WO2024060100A1

WO2024060100A1 - Method, device and computer readable medium for communications

Info

Publication number: WO2024060100A1
Application number: PCT/CN2022/120362
Authority: WO
Inventors: Jin Yang; Zhaobang MIAO; Gang Wang
Original assignee: Nec Corporation
Priority date: 2022-09-21
Filing date: 2022-09-21
Publication date: 2024-03-28

Abstract

Embodiments of the present disclosure relate to method, device and computer readable media for sidelink communications. The method comprises receiving, at a first terminal device, scheduling information for sidelink transmission on a first type of resources. The resources are on unlicensed spectrum. The scheduling information indicates an intended sidelink channel occupancy (CO) which can be used at least by the first terminal device. The method also comprises transmitting a sidelink signal according to the scheduling information.

Description

METHOD, DEVICE AND COMPUTER READABLE MEDIUM FOR COMMUNICATIONS

TECHNICAL FIELD

Embodiments of the present disclosure generally relate to the field of telecommunication, and in particular, to a method, device and computer readable media for sidelink communications.

BACKGROUND

Sidelink on unlicensed spectrum or band (SL-U) is to be studied in the 3rd Generation Partnership Project (3GPP) . The scheme of SL-U should base on New Radio (NR) sidelink and NR on unlicensed spectrum (NR-U) . Both Mode 1 and Mode 2 resource schemes are supported for SL-U. Channel occupancy time (COT) sharing in Mode 1 may improve resource efficiency.

SUMMARY

In general, example embodiments of the present disclosure provide methods, devices and computer readable media for sidelink communications.

In a first aspect, there is provided a method for sidelink communications. The method comprises: receiving, at a first terminal device, scheduling information for sidelink transmission on a first type of resources, wherein the scheduling information indicates an intended sidelink channel occupancy (CO) which can be used at least by the first terminal device, the first type of resources are comprised on unlicensed spectrum; and transmitting a sidelink signal according to the scheduling information.

In a second aspect, there is provided a method for sidelink communications. The method comprises: determining, at a network device, scheduling information for sidelink transmission on a first type of resources, wherein the scheduling information indicates an intended sidelink CO which can be used at least by a first terminal device, the first type of resources are comprised on unlicensed spectrum; and transmitting the scheduling information.

In a third aspect, there is provided a terminal device. The terminal device comprises a processor and a memory storing instructions. The memory and the instructions are configured, with the processor, to cause the terminal device to perform the method according to the first aspect.

In a fourth aspect, there is provided a network device. The network device comprises a processor and a memory storing instructions. The memory and the instructions are configured, with the processor, to cause the network 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 of a device, cause the device to perform 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 of a device, cause the device to perform the method according to the second aspect.

It is to be understood that the summary section is not intended to identify key or essential features of embodiments of the present disclosure, nor is it intended to be used to limit the scope of the present disclosure. 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 network in which implementations of the present disclosure can be implemented;

Fig. 2 illustrates an example of automatic gain control (AGC) symbol and guard period (GP) symbol in accordance with some embodiments of the present disclosure;

Fig. 3 illustrates an example of sidelink channels in accordance with some embodiments of the present disclosure;

Fig. 4 illustrates an example of IRBs in an NR-U IRB scheme in accordance with some embodiments of the present disclosure;

Fig. 5 illustrates an example of CO sharing in accordance with some embodiments of the present disclosure;

Fig. 6 illustrates a flowchart of an example method in accordance with some embodiments of the present disclosure;

Fig. 7 illustrates a flowchart of an example method in accordance with some other embodiments of the present disclosure;

Fig. 8 illustrates a signaling chart illustrating a process for SL-U scheduling with first DCI and second DCI in accordance with some implementations of the present disclosure;

Fig. 9 illustrates an example of COT sharing with the first DCI and second DCI in accordance with some embodiments of the present disclosure;

Fig. 10 illustrates a signaling chart illustrating a process for SL-U scheduling with third DCI in accordance with some implementations of the present disclosure;

Fig. 11 illustrates an example of COT sharing with the third DCI in accordance with some embodiments of the present disclosure;

Figs. 12A and 12B illustrate an example of CA type switching in accordance with some embodiments of the present disclosure, respectively;

Figs. 13A, 13B and 13C illustrate an example of SCI transmission in accordance with some embodiments of the present disclosure, respectively; and

Fig. 14 is a simplified block diagram of a device that is suitable for implementing 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 example 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, user equipment (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, device on vehicle for V2X communication where X means pedestrian, vehicle, or infrastructure/network, devices for Integrated Access and Backhaul (IAB) , Small Data Transmission (SDT) , mobility, Multicast and Broadcast Services (MBS) , positioning, dynamic/flexible duplex in commercial networks, reduced capability (RedCap) , 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) , Network-controlled Repeaters, 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 –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 network device may have the function of network energy saving, Self-Organising Networks (SON) /Minimization of Drive Tests (MDT) . The terminal may have the function of power saving.

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

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.

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 ‘some embodiments’ and ‘an embodiment’ are to be read as ‘at least some embodiments. ’ 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.

Fig. 1 illustrates a schematic diagram of an example communication network 100 in which embodiments of the present disclosure can be implemented. As shown in Fig. 1, the communication network 100 may include a first terminal device 110, a second terminal device 120, a third terminal device 130,

network devices

140 and 150. The

network devices

140 and 150 may communicate with the first terminal device 110, the second terminal device 120 and the third terminal device 130 via respective wireless communication channels.

In some embodiments, the network device 140 may be a gNB in NR, and the network device 150 may be an eNB in Long Term Evolution (LTE) system.

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

The communications in the communication network 100 may conform to any suitable standards including, but not limited to, Global System for Mobile Communications (GSM) , LTE, LTE-Evolution, LTE-Advanced (LTE-A) , Wideband Code Division Multiple Access (WCDMA) , Code Division Multiple Access (CDMA) , GSM EDGE Radio Access Network (GERAN) , Machine Type Communication (MTC) and the like. Furthermore, the communications 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.

In some embodiments, the communications in the communication network 100 may comprise sidelink communication. Sidelink communication is a wireless radio communication directly between two or more terminal devices, such as two or more terminal devices among the terminal device 110, the terminal device 120 and the terminal device 130. In this type of communication, the two or more terminal devices that are geographically proximate to each other can directly communicate without going through the

network device

140 or 150 or through a core network. Data transmission in sidelink communication is thus different from typical cellular network communications, in which a terminal device transmits data to the network device 140 or 150 (i.e., uplink transmissions) or receives data from the network device 140 or 150 (i.e., downlink transmissions) . In sidelink communication, data is transmitted directly from a source terminal device (such as the terminal device 110) to a target terminal device (such as the terminal device 120) through the Unified Air Interface, e.g., PC5 interface, (i.e., sidelink transmissions) , as shown in Fig. 1.

Sidelink communication can provide several advantages, including reducing data transmission load on a core network, system resource consumption, transmission power consumption, and network operation costs, saving wireless spectrum resources, and increasing spectrum efficiency of a cellular wireless communication system.

In a sidelink communication system, the sidelink resource is used to transmit information between terminal devices. According to application scenarios, service types, etc., a sidelink communication manner includes but is not limited to device to device (D2D) communication, Vehicle-to-Everything (V2X) communication, etc.

V2X communication enables vehicles to communicate with other vehicles (i.e. Vehicle-to-Vehicle (V2V) communication) , with infrastructure (i.e. Vehicle-to-Infrastructure (V2I) , with wireless networks (i.e. Vehicle-to-Network (V2N) communication) , with pedestrians (i.e. Vehicle-to-Pedestrian (V2P) communication) , and even with the owner's home (i.e. Vehicle-to-Home (V2H) ) . Examples of infrastructure include roadside units such as traffic lights, toll gates and the like. V2X communication can be used in a wide range of scenarios, including in accident prevention and safety, convenience, traffic efficiency and clean driving, and ultimately in relation to autonomous or self-driving vehicles.

For sidelink communications, a terminal device uses resources in sidelink resource pools to transmit or receive signals. The sidelink resource pools include resources in time domain and frequency domain, which are dedicated resources of the sidelink communication, or shared by the sidelink communication and a cellular link.

