WO2024065433A1

WO2024065433A1 - Method, device, and medium for communication

Info

Publication number: WO2024065433A1
Application number: PCT/CN2022/122758
Authority: WO
Inventors: Zhaobang MIAO; Jin Yang; Ying Zhao; Gang Wang
Original assignee: Nec Corporation
Priority date: 2022-09-29
Filing date: 2022-09-29
Publication date: 2024-04-04

Abstract

Example embodiments of the present disclosure relate to a solution for resource selection and reselection for sidelink communication. In this solution, a second device determines a group of first resources unavailable for sidelink transmission based on sidelink control indication (SCI) from a first device. The SCI indicates resource reservation of the group of first resources in a resource pool for sidelink communication. The second device selects, from the resource pool, a group of second resources for a first transmission based on a sensing result and the SCI. Prior to transmitting the first transmission, the second device determines whether at least one of the group of first resources is available for sidelink transmission. If at least one first resource is available, the second device reselects a group of third resources comprising the at least one first resource. The first device then transmits the first transmission on the group of third resources.

Description

METHOD, DEVICE, AND MEDIUM FOR COMMUNICATION

FIELD

Example embodiments of the present disclosure generally relate to the field of communication techniques and in particular, to a method, device, and medium for resource selection and reselection in sidelink communication.

BACKGROUND

In 5G NR, sidelink communication has been developed on unlicensed spectrum, which is also called SL-U. In SL-U, user equipment (UE) may select or reselect resources for sidelink transmission from a preconfigured resource pool in an autonomous way. In particular, the UE performs sensing on a sidelink channel during a certain period (e.g., a sensing window) . Based on a sensing result, the UE may select, reselect or even reserve multiple resources for its current or future transmissions. Sidelink control information (SCI) may be used for informing other UEs of the resource selection or reservation.

Furthermore, channel access mechanisms are introduced to SL-U operations. For example, before transmitting data, the UE performs a clear channel assessment (CCA) procedure. If CCA indicates that the sidelink channel is idle, then the UE is allowed to transmit the data. However, if CCA indicates that the sidelink channel is busy, then the UE is not allowed to access the sidelink channel, which may lead to the SCI for resource reservation failed to be sent.

SUMMARY

In general, embodiments of the present disclosure provide methods, devices and computer storage medium for resource selection and reselection in sidelink communication.

In a first aspect, there is provided a communication method performed by a second device. The communication method comprises: determining, at a second device, a group of first resources unavailable for sidelink transmission based on sidelink control indication (SCI) from a first device, the SCI indicating resource reservation of the group of first resources in a resource pool for sidelink communication; selecting, from the resource pool, a group of second resources for a first transmission based on a sensing result and the SCI; prior to transmitting the first transmission, determining whether at least one of the group of first resources is available for sidelink transmission; in accordance with a determination that the at least one first resource is available, reselecting a group of third resources comprising the at least one first resource; and transmitting the first transmission on the group of third resources.

In a second aspect, there is provided a communication method performed by a first device. The communication method comprises: in accordance with a determination that a clear channel assessment (CCA) for a fourth resource is failed, selecting, at a first device and from a resource pool for sidelink communication, a fifth resource for a second transmission, the fourth resource being reserved for transmitting the second transmission and intended for indicating a reservation of a group of sixth resources for at least a third transmission; transmitting the second transmission on the fifth resource; and transmitting the third transmission on at least one of the group of sixth resources.

In a third aspect, there is provided a communication device. The communication device includes a processing unit; and a memory coupled to the processing unit and storing instructions thereon, the instructions, when executed by the processing unit, causing the device to perform the method according to the first aspect.

In a fourth aspect, there is provided a communication device. The communication device includes a processing unit; and a memory coupled to the processing unit and storing instructions thereon, the instructions, when executed by the processing unit, causing the device to perform the method according to the second aspect.

In a fifth aspect, there is provided a computer readable medium having instructions stored thereon, the instructions, when executed on at least one processor, causing the at least one processor to carry out the method according to the first aspect.

In a sixth aspect, there is provided a computer readable medium having instructions stored thereon, the instructions, when executed on at least one processor, causing the at least one processor to carry out the method according to the second aspect.

Other features of the present disclosure will become easily comprehensible through the following description.

BRIEF DESCRIPTION OF THE DRAWINGS

Through the more detailed description of some embodiments of the present disclosure in the accompanying drawings, the above and other objects, features and advantages of the present disclosure will become more apparent, wherein:

FIG. 1 illustrates an example communication environment in which example embodiments of the present disclosure can be implemented;

FIG. 2A illustrates a schematic diagram of an example sensing mechanism for sidelink communication according to some embodiments of the present disclosure;

FIG. 2B illustrates a schematic diagram of an example resource reevaluation mechanism for sidelink communication according to some embodiments of the present disclosure;

FIG. 2C illustrates a schematic diagram of an example resource pre-emption mechanism for sidelink communication according to some embodiments of the present disclosure;

FIG. 3 illustrates a diagram of an example method for sidelink according to some embodiments of the present disclosure;

FIG. 4 illustrates a schematic diagram of an example resource selection and reselection mechanism for sidelink according to some embodiments of the present disclosure;

FIG. 5A illustrates a schematic diagram of an example resource (re-) selection according to some embodiments of the present disclosure;

FIG. 5B illustrates a schematic diagram of an example sidelink grant for resources according to some embodiments of the present disclosure;

FIG. 6 illustrates a diagram of an example method for sidelink according to some embodiments of the present disclosure;

FIG. 7 illustrates a schematic diagram of an example resource selection and reselection mechanism for sidelink according to some embodiments of the present disclosure;

FIG. 8 illustrates a simplified block diagram of an apparatus that is suitable for implementing example embodiments of the present disclosure.

Throughout the drawings, the same or similar reference numerals represent the same or similar element.

DETAILED DESCRIPTION

Principle of the present disclosure will now be described with reference to some embodiments. It is to be understood that these embodiments are described only for the purpose of illustration and help those skilled in the art to understand and implement the present disclosure, without suggesting any limitations as to the scope of the disclosure. The disclosure described herein can be implemented in various manners other than the ones described below.

In the following description and claims, unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skills in the art to which this disclosure belongs.

