WO2024016882A1

WO2024016882A1 - Method and apparatus for sidelink transmission

Info

Publication number: WO2024016882A1
Application number: PCT/CN2023/099120
Authority: WO
Inventors: Zhang Zhang; Min Wang
Original assignee: Telefonaktiebolaget Lm Ericsson (Publ)
Priority date: 2022-07-20
Filing date: 2023-06-08
Publication date: 2024-01-25

Abstract

Various embodiments of the present disclosure provide a method for sidelink (SL) transmission. The method which may be performed by a first terminal device comprises: generating a message which includes SL channel state information (CSI) reports and/or inter-user equipment (inter-UE) coordination information for a set of terminal devices. In accordance with an exemplary embodiment, the method further comprises: transmitting the message towards the set of the terminal devices.

Description

METHOD AND APPARATUS FOR SIDELINK TRANSMISSION

FIELD OF THE INVENTION

The present disclosure generally relates to communication networks, and more specifically, to a method and apparatus for sidelink (SL) transmission.

BACKGROUND

This section introduces aspects that may facilitate a better understanding of the disclosure. Accordingly, the statements of this section are to be read in this light and are not to be understood as admissions about what is in the prior art or what is not in the prior art.

Communication service providers and network operators have been continually facing challenges to deliver value and convenience to consumers by, for example, providing compelling network services and performance. With the evolution of wireless communication, a requirement for supporting device-to-device (D2D) communication features in various applications is proposed. An extension for the D2D work may consist of supporting vehicle-to-everything (V2X) communication, which may include any combination of direct communications among vehicles, pedestrians and infrastructure. Wireless communication networks such as fourth generation (4G) /long term evolution (LTE) and fifth generation (5G) /new radio (NR) networks may be expected to support various communication services such as V2X services for D2D capable user equipment (UE) .

SUMMARY

This summary is provided to introduce a selection of concepts in a simplified form that are further described below in the detailed description. This summary is not intended to identify key features or essential features of the claimed subject matter, nor is it intended to be used to limit the scope of the claimed subject matter.

D2D communications (also referred to as sidelink (SL) communications or communications over PC5 interface) between neighboring devices are specified by the 3rd generation partnership project (3GPP) in Release-12 (Rel-12) . Some enhancements of the SL are introduced in subsequent releases for vehicle-to-vehicle (V2V) or V2X communications. In a wireless communication network supporting SL communications, an SL-capable UE may act as a relay UE which can provide the functionality to support connectivity to the network for another UE that may be out of cell coverage and may not be able to connect with the network directly. In some cases, a UE may communicate with another UE directly or via one or more relay UEs.

In order to achieve additional transmission capacity and increased data rate, besides the traditional licensed exclusive spectrum, the next generation communication systems such as 5G/NR are also expected to be operable on the unlicensed spectrum (also referred to as NR-U) . Since the unlicensed spectrum may be shared by various radio devices, a listen-before-talk (LBT) procedure may need to be applied by a radio device before transmitting on a channel that uses the unlicensed spectrum. The LBT procedure requires the radio device to perform a clear channel assessment (CCA) to determine if the channel is available.

SL transmissions on the unlicensed spectrum (also referred to as SL-U) may be supported in the next 3GPP releases. A SL-capable UE may need to perform an LBT operation on a channel before a SL transmission so as to determine whether the channel is occupied by another UE. If the LBT operation does not succeed for the channel, the channel may not be used for the SL transmission, resulting in a delay of the SL transmission. In case of LBT failure, some information to be carried by the SL transmission, e.g., a SL channel state information (CSI) report and/or inter-UE coordination information, may become out of dated due to not being transmitted timely. This may become more serious when the UE needs to send the SL CSI report and/or the inter-UE coordination information to each of multiple UEs individually. Therefore, it may be desirable to implement an SL transmission in a more efficient way.

Various exemplary embodiments of the present disclosure propose mechanisms to mitigate the LBT failure impact on SL CSI and/or an inter-UE coordination information request/report.

It can be appreciated that a link or a radio link over which signals are transmitted between at least two UEs for D2D operations may be called in this document as SL. The signals transmitted between the UEs for D2D operations may be called in this document as SL signals. The terms “sidelink” and “SL” may also interchangeably be called as D2D link, V2X link, ProSe link, peer-to-peer link, PC5 link, etc. The SL signals may also interchangeably be called as V2X signals, D2D signals, ProSe signals, PC5 signals, peer-to-peer signals, etc.

According to a first aspect of the present disclosure, there is provided a method performed by a first terminal device. The method comprises: determining an SL congestion level of the first terminal device. In accordance with an exemplary embodiment, the method further comprises: transmitting information related to a latency bound to a second terminal device. The latency bound is based at least in part on the SL congestion level of the first terminal device.

In accordance with an exemplary embodiment, the information related to the latency bound may include an SL congestion status which indicates the SL congestion level of the first terminal device.

In accordance with an exemplary embodiment, the SL congestion status may be transmitted to the second terminal device by the first terminal device periodically and/or in response to one or more events.

In accordance with an exemplary embodiment, the one or more events may include one or more of:

· the transmission of the SL congestion status to the second terminal device is requested by the second terminal device;

· the transmission of the SL congestion status to the second terminal device is requested by a network node;

· the SL congestion level of the first terminal device is higher than a first threshold;

· the SL congestion level of the first terminal device is lower than a second threshold; and

· a change in the SL congestion level of the first terminal device exceeds a certain range.

In accordance with an exemplary embodiment, the method according to the first aspect of the present disclosure may further comprise: receiving a parameter indicating the latency bound from the second terminal device. In this case, the latency bound may be determined by the second terminal device based at least in part on the SL congestion level of the first terminal device.

In accordance with an exemplary embodiment, the information related to the latency bound may include a parameter indicating the latency bound. In this case, the latency bound may be determined by the first terminal device based at least in part on the SL congestion level of the first terminal device.

In accordance with an exemplary embodiment, the parameter indicating the latency bound may be included in one or more of: PC5-radio resource control (PC5-RRC) signaling; an SL medium access control (MAC) control element (CE) ; and Physical layer/Layer 1 (L1) signaling.

In accordance with an exemplary embodiment, the latency bound may be used for an SL CSI report and/or inter-UE coordination information of the first terminal device.

In accordance with an exemplary embodiment, for a same SL congestion level of the first terminal device, latency bound changes/adjustments for the SL CSI report and the inter-UE coordination information may be the same or different.

According to a second aspect of the present disclosure, there is provided an apparatus which may be implemented as a first terminal device. The apparatus may comprise one or more processors and one or more memories storing computer program codes. The one or more memories and the computer program codes may be configured to, with the one or more processors, cause the apparatus at least to perform any step of the method according to the first aspect of the present disclosure.

According to a third aspect of the present disclosure, there is provided a computer-readable medium having computer program codes embodied thereon which, when executed on a computer, cause the computer to perform any step of the method according to the first aspect of the present disclosure.

According to a fourth aspect of the present disclosure, there is provided an apparatus which may be implemented as a first terminal device. The apparatus may comprise a determining unit and a transmitting unit. In accordance with some exemplary embodiments, the determining unit may be operable to carry out at least the determining step of the method according to the first aspect of the present disclosure. The transmitting unit may be operable to carry out at least the transmitting step of the method according to the first aspect of the present disclosure.

According to a fifth aspect of the present disclosure, there is provided a method performed by a second terminal device. The method comprises: receiving information related to a latency bound from a first terminal device. The latency bound is based at least in part on an SL congestion level of the first terminal device. In accordance with an exemplary embodiment, the method further comprises: determining the latency bound according to the information related to the latency bound.

In accordance with an exemplary embodiment, the information related to the latency bound received by the second terminal device according to the fifth aspect of the present disclosure may correspond to the information related to the latency bound transmitted by the first terminal device according to the first aspect of the present disclosure. Thus, the information related to the latency bound as described according to the first and fifth aspects of the present disclosure may have the same or similar contents and/or feature elements.

In accordance with an exemplary embodiment, an SL congestion status which indicates the SL congestion level of the first terminal device and is included in the information related to the latency bound may be received from the first terminal device by the second terminal device periodically and/or in response to one or more events (e.g., the one or more events as described according to the first aspect of the present disclosure) .

In accordance with an exemplary embodiment, the method according to the fifth aspect of the present disclosure may further comprise: transmitting a parameter indicating the latency bound to the first terminal device. In this case, the latency bound may be determined by the second terminal device based at least in part on the SL congestion level of the first terminal device.

In accordance with an exemplary embodiment, the second terminal device may receive a parameter indicating the latency bound and included in the information related to the latency bound from the first terminal device. In this case, the latency bound may be determined by the first terminal device based at least in part on the SL congestion level of the first terminal device.

According to a sixth aspect of the present disclosure, there is provided an apparatus which may be implemented as a second terminal device. The apparatus may comprise one or more processors and one or more memories storing computer program codes. The one or more memories and the computer program codes may be configured to, with the one or more processors, cause the apparatus at least to perform any step of the method according to the fifth aspect of the present disclosure.

According to a seventh aspect of the present disclosure, there is provided a computer-readable medium having computer program codes embodied thereon which, when executed on a computer, cause the computer to perform any step of the method according to the fifth aspect of the present disclosure.

According to an eighth aspect of the present disclosure, there is provided an apparatus which may be implemented as a second terminal device. The apparatus may comprise a receiving unit and a determining unit. In accordance with some exemplary embodiments, the receiving unit may be operable to carry out at least the receiving step of the method according to the fifth aspect of the present disclosure. The determining unit may be operable to carry out at least the determining step of the method according to the fifth aspect of the present disclosure.

According to a ninth aspect of the present disclosure, there is provided a method performed by a first terminal device. The method comprises: generating a message which includes SL CSI reports and/or inter-UE coordination information for a set of terminal devices. In accordance with an exemplary embodiment, the method further comprises: transmitting the message towards the set of the terminal devices.

In accordance with an exemplary embodiment, the first terminal device may transmit the message towards the set of the terminal devices in one or more of:

· a MAC protocol data unit (PDU) including multiple SL CSI report and/or inter-UE coordination information MAC CEs for the set of the terminal devices;

· a MAC CE including the SL CSI reports and/or the inter-UE coordination information for the set of the terminal devices; and

· L1 signaling including the SL CSI reports and/or the inter-UE coordination information for the set of the terminal devices.

In accordance with an exemplary embodiment, a number of the set of the terminal devices may be indicated in a MAC subheader and/or preconfigured.

In accordance with an exemplary embodiment, the set of the terminal devices may include one or more of:

· one or more terminal devices which have sent SL CSI requests and/or inter-UE coordination requests to the first terminal device and for which associated latency bounds are not exceeded;

· one or more terminal devices which have sent SL CSI requests and/or inter-UE coordination requests having one or more parameters with similar or same values to the first terminal device;

· one or more terminal devices towards which the first terminal device is to transmit the SL CSI reports and/or the inter-UE coordination information having one or more parameters with similar or same values; and

· one or more terminal devices with which the first terminal device has SL connections carrying similar or same data and/or services.

In accordance with an exemplary embodiment, the set of the terminal devices may be indicated by one or more identifiers included in one or more of:

· L1 signaling;

· a MAC subheader;

· a MAC CE carrying the SL CSI reports for the set of the terminal devices;

· a MAC CE carrying the inter-UE coordination information for the set of the terminal devices; and

· PC5-RRC signaling.

According to a tenth aspect of the present disclosure, there is provided an apparatus which may be implemented as a first terminal device. The apparatus may comprise one or more processors and one or more memories storing computer program codes. The one or more memories and the computer program codes may be configured to, with the one or more processors, cause the apparatus at least to perform any step of the method according to the ninth aspect of the present disclosure.

According to an eleventh aspect of the present disclosure, there is provided a computer-readable medium having computer program codes embodied thereon which, when executed on a computer, cause the computer to perform any step of the method according to the ninth aspect of the present disclosure.

According to a twelfth aspect of the present disclosure, there is provided an apparatus which may be implemented as a first terminal device. The apparatus may comprise a generating unit and a transmitting unit. In accordance with some exemplary embodiments, the generating unit may be operable to carry out at least the generating step of the method according to the ninth aspect of the present disclosure. The transmitting unit may be operable to carry out at least the transmitting step of the method according to the ninth aspect of the present disclosure.

According to a thirteenth aspect of the present disclosure, there is provided a method performed by a second terminal device. The method comprises: receiving a message transmitted by a first terminal device. The message includes SL CSI reports and/or inter-UE coordination information for a set of terminal devices. In accordance with an exemplary embodiment, the method further comprises: decoding an SL CSI report and/or inter-UE coordination information provided to the second terminal device by the first terminal device in the message, when the second terminal device belongs to the set of terminal devices.

In accordance with an exemplary embodiment, the message received by the second terminal device according to the thirteenth aspect of the present disclosure may correspond to the message generated and transmitted by the first terminal device according to the ninth aspect of the present disclosure. Thus, the message as described according to the ninth and thirteenth aspects of the present disclosure may have the same or similar contents and/or feature elements.

