RU2825017C2 - Method and device for processing communication line failure, as well as terminal device and data medium - Google Patents

Abstract

FIELD: communication equipment.

SUBSTANCE: invention relates to a communication line failure handling method, to a communication line failure handling device, as well as to a terminal device and a data medium. Said result is ensured by determining whether to transmit a first notification message to a remote terminal device depending on a cell, with which the connection is re-established by the relay terminal device. A method for handling a line failure performed by a relay terminal device includes, in response to a communication line failure in the relay terminal device, transmitting a first notification message to a remote terminal device. Communication line failure includes at least one of the following: radio link failure, expiration of timer T310, expiration of timer T312, integrity monitoring error in signaling radio channel (SRB) 1, integrity monitoring error in SRB2, integrity monitoring error in SRB3 or reconfiguration error.

EFFECT: avoiding unnecessary transmission of notifications, which prevents wastage of resources.

20 cl, 11 dwg, 1 tbl

Description

Field of technology

[0001] The present invention relates to the field of communication technology, namely, to a method for handling a communication line failure, to a device for handling a communication line failure, as well as to a terminal device and a data carrier.

Prerequisites for the creation of an invention

[0002] In order to provide direct communication between different sets of subscriber equipment (UE), a sidelink technology was created. The interface between the sets of subscriber equipment (UE) is the PC5 port. Depending on the correspondence between the transmitting UE and the receiving UE, three transmission modes are supported in the sidelink, namely, unicast, multicast, and broadcast.

[0003] The subscriber equipment can communicate with the base station through a repeater by means of another subscriber equipment without having a direct connection with the base station. The subscriber equipment that does not have a connection with the base station is called a remote subscriber equipment, and the subscriber equipment that performs the function of a repeater is called a repeater subscriber equipment. The remote subscriber equipment can communicate with the repeater subscriber equipment through a direct communication link. When the repeater subscriber equipment communicates with the remote subscriber equipment, communication link failures often occur on the side of the repeater subscriber equipment, as a result of which the remote subscriber equipment cannot exchange data with the base station. However, there is no effective means for handling failures on the side of the repeater subscriber equipment.

The essence of the invention

[0004] In embodiments of the present invention, a method for handling a link failure, a device for handling a link failure, a terminal device and a storage medium are provided, which can be applied in 5G/New Radio (NR) systems. After a link failure occurs in a relay terminal device, the relay terminal device notifies a remote terminal device of this, so that the remote terminal device is aware that a link failure has occurred in the relay terminal device corresponding to this remote terminal device, and the remote terminal device can take appropriate actions to handle the link failure in the relay terminal device. For example, the remote terminal device may decide to re-select the repeater based on the said notification or wait for the re-establishment of the connection with the same repeater terminal device, that is, an appropriate processing method may be selected depending on the quality of service (QoS) requirements in the remote terminal device to avoid re-selecting the repeater without a real need, which allows saving resources and preventing their irrational use.

[0005] In a first aspect of the embodiments of the present invention, a method for handling a communication link failure performed by a relay terminal device is proposed. The proposed method includes:

[0006] in response to the occurrence of a communication link failure in the relay terminal device, transmitting a first notification message to the remote terminal device, wherein the communication link failure includes at least one of the following:

[0007] Radio Link Failure; T310 Timer Expiration; T312 Timer Expiration; Signaling Radio Bearer (SRB)1 Integrity Monitoring Error; SRB2 Integrity Monitoring Error; SRB3 Integrity Monitoring Error; or Reconfiguration Error.

[0008] In the proposed technical solution, after a communication link failure occurs in the relay terminal device, the relay terminal device notifies the remote terminal device about it, so that the remote terminal device is aware of the fact that a communication link failure has occurred in the relay terminal device corresponding to this remote terminal device, and the remote subscriber equipment can take appropriate actions to handle the communication link failure in the relay terminal device. For example, the remote terminal device can make a decision to perform a repeater reselection based on the said notification or wait for a re-establishment of a connection with the same relay terminal device, that is, an appropriate processing method can be applied depending on the quality of service (QoS) requirements in the remote terminal device to exclude a repeater reselection without a real need, which allows saving resources and preventing their irrational use.

[0009] In one implementation, transmitting a first notification message to a remote terminal device includes: determining whether to transmit the first notification message to the remote terminal device depending on the cell with which the connection is re-established.

[0010] In one possible implementation, determining whether to transmit a first notification message to a remote terminal device depending on a cell with which a connection has been re-established comprises: receiving a range of areas transmitted by a network device, wherein the range of areas is a list of cells or a list of tracking zones; in response to the relay user equipment performing a re-establishment of a connection with a cell from said range of areas, not performing a transmission of the first notification message to the remote terminal device; and in response to the relay user equipment failing to perform a re-establishment of a connection with a cell from said range of areas, transmitting the first notification message to the remote terminal device.

[0011] In the proposed technical solution, by determining whether to transmit the first notification message to the remote terminal device depending on the cell with which the connection is re-established by the relay terminal device, it is possible to avoid transmitting notifications without a real need, which makes it possible to save resources and prevent their irrational use.

[0012] In one possible implementation, determining whether to transmit a first notification message to a remote terminal device depending on the cell with which the connection is re-established includes: in response to the fact that the cell selected for re-establishing the connection by the relay terminal device is identical to the serving cell before the occurrence of the link failure, not transmitting the first notification message to the remote terminal device; and in response to the fact that the cell selected for re-establishing the connection by the relay terminal device differs from the serving cell before the occurrence of the link failure, transmitting the first notification message to the remote terminal device.

[0013] In the proposed technical solution, by determining whether to transmit the first notification message to the remote terminal device based on whether the cell selected for re-establishing the connection by the relay terminal device is identical to the serving cell before the occurrence of the link failure, it is possible to avoid transmitting notifications without a real need, which makes it possible to save resources and prevent their irrational use.

[0014] In one implementation, transmitting a first notification message to a remote terminal device includes: determining whether to transmit the first notification message to the remote terminal device depending on a configuration from the network device.

[0015] In one implementation, determining whether to transmit a first notification message to a remote terminal device depending on a configuration from a network device includes: receiving first identification information transmitted by the network device, wherein the first identification information is configured to indicate transmission of the first notification message to all remote terminal devices; and determining whether to transmit the first notification message to all remote terminal devices connected to the relay terminal device based on the first identification information.

[0016] In the proposed technical solution, in response to the occurrence of a communication line failure in the relay terminal device, it is determined whether to transmit a notification to all remote terminal devices based on an identifier transmitted by the network device to the relay terminal device. Accordingly, one identifier can be used to indicate the need to transmit a notification, by the relay terminal device, to all remote terminal devices, which makes it possible to improve the processing efficiency, save resources and prevent their irrational use.

[0017] In one implementation, determining whether to transmit a first notification message to a remote terminal device depending on a configuration from a network device includes: receiving a plurality of instances of second identification information transmitted by the network device, wherein each instance of the second identification information is configured to indicate whether to transmit the first notification message to the corresponding remote terminal device; and determining whether to transmit the first notification message to the corresponding remote terminal device based on the plurality of instances of the second identification information transmitted by the network device.

[0018] In the proposed technical solution, in response to the occurrence of a communication line failure in the relay terminal device, it is determined whether to transmit a notification to the corresponding remote terminal devices, based on a plurality of identifiers corresponding to the remote terminal devices transmitted by the network device to the relay terminal device. Accordingly, when using a plurality of identifiers, the relay terminal device transmits a notification only to specific remote relay devices, which makes it possible to exclude the transmission of notifications without real need, and accordingly, to save resources and prevent their irrational use.

[0019] In one implementation, determining whether to transmit a first notification message to a remote terminal device, depending on a configuration from a network device, includes: receiving a QoS requirement transmitted by the network device; in response to the remote terminal device data satisfying the corresponding QoS requirement, transmitting a first notification message to the remote terminal device that satisfies the corresponding QoS requirement; or in response to the remote terminal device data satisfying the corresponding QoS requirement, not transmitting the first notification message to the remote terminal device that satisfies the corresponding QoS requirement.

[0020] In the proposed technical solution, in response to the occurrence of a communication link failure in the relay terminal device, the relay terminal device determines whether to transmit a notification to a remote terminal device that satisfies the corresponding QoS requirement, based on the QoS requirement transmitted by the network device and the data of the remote terminal device. Accordingly, the relay terminal device can apply appropriate processing modes depending on the QoS requirements of the remote terminal device to prevent the transmission of notifications without real need, which also makes it possible to prevent the re-selection of the relay by the remote terminal device without real need.

[0021] In one implementation, the first notification message comprises auxiliary information, wherein the auxiliary information includes at least one of the following: whether a procedure in which a secondary cell group (SCG) restores a master cell group (MCG) has been started; whether the target cell with which the connection is re-established is the same as the serving cell before the link failure occurred; or a failure cause, wherein the failure cause includes at least one of the following: radio link failure; expiration of timer T310; expiration of timer T312; integrity check error in SRB1; integrity check error in SRB2; integrity check error in SRB3; or a reconfiguration error.

[0022] In one implementation, the method further comprises: stopping the transmission of the repeater search message; and/or notifying the upper layer of the occurrence of a communication link failure. This ensures conservation of resources and can prevent their irrational use.

[0023] In one possible implementation, the method further comprises: in response to a successful re-establishment of a Radio Resource Control (RRC) connection by the relay terminal device, transmitting a second notification message to the network device and/or transmitting a notification of a successful re-establishment of the RRC connection to the remote terminal device, wherein the second notification message includes remote terminal devices that remain connected or remote terminal devices with which the connection was broken.

[0024] In one possible implementation, the method further comprises: in response to an unsuccessful re-establishment of the RRC connection by the relay terminal device, transmitting a notification of an error in re-establishing the RRC connection to the remote terminal device.

[0025] In a second aspect of the embodiments of the present invention, another method for handling a communication link failure performed by a remote terminal device is provided. The proposed method includes: receiving a first notification message transmitted by a relay terminal device, wherein the first notification message is transmitted by the relay terminal device in response to the occurrence of a communication link failure in the relay terminal device, and wherein the communication link failure includes at least one of the following:

[0026] Radio Link Failure; Timer T310 Expired; Timer T312 Expired; Integrity Check Error in SRB1; Integrity Check Error in SRB2; Integrity Check Error in SRB3; or Reconfiguration Error.

