WO2023133807A1

WO2023133807A1 - Methods and apparatuses for resource re-evaluation and pre-emption for sidelink ca

Info

Publication number: WO2023133807A1
Application number: PCT/CN2022/072046
Authority: WO
Inventors: Zhennian SUN; Xiaodong Yu; Haipeng Lei; Xin Guo
Original assignee: Lenovo Beijing Ltd
Current assignee: Lenovo Beijing Ltd
Priority date: 2022-01-14
Filing date: 2022-01-14
Publication date: 2023-07-20
Anticipated expiration: 2024-07-14

Abstract

The present disclosure relates to methods and apparatuses for resource re-evaluation and pre-emption for sidelink carrier aggression (CA) One embodiment of the present disclosure provides a user equipment (UE), which includes: a transceiver; and a processor coupled to the transceiver, wherein the processor is configured to: determine whether a first physical sidelink feedback channel (PSFCH) on a first component carrier (CC) overlaps with a second PSFCH on a second CC, wherein the first PSFCH is associated with a first resource for a first sidelink (SL) transmission; and in the case that the first PSFCH and the second PSFCH at least partially overlaps in time domain, perform at least one of the following action: perform a resource re-selection procedure for the first resource; disable hybrid automatic repeat request (HARQ) feedback for the first SL transmission; or drop the second PSFCH on the second CC.

Description

METHODS AND APPARATUSES FOR RESOURCE RE-EVALUATION AND PRE-EMPTION FOR SIDELINK CA

TECHNICAL FIELD

The present disclosure relates to sidelink communication, and more specifically relates to methods and apparatuses for resource re-evaluation and pre-emption for sidelink carrier aggression (CA) .

BACKGROUND OF THE INVENTION

New Radio (NR) sidelink CA includes inter-band CA or intra-band CA. In R16, sidelink re-evaluation and pre-emption is supported to guarantee the reliability of sidelink transmission, and only one carrier is supported for R16 sidelink. For R16 resource re-evaluation and pre-emption, the UE evaluates the selected resources or reserved resources by sensing to guarantee that there is no resource conflict with other sidelink UEs. Sidelink HARQ-ACK is supported in R16.

In R18, sidelink evaluation, when intra-band CA is configured for one UE, the half-duplex issue may happen due to physical sidelink feedback channel (PSFCH) transmission or reception.

The present disclosure proposes some solutions for solving the half-duplex issue caused by PSFCH transmission or reception via the sidelink re-evaluation or pre-emption procedure.

SUMMARY

One embodiment of the present disclosure provides a user equipment (UE) , which includes: a transceiver; and a processor coupled to the transceiver, wherein the processor is configured to: determine whether a first physical sidelink feedback channel (PSFCH) on a first component carrier (CC) overlaps with a second PSFCH on a second CC, wherein the first PSFCH is associated with a first resource for a first sidelink (SL) transmission; and in the case that the first PSFCH and the second PSFCH at least partially overlaps in time domain, perform at least one of the following action: perform a resource re-selection procedure for the first resource; disable hybrid automatic repeat request (HARQ) feedback for the first SL transmission; or drop the second PSFCH on the second CC.

In some embodiments, the first PSFCH is for receiving HARQ feedback for the first SL transmission on the first CC.

In some embodiments, the second PSFCH is for transmitting HARQ feedback for a second physical sidelink shared channel (PSSCH) on the second CC and/or for transmitting a resource conflict indicator.

In some embodiments, the second PSSCH is received on the second CC or is reserved by a third PSSCH for re-transmission from another UE.

In some embodiments, in case the third PSSCH is successfully decoded, the processor is configured to determine whether to perform a resource re-selection procedure for the first SL resource based on UE implementation.

In some embodiments, the processor is further configured to: perform a resource re-selection procedure for the first resource based on a first priority of the first SL transmission to be transmitted on the first resource and/or a second priority of a second SL transmission associated with the second PSFCH.

