WO2021196120A1

WO2021196120A1 - Method and apparatus for evaluating sidelink resources

Info

Publication number: WO2021196120A1
Application number: PCT/CN2020/082964
Authority: WO
Inventors: Zhennian SUN; Xiaodong Yu; Haipeng Lei; Haiming Wang
Original assignee: Lenovo (Beijing) Limited
Priority date: 2020-04-02
Filing date: 2020-04-02
Publication date: 2021-10-07

Abstract

The present application relates to a method and apparatus for evaluating sidelink resources. One embodiment of the subject application provides a method performed by a User Equipment (UE), including: receiving a signal from a Base Station (BS), wherein the signal allocates one or more sidelink resources; and evaluating whether the one or more sidelink resources are available or not for sidelink transmission based on a sensing result of the UE.

Description

METHOD AND APPARATUS FOR EVALUATING SIDELINK RESOURCES

TECHNICAL FIELD

The subject application relates to sidelink communication, and more specifically relates to evaluating sidelink resources during sidelink communication.

BACKGROUND OF THE INVENTION

Vehicle to everything (V2X) has been introduced into 5G wireless communication technology. In terms of a channel structure of V2X communication, a direct link between two User Equipments (UEs) is called a sidelink (SL) . Sidelink is a long-term evolution (LTE) feature introduced in 3GPP Release 12, and enables a direct communication between proximal UEs, and data does not need to go through a base station (BS) or a core network.

In order to enhance the reliability of the sidelink communication, it is beneficial to evaluating the sidelink resources before performing the sidelink communication.

SUMMARY

One embodiment of the subject application provides a method performed by a User Equipment (UE) , including: receiving a signal from a Base Station (BS) , wherein the signal allocates one or more sidelink resources; and evaluating whether the one or more sidelink resources are available or not for sidelink transmission based on a sensing result of the UE.

Another embodiment of the subject application provides an apparatus, including: a non-transitory computer-readable medium having stored thereon computer-executable instructions; a receiving circuitry; a transmitting circuitry; and a processor coupled to the non-transitory computer-readable medium, the receiving circuitry and the transmitting circuitry, wherein the computer-executable instructions cause the processor to implement the method performed by a User Equipment (UE) , including: receiving a signal from a Base Station (BS) , wherein the signal allocates one or more sidelink resources; and evaluating whether the one or more sidelink resources are available or not for sidelink transmission based on a sensing result of the UE.

BRIEF DESCRIPTION OF THE DRAWINGS

Figure 1 illustrates a schematic diagram of a wireless communication system 100 in accordance with some embodiments of the subject disclosure.

Figure 2 illustrates the timing requirement for resource evaluation in accordance with some embodiments of the subject disclosure.

Figures 3 (a) , 3 (b) , 3 (c) , and 3 (d) illustrate technical solutions regarding determining the sidelink Hybrid Automatic Repeat Request (HARQ) feedback in accordance with some embodiments of the subject disclosure.

Figure 4 illustrates a method 400 performed by a UE for wireless communication according to a preferred embodiment of the subject disclosure.

Figure 5 illustrates a block diagram of a UE according to the embodiments of the subject disclosure.

DETAILED DESCRIPTION

The detailed description of the appended drawings is intended as a description of the preferred embodiments of the present invention, and is not intended to represent the only form in which the present invention may be practiced. It should be understood that the same or equivalent functions may be accomplished by different embodiments that are intended to be encompassed within the spirit and scope of the present invention.

Reference will now be made in detail to some embodiments of the present application, examples of which are illustrated in the accompanying drawings. To facilitate understanding, embodiments are provided under specific network architecture and new service scenarios, such as 3GPP 5G, 3GPP LTE Release 8 and so on. It is contemplated that along with developments of network architectures and new service scenarios, all embodiments in the present application are also applicable to similar technical problems; and moreover, the terminologies recited in the present application may change, which should not affect the principle of the present application.