As used herein, the term ‘terminal device’ refers to any device having wireless or wired communication capabilities. Examples of the terminal device include, but not limited to, UE, personal computers, desktops, mobile phones, cellular phones, smart phones, personal digital assistants (PDAs) , portable computers, tablets, wearable devices, internet of things (IoT) devices, Ultra-reliable and Low Latency Communications (URLLC) devices, Internet of Everything (IoE) devices, machine type communication (MTC) devices, devices on vehicle for V2X communication where X means pedestrian, vehicle, or infrastructure/network, devices for Integrated Access and Backhaul (IAB) , Space borne vehicles or Air borne vehicles in Non-terrestrial networks (NTN) including Satellites and High Altitude Platforms (HAPs) encompassing Unmanned Aircraft Systems (UAS) , eXtended Reality (XR) devices including different types of realities such as Augmented Reality (AR) , Mixed Reality (MR) and Virtual Reality (VR) , the unmanned aerial vehicle (UAV) commonly known as a drone which is an aircraft without any human pilot, devices on high speed train (HST) , or image capture devices such as digital cameras, sensors, gaming devices, music storage and playback appliances, or Internet appliances enabling wireless or wired Internet access and browsing and the like. The ‘terminal device’ can further has ‘multicast/broadcast’ feature, to support public safety and mission critical, V2X applications, transparent IPv4/IPv6 multicast delivery, IPTV, smart TV, radio services, software delivery over wireless, group communications and IoT applications. It may also incorporate one or multiple Subscriber Identity Module (SIM) as known as Multi-SIM. The term “terminal device” can be used interchangeably with a UE, a mobile station, a subscriber station, a mobile terminal, a user terminal or a wireless device.

The term “network device” refers to a device which is capable of providing or hosting a cell or coverage where terminal devices can communicate. Examples of a network device include, but not limited to, a Node B (NodeB or NB) , an evolved NodeB (eNodeB or eNB) , a next generation NodeB (gNB) , a transmission reception point (TRP) , a remote radio unit (RRU) , a radio head (RH) , a remote radio head (RRH) , an IAB node, a low power node such as a femto node, a pico node, a reconfigurable intelligent surface (RIS) , and the like.

The terminal device or the network device may have Artificial intelligence (AI) or Machine learning capability. It generally includes a model which has been trained from numerous collected data for a specific function, and can be used to predict some information.

The terminal or the network device may work on several frequency ranges, e.g., FR1 (410 MHz to 7125 MHz) , FR2 (24.25GHz to 71GHz) , frequency band larger than 100GHz as well as Tera Hertz (THz) . It can further work on licensed/unlicensed/shared spectrum. The terminal device may have more than one connection with the network devices under Multi-Radio Dual Connectivity (MR-DC) application scenario. The terminal device or the network device can work on full duplex, flexible duplex and cross division duplex modes.

The embodiments of the present disclosure may be performed in test equipment, e.g., signal generator, signal analyzer, spectrum analyzer, network analyzer, test terminal device, test network device, channel emulator.

In some embodiments, the terminal device may be connected with a first network device and a second network device. One of the first network device and the second network device may be a master node and the other one may be a secondary node. The first network device and the second network device may use different radio access technologies (RATs) . In some embodiments, the first network device may be a first RAT device and the second network device may be a second RAT device. In some embodiments, the first RAT device is eNB and the second RAT device is gNB. Information related with different RATs may be transmitted to the terminal device from at least one of the first network device or the second network device. In some embodiments, first information may be transmitted to the terminal device from the first network device and second information may be transmitted to the terminal device from the second network device directly or via the first network device. In some embodiments, information related with configuration for the terminal device configured by the second network device may be transmitted from the second network device via the first network device. Information related with reconfiguration for the terminal device configured by the second network device may be transmitted to the terminal device from the second network device directly or via the first network device.

As used herein, the singular forms ‘a’ , ‘an’ and ‘the’ are intended to include the plural forms as well, unless the context clearly indicates otherwise. The term ‘includes’ and its variants are to be read as open terms that mean ‘includes, but is not limited to. ’ The term ‘based on’ is to be read as ‘at least in part based on. ’ The term ‘one embodiment’ and ‘an embodiment’ are to be read as ‘at least one embodiment. ’ The term ‘another embodiment’ is to be read as ‘at least one other embodiment. ’ The terms ‘first, ’ ‘second, ’ and the like may refer to different or same objects. Other definitions, explicit and implicit, may be included below.

In some examples, values, procedures, or apparatus are referred to as ‘best, ’ ‘lowest, ’ ‘highest, ’ ‘minimum, ’ ‘maximum, ’ or the like. It will be appreciated that such descriptions are intended to indicate that a selection among many used functional alternatives can be made, and such selections need not be better, smaller, higher, or otherwise preferable to other selections.

As used herein, the term “resource, ” “transmission resource, ” “uplink resource, ” or “downlink resource” may refer to any resource for performing a communication, such as a resource in time domain, a resource in frequency domain, a resource in space domain, a resource in code domain, or any other resource enabling a communication, and the like. In the following, unless explicitly stated, a resource in both frequency domain and time domain will be used as an example of a transmission resource for describing some example embodiments of the present disclosure. It is noted that example embodiments of the present disclosure are equally applicable to other resources in other domains.

As used herein, the term “reevaluation” or “resource reevaluation” may refer to the resource (s) of a selected sidelink grant for a Media Access Control protocol data unit (MAC PDU) to transmit from multiplexing and assembly entity is reevaluated by the physical layer at a certain time instant before the slot where the SCI indicating the resource (s) is signaled at first time.

As used herein, the term “pre-emption” or “resource pre-emption” may refer to the resource (s) of a selected sidelink grant which has been indicated by a prior SCI for a MAC PDU to transmit from multiplexing and assembly entity could be checked for pre-emption by physical layer at a certain time instant before the slot where the resource (s) is located.

In SL-U, UE performs sensing on the sidelink channel to determine whether resources are used or reserved by other UEs. During the sensing window, the UE detects if any SCI is transmitted on the sidelink channel and compares the Physical Sidelink Control Channel Reference Signal Received Power (PSCCH-RSRP) or Physical Sidelink Shared Channel Reference Signal Received Power (PSSCH-RSRP) associated with the SCI transmission with a RSRP threshold. Based on the SCI decoded and RSRP comparison in the sensing window, the UE can exclude the reserved resources from candidate resources within a resource selection window, and then select or re-select resources for sidelink transmissions. Specifically, periodic reservation of resources is also supported. In this case, the UE may pre-select periodic resources for its future transmissions.

As previously mentioned, the UE needs to perform the CCA procedure before transmitting data on a selected or reserved resource. If CCA is failed, the UE has to drop the resource and reselect another one. This may cause a failure of transmitting SCI that are expected to be transmitted on the resource and indicates a periodic reservation of subsequent resources. Since other UEs may be unaware of the periodic reservation, they may (re-) select those resources for their transmissions. As result, a resource collision and latency are increased.

