Relay user equipment handover method, apparatus, device and readable storage medium

Abstract

[Solution] The present disclosure provides a method, apparatus, communication device and readable storage medium for handover of a relay UE, which are applied to the wireless communication technical field, and the handover method of a relay UE includes the steps of: determining whether to handover to a target relay UE based on a serving cell of a target relay UE. In the present disclosure, when a remote UE knows that it needs to handover to a target relay UE, determining whether to handover to the target relay UE based on the serving cell of a far-end target relay UE, i.e., using the serving cell of the target relay UE as a reference parameter for whether to perform handover, thereby avoiding the handover failure of the remote UE caused by the change of the serving cell of the relay UE, and improving the stability of the wireless communication system.

Description

[Technical field]

[0001] The present disclosure relates to the field of wireless communication technologies, and in particular to a relay user equipment (UE) handover method, apparatus, communication device and readable storage medium. [Background technology]

[0002] In the related art, a side link communication method is introduced to support direct communication between user equipments. The side link can support three types of transmission methods: unicast, multicast, and broadcast.

[0003] When two UEs perform sidelink communication, one of the UEs may not directly connect to the base station, but may use another UE as a relay to realize connection and communication with the base station. Of the two UEs, the UE that provides the relay function is called a relay UE, and the UE that is connected to the base station via the relay UE is called a remote UE. Communication between the relay UE and the remote UE is performed via a sidelink. Summary of the Invention [Problem to be solved by the invention]

[0004] In view of this, the embodiments of the present disclosure provide a method, apparatus, communication device and readable storage medium for handover of a relay UE.

[0005] According to a first aspect of an embodiment of the present disclosure, a handover method for relay user equipment is provided, the method being performed by a remote user equipment (UE), and including: determining whether to hand over to a target relay UE based on a serving cell of the target relay UE.

[0006] In one embodiment, the step of determining whether to hand over to the target relay UE based on a serving cell of the target relay UE includes the steps of: determining whether a serving cell of the target relay UE satisfies a handover condition in response to satisfying a trigger condition for handing over to the target relay UE; and performing a handover to the target relay UE in response to satisfying the handover condition.

[0007] In one embodiment, the method further comprises not performing a handover to the target relay UE in response to a handover condition not being met.

[0008] In one embodiment, the trigger condition for handing over to the target relay UE includes at least one of: receiving a handover command sent from a base station to instruct the remote UE to hand over to the target relay UE; and determining based on parameters of a sidelink between the remote UE and the target relay UE that a preset condition for handing over to the target relay UE is satisfied, where the preset condition is received from the base station.

[0009] In one embodiment, the parameters of the sidelink between the remote UE and the target relay UE include a channel quality of the sidelink between the remote UE and the target relay UE; The preset condition for handing over to the target relay UE includes that a channel quality of a sidelink between the remote UE and the target relay UE is greater than a preset threshold.

[0010] In one embodiment, the serving cell of the target relay UE satisfies a handover condition including at least one of: the serving cell of the target relay UE is the same as the serving cell of the remote UE; the serving cell of the target relay UE is the same as the serving cell of the target relay UE reported by the remote UE to a base station; and the serving cell of the target relay UE belongs to a cell list.

[0011] In one embodiment, the method further comprises receiving the cell list from a base station, the cell list corresponding to the target relay UE.

[0012] In one embodiment, the method further includes one of the following steps: sending information to the base station to indicate that the remote UE has not handed over to the target relay UE; initiating a reestablishment of a radio resource control link to the target relay UE; triggering a reestablishment request of a radio resource control link; deleting a handover command corresponding to the target relay UE; deleting the preset condition for handing over to the target relay UE; and deleting a handover command corresponding to the target relay UE and the preset condition for handing over to the target relay UE.

[0013] In one embodiment, after the step of transmitting information to the base station to indicate that the remote UE has not handed over to the target relay UE, the method includes a step of receiving a handover command from the base station to instruct the remote UE to hand over to another relay UE other than the target relay UE.

[0014] According to a second aspect of an embodiment of the present disclosure, a method for handing over relay user equipment is provided, the method being performed by a network device and including a step of receiving information sent from a remote user equipment (UE) to indicate that handover to a target relay UE has not been performed.

[0015] In one embodiment, the information for indicating no handover to the target relay UE is determined by the remote UE based on a serving cell of the target relay UE.

[0016] In one embodiment, the information for indicating not handing over to a target relay UE is determined when, in response to satisfying a trigger condition for handing over to the target relay UE, it is determined that a serving cell of the target relay UE does not satisfy a handover condition.

[0017] In one embodiment, the method includes a step of transmitting a cell list to the remote UE, such that if a serving cell of a target relay UE belongs to the cell list, the remote UE determines that the serving cell of the target relay UE satisfies a handover condition and performs a handover to the target relay UE.

[0018] In one embodiment, the method includes sending a handover command to instruct the remote UE to hand over to the target relay UE.

[0019] According to a third aspect of an embodiment of the present disclosure, a handover device for relay user equipment is provided, the device being applied to a remote user equipment (UE) and including a judgment module configured to judge whether to hand over to a target relay UE based on a serving cell of the target relay UE.

[0020] In one embodiment, the determination module includes: a determination unit configured to determine whether a serving cell of the target relay UE satisfies a handover condition in response to satisfying a trigger condition for handing over to the target relay UE; and a processing unit configured to perform a handover to the target relay UE in response to satisfying the handover condition.

[0021] In an embodiment, the processing unit is further configured to, in response to a handover condition not being satisfied, not to perform a handover to the target relay UE.

[0022] In one embodiment, the trigger condition for handing over to the target relay UE includes at least one of: receiving a handover command sent from a base station to instruct the remote UE to hand over to the target relay UE; and determining based on parameters of a sidelink between the remote UE and the target relay UE that a preset condition for handing over to the target relay UE is satisfied, where the preset condition is received from the base station.

[0023] In one embodiment, the parameters of the sidelink between the remote UE and the target relay UE include a channel quality of a sidelink between the remote UE and the target relay UE, and the pre-defined condition for handing over to the target relay UE includes a channel quality of a sidelink between the remote UE and the target relay UE being greater than a pre-defined threshold.

[0024] In one embodiment, the serving cell of the target relay UE satisfies a handover condition including at least one of: the serving cell of the target relay UE is the same as the serving cell of the remote UE; the serving cell of the target relay UE is the same as the serving cell of the target relay UE reported by the remote UE to a base station; and the serving cell of the target relay UE belongs to a cell list.

[0025] In one embodiment, the apparatus includes a receiving module configured to receive the cell list from a base station, the cell list corresponding to the target relay UE.