UE (s) under new radio (NR) V2X scenario may be referred to as V2X UE (s) . A V2X UE, which transmits data according to sidelink resource (s) scheduled by a base station (BS) , may be referred to as a UE for transmitting, a transmitting UE, a transmitting V2X UE, a Tx UE, a V2X Tx UE, a SL Tx UE, or the like. A V2X UE, which receives data according to sidelink resource (s) scheduled by a BS, may be referred to as a UE for receiving, a receiving UE, a receiving V2X UE, a Rx UE, a V2X Rx UE, a SL Rx UE, or the like.

V2X UE (s) may include computing devices, such as desktop computers, laptop computers, personal digital assistants (PDAs) , tablet computers, smart televisions (e.g., televisions connected to the Internet) , set-top boxes, game consoles, security systems (including security cameras) , vehicle on-board computers, network devices (e.g., routers, switches, and modems) , internet of things (IoT) devices, or the like.

According to some embodiments of the present application, V2X UE (s) may include a portable wireless communication device, a smart phone, a cellular telephone, a flip phone, a device having a subscriber identity module, a personal computer, a selective call receiver, or any other device that is capable of sending and receiving communication signals on a wireless network.

According to some embodiments of the present application, V2X UE (s) includes wearable devices, such as smart watches, fitness bands, optical head-mounted displays, or the like. Moreover, V2X UE (s) may be referred to as a subscriber unit, a mobile, a mobile station, a user, a terminal, a mobile terminal, a wireless terminal, a fixed terminal, a subscriber station, a user terminal, or a device, or described using other terminology used in the art. V2X UE (s) may communicate directly with BS (s) via uplink (UL) communication signals.

A BS under NR V2X scenario may be referred to as a base unit, a base, an access point, an access terminal, a macro cell, a Node-B, an enhanced Node B (eNB) , a gNB, a Home Node-B, a relay node, a device, a remote unit, or by any other terminology used in the art. A BS may be distributed over a geographic region. Generally, a BS is a part of a radio access network that may include one or more controllers communicably coupled to one or more corresponding base stations.

A BS is generally communicably coupled to one or more packet core networks (PCN) , which may be coupled to other networks, like the packet data network (PDN) (e.g., the Internet) and public switched telephone networks, among other networks. These and other elements of radio access and core networks are not illustrated but are well known generally by those having ordinary skill in the art. For example, one or more BSs may be communicably coupled to a mobility management entity (MME) , a serving gateway (SGW) , and/or a packet data network gateway (PGW) .

A BS may serve a number of V2X UEs within a serving area, for example, a cell or a cell sector via a wireless communication link. A BS may communicate directly with one or more of V2X UEs via communication signals. For example, a BS may serve V2X UEs within a macro cell.

Sidelink communication between a Tx UE and a Rx UE under NR V2X scenario includes groupcast communication, unicast communication, or broadcast communication.

Embodiments of the present application may be provided in a network architecture that adopts various service scenarios, for example but is not limited to, 3GPP 3G, long-term evolution (LTE) , LTE-Advanced (LTE-A) , 3GPP 4G, 3GPP 5G NR (new radio) , 3GPP LTE Release 12 and onwards, etc. It is contemplated that along with the 3GPP and related communication technology development, the terminologies recited in the present application may change, which should not affect the principle of the present application.

Figure 1 illustrates an exemplary V2X communication system in accordance with some embodiments of the present application.

As shown in Figure 1, the V2X communication system includes a base station, i.e., BS 102 and some V2X UEs, i.e., UE 101-A, UE 101-B, and UE 101-C. UE 101-A and UE 101-B are within the coverage of BS 102, and UE 101-C is not. UE 101-A and UE 101-B may perform sidelink unicast transmission, sidelink groupcast transmission, or sidelink broadcast transmission. It is contemplated that, in accordance with some other embodiments of the present application, a V2X communication system may include more or fewer BSs, and more or fewer V2X UEs. Moreover, it is contemplated that names of V2X UEs (which represent a Tx UE, a Rx UE, and etc. ) as illustrated and shown in Figure 1 may be different, e.g., UE 101c, UE 104f, and UE 108g or the like.

