A communication method and device

Abstract

The present application relates to a communication method and apparatus. A first message is received from a network device, where the first message is used to inquire whether a first terminal device can provide a relay service, or the first message includes configuration information, and the configuration information is used to configure the first terminal device to provide a relay service for a second terminal device. A second message is sent to the network device. When the first message is used to inquire whether the first terminal device can provide a relay service, the second message is used to indicate whether the first terminal device can provide a relay service; or, when the first message includes configuration information, the second message is used to indicate whether the configuration of the first terminal device is complete, or to indicate whether the first terminal device can provide a relay service. If the first terminal device refuses to provide a relay service, since the network device can also be informed of this situation, the first terminal device does not need to enter the RRC re-establishment process, but can continue to work normally under the network device, thereby improving the service quality of the first terminal device.

Description

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This application claims the priority of the Chinese patent application filed with the State Intellectual Property Office of China on August 25, 2020, with application number 202010866837.X and application name “A path switch process exception handling method”, the entire contents of which are incorporated by reference into this application; this application claims the priority of the Chinese patent application filed with the State Intellectual Property Office of China on October 15, 2020, with application number 202011105001.4 and application name “A communication method and device”, the entire contents of which are incorporated by reference into this application. Technical Field

[0003] The present application relates to the field of communication technology, and in particular to a communication method and device. Background Art

[0004] Among the user equipment (UE) relay technologies currently proposed, there is a relay mode in which the remote UE can be visible to the radio access network (RAN). In this relay mode, the remote UE can implement path switching, or link switching. For example, the remote UE can switch from a direct Uu link with the base station to an indirect link that communicates indirectly with the base station. The indirect link here is also a relay link, that is, the remote UE is connected to the base station through the relayUE.

[0005] The path switch process of the remote UE includes the process of switching from a direct link to an indirect link, the process of switching from an indirect link to a direct link, and the process of switching from an indirect link to an indirect link. Among them, for the case of switching to an indirect link (including switching from a direct link to an indirect link, or switching from an indirect link to an indirect link), the mainstream solution currently under discussion is that the base station configures the remote UE to perform measurements, and the remote UE sends the measurement results to the base station, and the base station decides whether the remote UE should perform path switch. If the base station determines that the remote UE is to perform path switch, the base station sends configuration information to the remote UE and the relay UE respectively for the configuration of the path switch.

[0006] In this path switch mode, if the relay UE refuses the relevant configuration, for example, the relay UE refuses to provide relay service for the remote UE, the relay UE needs to handle it according to the configuration failure. Specifically, the relay UE will enter the radio resource control (RRC) reestablishment process and can continue to work only after the RRC reestablishment is successful, which will obviously cause the service quality of the relay UE to deteriorate. Summary of the invention

[0007] The embodiments of the present application provide a communication method and apparatus for improving the service quality of a relay UE.

[0008] In a first aspect, a first communication method is provided, which can be executed by a first terminal device, or by a chip system, and the chip system can realize the function of the first terminal device. The first terminal device is, for example, a terminal device that provides relay services for other terminal devices in a relay scenario. The method includes: receiving a first message from a network device; wherein the first message is used to inquire whether the first terminal device can provide a relay service, or the first message includes configuration information, and the configuration information is used to configure the first terminal device to provide a relay service for a second terminal device; sending a second message to the network device; wherein, when the first message is used to inquire whether the first terminal device can provide a relay service, the second message is used to indicate whether the first terminal device can provide a relay service; or, when the first message includes configuration information, the second message is used to indicate whether the configuration of the first terminal device is complete, or the second message is used to indicate whether the first terminal device can provide a relay service.

[0009] In the embodiment of the present application, regardless of whether the first terminal device can provide the relay service for the second terminal device, the first terminal device can send a second message to the network device for notification, so that the network device can know whether the first terminal device can provide the relay service for the second terminal device. Therefore, if the first terminal device refuses to provide the relay service for the second terminal device, since the network device can also know this situation, the first terminal device does not need to enter the RRC re-establishment process, but can continue to work normally under the network device, thereby improving the service quality of the first terminal device and reducing the resources consumed by the RRC re-establishment process.

[0010] In combination with the first aspect, in a first optional implementation of the first aspect, the second message is used to indicate that the first terminal device determines that the configuration has failed, or is used to indicate that the first terminal device refuses to provide relay service for the second terminal device, and the method also includes: not initiating an RRC re-establishment process.

[0011] In combination with the first aspect or the first optional implementation of the first aspect, in the second optional implementation of the first aspect, when the first message is used to inquire whether the first terminal device can provide relay service, the first message includes one or more of the following: an identification of the second terminal device, integrity protection algorithm information or integrity protection rate information, encryption algorithm information or encryption rate information, PQI or 5QI, QoS, network slice information, or computing capability information.

[0012] The first message may include one or more of the above information. In addition to the above information, the first message may also include other information. Through the above one or more of the above information, the first terminal device can clearly understand the capabilities that the relay service needs to meet, so that the first terminal device can more accurately decide whether to provide the relay service.

[0013] In combination with the first aspect or the first optional implementation manner of the first aspect or the second optional implementation manner of the first aspect, in a third optional implementation manner of the first aspect, the second message is used to indicate that the configuration of the first terminal device has failed, or to indicate that the first terminal device refuses to provide relay service, and the second message also includes a reason value, and the reason value is used to indicate the reason why the first terminal device refuses to provide relay service.

[0014] The second message may include a reason value, which may indicate the reason why the first terminal device refuses to provide relay service, so that the network device can clearly understand why the first terminal device cannot provide relay service, so that the network device can take corresponding measures, for example, the network device can re-search for a terminal device that can provide relay service for the second terminal device.

[0015] In combination with the third optional implementation manner of the first aspect, in a fourth optional implementation manner of the first aspect, the reason why the first terminal device refuses to provide the relay service includes one or more of the following:

[0016] The first terminal device does not support the configuration of the Uu port included in the first message;

[0017] The first terminal device does not support the configuration of the PC5 port included in the first message;

[0018] The first terminal device fails to pass the access control of the second terminal device;

[0019] The first terminal device does not support the integrity protection algorithm included in the first message;

[0020] The first terminal device does not support the 5QI or PQI included in the first message;

[0021] The first terminal device cannot recognize the QoS flow ID indicated by the first message;

[0022] The first terminal device does not support the network slice indicated by the first message;

[0023] The first terminal device has insufficient power;

[0024] The PDCP of the first terminal device is overloaded; or,

[0025] The first terminal device does not support the computing capability indicated by the first message.

[0026] Some reasons why the first terminal device refuses to provide relay service are given above. In addition to the above reasons, the first terminal device may also refuse to provide relay service for other reasons. There is no limitation on the reasons why the first terminal device refuses to provide relay service.

[0027] In combination with the first aspect or any optional implementation manner from the first optional implementation manner to the fourth optional implementation manner of the first aspect, in the fifth optional implementation manner of the first aspect, the first message is used to inquire whether the first terminal device can provide relay service, and the second message is used to indicate that the first terminal device can provide relay service, and the method also includes: receiving the configuration information from the network device; and configuring according to the configuration information to provide relay service.

[0028] If the first message is to inquire whether the first terminal device can provide relay service, then the first message may not include configuration information. If the second message indicates that the first terminal device can provide relay service, the network device can send configuration information to the first terminal device, so that the first terminal device can be configured according to the configuration information to provide relay service.

[0029] In combination with the first aspect or any optional implementation manner from the first optional implementation manner to the fifth optional implementation manner of the first aspect, in the sixth optional implementation manner of the first aspect, the first message is an RRC reconfiguration message, or a message dedicated to inquiring whether the terminal device can provide relay service.

[0030] The first message can be implemented through an existing message, such as an RRC reconfiguration message, so that no other message needs to be added, which is conducive to compatibility with existing technologies. Alternatively, the first message can also be implemented through other messages, such as a new first message in the embodiment of the present application, which can be used to inquire whether the terminal device can provide relay services, so that there is no need to change the existing message.

[0031] In combination with the first aspect or any optional implementation manner from the first optional implementation manner to the sixth optional implementation manner of the first aspect, in the seventh optional implementation manner of the first aspect, the second message is an RRC reconfiguration completion message, or a message dedicated to indicating whether the terminal device provides relay service.

[0032] For example, regardless of whether the second message indicates success (for example, indicating that the first terminal device can provide relay service, or indicating that the configuration is complete) or failure (for example, indicating that the first terminal device refuses to provide relay service, or indicating that the configuration has failed), the same message can be used as the second message, for example, an RRC reconfiguration completion message can be used, or a newly added message can be used. The same message can indicate both success and failure, without introducing too many message types, thereby reducing the types of messages that the network device needs to recognize. Alternatively, different messages can be used for the second message to indicate success and failure. If this is the case, for example, the second message can use an RRC reconfiguration completion message to indicate success, and the second message can use a newly added message to indicate success or failure, and so on. By indicating success and failure respectively through different messages, the network device can determine whether it is a success or a failure based on the type of the second message, and the network device can determine success or failure more efficiently.

[0033] In combination with the first aspect or any optional implementation manner from the first optional implementation manner to the seventh optional implementation manner of the first aspect, in the eighth optional implementation manner of the first aspect, when the second message is used to indicate a configuration failure, the second message is a failure information message, or a SUI message.

[0034] If the second message indicates success and indicates failure using different messages, for example, if the second message indicates failure, the second message may be a failure information message, or may be a SUI message, and if the second message indicates success, the second message may be an RRC reconfiguration message, or may be other messages. Indicating success or failure using existing messages can improve the efficiency of determining success or failure of the network device, and there is no need to add new messages, which is conducive to compatibility with existing technologies.

[0035] In a second aspect, a second communication method is provided, which can be executed by a network device, or by a chip system, and the chip system can realize the functions of the network device. Exemplarily, the network device is an access network device, such as a base station. The method includes: sending a first message to a first terminal device; wherein the first message is used to inquire whether the first terminal device can provide a relay service, or the first message includes configuration information, and the configuration information is used to configure the first terminal device to provide a relay service for the second terminal device; receiving a second message from the first terminal device; wherein, when the first message is used to inquire whether the first terminal device can provide a relay service, the second message is used to indicate whether the first terminal device can provide a relay service; or, when the first message includes configuration information, the second message is used to indicate whether the configuration of the first terminal device is complete, or the second message is used to indicate whether the first terminal device can provide a relay service.

[0036] In combination with the second aspect, in a first optional implementation of the second aspect, the method further includes: determining that the first terminal device does not perform RRC re-establishment.

[0037] In combination with the second aspect or the first optional implementation of the second aspect, in the second optional implementation of the second aspect, when the first message is used to inquire whether the first terminal device can provide relay service, the first message includes one or more of the following: an identifier of the second terminal device, parameters of the PC5 or Uu port, integrity protection algorithm or integrity protection rate, encryption algorithm or encryption rate, PQI or 5QI, QoS, network slicing information, or computing capability information.

[0038] In combination with the second aspect or the first optional implementation manner of the second aspect or the second optional implementation manner of the second aspect, in a third optional implementation manner of the second aspect, the second message is used to indicate that the configuration of the first terminal device has failed, or to indicate that the first terminal device refuses to provide relay service, and the second message also includes a reason value, and the reason value is used to indicate the reason why the second terminal device refuses to provide relay service.

[0039] In combination with the third optional implementation manner of the second aspect, in a fourth optional implementation manner of the second aspect, the reason why the first terminal device refuses to provide the relay service includes one or more of the following:

[0040] The first terminal device does not support the configuration of the Uu port included in the first message;

[0041] The first terminal device does not support the configuration of the PC5 port included in the first message;

[0042] The first terminal device fails to pass the access control of the second terminal device;

[0043] The first terminal device does not support the integrity protection algorithm included in the first message;

[0044] The first terminal device does not support the 5QI or PQI included in the first message;

[0045] The first terminal device cannot recognize the QoS flow ID indicated by the first message;

[0046] The first terminal device does not support the network slice indicated by the first message;

[0047] The first terminal device has insufficient power;

[0048] The PDCP of the first terminal device is overloaded; or,

[0049] The first terminal device does not support the computing capability indicated by the first message.

[0050] In combination with the second aspect or any optional implementation manner from the first optional implementation manner to the fourth optional implementation manner of the second aspect, in the fifth optional implementation manner of the second aspect, the first message is used to inquire whether the first terminal device can provide relay service, and the second message is used to indicate that the first terminal device can provide relay service, and the method also includes: sending the configuration information to the first terminal device.

[0051] In combination with the second aspect or any optional implementation manner from the first optional implementation manner to the fifth optional implementation manner of the second aspect, in a sixth optional implementation manner of the second aspect, the first message is an RRC reconfiguration message.

[0052] In combination with the second aspect or any optional implementation manner from the first optional implementation manner to the sixth optional implementation manner of the second aspect, in the seventh optional implementation manner of the second aspect, the second message is an RRC reconfiguration completion message, or a message dedicated to indicating whether the terminal device provides relay service.

[0053] In combination with the second aspect or any optional implementation manner from the first optional implementation manner to the seventh optional implementation manner of the second aspect, in the eighth optional implementation manner of the second aspect, when the second message is used to indicate a configuration failure, the second message is a failure information message, or a SUI message.

[0054] In combination with the second aspect or any one of the optional implementations from the first optional implementation to the eighth optional implementation of the second aspect, in the ninth optional implementation of the second aspect, the second message is used to instruct the first terminal device to refuse to provide relay service, and the method also includes: sending a third message to the second terminal device, the third message being used to instruct the first terminal device to refuse to provide relay service, or to instruct to reselect a terminal device that can provide relay service.

[0055] If the first terminal device refuses to provide relay service, the network device may inform the second terminal device so that the second terminal device may take corresponding measures. For example, the second terminal device may restart measurement to find a terminal device that can provide relay service.

[0056] In combination with the ninth optional implementation of the second aspect, in the tenth optional implementation of the second aspect, the third message also includes information of one or more terminal devices, and the one or more terminal devices are terminal devices that cannot provide relay services.

[0057] The one or more terminal devices are terminal devices that cannot provide relay services, so the second terminal device does not need to measure the one or more terminal devices when performing measurements, so as to meet the energy saving requirements of the second terminal device.

[0058] In combination with the second aspect or any optional implementation manner from the first optional implementation manner to the tenth optional implementation manner of the second aspect, in the eleventh optional implementation manner of the second aspect, the method also includes: receiving a fourth message from the second terminal device, the fourth message being used to indicate energy saving requirements; sending first information to the second terminal device, the first information including information of M terminal devices, the M terminal devices being terminal devices that do not require measurement, or being terminal devices that refuse to provide relay services, and M is a positive integer.

[0059] If the second terminal device has energy-saving requirements, the second terminal device can inform the network device. After the network device learns that the second terminal device has energy-saving requirements, it can send the first information to the second terminal device. The M terminal devices indicated by the first information can be terminal devices that do not need to be measured, or terminal devices that refuse to provide relay services. Therefore, after the second terminal device receives the first information, it does not need to measure the M terminal devices during measurement, so as to reduce the power consumption caused by the measurement and achieve energy-saving requirements.

[0060] In combination with the eleventh optional implementation of the second aspect, in the twelfth optional implementation of the second aspect, the fourth message also includes second information, the second information includes information of N terminal devices, the N terminal devices are terminal devices that refuse to provide relay services, and N is a positive integer.

[0061] For example, if the second terminal device determines, based on historical information, that N terminal devices have refused to provide relay services for the second terminal device, the second terminal device may add the information of the N terminal devices to a blacklist and send the blacklist to the network device. Thus, when the network device configures the second terminal device to perform measurements, it may consider not configuring the second terminal device to measure the N terminal devices, so as to reduce the invalid measurement process of the second terminal device.

[0062] Regarding the technical effects brought about by the second aspect or each optional implementation manner of the second aspect, reference may be made to the introduction to the technical effects of the first aspect or the corresponding implementation manner.

[0063] In a third aspect, a third communication method is provided, which can be executed by a second terminal device, or by a chip system, and the chip system can realize the functions of the second terminal device. The second terminal device is, for example, a terminal device that needs to be relayed by other terminal devices in a relay scenario. The method includes: sending a measurement result to a network device, the measurement result including a measurement report for at least one terminal device; if a first condition is met, performing a first operation, otherwise not performing the first operation, the first operation including one or more of the following: sending a discovery message, measuring other terminal devices, or sending a new measurement result to the network device.

[0064] The first operation can be regarded as an operation related to the measurement process. That is to say, in the embodiment of the present application, if the first condition is not met, the second terminal device may not perform the first operation. Since the second terminal device has sent the measurement result to the network device, the network device can determine whether the second terminal device can perform path switching based on the measurement result. Therefore, even if the second terminal device no longer performs the measurement and no longer sends new measurement results to the network device, it has little effect on the judgment of the network device. In this way, the measurement process of the second terminal device can be reduced, the resources consumed by the measurement process can be reduced, and the power of the second terminal device can be saved.

[0065] In combination with the third aspect, in a first optional implementation of the third aspect, after sending the measurement result to the network device, the method further includes: starting a timer; wherein the first condition is that the timer times out.

[0066] In this way, satisfying the first condition means that the timer has timed out, and not satisfying the first condition means that the timer has not timed out. Determining whether to execute the first operation by the timer is relatively simple, which is conducive to promoting the technical solution of the embodiment of the present application to more terminal devices.

[0067] In combination with the third aspect, in a second optional implementation of the third aspect, the first condition is receiving a third message from the network device, and the third message is used to instruct the first terminal device to refuse to provide relay service, or to instruct to reselect a terminal device that can provide relay service.

[0068] In this way, satisfying the first condition means receiving the third message from the network device, and not satisfying the first condition means not receiving the third message from the network device. Determining whether to perform the first operation by the message from the network device can make the determination result more accurate and more in line with the current situation.

[0069] In combination with the second optional implementation of the third aspect, in a third optional implementation of the third aspect, the third message also includes information of one or more terminal devices, and the one or more terminal devices are terminal devices that cannot provide relay services.

[0070] In combination with the third aspect or any optional implementation manner from the first optional implementation manner of the third aspect to the third optional implementation manner of the third aspect, in the fourth optional implementation manner of the third aspect, the method also includes: sending a fourth message to the network device, the fourth message being used to indicate energy saving requirements; receiving first information from the network device, the first information including information of M terminal devices, the M terminal devices being terminal devices that do not require measurement, or being terminal devices that refuse to provide relay services, and M is a positive integer.

[0071] In combination with the fourth optional implementation of the third aspect, in the fifth optional implementation of the third aspect, the fourth message also includes second information, the second information includes information of N terminal devices, the N terminal devices are terminal devices that refuse to provide relay services, and N is a positive integer.

[0072] In combination with the third aspect or any optional implementation manner from the first optional implementation manner of the third aspect to the fifth optional implementation manner of the third aspect, in the sixth optional implementation manner of the third aspect, the method also includes: receiving measurement configuration information from a network device, performing measurement according to the measurement configuration information, and obtaining the measurement result; sending the measurement result to the network device, including: when the reporting conditions of the measurement report are met, sending the measurement result to the network device.

[0073] The network device sends measurement configuration information to the second terminal device to configure the second terminal device to perform measurement. After the second terminal device performs measurement, the measurement result may be obtained, and the measurement result may include, for example, a measurement report obtained by measuring one or more terminal devices. If the reporting conditions of the measurement report are met, the second terminal device may send the measurement result to the network device, so that the network device can obtain the measurement result of the second terminal device to select a terminal device that can provide relay service for the second terminal device.

[0074] In combination with the third aspect or any optional implementation manner from the first optional implementation manner of the third aspect to the sixth optional implementation manner of the third aspect, in the seventh optional implementation manner of the third aspect, when the first operation includes sending a discovery message, the method also includes: sending the discovery message; and stopping sending the discovery message if the first condition is not met.

[0075] If the first operation includes sending a discovery message, then if the second terminal device originally did not send a discovery message, then when it is determined that the first condition is not met, the second terminal device continues not to send a discovery message. Alternatively, if the second terminal device originally sent a discovery message, then when it is determined that the first condition is not met, the second terminal device may stop sending the discovery message to save power consumption.

[0076] In combination with the third aspect or any optional implementation manner from the first optional implementation manner of the third aspect to the sixth optional implementation manner of the third aspect, in the eighth optional implementation manner of the third aspect, when the first operation includes sending the new measurement result to the network device, the method also includes: receiving a discovery message from a second terminal device; measuring the discovery message of the second terminal device to obtain the new measurement result; and not sending the new measurement result to the network device if the first condition is not met and the reporting condition of the measurement report is met.

[0077] If the second terminal device receives the discovery message from the first terminal device, the second terminal device can measure the discovery message to obtain a new measurement result. If the first operation includes sending a new measurement report to the network device (or the first operation includes sending a measurement report to the network device), then, if the first condition is not met, even if the reporting condition of the measurement report is met, the second terminal device does not send a new measurement report to the network device to save power consumption.

