RU2842117C2 - Method and device for handover to relay subscriber device, communication device and readable data medium - Google Patents

Abstract

FIELD: wireless communication.

SUBSTANCE: handover to the relay UE includes a decision whether to perform handover to the target relay UE, based on serving cell of target relay UE, wherein when the remote UE determines the need for handover to the target relay UE, the remote UE determines whether to handover to the target relay UE, based on serving cell of target relay UE. In other words, a serving cell of the target relay UE is used as a reference parameter for handover.

EFFECT: preventing failures during handover by a remote UE (subscriber device), which can be caused by change of the serving cell of the relay UE, which improves stability of the wireless communication system.

18 cl, 9 dwg

Description

Field of technology to which the present invention relates

[1] The present invention relates to the field of wireless communication technologies, in particular to a method and device for implementing handover to a relay UE (subscriber equipment), a communication device and a readable data carrier.

Prior art of the present invention

[2] In the prior art, a side link is provided to provide direct communication between subscriber equipments (UEs). The side link can support the following three transmission modes: unicast mode, multicast mode, and broadcast mode.

[3] In a scenario where two subscriber equipments (UEs) communicate via a sidelink, one of them may not directly connect to the base station. In this case, it may use another UE, which serves as a relay, to establish a connection and communicate with the base station. The UE that provides the relay function is called the relay UE, and the UE that connects to the base station via the relay UE is called the remote UE. The relay UE communicates with the remote UE via a sidelink.

Brief summary of the present invention

[4] In this regard, embodiments of the present invention propose a method and device for implementing handover to a relay UE (subscriber equipment), a communication device and a readable data carrier.

[5] According to a first aspect of the embodiments of the present invention, a method for performing handover to a relay UE is proposed. The proposed method is implemented by a remote UE. This method includes:

[6] deciding whether to perform handover to the target relay UE based on the serving cell of the target relay UE.

[7] In one embodiment of the present invention, deciding whether to perform a handover to a target relay UE based on a serving cell of the target relay UE comprises:

[8] determining whether the serving cell of the target relay UE satisfies the condition for performing handover, based on the fact that the condition for initiating handover to the target relay UE is met; and

[9] performing handover to the target relay UE upon compliance with the handover conditions.

[10] In one embodiment of its implementation, the proposed method also provides for:

[11] failure to perform handover to the target relay UE due to non-compliance with the conditions for performing handover.

[12] In one embodiment of the present invention, the condition for initiating a handover to the target relay UE is at least one of the following conditions:

[13] receiving a handover command from the base station that instructs the remote UE to handover to the target relay UE; or

[14] determining, based on a sidelink parameter between the remote UE and the target relay UE, the fact that a predetermined condition for performing handover to the target relay UE is met; wherein the predetermined condition is received from the base station.

[15] In one embodiment of the present invention, the sidelink parameter between the remote UE and the target relay UE is: the quality of the sidelink channel between the remote UE and the target relay UE; and

[16] The specified condition for performing handover to the target relay UE provides for the following:

[17] the quality of the sidelink channel between the remote UE and the target relay UE exceeds a specified threshold.

[18] In one embodiment of the present invention, the serving cell of the target relay UE satisfying the conditions for performing handover is at least one of the following cells:

[19] the serving cell of the target relay UE, which is the same as the serving cell of the remote UE;

[20] a serving cell of the target relay UE that matches the declared serving cell of the target relay UE that was handed over by the remote UE to the base station; or

[21] the serving cell of the target relay UE included in the cell list.

[22] In one embodiment of its implementation, the proposed method also provides for:

[23] receiving a list of cells from the base station; wherein this list of cells is associated with the target relay UE.

[24] In one embodiment of its implementation, the proposed method also provides for the execution of one of the following operations:

[25] transmitting information to the base station indicating that the remote UE will not perform handover to the target relay UE;

[26] initiating the restoration of the radio resource control channel for communication with the target relay UE;

[27] initiating a request to restore the radio resource control channel;

[28] cancellation of the handover command related to the target relay UE;

[29] canceling the specified condition for performing handover to the target UE relay device; or

[30] canceling the handover execution command related to the target relay UE and the specified condition for performing the handover to the target relay UE.

[31] In one embodiment of the present invention, it is provided that after transmitting to the base station information indicating that the remote UE will not perform handover to the target relay UE, the proposed method further provides:

[32] receiving from the base station another handover command instructing the base station to perform handover to a relay UE other than the target relay UE.

[33] According to a second aspect of the embodiments of the present invention, a method for performing handover to a relay UE is proposed. The proposed method is implemented by a network device. This method includes:

[34] receiving information from the remote UE indicating that handover to the target relay UE has not been completed.

[35] In one embodiment of the present invention, information indicating that handover to the target relay UE has not been performed is determined by the remote UE based on the serving cell of the target relay UE.

[36] In one embodiment of the present invention, information indicating that handover to the target relay UE has not been performed is determined by the remote UE based on determining that the serving cell of the target relay UE does not satisfy the condition for performing handover while meeting the condition for initiating handover to the target relay UE.

[37] In one embodiment of its implementation, the proposed method provides for:

[38] transmitting a list of cells to a remote UE, wherein the list of cells enables the remote UE to determine that the serving cell of the target relay UE satisfies the condition for performing handover, based on the fact that the serving cell of the target relay UE is included in the specified list, and to perform handover to the target relay UE.

[39] In one embodiment of its implementation, the proposed method provides for:

[40] transmitting a handover command instructing the remote UE to perform a handover to the target relay UE.

[41] According to a third aspect of the embodiments of the present invention, a device for handover to a relay UE (subscriber equipment) is provided. This device is applicable to a remote UE and includes:

[42] a determining module configured to determine whether to perform a handover to a target relay UE based on a serving cell of the target relay UE.

[43] In one embodiment, the determination module includes:

[44] a determining unit configured to determine whether the serving cell of the target relay UE satisfies the condition for performing handover when the condition for initiating handover to the target relay UE is met; and

[45] a data processing unit configured to perform a handover to a target relay UE upon compliance with a handover condition.

[46] In one of its implementation options:

[47] The data processing unit is designed with the additional capability of not performing handover to the target relay UE due to non-compliance with the conditions for performing handover.

