Method, apparatus and computer readable medium for sidelink transmission

Abstract

Sidelink transmission methods, apparatuses, and computer readable media. A method is provided that includes performing, at a first UE, LBT processing on an unlicensed band to obtain a COT for sidelink transmission, determining, at the first UE, a set of candidate sidelink resources on the unlicensed band based on channel sensing performed on the unlicensed band, wherein each candidate sidelink resource is within a sidelink resource selection window and is not associated with a reservation having a RSRP higher than a predetermined resource exclusion RSRP threshold, selecting, at the first UE, a sidelink resource from the set of candidate sidelink resources, and performing, at the first UE, a sidelink transmission from the first UE to a second UE on the selected sidelink resource within the obtained COT. Decoding, at the first UE, a plurality of SCI messages on a single PSCCH resource.

Description

[0001] Cross-referencing of related patent applications

[0002] This invention claims priority to international application PCT / CN2022 / 089978, filed on April 28, 2022, the entire contents of which are incorporated herein by reference. Technical Field

[0003] This disclosure relates to wireless communications, and more particularly to sidelink communications via unlicensed frequency bands. Background Technology

[0004] User demand for cellular system throughput is increasing year by year. Cellular systems typically operate in expensive, scarce, and bandwidth-limited licensed spectrum. Therefore, one of the most promising solutions to increase cellular network throughput is to utilize idle unlicensed frequencies for data transmission. Summary of the Invention

[0005] This disclosure provides a method comprising: at a first user equipment (UE), performing listen-before-talk (LBT) processing on an unlicensed frequency band to obtain a channel occupancy time (COT) for sidelink transmission; at the first UE, determining a set of candidate sidelink resources on the unlicensed frequency band based on channel sensing performed on the unlicensed frequency band, wherein each candidate sidelink resource is within a sidelink resource selection window and has no reservation associated with an RSRP higher than a predetermined resource exclusion reference signal received power (RSRP) threshold; at the first UE, selecting a sidelink resource from the set of candidate sidelink resources; and within the obtained COT, performing a sidelink transmission from the first UE to a second UE on the selected sidelink resource. At the first UE, decoding multiple sidelink control information (SCI) messages on a single physical sidelink control channel (PSCCH) resource.

[0006] In one embodiment, the method further includes: receiving the SCI decoding capability of the second UE from the second UE; and determining at least one of the size of the sidelink resource selection window and the value of the RSRP threshold based on the received SCI decoding capability of the second UE.

[0007] In one implementation, the stronger the SCI decoding capability of the second UE, the narrower the size of the sidelink resource selection window, and the stronger the SCI decoding capability of the second UE, the larger the value of the RSRP threshold.

[0008] In one implementation, the reported SCI decoding capability is indicated by at least one of the following: the maximum number of SCIs decoded per PSCCH resource for the second UE, the maximum number of SCIs decoded per time slot, the maximum number of SCIs decoded per symbol, the maximum number of SCIs decoded per subchannel, the maximum number of SCIs decoded per resource pool, the maximum number of SCIs decoded per bandwidth part (BWP), the maximum number of SCIs decoded per frequency band, the maximum number of SCIs decoded per link pair for the second UE, and the maximum number of SCIs decoded by the second UE for each receiving device.

[0009] In one embodiment, decoding the plurality of SCI messages further includes: decoding the plurality of SCI messages in order of signal strength, such that the SCI message with a stronger signal strength is decoded first, and then the SCI message with a weaker signal strength is decoded.

[0010] In one embodiment, the method further includes: at a first UE, decoding multiple SCI messages on a single PSCCH resource to collect resource reservation information from a nearby sidelink UE; at the first UE, generating selection assistance information based on the collected resource reservation information; and reporting the generated selection assistance information from the first UE to a third UE for sidelink reception from the third UE.

[0011] In one implementation, the generation step further includes: at the first UE, generating an indication of preferred resources as generated selection assistance information, wherein the preferred resources are identified by the first UE as resources preferred for sidelink reception based on collected resource reservation information.

[0012] In one implementation, the generation step further includes: at the first UE, generating an indication of a non-preferred resource as generated selection assistance information, wherein the non-preferred resource is identified by the first UE as a resource that is not preferred for sidelink reception based on collected resource reservation information.

[0013] In one implementation, the generation step further includes: at the first UE, generating an indication of conflicting resources as generated selection aid information, wherein the conflicting resources are identified as resources that conflict when receiving from the side link of the third UE, based on the plurality of SCIs decoded on the PSCCH resources.

[0014] In one embodiment, the method further includes: receiving from a second UE a selection assistance information report indicating preferred resources, non-preferred resources, and / or potentially conflicting resources; and at a first UE, selecting a sidelink resource from the group of candidate sidelink resources based on the reported selection assistance information.

[0015] In one implementation, the determining step further includes: at the first UE, performing channel sensing by decoding the plurality of SCI messages on a single PSCCH resource to collect resource reservation information from nearby sidelink UEs; and at the first UE, determining the group of candidate sidelink resources based on the collected resource reservation information.

[0016] In one embodiment, the execution step further includes: decoding the plurality of SCI messages in order of signal strength, such that the SCI message with a stronger signal strength is decoded first, and then the SCI message with a weaker signal strength is decoded.

[0017] In one embodiment, the method further includes: receiving the SCI decoding capability of the second UE from the second UE; and at the first UE, selecting a conflicting resource as the selected sidelink resource based on the received SCI decoding capability and the priority level of the sidelink transmission to be performed, wherein the conflicting resource is reserved by a nearby sidelink UE.

[0018] This disclosure also provides an apparatus comprising circuitry configured to: at a first UE, perform LBT processing on an unlicensed frequency band to obtain a COT for sidelink transmission; at the first UE, determine a set of candidate sidelink resources on the unlicensed frequency band based on channel sensing performed on the unlicensed frequency band, wherein each candidate sidelink resource is within a sidelink resource selection window and has no reservations associated with an RSRP higher than a predetermined resource exclusion RSRP threshold; at the first UE, select a sidelink resource from the set of candidate sidelink resources; and within the obtained COT, perform a sidelink transmission from the first UE to a second UE on the selected sidelink resource. At the first UE, decode multiple SCI messages on a single PSCCH resource.

