Handover Enhancements

Abstract

An exemplary embodiment of the present disclosure relates to a handover enhancement. In response to receiving a first message from a third device to initiate a handover involving a first device and a second device, the first device performs a handover procedure to a target cell indicated in the first message. The first device acts as a UE-to-network relay for the second device to communicate with the third device. The first device then sends at least one instruction to the second device based on the handover procedure. In this manner, the remote UE can apply different operations based on the respective instructions related to the handover result. As a result, the operation of the remote UE can be aligned with the operation of the relay UE when performing a handover, and system performance and reliability can be improved.

Description

[Technical Field]

[0001] Various exemplary embodiments of the present disclosure relate generally to the field of telecommunications, and more particularly to methods, devices, apparatus, and computer-readable storage media for handover enhancement. [Background technology]

[0002] In a sidelink relay scenario, at least one remote UE may be connected to the network via a relay UE, also referred to as a UE-to-Network relay UE. For example, the remote UE may be a wearable device (e.g., a smart watch, glasses, etc.). In the case of mobility, the relay UE and the connected remote UE move together from one gNB (i.e., source gNB) to another gNB (i.e., target gNB), and the remote UE remains connected to the same relay UE. Depending on operator policy or configuration, the PC5 configuration may or may not be the same at the source gNB and the target gNB. Therefore, the remote UE and relay UE may use different RRC configurations, e.g., security keys, for communication with the source gNB and the target gNB. Summary of the Invention

[0003] Generally, the exemplary embodiments of the present disclosure provide a handover enhancement solution.

[0004] In a first aspect of the present disclosure, a first device is provided, the first device comprising: at least one processor and at least one memory that stores instructions that, when executed by the at least one processor, cause the first device to: in response to receiving a first message from a third device to initiate a handover involving the first device and a second device, perform, at the first device, a handover procedure to a target cell indicated in the first message, wherein the first device acts as a UE-to-network relay for the second device to communicate with the third device; and send, to the second device, at least one instruction based on the handover procedure.

[0005] In a second aspect of the present disclosure, a second device is provided, the second device comprising: at least one processor and at least one memory that stores instructions that, when executed by the at least one processor, cause the second device to at least perform the following steps: receive, from a third device via the first device, a second message comprising at least one candidate cell configuration and a set of conditions related to the first device, wherein the first device acts as a UE-to-network relay for the second device to communicate with the third device; and receive, from the first device, at least one instruction corresponding to at least one of the set of conditions.

[0006] In a third aspect of the present disclosure, a third device is provided, the third device comprising: at least one processor and at least one memory that stores instructions that, when executed by the at least one processor, cause the third device to at least perform the following steps in accordance with a determination that a handover involving a first device and a second device should be performed: generating a second message comprising at least one candidate cell configuration and a set of conditions related to the first device, where the first device acts as a UE-to-network relay for the second device to communicate with the third device, each of the sets of conditions corresponding to at least one instruction to be sent from the first device to the second device; transmitting the second message to the second device via the first device; and transmitting the first message to the first device to initiate the handover.

[0007] In a fourth aspect of the present disclosure, a method is provided, the method including: in response to receiving, from a third device, a first message for initiating a handover involving a first device and a second device, performing, at the first device, a handover procedure to a target cell indicated in the first message, wherein the first device acts as a UE-to-network relay for the second device to communicate with the third device; and sending, to the second device, at least one instruction based on the handover procedure.

[0008] In a fifth aspect of the present disclosure, a method is provided, the method including: receiving, via a first device from a third device, a second message comprising at least one candidate cell configuration and a set of conditions related to the first device, wherein the first device acts as a UE-to-network relay for the second device to communicate with the third device; and receiving, from the first device, at least one indication corresponding to at least one of the set of conditions.

[0009] In a sixth aspect of the present disclosure, a method is provided, the method including: generating, at a third device according to a determination that a handover related to a first device and a second device should be performed, a second message comprising at least one candidate cell configuration and a set of conditions related to the first device, the first device acting as a UE-to-network relay for the second device to communicate with the third device, each of the sets of conditions corresponding to at least one instruction to be sent from the first device to the second device; transmitting the second message to the second device via the first device; and transmitting the first message to the first device to initiate the handover.

[0010] In a seventh aspect of the present disclosure, a first apparatus is provided, the first apparatus including: means for, in response to receiving from a third apparatus a first message for initiating a handover relating to the first apparatus and a second apparatus, performing a handover procedure to a target cell indicated in the first message, the first apparatus including: means for acting as a UE-to-network relay for the second apparatus to communicate with the third apparatus; and means for transmitting at least one instruction to the second apparatus based on the handover procedure.

[0011] In an eighth aspect of the present disclosure, a second apparatus is provided, the second apparatus including: means for receiving, from a third apparatus via the first apparatus, a second message comprising at least one candidate cell configuration and a set of conditions associated with the first apparatus, the second message including at least one candidate cell configuration and a set of conditions associated with the first apparatus, the first apparatus acting as a UE-to-network relay for the second apparatus to communicate with the third apparatus; and means for receiving, from the first apparatus, at least one indication corresponding to at least one of the set of conditions.

[0012] In a ninth aspect of the present disclosure, a third apparatus is provided, the third apparatus including: means for generating, according to a determination that a handover related to a first apparatus and a second apparatus should be performed, a second message comprising at least one candidate cell configuration and a set of conditions related to the first apparatus, the first apparatus acting as a UE-to-network relay for the second apparatus to communicate with the third apparatus, each of the sets of conditions corresponding to at least one instruction to be sent from the first apparatus to the second apparatus; means for transmitting the second message to the second apparatus via the first apparatus; and means for transmitting the first message to the first apparatus to initiate the handover.

[0013] In a tenth aspect of the present disclosure, there is provided a computer-readable medium having stored thereon instructions for causing an apparatus to perform at least a method according to any of the fourth, fifth, or sixth aspects.

[0014] It should be understood that the "Summary" section is not intended to identify key or essential features of embodiments of the present disclosure, nor is it intended to be used to limit the scope of the present disclosure. Other features of the present disclosure will be readily apparent from the following description.

[0015] Hereinafter, embodiments will be described with reference to the drawings. [Brief explanation of the drawings]

[0016] [Figure 1] 1 illustrates an exemplary communication environment in which exemplary embodiments of the present disclosure may be implemented. [Figure 2] 1 illustrates a signaling chart for handover of a first device and a second device according to some example embodiments of the present disclosure. [Figure 3] 1 illustrates a flowchart of a method implemented in a first device, according to some exemplary embodiments of the present disclosure. [Figure 4]10 shows a flowchart of a method implemented in a second device, according to some example embodiments of the present disclosure. [Figure 5] 10 shows a flowchart of a method implemented in a third device, according to some example embodiments of the present disclosure. [Figure 6] FIG. 1 shows a simplified block diagram of a device suitable for implementing exemplary embodiments of the present disclosure. [Figure 7] 1 illustrates a block diagram of an exemplary computer-readable medium according to some exemplary embodiments of the present disclosure.

[0017] Throughout the drawings, the same or similar reference numbers represent the same or similar elements. DETAILED DESCRIPTION OF THE INVENTION

[0018] The principles of the present disclosure will now be described with reference to some exemplary embodiments. It should be understood that these embodiments are provided for illustrative purposes only, to assist those skilled in the art in understanding and practicing the present disclosure, but do not imply any limitation on the scope of the present disclosure. The disclosure described herein can be implemented in various ways other than those described below.