[48] In one embodiment of the present invention, the condition for initiating a handover to the target relay UE is at least one of the following conditions:

[49] receiving a handover command from the base station, instructing the remote UE to handover to the target relay UE;

[50] determining, based on a sidelink parameter between the remote UE and the target relay UE, the fact that a predetermined condition for performing handover to the target relay UE is met; wherein the predetermined condition is received from the base station.

[51] In one embodiment of the present invention, the sidelink parameter between the remote UE and the target relay UE is: the quality of the sidelink channel between the remote UE and the target relay UE; and

[52] The specified condition for performing handover to the target relay UE provides for the following:

[53] the quality of the sidelink channel between the remote UE and the target relay UE exceeds a specified threshold.

[54] In one embodiment of the present invention, the serving cell of the target relay UE satisfying the conditions for performing handover is at least one of the following cells:

[55] the serving cell of the target relay UE, which is the same as the serving cell of the remote UE;

[56] a serving cell of the target relay UE that matches the declared serving cell of the target relay UE that was handed over by the remote UE to the base station; or

[57] the serving cell of the target relay UE included in the cell list.

[58] In one embodiment, the proposed device includes:

[59] a receiving module configured to receive a list of cells from a base station, wherein the list of cells is associated with a target relay UE.

[60] In one embodiment, the proposed device includes:

[61] a transmitting module capable of performing one of the following operations:

[62] transmitting information to the base station indicating that handover to the target relay UE has not been completed; or

[63] initiating the restoration of the radio resource control channel for communication with the target relay UE;

[64] wherein the data processing module is configured to perform one of the following operations:

[65] initiating a request to restore the radio resource control channel;

[66] cancellation of the handover command related to the target relay UE;

[67] canceling the specified condition for performing handover to the target relay device UE; or

[68] canceling the handover command related to the target relay UE and the specified condition for performing handover to the target relay UE.

[69] In one embodiment, the proposed device includes:

[70] a receiving module configured to receive from the base station another handover command instructing it to perform handover to a relay UE other than the target relay UE.

[71] According to a fourth aspect of the embodiments of the present invention, a device for handover to a relay UE is provided. This device is applicable to a base station and includes:

[72] a receiving module configured to receive from a remote UE information indicating that handover to the target relay UE has not been completed.

[73] In one embodiment of the present invention, information indicating that handover to the target relay UE has not been performed is determined by the remote UE based on the serving cell of the target relay UE.

[74] In one embodiment of the present invention, information indicating that handover to the target relay UE has not been performed is determined by the remote UE based on determining that the serving cell of the target relay UE does not satisfy the condition for performing handover while meeting the condition for initiating handover to the target relay UE.

[75] In one embodiment, the proposed device additionally includes:

[76] a transmitting module configured to transmit a list of cells to a remote UE; wherein the list of cells enables the remote UE to determine that the serving cell of the target relay UE satisfies the condition for performing handover, based on the fact that the serving cell of the target relay UE is included in the specified list, and to perform handover to the target relay UE.

[77] In one embodiment, the proposed device additionally includes:

[78] a transmitting module configured to send a handover command instructing the remote UE to perform a handover to the target relay UE.

[79] According to a fifth aspect of the embodiments of the present invention, a communication device is provided. This communication device includes:

[80] processor; and

[81] memory for storing instructions executed by the processor;

[82] wherein the processor is configured to execute executable commands stored in the memory for the purpose of implementing the proposed methods.

[83] According to a sixth aspect of the embodiments of the present invention, a communication device is provided. This communication device includes:

[84] processor; and

[85] memory for storing commands executed by the processor;

[86] wherein the processor is configured to execute executable commands stored in the memory in order to implement the proposed methods.

[87] According to a seventh aspect of the embodiments of the present invention, a non-volatile machine-readable storage medium is provided, on which executable instructions are stored, wherein when the processor executes these executable instructions, implementation of methods for performing handover to a relay UE is ensured.

[88] According to an eighth aspect of the embodiments of the present invention, a non-volatile computer-readable storage medium is provided, on which executable instructions are stored, wherein when the processor executes these executable instructions, implementation of methods for performing handover to a relay UE is ensured.

[89] The technical solutions implemented in the embodiments of the present invention can achieve the following beneficial effects: when a remote UE determines that a handover to a target relay UE is necessary, the remote UE makes a decision on whether to perform a handover to the target relay UE based on a serving cell of the target relay UE; in other words, the serving cell of the target relay UE is used as a reference parameter for determining whether to perform a handover, so as to avoid failures in performing a handover by the remote UE that may be caused by a change in the serving cell of the relay UE, thereby improving the stability of the wireless communication system.

[90] It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory only and are not restrictive of the present invention in any way.

Brief description of the drawings

[91] The drawings provided in this document are used to provide a deeper understanding of the embodiments of the claimed invention and are an integral part thereof. The schematic representation of the embodiments of the present invention and their descriptions are used to explain the essence of the embodiments of the claimed invention and do not unduly limit them.

[92] The accompanying drawings, which are incorporated in and constitute a part of the present specification, illustrate embodiments of the claimed invention disclosed in the description and, together with the description, serve to explain the principles of the embodiments of the present invention.

[93] Fig. 1 is a diagram illustrating a wireless communication system according to one embodiment of the present invention.

[94] Fig. 2 is a block diagram illustrating a method for performing handover to a relay UE (user equipment) according to one embodiment of the present invention.

[95] Fig. 3 is a flow chart illustrating a method for performing handover to a relay UE according to one embodiment of the present invention.

[96] Fig. 4 is a flow chart illustrating a method for performing handover to a relay UE according to one embodiment of the present invention.

[97] Fig. 5 is a flow chart illustrating a method for performing handover to a relay UE according to one embodiment of the present invention.

[98] Fig. 6 is a block diagram illustrating an apparatus for performing handover to a relay UE according to one embodiment of the present invention.

[99] Fig. 7 is a block diagram of a device for performing handover to a relay UE according to one embodiment of the present invention.

[100] Fig. 8 is a block diagram of a device for performing handover to a relay UE according to one embodiment of the present invention.

[101] Fig. 9 is a block diagram of an apparatus for performing handover to a relay UE according to one embodiment of the present invention.

Detailed disclosure of the present invention

[102] Embodiments of the present invention will be further disclosed below in connection with the accompanying drawings and using the example of particular methods of its implementation.

