WO2023050148A1

WO2023050148A1 - Methods, devices, and computer readable medium for communication

Info

Publication number: WO2023050148A1
Application number: PCT/CN2021/121709
Authority: WO
Inventors: Da Wang; Gang Wang
Original assignee: Nec Corporation
Priority date: 2021-09-29
Filing date: 2021-09-29
Publication date: 2023-04-06
Also published as: CN118044325A

Abstract

According to embodiments, solutions on sidelink are proposed. A terminal device obtains a configuration of consistent listen before talk (LBT) failure detection for a sidelink communication. The configuration indicates a condition for consistent LBT failure. The terminal device also detects a consistent LBT failure for the sidelink communication. If the condition is met, the terminal device performs one of the followings: releasing the sidelink communication, suspending the sidelink communication, or performing a consistent LBT failure recovery. In this way, the terminal device can save power.

Description

METHODS, DEVICES, AND COMPUTER READABLE MEDIUM FOR COMMUNICATION

TECHNICAL FIELD

Embodiments of the present disclosure generally relate to the field of telecommunication, and in particular, to methods, devices, and computer readable medium for communication.

BACKGROUND

Several technologies have been proposed to improve communication performances. For example, device to device (D2D) /sidelink communication has been proposed. Sidelink is the special kind of communication mechanism between device and device without going through eNB.

SUMMARY

In general, example embodiments of the present disclosure provide a solution for communication.

In a first aspect, there is provided a method for communication. The communication method comprises: obtaining, at a first terminal device, a configuration of consistent listen before talk (LBT) failure detection, the configuration indicating a condition for a consistent LBT failure on a sidelink communication; detecting a consistent LBT failure for the sidelink communication based on the condition; and in accordance with a determination that the condition is met, performing one of the followings: releasing the sidelink communication, suspending the sidelink communication, or performing a consistent LBT failure recovery for the sidelink communication.

In a second aspect, there is provided a terminal device. The terminal device comprises a processing unit; and a memory coupled to the processing unit and storing instructions thereon, the instructions, when executed by the processing unit, causing the terminal device to perform acts comprising: obtaining, a configuration of consistent listen before talk (LBT) failure detection, the configuration indicating a condition for a consistent LBT failure on a sidelink communication; detecting a consistent LBT failure for the sidelink communication based on the condition; and in accordance with a determination that the condition is met, performing one of the followings: releasing the sidelink communication, suspending the sidelink communication, or performing a consistent LBT failure recovery for the sidelink communication.

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

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

BRIEF DESCRIPTION OF THE DRAWINGS

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

Figs. 1A and 1B are schematic diagrams of communication environments in which embodiments of the present disclosure can be implemented, respectively;

Fig. 2 illustrates a signaling flow for communications according to some embodiments of the present disclosure;

Fig. 3 illustrates a signaling flow for communications according to some embodiments of the present disclosure;

Fig. 4 is a flowchart of an example method in accordance with an embodiment of the present disclosure; and

Fig. 5 is a simplified block diagram of a device that is suitable for implementing embodiments of the present disclosure.

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

DETAILED DESCRIPTION

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

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

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

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

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

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

Embodiments of the present disclosure may be performed according to any generation communication protocols either currently known or to be developed in the future. Examples of the communication protocols include, but not limited to, the first generation (1G) , the second generation (2G) , 2.5G, 2.75G, the third generation (3G) , the fourth generation (4G) , 4.5G, the fifth generation (5G) communication protocols, 5.5G, 5G-Advanced networks, or the sixth generation (6G) networks.

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

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

Communications discussed herein may use conform to any suitable standards including, but not limited to, New Radio Access (NR) , Long Term Evolution (LTE) , LTE-Evolution, LTE-Advanced (LTE-A) , Wideband Code Division Multiple Access (WCDMA) , Code Division Multiple Access (CDMA) , cdma2000, and Global System for Mobile Communications (GSM) and the like. Furthermore, the communications may be performed according to any generation communication protocols either currently known or to be developed in the future. Examples of the communication protocols include, but not limited to, the first generation (1G) , the second generation (2G) , 2.5G, 2.85G, the third generation (3G) , the fourth generation (4G) , 4.5G, the fifth generation (5G) , and the sixth (6G) communication protocols. The techniques described herein may be used for the wireless networks and radio technologies mentioned above as well as other wireless networks and radio technologies. The embodiments of the present disclosure may be performed according to any generation communication protocols either currently known or to be developed in the future. Examples of the communication protocols include, but not limited to, the first generation (1G) , the second generation (2G) , 2.5G, 2.75G, the third generation (3G) , the fourth generation (4G) , 4.5G, the fifth generation (5G) communication protocols, 5.5G, 5G-Advanced networks, or the sixth generation (6G) networks.

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

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

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

As mentioned above, sidelink has been proposed. Sidelink supports direct communication between two or more nearby UEs, using NR/LTE technology but not traversing any network node. The next generation radio access network (NG-RAN) architecture can support a PC5 interface. Sidelink transmission and reception over the PC5 interface are supported when the UE is inside NG-RAN coverage, irrespective of which RRC state the UE is in, and when the UE is outside NG-RAN coverage. NR sidelink communication can comprise unicast, groupcast and broadcast. For unicast, the PC5-RRC connection is a logical connection between a pair of a Source Layer-2 ID and a Destination Layer-2 ID in the access stratum (AS) .

Conventionally, two sidelink resource allocation modes are supported: mode 1 and mode 2. In mode 1, the sidelink resource allocation is provided by the network. NG-RAN can dynamically allocate resources to the UE via the Sidelink RNTI (SL-RNTI) on Physical Downlink Control Channel (PDCCH) for NR sidelink communication. In addition, NG-RAN can allocate sidelink resources to a UE with two types of configured sidelink grants: with type 1, RRC directly provides the configured sidelink grant only for NR sidelink communication; with type 2, RRC defines the periodicity of the configured sidelink grant while PDCCH can either signal and activate the configured sidelink grant, or deactivate it. The PDCCH is addressed to (Sidelink Configured Scheduling RNTI) SL-CS-RNTI for NR sidelink communication. Currently configured sidelink grant is only used for initial transmission.

In mode 2, UE decides the SL transmission resources in the resource pool (s) . The UE autonomously selects sidelink resource (s) from resource pool (s) provided by broadcast system information or dedicated signaling while inside NG-RAN coverage or by pre-configuration while outside NG-RAN coverage. NG-RAN can dynamically allocate resources to the UE via the SL-RNTI on PDCCH (s) for NR sidelink communication. Currently, sidelink is only supported on licensed band. Moreover, it is studying on supporting sidelink communication performed on unlicensed band. However, the unlicensed band is unstable, consistent LBT failure can happen if there is sudden increase of traffic on the band. If the terminal device continues to perform the sidelink communication at the unlicensed band, it will result in waste of UE power and big latency of traffic. Moreover, it is also not known how to support configured sidelink retransmission for sidelink and how to get the received signal strength indicator (RSSI) and channel occupancy information at the peer UE.