[0027] In one implementation, the method further comprises: determining whether to continue to maintain a connection with the relay terminal device based on auxiliary information contained in the first notification message, and informing the relay terminal device of the determination result, wherein the auxiliary information comprises at least one of the following: whether a procedure in which the SCG restores the MCG has been started; whether the target cell with which the connection is re-established is the same as the serving cell before the link failure occurred; or a failure cause, wherein the failure cause comprises at least one of the following: radio link failure; expiration of timer T310; expiration of timer T312; integrity check error in SRB1; integrity check error in SRB2; integrity check error in SRB3; or a reconfiguration error.

[0028] In the proposed technical solution, the remote terminal device can be aware of the operations performed by the relay terminal device after the occurrence of a link failure or the cause of the link failure based on the auxiliary information contained in the notification message transmitted by the relay terminal device, so that the remote terminal device can apply an appropriate processing mode based on the auxiliary information to avoid re-selecting the relay without real need.

[0029] In one implementation, the method further comprises: in response to determining that the connection with the relay terminal device should continue to be maintained, terminating the transmission of relayed data to the relay terminal device.

[0030] In the proposed technical solution, the relay terminal device may stop transmitting relay data to the relay terminal device when it is determined that it is necessary to continue maintaining a connection with the relay terminal device, which makes it possible to save resources and avoid their irrational use.

[0031] In one possible implementation, the method further comprises: receiving a notification message about successful re-establishment of the RRC connection by the relay terminal device, transmitted by the relay terminal device; and resuming transmission of the relayed data to the relay terminal device.

[0032] In the proposed technical solution, if a notification message about successful re-establishment of the RRC connection by the relay terminal device transmitted by the relay terminal device is received, the remote terminal device can determine that the re-establishment of the RRC connection by the relay terminal device has been successful. After that, the remote terminal device can resume transmitting the relay data to the relay terminal device and communicate with the network device through the relay terminal device, which ensures normal functioning of the communication in the remote terminal device.

[0033] In one possible implementation, the method further comprises: receiving a RRC connection re-establishment error notification message from the relay terminal device, transmitted by the relay terminal device; disconnecting from the relay terminal device and performing a re-selection of the relay and/or initiating a re-establishment of the connection and/or performing a re-selection of the cell.

[0034] In the proposed technical solution, the remote terminal device is aware that the RRC connection re-establishment by the relay terminal device has failed when the RRC connection re-establishment error notification message transmitted by the relay terminal device is received. After that, the remote terminal device can disconnect from the relay terminal device and decide to perform a repeater re-selection (for example, select another repeater for communication), or initiate a connection re-establishment and wait for the connection re-establishment with the relay terminal device, or perform a cell re-selection, due to which the remote terminal device can apply an appropriate processing mode based on QoS requirements, which makes it possible to avoid a repeater re-selection without a real need.

[0035] In a third aspect of the embodiments of the present invention, a device for handling a communication link failure is proposed. The proposed device is capable of implementing part of the functions, or all of the functions, of the relay terminal device in the method described in the first aspect of the present invention. For example, the device for handling a communication link failure may have the functions of some of, or all of, the embodiments of the present invention, or may have functionality for independently implementing any of the embodiments of the present invention. Such functionality may be implemented using hardware or by executing appropriate software using hardware. Such hardware or software includes one or more units or modules corresponding to the functions described above.

[0036] In one implementation, the device for handling a communication link failure includes: a transmitting and receiving module and a processing module. The processing module is configured to ensure that the device for handling a communication link failure performs the corresponding functions of the method described above. The transmitting and receiving module is configured to provide communication between the device for handling a communication link failure and other devices. The device for handling a communication link failure may further include a storage module connected to the transmitting and receiving module and the processing module, which is configured to store the necessary computer programs and data for the device for handling a communication link failure.

[0037] In one example, the processing module may be a processor. The transmit/receive module may be a transceiver or a communication interface. The storage module may be a memory.

[0038] In a fourth aspect of the embodiments of the present invention, another device for handling a communication link failure is proposed. The proposed device is capable of implementing part of the functions, or all of the functions, of the remote terminal device in the method described in the second aspect of the present invention. For example, the device for handling a communication link failure may have the functions of some of, or all of, the embodiments of the present invention, or may have functionality for independently implementing any of the embodiments of the present invention. Such functionality may be implemented using hardware or by executing appropriate software using hardware. Such hardware or software includes one or more units or modules corresponding to the functions described above.

[0039] In one implementation, the device for handling a communication link failure includes: a transmitting and receiving module and a processing module. The processing module is configured to ensure that the device for handling a communication link failure performs the corresponding functions of the method described above. The transmitting and receiving module is configured to provide communication between the device for handling a communication link failure and other devices. The device for handling a communication link failure may further include a storage module connected to the transmitting and receiving module and the processing module, which is configured to store the necessary computer programs and data for the device for handling a communication link failure.

[0040] In one example, the processing module may be a processor. The transmit/receive module may be a transceiver or a communication interface. The storage module may be a memory.

[0041] According to a fifth aspect of the embodiments of the present invention, a terminal device is provided. The terminal device includes: a processor. When the processor calls the program stored in the memory, the above-described method is performed according to the first aspect of the present invention.

[0042] According to a sixth aspect of the embodiments of the present invention, a terminal device is provided. The terminal device includes: a processor. When the processor calls the program stored in the memory, the above-described method is performed according to the second aspect of the present invention.

[0043] According to a seventh aspect of the embodiments of the present invention, a terminal device is provided. The terminal device includes: a processor and a memory having a computer program stored therein. When the processor executes the computer program stored in the memory, the terminal device is provided with the above-described method according to the first aspect of the present invention.

[0044] According to an eighth aspect of the embodiments of the present invention, a terminal device is provided. The terminal device includes: a processor and a memory having a computer program stored therein. When the processor executes the computer program stored in the memory, the terminal device is enabled to perform the above-described method according to the eighth aspect of the present invention.

[0045] According to a ninth aspect of the embodiments of the present invention, a terminal device is provided. The terminal device includes: a processor and an interface circuit. The interface circuit is configured to receive code instructions and transmit the code instructions to the processor. The processor is configured to execute the code instructions to ensure that the terminal device performs the above-described method in accordance with the first aspect of the present invention.

[0046] According to a tenth aspect of the embodiments of the present invention, a terminal device is provided. The terminal device includes: a processor and an interface circuit. The interface circuit is configured to receive code instructions and transmit the code instructions to the processor. The processor is configured to execute the code instructions to ensure that the terminal device performs the above-described method according to the second aspect of the present invention.

[0047] According to an eleventh aspect of the present invention, a communication system is provided. The system includes: a device for handling a communication link failure according to the third aspect of the present invention, or a device for handling a communication link failure according to the fourth aspect of the present invention, or a terminal device according to the fifth aspect of the present invention, or a terminal device according to the sixth aspect of the present invention, or a terminal device according to the seventh aspect of the present invention, or a terminal device according to the eighth aspect of the present invention, or a terminal device according to the ninth aspect of the present invention, or a terminal device according to the tenth aspect of the present invention.

[0048] According to a twelfth aspect of the present invention, embodiments thereof provide a machine-readable medium that has instructions stored thereon that are used in the terminal device described above. When these instructions are executed, the terminal device is provided with the method according to the first aspect of the present invention.

[0049] According to a thirteenth aspect of the present invention, embodiments thereof provide a computer-readable medium that has instructions stored thereon that are used in the network device described above. When these instructions are executed, the network device is provided with the method according to the second aspect of the present invention.

[0050] According to a fourteenth aspect of the present invention, embodiments of the present invention provide a computer program product comprising a computer program. When said computer program is executed on a computer, the computer is provided with the method according to the first aspect of the present invention.

[0051] According to a fifteenth aspect of the present invention, embodiments of the present invention provide a computer program product comprising a computer program. When said computer program is executed on a computer, the computer is provided with the method according to the second aspect of the present invention.

[0052] According to a sixteenth aspect of the present invention, embodiments of the present invention provide a computer program. When said computer program is executed on a computer, the computer is enabled to execute the method according to the first aspect of the present invention.

[0053] According to a seventeenth aspect of the present invention, embodiments of the present invention provide a computer program. When said computer program is executed on a computer, the computer is provided with the method according to the second aspect of the present invention.

Brief description of the drawings

[0054] To illustrate in detail the technical solutions proposed in the embodiments of the present invention, as well as to describe existing technologies, a description of the corresponding attached drawings is given below.

[0055] Fig. 1 is a block diagram illustrating a communication system in accordance with one embodiment of the present invention.

[0056] Fig. 2 is a flow chart of a method for handling a communication link failure in accordance with one embodiment of the present invention.

[0057] Fig. 3 is a flow chart of another method for handling a communication link failure in accordance with one embodiment of the present invention.

[0058] Fig. 4 is a flow chart of another method for handling a communication link failure in accordance with one embodiment of the present invention.

[0059] Fig. 5 is a flow chart of another method for handling a communication link failure in accordance with one embodiment of the present invention.

[0060] Fig. 6 is a flow chart of another method for handling a communication link failure in accordance with one embodiment of the present invention.

[0061] Fig. 7 is a structural block diagram illustrating an apparatus for handling a communication link failure according to one embodiment of the present invention.

[0062] Fig. 8 is a structural block diagram illustrating another apparatus for handling a communication link failure according to one embodiment of the present invention.

[0063] Fig. 9 is a structural block diagram illustrating another apparatus for handling a communication link failure according to one embodiment of the present invention.

[0064] Fig. 10 is a structural block diagram illustrating another apparatus for handling a communication link failure according to one embodiment of the present invention.

[0065] Fig. 11 is a structural block diagram illustrating a terminal device according to one embodiment of the present invention.

Detailed description of the invention

[0066] Embodiments of the present invention will be discussed in more detail below with reference to the accompanying drawings, where the same or similar elements are designated by similar reference numerals throughout the description. The embodiments of the present invention discussed below with reference to the accompanying drawings are provided solely by way of example for the purpose of explaining the present invention and should not be considered as limiting the present invention.

[0067] To begin with, in order to provide a better understanding of the method for handling a communication link failure according to the embodiments of the present invention, a communication system used in the embodiments of the present invention will be discussed below.