[103] Reference will now be made in detail to illustrative embodiments of the present invention, examples of which are illustrated in the accompanying drawings. The following description is presented in connection with the accompanying drawings, wherein the same reference numerals presented in different drawings designate the same or similar elements, unless otherwise indicated. The embodiment examples disclosed in the following description of embodiments of the present invention do not represent all possible embodiments corresponding to the claimed invention, but serve only as illustrative examples of implementing devices and methods according to aspects of the present invention, which are set forth in the appended claims.

[104] The terms used in the description of embodiments of the present invention serve solely to describe particular embodiments thereof and should in no way be construed as limiting the claimed invention. As used herein and in the appended claims, the singular forms indicated by the indefinite and definite articles also include the plural forms unless the context clearly dictates otherwise. It should be understood that as used herein, the term "and/or" designates and includes any or all possible combinations of one or more of the corresponding listed elements.

[105] It should be understood that although the description of the embodiments of the present invention may use terms such as "first," "second," "third," and the like to represent various information, the information should not be limited to these terms. These terms are used solely to distinguish between information of the same type. For example, without departing from the scope of the embodiments of the present invention, the first information may also refer to the second information, and similarly, the second information may also refer to the first information. As used herein, the term "if" may be interpreted to mean "upon," "when," or "upon determination that," depending on the context.

[106] Fig. 1 is a diagram illustrating a wireless communication system according to one embodiment of the present invention. As shown in Fig. 1, the wireless communication system is a communication system based on mobile cellular communication technologies. The wireless communication system may include multiple subscriber equipment (UE) 110 and multiple base stations 120.

[107] The UE 110 may be a device that provides voice and/or data communications to a user. The UE 110 may communicate with one or more core networks via a radio access network (RAN). The UE may be an Internet of Things (IoT) subscriber device, such as a sensor device, a mobile phone (a "cellular" phone), or a computer equipped with an IoT subscriber device, such as a fixed, portable, handheld, handheld, embedded in a computer, or installed on a vehicle. For example, it may be a station (STA), a subscriber unit, a subscriber station, a mobile station, a mobile device, a remote station, an access point, a remote terminal, an access terminal, a subscriber terminal, a user agent, a user device, or a subscriber equipment (UE). Alternatively, the UE 110 may also be an unmanned aerial vehicle. In another alternative embodiment, the UE 110 device may be a device installed in a vehicle, such as an on-board computer with a wireless communication function or a wireless device connected to the on-board computer from the outside. In yet another alternative embodiment, the UE 110 device may also be a roadside device, such as a street lamp, a signal lamp or another roadside device with a wireless communication function.

[108] The base station 120 may be a network device in a wireless communication system. The wireless communication system may be a fourth generation (4G) mobile communication system, also known as a Long Term Evolution (LTE) system. In an alternative embodiment, the wireless communication system may be a fifth generation (5G) mobile communication system, also known as a New Radio (NR) system or a 5G NR system. In another alternative embodiment, the wireless communication system may be a next-generation system relative to the 5G system. The access network in the 5G system may be called a next-generation radio access network (NG-RAN).

[109] The base station 120 may be an enhanced base station (eNB) used in the 4G system. Alternatively, the base station 120 may be a gNB with a centralized and distributed architecture in the 5G system. When using a centralized distributed architecture, the base station 120 typically includes a central unit (CU) and at least two distributed units (DUs). The central unit is provided with a protocol stack including a packet data convergence protocol (PDCP) layer, a radio link control (RLC) layer, and a medium access control (MAC) layer. The distributed unit is provided with a physical layer (PHY) protocol stack. However, the embodiments of the present invention do not limit the implementation mechanism of the base station 120.

[110] A wireless connection may be established between the base station 120 and the UE 110 via a wireless radio interface. In various embodiments of the present invention, the wireless radio interface is a wireless radio interface based on a 4G mobile communication standard; or the wireless radio interface is a wireless radio interface based on a 5G mobile communication standard, such as New Radio. Alternatively, the wireless radio interface may be a wireless radio interface based on a mobile communication standard of another generation following the 5G generation.

[111] In some embodiments of the present invention, end-to-end (E2E) communication may also be established between UE devices 110 in scenarios such as vehicle-to-vehicle (V2V) communication, vehicle-to-infrastructure (V2I) communication, and vehicle-to-pedestrian (V2P) communication within vehicle-to-environment (V2X) communication.

[112] In the following description of embodiments of the present invention, said UE device may also be referred to as a terminal.

[113] In some embodiments of the present invention, said wireless communication system may further include a network management device 130.

[114] Each of the base stations 120 is connected to a network control device 130. The network control device 130 may be a core network device in a wireless communication system. For example, the network control device 130 may be a mobility management node (MME). Alternatively, the network control device may be other core network devices, such as a serving gateway (SGW), a public network gateway (PGW), a policy and charging rule function (PCRF) node, or a subscriber server (HSS). The implementation form of the network control device 130 is not limiting in embodiments of the present invention.

[115] In one embodiment of the present invention, it is provided that when a remote UE performs a handover between relay UEs during movement between base stations, this may result in a service interruption, as a result of which the remote UE cannot perform a handover operation during movement between base stations. The base station selects a suitable relay UE based on a measurement report received from the remote UE. An identifier of the selected relay UE is included in a handover command that is sent to the remote UE. However, after the remote UE sends the measurement report, the relay UE may change the serving cell. If, upon receipt of the handover command, the serving cell of the relay UE is changed (e.g. to a cell of the base station different from the one to which the remote UE belongs), this may result in a handover failure.

[116] In order to solve the problem of failure in performing handover by a remote UE due to a change in the serving cell of a relay UE, embodiments of the present invention propose a method for performing handover to a relay UE, which is implemented by the remote UE. Fig. 2 is a flow chart illustrating a method for performing handover to a relay UE according to one embodiment of the present invention. As shown in Fig. 2, this method for performing handover to a relay UE includes performing the step described below.

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

[118] Each device of the remote UE and the relay UE in the embodiments of the present invention may be any type of subscriber equipment (UE). For example, the remote UE and the relay UE may be a mobile phone, an intelligent terminal, a computer, a server, a transceiver, a tablet device, or a medical device. Alternatively, the remote UE and the relay UE may be a game console, a multimedia device, or a wearable device. There is no limitation on the type of the remote UE and the relay UE, as long as they can communicate with each other via a SL connection (via a side channel).