In some embodiments, the first priority is lower than a highest priority for the second SL transmission.

In some embodiments, the highest priority for the second SL transmission is higher than a priority threshold.

Another embodiment of the present disclosure provides a method performed by a user equipment (UE) , comprising: determining whether a first physical sidelink feedback channel (PSFCH) on a first component carrier (CC) overlaps with a second PSFCH on a second CC, wherein the first PSFCH is associated with a first resource for a first sidelink (SL) transmission; and in the case that the first PSFCH and the second PSFCH at least partially overlaps in time domain, performing at least one of the following action: performing a resource re-selection procedure for the first resource; disabling hybrid automatic repeat request (HARQ) feedback for the first SL transmission; or dropping the second PSFCH on the second CC.

In some embodiments, the method further includes: performing a resource re-selection procedure for the first resource based on a first priority of the first SL transmission to be transmitted on the first resource and/or a second priority of a second SL transmission associated with the second PSFCH.

In some embodiments, highest priority for the second SL transmission is higher than a priority threshold.

BRIEF DESCRIPTION OF THE DRAWINGS

In order to describe the manner in which advantages and features of the disclosure can be obtained, a description of the disclosure is rendered by reference to specific embodiments thereof, which are illustrated in the appended drawings. These drawings depict only example embodiments of the disclosure and are not therefore to be considered limiting of its scope.

Fig. 1 illustrates an exemplary wireless communication system (e.g., a V2X communication system) 100 in accordance with some embodiments of the present disclosure.

Fig. 2 illustrates an exemplary scenario of two overlapping PSFCHs in time domain according to some embodiments of the present disclosure.

Fig. 3 illustrates an exemplary scenario of two overlapping PSFCHs in time domain according to some embodiments of the present disclosure.

Figs. 4A and 4B illustrate exemplary scenarios of two overlapping PSFCHs in time domain according to some embodiments of the present disclosure.

Fig. 5 illustrates a method performed by a UE for resource re-evaluation and pre-emption for sidelink CA according to some embodiments of the present disclosure.

Fig. 6 illustrates a simplified block diagram of an exemplary apparatus according to some embodiments of the present disclosure.

DETAILED DESCRIPTION

The detailed description of the appended drawings is intended as a description of the currently 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.

While operations are depicted in the drawings in a particular order, persons skilled in the art will readily recognize that such operations need not be performed in the particular order as shown or in a sequential order, or that all illustrated operations need be performed, to achieve desirable results; sometimes one or more operations can be skipped. Further, the drawings can schematically depict one or more example processes in the form of a flow diagram. However, other operations that are not depicted can be incorporated in the example processes that are schematically illustrated. For example, one or more additional operations can be performed before, after, simultaneously, or between any of the illustrated operations. In certain circumstances, multitasking and parallel processing can be advantageous.

Reference will now be made in detail to some embodiments of the present disclosure, 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 the 3rd generation partnership project (3GPP) 5G (NR) , 3GPP long-term evolution (LTE) , and so on. It is contemplated that along with the developments of network architectures and new service scenarios, all embodiments in the present disclosure are also applicable to similar technical problems; and moreover, the terminologies recited in the present disclosure may change, which should not affect the principle of the present disclosure.

Embodiments of the present disclosure may be provided in a network architecture that adopts various service scenarios, for example but not limited to, 3GPP 3G, LTE, LTE-Advanced (LTE-A) , 3GPP 4G, 3GPP 5G NR, 3GPP Release 16 and onwards, etc. It is contemplated that along with the 3GPP and related communication technology development, the terminologies recited in the present disclosure may change, which should not affect the principle of the present disclosure.

Embodiments of the present disclosure may relate to coexistence between LTE V2X and NR V2X. It is contemplated that all embodiments in the present disclosure are also applicable to similar technical problems in coexistence between other different RATs.