In order to solve the above issue or any other potential issues, embodiments of the present disclosure provide a resource (re-) selection solution for sidelink communication. In the solution, the UE can either drops all the pre-selected periodic resources for future transmission, or continue to use the pre-selected periodic resources if CCA for a reserved resource is failed.

For the former case, other UE is able to (re-) select an excluded or unavailable resource for sidelink transmission by re-checking whether it turns into an available resource. In this way, it is likely to achieve consecutive slots transmission from the other UE, which help retain the channel occupancy time (COT) . For the latter case, the UE reselects another resource for transmitting the SCI indicating the pre-selected periodic resources. Thus, other UEs still have an opportunity to detect and know the periodic resource reservation. With the solution, the resource collision due to CCA failure can be avoided. In addition, the COT can be retained.

Principles and implementations of the present disclosure will be described in detail below with reference to the figures.

EXAMPLE OF COMMUNICATION NETWORK

FIG. 1 illustrates a schematic diagram of an example communication environment 100 in which example embodiments of the present disclosure can be implemented.

The communication environment 100 includes a first device 110 and a second device 120. The first device 110 and the second device 120 may be terminal devices, such as, UEs. In some embodiments, the first device 110 and the second device 120 may communicate with each other via a sidelink channel on unlicensed spectrum. A sidelink is a communication mode that allows direct communications between two or more terminal devices without the communications going through network device. Sidelink communications may be carried out on a wireless interface, e.g., PC5 interface. SL communications may be unicast, groupcast, or broadcast, and may be used for device-to-device (D2D) communications, vehicle-to-everything (V2X) communications, emergency rescue applications, etc. The sidelink channel may include, but not limited to, a Physical Sidelink Feedback Channel (PSFCH) , a PSSCH, a PSCCH, and a Physical Sidelink Broadcast Channel (PSBCH) , etc.

Depending on whether covered within a serving area of a network device or not, sidelink communication scenarios may include in-coverage, partial-coverage, and out-of-coverage (OOC) . In some cases, the communication network 100 may further include a network device (not shown in FIG. 1) that facilitates the scheduling of resources for sidelink communications. In other cases, sidelink communications are carried out between the first device 110 and the second device 120 without the involvement of a network device.

Sidelink resource allocation schemes may be applied for allocating resources in a resource pool for sidelink communications. There may be two sidelink resource allocation schemes. In a first sidelink resource allocation scheme, which is also referred to as Mode 1 for sidelink resource allocation, the network device may schedule sidelink resources via the communication interface with the first device 110 or the second device 120. The resource allocation may include dynamic grant, for example, by downlink control information (DCI) , or configured grant (e.g., Type 1 or Type 2 configured grant) . In a second sidelink resource allocation scheme, which is also referred to as Mode 2 for sidelink resource allocation, the resources for sidelink communications may be autonomously selected by the first device 110 and the second device 120 based on a contention scheme (e.g., sensing procedure) .

In the context of the embodiments, either of the first device 110 and the second device 120 may act as a transmitting (Tx) device that transmits control information (e.g., SCI) , data transmission (e.g., transport block (TB) ) , and so the like on the sidelink channel. Accordingly, the other one of the first device 110 and the second device 120 that monitors the sidelink channel and receives the SCI and selectively the data transmission may act as a receiving (Rx) device. In other words, the TX device and the Rx device are not fixed in the communication environment 100, which depend on devices’ behavior.

For the purpose of discussion, some embodiments may be described with reference to the first device 110 as the Tx device. However, it should be understood that in some cases, the operations of the first device 110 and the second device 120 may be exchanged with each other. Therefore, the present disclosure is not limited to this regard.

In some embodiments, the first device 110 may perform sensing on the sidelink channel for (re-) selecting and reserving resources for sidelink transmissions. FIG. 2A illustrates a schematic diagram of an example sensing mechanism 200 for sidelink communication according to some embodiments of the present disclosure. As shown in FIG. 2A, during a sensing window 201, the first device 110 monitors the sidelink channel, and determines available candidate resources within a resource selection window (RSW) 202 based on detection of SCI on a resource R.

The first device 110 may then select and periodically reserve resources r ₀ to r ₂, r ₄ to r ₅, …, r _n to r _q which correspond to different reservation periods. In particular, the resource r ₀ may be used for transmitting SCI that indicates a reservation of the resources r ₁ and r ₂ as well as a periodic reservation of the resources r ₄ to r ₆, …, r _n to r _q by including a “Resource reservation period” field. Likewise, the first device 110 may also intend to transmit SCI on resource r ₀ to indicate the reservation of the resources r ₁ and r ₂ as well as a periodic reservation of the resources r ₄ to r ₆, …, r _n to r _q.

However, if CCA in the resource r ₀ is failed, the first device 110 may fail to transmit the SCI. In some embodiments, the first device 110 may drop the resources r ₀ to r ₂, r ₄ to r ₅, …, r _n to r _q that are periodically reserved. In this case, other UEs, such as, the second device 120 is able to (re-) select these resources for their transmissions.

Alternatively, in some other embodiments, the first device 110 may reselect another resource for transmitting the SCI that includes an indication of periodic reservation of resources r ₁, r ₂, r _n to r _q and so on. As shown in FIG. 2A, a resource r ₃ subsequent to the resource r ₀ is reselected by the first device 110. In that case, the first device 110 may continue to use the resources r ₁ and r ₂ as well as a periodic reservation of the resources r ₄ to r ₆, …, r _n to r _q, while the other UEs may avoid to (re-) select these resources based on detection of SCI in the reselected resource r ₃. These embodiments will be discussed in detail later.

In some embodiments, before transmitting SCI for indicating resource reservation, the first device 110 may reevaluate a specific resource at a certain time instant. FIG. 2B illustrates a schematic diagram of an example resource reevaluation mechanism 210 for sidelink communication according to some embodiments of the present disclosure. As shown in FIG. 2B, in the RSW 202, the first device 110 intends to transmit SCI for indicating resource reservation on the resource r ₀ at first time, where the resource r ₀ corresponds to slot m in time domain. The L1 of the first device 110 (i.e., physical layer) may reevaluate if these resources are available for sidelink transmission at T1 slots before slot m, i.e., at slot m-T1.

In some embodiments, pre-emption may be enabled in the resource pool. If periodic reservation is adopted, the first device 110 may check pre-emption for resources provided by its MAC layer to L1 (i.e., physical layer) . In particular, L1 expects that MAC layer provides resources intended for at least one transmission of a TB, which may fit to the resource selection window of a current TB of the first device 110, and for which a relevant priority is available. If a resource is pre-empted, a resource re-selection for the at least one transmission due to the pre-empted resource would be triggered.