[119] In a wireless communication system, a relay UE is a UE that performs a relay function, and a remote UE is a UE that is connected to a base station through the relay UE.

[120] In the context of this document, a base station is an interface device that provides the UE with access to the Internet. The base station may be of any type. For example, it may be a 3G base station, a 4G base station, a 5G base station, or any other advanced base station. A base station may also be a terrestrial base station or a non-terrestrial base station.

[121] In one embodiment of the present invention, before performing step S21, the proposed method further comprises: receiving, by the remote UE, a discovery signal from the relay UE; and obtaining, by the remote UE, an identifier of a serving cell of the relay UE contained in the discovery signal.

[122] The relay UE and the remote UE exchange discovery signals and identify each other through these signals. The discovery signal transmitted by the relay UE carries the identifier of the serving cell of the relay UE.

[123] In one embodiment of the present invention, step S21 is performed if the remote UE determines that a handover is necessary to the target relay UE.

[124] There are two ways for a remote UE to determine whether it needs to handover to a target relay UE:

[125] Method 1: Receiving a handover command from the base station, instructing the remote UE to handover to the target relay UE; and

[126] Method 2: The remote UE establishes that the handover condition has been met.

[127] Method 2 is applicable in the case where the base station configures an automatic handover mechanism for the remote UE. In other words, the base station configures an automatic handover mechanism for the remote UE, i.e., the base station transmits a handover condition and a handover command corresponding to the target relay UE to the remote UE, and the remote UE determines in real time whether the handover condition is met.

[128] In one embodiment of the present invention, after receiving a handover command transmitted by the base station and instructing the remote UE to perform a handover to the target relay UT, step S21 is performed.

[129] In one embodiment of the present invention, it is provided that step S21 is performed when the remote UE determines that the handover condition is met.

[130] Step S21 further comprises: initiating a handover to the target relay UE upon determining that a handover to the target relay UE is necessary based on the serving cell of the target relay UE. Alternatively, step S21 further comprises: not initiating a handover to the target relay UE upon deciding not to perform a handover to the target relay UE based on the serving cell of the target relay UE.

[131] In one embodiment of the present invention, it is provided that when a remote UE determines that a handover to a target relay UE is necessary, the remote UE makes a decision on whether to perform a handover to the target relay UE based on a serving cell of the target relay UE; in other words, the serving cell of the target relay UE is used as a reference parameter for determining whether to perform a handover, so as to avoid failures in performing a handover by the remote UE that may be caused by a change in the serving cell of the relay UE, which improves the stability of the wireless communication system.

[132] Embodiments of the present invention provide a method for performing a handover to a relay UE, which is performed by a remote UE. Fig. 3 is a flow chart illustrating a method for performing a handover to a relay UE according to one embodiment of the present invention. As shown in Fig. 3, the proposed method for performing a handover to a relay UE includes performing the steps described below.

[133] In step S31, it is determined whether the serving cell of the target relay UE satisfies the condition for performing handover if it is determined that the condition for initiating handover to the target relay UE is met.

[134] At step S32, a handover is performed to the target relay UE upon fulfillment of the handover condition.

[135] An alternative embodiment provides that if the condition for performing handover is not met, then handover to the target relay UE is not performed.

[136] Another alternative provides that if the condition for handover to be performed is not met, then handover to the target relay UE is prohibited.

[137] In one embodiment of the present invention, the condition for initiating handover to the target relay UE, which is set in step S31, is at least one of the following conditions:

[138] receiving a handover command from the base station that instructs the remote UE to handover to the target relay UE; or

[139] determining, based on a sidelink parameter between the remote UE and the target relay UE, the fact that a specified condition for performing a handover to the target relay UE is met.

[140] In one example, the command to perform a handover is a reconfiguration message sent by the base station, wherein the reconfiguration message contains indication information indicating to the remote UE the need to perform a handover to the target relay UE.

[141] In one example, the sidelink parameter between the remote UE and the target relay UE is: the quality of the sidelink channel between the remote UE and the target relay UE.

[142] The specified condition for performing handover to the target relay UE is as follows: the quality of the sidelink channel between the remote UE and the target relay UE exceeds a specified threshold.

[143] In one embodiment of the present invention, the condition for performing handover that is satisfied by the serving cell of the target relay UE, which is determined in step S31, is at least one of the following conditions:

[144] the serving cell of the target relay UE is the same as the serving cell of the remote UE;

[145] the serving cell of the target relay UE is the same as the declared serving cell of the target relay UE that was handed over by the remote UE to the base station; or

[146] The serving cell of the target relay UE is included in the cell list.

[147] In one example, the remote UE maintains the target relay UE's declared serving cell that was handed over to the base station.

[148] In one example, before performing step S31, the proposed method further comprises: receiving a list of cells from a base station, wherein the list of cells is associated with a target relay UE, and different target relay UEs are associated with different lists of cells. The list of cells includes one or more cells.

[149] In the embodiments of the present invention, a handover initiation condition to a target relay UE is set for the remote UE, and if the handover initiation condition to the target relay UE is met, it is determined whether the serving cell of the target relay UE satisfies the handover execution condition. Handover to the target relay UE is performed only if the handover execution condition is met, in order to avoid failures in handover by the remote UE that may be caused by a change in the serving cell of the relay UE, thereby improving the stability of the wireless communication system.

[150] Embodiments of the present invention provide a method for performing handover to a relay UE by a remote UE. This method for performing handover to a relay UE includes performing the steps described below.

[151] At step S1-1, handover to the target relay UE is not performed due to the fact that it is determined that the serving cell of the target relay UE does not satisfy the condition for performing handover while meeting the condition for initiating handover to the target relay UE.

[152] At step S2-1, information is transmitted to the base station indicating that the remote UE has not performed handover to the target relay UE.

[153] In one embodiment of the present invention, the information indicating that handover to the target relay UE has not been performed comprises at least one of the following elements: an identifier of the target relay UE or an identifier of the serving cell of the target relay UE.

[154] In the embodiments of the present invention, a condition for initiating a handover to a target relay UE is set for the remote UE. If the condition for initiating a handover to the target relay UE is met, it is determined whether the serving cell of the target relay UE satisfies the condition for performing the handover. If the condition for performing the handover is not met, the handover to the target relay UE is not performed, and information indicating that the handover to the target relay UE is not performed is transmitted to the base station so that the base station can learn in time that the remote UE has not performed the handover to the target relay UE. Based on the received information, the base station performs reasonable further operations on network control.