User equipment (UE) under NR V2X scenario and/or LTE V2X scenario may be referred to as V2X UE (s) . A V2X UE which transmits data on sidelink may be referred to as a UE for transmitting, a transmitting UE, a transmitting V2X UE, a Tx UE, a V2X Tx UE, a sidelink (SL) Tx UE, or the like. A V2X UE which receives data on sidelink may be referred to as a UE for receiving, a receiving UE, a receiving V2X UE, an Rx UE, a V2X Rx UE, an 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 disclosure, 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 disclosure, V2X UE (s) may include 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 communication signals.

A BS under NR V2X scenario and/or LTE 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 V2X UEs via communication signals. For example, a BS may serve V2X UEs within a macro cell.

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

As shown in Fig. 1, the V2X communication system 100 includes a base station, i.e., BS 102, and some V2X UEs, i.e., UE 101-A, UE 101-B, UE 101-C, and UE 101-D. UE 101-A and UE 101-B are within the coverage of the BS 102, and UE and UE 101-D 101-C is outside the coverage of the BS 102. UE 101-A, UE 101-B, UE 101-C, and UE 101-D 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 disclosure, a V2X communication system may include more BSs and more or fewer V2X UEs.

In addition, although the V2X UE as shown in Fig. 1 is illustrated in the shape of a cellphone, 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 device or other type of device) in accordance with some other embodiments of the present disclosure.

According to some embodiments of Fig. 1, UE 101-A may function as a Tx UE, and UE 101-B, UE 101-C, and UE 101-D may function as Rx UEs. UE 101-A may exchange V2X messages with UE 101-B or UE 101-C through a sidelink using the NR technology, or the LTE technology, through PC5 interface as defined in 3GPP documents. 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 may transmit 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 101-A may transmit data to UE 101-B and UE 101-C by a sidelink broadcast transmission session.

Alternatively, according to some other embodiments of Fig. 1, UE 101-B or UE 101-C may function as a Tx UE and transmit V2X messages, and UE 101-A may function as an Rx UE and receive the V2X messages from UE 101-B or UE 101-C.

Both UE 101-A and UE 101-B in the embodiments of Fig. 1 may transmit information to the BS 102 and receive control information from the BS 102, for example, via NR Uu interface. The BS 102 may define one or more cells, and each cell may have a coverage area. As shown in Fig. 1, both UE 101-A and UE 101-B are within the coverage of the BS 102, while UE 101-C and UE 101-D are not.

The BS 102 as illustrated and shown in Fig. 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-A being 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 UE may perform sidelink transmission and/or sidelink reception in different component carriers (CCs) . NR sidelink carrier aggression (CA) includes in inter-band CA or intra-band CA.

In R18, sidelink evaluation NR sidelink CA operation has been agreed with the following objectives:

According to 3GPP documents, in sidelink resource allocation mode 2, the UE procedure for determining the subset of resources to be reported to higher layers in PSSCH resource selection may include the following operations:

The higher layer may request the UE to determine a subset of resources, and the higher layer will select resources for PSSCH/PSCCH transmission from the subset of resources, as part of re-evaluation or pre-emption procedure. To trigger this procedure, in slot n, the higher layer provides the some parameters for this PSSCH/PSCCH transmission.

The higher layer provides a set of resources (r ₀, r ₁, r ₂, ... ) which may be subject to re-evaluation, and a set of resources (r′ ₀, r′ ₁, r′ ₂, ... ) which may be subject to pre-emption.

It is up to UE implementation to determine the subset of resources as requested by higher layers before or after the slot r″ _i -T ₃, where slot r″ _i is the slot with the smallest slot index among the a set of resources (r ₀, r ₁, r ₂, ... ) and the a set of resources (r′ ₀, r′ ₁, r′ ₂, ... ) , and T ₃ is equal to

where

is defined in slots in the following table, where μ _sL is the sub-carrier spacing (SCS) configuration of the sidelink bandwidth part (BWP) .

depending on sub-carrier spacing

During the procedure, if the parameter sl-PreemptionEnable is provided, and if it is not equal to 'enabled' , internal parameter prio _pre is set to the higher layer provided parameter sl-PreemptionEnable.