[0068] Fig. 1 is a block diagram illustrating a communication system according to one embodiment of the present invention. The communication system may include, but is not limited to, a network device and a plurality of terminal devices. A terminal device in said plurality of terminal devices that is not connected to the network device is called a remote terminal device, and a terminal device that performs the functions of a repeater is called a repeater terminal device, wherein the remote terminal device communicates with the repeater terminal device over a direct communication link. The number and types of devices shown in Fig. 1 are purely illustrative and do not impose limitations on embodiments of the present invention, and in practice two or more network devices and two or more terminal devices may be used. The communication system shown in Fig. 1 may include, for example, a network device 101, a repeater terminal device 102, and a remote terminal device 103.

[0069] It should be noted that the technical solutions according to the embodiments of the present invention can be applied to various communication systems, for example, in a long term evolution (LTE) system, a 5th generation (5 ^th generation) mobile communication system, a 5G New Radio (NR) system, or other new future mobile communication systems.

[0070] The network device 101 in the embodiments of the present invention is an entity on the network side for receiving or transmitting signals. For example, the network device 101 may be an evolved NodeB (eNB), a transmission reception point (TRP), a next generation NodeB (gNB) in a New Radio (NR) system, a base station in other, future mobile communication systems, or an access point in a WiFi (wireless fidelity) system. The embodiments of the present invention are not limited in terms of specific technologies and specific types of the network device. The network device according to the embodiments of the present invention is composed of a central unit (CU) and a distributed unit (DU). The central unit, CU, may also be called a control unit. The use of a central and distributed unit (CU-DU) structure allows the protocol layers in a network device, such as a base station, to be separated: some of the protocol layer functions are placed in the central unit (CU) for centralized control, and the remaining protocol layer functions, or some of them, are placed in a distributed unit (DU) that is largely controlled by the central unit (CU).

[0071] A terminal device (for example, a relay terminal device 102 and a remote terminal device 103) in the embodiments of the present invention is an entity on the subscriber side for receiving or transmitting signals, for example, a cellular telephone. A terminal device may also be called a terminal, a user equipment (UE), a mobile station (MS), a mobile terminal (MT), etc. The terminal device may be a vehicle with communication functions, an intelligent vehicle, a mobile phone, a wearable device, a tablet computer, a computer with wireless transceiver functions, a virtual reality (VR) terminal device, an augmented reality (AR) terminal device, a wireless terminal device in an industrial control system, a wireless terminal device in an unmanned vehicle, a wireless terminal device in a remote surgery system, a wireless terminal device in an intelligent power grid, a wireless terminal device in a transport security system, a wireless terminal device in a smart city system, a wireless terminal device in a smart home system, etc. Embodiments of the present invention are not limited in terms of specific technologies and specific types of the terminal device used.

[0072] It should be understood that the communication system illustrated in the embodiments of the present invention is provided to explain the technical solutions proposed in the embodiments of the present invention and does not impose any limitations on the proposed technical solutions. It should be obvious to those skilled in the art that with the development of system architectures and the emergence of new commercial application scenarios, the technical solutions proposed in the embodiments of the present invention can also be applied to solve similar technical problems.

[0073] A method for handling a communication line failure, an apparatus for handling a communication line failure, a terminal device and a storage medium according to the present invention will be explained in more detail below with reference to the accompanying drawings.

[0074] Referring to Fig. 2, which is a flow chart of a method for handling a link failure in accordance with one embodiment of the present invention. It should be noted that this method for handling a link failure in accordance with embodiments of the present invention may be performed by a relay terminal device. According to the illustration of Fig. 2, the method for handling a link failure may include the following steps, but is not limited to them.

[0075] In step S201, in response to the occurrence of a communication link failure in the relay terminal device, a first notification message is transmitted to the remote terminal device.

[0076] In embodiments of the present invention, the link failure includes, but is not limited to, any of the following: a radio link failure; a T310 timer expiration; a T312 timer expiration; an integrity check error in SRB1; an integrity check error in SRB2; an integrity check error in SRB3; or a reconfiguration error.

[0077] It should be noted that during the 3GPP RAN2 group meetings and discussions, many companies proposed to introduce a fast recovery mechanism after radio link failure (RLF) based on the T312 timer in Release 12 (Rel-12) of the LTE standard to further reduce service outages and switching failures due to RLF failures in New Radio, NR, and LTE systems. The operation of the T312 timer in the LTE system is illustrated in Table 1. The introduction of the T312 timer allows the terminal device to announce the RLF failure earlier, due to which the RRC connection re-establishment procedure can be initiated earlier, and accordingly, the service outage time is significantly reduced. If the T310 timer is running, it means that the downlink quality of the terminal device is currently insufficient, and the initiation of a measurement report (e.g., an A3 event) indicates with a high probability that the terminal device has found a suitable target cell, and the network device will issue a handover command to the terminal device depending on the measurement results in the terminal device. However, due to the current downlink quality problems in the terminal device, there is a high probability that the terminal device will not be able to accept the handover command from the network device, which will result in an RLF failure. If the T312 timer were missing, the terminal device would have to wait for the T310 timer to expire before it initiates the RRC connection re-establishment procedure and RRC connection recovery. The service outage time in the terminal device can be reduced by introducing the T312 timer, in the presence of which the RRC connection re-establishment procedure can be initiated after the expiration of the T312 timer, which allows the terminal device to announce the RLF failure earlier and to start the RRC connection re-establishment procedure earlier.

[0078] Thus, in embodiments of the present invention, the relay terminal device may determine whether a link failure has occurred by monitoring whether an RLF failure has occurred, whether a T310 timer has expired, whether a T312 timer has expired, whether an integrity check error is present in SRB1, SRB2 or SRB3, or whether a reconfiguration error is present. The relay terminal device notifies the remote terminal device when it is determined that a link failure has occurred. That is, the relay terminal device transmits a first notification message to the remote terminal device, in the event of any of the situations described above that may be the cause of a link failure, where specific examples are given below for ease of understanding.

[0079] Example 1

[0080] In response to the occurrence of a communication link failure in the relay terminal device, a first notification message is transmitted to the remote terminal device.

[0081] For example, when a network device issues a handover command to a terminal device based on a measurement result in a relay terminal device, the relay terminal device is likely to fail to receive the handover command from the network device due to poor downlink quality of the relay terminal device at the current time, which may result in an RLF failure. In this case, the relay terminal device may transmit a first notification message to the remote terminal device to notify the remote terminal device, as a result of which the remote terminal device will be aware that an RLF failure has occurred in the corresponding relay terminal device, and may perform a corresponding operation based on this notification to handle the RLF failure in the relay terminal device. For example, the remote terminal device may decide, based on the notification, to perform a relay reselection or to wait for a re-establishment of a connection with the relay terminal device. Accordingly, the remote terminal device can apply reasonable processing modes depending on the QoS requirements of the remote terminal device to avoid re-selecting the repeater without real need, which can save resources and avoid their irrational use.

[0082] Example 2

[0083] When timer T310 expires in the relay terminal device, the first notification message is transmitted to the remote terminal device.

[0084] For example, when the relay terminal device performs radio link detection, if the number of desynchronization indicators received successively is N310, the timer T310 is initiated to start. When the timer T310 expires, it is considered that an RLF failure has occurred, and then the relay terminal device transmits the first notification message to the remote terminal device.

[0085] Example 3

[0086] When timer T312 expires in the relay terminal device, the first notification message is transmitted to the remote terminal device.

[0087] For example, if a measurement report is transmitted with a measurement identifier for which a timer T312 is configured, then when the starting condition of the timer T312 is satisfied, the timer T312 is started. If the conditional handover is not initiated before the timer T312 expires, it is determined that an RLF failure has occurred in the relay terminal device after the timer T312 expires, and then the relay terminal device transmits the first notification message to the remote terminal device.

[0088] Example 4

[0089] When an integrity control error is present in SRB1 of the relay terminal device, the first notification message is transmitted to the remote terminal device.

[0090] Example 5

[0091] When an integrity control error is present in SRB2 of the relay terminal device, the first notification message is transmitted to the remote terminal device.

[0092] Example 6

[0093] When an integrity control error is present in SRB3 of the relay terminal device, the first notification message is transmitted to the remote terminal device.

[0094] That is, when there is an integrity check error in SRB1, SRB2 or SRB3 of the relay terminal device, it is necessary to perform the initialization of the RRC connection re-establishment procedure, that is, it means that a link failure has occurred in the relay terminal device. At this time, the relay terminal device transmits the first notification message to the remote terminal device.

[0095] Example 7

[0096] When a reconfiguration error is present in the relay terminal device, a first notification message is transmitted to the remote terminal device.

[0097] For example, in response to an RRC reconfiguration error in a relay terminal device, the relay terminal device may notify a remote terminal device thereof, whereby the remote terminal device is informed, by said notification, that a link failure has occurred in the corresponding relay terminal device.

[0098] In one implementation, the first notification message may comprise auxiliary information. In embodiments of the present invention, the auxiliary information may include, but is not limited to, at least one of the following: whether a procedure in which the SCG restores the MCG has been started; whether the target cell with which the connection is re-established is the same as the serving cell before the link failure occurred; or a failure reason, where the failure reason includes, but is not limited to, any of the following: RLF; T310 timer expiration; T312 timer expiration; integrity check error in SRB1; integrity check error in SRB2; integrity check error in SRB3; or a reconfiguration error.

[0099] By implementing the embodiments of the present invention, the remote terminal device can be aware, by means of a notification transmitted by the user terminal, that a link failure has occurred in the corresponding relay terminal device, and the remote terminal device can perform appropriate operations based on the notification to handle the link failure in the relay terminal device. For example, the remote terminal device can decide to perform a relay reselection based on the notification or wait for a connection re-establishment with the same relay terminal device, that is, an appropriate processing method can be applied depending on the QoS requirements of the remote terminal device to avoid a relay reselection without a real need, which makes it possible to save resources and prevent their waste.

[00100] It should be noted that the relay terminal device may determine whether to notify the remote terminal device depending on the cell with which the connection is re-established. For example, refer to Fig. 3, which is a flow chart of a method for handling a link failure according to one embodiment of the present invention. It should be noted that this method for handling a link failure according to the embodiments of the present invention can be performed by the relay terminal device. According to the illustration of Fig. 3, the method for handling a link failure may include the following steps, but is not limited thereto.