In a sidelink resource pool which may contain multiple slots and resource blocks (RBs) , and all or part of the symbols in a slot can be used for sidelink transmission. Within a resource pool, among all the symbols configured for sidelink in each slot, the first symbol (i.e., the start symbol) is used as the automatic gain control (AGC) symbol, and the last symbol used as a guard period (GP) symbol. AGC symbols and GP symbols can be considered as fixed overheads in sidelink resource. In the description of the following embodiments, AGC symbols and GP symbols are included in the sidelink symbols which are indicated by the sidelink channel resource configuration, and AGC symbols carry redundancy sidelink information while GP symbols are not used for carrying sidelink information, as shown in Fig. 2.

The terminal device 110, the terminal device 120 and the terminal device 130 may use sidelink channels to transmit sidelink signaling or information. The sidelink channels include at least one of the following: a Physical Sidelink Control Channel (PSCCH) resource which is used for carrying sidelink control information (SCI) , a PSSCH resource which is used for carrying sidelink data service information, a physical sidelink feedback channel (PSFCH) resource which is used for carrying sidelink ACK/NACK feedback information, a physical sidelink broadcast channel (PSBCH) resource which is used for carrying sidelink broadcast information, and a physical sidelink discovery channel (PSDCH) resource which is used for carrying a sidelink discovery signal.

Fig. 3 illustrates an example of sidelink channels in accordance with some embodiments of the present disclosure. As shown in Fig. 3, a resource pool may be configured within a SL Bandwidth Part (BWP) . A resource pool configuration may comprise sl-StartRB-Subchannel and sl-RB-Number. The sl-StartRB-Subchannel may indicate the lowest RB of the resource pool. The lowest RB is also referred to as a start RB. The sl-RB-Number may indicate the total number of RBs of the resource pool.

RBs in the resource pool may be divided into consecutive sub-channels. Sub-channel is a frequency resource unit of PSSCH. PSSCH may carry SCI format 2A, SCI format 2B, SCI format 2C and sidelink data. Each sub-channel contains consecutive RBs. A terminal device may use one or more consecutive sub-channels as a PSSCH resource to transmit sidelink data. A sub-channel configuration of the resource pool may comprise sl-SubchannelSize which indicates the number of RBs contained in one sub-channel. The SubchannelSize may be equal to 10, 12, 15, 20, 25, 50, 75 or 100.

A PSCCH resource may be defined within each sub-channel. Each PSCCH resource may include t consecutive symbols in time domain and k consecutive RBs in frequency domain. The t symbols may start from the first symbol in the available symbols in the time domain. For example, t may be equal to 2 or 3. The k RBs may start from the lowest RB in the corresponding sub-channel. For example, k may be equal to 10, 12, 15, 20, or 25.

As mentioned above, IRB is used as a frequency resource unit for NR-U uplink. Fig. 4 illustrates an example of an RB set and IRB in an NR-U IRB scheme in accordance with some embodiments of the present disclosure. As shown in Fig. 4, each of the RB sets may be defined as 20MHz. For Subcarrier Spacing (SCS) of 15kHz, each of the RB sets may comprises 100 to 110 RBs. For SCS of 30kHz, each of the RB sets may comprises 50 to 55 RBs. There may be a guard band between two adjacent RB sets.

BWPs #1 and #2 are defined within a system carrier. The BWP #1 comprises RB sets #0 and #1. The BWP #2 comprises RB sets #2 and #3. It will be understood that although it is shown in Fig. 4 that each of BWPs comprises a plurality of RB sets, in some embodiments, one or more of the BWPs may comprise a single RB set.

In the present disclosure, terms “IRB” and “interlace” may be used interchangeably. IRBs or interlaces are defined within a system carrier. An IRB with an index 0 starts from a Common Resource Block (CRB) with an index 0 (i.e., CRB#0) . For SCS of 30kHz, 5 interlaces may be defined within the system carrier, as shown in Fig. 4. For SCS of 15kHz, 10 interlaces may be defined within the system carrier.

In NR-U schemes, one of the

terminal devices

110 and 120 may access to a channel in unlicensed spectrum by using a channel access procedure, and obtain a Channel Occupancy (CO) . A Channel Occupancy Time (COT) refers to total time for a CO which may be shared between the

terminal devices

110 and 120, as shown in Fig. 5.

In the example of Fig. 5, within a sidelink CO initiated by the terminal device 110, the terminal device 110 performs sidelink signal transmission starting from the beginning of the CO and the remaining resources after its transmission can be shared by the terminal device 120.

The

terminal devices

110 and 120 may perform the sidelink transmissions by using resources allocated by the

network device

140 or 150. This scheme for resource allocation is also referred to as mode 1 resource scheme. There may be a dedicated resource pool for mode 1 resource scheme. With mode 1 resource scheme, PSCCH resources and PSSCH resources may be allocated.

Mode 1 resource scheme supports dynamic scheduling and configured grant (also referred to as Semi-Persistent Scheduling (SPS) ) . There may be two types of configuration grant (CG) : type 1 CG and type 2 CG. Type 1 CG may be based on RRC configuration and type 2 CG may be activated by downlink control information (DCI) based on RRC configuration. The dynamic scheduling may be based on DCI. Mode 1 resource scheme also supports scheduling more than one resources for a transmission block (TB) for initial transmission and at least one retransmission. With mode 1 resource scheme, the

network device

140 or 150 does not receiving sidelink signals.

In mode 1 resource scheme, the

terminal device

110 and 120 transmits at least one of SCI and data on the scheduled PSCCH or PSSCH resources. There is RRC connection between the terminal device 110 and the

network device

140 or 150. There is RRC connection (i.e., Uu connection) between the terminal device 120 and the

network device

140 or 150. A dedicated Radio Network Temporary Identifier (RNTI) different from Uu RNTI may be used for sidelink scheduling DCI. The dedicated RNTI may be assigned by the network device 140 to sidelink terminal devices, such as the

terminal devices

110 and 120.

The

terminal devices

110 and 120 may forward sidelink Ack/Nack to the

network device

140 or 150 on PUCCH or PUSCH according to configuration.

With Mode 1 resource scheme, how to efficiently implement COT sharing among terminal devices needs to be studied.

Fig. 6 illustrates a flowchart of an example method 600 in accordance with some embodiments of the present disclosure. In some embodiments, the method 600 can be implemented at a network device, such as one of the

network devices

140 and 150 as shown in Fig. 1. For the purpose of discussion, the method 600 will be described with reference to Fig. 1 as performed by the network devices 140 without loss of generality.

At block 610, the network device 140 determines scheduling information for SL transmission on a first type of resources. The scheduling information indicates an intended SL CO which can be used at least by the first terminal device 110. The first type of resources comprises SL resources on unlicensed spectrum.

At block 620, the network device 140 transmits the scheduling information.

Fig. 7 illustrates a flowchart of an example method 700 in accordance with some embodiments of the present disclosure. In some embodiments, the method 700 can be implemented at a terminal device, such as one of the terminal device 110, the terminal device 120 and the terminal device 130 as shown in Fig. 1. For the purpose of discussion, the method 700 will be described with reference to Fig. 1 as performed by the terminal device 110 without loss of generality.

At block 710, the terminal device 110 receives scheduling information for SL transmission on a first type of resources. The scheduling information indicates an intended SL CO which can be used at least by the first terminal device 110. The first type of resources comprises SL resources on unlicensed spectrum.

At block 720, the terminal device 110 transmits an SL signal according to the scheduling information.

In some embodiments, the scheduling information may comprise first DCI for the intended SL CO. The first DCI may provide a common indication of a SL CO for all SL terminal devices. In this regard, the first DCI may be referred to as common DCI. The first DCI may reduce SL-U scheduling indication overhead.

In some embodiments, the scheduling information may further comprise second DCI for scheduling the first terminal device 110 within the intended SL CO. Because the second DCI provides a dedicated scheduling for a terminal device within an SL CO, the second DCI may be referred to as dedicated DCI. The second DCI may provide flexibility to assign one or more initial terminal devices for the intended SL CO.