If a resource r _i from the set (r ₀, r ₁, r ₂, ... ) is not a member of S _A, then the UE shall report re-evaluation of the resource r _i to higher layers, where the set S _A includes the candidate single-slot resources.

If a resource r′ _i from the set (r′ ₀, r′ ₁, r′ ₂, ... ) meets the conditions below then the UE shall report pre-emption of the resource r′ _i to higher layers:

- r′ _i is not a member of S _A, and

- r′ _i meets the conditions for exclusion, with Th (prio _RX, prio _TX) set to the final threshold after executing steps 1) -7) , i.e. including all necessary increments for reaching X·M _total, and

- the associated priority prio _RX, satisfies one of the following conditions:

i. sl-PreemptionEnable is provided and is equal to 'enabled' and prio _TX>prio _RX

ii. sl-PreemptionEnable is provided and is not equal to 'enabled' , and prio _RX<prio _pre and prio _TX>prio _RX.

The details of the above UE procedure for determining the subset of resources to be reported to higher layers in PSSCH resource selection may be found in 3GPP documents, such as 3GPP TS 38.214.

In NR sidelink inter-UE coordination is supported to enhance the reliability of mode 2. For inter-UE coordination scheme, one UE may transmit its reserved resource (s) to other UE (s) , other UE (s) may detect the resource conflict between the reserved resource (s) and other UE's reserved resources (s) or half-duplex on the reserved resource (s) , then the UE transmits the resource conflict indicator to the UE with reserved resources. The resource conflict indicator is carried in the PSFCH. It is agreed that a resource pool level (pre-) configuration may use either one of the following options:

Option 1: PSFCH occasion is derived by a slot where the UE_B's SCI is transmitted.

- Reuse PSSCH-to-PSFCH timing to determine the PSFCH occasion for resource conflict indication

- The time gap between the PSFCH and a slot where expected/potential resource conflict occurs is larger than or equal to T3 slots, where T3 is a preconfigured number.

Option 2: PSFCH occasion is derived by a slot where expected/potential resource conflict occurs on PSSCH resource indicated by UE-B's SCI

- UE_A transmits the PSFCH in a latest slot that includes PSFCH resources for inter-UE coordination information and is at least T3 slots of the resource pool before the PSSCH resource indicated by UE-B's SCI in which expected/potential resource conflict occurs.

It should be noted that it is possible that neither option 1 nor option 2 is configured.

The present disclosure proposes some solutions for resource re-evaluation or pre-emption checking for sidelink intra-band CA.

Specifically, suppose there are two carriers in the intra-band CA, the first carrier and the second carrier. On the first carrier, the first UE would perform the first PSFCH reception and the first PSFCH reception on the first carrier is associated with the resource which the UE is performing re-evaluation or pre-emption checking.

On the second carrier, the first UE would perform the second PSFCH transmission on the second carrier, the second PSFCH transmission may be for sidelink HARQ feedback or resource conflict indicator for inter-UE coordination scheme 2.

If the first PSFCH reception and the second PSFCH transmission partially overlaps, or fully overlaps in time domain, in other words, the half-duplex issue occurs, the first UE may trigger resource re-selection of one resource on the first carrier.

In the CA in Fig. 2, there are at least two component carriers, CC 1 and CC2. On CC1, the first UE intends to perform sidelink transmission on resource#1 (within the time period from t ₄ to t ₅) , and HARQ feedback is enabled for the sidelink transmission on resource#1. Resource#1 is the resource on which the first UE intends to perform re-evaluation or pre-emption procedure. PSFCH#1 on CC1, which is associated with resource#1, is for receiving sidelink HARQ feedback for the sidelink transmission on resource#1. PSFCH#1 is within the time period from t ₈ to t ₉.