[00101] In step S301, in response to the occurrence of a communication link failure in the relay terminal device, it is determined whether to transmit the first notification message to the remote terminal device depending on the cell with which the connection is re-established.

[00102] In embodiments of the present invention, the communication link failure includes, but is not limited to, at least one of the following: RLF; T310 timer expiration; T312 timer expiration; SRB1 integrity check error; SRB2 integrity check error; SRB3 integrity check error; or a reconfiguration error. Several examples are given below illustrating when the first notification message is transmitted to a remote terminal device.

[00103] Example 1

[00104] In response to the occurrence of an RLF failure in the relay terminal device, it is determined whether to transmit the first notification message to the remote terminal device, depending on the cell with which the connection is re-established.

[00105] Example 2

[00106] When the T310 timer expires in the relay terminal device, it is determined whether to transmit the first notification message to the remote terminal device, depending on the cell with which the connection is re-established.

[00107] Example 3

[00108] When the timer T312 expires in the relay terminal device, it is determined whether to transmit the first notification message to the remote terminal device, depending on the cell with which the connection is re-established.

[00109] Example 4

[00110] When an integrity control error is present in SRB1 of the relay terminal device, it is determined whether to transmit the first notification message to the remote terminal device depending on the cell with which the connection is re-established.

[00111] Example 5

[00112] When an integrity control error is present in SRB2 of the relay terminal device, it is determined whether to transmit the first notification message to the remote terminal device depending on the cell with which the connection is re-established.

[00113] Example 6

[00114] When an integrity control error is present in SRB3 of the relay terminal device, it is determined whether to transmit the first notification message to the remote terminal device depending on the cell with which the connection is re-established.

[00115] Example 7

[00116] When a reconfiguration error is present in the relay terminal device, it is determined whether to transmit the first notification message to the remote terminal device depending on the cell with which the connection is re-established.

[00117] It should be noted that in the embodiments of the present invention, after a link failure occurs in the relay terminal device, the relay terminal device initiates a connection re-establishment, wherein the connection re-establishment may be performed in the original cell or in a neighboring cell. The relay terminal device according to the embodiments of the present invention determines whether to transmit the first notification message to the remote terminal device depending on the selected cell with which the connection is re-established. Below are two different examples illustrating the implementation in which the relay terminal device determines whether to transmit the first notification message to the remote terminal device depending on the cell with which the connection is re-established.

[00118] In one possible implementation, the relay terminal device determines whether to transmit a first notification message to the remote terminal device, depending on the cell with which the connection is re-established, by the following method: receiving a range of areas transmitted by the network device, wherein the range of areas is a list of cells or a list of tracking areas (TA); in response to the relay terminal device performing a connection re-establishment within said range of areas, not performing the transmission of the first notification message to the remote terminal device; and in response to the relay terminal device failing to perform a connection re-establishment within said range of areas, transmitting the first notification message to the remote terminal device.

[00119] For example, a network device (for example, a base station) can transmit a range of areas to a relay terminal device, and the relay terminal device can determine whether a connection with a cell from this range of areas will be re-established. The relay terminal device does not notify the remote terminal device if the relay terminal device performs a connection re-establishment with a cell within this range of areas. If the relay terminal device does not perform a connection re-establishment with a cell from said range of areas, the relay terminal device notifies the remote terminal device. Accordingly, the relay terminal device determines whether to transmit the first notification message to the remote terminal device depending on the cell with which the relay terminal device has re-established a connection, and this makes it possible to avoid transmitting notifications without a real need, which makes it possible to save resources and prevent their inefficient use.

[00120] In one possible implementation, the relay terminal device determines whether to transmit a first notification message to the remote terminal device, depending on the cell with which the connection is re-established, in the following way: in response to the fact that the cell selected for re-establishing the connection by the relay terminal device is identical to the serving cell before the occurrence of the link failure, not transmitting the first notification message to the remote terminal device; and in response to the fact that the cell selected for re-establishing the connection by the relay terminal device differs from the serving cell before the occurrence of the link failure, transmitting the first notification message to the remote terminal device.

[00121] That is, when the cell selected for connection re-establishment by the relay terminal device is the same as the serving cell before the occurrence of the link failure, the relay terminal device does not notify the remote terminal device. When the cell selected for connection re-establishment by the relay terminal device is different from the serving cell before the occurrence of the link failure, the relay terminal device notifies the remote terminal device. Accordingly, the relay terminal device determines whether to transmit the first notification message to the remote terminal device depending on whether the cell selected for connection re-establishment by the relay terminal device is the same as the serving cell before the occurrence of the link failure, and this makes it possible to avoid transmitting notifications unnecessarily, which makes it possible to save resources and prevent their waste.

[00122] It should be noted that, in response to the occurrence of a link failure in the relay terminal device, the relay terminal device may determine whether to notify the remote terminal device depending on the configuration of the network device. For example, refer to Fig. 4, which is a flow chart of a method for handling a link failure according to one embodiment of the present invention. It should be noted that this method for handling a link failure according to the embodiments of the present invention can be performed by the relay terminal device. According to the illustration of Fig. 4, the method for handling a link failure may include the following steps, but is not limited thereto.

[00123] In step S401, in response to the occurrence of a communication link failure in the relay terminal device, it is determined whether to transmit the first notification message to the remote terminal device depending on the configuration from the network device.

[00124] In embodiments of the present invention, the communication link failure includes, but is not limited to, at least one of the following: RLF; expiration of timer T310; expiration of timer T312; integrity check error in SRB1; integrity check error in SRB2; integrity check error in SRB3; or reconfiguration error.

[00125] Below are several examples illustrating the cases in which the first notification message is transmitted to the remote terminal device.

[00126] Example 1

[00127] In step S401, in response to the occurrence of an RLF failure in the relay terminal device, it is determined whether to transmit the first notification message to the remote terminal device depending on the configuration from the network device.

[00128] Example 2

[00129] When the T310 timer in the relay terminal device expires, it is determined whether to transmit the first notification message to the remote terminal device, depending on the configuration from the network device.

[00130] Example 3

[00131] When the T312 timer in the relay terminal device expires, it is determined whether to transmit the first notification message to the remote terminal device, depending on the configuration from the network device.

[00132] Example 4

[00133] When an integrity control error is present in SRB1 of the relay terminal device, it is determined whether to transmit the first notification message to the remote terminal device depending on the configuration from the network device.

[00134] Example 5

[00135] When an integrity control error is present in SRB2 of the relay terminal device, it is determined whether to transmit the first notification message to the remote terminal device depending on the configuration from the network device.

[00136] Example 6

[00137] When an integrity control error is present in SRB3 of the relay terminal device, it is determined whether to transmit the first notification message to the remote terminal device depending on the configuration from the network device.

[00138] Example 7

[00139] When the reconfiguration of the relay terminal device fails, it is determined whether to transmit the first notification message to the remote terminal device depending on the configuration from the network device.

[00140] It should be noted that in embodiments of the present invention, the network device (for example, the base station) configures an identifier used to indicate whether the relay terminal device should transmit a notification to all remote terminal devices, or an identifier(s) used to indicate to which of the remote terminal devices the relay terminal device should transmit a notification. The following are examples that illustrate various implementations of the step of determining whether to transmit the first notification message to the remote terminal device, depending on the configuration of the network device.

[00141] As one example of possible implementations, determining by a relay terminal device whether to transmit a first notification message to a remote terminal device depending on a configuration from a network device includes: receiving first identification information transmitted by the network device, wherein the first identification information is configured to indicate the transmission of the first notification message to all remote terminal devices; and determining whether to transmit the first notification message to all remote terminal devices connected to the given relay terminal device based on the first identification information.

[00142] For example, a network device (for example, a base station) can transmit an identifier (i.e., the first identification information described above) to a relay terminal device. The relay terminal device determines, based on the first identification information, whether to transmit the first notification information to all remote terminal devices that have a connection with this relay terminal device. That is, the relay terminal device determines, based on the identifier transmitted by the network device, whether to transmit a notification to all remote terminal devices. Therefore, in the proposed technical solution, when a communication link failure occurs in the relay terminal device, it is determined based on the identifier transmitted by the network device to the relay terminal device whether to transmit a notification to all remote terminal devices. Accordingly, one identifier can be used to indicate the need to transmit a notification by a relay terminal device to all remote terminal devices, which allows for increased processing efficiency, saving resources and preventing their irrational use.

[00143] As another example of possible implementations, determining whether to transmit a first notification message to a remote terminal device depending on a configuration from a network device includes: receiving a plurality of instances of second identification information transmitted by the network device, wherein each instance of the second identification information is configured to indicate whether to transmit the first notification message to the corresponding remote terminal device; and determining whether to transmit the first notification message to the corresponding remote terminal device based on the plurality of instances of the second identification information transmitted by the network device.

[00144] For example, the network device may transmit a plurality of identifiers (that is, the above-described second identification information) corresponding to the remote terminal devices to the relay terminal device, wherein each of the identifiers is used to indicate whether to transmit a notification to the corresponding remote terminal device, as a result of which the relay terminal device can determine whether to transmit a notification to the corresponding remote terminal devices depending on the plurality of identifiers transmitted by the network device. Accordingly, when using a plurality of identifiers, the relay terminal device can transmit notifications only to specific remote relay devices, which makes it possible to avoid transmitting notifications without a real need, and accordingly, to save resources and avoid their irrational use.

[00145] As another example of possible implementations, determining, by a relay terminal device, whether to transmit a first notification message to a remote terminal device, depending on a configuration from a network device, includes: receiving a QoS requirement transmitted by the network device; in response to the fact that the data of the remote terminal device meets the corresponding QoS requirement, transmitting a first notification message to the remote terminal device that meets the corresponding QoS requirement; or in response to the fact that the data of the remote terminal device meets the corresponding QoS requirement, not transmitting the first notification message to the remote terminal device that meets the corresponding QoS requirement. The QoS can be controlled by a quasi co-location indicator (QCL) and a packet delay budget.