[0019] In the following description and claims, unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this disclosure belongs.

[0020] References in this disclosure to "one embodiment," "embodiment," "exemplary embodiment," etc. indicate that the described embodiment may include a particular feature, structure, or characteristic, but not all embodiments need include the particular feature, structure, or characteristic. Moreover, such phrases do not necessarily refer to the same embodiment. Furthermore, it is submitted that when a particular feature, structure, or characteristic is described in connection with an exemplary embodiment, it is within the knowledge of one skilled in the art to affect such feature, structure, or characteristic in connection with other embodiments, whether or not explicitly described.

[0021] Although the terms "first," "second," etc. may be used herein to describe various elements, it should be understood that these elements should not be limited by these terms. These terms are used only to distinguish the function of the various elements. As used herein, the term "and / or" includes any and all combinations of one or more of the listed terms.

[0022] The terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit example embodiments. As used herein, the singular forms "a," "an," and "the" are intended to include the plural forms unless the context clearly dictates otherwise. Furthermore, it will be understood that the terms "comprises," "comprising," "has," "having," "includes," and / or "including," when used herein, specify the presence of stated features, elements, and / or components, etc., but do not exclude the presence or addition of one or more other features, elements, components, and / or combinations thereof.

[0023] As used herein, when a list of two or more elements is joined by "and" or "or," "at least one of a list of two or more elements," and "at least one of a list of two or more elements," and similar phrases mean at least one of the elements, or at least any two or more of the elements, or at least all of the elements.

[0024] As used in this application, the term "circuitry" may refer to one or more or all of the following: (a) Hardware-only circuit implementation (e.g., implementation in analog and / or digital circuits only) (b) a combination of hardware circuitry and software (where applicable); (i) a combination of analog and / or digital hardware circuitry and software / firmware; (ii) Any portion of software (including digital signal processors), software, and hardware processors with memory, that cooperate to cause a device such as a mobile phone or server to perform various functions. (c) Hardware circuitry and / or processors, such as microprocessors or portions of microprocessors, that require software (e.g., firmware) to operate, but the software may not be present when not needed for operation.

[0025] This definition of circuit applies to all uses of the term in this application, including any claims. As a further example, as used in this application, the term circuit also encompasses simply a hardware circuit or processor (or processors), or a portion of a hardware circuit or processor, as well as its (or their) accompanying software and / or firmware implementations. The term circuit also encompasses, for example, a baseband or processor integrated circuit for a mobile device, or a similar integrated circuit in a server, cellular network device, or other computing or network device, if applicable to certain claim elements.

[0026] As used herein, the term "communication network" refers to a network conforming to any suitable communication standard, such as a fifth-generation (5G) system, Long Term Evolution (LTE), LTE-Advanced (LTE-A), Wideband Code Division Multiple Access (WCDMA), High-Speed ​​Packet Access (HSPA), or Narrow Band Internet of Things (NB-IoT). Furthermore, communication between terminal devices and network devices in a communication network may be performed according to any suitable generation communication protocol, including, but not limited to, first generation (1G), second generation (2G), 2.5G, 2.75G, third generation (3G), fourth generation (4G), or 4.5G, a fifth-generation (5G) New Radio (NR) communication protocol, and / or any other protocol currently known or developed in the future. Embodiments of the present disclosure may be applied to various communication systems. Given the rapid development of communications, there will naturally be future types of communication technologies and systems in which the present disclosure may be embodied. This should not be understood as limiting the scope of the present disclosure to only the aforementioned systems.

[0027] As used herein, the term "network device" refers to a node in a communication network through which a terminal device accesses the network and receives services therefrom. A network device may refer to a base station (BS) or Radio Access Network (RAN) node or access point (AP), e.g., a Node B (NodeB or NB), evolved Node B (eNodeB or eNB), next generation Node B (NR NB or gNB), remote radio unit (RRU), radio header (RH), remote radio head (RRH), integrated access and backhaul (IAB) node, low-power node such as relay, femto, pico, etc., depending on the terminology and technology applied. A network device may be defined as part of a gNB, e.g., in a CU / DU split, in which case the network device is defined to be either a gNB central unit (gNB-CU) or a gNB distributed unit (gNB-DU).

[0028] The term "terminal device" refers to any end device that may be capable of wireless communication. By way of example and not limitation, a terminal device may also be referred to as a communication device, user equipment (UE), subscriber station (SS), portable subscriber station, mobile station (MS), or access terminal (AT). Terminal devices may include, but are not limited to, mobile phones, cellular phones, smartphones, voice-over-IP (VoIP) phones, wireless local loop phones, tablets, wearable terminal devices, personal digital assistants (PDAs), portable computers, desktop computers, image capture terminal devices such as digital cameras, gaming terminal devices, music storage and playback equipment, vehicle-mounted wireless terminal devices, wireless endpoints, mobile stations, laptop embedded equipment (LEE), laptop mounted equipment (LME), USB dongles, smart devices, wireless customer premises equipment (CPE), Internet of Things (IoT) devices, watches or other wearables, head-mounted displays (HMD), vehicles, drones, medical devices and applications (e.g., remote surgery), industrial devices and applications (e.g., robots and / or other wireless devices operating in industrial and / or automated processing chain contexts), consumer electronics devices, devices operating on commercial and / or industrial wireless networks, etc. Terminal devices may also correspond to the mobile termination (MT) portion of an integrated access and backhaul (IAB) node (also known as a relay node). In the following description, the terms "terminal device", "communication device", "terminal", "user equipment", and "UE" may be used interchangeably.

[0029] While the functionality described herein may be performed in fixed and / or wireless network nodes in various exemplary embodiments, in other exemplary embodiments, the functionality may be implemented in a user equipment device (such as a mobile phone, tablet computer, laptop computer, desktop computer, mobile IoT device, or fixed IoT device). This user equipment device may, for example, have corresponding capabilities as described in connection with the fixed and / or wireless network nodes, as appropriate. The user equipment device may be user equipment and / or a control device, such as a chipset or processor, configured to control the user equipment when installed therein. Examples of such functionality include a bootstrapping server function and / or a home subscriber server, which may be implemented in the user equipment device by providing the user equipment device with software configured to cause the user equipment device to perform functions / nodes in terms of these functions / nodes.

[0030] [Example environment] 1 illustrates an exemplary communication environment 100 in which exemplary embodiments of the present disclosure may be implemented. The communication environment 100 may be a communication system that supports sidelink relay. As shown in FIG. 1, the communication environment 100 includes a first device 110, a second device 120, a third device 130, and a fourth device 140.

[0031] The first device 110 and the second device 120 may be terminal devices such as UEs. Specifically, the first device 110 serves as a relay UE, which may also be referred to as a UE-to-Network relay UE. The second device 120 serves as a remote UE, such as a smart watch, glasses, etc. Hereinafter, the first device 110 and the second device 120 may also be referred to as a relay UE 110 and a remote UE 120, respectively.