[0026] In one embodiment, the apparatus includes a receiving module and a processing module, wherein the receiving module is configured to perform one of the following steps: sending information to the base station to indicate that the target relay UE has not been handed over; and initiating a reestablishment of a radio resource control link to the target relay UE, and the processing module is configured to perform one of the following steps: triggering a reestablishment request of a radio resource control link; deleting a handover command corresponding to the target relay UE; deleting the preset condition for handing over to the target relay UE; and deleting a handover command corresponding to the target relay UE and the preset condition for handing over to the target relay UE.

[0027] In one embodiment, the apparatus includes a receiving module configured to receive a handover command from the base station to instruct a handover to another relay UE other than the target relay UE.

[0028] According to a fourth aspect of an embodiment of the present disclosure, a handover device for relay user equipment is provided, the device being applied to a base station and including a receiving module configured to receive information sent from a remote user equipment (UE) to indicate that handover to a target relay UE has not been performed.

[0029] In one embodiment, the information for indicating no handover to the target relay UE is determined by the remote UE based on a serving cell of the target relay UE.

[0030] In one embodiment, the information for indicating not handing over to a target relay UE is determined when, in response to satisfying a trigger condition for handing over to the target relay UE, it is determined that a serving cell of the target relay UE does not satisfy a handover condition.

[0031] In one embodiment, the apparatus further includes a sending module configured to send a cell list to the remote UE, the cell list being for the remote UE to determine that a serving cell of a target relay UE satisfies a handover condition if the serving cell of the target relay UE belongs to the cell list, and to perform a handover to the target relay UE.

[0032] In one embodiment, the apparatus further includes a sending module configured to send a handover command to instruct the remote UE to hand over to the target relay UE.

[0033] According to a fifth aspect of an embodiment of the present disclosure, a communication device is provided, the communication device including a processor and a memory for storing processor-executable instructions, the processor configured to execute the executable instructions in the memory to implement steps of the method.

[0034] According to a sixth aspect of an embodiment of the present disclosure, a communication device is provided, the communication device including a processor and a memory for storing processor-executable instructions, the processor configured to execute the executable instructions in the memory to realize steps of the method.

[0035] According to a seventh aspect of an embodiment of the present disclosure, a non-transitory computer-readable storage medium having executable instructions stored thereon is provided, the executable instructions, when executed by a processor, realizing steps of a handover method for the relay UE.

[0036] According to an eighth aspect of an embodiment of the present disclosure, a non-transitory computer-readable storage medium having executable instructions stored thereon is provided, the executable instructions, when executed by a processor, realizing steps of a handover method for the relay UE. Effect of the Invention

[0037] The technical solutions provided in the embodiments of the present application may include the following beneficial effects: When a remote UE knows that it needs to handover to a target relay UE, it determines whether to handover to the target relay UE based on the serving cell of the remote target relay UE, i.e., the serving cell of the target relay UE is used as a reference parameter for whether to perform handover, thereby avoiding the handover failure of the remote UE caused by the change of the serving cell of the relay UE, and improving the stability of the wireless communication system.

[0038] It is to be understood that the foregoing general description and the following detailed description are exemplary and explanatory only and are not restrictive of the present disclosure. [Brief description of the drawings]

[0039] The drawings described herein are used to provide a further understanding of the embodiments of the present disclosure, and constitute a part of this application, and the schematic embodiments and the description thereof are used to explain the embodiments of the present disclosure, and are not intended to unduly limit the embodiments of the present disclosure. In the drawings, the drawings herein are incorporated in the specification, constitute a part of this specification, show embodiments that fulfill the embodiments of the present disclosure, and are used together with the specification to interpret the principles of the embodiments of the present disclosure. [Figure 1] 1 is a schematic diagram of a wireless communication system according to an exemplary embodiment; [Diagram 2] 4 is a flowchart of a handover method for a relay UE according to an exemplary embodiment; [Diagram 3] 4 is a flowchart of a handover method for a relay UE according to an exemplary embodiment; [Figure 4] 4 is a flowchart of a handover method for a relay UE according to an exemplary embodiment; [Diagram 5] 4 is a flowchart of a handover method for a relay UE according to an exemplary embodiment; [Figure 6] FIG. 2 is a structural diagram of a handover device of a relay UE shown in accordance with an exemplary embodiment; [Figure 7] FIG. 2 is a structural diagram of a handover device of a relay UE shown in accordance with an exemplary embodiment; [Figure 8] FIG. 2 is a structural diagram of a handover device of a relay UE shown in accordance with an exemplary embodiment; [Figure 9] FIG. 2 is a structural diagram of a handover device of a relay UE shown in accordance with an exemplary embodiment; DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0040] Examples of the present disclosure will be further described in conjunction with the drawings and specific embodiments.

[0041] Exemplary embodiments will now be described in detail, examples of which are shown in the drawings. Where the following description refers to the drawings, the same numerals in different figures represent the same or similar elements unless otherwise noted. The embodiments described in the following exemplary embodiments do not represent all embodiments consistent with embodiments of the present disclosure. Instead, they are merely examples of apparatus and methods consistent with some aspects of the present disclosure, as detailed in the appended claims.

[0042] The terms used in the embodiments of the present disclosure are used only to describe certain embodiments and are not intended to limit the embodiments of the present disclosure. The singular forms "a" and "the" used in the embodiments of the present disclosure and the appended claims are also intended to include the plural forms unless the context clearly dictates otherwise. It will be understood that the term "and / or" used herein means to include any or all possible combinations of one or more of the associated listed items.

[0043] In the embodiments of the present disclosure, terms such as first, second, and third may be used to describe various pieces of information, but it should be understood that the information is not limited to these terms. These terms are used only to distinguish between the same types of information. For example, the first information may be referred to as the second information, and similarly, the second information may be referred to as the first information, without departing from the scope of the embodiments of the present disclosure. Depending on the context, the word "if" as used herein may be interpreted as "when," "in the case of," or "in response to determining."

[0044] Referring to Fig. 1, a schematic diagram of the structure of a wireless communication system provided in an embodiment of the present disclosure is shown. As shown in Fig. 1, the wireless communication system is a communication system based on cellular mobile communication technology, and may include a number of user equipments 110 and a number of base stations 120.