In addition, although each V2X UE as shown in Figure 1 is illustrated in the shape of a car, it is contemplated that a V2X communication system may include any type of UE (e.g., a roadmap device, a cell phone, a computer, a laptop, IoT (internet of things) device or other type of device) in accordance with some other embodiments of the present application.

According to some embodiments of Figure 1, UE 101-A functions as a Tx UE, and UE 101-B and UE 101-C function as a Rx UE. UE 101-A may exchange V2X messages with UE 101-B, or UE 101-C through a sidelink, for example, PC5 interface as defined in 3GPP TS 23.303. UE 101-A may transmit information or data to other UE (s) within the V2X communication system, through sidelink unicast, sidelink groupcast, or sidelink broadcast. For instance, UE 101-A transmits data to UE 101-B in a sidelink unicast session. UE 101-A may transmit data to UE 101-B and UE 101-C in a groupcast group by a sidelink groupcast transmission session. Also, UE 102 may transmit data to UE 101-B and UE 101-C by a sidelink broadcast transmission session.

Alternatively, according to some other embodiments of Figure 1, UE 101-B functions as a Tx UE and transmits V2X messages, UE 101-A functions as a Rx UE and receives the V2X messages from UE 101-B.

Both UE 101-A and UE 101-B in the embodiments of Figure 1 may transmit information to BS 102 and receive control information from BS 102, for example, via NR Uu interface. BS 102 may define one or more cells, and each cell may have a coverage area. As shown in Figure 1, both UE 101-A and UE 101-B are within a coverage of BS 102, and UE 101-C is outside of the coverage of BS 102.

BS 102 as illustrated and shown in Figure 1 is not a specific base station, but may be any base station (s) in the V2X communication system. For example, if the V2X communication system includes two BSs 102, UE 101-A being within a coverage area of any one the two BSs 102 may be called as a case that UE 101-A is within a coverage of BS 102 in the V2X communication system; and only UE 101-Abeing outside of coverage area (s) of both BSs 102 can be called as a case that UE 101-A is outside of the coverage of BS 102 in the V2X communication system.

The V2X UEs may operate in different modes. At least two sidelink resource allocation modes are defined for NR-V2X sidelink communication, which are: mode 1: base station schedules sidelink resource (s) to be used by UE for sidelink transmission (s) ; and mode 2: UE determines sidelink transmission resource (s) within sidelink resources configured by base station or network, or pre-configured sidelink resources, in mode 2, the base station does not schedules the sidelink resources for the UE. In Figure 1, UE 101-A and UE 101-B are in mode 1, and UE 101-C is in mode 2, and in this disclosure, we use UE 101-A representing a transmitting UE in mode 1, and UE 101-C representing another transmitting UE in mode 2.

Currently only dedicated resource pool is supported for mode 1 and mode 2. If shared resource pool between mode 1 and mode 2 is supported, that is, the UEs in mode 1 and the UEs in mode 2 can use the resources from the same resource pool. Therefore, resource collision between the UEs in mode 1 and the UEs in mode 2 might happen. For example, the sidelink resources allocated to UE 101-A, and the sidelink resources determined by UE 101-C are from the same resource pool, and these resources might overlap. If these resources overlap, this means UE 101-A and UE 101-C in Figure 1 might have a recourse collision, and the reliability of sidelink transmission cannot be ensured. For instance, on a specific sidelink resource, the transmission from the UE 101-C might have higher priority or more urgent aperiodic traffic than the transmission from the UE 101-A, and how the two UEs perform the sidelink transmission is discussed in this disclosure. It should be addressed to guarantee the reliability of sidelink transmission since there is aperiodic traffic in NR V2X or pre-emption.

In this subject disclosure, we focus on reducing the probability of resource collision between mode 1 UE and mode 2 UE, and the actions the UEs in mode 1 might take when the UEs in mode 1 detects a resource collision.

