WO2024229835A1

WO2024229835A1 - Devices and methods for communication

Info

Publication number: WO2024229835A1
Application number: PCT/CN2023/093660
Authority: WO
Inventors: You Li; Gang Wang
Original assignee: NEC Corp
Current assignee: NEC Corp
Priority date: 2023-05-11
Filing date: 2023-05-11
Publication date: 2024-11-14
Anticipated expiration: 2025-11-11

Abstract

Embodiments of the present disclosure provide a solution for multi-path configuration. In a solution, a first terminal device receives, first information from a second terminal device, wherein the first terminal device communicates with both a first network device via a direct path and a second network device via an indirect path comprising a first hop between the first terminal device and the second terminal device and a second hop between the second terminal device and the second network device, and wherein the first information indicates a handover procedure of the second terminal device; and performs one of the following: initiating a radio resource control (RRC) reestablishment procedure; or transmitting, to the first network device, second information indicating the handover procedure of the second terminal device.

Description

DEVICES AND METHODS FOR COMMUNICATION

FIELDS

Example embodiments of the present disclosure generally relate to the field of communication techniques and in particular, to devices and methods for multi-path configuration.

BACKGROUND

Recently, a technology of multi-path is proposed to be supported to enhance reliability and throughput. Specifically, a user equipment (UE) is allowed to communicate with the network via more than one path, such as, both a direct path and an indirect path, and the UE may switch among or utilize the multiple paths simultaneously. Further, the indirect path comprises a first hop between the UE and a relay UE and a second hop between the relay UE and the network device. According to current agreements, the first hop may be either a PC5 connection or a non-PC5 connection.

In some cases, the UE may connect with a same network device via the multiple paths, which is referred to as intra-gNB multi-path for brevity. In some other cases, the multiple paths of the UE may connect with more than one different network device, which is referred to as inter-gNB multi-path for brevity. In both of the intra-gNB multi-path and the inter-gNB multi-path scenarios, the relay device may occur some abnormal events, including but not limited to, handover, transitioning in a non-connected state, a radio link failure (RLF) , a failure of reestablishment and on so. If such abnormal events are not well handled, the communication may be interpreted.

SUMMARY

In general, embodiments of the present disclosure provide a solution for multi-path configuration.

In a first aspect, there is provided a first terminal device comprising: a processor configured to cause the first terminal device to: receive, first information from a second terminal device, wherein the first terminal device communicates with both a first network device via a direct path and a second network device via an indirect path comprising a first hop between the first terminal device and the second terminal device and a second hop between the second terminal device and the second network device, and wherein the first information indicates a handover procedure of the second terminal device; and perform one of the following: initiating a radio resource control (RRC) reestablishment procedure; or transmitting, to the first network device, second information indicating the handover procedure of the second terminal device.

In a second aspect, there is provided a second terminal device comprising: a processor configured to cause the second terminal device to: perform a handover procedure; and transmit, first information to a first terminal device, wherein the first terminal device communicates with both a first network device via a direct path and a second network device via an indirect path comprising a first hop between the first terminal device and the second terminal device and a second hop between the second terminal device and the second network device, and wherein the first information indicates the handover procedure.

In a third aspect, there is provided a first terminal device comprising: a processor configured to cause the first terminal device to: transmit, to a network device, a first message indicating a radio link failure (RLF) of a second terminal device, wherein the first terminal device was configured with an indirect path via the second terminal device; and receive, from the second terminal device, a second message indicating whether a reestablishment procedure of the second terminal device is successful.

In a fourth aspect, there is provided a second terminal device comprising: a processor configured to cause the second terminal device to: perform a reestablishment procedure after a radio link failure (RLF) of the second terminal device; and transmit, to a first terminal device, a second message indicating whether the reestablishment procedure of the second terminal device is successful, wherein the first terminal device was configured with an indirect path via the second terminal device.

In a fifth aspect, there is provided a network device comprising: a processor configured to cause the network device to: receive, from a first terminal device served by the network device, a first message indicating a radio link failure (RLF) of a second terminal device, wherein the first terminal device was configured with an indirect path via the second terminal device; and receive, from the first terminal device, one of the following: a fifth message indicating that a reestablishment procedure of the second terminal device is unsuccessful, or a sixth message indicating that the reestablishment procedure of the second terminal device is successful.

In a sixth aspect, there is provided a first terminal device comprising: a processor configured to cause the first terminal device to: receive, from a network device, a configuration used for configuring an indirect path for the first terminal device, wherein the indirect path comprises a first hop between the first terminal device and a second terminal device and a second hop between the second terminal device and the network device, and wherein the second hop is a non-PC5 hop; and perform at least one of the following: prior to receiving the configuration, reporting the second terminal device as a candidate relay terminal device to the network device in accordance with a determination that the second terminal device is in a connected state, wherein the second terminal device belongs to a plurality of second terminal devices pre-configured to the first terminal device; or triggering the second terminal device to transition in an idle state, an inactive state or a connected state.

In a seventh aspect, there is provided a second terminal device comprising: a processor configured to cause the second terminal device to: receive, from a network device, a configuration used for configuring the second terminal device to be a relay terminal device for a first terminal device, wherein a connection between the first terminal device and the second terminal device is a non-PC5 hop; and identify the second terminal device by different identities according to different states of the second terminal device.

In an eighth aspect, there is provided a second terminal device comprising: a processor configured to cause the second terminal device to: transition in a non-connected state, wherein a first terminal device was configured with an indirect path via the second terminal device and the transitioning is tigered by the second terminal device; and upon the transitioning, transmit a notification to the first terminal device, the notification comprising a cause indicating at least one of the following: a Uu interface failure of the second terminal device, a Uu radio resource control (RRC) failure of the second terminal device, an indirect path failure, or an expiry of a timer, upon an expiry of which the second terminal device transitions in the non-connected state.

In a ninth aspect, there is provided a second terminal device comprising: a processor configured to cause the second terminal device to: receive, from a network device, a configuration used for configuring the second terminal device to be a relay device for a first terminal device; and ignore a timer upon an expiry of which the second terminal device transitions in the idle state.

In a tenth aspect, there is provided a first terminal device comprising: a processor configured to cause the first terminal device to: receive, from a second terminal device a notification transmitted upon the second terminal device transitioning in an idle state, a first terminal device being configured with an indirect path via the second terminal device and the transitioning being tigered by the second terminal device, the notification comprising a cause indicating at least one of the following: a Uu interface failure of the second terminal device, a Uu radio resource control (RRC) failure of the second terminal device, an indirect path failure, or an expiry of a timer, upon an expiry of which the second terminal device transitions in the idle state.

In an eleventh aspect, there is provided a communication method performed by a first terminal device. The method comprises: receiving, first information from a second terminal device, wherein the first terminal device communicates with both a first network device via a direct path and a second network device via an indirect path comprising a first hop between the first terminal device and the second terminal device and a second hop between the second terminal device and the second network device, and wherein the first information indicates a handover procedure of the second terminal device; and performing one of the following: initiating a radio resource control (RRC) reestablishment procedure; or transmitting, to the first network device, second information indicating the handover procedure of the second terminal device.

In a twelfth aspect, there is provided a communication method performed by a second terminal device. The method comprises: performing a handover procedure; and transmitting, first information to a first terminal device, wherein the first terminal device communicates with both a first network device via a direct path and a second network device via an indirect path comprising a first hop between the first terminal device and the second terminal device and a second hop between the second terminal device and the second network device, and wherein the first information indicates the handover procedure.

In a thirteenth aspect, there is provided a communication method performed by a first terminal device. The method comprises: transmitting, to a network device, a first message indicating a radio link failure (RLF) of a second terminal device, wherein the first terminal device was configured with an indirect path via the second terminal device; and receiving, from the second terminal device, a second message indicating whether a reestablishment procedure of the second terminal device is successful.

In a fourteenth aspect, there is provided a communication method performed by a second terminal device. The method comprises: performing a reestablishment procedure after a radio link failure (RLF) of the second terminal device; and transmitting, to a first terminal device, a second message indicating whether the reestablishment procedure of the second terminal device is successful, wherein the first terminal device was configured with an indirect path via the second terminal device.

In a fifteenth aspect, there is provided a communication method performed by a network device. The method comprises: receiving, from a first terminal device served by the network device, a first message indicating a radio link failure (RLF) of a second terminal device, wherein the first terminal device was configured with an indirect path via the second terminal device; and receiving, from the first terminal device, one of the following: a fifth message indicating that a reestablishment procedure of the second terminal device is unsuccessful, or a sixth message indicating that the reestablishment procedure of the second terminal device is successful.

In a sixteenth aspect, there is provided a communication method performed by a first terminal device. The method comprises: receiving, from a network device, a configuration used for configuring an indirect path for the first terminal device, wherein the indirect path comprises a first hop between the first terminal device and a second terminal device and a second hop between the second terminal device and the network device, and wherein the second hop is a non-PC5 hop; and performing at least one of the following: prior to receiving the configuration, reporting the second terminal device as a candidate relay terminal device to the network device in accordance with a determination that the second terminal device is in a connected state, wherein the second terminal device belongs to a plurality of second terminal devices pre-configured to the first terminal device; or triggering the second terminal device to transition in an idle state, an inactive state or a connected state.

In a seventeenth aspect, there is provided a communication method performed by a second terminal device. The method comprises: receiving, from a network device, a configuration used for configuring the second terminal device to be a relay terminal device for a first terminal device, wherein a connection between the first terminal device and the second terminal device is a non-PC5 hop; and identifying the second terminal device by different identities according to different states of the second terminal device.

In an eighteenth aspect, there is provided a communication method performed by a second terminal device. The method comprises: transitioning in a non-connected state, wherein a first terminal device was configured with an indirect path via the second terminal device and the transitioning is tigered by the second terminal device; and upon the transitioning, transmitting a notification to the first terminal device, the notification comprising a cause indicating at least one of the following: a Uu interface failure of the second terminal device, a Uu radio resource control (RRC) failure of the second terminal device, an indirect path failure, or an expiry of a timer, upon an expiry of which the second terminal device transitions in the non-connected state.

In a nineteenth aspect, there is provided a communication method performed by a second terminal device. The method comprises: receiving, from a network device, a configuration used for configuring the second terminal device to be a relay device for a first terminal device; and ignoring a timer upon an expiry of which the second terminal device transitions in the idle state.

In a twentieth aspect, there is provided a communication method performed by a first terminal device. The method comprises: receiving, from a second terminal device a notification transmitted upon the second terminal device transitioning in an idle state, a first terminal device being configured with an indirect path via the second terminal device and the transitioning being tigered by the second terminal device, the notification comprising a cause indicating at least one of the following: a Uu interface failure of the second terminal device, a Uu radio resource control (RRC) failure of the second terminal device, an indirect path failure, or an expiry of a timer, upon an expiry of which the second terminal device transitions in the idle state.