[155] Embodiments of the present invention provide a method for performing handover to a relay UE by a remote UE. This method for performing handover to a relay UE includes performing the steps described below.

[156] At stage S1, handover to the target relay UE is not performed due to the fact that it is established that the serving cell of the target relay UE does not satisfy the condition for performing handover while meeting the condition for initiating handover to the target relay UE.

[157] At stage S2, information is transmitted to the base station indicating that the handover to the target relay UE has not been completed.

[158] At stage S3, another handover command is received from the base station, instructing it to perform handover to another relay UE other than the target relay UE.

[159] In one embodiment of the present invention, the information indicating that handover to the target relay UE has not been performed includes at least one of the following elements: an identifier of the target relay UE or an identifier of the serving cell of the target relay UE.

[160] In the embodiments of the present invention, a condition for initiating a handover to a target relay UE is set for the remote UE. If the condition for initiating a handover to the target relay UE is met, it is determined whether the serving cell of the target relay UE satisfies the condition for performing the handover. If the condition for performing the handover is not met, the handover to the target relay UE is not performed, and information indicating that the handover to the target relay UE is not performed is transmitted to the base station so that the base station can learn in time that the remote UE has not performed the handover to the target relay UE. Thereafter, based on this information, the base station may reasonably assign another relay UE to the remote UE and transmit a new handover command to the remote UE so that the remote UE can perform handover to the required relay UE.

[161] Embodiments of the present invention provide a method for performing handover to a relay UE by a remote UE. This method for performing handover to a relay UE includes performing the steps described below.

[162] At stage S1, handover to the target relay UE is not performed due to the fact that it is established that the serving cell of the target relay UE does not satisfy the condition for performing handover while meeting the condition for initiating handover to the target relay UE.

[163] At stage S2, an RRC (Radio Resource Control) channel reestablishment message is transmitted to the target relay UE.

[164] Embodiments of the present invention provide a method for performing a handover to a relay UE that is implemented by a remote UE. This method for performing a handover to a relay UE includes performing the steps described below.

[165] At stage S1, handover to the target relay UE is not performed due to the fact that it is established that the serving cell of the target relay UE does not satisfy the condition for performing handover while meeting the condition for initiating handover to the target relay UE.

[166] At stage S2, a request to restore the radio resource control channel is initiated.

[167] Initiating a request to restore a radio resource control channel means initiating the remote UE to start the following process: initiating the restoration of an RRC (Radio Resource Control) channel for communication with a target relay UE; or sending a request to the target relay UE to initiate the target relay UE to start the following process: initiating the restoration of an RRC (Radio Resource Control) channel for communication with the remote UE.

[168] Embodiments of the present invention provide a method for performing a handover to a relay UE that is implemented by a remote UE. This method for performing a handover to a relay UE includes performing the steps described below.

[169] At stage S1, handover to the target relay UE is not performed due to the fact that it is established that the serving cell of the target relay UE does not satisfy the condition for performing handover while meeting the condition for initiating handover to the target relay UE.

[170] At stage S2, at least one of the following operations is performed:

[171] canceling a handover command related to the target relay UE; or canceling a specified condition for performing handover to the target relay UE.

[172] In embodiments of the present invention, it is provided that when a condition for initiating a handover to a target relay UE is met, but it is determined that the serving cell of the target relay UE does not satisfy the condition for performing the handover, the handover to the target relay UE is not performed, and the corresponding command for performing the handover and/or the specified condition for performing the handover to the target relay UE is canceled. This means that the remote UE does not use an autonomous mechanism for handover to the target relay UE, but instead uses a mechanism in which the command for performing the handover is sent by the base station.

[173] Embodiments of the present invention provide a method for performing handover to a relay UE, which is implemented by a network device. Fig. 4 is a flow chart illustrating a method for performing handover to a relay UE according to one embodiment of the present invention. As shown in Fig. 4, the proposed method for performing handover to a relay UE includes performing the step described below.

[174] At step S41, information is received from the remote UE indicating that the handover to the target relay UE has not been performed.

[175] In one embodiment of the present invention, information indicating that handover to the target relay UE has not been performed is determined by the remote UE based on the serving cell of the target relay UE.

[176] In one embodiment of the present invention, information indicating that handover to the target relay UE has not been performed is determined by the remote UE based on the serving cell of the target relay UE.

[177] In one embodiment of the present invention, the information indicating that handover to the target relay UE has not been performed includes at least one of the following elements: an identifier of the target relay UE or an identifier of the serving cell of the target relay UE.

[178] In embodiments of the present invention, it is provided that when a remote UE determines that a handover to a target relay UE is necessary, the remote UE makes a decision on whether to perform a handover to the target relay UE based on a serving cell of the target relay UE. In other words, the serving cell of the target relay UE is used as a reference parameter for determining whether to perform a handover, in order to avoid failures in performing a handover by the remote UE that may be caused by a change in the serving cell of the relay UE, and when the remote UE decides not to perform a handover to the target relay UE.

[179] Embodiments of the present invention provide a method for performing handover to a relay UE. This method is implemented by a network device. Fig. 5 is a flow chart illustrating a method for performing handover to a relay UE according to one embodiment of the present invention. As shown in Fig. 5, the method for performing handover to a relay UE includes performing the steps described below.

[180] At step S51, information transmitted by the remote UE indicating that handover to the target relay UE has not been performed is received.

[181] At step S52, a handover command is transmitted to the remote UE indicating the need to perform a handover to another relay UE other than the target relay UE.

[182] In one embodiment of the present invention, information indicating that handover to the target relay UE has not been performed is determined by the remote UE based on the serving cell of the target relay UE.

[183] In one embodiment of the present invention, information indicating that handover to the target relay UE has not been performed is determined by the remote UE based on determining that the serving cell of the target relay UE does not satisfy the condition for performing handover while meeting the condition for initiating handover to the target relay UE.

[184] Embodiments of the present invention provide a method for performing handover to a relay UE, which is implemented by a network device. This method includes:

[185] sending a list of cells to the remote UE, wherein the list of cells enables the remote UE to determine that the serving cell of the target relay UE satisfies the condition for performing handover, based on the fact that the serving cell of the target relay UE is included in the specified list, and to perform handover to the target relay UE; and

[186] receiving information transmitted by the remote UE indicating that handover to the target relay UE has not been completed.