[0045] Here, the user equipment 110 may be a device that provides voice and / or data connectivity to a user. The user equipment 110 may communicate with one or more core networks via a radio access network (RAN), and the user equipment 110 may be user equipment in the Internet of Things, such as a sensor device, a mobile phone (also called a "cellular" phone), and a computer with Internet of Things user equipment, such as a fixed, portable, pocket, handheld, computer-embedded, or vehicle-mounted device. For example, the user equipment 110 may be a station (STA), subscriber unit, subscriber station, mobile station, mobile, remote station, access point, remote terminal, access terminal, user terminal, user agent, user device, or user equipment. Alternatively, the user equipment 110 may be an unmanned aerial vehicle device, or may be an in-vehicle device, such as a trip computer with wireless communication capabilities, or wireless user equipment with an external trip computer, or may be a roadside device, such as a street light, traffic light, or other roadside device with wireless communication capabilities.

[0046] The base station 120 may be a network side device in a wireless communication system. Here, the wireless communication system may be the 4th generation mobile communication (4G) system, also called Long Term Evolution (LTE) system, or the wireless communication system may be a 5G system, also called New Air Interface System or 5G NR system. Or the wireless communication system may be a next-generation system of the 5G system. Here, the access network in the 5G system may be called a New Generation-Radio Access Network (NG-RAN).

[0047] Here, the base station 120 may be an evolved base station (eNB) adopted in a 4G system. Or, the base station 120 may be a base station (gNB) adopting a centralized distributed architecture in a 5G system. When the base station 120 adopts a centralized distributed architecture, it generally includes a central unit (CU) and at least two distributed units (DU). The central unit is provided with a packet data convergence protocol (PDCP) layer, a radio link control (RLC) layer, and a medium access control (MAC) layer protocol stack, and the distributed units are provided with a physical (PHY) layer protocol stack. The embodiments of the present disclosure do not limit the specific implementation manner of the base station 120.

[0048] A wireless connection can be established between the base station 120 and the user equipment 110 via a wireless air interface. In different embodiments, the wireless air interface is a wireless air interface based on a fourth generation mobile communication network technology (4G) standard, or the wireless air interface is a wireless air interface based on a fifth generation mobile communication network technology (5G) standard, for example, the wireless air interface is a new air interface, or the wireless air interface may be a wireless air interface based on a 5G next generation mobile communication network technology standard.

[0049] In some embodiments, an end-to-end (E2E) connection can be further established between the user equipments 110. For example, vehicle-to-vehicle (V2V) communication, vehicle-to-infrastructure (V2I) communication, and vehicle-to-pedestrian (V2P) communication in vehicle-to-everything (V2X) Internet communication can be used.

[0050] Here, the user equipment may be considered as a terminal device in the following embodiments.

[0051] In some embodiments, the wireless communication system may further include a network management device 130 .

[0052] The multiple base stations 120 are respectively connected to a network management device 130. Here, the network management device 130 may be a core network device in a wireless communication system, for example, the network management device 130 may be a Mobility Management Entity (MME) in an Evolved Packet Core (EPC) network. Or, the network management device may be other core network devices, such as a Serving Gate Way (SGW), a Public Data Network Gate Way (PGW), a Policy and Charging Rules Function (PCRF) or a Home Subscriber Server (HSS). The implementation form of the network management device 130 is not limited by the embodiment of the present disclosure.

[0053] In one embodiment, the remote UE cannot perform handover operation during the process of moving between base stations because if the remote UE performs handover to the relay UE during the process of moving between base stations, the service will be discontinuous. The base station selects an appropriate relay UE based on the measurement report reported by the remote UE, and carries the identifier of the selected relay UE in the handover command sent to the remote UE. However, after the remote UE sends the measurement report, the relay UE may change the serving cell, and if the serving cell of the relay UE is changed (e.g., changed to a cell in another base station other than the base station to which the remote UE belongs) after the remote UE receives the handover command, the handover may fail.

[0054] In order to solve the problem that the change of the serving cell of the relay UE causes the handover of the remote UE to fail, the embodiment of the present disclosure provides a handover method of the relay UE, and the method is executed by the remote UE. Referring to Fig. 2, Fig. 2 is a flowchart of the handover method of the relay UE shown in the exemplary embodiment, as shown in Fig. 2, the handover method of the relay UE includes the following step S21:

[0055] In step S21, it is determined whether to perform handover to the target relay UE based on the serving cell of the target relay UE.

[0056] In the embodiment of the present disclosure, the remote UE and the relay UE may be various types of user equipment, for example, the remote UE and the relay UE may be a mobile phone, a smart terminal, a computer, a server, a transmitting / receiving device, a tablet device, a medical device, etc., or a game console, a multimedia device, a wearable device, etc. It is only necessary that the remote UE and the relay UE can communicate with each other via an SL connection.

[0057] In a wireless communication system, a relay UE is a UE that provides a relay function, and a remote UE is a UE that is connected to a base station via a relay UE.

[0058] The base station here is an interface device through which the UE accesses the Internet, and the base station may be various types of base stations, such as a 3G base station, a 4G base station, a 5G base station or other evolved base stations, and further, the base station may be a base station of a terrestrial network or a base station of a non-terrestrial network.

[0059] In one embodiment, before step S21, the method further includes the step of: the remote UE receiving a discovery signal from the relay UE, and obtaining an identifier of a serving cell of the relay UE from the discovery signal.

[0060] Here, the relay UE and the remote UE transmit discovery signals to each other to discover each other. The discovery signal transmitted from the relay UE carries an identifier of the serving cell of the relay UE.

[0061] In one embodiment, if the remote UE finds out that it needs to handover to the target relay UE, it executes step S21.

[0062] Knowing that the remote UE needs to handover to the target relay UE includes at least one of the following two ways.

[0063] In the manner 1, a handover command sent from a base station to instruct a remote UE to handover to a target relay UE is received.

[0064] In method 2, the handover condition is detected as being met by the remote UE.

[0065] Wherein, the method 2 is applied to a situation where a base station sets an automatic handover mechanism for a remote UE, which means that the base station sends a handover command corresponding to a handover condition and a target relay UE to the remote UE, and detects in real time whether the remote UE meets the handover condition.

[0066] In one embodiment, execute step S21 if a handover command sent from a base station is received to instruct the remote UE to handover to the target relay UE.

[0067] In one embodiment, if the remote UE detects that the handover condition is met, it executes step S21.

[0068] Wherein, step S21 further includes a step of initiating handover to the target relay UE when it is determined that handover to the target relay UE is required based on the serving cell of the remote target relay UE, or step S21 does not initiate handover to the target relay UE when it is determined that handover to the target relay UE is not required based on the serving cell of the remote target relay UE.

[0069] In the embodiment of the present disclosure, when a remote UE knows that it needs to handover to a target relay UE, it determines whether to handover to the target relay UE based on the serving cell of the far-end target relay UE, i.e., the serving cell of the target relay UE is used as a reference parameter for whether to perform handover, thereby avoiding the handover failure of the remote UE caused by the change of the serving cell of the relay UE, and improving the stability of the wireless communication system.