Embodiments of first DCI and second DCI

Fig. 8 illustrates a signaling chart illustrating a process 800 for SL-U scheduling with the first DCI and second DCI in accordance with some implementations of the present disclosure. Fig. 9 illustrates an example of COT sharing with the first DCI and second DCI in accordance with some embodiments of the present disclosure.

For the purpose of discussion, the process 800 will be described with reference to Figs. 1 and 9. The process 800 may involve the network device 140, the first terminal device 110, the second terminal device 120 and the third terminal device 130 as illustrated in Fig. 1. Although the process 800 will be described in the communication network 100 of Fig. 1, this process may be likewise applied to other communication scenarios.

As shown in Fig. 8, the network device 140 transmits 810 the first DCI for the intended SL CO. For example, as shown in Fig. 9, the network device 140 transmits the first DCI on slot #t. The intended SL CO may be scheduled to start from slot #n with CO duration of 3 slots.

In some embodiments, the network device 140 may transmit the first DCI for the intended SL CO on Uu interface.

In some embodiments, the network device 140 may broadcast the first DCI and thus the first DCI may be identified as SL broadcast information. For example, the first DCI may be identified with a dedicated SL broadcast identity (ID) .

The network device 140 transmits 820, to the first terminal device 110, the second DCI for scheduling the first terminal device 110 within the intended SL CO. For example, as shown in Fig. 9, the network device 140 transmits the second DCI for scheduling the first terminal device 110 on slot #t.

In some embodiments, the second DCI may indicate one or more of the first terminal device 110 and the second terminal device 120 to initiate the intended SL CO using Type 1 channel access (CA) process. In this way, success ratio of initiating the intended SL CO by sidelink terminal devices may be increased. In this example, the second DCI indicates the first terminal device 110 to initiate the intended SL CO using Type 1 channel access (CA) process. Hereinafter, a terminal device which initiates the intended SL CO may be referred to as an initial terminal device, and a terminal device which shares resources within the intended SL CO may be referred to as a responding terminal device.

The network device 140 transmits 830, to the second terminal device 120, the second DCI for scheduling the second terminal device 120 within the intended SL CO. For example, as shown in Fig. 9, the network device 140 transmits the second DCI for scheduling the second terminal device 120 on slot #t. Alternatively, the network device 140 may transmit the second DCI for scheduling the second terminal device 120 on slot #t+1. The second DCI may indicate the second terminal device 120 to perform Type 2CA procedure, e.g., Type 2A, Type 2B or Type 2C, to share the resources within the SL CO.

On the side of the first terminal device 110, the first terminal device 110 receives the first DCI and obtains 840 information of the intended SL CO from the first DCI. In addition, the first terminal device 110 receives the second DCI for scheduling the first terminal device 110 and obtains information from the second DCI.

In turn, the first terminal device 110 performs 850 Type 1 CA procedure to initiate the SL CO before slot #n.

If the Type 1 CA procedure succeeds, the first terminal device 110 transmits 860 sidelink data on slot #n according to the second DCI received from the network device 140. For example, the first terminal device 110 may broadcast or groupcast the sidelink data so that the second terminal device 120 and the third terminal device 130 may receive the sidelink data.

In some embodiments, the first terminal device 110 may transmit, on slot #n, SCI indicating the intended SL CO.

On the side of the second terminal device 120, the second terminal device 120 receives the first DCI and obtains 870 information of the intended SL CO from the first DCI. In addition, the second terminal device 120 receives the second DCI for scheduling the second terminal device 120 and obtains information from the second DCI.

In turn, the second terminal device 120 performs 880 Type 2A CA procedure to share the resources within the SL CO on slot #n+1.

If the Type 2A CA procedure succeeds, the second terminal device 120 transmits 890 sidelink data on slot #n+1 according to the second DCI received from the network device 140. For example, the second terminal device 120 may broadcast or groupcast the sidelink data so that the first terminal device 110 and the third terminal device 130 may receive the sidelink data.

In embodiments where the first terminal device 110 transmits SCI indicating the intended SL CO, the second terminal device 120 detects the SCI from the first terminal device 110.

With the process 800, success ratio of initiating the intended SL CO by sidelink terminal devices may be increased and resource efficiency may be improved. In addition, sidelink transmissions among terminal devices may be aligned.

In some embodiments, the first DCI may indicate at least one of the following:

● a start slot of the intended SL CO,

● a duration of the intended SL CO,

● at least one resource block (RB) set for the intended SL CO,

● a type of a channel access (CA) procedure to be used to initiate the intended sidelink CO,

● a first channel access priority class (CAPC) ,

● a type of SL terminal devices which are allowed to share the intended SL CO, or

● an ID of a SL terminal device which is assigned to initiate the intended SL CO.

In some embodiments, the start slot of the intended SL CO may be indicated by at least one of the following:

● an index of the start slot, or

● a first slot offset between a first slot and the start slot, wherein the first DCI is received on the first slot.

In some embodiments, according to sidelink resource configuration, the actual starting point of sidelink transmission may be the starting symbol within the starting slot. The starting symbol may be the first symbol of the slot, the first available symbol for sidelink transmission of the slot, or other symbols in the starting slot.

In some embodiments, the duration of the intended SL CO may be indicated by at least one of the following:

● the number of slots comprised in the intended SL CO;

● a second slot offset between a first slot and an end slot of the intended SL CO, wherein the first DCI is received on the first slot; or

● an index of the duration of the intended SL CO within a list of available SL CO durations, wherein the list is configured by a high layer signaling.

In some embodiments, the at least one RB set for the intended SL CO may be indicated by at least one of the following:

● a bitmap,

● an index of RB set, or

● a resource indicator value (RIV) .

In some embodiments, a length of the bitmap may be determined according to high layer configuration. In some embodiments, the length of the bitmap equals to the number of RB sets configured for sidelink communication.

In some embodiments, the RIV indicates an index of a start RB set and the number of consecutive RB sets assigned for the intended SL CO.

In some embodiments, the type of SL terminal devices which are allowed to share the intended SL CO may be indicated by at least one of the following:

● an ID of a SL communication group,

● an ID of a SL broadcast transmission, or

● an ID of at least one SL terminal device.

In embodiments where the type of SL terminal devices which are allowed to share the intended SL CO is indicated by the ID of the SL communication group, the intended SL CO can be used by the terminal devices belong to the group.

In embodiments where the type of SL terminal devices which are allowed to share the intended SL CO is indicated by the ID of the SL broadcast transmission, the intended SL CO can be used by the terminal devices for broadcast data with the ID.

In embodiments where the type of SL terminal devices which are allowed to share the intended SL CO is indicated by the ID of at least one SL terminal device, the indicated at least one SL terminal device can use the resources within intended SL CO.

In some embodiments, the first CAPC may indicate a CAPC to be used in a CA procedure to initiate the intended SL CO. In some embodiments, the first CAPC indicate a CAPC to be used in Type 1 CA procedure to initiate the intended SL CO.

In some embodiments, the type of the CA procedure to be used to initiate the intended sidelink CO may indicate Type 1 or Type 2 CA procedure. In some embodiments, Type 2 CA procedure may be Type 2A, Type 2B or Type 2C CA procedure.

In some embodiments, the first DCI may use a DCI format 3-2. Table 1 shows an example of contents of the DCI format 3-2.

Table 1

DCI contents	Indicator
Start slot of the intended SL CO	Slot offset = k
CO duration	m (slots)
CA type	Type	1
CAPC	3
RB set indicator	1100 (bitmap)
Allowed type	groupcast
Group ID	8 bits

Descriptions of fields in Table 1 are provided as below:

● start slot of the intended SL CO: the first DCI is received on slot #t and the start slot of the intended SL CO is slot #t+k;

● CO duration indicator: m slots, i.e., the intended SL CO comprises slot [#t+k, #t+k+m-1] ;

● CA type: Type 1 CA procedure to be used to initiate the intended SL CO;

● CAPC =3, one or more terminal devices may initiate the intended SL CO with CAPC of 3;

● RB set indicator: using bitmap to indicate frequency resource comprised in the intended SL CO, “1100” means there are 4 RB sets configured for sidelink, and the intended SL CO should use the first and second RB sets among the 4 RB;

● allowed type = groupcast: for the terminal device belongs to the indicated sidelink communication group, it can share the intended SL CO;

● group ID: when “allowed type = groupcast” , this filed represents the corresponding sidelink communication group ID.