[187] According to embodiments of the present invention, a network device configures a remote UE to use an autonomous handover mechanism that provides for the remote UE to independently determine whether to perform a handover to a target relay UE and receives information indicating that the handover to the target relay UE has not been performed when the remote UE determines that a condition for performing a handover has not been met.

[188] Embodiments of the present invention provide a method for performing handover to a relay UE, which is implemented by a network device. This method includes:

[189] receiving information transmitted by the remote UE indicating that handover to the target relay UE has not been completed; and

[190] transmitting a handover command instructing the remote UE to perform a handover to the target relay UE.

[191] In embodiments of the present invention, after receiving information transmitted by the remote UE indicating that the handover to the target relay device has not been performed, the network device decides to abandon the use of the autonomous handover mechanism by the remote UE to the target relay UE and to switch to using a mechanism that involves the transmission by the base station of a handover command instructing the remote UE to perform the handover to the target relay UE so that the remote UE can successfully complete the handover.

[192] Embodiments of the present invention provide an apparatus for performing handover to a relay UE. This apparatus is applicable to a remote UE. Fig. 6 is a block diagram illustrating an apparatus for performing handover to a relay UE according to one embodiment of the present invention. As shown in Fig. 6, the apparatus for performing handover to the relay UE includes a determining module 61.

[193] The determining module 61 is configured to determine whether to perform a handover to the target relay UE based on a serving cell of the target relay UE.

[194] In one embodiment, the determining module 61 includes: a determining unit and a data processing unit.

[195] The determining module is configured to determine whether the serving cell of the target relay UE satisfies the condition for performing handover while meeting the condition for initiating handover to the target relay UE.

[196] The data processing unit is configured to perform a handover to the target relay UE subject to the handover implementation condition.

[197] In one embodiment, the data processing unit is configured to not perform a handover to the target relay UE due to non-compliance with the handover implementation condition.

[198] In one embodiment of the present invention, the condition for initiating a handover to the target relay UE is at least one of the following conditions:

[199] receiving a handover command from the base station that instructs the remote UE to handover to the target relay UE; and

[200] determining, based on a sidelink parameter between the remote UE and the target relay UE, the fact that a predetermined condition for performing handover to the target relay UE is met; wherein the predetermined condition is received from the base station.

[201] In one embodiment of the present invention, the sidelink parameter between the remote UE and the target relay UE is: the quality of the sidelink channel between the remote UE and the target relay UE.

[202] The specified condition for performing handover to the target relay UE is as follows: the quality of the sidelink channel between the remote UE and the target relay UE exceeds a specified threshold.

[203] In one embodiment of the present invention, the serving cell of the target relay UE satisfying the conditions for performing handover is at least one of the following cells:

[204] a serving cell of the target relay UE that is the same as the serving cell of the remote UE;

[205] a serving cell of the target relay UE that matches the declared serving cell of the target relay UE that was handed over by the remote UE to the base station; or

[206] a serving cell of the target relay UE included in the cell list.

[207] In one embodiment, the proposed device includes a receiving module.

[208] The receiving module is configured to receive a list of cells from the base station, wherein the list of cells is associated with a target relay UE.

[209] In one embodiment, the proposed device includes a transmitting module.

[210] The transmitting module is configured to perform one of the following operations:

[211] transmitting to the base station information indicating that the remote UE will not perform handover to the target relay UE; or

[212] initiating the restoration of a radio resource control channel for communication with the target relay UE;

[213] The data processing module is configured to perform one of the following operations:

[214] initiating a request to restore the radio resource control channel;

[215] cancellation of the handover command related to the target relay UE;

[216] canceling the specified condition for performing handover to the target relay device UE; or

[217] canceling the handover command related to the target relay UE and the specified condition for performing handover to the target relay UE.

[218] In one embodiment, the proposed device includes: a receiving module.

[219] The receiving module is configured to receive from the base station a command indicating the need to perform a handover to another relay UE other than the target relay UE.

[220] Embodiments of the present invention provide an apparatus for performing handover to a relay UE. This apparatus is applicable to a network device. Fig. 7 is a block diagram illustrating an apparatus for performing handover to a relay UE according to one embodiment of the present invention. As shown in Fig. 7, the apparatus for performing handover to a relay UE includes a receiving module 71.

[221] The receiving module 71 is configured to receive information transmitted by the UE device indicating that handover to the target relay UE has not been performed.

[222] In one embodiment of the present invention, information indicating that handover to the target relay UE has not been performed is determined by the remote UE based on the serving cell of the target relay UE.

[223] In one embodiment of the present invention, information indicating that handover to the target relay UE has not been performed is determined by the remote UE based on the fact that the serving cell of the target relay UE does not satisfy the condition for performing handover while meeting the condition for initiating handover to the target relay UE.

[224] In one embodiment, the proposed device also includes a transmitting module.

[225] The transmitting module is configured to send a list of cells to the remote UE. This list of cells allows the remote UE to determine that the serving cell of the target relay UE satisfies the condition for performing handover, based on the fact that this serving cell of the target relay UE is included in the specified list, and to perform handover to the target relay UE.

[226] In one embodiment, the proposed device also includes a transmitting module.

[227] The transmitting module is configured to transmit a handover command instructing the remote UE to perform a handover to the target relay UE.

[228] Embodiments of the present invention provide a UE device. The UE includes:

[229] processor; and

[230] memory for storing instructions executed by the processor;

[231] wherein the processor is configured to execute executable commands stored in the memory in order to implement methods for performing handover to the relay UE.

[232] Embodiments of the present invention provide a network device. This network device includes:

[233] processor; and

[234] memory for storing instructions executed by the processor;

[235] wherein the processor is configured to execute executable commands stored in the memory in order to implement methods for performing handover to the relay UE.

[236] Embodiments of the present invention provide a non-volatile machine-readable data carrier on which executable instructions are stored, wherein when the processor executes these executable instructions, implementation of methods for performing handover to a relay UE is ensured.

[237] Embodiments of the present invention provide a non-volatile machine-readable data carrier on which executable instructions are stored, wherein when the processor executes these executable instructions, the implementation of methods for performing handover to a relay UE is ensured.