In order to avoid the resource collision, the subject disclosure proposes to evaluate the resources allocated by the base station, and determine whether these resources are available or not.

Taking Figure 1 as an example, in Figure 1, UE 101-A is the transmitting UE in mode 1, and BS 102 may allocate one or more sidelink resources to UE 101-A for the sidelink transmission for a Transport Block (TB) , for example, BS 102 may transmit a dynamic grant, Downlink Control Information (DCI) , e.g. DCI format 3_0, which indicates resources for one or multiple sidelink transmissions of a single TB. DCI indicates the time gap, e.g., the slot offset, between DCI reception and the first sidelink transmission scheduled by DCI. The minimum time gap between DCI and the first scheduled sidelink transmission shall not be smaller than the corresponding UE processing time.

In order to avoid the resource collision, after receiving the DCI transmitted by BS 102, UE 101-A might perform resource evaluation. In other words, UE 101-A determines whether the allocated resources are available or not, and the determination is based on the sensing and measuring performed by UE 101-A. More specifically, a UE can determine whether a sidelink resource is available or unavailable based on the following resource evaluation criterion:

Based on the sensing and measuring performed by UE 101-A, UE 101-Amight receive a SCI, which is transmitted by another UE, for example, UE 101-C, and the resources reserved by the SCI are fully or partially overlap with the resource allocated by BS 102, and the value of the associated Layer 1 Sidelink-Reference Signal Received Power (L1 SL-RSRP) is greater than to a threshold, then the sidelink resources are considered to be an unavailable sidelink resource for UE 101-A. Alternatively, if the priority level in the SCI transmitted by UE 101-C is higher than the priority level of UE 101-A's sidelink transmission, UE 101-A also determines that the resource allocated by the SCI are unavailable for UE 101-A. Generally, the priority level is inversely proportional to the priority value, for instance, the priority value '1' has a higher priority level than the priority value '2' .

Otherwise, UE 101-A determines that the resource allocated by BS 102 are available for UE 101-A to perform sidelink transmission. For example, if the sidelink resource is not indicated by a SCI, then the sidelink resource is considered to be an available sidelink resource. If a sidelink resource is indicated by a SCI, but the value of the associated L1 SL-RSRP is less than or equal to a threshold, then the sidelink resource is also considered to be an available sidelink resource. For another example, if the priority level in the SCI transmitted by UE 101-C is lower than or equal to the priority level of UE 101-A's sidelink transmission, UE 101-A also determines that the resource allocated by the SCI are available for UE 101-A.

The above determination for a sidelink resource should be accomplished before a time period of the sidelink resource. Figure 2 depicts the timing requirement for the resource evaluation. In Figure 2, the DCI transmitted by the BS indicates the time gap, or slot offset, between DCI reception and the first sidelink transmission scheduled by DCI. The DCI allocates n sidelink resources to a UE, wherein n is an integer, and n≥1. These sidelink resources are represented with 201, 202, …, 20n, and the starting time for the resources are t ₁, t ₂, …, t _n respectively. The first resource 201 may reserve the following resources, such as resource 202, 203, …, 20n, and second resource 202 may reserve the following resources, such as resource 203, 204, …, 20n, and so on. Suppose the preparation time of Physical Sidelink Control Channel (PSCCH) /Physical Sidelink Shared Channel (PSSCH) is T, therefore, for each allocated resource t ₁, t ₂, …, t _n, the resource evaluation should be done before t ₁-T, t ₂-T, …, t _n-T, respectively.

If UE 101-A evaluates one resource as unavailable, it may drop the sidelink transmission on the allocated resource; otherwise it may perform sidelink transmission on the allocated resource. For example, if UE 101-A determines that resource 201 is available, UE 101-A may perform sidelink transmission on resource 201; if UE 101-A determines that resource 202 is unavailable, UE 101-A may drop the sidelink transmission on resource 202.