In accordance with an exemplary embodiment, the second terminal device may receive the message in a MAC PDU including multiple SL CSI report and/or inter-UE coordination information MAC CEs for the set of the terminal devices. Alternatively or additionally, the second terminal device may receive the message in a MAC CE and/or L1 signaling including the SL CSI reports and/or the inter-UE coordination information for the set of the terminal devices.

According to a fourteenth aspect of the present disclosure, there is provided an apparatus which may be implemented as a second terminal device. The apparatus may comprise one or more processors and one or more memories storing computer program codes. The one or more memories and the computer program codes may be configured to, with the one or more processors, cause the apparatus at least to perform any step of the method according to the thirteenth aspect of the present disclosure.

According to a fifteenth aspect of the present disclosure, there is provided a computer-readable medium having computer program codes embodied thereon which, when executed on a computer, cause the computer to perform any step of the method according to the thirteenth aspect of the present disclosure.

According to a sixteenth aspect of the present disclosure, there is provided an apparatus which may be implemented as a second terminal device. The apparatus may comprise a receiving unit and a decoding unit. In accordance with some exemplary embodiments, the receiving unit may be operable to carry out at least the receiving step of the method according to the thirteenth aspect of the present disclosure. The decoding unit may be operable to carry out at least the decoding step of the method according to the thirteenth aspect of the present disclosure.

According to a seventeenth aspect of the present disclosure, there is provided a method performed by a first terminal device. The method comprises: receiving a message transmitted by a second terminal device. The message includes an SL CSI request and/or an inter-UE coordination request to a set of terminal devices. In accordance with an exemplary embodiment, the method further comprises: determining whether to respond to the SL CSI request and/or the inter-UE coordination request.

In accordance with an exemplary embodiment, the set of the terminal devices may be indicated by one or more identifiers included in one or more of: L1 signaling, a MAC subheader, a MAC CE carrying the SL CSI request, a MAC CE carrying the inter-UE coordination request, and PC5-RRC signaling.

In accordance with an exemplary embodiment, the one or more identifiers may include: one or more bits which indicate whether a terminal device receiving the message needs to respond to the SL CSI request and/or the inter-UE coordination request.

In accordance with an exemplary embodiment, the one or more identifiers may include: one or more group identifiers associated with one or more device groups; and/or one or more bits which indicate whether the SL CSI request and/or the inter-UE coordination request are associated with the one or more group identifiers.

In accordance with an exemplary embodiment, for the one or more device groups, a member in a device group may be allowed to: receive a request containing a group identifier associated with the device group from another member in the device group, and provide a response to the request to the another member; and/or transmit a request to the device group by including the associated group identifier in the request. In an embodiment, the request may include an SL CSI request and/or an inter-UE coordination request.

In accordance with an exemplary embodiment, the first terminal device and/or the second terminal device may be configured with one or multiple group identifiers associated with one or more device groups.

In accordance with an exemplary embodiment, when the first terminal device belongs to the set of terminal devices, the first terminal device may determine to respond to the SL CSI request and/or the inter-UE coordination request. In this case, the method according to the seventeenth aspect of the present disclosure may further comprise: generating an SL CSI report and/or inter-UE coordination information, according to the SL CSI request and/or the inter-UE coordination request. In accordance with an exemplary embodiment, the first terminal device may transmit the SL CSI report and/or the inter-UE coordination information towards the second terminal device.

According to an eighteenth aspect of the present disclosure, there is provided an apparatus which may be implemented as a first terminal device. The apparatus may comprise one or more processors and one or more memories storing computer program codes. The one or more memories and the computer program codes may be configured to, with the one or more processors, cause the apparatus at least to perform any step of the method according to the seventeenth aspect of the present disclosure.

According to a nineteenth aspect of the present disclosure, there is provided a computer-readable medium having computer program codes embodied thereon which, when executed on a computer, cause the computer to perform any step of the method according to the seventeenth aspect of the present disclosure.

According to a twentieth aspect of the present disclosure, there is provided an apparatus which may be implemented as a first terminal device. The apparatus may comprise a receiving unit and a determining unit. In accordance with some exemplary embodiments, the receiving unit may be operable to carry out at least the receiving step of the method according to the seventeenth aspect of the present disclosure. The determining unit may be operable to carry out at least the determining step of the method according to the seventeenth aspect of the present disclosure.

According to a twenty-first aspect of the present disclosure, there is provided a method performed by a second terminal device. The method comprises: generating a message which includes an SL CSI request and/or an inter-UE coordination request to a set of terminal devices. In accordance with an exemplary embodiment, the method further comprises: transmitting the message towards the set of the terminal devices.

In accordance with an exemplary embodiment, the message generated and transmitted by the second terminal device according to the twenty-first aspect of the present disclosure may correspond to the message received by the first terminal device according to the seventeenth aspect of the present disclosure. Thus, the message as described according to the seventeenth and twenty-first aspects of the present disclosure may have the same or similar contents and/or feature elements.

In accordance with an exemplary embodiment, the set of the terminal devices may be indicated by one or more identifiers (e.g., one or more bits and/or one or more group identifiers, etc. ) included in one or more of: L1 signaling, a MAC subheader, a MAC CE carrying the SL CSI request, a MAC CE carrying the inter-UE coordination request, and PC5-RRC signaling.

In accordance with an exemplary embodiment, the second terminal device may be configured with one or multiple group identifiers associated with one or more device groups (e.g., the one or more device groups as described according to the seventeenth aspect of the present disclosure) .

According to a twenty-second aspect of the present disclosure, there is provided an apparatus which may be implemented as a second terminal device. The apparatus may comprise one or more processors and one or more memories storing computer program codes. The one or more memories and the computer program codes may be configured to, with the one or more processors, cause the apparatus at least to perform any step of the method according to the twenty-first aspect of the present disclosure.

According to a twenty-third aspect of the present disclosure, there is provided a computer-readable medium having computer program codes embodied thereon which, when executed on a computer, cause the computer to perform any step of the method according to the twenty-first aspect of the present disclosure.

According to a twenty-fourth aspect of the present disclosure, there is provided an apparatus which may be implemented as a second terminal device. The apparatus may comprise a generating unit and a transmitting unit. In accordance with some exemplary embodiments, the generating unit may be operable to carry out at least the generating step of the method according to the twenty-first aspect of the present disclosure. The transmitting unit may be operable to carry out at least the transmitting step of the method according to the twenty-first aspect of the present disclosure.

According to a twenty-fifth aspect of the present disclosure, there is provided a method performed by a first terminal device. The method comprises: determining an amount of SL CSI reports and/or inter-UE coordination information included in a message to be transmitted towards a set of terminal devices. In accordance with an exemplary embodiment, the method further comprises: transmitting a scheduling request (SR) to a network node. The SR indicates the amount of the SL CSI reports and/or the inter-UE coordination information.

In accordance with an exemplary embodiment, the amount of the SL CSI reports and/or the inter-UE coordination information may be indicated by the SR in one or more of the following ways:

· the SR being associated with a SR configuration which corresponds to the amount of the SL CSI reports and/or the inter-UE coordination information; and

· one or more bits in the SR being set to represent a value which corresponds to the amount of the SL CSI reports and/or the inter-UE coordination information.

In accordance with an exemplary embodiment, the method according to the twenty-fifth aspect of the present disclosure may further comprise: receiving a grant from the network node. The grant may indicate resource allocation (RA) to the first terminal device for transmitting the SL CSI reports and/or the inter-UE coordination information towards the set of terminal devices.

According to a twenty-sixth aspect of the present disclosure, there is provided an apparatus which may be implemented as a first terminal device. The apparatus may comprise one or more processors and one or more memories storing computer program codes. The one or more memories and the computer program codes may be configured to, with the one or more processors, cause the apparatus at least to perform any step of the method according to the twenty-fifth aspect of the present disclosure.

According to a twenty-seventh aspect of the present disclosure, there is provided a computer-readable medium having computer program codes embodied thereon which, when executed on a computer, cause the computer to perform any step of the method according to the twenty-fifth aspect of the present disclosure.

According to a twenty-eighth aspect of the present disclosure, there is provided an apparatus which may be implemented as a first terminal device. The apparatus may comprise a determining unit and a transmitting unit. In accordance with some exemplary embodiments, the determining unit may be operable to carry out at least the determining step of the method according to the twenty-fifth aspect of the present disclosure. The transmitting unit may be operable to carry out at least the transmitting step of the method according to the twenty-fifth aspect of the present disclosure.

According to a twenty-ninth aspect of the present disclosure, there is provided a method performed by a network node. The method comprises: receiving an SR from a first terminal device. The SR indicates an amount of SL CSI reports and/or inter-UE coordination information included in a message to be transmitted by the first terminal device towards a set of terminal devices. In accordance with an exemplary embodiment, the method further comprises: determining, according to the SR, RA to the first terminal device for transmitting the SL CSI reports and/or the inter-UE coordination information towards the set of terminal devices.

In accordance with an exemplary embodiment, the SR may be associated with a SR configuration which corresponds to the amount of the SL CSI reports and/or the inter-UE coordination information. Alternatively or additionally, one or more bits in the SR may be set to represent a value which corresponds to the amount of the SL CSI reports and/or the inter-UE coordination information.

In accordance with an exemplary embodiment, the method according to the twenty-ninth aspect of the present disclosure may further comprise: transmitting a grant to the first terminal device. The grant may indicate the RA to the first terminal device for transmitting the SL CSI reports and/or the inter-UE coordination information towards the set of terminal devices.

According to a thirtieth aspect of the present disclosure, there is provided an apparatus which may be implemented as a network node. The apparatus may comprise one or more processors and one or more memories storing computer program codes. The one or more memories and the computer program codes may be configured to, with the one or more processors, cause the apparatus at least to perform any step of the method according to the twenty-ninth aspect of the present disclosure.

According to a thirty-first aspect of the present disclosure, there is provided a computer-readable medium having computer program codes embodied thereon which, when executed on a computer, cause the computer to perform any step of the method according to the twenty-ninth aspect of the present disclosure.

According to a thirty-second aspect of the present disclosure, there is provided an apparatus which may be implemented as a network node. The apparatus may comprise a receiving unit and a determining unit. In accordance with some exemplary embodiments, the receiving unit may be operable to carry out at least the receiving step of the method according to the twenty-ninth aspect of the present disclosure. The determining unit may be operable to carry out at least the determining step of the method according to the twenty-ninth aspect of the present disclosure.

According to a thirty-third aspect of the present disclosure, there is provided a method implemented in a communication system which may include a host computer, a base station and a UE. The method may comprise providing user data at the host computer. Optionally, the method may comprise, at the host computer, initiating a transmission carrying the user data to the UE via a cellular network comprising the base station which may perform any step of the method according to the twenty-ninth aspect of the present disclosure.

According to a thirty-fourth aspect of the present disclosure, there is provided a communication system including a host computer. The host computer may comprise processing circuitry configured to provide user data, and a communication interface configured to forward the user data to a cellular network for transmission to a UE. The cellular network may comprise a base station having a radio interface and processing circuitry. The base station’s processing circuitry may be configured to perform any step of the method according to the twenty-ninth aspect of the present disclosure.

According to a thirty-fifth aspect of the present disclosure, there is provided a method implemented in a communication system which may include a host computer, a base station and a UE. The method may comprise providing user data at the host computer. Optionally, the method may comprise, at the host computer, initiating a transmission carrying the user data to the UE via a cellular network comprising the base station. The UE may perform any step of the method according to the first, fifth, ninth, thirteenth, seventeenth, twenty-first or twenty-fifth aspect of the present disclosure.

According to a thirty-sixth aspect of the present disclosure, there is provided a communication system including a host computer. The host computer may comprise processing circuitry configured to provide user data, and a communication interface configured to forward user data to a cellular network for transmission to a UE. The UE may comprise a radio interface and processing circuitry. The UE’s processing circuitry may be configured to perform any step of the method according to the first, fifth, ninth, thirteenth, seventeenth, twenty-first or twenty-fifth aspect of the present disclosure.

According to a thirty-seventh aspect of the present disclosure, there is provided a method implemented in a communication system which may include a host computer, a base station and a UE. The method may comprise, at the host computer, receiving user data transmitted to the base station from the UE which may perform any step of the method according to the first, fifth, ninth, thirteenth, seventeenth, twenty-first or twenty-fifth aspect of the present disclosure.

According to a thirty-eighth aspect of the present disclosure, there is provided a communication system including a host computer. The host computer may comprise a communication interface configured to receive user data originating from a transmission from a UE to a base station. The UE may comprise a radio interface and processing circuitry. The UE’s processing circuitry may be configured to perform any step of the method according to the first, fifth, ninth, thirteenth, seventeenth, twenty-first or twenty-fifth aspect of the present disclosure.

According to a thirty-ninth aspect of the present disclosure, there is provided a method implemented in a communication system which may include a host computer, a base station and a UE. The method may comprise, at the host computer, receiving, from the base station, user data originating from a transmission which the base station has received from the UE. The base station may perform any step of the method according to the twenty-ninth aspect of the present disclosure.

According to a fortieth aspect of the present disclosure, there is provided a communication system which may include a host computer. The host computer may comprise a communication interface configured to receive user data originating from a transmission from a UE to a base station. The base station may comprise a radio interface and processing circuitry. The base station’s processing circuitry may be configured to perform any step of the method according to the twenty-ninth aspect of the present disclosure.