[0078] Regarding the technical effects brought about by some optional implementations of the third aspect, reference may be made to the introduction to the technical effects of the corresponding implementations of the second aspect.

[0079] In a fourth aspect, a fourth communication method is provided, which can be executed by a second terminal device, or by a chip system, and the chip system can realize the function of the second terminal device. The second terminal device is, for example, a terminal device that needs to be relayed through other terminal devices in a relay scenario. The method includes: receiving configuration information from a first network device, the configuration information is used to configure the second terminal device to switch to communicate with a third network device through the first terminal device, or to configure the second terminal device to switch to a second network device; performing path switching according to the configuration information; if the first condition is met, determining that the path switching is successful, otherwise determining that the path switching fails.

[0080] In the embodiment of the present application, the second terminal device can determine whether the path switching is successful or failed according to the first condition, that is, the embodiment of the present application provides a method for the second terminal device to determine whether the path switching is successful. If the path switching fails, the second terminal device can take corresponding actions, such as continuing to communicate under the source network device, or entering a new cell through cell reselection, so as to restore the service of the second terminal device as soon as possible and improve the continuity of the service.

[0081] In combination with the fourth aspect, in a first optional implementation of the fourth aspect, after receiving configuration information from the first network device, it also includes: starting a timer; wherein the first condition is that the timer has not timed out.

[0082] In this manner, satisfying the first condition means that the timer has not timed out, and not satisfying the first condition means that the timer has timed out. The second terminal device can determine whether the path switching is successful or failed based on the timer, and the determination method is relatively simple and easy to implement. Even for terminal devices with lower capabilities, the technical solution of the embodiment of the present application can be applied.

[0083] In combination with the fourth aspect, in a second optional implementation manner of the fourth aspect, the configuration information is used to configure the second terminal device to switch to communicate with the third network device through the first terminal device, and the first condition includes:

[0084] When the number of times the connection establishment request message is sent to the first terminal device is less than or equal to M, feedback is received from the first terminal device, where M is the maximum number of retransmissions; or,

[0085] The security verification of the first terminal device is passed; or,

[0086] A connection establishment request message is sent to the first terminal device, and a connection establishment response message is received from the first terminal device, wherein the connection establishment response message is used to indicate acceptance of establishing a connection.

[0087] If the second terminal device determines whether the path switching is successful based on a timer, the timing duration of the timer is generally not set too short, otherwise the determination result of the second terminal device may not be accurate enough. However, if the second terminal device does not use a timer, but determines whether the path switching is successful based on one of the above conditions, the time required for determination is relatively short and more efficient, so that the second terminal device can quickly determine whether the path switching is successful, so as to take corresponding measures as soon as possible and reduce the time of service interruption.

[0088] In combination with the fourth aspect or the first optional implementation manner of the fourth aspect or the second optional implementation manner of the fourth aspect, in the third optional implementation manner of the fourth aspect, determining that the path switching fails, the method also includes: sending failure information to the first network device via a first path, the failure information being used to indicate the path switching failure, the first path being the communication path between the second terminal device and the first network device before switching the path; and continuing to communicate with the first network device via the first path.

[0089] The first path is the communication path between the second terminal device and the first network device before the path switching is performed, for example, the first path is the second terminal device-first network device, or the second terminal device-first terminal device-first network device. If the second terminal device has not disconnected the connection with the first network device through the first path before the path switching is successful, the second terminal device can execute the method. After the first network device receives the failure information, the second terminal device and the first network device can continue to communicate through the first path, that is, since the second terminal device has not disconnected the original communication path, it can continue to communicate through the original communication path without reselecting the communication path, or the second terminal device will not initiate the RRC connection re-establishment process, thereby improving the service continuity of the second terminal device.

[0090] In combination with the fourth aspect or the first optional implementation manner of the fourth aspect or the second optional implementation manner of the fourth aspect, in the fourth optional implementation manner of the fourth aspect, the path switching failure is determined, and the method also includes: sending an RRC connection re-establishment request message to the first network device via a first path, the RRC connection re-establishment request message is used to request to re-establish the RRC connection with the first network device, and the first path is the communication path between the second terminal device and the first network device before switching the path.

[0091] If the second terminal device has not disconnected the connection with the first network device through the first path before the path switching is successful, the second terminal device may also execute the method to re-establish the RRC connection under the first network device to communicate with the first network device through the new connection.

[0092] In combination with the third optional implementation of the fourth aspect or the fourth optional implementation of the fourth aspect, in the fifth optional implementation of the fourth aspect, the first path is a path connected to the first network device through a third terminal device; or, the first path is a path directly connected to the first network device.

[0093] In combination with the fourth aspect or the first optional implementation of the fourth aspect or the second optional implementation of the fourth aspect, in a sixth optional implementation of the fourth aspect, it is determined that the path switching failure has occurred, and the method further includes: performing cell reselection to reselect to the first cell; initiating an RRC connection reestablishment process in the first cell, or initiating an RRC connection establishment process in the first cell.

[0094] For example, if the second terminal device disconnects the first path between the second terminal device and the first network device, the second terminal device may execute the method; or even if the second terminal device does not disconnect the first path between the second terminal device and the first network device, the second terminal device may execute the method.

[0095] In a fifth aspect, a fifth communication method is provided, which can be executed by a first network device, or by a chip system, and the chip system can implement the functions of the first network device. The method includes: receiving failure information or an RRC connection re-establishment request message from a second terminal device through a first path, wherein the failure information is used to indicate a path switching failure, and the RRC connection re-establishment request message is used to request to re-establish an RRC connection with the first network device, and the first path is a communication path between the second terminal device and the first network device before switching the path.

[0096] In combination with the fifth aspect, in a first optional implementation of the fifth aspect, what is received is the failure information, and the method further includes: determining that the second terminal device does not initiate RRC connection re-establishment.

[0097] Regarding the technical effects brought about by the fifth aspect or the first optional implementation of the fifth aspect, reference may be made to the introduction to the technical effects of the fourth aspect or the corresponding implementation.

[0098] In a sixth aspect, a sixth communication method is provided, which can be executed by a second terminal device, or by a chip system, and the chip system can realize the functions of the second terminal device. The second terminal device is, for example, a terminal device that needs to be relayed through other terminal devices in a relay scenario. The method includes: receiving configuration information from a first network device, the configuration information is used to configure the second terminal device to switch to communicate with a third network device through the first terminal device, or to configure the second terminal device to switch to a second network device; performing path switching according to the configuration information; and determining that the path switching fails when the second condition is met.

[0099] In the embodiment of the present application, the second terminal device can determine whether the path switching fails according to the second condition, that is, the embodiment of the present application provides a method for the second terminal device to determine whether the path switching fails. If the path switching fails, the second terminal device can take corresponding operations, such as continuing to initiate re-establishment under the source network device, or can enter a new cell through cell reselection to re-establish, or can initiate re-establishment through the first terminal device, or can reselect or select through the relay terminal device, select a new relay terminal device, and initiate re-establishment through the relay terminal device, so as to restore the service of the second terminal device as soon as possible and improve the continuity of the service.

[0100] In combination with the sixth aspect, in a first optional implementation of the sixth aspect, after receiving configuration information from the first network device, it also includes: starting a timer; wherein the second condition is that the timer times out.

[0101] In this way, satisfying the second condition means that the timer times out. The second terminal device can determine whether the path switching is successful or failed based on the timer, and the determination method is relatively simple and easy to implement. Even for terminal devices with lower capabilities, the technical solution of the embodiment of the present application can be applied.

[0102] In combination with the first implementation of the sixth aspect, in a second optional implementation of the sixth aspect, when one or more of the following conditions are met, the timer is stopped:

[0103] The second terminal device is connected to the PC5 of the first terminal device; or,

[0104] The random access between the second terminal device and the second network device is successful; or,

[0105] The second terminal device sends an RRC reconfiguration completion message to a lower layer of the second terminal device, and receives a confirmation feedback from the lower layer; or,

[0106] The second terminal device receives second indication information from the third network device, where the second indication information is used to instruct the second terminal device to stop the timer; or,

[0107] The second terminal device receives third indication information from the first terminal device, where the third indication information is used to instruct the second terminal device to stop the timer, or the third indication information is used to indicate that the first terminal device has successfully randomly accessed the third network device; or,

[0108] The second terminal device receives fourth indication information from the first terminal device, where the fourth indication information is used to indicate that a Uu radio link failure (RLF) occurs in the first terminal device or that the first terminal device fails to randomly access the third network device; or,

[0109] The second terminal device fails to establish a PC5 connection with the first terminal device or determines PC5RLF.

[0110] If the second terminal device determines whether the path switching fails based on the timer expiration, the timing duration of the timer is generally not set too short and needs to be stopped in time to avoid being judged as a path switching failure due to the timer not being stopped.

[0111] In combination with the sixth aspect or the first optional implementation manner of the sixth aspect or the second optional implementation manner of the sixth aspect, in the third optional implementation manner of the sixth aspect,

[0112] The second condition is that the timer times out; or,

[0113] The second condition is that the second terminal device receives fourth indication information from the first terminal device, and the fourth indication information is used to indicate that Uu RLF occurs in the first terminal device or the first terminal device fails to randomly access the third network device; or

[0114] The second condition is that the second terminal device fails to establish a PC5 connection with the first terminal device or determines that PC5RLF.

[0115] If the second terminal device determines whether the path switching fails only based on the timer timeout, the timer duration is generally not set too short, and when a failure occurs, the second terminal device still needs to wait. This implementation can quickly determine the failure when a failure occurs and enter the recovery process as soon as possible, thereby improving the service continuity of the second terminal device.

[0116] In combination with the sixth aspect or the first optional implementation manner of the sixth aspect or the second optional implementation manner of the sixth aspect or the third optional implementation manner of the sixth aspect, in the fourth optional implementation manner of the sixth aspect, the method also includes: the second terminal device sends an RRC connection re-establishment request message to the first network device via a first path, the RRC connection re-establishment request message is used to request to re-establish the RRC connection with the first network device, and the first path is the communication path between the second terminal device and the first network device before switching the path.

[0117] If the second terminal device has not disconnected the connection with the first network device through the first path before the path switching is successful, the second terminal device may also execute the method to re-establish the RRC connection under the first network device to communicate with the first network device through the new connection.

[0118] In combination with the fourth optional implementation of the sixth aspect, in the fifth optional implementation of the sixth aspect, the first path is a path connected to the first network device through a third terminal device; or, the first path is a path directly connected to the first network device.

[0119] In combination with the sixth aspect or the first optional implementation manner of the sixth aspect or the second optional implementation manner of the sixth aspect or the third optional implementation manner of the sixth aspect, in the sixth optional implementation manner of the sixth aspect, the method also includes: performing cell reselection to reselect to the first cell; initiating an RRC connection reestablishment process in the first cell, or initiating an RRC connection establishment process in the first cell.

[0120] For example, if the second terminal device disconnects the first path between the second terminal device and the first network device, the second terminal device may execute the method; or even if the second terminal device does not disconnect the first path between the second terminal device and the first network device, the second terminal device may execute the method.

[0121] In a seventh aspect, a communication device is provided. The communication device may include a module for executing the method in the first aspect or any optional implementation of the first aspect, for example, including a processing unit and a transceiver unit. Optionally, the communication device may also include a storage unit.

[0122] For example, the processing unit is used to receive a first message from a network device through the transceiver unit, where the first message includes configuration information, or the first message is used to inquire whether the first terminal device can provide a relay service, wherein the configuration information is used to configure the first terminal device to provide a relay service for a second terminal device;

[0123] The processing unit is further used to send a second message to the network device through the transceiver unit, wherein the second message is used to indicate that the configuration of the first terminal device is completed, or the configuration fails, wherein the first message includes the configuration information; or, the second message is used to indicate that the first terminal device can provide relay service, or refuses to provide relay service.

[0124] In an eighth aspect, a communication device is provided. The communication device may include a module for executing the method in the second aspect or any optional implementation of the second aspect, for example, including a transceiver unit and a processing unit. Optionally, the communication device may also include a storage unit.

[0125] For example, the processing unit is used to send a first message to the first terminal device through the transceiver unit, where the first message includes configuration information, or the first message is used to inquire whether the first terminal device can provide a relay service, wherein the configuration information is used to configure the first terminal device to provide a relay service for the second terminal device;

[0126] The processing unit is further used to receive a second message from the first terminal device through the transceiver unit, the second message being used to indicate that the configuration of the first terminal device is complete, or the configuration fails, wherein the first message includes the configuration information; or, the second message is used to indicate that the first terminal device can provide relay service, or refuses to provide relay service.

[0127] In a ninth aspect, a communication device is provided. The communication device may include a module for executing the method in the third aspect or any optional implementation of the third aspect, for example, including a transceiver unit and a processing unit. Optionally, the communication device may also include a storage unit.

[0128] For example, the processing unit is used to send a measurement result to a network device through the transceiver unit, where the measurement result includes a measurement report for at least one terminal device;

[0129] The processing unit is also used to perform a first operation when a first condition is met, otherwise not perform the first operation, and the first operation includes one or more of the following: sending a discovery message, measuring other terminal devices, or sending a new measurement result to the network device.

[0130] In a tenth aspect, a communication device is provided. The communication device may include a module for executing the method in the fourth aspect or any optional implementation of the fourth aspect, for example, including a transceiver unit and a processing unit. Optionally, it may also include a storage unit.

[0131] For example, the processing unit is used to receive configuration information from the first network device through the transceiver unit, and the configuration information is used to configure the second terminal device to switch to communicate with the third network device through the first terminal device, or to configure the second terminal device to switch to the second network device;

[0132] The processing unit is further used to perform path switching according to the configuration information;

[0133] The processing unit is further configured to determine that the path switching is successful if the first condition is met, and otherwise determine that the path switching is failed.

[0134] In an eleventh aspect, a communication device is provided. The communication device may include a module for executing the method in the fifth aspect or any optional implementation of the fifth aspect, for example, including a transceiver unit and a processing unit. Optionally, it may also include a storage unit.

[0135] For example, the processing unit is used to receive failure information or an RRC connection re-establishment request message from the second terminal device through the transceiver unit, the failure information is used to indicate a path switching failure, and the RRC connection re-establishment request message is used to request the re-establishment of the RRC connection with the first network device, and the first path is the communication path between the second terminal device and the first network device before switching the path.

[0136] In a twelfth aspect, a communication device is provided. The communication device may include a module for executing the method in the sixth aspect or any optional implementation of the sixth aspect, for example, including a transceiver unit and a processing unit. Optionally, the communication device may also include a storage unit.

[0137] For example, the processing unit is used to receive configuration information from the first network device through the transceiver unit, and the configuration information is used to configure the second terminal device to switch to communicate with the third network device through the first terminal device, or to configure the second terminal device to switch to the second network device;

[0138] The processing unit is further used to perform path switching according to the configuration information;

[0139] The processing unit is further configured to determine that the path switching is successful if the first condition is met, and otherwise determine that the path switching is failed.

[0140] In a thirteenth aspect, a chip system is provided, the chip system comprising one or more processors and a communication interface, the processor being coupled to the communication interface to implement the method provided in the first aspect or any optional implementation of the first aspect. Optionally, the chip system may also include a memory, for example, the processor may read and execute a software program stored in the memory to implement the method provided in the first aspect or any optional implementation of the first aspect.

[0141] In a fourteenth aspect, a chip system is provided, the chip system comprising one or more processors and a communication interface, the processor being coupled to the communication interface to implement the method provided in the second aspect or any optional implementation of the second aspect. Optionally, the chip system may also include a memory, for example, the processor may read and execute a software program stored in the memory to implement the method provided in the second aspect or any optional implementation of the second aspect.

[0142] In a fifteenth aspect, a chip system is provided, the chip system comprising one or more processors and a communication interface, the processor being coupled to the communication interface to implement the method provided in the third aspect or any optional implementation of the third aspect. Optionally, the chip system may also include a memory, for example, the processor may read and execute a software program stored in the memory to implement the method provided in the third aspect or any optional implementation of the third aspect.

[0143] In a sixteenth aspect, a chip system is provided, the chip system comprising one or more processors and a communication interface, the processor being coupled to the communication interface to implement the method provided in the fourth aspect or any optional implementation of the fourth aspect. Optionally, the chip system may also include a memory, for example, the processor may read and execute a software program stored in the memory to implement the method provided in the fourth aspect or any optional implementation of the fourth aspect.

[0144] In the seventeenth aspect, a chip system is provided, the chip system comprising one or more processors and a communication interface, the processor being coupled to the communication interface to implement the method provided in the fifth aspect or any optional implementation of the fifth aspect. Optionally, the chip system may also include a memory, for example, the processor may read and execute a software program stored in the memory to implement the method provided in the fifth aspect or any optional implementation of the fifth aspect.

[0145] In aspect 18, a chip system is provided, the chip system comprising one or more processors and a communication interface, the processor being coupled to the communication interface to implement the method provided in aspect 6 or any optional implementation of aspect 6. Optionally, the chip system may also include a memory, for example, the processor may read and execute a software program stored in the memory to implement the method provided in aspect 6 or any optional implementation of aspect 6.

[0146] In a nineteenth aspect, a first communication system is provided. The first communication system includes the communication device described in the seventh aspect or the chip system described in the thirteenth aspect, and includes the communication device described in the eighth aspect or the chip system described in the fourteenth aspect.

[0147] In the twentieth aspect, a second communication system is provided. The second communication system includes the communication device described in the eighth aspect or the chip system described in the fourteenth aspect, and includes the communication device described in the ninth aspect or the chip system described in the fifteenth aspect.

[0148] In a twenty-first aspect, a third communication system is provided. The third communication system includes the communication device described in the tenth aspect or the chip system described in the sixteenth aspect, and includes the communication device described in the eleventh aspect or the chip system described in the seventeenth aspect.

[0149] In aspect 22, a fourth communication system is provided, wherein the fourth communication system comprises the communication device according to aspect 12 or the chip system according to aspect 18, and the communication device according to aspect 11 or the chip system according to aspect 17.

[0150] In the twenty-third aspect, a computer-readable storage medium is provided, wherein the computer-readable storage medium is used to store a computer program. When the computer program is run on a computer, the computer executes the method provided in any one of the above aspects.

[0151] In the twenty-fourth aspect, a computer program product comprising instructions is provided, wherein the computer program product is used to store a computer program. When the computer program is run on a computer, the computer executes the method provided in any one of the above aspects.

[0152] In an embodiment of the present application, if the first terminal device refuses to provide relay service to the second terminal device, since the network device can also be informed of this situation, the first terminal device does not need to enter the RRC re-establishment process, but can continue to work normally under the network device, thereby improving the service quality of the first terminal device and reducing the resources consumed by the RRC re-establishment process. BRIEF DESCRIPTION OF THE DRAWINGS

[0153] Figure 1A to Figure 1D Several scenario diagrams for path switching for remote terminal devices;

[0154] Figure 2 A flowchart for switching a remote terminal device from a direct link to an indirect link;

[0155] Figure 3 A flowchart of a first communication method provided in an embodiment of the present application;

[0156] Figure 4 A flowchart of a second communication method provided in an embodiment of the present application;

[0157] Figure 5 A flowchart of a third communication method provided in an embodiment of the present application;

[0158] Figure 6 A flowchart of a fourth communication method provided in an embodiment of the present application;

[0159] Figure 7 A flowchart of a fifth communication method provided in an embodiment of the present application;

[0160] Figure 8 A flowchart of a sixth communication method provided in an embodiment of the present application;

[0161] Fig. 9 A flowchart of a seventh communication method provided in an embodiment of the present application;

[0162] Fig.10 A flowchart of an eighth communication method provided in an embodiment of the present application;

[0163] Fig.11 A schematic block diagram of a terminal device provided in an embodiment of the present application.

[0164] Fig.12 A schematic block diagram of a communication device provided in an embodiment of the present application. DETAILED DESCRIPTION

[0165] In order to make the purpose, technical solutions and advantages of the embodiments of the present application clearer, the embodiments of the present application will be further described in detail below with reference to the accompanying drawings.

[0166] Below, some terms in the embodiments of the present application are explained to facilitate understanding by those skilled in the art.

[0167] In the embodiment of the present application, the terminal device is a device with wireless transceiver function, which can be a fixed device, a mobile device, a handheld device (such as a mobile phone), a wearable device, a vehicle-mounted device, or a wireless device built into the above device (for example, a communication module, a modem, or a chip system, etc.). The terminal device is used to connect people, objects, machines, etc., and can be widely used in various scenarios, such as but not limited to the following scenarios: cellular communication, device-to-device communication (device-to-device, D2D), vehicle to everything (vehicle to everything, V2X), machine-to-machine / machine-type communication (machine-to-machine / machine-type communications, M2M / MTC), Internet of Things (Internet of Things, IoT), virtual reality (virtual reality, VR), augmented reality (augmented reality, AR), industrial control (industrial control), self-driving, remote medical, smart grid (smart grid), smart furniture, smart office, smart wear, smart transportation, smart city (smart city), drones, robots and other scenarios of terminal devices. The terminal device may sometimes be referred to as user equipment (UE), terminal, access station, UE station, remote station, wireless communication device, or user device, etc. For the convenience of description, the terminal device is described by taking UE as an example in the embodiments of the present application. Among them, remote UE refers to UE that needs other UE to provide relay services to access the network; relay UE refers to UE that provides relay services for other UEs.