In a twenty-first aspect, there is provided a computer readable medium having instructions stored thereon, the instructions, when executed on at least one processor, causing the at least one processor to carry out the method according to the eleventh, twelfth, thirteenth, fourteenth, fifteenth, sixteenth, seventeenth, eighteenth, nineteenth, or twentieth 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:

FIG. 1A and 1B illustrate example communication environments in which example embodiments of the present disclosure can be implemented;

FIG. 2 illustrates a signaling flow of communication in accordance with some embodiments of the present disclosure;

FIG. 3 illustrates a signaling flow of communication in accordance with some embodiments of the present disclosure;

FIG. 4A and 4B illustrate signaling flows of communication in accordance with some embodiments of the present disclosure;

FIG. 5 illustrates a flowchart of a method implemented at a first terminal device according to some example embodiments of the present disclosure;

FIG. 6 illustrates a flowchart of a method implemented at a second terminal device according to some example embodiments of the present disclosure;

FIG. 7 illustrates a flowchart of a method implemented at a first terminal device according to some example embodiments of the present disclosure;

FIG. 8 illustrates a flowchart of a method implemented at a second terminal device according to some example embodiments of the present disclosure;

FIG. 9 illustrates a flowchart of a method implemented at a network device according to some example embodiments of the present disclosure;

FIG. 10 illustrates a flowchart of a method implemented at a first terminal device according to some example embodiments of the present disclosure;

FIG. 11 illustrates a flowchart of a method implemented at a second terminal device according to some example embodiments of the present disclosure;

FIG. 12 illustrates a flowchart of a method implemented at a second terminal device according to some example embodiments of the present disclosure;

FIG. 13 illustrates a flowchart of a method implemented at a second terminal device according to some example embodiments of the present disclosure;

FIG. 14 illustrates a flowchart of a method implemented at a first terminal device according to some example embodiments of the present disclosure;

FIG. 15 illustrates a simplified block diagram of an apparatus that is suitable for implementing example embodiments of the present disclosure.

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

DETAILED DESCRIPTION

Principle of the present disclosure will now be described with reference to some 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 limitation as to the scope of the disclosure. Embodiments 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, devices on vehicle for V2X communication where X means pedestrian, vehicle, or infrastructure/network, devices for Integrated Access and Backhaul (IAB) , Space borne vehicles or Air borne vehicles in Non-terrestrial networks (NTN) including Satellites and High Altitude Platforms (HAPs) encompassing Unmanned Aircraft Systems (UAS) , eXtended Reality (XR) devices including different types of realities such as Augmented Reality (AR) , Mixed Reality (MR) and Virtual Reality (VR) , the unmanned aerial vehicle (UAV) commonly known as a drone which is an aircraft without any human pilot, devices on high speed train (HST) , or image capture devices such as digital cameras, sensors, gaming devices, music storage and playback appliances, or Internet appliances enabling wireless or wired Internet access and browsing and the like. The ‘terminal device’ can further has ‘multicast/broadcast’ feature, to support public safety and mission critical, V2X applications, transparent IPv4/IPv6 multicast delivery, IPTV, smart TV, radio services, software delivery over wireless, group communications and IoT applications. It may also incorporate one or multiple Subscriber Identity Module (SIM) as known as Multi-SIM. The term “terminal device” can be used interchangeably with a UE, a mobile station, a subscriber station, a mobile terminal, a user terminal or a wireless device.

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

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

The terminal or the network device may work on several frequency ranges, e.g., FR1 (e.g., 450 MHz to 6000 MHz) , FR2 (e.g., 24.25GHz to 52.6GHz) , frequency band larger than 100 GHz as well as Tera Hertz (THz) . It can further work on licensed/unlicensed/shared spectrum. The terminal device may have more than one connection with the network devices under Multi-Radio Dual Connectivity (MR-DC) application scenario. The terminal device or the network device can work on full duplex, flexible duplex and cross division duplex modes.

The embodiments of the present disclosure may be performed in test equipment, e.g., signal generator, signal analyzer, spectrum analyzer, network analyzer, test terminal device, test network device, channel emulator. In some embodiments, the terminal device may be connected with a first network device and a second network device. One of the first network device and the second network device may be a master node and the other one may be a secondary node. The first network device and the second network device may use different radio access technologies (RATs) . In some embodiments, the first network device may be a first RAT device and the second network device may be a second RAT device. In some embodiments, the first RAT device is eNB and the second RAT device is gNB. Information related with different RATs may be transmitted to the terminal device from at least one of the first network device or the second network device. In some embodiments, first information may be transmitted to the terminal device from the first network device and second information may be transmitted to the terminal device from the second network device directly or via the first network device. In some embodiments, information related with configuration for the terminal device configured by the second network device may be transmitted from the second network device via the first network device. Information related with reconfiguration for the terminal device configured by the second network device may be transmitted to the terminal device from the second network device directly or via the first network device.

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

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

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

As discussed above, the technology of multi-path is proposed to be supported to enhance reliability and throughput, where the UE is allowed to communicate with the network via more than one path, such as, both a direct path and an indirect path. Further, both intra-gNB multi-path and inter-gNB multi-path scenarios are expected to be supported.

In both of the intra-gNB multi-path and the inter-gNB multi-path scenarios, the relay device may occur some abnormal events, including but not limited to, handover, transitioning in a non-connected state, an RLF, a failure of reestablishment and on so. If such abnormal events are not well handled, the communication may be interpreted.

According to the present disclosure, at least part of the above-mentioned abnormal events may be well handed.

For ease of discussion, some terms used in the following description are listed as below:

● A direct network connection mode: refers to one mode of network connection, where there is no relay terminal device/relay UE between a terminal device and the network device.

● An indirect network connection mode: refers to one mode of network connection, where there is a relay terminal device/relay UE between a remote terminal device and the network devices.

● An indirect path/link/connection: refers to a path between a network device and a remote terminal device via a relay terminal device or multiple relay terminal devices, also referred to as a relay/relaying path sometimes. Further, the indirect path comprises a first hop be-tween a remote terminal device and a relay terminal device and a second hop between a relay terminal device and a network device. In view of this, the indirect path also may be identified by the first hop or the second hop.

● A first hop/link: refers to a hop between a remote terminal device and a relay terminal device, also referred to as a UE-UE hop.

● A second hop/link: refers to a hop between a relay terminal device and a network device.

● A non-PC5 entity/path/link/connection/interface: refers to an entity/path/link/connec-tion/interface which is not stipulated by the standard documents (such as, 3GPP specifica-tion) or is an ideal path/link/connection. Also may be referred to as non-3GPP en-tity/path/link/connection/interface. Further, a non-standardized/path/link/connection/in-terface also may be referred to as ideal/path/link/connection. It may be wired or wireless entity/path/link/connection/interface. Examples of non-PC5 entity/path/link/connection, include but are not limited to, Wi-Fi entity/path/link, bluetooth entity/path/link, zigbee en-tity/path/link, Ethernet entity/path/link.

● A PC5 entity/path/link/connection/interface: refers to an entity/path/link/connection which is stipulated by the standard documents (such as, 3GPP specification) .

In the present discourse, terms “hop” , “link” , “path” and “connection” may be used interchangeably.

In some embodiments, in case of RRC connection reestablishment, the terminal device may transmit an RRCReestablishmentRequest to the network device, and receive an RRCReestablishment from the network device. If the reestablishment is successful, the terminal device may respond an RRCReestablishmentComplete to the network device.

In some embodiments, in case of RRC reestablishment fallback to RRC establishment, the terminal device may transmit an RRCReestablishmentRequest to the network device, and receive an RRCSetup from the network device. If the reestablishment is successful, the terminal device may respond an RRCSetupComplete to the network device.

In view of the above, an RRC reestablishment may be considered to be successful if the terminal device transmits the RRCReestablishmentRequest to the network device, transmits the RRCReestablishmentComplete to the network device, transmits the RRCSetupComplete to the network device or receives the RRCSetup from the network device.

Accordingly, an RRC reestablishment may be considered to be failed if the T311 or the T301 expires.

Terms “reestablishment” and “ (Uu) recovery” may be used interchangeably.

Further, in case of multi-path scenario, the remote terminal device may be served by one or more network device. In other words, the remote terminal device may have more than one serving network device. Merely for ease of discussion, the network device which has a Uu connection with the remote terminal device may be referred to as the serving network device of the remote terminal device.

In the following, a scenario of intra-gNB multi-path relaying will be used as an example of application scenario for describing some specific example embodiments of the present disclosure. It is noted that example embodiments described with regard to the intra-gNB are equally applicable to scenario of inter-gNB multi-path relaying. Similarly, those example embodiments described with regard to the scenario of inter-gNB multi-path relaying are equally applicable to the scenario of intra-gNB multi-path relaying.

In the following, two-path scenario may be used as an example of the multi-path scenario for describing some specific example embodiments of the present disclosure. It is noted that more paths may be involved for the multi-path scenario.

In the following, in case of the two-path scenario, the remote terminal device is described to be configured with a direct path and an indirect path. It should be understood that, in the other embodiments, the direct path may be replaced with another indirect path. Merely for brevity, the same or similar contents are omitted here.

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

EXAMPLE OF COMMUNICATION NETWORK

FIG. 1A shows an example communication environment 100A in which example embodiments of the present disclosure can be implemented. The communication environment 100 comprises a plurality of terminal devices and one or more network devices. As shown in the FIG. 1A, the communication environment 100A comprises a network device 130-1 and an optional network device 130-2, collectively referred to as network device 130 or individually referred to as a first network device 130-1 or a second network device 130-2.

Further, the communication environment 100 also comprises terminal devices 110 and 120. Further, as illustrated in FIG. 1A, the terminal device 110 may communicate with the network device (s) 130 via a plurality of paths (also referred to as multi-path) , where each of the plurality of paths may be either a direct path or an indirect path (including a first hop and a second hop) .

In some embodiments, the remote terminal device 110 may be connected to the network device 130 by using one direct path and one indirect path via layer-2 UE-to-network relay, referred to as scenario #1 sometimes. Alternately, in some embodiments, the remote terminal device 110 may be connected to the network device 130 by using one direct path and one indirect path via the relay terminal device 120 (where the UE-UE inter-connection is assumed to be ideal, referred to as scenario #2 sometimes) .

In summary, the remote terminal device 110 may communicate with the network device 130 via any of the following paths:

A direct path, where the remote terminal device 110 is connected to the network device 130 directly.

An indirect path where the first hop is a PC5 connection. Specifically, the remote terminal device 110 is connected to the network device 130 via the relay terminal device 120, and the path between the remote terminal device 110 and the relay terminal device 120 is PC5/sidelink (SL) path.

An indirect path where the first hop is a non-PC5 connection. Specifically, the remote terminal device 110 is connected to the network device 130 via the relay terminal device 120, and the path between the remote terminal device 110 and the relay terminal device 120 is a non-PC5 connection.

As shown in FIG. 1A, the terminal device 110 may communicate with the network device 130 via the terminal device 120. In view of this, the terminal device 110 also may be referred to as a remote terminal device 110, and the terminal device 120 also may be referred to as a relay terminal device 120.