[238] Fig. 8 is a block diagram illustrating a UE 800 according to one embodiment of the present invention. For example, the UE 800 may be a mobile telephone, a computer, a digital broadcast terminal, a message transceiver, a game console, a tablet, a medical device, a training device, a personal digital assistant, or another similar device.

[239] As shown in Fig. 8, the subscriber equipment (UE) 800 may include one or more of the following components: a data 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.

[240] The data processing component 802 typically controls all actions of the UE 800, such as operations related to data display, telephone calls, data exchange, camera operation, and recording. The data processing component 802 may include one or more processors 820 that perform all or some stages of the methods described above. Moreover, the data processing component 802 may include one or more modules that facilitate interaction between the data processing component 802 and other components. For example, the data processing component 802 may include a multimedia module that facilitates interaction between the multimedia component 808 and the data processing component 802.

[241] Memory 804 is configured to store various types of data that support operation of UE 800. Examples of such data include commands for any applications or methods running on UE 800, contact data, phone book data, messages, images, videos, and other similar data. Memory 804 can be implemented using volatile or nonvolatile memory devices of any type or a combination thereof, such as static random access memory (SRAM), electrically erasable programmable read-only memory (EEPROM), erasable programmable read-only memory (EPROM), programmable read-only memory (PROM), read-only memory (ROM), magnetic memory, flash memory, magnetic or optical disk.

[242] Power component 806 supplies electrical power to various components of UE 800. Power component 806 may include a power management system, one or more power sources, and any other elements associated with generating, managing, and distributing power for UE 800.

[243] The multimedia component 808 includes a screen that is an output interface that communicates between the UE 800 and the user. In some embodiments of the present invention, the screen may include a liquid crystal display (LCD) and a touch panel (TP). If the screen includes a touch panel, the screen may be implemented as a touch panel for receiving input signals transmitted by the user. The touch panel includes one or more touch sensors for reading touches and finger movements on the touch panel in various directions. The touch sensor may not only read the boundary of the touch or finger movement on the touch panel, but also read the wake-up time period and pressure associated with the touch or finger movement on the touch panel. In some embodiments of the present invention, the multimedia component 808 includes a front camera and/or a rear camera. When the UE 800 is in an operating mode, such as in photo mode or video mode, the front camera and/or the rear camera may receive external multimedia data. Each camera from the front and rear cameras may have a fixed optical lens system or have the ability to change the focal length and optical zoom.

[244] The audio component 810 is configured to emit and/or receive audio signals. For example, the audio component 810 includes a microphone (MIC) configured to receive an external audio signal when the UE 800 is in an operating mode, such as a call mode, a recording mode, and a voice recognition mode. The received audio signal can then be stored in the memory 804 or transmitted via the communication component 816. In some embodiments of the present invention, the audio component 810 further includes a speaker for emit audio signals.

[245] The input/output (I/O) interface 812 provides interconnection between the data processing component 802 and peripheral interface modules such as a keyboard, a mouse wheel, buttons, etc. These buttons may include, but are not limited to, a return button, a volume control button, a start button, and a lock button.

[246] The sensor component 814 includes one or more sensors for providing an assessment of the state of various aspects of the UE 800. For example, the sensor component 814 may detect an open/closed state of the UE 800 and the relative location of components (e.g., a display and a numeric keypad) of the UE 800. The sensor component 814 may also detect a change in the position of the UE 800 or any component of the UE 800, the presence or absence of contact of the user with the UE 800, the orientation or acceleration/deceleration of the UE 800, and a change in the temperature of the UE 800. The sensor component 814 may include a proximity sensor configured to detect nearby objects without any physical contact with them. The sensor component 814 may also include a light-sensitive sensor, such as a CMOS (complementary metal-oxide-semiconductor) or CCD (charge-coupled device) image sensor, which is used in image processing applications. In some embodiments of the present invention, the sensor component 814 may also include an accelerometer, a gyroscope, a magnetic sensor, a pressure sensor, or a temperature sensor.

[247] The communication component 816 is configured to facilitate communication, both wirelessly and by wire, between the UE 800 and other devices. The UE 800 may access a wireless network using a communication standard such as Wi-Fi (wireless Internet access technology according to the IEEE 802.1 lx standard), 2G (second generation communication standard), or 3G (third generation communication standard), or a combination thereof. In one embodiment of the present invention, the communication component 816 receives a broadcast signal or broadcast information from an external broadcast control system via a broadcast channel. In one embodiment of the present invention, the communication component 816 further includes an NFC (near field communication) module that facilitates communication over short distances. For example, the NFC module can be implemented based on RFID (radio frequency identification) technology, IrDA (Infrared Data Association) technology, UWB (ultra wideband) technology, BT (Bluetooth wireless communication technology) technology and other technologies.

[248] In one embodiment of the present invention, the UE 800 may operate on one or more elements such as an application-specific integrated circuit (ASIC), a digital signal processor (DSP), a digital signal processing device (DSPD), a programmable logic device (PLD), a field programmable gate array (FPGA), a controller, a microcontroller, a microprocessor, or other electronic component to implement the methods described above.

[249] One embodiment of the present invention also provides a non-volatile computer-readable storage medium, such as memory 804, containing instructions that can be executed by processor 820 of subscriber equipment (UE) 800 to implement the above-described methods. For example, the non-volatile computer-readable storage medium may be read-only memory (ROM), random access memory (RAM), compact disc read-only memory (CD-ROM), magnetic tape, floppy disk, optical data storage device, or other similar device.

[250] Fig. 9 is a block diagram of a base station according to some embodiments of the present invention. For example, a base station 900 may be implemented as a network device. As shown in Fig. 9, the base station 900 includes a data processing component 922 that further comprises one or more processors and memory resources represented by a memory 932 for storing instructions executed by the data processing component 922, such as application programs. The application program stored in the memory 932 may include one or more modules, each of which corresponds to a certain set of instructions. In addition, the data processing component 922 is configured to execute instructions for executing any of the above-described methods implemented by the base station.

[251] The base station 900 may further include a power component 926 configured to control the power of the base station 900; a wired or wireless network interface 950 configured to connect the base station 900 to a network; and an input/output (I/O) interface 958. The base station 900 may operate on an operating system stored in the memory 932, such as Windows Server™, Mac OS X™, Unix™, Linux™, FreeBSD™, etc.