[0168] The network device in the embodiment of the present application includes, for example, an access network device and / or a core network device. The access network device is a device with a wireless transceiver function, which is used to communicate with the terminal device. The access network device includes but is not limited to the base station (BTS, Node B, eNodeB / eNB, or gNodeB / gNB) in the above-mentioned communication system, a transmission reception point (TRP), a base station of the subsequent evolution of the third generation partnership project (3GPP), an access node in the wireless fidelity (Wi-Fi) system, a wireless relay node, a wireless backhaul node, etc. The base station can be: a macro base station, a micro base station, a micro-micro base station, a small station, a relay station, etc. Multiple base stations can support the same access technology mentioned above, or they can support the networks of different access technologies mentioned above. The base station may include one or more co-station or non-co-station transmission reception points. The network device may also be a wireless controller, a centralized unit (CU), and / or a distributed unit (DU) in a cloud radio access network (CRAN) scenario. The network device can also be a server, a wearable device, or a vehicle-mounted device. For example, the network device in the vehicle to everything (V2X) technology can be a road side unit (RSU). The following describes the access network device taking the base station as an example. The base station can communicate with the terminal device, or it can communicate with the terminal device through a relay station. The terminal device can communicate with multiple base stations in different access technologies. The core network device is used to implement functions such as mobility management, data processing, session management, policy and billing. The names of the devices that implement the core network functions in systems with different access technologies may be different, and the embodiments of the present application do not limit this. Taking the 5G system as an example, the core network device includes: access and mobility management function (AMF), session management function (SMF), or user plane function (UPF), etc.

[0169] In the embodiment of the present application, the communication device for realizing the function of the network device may be a network device, or may be a device capable of supporting the network device to realize the function, such as a chip system, which may be installed in the network device. In the technical solution provided in the embodiment of the present application, the technical solution provided in the embodiment of the present application is described by taking the device for realizing the function of the network device as an example that the network device is used as the device.

[0170] In the embodiments of the present application, the number of nouns, unless otherwise specified, means "singular noun or plural noun", that is, "one or more". "At least one" means one or more, and "plural" means two or more. "And / or" describes the association relationship of associated objects, indicating that three relationships may exist. For example, A and / or B can mean: A exists alone, A and B exist at the same time, and B exists alone, where A and B can be singular or plural. The character " / " generally indicates that the previous and next associated objects are in an "or" relationship. For example, A / B means: A or B. "At least one of the following" or similar expressions refers to any combination of these items, including any combination of single or plural items. For example, at least one of a, b, or c means: a, b, c, a and b, a and c, b and c, or a and b and c, where a, b, c can be single or multiple.

[0171] The ordinal numbers such as "first" and "second" mentioned in the embodiments of the present application are used to distinguish multiple objects, and are not used to limit the size, content, order, timing, priority or importance of the multiple objects. For example, the first message and the second message can be the same message or different messages, and such names do not indicate the difference in the sending order, information volume, content, priority or importance of the two messages.

[0172] Among the currently proposed UE relay technologies, there is a relay mode in which the remote UE can be visible to the RAN. In this relay mode, the remote UE can implement path switching.

[0173] The path switch process of the remote UE includes the process of switching from a direct link to an indirect link, the process of switching from an indirect link to a direct link, and the process of switching from an indirect link to an indirect link. Figure 1A to Figure 1D .in, Figure 1AA scenario in which a remote UE switches from a non-direct link to a direct link, or a scenario in which a remote UE switches from a direct link to a non-direct link. For example, the remote UE is a smart watch, and the smart watch can be installed with an embedded subscriber identity module (eSIM) card, and the smart watch can communicate directly with the access network device through the eSIM card. The user goes out for a run with a smart watch, but does not bring a mobile phone. When outdoors, the smart watch can communicate directly with the access network device through the Uu port. When the user returns home after running, the smart watch detects the presence of the mobile phone through the sidelink (SL), and the smart watch can automatically switch from a direct link with the access network device to a non-direct link relayed by the mobile phone, or the smart watch can also switch from a direct link with the access network device to a non-direct link relayed by the mobile phone based on the user's operation, so as to use the mobile phone as a relay UE and communicate with the network through the mobile phone to save the power consumption of the smart watch.

[0174] Figure 1B The scenario where the remote UE switches from a non-direct link to another non-direct link. For example, the remote UE is a smart watch, and the user wears the smart watch and a mobile phone. At the beginning, the mobile phone is the relay UE of the smart watch, providing relay services for the smart watch. When the user enters the vehicle, the smart watch can switch from the non-direct link relayed by the mobile phone to the non-direct link relayed by the vehicle, so as to use the vehicle as the new relay UE and communicate with the network through the vehicle, which saves the power consumption of both the smart watch and the mobile phone.

[0175] Figure 1C The scenario in which the remote UE switches from a non-direct link to a direct link, or the scenario in which the remote UE switches from a direct link to a non-direct link. For example, the remote UE is a smart watch. The user is outdoors, and since the smart watch is installed with an eSIM card, the smart watch can communicate directly with access network device A through the eSIM card. Then, the user gets into a vehicle, and the vehicle drives to another city. During the driving of the vehicle, the smart watch automatically (or, based on user operation) switches from a direct link that directly communicates with access network device A to a non-direct link that is relayed through the vehicle to save power consumption of the smart watch. Since the vehicle is in motion, the access network device B and access network device A connected to the vehicle may be different access network devices.

[0176] Figure 1DThe remote UE switches from a non-direct link to a non-direct link. For example, the remote UE is a smart watch. The user takes vehicle A to a certain place. After the user enters vehicle 1, the smart watch can establish a connection with vehicle 1 and use vehicle 1 as the relay UE of the smart watch to communicate with the network through vehicle 1. On the way, the user changed vehicles and entered vehicle 2. During the driving of vehicle 2, the communication quality between the smart watch and vehicle 1 will gradually deteriorate. The smart watch can automatically (or, based on the user's operation) switch from a non-direct link relayed through vehicle 1 to a non-direct link relayed through vehicle 2 to improve the communication quality of the smart watch. In addition, since vehicle 2 is in a driving state, vehicle 1 may also be in a driving state, so the access network device serving vehicle 1 and the access network device serving vehicle 2 may be different access network devices.

[0177] in, Figure 1A and Figure 1B The scenario shown is a handover scenario within a base station (intra-gNB). Figure 1C and Figure 1D The scenario shown is an inter-gNB handover scenario.

[0178] For the case of switching to a non-direct link (including switching from a direct link to a non-direct link, or from a non-direct link to a non-direct link), the mainstream solution currently under discussion is that the base station configures the remote UE to perform measurements, and the remote UE performs measurements based on discovery messages from other UEs. The remote UE sends the measurement results to the base station, which decides whether the remote UE should perform a path switch. If the base station determines that the remote UE is to perform a path switch, the base station sends configuration information to the remote UE and the relay UE respectively for the configuration of the path switch. For example, the process of the remote UE switching from a direct link to a non-direct link can be referred to Figure 2 The process shown.

[0179] S201. A remote UE performs data transmission with a base station.

[0180] S202: The base station sends an RRC message to the remote UE, and the remote UE receives the RRC message from the base station. The RRC message includes, for example, measurement configuration information, and the measurement configuration information is used by the remote UE to measure other UEs or select other UEs.

[0181] S203: The remote UE measures or selects other UEs. For example, the remote UE may trigger other UEs to send discovery messages, so that the remote UE may measure the discovery messages from other UEs to complete the measurement or selection of other UEs.

[0182] S204, the remote UE sends a measurement result to the base station, and the base station receives the measurement result from the remote UE; or, the remote UE sends a selection result to the base station, and the base station receives the selection result from the remote UE. Figure 2 In the example, sending the measurement results is taken.

[0183] The measurement result is, for example, a measurement report, or the measurement result includes the ID of the relay UE determined by the remote UE. The selection result is, for example, the selection result of the remote UE for the relay UE, including the ID information of the relay UE, and optionally, the measurement information of the remote UE.

[0184] S205: The base station determines whether the remote UE performs path switch based on the measurement result or the selection result. If the base station determines that the remote UE performs path switch, S206 and S207 are executed; otherwise, S206 and S207 are not executed.

[0185] S206: The base station sends an RRC reconfiguration message to the relay UE, and the relay UE receives the RRC reconfiguration message from the base station. In order to distinguish it from other RRC reconfiguration messages, the RRC reconfiguration message in S206 is referred to as RRC reconfiguration message 1.

[0186] The RRC reconfiguration message 1 may include information configured by the base station for the relay UE, such as configuration information of the Uu port and configuration information of the sidelink (SL), where the sidelink is a link between the remote UE and the relay UE, and the relay UE provides relay services for the remote UE through the sidelink. After receiving the RRC reconfiguration message 1, the relay UE may perform configuration according to the information included in the RRC reconfiguration message 1, such as configuring the Uu link and the sidelink.

[0187] S207: The base station sends an RRC reconfiguration message to the remote UE, and the remote UE receives the RRC reconfiguration message from the base station. In order to distinguish it from other RRC reconfiguration messages, the RRC reconfiguration message in S207 is referred to as RRC reconfiguration message 2.

[0188] The RRC reconfiguration message 2 may include information configured by the base station for the remote UE, such as configuration information of the Uu port and configuration information of the sidelink. After receiving the RRC reconfiguration message 2, the remote UE may perform configuration according to the information included in the RRC reconfiguration message 2, such as configuring the Uu link and the sidelink.

[0189] According to the normal process, after the remote UE and relay UE are configured, the relay UE can provide relay services for the remote UE, so that the remote UE can communicate with the base station through the relay UE. However, it is very likely that the relay UE configuration fails, or the relay UE refuses to provide relay services for the remote UE. In this case, the relay UE cannot notify the base station, so the relay UE needs to handle it according to the configuration failure. Specifically, the relay UE will enter the RRC re-establishment process and can only continue to work after the RRC re-establishment is successful, which will obviously cause the service quality of the relay UE to deteriorate.

[0190] In view of this, a technical solution of an embodiment of the present application is provided. In an embodiment of the present application, regardless of whether the first terminal device is capable of providing a relay service, the first terminal device can send a second message to the network device for notification, so that the network device can learn whether the first terminal device is capable of providing a relay service. Therefore, if the first terminal device refuses to provide a relay service, since the network device can also learn of this situation, the first terminal device does not need to interrupt the current communication of the first terminal device, but can continue to work normally under the network device, thereby improving the service quality of the first terminal device and reducing the resources consumed by the RRC re-establishment process.

[0191] The technical solution provided in the embodiments of the present application can be applied to the fourth generation mobile communication technology (the 4th generation, 4G) system, such as the long term evolution (long term evolution, LTE) system, or can be applied to the 5G system, such as the new radio (new radio, NR) system, or can also be applied to the next generation mobile communication system or other similar communication systems, without specific limitation. In addition, the technical solution provided in the embodiments of the present application can be applied to device-to-device (D2D) scenarios, such as NR-D2D scenarios, etc., or can be applied to V2X scenarios, such as NR-V2X scenarios, etc., for example, it can be applied to the Internet of Vehicles, such as V2X, vehicle-to-vehicle (V2V), etc., or can be used in the fields of intelligent driving, assisted driving, or intelligent networked vehicles.

[0192] The application scenarios of the embodiments of this application can refer to Figure 1A , Figure 1B , Figure 1C or Figure 1D . Figure 1A to Figure 1D The access network device in the embodiment is, for example, a base station. The access network device corresponds to different devices in different systems. For example, in a 4G system, it may correspond to an eNB, and in a 5G system, it may correspond to an access network device in 5G, such as a gNB. Of course, the technical solution provided in the embodiment of the present application can also be applied to future mobile communication systems, so Figure 1A to Figure 1D The access network equipment in the present invention may also correspond to the network equipment in the future mobile communication system. Figure 1A to Figure 1D Taking the access network device as a base station as an example, in fact, referring to the introduction in the previous article, the access network device can also be RSU and other devices.

[0193] The method provided by the embodiments of the present application is described below in conjunction with the accompanying drawings. In the accompanying drawings corresponding to the various embodiments of the present application, all steps indicated by dotted lines are optional steps.

[0194] The present application embodiment provides a first communication method, see Figure 3 , which is a flowchart of the method. The method involves a process of switching to a non-direct link. In the following description, the method is applied to Figure 1A to Figure 1D Take the network architecture shown in any of the accompanying drawings as an example.

[0195] If the technical solution provided in the embodiment of the present application is applied to Figure 1A to Figure 1D The second terminal device described below may be a network architecture shown in any of the figures in Figure 1A to Figure 1D If the technical solution provided in the embodiment of the present application is applied to the remote terminal device shown in any of the figures. Figure 1AThe network architecture shown in FIG. 1 , the first terminal device described below may be Figure 1A The relay terminal device in the following description may be Figure 1A The access network device in; if the technical solution provided in the embodiment of the present application is applied to Figure 1B The network architecture shown in FIG. 1 , the first terminal device described below may be Figure 1B The relay terminal device 1 or the relay terminal device 2 in the embodiment, the network device described below may be Figure 1B The access network device in; if the technical solution provided in the embodiment of the present application is applied to Figure 1C The network architecture shown in FIG. 1 , the first terminal device described below may be Figure 1C The relay terminal device in the following description may be Figure 1C The access network device 1 in the embodiment of the present application is applied to Figure 1D The network architecture shown in FIG. 1 , the first terminal device described below may be Figure 1D The relay terminal device 1 in the embodiment of the present invention may be a network device Figure 1D The access network device 1 in the embodiment, or the first terminal device described below may be Figure 1D The relay terminal device 2 in the embodiment of the present invention may be a network device Figure 1D In the following description, the second terminal device is described as a remote UE and the first terminal device is a relay UE.

[0196] S301. The remote UE performs data transmission with a network device.

[0197] S302: The network device sends an RRC message to the remote UE, and correspondingly, the remote UE receives the RRC message from the network device. The RRC message includes, for example, measurement configuration information, and the measurement configuration information is used by the remote UE to measure other UEs.

[0198] Alternatively, the network device may also send broadcast information to the remote UE, and correspondingly, the remote UE receives the broadcast information from the network device. The broadcast information is included in a system message, or in other broadcast messages. The broadcast information may include relevant information for the remote UE to select the relay UE, for example, measurement configuration information for configuring the remote UE to perform measurements for selecting the relay UE.

[0199] S303: The remote UE measures or selects other UEs. For example, the remote UE may send a discovery message to trigger other UEs to send discovery messages, so that the remote UE may measure the discovery messages from other UEs to complete the measurement or selection of other UEs. Figure 3 Take the remote UE measuring other UEs as an example.

[0200] The remote UE may measure other UEs by measuring discovery messages from other UEs, or may measure other information from other UEs, such as data signals from other UEs, etc., which is not limited here. The remote UE may select other UEs based on the measurement results.

[0201] S304: The remote UE sends a first result to the network device, and correspondingly, the network device receives the first result from the remote UE. The first result is, for example, a measurement result or a selection result. Figure 3 Take the first result as an example, which is a measurement result.

[0202] The measurement result is, for example, a measurement report obtained by the remote UE measuring at least one UE. The selection result is a selection result of the remote UE for the relay UE, for example, including the ID of the selected relay UE, and optionally, measurement information of the remote UE.

[0203] Among them, if the application scenario of the embodiment of the present application is switching from a non-direct link to a non-direct link, then the communication between the remote UE and the network device in S301~S304 is forwarded by the relay UE to which the remote UE is connected before switching the link, and the relay UE described below is the relay UE after the remote UE switches the link.

[0204] S305: The network device determines whether the remote UE performs path switching based on the measurement result or the selection result. If the network device determines that the remote UE performs path switching, S306 and S307 are executed; otherwise, S306 and S307 are not executed.

[0205] S306: The network device sends a first message to the relay UE, and correspondingly, the relay UE receives the first message from the network device. In the embodiment of the present application, the first message is, for example, an RRC reconfiguration message.

[0206] The RRC reconfiguration message may include configuration information, and the configuration information may be used to configure the relay UE to provide relay service for the remote UE. For example, the configuration information includes configuration information of the Uu port and configuration information of the side link, and the side link is the link between the remote UE and the relay UE, and the relay UE provides relay service for the remote UE through the side link. After the relay UE receives the RRC reconfiguration message, if the relay UE believes that it can provide relay service for the remote UE, the relay UE may be configured according to the configuration information included in the RRC reconfiguration message, for example, the Uu link and the side link may be configured. If the relay UE refuses to provide relay service for the remote UE, the relay UE does not have to be configured according to the configuration information included in the RRC reconfiguration message.

[0207] In the RRC reconfiguration message, the configuration related to relaying the relay UE and the Uu configuration of the relay UE's own service may be indicated separately, for example, through different information elements. For example, the Uu configuration of the relay UE's own service may be carried in the original information element, and the configuration related to relaying the relay UE may be carried in the newly added information element. Alternatively, additional indications may be added to the configuration related to relaying the relay UE to indicate that the configuration is a configuration for supporting the relay service.

[0208] S307: The relay UE sends a second message to the network device, and correspondingly, the network device receives the second message from the relay UE.

[0209] The second message may indicate that the relay UE configuration is complete, or indicate that the relay UE configuration fails. Alternatively, the second message may indicate that the relay UE can provide relay services, or indicate that the relay UE refuses to provide relay services. If the second message indicates that the relay UE configuration is complete, it can also be considered as an implicit indication that the relay UE can provide relay services, and if the second message indicates that the relay UE configuration fails, it can also be considered as an implicit indication that the relay UE refuses to provide relay services.

[0210] In an embodiment of the present application, the first message and the second message may be messages of the same type, for example, both are messages of the RRC reconfiguration type, the first message is an RRC reconfiguration message, and the second message is an RRC reconfiguration complete message. Alternatively, the first message and the second message may also be messages of different types, for example, the first message is an RRC reconfiguration message, and the second message is a sidelink UE information (SUI) message.

[0211] In addition, the second message may indicate success (including indicating that the relay UE configuration is complete, or indicating that the relay UE can provide relay services for the remote UE), or failure (including indicating that the relay UE configuration fails, or indicating that the relay UE refuses to provide relay services for the remote UE). Therefore, the second message may use the same type of message regardless of whether it indicates success or failure. For example, the second message is an RRC reconfiguration completion message, and the RRC reconfiguration completion message may indicate success or failure. If the RRC reconfiguration completion message indicates failure, a first information element may be added to the RRC reconfiguration completion message to indicate failure. After receiving the second message, the network device needs to parse the message body of the second message to determine success or failure. By indicating both success and failure using the same type of message, there is no need to use too many types of messages, which can simplify the network device's recognition process for different types of messages.

[0212] Alternatively, the second message may indicate success and failure, and different types of messages may be used. For example, when indicating success, the second message may be an RRC reconfiguration completion message, and when indicating failure, the second message may be a SUI message, or a failure information message, or may be a message newly added in an embodiment of the present application, for example, the second message is a message dedicated to indicating whether the terminal device provides a relay service. If this is the case, the network device does not need to parse the message body of the second message, but can determine success or failure based on the type information carried in the message header of the second message, which helps to reduce the workload of the network device.

[0213] For example, if the relay UE is configured according to the configuration information included in the RRC reconfiguration message, and the configuration is successful, and the relay UE determines that it can provide relay service, the second message may indicate that the relay UE configuration is complete, or indicate that the relay UE can provide relay service. For another example, if the relay UE is configured according to the configuration information included in the RRC reconfiguration message, and the configuration fails, the second message may indicate that the relay UE configuration fails, or indicate that the relay UE refuses to provide relay service. For another example, if the relay UE determines that some parameters in the configuration information included in the RRC reconfiguration message are not supported, the second message may indicate that the relay UE refuses to provide relay service. For another example, if the relay UE is not configured according to the configuration information included in the RRC reconfiguration message, and the relay UE determines to refuse to provide relay service, the second message may indicate that the relay UE refuses to provide relay service.