Further, both of the intra-gNB multi-path and the inter-gNB multi-path scenarios are supported. In case of the intra-gNB multi-path scenario, the first terminal device 110 is connected with the first network device 130-1 via the direct path (or an indirect path) and the indirect path comprising the second terminal device. In case of the inter-gNB multi-path scenario, the first terminal device 110 is connected with the first network device 130-1 via the direct path (or an indirect path) and connected with the second network device 130-2 via the indirect path comprising the second terminal device.

Further, in both of the intra-gNB multi-path and the inter-gNB multi-path scenarios, the second terminal device 110-2 may occur some abnormal events, including but not limited to, handover which may be an intra-gNB handover or an inter-gNB handover.

Reference is now made to FIG. 1B for a better understanding, where FIG. 1B shows an example communication environment 100B in which example embodiments of the present disclosure can be implemented. FIG. 1B shows different handover procedures in different scenarios.

It should be appreciated that the numbers and types of devices/entities in FIGS. 1A and 1B are given for the purpose of illustration without suggesting any limitations to the present disclosure. The communication environment 100A and 100B may include any suitable number of network devices and/or terminal devices adapted for implementing implementations of the present disclosure. Further, the communication environment 100A and 100B may include any other devices than the network devices and the terminal devices, such as a core network element, but they are omitted here so as to avoid obscuring the present invention.

In some embodiments, the first terminal device 110/the second terminal device 120 and the network device 130 may communicate with each other via a channel such as a wireless communication channel on an air interface (e.g., Uu interface) . The wireless communication channel may comprise a physical uplink control channel (PUCCH) , a physical uplink shared channel (PUSCH) , a physical random-access channel (PRACH) , a physical downlink control channel (PDCCH) , a physical downlink shared channel (PDSCH) and a physical broadcast channel (PBCH) . Of course, any other suitable channels are also feasible.

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

EXAMPLE PROCESSES

It should be understood that although feature (s) /operation (s) are discussed in specific example embodiments separately, unless clearly indicated to the contrary, these feature (s) /operation (s) described in different example embodiments may be used in any suitable combination.

In the following, although some operations are described from a perspective of the first terminal device 110, it is to be understood that the corresponding operations should be performed by the second terminal device 120 and/or the network device 130, and vice versa.

In addition, in the following description, examples of signalling type (such as “RRC signalling” , “MAC CE” , “DCI” , “uplink control information, UCI” ) are only for the purpose of illustration without suggesting any limitations. In other example embodiments, any suitable message types may be used for the interaction between the first apparatus 110-1/110-2 and the second apparatus 120. Merely for brevity, the same or the similar contents are omitted here.

handover of the second terminal device

Reference is made to FIG. 2, which illustrates a signaling flow 200 of communication in accordance with some embodiments of the present disclosure. For the purposes of discussion, the signaling flow 200 will be discussed with reference to FIG. 1A and FIG. 1B, for example, by using the first terminal device 110, the second terminal device 120, the network device 130-1 and the second network device 130-2.

In FIG. 2, an inter-gNB multi-path may be implemented. Specifically, the first terminal device 110 communicates with both a first network device 130-1 via a direct path and a second network device 130-2 via an indirect path comprising a first hop between the first terminal device 110 and the second terminal device 120 and a second hop between the second terminal device 120 and the second network device 130-2. Further, the second terminal device 120 performs a handover procedure which may be either an intra-gNB handover or an inter-gNB handover.

In operation, the second terminal device 120 transmits 210 first information to a first terminal device 110, wherein the first information indicates the handover procedure.

In some embodiments, the first information may comprise a cause indicating the handover procedure or a failure of the indirect path.

In some embodiments, the transmission of the first information is performed conditionally. Specifically, the second terminal device 120 may transmit the first information to the first terminal device 110 if the handover procedure is an inter-gNB handover. Alternatively, in some embodiments, the second terminal device 120 may transmit the first information to the first terminal device 110 if a target network device for handover of the second terminal device 120 is different from the first network device 130-1.

Alternatively, in some other embodiments, the first network device 130-1 and the second network device 130-2 is not the same network device. In other words, the (source) network device of the second terminal device 120 is not the same with that of the first terminal device 110. That is, if the first network device 130-1 and the second network device 130-2 is the same network device, the second terminal device 120 may not transmit 210 first information.

In some embodiments, the second terminal device 120 may determine whether the handover procedure is an inter-gNB handover or an intra-gNB handover (or whether the target network device of the second terminal device 120 is different from the first network device 130-1, or whether the first network device 130-1 and a second network device 130-2 is not the same network device) based on suitable parameters. Example parameters include but are not limited to:

a second indication transmitted by the second network device 130-2, the second indication indicating whether the handover procedure is an inter-gNB handover or an intra-gNB handover,

identities of a source cell and a target cell for handover, or

identities of the second network device 130-2 and a target network device, or

identities of the second network device 130-2 and the first network device 130-1.

As for the first terminal device 110, in some embodiments, after receiving the first information, the first terminal device 110 may initiate 220 an RRC reestablishment procedure.

Alternatively, in some embodiments, after receiving the first information, the first terminal device 110 transmits 230 second information to the first network device 130-1, where the second information indicates the handover procedure of the second terminal device 120.

In some embodiments, together with transmitting the second information, the first terminal device 110 may suspend the transmissions on the indirect path, and/or receive 240 third information from the first network device 130-1, where the third information indicates the first terminal device 110 to release the indirect path or add a further indirect path.

In some embodiments, the transmission of the second information is performed conditionally. Specifically, in some embodiments, the first terminal device 110 may transmit the second information if the first terminal device 110 receives a first indication from the first network device 130-1, where the first indication indicates the first terminal device 110 to report the second information.

Alternatively, or in addition, in some embodiments, the first terminal device 110 may transmit the second information if the handover procedure of the second terminal device 120 is determined to be an inter-gNB handover.

Alternatively, or in addition, in some embodiments, the first terminal device 110 may transmit the second information if a target network device of the second terminal device 120 is determined to be different from the first network device 130-1.

Alternatively, or in addition, in some embodiments, the first terminal device 110 may transmit the second information if the first network device 130-1 and the second network device 130-2 is not the same network device. In other words, the first terminal device 110 may transmit the second information if the first network device 130-1 and the source network device (i.e., second network device 130-2) of the second terminal device 120 is not the same network device.

In some embodiments, the first terminal device 110 may determine whether the handover procedure is an inter-gNB handover or an intra-gNB handover (or whether the target network device of the second terminal device 120 is different from the first network device 130-1, or whether the first network device 130-1 and a second network device 130-2 is not the same network device) based on suitable parameters. Example parameters include but are not limited to:

an indication transmitted by the second terminal device 120, the indication indicating whether the handover procedure is an inter-gNB handover or an intra-gNB handover,

identities of a source cell and a target cell for handover, or

identities of the second network device 130-2 and a target network device, or

Alternatively, or in addition, in some embodiments, the first terminal device 110 may transmit the second information if a signaling radio bearer 1 (SRB1) is configured on the direct path and is not suspended.

Merely for a better understanding, some example embodiments for the above processes are discussed as below.

In some embodiments, the second terminal device 120 may always send notification about the handover or cell reselection (i.e., the first information) .

Alternately, in some embodiments, the second terminal device 120 may indicate to the first terminal device 110 that the second terminal device 120 is performing an inter-gNB handover or intra-gNB handover, or whether the (source) serving gNB of the second terminal device 120 is the same as that of the first terminal device 110, or whether the (target) serving gNB is the same as the first terminal device 110.

Alternately, in some embodiments, the second terminal device 120 may send notification about handover (i.e., the first information) if at least one of the following conditions is fulfilled: if the second terminal device 120 determines that the handover is inter-gNB or control by the second network device 130-2. Else, the second terminal device 120 will not send the first information.

In some embodiments, the second terminal device 120 is indicated by the source gNB with at least one of the following:

an indication of inter/intra gNB handover,

an indication of whether to notify the first terminal device 110,

an indication about the ID of the serving gNB of the first terminal device 110,

an indication about the ID of the source serving gNB of the second terminal device 120, or

an indication about the ID of the source serving gNB of the second terminal device 120.

In some embodiments, the second terminal device 120 may determine whether the handover is an intra-gNB handover or an inter-gNB handover locally, for example, by compare the ID of source cell and that of target cell or by compare the ID of source gNB and that of target gNB.

In some embodiments, the second terminal device 120 may determine whether the target gNB/cell of the second terminal device 120 is different from the serving gNB/cell of the first terminal device 110 (i.e., first network device 130-1) , or whether the source gNB/cell of the second terminal device 120 and the serving gNB/cell of the first terminal device 110 is the same gNB (i.e., whether the first network device 130-1 and a second network device 130-2 is not the same network device) .

In some embodiments, the serving gNB of the second terminal device 120 (i.e., the second network device 130-2) notifies the handover of the second terminal device 120 to the serving gNB of the first terminal device 110 (i.e., the first network device 130-1) , then serving gNB of the first terminal device 110 may release the configuration of the first terminal device 110 and/or the second terminal device 120 will not send notification message to the first terminal device 110.

As for the first terminal device 110, in some embodiments, after receiving the first information, the first terminal device 110 may initiate an RRC reestablishment procedure at once.

Alternatively, in some embodiments, after receiving the first information, the first terminal device 110 may report the first information to the first network device 130-1. Specifically, in some embodiments, the first terminal device 110 may suspend the transmissions on the indirect path and inform the first network device 130-1 if SRB1 is available on the direct path and not suspended, otherwise the first terminal device 110 may trigger the reestablishment. Additionally, the first terminal device 110 may wait for a command form the first network device 130-1, for example, a command used to release the indirect path, and/or add another indirect path via RRCRelease message or RRCReconfiguration message.

In some embodiments, whether and how to transmit the handover-related information is determined by the network device 130 and indicated to the first terminal device 110 and the second terminal device 120.

In some embodiments, if the first terminal device 110 determines that the second terminal device 120 performs inter-gNB handover or the target serving gNB of the second terminal device 120 is not the serving gNB/cell of the first terminal device 110 (i.e., the first network device 130-1) or if the source serving gNB (i.e., the second network device 130-2) /cell of the second terminal device 120 is not the serving gNB (i.e., the first network device 130-1) /cell of the first terminal device 110, the first terminal device 110 will report RLF/handover of relay/failure of indirect path to the first network device 130-1 (also the source gNB of the second terminal device 120) ; else, the first terminal device 110 will not report RLF/handover of relay/failure of indirect path to the first network device 130-1.

According to the above procedure, the signaling overhead is reduced.

reestablishment of the second terminal device

Reference is made to FIG. 3, which illustrates a signaling flow 300 of communication in accordance with some embodiments of the present disclosure. For the purposes of discussion, the signaling flow 300 will be discussed with reference to FIG. 1A and FIG. 1B, for example, by using the first terminal device 110, the second terminal device 120 and the first network device 130-1.

In FIG. 3, both of an inter-gNB multi-path and an intra-gNB multi-path may be implemented.