[0019] This disclosure also provides a non-transitory computer-readable medium that stores instructions. When executed by a processor, these instructions can cause the processor to perform the methods described above. Attached Figure Description

[0020] Various embodiments of this disclosure will be described in detail with reference to the following accompanying drawings, in which similar reference numerals denote similar elements, and wherein:

[0021] Figure 1 An example of a Type 1LBT process 100 according to some embodiments of this disclosure is shown;

[0022] Figure 2 The LBT duration 200 for type 1 LBT processing is shown, followed by the COT duration 213;

[0023] Figure 3 An example of Mode 2 resource allocation according to some embodiments of this disclosure is shown;

[0024] Figure 4 An example of side link transmission between transmitting device 420 and receiving device 410 according to some embodiments of the present disclosure is shown;

[0025] Figure 5 An example of side link transmission between transmitting device 520 and receiving device 510 according to some embodiments of the present disclosure is shown;

[0026] Figure 6 An example of side link transmission between transmitting device 620 and receiving device 610 according to some embodiments of the present disclosure is shown;

[0027] Figure 7 An example of side link transmission between transmitting device 720 and receiving device 710 according to some embodiments of the present disclosure is shown;

[0028] Figure 8 Exemplary processing 800 according to some embodiments of this disclosure is shown; and

[0029] Figure 9 An exemplary apparatus 900 according to some embodiments of the present disclosure is shown. Detailed Implementation

[0030] I. Sidelink over Unlicensed Spectrum (SL-U)

[0031] The UE can perform sidelink transmissions on unlicensed frequency bands. For example, the UE can perform sidelink sensing, sidelink resource selection, and sidelink transmissions simultaneously while performing channel access processing (e.g., LBT processing). The unlicensed frequency band may already be occupied (e.g., by a Wi-Fi network). Channel access processing can meet specification requirements to allow different radio access technologies (RATs) to share the unlicensed frequency band fairly.

[0032] For example, the process of an SL device transmitting on an unlicensed frequency band can be performed as follows: The SL device (SL UE) obtains the SL sensing window configuration from the network. For example, during sensing processing, the SL device senses and decodes SL control information (SCI) on PSCCH resources within the SL sensing window. Based on the sensing results from the sensing processing, the SL device can determine a candidate side traversal resource set. The SL device performs SL resource selection on the candidate side traversal resource set to select and reserve transmission opportunities (or transmission resources). The SL device can acquire one or more COTs by triggering one or more LBT processes. The SL device transmits on the selected / reserved transmission opportunities within the COT.

[0033] This invention discloses an operational method for an SL device to transmit on an unlicensed frequency band. This operational method satisfies the specification requirements for operating on an unlicensed frequency band (including LBT processing for acquiring COT) while adhering to SL resource allocation rules. The technology disclosed in this invention solves the following problems: (i) the LBT category and processing used by an SL device to access an unlicensed frequency band channel; and (ii) SL-U operation combining LBT processing and an SL resource allocation scheme. For example, the SL resource allocation scheme can be similar to sidelink resource allocation mode 2 specified in the standard specification developed by the 3rd Generation Partnership Project (3GPP). Examples of LBT categories and corresponding channel access processing are described in this disclosure. An example of baseline operation of an SL device accessing an unlicensed frequency band channel based on LBT processing and SL resource allocation mode 2 is described.

[0034] In some implementations, the LBT category and processing employed by the SL device can be similar to New Radio (NR) uplink (UL) shared spectrum channel access processing type 1 or type 2. In some implementations, LBT-based SL transmissions can have two scenarios:

[0035] - (Scenario 1) Obtain the initial COT for transmission.

[0036] - (Scenario 2) Share COT from other SL devices.

[0037] For example, in out-of-COT operation, an initial COT can be obtained for transmission. The SL device can apply an out-of-COT LBT to obtain the initial COT. For example, Type 1 Channel Access (LBT CAT4) can be applied. Type 1 LBT can be an LBT process with a random back-off and a variable-sized clear-channel assessment (CCA) period. For example, the initial value of the countdown timer (or counter) used in the random back-off can be randomly drawn from a variable-sized contention window. The size of this contention window can change based on channel dynamics.

[0038] For example, in In-COT operation, an SL UE can share a COT from other SL devices or share a COT used for multiple SL transmissions. SL devices can apply In-COT LBTs to share the COT. In some examples, the In-COT LBT type can be determined based on the COT owner's instructions. In some examples, the In-COT LBT type can be determined as Type 1 LBT (i.e., with random backoff). In some examples, the In-COT LBT type can be determined based on the transmission time interval. For example, Type 2A / 2B / 2C LBTs (i.e., without random backoff) can be used.

[0039] II. Channel Access Processing Based on LBT Mechanism

[0040] The following describes LBT-based channel access processing (LBT processing) and related parameters according to embodiments of this disclosure.

[0041] In this disclosure, a channel can refer to a shared spectrum (such as an unlicensed band) containing radio resources for performing channel access processing. Channel access processing (such as LBT processing) can be based on sensing the availability of the channel for performing transmissions. The basic unit for sensing can be a sensing time slot T. sl For example, a sensing time slot can have a duration T. sl = 9μs. If the UE senses the channel during the sensing slot duration and determines that the detection power is less than the energy detection threshold X for at least 4μs during the sensing slot duration. Thresh Then it is assumed that the duration of the sensing time slot T sl It is idle. Otherwise, the duration T of the sensing time slot is considered to be... sl It's busy.