[0032] The third device 130 and the fourth device 140 may be network devices, such as gNBs, transmit / receive points (TRPs), etc., that provide cells 102 and 104 for radio coverage, respectively. In the example shown in FIG. 1 , the first device 110 is initially located within the cell 102 and is served by the third device 130. The second device 120 is outside the cell 102 and connected to the network via the relay UE 110. Alternatively, as another example, the second device 120 may be inside the cell 102 but connected to the network via an indirect path via the relay UE 110. The first device 110 and the second device 120 may communicate with each other via a PC5 interface.

[0033] The fourth device 140 serves a neighboring cell 104. Hereinafter, the third device 130 and the fourth device 140 may also be referred to as a serving gNB 130 or a source gNB 130 and a target gNB 140, respectively. Furthermore, the cells 102 and 104 may also be referred to as a serving cell 102, a neighboring cell 104, or a target cell 104, respectively. In the example shown in FIG. 1, the first device 110 may perform a handover from the serving cell 102 to the neighboring cell 104. The first device 110 may communicate with the third device 130 or the fourth device 140 via a Uu interface.

[0034] In some exemplary embodiments, the link from the terminal device to the network device is referred to as the uplink (UL), and the link from the network device to the terminal device is referred to as the downlink (DL).

[0035] It should be understood that the number of devices and their connections shown in Figure 1 are for illustrative purposes only, without implying any limitation. Communications network 100 may include any suitable number of devices configured to implement exemplary embodiments of the present disclosure. Although not shown, it will be appreciated that one or more additional devices and connections may be deployed within communications network 100.

[0036] For purposes of explanation, the following describes some exemplary embodiments in which the first device 110 and the second device 120 operate as terminal devices (e.g., UEs) and the third device 130 and the fourth device 140 operate as network devices (e.g., gNBs, TRPs, etc.). However, in some exemplary embodiments, operations described with reference to terminal devices may be implemented in network devices or other devices, and operations described with reference to network devices may be implemented in terminal devices or other devices.

[0037] Communications in communication environment 100 may be implemented according to any suitable communications protocol, including, but not limited to, cellular communications protocols such as first generation (1G), second generation (2G), third generation (3G), fourth generation (4G), fifth generation (5G), sixth generation (6G), wireless local network communications protocols such as IEEE (Institute for Electrical and Electronics Engineers) 802.11, and / or any other protocols now known or developed in the future. Furthermore, communications may utilize any suitable wireless communications technology, including, but not limited to, code division multiple access (CDMA), frequency division multiple access (FDMA), time division multiple access (TDMA), frequency division duplex (FDD), time division duplex (TDD), multiple input multiple output (MIMO), orthogonal frequency division multiple access (OFDM) discrete Fourier transform spread OFDM (DFT-s-OFDM), and / or any other technology now known or developed in the future.

[0038] To hand over at least one remote UE to a target RAN node, the source RAN node sends a handover (HO) command to the at least one remote UE via a relay UE. The HO command may be carried in a radio resource control (RRC) reconfiguration message. This is performed while the relay UE is still connected to the source cell. However, if the at least one remote UE applies a new RRC configuration (e.g., a new security key associated with the target RAN node) immediately after receiving the HO command, this may cause a problem in that traffic of the at least one remote UE transmitted based on the new RRC configuration cannot be forwarded to the target RAN node unless the relay UE has performed HO to the target cell itself.

[0039] For example, a relay UE may detach from a source cell quite late after sending an RRC reconfiguration to the remote UE. Additionally or alternatively, the relay UE may fail to connect to the target RAN node and need to reestablish an RRC connection with a different RAN node. This may cause the remote UE to incorrectly apply the RRC reconfiguration that should be used for communication with the target RAN node when the remote UE still communicates with the source RAN node via the relay UE. Furthermore, the source RAN node must ensure that reconfigurations for connected remote UEs are issued immediately before reconfigurations for the relay UE. In some cases where radio signals may rapidly degrade, there is no guarantee that all connected remote UEs will receive the RRC reconfiguration immediately before the relay UE detaches from the source cell.

[0040] It is therefore expected that the relay UE and at least one remote UE are both handed over to the target cell and can apply the RRC configuration for the source cell or the target cell in a synchronized manner.

[0041] [Working principles and signaling examples for communication] According to some example embodiments of the present disclosure, an HO solution is provided, in which, in response to receiving a first message from a third device for initiating HO associated with a first device and a second device, the first device performs an HO procedure to a target cell indicated in the first message. The first device acts as a UE-to-network relay for the second device to communicate with the third device. The first device then sends at least one indication to the second device based on the HO procedure.

[0042] In this solution, at least one candidate cell configuration and a set of conditions related to the relay UE are provided to at least one remote UE. The set of conditions includes at least a set of PC5 conditions or events. When the source gNB initiates the HO procedure, the relay UE can send an indication of the PC5 conditions or events related to the HO procedure. Thus, corresponding configurations are triggered in the remote UE. In this way, the relay UE and the remote UE can be coordinated on their actions regarding performing HO and applying corresponding configurations for the source or target cell.

[0043] Preferred embodiments of the present disclosure will be described in detail below with reference to the accompanying drawings.

[0044] Reference is now made to Figure 2, which illustrates a signaling chart for handover of a first device and a second device, in accordance with some example embodiments of the present disclosure. As shown in Figure 2, process 200 includes first device 110, second device 120, third device 130, and fourth device 140. For purposes of explanation, reference is made to Figure 1 to describe signaling flow 200.

[0045] In process 200, the second device 120 (i.e., a remote UE) is initially connected to the third device 130 (i.e., a source gNB) through the first device 110 (i.e., a relay UE). Thus, UL and DL data between the second device 120 and the third device 130 is communicated through the first device 110 (202).

[0046] The third device 130 determines (204) that HO relating to the first device 110 and the second device 120 should be performed. In some example embodiments, such HO decision may be made based on a “group” instruction from the second device 120, or from the first device 110, or from the core network (CN).

[0047] In some demonstrative embodiments, the third device 130 may initiate 206 an HO preparation procedure for the second device 120 by sending an HO request message to a neighboring gNB, for example, the fourth device 140. The HO request message may include a “group” indication and information about the first device 110.

[0048] In some demonstrative embodiments, the fourth device 140 may accept the HO by responding 208 to the third device 130 with an HO request acknowledgement message.

[0049] Upon receiving the HO request acknowledgement message, the third device 130 generates (210) a second message comprising at least one candidate cell configuration and a set of conditions associated with the first device 110. The second message may be, for example, an RRC reconfiguration message, which may be considered a conditional RRCReconfiguration message.

[0050] The set of conditions may include a set of PC5 conditions or events. In some exemplary embodiments, the third device 130 may decide to add a set of PC5 conditions to the RRC reconfiguration message. This may be added in addition to or instead of the condition based on Uu measurements in a normal conditional handover (CHO). For example, the RRC reconfiguration message may include both PC5 conditions and Uu conditions.

[0051] In some exemplary embodiments, the term "conditional handover" or "CHO" refers to a handover that is executed by a UE when one or more handover execution conditions are met. In particular, the UE starts evaluating the at least one execution condition when it receives a CHO configuration and stops evaluating the at least one execution condition when the handover is executed.

[0052] The PC5 condition may refer to, for example, a condition used when the second device 120 remains connected to the first device 110 and connects to the fourth device 140. The Uu condition may refer to, for example, a condition used when the second device 120 performs an indirect direct path switch and connects to the fourth device 140.