In FIG. 3, the second terminal device 120 detected an RLF failure, and initiates a reestablishment procedure accordingly. In the following, example embodiments about how to handle the result about the reestablishment procedure will be discussed in detail.

In some embodiments, the first terminal device 110 transmits 310 a first message indicating a radio link failure (RLF) of a second terminal device 120 to the network device 130 (i.e., the serving network device of the first terminal device 110, i.e., the first network device 130-1) .

In the following, the first terminal device 110 receives 340 a second message indicating whether a reestablishment procedure of the second terminal device 120 is successful from the second terminal device 120.

In some embodiments, the second message may indicate at least one of the following:

a successful or unsuccessful Uu radio resource control (RRC) reestablishment procedure of the second terminal device 120,

an RRC state of the second terminal device 120,

an identity of a network device 130 serving the second terminal device 120 before the reestablishment procedure, or

an identity of a network device 130 serving the second terminal device 120 after the reestablishment procedure.

The following text will discuss how to handle the reestablishment result. In some embodiments, if the second message indicates that the reestablishment procedure of the second terminal device 120 is unsuccessful, the first terminal device 110 may perform at least one of the following:

transmitting, to the network device 130, a fifth message indicating that the reestablishment procedure of the second terminal device 120 is unsuccessful;

suspending the indirect path if not suspended;

releasing at least one of the following: a sidelink relay adaptation protocol (SRAP) configuration or a PC5 relay radio link control (RLC) channel configuration; or

requesting an upper layer of the first terminal device to release a PC5 connection with the second terminal device 120.

In some embodiments, the fifth message indicates at least one of the following: a Uu radio resource control (RRC) reestablishment procedure failure of the second terminal device 120, an indirect path failure, a release of a connection between the first terminal device 110 and the second terminal device 120, or a release of the indirect path (or the configuration of the indirect path) .

Additionally, the transmission of the fifth message is performed conditionally. Specifically, in some embodiments, if the SRB 1 is configured on the direct path and is not suspended, the first terminal device 110 may transmit the fifth message to the network device 130.

In some embodiments, if the second message indicates that the reestablishment procedure of the second terminal device 120 is successful, the first terminal device 110 may perform at least one of the following:

transmitting, to the network device 130, a sixth message indicating that the reestablishment procedure of the second terminal device 120 is successful; or

resuming the indirect path, for example, resuming the transmissions on the indirect path or re-active/re-apply the configuration of the indirect path.

In some embodiments, when resuming the indirect path, the first terminal device 110 may determine whether the second terminal device 120 has switched/connected to another network device 130 based on the second message, and further may resume the indirect path in accordance with a determination that the second terminal device 120 has not switched to another network device 130.

In some embodiments, when resuming the indirect path, the first terminal device 110 may determine whether the first terminal device 110 and the second terminal device 120 is served by a same network device 130 based on the second message, and further may resume the indirect path in accordance with a determination that the first terminal device 110 and the second terminal device 120 is served by a same network device 130.

Additionally, the transmission of the sixth message is performed conditionally. Specifically, in some embodiments, if the SRB 1 is configured on a direct path and is not suspended, transmitting the sixth message to the network device 130.

In some embodiments, prior to receiving the second message, the first terminal device 110 may receive third message from the network device 130, where the third message may indicate the first terminal device 110 not to release the indirect path (or to keep the indirect path) .

Alternatively, or in addition, prior to receiving the second message, the first terminal device 110 may transmit a fourth message to the second terminal device 120, where the fourth message may indicate that the indirect path or the configuration of the indirect path has not been released by the first terminal device.

Merely for a better understanding, some example embodiments for the above processes are discussed as below. Processes about how to handle a failed reestablishment will be discussed first.

In some embodiments, the second terminal device 120 may suffer a Uu RLF, and may indicate this Uu RLF to the first terminal device 110. After that, the second terminal device 120 may perform the RRC reestablishment procedure.

As for the first terminal device 110, after receiving the Uu RLF, the first terminal device 110 may report this Uu RLF of the second terminal device 120 to the first network device 130-1. Additionally, the first terminal device 110 may suspend the transmissions on the indirect path and inform the first network device 130-1 about the RLF if SRB1 is available on the direct path and not suspended, otherwise the first terminal device 110 may trigger reestablishment.

In some embodiments, the Uu RLF may be indicated by the following cause value/failure type: Uu RRC Recovery failure, Uu RLF, Uu RRC failure or an indirect path failure.

In some embodiments, the first network device 130-1 may keep the indirect path (or the configuration of the indirect path) for the first terminal device 110. Additionally, in some embodiments, the first network device 130-1 may indicate to the first terminal device 110 to keep the (configuration of) indirect path explicitly (or without sending RRCReconfiguration message to the first terminal device 110) .

In some embodiments, the second terminal device 120 will enter into idle state if it fails to complete the RRC Reestablishment procedure, and may notify its failure of completing the RRC reestablishment procedure (i.e., failure of RRC recovery) to the first terminal device 110. For example, the reason for the second terminal device 120 failing to complete the RRC Reestablishment procedure may be that T301 expires or T311 expires.

In some embodiments, the second terminal device 120 may send the notification message (i.e., the second message) to the first terminal device 110 with the following cause value/failure type: a Uu RRC Recovery failure, Uu RRC failure, Uu RRC Reestablishment failure, or an indirect path failure, or an RRC state of the second terminal device 120 (for example, idle) .

In some embodiments, upon receiving the second message, the first terminal device 110 may inform the first network device 130-1 if SRB1 is available on the direct path and not suspended, otherwise the first terminal device 110 may trigger an RRC reestablishment.

Additionally, in some embodiments, the first terminal device 110 may suspend transmissions on the indirect path if not suspended.

Alternately, or in addition, the first terminal device 110 may require the upper layer to release the PC5 connection with the second terminal device 120. Additionally, the first terminal device 110 may informs the first network device 130-1 if SRB1 is available on the direct path and not suspended, otherwise the first terminal device 110 may trigger reestablishment procedure.

Alternately, or in addition, the first terminal device 110 may trigger reestablishment procedure directly.

Alternately, or in addition, the first terminal device 110 may enter into the idle or inactive state.

In some embodiments, the first terminal device 110 may also release the configuration of indirect path, such as SRAP configuration, PC5 relay RLC configuration.

In some embodiments, the failed reestablishment may be informed to the first network device 130-1 by an indirect path failure, a Uu RRC recovery failure, Uu RRC failure, Uu RRC Reestablishment failure, the RRC state of the second terminal device 120 and/or the release of PC5 connection.

Processes about how to handle a success reestablishment will be discussed in the following.

In some embodiments, the second terminal device 120 may suffer a Uu RLF, and indicates this Uu RLF to the first terminal device 110. After that, the second terminal device 120 may performs the RRC reestablishment procedure.

In some embodiments, the first network device 130-1 may keep the indirect path (configuration) for the first terminal device 110. Additionally, in some embodiments, the first network device 130-1 may indicate to the first terminal device 110 to keep the (configuration of) indirect path explicitly (or without sending RRCReconfiguration message to the first terminal device 110) .

In some embodiments, the second terminal device 120 will enter into the RRC connected state or keep the RRC connected state if it completes the RRC Reestablishment procedure successfully, and may notify the success of completing the RRC Reestablishment procedure to the first terminal device 110 (i.e., the second message) .

In some embodiments, the second terminal device 120 may send notification message (the second message) to the first terminal device 110 with the following cause value/failure type: a Uu RRC recovered, an indirect path recovered, a successful RRC Reestablishment or the RRC state of the second terminal device 120 (for example, connected) .

In some embodiments, the second message may comprise the serving cell/gNB ID of the second terminal device 120. For example, the serving cell/gNB ID of the second terminal device 120 may be the ID of serving cell/gNB before the reestablishment procedure. As another example, the serving cell/gNB ID of the second terminal device 120 may be the ID of serving cell/gNB after the reestablishment procedure.

As for the first terminal device 110, upon receiving the second message, the first terminal device 110 may inform the first network device 130-1 if SRB1 is available on the direct path and not suspended.

Alternatively, or in addition, in some embodiments, the first terminal device 110 may resume the transmissions on the indirect path. The resuming is performed by the fist terminal device 110 conditionally. Specifically, in some embodiments, if the first terminal device 110 determines that the second terminal device 120 reconnect to another gNB.

In some embodiments, the first terminal device 110 may determine whether the second terminal device 120 reconnect to another gNB by an explicit indication, or by comparing the ID of the (current) serving cell/gNB of the second terminal device 120 after the reestablishment procedure and the ID of its (original) serving cell/gNB before the reestablishment procedure.

Processes about how to handle the reestablishment with a timer will be discussed in the following.

Alternately, or in addition, the first terminal device 110 may start a first timer. The value/length of the first timer may be a default value or may be configured by the network device 130 or indicated by the second terminal device 120. For example, the second terminal device 120 may indicate the value of T301 and/or T311 or the sum of the value of T301 and T311 to the first terminal device 110. Then the first terminal device 110 may set the value of the first timer equal to or larger than the indicated value received from the second terminal device 120.

Upon the first timer expiring, the first terminal device 110 may perform at least one of the following procedures:

informing the first network device 130-1, with the RRC state of the second terminal device 120 or the following cause value/failure type: Uu RRC Recovery failure, Uu RLF, Uu RRC failure or an indirect path failure, if SRB1 is available on the direct path and not suspended, otherwise the first terminal device 110 may trigger an RRC reestablishment; or

suspending transmissions on the indirect path if not suspended; or

requiring the upper layer to release the PC5 connection with the second terminal device 120; or

releasing the configuration of indirect path, such as SRAP configuration, PC5 relay RLC configuration; or

triggering reestablishment procedure directly; or

entering into the idle or inactive state.

In some embodiments, the second terminal device 120 will enter into the RRC connected state or keep the RRC connected state if it completes the RRC Reestablishment procedure successfully, and may notify the success of completing the RRC Reestablishment procedure to the first terminal device 110 (i.e., the second message) . Upon receiving this message, the first terminal device 110 may stop the first timer.

Alternately, or in addition, the first terminal device 110 may resume the transmissions on the indirect path. The resuming is performed by the fist terminal device 110 conditionally. Specifically, in some embodiments, if the first terminal device 110 determines that the second terminal device 120 reconnect to another gNB.

Alternately, or in addition, the first terminal device 110 may send notification message to the first network device 130-1 with the following cause value/failure type: a Uu RRC recovered, an indirect path recovered, a successful RRC Reestablishment or the RRC state of the second terminal device 120 (for example, connected) .

state transitioning of the second terminal

Reference is made to FIG. 4A, which illustrates a signaling flow 400A of communication in accordance with some embodiments of the present disclosure. For the purposes of discussion, the signaling flow 400A will be discussed with reference to FIG. 1A and FIG. 1B, for example, by using the first terminal device 110, the second terminal device 120 and the network device 130.

In FIG. 4A, the first hop between the first terminal device 110 and the second terminal device 120 is a non-PC5 connection. As indicated in FIG. 4A, the first terminal device 110 receives 420 a configuration used for configuring an indirect path for the first terminal device 110 from a network device 130. Accordingly, the second terminal device 120 also receives 425 a configuration used for configuring the second terminal device 120 to be a relay terminal device for a first terminal device 110 from the network device 130.

