Handover procedure in wireless communications

Abstract

Apparatus, systems, and methods for handover procedures in wireless communications. A target network device is configured to: transmit to the target network device a handover request requesting a handover of a remote wireless device served by a source network device or a source relay wireless device served by the source network device, the handover request comprising identification information of one or more candidate relay wireless devices served by the target network device; and receiving a handover response from the target network device; and in response to the handover response including a container, transmitting a handover command including the container to the remote wireless device, the container including identification information of a target relay wireless device selected by the target network device from the one or more candidate relay wireless devices or cell identification information of the target network device.

Description

Technical Field

[0001] The present application generally relates to wireless communications, including apparatus, systems, and methods for handover procedures in wireless communications. Background Art

[0002] Wireless mobile communication technologies use various standards and protocols to send data between base stations and wireless communication devices. Wireless communication system standards and protocols may include, for example, the 3rd Generation Partnership Project (3GPP) Long Term Evolution (LTE) (e.g., 4G), 3GPP New Radio (NR) (e.g., 5G), and the IEEE 802.11 standard for wireless local area networks (WLANs) (commonly referred to within industry organizations as WLANs). ).

[0003] As envisioned by 3GPP, different wireless communication system standards and protocols may use various radio access networks (RANs) to communicate between base stations of the RAN (which may also sometimes be referred to as RAN nodes, network nodes, or simply nodes) and wireless communication devices referred to as user equipment (UE). 3GPP RANs may include, for example, Global System for Mobile Communications (GSM), Enhanced Data Rates for GSM Evolution (EDGE) RAN (GERAN), Universal Terrestrial Radio Access Network (UTRAN), Evolved Universal Terrestrial Radio Access Network (E-UTRAN), and / or Next Generation Radio Access Network (NG-RAN).

[0004] Each RAN may use one or more radio access technologies (RATs) to perform communications between base stations and UEs. For example, GERAN implements GSM and / or EDGE RAT, UTRAN implements Universal Mobile Telecommunications System (UMTS) RAT or other 3GPP RAT, E-UTRAN implements LTE RAT (sometimes referred to as LTE), and NG-RAN implements NR RAT (sometimes referred to herein as 5G RAT, 5G NR RAT, or NR). In some deployments, E-UTRAN may also implement NR RAT. In some deployments, NG-RAN may also implement LTE RAT.

[0005] The base stations used by the RAN may correspond to the RAN. An example of an E-UTRAN base station is an Evolved Universal Terrestrial Radio Access Network (E-UTRAN) Node B (also often denoted as an evolved Node B, enhanced Node B, eNodeB, or eNB). An example of an NG-RAN base station is a Next Generation Node B (also sometimes referred to as a gNodeB or gNB).

[0006] The RAN provides its communication services with external entities through its connection to the Core Network (CN). For example, E-UTRAN may utilize the Evolved Packet Core (EPC) while NG-RAN may utilize the 5G Core Network (5GC). Summary of the invention

[0007] The present disclosure provides an apparatus, system, and method for a handover process in wireless communications.

[0008] Embodiments disclosed herein include a source network device, the source network device including: at least one antenna; and a processor, the processor being configured to: send a handover request to a target network device requesting handover of a remote wireless device served by the source network device or a source relay wireless device served by the source network device, the handover request including identification information of one or more candidate relay wireless devices served by the target network device; and receive a handover response from the target network device; and in response to the handover response including a container, send a handover command including a container to the remote wireless device, the container including identification information of a target relay wireless device selected by the target network device from one or more candidate relay wireless devices for serving the remote wireless device or cell identification information of the target network device for serving the remote wireless device.

[0009] The embodiments disclosed herein include a target network device, the target network device including: at least one antenna; and a processor, the processor being configured to: receive a handover request from a source network device requesting handover of a remote wireless device served by the source network device or a source relay wireless device served by the source network device, the handover request including identification information of one or more candidate relay wireless devices served by the target network device; select a target relay wireless device or the target network device itself from the one or more candidate relay wireless devices to serve the remote wireless device; and send a handover response to the source network device, wherein if the target relay wireless device or the target network device itself is selected as serving the remote wireless device, the handover response includes a container, the container including identification information of the target relay wireless device serving the remote wireless device or cell identification information of the target network device serving the remote wireless device.

[0010] The embodiments disclosed herein include a method performed by a source network device, the method including: sending a handover request to a target network device requesting handover of a remote wireless device served by the source network device or a source relay wireless device served by the source network device, the handover request including identification information of one or more candidate relay wireless devices served by the target network device; and receiving a handover response from the target network device; and in response to the handover response including a container, sending a handover command including a container to the remote wireless device, the container including identification information of a target relay wireless device selected by the target network device from one or more candidate relay wireless devices for serving the remote wireless device or cell identification information of a target network device for serving the remote wireless device.

[0011] The embodiments disclosed herein include a method performed by a target network device, the method comprising: receiving a handover request from a source network device requesting handover of a remote wireless device served by the source network device or a source relay wireless device served by the source network device, the handover request including identification information of one or more candidate relay wireless devices served by the target network device; selecting a target relay wireless device or the target network device itself from the one or more candidate relay wireless devices to serve the remote wireless device; and sending a handover response to the source network device, wherein if the target relay wireless device or the target network device itself is selected as the serving remote wireless device, the handover response includes a container including identification information of the target relay wireless device serving the remote wireless device or cell identification information of the target network device serving the remote wireless device.

[0012] Embodiments disclosed herein include a non-transitory computer-readable storage medium having instructions stored thereon, which, when executed by a processor of a source network device, cause the processor to: send a handover request to a target network device requesting handover of a remote wireless device served by the source network device or a source relay wireless device served by the source network device, the handover request including identification information of one or more candidate relay wireless devices served by the target network device; and receive a handover response from the target network device; and in response to the handover response including a container, send a handover command including a container to the remote wireless device, the container including identification information of a target relay wireless device selected by the target network device from the one or more candidate relay wireless devices for serving the remote wireless device or cell identification information of the target network device for serving the remote wireless device.

[0013] Embodiments disclosed herein include a non-transitory computer-readable storage medium having instructions stored thereon, which, when executed by a processor of a target network device, cause the processor to: receive a handover request from a source network device requesting handover of a remote wireless device served by the source network device or a source relay wireless device served by the source network device, the handover request including identification information of one or more candidate relay wireless devices served by the target network device; select a target relay wireless device or the target network device itself from the one or more candidate relay wireless devices to serve the remote wireless device; and send a handover response to the source network device, wherein if the target relay wireless device or the target network device itself is selected as the serving remote wireless device, the handover response includes a container including identification information of the target relay wireless device serving the remote wireless device or cell identification information of the target network device serving the remote wireless device.

[0014] Embodiments disclosed herein include a computer program product including computer program instructions stored thereon, which, when executed by a processor of a source wireless device, cause the processor to: send a handover request to a target network device requesting handover of a remote wireless device served by the source network device or a source relay wireless device served by the source network device, the handover request including identification information of one or more candidate relay wireless devices served by the target network device; and receive a handover response from the target network device; and in response to the handover response including a container, send a handover command including a container to the remote wireless device, the container including identification information of a target relay wireless device selected by the target network device from one or more candidate relay wireless devices for serving the remote wireless device or cell identification information of a target network device for serving the remote wireless device.