[00146] For example, the network device may transmit a QoS requirement to the relay terminal device. When the data of the remote terminal device meets the corresponding QoS requirement, the relay terminal device transmits a first notification message to the corresponding remote user equipment, UE. Or, when the data of the remote terminal device meets the corresponding QoS requirement, the relay terminal device does not transmit the first notification message to the corresponding remote terminal device. Accordingly, when a link failure occurs in the relay terminal device, the relay terminal device determines, depending on the QoS requirement transmitted by the network device and the data of the remote terminal device, whether to transmit a notification to the remote terminal device that meets the corresponding QoS requirement. Depending on the QoS requirement of the remote terminal device, a suitable processing mode can be selected, which allows avoiding the transmission of redundant notifications by the relay terminal device, and accordingly, eliminating the re-selection of the relay by the relay terminal device without real need.

[00147] In one implementation, the method for handling a link failure according to embodiments of the present invention further includes: stopping the transmission of a repeater discovery message after the occurrence of a link failure. For example, the relay terminal device may notify an upper layer of the occurrence of a link failure after it has occurred. The upper layer stops transmitting the repeater discovery message after receiving a notification of the link failure, which allows saving resources and avoiding their waste.

[00148] In one possible implementation, the method for handling a communication link failure according to embodiments of the present invention further comprises: in response to a successful re-establishment of the RRC connection with the relay terminal device, transmitting a second notification message to the network device and/or transmitting a notification of a successful re-establishment of the RRC connection to the remote terminal device, wherein the second notification message includes the remote terminal device(s) that remains connected or the remote terminal device(s) with which the connection has been broken.

[00149] That is, the relay terminal device notifies the network device (for example, the base station) of the state(s) of the remote terminal device(s) after the RRC connection is successfully re-established. The notification includes the remote terminal device(s) that are/are still connected or the remote terminal device(s) that have lost the connection, and thus the network device can be informed of which of the remote terminal devices remain connected or which of the remote terminal devices have lost the connection. For example, the relay terminal device may transmit a connection re-establishment success notification to the remote terminal device after the RRC connection is successfully re-established, as a result of which the remote terminal device may be informed that the RRC connection re-establishment with the relay terminal device was successful, and may resume transmission of relay data to the relay terminal device to ensure normal communication for the remote terminal device.

[00150] As another example, the relay terminal device may transmit a second notification message to the network device after a successful re-establishment of the RRC connection, and transmit a notification of a successful re-establishment of the RRC connection to the remote terminal device. Accordingly, the network device may be aware of which of the remote terminal devices are still connected and which of the remote terminal devices have lost the connection, and the remote terminal devices may be informed that the re-establishment of the RRC connection with the relay terminal device was successful, and may resume transmission of the relayed data to the relay terminal device, which makes it possible to ensure normal communication for the remote terminal device.

[00151] In one possible implementation, the method for handling a communication link failure according to the embodiments of the present invention further comprises: in response to an unsuccessful re-establishment of the RRC connection with the relay terminal device, transmitting an RRC connection re-establishment error notification to the remote terminal device. Accordingly, the remote terminal device can be aware that the re-establishment of the RRC connection with the relay terminal device was unsuccessful, and then the remote terminal device disconnects from the relay terminal device and performs a re-selection of the relay, and/or initiates a re-establishment of the connection, and/or performs a re-establishment of the cell, as a result of which the remote terminal device can select an appropriate processing mode depending on the QoS requirement, which makes it possible to avoid an unnecessary re-selection of the relay.

[00152] In embodiments of the present invention, another method for handling a link failure is also provided. The implementation of this method for handling a link failure will be discussed below from the point of view of a remote terminal device. Refer to Fig. 5, which is a flow chart of a method for handling a link failure according to one embodiment of the present invention. It should be noted that this method for handling a link failure according to embodiments of the present invention can be performed by a remote terminal device. According to the illustration of Fig. 5, the method for handling a link failure may include the steps described below, but is not limited to them.

[00153] In step S501, a first notification message transmitted by the relay terminal device is received, wherein in embodiments of the present invention, the first notification message is transmitted by the relay terminal device in response to the occurrence of a communication link failure in the relay terminal device.

[00154] That is, the relay terminal device transmits a first notification message to the remote terminal device in response to the occurrence of a communication link failure in the relay terminal device. The remote terminal device receives the first notification message from the relay terminal device using communication on a forward link. The communication link failure includes, but is not limited to, at least one of the following: RLF; expiration of timer T310; expiration of timer T312; integrity check error in SRB1; integrity check error in SRB2; integrity check error in SRB3; or a reconfiguration error.

[00155] That is, the relay terminal device transmits the first notification message to the remote terminal device, in the event of any of the situations described above that may be the cause of the communication link failure, and for ease of understanding, specific examples are given below.

[00156] Example 1

[00157] In response to the occurrence of an RLF failure in the relay terminal device, a first notification message is transmitted to the remote terminal device.

[00158] For example, when a network device issues a handover command to a relay terminal device based on a measurement result in the relay terminal device, the relay terminal device is likely to fail to receive the handover command from the network device due to poor downlink quality of the relay terminal device, which may result in an RLF failure. In this case, the relay terminal device may transmit a first notification message to the remote terminal device to notify the remote terminal device, as a result of which the remote terminal device will be aware, based on this notification, that an RLF has occurred in the corresponding relay terminal device, and can perform a corresponding operation based on this notification to handle the RLF failure in the relay terminal device. For example, the remote terminal device may decide to perform repeater reselection based on the said notification or wait for the reconnection with the same repeater terminal device to be reestablished, that is, an appropriate processing method may be applied depending on the QoS requirements of the remote terminal device to avoid repeater reselection without real need, which allows saving resources and preventing their irrational use.

[00159] Example 2

[00160] When timer T310 expires in the relay terminal device, the first notification message is transmitted to the remote terminal device.

[00161] For example, when the relay terminal device performs radio link detection, if the number of desynchronization indicators received successively is N310, the timer T310 is initiated to start. When the timer T310 expires, it is considered that an RLF failure has occurred, and then the relay terminal device transmits the first notification message to the remote terminal device.

[00162] Example 3

[00163] When timer T312 expires in the relay terminal device, the first notification message is transmitted to the remote terminal device.

[00164] For example, if a measurement report is transmitted with a measurement identifier for which a timer T312 is configured, then when the start condition of the timer T312 is satisfied, the timer T312 is started. If a conditional handover is not initiated before the timer T312 expires, then after the timer T312 expires, it is determined that an RLF failure has occurred in the relay terminal device. At this point, the relay terminal device transmits the first notification message to the remote terminal device.

[00165] Example 4

[00166] When an integrity control error is present in SRB1, the first notification message is transmitted to the remote terminal device.

[00167] Example 5

[00168] When an integrity control error is present in SRB2, the first notification message is transmitted to the remote terminal device.

[00169] Example 6

[00170] When an integrity control error is present in SRB3, the first notification message is transmitted to the remote terminal device.

[00171] That is, when there is an integrity control error in SRB1, SRB2 or SRB3 of the relay terminal device, it is necessary to perform the initialization of the RRC connection re-establishment procedure, that is, it means that a link failure has occurred in the relay terminal device. After that, the relay terminal device transmits the first notification message to the remote terminal device.

[00172] Example 7

[00173] When the reconfiguration of the relay terminal device is unsuccessful, a first notification message is transmitted to the remote terminal device.

[00174] For example, in response to an RRC reconfiguration error in a relay terminal device, the relay terminal device may notify a remote terminal device thereof, whereby the remote terminal device is informed, by said notification, that a link failure has occurred in the corresponding relay terminal device.

[00175] It should be noted that the relay terminal device determines whether to notify the remote terminal device depending on the cell with which the connection is re-established. In one example of a possible implementation, the relay terminal device determines whether to transmit a first notification message to the remote terminal device depending on the cell with which the connection is re-established by: receiving a range of areas transmitted by the network device, wherein the range of areas is a list of cells or a list of tracking areas (TA); in response to the relay terminal device re-establishing a connection with a cell from said range of areas, not transmitting the first notification message to the remote terminal device, and in response to the relay terminal device failing to re-establish a connection with a cell from said range of areas, transmitting the first notification message to the remote terminal device.

[00176] In one example of another possible implementation, determining, by the relay terminal device, whether to transmit a first notification message to the remote terminal device, depending on the cell with which the connection is re-established, includes: in response to the fact that the cell selected for re-establishing the connection by the relay terminal device is identical to the serving cell before the occurrence of the link failure, not transmitting the first notification message to the remote terminal device; and in response to the fact that the cell selected for re-establishing the connection by the relay terminal device is different from the serving cell before the occurrence of the link failure, transmitting the first notification message to the remote terminal device.

[00177] It should be noted that when a communication link failure occurs in the relay terminal device, the relay terminal device can determine whether to notify the remote terminal device depending on the configuration from the network device. As another example of possible implementations, determining, by the relay terminal device, whether to transmit a first notification message to the remote terminal device depending on the configuration from the network device includes: receiving first identification information transmitted by the network device, wherein the first identification information is configured to indicate transmission of the first notification message to all remote terminal devices; and determining whether to transmit the first notification message to all remote terminal devices connected to this relay terminal device based on the first identification information.

[00178] As another example of possible implementations, determining, by a relay terminal device, whether to transmit a first notification message to a remote terminal device, depending on a configuration from a network device, includes: receiving a plurality of instances of second identification information transmitted by the network device, wherein each instance of the second identification information is configured to indicate whether to transmit the first notification message to the corresponding remote terminal device; and determining whether to transmit the first notification message to the corresponding remote terminal device, based on the plurality of instances of the second identification information transmitted by the network device.

[00179] As another example of possible implementations, determining, by a relay terminal device, whether to transmit a first notification message to a remote terminal device, depending on a configuration from a network device, includes: receiving a QoS requirement transmitted by the network device; in response to the fact that the data of the remote terminal device meets the corresponding QoS requirement, transmitting a first notification message to the remote terminal device that meets the corresponding QoS requirement; or in response to the fact that the data of the remote terminal device meets the corresponding QoS requirement, not transmitting the first notification message to the remote terminal device that meets the corresponding QoS requirement. The QoS can be controlled using a QCL and a packet delay budget.

[00180] By implementing the embodiments of the present invention, when the remote terminal device receives the first notification message transmitted by the relay terminal device after the occurrence of a communication link failure, the remote terminal device can be timely informed of the occurrence of a communication link failure in the corresponding relay terminal device, so that the remote terminal device can timely apply an appropriate processing mode, which ensures normal communication for the remote terminal device and makes it possible to avoid re-selecting a relay without real need.