[0053] In some exemplary embodiments, the set of conditions may include at least one of the following: A condition for "suspending UL transmission", also referred to as a first condition, related to suspending data transmission to the third device 130 via the second device 120, in which if the first condition is met, the second device 120 suspends UL transmission over the PC5 interface. The second device 120 may continue DL reception by using a current RRC reconfiguration, e.g., a PC5 configuration and security keys associated with the third device 130. A condition for “resume in new configuration”, also referred to as a second condition, related to resuming in one of the at least one candidate cell configuration, in which if the second condition is met, the second device 120 performs an associated RRC reconfiguration and resumes UL transmission or DL ​​reception by using a new configuration, e.g., PC5 configuration, security key, associated with the fourth device 140. A condition for “resume old configuration”, also referred to as a third condition related to resuming the source cell configuration, in which if the third condition is met, the second device 120 discards at least one candidate cell configuration and resumes UL transmission or DL ​​reception by using a security key associated with the old configuration, e.g., the third device 130. A "discard and re-establish" condition, also referred to as a fourth condition, related to discarding at least one candidate cell configuration and initiating a re-establishment procedure, in which if the fourth condition is met, the second device 120 discards at least one candidate cell configuration and initiates an RRC re-establishment procedure.

[0054] The third device 130 then sends (212) a second message (e.g., an RRC reconfiguration message) to the second device 120 via the first device 110. In some exemplary embodiments, the second device 120 may buffer the received RRC reconfiguration message that includes the set of conditions.

[0055] Accordingly, the second device 120 may send an RRC reconfiguration complete message to the third device 130 via the first device 110 (214).

[0056] Upon receiving the RRC reconfiguration complete message, the third device 130 may initiate an HO preparation procedure for the first device 110 by sending (216) an HO request message including a “group” indication and information about the associated remote UE, i.e., the second device 120.

[0057] In response to the HO request message, the fourth device 140 may send an HO request acknowledgement message to the third device 130 (218).

[0058] Accordingly, the third device 130 sends 220 a first message to initiate the HO to the first device 110. The first message may be, for example, an HO command.

[0059] The HO command informs the first device 110 that a HO is being performed and that the second device 120 will be handed over together with the first device 110. In response to the first message, the first device 110 performs 222 a HO procedure to the target cell indicated in the first message. In particular, the first device 110 can touch down from the source cell 102. In the example of FIG. 1, the candidate cells may include the neighbor cell 104.

[0060] The first device 110 then transmits 224 at least one instruction based on the HO procedure to the second device 120. As described above, a set of conditions may correspond to the at least one instruction.

[0061] Depending on the indication, the behavior of the second device 120 may differ. In some demonstrative embodiments, the at least one indication may include an indication of an HO procedure being initiated at the first device 110. Thus, the second device 120 may be notified that the first device 110 is being touched by the source cell 102.

[0062] Additionally or alternatively, the at least one instruction may include an instruction to suspend UL transmissions from the second device 120 to the third device 130 via the first device 110. This instruction may also be referred to as a “suspend” instruction. As a result, upon receiving this instruction from the first device 110 via PC5, the second device 120 may suspend UL transmissions via PC5. The second device 120 may continue DL reception by applying the current RRC configuration (e.g., PC5 configuration and security keys associated with the serving gNB 130).

[0063] It should be noted that the HO command to the second device 120 in step 212 may implicitly or explicitly indicate that the CHO is tied to the ongoing HO of the first device 110. Thus, in some cases, this may allow the second device 120 to skip the HO initiation indication from the first device 110 in step 224, since the second device 120 is already aware of the ongoing HO of the first device 110 and may already suspend UL transmission immediately after receiving the HO command in step 212. Nevertheless, it is still beneficial to send the HO initiation indication, since the time period between the sending of the HO command in step 212 and the sending of the HO initiation indication may vary. Thus, sending the HO initiation indication may allow the second device 120 to transmit UL data within this time period. It should be understood that the sending of the HO initiation indication may be performed before detaching from the source cell 102, or alternatively, in parallel with detaching from the source cell 102.

[0064] In the above embodiment, upon receiving the instruction, the second device 120 may detect that the first condition for "suspending UL transmission" is met. Thus, the second device 120 may suspend UL transmission (226). Additionally, if the first device 110 still has buffered DL data for the second device 120, the first device 110 may continue to relay the DL data to the second device 120.

[0065] If the HO procedure is successful, the first device 110 may connect to the target cell 104. After the first device 110 connects to the target cell 104, the first device 110 may send an HO complete message to the fourth device 140 (228). Additionally, the first device 110 may send an indication to the second device 120 over the PC5 interface to resume with the target cell configuration (230). This indication informs the second device 120 to apply the buffered configuration associated with the target cell 104 and to resume data and / or signaling transmission and reception with the target cell 104 via the first device 110.

[0066] In certain example embodiments, the second device 120 may receive multiple RRCReconfigurations, each corresponding to a cell of the fourth device 140. When the first device 110 connects to a particular cell of the fourth device 140 and informs the second device 120 of the particular cell, the second device 120 should perform the associated RRCReconfiguration.

[0067] Upon receiving the indication to resume with the target cell configuration, the second device 120 may detect that the second condition, "resume with new configuration," has been met. Accordingly, the second device 120 may execute the previously buffered RRCReconfiguration (232).

[0068] Additionally, in some demonstrative embodiments, second device 120 may then send an HO complete message to fourth device 140 via first device 110 (234). Thus, UL and DL data is resumed between second device 120 and fourth device 140 via first device 110 (236).

[0069] Otherwise, if in step 222 the first device 110 fails to connect to the target cell 104, in other words, if the HO procedure fails, the first device 110 may reconnect with the source cell 102. In this case, the first device 110 may send an instruction to "resume with old configuration" to the second device 120 via PC5.

[0070] In the above embodiment, upon receiving this indication, the second device 120 may detect that the third condition, "resume with old configuration," is met. In this case, the second device 120 may discard the previously buffered RRCR configuration of the target cell 104 and resume UL and DL data with the old configuration of the source cell 102.

[0071] Alternatively, in some exemplary embodiments, if in step 222 the first device 110 fails to connect to the target cell 104, the first device 110 may not reconnect with the source cell 102, but may reconnect with another gNB that is not prepared. In this case, the first device 110 may perform a re-establishment procedure with a cell of the other gNB, the cell being different from the source cell 102 and the at least one candidate cell. The first device 110 may then send a "tear down and re-establish" instruction to the second device 120 via PC5, which corresponds to the fourth condition.

[0072] In the above embodiment, upon receiving this indication, the second device 120 may detect that the fourth condition for "tear down and re-establishment" is met. Thus, the second device 120 may tear down the previously buffered RRCReconfiguration and initiate the RRC re-establishment procedure.

[0073] It should be understood that some of the steps in process 200 are optional or can be omitted. Furthermore, the order of the steps is given for illustrative purposes, and a different order of the steps or more or fewer steps may also be applicable to implement the proposed solution. Accordingly, embodiments of the present disclosure are not limited in this respect.

[0074] According to an example embodiment of the present disclosure, handovers of a relay UE and a remote UE to the same target gNB may be performed jointly via a conditional RRC Reconfiguration, which is triggered by a PC5 condition or event related to HO for the relay UE. As a result, the behavior of the remote UE may be aligned with the behavior of the relay UE when performing a handover, and system performance and reliability may be improved.