[0042] Channel occupancy refers to the transmission performed on the channel by the UE after performing the corresponding channel access process. COT refers to the total time that the UE and any UEs sharing the channel occupancy perform transmissions on the channel after the corresponding channel access process. In some examples, to determine COT, if the transmission gap is less than or equal to, for example, 25 μs, the gap duration can be counted within the channel occupancy time. Channel occupancy time can be shared for transmissions between UEs.

[0043] In some examples, an SL transmission burst can be a group of transmissions from the UE without any gaps greater than a predefined threshold (such as 16 μs). Transmissions from the UE separated by gaps greater than the predefined threshold can be considered as separate SL transmission bursts. The UE can send transmissions after gaps within an SL transmission burst without sensing the availability of the corresponding channel.

[0044] In some examples, SL transmission is performed according to either Type 1 or Type 2 SL channel access processing (Type 1 or Type 2 SL LBT processing). For Type 1 SL channel access processing (Type 1 LBT), the duration spanned by the sensing slots sensed as idle prior to SL transmission is random. In some examples, the SL UE may perform Type 1 channel access processing as follows: The SL UE may first perform a deferral of duration T. d The sensing channel is idle during the duration of the sensing time slot. Then, the SL UE can perform the following steps: 1) Set N=N init , where N init It is uniformly distributed between 0 and CW p (Random number between the contention window) and proceed to step 4; 2) If N>0 and the UE chooses to decrement the counter, then set N=N-1; 3) Sensing the channel during the additional sensing slot duration, if the additional sensing slot duration is idle, then proceed to step 4; otherwise, proceed to step 5; 4) If N=0, then stop; otherwise, proceed to step 2; 5) Sensing the channel until the additional delay duration T d The busy sensing slot is detected within the time slot, or until the additional delay duration T is reached. d All sensing slots are detected as idle; 6) If the additional delay duration T d If the channel is sensed to be idle during all sensing time slot durations, proceed to step 4; otherwise, proceed to step 5.

[0045] In some examples, if the UE is ready to transmit at least for the sensing time slot duration T sl If the channel is detected to be idle, and if the delay duration T immediately preceding the transmission... dIf the channel is sensed to be idle during all sensing time slot durations, the SL UE can transmit on the channel. In some examples, the delay duration T... d Including duration T f =16μs, followed by m p The duration of each continuous sensing time slot. For example, the duration of each sensing time slot is T. sl = 9μs. For example, T f =16μs. T f Including those located in T f The duration T of the idle sensing slot at the beginning sl .

[0046] In some examples, the competition window size CW p From such as CW min,p ≤CW p ≤CW max,p Choose from the range. For example, CW p Adjustments can be made based on channel load conditions. The lower bound of the contention window size, CW. min,p and upper limit CW max,p This can be selected before step 1 of the above process. It can be determined based on the channel access priority class (CAPC) p associated with the current SL transmission. The COT of the current SL transmission can also be determined based on parameter m of CAPC. p CW min,p and CW max,p Table 1 shows examples of SL LBT processing parameters associated with CAPC.

[0047] Table 1

[0048]

[0049] For Type 2 SL channel access processing (Type 2 LBT processing), the duration of the sensing slot that is sensed as idle before SL transmission can be deterministic. In some examples, for Type 2A SL channel access processing (Type 2A SLBT processing), the SL UE can sense that the channel is idle (e.g., at least until the sensing interval T). short_ul Transmission will begin immediately after 25 μs. short_ul It can include duration T f =16μs, followed by a sensing time slot. T f Including those located in T f The sensing time slot at the beginning. If T is sensed. short_ul If all detection time slots are idle, the channel is considered to have been idle for T. short_ul .

[0050] In some examples, for Type 2B SL channel access processing (Type 2B SL LBT processing), the UE can, for example, T f Transmission is initiated immediately after the channel is detected to be idle within a duration of 16 μs. f Included in T f The sensing time slot occurs after the last 9 μs. For example, if the channel is sensed as idle for at least 5 μs (of which at least 4 μs of sensing occurs within the sensing time slot), then the channel is considered to be idle for a duration T. f The channel is idle. In some examples, for Type 2C SL channel access processing (Type 2C SL LBT processing), the UE does not sense the channel before transmission. For example, the duration of the corresponding UL transmission is at most 584 μs.

[0051] Figure 1 An example of a Type 1 Channel Access (LBT CAT4) process 100 according to an embodiment of this disclosure is shown. Process 100 may include three separate parts forming a loop: initial CCA processing (or procedure) 110, random backoff processing (or procedure) 120, and self-delayed transmission 130. The UE may perform process 100 to access a side-link channel on an unlicensed frequency band. Process 100 begins at step S111.

[0052] In step S111, the UE can operate in idle state. In step S112, it is determined whether to perform transmission. If transmission is to be performed, process 100 proceeds to step S113. If transmission is not performed, process 100 returns to step S111. In step S113, the UE delays for a duration T. d The sensing channel is checked for idleness during the duration of the sensing time slot. If the channel is idle throughout all sensing time slots, process 100 proceeds to step S121 and enters random backoff process 120. Otherwise, process 100 repeats the operation of step S113.

[0053] In step S121, the UE is between 0 and CW p A random counter value N is generated within the contention window. Contention window adjustment processing (or procedure) S126 can be performed at step S121 based on the channel loading state. In step S122, the UE can decrement the counter by 1. In step S123, the UE performs channel sensing within the sensing time slot. If the channel is idle within the sensing time slot, process 100 proceeds to step S124. Otherwise, process 100 proceeds to step S125. In step S125, the UE performs channel sensing within different durations T. dDuring this period, channel sensing is repeated until the channel is idle. Then, process 100 returns to step S122. In step S124, if the counter value is equal to 0, the process proceeds to step S131 and enters self-delayed transmission 130. Otherwise, the process returns to step S122.