[0214] As an optional implementation, if the second message indicates that the relay UE configuration fails, or indicates that the relay UE refuses to provide relay services, the second message may also include a cause value, which may indicate the reason why the relay UE refuses to provide relay services, so that the network device can clearly understand the reason why the relay UE cannot provide relay services, so that the network device can take corresponding measures. Among them, the cause value may also implicitly indicate configuration failure, that is, the second message contains a cause value indication, which indicates configuration failure or rejection of relay services. If it does not contain, it indicates that the configuration is successful or indicates that the relay service can be supported. The reasons why the relay UE refuses to provide relay service may include one or more of the following: the relay UE does not support the configuration of the Uu port (i.e., does not support the configuration of the Uu port included in the configuration information), the relay UE does not support the configuration of the PC5 port (i.e., does not support the configuration of the PC5 port included in the configuration information), the relay UE fails to pass the admission control of the remote UE, the relay UE fails to configure according to the configuration information, the relay UE does not support the integrity protection algorithm configured by the configuration information, the relay UE does not support the 5G QoS identifier (5G QoS identifier, 5QI) or PC5 5G QoS identifier (PC5 5QI, PQI) configured by the configuration information, the relay UE cannot identify the quality of service (QoS) flow ID indicated by the configuration information, the relay UE does not support the network slice indicated by the configuration information, the relay UE is insufficient in power, the packet data convergence protocol (PDCP) of the relay UE is overloaded, or the relay UE does not support the computing capability indicated by the configuration information. For example, the reason why the relay UE refuses to provide relay service is that the relay UE does not support the configuration of the Uu port; or, the reason why the relay UE refuses to provide relay service is that the relay UE does not support the configuration of the PC5 port; or, the reason why the relay UE refuses to provide relay service is that the relay UE cannot identify the QoS flow ID indicated by the configuration information; or, the reason why the relay UE refuses to provide relay service is that the relay UE does not support the network slice indicated by the configuration information and the relay UE is insufficient in power, etc.

[0215] If the second message uses the same type of message regardless of indicating success or failure, then optionally, if the second message indicates failure, a first information element and a second information element may be added to the second message, the first information element may indicate failure, and the second information element is used to carry the cause value. For example, the second message is an RRC reconfiguration complete message, and the RRC reconfiguration complete message may indicate success or failure. If the RRC reconfiguration complete message indicates failure, a first information element and a second information element may be added to the RRC reconfiguration complete message, the first information element is used to indicate failure, and the second information element is used to carry the cause value.

[0216] Alternatively, if the second message indicates success and indicates failure using different types of messages, then optionally, if the second message indicates failure, a third information element may be added to the second message, and the third information element is used to carry the cause value. For example, when indicating success, the second message may be an RRC reconfiguration completion message, and when indicating failure, the second message may be a SUI message, and a third information element is added to the SUI message, and the third information element may carry the cause value. It can be seen that since the second message indicates success and indicates failure using different types of messages, the second message itself implicitly indicates failure. In this case, the number of new information elements added in the second message is relatively small, which is beneficial to saving transmission overhead.

[0217] S308: The relay UE does not initiate the RRC re-establishment process.

[0218] If the second message indicates that the relay UE configuration fails, or indicates that the relay UE refuses to provide relay service, S308 may be executed. In this case, since the network device already knows that the relay UE does not provide relay service, the relay UE may not initiate the RRC re-establishment process, but continue to communicate normally with the network device, thereby improving the service quality of the relay UE and reducing the resources consumed by the RRC re-establishment process. It can be understood that the relay UE not initiating the RRC re-establishment process may mean that the relay UE continues to communicate with the network device through the existing RRC connection.

[0219] The relay UE does not initiate the RRC re-establishment process, which can be manifested as the relay UE continues to apply the connection configuration between the relay UE and the network device before receiving the first message, or the connection state between the relay UE and the network device does not change. In other words, the connection configuration (or connection state) between the relay UE and the network device does not change, which can implicitly indicate that the relay UE does not initiate the RRC re-establishment.

[0220] If the second message indicates that the relay UE configuration is complete, or indicates that the relay UE can provide relay services, then the following may be executed: Figure 2 As shown in S207, after the remote UE is also configured, the relay UE can provide relay service.

[0221] Alternatively, even if the second message indicates that the relay UE configuration fails, or indicates that the relay UE refuses to provide the relay service, Figure 2 The S207 shown may have already occurred, for example, the network device has executed S207 before receiving the second message. In this case, the remote UE needs to determine that the path switch has failed. How the remote UE determines that the path switch has failed will be described in the following embodiments.

[0222] In the embodiment of the present application, regardless of whether the relay UE can provide the relay service, the relay UE can send a second message to the network device for notification, so that the network device can learn whether the relay UE can provide the relay service. Therefore, if the relay UE refuses to provide the relay service, since the network device can also learn this situation, the relay UE does not need to enter the RRC re-establishment process, but can continue to work normally under the network device, thereby improving the service quality of the relay UE and reducing the resources consumed by the RRC re-establishment process.

[0223] This application embodiment provides a second communication method, see Figure 4 , which is a flowchart of the method. The method involves a process of switching to a non-direct link. In the following description, the method is applied to Figure 1A to Figure 1D As an example, the network architecture shown in any of the figures in the present application is used. Figure 1A to Figure 1D For details about the devices in the communication method, please refer to the introduction of the first communication method.

[0224] S401. The remote UE performs data transmission with a network device.

[0225] S402: The network device sends an RRC message to the remote UE, and correspondingly, the remote UE receives the RRC message from the network device. The RRC message includes, for example, measurement configuration information, and the measurement configuration information is used by the remote UE to measure other UEs.

[0226] Alternatively, the network device may also send broadcast information to the remote UE, and accordingly, the remote UE receives the broadcast information from the network device, the broadcast information being included in, for example, a system message or other broadcast messages. The broadcast information includes relevant information for the remote UE to select the relay UE, for example, measurement configuration information for configuring the remote UE to perform measurements for selecting the relay UE.

[0227] S403: The remote UE measures or selects other UEs. For example, the remote UE may send a discovery message to trigger other UEs to send discovery messages, so that the remote UE may measure the discovery messages from other UEs to complete the measurement or selection of other UEs. Figure 4 Take the remote UE measuring other UEs as an example.

[0228] The remote UE may measure other UEs by measuring discovery messages from other UEs, or may measure other information from other UEs, such as data signals from other UEs, etc., which is not limited here. The remote UE may select other UEs based on the measurement results.

[0229] S404: The remote UE sends a first result to the network device, and correspondingly, the network device receives the first result from the remote UE. The first result is, for example, a measurement result or a selection result. Figure 4 Take the first result as an example, which is a measurement result.

[0230] The measurement result is, for example, a measurement report obtained by measuring at least one UE. The selection result is a selection result of the remote UE for the relay UE, for example, including the ID of the selected relay UE, and optionally, the measurement information of the remote UE.

[0231] Among them, if the application scenario of the embodiment of the present application is switching from a non-direct link to a non-direct link, then the communication between the remote UE and the network device in S401~S404 is forwarded by the relay UE to which the remote UE is connected before switching the link, and the relay UE described below is the relay UE after the remote UE switches the link.

[0232] S405: The network device determines whether the remote UE performs path switching based on the measurement result or the selection result. If the network device determines that the remote UE performs path switching, S406 is continued to be executed, otherwise, subsequent steps are not executed.

[0233] S406. The network device sends a first message to the relay UE, and correspondingly, the relay UE receives the first message from the network device. The first message may inquire whether the relay UE can provide relay service. In an embodiment of the present application, the first message is, for example, an RRC reconfiguration message, or the first message may also be a message newly added in an embodiment of the present application and dedicated to inquiring whether the terminal device can provide relay service.

[0234] In the embodiment of the present application, the network device does not first send configuration information to the relay UE, but first inquires the relay UE whether it can provide the relay service through the first message. If the relay UE can provide the relay service, the network device can then send configuration information to the relay UE to make the sending of the configuration information more effective. Alternatively, the network device sends one or more sets of configuration information to the relay UE to inquire whether the relay UE can provide the relay service according to the corresponding configuration.

[0235] As an optional implementation, the first message may include one or more of the following: an identifier of the remote UE, integrity protection algorithm information or integrity protection rate information, encryption algorithm information or encryption rate information, PQI or 5QI, QoS, network slice information, configuration information, or computing capability information. For example, the first message includes the identifier of the remote UE; or, the first message includes the PQI; or, the first message includes configuration information; or, the first message includes the identifier of the remote UE and network slice information, and so on. The first message may implicitly inquire whether the relay UE is capable of providing relay service by including one or more of the above items, or, in addition to including one or more of the above items, the first message also includes inquiry information, and the inquiry information is used to inquire whether the relay UE is capable of providing relay service. For an introduction to the configuration information, please refer to Figure 3 The embodiment shown.

[0236] Among them, integrity protection algorithm information or integrity protection rate information, encryption algorithm information or encryption rate information, configuration information, PQI or 5QI, QoS, network slice information, and computing power information, etc., are all required by the remote UE, or in other words, are the capabilities required for the relay UE to relay. The first message includes the relevant capability information required for the relay UE to relay, so that the relay UE can better judge whether the relay UE can provide relay service for the remote UE. For example, if the relay UE does not have the capability indicated by the first message, the relay UE can determine to refuse to provide relay service for the remote UE, which makes the judgment of the relay UE more accurate. In various embodiments of the present application, the UE identifier is, for example, the UE ID, and the UE ID is, for example, the UE layer 2 (lay 2) ID, or the ID of the application (application, APP) installed for the UE that requires relay service, etc.

[0237] S407: The relay UE sends a second message to the network device, and correspondingly, the network device receives the second message from the relay UE. The second message may indicate that the relay UE can provide a relay service, or indicate that the relay UE refuses to provide a relay service.

[0238] As an optional implementation, when the first message includes one or more sets of configuration information, if the second message indicates that the relay UE can provide relay service, the second message may also include first indication information, used to indicate the configuration information that the relay UE can provide relay service, that is, the first indication information indicates that the UE can provide relay service for one or several sets of configuration information.

[0239] As an optional implementation, if the second message indicates that the relay UE refuses to provide relay service, the second message may also include a reason value, which may indicate the reason why the relay UE refuses to provide relay service, so that the network device can clearly understand the reason why the relay UE cannot provide relay service, so that the network device can take corresponding measures. The reason why the relay UE refuses to provide relay service may include one or more of the following: the relay UE does not support the configuration of the Uu port (i.e., does not support the configuration of the Uu port included in the first message), the relay UE does not support the configuration of the PC5 port (i.e., does not support the configuration of the PC5 port included in the first message), the relay UE fails to pass the admission control of the remote UE, the relay UE does not support the integrity protection algorithm configured in the first message, the relay UE does not support the 5QI or PQI configured in the first message, the relay UE cannot identify the QoS flow ID indicated in the first message, the relay UE does not support the network slice indicated in the first message, the relay UE is insufficient in power, the relay UE's PDCP is overloaded, or the relay UE does not support the computing power indicated in the first message. For example, the reason why the relay UE refuses to provide relay service is that the relay UE does not support the configuration of the Uu port; or, the reason why the relay UE refuses to provide relay service is that the relay UE does not support the configuration of the PC5 port; or, the reason why the relay UE refuses to provide relay service is that the relay UE cannot identify the QoS flow ID indicated by the first message; or, the reason why the relay UE refuses to provide relay service is that the relay UE does not support the network slice indicated by the first message and the relay UE is insufficient in power, and so on.

[0240] For more information about S407, such as the implementation of the second message, please refer to Figure 3 S307 in the illustrated embodiment.

[0241] If the second message indicates that the relay UE can provide relay service, and the second message does not include configuration information, S408 and S409 may be continued to be executed; or, if the second message indicates that the relay UE can provide relay service, and the second message includes configuration information, S409 may be continued to be executed, and S408 does not need to be executed; and if the second message indicates that the relay UE refuses to provide relay service, S410 may be executed. In addition, if the second message indicates that the relay UE refuses to provide relay service, since the network device already knows that the relay UE does not provide relay service, the relay UE may not initiate the RRC re-establishment process, but continue to communicate normally with the network device, thereby improving the service quality of the relay UE and reducing the resources consumed by the RRC re-establishment process.

[0242] The relay UE does not initiate the RRC re-establishment process, which can be manifested as the relay UE continues to apply the connection configuration between the relay UE and the network device before receiving the first message, or the connection state between the relay UE and the network device does not change. In other words, the connection configuration (or connection state) between the relay UE and the network device does not change, which can implicitly indicate that the relay UE does not initiate the RRC re-establishment.

[0243] S408: The network device sends an RRC reconfiguration message to the relay UE, and correspondingly, the relay UE receives the RRC reconfiguration message from the network device. In order to distinguish it from other RRC reconfiguration messages, the RRC reconfiguration message in S408 is referred to as RRC reconfiguration message 1.

[0244] The RRC reconfiguration message 1 may include configuration information, for example, the configuration information is referred to as configuration information 1, and the configuration information 1 includes, for example, configuration information of the Uu port and configuration information of the sidelink, the sidelink being a link between the remote UE and the relay UE, and the relay UE providing a relay service for the remote UE through the sidelink. If the relay UE can provide a relay service for the remote UE, the network device may send the configuration information 1 to the relay UE, and after receiving the RRC reconfiguration message 1, the relay UE may perform configuration according to the configuration information 1, for example, the Uu link and the sidelink may be configured.

[0245] In the embodiment of the present application, although the relay UE sends the configuration information 1 after the network device determines that it can provide the relay service, the relay UE may still fail to configure, for example, the relay UE enters an area with a poor signal, or the relay UE still does not support some parameters included in the configuration information 1, and these parameters are not included in the first message. Then, if the relay UE configuration fails, the relay UE can send a second message to the network device, and the second message can indicate the configuration failure.

[0246] S409: The network device sends an RRC reconfiguration message to the remote UE, and the remote UE receives the RRC reconfiguration message from the network device. In order to distinguish it from other RRC reconfiguration messages, the RRC reconfiguration message in S409 is referred to as RRC reconfiguration message 2.

[0247] The RRC reconfiguration message 2 may include information configured by the base station for the remote UE, for example, the information included in the RRC reconfiguration message 2 is referred to as configuration information 2, and the configuration information 2 may include configuration information of the Uu port and configuration information of the sidelink. If the relay UE can provide relay service for the remote UE, the network device may send the configuration information 2 to the remote UE, and after receiving the RRC reconfiguration message 2, the remote UE may perform configuration according to the configuration information 2, for example, the Uu link and the sidelink may be configured.

[0248] After the remote UE and relay UE are configured, the relay UE can provide relay service for the remote UE, so that the remote UE can communicate with the base station through the relay UE.

[0249] S410: The relay UE does not initiate an RRC re-establishment process.

[0250] If the second message indicates that the relay UE configuration fails, or indicates that the relay UE refuses to provide relay service, S410 may be executed. In this case, since the network device already knows that the relay UE does not provide relay service, the relay UE may not initiate the RRC re-establishment process, but continue to communicate normally with the network device, thereby improving the service quality of the relay UE and reducing the resources consumed by the RRC re-establishment process.

[0251] For more information about S410, please refer to Figure 3 S308 in the illustrated embodiment.

[0252] In an embodiment of the present application, the network device can inquire whether the relay UE can provide relay service through a first message. For example, the first message is a message dedicated to inquiring whether the terminal device can provide relay service, and the second message is not an RRC reconfiguration completion message. Then, the embodiment of the present application is equivalent to not using the messages involved in the RRC re-establishment process, and does not change the existing RRC re-establishment process flow, which makes the technical solution of the embodiment of the present application better compatible with existing technologies.

[0253] Next, let's consider a question. According to the aforementioned processes, if the remote UE wants to implement path switch, it needs to measure other UEs. If the reporting conditions of the measurement report are met, the remote UE can send the measurement results to the network device. Regardless of whether the remote UE sends the measurement results to the network device, the measurement process may be continuous, which will consume more power of the remote UE. In addition, the remote UE generally performs measurements based on discovery messages, which requires other UEs (for example, relay UEs) to send discovery messages, so that the remote UE performs measurements based on discovery messages. However, it is possible that a UE will not continue to send discovery messages, so the remote needs to send discovery messages to other UEs first. The discovery message, for example, requests a corresponding service (such as a relay service). After other UEs receive the discovery message, if they can provide the service, they will send a discovery message to the remote UE, and the remote UE can perform measurements based on the received discovery message. It can be seen that in order to stimulate the relay UE to send a discovery message to the remote UE, the remote UE may need to send and receive discovery messages multiple times, which also consumes more resources.

[0254] In order to solve this problem, the embodiment of the present application provides a third communication method, through which measurement resources can be saved and the power of the remote UE can be saved. Figure 5 , which is a flowchart of the method. The method may involve a process of switching from a direct link to an indirect link, or a process of switching from a direct link to a direct link, or a process of switching from an indirect link to a direct link, or a process of switching from an indirect link to an indirect link. In the following introduction, the method is applied to Figure 1A to Figure 1D Take the network architecture shown in any of the accompanying drawings as an example.

[0255] If the technical solution provided in the embodiment of the present application is applied to Figure 1A to Figure 1D The second terminal device described below may be a network architecture shown in any of the figures in Figure 1A to Figure 1D If the technical solution provided in the embodiment of the present application is applied to the remote terminal device shown in any of the figures. Figure 1A The network architecture shown in FIG. 1 , the first terminal device described below may be Figure 1A The relay terminal device in the following description may be Figure 1A The access network device in; if the technical solution provided in the embodiment of the present application is applied to Figure 1B The network architecture shown in FIG. 1 , the first terminal device described below may be Figure 1B The relay terminal device 1 or the relay terminal device 2 in the embodiment, the network device described below may be Figure 1B The access network device in; if the technical solution provided in the embodiment of the present application is applied to Figure 1C The network architecture shown in FIG. 1 , the first terminal device described below may be Figure 1C The relay terminal device in the following description may be Figure 1C The access network device 1 or the access network device 2 in the embodiment of the present application is applied to Figure 1D The network architecture shown in FIG. 1 , the first terminal device described below may be Figure 1D The relay terminal device 1 in the embodiment of the present invention may be a network device Figure 1D The access network device 1 in the embodiment, or the first terminal device described below may be Figure 1D The relay terminal device 2 in the embodiment of the present invention may be a network device Figure 1D Access network device 2 in.

[0256] In addition, in the following description, the second terminal device is described as a remote UE and the first terminal device is a relay UE. Figure 5 The relay terminal device 1 and the relay terminal device 2 in the figure only indicate that there may be multiple UEs that can serve as relay UEs. When the remote UE performs measurement, it can measure multiple UEs.

[0257] S501. The remote UE performs data transmission with a network device.

[0258] S502: The network device sends an RRC message to the remote UE, and correspondingly, the remote UE receives the RRC message from the network device. The RRC message includes, for example, measurement configuration information, and the measurement configuration information is used by the remote UE to measure other UEs.

[0259] Alternatively, the network device may also send broadcast information to the remote UE, and correspondingly, the remote UE receives the broadcast information from the network device. The broadcast information is included in a system message, or in other broadcast messages. The broadcast information may include relevant information for the remote UE to select the relay UE, for example, measurement configuration information for configuring the remote UE to perform measurements for selecting the relay UE.

[0260] S503: The remote UE measures or selects other UEs. For example, the remote UE may send a discovery message to trigger other UEs to send discovery messages, so that the remote UE may measure the discovery messages from other UEs to complete the measurement or selection of other UEs. Figure 5 Take the remote UE measuring other UEs as an example.

[0261] The remote UE may measure other UEs by measuring discovery messages from other UEs, or may measure other information from other UEs, such as data signals from other UEs, etc., which is not limited here. The remote UE may select other UEs based on the measurement results.

[0262] S504: The remote UE sends a first result to the network device, and correspondingly, the network device receives the first result from the remote UE. The first result is, for example, a measurement result or a selection result. Figure 5 Take the first result as an example, which is a measurement result.

[0263] The measurement result includes, for example, a measurement report of the remote UE on at least one UE. The selection result is a selection result of the remote UE on the relay UE, for example, including the ID of the selected relay UE, and optionally, measurement information of the remote UE.

[0264] In the embodiment of the present application, after the remote UE sends the measurement result, if the first condition is not met, the remote UE does not perform the first operation, and the first operation can be regarded as an operation related to the measurement process.

[0265] The first operation may include one or more of the following: sending a discovery message, measuring other UEs, or sending a new first result to a network device (or sending the first result to the network device). For example, the first operation includes sending a discovery message; or, the first operation includes measuring other UEs; or, the first operation includes sending a new first result to a network device; or, the first operation includes sending a discovery message and measuring other UEs, and so on.

[0266] For example, if the first operation includes sending a discovery message, and does not include measuring other UEs, and does not include sending a new first result to the network device, then if the first condition is not met, the remote UE may not send a discovery message (for example, if the remote UE was sending a discovery message before, then if the first condition is not met, the remote UE stops sending the discovery message), but if the remote UE receives a discovery message from other UEs, the remote UE can still perform measurements based on the received discovery message and the measurement configuration information in S502 to obtain new measurement results. When the reporting conditions of the measurement report are met, the remote UE can also send a new first result to the network device. Alternatively, if the first operation includes measuring other UEs and does not include sending a discovery message or sending a new first result to the network device, then if the first condition is not met, the remote UE may not measure other UEs. Since there is no need to measure other UEs, the remote UE may not send a discovery message. Alternatively, the remote UE may send a discovery message, but even if it receives a discovery message from other UEs, the remote UE does not have to perform measurements. Since there is no need to measure other UEs, the remote UE will not obtain a measurement report and therefore does not have to send a new first result to the network device. Alternatively, if the first operation includes sending new measurement results to the network device, and does not include sending a discovery message or measuring other UEs, then if the first condition is not met, the remote UE may not send a discovery message, or may send a discovery message, and if the remote UE receives a discovery message from other UEs, the remote UE may still perform measurements based on the received discovery message, but the remote UE may not form a measurement report after the measurement, that is, it may measure but not obtain a measurement report, or if the remote UE performs measurement, it may also obtain a measurement report, but even if the reporting conditions for the measurement report are met, the remote UE does not send a measurement report to the network device.