[0075] [Example Method] 3 illustrates a flowchart of a method 300 implemented in a first device according to some exemplary embodiments of the present disclosure. For example, the first device may include a terminal device. For illustrative purposes, the method 300 will be described from the perspective of the first device 110 of FIG. 1.

[0076] At block 310, the first device 110 receives a first message from the third device 130 to initiate a handover involving the first device 110 and the second device 120. The first device 110 acts as a UE-to-network relay for the second device 120 to communicate with the third device 130. The third device 130 may act as a source gNB that provides a serving cell 102 for the first device 110.

[0077] In response to receiving the first message, at block 320, the first device 110 performs a handover procedure to the target cell indicated in the first message.

[0078] At block 330, the first device 110 sends at least one indication to the second device 120 based on the handover procedure.

[0079] In some exemplary embodiments, the step of transmitting at least one instruction may include transmitting to the second device 120 at least one of an instruction to initiate a handover procedure at the first device 110 or an instruction to suspend uplink transmission from the second device 120 to the third device 130 via the first device 110.

[0080] In some demonstrative embodiments, the first device 110 may be further configured to perform the steps of determining that at least one downlink data from the third device 130 to the second device 120 is buffered at the first device 110, and transmitting the at least one downlink data to the second device 120 in accordance with the determination that the at least one downlink data is buffered.

[0081] In some exemplary embodiments, the step of transmitting at least one instruction may include determining that the handover procedure to the target cell has been successfully performed, and, in accordance with the determination that the handover procedure has been successfully performed, transmitting an instruction to the second device 120 to resume with the target cell configuration, the instruction instructing the second device 120 to apply a configuration associated with the target cell and resume data and / or signaling transmission and reception with the target cell via the first device 110.

[0082] In some demonstrative embodiments, transmitting the at least one instruction may include determining that the handover procedure failed and, according to a determination that the first device 110 has reconnected with the source cell after the handover procedure failed, transmitting an instruction to the second device 120 to resume with the source cell configuration. The instruction may instruct the second device 120 to apply a configuration associated with the source cell 102 and resume data and / or signaling transmission and reception with the source cell via the first device 110.

[0083] In some exemplary embodiments, the step of sending at least one instruction may include the steps of determining that the handover procedure has failed, performing a re-establishment procedure with a cell other than the source cell and the target cell in accordance with the determination that the handover procedure has failed, and sending a re-establishment instruction to the second device 120 in accordance with the determination that the re-establishment procedure has been successfully performed, wherein the re-establishment instruction instructs the second device 120 to discard at least one candidate cell configuration and initiate the re-establishment procedure with the cell via the first device 110.

[0084] In some demonstrative embodiments, the first device 110 may comprise a relay terminal device, the second device 120 may comprise a remote terminal device, and the third device 130 may comprise a network device.

[0085] 4 illustrates a flowchart of an example method 400 implemented in a second device in accordance with some example embodiments of the present disclosure. For example, the second device may include a remote UE connected to the network via a relay UE. For illustrative purposes, the method 400 will be described from the perspective of the second device 120 of FIG. 1.

[0086] In step 410, the second device 120 receives a second message from the third device 130 via the first device 110, the second message comprising at least one candidate cell configuration and a set of conditions associated with the first device 110. The first device 110 acts as a UE-to-network relay for the second device 120 to communicate with the third device 130.

[0087] In some exemplary embodiments, the second message may comprise an RRC reconfiguration message and further comprises a measurement configuration related to an interface (e.g., a Uu interface) between the second device 120 and the third device 130.

[0088] In some exemplary embodiments, the set of conditions may include at least one of the following: a first condition related to interrupting data transmission to the third device 130 via the first device 110; A second condition related to restarting in one of the at least one candidate cell configuration. The third condition is related to the resumption of the source cell configuration. A fourth condition related to abandoning at least one candidate cell configuration and initiating a re-establishment procedure.

[0089] In step 420, the second device 120 receives from the first device 110 at least one instruction corresponding to at least one of the set of conditions.

[0090] In some demonstrative embodiments, method 400 may include determining, in response to receiving the second message, that a first condition is met, and suspending uplink transmission to third device 130 via first device 110 in accordance with the determination that the first condition is met.

[0091] In some exemplary embodiments, receiving at least one indication includes receiving an indication from the first device 110 that a handover procedure has been initiated at the first device 110, the indication corresponding to a first condition.

[0092] In some demonstrative embodiments, the method 400 may include determining that the first condition is met in response to receiving an indication corresponding to the first condition, and suspending uplink transmission to the third device 130 via the first device 110 in accordance with the determination that the first condition is met.

[0093] In some demonstrative embodiments, method 400 may include receiving, from first device 110, at least one downlink data transmission transmitted by third device 130.

[0094] In some demonstrative embodiments, receiving the at least one instruction may include receiving, from the first device 110, an instruction to resume in the target cell configuration, at least one candidate cell that comprises the target cell, and an instruction corresponding to the second condition.

[0095] In some demonstrative embodiments, method 400 may include determining, in response to receiving the indication, that a second condition is met; determining a target cell configuration from the at least one candidate cell configuration according to the determination that the second condition is met; and applying the target cell configuration and resuming data and / or signaling transmission and reception.

[0096] In some demonstrative embodiments, receiving at least one indication may include receiving an indication from the first device 110 to resume with the source cell configuration, the indication corresponding to a third condition.

[0097] Additionally or alternatively, in some exemplary embodiments, method 400 may further include, in response to receiving the indication, determining that a third condition is met; discarding the at least one candidate cell configuration in accordance with the determination that the third condition is met; and applying the source cell configuration and resuming data and / or signaling transmission and reception.

[0098] In some demonstrative embodiments, receiving at least one indication may include receiving, from first device 110, a re-establishment indication corresponding to a fourth condition.

[0099] In some demonstrative embodiments, the method 400 may include discarding the at least one candidate cell configuration and initiating a re-establishment procedure in accordance with a determination that the fourth condition is met.

[0100] In some demonstrative embodiments, the first device 110 may comprise a relay terminal device, the second device 120 may comprise a remote terminal device, and the third device 130 may comprise a network device.

[0101] 5 shows a flowchart of an example method 500 implemented in a third device according to some exemplary embodiments of the present disclosure. For example, the third device may include a network device, such as a serving gNB. For illustrative purposes, the method 500 will be described from the perspective of the third device 130 of FIG. 1.

[0102] At block 510, the third device 130 determines whether a handover involving the first device 110 and the second device 120 should be performed.

[0103] If a handover is to be performed, in block 520, the third device 130 generates a second message comprising at least one candidate cell configuration and a set of conditions associated with the first device 110. The first device 110 acts as a UE-to-network relay for the second device 120 to communicate with the third device 130. Each of the sets of conditions corresponds to at least one instruction to be sent from the first device 110 to the second device 120.

[0104] At block 530 , the third device 130 sends a second message to the second device 120 via the first device 110 .

[0105] At block 540, the third device 130 sends a first message to the first device 110 to initiate the handover.

[0106] In some demonstrative embodiments, the second message may comprise an RRC reconfiguration message and further comprises a measurement configuration related to an interface between the second device 120 and the third device 130. The interface may be, for example, a Uu interface.