[0054] In step S131, it is determined whether the UE is ready to transmit. If the UE is ready to transmit, process 100 proceeds to step S132. Otherwise, process 100 proceeds to step S133. In step S133, the UE can operate in an idle state. In step S134, it is determined whether to perform a transmission. If a transmission is to be performed, process 100 proceeds to step S135. Otherwise, process 100 returns to step S133. In step S135, the UE delays for a duration T. d The channel is sensed during the sensing time slot. If the channel is delayed for a duration T... d If the process is idle, then process 100 proceeds to step S131. Otherwise, the process returns to step S113.

[0055] Figure 2 The diagram illustrates the LBT duration 200 for Type 1 LBT processing, followed by the COT duration 213. As shown, the LBT duration comprises two parts: a delay duration 211 and a backoff duration 212. Variables used to determine the LBT duration 200 and COT duration 213 can be configured according to priority levels. For example, the backoff duration 212 can be determined based on the number of sensing slots randomly generated according to the contention window (CW). The size of the contention window can be determined based on the priority level of the associated SL transmission (e.g., CAPC). The COT duration 213 is the maximum channel occupancy time T. maximum cot The maximum channel occupancy time T can also be determined based on the priority level of the relevant SL transmission (e.g., CAPC). maximumco t.

[0056] exist Figure 2 In the example, the minimum time length for LBT processing can be the delay duration 2^11(T) d The sum of the LBT duration and the backoff duration 212 (sensing slot duration). The number of sensing slots (denoted as N) can randomly roll between 0 and the CW size. Therefore, in some examples, the LBT duration (or LBT time) can be expressed as follows:

[0057] LBT duration (LBT time) = T d +T sl *N.

[0058] III. Sidelink Mode 2 Resource Allocation

[0059] The following describes the processing and parameters for SL channel sensing and resource selection in resource allocation mode 2 according to embodiments of this disclosure.

[0060] In some examples, PSCCH and physical sidelink shared channel (PSSCH) resources can be defined within the resource pool of the corresponding channel. The SL UE can perform resource selection based on sensing within the resource pool. The resource pool can be divided into sub-channels in the frequency domain. Resource allocation, sensing, and resource selection can be performed on a sub-channel basis. There are two SL resource allocation modes: Mode 1 and Mode 2 in various implementations. Mode 1 can be used for resource allocation performed by the base station (BS). Mode 2 can be used for UE-autonomous resource selection (without involving the BS).

[0061] Figure 3 An example of Mode 2 resource allocation according to some embodiments of this disclosure is shown. The UE performs sensing within a (pre-)configured resource pool to determine which resources are not being used by other UEs with higher priority services. Therefore, the UE can select an appropriate number of such resources for transmission. The UE can transmit and retransmit a certain number of times on the selected resources.

[0062] For example, resource reservation information can be carried in the SCI (such as the first-level SCI) of the current transport block. The SCI can also be carried in the PSCCH. The sensing UE can monitor sensing window 301 to decode the PSCCH of other UEs, thereby obtaining which resources have been reserved. The sensing UE can also measure the SL reference signal received power (SL-RSRP) in the time slot of sensing window 301. In this way, the sensing UE can collect sensing information including the reserved resources associated with sensing window 301 and the SL-RSRP measurement results. For example, service arrival or reselection triggering can occur in time slot n. Sensing window 301 can begin at a past time slot [n-T0] and end at a time shortly before time slot n [n-T0proc]. For example, sensing window 301 can be 1100ms or 100ms wide. The 100ms option can be used for non-periodic services. The 1100ms option can be used for periodic services.

[0063] The sensing UE can then select resources for (re)transmission from within selection window 302. For example, selection window 302 can begin in time slot [n+T1] shortly after the trigger for (re)selecting resources and end in time slot [n+T2]. T2 cannot be longer than the remaining delay time budget of the packet to be transmitted. Resources reserved in the selection window with an SL-RSRP above a threshold can be excluded as candidates by the sensing UE. This threshold can be set according to the priority of the services of the sensing and transmitting UEs. For example, higher-priority transmissions from the sensing UE can occupy resources reserved by a transmitting UE with sufficiently low SL-RSRP and sufficiently low-priority services.

[0064] In some examples, the UE can randomly select an appropriate amount of resources from this non-exclusion set. The selected resources are typically not periodic. Up to three resources can be indicated in each SCI transmission, each of which can be located independently in time and frequency. In some cases, the indicated resources can be reserved for a semi-persistent transmission in another transmission block. In some examples, shortly before transmission with the reserved resources, the sensing UE re-evaluates its set of available resources to check if its intended transmission is still appropriate. For example, a late-arriving SCI can instruct a non-periodic, higher-priority service to begin transmission after the original sensing window has ended. If the reserved resources are not part of the set used for selection, new resources are selected from the updated resource selection window.

[0065] IV. Sidelink UE Operation Design

[0066] 1. Problems and Key Points

[0067] In various implementations, sidelink UE operation can be designed to address scenarios where the sidelink device acquires an initial COT for transmission and obtains transmission resources through sidelink resource allocation mode 2. 3GPP TS38.214 provides further examples of sidelink resource allocation mode 2. For SL UE operation, two desired behaviors can be:

[0068] - The SL device performs a Type 1 Channel Access (LBT CAT4) procedure to obtain the COT for transmission;

[0069] - The SL device follows SL resource allocation mode 2 to perform SL sensing and resource selection.

[0070] In some implementations, the following four issues were identified in order to combine SL resource allocation mode 2 and LBT processing.

[0071] 1) Significant transmission delay

[0072] Performing SL resource selection requires random resource selection within the SL selection window. However, a larger selection window length leads to increased transmission latency. Furthermore, to improve packet decoding success rate and reduce interference, a larger selection window is needed to obtain more candidate resource options and avoid conflicting transmission slots.

[0073] Therefore, using an LBT random backoff window with a collision avoidance mechanism and a large SL selection window length both lead to significant transmission delays.

[0074] 2) Hidden Node Issues

[0075] While the LBT process and SL resource selection can help reduce potential interference and ensure idle channels during transmission, they cannot completely eliminate the "hidden node" problem.