[0267] In the embodiment of the present application, the first condition is related to the timer, and reference may be made to the introduction below.

[0268] S505: The remote UE starts a timer.

[0269] For example, when the remote UE completes executing S504, that is, when the measurement result is sent to the network device, the timer may be started. The first condition is satisfied, for example, when the timer times out, and the first condition is not satisfied, for example, when the timer does not time out.

[0270] S506: If the timer has not timed out, the remote UE does not perform the first operation.

[0271] That is, in the embodiment of the present application, if the timer has not timed out, the remote UE may not perform the first operation, because the remote UE has sent the measurement result to the network device, and the network device can determine whether the remote UE can perform path switch based on the measurement result, so even if the remote UE no longer performs measurement and no longer sends new measurement results to the network device, it has little effect on the judgment of the network device. In addition, in this way, the measurement process of the remote UE can be reduced, the resources consumed by the measurement process can be reduced, and the power of the remote UE can be saved.

[0272] S507: When the timer times out, the remote UE may perform the first operation.

[0273] If the timer times out, and the remote UE does not receive the configuration information from the network device (configure the remote UE to perform path switch), the remote UE may continue to perform the first operation to resend new measurement results to the network device. Of course, here it is just saying that if the timer times out, and the remote UE does not receive the configuration information from the network device (configure the remote UE to perform path switch), the remote UE can perform the first operation, but whether to perform the first operation depends on the implementation of the remote UE. This is just a possibility, not a restriction on the behavior of the remote UE. For example, if the timer times out, the remote UE can measure other UEs. When the reporting conditions of the measurement report are met, the remote UE sends new measurement results to the network device. If the network device determines that the remote UE can perform path switch based on the new measurement results, the network device can send configuration information to the remote UE and the relay UE (when switching to a non-direct link) respectively.

[0274] In an embodiment of the present application, after the remote UE sends the measurement result to the network device, it can start a timer. If the timer has not timed out, the remote UE does not need to perform measurement-related operations, so as to reduce the measurement process of the remote UE and save the resources required for the measurement process. Moreover, since the remote UE reduces related operations, the power of the remote UE can also be saved.

[0275] This application embodiment provides a fourth communication method, see Figure 6 , which is a flowchart of the method. The method may involve a process of switching from a direct link to an indirect link, or a process of switching from a direct link to a direct link, or a process of switching from an indirect link to a direct link, or a process of switching from an indirect link to an indirect link. In the following introduction, the method is applied to Figure 1A to Figure 1D As an example, the network architecture shown in any of the figures in the present application is used. Figure 1A to Figure 1D For details about which devices are used, please refer to the introduction to the third communication method.

[0276] In addition, in the following description, the second terminal device is described as a remote UE and the first terminal device is a relay UE. Figure 6 The relay terminal device 1 and the relay terminal device 2 in the figure only indicate that there may be multiple UEs that can serve as relay UEs, and the remote UE can measure multiple UEs when performing measurements. The relay UE as the first terminal device described below is, for example, the relay terminal device 1.

[0277] S601. A remote UE performs data transmission with a network device.

[0278] S602: The network device sends an RRC message to the remote UE, and correspondingly, the remote UE receives the RRC message from the network device. The RRC message includes, for example, measurement configuration information, and the measurement configuration information is used by the remote UE to measure other UEs.

[0279] Alternatively, the network device may also send broadcast information to the remote UE, and correspondingly, the remote UE receives the broadcast information from the network device. The broadcast information is included in a system message, or in other broadcast messages. The broadcast information may include relevant information for the remote UE to select the relay UE, for example, measurement configuration information for configuring the remote UE to perform measurements for selecting the relay UE.

[0280] S603: The remote UE measures or selects other UEs. For example, the remote UE may send a discovery message to trigger other UEs to send discovery messages, so that the remote UE may measure the discovery messages from other UEs to complete the measurement or selection of other UEs. Figure 6 Take the remote UE measuring other UEs as an example.

[0281] The remote UE may measure other UEs by measuring discovery messages from other UEs, or may measure other information from other UEs, such as data signals from other UEs, etc., which is not limited here. The remote UE may select other UEs based on the measurement results.

[0282] S604: The remote UE sends a first result to the network device, and correspondingly, the network device receives the first result from the remote UE. The first result is, for example, a measurement result or a selection result. Figure 6 Take the first result as an example, which is a measurement result.

[0283] The measurement result includes, for example, a measurement report of the remote UE on at least one UE. The selection result is a selection result of the remote UE on the relay UE, for example, including the ID of the selected relay UE, and optionally, measurement information of the remote UE.

[0284] In the embodiment of the present application, after the remote UE sends the first result, if the first condition is not met, the remote UE does not perform the first operation, and the first operation can be regarded as an operation related to the measurement process. For an introduction to the first operation, please refer to Figure 3 The embodiment shown.

[0285] In the embodiment of the present application, the first condition is related to a message from a network device, and reference may be made to the introduction below.

[0286] S605: The network device determines whether the remote UE performs path switching based on the measurement result or the selection result. If the network device determines that the remote UE performs path switching, S606 and S607 are executed, or S608 to S609 are executed; or, if the network device determines that the remote UE does not perform path switching, subsequent steps are not executed, or S610 may be executed.

[0287] S606: The network device sends a first message to the relay UE, and correspondingly, the relay UE receives the first message from the network device.

[0288] For more information about S606, please refer to Figure 3 S306 in the illustrated embodiment.

[0289] S607: The relay UE sends a second message to the network device, and correspondingly, the network device receives the second message from the relay UE.

[0290] The second message may indicate that the relay UE configuration is complete, or indicate that the relay UE configuration fails. Alternatively, the second message may indicate that the relay UE can provide relay service, or indicate that the relay UE refuses to provide relay service. For example, in an embodiment of the present application, the second message indicates that the relay UE configuration fails, or indicates that the relay UE refuses to provide relay service.

[0291] For more information about S607, please refer to Figure 3 S307 in the illustrated embodiment.

[0292] S608: The network device sends a first message to the relay UE, and correspondingly, the relay UE receives the first message from the network device. The first message may inquire whether the relay UE can provide a relay service.

[0293] For more information about S608, please refer to Figure 4 S406 in the illustrated embodiment.

[0294] S609: The relay UE sends a second message to the network device, and correspondingly, the network device receives the second message from the relay UE.

[0295] The second message may indicate that the relay UE configuration is complete, or indicate that the relay UE configuration fails. Alternatively, the second message may indicate that the relay UE can provide relay service, or indicate that the relay UE refuses to provide relay service. For example, in an embodiment of the present application, the second message indicates that the relay UE configuration fails, or indicates that the relay UE refuses to provide relay service.

[0296] For more information about S609, please refer to Figure 4 S407 in the embodiment shown.

[0297] Among them, S606-S607 and S608-S609 are two parallel processes, and only one of the processes needs to be executed.

[0298] S610: The network device sends a third message to the remote UE, and accordingly, the remote UE receives the third message from the network device. The third message may instruct the relay UE to refuse to provide relay service, or instruct to reselect a UE that can provide relay service. The third message may be, for example, an RRC message, or may be other messages.

[0299] S611. The remote UE performs a first operation.

[0300] In an embodiment of the present application, if the remote UE receives a third message from the network device, it is considered that the first condition is met, and the first operation can be performed. If the third message from the network device is not received, it is considered that the first condition is not met. When the first condition is not met, the remote UE does not have to perform the first operation to reduce the measurement process of the remote UE and save the resources required for the measurement process. Since the remote UE reduces measurement-related operations, the power of the remote UE can also be saved. When the first condition is met, the remote UE learns that it needs to reselect a UE that can provide relay services, and the remote UE can trigger the measurement process to select other relay UEs.

[0301] As an optional implementation, after executing S604, or before executing S604, the remote UE may also send a fourth message to the network device, and the fourth message may indicate an energy saving requirement, which can be understood as indicating that the fourth message indicates that the remote UE has an energy saving requirement. Then, after the network device receives the fourth message, it can be determined that the remote UE has an energy saving requirement. Then optionally, the network device may also send the first information to the remote UE, and accordingly, the remote UE receives the first information from the network device. The first information may be included in the third message, or may also be sent through other messages. The first information may include information of M UEs, and the UE information is, for example, an identifier of the UE, and M is a positive integer. The M UEs are UEs that do not need to be measured, or are UEs that refuse to provide relay services. For the remote UE, if the first information is received, the remote UE does not need to measure the M UEs, saving the measurement process of the remote UE and reducing the power consumption of the remote UE to meet the energy saving requirements of the remote UE.

[0302] Optionally, the fourth message may also include information of N UEs, where the information of the UE is, for example, an identifier of the UE, and N is a positive integer. For example, the N UEs are UEs that refuse to provide relay services. For example, the remote UE determines based on historical information that N UEs have refused to provide relay services for the remote UE. The remote UE may add the information of the N UEs to a blacklist and send the blacklist to the network device. Thus, when the network device configures the remote UE for measurement, it may consider not configuring the remote UE to measure the N UEs to reduce the invalid measurement process of the remote UE. If the fourth message includes information of N UEs, and the network device sends the first information, then the M UEs may be determined by the network device based on the N UEs and some other factors. For example, the M UEs are N UEs, and M=N at this time, or the M UEs have no intersection with the N UEs, or the M UEs have an intersection with the N UEs, but are not exactly the same.

[0303] In an embodiment of the present application, after the remote UE sends the measurement result to the network device, if the remote UE does not receive the third message from the network device, the remote UE does not need to perform measurement-related operations, so as to reduce the measurement process of the remote UE and save the resources required for the measurement process. Moreover, since the remote UE reduces the related operations, the power of the remote UE can also be saved.

[0304] Next, consider another problem. At present, when the remote UE performs path switch, it may succeed or fail. However, in the case where the remote UE fails to perform path switch, the remote UE cannot judge, that is, the remote UE cannot determine under what circumstances the path switch fails, which may cause the remote UE to be unable to continue its work.

[0305] To this end, the embodiment of the present application provides a fifth communication method, through which the remote UE can determine under what circumstances the path switch fails, so that the work of the remote UE can continue. Figure 7 , which is a flowchart of the method. The method may involve a process of switching from a non-direct link to a direct link. In the following introduction, the method is applied to Figure 1A or Figure 1C The network architecture shown is taken as an example.

[0306] If the technical solution provided in the embodiment of the present application is applied to Figure 1AThe network architecture shown in FIG. 1 shows that the source network device before the remoteUE performs the path switch and the target network device after the path switch are the same network device. Then the first terminal device described below can be Figure 1A The relay terminal device in the following description may be a second terminal device Figure 1A The remote terminal device in the following description can be Figure 1A The access network device in the embodiment of the present application is both a source network device and a target network device; if the technical solution provided in the embodiment of the present application is applied to Figure 1C The network architecture shown in FIG. 1 shows that the source network device before the remote UE performs the path switch and the target network device after the path switch are different network devices. Then the first terminal device described below can be Figure 1C The relay terminal device in the following description may be a second terminal device Figure 1C The remote terminal device in the example, the network device described below (or referred to as the first network device, the first network device being the source network device) may be Figure 1C The access network device 1 in the text, in addition, the target network device is also involved below, which can be called the second network device, but Figure 1C Access network device 2 in.

[0307] In addition, in the following description, the second terminal device is a remote UE and the first terminal device is a relay UE. In addition, in the embodiment of the present application, the source network device and the target network device are different network devices.

[0308] S701. The remote UE performs data transmission with a source network device.

[0309] S702: The source network device sends an RRC message to the remote UE, and correspondingly, the remote UE receives the RRC message from the source network device. The RRC message includes, for example, measurement configuration information, and the measurement configuration information is used by the remote UE to measure a reference signal from the source network device.

[0310] S703: The remote UE measures a reference signal from the network device.

[0311] For example, the remote UE receives a synchronization signal block (SSB) or a channel state information reference signal (CSI-RS) from the source network device, and the remote UE can measure the strength of the received signal to complete the measurement of the source network device. In addition, the remote UE can also measure the target network device, for example, the remote UE receives an SSB or CSI-RS from the target network device, and the remote UE can measure the strength of the received signal to complete the measurement of the target network device.

[0312] S704: The remote UE sends a measurement result to the source network device, and correspondingly, the source network device receives the measurement result from the remote UE. The measurement result, for example, includes a measurement report obtained by measuring at least one frequency point or cell.

[0313] Among them, the communication between the remote UE and the source network device in S701 to S704 is forwarded by the relay UE.

[0314] S705. The source network device makes a handover decision. The source network device determines whether the remote UE can perform a path switch based on the measurement result. In the embodiment of the present application, the source network device determines whether the remote UE can switch from the relay UE to the target network device based on the measurement result. If the source network device determines that the remote UE can switch from the relay UE to the target network device, S706 is executed.

[0315] S706: The source network device sends a handover request message to the target network device, and correspondingly, the target network device receives the handover request message from the source network device. The handover request message may indicate that the remote UE will be handed over to the target network device.

[0316] S707: The target network device sends a handover request acknowledgement message to the source network device. Correspondingly, the source network device receives the handover request acknowledgement message from the target network device. The handover request acknowledgement message may indicate that the remote UE is allowed to handover to the target network device, or indicate that the remote UE is not allowed to handover to the target network device.

[0317] If the handover request confirmation message indicates that the remote UE is allowed to handover to the target network device, then continue to execute S708, otherwise, do not execute subsequent steps.

[0318] If the target network device and the source network device are the same network device, after S705 , there is no need to execute S706 to S707 , and S708 is continued to be executed.

[0319] S708: The source network device sends an RRC reconfiguration message to the remote UE. Correspondingly, the remote UE receives the RRC reconfiguration message from the source network device.

[0320] The RRC reconfiguration message may include configuration information, and the configuration information may configure the remote UE to switch to the target network device, for example, the configuration information may include the configuration information of the Uu port. The configuration information of the Uu port may include the identifier of the target network device, the user ID (eg, C-RNTI) used by the relay UE when accessing, and the timer duration for determining whether the access is successful, such as T304. Optionally, it may also include the random access resource configuration and non-competitive preamble configuration for the relay UE to access the network device.

[0321] S709: The remote UE performs a path switch according to the configuration information. For example, the remote UE performs configuration according to the configuration information, and the remote UE initiates a random access to the target network device. If the remote UE random access succeeds, the remote UE is successfully switched to the target network device.

[0322] If the first condition is met and the remote UE successfully accesses the target network device, the remote UE may determine that the path switch is successful; otherwise, if the first condition is not met and the remote UE fails to access the target network device, the remote UE determines that the path switch fails.

[0323] In the embodiment of the present application, the first condition may be related to a timer, and reference may be made to the introduction below.

[0324] S710. The remote UE starts a timer.

[0325] For example, after executing S708, or after receiving the configuration information from the source network device, the remote UE may start a timer. The timer may be T304, or may be another newly introduced timer, which is not limited here.

[0326] S711. The remote UE initiates random access to the target network device.

[0327] Among them, if the remote UE successfully accesses the target network device before the timer times out, it is determined that the pathswitch is successful, and if the remote UE has not successfully accessed the target network device when the timer times out, it is determined that the pathswitch has failed. The embodiment of the present application determines whether the path switch is successful by a timer, which is relatively simple and easy to implement. The timing duration of the timer can be determined by the remote UE. For example, the remote UE can determine the time of accessing the network device based on historical information, and determine the time as the timing duration of the timer. Alternatively, the timing duration of the timer can also be configured by the network device in S708 and notified to the remote UE, or the timing duration of the timer can also be specified by a protocol. If the random access is successful, the timer can be stopped to avoid timer timeout.

[0328] If the remote UE successfully accesses the target network device before the timer expires, the remote UE can communicate normally under the target network device without executing the subsequent steps. If the remote UE has not successfully accessed the target network device when the timer expires, the following steps can be continued.

[0329] S712, the remote UE sends failure information to the source network device through the first path, and correspondingly, the source network device receives failure information from the remote UE through the first path. The failure information may indicate a path switch failure. The failure information is, for example, an RRC message, for example, the failure information may be a failure information message, a master cell group failure information (MCG failure information) message, an RRC reconfiguration complete message, or a UE information response message, or may also be other newly added RRC messages, which are not limited here.

[0330] The first path is the communication path between the remote UE and the source network device before the path switch is performed. Since the embodiment of the present application takes the scenario of switching from a non-direct link to a direct link as an example, the first path is the communication path of the remote UE connecting to the source network device through the relay UE, that is, the first path is: remote UE-relayUE-source network device.

[0331] If the remote UE has not disconnected the connection with the source network device through the first path before the path switch is successfully performed, the remote UE may execute S712. After the source network device receives the failure information, the remote UE and the source network device may continue to communicate through the first path, that is, the remote UE may continue to communicate through the original communication path because the original communication path has not been disconnected, and there is no need to reselect the communication path, or the remote UE will not initiate the RRC connection re-establishment process, thereby improving the service continuity of the remote UE.

[0332] S713: The remote UE sends an RRC connection re-establishment request message to the source network device through the first path. Correspondingly, the source network device receives the RRC connection re-establishment request message from the remote UE.

[0333] Among them, S712 and S713 are parallel steps, and only one of them needs to be executed. If the remote UE has not disconnected the connection with the source network device through the first path before the path switch is successfully performed, the remote UE can also execute S713 to re-establish the RRC connection under the source network device to communicate with the source network device through the new connection.

[0334] S714: The remote UE performs cell reselection.

[0335] The remote UE may enter an RRC idle state, and perform cell reselection in the RRC idle state. For example, the cell to which the remote UE reselects is referred to as the first cell.

[0336] S715. The remote UE initiates an RRC connection re-establishment process in the first cell, or initiates an RRC connection establishment process in the first cell.

[0337] If the first cell stores the context of the remote UE, the remote UE can initiate the RRC connection re-establishment process in the first cell, and if the first cell does not store the context of the remote UE, the remote UE can initiate the RRC connection establishment process in the first cell. For example, the remote UE can initiate the RRC connection re-establishment process in the first cell. If the first cell stores the context of the remote UE, the probability of success of the RRC connection re-establishment process of the remote UE is relatively high. If the first cell does not store the context of the remote UE and the context of the remote UE cannot be obtained through the interface of the network device, the RRC connection re-establishment process of the remote UE may fail. If the RRC connection re-establishment process of the remote UE fails, the remote UE initiates the RRC connection establishment process in the first cell again. Alternatively, the remote UE can also directly initiate the RRC connection establishment process in the first cell to reduce the possibility of RRC re-establishment failure due to the fact that the first cell does not store the context of the remote UE.

[0338] Among them, S712, S713, and S714-S715, these three solutions are parallel, and only one of them needs to be executed.

[0339] In the embodiment of the present application, the remote UE can determine the success or failure of the path switch according to the timer, and the determination method is relatively simple and easy to implement. Even for UEs with lower capabilities, the technical solution of the embodiment of the present application can be applied. Moreover, if the path switch fails, the remote UE can take corresponding actions, such as continuing to communicate under the source network device, or entering a new cell through cell reselection, so as to restore the service of the remote UE as soon as possible and improve the continuity of the service.

[0340] The embodiment of the present application provides a sixth communication method, through which the remote UE can also determine under what circumstances the path switch fails, so that the work of the remote UE can continue. Figure 8 , which is a flow chart of the method. The method may involve a process of switching from a non-direct link to a non-direct link, or may involve a process of switching from a direct link to a non-direct link. In the following introduction, the method is applied to Figure 1A to Figure 1D Take the network architecture shown in any of the accompanying drawings as an example.