According to various exemplary embodiments, SL CSI and/or inter-UE coordination information request (s) /report (s) may be communicated between UEs with reduced negative impact of LBT failures. This can enable a UE to transmit SL data efficiently without performing too many LBT operations and/or unnecessary deletion of SL information, improving resource utilization and enhancing service performance.

BRIEF DESCRIPTION OF THE DRAWINGS

The disclosure itself, the preferable mode of use and further objectives are best understood by reference to the following detailed description of the embodiments when read in conjunction with the accompanying drawings, in which:

Fig. 1A-1B are flowcharts illustrating methods according to some embodiments of the present disclosure;

Fig. 2A-2B are flowcharts illustrating methods according to some embodiments of the present disclosure;

Fig. 3A-3B are flowcharts illustrating methods according to some embodiments of the present disclosure;

Fig. 4A-4B are flowcharts illustrating methods according to some embodiments of the present disclosure;

Fig. 5 is a block diagram illustrating an apparatus according to an embodiment of the present disclosure;

Figs. 6A-6H are block diagrams illustrating various apparatuses according to some embodiments of the present disclosure;

Fig. 7 is a block diagram illustrating a telecommunication network connected via an intermediate network to a host computer in accordance with some embodiments of the present disclosure;

Fig. 8 is a block diagram illustrating a host computer communicating via a base station with a UE over a partially wireless connection in accordance with some embodiments of the present disclosure;

Fig. 9 is a flowchart illustrating a method implemented in a communication system, in accordance with an embodiment of the present disclosure;

Fig. 10 is a flowchart illustrating a method implemented in a communication system, in accordance with an embodiment of the present disclosure;

Fig. 11 is a flowchart illustrating a method implemented in a communication system, in accordance with an embodiment of the present disclosure; and

Fig. 12 is a flowchart illustrating a method implemented in a communication system, in accordance with an embodiment of the present disclosure.

DETAILED DESCRIPTION

The embodiments of the present disclosure are described in detail with reference to the accompanying drawings. It should be understood that these embodiments are discussed only for the purpose of enabling those skilled persons in the art to better understand and thus implement the present disclosure, rather than suggesting any limitations on the scope of the present disclosure. Reference throughout this specification to features, advantages, or similar language does not imply that all of the features and advantages that may be realized with the present disclosure should be or are in any single embodiment of the disclosure. Rather, language referring to the features and advantages is understood to mean that a specific feature, advantage, or characteristic described in connection with an embodiment is included in at least one embodiment of the present disclosure. Furthermore, the described features, advantages, and characteristics of the disclosure may be combined in any suitable manner in one or more embodiments. One skilled in the relevant art will recognize that the disclosure may be practiced without one or more of the specific features or advantages of a particular embodiment. In other instances, additional features and advantages may be recognized in certain embodiments that may not be present in all embodiments of the disclosure.

As used herein, the term “communication network” refers to a network following any suitable communication standards, such as new radio (NR) , long term evolution (LTE) , LTE-Advanced, wideband code division multiple access (WCDMA) , high-speed packet access (HSPA) , and so on. Furthermore, the communications between a terminal device and a network node in the communication network may be performed according to any suitable generation communication protocols, including, but not limited to, the first generation (1G) , the second generation (2G) , 2.5G, 2.75G, the third generation (3G) , 4G, 4.5G, 5G communication protocols, and/or any other protocols either currently known or to be developed in the future.

The term “network node” refers to a network device in a communication network via which a terminal device accesses to the network and receives services therefrom. The network node may refer to a base station (BS) , an access point (AP) , a multi-cell/multicast coordination entity (MCE) , a controller or any other suitable device in a wireless communication network. The BS may be, for example, a node B (NodeB or NB) , an evolved NodeB (eNodeB or eNB) , a next generation NodeB (gNodeB or gNB) , a remote radio unit (RRU) , a radio header (RH) , a remote radio head (RRH) , a relay, a low power node such as a femto, a pico, and so forth.

Yet further examples of the network node comprise multi-standard radio (MSR) radio equipment such as MSR BSs, network controllers such as radio network controllers (RNCs) or base station controllers (BSCs) , base transceiver stations (BTSs) , transmission points, transmission nodes, positioning nodes and/or the like. More generally, however, the network node may represent any suitable device (or group of devices) capable, configured, arranged, and/or operable to enable and/or provide a terminal device access to a wireless communication network or to provide some service to a terminal device that has accessed to the wireless communication network.

The term “terminal device” refers to any end device that can access a communication network and receive services therefrom. By way of example and not limitation, the terminal device may refer to a mobile terminal, a user equipment (UE) , or other suitable devices. The UE may be, for example, a subscriber station, a portable subscriber station, a mobile station (MS) or an access terminal (AT) . The terminal device may include, but not limited to, portable computers, image capture terminal devices such as digital cameras, gaming terminal devices, music storage and playback appliances, a mobile phone, a cellular phone, a smart phone, a tablet, a wearable device, a personal digital assistant (PDA) , a vehicle, and the like.

As yet another specific example, in an Internet of things (IoT) scenario, a terminal device may also be called an IoT device and represent a machine or other device that performs monitoring, sensing and/or measurements etc., and transmits the results of such monitoring, sensing and/or measurements etc. to another terminal device and/or a network equipment. The terminal device may in this case be a machine-to-machine (M2M) device, which may in a 3rd generation partnership project (3GPP) context be referred to as a machine-type communication (MTC) device.

As one particular example, the terminal device may be a UE implementing the 3GPP narrow band Internet of things (NB-IoT) standard. Particular examples of such machines or devices are sensors, metering devices such as power meters, industrial machinery, or home or personal appliances, e.g., refrigerators, televisions, personal wearables such as watches etc. In other scenarios, a terminal device may represent a vehicle or other equipment, for example, a medical instrument that is capable of monitoring, sensing and/or reporting etc. on its operational status or other functions associated with its operation.

As used herein, the terms “first” , “second” and so forth refer to different elements. The singular forms “a” and “an” are intended to include the plural forms as well, unless the context clearly indicates otherwise. The terms “comprises” , “comprising” , “has” , “having” , “includes” and/or “including” as used herein, specify the presence of stated features, elements, and/or components and the like, but do not preclude the presence or addition of one or more other features, elements, components and/or combinations thereof. The term “based on” is to be read as “based at least in part 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” . Other definitions, explicit and implicit, may be included below.

Wireless communication networks are widely deployed to provide various telecommunication services such as voice, video, data, messaging and broadcasts. To meet dramatically increasing network requirements on traffic capacity and data rates, one interesting option for communication technique development is to allow D2D communications to be implemented in a wireless communication network such as 4G/LTE or 5G/NR network. As used herein, D2D may be referred to in a broader sense to include communications between any types of UEs, and include V2X communications between a vehicle UE and any other type of UE. D2D and/or V2X may be a component of many existing wireless technologies when it comes to direct communication between wireless devices. D2D and/or V2X communications as an underlay to cellular networks may be proposed as an approach to take advantage of the proximity of devices.

In order to tackle with the ever-increasing data demanding, NR may be supported on both licensed and unlicensed spectrums (i.e., referred to as NR-U) . Compared to the LTE license assisted access (LAA) , NR-U may support dual connectivity (DC) and standalone scenarios, where the medium access control (MAC) procedures including random access channel (RACH) and scheduling procedures on the unlicensed spectrum are subject to the LBT failures, while there is no such restriction in LTE LAA, since there is the licensed spectrum in LAA scenario so the RACH and scheduling related signaling can be transmitted on the licensed spectrum instead of the unlicensed spectrum.

Access to a channel in the unlicensed spectrum, especially in the 5 GHz and 6 GHz bands, may be guaranteed by LBT requirements defined by regulations, unlike the licensed spectrum which is assigned to a specific operator.

The LBT mechanism mandates a device to sense for the presence of other users’ transmissions in the channel before attempting to transmit. The device may perform clear channel assessment (CCA) checks on the channel using energy detection (ED) before transmitting. If the channel is found to be idle, i.e., energy detected is below a certain threshold, the device may be allowed to transmit. Otherwise, if the channel is found to be occupied (i.e., LBT is failed) , the device may have to defer from transmitting. This mechanism reduces interferences and collisions to other systems and increases probabilities of successful transmissions. After sensing the medium to be idle, the node is typically allowed to transmit for a certain amount of time, sometimes referred to as transmission opportunity (TXOP) . The length of the TXOP depends on the regulation and type of CCA that has been performed, but typically ranges from 1ms to 10ms. This duration is often referred to as a channel occupancy time (COT) .

NR-U may support two different LBT modes, dynamic and semi-static channel occupancy for two types of equipment, i.e., load based equipment (LBE) and frame based equipment (FBE) , respectively.

3GPP specified the LTE D2D technology, also known as SL or the PC5 interface, as part of Release 12 (Rel-12) . The target use case was the proximity services (communication and discovery) . Support was enhanced during Rel-13. In Rel-14, the LTE SL was extensively redesigned to support vehicular communications (commonly referred to as V2X or V2V) . Support was again enhanced during Rel-15. From the point of view of the lowest radio layers, the LTE SL uses broadcast communication. That is, transmission from a UE targets any receiver that is in range.

In Rel-16, 3GPP introduced SL for the 5G NR. The driving use case was vehicular communications with more stringent requirements than those typically served using the LTE SL. To meet these requirements, the NR SL is capable of broadcast, groupcast, and unicast communications. In groupcast communication, the intended receivers of a message are typically a subset of the vehicles near the transmitter, whereas in unicast communication, there is a single intended receiver. Hybrid automatic repeat request (HARQ) feedback based retransmission is supported for unicast and groupcast.

NR SL introduces 2 stage SCI, the 1st stage SCI is transmitted on physical sidelink control channel (PSCCH) and used for the scheduling of physical sidelink shared channel (PSSCH) and 2nd stage SCI on PSSCH. PSCCH carrying the 1st stage SCI and the PSSCH scheduled by the 1st stage SCI are transmitted in the same slot but in different symbols.

For unicast, an SL CSI report is introduced. So far only the aperiodic SL CSI report is supported, i.e., a UE only transmits an SL CSI report to a peer UE if SL CSI reporting is enabled for the UE and the peer UE has requested the SL CSI report from the UE (i.e., has set the “CSI request” field to 1 in the 2nd stage SCI targeting the UE) . Besides, the CSI requesting UE may inform the latency bound of the SL CSI report to the CSI reporting UE via PC5-RRC, and the CSI reporting UE may cancel a triggered SL CSI report if it may not be sent within the latency bound. The CSI requesting UE may determine the latency bound by its implementation.

NR sidelink transmissions may have the following two modes of resource allocations:

· Mode 1: Sidelink resources are scheduled by the gNB.

· Mode 2: The UE autonomously selects sidelink resources from a (pre-) configured sidelink resource pool (s) based on the channel sensing mechanism.

For RRC CONNECTED UE, a gNB may be configured to adopt either Mode 1 or Mode 2 resource allocation (RA) . In other cases, only Mode 2 can be adopted. Furthermore, an RRC CONNECTED Mode 2 UE may use dedicated TX resource pool configured by the gNB using dedicated RRC signaling, an RRC IDLE/INACTIVE Mode 2 UE may select a common TX resource pool to use from the set of common TX resource pools configured by the gNB using common RRC signaling, and an out of coverage Mode 2 UE may select a common TX resource pool to use from the set of preconfigured common TX resource pools.

Inter-UE coordination is introduced in 3GPP Rel-17 to enhance Mode 2 RA for improved reliability and reduced latency, i.e., a set of resources is determined at UE-A, this set is sent to UE-B which adopts Mode 2 RA, and UE-B takes this into account in the resource selection for its own transmission.

The following two inter-UE coordination schemes may be supported:

· Inter-UE Coordination Scheme 1: the coordination information sent from UE-A to UE-B is the set of resources preferred and/or non-preferred for UE-B’s transmission.

· Inter-UE Coordination Scheme 2: the coordination information sent from UE-A to UE-B is the presence of expected/potential and/or detected resource conflict on the resources indicated by UE-B’s SCI.

A UE that sends an explicit request for inter-UE coordination information may be UE-B. A UE that received an explicit request from UE-B and sends inter-UE coordination information to UE-B may be UE-A. Besides, a UE may act as UE-A and send inter-UE coordination information to another UE (i.e., UE-B) when certain conditions are met based on which it can determine whether a certain set of resources are preferred and/or non-preferred for the other UE’s transmission or whether there is a resource conflict on the resources indicated by the other UE’s SCI.

For Scheme 1, the inter-UE coordination request and the inter-UE coordination information may be sent in the 2nd stage SCI (SCI format 2-C) and/or MAC CE. Similar as for SL CSI reporting, a latency bound restriction may be applied for the request based inter-UE coordination information transmission. The inter-UE coordination requesting UE may inform the latency bound to the inter-UE coordination information reporting UE via PC5-RRC, and the inter-UE coordination information reporting UE may cancel a triggered inter-UE coordination information report if it may not be sent within the latency bound. The inter-UE coordination requesting UE may determine the latency bound by its implementation.