[0015] Embodiments disclosed herein include a computer program product including computer program instructions stored thereon, which, when executed by a processor of a target wireless device, cause the processor to: receive a handover request from a source network device requesting handover of a remote wireless device served by the source network device or a source relay wireless device served by the source network device, the handover request including identification information of one or more candidate relay wireless devices served by the target network device; select a target relay wireless device or the target network device itself from the one or more candidate relay wireless devices to serve the remote wireless device; and send a handover response to the source network device, wherein if the target relay wireless device or the target network device itself is selected as the serving remote wireless device, the handover response includes a container including identification information of the target relay wireless device serving the remote wireless device or cell identification information of the target network device serving the remote wireless device. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] To easily identify the discussion of any particular element or action, the most significant digit(s) in a reference number refers to the drawing number that first introduces the element.

[0017] Figure 1 An example architecture of a wireless communication system according to embodiments disclosed herein is illustrated.

[0018] Figure 2 A system for performing signaling between a wireless device and a network device according to embodiments disclosed herein is illustrated.

[0019] FIG. 3A to FIG. 3C An example scenario of inter-gNB handover according to the embodiments disclosed herein is illustrated.

[0020] Figure 4 An example relay discovery of a remote UE to a relay UE in a neighboring cell according to embodiments disclosed herein is illustrated.

[0021] Figure 5 An example communication process for inter-gNB handover according to the embodiments disclosed herein is illustrated.

[0022] Figure 6 An example communication process for conditional inter-gNB switching according to the embodiments disclosed herein is illustrated.

[0023] Figure 7 An example method performed by a source network device according to embodiments disclosed herein is illustrated.

[0024] Figure 8 An example method performed by a target network device according to embodiments disclosed herein is illustrated. DETAILED DESCRIPTION

[0025] Various embodiments are described with respect to UE. However, reference to UE is provided for illustrative purposes only. The example embodiments may be used with any wireless device that can establish a connection with a network and is configured with hardware, software and / or firmware for exchanging information and data with the network. Therefore, UE described herein is used to represent any suitable wireless device.

[0026] Various embodiments are described with respect to gNBs. However, references to gNBs are provided for illustrative purposes only. The example embodiments may be used with any network device in a network and configured with hardware, software, and / or firmware to implement any functionality of the network. Thus, gNBs described herein are used to represent any suitable network device.

[0027] Figure 1An example architecture of a wireless communication system 100 is illustrated in accordance with an embodiment disclosed herein. The description provided below is for an example wireless communication system 100 operating in conjunction with the LTE system standard and / or the 5G or NR system standard provided in the 3GPP technical specifications.

[0028] like Figure 1 As shown, wireless communication system 100 includes UE 102 and UE 104 (although any number of UEs may be used). In this example, UE 102 and UE 104 are illustrated as smartphones (e.g., handheld touch screen mobile computing devices capable of connecting to one or more cellular networks), but may also include any mobile or non-mobile computing device configured for wireless communication.

[0029] UE 102 and UE 104 may be configured to be communicatively coupled to RAN 106. In an embodiment, RAN 106 may be NG-RAN, E-UTRAN, etc. UE 102 and UE 104 utilize connections (or channels) (shown as connection 108 and connection 110, respectively) with RAN 106, where each connection (or channel) includes a physical communication interface. RAN 106 may include one or more base stations, such as base station 112 and base station 114, to implement connection 108 and connection 110.

[0030] In this example, connection 108 and connection 110 are air interfaces that enable such communicative coupling and may conform to the RAT used by RAN 106 , such as, for example, LTE and / or NR.

[0031] In some embodiments, UE 102 and UE 104 may also directly exchange communication data via side link interface 116. UE 104 is shown as being configured to access an access point (shown as AP 118) via connection 120. By way of example, connection 120 may include a local wireless connection, such as a connection conforming to any IEEE 802.11 protocol, wherein AP 118 may include In this example, AP 118 may be connected to another network (eg, the Internet) without going through CN 124.

[0032] In an embodiment, UE 102 and UE 104 may be configured to communicate with each other or with base station 112 and / or base station 114 over a multi-carrier communication channel using orthogonal frequency division multiplexing (OFDM) communication signals according to various communication techniques, such as but not limited to orthogonal frequency division multiple access (OFDMA) communication techniques (e.g., for downlink communication) or single carrier frequency division multiple access (SC-FDMA) communication techniques (e.g., for uplink and ProSe or sidelink communication), although the scope of the embodiment is not limited in this respect. The OFDM signal may include multiple orthogonal subcarriers.

[0033] In some embodiments, all or part of base station 112 or base station 114 may be implemented as one or more software entities running on a server computer as part of a virtual network. In addition, or in other embodiments, base station 112 or base station 114 may be configured to communicate with each other via interface 122. In an embodiment where wireless communication system 100 is an LTE system (e.g., when CN124 is EPC), interface 122 may be an X2 interface. The X2 interface may be defined between two or more base stations (e.g., two or more eNBs, etc.) connected to EPC and / or between two eNBs connected to EPC. In an embodiment where wireless communication system 100 is an NR system (e.g., when CN 124 is 5GC), interface 122 may be an Xn interface. The Xn interface is defined between two or more base stations (e.g., two or more gNBs, etc.) connected to 5GC, between base station 112 (e.g., gNB) and eNB connected to 5GC, and / or between two eNBs connected to 5GC (e.g., CN 124).

[0034] The RAN 106 is shown as being communicatively coupled to the CN 124. The CN 124 may include one or more network elements 126 configured to provide various data and telecommunication services to customers / subscribers (e.g., UE 102 and users of UE 104) connected to the CN 124 via the RAN 106. The components of the CN 124 may be implemented in one physical device or separate physical devices including components for reading and executing instructions from a machine-readable or computer-readable medium (e.g., a non-transitory machine-readable storage medium).

[0035] In an embodiment, CN 124 may be an EPC, and RAN 106 may be connected to CN 124 via an S1 interface 128. In an embodiment, S1 interface 128 may be divided into two parts: an S1 user plane (S1-U) interface, which carries traffic data between base station 112 or base station 114 and a serving gateway (S-GW); and an S1-MME interface, which is a signaling interface between base station 112 or base station 114 and a mobility management entity (MME).

[0036] In an embodiment, CN 124 may be a 5GC, and RAN 106 may be connected to CN 124 via an NG interface 128. In an embodiment, NG interface 128 may be divided into two parts: an NG user plane (NG-U) interface that carries service data between base station 112 or base station 114 and a user plane function (UPF); and an S1 control plane (NG-C) interface that is a signaling interface between base station 112 or base station 114 and an access and mobility management function (AMF).

[0037] Generally speaking, application server 130 may be an element that provides applications (e.g., packet-switched data services) that use Internet Protocol (IP) bearer resources with CN 124. Application server 130 may also be configured to support one or more communication services (e.g., VoIP sessions, group communication sessions, etc.) for UE 102 and UE 104 via CN 124. Application server 130 may communicate with CN 124 via IP communication interface 132.