According to embodiments, solutions on sidelink are proposed. A terminal device obtains a configuration of consistent listen before talk (LBT) failure detection. The configuration indicates a condition for consistent LBT failure. The terminal device also detects a consistent LBT failure for a sidelink communication based on the condition. If the condition is met, the terminal device performs one of the followings: releasing the sidelink communication, suspending the sidelink communication, or performing a consistent LBT failure recovery for the sidelink communication. In this way, the terminal device can save power.

Fig. 1A illustrates a schematic diagram of a communication system in which embodiments of the present disclosure can be implemented. The communication system 100-1, which is a part of a communication network, comprises a terminal device 110. The communication system also comprises a terminal device 130-1, a terminal device 130-2, ..., a terminal device 130-N, which can be collectively referred to as “terminal device (s) 130. ” The number N can be any suitable integer number. The terminal devices 110 can communication with the terminal devices 130 (for example, the terminal devices 130-1, 130-2 and 130-N) and a link between terminal devices is referred to as sidelink.

The communication system 100-1 further comprises a network device. In the communication system 100, the network device 120 and the terminal device 110 can communicate data and control information to each other. The numbers of terminal devices shown in Fig. 1 are given for the purpose of illustration without suggesting any limitations. The network device 120 can also communication with the terminal devices 130. In this case, the terminal devices 130-1, 130-2 and 130-N can be referred to as destination terminal devices/UE. In the communication system 110 shown in Fig. 1A, the terminal device 110 and the terminal devices 130 are in the coverage of the network device 120. Alternatively, in the communication system 130-1 as shown in Fig. 1B, the terminal device 110 and the terminal device 130 are out of the coverage of the network device 120. In some other embodiments, one or more of the terminal devices (including the terminal device 110 and the terminal devices 130) may be out of the coverage of the network device 120 and other terminal devices may be in the coverage of the network device 120.

Communications in the communication system 100 may be implemented according to any proper communication protocol (s) , comprising, but not limited to, cellular communication protocols of the first generation (1G) , the second generation (2G) , the third generation (3G) , the fourth generation (4G) and the fifth generation (5G) and on the like, wireless local network communication protocols such as Institute for Electrical and Electronics Engineers (IEEE) 802.11 and the like, and/or any other protocols currently known or to be developed in the future. Moreover, the communication may utilize any proper wireless communication technology, comprising but not limited to: Code Divided Multiple Address (CDMA) , Frequency Divided Multiple Address (FDMA) , Time Divided Multiple Address (TDMA) , Frequency Divided Duplexer (FDD) , Time Divided Duplexer (TDD) , Multiple-Input Multiple-Output (MIMO) , Orthogonal Frequency Divided Multiple Access (OFDMA) and/or any other technologies currently known or to be developed in the future.

Embodiments of the present disclosure can be applied to any suitable scenarios. For example, embodiments of the present disclosure can be implemented at reduced capability NR devices. Alternatively, embodiments of the present disclosure can be implemented in one of the followings: NR multiple-input and multiple-output (MIMO) , NR sidelink enhancements, NR systems with frequency above 52.6GHz, an extending NR operation up to 71GHz, narrow band-Internet of Thing (NB-IOT) /enhanced Machine Type Communication (eMTC) over non-terrestrial networks (NTN) , NTN, UE power saving enhancements, NR coverage enhancement, NB-IoT and LTE-MTC, Integrated Access and Backhaul (IAB) , NR Multicast and Broadcast Services, or enhancements on Multi-Radio Dual-Connectivity.

The term “slot” used herein refers to a dynamic scheduling unit. One slot comprises a predetermined number of symbols. The term “downlink (DL) sub-slot” may refer to a virtual sub-slot constructed based on uplink (UL) sub-slot. The DL sub-slot may comprise fewer symbols than one DL slot. The slot used herein may refer to a normal slot which comprises a predetermined number of symbols and also refer to a sub-slot which comprises fewer symbols than the predetermined number of symbols.

Embodiments of the present disclosure will be described in detail below. Reference is first made to Fig. 2, which shows a signaling chart illustrating process 200 between the terminal device and the network device according to some example embodiments of the present disclosure. Only for the purpose of discussion, the process 200 will be described with reference to Fig. 1. The process 200 may involve the terminal device 110 and the network device 120 in Fig. 1.

The terminal device 110 obtains a configuration of consistent LBT failure detection. The term “listen before talk (LBT) ” used herein refers to a technique used in radio communications whereby a radio transmitter first senses its radio environment before it starts a transmission. LBT can be used by a radio device to find a network the device is allowed to operate on or to find a free radio channel to operate on. The term “clear channel assessment (CCA) ” used herein refers to a technique to appraise the RF medium. The CCA involves listening for RF transmissions at the Physical layer radios use two separate CCA thresholds when listening to the RF medium.

The configuration of the consistent LBT failure detection indicates a condition for consistent LBT failure. For example, in some embodiments, the configuration of the consistent LBT failure detection may comprise a threshold value of a counter for the LBT failure, which determines after how many consistent sidelink LBT failure events the UE considers consistent LBT failure for the sidelink is detected. In addition, the configuration of consistent LBT failure detection may comprise value of timer for consistent sidelink LBT failure detection.

Referring to Fig. 2, in some embodiments, the network device 120 may transmit 2005 the configuration of the consistent LBT failure detection to the terminal device 110. For example, the configuration of the consistent LBT failure detection can be transmitted in system information. Alternatively, the configuration of the consistent LBT failure detection may be transmitted in a RRC reconfiguration message.

In some other embodiments, the terminal device 110 may obtain 2010 the configuration of the consistent LBT failure detection from preconfigured information. In this case, the terminal device 110 may obtain the configuration of the consistent LBT failure detection when out of the coverage of the network device 120.

The terminal device 110 detects 2015 a consistent LBT failure for the sidelink communications. In some embodiments, the terminal device 110 may detect the consistent LBT failure per sidelink bandwidth part (BWP) . Alternatively, the terminal device 110 may detect the consistent LBT failure per sidelink resource pool.

In some embodiments, the terminal device 110 maintains one counter and one timer for consistent LBT failure detection for each sidelink BWP. In some embodiments, the terminal device 110 may count LBT failure indications from lower layers to the MAC layer. For example, if the LBT failure indication has been received from lower layers, the MAC layer of the terminal device 110 may start or restart the timer and increment one counter by 1. If the counter is equal to or above the threshold value indicated in configuration of the consistent LBT failure detection, it means that the condition for the consistent LBT failure is met. In this case, the consistent LBT failure for the active SL BWP is triggered. If the timer expiry, the terminal device 110 may reset the counter to 0. Alternatively, if the SL BWP is deactivated, the counter can be reset and the timer for detecting the consistent LBT failure can be stopped. In some embodiments, if the consistent LBT failure is detected by the MAC layer, the MAC layer may inform the RRC layer regarding the consistent LBT failure.

In some embodiments, if the condition for the consistent LBT failure is met, the terminal device 110 may release 2020 the sidelink communications. In this way, upon detection of consistent LBT failure, the terminal device can stop the sidelink transmission and reception, for power saving.