[0070] The embodiment of the present disclosure provides a handover method for a relay UE, and the method is executed by a remote UE. Referring to Fig. 3, Fig. 3 is a flowchart of a handover method for a relay UE shown in an exemplary embodiment, as shown in Fig. 3, the handover method for a relay UE includes the following steps S31 and S32:

[0071] In step S31, in response to satisfying a trigger condition for handing over to a target relay UE, it is determined whether a serving cell of the target relay UE satisfies a handover condition.

[0072] In step S32, in response to satisfying a handover condition, perform a handover to the target relay UE.

[0073] or not performing a handover to the target relay UE in response to the handover condition not being met.

[0074] or inhibiting execution of handover to the target relay UE in response to the handover condition not being satisfied.

[0075] In one embodiment, the trigger conditions for handing over to the target relay UE in step S31 include at least one of the following:

[0076] 1. A handover command sent from a base station is received to instruct the remote UE to hand over to the target relay UE. In one example, the handover command is a reallocation message sent from the base station, and the reallocation message includes instruction information for instructing the remote UE to hand over to the target relay UE.

[0077] Second, based on parameters of a sidelink between a remote UE and the target relay UE, it is determined that a preset condition for handing over to the target relay UE is satisfied, where the preset condition is received from the base station.

[0078] In one example, the parameters of the sidelink between the remote UE and the target relay UE include a channel quality of the sidelink between the remote UE and the target relay UE.

[0079] The preset condition for handing over to the target relay UE includes that a channel quality of a sidelink between the remote UE and the target relay UE is greater than a preset threshold.

[0080] In one embodiment, in step S31, the serving cell of the target relay UE satisfies the handover condition, the handover condition includes at least one of the following:

[0081] First, the serving cell of the target relay UE is the same as the serving cell of the remote UE.

[0082] Second, the serving cell of the target relay UE is the same as the serving cell of the target relay UE reported to the base station by the remote UE.

[0083] In one example, the remote UE stores the serving cell of the target relay UE that it has already reported to the base station.

[0084] Third, the serving cell of the target relay UE belongs to the cell list.

[0085] In one example, before step S31, the method further includes the step of receiving the cell list from a base station, the cell list corresponding to the target relay UE, and different target relay UEs corresponding to different cell lists, where the cell list includes one or more cells.

[0086] In an embodiment of the present disclosure, a trigger condition for handing over to the target relay UE is set for a remote UE, and when the trigger condition for handing over to the target relay UE is satisfied, it is determined whether the serving cell of the target relay UE satisfies the handover condition. If the handover condition is satisfied, a handover to the target relay UE is performed, thereby avoiding a handover failure of the remote UE due to a change in the serving cell of the relay UE, and improving the stability of the wireless communication system.

[0087] An embodiment of the present disclosure provides a handover method for a relay UE, which is executed by a remote UE. The handover method for a relay UE includes the following steps S1-1 to S1-2.

[0088] In step S1-1, in response to satisfying a trigger condition for handover to the target relay UE, if it is determined that the serving cell of the target relay UE does not satisfy the handover condition, then handover to the relay UE is not performed.

[0089] In step S2-1, information is sent to the base station to indicate that the remote UE has not been handed over to the target relay UE.

[0090] In one embodiment, the information for indicating a non-handover to a target relay UE includes at least one of an identifier of the target relay UE and an identifier of a serving cell of the target relay UE.

[0091] In an embodiment of the present disclosure, a trigger condition for handing over to the target relay UE is set for a remote UE, and when the trigger condition for handing over to the target relay UE is satisfied, it is determined whether the serving cell of the target relay UE satisfies the handover condition; if the handover condition is not satisfied, the handover to the target relay UE is not performed, and information is sent to the base station to indicate that the handover has not been performed to the target relay UE, so that the base station is aware of the state in which the remote UE has not handed over to the target relay UE in a timely manner, and the base station performs reasonable subsequent control operations based on this state.

[0092] The embodiment of the present disclosure provides a handover method for a relay UE, which is executed by a remote UE. The handover method for a relay UE includes the following steps S1 to S3.

[0093] In step S1, in response to satisfying a trigger condition for handing over to the target relay UE, if it is determined that the serving cell of the target relay UE does not satisfy a handover condition, then handing over to the relay UE is not performed.

[0094] In step S2, information for indicating that handover is not performed to the target relay UE is transmitted to the base station.

[0095] In step S3, a handover command is received from the base station to instruct a handover to another relay UE other than the target relay UE.

[0096] In one embodiment, the information for indicating a non-handover to a target relay UE includes at least one of an identifier of the target relay UE and an identifier of a serving cell of the target relay UE.

[0097] In an embodiment of the present disclosure, a trigger condition for handing over to the target relay UE is set for a remote UE, and when the trigger condition for handing over to the target relay UE is satisfied, it is determined whether the serving cell of the target relay UE satisfies the handover condition; if the handover condition is not satisfied, the handover to the target relay UE is not performed, and information is sent to the base station to indicate that the target relay UE has not been handed over, so that the base station is timely aware of the state in which the remote UE has not been handed over to the target relay UE, and the base station rationally allocates other relay UEs to the remote UE based on this state, and sends a new handover command to the remote UE to hand over the remote UE to the required relay UE.

[0098] The embodiment of the present disclosure provides a handover method for a relay UE, which is executed by a remote UE. The handover method for a relay UE includes the following steps S1 to S2.

[0099] In step S1, in response to satisfying a trigger condition for handing over to the target relay UE, if it is determined that the serving cell of the target relay UE does not satisfy a handover condition, then handing over to the relay UE is not performed.

[0100] In step S2, initiate radio resource control (RRC) link re-establishment to the target relay UE.

[0101] The embodiment of the present disclosure provides a handover method for a relay UE, which is executed by a remote UE. The handover method for a relay UE includes the following steps S1 to S2.

[0102] In step S1, in response to satisfying a trigger condition for handing over to the target relay UE, if it is determined that the serving cell of the target relay UE does not satisfy a handover condition, then handing over to the relay UE is not performed.

[0103] At S2, a request for re-establishment of the radio resource control link is triggered.

[0104] Here, triggering a radio resource control link reestablishment request means that the remote UE initiates a flow to initiate a radio resource control (RRC) link reestablishment to the target relay UE, or initiates a flow to trigger the target relay UE to initiate a flow to initiate a radio resource control (RRC) link reestablishment to the remote UE by sending a trigger request to the target relay UE.