[0038] Figure 2 A system 200 for performing signaling 234 between a wireless device 202 and a network device 218 according to an embodiment disclosed herein is illustrated. The system 200 may be part of a wireless communication system as described herein. The wireless device 202 may be, for example, a UE of a wireless communication system. The network device 218 may be, for example, a base station (e.g., an eNB or a gNB) of a wireless communication system.

[0039] The wireless device 202 may include one or more processors 204. The processor 204 may execute instructions to perform various operations of the wireless device 202, as described herein. The processor 204 may include one or more baseband processors implemented using, for example, a central processing unit (CPU), a digital signal processor (DSP), an application specific integrated circuit (ASIC), a controller, a field programmable gate array (FPGA) device, another hardware device, a firmware device, or any combination thereof configured to perform the operations described herein.

[0040] The wireless device 202 may include a memory 206. The memory 206 may be a non-transitory computer-readable storage medium that stores instructions 208 (which may include, for example, instructions executed by the processor 204). The instructions 208 may also be referred to as program code or a computer program. The memory 206 may also store data used by the processor 204 and results calculated by the processor.

[0041] The wireless device 202 may include one or more transceivers 210 that may use radio frequency (RF) transmitter and / or receiver circuitry that uses an antenna 212 of the wireless device 202 to facilitate signaling (e.g., signaling 234) to and / or from the wireless device 202 with other devices (e.g., network device 218) according to a corresponding RAT.

[0042] The wireless device 202 may include one or more antennas 212 (e.g., one, two, four, or more). For embodiments with multiple antennas 212, the wireless device 202 may utilize the spatial diversity of such multiple antennas 212 to transmit and / or receive multiple different data streams on the same time-frequency resource. This behavior may be referred to as, for example, multiple-input multiple-output (MIMO) behavior (referring to the multiple antennas used at each of the transmitting device and the receiving device to implement this aspect). MIMO transmission by the wireless device 202 may be implemented based on precoding (or digital beamforming) applied at the wireless device 202, which multiplexes the data streams across the antennas 212 based on known or assumed channel characteristics, so that each data stream is received at an appropriate signal strength relative to the other streams and at a desired location in the spatial domain (e.g., the location of the receiver associated with the data stream). Certain embodiments may use a single-user MIMO (SU-MIMO) approach (where the data streams are all directed to a single receiver) and / or a multi-user MIMO (MU-MIMO) approach (where separate data streams may be directed to separate (different) receivers in different locations in the spatial domain).

[0043] In certain embodiments with multiple antennas, the wireless device 202 may implement analog beamforming techniques whereby the phases of signals transmitted by the antennas 212 are relatively adjusted so that the (joint) transmissions of the antennas 212 can be directed (this is sometimes referred to as beam steering).

[0044] The wireless device 202 may include one or more interfaces 214. The interfaces 214 may be used to provide input to the wireless device 202 or output from the wireless device. For example, a wireless device 202 that is a UE may include an interface 214, such as a microphone, a speaker, a touch screen, buttons, etc., to allow a user of the UE to input and / or output to the UE. Other interfaces of such a UE may be composed of transmitters, receivers, and other circuits that allow communication between the UE and other devices (e.g., in addition to the transceiver 210 / antenna 212 described above), and may be based on known protocols (e.g., etc.) to perform the operation.

[0045] The network device 218 may include one or more processors 220. The processor 220 may execute instructions to perform various operations of the network device 218, as described herein. The processor 204 may include one or more baseband processors implemented using, for example, a CPU, a DSP, an ASIC, a controller, an FPGA device, another hardware device, a firmware device, or any combination thereof configured to perform the operations described herein.

[0046] The network device 218 may include a memory 222. The memory 222 may be a non-transitory computer-readable storage medium that stores instructions 224 (which may include, for example, instructions executed by the processor 220). The instructions 224 may also be referred to as program code or a computer program. The memory 222 may also store data used by the processor 220 and results calculated by the processor.

[0047] The network device 218 may include one or more transceivers 226, which may include RF transmitter and / or receiver circuits that use an antenna 228 of the network device 218 to facilitate signaling (e.g., signaling 234) to and / or from the network device 218 with other devices (e.g., wireless device 202) according to a corresponding RAT.

[0048] The network device 218 may include one or more antennas 228 (eg, one, two, four, or more). In embodiments with multiple antennas 228, the network device 218 may perform MIMO, digital beamforming, analog beamforming, beamsteering, etc. as described.

[0049] The network device 218 may include one or more interfaces 230. The interface 230 may be used to provide input to or output from the network device 218. For example, the network device 218 as a base station may include an interface 230 composed of a transmitter, a receiver, and other circuits (e.g., in addition to the transceiver 226 / antenna 228 described above), which enables the base station to communicate with other equipment in the core network and / or enables the base station to communicate with external networks, computers, databases, etc., in order to achieve the purpose of performing operations, management, and maintenance of the base station or other equipment operably connected to the base station.

[0050] In a UE-to-network relay system, a relay UE relays traffic between a remote UE and the network. UE-to-network relay enables extended coverage and power savings for remote UEs. A group of remote UEs may rely on a single relay UE to communicate with the network.

[0051] FIG. 3A to FIG. 3CExample scenarios for inter-gNB handover according to the embodiments disclosed herein are illustrated. For a direct path, the remote UE will connect directly to the network. For an indirect path, the remote UE will connect to the network via a relay UE. Figure 3A The scenario of indirect to direct path handover between gNBs (i.e. “remote UE <-> relay UE A <-> gNB X” to “remote UE <-> gNB Y”) is illustrated. Figure 3B The scenario of direct to indirect path switching between gNBs (i.e., “remote UE <-> gNB X” to “remote UE <-> relay UE A <-> gNB Y”) is illustrated. Figure 3C The scenario of indirect to indirect path switching between gNBs (i.e., "remote UE <-> relay UE A <-> gNB X" to "remote UE <-> relay UE B <-> gNB Y") is illustrated.

[0052] The target relay UE can be in RRC connected state or RRC idle / inactive state. For target relay UE in RRC connected state and RRC idle / inactive state, the remote UE will use two different connection establishment procedures. The handover command of the gNB will inform the remote UE which connection establishment procedure to use. That is, if the target relay UE is in RRC connected state (i.e., gNB controlled), the gNB will provide a dedicated RLC channel configuration for transmitting the RRCReconfigurationComplete message. Otherwise, the UE must use the default RLC channel configuration.

[0053] For indirect path to indirect path under the same gNB, the gNB knows whether the candidate relay UE is in RRC connected state. It is up to the gNB implementation to decide which relay UE to select. However, for direct path to indirect path under different gNBs or indirect path to indirect path under different gNBs, the source gNB does not know the RRC state of the candidate relay UE. Therefore, an additional query process may be required for the RRC state of the candidate relay UE. In addition, the source gNB does not know the Uu quality of the candidate relay UE (towards the target gNB). Therefore, an additional query process may be required for the Uu quality of the candidate relay UE (towards the target gNB).

[0054] The embodiment contemplated herein lets the target gNB determine whether it or its relay UE serves the remote UE. The target gNB knows the RRC state of the candidate relay UE and the Uu quality (RSRP / RSRQ / SINR) of the candidate relay UE. As a result, the target gNB is able to better determine the target relay UE to avoid additional inter-gNB exchanges on the RRC state and / or Uu quality of the candidate relay UE.