Besides, at least the following parameters may be provided by UE-B’s inter-UE coordination request, which may be used by UE-A to determine the set of resources preferred and/or non-preferred for UE-B’s transmission:

· Priority value to be used for UE-B’s PSCCH/PSSCH transmission;

· Number of sub-channels to be used for UE-B’s PSSCH/PSCCH transmission in a slot; and

· Resource reservation interval for UE-B’s PSSCH/PSCCH transmission.

In case the inter-UE coordination information is triggered by conditions, the above parameters may be (pre) configured for a resource pool or determined by UE-Aby its implementation.

For Scheme 2, physical sidelink feedback channel (PSFCH) (format 0) may be used to convey the presence of expected/potential/detected resource conflict.

In 3GPP Rel-18, a work item (WI) on sidelink enhancement is approved, and one of the objectives is to study and specify support of sidelink on unlicensed spectrum.

In unlicensed band, a UE may need to perform an LBT operation prior to any SL transmission, when the LBT operation is failed for a channel, the channel may not be accessed and the transmission may not be made. This may lead to a large delay in sending a SL CSI report/request and/or inter-UE coordination information/request, and it could happen that the SL CSI report and/or the inter-UE coordination information become out of dated and are cancelled due to the latency bound is exceeded. The problem may be more critical if the UE needs to send its SL CSI report/request and/or inter-UE coordination information/request to multiple UEs as currently the SL CSI report/request and/or the inter-UE coordination information/request need to be sent to each UE individually and it may be more difficult to have the signaling sent (timely) to all the UEs.

Therefore, it may be desirable to study the above issues and develop solutions addressing at least one of the issues.

Various exemplary embodiments of the present disclosure propose solutions to transmit an SL CSI report/request and/or inter-UE coordination information/request more timely and reduce the probability that the SL CSI/report and/or the inter-UE coordination information is cancelled due to the latency bound is exceeded, e.g., at the presence of LBT failure in SL unlicensed band.

In accordance with exemplary embodiments in a first aspect of the solutions, a UE may send its experienced SL congestion to another UE, based on which the other UE may adjust the latency bound used in determining whether or not to cancel a triggered SL CSI report and/or inter-UE coordination information. Alternatively or additionally, the UE may adjust the latency bound by itself based on its experienced SL congestion, and indicate the adjusted latency bound to the other UE.

In accordance with exemplary embodiments in a second aspect of the solutions, multiple SL CSI reports and/or inter-UE coordination information to different UEs may be aggregated into one message. In this case, different signaling alternatives may be used to indicate the target UEs of the aggregated SL CSI reports and/or inter-UE coordination information.

In accordance with exemplary embodiments in a third aspect of the solutions, a single SL CSI request and/or inter-UE coordination request may be transmitted to multiple peer UEs at the same time. It can be appreciated that various signaling alternatives may be used to indicate the target UEs of the SL CSI request and/or inter-UE coordination request.

In accordance with exemplary embodiments in a fourth aspect of the solutions, a UE may indicate, to a gNB by e.g., using the corresponding SR configuration for proper Mode 1 RA, the number of SL CSI reports and/or the amount of inter-UE coordination information transmitted at one time.

It can be appreciated that various exemplary embodiments in different aspects of the solutions as described in the present disclosure may be combined in any suitable manner. For example, a UE for which the latency bound can be adjusted according to its experienced SL congestion may aggregate multiple SL CSI reports and/or inter-UE coordination information intended to different UEs in one message, and optionally indicate the amount of the aggregated SL CSI reports and/or inter-UE coordination information to a gNB via an SR to obtain a proper RA for transmission of the SL CSI reports and/or the inter-UE coordination information. Alternatively or additionally, the UE may also receive an SL CSI request and/or an inter-UE coordination request which are transmitted to multiple UEs by a peer UE at the same time.

Many advantages may be achieved by applying the proposed solutions. For example, it may be feasible for a UE to transmit an SL CSI report/request and/or inter-UE coordination information/request in a more timely and efficient manner, and the radio resource utilization may be improved by mitigating negative impact of LBT failures. In addition, quality of service (QoS) satisfaction of services may be improved since the UE can perform SL transmissions more efficiently.

It can be appreciated that although some exemplary embodiments are described in the context of NR SL communications in an unlicensed carrier, the same principle may be applied to any kind of direct communications between UEs involving D2D communications such as LTE SL in an unlicensed carrier. The unlicensed SL carrier may be in any unlicensed band, e.g., 2.5GHz, 5GHz, 6GHz, frequency range 1 (FR1) , FR2, 52.6GHz-71GHz, or beyond 100GHz. Embodiments are described from a transmitting (TX) UE and receiving (RX) UE point of view. Further, it is assumed that a SL UE and its serving gNB (if the UE is in network coverage) operates with the same radio access technology (RAT) , e.g., NR, LTE, and so on. However, all the embodiments may be applicable without loss of meaning to any combination of RATs between the SL UE and its serving gNB.

It also can be appreciated that the term LBT may be interchangeably called as CCA, shared spectrum access procedure, etc. The carrier on which the LBT is applied may belong to a shared spectrum or an unlicensed band or a band with contention based access, etc. Various exemplary embodiments described in the present disclosure may also be applicable to direct communication in a licensed carrier.

In various exemplary embodiments, UE-1 may refer to the UE sending an SL CSI report and/or inter-UE coordination information (IUC) while receiving an SL CSI request and/or an inter-UE coordination request, and UE-2 may refer to the UE sending an SL CSI request and/or an inter-UE coordination request while receiving an SL CSI report and/or inter-UE coordination information.

In accordance with an exemplary embodiment, UE-1 may send the status of its experienced SL congestion to UE-2 over SL, where the SL congestion may be expressed in terms of channel busy ratio (CBR) , channel occupation ratio, LBT failure ratio, etc. The UE may send the congestion status in any cast type, e.g., unicast or groupcast or broadcast. In an embodiment, the congestion status may be sent in any of the following manners:

· Periodically;

· Requested by UE-2;

· Requested by the gNB; and/or

· Certain conditions are met, e.g., the experienced SL congestion becomes higher than a (pre) configured threshold or lower than a (pre) configured threshold, or the change in the congestion level exceeds a certain range.

In accordance with an exemplary embodiment, based on one or multiple received SL congestion status from UE-1, UE-2 may adjust the latency bound used by UE-1 in determining whether or not to cancel a triggered SL CSI report and/or inter-UE coordination information. For example, the latency bound may be increased if the received congestion level is high (by this UE-1 would not cancel the triggered CSI report and/or inter-UE coordination information unnecessarily if there is still time allowed for UE-1 to try more LBT operation attempts) , otherwise the latency bound may be decreased if the received congestion level is medium or low.

According to an embodiment, either common or separate latency bounds may be adopted for the SL CSI report and the inter-UE coordination information. According to another embodiment, for the same SL congestion level/SL congestion status, the increase/decrease in the latency bound for the SL CSI report and the inter-UE coordination information may be either different or the same. In a further embodiment, increase in the latency bound may be limited by an upper bound, which may correspond to a maximum allowed latency. If the latency in transmitting the SL CSI report and inter-UE coordination information is more than that maximum latency bound, the report/information becomes too old and is not useful anymore.

When SL is operated in unlicensed band, PSFCH transmission may also be blocked in case of LBT failure, therefore a similar latency bound may also be introduced for inter-UE coordination Scheme 2 and adjusted as described above.

In accordance with an exemplary embodiment, UE-2 may inform the (adjusted) latency bound to UE-1 in any of the following signaling alternatives:

· In PC5-RRC signaling;

· In an SL MAC CE, e.g., either adding the latency bound information in an SL CSI request and/or inter-UE coordination request MAC CE or using a new MAC CE;

· In L1 signaling such as (2nd stage) SCI, e.g., either in an existing (2nd stage) SCI format or using a new SCI format; and

· In both PC5-RRC signaling and an SL MAC CE or L1 signaling such as (2nd stage) SCI, e.g., indicating in PC5-RRC signaling a set of latency bounds while indicating in an SL MAC CE or L1 signaling the actually applied latency bound at present, which may be an index to the set of latency bounds informed by PC5-RRC signaling.

In accordance with an exemplary embodiment, UE-1 may adjust the latency bound for an SL CSI report and/or inter-UE coordination information by itself based on the measured SL congestion status/congestion level. After that, UE-1 may indicate the adjusted latency bound to UE-2 via any of the signaling alternatives as described above.

In accordance with an exemplary embodiment, UE-1 may transmit SL CSI reports and/or inter-UE coordination information to multiple UEs at the same time. In other words, UE-1 can aggregate multiple SL CSI reports and/or inter-UE coordination information into one message, by this less transmission opportunities may be required and it is more likely to have SL CSI reports and/or inter-UE coordination information transmitted with the same latency bound at the presence of LBT failure. Such kind of transmission to multiple UEs may be implemented in variously different ways:

· Aggregate multiple SL CSI report and/or inter-UE coordination information MAC CEs in one MAC PDU.

· Aggregate multiple SL CSI reports for multiple UEs in one MAC CE. This may require an additional MAC CE format to be defined. For example, an additional MAC CE format may be defined as an aggregated SL CSI report MAC CE, which is able to carry SL CSI reports for N target UEs in the same MAC CE.

· Aggregate inter-UE coordination information for multiple UEs in one L1 signaling message such as (2nd stage) SCI (e.g., a new (2nd stage) SCI format may be defined for this) and/or one MAC CE (e.g., a new MAC CE format which is able to carry inter-UE coordination information for N target UEs in the same MAC CE may be defined for this) .

Regarding setting of the parameter “N” , in an embodiment, N is a semi-static value, which may be predefined or configured to UE-1. In another embodiment, N is a fixed value predefined in specification in a hard coded fashion. In a further example, N may be implicitly indicated by e.g., a length field in the MAC subheader of the MAC CE. The length field can indicate the size of the MAC CE, and based on the size, UE-2 can deduce the actual value of N.

In accordance with an exemplary embodiment, only the same type of information/reports may be aggregated, e.g., CSI reports may not be aggregated with inter-UE coordination information in one MAC CE and/or L1 signaling. In another embodiment, different types of information/reports may be aggregated, e.g., CSI reports may be aggregated with inter-UE coordination information in one MAC CE and/or L1 signaling.

In accordance with an exemplary embodiment, UE-1 may determine, based on one or more of the following conditions, a set of UEs towards which SL CSI reports and/or inter-UE coordination information is sent by UE-1 at the same time:

· The UEs which have sent SL CSI requests and/or inter-UE coordination requests to UE-1 and the associated latency bounds are not exceeded yet.

· The parameters/contents included in the requests (e.g., priority, the number of sub-channels, resource reservation interval, etc. ) have similar or same values.

· The parameters/contents in the SL CSI reports and/or inter-UE coordination information have similar or same values.

· Data and/or services which are carried on the SL connections towards the set of UEs are same or similar in terms of e.g., QoS requirements.

In accordance with an exemplary embodiment, for a SL CSI report and/or inter-UE coordination information sent by UE-1, the targeted peer UEs (e.g., which UEs need to receive/decode the SL CSI report and/or the inter-UE coordination information) may be indicated in any one or more of the following signaling alternatives:

· Indicate the set of UE IDs in L1 signaling such as (2nd stage) SCI (e.g., a new (2nd stage) SCI format may be defined for this) .

· Indicate the set of UE IDs in a MAC subheader.

· Indicate the set of UE IDs in the MAC CE carrying the SL CSI report and/or the MAC CE carrying the inter-UE coordination information.

· Indicate the set of UE IDs in PC5-RRC signaling.

In accordance with an exemplary embodiment, for any UE ID indicated in any one of the above signaling alternatives, the UE ID may be a Layer 2 (L2) ID or a local ID converted from the L2 ID.

In accordance with an exemplary embodiment, instead of transmitting separate SL CSI requests or inter-UE coordination requests to different peer UEs, UE-2 may transmit a single SL CSI request and/or inter-UE coordination request to multiple peer UEs at the same time. By doing this, UE-2 can avoid initiating separate LBT operations for multiple requests, and thus negative impact of LBT failures on transmission of a request message can be minimized.

In accordance with an exemplary embodiment, the targeted peer UEs for a request message may be indicated by UE-2 in an explicit fashion or an implicit fashion.

In case of explicit indication, the targeted peer UEs may be indicated in one or more of the following signaling alternatives by UE-2:

· Indicate the set of UE IDs in a MAC subheader.

· Indicate the set of UE IDs in the MAC CE carrying the SL CSI request and/or the MAC CE carrying the inter-UE coordination request.

· Indicate the set of UE IDs in PC5-RRC signaling.

In accordance with an exemplary embodiment, for any UE ID indicated in any one of the above signaling alternatives, the UE ID may be a L2 ID or a local ID converted from the L2 ID.

In case of implicit indication, there may be several alternatives to indicate the targeted peer UEs for a request message by UE-2. In an embodiment, one or more bits in L1 signaling and/or a MAC subheader and/or a MAC CE may be used to indicate whether all UEs receiving a SL CSI request from UE-2 and having unicast connections to UE-2 need to send the requested SL CSI report to UE-2, and whether all UEs receiving an inter-UE coordination request from UE-2 (and receiving transmission from UE-2) need to send the requested inter-UE coordination information to UE-2.