[00181] It should be noted that the first notification message transmitted by the relay terminal device to the remote terminal device may contain auxiliary information. Thus, the remote terminal device, after receiving the first notification message, can determine whether it should maintain a connection with the connection with the relay terminal device. For example, refer to Fig. 6, which is a flow chart of a method for handling a link failure according to one embodiment of the present invention. It should be noted that this method for handling a link failure according to the embodiments of the present invention can be performed by a remote terminal device. According to the illustration of Fig. 6, the method for handling a link failure may include the following steps, but is not limited thereto.

[00182] At step 601, a first notification message transmitted by a relay terminal device is received, wherein the first notification message is transmitted by the relay terminal device in response to the occurrence of a communication link failure in the relay terminal device, and wherein the communication link failure includes at least one of the following:

[00183] RLF; T310 timer expired; T312 timer expired; SRB1 integrity check error; SRB2 integrity check error; SRB3 integrity check error; or reconfiguration error.

[00184] Step S601 may be implemented in any of the embodiments of the present invention as appropriate, without limiting the embodiments of the present invention in this regard, and the description of these embodiments of the invention will not be repeated.

[00185] In step S602, it is determined whether to continue to maintain a connection with the relay terminal device based on the auxiliary information contained in the first notification message, and the relay terminal device is informed of the determination result.

[00186] In some embodiments of the present invention, the auxiliary information includes at least one of the following: whether a procedure in which the SCG restores the MCG has been started; whether the target cell with which the connection is re-established is the same as the serving cell before the link failure occurred; or a failure cause, where the failure cause includes at least one of the following: radio link failure; expiration of timer T310; expiration of timer T312; integrity check error in SRB1; integrity check error in SRB2; integrity check error in SRB3; or a reconfiguration error.

[00187] In embodiments of the present invention, the remote terminal device, after receiving the first notification message transmitted by the relay terminal device after the occurrence of a communication link failure, determines whether to continue to maintain a connection with the relay terminal device depending on the auxiliary information contained in the first notification message. If the remote terminal device decides to continue to maintain a connection with the relay terminal device, the remote terminal device notifies the relay terminal device of the decision to maintain the connection, and as a result, the relay terminal device can be aware that the remote terminal device maintains a connection with the relay terminal device. If the remote terminal device decides to disconnect from the relay terminal device based on the auxiliary information contained in the first notification message, the remote terminal device disconnects from the relay terminal device and notifies the relay terminal device when disconnecting from the relay terminal device, as a result of which the relay terminal device can be aware that the remote terminal device has disconnected from this relay terminal device.

[00188] By implementing embodiments of the present invention, the remote terminal device, based on the auxiliary information from the notification message transmitted by the relay terminal device, can be aware of the operations performed after the occurrence of a link failure in the relay terminal device or the causes of the link failure, as a result of which the remote terminal device can select an appropriate processing mode depending on the auxiliary information, which makes it possible to avoid re-selecting the relay without real need.

[00189] In one implementation, the method for handling a communication link failure according to embodiments of the present invention further comprises: in response to a determination by the remote terminal device that the connection with the relay terminal device should be continued, stopping the transmission of relayed data to the relay terminal device. In the proposed technical solution, the relay terminal device can stop the transmission of relayed data to the relay terminal device when it is determined that the connection with the relay terminal device should be continued, which allows for saving resources and avoiding their irrational use.

[00190] In one possible implementation, the method for handling a communication link failure according to the embodiments of the present invention further comprises: receiving, by the remote terminal device, a notification message about successful re-establishment of the RRC connection by the relay terminal device transmitted by the relay terminal device; and resuming the transmission of the relay data to the relay terminal device. In the proposed technical solution, the remote terminal device can determine that the re-establishment of the RRC connection with the relay terminal device has been completed successfully when the notification message about successful re-establishment of the RRC connection by the relay terminal device transmitted by the relay terminal device is received. In this case, the remote terminal device can resume the transmission of the relay data to the relay terminal device and communicate with the network device through the relay terminal device, which ensures the normal functioning of the communication in the remote terminal device.

[00191] In one possible implementation, the method for handling a communication link failure according to the embodiments of the present invention further comprises: receiving a message about an RRC connection re-establishment error by the relay terminal device transmitted by the relay terminal device; disconnecting from the relay terminal device and performing a relay re-selection and/or initiating a connection re-establishment and/or performing a cell re-selection. In the proposed technical solution, the remote terminal device, after receiving the notification about an RRC connection re-establishment error by the relay terminal device transmitted by the relay terminal device, is aware that the RRC connection re-establishment by the relay terminal device has failed. In this case, the remote terminal device can disconnect from the relay terminal device and perform relay reselection, that is, select another relay for communication, or initiate connection reestablishment and wait for connection reestablishment with the relay terminal device, or perform cell reselection. In this way, the remote terminal device can select an appropriate processing method depending on the QoS requirements, which makes it possible to avoid relay reselection without real need.

[00192] In the above-described embodiments of the present invention, the methods according to the embodiments of the invention are discussed from the point of view of a relay terminal device and a remote terminal device, respectively. In order to implement all the functions described above in the methods according to the embodiments of the present invention, the relay terminal device and the remote terminal device may comprise hardware structures and software modules, and any of the functions described above may be implemented by hardware structures, software modules, or a combination of hardware structures and software modules. Each individual function described above may be performed by hardware structures, software modules, or a combination of hardware structures and software modules.

[00193] Referring to Fig. 7, which is a structural block diagram illustrating a device 70 for handling a communication link failure according to one embodiment of the present invention. It should be noted that the device 70 for handling a communication link failure may be a terminal device (for example, a relay terminal device in the above-described embodiments of the present invention), a device included in a terminal device, or a device capable of being used together with a terminal device.

[00194] The device 70 for processing a communication link failure illustrated in Fig. 7 may comprise a transmitting/receiving module 701. The transmitting/receiving module 701 may include a transmitting module and/or a receiving module. The transmitting module is configured to implement transmitting functions, and the receiving module is configured to implement receiving functions. The transmitting/receiving module 701 may implement the transmitting module and/or the receiving module.

[00195] In embodiments of the present invention, the transmitting/receiving module 701, in response to the occurrence of a communication link failure in the relay terminal device, is configured to transmit a first notification message to the remote terminal device, wherein the communication link failure includes at least one of the following: RLF; expiration of timer T310; expiration of timer T312; integrity check error in SRB1; integrity check error in SRB2; integrity check error in SRB3; or a reconfiguration error.

[00196] In one implementation, transmitting, by the transceiver module 701, a first notification message to a remote terminal device includes: determining whether to transmit the first notification message to the remote terminal device depending on the cell with which the connection is re-established.

[00197] In one possible implementation, determining, by the transmitting/receiving module 701, whether to transmit a first notification message to the remote terminal device depending on the cell with which the connection is re-established, includes: receiving a range of areas transmitted by the network device, wherein the range of areas is a list of cells or a list of tracking areas (TA); in response to the relay user equipment performing a re-establishment of the connection with a cell from said range of areas, not transmitting the first notification message to the remote terminal device; and in response to the relay user equipment performing a re-establishment of the connection with a cell from said range of areas, not transmitting the first notification message to the remote terminal device;

[00198] In one possible implementation, determining, by the transmitting/receiving module 701, whether to transmit a first notification message to the remote terminal device, depending on the cell with which the connection is re-established, includes: in response to the fact that the cell selected for re-establishing the connection by the relay terminal device is identical to the serving cell before the occurrence of the link failure, not transmitting the first notification message to the remote terminal device; and in response to the fact that the cell selected for re-establishing the connection by the relay terminal device differs from the serving cell before the occurrence of the link failure, transmitting the first notification message to the remote terminal device.

[00199] In one implementation, transmitting, by the transmitting/receiving module 701, a first notification message to a remote terminal device includes: determining whether to transmit the first notification message to the remote terminal device depending on a configuration from the network device.

[00200] In one implementation, determining, by the transmitting/receiving module 701, whether to transmit a first notification message to a remote terminal device, depending on a configuration from the network device, includes: receiving first identification information transmitted by the network device, wherein the first identification information is configured to indicate the transmission of the first notification message to all remote terminal devices; and determining whether to transmit the first notification message to all remote terminal devices connected to the given relay terminal device, based on the first identification information.

[00201] In one implementation, determining, by the transmitting/receiving module 701, whether to transmit the first notification message to the remote terminal device, depending on the configuration from the network device, includes: receiving a plurality of instances of the second identification information transmitted by the network device, wherein each instance of the second identification information is configured to indicate whether to transmit the first notification message to the corresponding remote terminal device; and determining whether to transmit the first notification message to the corresponding remote terminal device, based on the plurality of instances of the second identification information transmitted by the network device.

[00202] In one implementation, determining, by the transmitting/receiving module 701, whether to transmit the first notification message to the remote terminal device, depending on the configuration from the network device, includes: receiving a QoS requirement transmitted by the network device; in response to the fact that the data of the remote terminal device satisfies the corresponding QoS requirement, transmitting the first notification message to the remote terminal device that satisfies the corresponding QoS requirement; or in response to the fact that the data of the remote terminal device satisfies the corresponding QoS requirement, not transmitting the first notification message to the remote terminal device that satisfies the corresponding QoS requirement.

[00203] In one implementation, the first notification message contains auxiliary information, wherein the auxiliary information includes at least one of the following: whether a procedure in which the SCG restores the MCG has been started; whether the target cell with which the connection is re-established is the same as the serving cell before the link failure occurred; or a failure cause, wherein the failure cause includes at least one of the following: RLF; expiration of timer T310; expiration of timer T312; integrity check error in SRB1; integrity check error in SRB2; integrity check error in SRB3; or a reconfiguration error.

[00204] In one possible implementation, in accordance with the illustration of Fig. 8, the device 80 for handling a communication link failure may further comprise a processing module 802. The processing module 802 is configured: in response to the occurrence of a communication link failure in the relay terminal device, to stop transmitting a repeater discovery message; and/or to notify an upper layer about the occurrence of a communication link failure. The module 801 in Fig. 8 and the module 701 in Fig. 7 have a similar structure and functions.