[0105] The embodiment of the present disclosure provides a handover method for a relay UE, which is executed by a remote UE. The handover method for a relay UE includes the following steps S1 to S2.

[0106] In step S1, in response to satisfying a trigger condition for handing over to the target relay UE, if it is determined that the serving cell of the target relay UE does not satisfy a handover condition, then handing over to the relay UE is not performed.

[0107] In step S2, at least one of the following is performed: deleting a handover command corresponding to the target relay UE; and deleting the pre-set condition for handing over to the target relay UE.

[0108] In the embodiment of the present application, when the trigger condition for handover to the target relay UE is met, after determining that the serving cell of the target relay UE does not satisfy the handover condition, the handover to the target relay UE is not performed, and the related handover command and / or the preset condition for handover to the target relay UE are deleted, that is, the mechanism of the remote UE independently handing over to the target relay is abandoned, and the mechanism of the base station sending the handover command is adopted.

[0109] The embodiment of the present disclosure provides a handover method for a relay UE, and the method is executed by a network device. Referring to Fig. 4, Fig. 4 is a flowchart of a handover method for a relay UE shown in an exemplary embodiment. As shown in Fig. 4, the handover method for a relay UE includes the following step S41:

[0110] In step S41, information transmitted from a remote UE to instruct a target relay UE that handover has not been performed is received.

[0111] In one embodiment, the information for indicating no handover to the target relay UE is determined by the remote UE based on a serving cell of the target relay UE.

[0112] In one embodiment, the information for indicating not handing over to a target relay UE is determined when, in response to satisfying a trigger condition for handing over to the target relay UE, it is determined that a serving cell of the target relay UE does not satisfy a handover condition.

[0113] In one embodiment, the information for indicating a non-handover to a target relay UE includes at least one of an identifier of the target relay UE and an identifier of a serving cell of the target relay UE.

[0114] In the embodiment of the present disclosure, when a remote UE finds out that it needs to handover to a target relay UE, it determines whether to handover to the target relay UE according to the serving cell of the far-end target relay UE, i.e., the serving cell of the target relay UE is used as a reference parameter for whether to perform handover, thereby avoiding the handover failure of the remote UE caused by the change of the serving cell of the relay UE; and when it is determined that the remote UE does not need to handover to the target relay UE,

[0115] An embodiment of the present disclosure provides a handover method for a relay UE, and the method is executed by a network device. Referring to Fig. 5, Fig. 5 is a flowchart of a handover method for a relay UE shown in an exemplary embodiment, as shown in Fig. 5, the handover method for a relay UE includes the following steps S51 to S52:

[0116] In step S51, information transmitted from a remote UE to instruct a target relay UE that handover has not been performed is received.

[0117] In step S52, a handover command is sent to the remote UE to instruct it to perform handover to another relay UE other than the target relay UE.

[0118] In one embodiment, the information for indicating no handover to the target relay UE is determined by the remote UE based on the serving cell of the target relay UE.

[0119] In one embodiment, the information for indicating not handing over to the target relay UE is determined when, in response to satisfying a trigger condition for handing over to the target relay UE, it is determined that a serving cell of the target relay UE does not satisfy a handover condition.

[0120] An embodiment of the present disclosure provides a handover method for a relay UE, the method being executed by a network device, the method including: sending a cell list to the remote UE, where the cell list is for allowing the remote UE to determine that the serving cell of the target relay UE satisfies a handover condition and perform handover to the target relay UE if a serving cell of a target relay UE belongs to the cell list; and receiving information sent from the remote UE to indicate not handing over to the target relay UE.

[0121] In an embodiment of the present disclosure, the network device is configured to adopt a mechanism for the remote UE to autonomously determine whether to hand over to the target relay UE, and receive information to indicate not to hand over to the target relay UE when the remote UE determines that the handover condition is not satisfied.

[0122] An embodiment of the present disclosure provides a handover method for a relay UE, which is executed by a network device, and includes the steps of: receiving information sent from a remote UE to indicate that a target relay UE has not been handed over; and sending a handover command to indicate that the remote UE should hand over to the target relay UE.

[0123] In an embodiment of the present disclosure, after receiving information sent from a remote UE to indicate that the remote UE has not handed over to the target relay UE, the network device determines that the remote UE should abandon the mechanism of autonomous handover from the remote UE to the target relay UE, and further adopts a mechanism of a base station sending a handover command to send a handover command to the remote UE to instruct the remote UE to hand over to the target relay UE, so as to allow the remote UE to smoothly complete the handover.

[0124] An embodiment of the present disclosure provides a handover device for a relay UE, which is applied to a remote UE. Referring to Fig. 6, Fig. 6 is a structural diagram of a handover device for a relay UE shown in an exemplary embodiment, as shown in Fig. 6, the handover device for a relay UE includes: a judgment module 61, configured to judge whether to handover to a target relay UE according to a serving cell of the target relay UE.

[0125] In one embodiment, the determination module 61 includes a determination unit configured to determine whether a serving cell of the target relay UE satisfies a handover condition in response to satisfying a trigger condition for handing over to the target relay UE, and a processing unit configured to perform a handover to the target relay UE in response to satisfying the handover condition.

[0126] In an embodiment, the processing unit is further configured to, in response to a handover condition not being satisfied, not to perform a handover to the target relay UE.

[0127] In one embodiment, the trigger condition for handing over to the target relay UE includes at least one of: receiving a handover command sent from a base station to instruct the remote UE to hand over to the target relay UE; and determining based on parameters of a sidelink between the remote UE and the target relay UE that a preset condition for handing over to the target relay UE is satisfied, where the preset condition is received from the base station.

[0128] In one embodiment, the parameters of the sidelink between the remote UE and the target relay UE include a channel quality of a sidelink between the remote UE and the target relay UE, and the pre-defined condition for handing over to the target relay UE includes a channel quality of a sidelink between the remote UE and the target relay UE being greater than a pre-defined threshold.

[0129] In one embodiment, the serving cell of the target relay UE satisfies a handover condition including at least one of: the serving cell of the target relay UE is the same as the serving cell of the remote UE; the serving cell of the target relay UE is the same as the serving cell of the target relay UE reported by the remote UE to a base station; and the serving cell of the target relay UE belongs to a cell list.

[0130] In one embodiment, the apparatus includes a receiving module configured to receive the cell list from a base station, the cell list corresponding to the target relay UE.

[0131] In one embodiment, the apparatus includes a transmitting module and a processing module, wherein the transmitting module is configured to perform one of the following steps: transmitting information to the base station to indicate that the remote UE has not handed over to the target relay UE; and initiating a reestablishment of a radio resource control link to the target relay UE; and the processing module is configured to perform one of the following steps: triggering a reestablishment request of a radio resource control link; deleting a handover command corresponding to the target relay UE; deleting the preset condition for handing over to the target relay UE; and deleting a handover command corresponding to the target relay UE and the preset condition for handing over to the target relay UE.