According to some embodiments of the present discourse, the second terminal device 120 may be identified by different identities according to different states of the second terminal device 120.

In some embodiments, if the second terminal device 120 is in an idle state, the second terminal device 120 may be identified by a temporary mobile subscriber identity (TMSI) , for example, the 5G S-Temporary Mobile Subscription Identifier or 5G Temporary Mobile Subscription Identifier.

Alternatively, in some embodiments, if the second terminal device 120 is in an inactive state the second terminal device 120 may be identified by an inactive radio network temporary identifier (I-RNTI) or the TMSI.

Alternatively, in some embodiments, if the second terminal device 120 is in a connected state the second terminal device 120 may be identified by a cell radio network temporary identifier (C-RNTI) .

As indicated in FIG. 4A, the second terminal device 120 may notify 410 its identity or RRC state to the first terminal device 110. Addition, such notifying may be performed conditionally. As one embodiment, the second terminal device 120 may notify the first terminal device 110 about the identity of the second terminal device 120 if the second terminal device 120 is in a connected state.

As for the first terminal device 110, in some embodiments, in order to ensure the availability of the second terminal device 120, prior to receiving the configuration, the first terminal device 110 may report 415 the second terminal device 120 as a candidate relay terminal device to the network device 130 only if the second terminal device 120 is in a connected state, wherein the second terminal device 120 belongs to a plurality of second terminal devices pre-configured to the first terminal device 110.

Alternatively, in some embodiments, in order to ensure the availability of the second terminal device 120 or that the second terminal device 120 is in the connected state, the first terminal device 110 may trigger 430 the second terminal device 120 to transition in a connected state.

In addition, in some embodiments, in order to save power, the first terminal device 110 may trigger the second terminal device 120 to transition in an idle state, an inactive state.

In some embodiments, in order to ensure only the connected state may be selected as the relay terminal device, the first terminal device may only report the candidate relay devices which are in the connected state. In view of this, prior to reporting the candidate relay devices, the first terminal device 110 needs to determine the state of the candidate relay devices (i.e., the pre-configured candidate relay devices including the second terminal device 120) .

The first terminal device 110 may determine the state of the second terminal device 120 according to any suitable information. In some embodiments, the first terminal device 110 may determine a state of the second terminal device 120 based on an eighth message from the second terminal device 120, where the eighth message comprises at least one of the following: the state of the second terminal device 120, or an identity of the second terminal device 120 as the second terminal device is identified by different identities according to different states of the second terminal device.

In some embodiments, the second terminal device 120 may choose the appropriate identity to notify according to the RRC state of the second terminal device 120.

In some embodiments, after the multi-path is configured or the indirect path is added, the network device 10 may release the second terminal device 120 which are not used by the indirect path to the inactive or idle state.

In some embodiments, the first terminal device 110 may ask the second terminal device 120 to enter into the inactive or idle state. In one embodiment, if the buffer is empty, the first terminal device 110 may ask the second terminal device 120 to enter into the inactive or idle state.

In some embodiments, a new signalling may be introduced, used by the first terminal device 110 to change of the RRC status of the second terminal device 120. In some embodiments, the signalling for changing of RRC status of the second terminal device 120 may be any of RRC, MAC CE, UCI, PDCP control PDU, RLC control PDU.

In some embodiments, the first terminal device 110 may report the second terminal device 120 as a candidate relay terminal device to the network device 130 only if the second terminal device 120 is in a connected state, such that the selected relay terminal device is always in a connected state.

In some embodiments, only the second terminal device 120 in RRC_CONNECTED may notify the first terminal device 110 with its identity or RRC state.

In some embodiments, the second terminal device 120 implicitly indicates its state by an indication of RRC status/identity for connected state, i.e., C-RNTI.

Alternatively, the RRC status of the second terminal device 120 is explicitly indicated by the specific identity.

In some embodiments, the second terminal device 120 in any RRC status may notify the first terminal device 110 with its identity/indication for RRC states. In this event, the first terminal device 110 may determine the RRC state of the second terminal device 120 based on its identity or the indication.

In some embodiments, the first terminal device 110 always assume the second terminal device 120 is in connected state (if detected by the first terminal device 110) . In this event, the second terminal device 120 may enter connected state after power on.

In some embodiments, the first terminal device 110 may always trigger the second terminal device 120 to enter into the connected state. Additionally, in some embodiments, in case that the first terminal device 110 reporting, SUI may be used.

In some embodiments, first terminal device 110 may be configured with a split bearer. Since the first hop between the first terminal device 110 and the second terminal device 120 is a non-PC5 connection, it may be uneasy to collect the data volume of the indirect path. In view of this, whether or how to perform data split need to be further discussed. In the following, example embodiments about whether or how to perform data split will be discussed.

In some embodiments, when the split bearer is configured, only the (data) duplication function may be allowed for the split bearer. In other words, data split for the split bearer is not allowed for a split bearer when the first hop between the first terminal device 110 and the second terminal device 120 is a non-PC5 connection.

Alternately, or in addition, when the data split is configured, the primary path of the split bearer may be always on the direct path.

Alternately, or in addition, when the data split is configured, the primary path of the split bearer may be always on the indirect path. And how to perform date split may be up to the UE implementation. That is, there is no needs to configure the threshold of data split for the first terminal device 110 or the first terminal device 110 may ignore the configured threshold of data split.

Reference is made to FIG. 4B, which illustrates a signaling flow 400B of communication in accordance with some embodiments of the present disclosure. For the purposes of discussion, the signaling flow 400B will be discussed with reference to FIG. 1A and FIG. 1B, for example, by using the first terminal device 110, the second terminal device 120 and the network device 130.

As illustrated in FIG. 4B, the second terminal device 120 transitions 450 in a non-connected state, where the transitioning is triggered by the second terminal device 120. In this event, upon the transitioning, the second terminal device 120 transmits 544 a notification to the first terminal device 110, where the notification comprises a cause indicating at least one of the following:

a Uu interface failure of the second terminal device,

a Uu radio resource control (RRC) failure of the second terminal device,

an indirect path failure, or

an expiry of a timer, upon an expiry of which the second terminal device transitions in the non-connected state, or

the transitioning triggered by the upper layer of the second terminal device 120.

In some embodiments, the timer is one of the following: a data inactivity timer, or a locally state transforming timer. One example of the locally state transforming timer is T346g.

In some embodiments, upon receiving the notification, the first terminal device 110 may suspend the transmissions on the indirect path and informs the network device 130 if the SRB1 is available on the direct path and not suspended, otherwise the first terminal device 110 may trigger reestablishment.

Alternatively, if one terminal device is performed/configured as a relay terminal device, the terminal device may ignore the configuration of DataInactivityTimer, or set it to be an infinite value, or not start it.

Alternatively, if the first terminal device 110 has already received the configuration to release the indirect link or switched the indirect link, the first terminal device 110 may ignore this notification form the second terminal device 120.

Alternatively, or in addition, the second terminal device 120 may receive 460 a configuration used for configuring the second terminal device 120 to be a relay device for a first terminal device 110 (such as, configured with Uu relay RLC channel, SRAP) . Then the second terminal device 120 may ignore 465 a timer upon an expiry of which the second terminal device 120 transitions in the idle state.

Additionally, in some embodiments, the second terminal device 120 may ignore a timer by setting a time value of the timer to be infinite or disabling starting the timer.

Example Methods

FIG. 5 illustrates a flowchart of a communication method 500 implemented at a first terminal device in accordance with some embodiments of the present disclosure. For the purpose of discussion, the method 500 will be described from the perspective of the first terminal device in FIG. 1.

At block 510, the first terminal device receives first information from a second terminal device. The first terminal device communicates with both a first network device via a direct path and a second network device via an indirect path comprising a first hop between the first terminal device and the second terminal device and a second hop between the second terminal device and the second network device. The first information indicates a handover procedure of the second terminal device.

At block 520, the first terminal device performs one of the following: initiating a radio resource control (RRC) reestablishment procedure; or transmitting, to the first network device, second information indicating the handover procedure of the second terminal device.

In some example embodiments, together with transmitting the second information, the first terminal device performs at least one of the following: suspending transmissions on the indirect path; and receiving third information from the first network device. The third information indicates the first terminal device to release the indirect path or add a further indirect path.

In some example embodiments, the first terminal device transmits the second information if at least one of the following: receive, from the first network device, a first indication indicating the first terminal device to report the second information; the handover procedure is determined to be an inter-gNodeB (inter-gNB) handover; or a target network device of the second terminal device is determined to be different from the first network device.

In some example embodiments, in accordance with a determination that a signaling radio bearer 1 (SRB1) is configured on the direct path and is not suspended, the first terminal device transmits the second information to the first network device.

In some example embodiments, the first information comprises a cause indicating the handover procedure of the second terminal device or a failure of the indirect path.

FIG. 6 illustrates a flowchart of a communication method 600 implemented at a second terminal device in accordance with some embodiments of the present disclosure. For the purpose of discussion, the method 600 will be described from the perspective of the second terminal device in FIG. 1.

At block 610, the second terminal device performs a handover procedure.

At block 620, the second terminal device transmits first information to a first terminal device. The first terminal device communicates with both a first network device via a direct path and a second network device via an indirect path comprising a first hop between the first terminal device and the second terminal device and a second hop between the second terminal device and the second network device. The first information indicates the handover procedure.

In some example embodiments, the first information indicates whether the handover procedure is an inter-gNodeB (inter-gNB) handover or an intra-gNB handover.

In some example embodiments, the second terminal device transmits the first information to the first terminal device if at least one of the following: the handover procedure is an inter-gNodeB (inter-gNB) handover; or a target network device of the second terminal device is different from the first network device.

In some example embodiments, the second terminal device determines whether the handover procedure is an inter-gNB handover or an intra-gNodeB (intra-gNB) handover or whether the target network device of the second terminal device is different from the first network device, based on at least one of the following: a second indication transmitted by the second network device, the second indication indicating whether the handover procedure is an inter-gNB handover or an intra-gNB handover, identities of a source cell and a target cell, or identities of the second network device and a target network device.

FIG. 7 illustrates a flowchart of a communication method 700 implemented at a first terminal device in accordance with some embodiments of the present disclosure. For the purpose of discussion, the method 700 will be described from the perspective of the first terminal device in FIG. 1.

At block 710, the first terminal device transmits, to a network device, a first message indicating a radio link failure (RLF) of a second terminal device. The first terminal device was configured with an indirect path via the second terminal device.

At block 720, the first terminal device receives, from the second terminal device, a second message indicating whether a reestablishment procedure of the second terminal device is successful.

In some example embodiments, the second message indicates at least one of the following: a successful or unsuccessful Uu radio resource control (RRC) reestablishment procedure of the second terminal device, an RRC state of the second terminal device, an identity of a network device serving the second terminal device before the reestablishment procedure, or an identity of a network device serving the second terminal device after the reestablishment procedure.

