidate resources in the resource selection window to determine transmission resources for at least two of the plurality of subchannels; one or more processors configured to cause data to be transmitted using the transmission resources based on a result of the CCA process.

30. The one or more processors, in response to the data arriving for SL transmission at the UE, performing the CCA process on each of the plurality of sub-channels; selecting, for the resource selection window, a candidate resource in a first subchannel of the plurality of subchannels for which a corresponding CCA reaches a threshold level of completion; causing the resource selection window to select candidate resources in a second sub-channel of the plurality of sub-channels; the resource selection window does not include candidate resources in other sub-channels of the plurality of sub-channels; 30. The apparatus of claim 29, configured to cause the resource selection process to be performed on the candidate resources in the resource selection window to determine the transmission resource.

31. The one or more processors, in response to the data arriving for SL transmission at the UE, Initiating the CCA process on a selected one of the plurality of sub-channels; responsive to the CCA process reaching a threshold level of completion, causing the resource selection window to select candidate resources in all of the plurality of subchannels; 30. The apparatus of claim 29, configured to cause the resource selection process to perform the resource selection process in the resource selection window to determine the transmission resources in a first sub-channel and a second sub-channel of the plurality of sub-channels.

32. 30. The apparatus of claim 29, wherein the one or more processors are configured to cause the UE to select the subchannel on which the CCA is performed as a first subchannel or a second subchannel.

33. 1. An apparatus for user equipment (UE) operating in an unlicensed spectrum, comprising: one or more processors, the one or more processors causing the UE to: receiving an assignment of sidelink (SL) resources in response to data arriving for SL transmission to another UE, the assigned SL resources including candidate resources in a plurality of subchannels; performing at least one clear subchannel assessment (CCA) process on at least one of the plurality of subchannels; performing a resource selection process based on candidate resources in a resource selection window corresponding to at least a subset of the assigned SL resources to determine transmission resources including frequency resources in at least two of the plurality of subchannels; The apparatus, configured to trigger an L1 LBT failure indication in response to a CCA process failing in at least one subchannel.

34. 34. The apparatus of claim 33, wherein the at least one CCA process includes a Type 1 CCA or a Type 2 CCA, or both a Type 1 CCA and a Type 2 CCA.

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