The UE may perform the resource evaluation depending on the priority of the traffic. In one embodiment, UE 101-A always performs resource evaluation before sidelink transmission, in other words, UE 101-A always performs sensing and measurement every slot regardless the priority of the traffic to be transmitted by UE 101-A.

In another embodiment, when the priority level of the traffic to be transmitted by the UE is higher than or equal to a threshold, the UE may skip the resource evaluation. For example, UE 101-A can determine whether to perform resource evaluation based on the priority level of the sidelink transmission of UE 101-A. That is, a priority threshold may be configured per resource pool to enable or disable the resource evaluation behavior, when the priority level of the sidelink transmission of UE 101-A is below the threshold, which might suggest that the sidelink transmission may not be so urgent, UE 101-A should perform the resource evaluation before the sidelink transmission. When the priority level of the sidelink transmission of UE 101-A is above or equal to the threshold, which might imply that the sidelink transmission may be urgent, and UE 101-A may skip the resource evaluation before sidelink transmission. As indicated above, before UE 101-A starts the sidelink transmission, it shall broadcast a SCI with the priority level. If the priority level is high enough, e.g., higher than a threshold, and other UE, for example, UE 101-C, receives such a SCI would drop the transmission on the resource. Therefore, the probability of resource collision is reduced.

The resource evaluation may depend on the instruction from the BS, an indicator may be transmitted in DCI to trigger the re-evaluation. For example, the DCI may further include an indicator, to indicate whether UE 101-A should perform resource evaluation before the sidelink transmission.

For dynamic grant and configured grant, the BS might further provide PUCCH resources for feedback. If the BS provides PUCCH resources for feedback, the UE reports sidelink HARQ feedback to the BS, and if the BS does not provide PUCCH resources for feedback, the UE does not report SL HARQ feedback to the BS.

Figures 3 (a) -3 (d) illustrate technical solutions regarding determining the sidelink HARQ feedback in accordance with some embodiments of the subject disclosure. Figure 3 (a) and 3 (b) relates to PSCCH/PSSCH enabled SL HARQ feedback, and Figures 3 (c) and 3 (d) relates to PSCCH/PSSCH disabled SL HARQ feedback. In Figures 3 (a) -3 (d) , the DCI indicates the time gap, for example, slot offset, between DCI reception and the first sidelink transmission scheduled by DCI, and the BS provides PUCCH resources for feedback.

In Figure 3 (a) , the DCI allocates resource 301 to the mode 1 UE, e.g. UE 101-A, and the BS further allocates a PUCCH resource for the UE to transmit a sidelink HARQ report. In Figure 3 (a) , UE 101-A enables the sidelink HARQ feedback, and thus UE 101-A transmits PSCCH/PSSCH enabled SL HARQ feedback to the BS. The sidelink HARQ feedback for the sidelink transmission may be received in the Physical Sidelink Feedback Channel (PSFCH) , which is represented with the reference numeral 301' in Figure 3 (a) .

After evaluation, if UE 101-A determines that resource 301 is an unavailable resource for sidelink transmission, it shall transmit negative acknowledgement (NACK) on the PUCCH resource to the BS to request additional resources. If UE 101-A determines that resource 301 is an available resource for sidelink transmission, it would perform transmission on resource 301, then reports the SL HARQ feedback according to the received sidelink HARQ feedback in Physical Sidelink Feedback Channel (PSFCH) , which is represented with the reference numeral 301' in Figure 3 (a) . That is, if the sidelink transmission on resource 301 is successful, UE 101-A transmits ACK to the BS; if not, UE 101-A transmits NACK to the BS.

In Figure 3 (b) , the DCI allocates multiple resources 301, 302, …, 30n to the mode 1 UE, e.g. UE 101-A, and the BS further allocates a PUCCH resource for the UE to transmit a sidelink HARQ report. In Figure 3 (a) , UE 101-A also enables the sidelink HARQ feedback, and thus UE 101-A transmits PSCCH/PSSCH enabled SL HARQ feedback to the BS. The sidelink HARQ feedback for the sidelink transmission may be received in the PSFCH, which is represented with the reference numerals 301', 302', …, 30n' respectively in Figure 3 (b) .