[0132] In one embodiment, the apparatus includes a receiving module configured to receive a handover command from the base station to instruct a handover to another relay UE other than the target relay UE.

[0133] An embodiment of the present disclosure provides a handover device for a relay UE, which is applied to a network device. Referring to Fig. 7, Fig. 7 is a structural diagram of a handover device for a relay UE shown in an exemplary embodiment, as shown in Fig. 7, the handover device for a relay UE includes: a receiving module 71 configured to receive information sent from a user equipment (UE) to indicate that a handover is not performed to a target relay UE;

[0134] In one embodiment, the information for indicating no handover to the target relay UE is determined by the remote UE based on a serving cell of the target relay UE.

[0135] In one embodiment, the information for indicating not handing over to a target relay UE is determined when, in response to satisfying a trigger condition for handing over to the target relay UE, it is determined that a serving cell of the target relay UE does not satisfy a handover condition.

[0136] In one embodiment, the apparatus further includes a sending module configured to send a cell list to the remote UE, such that if a serving cell of a target relay UE belongs to the cell list, the remote UE determines that the serving cell of the target relay UE satisfies a handover condition and performs a handover to the target relay UE.

[0137] In one embodiment, the apparatus further includes a sending module configured to send a handover command to instruct the remote UE to hand over to the target relay UE.

[0138] An embodiment of the present disclosure provides a user equipment including a processor and a memory for storing processor-executable instructions, the processor being configured to execute the executable instructions in the memory to implement steps of a handover method for the relay UE.

[0139] An embodiment of the present disclosure provides a network device including a processor and a memory for storing processor-executable instructions, the processor configured to execute the executable instructions in the memory to implement steps of a handover method for the relay UE.

[0140] An embodiment of the present disclosure provides a non-transitory computer-readable storage medium having executable instructions stored thereon, where, when the executable instructions are executed by a processor, steps of a handover method for the relay UE are realized.

[0141] An embodiment of the present disclosure provides a non-transitory computer-readable storage medium having executable instructions stored thereon, where, when the executable instructions are executed by a processor, steps of a handover method for the relay UE are realized.

[0142] 8 is a block diagram of user equipment 800 shown in accordance with an exemplary embodiment. For example, user equipment 800 may be a mobile phone, a computer, digital broadcast user equipment, a messaging device, a game console, a tablet, a medical device, a fitness device, a personal digital assistant, etc.

[0143] Referring to FIG. 8, the user equipment 800 may include one or more of a processing component 802, a memory 804, a power component 806, a multimedia component 808, an audio component 810, an input / output (I / O) interface 812, a sensor component 814, and a communication component 816.

[0144] The processing component 802 generally controls the overall operation of the user equipment 800, such as operations related to display, phone calls, data communication, camera operation, and recording operation. The processing component 802 may include one or more processors 820 to execute instructions to complete all or some of the steps of the above methods. The processing component 802 may also include one or more modules to facilitate interaction between the processing component 802 and other components. For example, the processing component 802 may include a multimedia module to facilitate interaction between the multimedia component 808 and the processing component 802.

[0145] The memory 804 is configured to store various data to support operation of the user equipment 800. Examples of such data include instructions for any application programs or methods operated on the user equipment 800, contact data, phone book data, messages, pictures, videos, etc. The memory 804 can be implemented by any type of volatile or non-volatile storage device, such as, for example, a static random access memory (SRAM), an electrically erasable programmable read-only memory (EEPROM), an erasable programmable read-only memory (EPROM), a programmable read-only memory (PROM), a read-only memory (ROM), a magnetic memory, a flash memory, a magnetic disk, or an optical disk, or a combination thereof.

[0146] The power component 806 provides power to the various components of the user equipment 800. The power component 806 may include a power management system, one or more power sources, and other components associated with generating, managing, and distributing power for the user equipment 800.

[0147] The multimedia component 808 includes a screen that provides an output interface between the user equipment 800 and the user. In some embodiments, the screen may include a liquid crystal display (LCD) and a touch panel (TP). When the screen includes a touch panel, the screen can be implemented as a touch panel to receive input signals from the user. The touch panel includes one or more touch sensors to sense touches, slides, and gestures on the touch panel. The touch sensors can not only sense the boundaries of a touch or slide motion, but also detect the duration and pressure associated with the touch or slide motion. In some embodiments, the multimedia component 808 includes one front camera and / or a rear camera. When the user equipment 800 is in an operational mode, such as a photo mode or a video mode, the front camera and / or the rear camera can receive external multimedia data. Each front camera and rear camera may be a specific optical lens system or have a focal length and optical zoom function.

[0148] The audio component 810 is configured to output and / or input audio signals. For example, the audio component 810 includes a microphone (MIC) configured to receive external audio signals when the user equipment 800 is in an operation mode, such as a call mode, a record mode, and a voice recognition mode. The received audio signals can be further stored in the memory 804 or transmitted via the communication component 816. In some embodiments, the audio component 810 further includes a speaker to output the audio signals.

[0149] The I / O interface 812 provides an interface between the processing component 802 and a peripheral interface module, which may be a keyboard, a click wheel, buttons, etc. These buttons may include, but are not limited to, a home button, volume buttons, a start button, and a lock button.

[0150] The sensor component 814 includes one or more sensors to provide the user equipment 800 with a status assessment of each surface. For example, the sensor component 814 can detect the on / off state of the device 800, the relative positioning of a component, e.g., the display and keypad of the user equipment 800, and the sensor component 814 can further detect a change in position of the user equipment 800 or one of the components of the user equipment 800, whether there is contact between the user and the user equipment 800, the orientation or acceleration / deceleration of the user equipment 800, and a temperature change of the user equipment 800. The sensor component 814 may include a proximity sensor configured to detect the presence of a nearby object in the absence of any physical contact. The sensor component 814 may further include an optical sensor used for imaging applications, e.g., a CMOS or CCD image sensor. In some embodiments, the sensor component 814 may further include an acceleration sensor, a gyroscope sensor, a magnetic sensor, a pressure sensor, or a temperature sensor.

[0151] The communication component 816 is configured to facilitate wired or wireless communication between the user equipment 800 and other devices. The user equipment 800 can access a wireless network based on a communication standard, such as WiFi, 2G, or 3G, or a combination thereof. In an exemplary embodiment, the communication component 816 receives a broadcast signal or broadcast-related information from an external broadcast management system via a broadcast channel. In an exemplary embodiment, the communication component 816 further includes a Near Field Communication (NFC) module to facilitate short-range communication. For example, the NFC module can be implemented based on Radio Frequency Identification (RFID) technology, Infrared Data Association (IrDA) technology, Ultra-Wideband (UWB) technology, Bluetooth (BT) technology, and other technologies.