[0076] For example, during channel sensing, the transmitting UE may have difficulty detecting all sources that could potentially interfere with the receiving UE, resulting in some nodes going undetected. As a result, transmissions may still conflict with transmissions between these hidden nodes and the receiving UE, leading to decoding failures.

[0077] 3) Incoordination of SL UE operations

[0078] In a common SL UE (Service Link Entity) operation scenario, Internet of Things (IoT) devices are served by another device owned by the same user. For example, a user's smartwatch is typically served by his or her own smartphone. In such cases, the pairing of SL services is not based on the best service link quality between the two devices, but rather on the fact that the two devices belong to the same owner.

[0079] However, for example, when the service RSRP of such a service SL pair is low, incoordination issues may occur. That is, transmissions within the service pair may be overpowered by nearby SL transmissions with better service link quality.

[0080] 4) The inapplicability of HARQ retransmission to control channel transmission

[0081] The Hybrid Automatic Repeat Request (HARQ) retransmission mechanism can be used to ensure reliable data transmission even in noisy and interference-prone environments. However, this mechanism is not suitable for control channel transmission.

[0082] For example, in one scenario, the SCI message sent by the UE might conflict with an SCI sent by an interfering device on the same resource. The interfering SCI might have higher power on the receiving UE side. The receiving UE blindly decoding the control signal at higher power might cause the decoding of the desired SCI to fail. Since the HARQ mechanism cannot remedy the failure of control channel transmission, the decoding failure of the desired control signal will ultimately lead to the decoding failure of the data channel.

[0083] 2. Solution

[0084] In sidelink communication, the transmitting UE and the receiving UE typically sense and decode only one SCI message on the control channel resource. However, multiple SL UEs may be transmitting their own SCI messages on the same control channel resource. Given the limited decoding capabilities of the SL UEs, under normal circumstances, these SL UEs will only decode the SCI message with the highest power on the control channel resource, ignoring SCI messages with lower power levels.

[0085] To address the issues mentioned above, multi-SCI sensing / decoding methods are employed in various implementations. The following features can be combined to provide advantages over conventional methods.

[0086] 1) Multi-SCI decoding operation

[0087] At least one of the transmitting UE and the receiving UE can decode multiple SCI messages on a single PSCCH resource. The maximum number of decoded SCI messages can be determined by the UE's decoding capability. The UE can decode multiple SCI messages in order of signal strength. For example, the device can decode a first SCI with the highest power, then decode a second SCI with the second highest power, and so on, until the UE's maximum SCI decoding capability is reached.

[0088] 2) The receiving UE reports its SCI decoding capability to the sending UE.

[0089] The receiving UE can report its SCI decoding capabilities to the transmitting UE. This information can help the transmitting UE select resources.

[0090] 3) The transmitting UE performs resource selection based on the receiving UE's SCI decoding capability.

[0091] Knowing the receiving UE's SCI decoding capabilities, the transmitting UE can adjust accordingly or adopt different resource selection strategies. Two examples are provided below.

[0092] A) Shorter selection window and / or larger SL resource exclusion RSRP threshold

[0093] As described above, the transmitting UE selects resources for transmission within a selection window. If a reserved resource within the selection window has an SL-RSRP higher than a certain threshold, the transmitting UE excludes that reserved resource from being considered a candidate resource.

[0094] Because the receiving UE has the ability to decode multiple SCI messages on a single PSCCH resource, it is resilient to potential interference or conflicting SL transmissions. This means that even if the signal of the desired SCI is not the strongest signal on the corresponding SL resource on the receiving UE's side, the receiving UE can still decode the SCI. Therefore, the transmitting UE can use a shorter selection window length and / or a stricter (or higher) resource exclusion threshold in resource selection. This effectively reduces latency in the desired transmission.

[0095] B) Preemption of SL transmission

[0096] Given the receiving UE's multi-SCI decoding capability, the transmitting UE can decide to preempt the transmissions of other SL devices to send packets with higher priority. Since the receiving UE can decode multiple SCI messages on a single control channel resource, it can still maintain good decoding performance even in conflicting transmissions.

[0097] 4) Transmit the UE to perform resource selection based on its multiple SCI sensing results.

[0098] When the transmitting UE performs sensing within the SL sensing window, the ability to decode multiple SCI messages is beneficial for collecting more resource reservation information from other SL devices. During resource selection, this resource reservation information can be used to make better selection decisions and avoid collisions during transmission. The problem of SCI decoding failures caused by hidden node interference can also be mitigated by the multi-SCI decoding capability of the transmitting and / or receiving UEs.

[0099] V. Non-limiting implementation of multi-SCI decoding solutions

[0100] Based on the above design concept, several implementation methods are illustrated below. These implementation methods include the following four scenarios:

[0101] Scenario 1: The receiving UE reports its decoding capability to the sending UE for resource selection.

[0102] Scenario 2: The receiving UE performs sensing / decoding of multiple SCI messages to help the sending UE select transmission resources. Scenario 3: The sending UE performs sensing / decoding of multiple SCI messages to select transmission resources.

[0103] Scenario 4: The receiving UE reports its decoding capability to the sending UE for resource preemption.

[0104] 1. Case 1: The receiving UE reports its decoding capability to the sending UE for resource selection.

[0105] Figure 4 An example of side link transmission between transmitting device 420 and receiving device 410 according to some embodiments of this disclosure is shown. The sequential steps are described in detail below.

[0106] 1) Report SCI decoding capability

[0107] In step 415, the receiving UE 410 reports its SCI decoding capability to the transmitting UE 420. For example, the SCI decoding capability could be the maximum number of SCIs that the receiving UE 410 can decode per PSCCH resource. Non-limiting examples of SCI decoding capability could include: the maximum number of SCIs decoded per time slot, per symbol, per subchannel, per resource pool, per BWP, and per frequency band; the maximum number of SCIs that the receiving UE 410 can decode per link pair; the maximum number of SCIs that the receiving UE 410 can decode for each transmitting UE, etc.