If all the resources are evaluated as unavailable resources, UE 101-A reports NACK to the BS; otherwise UE 101-A determines SL HARQ feedback according to the received sidelink HARQ feedback in PSFCH, the sidelink HARQ feedback 301', 302', …, 30n', which correspond to the sidelink resources 301, 302, …, 30n respectively. The SL HARQ feedback might be NACK or ACK, then UE 101-A reports the SL HARQ feedback to the BS. That is, if the sidelink transmission on resource 301 is successful, UE 101-A transmits ACK to the BS; if not, UE 101-A transmits NACK to the BS.

In Figure 3 (c) , the DCI allocates a sidelink resource 301 to the mode 1 UE, e.g. UE 101-A, and the BS further allocates a PUCCH resource for the UE to transmit a sidelink HARQ report. In Figure 3 (c) , UE 101-A disables the sidelink HARQ feedback, and thus UE 101-A transmits PSCCH/PSSCH disabled SL HARQ feedback to the BS.

In Figure 3 (c) , the BS allocates one sidelink resource 301 to UE 101-A, and UE 101-A performs sidelink transmission with blind re-transmission. If resource 301 is evaluated as unavailable resources, UE 101-A will drop the sidelink transmissions on resource 301 and report NACK to the BS on the PUCCH to request additional sidelink resource allocation.

In Figure 3 (d) , the DCI allocates multiple resources 301, 302, …, 30n to the mode 1 UE, e.g. UE 101-A, and the BS further allocates a PUCCH resource for the UE to transmit a sidelink HARQ report. In Figure 3 (d) , UE 101-A disables the sidelink HARQ feedback, and thus UE 101-A transmits PSCCH/PSSCH disabled SL HARQ feedback to the BS.

In one embodiment, UE 101-A might perform sidelink transmission with blind re-transmission.

If all the allocated resources are evaluated as unavailable resources, it means that UE 101-A will drop the sidelink transmissions on the allocated resources; then UE 101-A should report NACK to the BS on the PUCCH to request additional sidelink resource allocation.

If some of allocated resources are evaluated as unavailable resources for sidelink transmission, for example, resources 301 and 302 are available resources, and 303-30n are unavailable resources, UE 101-A has multiple approaches to determine the sidelink HARQ report.

In one embodiment, UE 101-A report NACK to the BS, and the BS may evaluate the reliability of sidelink transmission based on the reported SL Buffer Status Report (BSR) , for example, Logic Channel ID (LCH_ID) in SL BSR, and determines the number of sidelink re-transmissions, and then allocates corresponding sidelink resources for sidelink transmission. If UE 101-A drops one or more transmissions after resource evaluation, it means that it may need more resources to guarantee the sidelink transmission; so it shall report NACK to the BS to request additional resources

In another embodiment, UE 101-A might determine whether ACK or NACK should be reported based on UE implementation. For instance, if UE 101-A estimates that the number of re-transmissions after several dropping cannot guarantee the reliability of the sidelink transmission, it may report NACK to the BS to request more sidelink resources for sidelink blind re-transmission. If UE 101-A estimates that the reliability of the sidelink transmission can still be guaranteed with several dropping, it may report ACK to the BS.

Figure 4 illustrates a method 400 performed by a UE for sidelink communication according to a preferred embodiment of the subject disclosure. In step 401, the UE receives a signal from a BS, for example, the DCI, which allocates one or more sidelink resources. In step 402, the UE evaluates whether the one or more sidelink resources are available or not for sidelink transmission based on a sensing result of the UE.

After the evaluation, the UE may perform sidelink transmission on one or more available sidelink resources, if there is no available sidelink resources, the UE might drop all the allocated resources. The UE may drop sidelink transmission on one or more unavailable sidelink resources, and if there is no unavailable sidelink resources, the UE would not drop any of the allocated resources.