FIG. 2C illustrates a schematic diagram of an example resource pre-empt mechanism 220 for sidelink communication according to some embodiments of the present disclosure. As shown in FIG. 2C, the first device 110 may transmit SCI indicative of resource reservation of the resource r ₁ corresponding to a slot m’ in time domain. The L1 of the first device 110 may check for pre-emption at T2 slots before the slot m’, i.e., at a slot m’ -T2.

The communications in the communication environment 100 may conform to any suitable standards including, but not limited to, Global System for Mobile Communications (GSM) , Long Term Evolution (LTE) , LTE-Evolution, LTE-Advanced (LTE-A) , New Radio (NR) , Wideband Code Division Multiple Access (WCDMA) , Code Division Multiple Access (CDMA) , GSM EDGE Radio Access Network (GERAN) , Machine Type Communication (MTC) and the like. The embodiments of the present disclosure may be performed according to any generation communication protocols either currently known or to be developed in the future. Examples of the communication protocols include, but not limited to, the first generation (1G) , the second generation (2G) , 2.5G, 2.75G, the third generation (3G) , the fourth generation (4G) , 4.5G, the fifth generation (5G) communication protocols, 5.5G, 5G-Advanced networks, or the sixth generation (6G) networks.

It is to be understood that the number of devices and their connections in FIG. 1 are given for the purpose of illustration without suggesting any limitations to the present disclosure. The communication environment 100 may include any suitable number of network devices and/or terminal devices adapted for implementing implementations of the present disclosure.

WORK PRINCIPLE AND EXAMPLE PROCESS

Example embodiments of the present disclosure provide a solution for resource selection and reselection for sidelink communication. In this solution, the sidelink resources that are periodically reserved will be released in case of CCA failure. Accordingly, other UEs is able to (re-) select these resources for their transmissions, which improves resource use efficiency and retains the COT.

Reference is made to FIG. 3, which illustrates a diagram of an example method 300 for sidelink according to some embodiments of the present disclosure. The method 300 can be implemented at any suitable terminal devices. For the purpose of discussion, the process 300 will be described with reference to FIG. 1. The process 300 may be implemented at the second device 120, which also involves the first device 110.

At block 310, the second device 120 determines a group of first resources unavailable for sidelink transmission based on SCI from the first device 110. The SCI indicates resource reservation of the group of first resources in the resource pool for sidelink communication.

FIG. 4 illustrates a schematic diagram of an example resource selection and reselection mechanism 400 for sidelink according to some embodiments of the present disclosure. As shown in FIG. 4, the first device 110 transmits SCI on a resource R0 (e.g., at slot m) which indicates resource reservation of periodic resources R1 to Rn, that is, the group of first resources. Upon receiving the SCI, the second device 120 may consider the resources R1 to Rn are unavailable for sidelink transmission and thus exclude from its candidate resources.

Due to the CCA failure in the resource R1, the first device 110 fails to access the sidelink channel, and thus the reserved the resources R1 to Rn are released. In other words, at this point, the resources R1 to Rn are available for sidelink transmission but other UEs are unaware of this fact.

At block 320, the second device 120 selects or has higher priority to select, from the resource pool, a group of second resources for a first transmission based on a sensing result and the SCI. As shown in FIG. 4, the second group of resources may include the resources R0’, R1’, R3’ and R4’.

In some cases, the excluded resources may be important or even essential for other UEs’ transmission. By way of example, as shown in FIG. 4 and FIG. 5A, the excluded resource R2 is located among the resources R0’ to R4’ that are selected by the second device 120. If the resource R2 is available, then the second device 120 can achieve a multi-consecutive slots transmission (MCSt) on the consecutive resources R0’, R1’, R2, R3’ and R4’, which helps retain the COT.

To this end, prior to transmitting the first transmission, at block 330, the second device 120 determines whether at least one of the group of first resources is available for sidelink transmission. Such a determination may be implemented based on reevaluation, pre-emption and so on.

In some embodiments, the at least one first resource may correspond to a first time resource. In these embodiments, the second device 120 may determine whether the at least one first resource is available for sidelink transmission at a second time resource before a first time resource. For example, a time offset between the first time resource and the second time resource may be a predetermined value.

As shown in FIG. 4, the first resource of interest is R2, and the first time resource corresponding to R2 is slot n. The second time resource is a time instant T_recheck, and a time offset between the first time resource n and the second time resource T_recheck is T3= n -T_recheck. In other words, the second device 120 may recheck whether the availability of the resource R2 turns from unavailable to available at T_recheck. It should be understood that this recheck procedure could also be applied by the second device 120 at any other proper time, for example, before or after T_recheck.

The resource recheck may be triggered by UE’s higher layer (e.g., MAC layer) . In particular, the higher layer may provide resources of interest (e.g., the resource R2) to the physical layer to request a resource recheck at T_recheck. In some embodiments, if a request for re-checking whether the at least one first resource is available for sidelink transmission is provided from the higher layer to the physical layer, the second device 120 may re-check the availability of the at least one first resource for sidelink transmission based on a sensing procedure at the physical layer.

To re-check the availability, in some embodiments, the second device 120 may determine whether a set of available resources determined based on the sensing result comprises the at least one first resource. By way of example, in response to the resource recheck request from the higher layer, the physical layer may perform sensing at T_recheck to check if the resource R2 is one of the available resources based on full sensing occasions, to check even no other UEs has reserved the first resource.

In the above embodiments, if the set of available resources comprises the at least one first resource, the second device 120 may determine the at least one first resource available for sidelink transmission. In this case, the re-checking result indicating the availability of the at least one first resource may be provided from the physical layer to the higher layer.

Alternatively, as another example, the physical layer may perform sensing based on dedicated sensing occasion in the resource R2. In some embodiments, the second device 120 may determine whether SCI is detected on the at least one first resource. For example, the second device 120 may determine if SCI for reserving the resource R2 is monitored in the resource R1. If no SCI is detected on the at least one first resource, the second device 120 may then determine the at least one first resource available for sidelink transmission.

Otherwise, if SCI is detected on the at least one first resource, the second device 120 may further measure a signal strength on the at least one first resource. If the signal strength is below a predetermined threshold, the second device 120 may determine the at least one first resource available for sidelink transmission. For example, the signal strength may be estimated by RSRP of PSCCH or PSSCH. If the signal strength is not below the predetermined threshold, the second device 120 may determine the at least one first resource unavailable for sidelink transmission.