[0055] In some embodiments of the present disclosure, the source gNB may select a target gNB but may not determine whether the target gNB or its relay UEs will serve the remote UE. The source gNB forwards the following information to its selected target gNB via a handover request message: the remote UE's Uu measurements for the target gNB, the remote UE's SD-RSRP / SL-RSRP for the candidate relay UEs served by the target gNB, and the Lay 2 identifier (L2 ID) of the candidate relay UEs served by the target gNB.

[0056] The target gNB may prepare the configuration in the target cell and transparently forward the information of the serving node (target gNB or target relay UE) and the prepared configuration to the source gNB via the handover response. Therefore, the RRC state of the target relay UE may be transparent to the source gNB.

[0057] Figure 4 An example relay discovery of a relay UE in a neighboring cell by a remote UE according to embodiments disclosed herein is illustrated. A remote UE in a cell of gNB X discovers a relay UE in a cell of gNB Y and wants to switch its path to the relay UE. Although the remote UE is shown as being directly connected to gNB X, it may also be indirectly connected to gNB X via the relay UE.

[0058] Figure 5 An example communication process for inter-gNB handover according to the embodiments disclosed herein is illustrated.

[0059] First, the candidate relay UE sends a discovery notification for relay discovery. For example, the relay UE selected as the target relay UE sends a discovery notification for relay discovery in step S502. Although not shown, there are other candidate relay UEs that send discovery notifications. Each discovery notification in the discovery notification may include identification information of the corresponding relay UE (e.g., L2 ID of the relay UE), cell identification information (e.g., serving cell ID), relay service code, and PLMN ID.

[0060] In step S504, after receiving the discovery notification, the remote UE sends a measurement report to the source gNB serving the remote UE. The measurement report may include identification information of the candidate relay UE, cell identification information, and the remote UE's measurement results of the candidate relay UE (e.g., the measured SD-RSRP / SL-RSRP and / or sidelink beam information of the relay UE). In addition, the measurement report may include the remote UE's measurement results of the candidate gNB indicated by the cell identification information. The candidate relay UE may be served by multiple candidate gNBs, and the multiple candidate gNBs may be indicated by the cell identification information associated with the identification information of the candidate relay UE.

[0061] In step S506, the source gNB determines the target gNB based on the measurement report received from the remote UE. In some embodiments of the present disclosure, the source gNB determines all candidate gNBs indicated by the measurement report as target gNBs. In some embodiments of the present disclosure, the source gNB selects the target gNB from multiple candidate gNBs indicated by the measurement report. The selection of the target gNB may be based on the measurement results of the remote UE on the candidate gNB and / or the measurement results of the remote UE on the candidate relay UE. For example, the selection of the target gNB may be based on one of the following: the average value of the Uu RSRP of the candidate gNB and the SD-RSRP / SL-RSRP of all its candidate relay UEs, the average value of the Uu RSRP of the candidate gNB and max (SD-RSRP / SL-RSRP of all its candidate relay UEs), max [Uu RSRP of the candidate gNB, max (SD-RSRP / SL-RSRP of all its candidate relay UEs)], or min [Uu RSRP of the candidate gNB, max (SD-RSRP / SL-RSRP of all its candidate relay UEs)].

[0062] In step S508, the source gNB sends a handover request to the target gNB. The handover request may include identification information of the candidate relay UE served by the target gNB. The handover request may also include cell identification information of the target gNB, measurement results of the remote UE on the candidate relay UE, and / or measurement results of the remote UE on the target gNB.

[0063] In step S510, the target gNB selects a target relay UE or itself from the candidate relay UEs to serve the remote UE after receiving the handover request from the source gNB. The selection may be based on the RRC state of the candidate relay UE. A relay UE in an RRC connected state may be selected. In addition, the measurement results of the remote UE on the candidate relay UE may also be considered. For example, a relay UE with high SD-RSRP / SL-RSRP and / or with a measured side link beam similar to its Uu beam may be selected. In some embodiments of the present disclosure, if the measurement results of the remote UE on the target gNB are good enough, the target gNB may decide to serve the remote UE itself.

[0064] If the selected target relay UE is in an RRC connected state, then in step S512, the target gNB sends an RRC reconfiguration message to the selected target relay UE to reconfigure the dedicated bearer mapping (i.e., Sidelink Relay Adaptation Protocol (SRAP) bearer mapping) for the target relay UE.

[0065] In step S514, the target gNB sends a handover response to the source gNB. If the target relay UE or the target gNB itself is selected to serve the remote UE, the handover response may include a container. The container may include identification information of the target UE serving the remote UE or cell identification information of the target gNB serving the remote UE. If the target relay UE is selected to serve the remote UE, the container may include identification information of the target relay UE. If the target gNB decides to serve the remote UE itself, the container may include cell identification information of the target gNB. If any of the candidate relay UEs is not found (for example, if the relay UE has been reselected to another gNB or its L2 ID has changed), the handover response may include a failure cause value indicating that the candidate relay UE was not found.

[0066] The handover response may be a path switch command prepared by the target gNB according to the RRC state of the target relay UE. For example, if the selected target relay UE is in the RRC connected state, the container in the handover response may include the configuration of the Sidelink Relay Adaptation Protocol (SRAP) bearer mapping. Otherwise, if the selected target relay UE is in the RRC idle / inactive state, the container in the handover response does not include such configuration of the SRAP bearer mapping.

[0067] The target gNB may also assign identification information to the remote UE and include the assigned identification information in the container. The identification information assigned to the remote wireless device may be used at least in the Sidelink Relay Adaptation Protocol (SRAP) header. The assigned identification information may be a local ID of the remote UE, which is used in the SRAP header to ensure security. If the real remote UE ID is included in the SRAP header, some security issues may result because the adaptation layer has no security protection.

[0068] The container in the Handover Response may be transparent to the source gNB. That is, the source gNB may transmit the container to the remote UE without interpreting it. Therefore, the source gNB does not need to know the RRC state of the target relay UE.

[0069] In step S516, in response to the handover response including the container, the source gNB sends a handover command including the container to the remote UE to instruct the remote UE to perform the handover. The handover command may include the container in the handover response and may be sent in the form of an RRC reconfiguration message with a ReconfigWithSync field. Upon receiving the handover command, the remote UE may determine the RRC state of the target relay UE based on the container in the handover command (i.e., whether there is a dedicated SRAP bearer mapping configuration) and perform path switch execution accordingly.

[0070] A similar communication process may be applied to conditional handover of a remote UE. Figure 6 An example communication process for conditional inter-gNB switching according to the embodiments disclosed herein is illustrated. Figure 6 The conditional switching process is Figure 5 The handover process of is different in that the source gNB selects two candidate gNBs (C-gNB1 and C-gNB 2) as target gNBs. Therefore, the source gNB sends a handover request not only to C-gNB1 but also to C-gNB2. In addition, C-gNB1 and C-gNB2 will each select a target relay UE and send a handover response to the source gNB.