[0152] In an exemplary embodiment, the user equipment 800 may be implemented with one or more application specific integrated circuits (ASICs), digital signal processors (DSPs), digital signal processing devices (DSPDs), programmable logic devices (PLDs), field programmable gate arrays (FPGAs), controllers, microcontrollers, microprocessors, or other electronic elements and may be used to perform the methods described above.

[0153] In an exemplary embodiment, a non-transitory computer readable storage medium containing instructions is further provided, such as a memory 804 containing instructions, which can be executed by the processor 820 of the user equipment 800 to complete the above method. For example, the non-transitory computer readable storage medium may be a ROM, a random access memory (RAM), a CD-ROM, a magnetic tape, a floppy disk, an optical data storage device, and the like.

[0154] As shown in FIG. 9, an embodiment of the present disclosure illustrates a structure of a base station. For example, the base station 900 may be provided as a network side device. With reference to FIG. 9, the base station 900 includes a processing component 922, which further includes one or more processors and a memory resource represented by a memory 932 for storing instructions executable by the processing component 922, such as an application program. The application program stored in the memory 932 may include one or more modules, each corresponding to a set of instructions. And the processing component 922 is configured to execute instructions to perform any method applied to the base station described in the above method.

[0155] Base station 900 may include a power component 926 configured to perform power management of base station 900, a wired or wireless network interface 950 configured to connect base station 900 to a network, and an input / output (I / O) interface 958. Base station 900 may operate an operating system stored in memory 932, such as Windows Server™, Mac OS X™, Unix™, Linux™, Free BSD™, or the like.

[0156] Those skilled in the art will be able to readily devise other implementations of the disclosed embodiments from consideration of the specification and practice of the invention disclosed herein. This application is intended to cover any modifications, uses or adaptations of the disclosed embodiments which follow the general principles of the disclosed embodiments and include means well known or commonly used in the art that are not disclosed in this disclosure. It is intended that the specification and examples be considered as exemplary only, with a true scope and spirit of the disclosed embodiments being indicated by the following claims.

[0157] It will be understood that the embodiments of the present disclosure are not limited to the exact construction described above and illustrated in the drawings, and that various modifications and changes can be made without departing from the scope thereof, which is limited only by the appended claims. [Industrial Applicability]

[0158] When a remote UE knows that it needs to hand over to a target relay UE, it determines whether to hand over to the target relay UE based on the serving cell of the far-end target relay UE, i.e., the serving cell of the target relay UE is used as a reference parameter for whether to perform handover, thereby avoiding the failure of handover of the remote UE caused by the change of the serving cell of the relay UE, and improving the stability of the wireless communication system.

Claims

1. A method for handover to a relay user equipment, the method being performed by a remote user equipment (UE), comprising: determining whether to handover to a target relay UE based on a serving cell of the target relay UE; and in response to a serving cell of the target relay UE satisfying a handover condition, performing a handover to the target relay UE. The serving cell of the target relay UE satisfies a handover condition, the serving cell of the target relay UE being the same as the serving cell of the target relay UE reported by the remote user equipment (UE) to a network device. A method for handing over to relay user equipment.

2. Before the step of determining whether to hand over to the target relay UE based on a serving cell of the target relay UE, receiving a handover command sent from a network device to instruct the remote user equipment (UE) to hand over to the target relay UE; A method for handing over to relay user equipment according to claim 1.

3. The step of determining whether to handover to the target relay UE based on a serving cell of the target relay UE includes: in response to satisfying a trigger condition for handing over to the target relay UE, determining whether a serving cell of the target relay UE satisfies a handover condition. A method for handing over to relay user equipment according to claim 1.

4. The trigger condition for handing over to the target relay UE is: receiving a handover command sent from a network device to instruct the remote user equipment (UE) to hand over to the target relay UE; determining that a preset condition for handing over to the target relay UE is met based on parameters of a sidelink between the remote user equipment (UE) and the target relay UE, the preset condition being received from the network device; A method for handing over to relay user equipment according to claim 3.

5. The parameters of the sidelink between the remote user equipment (UE) and the target relay UE include a channel quality of the sidelink between the remote user equipment (UE) and the target relay UE; The preset condition for handing over to the target relay UE is: a channel quality of a sidelink between the remote user equipment (UE) and the target relay UE is greater than a set threshold. A method for handing over to relay user equipment according to claim 4.

6. and in response to a handover condition not being satisfied, not performing a handover to the target relay UE. A method for handing over to relay user equipment according to any one of claims 1 to 5.

7. sending information to the network device to indicate that the remote user equipment (UE) has not been handed over to the target relay UE; initiating a re-establishment of a radio resource control link to the target relay UE; triggering a radio resource control link re-establishment request; deleting a handover command corresponding to the target relay UE; deleting a preset condition for handing over to the target relay UE; deleting a handover command corresponding to the target relay UE and a preset condition for handing over to the target relay UE. A method for handing over to relay user equipment according to claim 6.

8. after sending information to the network device to indicate that the remote user equipment (UE) has not been handed over to the target relay UE; receiving a handover command from the network device to instruct a handover to another relay UE other than the target relay UE; A method for handover to relay user equipment according to claim 7.

9. 1. A method for handover to relay user equipment, the method being performed by a network device, comprising: sending a handover command to a remote user equipment (UE), the handover command instructing the remote user equipment (UE) to hand over to a target relay UE; the handover command is for triggering the remote UE to determine whether to hand over to the target relay UE based on a serving cell of the target relay UE, and to perform handover to the target relay UE in response to the serving cell of the target relay UE satisfying a handover condition; The serving cell of the target relay UE satisfies a handover condition, the serving cell of the target relay UE being the same as the serving cell of the target relay UE reported by the remote user equipment (UE) to a network device. A method for handing over to relay user equipment.

10. The handover command further comprises: in response to the remote UE not satisfying a handover condition, the serving cell of the target relay UE; sending information to the network device to indicate that the remote user equipment (UE) has not been handed over to the target relay UE; initiating a re-establishment of a radio resource control link to the target relay UE; triggering a radio resource control link re-establishment request; deleting a handover command corresponding to the target relay UE; deleting a preset condition for handing over to the target relay UE; and deleting a handover command corresponding to the target relay UE and a preset condition for handing over to the target relay UE. Trigger like this, A method for handover to relay user equipment according to claim 9.