[00205] In one possible implementation, the first transmitting/receiving module is further configured: in response to a successful re-establishment of the RRC connection with the relay terminal device, to transmit a second notification message to the network device and/or to transmit a notification of a successful re-establishment of the RRC connection to the remote terminal device, wherein the second notification message includes the remote terminal device(s) that remains connected, or the remote terminal device(s) with which the connection has been broken.

[00206] In one possible implementation, the first transmit/receive module is further configured: in response to an unsuccessful re-establishment of the RRC connection with the relay terminal device, to transmit a notification of the RRC connection re-establishment error to the remote terminal device.

[00207] In the device proposed in the above-described embodiments of the present invention, the modules performing the corresponding operations operate in accordance with the principles described in detail in the embodiments of the corresponding method. Their description will not be repeated here.

[00208] Fig. 9 is a structural block diagram illustrating a device 90 for handling a communication link failure according to one embodiment of the present invention. It should be noted that the device 90 for handling a communication link failure may be a terminal device (for example, a remote terminal device in the above-described embodiments of the present invention), a device included in a terminal device, or a device capable of being used together with a terminal device.

[00209] The device 90 for processing a communication link failure illustrated in Fig. 9 may comprise a transmitting/receiving module 901. The transmitting/receiving module 901 may include a transmitting module and/or a receiving module. The transmitting module is configured to implement transmitting functions, and the receiving module is configured to implement receiving functions. The transmitting/receiving module 901 may implement the transmitting module and/or the receiving module.

[00210] In embodiments of the present invention, the transmitting/receiving module 901 is configured to: receive a first notification message transmitted by a relay terminal device, wherein the first notification message is transmitted by the relay terminal device in response to the occurrence of a link failure in the relay terminal device, and wherein the link failure includes at least one of the following: RLF; expiration of timer T310; expiration of timer T312; integrity check error in SRB1; integrity check error in SRB2; integrity check error in SRB3; or a reconfiguration error.

[00211] In one possible implementation, according to the illustration of FIG. 10, the device 100 for handling a link failure may further comprise a processing module 1002. The processing module 1002 is configured to: determine whether to continue to maintain a connection with the relay terminal device based on the auxiliary information contained in the first notification message. The transceiver module 1001 is configured to: inform the relay terminal device of a result of the determination, wherein the auxiliary information includes at least one of the following: whether a procedure in which the SCG restores the MCG has been started; whether the target cell with which the connection is re-established is the same as the serving cell before the occurrence of the link failure; or a failure cause, wherein the failure cause includes at least one of the following: RLF; expiration of timer T310; expiration of timer T312; integrity check error in SRB1; integrity check error in SRB2; integrity check error in SRB3; or reconfiguration error. Module 1001 in Fig. 10 and module 901 in Fig. 9 have similar structure and functions.

[00212] In one implementation, the processing module 1002 is configured: in response to determining that a connection with the relay terminal device should continue to be maintained, to stop transmitting relayed data to the relay terminal device.

[00213] In one possible implementation, the transmitting/receiving module 1001 is configured to: receive a notification message about a successful re-establishment of the RRC connection by the relay terminal device, transmitted by the relay terminal device; and to resume transmission of the relayed data to the relay terminal device.

[00214] In one possible implementation, the transmitting/receiving module 1001 is configured to: receive a RRC connection re-establishment error notification message from the relay terminal device transmitted by the relay terminal device; The processing module 1002 is configured to: disconnect from the relay terminal device and perform a repeater re-selection and/or initiate a connection re-establishment and/or perform a cell re-selection.

[00215] In the device proposed in the above-described embodiments of the present invention, the modules performing the corresponding operations operate in accordance with the principles described in detail in the embodiments of the corresponding method. Their description will not be repeated here.

[00216] Fig. 11 is a structural block diagram illustrating a terminal device 1100 according to one embodiment of the present invention. The terminal device 1100 may be a terminal device (for example, a relay terminal device in the above-described method embodiments), a remote terminal device in the above-described method embodiments, or a chip, a chip-based system, or a processor that helps the terminal device perform the above-described methods. The terminal device may be used to implement the methods that are described in the above-described method embodiments with reference to the description of the above-described method embodiments of the present invention.

[00217] The terminal device 1100 may include one or more processors 1101. The processor 1101 may be a general-purpose processor or a special-purpose processor, such as a baseband processor and a central processor. The baseband processor is used to process communication protocols as well as transmitted data. The central processor is used to control the communication device (for example, a base station, a baseband chip, a terminal device, a chip in a terminal device, a distributed unit DU, or a central unit CU).

[00218] In some examples, the terminal device 1100 may include one or more memory units 1102, on which computer programs may be stored. The processor 1101 executes the computer programs 1104 to ensure that the terminal device 1100 performs the methods described in the above embodiments of the present invention related to the methods. Or, data may also be stored in the memory 1102. The terminal device 1100 and the memory 1102 may be implemented separately or may be integrated with each other.

[00219] In some examples, the terminal device 1100 may also include a transceiver 1105 and an antenna 1106. The transceiver 1105 may be called a transceiver unit, a transceiver device, or a transceiver circuit that implements a transceiver function. The transceiver 1105 may include a receiver and a transmitter. The receiver may be called a receiver or a receiver circuit that implements a reception function. The transmitter may be called a transmitter or a transmitter circuit that implements a transmission function.

[00220] In some examples, the terminal device 1100 may also include one or more interface circuits 1107. The interface circuits 1107 are used to receive code instructions and transmit them to the processor 1101. The processor 1101 executes the code instructions, causing the terminal device 1100 to perform the methods described in the embodiments of the present invention related to the methods.

[00221] The terminal device 1100 may be a relay terminal device from the embodiments of the method discussed above. The transceiver 1105 is used to perform step S201 in Fig. 2, step S301 in Fig. 3 and step S401 in Fig. 4. The processor 1101 is used to perform the steps of stopping transmission of the repeater discovery message after the occurrence of a communication link failure and/or the steps of notifying an upper layer about the occurrence of a communication link failure.

[00222] The terminal device 1100 may be a remote terminal device from the above-described embodiments of the present invention related to the methods. The transceiver 1105 is used to perform step S501 in Fig. 5, step S601 in Fig. 6, the steps of receiving a notification message about a successful re-establishment of the RRC connection by the relay terminal device transmitted by the relay terminal device and resuming the transmission of the relay data to the relay terminal device, as well as the step of receiving an error message about re-establishing the RRC connection in the relay terminal device transmitted by the relay terminal device. The processor 1101 is used to perform step S602 in Fig. 6, a step of stopping transmission of relay data to the relay terminal device in response to determining that a connection with the relay terminal device should be continued, and a step of disconnecting from the relay terminal device and performing relay reselection and/or initiating connection re-establishment and/or performing cell reselection.

[00223] In one implementation, the processor 1101 may include a transceiver for implementing reception and transmission functions. Such a transceiver may be, for example, a transceiver circuit, an interface, or an interface circuit. The transceiver circuit, interface, or interface circuit for implementing reception and transmission functions may be separate from each other or may be integrated with each other. The transceiver circuit, interface, or interface circuit described above may be used to read and write codes or data, or may be used to transmit, or deliver, signals.

[00224] In one implementation, the computer program 1103 may be stored in the processor. When the computer program 1103 is executed on the processor 1101, the terminal device 1100 is enabled to perform the methods described in the above embodiments of the present invention related to the methods. The computer program 1103 may be hard-coded in the processor 1101, and in such a case, the processor 1101 may be implemented using hardware.

[00225] In one implementation, the terminal device 1100 may include electronic circuits. These circuits may implement the functions of transmitting, receiving, or communicating in the above-described embodiments of the present invention related to the methods. The processor and transceiver described in this document may be implemented on integrated circuits (IC), analog integrated circuits, radio frequency integrated circuits (RFIC), mixed-signal integrated circuits, application specific integrated circuits (ASICs), printed circuit boards (PCBs), and electronic devices. The processor and transceiver can be manufactured using various integrated circuit manufacturing technologies, such as complementary metal oxide semiconductor (CMOS), n-channel metal oxide semiconductor (NMOS), positive channel metal oxide semiconductor (PMOS), bipolar junction transistor (BJT), bipolar CMOS (BiCMOS), silicon germanium (SiGe), gallium arsenide (GaAs), etc.

[00226] The terminal device in the above description of the embodiments of the present invention may be a network device or a terminal device (for example, a relay terminal device or a remote terminal device in the above embodiments of the present invention related to methods), however, the terminal devices in the present invention are not limited to only these listed devices, and the structure of the terminal device is not limited to that shown in Fig. 11. The terminal device may be a stand-alone device or a part of a larger device. For example, the described terminal device may be:

[00227] (1) a separate integrated circuit, microcircuit, system or subsystem on microcircuits;

[00228] (2) a set of integrated circuits that includes one or more integrated circuits. In some examples, the set of integrated circuits may also include memory components for storing data and computer programs;

[00229] (3) ASIC, such as a modem;

[00230] (4) a module that is built into other devices;

[00231] (5) a receiver, a terminal device, an intelligent terminal device, a cellular telephone, a wireless device, a portable device, a mobile unit, an on-board device of a vehicle, a network device, an artificial intelligence device; or

[00232] (6) another device.

[00233] Those skilled in the art will understand that the various logical blocks and examples illustrated in the embodiments of the present invention may be implemented using electronic hardware, computer software, or a combination of both. Whether a function is implemented using hardware or software depends on the specific application and design requirements of the overall system. Those skilled in the art may use various methods to implement the necessary functions in each specific application, but no implementation thereof can be considered as limiting the scope of legal protection of the embodiments of the present invention.

[00234] In embodiments of the present invention, a system for handling a communication link failure is also provided. The proposed system includes devices for handling a communication link failure shown in Fig. 7 and Fig. 8 and acting as a relay terminal device in the above-described embodiments of the present invention related to methods, and devices for a communication link failure shown in Fig. 9 and Fig. 10 and acting as a remote terminal device in the above-described embodiments of the present invention related to methods. Or the system may include a terminal device shown in Fig. 11 and acting as a relay terminal device in the above-described embodiments of the present invention related to methods.

[00235] The present invention also provides a computer-readable medium that has instructions stored thereon. When these instructions are executed by a computer, the functionality is implemented in accordance with any of the embodiments of the method described above.

[00236] The present invention also provides a computer program product. When the computer program product is executed by a computer, the functionality is implemented in accordance with any of the embodiments of the method described above.