In another embodiment, a special L2 ID may be (pre) configured to the UEs or configured and informed by a gNB or configured by UE-1 and informed to UE-2. A UE (pre) configured with such special L2 ID may act as UE-1 and/or UE-2. Such special L2 ID may be defined to represent a group of UEs where:

· Each UE in the group may operate as UE-1 to receive a request (e.g., an SL CSI request and/or an inter-UE coordination request) containing the special L2 ID from any other UE in the group, and provide the requested report/information (e.g., an SL CSI report and/or inter-UE coordination information) to the UE (s) which have sent the request.

· Each UE in the group may operate as UE-2 to send a request (e.g., an SL CSI request or an inter-UE coordination request) to the group by including the special L2 ID in the request. Any other UE in the group which receives the request may behave as UE-1 as described above.

In accordance with an exemplary embodiment, the special L2 ID may be indicated by a UE to another UE in one or more of the following ways:

· Indicate the special L2 ID in L1 signaling such as (2nd stage) SCI and/or a MAC subheader and/or a MAC CE.

· Indicate (using e.g., one or more bits) in L1 signaling such as (2nd stage) SCI and/or a MAC subheader and/or a MAC CE whether the SL CSI request and/or the inter-UE coordination request is associated to the (pre) configured special L2 ID.

In accordance with an exemplary embodiment, multiple special L2 IDs may be introduced and a UE may be (pre) configured with one or more than one of such special L2 IDs. In this case, the UE may send an SL CSI report and/or inter-UE coordination information to another UE if it has received from that other UE an SL CSI request and/or an inter-UE coordination request and also at least one special L2 ID which matches the ID (s) (pre) configured to the UE. In an embodiment, that other UE may indicate the special L2 ID (s) explicitly or using e.g., a bitmap in L1 signaling such as (2nd stage) SCI and/or a MAC subheader and/or a MAC CE.

In accordance with an exemplary embodiment, different SR configurations and/or one or more additional bits in an SR may be used to indicate different amount of SL CSI reports and/or inter-UE coordination information transmitted at one time. In case UE-1 adopting Mode 1 RA, it may indicate the amount of SL CSI reports and/or inter-UE coordination information transmitted at one time to a gNB, e.g., by using the corresponding SR configuration or setting one or more bits in the SR to the corresponding value. In this way, the gNB may understand/determine the amount of resource required to transmit the SL CSI reports and/or the inter-UE coordination information and can provide UE-1 with a proper grant correspondingly.

For various exemplary embodiments, any signaling exchanged between a UE and a gNB via Uu interface may be transmitted via at least one of the following alternatives:

· RRC signaling;

· MAC CE;

· Paging message;

· Control PDU of a protocol layer (e.g., service data adaptation protocol (SDAP) , packet data convergence protocol (PDCP) , radio link control (RLC) , or an adaptation layer in case of SL relay, etc. ) ; and

· L1 signaling on channels such as physical random access channel (PRACH) , physical uplink control channel (PUCCH) , physical downlink control channel (PDCCH) , etc.

For various exemplary embodiments, any signaling exchanged between UEs via the PC5 interface may be transmitted via at least one of the following signaling alternatives:

· RRC signaling (e.g., PC5-RRC signaling, etc. ) ;

· PC5-Ssignaling;

· Discovery signaling;

· MAC CE;

· Control PDU of a protocol layer (e.g., SDAP, PDCP, RLC, or an adaptation layer in case of SL relay, etc. ) ; and

· L1 signaling on channels such as PSSCH, PSCCH, or PSFCH, etc.

It is noted that some embodiments of the present disclosure are mainly described in relation to 4G/LTE or 5G/NR specifications being used as non-limiting examples for certain exemplary network configurations and system deployments. As such, the description of exemplary embodiments given herein specifically refers to terminology which is directly related thereto. Such terminology is only used in the context of the presented non-limiting examples and embodiments, and does naturally not limit the present disclosure in any way. Rather, any other system configuration or radio technologies may equally be utilized as long as exemplary embodiments described herein are applicable.

Fig. 1A is a flowchart illustrating a method 110 according to some embodiments of the present disclosure. The method 110 illustrated in Fig. 1A may be performed by a first terminal device or an apparatus communicatively coupled to the first terminal device. In accordance with an exemplary embodiment, the first terminal device such as UE-1 may be configured to support D2D communication (e.g., V2X or SL communication, etc. ) with other devices. In an exemplary embodiment, the first terminal device may be configured to communicate with a network node (e.g., a base station such as gNB, etc. ) directly or via a relay.

According to the exemplary method 110 illustrated in Fig. 1A, the first terminal device may determine an SL congestion level of the first terminal device, as shown in block 112. In accordance with an exemplary embodiment, the first terminal device may transmit information related to a latency bound to a second terminal device, as shown in block 114. The latency bound may be based at least in part on the SL congestion level of the first terminal device.

In accordance with an exemplary embodiment, the SL congestion status may be transmitted to the second terminal device by the first terminal device periodically and/or in response to one or more events. In an embodiment, the one or more events may include one or more of:

· the SL congestion level of the first terminal device is lower than a second threshold (which may be the same or different from the first threshold) ; and

In accordance with an exemplary embodiment, the first terminal device may receive a parameter indicating the latency bound from the second terminal device. In this case, the latency bound may be determined by the second terminal device based at least in part on the SL congestion level of the first terminal device.

In accordance with an exemplary embodiment, the parameter indicating the latency bound may be included in PC5-RRC signaling and/or an SL MAC CE and/or L1 signaling.

Fig. 1B is a flowchart illustrating a method 120 according to some embodiments of the present disclosure. The method 120 illustrated in Fig. 1B may be performed by a second terminal device or an apparatus communicatively coupled to the second terminal device. In accordance with an exemplary embodiment, the second terminal device such as UE-2 may be configured to support D2D communication (e.g., V2X or SL communication, etc. ) with other devices. In an exemplary embodiment, the second terminal device may be configured to communicate with a network node (e.g., a base station such as gNB, etc. ) directly or via a relay.

According to the exemplary method 120 illustrated in Fig. 1B, the second terminal device may receive information related to a latency bound from a first terminal device (e.g., the first terminal device as described with respect to Fig. 1A) , as shown in block 122. The latency bound may be based at least in part on an SL congestion level of the first terminal device. In accordance with an exemplary embodiment, the second terminal device may determine the latency bound according to the information related to the latency bound, as shown in block 124.

In accordance with an exemplary embodiment, the information related to the latency bound received by the second terminal device according to the method 120 may correspond to the information related to the latency bound transmitted by the first terminal device according to the method 110. Thus, the information related to the latency bound as described with respect to Fig. 1A and Fig. 1B may have the same or similar contents and/or feature elements.

In accordance with an exemplary embodiment, an SL congestion status which indicates the SL congestion level of the first terminal device and is included in the information related to the latency bound may be received from the first terminal device by the second terminal device periodically and/or in response to one or more events (e.g., the one or more events as described with respect to the method 110 of Fig. 1A) .

In accordance with an exemplary embodiment, the second terminal device may transmit a parameter indicating the latency bound to the first terminal device. In this case, the latency bound may be determined by the second terminal device based at least in part on the SL congestion level of the first terminal device.

Fig. 2A is a flowchart illustrating a method 210 according to some embodiments of the present disclosure. The method 210 illustrated in Fig. 2A may be performed by a first terminal device or an apparatus communicatively coupled to the first terminal device. In accordance with an exemplary embodiment, the first terminal device such as UE-1 may be configured to support D2D communication (e.g., V2X or SL communication, etc. ) with other devices. In an exemplary embodiment, the first terminal device may be configured to communicate with a network node (e.g., a base station such as gNB, etc. ) directly or via a relay.

According to the exemplary method 210 illustrated in Fig. 2A, the first terminal device may generate a message which includes SL CSI reports and/or inter-UE coordination information for a set of terminal devices, as shown in block 212. In accordance with an exemplary embodiment, the first terminal device may transmit the message towards the set of the terminal devices, as shown in block 214.

· a MAC PDU including multiple SL CSI report and/or inter-UE coordination information MAC CEs for the set of the terminal devices;

· L1 signaling;

· a MAC subheader;

· a MAC CE carrying the SL CSI reports for the set of the terminal devices;

· PC5-RRC signaling.

Fig. 2B is a flowchart illustrating a method 220 according to some embodiments of the present disclosure. The method 220 illustrated in Fig. 2B may be performed by a second terminal device or an apparatus communicatively coupled to the second terminal device. In accordance with an exemplary embodiment, the second terminal device such as UE-2 may be configured to support D2D communication (e.g., V2X or SL communication, etc. ) with other devices. In an exemplary embodiment, the second terminal device may be configured to communicate with a network node (e.g., a base station such as gNB, etc. ) directly or via a relay.

According to the exemplary method 220 illustrated in Fig. 2B, the second terminal device may receive a message transmitted by a first terminal device (e.g., the first terminal device as described with respect to Fig. 2A) , as shown in block 222. The message may include SL CSI reports and/or inter-UE coordination information for a set of terminal devices. In accordance with an exemplary embodiment, the second terminal device may decode an SL CSI report and/or inter-UE coordination information provided to the second terminal device by the first terminal device in the message, when the second terminal device belongs to the set of terminal devices, as shown in block 224.

In accordance with an exemplary embodiment, the message received by the second terminal device according to the method 220 may correspond to the message generated and transmitted by the first terminal device according to the method 210. Thus, the message including SL CSI reports and/or inter-UE coordination information for a set of terminal devices as described with respect to Fig. 2A and Fig. 2B may have the same or similar contents and/or feature elements.

In accordance with an exemplary embodiment, the second terminal device may receive the message in a MAC PDU including multiple SL CSI report and/or inter-UE coordination information MAC CEs for the set of the terminal devices. Alternatively or additionally, the second terminal device may receive the message in a MAC CE and/or L1 signaling which include the SL CSI reports and/or the inter-UE coordination information for the set of the terminal devices.

Fig. 3A is a flowchart illustrating a method 310 according to some embodiments of the present disclosure. The method 310 illustrated in Fig. 3A may be performed by a first terminal device or an apparatus communicatively coupled to the first terminal device. In accordance with an exemplary embodiment, the first terminal device such as UE-1 may be configured to support D2D communication (e.g., V2X or SL communication, etc. ) with other devices. In an exemplary embodiment, the first terminal device may be configured to communicate with a network node (e.g., a base station such as gNB, etc. ) directly or via a relay.

According to the exemplary method 310 illustrated in Fig. 3A, the first terminal device may receive a message transmitted by a second terminal device, as shown in block 312. The message may include an SL CSI request and/or an inter-UE coordination request to a set of terminal devices. In accordance with an exemplary embodiment, the first terminal device may determine whether to respond to the SL CSI request and/or the inter-UE coordination request, as shown in block 314.

In accordance with an exemplary embodiment, when the first terminal device belongs to the set of terminal devices, the first terminal device may determine to respond to the SL CSI request and/or the inter-UE coordination request. In this case, the first terminal device may generate an SL CSI report and/or inter-UE coordination information, according to the SL CSI request and/or the inter-UE coordination request. In accordance with an exemplary embodiment, the first terminal device may transmit the SL CSI report and/or the inter-UE coordination information towards the second terminal device.

Fig. 3B is a flowchart illustrating a method 320 according to some embodiments of the present disclosure. The method 320 illustrated in Fig. 3B may be performed by a second terminal device or an apparatus communicatively coupled to the second terminal device. In accordance with an exemplary embodiment, the second terminal device such as UE-2 may be configured to support D2D communication (e.g., V2X or SL communication, etc. ) with other devices. In an exemplary embodiment, the second terminal device may be configured to communicate with a network node (e.g., a base station such as gNB, etc. ) directly or via a relay.

According to the exemplary method 320 illustrated in Fig. 3B, the second terminal device may generate a message which includes an SL CSI request and/or an inter-UE coordination request to a set of terminal devices (e.g., the set of the terminal devices as described with respect to Fig. 3A) , as shown in block 322. In accordance with an exemplary embodiment, the second terminal device may transmit the message towards the set of the terminal devices, as shown in block 324.

In accordance with an exemplary embodiment, the message generated and transmitted by the second terminal device according to the method 320 may correspond to the message received by the first terminal device according to the method 310. Thus, the message including an SL CSI request and/or an inter-UE coordination request to a set of terminal devices as described with respect to Fig. 3A and Fig. 3B may have the same or similar contents and/or feature elements.

In accordance with an exemplary embodiment, the set of the terminal devices may be indicated by one or more identifiers (e.g., one or more bits, one or more group identifiers, and/or any other suitable explicit or implicit indication information) which are included in L1 signaling, and/or a MAC subheader, and/or a MAC CE carrying the SL CSI request and/or the inter-UE coordination request, and/or PC5-RRC signaling.

In accordance with an exemplary embodiment, the second terminal device may be configured with one or multiple group identifiers associated with one or more device groups. In an embodiment, for the one or more device groups, a member in a device group may be allowed to: receive a request (e.g., an SL CSI request and/or an inter-UE coordination request, etc. ) containing a group identifier associated with the device group from another member in the device group, and provide a response to the request to the another member. In another embodiment, the member in the device group may be allowed to transmit a request (e.g., an SL CSI request and/or an inter-UE coordination request, etc. ) to the device group by including the associated group identifier in the request.