If the at least one first resource is determined to be available, at block 340, the second device 120 reselects a group of third resources comprising the at least one first resource. In the example shown in FIG. 5, as the resource R2 is available based on the recheck result, the second device 120 may reselect a group of third resources comprising the resources R0’, R1’, R2, R3’ and R4’.

In some example embodiments, the second device 12 may determine whether the at least one first resource is available for sidelink transmission. If the least one first resource is determined to be available, the second device 120 may adjust a first sidelink grant for the group of second resources to a second sidelink grant for the group of third resources at the higher layer. As shown in FIG. 5B, as the physical layer reports a recheck success to the MAC layer, the MAC layer may adjust the sidelink grant 1 to the sidelink grant 2 for the group of third resources.

At block 350, the second device 120 transmits the first transmission on the group of third resources. In some example embodiments, the first transmission can be performed as MCSt.

Through this solution, the UE is able to reselect resources that were previously indicated as reserved but actually released by other UE (s) . In this way, resource utilization and resource reservation efficiency can be improved, and the COT can be retained in sidelink communication.

According to the example embodiments of the present disclosure, there is provided another solution for selection and reselection for sidelink communication. With this solution, UE can utilize the sidelink resources that are periodically reserved even in case of CCA failure. To this end, a further resource is reselected as a substitute of the resource in which CCA has failed. The UE may use the substitute resource for transmitting an indication of periodic resource reservation. In this way, the resource collision and latency can be reduced.

Detailed description related to the selection and reselection solution will be provided in reference to FIG. 6, which illustrates a flowchart of an example method 600 in accordance with an embodiment of the present disclosure. The method 600 can be implemented at any suitable terminal devices. Only for the purpose of discussion, the method 600 will be described with reference to FIG. 1. For example, the method 600 may be implemented at the first device 110, which may also involve the second device 120.

At block 610, the first device 110 determines if a CCA for a fourth resource is failed. The fourth resource may be reserved for transmitting the second transmission and intended for indicating a reservation of a group of sixth resources for at least a third transmission.

FIG. 7 illustrates a schematic diagram of an example resource selection and reselection mechanism 700 for sidelink according to some embodiments of the present disclosure. As shown in FIG. 7, the first device 110 intends to transmit SCI on the resource R1 (e.g., the fourth resource) which indicates resource reservation of the periodic resources R2 to Rn, that is, the group of sixth resources.

If the CCA for the fourth resource is failed, at block 620, the first device 110 selects a fifth resource for a second transmission from the resource pool for sidelink communication. In the example shown in FIG. 7, the fifth resource may be the resource R1” .

At block 630, the first device 110 transmits the second transmission on the fifth resource. As such, the SCI indicating reservation of the periodic resources R2 to Rn is also transmitted on the fifth resource. Accordingly, other UEs may be informed of the resource reservation by decoding SCI.

At block 640, the first device 110 transmits the third transmission on at least one of the group of sixth resources.

In some embodiments where CCA is failed for the resource R1 in the current period, the first device 110 may perform resource reselection of the resource R1” to substitute the resource R1. In this case, there is no time or frequency restriction on resource selection. Thus, reevaluation may be introduced to avoid the resource collision. In particular, prior to transmitting the third transmission, the first device 110 may perform reevaluation on one of the group of sixth resources. As shown in FIG. 7, the first device 110 may perform reevaluation at T4 slots before slot n corresponding to the earliest resource in the group, i.e., the resource R2.

In other words, in a case where the UE fails to access the channel (e.g., based on CCA) at the immediate last periodic resource R1, or whose periodic reservation SCI in immediate last period resource R1 is not transmitted due to failing to access the channel at the resource R1, at least one resource of the selected sidelink grant for a MAC PDU to transmit from multiplexing and assembly entity may be reevaluated by physical layer at T4 before the slot n where the SCI indicating the at least one resource is signalled at first time.

In some other embodiments, the first device 110 may select the fifth resource from a plurality of candidate resources, and the fourth resource and the fifth resource comprise same frequency domain resources.

In some example embodiments, a time offset between the fourth resource and the fifth resource in time domain may be below a predetermined offset threshold. As shown in FIG. 7, the time offset T_offset between the fourth resource R1 and the fifth resource R1” should be below the predetermined offset threshold. In this case, less UEs will be impact by moving the transmission of SCI for resource reservation from the fourth resource R1 to the fifth resource R1” .

The first device 110 may further transmit SCI indicating the group of sixth resources R2 to Rn on the fifth resource R1” . Additionally, in some embodiments, the interval between the substitute resource R1” and subsequent pre-selected resource R2 may be preferred to be one of the allowed reservation periods configured for the resource pool. In this case, the SCI may comprise a “reservation period field” that indicates a first interval between the fifth resource R1” and the group of sixth resources (e.g., the earliest resource in the group, i.e., the resource R2) in time domain, and a value of the reservation period field is set to one of valid values configured for the resource pool. In some cases, if no resource satisfies the above conditions, the first device 110 may drops the group of sixth resources R2 to Rn. The first device 110 may further reselect a group of periodic resources.

Additionally, or alternatively, in some embodiments, there may be no time interval restrictions on the fifth resource R1” and the group of sixth resources R2 to Rn. The SCI may comprise a field indicative of a first interval between the fifth resource R1” and the group of sixth resources R2 to Rn in time domain, and a value of a reservation period field of the SCI is set to an invalid value. In this case, an additional field in SCI is used for explicitly indicating the differences of RB set or frequency resources between the current resource R1” and the next periodic resource R2. Accordingly, from the perspective of the second device 120, it is able to derive the reserved resource via the additional field, and ignore the "reservation period" field if it is set to the invalid value.

In the above embodiments, a time interval between the fifth resource R1” and the group of sixth resources R2 to Rn in time domain may be the first interval. In this case, prior to transmitting the third transmission, in accordance with a determination that the CCA for the fourth resource is failed, and the fourth resource is one of the last one or more recent resources relative to the group of sixth resources, the first device 110 may determine whether at least one of the group of sixth resources is available for sidelink transmission by performing at least one of reevaluation or pre-empt on the at least one sixth resource.

It would be appreciated that the examples, configurations and structures in FIG. 4 and FIG. 7 are given for the purpose of illustration. There will be many variants to sidelink resource allocation, selection and reservation schemes in practice. Therefore, the scope of the present disclosure is not limited in this regard.