[0341] If the technical solution provided in the embodiment of the present application is applied to Figure 1AThe network architecture shown in FIG. 1 shows that the source network device before the remoteUE performs the path switch and the target network device after the path switch are the same network device. Then the first terminal device described below can be Figure 1A The relay terminal device in the following description may be a second terminal device Figure 1A The remote terminal device in the following description can be Figure 1A The access network device in the embodiment of the present application is both a source network device and a target network device; if the technical solution provided in the embodiment of the present application is applied to Figure 1B The network architecture shown in FIG. 1 shows that the source network device before the remote UE performs the path switch and the target network device after the path switch are the same network device. Then the first terminal device described below can be Figure 1B The relay terminal device 1 or the relay terminal device 2 in the embodiment, the second terminal device described below may be Figure 1B The remote terminal device in the following description can be Figure 1B The access network device in the embodiment of the present application is both a source network device and a target network device; if the technical solution provided in the embodiment of the present application is applied to Figure 1C The network architecture shown in FIG. 1 shows that the source network device before the remote UE performs the path switch and the target network device after the path switch are different network devices. Then the first terminal device described below may be Figure 1C The relay terminal device in the following description may be a second terminal device Figure 1C The remote terminal device in the example, the network device described below (or referred to as the first network device, the first network device being the source network device) may be Figure 1C The access network device 1 in the text, in addition, the target network device is also referred to below, which can be called the second network device, which can be Figure 1C The access network device 2 in the source network device may be Figure 1C The access network device 2 in the target network device can be Figure 1C The access network device 1 in the embodiment of the present application is applied to Figure 1D The network architecture shown in FIG. 1 shows that the source network device before the remote UE performs the path switch and the target network device after the path switch are different network devices. Then the first terminal device described below may be Figure 1D The relay terminal device 1 in the embodiment, the second terminal device described below may be Figure 1DThe remote terminal device in the example, the network device described below (or referred to as the first network device, the first network device being the source network device) may be Figure 1D The access network device 1 in the text, in addition, the target network device is also referred to below, which can be called the second network device, which can be Figure 1D The access network device 2 in the embodiment, or the first terminal device may be Figure 1D The relay terminal device 2 in the source network device can be Figure 1D The access network device 2 in the target network device can be Figure 1D Access network device 1 in.

[0342] In addition, in the following description, the second terminal device is a remote UE and the first terminal device is a relay UE. In addition, in the embodiment of the present application, the source network device and the target network device are different network devices.

[0343] S801. A remote UE performs data transmission with a source network device.

[0344] S802: The source network device sends an RRC message to the remote UE, and correspondingly, the remote UE receives the RRC message from the source network device. The RRC message includes, for example, measurement configuration information, and the measurement configuration information is used by the remote UE to measure other UEs.

[0345] Alternatively, the network device may also send broadcast information to the remote UE, and correspondingly, the remote UE receives the broadcast information from the network device. The broadcast information is included in a system message, or in other broadcast messages. The broadcast information may include relevant information for the remote UE to select the relay UE, for example, measurement configuration information for configuring the remote UE to perform measurements for selecting the relay UE.

[0346] S803: The remote UE measures or selects other UEs. For example, the remote UE may send a discovery message to trigger other UEs to send discovery messages, so that the remote UE may measure the discovery messages from other UEs to complete the measurement or selection of other UEs. Figure 8 Take the remote UE measuring other UEs as an example.

[0347] The remote UE may measure other UEs by measuring discovery messages from other UEs, or may measure other information from other UEs, such as data signals from other UEs, etc., which is not limited here. The remote UE may select other UEs based on the measurement results.

[0348] S804: The remote UE sends a first result to the network device, and correspondingly, the network device receives the first result from the remote UE. The first result is, for example, a measurement result or a selection result. Figure 8 Take the first result as an example, which is a measurement result.

[0349] The measurement result includes, for example, a measurement report of the remote UE on at least one UE. The selection result is a selection result of the remote UE on the relay UE, for example, including the ID of the selected relay UE, and optionally, measurement information of the remote UE.

[0350] Among them, if the application scenario of the embodiment of the present application is switching from a non-direct link to a non-direct link, then the communication between the remote UE and the network device in S801~S804 is forwarded by the relay UE to which the remote UE is connected before switching the link, and the relay UE described below is the relay UE after the remote UE switches the link.

[0351] S805. The source network device makes a handover decision. The source network device determines whether the remote UE can perform a path switch based on the measurement result. In the embodiment of the present application, the source network device determines whether the remote UE can switch from the relay UE to the target network device based on the measurement result. If the source network device determines that the remote UE can switch from the relay UE to the target network device, S806 is executed.

[0352] S806. The source network device sends a handover request message to the target network device, and accordingly, the target network device receives the handover request message from the source network device. The handover request message may indicate that the remote UE will be handed over to the target network device, which is the target network device serving the relay UE. Because the remote UE wants to switch to communicating through the relay UE, the source network device requests the target network device where the relay UE is located to hand over.

[0353] S807: The target network device sends an RRC reconfiguration message to the relay UE, and correspondingly, the relay UE receives the RRC reconfiguration message from the target network device. For example, the RRC reconfiguration message is referred to as RRC reconfiguration message 1.

[0354] The RRC reconfiguration message includes, for example, configuration information. The RRC reconfiguration message implements, for example Figure 3 Alternatively, the RRC reconfiguration message, for example, inquires whether the relay UE can provide the relay service. The RRC reconfiguration message, for example, implements Figure 4 Function of the first message in the embodiment shown.

[0355] S808: The relay UE sends a second message to the target network device. Correspondingly, the target network device receives the second message from the relay UE. Figure 3 The function of the first message in the embodiment shown in FIG. 8 is realized by the second message of S808. Figure 3 Function of the second message in the embodiment shown; or, if the RRC reconfiguration message in S807 implements Figure 4 The function of the first message in the embodiment shown in FIG. 8 is realized by the second message of S808. Figure 4 Function of the second message in the embodiment shown. S808 may be an optional step and is not sent. The relay UE confirms that the reconfiguration fails and triggers the relay UE to enter the RRC connection reestablishment process.

[0356] In the embodiment of the present application, for example, the second message indicates a configuration failure, or instructs the relay UE to refuse to provide a relay service. Figure 3 S306 or S307 in the embodiment shown, or Figure 4 S406 or S407 in the embodiment shown.

[0357] S809: The target network device sends a handover request acknowledgement message to the source network device. Correspondingly, the source network device receives the handover request acknowledgement message from the target network device.

[0358] The handover request confirmation message may indicate that the remote UE is allowed to switch to the target network device, or indicate that the remote UE is not allowed to switch to the target network device. In the embodiment of the present application, since the second message indicates a configuration failure, or indicates that the relay UE refuses to provide relay service, the handover request confirmation message may indicate that the remote UE is not allowed to switch to the target network device.

[0359] Among them, S807 is after S806, and S810 is after S809, but there is no restriction on the order of S807 and S809. For example, the target network device can execute S809 after configuring the relay UE, or it can execute S809 first and then inquire or configure the relayUE. If the target network device and the source network device are the same network device, there is no need to execute S806 and S809.

[0360] S810: The source network device sends an RRC reconfiguration message to the remote UE, and correspondingly, the remote UE receives the RRC reconfiguration message from the source network device. For example, the RRC reconfiguration message is called RRC reconfiguration message 2.

[0361] The RRC reconfiguration message may include configuration information, and the configuration information may configure the remote UE to switch to a non-direct path and communicate with the target network device through the relay UE. For example, the configuration information may include the configuration information of the Uu port, and the configuration information of the Uu port may include the Uu configuration information of the relay UE. The configuration information may also include the user ID accessed by the relay UE (for example, the ID is a cell-radio network temporary identifier (C-RNTI)), and may also include the random access resource configuration and non-competitive preamble configuration of the relay UE accessing the network device. For another example, the configuration information may include the configuration information of the remote UE, and the configuration information of the remote UE may include the user ID of the remote UE (for example, C-RNTI), and may also include the configuration information of the PC5 of the remote UE or relay UE, for example, the configuration information of the PC5 of the remote UE or relay UE includes one or more of the following: configuration information of the PC5 radio link control (radio link control, RLC), the logical channel identifier (logic channel ID, LCID) corresponding to the PC5 RLC entity, or the association relationship between the LCID corresponding to the PC5 RLC entity and the data radio bearer (data radiobearer, DRB) ID. For another example, the configuration information may include timer related information, and the timer can be used by the remote UE to determine whether the path switching fails. The timer is, for example, timer T304, or it may be other newly introduced timers, which are not limited here. The source network device can choose to configure different timers according to whether the remote UE performs path switching or ordinary switching. For example, if the remote UE is to perform a path switch, a new timer can be configured for it, and if the remote UE is to perform a normal switch, timer T304 can be configured for it. Alternatively, the source network device can also configure timer T304 for the remote UE through a normal RRC reconfiguration message, without having to configure it through a synchronous RRC reconfiguration (RRC reconfiguration with sync) message. The source network device can indicate that the remote UE needs to switch to a non-direct path (i.e., a path that communicates with the network through a relay) by adding a new information element, such as a fourth information element, to the RRC reconfiguration message, and the configured timer can be included in the fourth information element. The ID of the above remote UE can also be included in the fourth information element, which is not limited here.The timer-related information included in the configuration information may include the duration of the timer, or include the duration of the timer and the offset duration, or include the offset duration. The offset duration may be determined according to the state of the relay UE. For example, the setting of the offset duration may be different for the three situations where the relay UE is in the RRC idle state, the RRC inactive state, and the RRC connected state. For example, when the relay UE is in the RRC connected state, the offset duration may be set shorter, or even 0. If the remote UE switches the path to access the network through the relay UE in the RRC connected state, the relay UE in the RRC connected state does not need to perform the random access process of the Uu, and if the remote UE switches the path to access the network through the relay UE in the RRC idle state or the RRC inactive state, the relay UE in the RRC idle state or the RRC inactive state needs to perform the random access process of the Uu port. Therefore, when the path switched by the remote UE is different, the duration for the remote UE to establish a connection with the network device may also be different. For example, one way for the remote UE to determine the duration of the timer used to determine whether the path switch fails is that the duration of the timer received by the remote UE is X, and if the relay UE is in the RRC idle state, the offset duration is Y, Y is greater than 0, and if the relay UE is in the RRC connected state, the offset duration is 0. In the case where the remote UE switches to access the network through the relay UE, if the relay UE is in the RRC idle state, the duration of the timer used by the remote UE to determine whether the path switch fails will be set to X+Y, and if the relay UE is in the RRC connected state, the duration of the timer used by the remote UE to determine whether the path switch fails will be set to X+0. In other words, the offset duration can be determined according to the state of the relay UE, thereby effectively reducing the time that the remote UE needs to wait when the relay UE switched to the RRC connected state fails, so that the remote UE can enter the state recovery process as soon as possible.

[0362] S811, the remote UE performs path switch according to the configuration information. For example, the remote UE performs configuration according to the configuration information, and the remote UE requests a connection from the relay UE. If the remote UE successfully establishes a connection with the relay UE, the remote UE successfully switches to communicating with the network through the relay UE.

[0363] If the first condition is met and the remote UE successfully establishes a connection with the relay UE, the remote UE may determine that the path switch is successful; otherwise, if the first condition is not met and the remote UE fails to establish a connection with the relay UE, the remote UE determines that the path switch fails.

[0364] In the embodiment of the present application, the first condition may be related to a timer, and reference may be made to the introduction below.

[0365] S812. The remote UE starts a timer.

[0366] For example, after executing S810, or in other words, after receiving the configuration information from the source network device (the configuration information is, for example, included in an RRC reconfiguration message that does not carry a synchronization reconfiguration information element, or included in an RRC reconfiguration message that carries a fourth information element, or included in an RRC reconfiguration message that carries a synchronization reconfiguration information element), the remote UE can start a timer. The timer can be timer T304, or it can also be other newly introduced timers, which are not limited here. The timing duration and / or offset duration of the timer can be configured through the RRC reconfiguration message in S810, or through a broadcast message, or by the relay UE. The remote UE can determine the timing duration of the timer based on the configured timing duration and / or offset duration of the timer. For example, the remote UE directly determines the timing duration of the timer according to the RRC reconfiguration message; for another example, the remote UE determines the timing duration of the timer according to the broadcast message; for another example, the remote UE determines the timing duration of the timer according to the timing duration configured by the broadcast message and the offset duration configured by the RRC reconfiguration message, for example, the timing duration of the timer is the sum of the timing duration configured by the broadcast message and the offset duration configured by the RRC reconfiguration message; for another example, the remote UE determines the timing duration of the timer according to the timing duration configured by the RRC reconfiguration message or the broadcast message, and according to the offset duration configured by the PC5RRC message received from the relay UE, for example, the timing duration of the timer is the sum of the timing duration configured by the RRC reconfiguration message or the broadcast message and the offset duration configured by the PC5RRC message. Since the setting of the offset duration is based on the status of the relay UE, it can more reasonably help the remote UE determine the required waiting time to determine whether a path switch failure occurs.

[0367] S813, the remote UE requests the relay UE to establish a connection. For example, the remote UE sends a connection establishment request to the relay UE, and after receiving the connection establishment request, if the relay UE replies with a connection establishment response message to the remote UE, and the connection establishment response message indicates that the connection is allowed to be established, then the connection between the remote UE and the relay UE is successfully established; and if after receiving the connection establishment request, the relay UE replies with a connection establishment response message to the remote UE, and the connection establishment response message indicates that the connection is not allowed to be established, or the relay UE does not reply to the connection establishment response message, then the connection between the remote UE and the relay UE fails to be established.

[0368] The timer related to the first condition, that is, the timer started in S812, can be stopped when some conditions are met. For example, the timer can be stopped when any of the first stop condition, the second stop condition, the third stop condition, or the fourth stop condition is met. These stop conditions are briefly introduced below.

[0369] For example, the first stop condition is that the PC5RRC connection between the remote UE and the relay UE is successfully established, then the timer can be stopped. For example, the remote UE receives a connection establishment response message replied by the remote UE, and the connection establishment response message indicates that the connection establishment is allowed, then the timer can be stopped.

[0370] Among them, if the remote UE successfully establishes a connection with the relay UE before the timer expires, it is determined that the pathswitch is successful, and if the remote UE has not established a connection with the relay UE when the timer expires, it is determined that the pathswitch fails. The embodiment of the present application determines whether the path switch is successful by a timer, which is relatively simple and easy to implement. The timing duration of the timer can be determined by the remote UE or refer to the description of S810 and S812. For example, the remote UE can determine the time to establish a connection with other UEs based on historical information, and determine the time as the timing duration of the timer. Alternatively, the timing duration of the timer can also be configured by the network device and notified to the remote UE, or the timing duration of the timer can also be specified by a protocol.

[0371] If the remote UE successfully establishes a connection with the relay UE before the timer expires, the remote UE can communicate normally through the relay UE without executing the subsequent steps. If the remote UE has not established a connection with the relay UE when the timer expires, the subsequent steps can be continued.

[0372] For example, the second stop condition is that the RRC layer of the remote UE sends an RRC reconfiguration complete message to the bottom layer of the remote UE, and the RRC layer receives confirmation feedback from the bottom layer. The bottom layer here is, for example, the packet data convergence protocol (PDCP) layer, the radio link control (RLC) layer or the media access control (MAC) layer. Among them, if the timer of the remote UE times out, it is determined that the path switch has failed. The embodiment of the present application determines whether the path switch is successful through a timer, which is relatively simple and easy to implement. The setting method of the timer is similar to the setting method under the first stop condition, and will not be repeated here. If the timer of the remote UE times out, the subsequent steps can be continued.

[0373] For example, the third stop condition is that the remote UE receives a confirmation indication from the relay UE, and the confirmation indication is, for example, sent by the source network device through the relay UE. Among them, if the timer of the remote UE times out, it is determined that the pathswitch has failed. The embodiment of the present application determines whether the path switch is successful by a timer, which is relatively simple and easy to implement. The setting method of the timer is similar to the setting method under the first stop condition, and will not be repeated here. If the timer of the remoteUE times out, the subsequent steps can be continued.

[0374] For example, the fourth stop condition is that the remote UE receives indication information from the relay UE, and the indication information is carried by a PC5RRC message, for example, and the indication information is used to instruct the remote UE to stop the timer, or to indicate that the relay UE has successfully accessed the network device.

[0375] The relay UE may determine when to send the indication information to the remote UE according to the state of the relay UE. For example, if the relay UE is in the RRC connected state, the relay UE may send the indication information to the remote UE when the connection with the remote UE is successfully established or after the connection is successfully established. If the relay UE is in the RRC idle state or the RRC inactive state, the relay UE may send the indication information to the remote UE when the random access is completed; or, the relay UE may send the indication information to the remote UE when it is determined that the RRC connection is successfully established or the RRC connection is successfully restored (for example, after successfully receiving the RRC setup (RRCsetup) message or the RRC resume (RRC resume) message); or, the relay UE may send the indication information to the remote UE when it is determined that the RRC connection is successfully established or the RRC connection is successfully restored (for example, after the relay UE stops the timer T300 or stops the timer T319). If the timer of the remote UE times out, it is determined that the path switch has failed. The embodiment of the present application determines whether the path switch is successful by using a timer, which is relatively simple and easy to implement. The setting method of the timer is similar to the setting method under the first stop condition, and will not be repeated here. If the timer of the remote UE times out, the subsequent steps can be continued.

[0376] S814: The remote UE sends failure information to the source network device via the first path, and correspondingly, the source network device receives failure information from the remote UE via the first path. The failure information may indicate that the path switch fails.

[0377] The first path is the communication path between the remote UE and the source network device before the path switch is performed. If the embodiment of the present application is applied in the scenario of switching from a non-direct link to a non-direct link, the first path is the communication path of the remote UE connected to the source network device through the relay UE, that is, the first path is: remote UE-relay UE-source network device, and the relay UE at this time is the relay UE connected to the remote UE before the path switch is performed. If the embodiment of the present application is applied in the scenario of switching from a direct link to a non-direct link, the first path is the communication path of the remote UE directly connected to the source network device, that is, the first path is: remote UE-source network device.

[0378] For more information about S814, please refer to Figure 7S712 in the embodiment shown.

[0379] S815, the remote UE sends an RRC connection re-establishment request message to the source network device via the first path, and correspondingly, the source network device receives the RRC connection re-establishment request message from the remote UE. Alternatively, after the remote UE reselects the relay, it may select another relay UE and initiate RRC connection re-establishment via the other relay UE.

[0380] Among them, S814 and S815 are parallel steps, and only one of them needs to be executed. If the remote UE has not disconnected the connection with the source network device through the first path before the path switch is successfully performed, the remote UE can also execute S815 to re-establish the RRC connection under the source network device to communicate with the source network device through the new connection.

[0381] S816: The remote UE performs cell reselection.

[0382] The remote UE may enter an RRC idle state, and perform cell reselection in the RRC idle state. For example, the cell to which the remote UE reselects is referred to as the first cell.

[0383] S817. The remote UE initiates an RRC connection re-establishment process in the first cell, or initiates an RRC connection establishment process in the first cell.

[0384] Among them, S814, S815, and S816-S817, these three solutions are parallel, and only one of them needs to be executed.

[0385] For more information about S817, please refer to Figure 7 S715 in the embodiment shown.

[0386] In the embodiment of the present application, the remote UE can determine the success or failure of the path switch according to the timer, and the determination method is relatively simple and easy to implement. Even for UEs with lower capabilities, the technical solution of the embodiment of the present application can be applied. Moreover, if the path switch fails, the remote UE can take corresponding actions, such as continuing to communicate under the source network device, or entering a new cell through cell reselection, so as to restore the service of the remote UE as soon as possible and improve the continuity of the service.

[0387] The embodiment of the present application provides a seventh communication method, through which the remote UE can also determine under what circumstances the path switch fails, so that the work of the remote UE can continue. Fig. 9 , which is a flow chart of the method. The method may involve a process of switching from a non-direct link to a non-direct link, or may involve a process of switching from a direct link to a non-direct link. In the following introduction, the method is applied to Figure 1A to Figure 1D As an example, the network architecture shown in any of the figures in the present application is used. Figure 1A to Figure 1D For details about the devices in the communication method, please refer to the introduction of the sixth communication method. Fig. 9 The relay terminal device 1 and the relay terminal device 2 in the figure only indicate that there may be multiple UEs that can serve as relay UEs. When the remote UE performs measurement, it can measure multiple UEs.

[0388] In the embodiment of the present application, the source network device and the target network device are taken as an example to be the same network device. In addition, in the following, the second terminal device is described as a remote UE and the first terminal device is a relay UE.

[0389] S901. Remote UE transmits data with a network device.

[0390] S902: The network device sends an RRC message to the remote UE, and correspondingly, the remote UE receives the RRC message from the network device. The RRC message includes, for example, measurement configuration information, and the measurement configuration information is used by the remote UE to measure other UEs.

[0391] Alternatively, the network device may also send broadcast information to the remote UE, and correspondingly, the remote UE receives the broadcast information from the network device. The broadcast information is included in a system message, or in other broadcast messages. The broadcast information may include relevant information for the remote UE to select the relay UE, for example, measurement configuration information for configuring the remote UE to perform measurements for selecting the relay UE.

[0392] S903: The remote UE measures or selects other UEs. For example, the remote UE may send a discovery message to trigger other UEs to send discovery messages, so that the remote UE may measure the discovery messages from other UEs to complete the measurement or selection of other UEs. Fig. 9Take the remote UE measuring other UEs as an example.

[0393] The remote UE may measure other UEs by measuring discovery messages from other UEs, or may measure other information from other UEs, such as data signals from other UEs, etc., which is not limited here. The remote UE may select other UEs based on the measurement results.

[0394] S904: The remote UE sends a first result to the network device, and correspondingly, the network device receives the first result from the remote UE. The first result is, for example, a measurement result or a selection result. Fig. 9 Take the first result as an example, which is a measurement result.