[0108] 2) Adjust the selection window and / or the resource exclusion RSRP threshold.

[0109] Based on the decoding capability reported by the receiving UE 410, in step 425, the transmitting UE 420 may adjust the resource selection window and / or the resource exclusion RSRP threshold. For example, when the receiving UE 410 is able to decode more SCIs per PSCCH resource, the transmitting UE 420 may use a shorter selection window and / or a larger resource exclusion RSRP threshold.

[0110] 3) Resource selection based on adjusted parameters

[0111] In step 435, the transmitting UE 420 selects transmission resources based on the adjusted resource selection window and / or the resource exclusion RSRP threshold. For example, since the receiving UE 410 can tolerate transmission conflicts, the transmitting UE 420 can make a selection decision in a more proactive manner. Therefore, transmission can be performed between the transmitting UE 420 and the receiving UE 410 with shorter latency.

[0112] 4) Perform sidelink transmission on the selected resources.

[0113] In step 445, a sidelink transmission is performed on the selected resource between the sending UE 420 and the receiving UE 410.

[0114] 5) Perform multi-SCI decoding on the receiving UE side

[0115] In step 455, the receiving UE 410 can decode multiple SCI messages on a single PSCCH resource. Decoding of the multiple SCI messages can be performed in order of signal strength. Using the decoded SCI information, the receiving UE 410 can decode data transmitted on the data channel.

[0116] 2. Scenario 2: The receiving UE utilizes its multi-SCI decoding capability to perform channel sensing.

[0117] Figure 5 An example of side link transmission between transmitting device 520 and receiving device 510 according to some embodiments of this disclosure is shown. The sequential steps are described in detail below.

[0118] 1) Sensing and decoding are performed at the receiving UE side.

[0119] In step 515, the receiving UE 510 can perform channel sensing and decode multiple SCI messages on a single PSCCH resource. The decoding of multiple SCI messages can be performed in order of signal strength. Through SCI decoding, the receiving UE 510 can collect resource reservation information from nearby SL devices.

[0120] 2) Report preferred / non-preferred resources or resource conflicts

[0121] In step 525, based on the sensing and decoding results, the receiving UE 510 may generate an indication of its preferred / non-preferred resources and / or any resource conflicts, and report the information to the sending UE 520.

[0122] 3) Selection of transmission resources

[0123] In step 535, the transmitting UE 520 may make a resource selection decision taking into account preferred / non-preferred resources and / or resource conflicts reported by the receiving UE 510. By taking this information into account, transmissions between the transmitting UE 520 and the receiving UE 510 can be performed on the receiving UE side with a lower probability of interference.

[0124] 4) Perform sidelink transmission on the selected resources.

[0125] In step 545, a sidelink transmission is performed on the selected resource between the sending UE 520 and the receiving UE 510.

[0126] 3. Case 3: The transmitting UE utilizes its multi-SCI decoding capability to perform channel sensing.

[0127] Figure 6An example of side link transmission between transmitting device 620 and receiving device 610 according to some embodiments of the present disclosure is shown. The sequential steps are described in detail below.

[0128] 1) Sensing and decoding are performed on the transmitting UE side.

[0129] In step 615, the transmitting UE 620 performs channel sensing and decodes multiple SCI messages on a single PSCCH resource. The decoding of the multiple SCI messages can be performed in order of signal strength. Through SCI decoding, the transmitting UE 610 can collect resource reservation information from nearby SL devices.

[0130] 2) Selecting transmission resources based on multiple SCI decoding results

[0131] Based on the sensing and decoding results, in step 625, the transmitting UE 620 can select a transmission resource. Utilizing the ability of the transmitting UE 620 to decode multiple SCI signals on the PSCCH resource, the transmitting UE 620 can collect more reserved information from nearby SL devices. This allows the transmitting UE 620 to make a more informed selection decision while avoiding potential interference.

[0132] 3) Perform sidelink transmission on the selected resources.

[0133] In step 635, a sidelink transmission is performed on the selected resource between the sending UE 620 and the receiving UE 610.

[0134] 4. Case 4: The receiving UE reports its SCI decoding capability to the sending UE for resource preemption.

[0135] Figure 7 An example of side link transmission between transmitting device 720 and receiving device 710 according to some embodiments of this disclosure is shown. The sequential steps are described in detail below.

[0136] 1) Report SCI decoding capability

[0137] In step 715, the receiving UE 710 reports its SCI decoding capability (e.g., the maximum number of SCI decodes per PSCCH resource) to the sending UE 720.

[0138] 2) Seize the opportunity

[0139] Based on the SCI decoding capability reported by the receiving UE 710, in step 725, if the receiving UE 710 is capable of decoding multiple SCI messages and the transmission to be performed by the sending UE 720 has a higher priority, the sending UE 720 may decide to preempt resources reserved by another SL device. Since the receiving UE 710 is adaptable to transmission conflicts, the sending UE 720 can transmit on the conflicting resources.

[0140] 3) Perform sidelink transmission on the selected resources.

[0141] In step 735, a sidelink transmission is performed on the selected resource between the sending UE 720 and the receiving UE 710.

[0142] 4) Perform multi-SCI decoding on the receiving UE side

[0143] In step 745, the receiving UE 710 can decode multiple SCI messages on a single PSCCH resource. Decoding of the multiple SCI messages can be performed in order of signal strength. Using the decoded SCI information, the receiving UE 710 can decode data transmitted on the data channel.

[0144] VI. Further Examples of SL-U Access Processing

[0145] Figure 8 An SL-U channel access process 800 according to an embodiment of the present disclosure is illustrated. Process 800 can be performed at a sidelink UE pair. Process 800 begins at step S810. It should be noted that examples of the processing (or procedures) disclosed herein may include multiple steps. In various embodiments, these steps may be performed in a different order than that described in the examples. Moreover, not all of these steps need to be performed. In some embodiments, these steps may be performed in parallel.