[0107] In some example embodiments, the set of conditions may include at least one of the following: a first condition related to interrupting data transmission to the third device 130 via the second device 120; A second condition related to restarting in one of the at least one candidate cell configuration. The third condition is related to restarting with the source cell configuration. A fourth condition related to abandoning at least one candidate cell configuration and initiating a re-establishment procedure.

[0108] In some demonstrative embodiments, the first device 110 may comprise a relay terminal device, the second device 120 may comprise a remote terminal device, and the third device 130 may comprise a network device.

[0109] [Example Apparatus, Device and Media] In some demonstrative embodiments, a first apparatus capable of performing any of the methods 300 (e.g., the first device 110 of FIG. 1 ) may comprise means for performing each operation of the method 300. The means may be implemented in any suitable form. For example, the means may be implemented in a circuit or a software module. The first apparatus may be implemented as or included in the first device 110 of FIG. 1 .

[0110] In some demonstrative embodiments, the first device may include means for, in response to receiving from a third device a first message for initiating a handover relating to the first device and the second device, performing a handover procedure to a target cell indicated in the first message, wherein the first device may include means for acting as a UE-to-network relay for the second device to communicate with the third device, and means for sending to the second device at least one instruction based on the handover procedure.

[0111] In some demonstrative embodiments, the means for transmitting at least one instruction may include means for transmitting to the second device at least one of an instruction of a handover procedure being initiated at the first device or an instruction to suspend uplink transmission from the second device to the third device via the first device.

[0112] In some demonstrative embodiments, the first device may include means for determining that at least one downlink data from the third device to the second device is buffered at the first device, and means for transmitting the at least one downlink data to the second device according to the determination that the at least one downlink data is buffered.

[0113] In some exemplary embodiments, the means for transmitting at least one instruction may include means for determining that the handover procedure has been successfully performed to the target cell, and means for transmitting an instruction to the second device to resume with the target cell configuration according to the determination that the handover procedure has been successfully performed, the instruction instructing the second device to apply a configuration associated with the target cell and resume data and / or signaling transmission and reception with the target cell via the first device.

[0114] In some demonstrative embodiments, the means for transmitting at least one instruction may include means for determining that the handover procedure has failed, means for acting in accordance with a determination that the first device has reconnected with the source cell after the handover procedure has failed, and means for transmitting an instruction to resume with the source cell configuration to the second device, the instruction instructing the second device to apply a configuration associated with the source cell and resume data and / or signaling transmission and reception with the source cell via the first device.

[0115] In some demonstrative embodiments, the means for transmitting at least one instruction may include means for determining that the handover procedure has failed; means for performing a re-establishment procedure with a cell other than the source cell and the target cell in accordance with a determination that the handover procedure has failed; and means for transmitting a re-establishment instruction to the second device in accordance with a determination that the re-establishment procedure has been successfully performed, the re-establishment instruction instructing the second device to discard at least one candidate cell configuration; and means for initiating the re-establishment procedure with the cell via the first device.

[0116] In some exemplary embodiments, the first apparatus comprises a relay terminal device, the second apparatus comprises a remote terminal device, and the third apparatus comprises a network device.

[0117] In some demonstrative embodiments, a second apparatus capable of performing any of the methods 400 (e.g., the second device 120 of FIG. 1 ) may comprise means for performing each operation of the method 400. The means may be implemented in any suitable form. For example, the means may be implemented in a circuit or a software module. The second apparatus may be implemented as or included in the second device 120 of FIG. 1 .

[0118] In some demonstrative embodiments, the second device may include means for receiving, from the third device via the first device, a second message comprising at least one candidate cell configuration and a set of conditions associated with the first device, wherein the first device acts as a UE-to-network relay for the second device to communicate with the third device, and means for receiving, from the first device, at least one indication corresponding to at least one of the set of conditions.

[0119] In some exemplary embodiments, the second message comprises a radio resource control reconfiguration message and further comprises a measurement configuration related to an interface between the second device and the third device.

[0120] In some demonstrative embodiments, the set of conditions may include at least one of a first condition related to suspending data transmission to the third device via the first device, a second condition related to resuming one of the at least one candidate cell configurations, a third condition related to resuming the source cell configuration, and a fourth condition related to abandoning the at least one candidate cell configuration and initiating a re-establishment procedure.

[0121] In some demonstrative embodiments, the second device may include means for determining, in response to receiving the second message, that a first condition is met, and means for suspending uplink transmission to the third device via the first device in accordance with a determination that the first condition is met.

[0122] In some demonstrative embodiments, the means for receiving at least one indication includes receiving an indication from the first device that a handover procedure is being initiated at the first device, the indication corresponding to the first condition.

[0123] In some demonstrative embodiments, the second device may include means for determining, in response to receiving an indication corresponding to the first condition, that the first condition is met, and means for suspending uplink transmissions to the third device via the first device in accordance with the determination that the first condition is met.

[0124] In some demonstrative embodiments, the second apparatus may include means for receiving, from the first apparatus, at least one downlink data transmission transmitted by the third apparatus.

[0125] In some demonstrative embodiments, the means for receiving at least one indication may include means for receiving, from the first device, an indication to resume in the target cell configuration, at least one candidate cell comprising the target cell, and an indication corresponding to the second condition.

[0126] In some demonstrative embodiments, the second apparatus may include means for determining, in response to receiving the indication, that a second condition is met; means for determining a target cell configuration from the at least one candidate cell configuration according to the determination that the second condition is met; and means for applying the target cell configuration and resuming data and / or signaling transmission and reception.

[0127] In some exemplary embodiments, the means for receiving at least one indication includes means for receiving, from the first device, an indication to resume with the source cell configuration, the indication corresponding to a third condition.

[0128] In some demonstrative embodiments, the second apparatus may include means for determining, in response to receiving the indication, that a third condition is met; means for discarding the at least one candidate cell configuration in accordance with the determination that the third condition is met; and means for applying the source cell configuration and resuming data and / or signaling transmission and reception.

[0129] In some demonstrative embodiments, the means for receiving at least one indication may include means for receiving, from the first device, a re-establishment indication corresponding to the fourth condition.

[0130] In some demonstrative embodiments, the second apparatus may include means for discarding the at least one candidate cell configuration according to a determination that the fourth condition is met, and means for initiating a re-establishment procedure.

[0131] In some exemplary embodiments, the first apparatus comprises a relay terminal device, the second apparatus comprises a remote terminal device, and the third apparatus comprises a network device.

[0132] In some demonstrative embodiments, a third apparatus capable of performing any of the methods 500 (e.g., the third device 130 of FIG. 1 ) may comprise means for performing each operation of the method 500. The means may be implemented in any suitable form. For example, the means may be implemented in a circuit or a software module. The second apparatus may be implemented as or included in the third device 130 of FIG. 1 .

[0133] In some demonstrative embodiments, the third device may include means for generating, in accordance with a determination that a handover related to the first device and the second device should be performed, a second message comprising at least one candidate cell configuration and a set of conditions related to the first device, wherein the first device acts as a UE-to-network relay for the second device to communicate with the third device, each of the sets of conditions corresponding to at least one instruction to be sent from the first device to the second device; means for transmitting the second message to the second device via the first device; and means for transmitting the first message to the first device to initiate the handover.

[0134] In some exemplary embodiments, the second message comprises a radio resource control reconfiguration message and further comprises a measurement configuration related to an interface between the second device and the third device.