[0395] The measurement result is, for example, a measurement report obtained by the remote UE measuring at least one UE. The selection result is a selection result of the remote UE for the relay UE, for example, including the ID of the selected relay UE, and optionally, measurement information of the remote UE.

[0396] Among them, if the application scenario of the embodiment of the present application is switching from a non-direct link to a non-direct link, then the communication between the remote UE and the network device in S901 to S904 is forwarded by the relay UE connected to the remote UE before switching the link, that is, Fig. 9 The relay terminal device 2 in the figure, and the relay UE described later is the relay UE after the remote UE switches the link, that is, Fig. 9 Relay terminal device 1 in.

[0397] S905: The network device determines whether the remote UE performs path switching based on the measurement result or the selection result. If the network device determines that the remote UE performs path switching, the subsequent steps are executed; otherwise, the subsequent steps are not executed.

[0398] S906: The network device sends a first message to the relay UE, and correspondingly, the relay UE receives the first message from the network device.

[0399] For more information about S906, please refer to Figure 3 S306 in the illustrated embodiment.

[0400] S907: The relay UE sends a second message to the network device. Correspondingly, the network device receives the second message from the relay UE.

[0401] The second message may indicate that the relay UE configuration is complete, or indicate that the relay UE configuration fails. Alternatively, the second message may indicate that the relay UE can provide relay service, or indicate that the relay UE refuses to provide relay service. For example, in an embodiment of the present application, the second message indicates that the relay UE configuration fails, or indicates that the relay UE refuses to provide relay service.

[0402] For more information about S907, please refer to Figure 3 S307 in the illustrated embodiment.

[0403] S908: The network device sends a first message to the relay UE, and correspondingly, the relay UE receives the first message from the network device. The first message may inquire whether the relay UE can provide a relay service.

[0404] For more information about S908, please refer to Figure 4 S406 in the illustrated embodiment.

[0405] S909: The relay UE sends a second message to the network device. Correspondingly, the network device receives the second message from the relay UE.

[0406] The second message may indicate that the relay UE configuration is complete, or indicate that the relay UE configuration fails. Alternatively, the second message may indicate that the relay UE can provide relay service, or indicate that the relay UE refuses to provide relay service. For example, in an embodiment of the present application, the second message indicates that the relay UE configuration fails, or indicates that the relay UE refuses to provide relay service.

[0407] For more information about S909, please refer to Figure 4 S407 in the embodiment shown.

[0408] Among them, S906-S907 and S908-S909 are two parallel processes, and only one of the processes needs to be executed.

[0409] Alternatively, S906 to S909 may not be executed, but the network device may send an RRC reconfiguration message to the relay UE in the existing manner, and the RRC reconfiguration message includes configuration information. After receiving the RRC reconfiguration message, the relay UE may perform configuration. If the configuration is successful, the relay UE may send an RRC reconfiguration completion message to the network device. If the configuration fails, or the relay UE refuses to provide relay service, the relay UE may enter the RRC reestablishment process.

[0410] S910: The network device sends an RRC reconfiguration message to the remote UE. Correspondingly, the remote UE receives the RRC reconfiguration message from the network device.

[0411] The RRC reconfiguration message may include configuration information, and the configuration information may configure the remote UE to switch to provide the relay UE with communication with the target network device. For example, the configuration information may include configuration information of the Uu port.

[0412] S911, the remote UE performs path switch according to the configuration information. For example, the remote UE performs configuration according to the configuration information, and the remote UE requests a connection from the relay UE. If the remote UE successfully establishes a connection with the relay UE, the remote UE successfully switches to communicating with the network through the relay UE.

[0413] If the first condition is met, the remote UE may determine that the path switch is successful, otherwise, if the first condition is not met, the remote UE determines that the path switch is failed.

[0414] In the embodiment of the present application, failure to meet the first condition may be failure to establish a direct communication connection, for example, including one of condition 1, condition 2 or condition 3.

[0415] Condition 1: When the number of times the connection establishment request message is sent to the relay UE is less than or equal to M, feedback is received from the relay UE, where M is the maximum number of retransmissions. The premise of using condition 1 is that if the relay UE does not accept the connection establishment with the remote UE, the relay UE does not reply with a connection establishment response message to the remote UE.

[0416] The remote UE sends a connection establishment request message to the relay UE, and a retransmission mechanism can be used, that is, if the transmission is unsuccessful once, it can be retransmitted. However, the number of retransmissions is limited, and M is the maximum number of retransmissions. If the remote UE has sent the connection establishment request message to the relay UE M times and still has not received feedback from the relay UE, it indicates that the connection establishment has failed. Therefore, if feedback is received from the relay UE when the number of connection establishment request messages sent to the relay UE is less than or equal to M, it indicates that the connection establishment is successful. If feedback is not received from the relay UE when the number of connection establishment request messages sent to the relay UE is greater than or equal to M, it indicates that the connection establishment has failed. If the connection establishment fails, the remote UE will not be able to communicate through the relay UE, and the path switch fails. Therefore, condition 1 can be used to determine whether the path switch is successful.

[0417] Condition 2: The security verification of the relay UE is passed.

[0418] After the remote UE sends a connection establishment request message to the relay UE, if the relay UE agrees to establish the connection, it will send security-related parameters to the remote UE, and the remote UE needs to configure according to these security-related parameters. However, the remote UE may fail to configure. For example, some parameters sent by the relay UE (such as integrity protection algorithm, etc.) are not supported by the remote UE, and the remote UE will fail to configure. If the remote UE fails to configure according to the security parameters, it is considered that the security verification of the relay UE has failed. If the remote UE successfully configures according to the security parameters, it is considered that the security verification of the relay UE has passed. If the security verification of the relay UE passes, the remote UE can communicate through the relay UE, and the path switch is successful. If the security verification of the relay UE fails, the remote UE cannot communicate through the relay UE, and the path switch fails. Therefore, condition 2 can be used to determine whether the path switch is successful.

[0419] Condition 3: Send a connection establishment request message to the relay UE and receive a connection establishment response message from the relay UE, which may indicate acceptance (or permission) of the connection establishment. The premise of using condition 3 is that, regardless of whether the relay UE accepts to establish a connection with the remote UE, the relay UE will reply to the remote UE with a connection establishment response message.

[0420] The remote UE sends a connection establishment request message to the relay UE. If the relay UE replies with a connection establishment response message, and the connection establishment response message indicates that the connection is accepted, the remote UE can communicate through the relay UE, and the path switch is successful. If the connection establishment response message indicates that the connection is not accepted, the remote UE cannot communicate through the relay UE, and the path switch fails. Therefore, condition 3 can also be used to determine whether the path switch is successful.

[0421] Which of the above three conditions is used by the remote UE to determine whether the path switch is successful can be determined by the remote UE itself, or can be configured by the network device, or can be stipulated by the protocol. Using the above conditions can flexibly and quickly enable the remote UE to determine whether the path switch is successful. If the path switch fails, compared with the solution of using a timer to determine whether the path switch is successful, the remote UE can enter the link recovery step faster, reduce or avoid communication interruption, and improve service continuity.

[0422] Alternatively, in the embodiment of the present application, the remote UE may not adopt the above conditions, but use a timer to determine whether the path switch is successful. For details about the method of using a timer to determine, refer to Figure 8 Description of the illustrated embodiment.

[0423] Alternatively, Figure 8 In the embodiment shown, the remote UE may not use a timer to determine whether the path switch is successful, but may use one of the above three conditions to determine whether the path switch is successful. For the determination method, please refer to the introduction of the embodiment of the present application.

[0424] If the remote UE determines that the path switch fails, the remote UE can communicate normally through the relay UE and does not need to perform subsequent steps. If the remote UE determines that the path switch fails, the following steps can be continued.

[0425] S912: The remote UE sends failure information to the network device via the first path, and correspondingly, the network device receives failure information from the remote UE via the first path. The failure information may indicate that the path switch fails.

[0426] The first path is the communication path between the remote UE and the network device before the path switch is performed. If the embodiment of the present application is applied in the scenario of switching from a non-direct link to a non-direct link, the first path is the communication path of the remote UE connecting to the network device through the relay UE, that is, the first path is: remote UE-relay UE-network device, and the relay UE at this time is the relay UE connected to the remote UE before the path switch is performed. If the embodiment of the present application is applied in the scenario of switching from a direct link to a non-direct link, the first path is the communication path of the remote UE directly connecting to the network device, that is, the first path is: remote UE-network device.

[0427] For more information about S912, please refer to Figure 7 S712 in the embodiment shown.

[0428] S913: The remote UE sends an RRC connection re-establishment request message to the source network device through the first path. Correspondingly, the source network device receives the RRC connection re-establishment request message from the remote UE.

[0429] Among them, S912 and S913 are parallel steps, and only one of them needs to be executed. If the remote UE has not disconnected the connection with the source network device through the first path before the path switch is successfully performed, the remote UE can also execute S912 to re-establish the RRC connection under the source network device to communicate with the source network device through the new connection.

[0430] S914: The remote UE performs cell reselection.

[0431] The remote UE may enter an RRC idle state, and perform cell reselection in the RRC idle state. For example, the cell to which the remote UE reselects is referred to as the first cell.

[0432] S915. The remote UE initiates an RRC connection re-establishment process in the first cell, or initiates an RRC connection establishment process in the first cell.

[0433] Among them, S912, S913, and S914-S915, these three solutions are parallel, and only one of them needs to be executed.

[0434] For more information about S915, please refer to Figure 7 S715 in the embodiment shown.

[0435] In the embodiment of the present application, the remote UE can determine the success or failure of the path switch according to different conditions. Compared with the method of determining whether the path switch is successful by a timer, determining by the conditions described above can reduce the time required for the determination process and improve the efficiency of the determination, so that the remote UE can learn whether the path switch is successful more quickly, so as to take corresponding measures more quickly and reduce the time of service interruption. Moreover, if the path switch fails, the remote UE can take corresponding actions, such as continuing to communicate under the source network device, or can enter a new cell through cell reselection, so as to restore the remote UE's service as soon as possible and improve the continuity of the service.

[0436] Next, the embodiment of the present application provides an eighth communication method, through which the remote UE can also determine under what circumstances the path switch fails, so that the work of the remote UE can continue. Fig.10 , which is a flow chart of the method. The method may involve a process of switching from a non-direct link to a non-direct link, or may involve a process of switching from a direct link to a non-direct link. In the following introduction, the method is applied to Figure 1A to Figure 1D Take the network architecture shown in any of the accompanying drawings as an example.

[0437] If the technical solution provided in the embodiment of the present application is applied to Figure 1A The network architecture shown in FIG. 1 shows that the source network device before the remoteUE performs the path switch and the target network device after the path switch are the same network device. Then the first terminal device described below can be Figure 1A The relay terminal device in the following description may be a second terminal device Figure 1A The remote terminal device in the following description can be Figure 1AThe access network device in the embodiment of the present application is both a source network device and a target network device; if the technical solution provided in the embodiment of the present application is applied to Figure 1B The network architecture shown in FIG. 1 shows that the source network device before the remote UE performs the path switch and the target network device after the path switch are the same network device. Then the first terminal device described below can be Figure 1B The relay terminal device 1 or the relay terminal device 2 in the embodiment, the second terminal device described below may be Figure 1B The remote terminal device in the following description can be Figure 1B The access network device in the embodiment of the present application is both a source network device and a target network device; if the technical solution provided in the embodiment of the present application is applied to Figure 1C The network architecture shown in FIG. 1 shows that the source network device before the remote UE performs the path switch and the target network device after the path switch are different network devices. Then the first terminal device described below may be Figure 1C The relay terminal device in the following description may be a second terminal device Figure 1C The remote terminal device in the example, the network device described below (or referred to as the first network device, the first network device being the source network device) may be Figure 1C The access network device 1 in the text, in addition, the target network device is also referred to below, which can be called the second network device, which can be Figure 1C The access network device 2 in the source network device may be Figure 1C The access network device 2 in the target network device can be Figure 1C The access network device 1 in the embodiment of the present application is applied to Figure 1D The network architecture shown in FIG. 1 shows that the source network device before the remote UE performs the path switch and the target network device after the path switch are different network devices. Then the first terminal device described below may be Figure 1D The relay terminal device 1 in the embodiment, the second terminal device described below may be Figure 1D The remote terminal device in the example, the network device described below (or referred to as the first network device, the first network device being the source network device) may be Figure 1D The access network device 1 in the text, in addition, the target network device is also referred to below, which can be called the second network device, which can be Figure 1D The access network device 2 in the embodiment, or the first terminal device may be Figure 1D The relay terminal device 2 in the source network device can be Figure 1D The access network device 2 in the target network device can be Figure 1DAccess network device 1 in.

[0438] In the following, the second terminal device is described as a remote UE and the first terminal device is a relay UE. In addition, in the embodiment of the present application, the source network device and the target network device are different network devices.

[0439] S1001. A remote UE performs data transmission with a source network device.

[0440] S1002: The source network device sends an RRC message to the remote UE, and correspondingly, the remote UE receives the RRC message from the source network device. The RRC message includes, for example, measurement configuration information, and the measurement configuration information is used by the remote UE to measure other UEs.

[0441] Alternatively, the network device may also send broadcast information to the remote UE, and correspondingly, the remote UE receives the broadcast information from the network device. The broadcast information is included in a system message, or in other broadcast messages. The broadcast information may include relevant information for the remote UE to select the relay UE, for example, measurement configuration information for configuring the remote UE to perform measurements for selecting the relay UE.

[0442] S1003: The remote UE measures or selects other UEs. For example, the remote UE may send a discovery message to trigger other UEs to send discovery messages, so that the remote UE may measure the discovery messages from other UEs to complete the measurement or selection of other UEs. Fig.10 Take the remote UE measuring other UEs as an example.

[0443] The remote UE may measure other UEs by measuring discovery messages from other UEs, or may measure other information from other UEs, such as data signals from other UEs, etc., which is not limited here. The remote UE may select other UEs based on the measurement results.

[0444] S1004: The remote UE sends a first result to the network device, and correspondingly, the network device receives the first result from the remote UE. The first result is, for example, a measurement result or a selection result. Fig.10 Take the first result as an example, which is a measurement result.

[0445] The measurement result includes, for example, a measurement report of the remote UE on at least one UE. The selection result is a selection result of the remote UE on the relay UE, for example, including the ID of the selected relay UE, and optionally, measurement information of the remote UE.

[0446] Among them, if the application scenario of the embodiment of the present application is switching from a direct link to a non-direct link, then the measurement result can also include the measurement result of the service cell, that is, the measurement result of the network device. If the application scenario of the embodiment of the present application is switching from a non-direct link to a non-direct link, then the communication between the remote UE and the network device in S1001 to S1004 is forwarded by the relay UE connected to the remote UE before switching the link, and the relay UE described later is the relay UE after the remote UE switches the link. The first result can also include the measurement result of the relay UE connected to the link before switching.

[0447] S1005. The source network device makes a switching decision. The source network device determines whether the remote UE can perform a path switch based on the measurement result. In the embodiment of the present application, the source network device determines whether the remote UE can switch from the relay UE to the target network device based on the measurement result. If the source network device determines that the remote UE can switch from the relay UE to the target network device, S1006 is executed.

[0448] S1006. The source network device sends a handover request message to the target network device, and accordingly, the target network device receives the handover request message from the source network device. The handover request message may indicate that the remote UE will be handed over to the target network device, which is the target network device serving the relay UE. Because the remote UE wants to switch to communicating through the relay UE, the source network device requests the handover from the target network device where the relay UE is located.

[0449] S1007: The target network device sends an RRC reconfiguration message to the relay UE, and correspondingly, the relay UE receives the RRC reconfiguration message from the target network device. For example, the RRC reconfiguration message is referred to as RRC reconfiguration message 1.

[0450] The RRC reconfiguration message includes, for example, configuration information. The RRC reconfiguration message implements, for example Figure 3 Alternatively, the RRC reconfiguration message, for example, inquires whether the relay UE can provide the relay service. The RRC reconfiguration message, for example, implements Figure 4The function of the first message in the embodiment shown. Or after the RRC reconfiguration message is configured, if the relay UE cannot configure the relevant configuration, the relay UE triggers the reconfiguration failure, which in turn causes the relay UE to enter the RRC connection reestablishment process.

[0451] S1008: The relay UE sends a second message to the target network device. Correspondingly, the target network device receives the second message from the relay UE. Figure 3 The function of the first message in the embodiment shown in FIG. 1004 can be realized by the second message in S1008. Figure 3 Function of the second message in the embodiment shown; or, if the RRC reconfiguration message in S1007 implements Figure 4 The function of the first message in the embodiment shown in FIG. 1004 can be realized by the second message in S1008. Figure 4 Function of the second message in the illustrated embodiment.

[0452] In the embodiment of the present application, for example, the second message indicates a configuration failure, or instructs the relay UE to refuse to provide a relay service. Figure 3 S306 or S307 in the embodiment shown, or Figure 4 S406 or S407 in the embodiment shown. If the configuration message configuration of S1007 fails, S1008 may be an optional step and is not sent. The relay UE confirms that the reconfiguration fails, and triggers the relay UE to enter the RRC connection reestablishment process.

[0453] S1009: The target network device sends a switching request confirmation message to the source network device. Correspondingly, the source network device receives the switching request confirmation message from the target network device.

[0454] The handover request confirmation message may indicate that the remote UE is allowed to switch to the target network device, or indicate that the remote UE is not allowed to switch to the target network device. In the embodiment of the present application, since the second message indicates a configuration failure, or indicates that the relay UE refuses to provide relay service, the handover request confirmation message may indicate that the remote UE is not allowed to switch to the target network device.

[0455] Among them, S1007 is after S1006, and S1010 is after S1009, but there is no restriction on the order of S1007 and S1009. For example, the target network device can execute S1009 after configuring the relay UE, or can execute S1009 first and then inquire or configure the relay UE. If the target network device and the source network device are the same network device, there is no need to execute S1006 and S1009.

[0456] S1010: The source network device sends an RRC reconfiguration message to the remote UE, and correspondingly, the remote UE receives the RRC reconfiguration message from the source network device. For example, the RRC reconfiguration message is called RRC reconfiguration message 2.

[0457] The RRC reconfiguration message may include configuration information, and the configuration information may configure the remote UE to switch to a non-direct path and communicate with the target network device through the relay UE. For more information about S1010, such as the implementation of the configuration information, please refer to Figure 8 S810 in the illustrated embodiment.

[0458] S1011. The remote UE performs a path switch according to the configuration information. For example, the remote UE performs a configuration according to the configuration information, and the remote UE requests a connection from the relay UE. If the second condition is met, it can be determined that the remote UE path switch fails.

[0459] In the embodiment of the present application, the second condition may be related to the timer and the received indication. For example, if the configured timer times out, or the remote UE fails to establish a connection with the relay UE before the timer times out, or the remote UE receives an RLF indication sent by the relay UE before the timer times out, the remote UE determines that the path switch fails. For details, please refer to the following description.

[0460] S1012. The remote UE starts a timer.

[0461] For example, after executing S1010, or in other words, after receiving the configuration information from the source network device (the configuration information may be included in the ordinary RRC reconfiguration message), the remote UE may start a timer. The timer may be, for example, timer T304, or may be other newly introduced timers, which are not limited here. For the configuration method of the timer and other parameters such as the timing duration of the timer, please refer to Figure 8 S812 in the embodiment shown. In addition, the timer can be stopped in a specific scenario, and the specific stop condition can be referred to the description in S1013 below.

[0462] S1013, the remote UE requests the relay UE to establish a connection. For example, the remote UE sends a connection establishment request to the relay UE, and after receiving the connection establishment request, if the relay UE replies with a connection establishment response message to the remote UE, and the connection establishment response message indicates that the connection establishment is allowed, then the connection between the remote UE and the relay UE is successfully established; and if after receiving the connection establishment request, the relay UE replies with a connection establishment response message to the remote UE, and the connection establishment response message indicates that the connection establishment is not allowed, or the relay UE does not reply to the connection establishment response message, then the connection between the remote UE and the relay UE fails to be established.

[0463] In more detail, when one or more of the following scenarios occur, it can be directly determined that the connection establishment between the remote UE and the relay UE has failed. When it is determined that the connection establishment has failed, it can be determined that the path switch has failed. Optionally, the configured timer can be stopped. In other words, when one or more of the following scenarios occur, it is not necessary to wait for the timer to determine that the connection establishment has failed, thereby reducing the waiting time of the remote UE. Optionally, if it is determined that the connection establishment has failed, the remote UE can also be triggered to re-establish RRC.

[0464] Scenario 1: When the number of times the connection establishment request message is sent to the relay UE reaches M, no feedback is received from the relay UE, where M is the maximum number of retransmissions.