In some example embodiments, prior to receiving the second message, the first terminal device receives a third message from the network device. The third message indicates the first terminal device not to release the indirect path. Alternatively, prior to receiving the second message, the first terminal device transmits a fourth message to the second terminal device. The fourth message indicates that the indirect path has not been released by the first terminal device.

In some example embodiments, if the second message indicates that the reestablishment procedure of the second terminal device is unsuccessful, the first terminal device performs at least one of the following: transmitting, to the network device, a fifth message indicating that the reestablishment procedure of the second terminal device is unsuccessful; suspending the indirect path if not suspended; releasing at least one of the following: a sidelink relay adaptation protocol (SRAP) configuration or a PC5 relay radio link control (RLC) channel configuration; or requesting an upper layer of the first terminal device to release a PC5 connection with the second terminal device.

In some example embodiments, in accordance with a determination that a signaling radio bearer 1 (SRB1) is configured on the direct path and is not suspended, the first terminal device transmits the fifth message to the network device.

In some example embodiments, the fifth message indicates at least one of the following: a Uu radio resource control (RRC) reestablishment procedure failure of the second terminal device, an indirect path failure, a release of a connection between the first and second terminal devices.

In some example embodiments, if the second message indicates that the reestablishment procedure of the second terminal device is successful, the first terminal device performs at least one of the following: transmitting, to the network device, a sixth message indicating that the reestablishment procedure of the second terminal device is successful; or resuming the indirect path.

In some example embodiments, the first terminal device determines, based on the second message, whether the second terminal device has switched to another network device or whether the first terminal device and the second terminal device are served by a same network device, Moreover, the first terminal device resumes the indirect path in accordance with a determination that the second terminal device has not switched to another network device.

In some example embodiments, in accordance with a determination that a signaling radio bearer 1 (SRB1) is configured on a direct path and is not suspended, the first terminal device transmits the sixth message to the network device.

FIG. 8 illustrates a flowchart of a communication method 800 implemented at a second terminal device in accordance with some embodiments of the present disclosure. For the purpose of discussion, the method 800 will be described from the perspective of the second terminal device in FIG. 1.

At block 810, the second terminal device performs a reestablishment procedure after a radio link failure (RLF) of the second terminal device.

At block 820, the second terminal device transmits, to a first terminal device, a second message indicating whether the reestablishment procedure of the second terminal device is successful. The first terminal device was configured with an indirect path via the second terminal device.

In some example embodiments, prior to transmitting the second message, the second terminal device receives a fourth message from the first terminal device. The fourth message indicates that the indirect path has not been released by the first terminal device.

FIG. 9 illustrates a flowchart of a communication method 900 implemented at a network device in accordance with some embodiments of the present disclosure. For the purpose of discussion, the method 900 will be described from the perspective of the network device in FIG. 1.

At block 910, network device receives, from a first terminal device served by the network device, a first message indicating a radio link failure (RLF) of a second terminal device. The first terminal device was configured with an indirect path via the second terminal device.

At block 920, the network device receives, from the first terminal device, one of the following: a fifth message indicating that a reestablishment procedure of the second terminal device is unsuccessful, or a sixth message indicating that the reestablishment procedure of the second terminal device is successful.

In some example embodiments, after receiving the first message, the network device transmits a third message to the first terminal device. The third message indicates to the first terminal device not to release the indirect path.

In some example embodiments, in accordance with a determination that a signaling radio bearer 1 (SRB1) is configured on the direct path and is not suspended, the network device receives the fifth or sixth message from the first terminal device.

FIG. 10 illustrates a flowchart of a communication method 1000 implemented at a first terminal device in accordance with some embodiments of the present disclosure. For the purpose of discussion, the method 1000 will be described from the perspective of the first terminal device in FIG. 1.

At block 1010, the first terminal device receives, from a network device, a configuration used for configuring an indirect path for the first terminal device. The indirect path comprises a first hop between the first terminal device and a second terminal device and a second hop between the second terminal device and the network device. The second hop is a non-PC5 hop.

At block 1020, the first terminal device performs at least one of the following: prior to receiving the configuration, reporting the second terminal device as a candidate relay terminal device to the network device in accordance with a determination that the second terminal device is in a connected state, wherein the second terminal device belongs to a plurality of second terminal devices pre-configured to the first terminal device; or triggering the second terminal device to transition in an idle state, an inactive state or a connected state.

In some example embodiments, the first terminal device determines a state of the second terminal device based on an eighth message from the second terminal device. The eighth message comprises at least one of the following: the state of the second terminal device, or an identity of the second terminal device.

In some example embodiments, if the second terminal device is in an idle state, the second terminal device is identified by a temporary mobile subscriber identity (TMSI) . Alternatively, if the second terminal device is in an inactive state the second terminal device is identified by an inactive radio network temporary identifier (I-RNTI) or the TMSI. Alternatively, if the second terminal device is in a connected state the second terminal device is identified by a cell radio network temporary identifier (C-RNTI) .

FIG. 11 illustrates a flowchart of a communication method 1100 implemented at a second terminal device in accordance with some embodiments of the present disclosure. For the purpose of discussion, the method 1100 will be described from the perspective of the second terminal device in FIG. 1.

At block 1110, the second terminal device receives, from a network device, a configuration used for configuring the second terminal device to be a relay terminal device for a first terminal device. A connection between the first terminal device and the second terminal device is a non-PC5 hop.

At block 1120, the second terminal device identifies the second terminal device by different identities according to different states of the second terminal device.

In some example embodiments, the second terminal device notifies the first terminal device about the identity of the second terminal device if the second terminal device is in a connected state.

FIG. 12 illustrates a flowchart of a communication method 1200 implemented at a second terminal device in accordance with some embodiments of the present disclosure. For the purpose of discussion, the method 1200 will be described from the perspective of the second terminal device in FIG. 1.

At block 1210, the second terminal devices transitions in a non-connected state. A first terminal device was configured with an indirect path via the second terminal device and the transitioning is tigered by the second terminal device.

At block 1220, upon the transitioning, the second terminal device transmits a notification to the first terminal device. The notification comprises a cause indicating at least one of the following: a Uu interface failure of the second terminal device, a Uu radio resource control (RRC) failure of the second terminal device, an indirect path failure, or an expiry of a timer, upon an expiry of which the second terminal device transitions in the non-connected state.

In some example embodiments, the timer is one of the following: a data inactivity timer, or a locally state transforming timer.

FIG. 13 illustrates a flowchart of a communication method 1300 implemented at a second terminal device in accordance with some embodiments of the present disclosure. For the purpose of discussion, the method 1300 will be described from the perspective of the second terminal device in FIG. 1.

At block 1310, the second terminal device receives, from a network device, a configuration used for configuring the second terminal device to be a relay device for a first terminal device.

At block 1320, the second terminal device ignores a timer upon an expiry of which the second terminal device transitions in the idle state.

In some example embodiments, the second terminal device sets a time value of the timer to be infinite. Alternatively, the second terminal device disables starting the timer.

FIG. 14 illustrates a flowchart of a communication method 1400 implemented at a first terminal device in accordance with some embodiments of the present disclosure. For the purpose of discussion, the method 1400 will be described from the perspective of the first terminal device in FIG. 1.

At block 1410, the first terminal device receives, from a second terminal device a notification transmitted upon the second terminal device transitioning in an idle state. A first terminal device is configured with an indirect path via the second terminal device. The transitioning is tigered by the second terminal device. Moreover, the notification comprises a cause indicating at least one of the following: a Uu interface failure of the second terminal device, a Uu radio resource control (RRC) failure of the second terminal device, an indirect path failure, or an expiry of a timer, upon an expiry of which the second terminal device transitions in the idle state.

Example Apparatus, Device and Medium

FIG. 15 is a simplified block diagram of a device 1500 that is suitable for implementing embodiments of the present disclosure. The device 1500 can be considered as a further example implementation of any of the devices as shown in FIG. 1A. Accordingly, the device 1500 can be implemented at or as at least a part of the first terminal device 110, the second terminal device 12-or the network device 130.

As shown, the device 1500 includes a processor 1510, a memory 1520 coupled to the processor 1510, a suitable transceiver 1540 coupled to the processor 1510, and a communication interface coupled to the transceiver 1540. The memory 1510 stores at least a part of a program 1530. The transceiver 1540 may be for bidirectional communications or a unidirectional communication based on requirements. The transceiver 1540 may include at least one of a transmitter 1542 and a receiver 1544. The transmitter 1542 and the receiver 1544 may be functional modules or physical entities. The transceiver 1540 has at least one antenna to facilitate communication, though in practice an Access Node mentioned in this application may have several ones. The communication interface may represent any interface that is necessary for communication with other network elements, such as X2/Xn interface for bidirectional communications between eNBs/gNBs, S1/NG interface for communication between a Mobility Management Entity (MME) /Access and Mobility Management Function (AMF) /SGW/UPF and the eNB/gNB, Un interface for communication between the eNB/gNB and a relay node (RN) , or Uu interface for communication between the eNB/gNB and a terminal device.

The program 1530 is assumed to include program instructions that, when executed by the associated processor 1510, enable the device 1500 to operate in accordance with the embodiments of the present disclosure, as discussed herein with reference to FIGS. 1 to 15. The embodiments herein may be implemented by computer software executable by the processor 1510 of the device 1500, or by hardware, or by a combination of software and hardware. The processor 1510 may be configured to implement various embodiments of the present disclosure. Furthermore, a combination of the processor 1510 and memory 1520 may form processing means 1550 adapted to implement various embodiments of the present disclosure.

The memory 1520 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 1520 is shown in the device 1500, there may be several physically distinct memory modules in the device 1500. The processor 1510 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 1500 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.

According to embodiments of the present disclosure, a first terminal device comprising a circuitry is provided. The circuitry is configured to: receive, first information from a second terminal device, wherein the first terminal device communicates with both a first network device via a direct path and a second network device via an indirect path comprising a first hop between the first terminal device and the second terminal device and a second hop between the second terminal device and the second network device, and wherein the first information indicates a handover procedure of the second terminal device; and perform one of the following: initiating a radio resource control (RRC) reestablishment procedure; or transmitting, to the first network device, second information indicating the handover procedure of the second terminal device. According to embodiments of the present disclosure, the circuitry may be configured to perform any method implemented by the first terminal device as discussed above.

According to embodiments of the present disclosure, a second terminal device comprising a circuitry is provided. The circuitry is configured to: perform a handover procedure; and transmit, first information to a first terminal device, wherein the first terminal device communicates with both a first network device via a direct path and a second network device via an indirect path comprising a first hop between the first terminal device and the second terminal device and a second hop between the second terminal device and the second network device, and wherein the first information indicates the handover procedure. According to embodiments of the present disclosure, the circuitry may be configured to perform any method implemented by the second terminal device as discussed above.