There are several cases that a UE would consider a sidelink resource as unavailable: 1) when the sensing result indicates that the sidelink resource is indicated by a received SCI and a value of a SL-RSRP measurement is greater than a first threshold; 2) the sensing result indicates that the sidelink resource is indicated by a received SCI and a priority level in the received SCI is higher than a priority level of a sidelink transmission of the UE.

If the sensing result does not indicate the above cases, the UE evaluates a sidelink resource as available. For example, in one embodiment, a sidelink resource is available when the sensing result indicates that the sidelink resource is not indicated by a received SCI. For another embodiment, a sidelink resource is available when the sensing result indicates that the sidelink resource is indicated by a received SCI and a value of a SL-RSRP measurement is less than or equal to a first threshold. For a third embodiment, a sidelink resource is available when the sensing result indicates that the sidelink resource is indicated by a received SCI and a priority level in the received SCI is lower than or equal to a priority level of a sidelink transmission of the UE.

There is a deadline for the evaluating for each sidelink resource. That is, for a specific sidelink resource, the evaluating for each sidelink resource is finished before a period of a corresponding starting time of each sidelink resource. For example, in Figure 2, the evaluating of sidelink resource 202 should be accomplished before t ₂-T, wherein T is the preparation time of PSCCH/PSSCH, and t ₂ is the starting time of sidelink resource 202.

In one preferred embodiment, the resource evaluating is performed when a priority level of a sidelink transmission of the UE is higher than a second threshold. In another preferred embodiment, the resource evaluating is performed based on an indicator in the DCI.

After the evaluation, the UE may transmit a NACK to the BS when the one or more sidelink resources are all evaluated as unavailable. Alternatively, the UE may transmit a NACK to the BS when the one or more sidelink resources are evaluated as partially unavailable and sidelink HARQ feedback is disabled, for example, in the technical solution in Figure 3 (d) , UE 101-C may transmit a NACK to the BS when some sidelink resources are evaluated as unavailable. In another embodiment, the UE may determine whether to transmit an ACK or a NACK to the BS based on UE implementation when the one or more sidelink resources are evaluated as partially unavailable and sidelink HARQ feedback is disabled, for instance, in the technical solution in Figure 3 (d) , UE 101-C may transmit an ACK or a NACK to the BS based on UE implementation when some sidelink resources are evaluated as unavailable.

Figure 5 illustrates a block diagram of a UE according to the embodiments of the subject disclosure. The UE may include a receiving circuitry, a processor, and a transmitting circuitry. In one embodiment, the UE may include a non-transitory computer-readable medium having stored thereon computer-executable instructions; a receiving circuitry; a transmitting circuitry; and a processor coupled to the non-transitory computer-readable medium, the receiving circuitry and the transmitting circuitry. The computer executable instructions can be programmed to implement a method (e.g. the methods in Figure 4) with the receiving circuitry, the transmitting circuitry and the processor. That is, the receiving circuitry may receive a signal from a BS, wherein the signal allocates one or more sidelink resources, and the processor may evaluate whether the one or more sidelink resources are available or not for sidelink transmission based on a sensing result of the UE.

The method of the present disclosure can be implemented on a programmed processor. However, the controllers, flowcharts, and modules may also be implemented on a general purpose or special purpose computer, a programmed microprocessor or microcontroller and peripheral integrated circuit elements, an integrated circuit, a hardware electronic or logic circuit such as a discrete element circuit, a programmable logic device, or the like. In general, any device that has a finite state machine capable of implementing the flowcharts shown in the figures may be used to implement the processing functions of the present disclosure.

While the present disclosure has been described with specific embodiments thereof, it is evident that many alternatives, modifications, and variations will be apparent to those skilled in the art. For example, various components of the embodiments may be interchanged, added, or substituted in the other embodiments. Also, all of the elements shown in each figure are not necessary for operation of the disclosed embodiments. For example, one skilled in the art of the disclosed embodiments would be capable of making and using the teachings of the present disclosure by simply employing the elements of the independent claims. Accordingly, the embodiments of the present disclosure as set forth herein are intended to be illustrative, not limiting. Various changes may be made without departing from the spirit and scope of the present disclosure.