In some embodiments, the first terminal device 110 may further receive configuration information which indicates a SL CO sharing list. The SL CO sharing list comprises at least one entry of SL CO sharing configuration.

In such embodiments, the first terminal device 110 may receive a high layer signaling from the network device 140. The high layer signaling comprises the configuration information which indicates the SL CO sharing list. For example, the configuration information which indicates the SL CO sharing list may be as below:

● SL-COT-Sharinglist: SEQUENCE (SIZE (1.. 1709) ) OF SL-COT-Sharing

● SL-COT-Sharing:

‐ noCOT-Sharing

‐ cot-Sharing:

◆ duration INTEGER (1.. 39) ,

◆ offset INTEGER (1.. 39) ,

◆ channelAccessPriority INTEGER (1.. 4) ,

◆ allowedType ENUMERATED {broadcast, groupcast}

where:

◆ “SL-COT-Sharinglist” represents the SL CO sharing list,

◆ “SL-COT-Sharing” represents an entry of the SL CO sharing configuration,

◆ “noCOT-Sharing” indicates that the intended SL CO is not allowed for sharing;

◆ “duration” indicates the number of slots of the intended SL CO;

◆ “offset” indicates the number of slots between the first slot where the first DCI is received and the start slot of the intended SL CO;

◆ “channelAccessPriority” indicates a CAPC to be used in a CA procedure to initiate the intended sidelink CO;

◆ “allowedType” indicates a type of sidelink terminal devices which are allowed to share the intended sidelink CO; the value of “broadcast” corresponds to sidelink broadcast, and the value of “groupcast” corresponds to sidelink groupcast.

In such embodiments, the scheduling information may comprise an index of an entry of the SL CO sharing configuration in the SL CO sharing list.

In such embodiments, the index of the entry of the SL CO sharing configuration may be indicated in the first DCI. For example, if the first DCI indicates the index of the entry of the SL CO sharing configuration is 0, the first terminal device 110 determine the intended SL CO configuration as the first SL-COT-Sharing configured in the SL-COT-Sharinglist.

In some embodiments, the second DCI for scheduling the first terminal device 110 within the intended SL CO may indicate at least one of the following:

● an SL resource assigned for transmission of the SL signal within the intended SL CO,

● an indication indicating whether the first terminal device 110 is assigned to initiate the intended SL CO,

● a type of a CA procedure to be used to initiate the intended sidelink CO,

● a type of a CA procedure to be used for the assigned SL resource within the intended SL CO,

● a first CAPC,

● a CAPC threshold,

● a first flag indicating whether SCI indicating the intended SL CO is to be transmitted, or

● a second flag indicating whether a feedback is to be transmitted to indicate that the intended SL CO is successfully obtained.

In some embodiments, the first CAPC may indicate a CAPC to be used in a CA procedure to initiate the intended SL CO.

In some embodiments, the CAPC threshold may indicate a CAPC threshold for sharing the intended SL CO.

In some embodiments, the SL resource assigned for transmission of the SL signal within the intended SL CO may indicate at least one of the following:

● a PSCCH resource,

● a PSSCH resource,

● a PSFCH resource, or

● a PSBCH resource.

In some embodiments, the type of the CA procedure to be used to initiate the intended sidelink CO, or the type of the CA procedure to be used for the assigned SL resource within the intended SL CO may comprise at least one of following:

● Type 1 CA procedure,

● Type 2A CA procedure,

● Type 2B CA procedure, or,

● Type 2C CA procedure.

In some embodiments, the second DCI may use a DCI format 3-3. Table 2 shows an example of contents of the DCI format 3-3 for the first terminal device 110.

Table 2

DCI contents	Indicator
Sidelink resource (s) assignment	PSCCH and PSSCH resource assignment
initial terminal device indicator	“1”
CA Type for the assigned SL resource	“11”
CAPC	3
SCI for the SL CO (the first flag)	“0”
SL CO feedback (the second flag)	“1”

Descriptions of fields in Table 2 are provided as below:

● sidelink resource assignment: indicating a PSCCH resource and corresponding PSSCH resource within the intended SL CO, and the PSCCH/PSSCH is on the start slot of the intended SL CO, indication overhead depending on the sidelink resource configuration on the unlicensed spectrum;

● initial terminal device indicator: 1 bit, “1” indicating the first terminal device 110 is an initial terminal device for the intended SL CO, else, it is set to “0” ;

● CA Type for the assigned SL resource: 2 bits, “00” (0) indicating Type 2C CA, “01” (1) indicating Type 2B CA, “10” (2) indicating Type 2A CA, “11” (3) indicating Type 1 CA;

● CAPC: 2 bits, as the first terminal device 110 is indicated as an initial terminal device, the CAPC level = 3 represents the CAPC to be used in Type 1 CA procedure to obtain the intended SL CO;

● SCI for indicating the SL CO: 1 bit, “1” indicating the SCI needs to be sent by the first terminal device 110, else, it is set to “0” ;

● SL CO feedback: 1 bit, “1” indicating a feedback needs to be sent to the network device 140 to indicate whether the CA procedure for the intended SL CO is successfully obtained or not, else, it is set to “0” .

In some embodiments, the scheduling information may comprise third DCI for scheduling the first terminal device 110 within the intended SL CO. The third DCI may provide flexible scheduling for a terminal device on unlicensed spectrum. In addition, the third DCI may provide an additional scheme for sharing SL CO among terminal devices.

Embodiments of Third DCI

In some embodiments, the third DCI may indicate at least one of the following:

● a sidelink resource assigned for transmission of the sidelink signal on the first type of the resources,

● a type of a CA procedure to be used to initiate the intended sidelink CO,

● a type of a CA procedure to be used for the assigned sidelink resource within the intended SL CO,

● a first CAPC,

● a start slot of the intended SL CO,

● a duration of the intended SL CO,

● at least one RB set for the intended SL CO,

● a first flag indicating whether SCI indicating the intended SL CO is to be transmitted,

● a second flag indicating whether a feedback is to be transmitted to the network device to indicate that the intended SL CO is successfully obtained,

● a third flag indicating whether the intended SL CO can be shared by the second terminal device 120,

● a type of sidelink terminal devices which are allowed to share the intended SL CO, or

● a CAPC threshold.

● an index of the start slot, or

● a first slot offset between a first slot and the start slot, wherein the third DCI is received on the first slot.

● the number of slots comprised in the intended SL CO;

● a second slot offset between a first slot and an end slot of the intended SL CO, wherein the third DCI is received on the first slot; or

● a bitmap,

● an index of RB set, or

● a resource indicator value (RIV) .

In some embodiments, the type of sidelink terminal devices which are allowed to share the intended SL CO is indicated by at least one of the following:

● an identity of a SL COmmunication group,

● an identity of a sidelink broadcast transmission, or

● an identity of at least one sidelink terminal device.

In some embodiments, the first CAPC indicates a CAPC to be used in a CA procedure to initiate the intended SL CO.

In some embodiments, the CAPC threshold indicates a CAPC threshold for sharing the intended SL CO.

In some embodiments, a sidelink resource assigned for transmission of the sidelink signal within the intended SL CO indicates at least one of the following:

● a PSCCH resource,

● a PSSCH resource,

● a PSFCH resource, or

● a PSBCH resource.

In some embodiments, the type of the CA procedure to be used to initiate the intended sidelink CO, or the type of the CA procedure to be used for the assigned sidelink resource within the intended SL CO comprises at least one of following:

● Type 1 CA procedure,

● Type 2A CA procedure,

● Type 2B CA procedure, or,

● Type 2C CA procedure.

In such embodiments, the scheduling information may comprise an index of an entry of the SL CO sharing configuration.

In such embodiments, the index of the entry of the SL CO sharing configuration may be indicated in the third DCI.