[0071] First, the candidate relay UE sends a discovery notification for relay discovery. For example, the relay UE of C-gNB1 selected as the target relay UE sends a discovery notification for relay discovery in step S602a, and the relay UE of C-gNB2 selected as the target relay UE sends a discovery notification for relay discovery in step S602b. Although not shown, there are other candidate relay UEs that send discovery notifications. In step S604, after receiving the discovery notification, the remote UE sends a measurement report to the source gNB serving the remote UE. In step S606, the source gNB determines the target gNB based on the measurement report received from the remote UE. Figure 6 As shown, two candidate gNBs (C-gNB1 and C-gNB 2) are selected by the source gNB as target gNBs. However, in some embodiments of the present disclosure, the source gNB may select more candidate gNBs as target gNBs.

[0072] In step S608a, the source gNB sends a handover request to C-gNB1. In step S608a, the source gNB sends a handover request to C-gNB2.

[0073] In step S610a, C-gNB1, after receiving the handover request from the source gNB, selects a target relay UE or itself from its candidate relay UEs to serve the remote UE. If the selected target relay UE is in the RRC connected state, in step S612a, C-gNB1 sends an RRC reconfiguration message to the selected target relay UE to reconfigure the dedicated bearer mapping (i.e., Sidelink Relay Adaptation Protocol (SRAP) bearer mapping) for the target relay UE. In step S614a, C-gNB1 sends a handover response to the source gNB.

[0074] In step S610b, C-gNB2 selects a target relay UE or itself from its candidate relay UEs to serve the remote UE after receiving the handover request from the source gNB. If the selected target relay UE is in the RRC connected state, then in step S612b, C-gNB2 sends an RRC reconfiguration message to the selected target relay UE to reconfigure the dedicated bearer mapping (i.e., Sidelink Relay Adaptation Protocol (SRAP) bearer mapping) for the target relay UE. In step S614b, C-gNB2 sends a handover response to the source gNB.

[0075] In step S616, in response to the handover response from C-gNB1 and / or C-gNB2 including the container, the source gNB sends a handover command to the remote UE to instruct the remote UE to perform the handover. The handover command includes the container in the handover response from C-gNB1 and / or C-gNB2.

[0076] Figure 6 The communication process is similar to Figure 5 Therefore, the signaling exchanged between the UE and the gNB is not described in detail, as they can be Figure 5 The signaling in the communication process is the same.

[0077] Various embodiments are described with respect to a UE and a gNB. However, as previously indicated, a UE as described herein is used to represent any suitable wireless device, and a gNB as described herein is used to represent any suitable network device.

[0078] Figure 7 An example method performed by a source network device according to embodiments disclosed herein is illustrated.

[0079] In step S702, the source network device sends a handover request to the target network device requesting handover of a remote wireless device served by the source network device or a source relay wireless device served by the source network device. The handover request includes identification information of one or more candidate relay wireless devices served by the target network device.

[0080] In step S704 , the source network device receives a switching response from the target network device.

[0081] In step S706, in response to the handover response including the container, the source network device sends a handover command including the container to the remote wireless device, wherein the container includes identification information of a target relay wireless device selected by the target network device from one or more candidate relay wireless devices for serving the remote wireless device or cell identification information of the target network device for serving the remote wireless device.

[0082] Figure 8An example method performed by a target network device according to embodiments disclosed herein is illustrated.

[0083] In step S802 , the target network device receives a handover request from the source network device requesting handover of a remote wireless device served by the source network device or a source relay wireless device served by the source network device, the handover request including identification information of one or more candidate relay wireless devices served by the target network device.

[0084] In step S804, the target network device selects a target relay wireless device from one or more candidate relay wireless devices or target network devices to serve the remote wireless device.

[0085] In step S806, the target network device sends a switching response to the source network device, wherein if the target relay wireless device or the target network device itself is selected as the serving remote wireless device, the switching response includes a container, which includes identification information of the target relay wireless device serving the remote wireless device or cell identification information of the target network device serving the remote wireless device.

[0086] Embodiments contemplated herein include a source network device, the source network device comprising: at least one antenna; and a processor, the processor being configured to: send a handover request to a target network device requesting handover of a remote wireless device served by the source network device or a source relay wireless device served by the source network device, the handover request comprising identification information of one or more candidate relay wireless devices served by the target network device; and receive a handover response from the target network device; and in response to the handover response comprising a container, send a handover command including a container to the remote wireless device, the container including identification information of a target relay wireless device selected by the target network device from one or more candidate relay wireless devices for serving the remote wireless device or cell identification information of the target network device for serving the remote wireless device.

[0087] In some embodiments of the present disclosure, the processor is further configured to receive a measurement report from a remote wireless device, the measurement report including cell identification information of a target network device, identification information of one or more candidate relay wireless devices served by the target network device, and measurement results of the remote wireless device on the one or more candidate relay wireless devices.

[0088] In some embodiments of the present disclosure, the measurement report includes cell identification information of multiple network devices, identification information of multiple candidate relay wireless devices served by the multiple network devices, and measurement results of the remote wireless device on the multiple candidate relay wireless devices, and the processor is further configured to select a target network device from the multiple network devices based on the measurement report.

[0089] In some embodiments of the present disclosure, the measurement report also includes measurement results of the remote wireless device on the plurality of network devices.

[0090] In some embodiments of the present disclosure, the handover request also includes measurement results of the remote wireless device on one or more candidate relay wireless devices.

[0091] In some embodiments of the present disclosure, the handover request also includes a measurement result of the remote wireless device on the target network device.

[0092] In some embodiments of the present disclosure, the identification information of one or more candidate relay wireless devices includes at least a layer 2 identifier (L2 ID).

[0093] In some embodiments of the present disclosure, the container also includes a configuration of a Sidelink Relay Adaptation Protocol (SRAP) bearer mapping.

[0094] In some embodiments of the present disclosure, the handover response includes a failure cause value indicating that one or more candidate relay wireless devices were not found.

[0095] In some embodiments of the present disclosure, the container is transparent to the source network device.

[0096] In some embodiments of the present disclosure, the processor is further configured to: send another handover request to another target network device requesting handover of the remote wireless device, the handover request including identification information of one or more other candidate relay wireless devices served by the other target network device; and receive another handover response from the other target network device including another container, the other container including identification information of another target relay wireless device selected by the other target network device from one or more other candidate relay wireless devices for serving the remote wireless device or cell identification information of another target network device for serving the remote wireless device.

[0097] Embodiments contemplated herein include an apparatus including means for performing one or more elements of a method, the method comprising: sending a handover request to a target network device requesting handover of a remote wireless device served by a source network device or a source relay wireless device served by the source network device, the handover request including identification information of one or more candidate relay wireless devices served by the target network device; and receiving a handover response from the target network device; and in response to the handover response including a container, sending a handover command including a container to the remote wireless device, the container including identification information of a target relay wireless device selected by the target network device from one or more candidate relay wireless devices for serving the remote wireless device or cell identification information of a target network device for serving the remote wireless device. The apparatus may be, for example, an apparatus of a UE (such as wireless device 202 as a UE, as described herein).