[0135] In some demonstrative embodiments, the set of conditions may include at least one of a first condition related to suspending data transmission to the third device via the second device, a second condition related to resuming one of the at least one candidate cell configurations, a third condition related to resuming the source cell configuration, and a fourth condition related to abandoning the at least one candidate cell configuration and initiating a re-establishment procedure.

[0136] In some exemplary embodiments, the first apparatus comprises a relay terminal device, the second apparatus comprises a remote terminal device, and the third apparatus comprises a network device.

[0137] 6 is a simplified block diagram of a device 600 suitable for implementing an exemplary embodiment of the present disclosure. Device 600 may be provided to implement an electronic device, such as first device 110, second device 120, third device 130, or fourth device 140 as shown in FIG. 1. As shown, device 600 includes one or more processors 610, one or more memories 620 coupled to processor 610, and one or more communication modules 640 coupled to processor 610.

[0138] The communications module 640 is for bidirectional communication. The communications module 640 has one or more communications interfaces to facilitate communication with one or more other modules or devices. The communications interfaces may represent any interface necessary for communication with other network elements. In some demonstrative embodiments, the communications module 640 may include at least one antenna.

[0139] Processor 610 may be of any type suitable for a local technology network and may include, by way of non-limiting example, one or more of a general-purpose computer, a special-purpose computer, a microprocessor, a digital signal processor (DSP), and a processor based on a multi-core processor architecture. Device 600 may include multiple processors, such as application-specific integrated circuit chips that are time-slaved to a clock that synchronizes a main processor.

[0140] The memory 620 may include one or more nonvolatile memories and one or more volatile memories. Examples of nonvolatile memory include, but are not limited to, read-only memory (ROM) 624, electrically programmable read-only memory (EPROM), flash memory, hard disks, compact disks (CDs), digital video disks (DVDs), optical disks, laser disks, and other magnetic and / or optical storage. Examples of volatile memory include, but are not limited to, random access memory (RAM) 622 and other volatile memory that does not persist during power-down durations.

[0141] The computer program 630 includes computer-executable instructions that are executed by the associated processor 610. The instructions of the program 630 may include instructions for performing the operations / acts of some exemplary embodiments of the present disclosure. The program 630 may be stored in a memory, such as the ROM 624. The processor 610 may perform any appropriate actions and processes by loading the program 630 into the RAM 622.

[0142] An exemplary embodiment of the present disclosure may be implemented by a program 630 such that the device 600 may execute any process of the present disclosure, as discussed with reference to Figures 2 to 5. An exemplary embodiment of the present disclosure may also be implemented by hardware or a combination of software and hardware.

[0143] In some exemplary embodiments, the program 630 may be tangibly contained in a computer-readable medium, which may be included in the device 600 (such as memory 620) or other storage device accessible by the device 600. The device 600 may load the program 630 from the computer-readable medium into RAM 622 for execution. In some exemplary embodiments, the computer-readable medium may include any type of non-transitory storage medium, such as ROM, EPROM, flash memory, hard disk, CD, DVD, etc. The term "non-transitory" as used herein is a limitation of the medium itself (i.e., tangible as opposed to a signal) as opposed to a limitation to data storage permanence (e.g., RAM vs. ROM).

[0144] 7 shows an example of a computer readable medium 700, which may be in the form of a CD, DVD or other optical storage disc. The computer readable medium 700 has the program 630 stored thereon.

[0145] In general, various embodiments of the present disclosure may be implemented in hardware or special purpose circuits, software, logic, or any combination thereof. While some aspects may be implemented in hardware, other aspects may be implemented in firmware or software that may be executed by a controller, microprocessor, or other computing device. While various aspects of the embodiments of the present disclosure are illustrated and described as block diagrams, flowcharts, or using some other pictorial representations, it should be understood that the blocks, apparatus, systems, techniques, or methods described herein may be implemented in, by way of non-limiting example, hardware, software, firmware, special purpose circuits or logic, general purpose hardware or controller, or other computing device, or some combination thereof.

[0146] Some exemplary embodiments of the present disclosure also provide at least one computer program product tangibly stored on a computer-readable medium, such as a non-transitory computer-readable medium. The computer program product includes computer-executable instructions, such as those included in program modules, that execute on a target physical or virtual processor device to perform any of the methods described above. Generally, program modules include routines, programs, libraries, objects, classes, components, data structures, etc. that perform particular tasks or implement particular abstract data types. The functionality of the program modules may be combined or divided among program modules as desired in various embodiments. Machine-executable instructions for program modules may be executed in local or distributed devices. In distributed devices, program modules may be located in both local and remote storage media.

[0147] Program code for carrying out the methods of the present disclosure may be written in any combination of one or more programming languages. The program code may be provided to a processor or controller of a general-purpose computer, a special-purpose computer, or other programmable data processing apparatus, so that when executed by the processor or controller, the program code implements the functions / acts specified in the flowcharts and / or block diagrams. The program code may run entirely on the machine, partially on the machine, as a stand-alone software package, partially on the machine, partially on a remote machine, or entirely on a remote machine or server.

[0148] In the context of the present disclosure, computer program code or associated data may be carried by any suitable carrier to enable a device, apparatus, or processor to perform the various processes and operations as described above. Examples of carriers include signals, computer-readable media, etc.

[0149] The computer-readable medium may be a computer-readable signal medium or a computer-readable storage medium. The computer-readable medium may include, but is 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 computer-readable storage medium may be 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 storage device including a portable compact disc read-only memory (CD-ROM), a magnetic storage device, or any suitable combination thereof.

[0150] Furthermore, while operations are shown in a particular order, this should not be understood as requiring such operations to be performed in the particular order shown, or in any sequential order, or that all of the shown operations be performed, to achieve desirable results. In some situations, multitasking and parallel processing may be advantageous. Similarly, while some specific implementation details are included in the above description, these should not be construed as limitations on the scope of the disclosure, but rather as descriptions of features that may be specific to particular embodiments. Unless expressly stated otherwise, certain features that are described in the context of separate embodiments may also be implemented in combination in a single embodiment. Conversely, unless expressly stated otherwise, various features that are described in the context of a single embodiment may also be implemented in multiple embodiments separately or in any suitable subcombination.

[0151] 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, as defined by 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

1. at least one processor; and at least one memory storing instructions that, when executed by the at least one processor, cause the first device to: In response to receiving a first message from a third device to initiate a handover involving the first device and the second device, performing, at the first device, a handover procedure to a target cell indicated in the first message, wherein the first device acts as a UE-to-network relay for the second device to communicate with the third device; and transmitting to the second device at least one instruction based on the handover procedure.

2. The step of transmitting at least one instruction comprises: an indication that the handover procedure is to be initiated at the first device; or an instruction to suspend uplink transmission from the second device to the third device via the first device; 10. The first device of claim 1, further comprising the step of transmitting at least one of:

3. The first device determining that at least one downlink data from the third device to the second device is buffered at the first device; and transmitting the at least one downlink data to the second device in accordance with a determination that the at least one downlink data is buffered.

4. The step of transmitting at least one instruction comprises: determining that the handover procedure to the target cell has been successfully performed; 4. The first device according to claim 1, further comprising: a step of: transmitting an instruction to the second device to resume with a target cell configuration according to a determination that the execution of the handover procedure has been successful, the instruction instructing the second device to apply a configuration related to the target cell and to resume the data and / or signaling transmission / reception with the target cell via the first device.