For example, if the consistent LBT failure is detected for one sidelink BWP, the terminal device 110 may release data radio bearers (DRB) of all destination terminal devices or all destination terminal devices working on the sidelink BWP. For example, the terminal device 110 may release the DRBs of all destination terminal devices 130. Alternatively, if the terminal devices 130-1 and 130-2 are working on the sidelink BWP, of which consistent LBT failure is detected, the terminal device 110 may release the DRBs of the terminal devices 130-1 and 130-2. The term “data radio bearer (DRB) ” used herein can refer to a bearer which transports data between terminal devices or between the terminal device and the network device.

In other embodiments, the terminal device 110 may release service radio bearers (SRB) of all destination terminal devices or all destination terminal devices working on the sidelink BWP. The consistent LBT failure is detected on this sidelink BWP. For example, the terminal device 110 may release the SRBs of all destination terminal devices 110. Alternatively, if the terminal devices 130-1 and 130-2 are working on the sidelink BWP, the terminal device 110 may release the SRBs of the terminal devices 130-1 and 130-2. The term “signaling radio bearer (SRB) ” used herein can refer to a type of radio bearer that carries signaling message (for example, RRC or/and non-access stratums (NAS) message) .

Alternatively, the terminal device 110 may discard a sidelink communication related configuration of all destination terminal devices or all destination terminal devices working on the sidelink BWP. The consistent LBT failure is detected on this sidelink BWP. For example, the terminal device 110 may discard the sidelink communication related configuration of all destination terminal devices 110. Alternatively, if the terminal devices 130-1 and 130-2 are working on the sidelink BWP, the terminal device 110 may discard the sidelink communication related configuration of the terminal devices 130-1 and 130-2.

Additionally, the terminal device 110 may reset a sidelink specific MAC of all destination terminal devices or all destination terminal devices working on the sidelink BWP. The consistent LBT failure is detected on this sidelink BWP. For example, the terminal device 110 may reset the sidelink specific MAC of all destination terminal devices 110. Alternatively, if the terminal devices 130-1 and 130-2 are working on the sidelink BWP, the terminal device 110 may reset the sidelink specific MAC of the terminal devices 130-1 and 130-2.

In some other embodiments, the terminal device 110 may release PC5-RRC connection for all destination terminal devices or all destination terminal devices working on the sidelink BWP. The consistent LBT failure is detected on this sidelink BWP. For example, the terminal device 110 may release the PC5-RRC connection for all destination terminal devices 110. Alternatively, if the terminal devices 130-1 and 130-2 are working on the sidelink BWP, the terminal device 110 may release the PC5-RRC connection for the terminal devices 130-1 and 130-2. In an example embodiment, the RRC layer terminal device 110 may indicate the release of the PC5-RRC connection for all destination terminal device or all destination terminal devices to an upper layer (for example, PC5 sidelink layer) .

Alternatively, if the the condition for the consistent LBT failure is met, the terminal device 110 may suspend 2025 the sidelink communications. In this way, the network can fix the consistent LBT issue by a further RRC Reconfiguration, thus there is no need a release and add of PC5-RRC connection.

For example, if the consistent LBT failure is detected for one sidelink BWP, the terminal device 110 may suspend DRBs of all destination terminal devices or all destination terminal devices working on the sidelink BWP. The consistent LBT failure is detected on this sidelink BWP. For example, the terminal device 110 may suspend the DRBs of all destination terminal devices 110. Alternatively, if the terminal devices 130-1 and 130-2 are working on the sidelink BWP, the terminal device 110 may suspend the DRBs of the terminal devices 130-1 and 130-2.

In other embodiments, the terminal device 110 may suspend SRBs of all destination terminal devices or all destination terminal devices working on the sidelink BWP. The consistent LBT failure is detected on this sidelink BWP. For example, the terminal device 110 may suspend the SRBs of all destination terminal devices 110. Alternatively, if the terminal devices 130-1 and 130-2 are working on the sidelink BWP, the terminal device 110 may suspend the SRBs of the terminal devices 130-1 and 130-2.

In other embodiments, the terminal device 110 may suspend sidelink transmissions for the DRBs and the SRBs of all destination terminal devices or all destination terminal devices working on the sidelink BWP. The consistent LBT failure is detected on this sidelink BWP. For example, the terminal device 110 may suspend sidelink transmissions for the DRBs and the SRBs of all destination terminal devices 110. Alternatively, if the terminal devices 130-1 and 130-2 are working on the sidelink BWP, the terminal device 110 may suspend sidelink transmissions for the DRBs and the SRBs of the terminal devices 130-1 and 130-2.

Additionally, the terminal device 110 may reset a sidelink specific MAC of all destination terminal devices or all destination terminal devices working on the sidelink BWP. For example, the terminal device 110 may reset the sidelink specific MAC of all destination terminal devices 110. Alternatively, if the terminal devices 130-1 and 130-2 are working on the sidelink BWP, the terminal device 110 may reset the sidelink specific MAC of the terminal devices 130-1 and 130-2.

In other embodiments, the terminal device 110 may suspend a sidelink carrier, the sidelink BWP of which is detected as consistent LBT failure. Alternatively or in addition, the terminal device 110 may suspend the BWP, of which consistent LBT failure is detected.

In some other embodiments, the terminal device 110 may suspend PC5-RRC connection for all destination terminal devices or all destination terminal devices working on the sidelink BWP. The consistent LBT failure is detected on this sidelink BWP.. For example, the terminal device 110 may suspend the PC5-RRC connection for all destination terminal devices 110. Alternatively, if the terminal devices 130-1 and 130-2 are working on the sidelink BWP, the terminal device 110 may suspend the PC5-RRC connection for the terminal devices 130-1 and 130-2. In an example embodiment, the RRC layer terminal device 110 may indicate the suspending of the PC5-RRC connection for all destination terminal devices or all destination terminal device working on the sidelink BWP to an upper layer (for example, PC5 sidelink layer) .

In an example embodiment, the terminal device 110 may inform the network device 120 regarding the consistent LBT failure. For example, an information element (IE) or indication can be included in the RRC message (for example SidelinkUEInformationNR message) to indicate consistent LBT failure of the sidelink.

Alternatively or in addition, the terminal device 110 may inform the network device 120 regarding a radio link failure (RLF) for all destination terminal devices or all destination terminal devices working on the sidelink BWP. For example, the terminal device 110 may set sl-failure as RLF failure in the SidelinkUEInformationNR message to indicate the consistent LBT failure.

In other embodiments, the terminal device 110 may transmit at least one of sidelink BWP information or sidelink carrier information of the consistent LBT failure to the network device 120. The sidelink BWP information may indicate the ID of sidelink BWP. The carrier information may indicate a frequency of the sidelink carrier.