[0098] Embodiments contemplated herein include one or more non-transitory computer-readable media including instructions to cause an electronic device to perform one or more elements of a method when the instructions are executed by one or more processors of the electronic device, the method comprising: sending a handover request to a target network device requesting a handover of a remote wireless device served by a source network device or a source relay wireless device served by the source network device, the handover request including identification information of one or more candidate relay wireless devices served by the target network device; and receiving a handover response from the target network device; and in response to the handover response including a container, sending a handover command including a container to the remote wireless device, the container including identification information of a target relay wireless device selected by the target network device from one or more candidate relay wireless devices for serving the remote wireless device or cell identification information of a target network device for serving the remote wireless device. The non-transitory computer-readable medium may be, for example, a memory of a UE (such as the memory 206 of the wireless device 202 as a UE, as described herein).

[0099] Embodiments contemplated herein include an apparatus including logic components, modules, or circuits for performing one or more elements of a method, the method comprising: sending a handover request to a target network device requesting handover of a remote wireless device served by a source network device or a source relay wireless device served by the source network device, the handover request including identification information of one or more candidate relay wireless devices served by the target network device; and receiving a handover response from the target network device; and in response to the handover response including a container, sending a handover command including a container to the remote wireless device, the container including identification information of a target relay wireless device selected by the target network device from one or more candidate relay wireless devices for serving the remote wireless device or cell identification information of a target network device for serving the remote wireless device. The apparatus may be, for example, an apparatus of a UE (such as wireless device 202 as a UE, as described herein).

[0100] Embodiments contemplated herein include an apparatus comprising: one or more processors and one or more computer-readable media comprising instructions that, when executed by the one or more processors, cause the one or more processors to perform one or more elements of a method comprising: sending a handover request to a target network device requesting a handover of a remote wireless device served by a source network device or a source relay wireless device served by the source network device, the handover request comprising identification information of one or more candidate relay wireless devices served by the target network device; and receiving a handover response from the target network device; and in response to the handover response comprising a container, sending a handover command comprising a container to the remote wireless device, the container comprising identification information of a target relay wireless device selected by the target network device from the one or more candidate relay wireless devices for serving the remote wireless device or cell identification information of a target network device for serving the remote wireless device. The apparatus may be, for example, an apparatus of a UE (such as wireless device 202 as a UE, as described herein).

[0101] Embodiments contemplated herein include signals as described in or relating to one or more elements of a method, the method comprising: sending a handover request to a target network device requesting handover of a remote wireless device served by a source network device or a source relay wireless device served by the source network device, the handover request including identification information of one or more candidate relay wireless devices served by the target network device; and receiving a handover response from the target network device; and in response to the handover response including a container, sending a handover command to the remote wireless device including a container, the container including identification information of a target relay wireless device selected by the target network device from the one or more candidate relay wireless devices for serving the remote wireless device or cell identification information of the target network device for serving the remote wireless device.

[0102] Embodiments contemplated herein include a computer program or computer program product containing instructions, wherein the program is executed by a processor to cause the processor to perform one or more elements of a method, the method comprising: sending a handover request to a target network device requesting a handover of a remote wireless device served by a source network device or a source relay wireless device served by the source network device, the handover request including identification information of one or more candidate relay wireless devices served by the target network device; and receiving a handover response from the target network device; and in response to the handover response including a container, sending a handover command including a container to the remote wireless device, the container including identification information of a target relay wireless device selected by the target network device from one or more candidate relay wireless devices for serving the remote wireless device or cell identification information of a target network device for serving the remote wireless device. These instructions may be located, for example, in a processor and / or on a memory of a UE (such as memory 206 of wireless device 202 as a UE, as described herein).

[0103] Embodiments contemplated herein include a target network device, the target network device including: at least one antenna; and a processor configured to: receive a handover request from a source network device requesting handover of a remote wireless device served by the source network device or a source relay wireless device served by the source network device, the handover request including identification information of one or more candidate relay wireless devices served by the target network device; select a target relay wireless device or a target network device from the one or more candidate relay wireless devices to serve the remote wireless device; and send a handover response to the source network device, wherein if the target relay wireless device or the target network device itself is selected to serve the remote wireless device, the handover response includes a container including identification information of the target relay wireless device serving the remote wireless device or cell identification information of the target network device serving the remote wireless device.

[0104] In some embodiments of the present disclosure, the target relay wireless device is selected based at least on a radio resource control (RRC) state of the target relay wireless device.

[0105] In some embodiments of the present disclosure, the handover request also includes a measurement result of the remote wireless device on the target network device, and the processor is configured to select a target relay wireless device or the target network device itself to serve the remote wireless device based at least on the measurement result of the remote wireless device on the target network device.

[0106] In some embodiments of the present disclosure, the handover request also includes measurement results of the remote wireless device on one or more candidate relay wireless devices, and the processor is configured to select a target relay wireless device or the target network device itself to serve the remote wireless device based at least on the measurement results of the remote wireless device on the one or more candidate relay wireless devices.

[0107] In some embodiments of the present disclosure, the processor is further configured to: if the target relay wireless device is in an RRC connected state, send an RRC reconfiguration message to the target relay wireless device to reconfigure a Sidelink Relay Adaptation Protocol (SRAP) bearer mapping for the target relay wireless device.

[0108] In some embodiments of the present disclosure, the container also includes a configuration of a Sidelink Relay Adaptation Protocol (SRAP) bearer mapping.

[0109] In some embodiments of the present disclosure, the processor is further configured to assign identification information to the remote wireless device, and wherein the container further includes the identification information of the remote wireless device.

[0110] In some embodiments of the present disclosure, identification information assigned to a remote wireless device is used at least in a Sidelink Relay Adaptation Protocol (SRAP) header.

[0111] In some embodiments of the present disclosure, if any of the one or more candidate relay wireless devices are not found, the handover response includes a failure cause value indicating that the one or more candidate relay wireless devices were not found.

[0112] In some embodiments of the present disclosure, the container is transparent to the source network device.

[0113] Embodiments contemplated herein include an apparatus including means for performing one or more elements of a method, the method including: receiving a handover request from a source network device requesting a handover of a remote wireless device served by the source network device or a source relay wireless device served by the source network device, the handover request including identification information of one or more candidate relay wireless devices served by a target network device; selecting a target relay wireless device or the target network device itself from the one or more candidate relay wireless devices to serve the remote wireless device; and sending a handover response to the source network device, wherein if the target relay wireless device or the target network device itself is selected as serving the remote wireless device, the handover response includes a container including identification information of the target relay wireless device serving the remote wireless device or cell identification information of the target network device serving the remote wireless device. The apparatus may be, for example, an apparatus of a base station (such as network device 218 as a base station, as described herein).

[0114] Embodiments contemplated herein include one or more non-transitory computer-readable media including instructions to cause an electronic device to perform one or more elements of a method when the instructions are executed by one or more processors of the electronic device, the method comprising: receiving a handover request from a source network device requesting a handover of a remote wireless device served by the source network device or a source relay wireless device served by the source network device, the handover request including identification information of one or more candidate relay wireless devices served by a target network device; selecting a target relay wireless device or the target network device itself from the one or more candidate relay wireless devices to serve the remote wireless device; and sending a handover response to the source network device, wherein if the target relay wireless device or the target network device itself is selected as serving the remote wireless device, the handover response includes a container including identification information of the target relay wireless device serving the remote wireless device or cell identification information of the target network device serving the remote wireless device. The non-transitory computer-readable medium may be, for example, a memory of a base station (such as the memory 222 of the network device 218 as a base station, as described herein).