[00237] The embodiments of the present invention described above may be implemented, in whole or in part, in software, hardware, firmware, or any combination thereof. When implemented using software, the embodiments of the present invention described above may be implemented, in whole or in part, in the form of a computer program product. The computer program product includes one or more computer programs. When loaded and executed on a computer, the computer program implements all or part of the procedures and functions described in the embodiments of the present invention. Such a computer may be a general-purpose computer, a special-purpose computer, a computer network, or another programmable device. The computer program may be stored on a computer-readable storage medium or transmitted from one computer-readable storage medium to another computer-readable storage medium. For example, a computer program may be transmitted from one website, computer, server or data center to another website, computer, server or data center by wired communication (e.g., coaxial cables, optical fiber or digital subscriber lines (DSL)) or by wireless communication (e.g., infrared waves, radio waves or microwave signals). A computer-readable storage medium may be any suitable medium that can be accessed by a computer or a storage device, such as a server into which one or more suitable media are embedded, or a data center. The said suitable medium may be magnetic (e.g., a floppy disk, a hard disk or a tape), optical (e.g., a high-density digital video disc (DVD)), or a semiconductor medium (e.g., a solid-state disk (SSD).

[00238] Those skilled in the art will understand that “first,” “second,” and other numerals in this description are used solely for convenience of distinction, but not to limit the scope of an embodiment of the present invention, and not to indicate an order of precedence.

[00239] The expression "at least one" in the present document may be understood as "one or more", and the expression "a plurality" may mean two, three, four or more, without limiting the present invention in this regard. In the embodiments of the present invention, with respect to the types of technical features, the expressions "first", "second" and "third", as well as "A", "B", "C" or "D" are used to distinguish technical features of the same type, while when the expressions "first", "second" and "third", as well as "A", "B", "C" or "D" are used to describe a technical feature, this does not indicate either the order of precedence or the magnitude.

[00240] The correspondences shown in the tables in this document may be configurable or may be predetermined. The values of the information in the tables are provided solely for example and may be configured to be equal to other values, without limiting the present invention in this regard. When configuring the correspondence between the information and the parameters, it is not necessarily required that all of the correspondences illustrated in the tables be configured. For example, the correspondences shown in some of the rows of the tables in this document may not be configured. As another example, the tables shown above may be adjusted as needed, such as split, combined, etc. The parameters in the headers of the tables shown above may have other names recognized by the network device, and the parameters may also have other values or representation forms recognized by the network device. All of the above tables can also be implemented using other data structures, such as arrays, queues, containers, stacks, linear tables, pointers, chained lists, trees, graphs, structures, classes, unordered arrays (heaps), or hash tables.

[00241] The expression "predetermined" as used herein may be understood as defined, set in advance, stored, pre-stored, pre-agreed upon, pre-configured, hard-coded, or initially specified.

[00242] Those skilled in the art will understand that the steps of the algorithms in the various examples discussed in connection with the embodiments of the present invention proposed in this document may be implemented in the form of electronic hardware or by means of computer software in combination with electronic hardware. The implementation of these functions in the form of hardware or software depends on the requirements of a particular application and the design limitations imposed on the technical solutions. Those skilled in the art may use different methods of implementing the described functions in each particular application, but it should be understood that such implementations fall within the scope of legal protection of the present invention.

[00243] Those skilled in the art should understand that for convenience and brevity of description, specific functional procedures in the systems, devices and units described above are not repeated. For their description, reference should be made to the corresponding procedures in the embodiments of the present invention related to methods.

[00244] Only specific embodiments of the present invention have been discussed above, but its scope is not limited by them. Those skilled in the art can easily find modifications and substitutions for the described invention, but all such modifications and substitutions fall within the scope of the present invention. Accordingly, the scope of the invention is determined by the scope of the appended claims.

Claims (54)

1. A method for handling a communication line failure performed by a relay terminal device and comprising: in response to the occurrence of a communication link failure in the relay terminal device, transmitting a first notification message to the remote terminal device, wherein the first notification message is configured to indicate to the remote terminal device to determine whether to continue to maintain a connection with the relay terminal device, based on auxiliary information contained in the first notification message, and to inform the relay terminal device of the result of the determination, wherein the communication link failure includes at least one of the following: Radio link failure; Timer T310 expired; Timer T312 expired; Integrity check error in signaling radio channel (SRB) 1; Integrity check error in SRB2; Integrity check error in SRB3 or reconfiguration error. 2. The method according to claim 1, wherein transmitting the first notification message to the remote terminal device comprises: determining whether to transmit the first notification message to the remote terminal device, depending on the cell with which the connection is re-established. 3. The method according to claim 2, wherein determining whether to transmit the first notification message to the remote terminal device, depending on the cell with which the connection is re-established, includes: receiving a range of areas transmitted by a network device, wherein the range of areas is a list of cells or a list of tracking zones; in response to the execution, by the relay subscriber equipment, of a re-establishment of a connection with a cell from the said range of areas, failure to transmit the first notification message to the remote terminal device; or in response to the failure of the relay subscriber equipment to re-establish a connection with a cell from the said range of areas, performing the transmission of the first notification message to the remote terminal device. 4. The method according to claim 2, wherein determining whether to transmit the first notification message to the remote terminal device, depending on the cell with which the connection is re-established, includes: in response to the fact that the cell selected for connection re-establishment by the relay terminal device is identical to the serving cell before the link failure occurred, failing to transmit the first notification message to the remote terminal device; or in response to the fact that the cell selected for re-establishing the connection by the relay terminal device is different from the serving cell before the occurrence of the link failure, transmitting a first notification message to the remote terminal device. 5. The method according to claim 1, wherein transmitting the first notification message to the remote terminal device comprises: determine whether to transmit the first notification message to the remote terminal device, depending on the configuration from the network device. 6. The method according to claim 5, wherein determining whether to transmit the first notification message to the remote terminal device depending on the configuration from the network device includes: receiving first identification information transmitted by the network device, wherein the first identification information is configured to indicate transmission of a first notification message to all remote terminal devices; or determining whether to transmit the first notification message to all remote terminal devices connected to the relay terminal device based on the first identification information. 7. The method according to claim 5, wherein determining whether to transmit the first notification message to the remote terminal device depending on the configuration from the network device includes: receiving a plurality of instances of the second identification information transmitted by the network device, wherein each instance of the second identification information is configured to indicate whether to transmit the first notification message to the corresponding remote terminal device; or determining whether to transmit the first notification message to the corresponding remote terminal device based on a plurality of instances of the second identification information transmitted by the network device. 8. The method according to claim 5, wherein determining whether to transmit the first notification message to the remote terminal device depending on the configuration from the network device includes: receiving a quality of service request transmitted by a network device; in response to the remote terminal device data satisfying the relevant quality of service requirement, transmitting a first notification message to the remote terminal device that satisfies the relevant quality of service requirement; or in response to the remote terminal device data satisfying the corresponding quality of service requirement, failing to transmit the first notification message to the remote terminal device that satisfies the corresponding quality of service requirement. 9. The method according to claim 1, wherein the auxiliary information includes at least one of the following: whether the procedure in which the secondary cell group (SCG) re-establishes the primary cell group (MCG) has been started; whether the target cell to which the connection is re-established is the same as the serving cell before the link failure occurred; or a failure reason, wherein the failure reason includes at least one of the following: radio link failure; expiration of timer T310; expiration of timer T312; integrity check error in SRB1; integrity check error in SRB2; integrity check error in SRB3; or reconfiguration error. 10. The method according to any one of paragraphs 1-9, further comprising at least one of the following: stop transmitting the repeater search message; notification of a higher level about the occurrence of a communication line failure. 11. The method according to paragraph 1, also including: in response to a successful re-establishment of a radio resource control (RRC) connection by the relay terminal device, transmitting a second notification message to the network device and/or transmitting a notification of successful re-establishment of the RRC connection to the remote terminal device, wherein the second notification message includes remote terminal devices that remain connected or remote terminal devices with which the connection has been broken; or in response to an unsuccessful re-establishment of the RRC connection with the relay terminal device, transmitting an RRC connection re-establishment error notification to the remote terminal device. 12. A method for handling a communication line failure performed by a remote terminal device and comprising: receiving a first notification message transmitted by a relay terminal device, wherein the first notification message is transmitted by the relay terminal device in response to the occurrence of a communication link failure in the relay terminal device, wherein the communication link failure includes at least one of the following: Radio link failure; Timer T310 expired; Timer T312 expired; Integrity check error in signaling radio channel (SRB)1; Integrity check error in SRB2; Integrity check error in SRB3 or reconfiguration error, wherein the method also includes determining whether to continue maintaining a connection with the relay terminal device based on the auxiliary information contained in the first notification message, and informing the relay terminal device of the result of the determination. 13. The method of claim 12, wherein the auxiliary information includes at least one of the following: whether the procedure in which the SCG restores the MCG has been started; whether the target cell to which the connection is re-established is the same as the serving cell before the link failure occurred; or a failure reason, wherein the failure reason includes at least one of the following: radio link failure; expiration of timer T310; expiration of timer T312; integrity check error in SRB1; integrity check error in SRB2; integrity check error in SRB3; or reconfiguration error. 14. The method according to paragraph 12, also including: in response to determining that the connection with the relay terminal device should continue to be maintained, stopping the transmission of relayed data to the relay terminal device. 15. The method according to paragraph 14, also including: receiving a notification message of successful re-establishment of a radio resource control (RRC) connection by the relay terminal device transmitted by the relay terminal device; and resumption of transmission of relayed data to the relay terminal device. 16. The method according to paragraph 12, also including: receiving a radio resource control (RRC) connection re-establishment error notification message transmitted by the relay terminal device; and disconnecting from the relay terminal device and performing at least one of relay reselection, connection reestablishment initiation, and cell reselection. 17. A relay terminal device including a processor and a memory storing a computer program executed by the processor, wherein the processor ensures the execution of the method according to any of paragraphs 1-11. 18. A remote terminal device including a processor and memory storing a computer program executed by the processor, wherein the processor ensures the execution of the method according to any of paragraphs 12-16. 19. A machine-readable medium for storing instructions, the execution of which ensures the implementation of the method according to any of paragraphs 1-11. 20. A machine-readable medium for storing instructions, the execution of which ensures the implementation of the method according to any of paragraphs 12-16.

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