On CC2, the first UE receives physical sidelink shared channel (PSSCH) with HARQ enabled from the second UE (within the time period from t ₁ to t ₂) . HARQ enabled means that the first UE is supposed to transmit the HARQ feedback for the PSSCH received from the second UE. PSFCH#2 on CC2, which is associated with the PSSCH received from the second UE, is for transmitting sidelink HARQ feedback for the received PSSCH, and PSFCH#2 is within the time period from t ₆ to t ₇ on CC2. PSFCH#2 may be determined by the PSSCH-to-PSFCH timing.

According to Fig. 2, the time gap between the PSSCH on CC2 (the time period from t ₁ to t ₂) and resource#1 on CC1 (the time period from t ₂ to t ₄) is more than T3 slot (s) in time domain, wherein T3 is a predefined value. As shown in Fig. 2, the time period from t ₃ to t ₄ is T3 slot (s) , and t ₃ is after t ₂ in time domain. The length of the time duration: T3 slot (s) may be represented with other units, such as frames, sub-frames, etc.

As shown in the drawings of the present disclosure, PSFCH#1 and PSFCH#2 overlap (fully or partially overlapping) in time domain. That is, the time period 1 (from t ₈ to t ₉) and the time period 2 (from t ₆ to t ₇) fully or partially overlap. For example, the time point t ₆ and/or the time point t ₇ are within the timer period 1 (from t ₈ to t ₉) , the time point t ₈ and/or the time point t ₉ are within the timer period 2 (from t ₆ to t ₇) .

It should be noted the time points in the drawings of the present disclosure, i.e. t ₁, t ₂, …, t ₉, …, t ₁₁, may be represented with units of slots, for example, t ₁ is at slot 1, t ₂ is at slot 2, …, t ₉ is at slot 9, …, t ₁₁ is at slot 11, etc. The time point may be represented with units of frames, subframes, etc.

On CC1, the UE performs the resource re-evaluation or pre-emption procedure, to check whether there is half-duplex issue for resource#1. Based on the resource re-evaluation or pre-emption procedure, the UE found that PSFCH#1 and PSFCH#2 overlap, and the first UE has resource conflict with the second UE.

Among the CCs of the CA, the UE may perform the resource re-evaluation or pre-emption procedure for one or more CCs of the CA, in a similar way as for CC1.

In Fig. 3, there are also at least two component carriers, CC 1 and CC2. On CC1, the first UE intends to perform sidelink transmission on resource#1 (within the time period from t ₄ to t ₅) , and HARQ feedback is enabled for the sidelink transmission on resource#1. Resource#1 is the resource on which the first UE intends to perform re-evaluation or pre-emption procedure. PSFCH#1 on CC1, which is associated with resource#1, is for receiving sidelink HARQ feedback for the sidelink transmission on resource#1. PSFCH#1 is within the time period from t ₈ to t ₉.

On CC2, the first UE receives PSSCH#1 with HARQ feedback enabled. PSFCH#3 on CC2, which is associated with the received PSSCH#1, is for transmitting sidelink HARQ feedback for the received PSSCH#1. PSSCH#1 reserves PSSCH#2, which is reserved for a subsequent transmission (or re-transmission) from the second UE. PSFCH#2 on CC2, which is associated with the reserved PSSCH#2, is for transmitting sidelink HARQ feedback for the received PSSCH#2. PSFCH#2 is within the time period from t ₆ to t ₇ on CC2.