[0146] In step S810, LBT processing can be performed on the unlicensed frequency band to obtain COT for sidelink transmission. LBT processing can be an LBT CAT4 process that includes random backoff processing. The duration of the random backoff processing can be determined by a randomly generated LBT counter (or LBT counter value).

[0147] In step S820, based on the results of the sensing operation performed on the unlicensed frequency band, multiple candidate sidelink resources can be determined on the unlicensed frequency band within the sidelink resource selection window.

[0148] In step S830, a sidelink resource can be selected from the plurality of candidate sidelink resources.

[0149] In step S840, a side link transmission from the transmitting device to the receiving device can be performed on the selected side link resources within the obtained COT.

[0150] VII. Apparatus and non-transitory computer-readable medium

[0151] Figure 9 An exemplary apparatus 900 according to embodiments of the present disclosure is shown. The apparatus 900 can be configured to perform various functions according to one or more embodiments or examples described herein. Therefore, the apparatus 900 can provide means for implementing the mechanisms, techniques, processes, functions, components, and systems described herein. For example, the apparatus 900 can be used to implement the functions of a UE or BS in the various embodiments and examples described herein. The apparatus 900 may include a general-purpose processor or specially designed circuitry to implement the various functions, components, or processes described herein in various embodiments. The apparatus 900 may include: processing circuitry 910, memory 920, and radio frequency (RF) module 930.

[0152] In various examples, the processing circuitry 910 may include circuitry configured to perform the functions and processes described herein, with or without software. In various examples, the processing circuitry 910 may be a digital signal processor (DSP), an application-specific integrated circuit (ASIC), a programmable logic device (PLD), a field-programmable gate array (FPGA), digital enhancement circuitry, or similar devices or combinations thereof.

[0153] In some other examples, processing circuitry 910 may be a central processing unit (CPU) configured to execute program instructions for performing the various functions and processes described herein. Therefore, memory 920 may be configured to store program instructions. Processing circuitry 910 may perform the functions and processes when executing these program instructions. Memory 920 may also store other programs or data, such as operating systems, application programs, etc. Memory 920 may include non-transitory storage media, such as read-only memory (ROM), random access memory (RAM), flash memory, solid-state memory, hard disk drive, optical disk drive, etc.

[0154] In one embodiment, RF module 930 receives processed data signals from processing circuitry 910 and converts the processed data signals into beamforming wireless signals, which are then transmitted via antenna array 940, or vice versa. RF module 930 may include: an analog-to-analog converter (DAC), an analog-to-digital converter (ADC), an up-converter, a down-converter, filters, and amplifiers for receive and transmit operations. RF module 930 may include multi-antenna circuitry for beamforming operations. For example, multi-antenna circuitry may include uplink and downlink spatial filter circuitry for shifting the phase of analog signals or scaling the amplitude of analog signals. Antenna array 940 may include one or more antenna arrays.

[0155] The device 900 may optionally include other components, such as input and output devices, additional or signal processing circuitry, etc. Therefore, the device 900 is capable of performing other additional functions, such as executing application programs and processing alternative communication protocols.

[0156] The processes and functions described herein can be implemented as computer programs that, when executed by one or more processors, cause the processors to perform the corresponding processes and functions. The computer program can be stored or distributed on suitable media, such as optical storage media or solid-state media provided together with or as part of other hardware. The computer program can also be distributed in other forms, such as via the Internet or other wired or wireless telecommunications systems. For example, the computer program can be obtained and loaded into a device, including through physical media or distributed systems (e.g., from a server connected to the Internet).

[0157] The computer program may be accessed from a computer-readable medium that provides program instructions for use by or in conjunction with a computer or any instruction execution system. The computer-readable medium may include any device for storing, transmitting, propagating, or transporting the computer program for use by or in conjunction with an instruction execution system, device, or apparatus. The computer-readable medium may be a magnetic, optical, electronic, electromagnetic, infrared, or semiconductor system (or device or apparatus) or a propagation medium. The computer-readable medium may include computer-readable non-transitory storage media, such as semiconductor or solid-state memory, magnetic tape, removable computer disks, random access memory (RAM), read-only memory (ROM), magnetic disks, and optical disks. The computer-readable non-transitory storage medium may include all types of computer-readable media, including magnetic storage media, optical storage media, flash memory media, and solid-state storage media.

[0158] While various aspects of this disclosure have been described in conjunction with specific embodiments presented as examples, alternatives, modifications, and changes may be made to these examples. Therefore, the embodiments described herein are intended to be illustrative and not limiting. Changes may be made without departing from the scope of the set forth claims.

Claims

1. A sidelink transmission method, comprising: At the first user equipment, pre-transmission listening is performed on the unlicensed frequency band to obtain the channel occupancy time for sidelink transmission; At the first user equipment, a set of candidate sidelink resources on the unlicensed frequency band is determined based on channel sensing performed on the unlicensed frequency band, wherein each candidate sidelink resource is within a sidelink resource selection window and has no reservation associated with a reference signal received power higher than a predetermined resource exclusion reference signal received power threshold. At the first user equipment, a sidelink resource is selected from the set of candidate sidelink resources; and During the obtained channel occupancy time, the sidelink transmission from the first user equipment to the second user equipment is performed on the selected sidelink resources. Specifically, the first user equipment decodes multiple side-link control information messages on a single physical side-link control channel resource.

2. The side-link transmission method according to claim 1 further includes: The ability to receive and decode the side link control information of the second user equipment; as well as The size of the sidelink resource selection window and the value of the reference signal received power threshold are determined based on the decoding capability of the sidelink control information received by the second user equipment.

3. The side-link transmission method according to claim 2, characterized in that, The stronger the sidelink control information decoding capability of the second user equipment, the narrower the size of the sidelink resource selection window, and The stronger the side link control information decoding capability of the second user equipment, the larger the value of the reference signal received power threshold.