In this disclosure, relational terms such as "first, " "second, " and the like may be used solely to distinguish one entity or action from another entity or action without necessarily requiring or implying any actual such relationship or order between such entities or actions. The terms "comprises, " "comprising, " or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements but may include other elements not expressly listed or inherent to such process, method, article, or apparatus. An element proceeded by "a, " "an, " or the like does not, without more constraints, preclude the existence of additional identical elements in the process, method, article, or apparatus that comprises the element. Also, the term "another" is defined as at least a second or more. The terms "including, " "having, " and the like, as used herein, are defined as "comprising. "

Claims

A method performed by a User Equipment (UE) , comprising:

receiving a signal from a Base Station (BS) , wherein the signal allocates one or more sidelink resources; and

evaluating whether the one or more sidelink resources are available or not for sidelink transmission based on a sensing result of the UE.
The method of Claim 1, further comprising:

performing sidelink transmission on one or more available sidelink resources.
The method of Claim 1, further comprising:

dropping sidelink transmission on one or more unavailable sidelink resources.
The method of Claim 1, wherein a sidelink resource is unavailable when the sensing result indicates that the sidelink resource is indicated by a received Sidelink Control Information (SCI) and a value of a Sidelink Reference Signal Received Power (SL-RSRP) measurement is greater than a first threshold.
The method of Claim 1, wherein a sidelink resource is unavailable when the sensing result indicates that the sidelink resource is indicated by a received Sidelink Control Information (SCI) and a priority level in the received SCI is higher than a priority level of a sidelink transmission of the UE.
The method of Claim 1, wherein a sidelink resource is available when the sensing result indicates that the sidelink resource is not indicated by a received Sidelink Control Information (SCI) .
The method of Claim 1, wherein a sidelink resource is available when the sensing result indicates that the sidelink resource is indicated by a received SCI and a value of a Sidelink Reference Signal Received Power (SL-RSRP) measurement is less than or equal to a first threshold.
The method of Claim 1, wherein a sidelink resource is available when the sensing result indicates that the sidelink resource is indicated by a received Sidelink Control Information (SCI) and a priority level in the received SCI is lower than or equal to a priority level of a sidelink transmission of the UE.
The method of Claim 1, wherein the evaluating for each sidelink resource is finished before a period of a corresponding starting time of each sidelink resource.
The method of Claim 1, wherein the evaluating whether the one or more sidelink resources are available or not for sidelink transmission based on a sensing result of the UE further comprising:

evaluating the one or more sidelink resources when a priority level of a sidelink transmission of the UE is higher than a second threshold.
The method of Claim 1, wherein the evaluating whether the one or more sidelink resources are available or not for sidelink transmission based on a sensing result of the UE further comprising:

evaluating the one or more sidelink resources based on an indicator in the signal.
The method of Claim 1, further comprising:

transmitting a negative acknowledgement (NACK) to the BS when the one or more sidelink resources are all evaluated as unavailable.
The method of Claim 1, further comprising:

transmitting a negative acknowledgement (NACK) to the BS when the one or more sidelink resources are evaluated as partially unavailable and sidelink Hybrid Automatic Repeat Request (HARQ) feedback is disabled.
The method of Claim 1, further comprising:

determining whether to transmit an acknowledgement (ACK) or a negative acknowledgement (NACK) to the BS based on UE implementation when the one or more sidelink resources are evaluated as partially unavailable and sidelink Hybrid Automatic Repeat Request (HARQ) feedback is disabled.
An apparatus, comprising:

a non-transitory computer-readable medium having stored thereon computer-executable instructions;

a receiving circuitry;

a transmitting circuitry; and

a processor coupled to the non-transitory computer-readable medium, the receiving circuitry and the transmitting circuitry,

wherein the computer-executable instructions cause the processor to implement the method of any of Claims 1-14.