In this case, whether the first UE triggers resource re-selection of resource#1 or take other actions to avoid the resource conflict, is further based on decoding result of PSSCH#1 (or based on HARQ-ACK, or HARQ-NACK feedback on PSFCH#3) , if the first UE decoded PSSCH#1 unsuccessfully, and the first UE may transmit HARQ-NACK feedback on PSFCH#3 to the second UE. Then the second UE will perform re-transmission of PSSCH#2. Since it is a re-transmission, PSSCH#2 may also be enabled with HARQ feedback. Accordingly, the first UE has high probability to transmit PSFCH#2, so the first UE may trigger resource re-selection of resource#1 or take other actions to avoid the resource conflict.

If the first UE decoded PSSCH#1 successfully, the reserved PSSCH#2 would not be used for re-transmit PSSCH#1. In this scenario, PSSCH#2 may be with or without HARQ feedback enabled, which is up to the second UE implementation. The second UE may perform sidelink transmission with or without HARQ feedback enabled, so it is up to second UE implementation as to whether trigger resource re-selection of resource#1 or take other actions to avoid the resource conflict.

In Figs. 4A and 4B, there are also two component carriers, CC1 and CC2. On CC1, the first UE intends to perform sidelink transmission on resource#1 (within the time period from t ₄ to t ₅) , and HARQ feedback is enabled for the sidelink transmission on resource#1. Resource#1 is the resource on which the first UE intends to perform re-evaluation or pre-emption procedure. PSFCH#1 on CC1, which is associated with resource#1, is for receiving sidelink HARQ feedback for the sidelink transmission on resource#1. PSFCH#1 is within the time period from t ₈ to t ₉.

On CC2, the first UE receives PSSCH#1. PSSCH#1 reserves PSSCH#2 (within the time period from t ₁₀ to t ₁₁) , and PSFCH#2 (within the time period from t ₆ to t ₇) on CC2 is for transmitting resource conflict indicator and is associated with reserved PSSCH, i.e. PSSCH#2.

The PSFCH for the resource conflict indicator transmission may be configured to be associated with the sidelink control information (SCI) which reserves the resource that potential resource conflict occurs, or configured to be associated with the reserved resource that expected or potential resource conflict occurs.

In Fig. 4A, PSFCH#2 for the resource conflict indicator transmission is configured to be associated with the sidelink control information (SCI) which reserves the resource. The UE receives PSSCH#1 at least T3 slot (s) before resource#1, and PSSCH#1 reserves PSSCH#2, if resource conflict happens on PSSCH#2, the UE may transmit PSFCH#2 which is associated with PSSCH#1 for resource conflict indicator. PSFCH#1 and PSFCH#2 overlap in time domain.

In Fig. 4B, PSFCH#2 for resource conflict indicator is configured to be associated with the reserved resource, i.e. PSSCH#2, that expected or potential resource conflict occurs. The UE receives PSSCH#1 at least T3 slots before Resource#1, and PSSCH#1 reserves PSSCH#2, if resource conflict happens on PSSCH#2 the UE may transmit PSFCH#2 which is associated with PSSCH#2 for resource conflict indicator. PSFCH#1 and PSFCH#2 overlap in time domain.

The present disclosure proposes several solutions for solving the above resource conflict issues. Specifically, the first UE may determine whether to trigger resource re-selection of resource#1, or take other actions. The detailed options as presented as follows:

Solution 1:

The first UE always triggers resource re-selection of resource#1 for the scenarios in Figs. 2, 3, 4A and 4B.

Solution 2:

Whether the first UE triggers resource re-selection of resource#1 is further based on the priority.

Suppose the priority of the intended transmission on resource#1 on CC1 the priority 1; and the highest priority of sidelink transmissions associated with PSFCH on CC2 is priority 2.

In the case that priority 1 is lower than priority 2, the first UE triggers resource re-selection of resource#1.

In the case that priority 1 is higher than or equal to priority 2, the first UE does not trigger resource re-selection of resource#1. In other words, the first UE continues the sidelink transmission on resource#1 on CC1, and performs reception of PSFCH#1 for HARQ feedback on CC1. The UE may drop PSFCH#2 on CC2.