11. The method according to claim 1, further comprising the step of receiving information transmitted from the remote user equipment (UE) indicating that the remote user equipment (UE) has not been handed over to the target relay UE. A method for handover to relay user equipment according to claim 10.

12. The information for indicating that the remote user equipment (UE) has not handed over to the target relay UE is determined by the remote user equipment (UE) based on a serving cell of the target relay UE. A method for handover to relay user equipment according to claim 11.

13. The information for indicating not to hand over to the target relay UE is determined when, in response to satisfying a trigger condition for handing over to the target relay UE, a remote user equipment (UE) determines that a serving cell of the target relay UE does not satisfy a handover condition. A method for handover to relay user equipment according to claim 11.

14. sending a handover command to the remote user equipment (UE) to instruct the remote user equipment (UE) to perform a handover to another relay UE other than the target relay UE; A method for handover to relay user equipment according to any one of claims 9 to 13.

15. A handover device to a relay user equipment, the handover device being applied to a remote user equipment (UE), a determining module configured to determine whether to hand over to a target relay UE based on a serving cell of the target relay UE; the determining module includes a processing unit; the processing unit is configured to perform a handover to the target relay UE in response to a serving cell of the target relay UE satisfying a handover condition; The serving cell of the target relay UE satisfies a handover condition, the serving cell of the target relay UE being the same as the serving cell of the target relay UE reported by the remote user equipment (UE) to a network device. Handover device to relay user equipment.

16. The determination module is further configured to receive a handover command sent from a network device to instruct the remote user equipment (UE) to hand over to the target relay UE before determining whether to hand over to the target relay UE based on a serving cell of the target relay UE. An apparatus for handing over to relay user equipment according to claim 15.

17. The determination module includes: and a determining unit configured to determine whether a serving cell of the target relay UE satisfies a handover condition in response to satisfying a trigger condition for handing over to the target relay UE. An apparatus for handing over to relay user equipment according to claim 15.

18. The trigger condition for handing over to the target relay UE is: receiving a handover command sent from a network device to instruct the remote user equipment (UE) to hand over to the target relay UE; determining that a preset condition for handing over to the target relay UE is met based on parameters of a sidelink between the remote user equipment (UE) and the target relay UE, the preset condition being received from the network device; An apparatus for handing over to relay user equipment according to claim 17.

19. The parameters of the sidelink between the remote user equipment (UE) and the target relay UE include a channel quality of the sidelink between the remote user equipment (UE) and the target relay UE; The preset condition for handing over to the target relay UE is: a channel quality of a sidelink between the remote user equipment (UE) and the target relay UE is greater than a set threshold.

20. An apparatus for handing over to relay user equipment according to claim 18.

20. the processing unit is further configured to, in response to not satisfying a handover condition, not perform a handover to the target relay UE. An apparatus for handing over to relay user equipment according to any one of claims 15 to 19.

21. The apparatus includes a transmitting module and a processing module; The transmission module: sending information to the network device to indicate that the remote user equipment (UE) has not been handed over to the target relay UE; initiating a re-establishment of a radio resource control link to the target relay UE; and configured to perform one of: The processing module comprises: triggering a radio resource control link re-establishment request; deleting a handover command corresponding to the target relay UE; deleting a preset condition for handing over to the target relay UE; deleting a handover command corresponding to the target relay UE and a preset condition for handing over to the target relay UE; configured to perform one of the following: An apparatus for handing over to relay user equipment according to claim 20.

22. a receiving module configured to receive a handover command from the network device to instruct a handover to another relay UE other than the target relay UE; An apparatus for handing over to relay user equipment according to claim 21.

23. A handover apparatus for relay user equipment, which is applied to a network device, a sending module configured to send a handover command to a remote user equipment (UE), the handover command instructing the remote user equipment (UE) to hand over to a target relay UE; the handover command is for triggering the remote UE to determine whether to hand over to the target relay UE based on a serving cell of the target relay UE, and to perform handover to the target relay UE in response to the serving cell of the target relay UE satisfying a handover condition; The serving cell of the target relay UE satisfies a handover condition, the serving cell of the target relay UE being the same as the serving cell of the target relay UE reported by the remote user equipment (UE) to a network device. Handover device to relay user equipment.

24. The handover command further comprises: in response to the remote UE not satisfying a handover condition, the serving cell of the target relay UE; sending information to the network device to indicate that the remote user equipment (UE) has not been handed over to the target relay UE; initiating a re-establishment of a radio resource control link to the target relay UE; triggering a radio resource control link re-establishment request; deleting a handover command corresponding to the target relay UE; deleting a preset condition for handing over to the target relay UE; and deleting a handover command corresponding to the target relay UE and a preset condition for handing over to the target relay UE. Trigger like this, An apparatus for handing over to relay user equipment according to claim 23.

25. The method according to claim 24, further comprising: a receiving module for receiving information transmitted from the remote user equipment (UE) for indicating that the remote user equipment (UE) has not been handed over to the target relay UE. An apparatus for handing over to relay user equipment according to claim 24.

26. The method of claim 25, wherein the information for indicating that the remote user equipment (UE) has not handed over to the target relay UE is determined by the remote user equipment (UE) based on a serving cell of the target relay UE.

26. An apparatus for handing over to relay user equipment according to claim 25.

27. The information for indicating not to hand over to the target relay UE is determined when, in response to satisfying a trigger condition for handing over to the target relay UE, a remote user equipment (UE) determines that a serving cell of the target relay UE does not satisfy a handover condition.

26. An apparatus for handing over to relay user equipment according to claim 25.

28. The sending module is further configured to send a handover command to the remote user equipment (UE) to instruct the remote user equipment (UE) to perform a handover to another relay UE other than the target relay UE. An apparatus for handing over to relay user equipment according to any one of claims 23 to 27.

29. A processor; a memory for storing processor-executable instructions; The processor is configured to execute executable instructions in the memory to perform the steps of the method according to any one of claims 1 to 8. Communication devices.

30. A processor; a memory for storing processor-executable instructions; The processor is configured to execute executable instructions in the memory to perform the steps of the method according to any one of claims 9 to 14. Communication devices.

31. A non-transitory computer-readable storage medium having executable instructions stored thereon, comprising: When the executable instructions are executed by a processor, the steps of the handover method to a relay UE according to any one of claims 1 to 8 are realized. A non-transitory computer-readable storage medium.

32. A non-transitory computer-readable storage medium having executable instructions stored thereon, comprising: When the executable instructions are executed by a processor, the steps of the handover method to a relay UE according to any one of claims 9 to 14 are realized. A non-transitory computer-readable storage medium.

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