[252] Other embodiments of the present invention will become apparent to those skilled in the art upon review of the present description and upon practice of the invention disclosed herein. It is intended that the present invention cover any modifications, uses or adaptations thereto that comply with the general principles of the embodiments of the claimed invention and that incorporate common knowledge in the art not disclosed herein or conventional technical means. It is intended that the present description and examples be illustrative only, and that the true scope and spirit of the disclosed embodiments of the present invention be indicated by the following claims.

[253] It should be understood that the embodiments of the present invention are not limited to the specific structure described above and illustrated in the accompanying drawings, and that various changes and modifications can be made thereto without departing from their scope. It is intended that the scope of the disclosed embodiments of the present invention be limited solely by the appended claims.

[254] Industrial applicability

[255] When the remote UE determines that a handover to the target relay UE is necessary, the remote UE makes a decision on whether to perform a handover to the target relay UE based on a serving cell of the target relay UE. In this case, the serving cell of the target relay UE is used as a reference parameter for determining whether to perform a handover, in order to avoid failures in performing a handover by the remote UE that may be caused by a change in the serving cell of the relay UE, which improves the stability of the wireless communication system.

Claims (53)

1. A method for implementing handover to a relay subscriber equipment (UE), implemented by a remote UE and providing for: deciding whether to perform handover to the target relay UE based on the serving cell of the target relay UE; performing a handover to the target relay UE based on the fact that the handover condition is met by the serving cell of the target relay UE, the serving cell of the target relay UE satisfying the handover condition includes: a serving cell of the target relay UE that matches the declared serving cell of the target relay UE that was transmitted by the remote UE to the network device. 2. The method according to claim 1, wherein prior to deciding whether to perform a handover to the target relay UE based on the serving cell of the target relay UE, the method comprises: receiving a handover command from the network device, which instructs the remote UE to handover to the target relay UE. 3. The method according to claim 1, wherein deciding whether to perform handover to the target relay UE based on the serving cell of the target relay UE comprises: determining whether the serving cell of the target relay UE satisfies the condition for performing handover, based on the fact that the condition for initiating handover to the target relay UE is met. 4. The method according to claim 3, wherein the condition for initiating handover to the target relay UE is at least one of the following conditions: receiving a handover command from the network device that instructs the remote UE to handover to the target relay UE; or determining, based on a sidelink parameter between the remote UE and the target relay UE, the fact that a predetermined condition for performing handover to the target relay UE is met; wherein the predetermined condition is received from the network device. 5. The method according to paragraph 4, wherein: the parameter of the sidelink between the remote UE and the target relay UE is: the quality of the sidelink channel between the remote UE and the target relay UE; and the specified condition for performing handover to the target relay UE provides for the following: the quality of the sidelink channel between the remote UE and the target relay UE exceeds a specified threshold. 6. The method according to any of paragraphs 1-5, additionally providing: failure to perform handover to the target relay UE due to non-compliance with the conditions for performing handover. 7. The method according to paragraph 6, additionally providing for the performance of one of the following operations: transmitting to the network device information indicating that the remote UE is not performing handover to the target relay UE; initiating the restoration of a radio resource control channel for communication with the target relay UE; initiating a request to restore the radio resource control channel; cancellation of the handover command related to the target relay UE; cancellation of the specified condition for performing handover to the target UE relay device; or canceling the handover execution command related to the target relay UE and the specified condition for performing the handover to the target relay UE. 8. The method according to claim 7, which, after transmitting from the network device information indicating that the remote UE has not performed a handover to the target relay UE, further comprises: receiving from the network device another handover command instructing the handover to be performed to a relay UE other than the target relay UE. 9. A method for implementing handover to a relay subscriber equipment (UE), implemented by a network device and providing for: initiating a remote UE to determine the need for a handover to a target relay UE based on the serving cell of the target relay UE, wherein the remote UE is configured to perform a handover to the target relay UE based on the fact that a handover condition is met by the serving cell of the target relay UE, the serving cell of the target relay UE that satisfies the handover condition includes: a serving cell of the target relay UE that matches the declared serving cell of the target relay UE that was transmitted by the remote UE to the network device. 10. The method according to paragraph 9, additionally providing for: transmitting a handover command to the remote UE, instructing the remote UE to perform a handover to the target relay UE, wherein the command to perform the handover is configured to initiate the remote UE to determine the need for a handover to the target relay UE based on the serving cell of the target relay UE. 11. The method according to claim 10, wherein the command to perform a handover further comprises initiating the remote UE to perform one of the following operations in response to the fact that the serving cell of the target relay UE does not meet the handover condition: transmitting to the network device information indicating that the remote UE is not performing handover to the target relay UE; initiating the restoration of a radio resource control channel for communication with the target relay UE; initiating a request to restore the radio resource control channel; cancellation of the handover command related to the target relay UE; cancellation of the specified condition for performing handover to the target UE relay device; or canceling the handover execution command related to the target relay UE and the specified condition for performing the handover to the target relay UE. 12. The method according to paragraph 11, additionally providing for: receiving information from the remote UE indicating that the remote UE does not perform handover to the target relay UE. 13. The method according to claim 12, in which information indicating that handover to the target relay UE has not been performed is determined by the remote UE based on the serving cell of the target relay UE; or information indicating that handover to the target relay UE has not been performed is determined by the remote UE based on the establishment of the fact that the serving cell of the target relay UE does not satisfy the condition for performing handover while meeting the condition for initiating handover to the target relay UE. 14. The method according to any of paragraphs 9-13, additionally providing: transmission from the remote UE of another handover command instructing the handover to be performed to a relay UE other than the target relay UE. 15. A communication device comprising: processor; and memory for storing commands executed by the processor; wherein the processor is configured to execute executable commands stored in the memory for the purpose of implementing the method according to any of paragraphs 1-8. 16. A communication device comprising: a processor; and memory for storing commands executed by the processor; wherein the processor is configured to execute executable commands stored in the memory for the purpose of implementing the method according to any of paragraphs 9-14. 17. A non-volatile machine-readable data carrier on which executable commands are stored, wherein when the processor executes these executable commands, the implementation of the method for performing handover to a relay subscriber device (UE) is ensured according to any of paragraphs 1-8. 18. A non-volatile machine-readable data carrier on which executable commands are stored, wherein when the processor executes these executable commands, the implementation of the method for performing handover to a relay subscriber device (UE) is ensured according to any of paragraphs 9-14.