[0115] Embodiments contemplated herein include an apparatus including logic components, modules, or circuits for performing one or more elements of a method, the method comprising: receiving a handover request from a source network device requesting a handover of a remote wireless device served by the source network device or a source relay wireless device served by the source network device, the handover request including identification information of one or more candidate relay wireless devices served by a target network device; selecting a target relay wireless device or the target network device itself from the one or more candidate relay wireless devices to serve the remote wireless device; and sending a handover response to the source network device, wherein if the target relay wireless device or the target network device itself is selected as the serving remote wireless device, the handover response includes a container including identification information of the target relay wireless device serving the remote wireless device or cell identification information of the target network device serving the remote wireless device. The apparatus may be, for example, an apparatus of a base station (such as the network device 218 as a base station, as described herein).

[0116] Embodiments contemplated herein include an apparatus comprising: one or more processors and one or more computer-readable media comprising instructions that, when executed by the one or more processors, cause the one or more processors to perform one or more elements of a method comprising: receiving a handover request from a source network device requesting a handover of a remote wireless device served by the source network device or a source relay wireless device served by the source network device, the handover request comprising identification information of one or more candidate relay wireless devices served by a target network device; selecting a target relay wireless device or the target network device itself from the one or more candidate relay wireless devices to serve the remote wireless device; and sending a handover response to the source network device, wherein if the target relay wireless device or the target network device itself is selected to serve the remote wireless device, the handover response comprises a container comprising identification information of the target relay wireless device serving the remote wireless device or cell identification information of the target network device serving the remote wireless device. The apparatus may be, for example, an apparatus of a base station (such as network device 218 as a base station, as described herein).

[0117] Embodiments contemplated herein include signals as described in or associated with one or more elements of a method, the method comprising: receiving a handover request from a source network device requesting handover of a remote wireless device served by the source network device or a source relay wireless device served by the source network device, the handover request including identification information of one or more candidate relay wireless devices served by a target network device; selecting a target relay wireless device or the target network device itself from the one or more candidate relay wireless devices to serve the remote wireless device; and sending a handover response to the source network device, wherein if the target relay wireless device or the target network device itself is selected to serve the remote wireless device, the handover response includes a container including identification information of the target relay wireless device serving the remote wireless device or cell identification information of the target network device serving the remote wireless device.

[0118] The embodiments contemplated herein include a computer program or computer program product containing instructions, wherein the program is executed by a processing element to cause the processing element to implement one or more elements of a method, the method comprising: receiving a handover request from a source network device requesting a handover of a remote wireless device served by the source network device or a source relay wireless device served by the source network device, the handover request including identification information of one or more candidate relay wireless devices served by the target network device; selecting a target relay wireless device or the target network device itself from the one or more candidate relay wireless devices to serve the remote wireless device; and sending a handover response to the source network device, wherein if the target relay wireless device or the target network device itself is selected as the serving remote wireless device, the handover response includes a container including identification information of the target relay wireless device serving the remote wireless device or cell identification information of the target network device serving the remote wireless device. The processor may be a processor of a base station (such as the processor 220 of the network device 218 as a base station, as described herein). For example, these instructions may be located in the processor and / or on a memory of the base station (such as the memory 222 of the network device 218 as a base station, as described herein).

[0119] For one or more embodiments, at least one of the components set forth in one or more of the foregoing figures may be configured to perform one or more operations, techniques, processes, and / or methods as described herein. For example, a baseband processor as described herein in conjunction with one or more of the foregoing figures may be configured to operate according to one or more of the examples set forth herein. For another example, circuits associated with a UE, a base station, a network element, etc. as described above in conjunction with one or more of the foregoing figures may be configured to operate according to one or more of the examples set forth herein.

[0120] Unless otherwise expressly stated, any of the above embodiments may be combined with any other embodiment (or combination of embodiments). The foregoing description of one or more specific implementations provides illustration and description, but is not intended to be exhaustive or to limit the scope of the embodiments to the precise form disclosed. In view of the above teachings, modifications and variations are possible or can be obtained from the practice of various embodiments.

[0121] Embodiments and implementations of the systems and methods described herein may include various operations that may be embodied in machine executable instructions to be executed by a computer system. A computer system may include one or more general or special purpose computers (or other electronic devices). A computer system may include hardware components that include specific logic components for performing operations; or may include a combination of hardware, software, and / or firmware.

[0122] It should be appreciated that the systems described herein include descriptions of specific embodiments. These embodiments may be combined into a single system, partially combined into other systems, separated into multiple systems, or otherwise divided or combined. In addition, it is contemplated that parameters, attributes, aspects, etc. of another embodiment may be used in one embodiment. For clarity, these parameters, attributes, aspects, etc. are described only in one or more embodiments, and it should be appreciated that these parameters, attributes, aspects, etc. may be combined with or substituted for parameters, attributes, aspects, etc. of another embodiment unless expressly stated herein.

[0123] It is understood that the use of personally identifiable information should be subject to privacy policies and practices that are generally recognized to meet or exceed industry or government requirements for maintaining user privacy. Specifically, personally identifiable information data should be managed and processed to minimize the risk of unintentional or unauthorized access or use, and the nature of the authorized use should be clearly stated to users.

[0124] Although the foregoing has been described in considerable detail for the sake of clarity, it will be apparent that certain changes and modifications may be made without departing from the principles of the invention. It should be noted that there are many alternative ways to implement both the processes and the apparatus described herein. Therefore, the embodiments of the present invention should be regarded as illustrative rather than restrictive, and the specification is not limited to the details given herein, but may be modified within the scope and equivalents of the appended claims.

Claims

1. A source network device, the source network device comprising: at least one antenna; as well as A processor, the processor being configured to: sending a handover request to a target network device requesting handover of a remote wireless device served by the source network device or a source relay wireless device served by the source network device, the handover request including identification information of one or more candidate relay wireless devices served by the target network device; as well as receiving a handover response from the target network device; and In response to the handover response including a container, sending a handover command including the container to the remote wireless device, the container including identification information of a target relay wireless device selected by the target network device from the one or more candidate relay wireless devices for serving the remote wireless device or cell identification information of the target network device for serving the remote wireless device.

2. The source network device according to claim 1, wherein the processor is further configured to receive a measurement report from the remote wireless device, the measurement report comprising cell identification information of the target network device, identification information of the one or more candidate relay wireless devices served by the target network device, and measurement results of the remote wireless device on the one or more candidate relay wireless devices.

3. The source network device according to claim 2, wherein the measurement report comprises cell identification information of a plurality of network devices, identification information of a plurality of candidate relay wireless devices served by the plurality of network devices, and measurement results of the plurality of candidate relay wireless devices by the remote wireless device, and The processor is further configured to select the target network device from the plurality of network devices based on the measurement report. 4 . The source network device of claim 3 , wherein the measurement report further includes measurement results of the remote wireless device on the plurality of network devices. 5 . The source network device of claim 3 , wherein the handoff request further comprises measurement results of the remote wireless device on the one or more candidate relay wireless devices. 6 . The source network device of claim 4 , wherein the handoff request further includes a measurement result of the remote wireless device on the target network device.