Fig. 4A is a flowchart illustrating a method 410 according to some embodiments of the present disclosure. The method 410 illustrated in Fig. 4A may be performed by a first terminal device or an apparatus communicatively coupled to the first terminal device. In accordance with an exemplary embodiment, the first terminal device such as UE-1 may be configured to support D2D communication (e.g., V2X or SL communication, etc. ) with other devices. In an exemplary embodiment, the first terminal device may be configured to communicate with a network node (e.g., a base station such as gNB, etc. ) directly or via a relay.

According to the exemplary method 410 illustrated in Fig. 4A, the first terminal device may determine an amount of SL CSI reports and/or inter-UE coordination information included in a message to be transmitted towards a set of terminal devices (e.g., the set of the terminal devices as described with respect to Fig. 2A) , as shown in block 412. In accordance with an exemplary embodiment, the first terminal device may transmit an SR to a network node, as shown in block 414. The SR may indicate the amount of the SL CSI reports and/or the inter-UE coordination information.

In accordance with an exemplary embodiment, the first terminal device may receive a grant from the network node. The grant may indicate RA to the first terminal device for transmitting the SL CSI reports and/or the inter-UE coordination information towards the set of terminal devices.

Fig. 4B is a flowchart illustrating a method 420 according to some embodiments of the present disclosure. The method 420 illustrated in Fig. 4B may be performed by a network node (e.g., a base station, an AP, etc. ) or an apparatus communicatively coupled to the network node. In accordance with an exemplary embodiment, the network node may be configured to support cellular coverage extension with D2D communication (e.g., V2X or SL communication, etc. ) . For example, the network node may be configured to communicate with a terminal device such as a UE, e.g., directly or via a relay.

According to the exemplary method 420 illustrated in Fig. 4B, the network node may receive an SR from a first terminal device (e.g., the first terminal device as described with respect to Fig. 4A) , as shown in block 422. The SR may indicate an amount of SL CSI reports and/or inter-UE coordination information included in a message to be transmitted by the first terminal device towards a set of terminal devices. In accordance with an exemplary embodiment, the network node may determine, according to the SR, RA to the first terminal device for transmitting the SL CSI reports and/or the inter-UE coordination information towards the set of terminal devices, as shown in block 424.

In accordance with an exemplary embodiment, the network node may transmit a grant to the first terminal device. The grant may indicate the RA to the first terminal device for transmitting the SL CSI reports and/or the inter-UE coordination information towards the set of terminal devices.

It can be appreciated that according to different application scenarios and service requirements, a terminal device (e.g., a UE, a MS, etc. ) may be configured in some cases to act as a first terminal device as described with respect to Fig. 1A, Fig. 2A, Fig. 3A and/or Fig. 4A to perform any one or a combination of the methods 110, 210, 310 and 410, and may also be configured in other cases to act as a second terminal device as described with respect to Fig. 1B, Fig. 2B and/or Fig. 3B to perform any one or a combination of the methods 120, 220 and 320.

The various blocks shown in Figs. 1A-1B, Figs. 2A-2B, Figs. 3A-3B and Figs. 4A-4B may be viewed as method steps, and/or as operations that result from operation of computer program code, and/or as a plurality of coupled logic circuit elements constructed to carry out the associated function (s) . The schematic flow chart diagrams described above are generally set forth as logical flow chart diagrams. As such, the depicted order and labeled steps are indicative of specific embodiments of the presented methods. Other steps and methods may be conceived that are equivalent in function, logic, or effect to one or more steps, or portions thereof, of the illustrated methods. Additionally, the order in which a particular method occurs may or may not strictly adhere to the order of the corresponding steps shown.

Fig. 5 is a block diagram illustrating an apparatus 500 according to various embodiments of the present disclosure. As shown in Fig. 5, the apparatus 500 may comprise one or more processors such as processor 501 and one or more memories such as memory 502 storing computer program codes 503. The memory 502 may be non-transitory machine/processor/computer readable storage medium. In accordance with some exemplary embodiments, the apparatus 500 may be implemented as an integrated circuit chip or module that can be plugged or installed into a first terminal device as described with respect to Fig. 1A/Fig. 2A/Fig. 3A/Fig. 4A, or a second terminal device as described with respect to Fig. 1B/Fig. 2B/Fig. 3B, or a network node as described with respect to Fig. 4B. In such cases, the apparatus 500 may be implemented as a first terminal device as described with respect to Fig. 1A/Fig. 2A/Fig. 3A/Fig. 4A, or a second terminal device as described with respect to Fig. 1B/Fig. 2B/Fig. 3B, or a network node as described with respect to Fig. 4B.

In some implementations, the one or more memories 502 and the computer program codes 503 may be configured to, with the one or more processors 501, cause the apparatus 500 at least to perform any operation of the method as described in connection with Fig. 1A/Fig. 2A/Fig. 3A/Fig. 4A. In other implementations, the one or more memories 502 and the computer program codes 503 may be configured to, with the one or more processors 501, cause the apparatus 500 at least to perform any operation of the method as described in connection with Fig. 1B/Fig. 2B/Fig. 3B. In other implementations, the one or more memories 502 and the computer program codes 503 may be configured to, with the one or more processors 501, cause the apparatus 500 at least to perform any operation of the method as described in connection with Fig. 4B. Alternatively or additionally, the one or more memories 502 and the computer program codes 503 may be configured to, with the one or more processors 501, cause the apparatus 500 at least to perform more or less operations to implement the proposed methods according to the exemplary embodiments of the present disclosure.

Fig. 6A is a block diagram illustrating an apparatus 610 according to some embodiments of the present disclosure. As shown in Fig. 6A, the apparatus 610 may comprise a determining unit 611 and a transmitting unit 612. In an exemplary embodiment, the apparatus 610 may be implemented in a first terminal device. The determining unit 611 may be operable to carry out the operation in block 112, and the transmitting unit 612 may be operable to carry out the operation in block 114. Optionally, the determining unit 611 and/or the transmitting unit 612 may be operable to carry out more or less operations to implement the proposed methods according to the exemplary embodiments of the present disclosure.

Fig. 6B is a block diagram illustrating an apparatus 620 according to some embodiments of the present disclosure. As shown in Fig. 6B, the apparatus 620 may comprise a receiving unit 621 and a determining unit 622. In an exemplary embodiment, the apparatus 620 may be implemented in a second terminal device. The receiving unit 621 may be operable to carry out the operation in block 122, and the determining unit 622 may be operable to carry out the operation in block 124. Optionally, the receiving unit 621 and/or the determining unit 622 may be operable to carry out more or less operations to implement the proposed methods according to the exemplary embodiments of the present disclosure.

Fig. 6C is a block diagram illustrating an apparatus 630 according to some embodiments of the present disclosure. As shown in Fig. 6C, the apparatus 630 may comprise a generating unit 631 and a transmitting unit 632. In an exemplary embodiment, the apparatus 630 may be implemented in a first terminal device. The generating unit 631 may be operable to carry out the operation in block 212, and the transmitting unit 632 may be operable to carry out the operation in block 214. Optionally, the generating unit 631 and/or the transmitting unit 632 may be operable to carry out more or less operations to implement the proposed methods according to the exemplary embodiments of the present disclosure.

Fig. 6D is a block diagram illustrating an apparatus 640 according to some embodiments of the present disclosure. As shown in Fig. 6D, the apparatus 640 may comprise a receiving unit 641 and a decoding unit 642. In an exemplary embodiment, the apparatus 640 may be implemented in a second terminal device. The receiving unit 641 may be operable to carry out the operation in block 222, and the decoding unit 642 may be operable to carry out the operation in block 224. Optionally, the receiving unit 641 and/or the decoding unit 642 may be operable to carry out more or less operations to implement the proposed methods according to the exemplary embodiments of the present disclosure.

Fig. 6E is a block diagram illustrating an apparatus 650 according to some embodiments of the present disclosure. As shown in Fig. 6E, the apparatus 650 may comprise a receiving unit 651 and a determining unit 652. In an exemplary embodiment, the apparatus 650 may be implemented in a first terminal device. The receiving unit 651 may be operable to carry out the operation in block 312, and the determining unit 652 may be operable to carry out the operation in block 314. Optionally, the receiving unit 651 and/or the determining unit 652 may be operable to carry out more or less operations to implement the proposed methods according to the exemplary embodiments of the present disclosure.

Fig. 6F is a block diagram illustrating an apparatus 660 according to some embodiments of the present disclosure. As shown in Fig. 6F, the apparatus 660 may comprise a generating unit 661 and a transmitting unit 662. In an exemplary embodiment, the apparatus 660 may be implemented in a second terminal device. The generating unit 661 may be operable to carry out the operation in block 322, and the transmitting unit 662 may be operable to carry out the operation in block 324. Optionally, the generating unit 661 and/or the transmitting unit 662 may be operable to carry out more or less operations to implement the proposed methods according to the exemplary embodiments of the present disclosure.

Fig. 6G is a block diagram illustrating an apparatus 670 according to some embodiments of the present disclosure. As shown in Fig. 6G, the apparatus 670 may comprise a determining unit 671 and a transmitting unit 672. In an exemplary embodiment, the apparatus 670 may be implemented in a first terminal device. The determining unit 671 may be operable to carry out the operation in block 412, and the transmitting unit 672 may be operable to carry out the operation in block 414. Optionally, the determining unit 671 and/or the transmitting unit 672 may be operable to carry out more or less operations to implement the proposed methods according to the exemplary embodiments of the present disclosure.

Fig. 6H is a block diagram illustrating an apparatus 680 according to some embodiments of the present disclosure. As shown in Fig. 6H, the apparatus 680 may comprise a receiving unit 681 and a determining unit 682. In an exemplary embodiment, the apparatus 680 may be implemented in a network node. The receiving unit 681 may be operable to carry out the operation in block 422, and the determining unit 682 may be operable to carry out the operation in block 424. Optionally, the receiving unit 681 and/or the determining unit 682 may be operable to carry out more or less operations to implement the proposed methods according to the exemplary embodiments of the present disclosure.

Fig. 7 is a block diagram illustrating a telecommunication network connected via an intermediate network to a host computer in accordance with some embodiments of the present disclosure.

With reference to Fig. 7, in accordance with an embodiment, a communication system includes a telecommunication network 710, such as a 3GPP-type cellular network, which comprises an access network 711, such as a radio access network, and a core network 714. The access network 711 comprises a plurality of base stations 712a, 712b, 712c, such as NBs, eNBs, gNBs or other types of wireless access points, each defining a corresponding coverage area 713a, 713b, 713c. Each base station 712a, 712b, 712c is connectable to the core network 714 over a wired or wireless connection 715. A first UE 791 located in a coverage area 713c is configured to wirelessly connect to, or be paged by, the corresponding base station 712c. A second UE 792 in a coverage area 713a is wirelessly connectable to the corresponding base station 712a. While a plurality of UEs 791, 792 are illustrated in this example, the disclosed embodiments are equally applicable to a situation where a sole UE is in the coverage area or where a sole UE is connecting to the corresponding base station 712.

The telecommunication network 710 is itself connected to a host computer 730, which may be embodied in the hardware and/or software of a standalone server, a cloud-implemented server, a distributed server or as processing resources in a server farm. The host computer 730 may be under the ownership or control of a service provider, or may be operated by the service provider or on behalf of the service provider. Connections 721 and 722 between the telecommunication network 710 and the host computer 730 may extend directly from the core network 714 to the host computer 730 or may go via an optional intermediate network 720. An intermediate network 720 may be one of, or a combination of more than one of, a public, private or hosted network; the intermediate network 720, if any, may be a backbone network or the Internet; in particular, the intermediate network 720 may comprise two or more sub-networks (not shown) .

The communication system of Fig. 7 as a whole enables connectivity between the connected UEs 791, 792 and the host computer 730. The connectivity may be described as an over-the-top (OTT) connection 750. The host computer 730 and the connected UEs 791, 792 are configured to communicate data and/or signaling via the OTT connection 750, using the access network 711, the core network 714, any intermediate network 720 and possible further infrastructure (not shown) as intermediaries. The OTT connection 750 may be transparent in the sense that the participating communication devices through which the OTT connection 750 passes are unaware of routing of uplink and downlink communications. For example, the base station 712 may not or need not be informed about the past routing of an incoming downlink communication with data originating from the host computer 730 to be forwarded (e.g., handed over) to a connected UE 791. Similarly, the base station 712 need not be aware of the future routing of an outgoing uplink communication originating from the UE 791 towards the host computer 730.

Fig. 8 is a block diagram illustrating a host computer communicating via a base station with a UE over a partially wireless connection in accordance with some embodiments of the present disclosure.