According to embodiments of the present disclosure, a first terminal device comprising a circuitry is provided. The circuitry is configured to: transmit, to a network device, a first message indicating a radio link failure (RLF) of a second terminal device, wherein the first terminal device was configured with an indirect path via the second terminal device; and receive, from the second terminal device, a second message indicating whether a reestablishment procedure of the second terminal device is successful. According to embodiments of the present disclosure, the circuitry may be configured to perform any method implemented by the first terminal device as discussed above.

According to embodiments of the present disclosure, a second terminal device comprising a circuitry is provided. The circuitry is configured to: perform a reestablishment procedure after a radio link failure (RLF) of the second terminal device; and transmit, to a first terminal device, a second message indicating whether the reestablishment procedure of the second terminal device is successful, wherein the first terminal device was configured with an indirect path via the second terminal device. According to embodiments of the present disclosure, the circuitry may be configured to perform any method implemented by the second terminal device as discussed above.

According to embodiments of the present disclosure, a network device comprising a circuitry is provided. The circuitry is configured to: receive, from a first terminal device served by the network device, a first message indicating a radio link failure (RLF) of a second terminal device, wherein the first terminal device was configured with an indirect path via the second terminal device; and receive, from the first terminal device, one of the following: a fifth message indicating that a reestablishment procedure of the second terminal device is unsuccessful, or a sixth message indicating that the reestablishment procedure of the second terminal device is successful. According to embodiments of the present disclosure, the circuitry may be configured to perform any method implemented by the network device as discussed above.

According to embodiments of the present disclosure, a first terminal device comprising a circuitry is provided. The circuitry is configured to: receive, from a network device, a configuration used for configuring an indirect path for the first terminal device, wherein the indirect path comprises a first hop between the first terminal device and a second terminal device and a second hop between the second terminal device and the network device, and wherein the second hop is a non-PC5 hop; and perform at least one of the following: prior to receiving the configuration, reporting the second terminal device as a candidate relay terminal device to the network device in accordance with a determination that the second terminal device is in a connected state, wherein the second terminal device belongs to a plurality of second terminal devices pre-configured to the first terminal device; or triggering the second terminal device to transition in an idle state, an inactive state or a connected state. According to embodiments of the present disclosure, the circuitry may be configured to perform any method implemented by the first terminal device as discussed above.

According to embodiments of the present disclosure, a second terminal device comprising a circuitry is provided. The circuitry is configured to: receive, from a network device, a configuration used for configuring the second terminal device to be a relay terminal device for a first terminal device, wherein a connection between the first terminal device and the second terminal device is a non-PC5 hop; and identify the second terminal device by different identities according to different states of the second terminal device. According to embodiments of the present disclosure, the circuitry may be configured to perform any method implemented by the second terminal device as discussed above.

According to embodiments of the present disclosure, a second terminal device comprising a circuitry is provided. The circuitry is configured to: transition in a non-connected state, wherein a first terminal device was configured with an indirect path via the second terminal device and the transitioning is tigered by the second terminal device; and upon the transitioning, transmit a notification to the first terminal device, the notification comprising a cause indicating at least one of the following: a Uu interface failure of the second terminal device, a Uu radio resource control (RRC) failure of the second terminal device, an indirect path failure, or an expiry of a timer, upon an expiry of which the second terminal device transitions in the non-connected state. According to embodiments of the present disclosure, the circuitry may be configured to perform any method implemented by the second terminal device as discussed above.

According to embodiments of the present disclosure, a second terminal device comprising a circuitry is provided. The circuitry is configured to: receive, from a network device, a configuration used for configuring the second terminal device to be a relay device for a first terminal device; and ignore a timer upon an expiry of which the second terminal device transitions in the idle state. According to embodiments of the present disclosure, the circuitry may be configured to perform any method implemented by the second terminal device as discussed above.

According to embodiments of the present disclosure, a first terminal device comprising a circuitry is provided. The circuitry is configured to: receive, from a second terminal device a notification transmitted upon the second terminal device transitioning in an idle state, a first terminal device being configured with an indirect path via the second terminal device and the transitioning being tigered by the second terminal device, the notification comprising a cause indicating at least one of the following: a Uu interface failure of the second terminal device, a Uu radio resource control (RRC) failure of the second terminal device, an indirect path failure, or an expiry of a timer, upon an expiry of which the second terminal device transitions in the idle state. According to embodiments of the present disclosure, the circuitry may be configured to perform any method implemented by the first terminal device as discussed above.

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

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

In an aspect, it is proposed a first terminal device comprising: a processor configured to cause the first terminal device to: receive, first information from a second terminal device, wherein the first terminal device communicates with both a first network device via a direct path and a second network device via an indirect path comprising a first hop between the first terminal device and the second terminal device and a second hop between the second terminal device and the second network device, and wherein the first information indicates a handover procedure of the second terminal device; and perform one of the following: initiating a radio resource control (RRC) reestablishment procedure; or transmitting, to the first network device, second information indicating the handover procedure of the second terminal device.

In some embodiments, together with transmitting the second information, the processor is further configured to cause the first terminal device to perform at least one of the following: suspending transmissions on the indirect path; and receiving third information from the first network device, the third information indicating the first terminal device to release the indirect path or add a further indirect path.

In some embodiments, transmitting the second information comprises: transmitting the second information if at least one of the following: receive, from the first network device, a first indication indicating the first terminal device to report the second information; the handover procedure is determined to be an inter-gNodeB (inter-gNB) handover; or a target network device of the second terminal device is determined to be different from the first network device.

In some embodiments, transmitting the second information comprises: in accordance with a determination that a signaling radio bearer 1 (SRB1) is configured on the direct path and is not suspended, transmitting the second information to the first network device.

In some embodiments, the first information comprises a cause indicating the handover procedure of the second terminal device or a failure of the indirect path.

In an aspect, it is proposed a second terminal device comprising: a processor configured to cause the second terminal device to: perform a handover procedure; and transmit, first information to a first terminal device, wherein the first terminal device communicates with both a first network device via a direct path and a second network device via an indirect path comprising a first hop between the first terminal device and the second terminal device and a second hop between the second terminal device and the second network device, and wherein the first information indicates the handover procedure.

In some embodiments, the first information indicates whether the handover procedure is an inter-gNodeB (inter-gNB) handover or an intra-gNB handover.

In some embodiments, transmitting the first information comprises: transmitting the first information to the first terminal device if at least one of the following: the handover procedure is an inter-gNodeB (inter-gNB) handover; or a target network device of the second terminal device is different from the first network device.

In some embodiments, the processor is further configured to cause the second terminal device to: determine whether the handover procedure is an inter-gNB handover or an intra-gNodeB (intra-gNB) handover or whether the target network device of the second terminal device is different from the first network device, based on at least one of the following: a second indication transmitted by the second network device, the second indication indicating whether the handover procedure is an inter-gNB handover or an intra-gNB handover, identities of a source cell and a target cell, or identities of the second network device and a target network device.

In an aspect, it is proposed a first terminal device comprising: a processor configured to cause the first terminal device to: transmit, to a network device, a first message indicating a radio link failure (RLF) of a second terminal device, wherein the first terminal device was configured with an indirect path via the second terminal device; and receive, from the second terminal device, a second message indicating whether a reestablishment procedure of the second terminal device is successful.

In some embodiments, the second message indicates at least one of the following: a successful or unsuccessful Uu radio resource control (RRC) reestablishment procedure of the second terminal device, an RRC state of the second terminal device, an identity of a network device serving the second terminal device before the reestablishment procedure, or an identity of a network device serving the second terminal device after the reestablishment procedure.

In some embodiments, the processor is further configured to cause the first terminal device to perform at least one of the following: prior to receiving the second message, receiving a third message from the network device, the third message indicating the first terminal device not to release the indirect path; or prior to receiving the second message, transmitting a fourth message to the second terminal device, the fourth message indicating that the indirect path has not been released by the first terminal device.

In some embodiments, if the second message indicates that the reestablishment procedure of the second terminal device is unsuccessful, the processor is further configured to cause the first terminal device to perform at least one of the following: transmitting, to the network device, a fifth message indicating that the reestablishment procedure of the second terminal device is unsuccessful; suspending the indirect path if not suspended; releasing at least one of the following: a sidelink relay adaptation protocol (SRAP) configuration or a PC5 relay radio link control (RLC) channel configuration; or requesting an upper layer of the first terminal device to release a PC5 connection with the second terminal device.

In some embodiments, transmitting the fifth message comprises: in accordance with a determination that a signaling radio bearer 1 (SRB1) is configured on the direct path and is not suspended, transmitting the fifth message to the network device.

In some embodiments, the fifth message indicates at least one of the following: a Uu radio resource control (RRC) reestablishment procedure failure of the second terminal device, an indirect path failure, a release of a connection between the first and second terminal devices.

In some embodiments, if the second message indicates that the reestablishment procedure of the second terminal device is successful, the processor is further configured to cause the first terminal device to perform at least one of the following: transmitting, to the network device, a sixth message indicating that the reestablishment procedure of the second terminal device is successful; or resuming the indirect path.

In some embodiments, resuming the indirect path comprises: determining, based on the second message, whether the second terminal device has switched to another network device or whether the first terminal device and the second terminal device are served by a same network device; and resuming the indirect path in accordance with a determination that the second terminal device has not switched to another network device.

In some embodiments, transmitting the sixth message comprises: in accordance with a determination that a signaling radio bearer 1 (SRB1) is configured on a direct path and is not suspended, transmitting the sixth message to the network device.

In an aspect, it is proposed a second terminal device comprising: a processor configured to cause the second terminal device to: perform a reestablishment procedure after a radio link failure (RLF) of the second terminal device; and transmit, to a first terminal device, a second message indicating whether the reestablishment procedure of the second terminal device is successful, wherein the first terminal device was configured with an indirect path via the second terminal device.

In some embodiments, the processor is further configured to cause the second terminal device to: prior to transmitting the second message, receive a fourth message from the first terminal device, the fourth message indicating that the indirect path has not been released by the first terminal device.

In an aspect, it is proposed a network device comprising: a processor configured to cause the network device to: receive, from a first terminal device served by the network device, a first message indicating a radio link failure (RLF) of a second terminal device, wherein the first terminal device was configured with an indirect path via the second terminal device; and receive, from the first terminal device, one of the following: a fifth message indicating that a reestablishment procedure of the second terminal device is unsuccessful, or a sixth message indicating that the reestablishment procedure of the second terminal device is successful.

In some embodiments, the processor is further configured to cause the network device to: after receiving the first message, transmit a third message to the first terminal device, the third message indicating to the first terminal device not to release the indirect path.

In some embodiments, receiving the fifth or sixth message comprises: in accordance with a determination that a signaling radio bearer 1 (SRB1) is configured on the direct path and is not suspended, receiving the fifth or sixth message from the first terminal device.

In an aspect, it is proposed a first terminal device comprising: a processor configured to cause the first terminal device to: receive, from a network device, a configuration used for configuring an indirect path for the first terminal device, wherein the indirect path comprises a first hop between the first terminal device and a second terminal device and a second hop between the second terminal device and the network device, and wherein the second hop is a non-PC5 hop; and perform at least one of the following: prior to receiving the configuration, reporting the second terminal device as a candidate relay terminal device to the network device in accordance with a determination that the second terminal device is in a connected state, wherein the second terminal device belongs to a plurality of second terminal devices pre-configured to the first terminal device; or triggering the second terminal device to transition in an idle state, an inactive state or a connected state.