In some embodiments, a priority threshold is configured. In these embodiments, the first UE triggers resource re-selection of resource#1 if the following two conditions are satisfied:

- priority 1 is lower than priority 2; and

- priority 2 is higher than the priority threshold.

If the above two conditions are met, it means that the PSFCH transmission on CC2 is very important, and the first UE performs the PSFCH transmission on CC2.

If the above two conditions are not met, the first UE does not trigger resource re-selection of resource#1. In other words, the first UE continues the sidelink transmission on resource#1 on CC1, and performs reception of PSFCH#1 for HARQ feedback on CC1. The UE may drop PSFCH#2 on CC2.

Solution 3:

The first UE doesn't trigger resource re-selection of resource#1, instead, the first UE disables the HARQ feedback on the transmission on resource#1. In other words, the HARQ feedback which is transmitted in PSFCH#1 in Figs. 2-4B are disabled, in this case, the receiving UE that receives sidelink transmission from the first UE will not transmit feedback on the PSFCH#1. Correspondingly, at the first UE side, the first UE would not perform reception of PSFCH#1 in CC1, and it would perform transmission of PSFCH#2 on CC2.

With the above solutions, the resource conflict issues are solved.

In should be noted that the above three solutions may be applied separately or in any combination. For example, the first UE may disable the HARQ feedback on the transmission on resource#1 (solution 3) and also drop PSFCH#2 on CC2 (solution 2) . Alternatively, the first UE may triggers resource re-selection of resource#1 (solution 1) , and also drop PSFCH#2 on CC2 (solution 2) . Alternatively, the first UE may triggers resource re-selection of resource#1 (solution 1) and disable the HARQ feedback on the transmission on resource#1 (solution 3) . Alternatively, the first UE may triggers resource re-selection of resource#1 (solution 1) , disable the HARQ feedback on the transmission on resource#1 (solution 3) , and also drop PSFCH#2 on CC2 (solution 2) . Any combination of the above solutions is not limited in the present disclosure.

In operation 501, the UE determines whether a first PSFCH on a first CC overlaps with a second PSFCH on a second CC, wherein the first PSFCH is associated with a first resource for a first SL transmission.

In operation 502, in the case that the first PSFCH and the second PSFCH at least partially overlaps in time domain, the UE performs at least one of the following action: performing a resource re-selection procedure for the first resource; disabling HARQ feedback for the first SL transmission; or dropping the second PSFCH on the second CC.

In some embodiments, the first PSFCH is for receiving HARQ feedback for the first SL transmission on the first CC. For example, PSFCH#1 in Fig. 2 is for receiving HARQ feedback the SL transmission on resource#1.

In some embodiments, the second PSSCH is received on the second CC or is reserved by a third PSSCH for re-transmission from another UE. For example, PSFCH#2 in Fig. 3 is reserved by a PSSCH#1 for re-transmission from the second UE.

In some embodiments, in case the third PSSCH is successfully decoded, the UE determines whether to perform a resource re-selection procedure for the first SL resource based on UE implementation. For example, PSFCH#1 is successfully decoded, whether to perform a resource re-selection procedure for the first SL resource depends on PSFCH#2 is with HARQ feedback enabled or disabled, which is based on UE implementation.

In some embodiments, the UE further performs a resource re-selection procedure for the first resource based on a first priority of the first SL transmission to be transmitted on the first resource and/or a second priority of a second SL transmission associated with the second PSFCH.

In some embodiments, the first priority is lower than a highest priority for the second SL transmission. In some embodiments, the highest priority for the second SL transmission is higher than a priority threshold.

Fig. 6 illustrates a simplified block diagram of an exemplary apparatus 600 according to some embodiments of the present disclosure. The apparatus 600 may be or include at least a part of a UE, or other device with similar functionality.

As shown in Fig. 6, the apparatus 600 may include a transceiver 601, and a processor 602. It is contemplated that the apparatus 600 may include other components not shown in Fig. 6.