In such embodiments, the SL CO sharing list associated with the third DCI may be the same as that associated with the first DCI. Thus, details of the SL CO sharing list are omitted for brevity.

Fig. 10 illustrates a signaling chart illustrating a process 1000 for SL-U scheduling with the third DCI in accordance with some implementations of the present disclosure. Fig. 11 illustrates an example of COT sharing with the third DCI in accordance with some embodiments of the present disclosure.

For the purpose of discussion, the process 1000 will be described with reference to Figs. 1 and 11. The process 1000 may involve the network device 140, the first terminal device 110, the second terminal device 120 and the third terminal device 130 as illustrated in Fig. 1. Although the process 1000 will be described in the communication network 100 of Fig. 1, this process may be likewise applied to other communication scenarios.

As shown in Fig. 10, the network device 140 transmits 1010, to the first terminal device 110, the third DCI for scheduling the first terminal device 110 within the intended SL CO. For example, as shown in Fig. 11, the network device 140 may transmit the third DCI for scheduling the first terminal device 110 on slot #t.

The network device 140 transmits 1020, to the second terminal device 120, the third DCI for scheduling the second terminal device 120 within the intended SL CO. For example, as shown in Fig. 11, the network device 140 may transmit the third DCI for scheduling the second terminal device 120 on slot #t+1.

On the side of the first terminal device 110, the first terminal device 110 receives the third DCI for scheduling the first terminal device 110 and obtains information of the intended SL CO from the third DCI.

The third DCI for scheduling the first terminal device 110 may indicate the following:

● configuration of the intended SL CO,

● the first terminal device 110 is assigned to initiate the intended SL CO,

● Type 1 CA procedure is to be used to initiate the intended SL CO,

● PSCCH and PSSCH resources assigned on a start slot of the intended SL CO, and

● SCI indicating the intended SL CO is to be transmitted by the first terminal device 110.

In turn, before slot #t+k, the first terminal device 110 performs 1030 Type 1 CA procedure to initiate the SL CO with CAPC of 2.

If the Type 1 CA procedure succeeds, the first terminal device 110 transmits 1040 sidelink data on slot #t+k according to the third DCI. For example, the first terminal device 110 may broadcast or groupcast the sidelink data so that the second terminal device 120 and the third terminal device 130 may receive the sidelink data. In some embodiments, the first terminal device 110 may transmit sidelink unicast data to a target terminal device, e.g., the second terminal device 120, and the sidelink unicast pair terminal device 120 may receive the sidelink data.

The first terminal device 110 also transmits, on slot #t+k, SCI indicating the intended SL CO.

On the side of the second terminal device 120, the second terminal device 120 receives the third DCI for scheduling the second terminal device 120 and obtains information of the intended SL CO from the third DCI.

The third DCI for scheduling the second terminal device 120 may indicate the following:

● configuration of the intended SL CO,

● Type 2A CA procedure is to be used to share the resources within the intended SL CO, and

● assigned sidelink resources are within the intended SL CO which may initiated by the first terminal device 110.

In turn, before slot #t+k+1, the second terminal device 120 performs 1050 Type 2A CA procedure to share the resources within the intended SL CO.

If the Type 2A CA procedure succeeds, the second terminal device 120 transmits 1060 sidelink data on slot #t+k+1 according to the third DCI. For example, the second terminal device 120 may broadcast or groupcast the sidelink data so that the first terminal device 110 and the third terminal device 130 may receive the sidelink data.

In some embodiments, the third DCI may use a DCI format 3-4. Table 3 shows an example of contents of the DCI format 3-3 for the first terminal device 110.

Table 3

DCI format 3-4 contents	Indicator
Sidelink resource (s) assignment	PSCCH and PSSCH resources assignment
CA Type to initiate the intended SL CO	Type	1 CA
CAPC
	2
initial terminal device indicator	“1”
Start slot of the intended SL CO	Slot offset = k
CO duration	m (slots)
CO sharing indicator	“1”
CAPC threshold	2
SCI for the SL CO	“1”
SL CO feedback	“1”

Descriptions of fields in Table 3 are provided as below:

● “Sidelink resource (s) assignment” indicates PSCCH and PSSCH resources for transmitting sidelink data;

● “CA Type to initiate the intended SL CO” indicates that Type 1 CA procedure is to be used to initiate an SL CO;

● “CAPC” indicates that a CAPC value = 2 is to be used in the CA procedure to initiate the intended SL CO;

● “initial terminal device indicator” is set to “1” , indicates the first terminal device 110 is an initial terminal device for the intended SL CO;

● “Start slot of the intended SL CO” indicates that if the CA procedure succeeds, the SL CO should start from slot #t+k, where slot #t contains the third DCI;

● “CO duration” indicates the number of slots comprised in the intended SLCO, i.e., m slots;

● “CO sharing indicator” is set to “1” , indicates the intended SL CO can be shared with other UE (s) ;

● “CAPC threshold” indicates the CAPC threshold for sharing the intended SL CO, i.e., responding UE (s) may share the resources within the intended SL CO for sidelink data with CAPC equal to or higher than the CAPC threshold;

● “SCI for the SL CO” is set to “1” , indicates that an SCI for the SL CO should be transmitted by the first terminal device 110 if the intended SL CO is successfully initiated, the SCI may indicate that the SL CO can be shared and the CAPC threshold for sharing the SL CO, the PSCCH resource for the SCI is assigned in the third DCI;

● “SL CO feedback” is set to “1” , indicates a feedback is to be transmitted to the network device to indicate that the intended SL CO is successfully obtained.

Table 4 shows an example of contents of the DCI format 3-3 for the second terminal device 120.

Table 4

Descriptions of fields in Table 4 are provided as below:

● “CA Type for the assigned sidelink resource” indicates that Type 2A CA procedure is to be used for the assigned sidelink resource within the intended SL CO;

● “CAPC” indicates that a CAPC value = 1 which is the CAPC level of sidelink data or signal to be transmitted by the second terminal device 120 on the assigned sidelink resources within the intended SL CO;

● “initial terminal device indicator” is set to “0” , indicating the second terminal device 120 is not an initial terminal device for the intended SL CO;

● “Start slot of the intended SL CO” indicates that if the intended SL CO is successfully initiated, the intended SL CO should start from slot #t+1+k’ , where slot #t+1 contains the third DCI;

● “CO duration” indicates m’s lots are comprised in the intended SL CO, m’ should be aligned to the indication in the DCI for the first terminal device 110;

● “CO sharing indicator” is set to “1” , indicating the intended SL CO can be shared with other UE (s) ;

● “SCI for the SL CO” is set to “0” , indicates that an SCI for the SL CO should not be transmitted by the second terminal device 120; and

● “SL CO feedback” is set to “0” , indicates no feedback is to be transmitted to the network device.

In such embodiments, the second terminal device 120 should try to detect the SCI for the SL CO in the intended SL CO;

Under some conditions, the first terminal device 120 or the second terminal device 120 may use a CA type different from the indication of the network device 140 to access channel. In other words, there may be CA type switching. Hereinafter, some embodiments of CA type switching will be described by taking the second terminal device 120 for example.

Embodiments of CA type switching

In some embodiments, the scheduling information indicates a Type 1 CA procedure to be used for an assigned sidelink resource within the intended SL CO. In such embodiments, if the intended SL CO is initiated and the assigned sidelink resource is covered within the intended SL CO, the second terminal device 120 may change to perform a Type 2 CA procedure for transmission of the sidelink signal. This will be described with reference to Fig. 12A.

Fig. 12A illustrates an example of CA type switching in accordance with some embodiments of the present disclosure. In this example, the network device 140 indicates an intended SL CO in the first DCI. The first terminal device 110 and the second terminal device 120 are respectively scheduled to use Type 1 CA procedure to access channel for sidelink transmissions on slot #n and slot #n+1.

The first terminal device 110 uses Type 1 CA procedure to access channel and succeeds to initiate an SL CO according to the indication of the intended SL CO. The SL CO starts from slot #n.