The network device 120 may transmit 2040, to the terminal device 110, a reconfiguration message for reconfiguring the sidelink communication. The reconfiguration message may reconfigure the sidelink carrier frequency or reconfigure the sdielink BWP for the terminal device 110. In this case, the terminal device 110 may resume the DRBs. Alternatively or in addition, the terminal device 110 may resume the SRBs. In some embodiments, the terminal device 110 may resume the sidelink transmissions for the DRBs and the SRBs. In other embodiments, the terminal device 110 may resume the sidelink carrier. Alternatively or in addition, the terminal device 110 may resume the sidelink BWP. The terminal device 110 may also resume the PC5-RRC connection. In this case, the terminal device 110 may indicate the resuming of the PC5-RRC connection to an upper layer, for example, a PC5 sidelink layer. In this way, the network can fix the consistent LBT issue by a further RRC Reconfiguration, thus there is no need a release and add of PC5-RRC connection.

If there is no sidelink BWP or SL carrier of which consistent LBT failure has not been triggered, the terminal device 110 may release (2020) the sidelink communication. Alternatively, the terminal device 110 may suspend (2025) the sidelink communication.

In other embodiments, if the condition for the consistent LBT failure is met, the terminal device 110 may perform 2030 a failure recovery. In this way, it can reduce latency.

For example, the terminal device 110 may be provided with a set of resources for the recovery procedure via RRC message. For example, the terminal device 110 may switch to another sidelink BWP or carrier for which the consistent LBT failure has not been triggered. In some embodiments, the terminal device 110 may release the sidelink BWP. Alternatively or in addition, the terminal device 110 may release the sidelink carrier. In some other embodiments, the terminal device 110 may deactivate the sidelink BWP. The terminal device 110 may deactivate the sidelink carrier. In this case, the terminal device 110 may transmit 2035 information to the network device 120. The information may indicate the switching of the sidelink BWP. Alternatively or in addition, the information may indicate the releasing or deactivating of the sidelink BWP. In other embodiments, the information may indicate the switching of the sidelink carrier. Alternatively or in addition, the information may indicate the releasing or deactivating of the sidelink carrier.

In some embodiments, the sidelink BWP and the uplink BWP may be the same. Alternatively, the sidelink BWP and the uplink BWP may have a same central frequency but different bandwidths. There can be another counter of an uplink consistent LBT failure detection and another timer of the uplink consistent LBT failure detection. In this this situation where the sidelink BWP at least partially overlaps with the uplink BWP, if one LBT failure on the sidelink is indicated by lower layers (e.g. physical layer) , said counter of the uplink consistent LBT detection can be increased by one and said timer of the uplink consistent LBT failure detection may be started or restarted. Alternatively or in addition, if one LBT failure on the uplink is indicated by lower layers (e.g. physical layer) , the counter of the sidelink consistent LBT detection can be increased by one. The timer of the sidelink consistent LBT detection can also be started or restarted. In this way, the counter is shared between Uu LBT failure and sidelink LBT failure on the same BWP, which can faster the triggering of consistent LBT failure.

As mentioned above, the consistent LBT failure can be detected per sidelink resource pool. The terminal device 110 maintains one counter and one timer for consistent LBT failure detection for each sidelink resource pool. If LBT failure indication has been received from lower layers (e.g. physical layer) for one resource pool, the MAC layer of the terminal device starts or restarts one timer, and increment one counter by 1 corresponding to the resource pool. If the counter is equal to or above a threshold configured, then UE considers consistent LBT failure for the resource pool happens. If the timer expiry, then reset the counter to 0 for the resource pool. In this way, the consistent LBT failure can be detected in a smaller granularity. In this case, if the consistent LBT failure is detected for the current sidelink resource pool, the terminal device 110 may release the current resource pool. Alternatively, the terminal device 110 may suspend the current resource pool. In other embodiments, the terminal device 110 may deactivate the current resource pool.

In some embodiments, if the consistent LBT failure is detected for the current sidelink resource pool, the terminal device 110 may reselect a resource pool for the MAC protocol data units (PDUs) to be transmitted or retransmitted. If all resource pools cannot be used, the terminal device 110 may release (2020) the sidelink communication. Alternatively, the terminal device 110 may suspend (2025) the sidelink communication. In other embodiments, the terminal device 110 may deactivate the sidelink communication. The terminal device 110 may perform (2030) the consistent LBT failure recovery.

The network device 120 may transmit 2050, to the terminal device 110, information indicating whether a configured sidelink grant retransmission is supported at the first terminal device. In some embodiments, the above information may be transmitted in a RRC message. Alternatively, the above information may be transmitted in system information. In this case, if a transmission or retransmission of a MAC protocol data unit (PDU) is failed, the terminal device 110 may retransmit 2055 the MAC PDU to the terminal device 130-1. The failure transmission of MAC PDU can be determined by based on LBT failure indication from lower layer (e.g. physical layer) or based on negative hybrid automatic repeat request (HARQ) feedback received. Alternatively or in addition, if the terminal device 110 does not receive HARQ feedback of the MAC PDU, the terminal device 110 may retransmit 2055 the MAC PDU to the terminal device 130-1. In other words, if physical sidelink feedback channel (PSFCH) reception is absent on the PSFCH reception occasion, the terminal device 110 may retransmit the MAC PDU to the terminal device 130-1. In this way, MAC PDU can be retransmitted using configured sidelink grant, which is benefit for the resource usage.

In some embodiments, the terminal device 110 may configure its peer UE (for example, the terminal device 130) to perform received signal strength indicator (RSSI) and channel occupancy condition to its peer UE. And the terminal device 110 can receive the measurement result from the peer UE and then transmit the measurement result to the network device 120. In this way, the channel condition of its peer UE can be aware. If the channel condition is poor, the, the network/UE can perform some behavior to improve the condition, e.g. switch BWP, carrier. Details are described with the reference to Fig. 3.

The network device 120 may transmit 3010 a sidelink measurement configuration to the terminal device 110. The sidelink measurement can be used for RSSI and channel occupancy measurement. In some embodiments, the sidelink measurement configuration can be transmitted in RRCReconfiguration messages. Alternatively, the sidelink measurement configuration can be transmitted in system information.

The terminal device 110 may transmit 3020 the sidelink measurement configuration to the terminal device 130-1. The terminal device 130-1 may transmit 3030 a RRCReconfiguration sidelink complete message to the terminal device 110.

The terminal device 130-1 may perform 3040 a measurement based on the sidelink measurement configuration. The terminal device 130-1 may transmit 3050 a measurement report to the terminal device 110. In some embodiment, the measurement report of RSSI and channel occupancy can be transmitted periodically. Alternatively, the measurement report can be reported based on a triggered event. For example, if the RRSI or channel occupancy is above a threshold, the measurement report can be transmitted. Alternatively, if the RRSI or channel occupancy is below a threshold, the measurement report can be transmitted. The terminal device 110 may transmit the measurement report to the network device 120.

Fig. 4 shows a flowchart of an example method 400 in accordance with an embodiment of the present disclosure. The method 400 can be implemented at any suitable devices. Only for the purpose of illustrations, the method 400 can be implemented at a terminal device 110 as shown in Fig. 1.

At block 410, the terminal device 110 obtains a configuration of consistent LBT failure detection. The configuration of the consistent LBT failure detection indicates a condition for consistent LBT failure. For example, in some embodiments, the configuration of the consistent LBT failure detection may comprise a threshold value of a counter for the LBT failure. In addition, the configuration of the consistent LBT failure detection may comprise a timer of the counter.