In some embodiments, the processor is further configured to cause the first terminal device to: determine a state of the second terminal device based on an eighth message from the second terminal device, the eighth message comprising at least one of the following: the state of the second terminal device, or an identity of the second terminal device.

In some embodiments, if the second terminal device is in an idle state, the second terminal device is identified by a temporary mobile subscriber identity (TMSI) , if the second terminal device is in an inactive state the second terminal device is identified by an inactive radio network temporary identifier (I-RNTI) or the TMSI, or if the second terminal device is in a connected state the second terminal device is identified by a cell radio network temporary identifier (C-RNTI) .

In an aspect, it is proposed a second terminal device comprising: a processor configured to cause the second terminal device to: receive, from a network device, a configuration used for configuring the second terminal device to be a relay terminal device for a first terminal device, wherein a connection between the first terminal device and the second terminal device is a non-PC5 hop; and identify the second terminal device by different identities according to different states of the second terminal device.

In some embodiments, the processor is further configured to cause the second terminal device to: notify the first terminal device about the identity of the second terminal device if the second terminal device is in a connected state.

In an aspect, it is proposed a second terminal device comprising: a processor configured to cause the second terminal device to: transition in a non-connected state, wherein a first terminal device was configured with an indirect path via the second terminal device and the transitioning is tigered by the second terminal device; and upon the transitioning, transmit a notification to the first terminal device, the notification comprising a cause indicating at least one of the following: a Uu interface failure of the second terminal device, a Uu radio resource control (RRC) failure of the second terminal device, an indirect path failure, or an expiry of a timer, upon an expiry of which the second terminal device transitions in the non-connected state.

In some embodiments, the timer is one of the following: a data inactivity timer, or a locally state transforming timer.

In an aspect, it is proposed a second terminal device comprising: a processor configured to cause the second terminal device to: receive, from a network device, a configuration used for configuring the second terminal device to be a relay device for a first terminal device; and ignore a timer upon an expiry of which the second terminal device transitions in the idle state.

In some embodiments, ignoring a timer comprises one of the following: setting a time value of the timer to be infinite; or disabling starting the timer.

In an aspect, it is proposed a first terminal device comprising: a processor configured to cause the first terminal device to: receive, from a second terminal device a notification transmitted upon the second terminal device transitioning in an idle state, a first terminal device being configured with an indirect path via the second terminal device and the transitioning being tigered by the second terminal device, the notification comprising a cause indicating at least one of the following: a Uu interface failure of the second terminal device, a Uu radio resource control (RRC) failure of the second terminal device, an indirect path failure, or an expiry of a timer, upon an expiry of which the second terminal device transitions in the idle state.

In an aspect, a first terminal device comprises: at least one processor; and at least one memory coupled to the at least one processor and storing instructions thereon, the instructions, when executed by the at least one processor, causing the device to perform the method implemented by the first terminal device discussed above.

In an aspect, a second terminal device comprises: at least one processor; and at least one memory coupled to the at least one processor and storing instructions thereon, the instructions, when executed by the at least one processor, causing the device to perform the method implemented by the second terminal device discussed above.

In an aspect, a network device comprises: at least one processor; and at least one memory coupled to the at least one processor and storing instructions thereon, the instructions, when executed by the at least one processor, causing the device to perform the method implemented by the network device discussed above.

In an aspect, 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 implemented by the first terminal device discussed above.

In an aspect, 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 implemented by the second terminal device discussed above.

In an aspect, 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 implemented by the network device discussed above.

In an aspect, a computer program comprising instructions, the instructions, when executed on at least one processor, causing the at least one processor to perform the method implemented by the first terminal device discussed above.

In an aspect, a computer program comprising instructions, the instructions, when executed on at least one processor, causing the at least one processor to perform the method implemented by the second terminal device discussed above.

In an aspect, a computer program comprising instructions, the instructions, when executed on at least one processor, causing the at least one processor to perform the method implemented by the network device discussed above.

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

The present disclosure also provides at least one computer program product tangibly stored on a non-transitory computer readable storage medium. The computer program product includes computer-executable instructions, such as those included in program modules, being executed in a device on a target real or virtual processor, to carry out the process or method as described above with reference to FIGS. 1 to 15. 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 first terminal device comprising:

a processor configured to cause the first terminal device to:

receive, first information from a second terminal device, wherein the first terminal device communicates with both a first network device via a direct path and a second network device via an indirect path comprising a first hop between the first terminal device and the second terminal device and a second hop between the second terminal device and the second network device, and wherein the first information indicates a handover procedure of the second terminal device; and

perform one of the following:

initiating a radio resource control (RRC) reestablishment procedure; or

transmitting, to the first network device, second information indicating the handover procedure of the second terminal device.
The first terminal device of claim 1, wherein the processor is further configured to cause the first terminal device to:

transmit the second information if at least one of the following:

receive, from the first network device, a first indication indicating the first terminal device to report the second information;

the handover procedure is determined to be an inter-gNodeB (inter-gNB) handover; or

a target network device of the second terminal device is determined to be different from the first network device.
The first terminal device of claim 1, wherein the first information comprises a cause indicating the handover procedure of the second terminal device or a failure of the indirect path.
A second terminal device comprising:

a processor configured to cause the second terminal device to:

perform a handover procedure; and

transmit, first information to a first terminal device, wherein the first terminal device communicates with both a first network device via a direct path and a second network device via an indirect path comprising a first hop between the first terminal device and the second terminal device and a second hop between the second terminal device and the second network device, and wherein the first information indicates the handover procedure.
The second terminal device of claim 4, wherein the processor is further configured to cause the first terminal device to:

transmit the first information to the first terminal device if at least one of the following:

the handover procedure is an inter-gNodeB (inter-gNB) handover; or

a target network device of the second terminal device is different from the first network device.
The second terminal device of claim 5, wherein the processor is further configured to cause the second terminal device to:

determine whether the handover procedure is an inter-gNB handover or an intra-gNodeB (intra-gNB) handover or whether the target network device of the second terminal device is different from the first network device, based on at least one of the following:

a second indication transmitted by the second network device, the second indication indicating whether the handover procedure is an inter-gNB handover or an intra-gNB handover,

identities of a source cell and a target cell, or

identities of the second network device and a target network device.
A first terminal device comprising:

a processor configured to cause the first terminal device to:

transmit, to a network device, a first message indicating a radio link failure (RLF) of a second terminal device, wherein the first terminal device was configured with an indirect path via the second terminal device; and

receive, from the second terminal device, a second message indicating whether a reestablishment procedure of the second terminal device is successful.
The first terminal device of claim 7, wherein the second message indicates at least one of the following:

a successful or unsuccessful Uu radio resource control (RRC) reestablishment procedure of the second terminal device,

an RRC state of the second terminal device,

an identity of a network device serving the second terminal device before the reestablishment procedure, or

an identity of a network device serving the second terminal device after the reestablishment procedure.
The first terminal device of claim 7, wherein the processor is further configured to cause the first terminal device to perform at least one of the following:

prior to receiving the second message, receiving a third message from the network device, the third message indicating the first terminal device not to release the indirect path; or

prior to receiving the second message, transmitting a fourth message to the second terminal device, the fourth message indicating that the indirect path has not been released by the first terminal device.
The first terminal device of claim 7, wherein if the second message indicates that the reestablishment procedure of the second terminal device is unsuccessful, the processor is further configured to cause the first terminal device to perform at least one of the following:

transmitting, to the network device, a fifth message indicating that the reestablishment procedure of the second terminal device is unsuccessful;

suspending the indirect path if not suspended;

releasing at least one of the following: a sidelink relay adaptation protocol (SRAP) configuration or a PC5 relay radio link control (RLC) channel configuration; or

requesting an upper layer of the first terminal device to release a PC5 connection with the second terminal device.
The first terminal device of claim 10, wherein the fifth message indicates at least one of the following:

a Uu radio resource control (RRC) reestablishment procedure failure of the second terminal device,

an indirect path failure,

a release of a connection between the first and second terminal devices.
The first terminal device of claim 7, wherein if the second message indicates that the reestablishment procedure of the second terminal device is successful, the processor is further configured to cause the first terminal device to perform at least one of the following:

transmitting, to the network device, a sixth message indicating that the reestablishment procedure of the second terminal device is successful; or

resuming the indirect path.
The first terminal device of claim 12, wherein the processor is further configured to cause the first terminal device to:

determine, based on the second message, whether the second terminal device has switched to another network device; and

resume the indirect path in accordance with a determination that the second terminal device has not switched to another network device.
A second terminal device comprising:

a processor configured to cause the second terminal device to:

perform a reestablishment procedure after a radio link failure (RLF) of the second terminal device; and

transmit, to a first terminal device, a second message indicating whether the reestablishment procedure of the second terminal device is successful, wherein the first terminal device was configured with an indirect path via the second terminal device.
The second terminal device of claim 14, wherein the processor is further configured to cause the second terminal device to:

prior to transmitting the second message, receive a fourth message from the first terminal device, the fourth message indicating that the indirect path has not been released by the first terminal device.
A first terminal device comprising:

a processor configured to cause the first terminal device to:

receive, from a network device, a configuration used for configuring an indirect path for the first terminal device, wherein the indirect path comprises a first hop between the first terminal device and a second terminal device and a second hop between the second terminal device and the network device, and wherein the second hop is a non-PC5 hop; and

perform at least one of the following:

prior to receiving the configuration, reporting the second terminal device as a candidate relay terminal device to the network device in accordance with a determination that the second terminal device is in a connected state, wherein the second terminal device belongs to a plurality of second terminal devices pre-configured to the first terminal device; or

triggering the second terminal device to transition in an idle state, an inactive state or a connected state.
The first terminal device of claim 16, wherein the processor is further configured to cause the first terminal device to:

determine a state of the second terminal device based on an eighth message from the second terminal device, the eighth message comprising at least one of the following:

the state of the second terminal device, or

an identity of the second terminal device.
The first terminal device of claim 17, wherein,

if the second terminal device is in an idle state, the second terminal device is identified by a temporary mobile subscriber identity (TMSI) ,

if the second terminal device is in an inactive state the second terminal device is identified by an inactive radio network temporary identifier (I-RNTI) or the TMSI, or

if the second terminal device is in a connected state the second terminal device is identified by a cell radio network temporary identifier (C-RNTI) .
A second terminal device comprising:

a processor configured to cause the second terminal device to:

receive, from a network device, a configuration used for configuring the second terminal device to be a relay terminal device for a first terminal device, wherein a connection between the first terminal device and the second terminal device is a non-PC5 hop; and

identify the second terminal device by different identities according to different states of the second terminal device.
The second terminal device of claim 19, wherein the processor is further configured to cause the second terminal device to:

notify the first terminal device about the identity of the second terminal device if the second terminal device is in a connected state.