The second terminal device 120 detects the SL CO starting from slot #n. Specifically, the SL CO duration is 3 slots, which covers the assigned resources on slot #n+1, and frequency domain resources assigned for the second terminal device 120 are also comprised within the resources of the SL CO. The SL CO can be shared by the second terminal device 120. The assigned resources on slot #n+1 are not reserved by other terminal devices. Then, the second terminal device 120 changes to use Type 2A CA procedure instead of Type 1 CA procedure to share the resource within the SL CO and transmits a sidelink signal on the assigned resources.

In some embodiments, the scheduling information indicates a Type 2 CA procedure to be used for an assigned sidelink resource within the intended SL CO.

In such embodiments, if the intended SL CO covering the assigned sidelink resource is unavailable, the second terminal device 120 performs a Type 1 CA procedure for transmission of the sidelink signal.

In such embodiments, the second terminal device 120 may determine that the intended SL CO covering the assigned sidelink resource is unavailable based on determining at least one of the following:

● a failure of detecting the intended SL CO,

● a failure of detecting SCI indicating the intended SL CO, or

● an indication of the intended SL CO is not shared.

Alternatively, in some embodiments, only the sidelink signal with CAPC level equal to or higher than the CAPC threshold can share the resource within the intended SL CO.In such embodiments, if the CAPC of the sidelink signal to be transmitted by the second terminal device 120 is below the CAPC threshold for sharing the intended SL CO, the second terminal device 120 may determine that the intended SL CO covering the assigned sidelink resource is unavailable.

Fig. 12B illustrates another example of CA type switching in accordance with some embodiments of the present disclosure. In this example, the network device 140 indicates third DCI for the first terminal device 110 and the second terminal device 120 respectively.

For the first terminal device 110, Type 1 CA procedure is indicated to access channel and initiate an SL CO with 3 slots as CO duration.

For the second terminal device 120, Type 2A CA procedure is indicated to access channel within an SL CO which would be initiated starting from slot #n.

The first terminal device 110 uses Type 1 CA procedure to access channel but fails to initiate the SL CO starting from slot #n, and cannot transmit a sidelink signal on the assigned resources on slot #n.

The second terminal device 120 does not detect the SL CO starting from slot #n. in other words, the second terminal device 120 determines a failure of detecting the intended SL CO. Then, the second terminal device 120 changes to use Type 1 CA procedure before slot #n+1 to access channel.

When the Type 1 CA procedure of the second terminal device 120 succeeds, it initiates an SL CO with CO duration of 2 slots. That is, an end of the SL CO initiated by the second terminal device 120 is the same as that of the intended SL CO configured in the third DCI for the first terminal device 110. Then, the second terminal device 120 transmits a sidelink signal on the assigned resources on slot #n+1.

When the Type 1 CA procedure of the second terminal device 120 fails, it cannot transmit a sidelink signal on the assigned resources.

In some embodiments, an initial terminal device of an SL CO or a responding terminal device which sharing the resource of the SL CO may transmit SCI indicating the intended SL CO. The SCI may provide information of an SL CO which may be shared by SL terminal devices and improve SL transmission efficiency. For example, the SCI may use SCI format 1-B. Hereinafter, some embodiments of the SCI will be described.

Embodiments of SCI

In some embodiments, the first terminal device 110 may be a sidelink terminal device which initiates the intended SL CO. In other words, the first terminal device 110 may be an initial terminal device of the SL CO. In such embodiments, the first terminal device 110 may determine the first SCI based on the scheduling information received from the network device 140.

In embodiments where the scheduling information comprises the first DCI, the first terminal device 110 may determine the first SCI based on relevant fields in the first DCI.

In embodiments where the scheduling information comprises the third DCI, the first terminal device 110 may determine the first SCI based on relevant fields in the third DCI.

In some embodiments, the first terminal device 110 may determine the first SCI based on CA procedure result. In such embodiments, contents of the first SCI may be different from the contents of the first DCI or the third DCI.

In some embodiments, the second terminal device 120 may be a sidelink terminal device which shares a resource within the intended SL CO. In other words, the second terminal device 120 may be a responding terminal device sharing the resource within the intended SL CO. In such embodiments, the second terminal device 120 may receive the first SCI indicating the intended SL CO from the first terminal device 110. In turn, the second terminal device 120 may determine second SCI indicating the intended SL CO based on the first SCI.

In some embodiments, the first SCI or the second SCI may indicate at least one of the following:

● a duration of the intended SL CO,

● at least one RB set for the intended SL CO,

● a CAPC threshold for sharing the intended SL CO,

● a type of a CA procedure which is allowed to be used for sharing the intended SL CO,

● a third flag indicating whether the intended SL CO can be shared by a terminal device,

● an identity of a sidelink terminal device which initiates the intended SL CO.

In some embodiments, the first SCI or the second SCI may indicate the duration of the intended SL CO by indicating at least one of the following:

● the number of slots from a start slot of the intended SL CO to an end slot of the intended SL CO,

● the number of slots from a slot which contains the first SCI or the second SCI to the end slot of the intended SL CO,

● the number of slots from a slot which contains the first SCI or the second SCI to the end slot of the intended SL CO minus one, or

● remaining duration of the intended SL CO.

Fig. 13A illustrates an example of SCI transmission in accordance with some embodiments of the present disclosure. In this example, the network device 140 transmits third DCI for the first terminal device 110 which indicates the following:

● an intended SL CO starts from slot #n, and CO duration = 4 slots;

● PSCCH and relevant PSSCH on slot #n, i.e., the start slot of the intended SL CO;

● PSCCH and relevant PSSCH on slot #n+1, i.e., consecutive transmissions for the first terminal device 110;

● the first terminal device 110 should use Type 1 CA procedure to initiate an SL CO with CAPC = 2;

● the first terminal device 110 should send SCI indicating the initiated SL CO.

The first terminal device 110 receives the third DCI for the first terminal device 110 from the network device 140.

The first terminal device 110 performs Type 1 CA procedure to initiate an SL CO before slot #n. However, the first terminal device 110 fails to initiate the intended SL CO on slot #n, and cannot transmit PSCCH/PSSCH on the assigned resources.

The first terminal device 110 continues to perform Type 1 CA procedure and succeeds before slot #n+1. As a result, the first terminal device 110 initiates an SL CO starting from slot #n+1;

In turn, the first terminal device 110 transmits sidelink data on the assigned PSCCH/PSSCH on slot #n+1.

In addition, the first terminal device 110 transmits SCI (for example, the first SCI) indicating the initiated SL CO. In some embodiments, PSCCH resource for transmitting the first SCI is pre-configured. For example, it may be pre-configured that PSCCH on slot #n+1 is used.

An example of contents of the first SCI is shown in Table 5.

Table 5

SCI content	Indicator
CO duration	3 (slots)
RB set indicator	1100 (bitmap)
CAPC threshold	2
CA type	Type	2A/2B
CO sharing flag	“1”
Allowed type	unicast
Initial terminal device ID	ID of the first terminal device 110

Descriptions of fields in Table 5 are provided as below:

● “CO duration” indicates the SL CO duration is 3 slots;

● “CO sharing flag” indicates the SL CO can be shared;

● “CAPC threshold” indicates the CAPC threshold for sharing the SL CO is 2;

● allowed type = “unicast” , i.e., only the unicast sidelink transmission to the first terminal device 110 is allowed to share the remain resources in the SL CO;

● “initial terminal device ID” indicates an ID of the first terminal device 110 itself.

In such embodiments, as the first terminal device 110 fails to initiate the intended SL CO on slot #n, and then succeeds on slot #n+1, the SL CO duration is 3 slots which is different from the “CO duration = 4 slots” indicated in the third DCI. The actual SL CO duration is determined according to the CA procedure result of the first terminal device 110.

In the example of Fig. 13A, the network device 140 also transmits third DCI for the second terminal device 120 which indicates the following:

● an intended SL CO starts from slot #n, and CO duration = 4 slots;

● PSCCH and relevant PSSCH on slot #n+2;

● the second terminal device 120 should use Type 2A CA procedure to access channel within the intended SL;

● the second terminal device 120 should send SCI indicating the SL CO.

The second terminal device 120 receives the third DCI for the second terminal device 120 from the network device 140.

The second terminal device 120 also receives the first SCI from the first terminal device 110.