In some embodiments, the terminal device 110 may receive the configuration of the consistent LBT failure detection from the network device 120. For example, the configuration of the consistent LBT failure detection can be transmitted in system information. Alternatively, the configuration of the consistent LBT failure detection may be transmitted in a RRC reconfiguration message.

In some other embodiments, the terminal device 110 may obtain the configuration of the consistent LBT failure detection from preconfigured information. In this case, the terminal device 110 may obtain the configuration of the consistent LBT failure detection when out of the coverage of the network device 120.

At block 420, the terminal device 110 detects a consistent LBT failure for the sidelink communications. In some embodiments, the terminal device 110 may detect the consistent LBT failure per sidelink bandwidth part (BWP) . Alternatively, the terminal device 110 may detect the consistent LBT failure per sidelink resource pool.

In some embodiments, the terminal device 110 may count LBT failure indications from lower layers to the MAC layer. For example, if the LBT failure indication has been received from lower layers (for example, physical layer) , the MAC layer of the terminal device 110 may start or restart the timer and increment one counter by 1. If the counter is equal to or above the threshold value indicated in configuration of the consistent LBT failure detection, it means that the condition for the consistent LBT failure is met. In this case, the consistent LBT failure for the active SL BWP is triggered. If the timer expiry, the terminal device 110 may reset the counter to 0. Alternatively, if the SL BWP is deactivated, the counter can be reset and the timer for detecting the consistent LBT failure can be stopped. In some embodiments, if the consistent LBT failure is detected by the MAC layer, the MAC layer may inform the RRC layer regarding the consistent LBT failure.

In some embodiments, if the condition for the consistent LBT failure is met, the terminal device 110 may release the sidelink communications. In this way, upon detection of consistent LBT failure, the terminal device can stop the sidelink transmission and reception, for power saving.

For example, if the consistent LBT failure is detected per sidelink BWP, the terminal device 110 may release data radio bearers (DRB) of all destination terminal devices or all destination terminal devices working on the sidelink BWP. For example, the terminal device 110 may release the DRBs of all destination terminal devices 110. Alternatively, if the terminal devices 130-1 and 130-2 are working on the sidelink BWP, the terminal device 110 may release the DRBs of the terminal devices 130-1 and 130-2. The term “data radio bearer (DRB) ” used herein can refer to a bearer which transports data between terminal devices or between the terminal device and the network device.

In other embodiments, the terminal device 110 may release service radio bearers (SRB) of all destination terminal devices or all destination terminal devices working on the sidelink BWP. For example, the terminal device 110 may release the SRBs of all destination terminal devices 110. Alternatively, if the terminal devices 130-1 and 130-2 are working on the sidelink BWP, the terminal device 110 may release the SRBs of the terminal devices 130-1 and 130-2. The term “signaling radio bearer (SRB) ” used herein can refer to a type of radio bearer that carries signaling message (for example, RRC or/and non-access stratums (NAS) message) .

Alternatively, the terminal device 110 may discard a sidelink communication related configuration of all destination terminal devices or all destination terminal devices working on the sidelink BWP. For example, the terminal device 110 may discard the sidelink communication related configuration of all destination terminal devices 110. Alternatively, if the terminal devices 130-1 and 130-2 are working on the sidelink BWP, the terminal device 110 may discard the sidelink communication related configuration of the terminal devices 130-1 and 130-2.

In some other embodiments, the terminal device 110 may release PC5-RRC connection for all destination terminal devices or all destination terminal devices working on the sidelink BWP. For example, the terminal device 110 may release the PC5-RRC connection for all destination terminal devices 110. Alternatively, if the terminal devices 130-1 and 130-2 are working on the sidelink BWP, the terminal device 110 may release the PC5-RRC connection for the terminal devices 130-1 and 130-2. In an example embodiment, the terminal device 110 may indicate the release of the PC5-RRC connection for all destination terminal device or all destination terminal devices to an upper layer (for example, PC5 sidelink layer) .

Alternatively, if the the condition for the consistent LBT failure is met, the terminal device 110 may suspend the sidelink communications. In this way, the network can fix the consistent LBT issue by a further RRC Reconfiguration, thus there is no need a release and add of PC5-RRC connection.

For example, if the consistent LBT failure is detected per sidelink BWP, the terminal device 110 may suspend DRBs of all destination terminal devices or all destination terminal devices working on the sidelink BWP. For example, the terminal device 110 may suspend the DRBs of all destination terminal devices 110. Alternatively, if the terminal devices 130-1 and 130-2 are working on the sidelink BWP, the terminal device 110 may suspend the DRBs of the terminal devices 130-1 and 130-2.

In other embodiments, the terminal device 110 may suspend SRBs of all destination terminal devices or all destination terminal devices working on the sidelink BWP. For example, the terminal device 110 may suspend the SRBs of all destination terminal devices 110. Alternatively, if the terminal devices 130-1 and 130-2 are working on the sidelink BWP, the terminal device 110 may suspend the SRBs of the terminal devices 130-1 and 130-2. In some embodiments, the terminal device 110 may suspend sidelink transmissions for the DRBs and the SRBs of all destination terminal devices or all destination terminal devices working on the sidelink BWP.

In other embodiments, the terminal device 110 may suspend a sidelink carrier. Alternatively or in addition, the terminal device 110 may suspend the BWP.

In some other embodiments, the terminal device 110 may suspend PC5-RRC connection for all destination terminal devices or all destination terminal devices working on the sidelink BWP. For example, the terminal device 110 may suspend the PC5-RRC connection for all destination terminal devices 110. Alternatively, if the terminal devices 130-1 and 130-2 are working on the sidelink BWP, the terminal device 110 may suspend the PC5-RRC connection for the terminal devices 130-1 and 130-2. In an example embodiment, the terminal device 110 may indicate the release of the PC5-RRC connection for all destination terminal device or all destination terminal devices to an upper layer (for example, PC5 sidelink layer) or indicate the suspend of the PC5-RRC connection for all destination terminal devices or all destination terminal device working on the sidelink BWP to an upper layer.

In an example embodiment, the terminal device 110 may inform the network device 120 regarding the consistent LBT failure. For example, an information element (IE) or indication can be included in the SidelinkUEInformationNR message to indicate consistent LBT failure of the sidelink.

Alternatively or in addition, the terminal device 110 may inform the network device 120 regarding a radio link failure (RLF) for all destination terminal devices or all destination terminal devices working on the sidelink BWP. For example, the terminal device 110 may set sl-failure as RLF failure.

In other embodiments, the terminal device 110 may transmit BWP information and carrier information of the consistent LBT failure to the network device 120. The BWP information may indicate the BWP ID. The carrier information may indicate a frequency of the carrier.

In other embodiments, if the condition for the consistent LBT failure is met, the terminal device 110 may perform a beam failure recovery. In this way, it can reduce latency.