FIG. 8 is a simplified block diagram of a device 800 that is suitable for implementing embodiments of the present disclosure. The device 800 can be considered as a further example implementation of the first device 110 or the second device 120 as shown in FIG. 1. Accordingly, the device 800 can be implemented at or as at least a part of the first device 110 or the second device 120.

As shown, the device 800 includes a processor 810, a memory 820 coupled to the processor 810, a suitable transmitter (TX) /receiver (RX) 840 coupled to the processor 810, and a communication interface coupled to the TX/RX 840. The memory 810 stores at least a part of a program 830. The TX/RX 840 is for bidirectional communications. The TX/RX 840 has at least one antenna to facilitate communication, though in practice an Access Node mentioned in this application may have several ones. The communication interface may represent any interface that is necessary for communication with other network elements, such as X2/Xn interface for bidirectional communications between eNBs/gNBs, S1/NG interface for communication between a Mobility Management Entity (MME) /Access and Mobility Management Function (AMF) /SGW/UPF and the eNB/gNB, Un interface for communication between the eNB/gNB and a relay node (RN) , or Uu interface for communication between the eNB/gNB and a terminal device.

The program 830 is assumed to include program instructions that, when executed by the associated processor 810, enable the device 800 to operate in accordance with the embodiments of the present disclosure, as discussed herein with reference to FIGs. 1 to 7. The embodiments herein may be implemented by computer software executable by the processor 810 of the device 800, or by hardware, or by a combination of software and hardware. The processor 810 may be configured to implement various embodiments of the present disclosure. Furthermore, a combination of the processor 810 and memory 820 may form processing means 850 adapted to implement various embodiments of the present disclosure.

The memory 820 may be of any type suitable to the local technical network and may be implemented using any suitable data storage technology, such as a non-transitory computer readable storage medium, semiconductor based memory devices, magnetic memory devices and systems, optical memory devices and systems, fixed memory and removable memory, as non-limiting examples. While only one memory 820 is shown in the device 800, there may be several physically distinct memory modules in the device 800. The processor 1010 may be of any type suitable to the local technical network, and may include one or more of general purpose computers, special purpose computers, microprocessors, digital signal processors (DSPs) and processors based on multicore processor architecture, as non-limiting examples. The device 800 may have multiple processors, such as an application specific integrated circuit chip that is slaved in time to a clock which synchronizes the main processor.

In some embodiments, a second device (e.g., a terminal device) comprises a circuitry configured to: determine a group of first resources unavailable for sidelink transmission based on sidelink control indication (SCI) from a first device, the SCI indicating resource reservation of the group of first resources in a resource pool for sidelink communication; select, from the resource pool, a group of second resources for a first transmission based on a sensing result and the SCI; prior to transmitting the first transmission, determining whether at least one of the group of first resources is available for sidelink transmission; in accordance with a determination that the at least one first resource is available, reselect a group of third resources comprising the at least one first resource; and transmit the first transmission on the group of third resources.

In some embodiments, one of the at least one first resource comprises a first time resource. In these embodiments, the circuitry is configured to determine whether the at least one first resource is available by: determining, at a second time resource before the first time resource, whether the at least one first resource is available for sidelink transmission, a time offset between the first time resource and the second time resource being a predetermined value.

In some embodiments, the circuitry is configured to determine determine whether the at least one first resource is available by: if a request for re-checking whether the at least one first resource is available for sidelink transmission is provided from a higher layer to a physical layer of the second device, re-checking an availability of the at least one first resource for sidelink transmission based on a sensing procedure at the physical layer.

In some embodiments, the circuitry is configured to re-check the availability of the at least one first resource by: determining whether a set of available resources determined based on the sensing result comprises the at least one first resource; and in accordance with a determination that the set of available resources comprises the at least one first resource, determining the at least one first resource available for sidelink transmission, wherein a re-checking result indicating the availability of the at least one first resource is provided from the physical layer to the higher layer.

In some embodiments, the circuitry is configured to determine the group of third resources by: in accordance with a determination that the at least one first resource is available for sidelink transmission, adjusting a first sidelink grant for the group of second resources to a second sidelink grant for the group of third resources at the higher layer.

In some embodiments, the circuitry is configured to re-check the availability of the at least one first resource by: determining whether SCI is detected on the at least one first resource; and in accordance with a determination that no SCI is detected on the at least one first resource, determining the at least one first resource available for sidelink transmission.

In some embodiments, the circuitry is configured to re-check the availability of the at least one first resource by: in accordance with a determination that SCI is detected on the at least one first resource, measuring a signal strength on the at least one first resource; and in accordance with a determination that the signal strength is below a predetermined threshold, determining the at least one first resource available for sidelink transmission.

In some embodiments, a first device (e.g., a terminal device) comprises a circuitry configured to: in accordance with a determination that a clear channel assessment (CCA) for a fourth resource is failed, select, from a resource pool for sidelink communication, a fifth resource for a second transmission, the fourth resource being reserved for transmitting the second transmission and intended for indicating a reservation of a group of sixth resources for at least a third transmission; transmit the second transmission on the fifth resource; and transmit the third transmission on at least one of the group of sixth resources.

In some embodiments, the circuitry is configured to transmit the third transmission on at least one of the group of sixth resources by: prior to transmitting the third transmission, performing reevaluation on one of the group of sixth resources; and in accordance with a determination that the sixth resource is available for sidelink transmission based on a reevaluation result, transmitting the third transmission on the sixth resource.

In some embodiments, the circuitry is configured to select the fifth resource for the second transmission by: selecting the fifth resource from a plurality of candidate resources, the fourth resource and the fifth resource comprising same frequency domain resources.

In some embodiments, a time offset between the fourth resource and the fifth resource in time domain is below a predetermined offset threshold.

In some embodiments, the circuitry is further configured to: transmit sidelink control information (SCI) indicating the group of sixth resources on the fifth resource.

In some embodiments, the SCI comprises a reservation period field indicating a first interval between the fifth resource and the group of sixth resources in time domain, and a value of the reservation period field is set to one of valid values configured for the resource pool.

In some embodiments, the SCI comprises a field indicative of a first interval between the fifth resource and the group of sixth resources in time domain, and a value of a reservation period field of the SCI is set to an invalid value.

In some embodiments, a time interval between the fifth resource and the group of sixth resources in time domain is the first interval. In these embodiments, the circuitry is configured to transmit the third transmission on at least one of the group of sixth resources by: prior to transmitting the third transmission, in accordance with a determination that the CCA for the fourth resource is failed, the fourth resource being one of the last one or more recent resources relative to the group of sixth resources, determining whether at least one of the group of sixth resources is available for sidelink transmission by performing at least one of reevaluation or pre-empt on the at least one sixth resource.