7. The source network device of claim 1, wherein the identification information of the one or more candidate relay wireless devices includes at least a layer 2 identifier (L2 ID).

8. The source network device of claim 1, wherein the container further comprises a configuration of a Sidelink Relay Adaptation Protocol (SRAP) bearer mapping.

9. The source network device of claim 1, wherein the handover response includes a failure cause value indicating that the one or more candidate relay wireless devices were not found.

10. The source network device of claim 1, wherein the container is transparent to the source network device.

11. The source network device of claim 1 , wherein the processor is further configured to: sending another handover request to another target network device requesting handover of the remote wireless device, the another handover request including identification information of one or more other candidate relay wireless devices served by the another target network device; and another handover response including another container is received from the another target network device, the another container including identification information of another target relay wireless device selected by the another target network device from the one or more other candidate relay wireless devices for serving the remote wireless device or cell identification information of the another target network device for serving the remote wireless device.

12. A target network device, the target network device comprising: at least one antenna; as well as A processor, the processor being configured to: receiving, from a source network device, a handover request requesting handover of a remote wireless device served by the source network device or a source relay wireless device served by the source network device, the handover request including identification information of one or more candidate relay wireless devices served by the target network device; selecting a target relay wireless device or the target network device itself from the one or more candidate relay wireless devices to serve the remote wireless device; as well as sending a switching response to the source network device, If the target relay wireless device or the target network device itself is selected to serve the remote wireless device, the handover response includes a container, wherein the container includes identification information of the target relay wireless device for serving the remote wireless device or cell identification information of the target network device for serving the remote wireless device.

13. The target network device of claim 12, wherein the target relay wireless device is selected based at least on a radio resource control (RRC) state of the target relay wireless device.

14. The target network device of claim 12, wherein the handover request further comprises a measurement result of the remote wireless device on the target network device, and the processor is configured to select the target relay wireless device or the target network device itself to serve the remote wireless device based at least on the measurement result of the remote wireless device on the target network device.

15. The target network device of claim 12, wherein the handover request further comprises a measurement result of the remote wireless device on the one or more candidate relay wireless devices, and the processor is configured to select the target relay wireless device or the target network device itself to serve the remote wireless device based at least on the measurement result of the remote wireless device on the one or more candidate relay wireless devices.

16. The target network device of claim 12, wherein the processor is further configured to send an RRC reconfiguration message to the target relay wireless device if the target relay wireless device is in an RRC connected state so as to reconfigure a Sidelink Relay Adaptation Protocol (SRAP) bearer mapping for the target relay wireless device.

17. The target network device of claim 16, wherein the container further comprises a configuration of the Sidelink Relay Adaptation Protocol (SRAP) bearer mapping.

18. The target network device of claim 12, wherein the processor is further configured to assign identification information to the remote wireless device, and wherein the container further includes the identification information of the remote wireless device.

19. The target network device of claim 18, wherein the identification information assigned to the remote wireless device is used at least in a Sidelink Relay Adaptation Protocol (SRAP) header.

20. The target network device of claim 12, wherein if any of the one or more candidate relay wireless devices is not found, the handover response includes a failure cause value indicating that the one or more candidate relay wireless devices are not found.

21. The target network device of claim 12, wherein the container is transparent to the source network device.

22. A method performed by a source network device, the method comprising: sending a handover request to a target network device requesting handover of a remote wireless device served by the source network device or a source relay wireless device served by the source network device, the handover request including identification information of one or more candidate relay wireless devices served by the target network device; as well as receiving a handover response from the target network device; and In response to the handover response including a container, sending a handover command including the container to the remote wireless device, the container including identification information of a target relay wireless device selected by the target network device from the one or more candidate relay wireless devices for serving the remote wireless device or cell identification information of the target network device for serving the remote wireless device.

23. A method performed by a target network device, the method comprising: receiving, from a source network device, a handover request requesting handover of a remote wireless device served by the source network device or a source relay wireless device served by the source network device, the handover request including identification information of one or more candidate relay wireless devices served by the target network device; selecting a target relay wireless device or the target network device itself from the one or more candidate relay wireless devices to serve the remote wireless device; as well as sending a switching response to the source network device, If the target relay wireless device or the target network device itself is selected to serve the remote wireless device, the handover response includes a container, wherein the container includes identification information of the target relay wireless device for serving the remote wireless device or cell identification information of the target network device for serving the remote wireless device.

24. A non-transitory computer-readable storage medium having stored thereon instructions that, when executed by a processor of a source network device, cause the processor to: sending a handover request to a target network device requesting handover of a remote wireless device served by the source network device or a source relay wireless device served by the source network device, the handover request including identification information of one or more candidate relay wireless devices served by the target network device; and receiving a handover response from the target network device; and In response to the handover response including a container, sending a handover command including the container to the remote wireless device, the container including identification information of a target relay wireless device selected by the target network device from the one or more candidate relay wireless devices for serving the remote wireless device or cell identification information of the target network device for serving the remote wireless device.

25. A non-transitory computer-readable storage medium having stored thereon instructions that, when executed by a processor of a target network device, cause the processor to: receiving, from a source network device, a handover request requesting handover of a remote wireless device served by the source network device or a source relay wireless device served by the source network device, the handover request including identification information of one or more candidate relay wireless devices served by the target network device; selecting a target relay wireless device or the target network device itself from the one or more candidate relay wireless devices to serve the remote wireless device; as well as sending a switching response to the source network device, If the target relay wireless device or the target network device itself is selected to serve the remote wireless device, the handover response includes a container, wherein the container includes identification information of the target relay wireless device for serving the remote wireless device or cell identification information of the target network device for serving the remote wireless device.

26. A computer program product comprising computer program instructions stored thereon which, when executed by a processor of a source wireless device, cause the processor to: sending a handover request to a target network device requesting handover of a remote wireless device served by the source network device or a source relay wireless device served by the source network device, the handover request including identification information of one or more candidate relay wireless devices served by the target network device; and receiving a handover response from the target network device; and In response to the handover response including a container, sending a handover command including the container to the remote wireless device, the container including identification information of a target relay wireless device selected by the target network device from the one or more candidate relay wireless devices for serving the remote wireless device or cell identification information of the target network device for serving the remote wireless device.

27. A computer program product comprising computer program instructions stored thereon which, when executed by a processor of a target wireless device, cause the processor to: receiving, from a source network device, a handover request requesting handover of a remote wireless device served by the source network device or a source relay wireless device served by the source network device, the handover request including identification information of one or more candidate relay wireless devices served by the target network device; selecting a target relay wireless device or the target network device itself from the one or more candidate relay wireless devices to serve the remote wireless device; as well as sending a switching response to the source network device, If the target relay wireless device or the target network device itself is selected to serve the remote wireless device, the handover response includes a container, wherein the container includes identification information of the target relay wireless device for serving the remote wireless device or cell identification information of the target network device for serving the remote wireless device.

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