For example, the terminal device 110 may be provided with a set of resources for the recovery procedure in the BeamFailureRecoveryConfig via RRC message. The beam failure recovery may happen by performing RACH on the best candidate beam selected during the Beam failure recovery procedure. For example, the terminal device 110 may switch to another sidelink BWP or carrier for which the consistent LBT failure has not been triggered. In some embodiments, the terminal device 110 may release the sidelink BWP. Alternatively or in addition, the terminal device 110 may release the sidelink carrier. In some other embodiments, the terminal device 110 may deactivate the sidelink BWP. The terminal device 110 may deactivate the sidelink carrier. In this case, the terminal device 110 may transmit 2035 information to the network device 120. The information may indicate the switch of the sidelink BWP. Alternatively or in addition, the information may indicate the release or deactivate of the sidelink BWP. In other embodiments, the information may indicate the switch of the sidelink carrier. Alternatively or in addition, the information may indicate the release or deactivate of the sidelink carrier.

In some embodiments, the terminal device 110 may receive, form the network device 120, a reconfiguration message for reconfiguring the sidelink communication. In this case, the terminal device 110 may resume the DRBs. Alternatively or in addition, the terminal device 110 may resume the SRBs. In some embodiments, the terminal device 110 may resume the sidelink transmissions for the DRBs and the SRBs. In other embodiments, the terminal device 110 may resume the sidelink carrier. Alternatively or in addition, the terminal device 110 may resume the sidelink BWP. The terminal device 110 may also resume the PC5-RRC connection. In this case, the terminal device 110 may indicate the resuming of the PC5-RRC connection to an upper layer, for example, a MAC layer.

In some embodiments, the sidelink BWP and the uplink BWP may be the same. Alternatively, the sidelink BWP and the uplink BWP may have a same central frequency but different bandwidths. There can be another counter of an uplink consistent LBT failure detection and another timer of the uplink consistent LBT failure detection. In this this situation where the sidelink BWP at least partially overlaps with the uplink BWP, if the LBT failure on the sidelink is detected, said counter of the uplink consistent LBT detection can be increased by one and said timer of the uplink consistent LBT failure detection may be started or restarted. Alternatively or in addition, if the LBT failure on the uplink is detected, the counter of the sidelink consistent LBT detection can be increased by one. The timer of the sidelink consistent LBT detection can also be started or restart. In this way, the counter is shared between Uu LBT failure and sidelink LBT failure on the same BWP, which can faster the triggering of consistent LBT failure.

As mentioned above, the consistent LBT failure can be detected per sidelink resource pool. In this way, the consistent LBT failure can be detected in a smaller granularity. In this case, if the consistent LBT failure is detected for the current sidelink resource pool, the terminal device 110 may release the current resource pool. Alternatively, the terminal device 110 may suspend the current resource pool. In other embodiments, the terminal device 110 may deactivate the current resource pool.

In some embodiments, if the consistent LBT failure is detected for the current sidelink resource pool, the terminal device 110 may reselect another resource pool. If all resource pools cannot be used, the terminal device 110 may release the sidelink communication. Alternatively, the terminal device 110 may suspend the sidelink communication. In other embodiments, the terminal device 110 may deactivate the sidelink communication. The terminal device 110 may perform (the consistent LBT failure recovery.

The terminal device 110 may receive, from the network device 120, information indicating whether a configured sidelink grant retransmission is supported at the first terminal device. In some embodiments, the above information may be transmitted in a RRC message. Alternatively, the above information may be transmitted in system information. In this case, if a transmission of a MAC protocol data unit (PDU) is failed, the terminal device 110 may retransmit the MAC PDU to the terminal device 130-1. Alternatively or in addition, if the terminal device 110 does not receive hybrid automatic repeat request (HARQ) feedback of the MAC PDU, the terminal device 110 may retransmit the MAC PDU to the terminal device 130-1. In other words, if physical sidelink feedback channel (PSFCH) reception is absent on the PSFCH reception occasion, the terminal device 110 may retransmit the MAC PDU to the terminal device 130-1. In this way, MAC PDU can be retransmitted using configured sidelink grant, which is benefit for the resource usage.

In some embodiments, the terminal device 110 may configure its peer UE to perform received signal strength indicator (RSSI) and channel occupancy condition to its peer UE. And the terminal device 110 can report the measurement result back. In this way, the channel condition of its peer UE can be aware. If the channel condition is poor, the, the network/UE can perform some behavior to improve the condition, e.g. switch BWP, carrier.

The terminal device may receive a sidelink measurement configuration from the network device 120. The sidelink measurement can be used for RSSI and channel occupancy measurement. In some embodiments, the sidelink measurement configuration can be transmitted in RRCReconfiguration messages. Alternatively, the sidelink measurement configuration can be transmitted in system information.

The terminal device 110 may transmit the sidelink measurement configuration to the terminal device 130-1. The terminal device 110 may receive a RRCReconfiguration sidelink complete message from the terminal device 130-1.

The terminal device 110 may receive a measurement report from the terminal device 130-1. In some embodiment, the measurement report can be transmitted periodically. Alternatively, the measurement report can be reported based on a triggered event. For example, if the RRSI or channel occupancy is above a threshold, the measurement report can be transmitted. Alternatively, if the RRSI or channel occupancy is below a threshold, the measurement report can be transmitted. The terminal device 110 may transmit the measurement report to the network device 120.

In some embodiment, a first terminal device comprises circuitry configured to obtain a configuration of listen before talk (LBT) failure detection, the configuration indicating a condition for a consistent LBT failure on a sidelink communication; detect a consistent LBT failure for the sidelink communication based on the condition; and in accordance with a determination that the condition is met, perform one of the followings: releasing the sidelink communication, suspending the sidelink communication, or performing a consistent LBT failure recovery for the sidelink communication.

In some embodiment, the first terminal device comprises circuitry configured to obtain receiving the configuration from a network device via system information or a radio resource control (RRC) reconfiguration; or obtain the configuration from preconfigured information.

In some embodiment, the first terminal device comprises circuitry configured to detect the consistent LBT failure for the sidelink communication by detecting the consistent LBT failure per sidelink bandwidth part (BWP) .

In some embodiment, the first terminal device comprises circuitry configured to in accordance with a determination that the sidelink BWP is deactivated, reset a counter for counting a LBT failure for the sidelink communication; and cause a timer for detecting the consistent LBT failure to be stopped.

In some embodiment, the first terminal device comprises circuitry configured to in accordance with a determination that the sidelink BWP at least partially overlaps with an uplink BWP and a determination that a sidelink LBT failure is detected on the sidelink BWP, increasing a counter of an uplink consistent LBT failure detection by one; and start or restart a timer of the uplink consistent LBT failure detection.

In some embodiment, the first terminal device comprises circuitry configured to in accordance with a determination that the sidelink BWP at least partially overlaps with an uplink BWP and a determination that an uplink LBT failure is detected on the uplink BWP, increasing a counter for counting the consistent LBT failure by one; and start or restart a timer of the consistent LBT failure detection.