Example implementations, in accordance with an embodiment, of the UE, base station and host computer discussed in the preceding paragraphs will now be described with reference to Fig. 8. In a communication system 800, a host computer 810 comprises hardware 815 including a communication interface 816 configured to set up and maintain a wired or wireless connection with an interface of a different communication device of the communication system 800. The host computer 810 further comprises a processing circuitry 818, which may have storage and/or processing capabilities. In particular, the processing circuitry 818 may comprise one or more programmable processors, application-specific integrated circuits, field programmable gate arrays or combinations of these (not shown) adapted to execute instructions. The host computer 810 further comprises software 811, which is stored in or accessible by the host computer 810 and executable by the processing circuitry 818. The software 811 includes a host application 812. The host application 812 may be operable to provide a service to a remote user, such as UE 830 connecting via an OTT connection 850 terminating at the UE 830 and the host computer 810. In providing the service to the remote user, the host application 812 may provide user data which is transmitted using the OTT connection 850.

The communication system 800 further includes a base station 820 provided in a telecommunication system and comprising hardware 825 enabling it to communicate with the host computer 810 and with the UE 830. The hardware 825 may include a communication interface 826 for setting up and maintaining a wired or wireless connection with an interface of a different communication device of the communication system 800, as well as a radio interface 827 for setting up and maintaining at least a wireless connection 870 with the UE 830 located in a coverage area (not shown in Fig. 8) served by the base station 820. The communication interface 826 may be configured to facilitate a connection 860 to the host computer 810. The connection 860 may be direct or it may pass through a core network (not shown in Fig. 8) of the telecommunication system and/or through one or more intermediate networks outside the telecommunication system. In the embodiment shown, the hardware 825 of the base station 820 further includes a processing circuitry 828, which may comprise one or more programmable processors, application-specific integrated circuits, field programmable gate arrays or combinations of these (not shown) adapted to execute instructions. The base station 820 further has software 821 stored internally or accessible via an external connection.

The communication system 800 further includes the UE 830 already referred to. Its hardware 835 may include a radio interface 837 configured to set up and maintain a wireless connection 870 with a base station serving a coverage area in which the UE 830 is currently located. The hardware 835 of the UE 830 further includes a processing circuitry 838, which may comprise one or more programmable processors, application-specific integrated circuits, field programmable gate arrays or combinations of these (not shown) adapted to execute instructions. The UE 830 further comprises software 831, which is stored in or accessible by the UE 830 and executable by the processing circuitry 838. The software 831 includes a client application 832. The client application 832 may be operable to provide a service to a human or non-human user via the UE 830, with the support of the host computer 810. In the host computer 810, an executing host application 812 may communicate with the executing client application 832 via the OTT connection 850 terminating at the UE 830 and the host computer 810. In providing the service to the user, the client application 832 may receive request data from the host application 812 and provide user data in response to the request data. The OTT connection 850 may transfer both the request data and the user data. The client application 832 may interact with the user to generate the user data that it provides.

It is noted that the host computer 810, the base station 820 and the UE 830 illustrated in Fig. 8 may be similar or identical to the host computer 730, one of base stations 712a, 712b, 712c and one of UEs 791, 792 of Fig. 7, respectively. This is to say, the inner workings of these entities may be as shown in Fig. 8 and independently, the surrounding network topology may be that of Fig. 7.

In Fig. 8, the OTT connection 850 has been drawn abstractly to illustrate the communication between the host computer 810 and the UE 830 via the base station 820, without explicit reference to any intermediary devices and the precise routing of messages via these devices. Network infrastructure may determine the routing, which it may be configured to hide from the UE 830 or from the service provider operating the host computer 810, or both. While the OTT connection 850 is active, the network infrastructure may further take decisions by which it dynamically changes the routing (e.g., on the basis of load balancing consideration or reconfiguration of the network) .

Wireless connection 870 between the UE 830 and the base station 820 is in accordance with the teachings of the embodiments described throughout this disclosure. One or more of the various embodiments improve the performance of OTT services provided to the UE 830 using the OTT connection 850, in which the wireless connection 870 forms the last segment. More precisely, the teachings of these embodiments may improve the latency and the power consumption, and thereby provide benefits such as lower complexity, reduced time required to access a cell, better responsiveness, extended battery lifetime, etc.

A measurement procedure may be provided for the purpose of monitoring data rate, latency and other factors on which the one or more embodiments improve. There may further be an optional network functionality for reconfiguring the OTT connection 850 between the host computer 810 and the UE 830, in response to variations in the measurement results. The measurement procedure and/or the network functionality for reconfiguring the OTT connection 850 may be implemented in software 811 and hardware 815 of the host computer 810 or in software 831 and hardware 835 of the UE 830, or both. In embodiments, sensors (not shown) may be deployed in or in association with communication devices through which the OTT connection 850 passes; the sensors may participate in the measurement procedure by supplying values of the monitored quantities exemplified above, or supplying values of other physical quantities from which the software 811, 831 may compute or estimate the monitored quantities. The reconfiguring of the OTT connection 850 may include message format, retransmission settings, preferred routing etc.; the reconfiguring need not affect the base station 820, and it may be unknown or imperceptible to the base station 820. Such procedures and functionalities may be known and practiced in the art. In certain embodiments, measurements may involve proprietary UE signaling facilitating the host computer 810’s measurements of throughput, propagation times, latency and the like. The measurements may be implemented in that the software 811 and 831 causes messages to be transmitted, in particular empty or ‘dummy’ messages, using the OTT connection 850 while it monitors propagation times, errors etc.

Fig. 9 is a flowchart illustrating a method implemented in a communication system, in accordance with an embodiment. The communication system includes a host computer, a base station and a UE which may be those described with reference to Fig. 7 and Fig. 8. For simplicity of the present disclosure, only drawing references to Fig. 9 will be included in this section. In step 910, the host computer provides user data. In substep 911 (which may be optional) of step 910, the host computer provides the user data by executing a host application. In step 920, the host computer initiates a transmission carrying the user data to the UE. In step 930 (which may be optional) , the base station transmits to the UE the user data which was carried in the transmission that the host computer initiated, in accordance with the teachings of the embodiments described throughout this disclosure. In step 940 (which may also be optional) , the UE executes a client application associated with the host application executed by the host computer.

Fig. 10 is a flowchart illustrating a method implemented in a communication system, in accordance with an embodiment. The communication system includes a host computer, a base station and a UE which may be those described with reference to Fig. 7 and Fig. 8. For simplicity of the present disclosure, only drawing references to Fig. 10 will be included in this section. In step 1010 of the method, the host computer provides user data. In an optional substep (not shown) the host computer provides the user data by executing a host application. In step 1020, the host computer initiates a transmission carrying the user data to the UE. The transmission may pass via the base station, in accordance with the teachings of the embodiments described throughout this disclosure. In step 1030 (which may be optional) , the UE receives the user data carried in the transmission.

Fig. 11 is a flowchart illustrating a method implemented in a communication system, in accordance with an embodiment. The communication system includes a host computer, a base station and a UE which may be those described with reference to Fig. 7 and Fig. 8. For simplicity of the present disclosure, only drawing references to Fig. 11 will be included in this section. In step 1110 (which may be optional) , the UE receives input data provided by the host computer. Additionally or alternatively, in step 1120, the UE provides user data. In substep 1121 (which may be optional) of step 1120, the UE provides the user data by executing a client application. In substep 1111 (which may be optional) of step 1110, the UE executes a client application which provides the user data in reaction to the received input data provided by the host computer. In providing the user data, the executed client application may further consider user input received from the user. Regardless of the specific manner in which the user data was provided, the UE initiates, in substep 1130 (which may be optional) , transmission of the user data to the host computer. In step 1140 of the method, the host computer receives the user data transmitted from the UE, in accordance with the teachings of the embodiments described throughout this disclosure.

Fig. 12 is a flowchart illustrating a method implemented in a communication system, in accordance with an embodiment. The communication system includes a host computer, a base station and a UE which may be those described with reference to Fig. 7 and Fig. 8. For simplicity of the present disclosure, only drawing references to Fig. 12 will be included in this section. In step 1210 (which may be optional) , in accordance with the teachings of the embodiments described throughout this disclosure, the base station receives user data from the UE. In step 1220 (which may be optional) , the base station initiates transmission of the received user data to the host computer. In step 1230 (which may be optional) , the host computer receives the user data carried in the transmission initiated by the base station.

According to some exemplary embodiments, there is provided a method implemented in a communication system which may include a host computer, a base station and a UE. The method may comprise providing user data at the host computer. Optionally, the method may comprise, at the host computer, initiating a transmission carrying the user data to the UE via a cellular network comprising the base station which may perform any step of the exemplary method 420 as described with respect to Fig. 4B.

According to some exemplary embodiments, there is provided a communication system including a host computer. The host computer may comprise processing circuitry configured to provide user data, and a communication interface configured to forward the user data to a cellular network for transmission to a UE. The cellular network may comprise a base station having a radio interface and processing circuitry. The base station’s processing circuitry may be configured to perform any step of the exemplary method 420 as described with respect to Fig. 4B.

According to some exemplary embodiments, there is provided a method implemented in a communication system which may include a host computer, a base station and a UE. The method may comprise providing user data at the host computer. Optionally, the method may comprise, at the host computer, initiating a transmission carrying the user data to the UE via a cellular network comprising the base station. The UE may perform any step of the exemplary method 110/120/210/220/310/320/410 as described with respect to Fig. 1A/Fig. 1B/Fig. 2A/Fig. 2B/Fig. 3A/Fig. 3B/Fig. 4A.

According to some exemplary embodiments, there is provided a communication system including a host computer. The host computer may comprise processing circuitry configured to provide user data, and a communication interface configured to forward user data to a cellular network for transmission to a UE. The UE may comprise a radio interface and processing circuitry. The UE’s processing circuitry may be configured to perform any step of the exemplary method 110/120/210/220/310/320/410 as described with respect to Fig. 1A/Fig. 1B/Fig. 2A/Fig. 2B/Fig. 3A/Fig. 3B/Fig. 4A.

According to some exemplary embodiments, there is provided a method implemented in a communication system which may include a host computer, a base station and a UE. The method may comprise, at the host computer, receiving user data transmitted to the base station from the UE which may perform any step of the exemplary method 110/120/210/220/310/320/410 as described with respect to Fig. 1A/Fig. 1B/Fig. 2A/Fig. 2B/Fig. 3A/Fig. 3B/Fig. 4A.

According to some exemplary embodiments, there is provided a communication system including a host computer. The host computer may comprise a communication interface configured to receive user data originating from a transmission from a UE to a base station. The UE may comprise a radio interface and processing circuitry. The UE’s processing circuitry may be configured to perform any step of the exemplary method 110/120/210/220/310/320/410 as described with respect to Fig. 1A/Fig. 1B/Fig. 2A/Fig. 2B/Fig. 3A/Fig. 3B/Fig. 4A.

According to some exemplary embodiments, there is provided a method implemented in a communication system which may include a host computer, a base station and a UE. The method may comprise, at the host computer, receiving, from the base station, user data originating from a transmission which the base station has received from the UE. The base station may perform any step of the exemplary method 420 as described with respect to Fig. 4B.

According to some exemplary embodiments, there is provided a communication system which may include a host computer. The host computer may comprise a communication interface configured to receive user data originating from a transmission from a UE to a base station. The base station may comprise a radio interface and processing circuitry. The base station’s processing circuitry may be configured to perform any step of the exemplary method 420 as described with respect to Fig. 4B.

In general, the various exemplary embodiments may be implemented in hardware or special purpose chips, circuits, software, logic or any combination thereof. For example, 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, although the disclosure is not limited thereto. While various aspects of the exemplary embodiments of this disclosure may be illustrated and described as block diagrams, flow charts, or using some other pictorial representation, it is well understood that these 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.

As such, it should be appreciated that at least some aspects of the exemplary embodiments of the disclosure may be practiced in various components such as integrated circuit chips and modules. It should thus be appreciated that the exemplary embodiments of this disclosure may be realized in an apparatus that is embodied as an integrated circuit, where the integrated circuit may comprise circuitry (as well as possibly firmware) for embodying at least one or more of a data processor, a digital signal processor, baseband circuitry and radio frequency circuitry that are configurable so as to operate in accordance with the exemplary embodiments of this disclosure.

It should be appreciated that at least some aspects of the exemplary embodiments of the disclosure may be embodied in computer-executable instructions, such as in one or more program modules, executed by one or more computers or other devices. Generally, program modules include routines, programs, objects, components, data structures, etc. that perform particular tasks or implement particular abstract data types when executed by a processor in a computer or other device. The computer executable instructions may be stored on a computer readable medium such as a hard disk, optical disk, removable storage media, solid state memory, random access memory (RAM) , etc. As will be appreciated by one of skill in the art, the function of the program modules may be combined or distributed as desired in various embodiments. In addition, the function may be embodied in whole or partly in firmware or hardware equivalents such as integrated circuits, field programmable gate arrays (FPGA) , and the like.

The present disclosure includes any novel feature or combination of features disclosed herein either explicitly or any generalization thereof. Various modifications and adaptations to the foregoing exemplary embodiments of this disclosure may become apparent to those skilled in the relevant arts in view of the foregoing description, when read in conjunction with the accompanying drawings. However, any and all modifications will still fall within the scope of the non-limiting and exemplary embodiments of this disclosure.