The transceiver 601 and the processor 602 can be configured to perform any of the methods described in the present disclosure, for example, the method described with respect to Fig. 5.

For example, the processor 602 may determine whether a first PSFCH on a first CC overlaps with a second PSFCH on a second CC, wherein the first PSFCH is associated with a first resource for a first SL transmission. In the case that the first PSFCH and the second PSFCH at least partially overlaps in time domain, the processor 602 may perform at least one of the following action: the processor 602 may perform a resource re-selection procedure for the first resource; disable HARQ feedback for the first SL transmission; or drop the second PSFCH on the second CC.

The method of the present disclosure can be implemented on a programmed processor. However, 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 other embodiments. Also, all of the elements shown in each Fig. 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 user equipment (UE) , comprising:

a transceiver; and

a processor coupled to the transceiver, wherein the processor is configured to:

determine whether a first physical sidelink feedback channel (PSFCH) on a first component carrier (CC) overlaps with a second PSFCH on a second CC, wherein the first PSFCH is associated with a first resource for a first sidelink (SL) transmission; and

in the case that the first PSFCH and the second PSFCH at least partially overlaps in time domain, perform at least one of the following action:

perform a resource re-selection procedure for the first resource;

disable hybrid automatic repeat request (HARQ) feedback for the first SL transmission; or

drop the second PSFCH on the second CC.
The UE of Claim 1, wherein the first PSFCH is for receiving HARQ feedback for the first SL transmission on the first CC.
The UE of Claim 1, wherein the second PSFCH is for transmitting HARQ feedback for a second physical sidelink shared channel (PSSCH) on the second CC and/or for transmitting a resource conflict indicator.
The UE of Claim 1, wherein the second PSSCH is received on the second CC or is reserved by a third PSSCH for re-transmission from another UE.
The UE of Claim 1, wherein in case the third PSSCH is successfully decoded, the processor is configured to determine whether to perform a resource re-selection procedure for the first SL resource based on UE implementation.
The UE of Claim 1, wherein the processor is further configured to:

perform a resource re-selection procedure for the first resource based on a first priority of the first SL transmission to be transmitted on the first resource and/or a second priority of a second SL transmission associated with the second PSFCH.
The UE of Claim 6, wherein the first priority is lower than a highest priority for the second SL transmission.
The UE of Claim 7, wherein the highest priority for the second SL transmission is higher than a priority threshold.
A method performed by a user equipment (UE) , comprising:

determining whether a first physical sidelink feedback channel (PSFCH) on a first component carrier (CC) overlaps with a second PSFCH on a second CC, wherein the first PSFCH is associated with a first resource for a first sidelink (SL) transmission; and

in the case that the first PSFCH and the second PSFCH at least partially overlaps in time domain, performing at least one of the following action:

performing a resource re-selection procedure for the first resource;

disabling hybrid automatic repeat request (HARQ) feedback for the first SL transmission; or

dropping the second PSFCH on the second CC.
The method of Claim 9, wherein the first PSFCH is for receiving HARQ feedback for the first SL transmission on the first CC.
The method of Claim 9, wherein the second PSFCH is for transmitting HARQ feedback for a second physical sidelink shared channel (PSSCH) on the second CC and/or for transmitting a resource conflict indicator.
The method of Claim 9, wherein the second PSSCH is received on the second CC or is reserved by a third PSSCH for re-transmission from another UE.
The method of Claim 9, wherein in case the third PSSCH is successfully decoded, the processor is configured to determine whether to perform a resource re-selection procedure for the first SL resource based on UE implementation.
The method of Claim 9, further comprising:

performing a resource re-selection procedure for the first resource based on a first priority of the first SL transmission to be transmitted on the first resource and/or a second priority of a second SL transmission associated with the second PSFCH.
The method of Claim 14, wherein the first priority is lower than a highest priority for the second SL transmission.