In some embodiment, the first terminal device comprises circuitry configured to release the sidelink communication by at least one of: releasing data radio bearers (DRBs) of all destination terminal devices or all destination terminal devices working on the sidelink BWP; releasing signaling radio bearers (SRBs) of all destination terminal devices or all destination terminal devices working on the sidelink BWP; discarding a sidelink communication related configuration of all destination terminal devices or all destination terminal devices working on the sidelink BWP; resetting a sidelink specific MAC of all destination terminal devices or all destination terminal devices working on the sidelink BWP; releasing PC5-RRC connection for all destination terminal devices or all destination terminal devices working on the sidelink BWP; indicating the release of the PC5-RRC connection for all destination terminal device or all destination terminal devices to an upper layer; informing a network device regarding the consistent LBT failure; informing the network device regarding a radio link failure (RLF) for all destination terminal devices or all destination terminal devices working on the sidelink BWP; or transmitting, to the network device, BWP information and carrier information of the consistent LBT failure.

In some embodiment, the first terminal device comprises circuitry configured to suspend the sidelink communication by at least one of: suspending DRBs of all destination terminal devices or all destination terminal devices working on the sidelink BWP; suspending SRBs of all destination terminal devices or all destination terminal devices working on the sidelink BWP; suspending sidelink transmissions for the DRBs and the SRBs of all destination terminal devices or all destination terminal devices working on the sidelink BWP; resetting a sidelink specific MAC of all destination terminal devices or all destination terminal devices working on the sidelink BWP; suspending a sidelink carrier and/or the sidelink BWP; suspending PC5-RRC connection for all destination terminal devices or all destination terminal devices working on the sidelink BWP; indicating the suspend of the PC5-RRC connection for all destination terminal devices or all destination terminal device working on the sidelink BWP to an upper layer; informing a network device regarding the consistent LBT failures; informing the network device regarding radio link failure (RLF) for all destination terminal devices or all destination terminal devices working on the sidelink BWP; or transmitting, to the network device, BWP information and carrier information of the consistent LBT failures.

In some embodiment, the first terminal device comprises circuitry configured to receive, from a network device, a reconfiguration message for reconfiguring the sidelink communication; and perform at least one of: resuming the DRBs; resuming the SRBs; resuming the sidelink transmissions for the DRBs and the SRBs; resuming the sidelink carrier and/or sidelink BWP; resuming the PC5-RRC connection; or indicating the resuming of the PC5-RRC connection to an upper layer.

In some embodiment, the first terminal device comprises circuitry configured to perform the consistent LBT failure recovery comprises at least one of: switching to another sidelink BWP or carrier for which the consistent LBT failure has not been triggered; releasing the sidelink BWP or a sidelink carrier; or deactivating the sidelink BWP or the sidelink carrier.

In some embodiment, the first terminal device comprises circuitry configured to transmit, to a network device, information indicating at least one of: the switching of the sidelink BWP; the releasing or deactivating of the sidelink BWP; the switching of the sidelink carrier; or the releasing or deactivating the sidelink carrier.

In some embodiment, the first terminal device comprises circuitry configured to detect the consistent LBT failure by: detecting the consistent LBT failure per sidelink resource pool.

In some embodiment, the first terminal device comprises circuitry configured to in accordance with a determination with a detection of the consistent LBT failure for a current sidelink resource pool, perform at least one of: releasing the current resource pool; suspending the current resource pool; or deactivating the current resource pool.

In some embodiment, the first terminal device comprises circuitry configured to in accordance with a determination with a detection of the consistent LBT failure for a current sidelink resource pool, reselect another resource pool.

In some embodiment, the first terminal device comprises circuitry configured to in accordance with a determination that all resource pools cannot be used, perform one of the followings: releasing the sidelink communication, suspending the sidelink communication, performing the consistent LBT failure recovery for the sidelink communication.

In some embodiment, the first terminal device comprises circuitry configured to detect the consistent LBT failure for the sidelink communication by: counting a LBT failure indication received at a medium access control (MAC) entity from a lower layer.

In some embodiment, the first terminal device comprises circuitry configured to receive, from a network device, information indicating whether a configured sidelink grant retransmission is supported at the first terminal device; and in accordance with a determination that the configured sidelink grant retransmission is supported and a determination with a failure transmission of a MAC protocol data unit (PDU) or no reception of hybrid automatic repeat request (HARQ) feedback of the MAC PDU, retransmit the MAC PDU using the configured sidelink grant.

In some embodiment, the first terminal device comprises circuitry configured to receive, from a network device, a sidelink measurement configuration for sidelink received signal strength indicator (RSSI) and channel occupancy measurement; transmit, to a second terminal device, the sidelink measurement configuration for sidelink RSSI and channel occupancy measurement; receive, from the second terminal device, a measurement report of sidelink RSSI and channel occupancy measurement; and transmit, to the network device, the measurement report of sidelink RSSI and channel occupancy measurement.

Fig. 5 is a simplified block diagram of a device 500 that is suitable for implementing embodiments of the present disclosure. The device 500 can be considered as a further example implementation of the terminal device 110 and the network device 120 as shown in Fig. 1. Accordingly, the device 500 can be implemented at or as at least a part of the terminal device 110.

As shown, the device 500 includes a processor 510, a memory 520 coupled to the processor 510, a suitable transmitter (TX) and receiver (RX) 540 coupled to the processor 510, and a communication interface coupled to the TX/RX 540. The memory 520 stores at least a part of a program 530. The TX/RX 540 is for bidirectional communications. The TX/RX 540 has at least one antenna to facilitate communication, though in practice an Access Node mentioned in this application may have several ones. The communication interface may represent any interface that is necessary for communication with other network elements, such as X2 interface for bidirectional communications between eNBs, S1 interface for communication between a Mobility Management Entity (MME) /Serving Gateway (S-GW) and the eNB, Un interface for communication between the eNB and a relay node (RN) , or Uu interface for communication between the eNB and a terminal device.

The program 530 is assumed to include program instructions that, when executed by the associated processor 510, enable the device 500 to operate in accordance with the embodiments of the present disclosure, as discussed herein with reference to Fig. 2 to 4. The embodiments herein may be implemented by computer software executable by the processor 510 of the device 500, or by hardware, or by a combination of software and hardware. The processor 510 may be configured to implement various embodiments of the present disclosure. Furthermore, a combination of the processor 510 and memory 520 may form processing means 550 adapted to implement various embodiments of the present disclosure.

The memory 520 may be of any type suitable to the local technical network and may be implemented using any suitable data storage technology, such as a non-transitory computer readable storage medium, semiconductor-based memory devices, magnetic memory devices and systems, optical memory devices and systems, fixed memory and removable memory, as non-limiting examples. While only one memory 520 is shown in the device 500, there may be several physically distinct memory modules in the device 500. The processor 510 may be of any type suitable to the local technical network, and may include one or more of general purpose computers, special purpose computers, microprocessors, digital signal processors (DSPs) and processors based on multicore processor architecture, as non-limiting examples. The device 500 may have multiple processors, such as an application specific integrated circuit chip that is slaved in time to a clock which synchronizes the main processor.