Claims

A method (210) performed by a first terminal device, comprising:

generating (212) a message which includes sidelink, SL, channel state information, CSI, reports and/or inter-user equipment, inter-UE, coordination information for a set of terminal devices; and

transmitting (214) the message towards the set of the terminal devices.
The method according to claim 1, wherein the first terminal device transmits the message towards the set of the terminal devices in one or more of:

a medium access control, MAC, protocol data unit, PDU, including multiple SL CSI report and/or inter-UE coordination information MAC control elements, CEs, for the set of the terminal devices;

a MAC CE including the SL CSI reports and/or the inter-UE coordination information for the set of the terminal devices; and

Layer 1, L1, signaling including the SL CSI reports and/or the inter-UE coordination information for the set of the terminal devices.
The method according to claim 1 or 2, wherein a number of the set of the terminal devices is indicated in a MAC subheader and/or preconfigured.
The method according to any of claims 1-3, wherein the set of the terminal devices include one or more of:

one or more terminal devices which have sent SL CSI requests and/or inter-UE coordination requests to the first terminal device and for which associated latency bounds are not exceeded;

one or more terminal devices which have sent SL CSI requests and/or inter-UE coordination requests having one or more parameters with similar or same values to the first terminal device;

one or more terminal devices towards which the first terminal device is to transmit the SL CSI reports and/or the inter-UE coordination information having one or more parameters with similar or same values; and

one or more terminal devices with which the first terminal device has SL connections carrying similar or same data and/or services.
The method according to any of claims 1-4, wherein the set of the terminal devices is indicated by one or more identifiers included in one or more of:

L1 signaling;

a MAC subheader;

a MAC CE carrying the SL CSI reports for the set of the terminal devices;

a MAC CE carrying the inter-UE coordination information for the set of the terminal devices; and

PC5-radio resource control, PC5-RRC, signaling.
A first terminal device (500) , comprising:

one or more processors (501) ; and

one or more memories (502) comprising computer program codes (503) ,

the one or more memories (502) and the computer program codes (503) configured to, with the one or more processors (501) , cause the first terminal device (500) at least to:

generate a message which includes sidelink, SL, channel state information, CSI, reports and/or inter-user equipment, inter-UE, coordination information for a set of terminal devices; and

transmit the message towards the set of the terminal devices.
The first terminal device according to claim 6, wherein the one or more memories and the computer program codes are configured to, with the one or more processors, cause the first terminal device to perform the method according to any one of claims 2-5.
A method (220) performed by a second terminal device, comprising:

receiving (222) a message transmitted by a first terminal device, wherein the message includes sidelink, SL, channel state information, CSI, reports and/or inter-user equipment, inter-UE, coordination information for a set of terminal devices; and

decoding (224) an SL CSI report and/or inter-UE coordination information provided to the second terminal device by the first terminal device in the message, when the second terminal device belongs to the set of terminal devices.
The method according to claim 8, wherein the second terminal device receives the message in one or more of:

a medium access control, MAC, protocol data unit, PDU, including multiple SL CSI report and/or inter-UE coordination information MAC control elements, CEs, for the set of the terminal devices;

a MAC CE including the SL CSI reports and/or the inter-UE coordination information for the set of the terminal devices; and

Layer 1, L1, signaling including the SL CSI reports and/or the inter-UE coordination information for the set of the terminal devices.
The method according to claim 8 or 9, wherein a number of the set of the terminal devices is indicated in a MAC subheader and/or preconfigured.
The method according to any of claims 8-10, wherein the set of the terminal devices include one or more of:

one or more terminal devices which have sent SL CSI requests and/or inter-UE coordination requests to the first terminal device and for which associated latency bounds are not exceeded;

one or more terminal devices which have sent SL CSI requests and/or inter-UE coordination requests having one or more parameters with similar or same values to the first terminal device;

one or more terminal devices towards which the first terminal device is to transmit the SL CSI reports and/or the inter-UE coordination information having one or more parameters with similar or same values; and

one or more terminal devices with which the first terminal device has SL connections carrying similar or same data and/or services.
The method according to any of claims 8-11, wherein the set of the terminal devices is indicated by one or more identifiers included in one or more of:

L1 signaling;

a MAC subheader;

a MAC CE carrying the SL CSI reports for the set of the terminal devices;

a MAC CE carrying the inter-UE coordination information for the set of the terminal devices; and

PC5-radio resource control, PC5-RRC, signaling.
A second terminal device (500) , comprising:

one or more processors (501) ; and

one or more memories (502) comprising computer program codes (503) ,

the one or more memories (502) and the computer program codes (503) configured to, with the one or more processors (501) , cause the second terminal device (500) at least to:

receive a message transmitted by a first terminal device, wherein the message includes sidelink, SL, channel state information, CSI, reports and/or inter-user equipment, inter-UE, coordination information for a set of terminal devices; and

decode an SL CSI report and/or inter-UE coordination information provided to the second terminal device by the first terminal device in the message, when the second terminal device belongs to the set of terminal devices.
The second terminal device according to claim 13, wherein the one or more memories and the computer program codes are configured to, with the one or more processors, cause the second terminal device to perform the method according to any one of claims 9-12.
A method (310) performed by a first terminal device, comprising:

receiving (312) a message transmitted by a second terminal device, wherein the message includes a sidelink, SL, channel state information, CSI, request and/or an inter-user equipment, inter-UE, coordination request to a set of terminal devices; and

determining (314) whether to respond to the SL CSI request and/or the inter-UE coordination request.
The method according to claim 15, wherein the set of the terminal devices is indicated by one or more identifiers included in one or more of:

Layer 1, L1, signaling;

a medium access control, MAC, subheader;

a MAC control element, CE, carrying the SL CSI request;

a MAC CE carrying the inter-UE coordination request; and

PC5-radio resource control, PC5-RRC, signaling.
The method according to claim 16, wherein the one or more identifiers include one or more bits which indicate whether a terminal device receiving the message needs to respond to the SL CSI request and/or the inter-UE coordination request.
The method according to claim 16 or 17, wherein the one or more identifiers include: one or more group identifiers associated with one or more device groups; and/or one or more bits which indicate whether the SL CSI request and/or the inter-UE coordination request are associated with the one or more group identifiers.
The method according to claim 18, wherein for the one or more device groups, a member in a device group is allowed to:

receive a request containing a group identifier associated with the device group from another member in the device group, and provide a response to the request to the another member; and/or

transmit a request to the device group by including the associated group identifier in the request,

wherein the request includes an SL CSI request and/or an inter-UE coordination request.
The method according to claim 19, wherein the first terminal device and/or the second terminal device are configured with one or multiple group identifiers associated with one or more device groups.
The method according to any of claims 15-20, wherein when the first terminal device belongs to the set of terminal devices, the first terminal device determines to respond to the SL CSI request and/or the inter-UE coordination request, and the method further comprises:

generating an SL CSI report and/or inter-UE coordination information, according to the SL CSI request and/or the inter-UE coordination request; and

transmitting the SL CSI report and/or the inter-UE coordination information towards the second terminal device.
A first terminal device (500) , comprising:

one or more processors (501) ; and

one or more memories (502) comprising computer program codes (503) ,

the one or more memories (502) and the computer program codes (503) configured to, with the one or more processors (501) , cause the first terminal device (500) at least to:

receive a message transmitted by a second terminal device, wherein the message includes a sidelink, SL, channel state information, CSI, request and/or an inter-user equipment, inter-UE, coordination request to a set of terminal devices; and

determine whether to respond to the SL CSI request and/or the inter-UE coordination request.
The first terminal device according to claim 22, wherein the one or more memories and the computer program codes are configured to, with the one or more processors, cause the first terminal device to perform the method according to any one of claims 16-21.
A method (320) performed by a second terminal device, comprising:

generating (322) a message which includes a sidelink, SL, channel state information, CSI, request and/or an inter-user equipment, inter-UE, coordination request to a set of terminal devices; and

transmitting (324) the message towards the set of the terminal devices.
The method according to claim 24, wherein the set of the terminal devices is indicated by one or more identifiers included in one or more of:

Layer 1, L1, signaling;

a medium access control, MAC, subheader;

a MAC control element, CE, carrying the SL CSI request;

a MAC CE carrying the inter-UE coordination request; and

PC5-radio resource control, PC5-RRC, signaling.
The method according to claim 25, wherein the one or more identifiers include: one or more bits which indicate whether a terminal device receiving the message needs to respond to the SL CSI request and/or the inter-UE coordination request.
The method according to claim 25 or 26, wherein the one or more identifiers include: one or more group identifiers associated with one or more device groups, and/or one or more bits which indicate whether the SL CSI request and/or the inter-UE coordination request are associated with the one or more group identifiers.
The method according to claim 27, wherein for the one or more device groups, a member in a device group is allowed to:

receive a request containing a group identifier associated with the device group from another member in the device group, and provide a response to the request to the another member; and/or

transmit a request to the device group by including the associated group identifier in the request,

wherein the request includes an SL CSI request and/or an inter-UE coordination request.
The method according to claim 28, wherein the second terminal device is configured with one or multiple group identifiers associated with one or more device groups.
A second terminal device (500) , comprising:

one or more processors (501) ; and

one or more memories (502) comprising computer program codes (503) ,

the one or more memories (502) and the computer program codes (503) configured to, with the one or more processors (501) , cause the second terminal device (500) at least to:

generate a message which includes a sidelink, SL, channel state information, CSI, request and/or an inter-user equipment, inter-UE, coordination request to a set of terminal devices; and

transmit the message towards the set of the terminal devices.
The second terminal device according to claim 30, wherein the one or more memories and the computer program codes are configured to, with the one or more processors, cause the second terminal device to perform the method according to any one of claims 25-29.
A method (410) performed by a first terminal device, comprising:

determining (412) an amount of sidelink, SL, channel state information, CSI, reports and/or inter-user equipment, inter-UE, coordination information included in a message to be transmitted towards a set of terminal devices; and

transmitting (414) a scheduling request, SR, to a network node, wherein the SR indicates the amount of the SL CSI reports and/or the inter-UE coordination information.
The method according to claim 32, wherein the amount of the SL CSI reports and/or the inter-UE coordination information is indicated by the SR in one or more of the following ways:

the SR being associated with a SR configuration which corresponds to the amount of the SL CSI reports and/or the inter-UE coordination information; and

one or more bits in the SR being set to represent a value which corresponds to the amount of the SL CSI reports and/or the inter-UE coordination information.
The method according to claim 32 or 33, further comprising:

receiving a grant from the network node, wherein the grant indicates resource allocation to the first terminal device for transmitting the SL CSI reports and/or the inter-UE coordination information towards the set of terminal devices.
A first terminal device (500) , comprising:

one or more processors (501) ; and

one or more memories (502) comprising computer program codes (503) ,

the one or more memories (502) and the computer program codes (503) configured to, with the one or more processors (501) , cause the first terminal device (500) at least to:

determine an amount of sidelink, SL, channel state information, CSI, reports and/or inter-user equipment, inter-UE, coordination information included in a message to be transmitted towards a set of terminal devices; and

transmit a scheduling request, SR, to a network node, wherein the SR indicates the amount of the SL CSI reports and/or the inter-UE coordination information.
The first terminal device according to claim 35, wherein the one or more memories and the computer program codes are configured to, with the one or more processors, cause the first terminal device to perform the method according to any one of claims 33-34.
A method (420) performed by a network node, comprising:

receiving (422) a scheduling request, SR, from a first terminal device, wherein the SR indicates an amount of sidelink, SL, channel state information, CSI, reports and/or inter-user equipment, inter-UE, coordination information included in a message to be transmitted by the first terminal device towards a set of terminal devices; and

determining (424) , according to the SR, resource allocation to the first terminal device for transmitting the SL CSI reports and/or the inter-UE coordination information towards the set of terminal devices.
The method according to claim 37, wherein the amount of the SL CSI reports and/or the inter-UE coordination information is indicated by the SR in one or more of the following ways:

the SR being associated with a SR configuration which corresponds to the amount of the SL CSI reports and/or the inter-UE coordination information; and

one or more bits in the SR being set to represent a value which corresponds to the amount of the SL CSI reports and/or the inter-UE coordination information.
The method according to claim 37 or 38, further comprising:

transmitting a grant to the first terminal device, wherein the grant indicates the resource allocation to the first terminal device for transmitting the SL CSI reports and/or the inter-UE coordination information towards the set of terminal devices.
A network node (500) , comprising:

one or more processors (501) ; and

one or more memories (502) comprising computer program codes (503) ,

the one or more memories (502) and the computer program codes (503) configured to, with the one or more processors (501) , cause the network node (500) at least to:

receive a scheduling request, SR, from a first terminal device, wherein the SR indicates an amount of sidelink, SL, channel state information, CSI, reports and/or inter-user equipment, inter-UE, coordination information included in a message to be transmitted by the first terminal device towards a set of terminal devices; and

determine, according to the SR, resource allocation to the first terminal device for transmitting the SL CSI reports and/or the inter-UE coordination information towards the set of terminal devices.
The network node according to claim 40, wherein the one or more memories and the computer program codes are configured to, with the one or more processors, cause the network node to perform the method according to any one of claims 38-39.
A computer-readable medium having computer program codes (503) embodied thereon which, when executed on a computer, cause the computer to perform any step of the method according to any one of claims 1-5, or any one of claims 8-12, or any one of claims 15-21, or any one of claims 24-29, or any one of claims 32-34, or any one of claims 37-39.