4. The side-link transmission method according to claim 2, characterized in that, The reported side-link control information decoding capability is indicated by one of the following: The maximum number of side-link control information decoded per physical side-link control channel resource of the second user equipment. The maximum amount of side link control information used for decoding per time slot The maximum amount of side link control information used per symbol for decoding The maximum amount of side link control information that can be decoded per sub-channel The maximum number of sidelink control messages that can be decoded per resource pool The maximum amount of side link control information that can be decoded per bandwidth portion The maximum amount of side link control information used for decoding per frequency band. The maximum number of side link control information decoded per link pair of the second user equipment, and The second user equipment decodes the maximum number of side link control information for each receiving device.

5. The side-link transmission method according to claim 1, characterized in that, Decoding the multiple side link control information messages further includes: decoding the multiple side link control information messages in order of signal strength, first decoding the side link control information messages with stronger signal strength, and then decoding the side link control information messages with weaker signal strength.

6. The side-link transmission method according to claim 1 further includes: At the first user equipment, the plurality of sidelink control information messages are decoded on a single physical sidelink control channel resource to collect resource reservation information from nearby sidelink user equipment; At the first user equipment, selection assistance information is generated based on the collected resource reservation information; as well as The generated selection assistance information is reported from the first user equipment to the third user equipment for side link reception from the third user equipment.

7. The side-link transmission method according to claim 6, characterized in that, The generation step further includes: at the first user equipment, generating an indication of preferred resources as the generated selection assistance information, and The preferred resources are those identified by the first user equipment as being preferred for the side link reception based on the collected resource reservation information.

8. The side-link transmission method according to claim 6, characterized in that, The generation step further includes: at the first user equipment, generating an indication of non-preferred resources as the generated selection assistance information, and The non-preferred resources are those identified by the first user equipment as not preferred for the side link reception based on the collected resource reservation information.

9. The side-link transmission method according to claim 6, characterized in that, The generation step further includes: at the first user equipment, generating an indication of conflicting resources as the generated selection assistance information, and The conflicting resources are identified as resources that conflict when receiving data from the third user equipment via the sidelink, based on the multiple sidelink control information decoded on the physical sidelink control channel resources.

10. The side-link transmission method according to claim 1, further comprising: Receive a selection assistance information report from the second user equipment indicating preferred resources, non-preferred resources, and / or potentially conflicting resources; as well as At the first user equipment, the sidelink resource is selected from the set of candidate sidelink resources based on the selection assistance information reported.

11. The side-link transmission method according to claim 1, characterized in that, The determining step further includes: At the first user equipment, channel sensing is performed by decoding the plurality of sidelink control information messages on the single physical sidelink control channel resource to collect resource reservation information from nearby sidelink user equipment; and At the first user equipment, the set of candidate sidelink resources is determined based on the collected resource reservation information.

12. The side-link transmission method according to claim 11, characterized in that, The execution steps further include: decoding the plurality of side link control information messages in order of signal strength, first decoding the side link control information messages with stronger signal strength, and then decoding the side link control information messages with weaker signal strength.

13. The side-link transmission method according to claim 1, further comprising: The ability to receive and decode the side link control information of the second user equipment; as well as At the first user equipment, a conflicting resource is selected as the selected sidelink resource based on the decoding capability of the received sidelink control information and the priority level of the sidelink transmission to be performed, wherein the conflicting resource is reserved by a nearby sidelink user equipment.

14. An apparatus for performing side-link transmission, the apparatus comprising circuitry configured to: At the first user equipment, pre-transmission listening is performed on the unlicensed frequency band to obtain the channel occupancy time for sidelink transmission; At the first user equipment, a set of candidate sidelink resources in the unlicensed frequency band is determined based on channel sensing performed on the unlicensed frequency band, wherein, Each candidate sidelink resource is within the sidelink resource selection window and there are no reservations associated with a reference signal received power higher than the predetermined resource exclusion reference signal received power threshold; At the first user equipment, a sidelink resource is selected from the set of candidate sidelink resources; as well as During the obtained channel occupancy time, the sidelink transmission from the first user equipment to the second user equipment is performed on the selected sidelink resources. Specifically, the first user equipment decodes multiple side-link control information messages on a single physical side-link control channel resource.

15. The apparatus according to claim 14, characterized in that, The circuit is also used for: The ability to receive and decode side link control information from the second user equipment; and The size of the sidelink resource selection window and the value of the reference signal received power threshold are determined based on the decoding capability of the sidelink control information received by the second user equipment.

16. The apparatus according to claim 14, characterized in that, The circuit is also used to decode the plurality of side link control information messages in order of signal strength, first decoding the side link control information messages with stronger signal strength, and then decoding the side link control information messages with weaker signal strength.

17. The apparatus according to claim 14, characterized in that, The circuit is also used for: At the first user equipment, the plurality of sidelink control information messages are decoded on a single physical sidelink control channel resource to collect resource reservation information from nearby sidelink user equipment; At the first user equipment, selection assistance information is generated based on the collected resource reservation information; as well as The generated selection assistance information is reported from the first user equipment to the third user equipment for side link reception from the third user equipment.

18. The apparatus according to claim 14, characterized in that, The circuit is also used for: At the first user equipment, the channel sensing is performed by decoding the plurality of sidelink control information messages on the single physical sidelink control channel resource to collect resource reservation information from nearby sidelink user equipment; as well as At the first user equipment, the set of candidate sidelink resources is determined based on the collected resource reservation information.

19. The apparatus according to claim 14, characterized in that, The circuit is also used for: The ability to receive and decode side link control information from the second user equipment; and At the first user equipment, a conflicting resource is selected as the selected sidelink resource based on the decoding capability of the received sidelink control information and the priority level of the sidelink transmission to be performed, wherein the conflicting resource is reserved by a nearby sidelink user equipment.

20. A non-transitory computer-readable medium storing instructions that, when executed by a processor, perform the steps of the method for sidelink transmission according to any one of claims 1-13.

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