The term “circuitry” used herein may refer to hardware circuits and/or combinations of hardware circuits and software. For example, the circuitry may be a combination of analog and/or digital hardware circuits with software/firmware. As a further example, the circuitry may be any portions of hardware processors with software including digital signal processor (s) , software, and memory (ies) that work together to cause an apparatus, such as a terminal device or a network device, to perform various functions. In a still further example, the circuitry may be hardware circuits and or processors, such as a microprocessor or a portion of a microprocessor, that requires software/firmware for operation, but the software may not be present when it is not needed for operation. As used herein, the term circuitry also covers an implementation of merely a hardware circuit or processor (s) or a portion of a hardware circuit or processor (s) and its (or their) accompanying software and/or firmware.

In summary, embodiments of the present disclosure provide the following solutions.

In one solution, a communication method: determining, at a second device, a group of first resources unavailable for sidelink transmission based on sidelink control indication (SCI) from a first device, the SCI indicating resource reservation of the group of first resources in a resource pool for sidelink communication; selecting, from the resource pool, a group of second resources for a first transmission based on a sensing result and the SCI; prior to transmitting the first transmission, determining whether at least one of the group of first resources is available for sidelink transmission; in accordance with a determination that the at least one first resource is available, reselecting a group of third resources comprising the at least one first resource; and transmitting the first transmission on the group of third resources.

In some embodiments, one of the at least one first resource comprises a first time resource, and determining whether the at least one first resource is available comprises: determining, at a second time resource before the first time resource, whether the at least one first resource is available for sidelink transmission, a time offset between the first time resource and the second time resource being a predetermined value.

In some embodiments, determining whether the at least one first resource is available comprises: if a request for re-checking whether the at least one first resource is available for sidelink transmission is provided from a higher layer to a physical layer of the second device, re-checking an availability of the at least one first resource for sidelink transmission based on a sensing procedure at the physical layer.

In some embodiments, re-checking the availability of the at least one first resource comprises: determining whether a set of available resources determined based on the sensing result comprises the at least one first resource; and in accordance with a determination that the set of available resources comprises the at least one first resource, determining the at least one first resource available for sidelink transmission, wherein a re-checking result indicating the availability of the at least one first resource is provided from the physical layer to the higher layer.

In some embodiments, determining the group of third resources comprises: in accordance with a determination that the at least one first resource is available for sidelink transmission, adjusting a first sidelink grant for the group of second resources to a second sidelink grant for the group of third resources at the higher layer.

In some embodiments, re-checking the availability of the at least one first resource comprises: determining whether SCI is detected on the at least one first resource; and in accordance with a determination that no SCI is detected on the at least one first resource, determining the at least one first resource available for sidelink transmission.

In some embodiments, re-checking the availability of the at least one first resource further comprises: in accordance with a determination that SCI is detected on the at least one first resource, measuring a signal strength on the at least one first resource; and in accordance with a determination that the signal strength is below a predetermined threshold, determining the at least one first resource available for sidelink transmission.

In another solution, a communication method comprising: in accordance with a determination that a clear channel assessment (CCA) for a fourth resource is failed, selecting, at a first device and from a resource pool for sidelink communication, a fifth resource for a second transmission, the fourth resource being reserved for transmitting the second transmission and intended for indicating a reservation of a group of sixth resources for at least a third transmission; transmitting the second transmission on the fifth resource; and transmitting the third transmission on at least one of the group of sixth resources.

In some embodiments, transmitting the third transmission on at least one of the group of sixth resources comprises: prior to transmitting the third transmission, performing reevaluation on one of the group of sixth resources; and in accordance with a determination that the sixth resource is available for sidelink transmission based on a reevaluation result, transmitting the third transmission on the sixth resource.

In some embodiments, selecting the fifth resource for the second transmission comprises: selecting the fifth resource from a plurality of candidate resources, the fourth resource and the fifth resource comprising same frequency domain resources.

In some embodiments, the method further comprises: transmitting sidelink control information (SCI) indicating the group of sixth resources on the fifth resource.

In some embodiments, a time interval between the fifth resource and the group of sixth resources in time domain is the first interval, and transmitting the third transmission on at least one of the group of sixth resources further comprises: prior to transmitting the third transmission, in accordance with a determination that the CCA for the fourth resource is failed, the fourth resource being one of the last one or more recent resources relative to the group of sixth resources, determining whether at least one of the group of sixth resources is available for sidelink transmission by performing at least one of reevaluation or pre-empt on the at least one sixth resource.

In still another solution, a communication device comprises: at least one processor; and at least one memory storing instructions that, when executed by the at least one processor, cause the device to perform any of the methods above.

In yet another solution, a computer readable medium having instructions stored thereon, the instructions, when executed on at least one processor, causing the at least one processor to perform any of the methods above.

In a yet further solution, a computer program comprising instructions, the instructions, when executed on at least one processor, causing the at least one processor to perform any of the methods above.

Generally, various embodiments of the present disclosure may be implemented in hardware or special purpose circuits, software, logic or any combination thereof. Some aspects may be implemented in hardware, while other aspects may be implemented in firmware or software which may be executed by a controller, microprocessor or other computing device. While various aspects of embodiments of the present disclosure are illustrated and described as block diagrams, flowcharts, or using some other pictorial representation, it will be appreciated that the blocks, apparatus, systems, techniques or methods described herein may be implemented in, as non-limiting examples, hardware, software, firmware, special purpose circuits or logic, general purpose hardware or controller or other computing devices, or some combination thereof.

The present disclosure also provides at least one computer program product tangibly stored on a non-transitory computer readable storage medium. The computer program product includes computer-executable instructions, such as those included in program modules, being executed in a device on a target real or virtual processor, to carry out the process or method as described above with reference to FIGS. 1 to 7. Generally, program modules include routines, programs, libraries, objects, classes, components, data structures, or the like that perform particular tasks or implement particular abstract data types. The functionality of the program modules may be combined or split between program modules as desired in various embodiments. Machine-executable instructions for program modules may be executed within a local or distributed device. In a distributed device, program modules may be located in both local and remote storage media.

Program code for carrying out methods of the present disclosure may be written in any combination of one or more programming languages. These program codes may be provided to a processor or controller of a general purpose computer, special purpose computer, or other programmable data processing apparatus, such that the program codes, when executed by the processor or controller, cause the functions/operations specified in the flowcharts and/or block diagrams to be implemented. The program code may execute entirely on a machine, partly on the machine, as a stand-alone software package, partly on the machine and partly on a remote machine or entirely on the remote machine or server.