5. The step of transmitting at least one instruction comprises: determining that the handover procedure has failed; 4. The first device according to claim 1, further comprising: a step of: transmitting an instruction to the second device to resume with the source cell configuration according to a determination that the first device will be reconnected with the source cell after the handover procedure has failed, the instruction instructing the second device to apply a configuration related to the source cell and to resume the data and / or signaling transmission and reception with the source cell via the first device.

6. The step of transmitting at least one instruction comprises: determining that the handover procedure has failed; performing a re-establishment procedure with a cell other than the source cell and the target cell according to a determination that the handover procedure has failed; 4. The first device according to claim 1, further comprising: a step of transmitting a re-establishment instruction to the second device according to a determination that the re-establishment procedure has been successfully performed, the re-establishment instruction instructing the second device to discard at least one candidate cell configuration and initiating a re-establishment procedure with the cell via the first device.

7. 10. The first device of claim 1, wherein the first device comprises a relay terminal device, the second device comprises a remote terminal device, and the third device comprises a network device.

8. at least one processor; and at least one memory storing instructions that, when executed by the at least one processor, cause the second device to: receiving a second message from a third device via a first device, the second message comprising at least one candidate cell configuration and a set of conditions related to the first device, the first device acting as a UE-to-network relay for the second device to communicate with the third device; and receiving from said first device at least one instruction corresponding to at least one of said set of conditions.

9. 10. The second device of claim 8, wherein the second message comprises a radio resource control reconfiguration message and further comprises a measurement configuration related to an interface between the second device and the third device.

10. The set of conditions is: a first condition related to suspending data transmission to the third device via the first device; a second condition related to restarting in one of the at least one candidate cell configuration; and a third condition related to restarting in the source cell configuration; and and a fourth condition related to abandoning the at least one candidate cell configuration and initiating a re-establishment procedure.

11. The second device determining that the first condition is satisfied in response to receiving the second message; and ceasing the uplink transmission to the third device via the first device in accordance with the determination that the first condition is satisfied.

12. The step of receiving at least one instruction comprises:

11. The second device of claim 10, further comprising receiving an indication from the first device that a handover procedure is to be initiated at the first device, the indication corresponding to the first condition.

13. The second device determining that the first condition is satisfied in response to receiving the indication corresponding to the first condition; and ceasing the uplink transmission to the third device via the first device in accordance with the determination that the first condition is satisfied.

14. The second device 14. The second device of claim 8 or claim 13, further performing the step of receiving from the first device at least one downlink data transmission transmitted by the third device.

15. The step of receiving at least one instruction comprises: The second device according to any one of claims 8 to 13, characterized in that it comprises a step of receiving from the first device an instruction to resume in a target cell configuration, the at least one candidate cell comprising the target cell, and the instruction corresponding to the second condition.

16. The second device determining, in response to receiving the indication, that the second condition is satisfied; determining the target cell configuration from the at least one candidate cell configuration according to a determination that the second condition is satisfied; 16. The second device of claim 15, further comprising the steps of: applying the target cell configuration and resuming data and / or signaling transmission and reception.

17. The step of receiving at least one instruction comprises: A second device according to any one of claims 8 to 13, characterized in that it includes a step of receiving from the first device an instruction to resume in a source cell configuration, the instruction corresponding to the third condition.

18. The second device determining, in response to receiving the indication, that the third condition is satisfied; discarding the at least one candidate cell configuration in accordance with a determination that the third condition is satisfied; and 20. The second device of claim 17, further performing the steps of: applying the source cell configuration; and resuming data and / or signaling transmission and reception.

19. The step of receiving at least one instruction comprises: The second device according to any one of claims 8 to 13, further comprising the step of receiving, from the first device, a re-establishment instruction corresponding to the fourth condition.

20. The second device discarding the at least one candidate cell configuration in accordance with a determination that the fourth condition is satisfied; and 20. The second device of claim 19, further comprising: a step of: initiating a re-establishment procedure.

21. 10. The second device of claim 8, wherein the first device comprises a relay terminal device, the second device comprises a remote terminal device, and the third device comprises a network device.

22. at least one processor; and at least one memory storing instructions that, when executed by the at least one processor, cause the third device to: generating a second message according to a determination that a handover related to a first device and a second device should be performed, the second message comprising at least one candidate cell configuration and a set of conditions related to the first device, the first device acting as a UE-to-network relay for the second device to communicate with the third device, each of the sets of conditions corresponding to at least one instruction to be sent from the first device to the second device; sending the second message to the second device via the first device; and a step of causing the first device to perform at least the steps of: transmitting a first message to initiate the handover;

23. 23. The third device of claim 22, wherein the second message comprises a radio resource control reconfiguration message and further comprises a measurement configuration related to an interface between the second device and the third device.

24. The set of conditions is: a first condition related to suspending data transmission to the third device via the second device; a second condition related to restarting in one of the at least one candidate cell configuration; and a third condition related to restarting in the source cell configuration; and and a fourth condition related to abandoning the at least one candidate cell configuration and initiating a re-establishment procedure.

25. 23. The third device of claim 22, wherein the first device comprises a relay terminal device, the second device comprises a remote terminal device, and the third device comprises a network device.

26. In response to receiving a first message from a third device to initiate a handover involving a first device and a second device, performing, at the first device, a handover procedure to a target cell indicated in the first message, wherein the first device acts as a UE-to-network relay for the second device to communicate with the third device; and sending at least one indication to the second device based on the handover procedure.

27. receiving a second message from a third device via a first device, the second message comprising at least one candidate cell configuration and a set of conditions related to the first device, the first device acting as a UE-to-network relay for the second device to communicate with the third device; receiving from the first device at least one indication corresponding to at least one of the set of conditions.

28. generating, at a third device according to a determination that a handover related to a first device and a second device should be performed, a second message comprising at least one candidate cell configuration and a set of conditions related to the first device, wherein the first device acts as a UE-to-network relay for the second device to communicate with the third device, and each of the sets of conditions corresponds to at least one instruction to be sent from the first device to the second device; sending the second message to the second device via the first device; sending a first message to the first device to initiate the handover.

29. When executed by an apparatus, the apparatus at least: In response to receiving a first message from a third device to initiate a handover involving a first device and a second device, performing, at the first device, a handover procedure to a target cell indicated in the first message, wherein the first device acts as a UE-to-network relay for the second device to communicate with the third device; and transmitting to the second device at least one indication based on the handover procedure.

30. When executed by an apparatus, the apparatus at least: receiving a second message from a third device via a first device, the second message comprising at least one candidate cell configuration and a set of conditions related to the first device, the first device acting as a UE-to-network relay for the second device to communicate with the third device; and receiving from the first device at least one instruction corresponding to at least one of the set of conditions.

31. When executed by an apparatus, the apparatus at least: generating, at a third device according to a determination that a handover related to a first device and a second device should be performed, a second message comprising at least one candidate cell configuration and a set of conditions related to the first device, wherein the first device acts as a UE-to-network relay for the second device to communicate with the third device, and each of the sets of conditions corresponds to at least one instruction to be sent from the first device to the second device; sending the second message to the second device via the first device; and transmitting to the first device a first message to initiate the handover.

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