The second terminal device 120 performs Type 2A CA procedure to share resource in the SL CO.

The second terminal device 120 transmits sidelink data on the assigned PSCCH/PSSCH on slot #n+2.

The second terminal device 120 sends SCI (for example, the second SCI) indicating the SL CO. In some embodiments, PSCCH resource for transmitting the second SCI is pre-configured. For example, it may be pre-configured that PSCCH on slot #n+2 is used.

An example of contents of the second SCI is shown in Table 6.

Table 6

SCI content	Indicator
CO duration	2 (slots)
RB set indicator	1100 (bitmap)
CAPC threshold	2
CA type	Type	2A/2B
CO sharing flag	“1”
Allowed type	unicast
Initial terminal device ID	ID of the first terminal device 110

The contents of the second SCI should be determined as the same as the first SCI transmitted by the first terminal device 110 except that the SL CO duration is 2 slots.

In order to transmit the first SCI, the first terminal device 110 may determine a first PSCCH resource for transmitting the first SCI. Hereinafter, some embodiments of determining the first PSCCH resource for transmitting the first SCI will be described.

Embodiments of determining PSCCH resource for transmitting the first SCI

In some embodiments, the first terminal device 110 may determine the first PSCCH resource based on at least one of the following:

● the scheduling information,

● a configuration,

● a pre-configuration, or

● a predefinition.

Such embodiments provide PSCCH resource for SCI indicating SL CO relevant information with less signaling overhead. In addition, it benefits the terminal device detection of the potential SL CO.

In some embodiments, the scheduling information indicates PSCCH resources. In some embodiments, the first terminal device 110 may determine one of the PSCCH resources assigned in the scheduling information which has a lowest index or a highest index as the first PSCCH resource.

In some embodiments, the configuration or the pre-configuration indicates at least one of the following:

● an index of the first PSCCH resource in a sidelink resource pool,

● an index of a sub-channel which contains the first PSCCH resource, or

● an index of a logical slot within the intended SL CO which contains the first PSCCH resource.

In some embodiments, the predefinition indicates at least one of the following:

● the first PSCCH resource is located on a start slot of the intended SL CO,

● the first PSCCH resource is located on each of slots within the intended SL CO, or

● the first PSCCH resource has a lowest index or a highest index among PSCCH resources in a sidelink resource pool or a resource block set.

In some embodiments, the first terminal device 110 may transmit the first SCI and sidelink data on the same slot within the intended SL CO.

Fig. 13B illustrates another example of SCI transmission in accordance with some embodiments of the present disclosure. In this example, the network device 140 transmits third DCI for the first terminal device 110 and third DCI for the second terminal device 120.

The third DCI for the first terminal device 110 indicates the first terminal device 110 to transmit the first SCI. The third DCI for the second terminal device 120 indicates the second terminal device 120 to transmit the second SCI. Other settings in this example are the same as those in the example of Fig. 13A.

PSCCHs for the first SCI and the second SCI are pre-defined as the PSCCH resources on each of slots within an SL CO at the lowest index, i.e., the PSCCHs contained in the lowest sub-channel in an SL resource pool.

The first terminal device 110 initiates the intended SL CO successfully on slot #n. The first terminal device 110 transmits the first SCI on slot #n using PSCCH index #0, i.e., the lowest PSCCH index comprised in the lowest index sub-channel. The first terminal device 110 also transmits the first SCI on slot #n+1 using PSCCH index #0. On slot #n and slot #n+1, the first terminal device 110 also transmits PSSCH carrying sidelink data.

The second terminal device 120 transmits the second SCI on slot #n+2 using PSCCH index #0. On slot #n+2, the second terminal device 120 also transmits PSSCH carrying sidelink data.

Fig. 13C illustrates a further example of SCI transmission in accordance with some embodiments of the present disclosure. In this example, the network device 140 transmits third DCI for the first terminal device 110 and third DCI for the second terminal device 120.

The network device 140 assigns PSCCH and PSSCH resources for the first terminal device 110 on slot #n and slot n+1.

The network device 140 assigns PSCCH and PSSCH resources for the second terminal device 120 on slot #n+1 and slot n+2.

PSCCH resources for the first SCI and the second SCI are configured through a high layer signaling as: the PSCCH resources on each of slots within an SL CO at the highest index, i.e., the PSCCH resources contained in the highest index of sub-channel in an SL resource pool.

The first terminal device 110 initiates the intended SL CO successfully on slot #n. The first terminal device 110 transmits the first SCI on slot #n using PSCCH index #N-1 (N is the number of sub-channels in the SL resource pool. The first terminal device 110 also transmits the first SCI on slot #n+1 using PSCCH index #N-1.

The second terminal device 120 transmits the second SCI on slot #n+1 and slot #n+2 using PSCCH index #N-1. On the PSCCH resource for SCI on slot #n+1, both the first terminal device 110 and the second terminal device 120 transmit the SCI. That is, more than one terminal device may transmit SCI for indicating an SL CO with the same SCI content.

Fig. 14 is a simplified block diagram of a device 1400 that is suitable for implementing some embodiments of the present disclosure. The device 1400 can be considered as a further example embodiment of one of the

terminal devices

110, 120 and 130, or one of the

network devices

140 and 150 as shown in Fig. 1. Accordingly, the device 1400 can be implemented at or as at least a part of one of the

terminal devices

110, 120 and 130, or one of the

network devices

140 and 150.

As shown, the device 1400 includes a processor 1410, a memory 1420 coupled to the processor 1410, a suitable transmitter (TX) and receiver (RX) 1440 coupled to the processor 1410, and a communication interface coupled to the TX/RX 1440. The memory 1420 stores at least a part of a program 1430. The TX/RX 1440 is for bidirectional communications. The TX/RX 1440 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 interface for bidirectional communications between gNBs or eNBs, S1 interface for communication between a Mobility Management Entity (MME) /Serving Gateway (S-GW) and the gNB or eNB, Un interface for communication between the gNB or eNB and a relay node (RN) , or Uu interface for communication between the gNB or eNB and a terminal device.

The program 1430 is assumed to include program instructions that, when executed by the associated processor 1410, enable the device 1400 to operate in accordance with the embodiments of the present disclosure, as discussed herein with reference to Figs. 1 to 13. The embodiments herein may be implemented by computer software executable by the processor 1410 of the device 1400, or by hardware, or by a combination of software and hardware. The processor 1410 may be configured to implement various embodiments of the present disclosure. Furthermore, a combination of the processor 1410 and memory 1420 may form processing means 1450 adapted to implement various embodiments of the present disclosure.

The memory 1420 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 1420 is shown in the device 1400, there may be several physically distinct memory modules in the device 1400. The processor 1410 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 1400 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.

The components included in the apparatuses and/or devices of the present disclosure may be implemented in various manners, including software, hardware, firmware, or any combination thereof. In one embodiment, one or more units may be implemented using software and/or firmware, for example, machine-executable instructions stored on the storage medium. In addition to or instead of machine-executable instructions, parts or all of the units in the apparatuses and/or devices may be implemented, at least in part, by one or more hardware logic components. For example, and without limitation, illustrative types of hardware logic components that can be used include Field-programmable Gate Arrays (FPGAs) , Application-specific Integrated Circuits (ASICs) , Application-specific Standard Products (ASSPs) , System-on-a-chip systems (SOCs) , Complex Programmable Logic Devices (CPLDs) , and the like.