The above program code may be embodied on a machine readable medium, which may be any tangible medium that may contain, or store a program for use by or in connection with an instruction execution system, apparatus, or device. The machine readable medium may be a machine readable signal medium or a machine readable storage medium. A machine readable medium may include but not limited to an electronic, magnetic, optical, electromagnetic, infrared, or semiconductor system, apparatus, or device, or any suitable combination of the foregoing. More specific examples of the machine readable storage medium would include an electrical connection having one or more wires, a portable computer diskette, a hard disk, a random access memory (RAM) , a read-only memory (ROM) , an erasable programmable read-only memory (EPROM or Flash memory) , an optical fiber, a portable compact disc read-only memory (CD-ROM) , an optical storage device, a magnetic storage device, or any suitable combination of the foregoing.

Further, while operations are depicted in a particular order, this should not be understood as requiring that such operations be performed in the particular order shown or in sequential order, or that all illustrated operations be performed, to achieve desirable results. In certain circumstances, multitasking and parallel processing may be advantageous. Likewise, while several specific implementation details are contained in the above discussions, these should not be construed as limitations on the scope of the present disclosure, but rather as descriptions of features that may be specific to particular embodiments. Certain features that are described in the context of separate embodiments may also be implemented in combination in a single embodiment. Conversely, various features that are described in the context of a single embodiment may also be implemented in multiple embodiments separately or in any suitable sub-combination.

Although the present disclosure has been described in language specific to structural features and/or methodological acts, it is to be understood that the present disclosure defined in the appended claims is not necessarily limited to the specific features or acts described above. Rather, the specific features and acts described above are disclosed as example forms of implementing the claims.

Claims

A communication method comprising:

determining, at a second device, a group of first resources unavailable for sidelink transmission based on sidelink control indication (SCI) from a first device, the SCI indicating resource reservation of the group of first resources in a resource pool for sidelink communication;

selecting, from the resource pool, a group of second resources for a first transmission based on a sensing result and the SCI;

prior to transmitting the first transmission, determining whether at least one of the group of first resources is available for sidelink transmission;

in accordance with a determination that the at least one first resource is available, reselecting a group of third resources comprising the at least one first resource; and

transmitting the first transmission on the group of third resources.
The communication method of claim 1, wherein one of the at least one first resource comprises a first time resource, and

wherein determining whether the at least one first resource is available comprises:

determining, at a second time resource before the first time resource, whether the at least one first resource is available for sidelink transmission, a time offset between the first time resource and the second time resource being a predetermined value.
The communication method of claim 2, wherein determining whether the at least one first resource is available comprises:

if a request for re-checking whether the at least one first resource is available for sidelink transmission is provided from a higher layer to a physical layer of the second device, re-checking an availability of the at least one first resource for sidelink transmission based on a sensing procedure at the physical layer.
The communication method of claim 3, wherein re-checking the availability of the at least one first resource comprises:

determining whether a set of available resources determined based on the sensing result comprises the at least one first resource; and

in accordance with a determination that the set of available resources comprises the at least one first resource, determining the at least one first resource available for sidelink transmission, wherein a re-checking result indicating the availability of the at least one first resource is provided from the physical layer to the higher layer.
The communication method of claim 4, wherein determining the group of third resources comprises:

in accordance with a determination that the at least one first resource is available for sidelink transmission, adjusting a first sidelink grant for the group of second resources to a second sidelink grant for the group of third resources at the higher layer.
The communication method of claim 3, wherein re-checking the availability of the at least one first resource comprises:

determining whether SCI is detected on the at least one first resource; and

in accordance with a determination that no SCI is detected on the at least one first resource, determining the at least one first resource available for sidelink transmission.
The communication method of claim 6, wherein re-checking the availability of the at least one first resource further comprises:

in accordance with a determination that SCI is detected on the at least one first resource, measuring a signal strength on the at least one first resource; and

in accordance with a determination that the signal strength is below a predetermined threshold, determining the at least one first resource available for sidelink transmission.
A communication method comprising:

in accordance with a determination that a clear channel assessment (CCA) for a fourth resource is failed, selecting, at a first device and from a resource pool for sidelink communication, a fifth resource for a second transmission, the fourth resource being reserved for transmitting the second transmission and intended for indicating a reservation of a group of sixth resources for at least a third transmission;

transmitting the second transmission on the fifth resource; and

transmitting the third transmission on at least one of the group of sixth resources.
The communication method of claim 8, wherein transmitting the third transmission on at least one of the group of sixth resources comprises:

prior to transmitting the third transmission, performing reevaluation on one of the group of sixth resources; and

in accordance with a determination that the sixth resource is available for sidelink transmission based on a reevaluation result, transmitting the third transmission on the sixth resource.
The communication method of claim 8, wherein selecting the fifth resource for the second transmission comprises:

selecting the fifth resource from a plurality of candidate resources, the fourth resource and the fifth resource comprising same frequency domain resources.
The communication method of claim 10, wherein a time offset between the fourth resource and the fifth resource in time domain is below a predetermined offset threshold.
The communication method of claim 8, further comprising:

transmitting sidelink control information (SCI) indicating the group of sixth resources on the fifth resource.
The communication method of claim 12, wherein the SCI comprises a reservation period field indicating a first interval between the fifth resource and the group of sixth resources in time domain, and a value of the reservation period field is set to one of valid values configured for the resource pool.
The communication method of claim 13, wherein the SCI comprises a field indicative of a first interval between the fifth resource and the group of sixth resources in time domain, and a value of a reservation period field of the SCI is set to an invalid value.
The communication method of claim 13 or 14, wherein a time interval between the fifth resource and the group of sixth resources in time domain is the first interval, and transmitting the third transmission on at least one of the group of sixth resources further comprises:

prior to transmitting the third transmission, in accordance with a determination that the CCA for the fourth resource is failed, the fourth resource being one of the last one or more recent resources relative to the group of sixth resources, determining whether at least one of the group of sixth resources is available for sidelink transmission by performing at least one of reevaluation or pre-empt on the at least one sixth resource.
A communication device comprising:

at least one processor configured to cause the device to perform the method according to any of claims 1 to 7.
A communication device comprising:

at least one processor configured to cause the device to perform the method according to any of claims 8 to 15.
A computer readable medium having instructions stored thereon, the instructions, when executed on at least one processor, causing the at least one processor to perform the method according to any of claims 1 to 7.
A computer readable medium having instructions stored thereon, the instructions, when executed on at least one processor, causing the at least one processor to perform the method according to any of claims 8 to 15.