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

The present disclosure also provides at least one computer program product tangibly stored on a non-transitory computer readable storage medium. The computer program product includes computer-executable instructions, such as those included in program modules, being executed in a device on a target real or virtual processor, to carry out the process or method as described above with reference to any of Figs. 2-4. Generally, program modules include routines, programs, libraries, objects, classes, components, data structures, or the like that perform particular tasks or implement particular abstract data types. The functionality of the program modules may be combined or split between program modules as desired in various embodiments. Machine-executable instructions for program modules may be executed within a local or distributed device. In a distributed device, program modules may be located in both local and remote storage media.

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

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

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

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

Claims

A communication method, comprising:

obtaining, at a first terminal device, a configuration of consistent listen before talk (LBT) failure detection, the configuration indicating a condition for a consistent LBT failure on a sidelink communication;

detecting a consistent LBT failure for the sidelink communication based on the condition; and

in accordance with a determination that the condition is met, performing one of the followings:

releasing the sidelink communication,

suspending the sidelink communication, or

performing a consistent LBT failure recovery for the sidelink communication.
The method of claim 1, wherein obtaining the configuration comprises:

receiving the configuration from a network device via system information or a radio resource control (RRC) reconfiguration; or

obtaining the configuration from preconfigured information.
The method of claim 1, wherein detecting the consistent LBT failure for the sidelink communication comprises:

detecting the consistent LBT failure per sidelink bandwidth part (BWP) .
The method of claim 3, further comprising:

in accordance with a determination that the sidelink BWP is deactivated, resetting a counter for counting a LBT failure for the sidelink communication ; and

causing a timer for detecting the consistent LBT failure to be stopped.
The method of claim 3, further comprising:

in accordance with a determination that the sidelink BWP at least partially overlaps with an uplink BWP and a determination that a sidelink LBT failure is detected on the sidelink BWP, increasing a value of a counter of an uplink consistent LBT failure detection by one; and

starting or restarting a timer of the uplink consistent LBT failure detection.
The method of claim 3, further comprising:

in accordance with a determination that the sidelink BWP at least partially overlaps with an uplink BWP and a determination that an uplink LBT failure is detected on the uplink BWP, increasing a value of a counter for counting the consistent LBT failure by one; and

starting or restarting a timer of the consistent LBT failure detection.
The method of claim 3, wherein releasing the sidelink communication comprises at least one of:

releasing data radio bearers (DRBs) of all destination terminal devices or all destination terminal devices working on the sidelink BWP;

releasing signaling radio bearers (SRBs) of all destination terminal devices or all destination terminal devices working on the sidelink BWP;

discarding a sidelink communication related configuration of all destination terminal devices or all destination terminal devices working on the sidelink BWP;

resetting a sidelink specific MAC of all destination terminal devices or all destination terminal devices working on the sidelink BWP;

releasing PC5-RRC connection for all destination terminal devices or all destination terminal devices working on the sidelink BWP;

indicating the release of the PC5-RRC connection for all destination terminal device or all destination terminal devices to an upper layer;

informing a network device regarding the consistent LBT failure;

informing the network device regarding a radio link failure (RLF) for all destination terminal devices or all destination terminal devices working on the sidelink BWP; or

transmitting, to the network device, BWP information and carrier information of the consistent LBT failure.
The method of claim 3, wherein suspending the sidelink communication comprises at least one of:

suspending DRBs of all destination terminal devices or all destination terminal devices working on the sidelink BWP;

suspending SRBs of all destination terminal devices or all destination terminal devices working on the sidelink BWP;

suspending sidelink transmissions for the DRBs and the SRBs of all destination terminal devices or all destination terminal devices working on the sidelink BWP;

resetting a sidelink specific MAC of all destination terminal devices or all destination terminal devices working on the sidelink BWP;

suspending a sidelink carrier and/or the sidelink BWP;

suspending PC5-RRC connection for all destination terminal devices or all destination terminal devices working on the sidelink BWP;

indicating the suspend of the PC5-RRC connection for all destination terminal devices or all destination terminal device working on the sidelink BWP to an upper layer;

informing a network device regarding the consistent LBT failures;

informing the network device regarding radio link failure (RLF) for all destination terminal devices or all destination terminal devices working on the sidelink BWP; or

transmitting, to the network device, BWP information and carrier information of the consistent LBT failures.
The method of claim 8, further comprising:

receiving, from a network device, a reconfiguration message for reconfiguring the sidelink communication; and

performing at least one of:

resuming the DRBs;

resuming the SRBs;

resuming the sidelink transmissions for the DRBs and the SRBs;

resuming the sidelink carrier and/or sidelink BWP;

resuming the PC5-RRC connection; or

indicating the resuming of the PC5-RRC connection to an upper layer.
The method of claim 3, wherein performing the consistent LBT failure recovery comprises at least one of:

switching to another sidelink BWP or carrier for which the consistent LBT failure has not been triggered;

releasing the sidelink BWP or a sidelink carrier; or

deactivating the sidelink BWP or the sidelink carrier.
The method of claim 10, further comprising:

transmitting, to a network device, information indicating at least one of:

the switching of the sidelink BWP;

the releasing or deactivate of the sidelink BWP;

the switching of the sidelink carrier; or

the releasing or deactivating the sidelink carrier.
The method of claim 1, wherein detecting the consistent LBT failure comprises:

detecting the consistent LBT failure per sidelink resource pool.
The method of claim 12, further comprising:

in accordance with a determination with a detection of the consistent LBT failure for a current sidelink resource pool, performing at least one of:

releasing the current resource pool;

suspending the current resource pool; or

deactivating the current resource pool.
The method of claim 13, further comprising:

in accordance with a determination with a detection of the consistent LBT failure for a current sidelink resource pool, reselecting another resource pool.
The method of claim 13, further comprising:

in accordance with a determination that all resource pools cannot be used, performing one of the followings:

releasing the sidelink communication,

suspending the sidelink communication,

performing the consistent LBT failure recovery for the sidelink communication.
The method of claim 1, wherein detecting the consistent LBT failure for the sidelink communication comprises:

counting a LBT failure indication received at a medium access control (MAC) entity from a lower layer.
The method of claim 1, further comprising:

receiving, from a network device, information indicating whether a configured sidelink grant retransmission is supported at the first terminal device; and

in accordance with a determination that the configured sidelink grant retransmission is supported and a determination with a failure transmission of a MAC protocol data unit (PDU) or no reception of hybrid automatic repeat request (HARQ) feedback of the MAC PDU, retransmitting the MAC PDU using the configured sidelink grant.
The method of claim 1, further comprising:

receiving, from a network device, a sidelink measurement configuration for sidelink received signal strength indicator (RSSI) and channel occupancy measurement;

transmitting, to a second terminal device, the sidelink measurement configuration for sidelink RSSI and channel occupancy measurement;

receiving, from the second terminal device, a measurement report of sidelink RSSI and channel occupancy measurement; and

transmitting, to the network device, the measurement report of sidelink RSSI and channel occupancy measurement.
A terminal device comprising:

a processor; and

a memory coupled to the processor and storing instructions thereon, the instructions, when executed by the processor, causing the terminal device to perform the method according to any of claims 1 to 18.
A computer readable medium having instructions stored thereon, the instructions, when executed on at least one processor, causing the at least one processor to perform the method according to any of claims 1 to 18.