Claims

A method for sidelink communications, comprising:

receiving, at a first terminal device, scheduling information for sidelink transmission on a first type of resources, wherein the scheduling information indicates an intended sidelink channel occupancy (CO) which can be used at least by the first terminal device, the first type of resources are comprised on unlicensed spectrum; and

transmitting a sidelink signal according to the scheduling information.
The method of claim 1, wherein the scheduling information comprises first downlink control information (DCI) for the intended sidelink CO.
The method of claim 2, wherein the first DCI indicates at least one of the following:

a start slot of the intended sidelink CO,

a duration of the intended sidelink CO,

at least one resource block (RB) set for the intended sidelink CO,

a type of a channel access (CA) procedure to be used to initiate the intended sidelink CO,

a first channel access priority class (CAPC) ,

a type of sidelink terminal devices which are allowed to share the intended sidelink CO, or

an identity of a sidelink terminal device which is assigned to initiate the intended sidelink CO.
The method of claim 2, wherein the scheduling information further comprises second DCI for scheduling the first terminal device within the intended sidelink CO; and

wherein the second DCI indicates at least one of the following:

a sidelink resource assigned for transmission of the sidelink signal within the intended sidelink CO,

an indication indicating whether the first terminal device is assigned to initiate the intended sidelink CO,

a type of a channel access (CA) procedure to be used to initiate the intended sidelink CO,

a type of a channel access (CA) procedure to be used for the assigned sidelink resource within the intended sidelink CO,

a first channel access priority class (CAPC) ,

a CAPC threshold,

a first flag indicating whether sidelink control information (SCI) indicating the intended sidelink CO is to be transmitted, or

a second flag indicating whether a feedback is to be transmitted to indicate that the intended sidelink CO is successfully obtained.
The method of claim 1, wherein the scheduling information comprises third downlink control information (DCI) for scheduling the first terminal device within the intended sidelink CO; and

wherein the third DCI indicates at least one of the following:

a sidelink resource assigned for transmission of the sidelink signal on the first type of the resources,

a type of a channel access (CA) procedure to be used to initiate the intended sidelink CO,

a type of a channel access (CA) procedure to be used for the assigned sidelink resource within the intended sidelink CO,

a first channel access priority class (CAPC) ,

an indication indicating whether the first terminal device is assigned to initiate the intended sidelink CO,

a start slot of the intended sidelink CO,

a duration of the intended sidelink CO,

at least one resource block (RB) set for the intended sidelink CO,

a first flag indicating whether sidelink control information (SCI) indicating the intended sidelink CO is to be transmitted,

a second flag indicating whether a feedback is to be transmitted to the network device to indicate that the intended sidelink CO is successfully obtained,

a third flag indicating whether the intended sidelink CO can be shared by a second terminal device,

a type of sidelink terminal devices which are allowed to share the intended sidelink CO, or

a CAPC threshold.
The method of claim 3 or 5, wherein the start slot of the intended sidelink CO is indicated by at least one of the following:

an index of the start slot, or

a first slot offset between a first slot and the start slot, wherein the first DCI is received on the first slot, or the third DCI is received on the first slot.
The method of claim 3 or 5, wherein the duration of the intended sidelink CO is indicated by at least one of the following:

the number of slots comprised in the intended sidelink CO;

a second slot offset between a first slot and an end slot of the intended sidelink CO, wherein the first DCI is received on the first slot, or the third DCI is received on the first slot; or

an index of the duration of the intended sidelink CO within a list of available sidelink CO durations, the list being configured by a high layer signaling.
The method of claim 1, further comprising:

receiving configuration information which indicates a sidelink CO sharing list, the sidelink CO sharing list comprising at least one entry of sidelink CO sharing configuration.
The method of claim 8, wherein the scheduling information comprises an index of an entry of the sidelink CO sharing configuration; and

wherein:

the index of the entry of the sidelink CO sharing configuration is indicated in first downlink control information (DCI) , or

the index of the entry of the sidelink CO sharing configuration is indicated in third DCI.
The method of claim 1, wherein the scheduling information indicates a Type 1 channel access (CA) procedure to be used for an assigned sidelink resource within the intended sidelink CO; and

wherein the method further comprises:

in accordance with a determination that the intended sidelink CO is initiated and the assigned sidelink resource is covered within the intended sidelink CO, performing a Type 2 CA procedure for transmission of the sidelink signal.
The method of claim 1, wherein the scheduling information indicates a Type 2 channel access (CA) procedure to be used for an assigned sidelink resource within the intended sidelink CO;

wherein the method further comprises:

in accordance with a determination that the intended sidelink CO covering the assigned sidelink resource is unavailable, performing a Type 1 CA procedure for transmission of the sidelink signal.
The method of claim 11, further comprising:

determining that the intended sidelink CO covering the assigned sidelink resource is unavailable based on determining at least one of the following:

a failure of detecting the intended sidelink CO,

a failure of detecting sidelink control information (SCI) indicating the intended sidelink CO,

an indication of the intended sidelink CO is not shared, or

a channel access priority class (CAPC) of the sidelink signal being below a CAPC threshold for sharing the intended sidelink CO.
The method of claim 1, further comprising:

determining a first physical sidelink control channel (PSCCH) resource within the intended sidelink CO; and

transmitting first sidelink control information (SCI) indicating the intended sidelink CO on the first PSCCH resource.
The method of claim 13, wherein the first SCI indicates at least one of the following:

a duration of the intended sidelink CO,

at least one resource block (RB) set for the intended sidelink CO,

a channel access priority class (CAPC) threshold for sharing the intended sidelink CO,

a type of a channel access (CA) procedure which is allowed to be used for sharing the intended sidelink CO,

a third flag indicating whether the intended sidelink CO can be shared by a second terminal device,

a type of sidelink terminal devices which are allowed to share the intended sidelink CO, or

an identity of a sidelink terminal device which initiates the intended sidelink CO.
A method for sidelink communications, comprising:

determining, at a network device, scheduling information for sidelink transmission on a first type of resources, wherein the scheduling information indicates an intended sidelink channel occupancy (CO) , the first type of resources are comprised on unlicensed spectrum; and

transmitting the scheduling information.
The method of claim 15, wherein the scheduling information comprises first downlink control information (DCI) for the intended sidelink CO; and

wherein the first DCI indicates at least one of the following:

a start slot of the intended sidelink CO,

a duration of the intended sidelink CO,

at least one resource block (RB) set for the intended sidelink CO,

a type of a channel access (CA) procedure to be used to initiate the intended sidelink CO,

a first channel access priority class (CAPC) ,

a type of sidelink terminal devices which are allowed to share the intended sidelink CO, or

an identity of a sidelink terminal device which is assigned to initiate the intended sidelink CO.
The method of claim 16, wherein the scheduling information further comprises second DCI for scheduling the first terminal device within the intended sidelink CO; and

wherein the second DCI indicates at least one of the following:

a sidelink resource assigned for transmission of the sidelink signal within the intended sidelink CO,

an indication indicating whether the first terminal device is assigned to initiate the intended sidelink CO,

a type of a channel access (CA) procedure to be used to initiate the intended sidelink CO,

a type of a channel access (CA) procedure to be used for the assigned sidelink resource within the intended sidelink CO,

a first channel access priority class (CAPC) ,

a CAPC threshold,

a first flag indicating whether sidelink control information (SCI) indicating the intended sidelink CO is to be transmitted, or

a second flag indicating whether a feedback is to be transmitted to indicate that the intended sidelink CO is successfully obtained.
The method of claim 1, wherein the scheduling information comprises third downlink control information (DCI) for scheduling the first terminal device within the intended sidelink CO; and

wherein the third DCI indicates at least one of the following:

a sidelink resource assigned for transmission of the sidelink signal on the first type of the resources,

a type of a channel access (CA) procedure to be used to initiate the intended sidelink CO,

a type of a channel access (CA) procedure to be used for the assigned sidelink resource within the intended sidelink CO,

a first channel access priority class (CAPC) ,

an indication indicating whether the first terminal device is assigned to initiate the intended sidelink CO,

a start slot of the intended sidelink CO,

a duration of the intended sidelink CO,

at least one resource block (RB) set for the intended sidelink CO,

a first flag indicating whether sidelink control information (SCI) indicating the intended sidelink CO is to be transmitted,

a second flag indicating whether a feedback is to be transmitted to the network device to indicate that the intended sidelink CO is successfully obtained,

a third flag indicating whether the intended sidelink CO can be shared by a second terminal device,

a type of sidelink terminal devices which are allowed to share the intended sidelink CO, or

a CAPC threshold.
A computer readable medium having instructions stored thereon, the instructions, when executed on at least one processor of a device, causing the device to carry out the method according to any of claims 1-14.
A computer readable medium having instructions stored thereon, the instructions, when executed on at least one processor of a device, causing the device to carry out the method according to any of claims 15-18.