[0465] The remote UE sends a connection establishment request message to the relay UE, and a retransmission mechanism can be used, that is, if one transmission fails, it can be retransmitted. However, the retransmission is limited in number, and M is the maximum number of retransmissions. If the remote UE has sent M connection establishment request messages to the relay UE and still has not received any feedback from the relay UE, it indicates that the connection establishment has failed. If no feedback is received from the relay UE when the number of connection establishment request messages sent to the relay UE is greater than or equal to M, it indicates that the connection establishment has failed. If the connection establishment fails, the remote UE will not be able to communicate through the relay UE, and the path switch will fail.

[0466] Scenario 2: The remote UE fails the security verification of the relay UE.

[0467] After the remote UE sends a connection establishment request message to the relay UE, if the relay UE agrees to establish the connection, it will send security-related parameters to the remote UE, and the remote UE needs to be configured according to these security-related parameters. However, the remote UE may fail to configure. For example, some parameters sent by the relay UE (such as integrity protection algorithm, etc.) are not supported by the remote UE, and the remote UE will fail to configure. If the remote UE fails to configure according to the security parameters, it is considered that the security verification of the relay UE has failed. If the remote UE successfully configures according to the security parameters, it is considered that the security verification of the relay UE has passed. If the security verification of the relay UE fails, the remote UE cannot communicate through the relay UE, indicating that the connection establishment failed and the path switch failed.

[0468] Scenario 3: Sending a connection establishment request message to the relay UE, and receiving a connection establishment response message from the relay UE, where the connection establishment response message may indicate rejection of the connection establishment.

[0469] The remote UE sends a connection establishment request message to the relay UE. If the relay UE replies with a connection establishment response message, and the connection establishment response message indicates that the connection is accepted, the remote UE can communicate through the relay UE. If the connection establishment response message indicates that the connection is not accepted, the remote UE cannot communicate through the relay UE, indicating that the connection establishment fails and the path switch fails.

[0470] In addition, the timer related to the second condition, that is, the timer started in S1012, can be stopped when some conditions are met. For example, the timer can be stopped when any of the first stop condition, the second stop condition, the third stop condition, the fourth stop condition, or the fifth stop condition is met. For the first to fourth stop conditions, please refer to Figure 8 With reference to S813 in the illustrated embodiment, the fifth stop condition is briefly introduced below.

[0471] For example, the fifth stop condition is that the remote UE determines that the connection establishment with the relay UE fails, or determines that the PC5RLF between the remote UE and the relay UE occurs, or the remote UE receives a Uu RLF indication from the relay UE, or the remote UE receives an access failure indication from the relay UE. If the fifth stop condition is met, the remote UE can stop the timer and determine that the path switch fails. Among them, if the timer of the remote UE times out, it is determined that the path switch fails. The embodiment of the present application determines whether the path switch is successful by a timer, and the method is relatively simple and easy to implement. The setting method of the timer is similar to the setting method under the first stop condition, and will not be repeated here. The fifth stop condition includes multiple conditions. By introducing these conditions, it is possible to quickly determine whether the path switch fails before the timer times out, reduce the waiting time of the remote UE, and speed up the service recovery speed of the remote UE.

[0472] After determining that the path switch has failed, you can continue to execute subsequent steps after determining the failure.

[0473] S1013a. If the configuration information in S1010 includes the configuration information of the relay UE, the remote UE sends the configuration information to the relay UE. Correspondingly, the relay UE receives the configuration information from the remote UE. The configuration information sent by the remote UE to the relay UE, for example, includes the Uu port configuration information of the relay UE, or the PC5 port configuration information, wherein the PC5 port configuration information may include the PC5RLC configuration, and may include the LCID and parameter configuration. The information configured by the remote UE to the relay UE may also be the configuration information in S1010, or may also be the configuration information of the relay UE included in the configuration information in S1010, which will not be repeated here.

[0474] S1013b: If the connection between the relay UE and the remote UE is established successfully, the remote UE sends an RRC reconfiguration complete message to the network device through the relay UE. Correspondingly, the network device receives the RRC reconfiguration complete message from the relay UE.

[0475] Among them, the configuration used by the remote UE to send the RRC reconfiguration completion message to the relay UE may be the default PC5RLC configuration, which may include a default LCID and a default parameter configuration, etc. Using the default parameter configuration, the relay UE can normally receive the RRC reconfiguration completion message from the remote UE even in the RRC idle state or the RRC inactive state, thereby triggering the entry into the RRC connected state. The configuration used by the remote UE to send the RRC reconfiguration completion message to the relay UE may also use the configuration sent in S1013a. If the PC5 connection establishment fails in S1013, S1013b may not be executed.

[0476] S1013c: If the relay UE is in the RRC idle state or the RRC inactive state, upon receiving the RRC reconfiguration completion message from the remote UE, it is triggered to enter the RRC connected state and access the network device.

[0477] S1014: The remote UE sends failure information to the source network device via the first path. Correspondingly, the source network device receives failure information from the remote UE via the first path. The failure information may indicate that the path switch fails.

[0478] The first path is the communication path between the remote UE and the source network device before the path switch is performed. If the embodiment of the present application is applied in the scenario of switching from a non-direct link to a non-direct link, the first path is the communication path of the remote UE connected to the source network device through the relay UE, that is, the first path is: remote UE-relay UE-source network device, and the relay UE at this time is the relay UE connected to the remote UE before the path switch is performed. If the embodiment of the present application is applied in the scenario of switching from a direct link to a non-direct link, the first path is the communication path of the remote UE directly connected to the source network device, that is, the first path is: remote UE-source network device.

[0479] For more information about S1014, please refer to Figure 7 S712 in the embodiment shown.

[0480] S1015, the remote UE sends an RRC connection re-establishment request message to the source network device via the first path, and correspondingly, the source network device receives the RRC connection re-establishment request message from the remote UE. Or the remote UE selects another relay UE through relay reselection and initiates connection re-establishment.

[0481] Among them, S1014 and S1015 are parallel steps, and only one of them needs to be executed. If the remote UE has not disconnected the connection with the source network device through the first path before the path switch is successfully performed, the remote UE can also execute S1015 to re-establish the RRC connection under the source network device to communicate with the source network device through the new connection.

[0482] S1016. The remote UE performs cell reselection.

[0483] The remote UE may enter an RRC idle state, and perform cell reselection in the RRC idle state. For example, the cell to which the remote UE reselects is referred to as the first cell.

[0484] S1017. The remote UE initiates an RRC connection reestablishment process in the first cell, or initiates an RRC connection establishment process in the first cell.

[0485] Among them, S81014, S1015, and S1016-S1017, these three solutions are parallel, and only one of them needs to be executed.

[0486] For more information about S1017, please refer to Figure 7 S715 in the embodiment shown.

[0487] In the embodiment of the present application, the remote UE can determine the success or failure of the path switch according to the timer, and the determination method is relatively simple and easy to implement. Even for UEs with lower capabilities, the technical solution of the embodiment of the present application can be applied. Moreover, if the path switch fails, the remote UE can take corresponding actions, such as continuing to communicate under the source network device, or entering a new cell through cell reselection, so as to restore the service of the remote UE as soon as possible and improve the continuity of the service.

[0488] The following describes the device used to implement the above method in the embodiment of the present application in conjunction with the accompanying drawings. Therefore, the above content can be used in subsequent embodiments, and the repeated content will not be repeated.

[0489] The embodiment of the present application provides a communication device, which can be a terminal device or a circuit. The communication device can be used to execute the actions executed by the terminal device in the above-mentioned various method embodiments.

[0490] When the communication device is a terminal device, Fig.11 A simplified schematic diagram of the structure of a terminal device is shown. For ease of understanding and illustration, Fig.11In the example, a mobile phone is used as the terminal device. Fig.11 As shown, the terminal device includes a processor, a memory, a radio frequency circuit, an antenna, and an input-output device. The processor is mainly used to process communication protocols and communication data, as well as to control the terminal device, execute software programs, process software program data, etc. The memory is mainly used to store software programs and data. The radio frequency circuit is mainly used for conversion between baseband signals and radio frequency signals and processing of radio frequency signals. The antenna is mainly used to send and receive radio frequency signals in the form of electromagnetic waves. Input-output devices, such as touch screens, display screens, keyboards, etc., are mainly used to receive data input by users and output data to users. It should be noted that some types of terminal devices may not have input-output devices.

[0491] When data needs to be sent, the processor performs baseband processing on the data to be sent and outputs the baseband signal to the RF circuit. The RF circuit performs RF processing on the baseband signal and then sends the RF signal outward in the form of electromagnetic waves through the antenna. When data is sent to the terminal device, the RF circuit receives the RF signal through the antenna, converts the RF signal into a baseband signal, and outputs the baseband signal to the processor. The processor converts the baseband signal into data and processes the data. For ease of explanation, Fig.11 Only one memory and processor are shown. In an actual terminal device product, there may be one or more processors and one or more memories. The memory may also be referred to as a storage medium or a storage device. The memory may be set independently of the processor or may be integrated with the processor, and the embodiments of the present application do not limit this.

[0492] In the embodiments of the present application, the antenna and the radio frequency circuit with transceiver functions may be regarded as the transceiver unit of the terminal device (the transceiver unit may be a functional unit that can realize the sending function and the receiving function; or the transceiver unit may also include two functional units, namely, a receiving unit that can realize the receiving function and a sending unit that can realize the sending function), and the processor with processing function may be regarded as the processing unit of the terminal device. Fig.11 As shown, the terminal device includes a transceiver unit 1110 and a processing unit 1120. The transceiver unit may also be referred to as a transceiver, a transceiver, a transceiver device, etc. The processing unit may also be referred to as a processor, a processing board, a processing module, a processing device, etc. Optionally, the device used to implement the receiving function in the transceiver unit 1110 may be regarded as a receiving unit, and the device used to implement the sending function in the transceiver unit 1110 may be regarded as a sending unit, that is, the transceiver unit 1110 includes a receiving unit and a sending unit. The transceiver unit may also be sometimes referred to as a transceiver, a transceiver, or a transceiver circuit, etc. The receiving unit may also be sometimes referred to as a receiver, a receiver, or a receiving circuit, etc. The sending unit may also be sometimes referred to as a transmitter, a transmitter, or a transmitting circuit, etc.

[0493] It should be understood that the transceiver unit 1110 is used to perform the above Figure 3 The embodiment shown to Fig.10 In any of the embodiments shown in the drawings, the first terminal device side or the second terminal device side sends and receives the operation, and the processing unit 1120 is used to perform the above Figure 3 The embodiment shown to Fig.10 In any of the illustrated embodiments, the first terminal device side or the second terminal device side performs other operations besides the sending and receiving operations.

[0494] When the communication device is a chip-type device or circuit, the device may include a transceiver unit and a processing unit, wherein the transceiver unit may be an input / output circuit and / or a communication interface; and the processing unit may be an integrated processor or microprocessor or integrated circuit.

[0495] Fig.12 The following is a schematic block diagram of another communication device 1200 provided in an embodiment of the present application. For example, the communication device 1200 is a terminal device or a network device. For example, the communication device 1200 can implement Figure 3 The embodiment shown or Figure 4 The function of the first terminal device described in the embodiment shown, or the implementation Figure 3 The embodiment shown or Figure 4 Alternatively, the communication device 1200 can implement Figure 5 The embodiment shown or Figure 6 The function of the second terminal device described in the embodiment shown, or the implementation Figure 5 The embodiment shown or Figure 6 Alternatively, the communication device 1200 can implement Figure 7 The embodiment shown to Fig. 9 The function of the second terminal device described in any of the embodiments shown in the embodiment, or the implementation Figure 7 The embodiment shown to Fig. 9 The first network device ( Fig. 9 In the embodiment shown, the source network device and the target network device are the same network device, both of which can be referred to as the first network device). Alternatively, the communication device 1200 can implement Fig.10 The function of the second terminal device described in the embodiment shown, or the implementation Fig.10 The functions of the first network device described in the embodiment shown.

[0496] The communication device 1200 includes a transceiver unit 1220 and a processing unit 1210. Optionally, the communication device 1200 may further include a storage unit, which can communicate with the processing unit 1210. Fig.12 It is not shown in the figure. Alternatively, the communication device 1200 may not include a storage unit, and the storage unit may also be located outside the communication device 1200. Exemplarily, the communication device 1200 may be a terminal device, or a chip applied to a terminal device, or other combination devices, components, etc. having the functions of the first terminal device or the second terminal device, or the communication device 1200 may be a network device, or a chip applied to a network device, or other combination devices, components, etc. having the functions of the network device. When the communication device 1200 is a terminal device or a network device, the processing unit 1010 may include a processor, such as a baseband processor, and the baseband processor may include one or more central processing units (CPUs); the transceiver unit 1220 may be a transceiver, and the transceiver may include an antenna and a radio frequency circuit, etc. Among them, the transceiver may include a transmitter and a receiver, and the transceiver may realize the functions of the transmitter and the receiver, or the transmitter and the receiver may also be two functional modules deployed separately, but the embodiment of the present application refers to the two functional modules as transceivers. When the communication device 1200 is a component having the functions of the above-mentioned terminal device or network device, the transceiver unit 1220 may be a radio frequency unit, and the processing unit 1210 may be a processor, such as a baseband processor. When the communication device 1200 is a chip system, the transceiver unit 1220 may be an input and output interface of a chip (such as a baseband chip), and the processing unit 1210 may be a processor of the chip system, which may include one or more central processing units. It should be understood that the processing unit 1210 in the embodiment of the present application may be implemented by a processor or a processor-related circuit component, and the transceiver unit 1220 may be implemented by a transceiver or a transceiver-related circuit component.

[0497] In one embodiment, when the communication device 1200 is used to implement Figure 3 When the first terminal device functions as described in the embodiment shown, the processing unit 1210 can be used to execute Figure 3 In the embodiment shown, all operations except the transceiver operation performed by the first terminal device, such as S308, and / or other processes for supporting the technology described herein. The transceiver unit 1220 may be used to perform Figure 3 All receiving operations and sending operations performed by the first terminal device in the illustrated embodiment, such as S303, S306 and S307, and / or other processes for supporting the technology described herein.

[0498] In one embodiment, when the communication device 1200 is used to implement Figure 3 When the network device functions as described in the embodiment shown, the processing unit 1210 can be used to execute Figure 3 In the embodiment shown, all operations performed by the network device except the transceiver operation, such as S305, and / or other processes used to support the technology described herein. The transceiver unit 1220 can be used to perform Figure 3 All receiving operations and sending operations performed by the network device in the illustrated embodiment, such as S301, S302, S304, S306 and S307, and / or other processes for supporting the technology described herein.

[0499] In one embodiment, when the communication device 1200 is used to implement Figure 4 When the first terminal device functions as described in the embodiment shown, the processing unit 1210 can be used to execute Figure 4 In the embodiment shown, all operations except the transceiver operation performed by the first terminal device, such as S410, and / or other processes for supporting the technology described herein. The transceiver unit 1220 may be used to perform Figure 4 All receiving operations and sending operations performed by the first terminal device in the illustrated embodiment, such as S403, S406, S407 and S408, and / or other processes for supporting the technology described herein.

[0500] In one embodiment, when the communication device 1200 is used to implement Figure 4 When the network device functions as described in the embodiment shown, the processing unit 1210 can be used to execute Figure 4 In the embodiment shown, all operations performed by the network device except the transceiver operation, such as S405, and / or other processes used to support the technology described herein. The transceiver unit 120 can be used to perform Figure 4 All receiving operations and sending operations performed by the network device in the illustrated embodiment, such as S401, S402, S404, S406, S407, S408 and S409, and / or other processes for supporting the technology described herein.

[0501] In one embodiment, when the communication device 1200 is used to implement Figure 5 When the second terminal device functions as described in the embodiment shown, the processing unit 1210 can be used to execute Figure 5 In the embodiment shown, all operations except the transceiver operation performed by the second terminal device, such as S505, S506 and S507, and / or other processes for supporting the technology described herein. The transceiver unit 1220 may be used to perform Figure 5All receiving operations and sending operations performed by the second terminal device in the illustrated embodiment, such as S501, S502, S503 and S504, and / or other processes for supporting the technology described herein.

[0502] In one embodiment, when the communication device 1200 is used to implement Figure 5 When the network device functions as described in the embodiment shown, the processing unit 1210 can be used to execute Figure 5 All operations performed by the network device in the illustrated embodiment except for the transceiver operation, and / or other processes used to support the technology described herein. The transceiver unit 1220 can be used to perform Figure 5 All receiving operations and sending operations performed by the network device in the illustrated embodiment, such as S501, S502 and S504, and / or other processes for supporting the technology described herein.

[0503] In one embodiment, when the communication device 1200 is used to implement Figure 6 When the second terminal device functions as described in the embodiment shown, the processing unit 1210 can be used to execute Figure 6 In the embodiment shown, all operations except the transceiver operation performed by the second terminal device, such as S611, and / or other processes for supporting the technology described herein. The transceiver unit 1220 may be used to perform Figure 6 All receiving operations and sending operations performed by the second terminal device in the illustrated embodiment, such as S601, S602, S603, S604 and S610, and / or other processes for supporting the technology described herein.

[0504] In one embodiment, when the communication device 1200 is used to implement Figure 6 When the network device functions as described in the embodiment shown, the processing unit 1210 can be used to execute Figure 6 In the embodiment shown, all operations performed by the network device except the transceiver operation, such as S605, and / or other processes used to support the technology described herein. The transceiver unit 1220 can be used to perform Figure 6 All receiving operations and sending operations performed by the network device in the illustrated embodiment, such as S601, S602, S604, and S606-S610, and / or other processes for supporting the technology described herein.

[0505] In one embodiment, when the communication device 1200 is used to implement Figure 7 When the second terminal device functions as described in the embodiment shown, the processing unit 1210 can be used to execute Figure 7In the embodiment shown, all operations except the transceiver operation performed by the second terminal device, such as S709, S710 and S714, and / or other processes for supporting the technology described herein. The transceiver unit 1020 may be used to perform Figure 7 All receiving operations and sending operations performed by the second terminal device in the illustrated embodiment, such as S701, S702, S703, S704, S708, S711, S712, S713 and S715, and / or other processes for supporting the technology described herein.

[0506] In one embodiment, when the communication device 1200 is used to implement Figure 7 When the functions of the first network device described in the embodiment shown are performed, the processing unit 1210 can be used to execute Figure 7 In the embodiment shown, all operations except the transceiver operation performed by the first network device, such as S705, and / or other processes for supporting the technology described herein. The transceiver unit 1220 may be used to perform Figure 7 All receiving operations and sending operations performed by the first network device in the illustrated embodiment, such as S701, S702, S704, S706, S707, S708, S712, S713 and S715, and / or other processes for supporting the technology described herein.

[0507] In one embodiment, when the communication device 1200 is used to implement Figure 8 When the second terminal device functions as described in the embodiment shown, the processing unit 1210 can be used to execute Figure 8 In the embodiment shown, all operations except the transceiver operation performed by the second terminal device, such as S811, S812 and S816, and / or other processes for supporting the technology described herein. The transceiver unit 1220 may be used to perform Figure 8 All receiving operations and sending operations performed by the second terminal device in the illustrated embodiment, such as S801, S802, S803, S804, S810, S813, S814, S815 and S817, and / or other processes for supporting the technology described herein.

[0508] In one embodiment, when the communication device 1200 is used to implement Figure 8 When the functions of the first network device described in the embodiment shown are performed, the processing unit 1210 can be used to execute Figure 8 In the embodiment shown, all operations except the transceiver operation performed by the first network device, such as S805, and / or other processes for supporting the technology described herein. The transceiver unit 1220 may be used to perform Figure 8All receiving operations and sending operations performed by the first network device in the illustrated embodiment, such as S801, S802, S804, S806, S809, S810, SS814, S815 and S817, and / or other processes for supporting the technology described herein.

[0509] In one embodiment, when the communication device 1200 is used to implement Fig. 9 When the second terminal device functions as described in the embodiment shown, the processing unit 1210 can be used to execute Fig. 9 In the embodiment shown, all operations except the transceiver operation performed by the second terminal device, such as S911 and S914, and / or other processes for supporting the technology described herein. The transceiver unit 1220 may be used to perform Fig. 9 All receiving operations and sending operations performed by the second terminal device in the illustrated embodiment, such as S901, S902, S903, S904, S910, S912, S913 and S915, and / or other processes for supporting the technology described herein.

[0510] In one embodiment, when the communication device 1200 is used to implement Fig. 9 When the functions of the first network device described in the embodiment shown are performed, the processing unit 1210 can be used to execute Fig. 9 In the embodiment shown, all operations except the transceiver operation performed by the first network device, such as S905, and / or other processes for supporting the technology described herein. The transceiver unit 1220 may be used to perform Fig. 9 All receiving operations and sending operations performed by the first network device in the illustrated embodiment, such as S901, S902, S904, S906-S910, S912, S913 and S915, and / or other processes for supporting the technology described herein.

[0511] In one embodiment, when the communication device 1200 is used to implement Fig.10 When the second terminal device functions as described in the embodiment shown, the processing unit 1210 can be used to execute Fig.10 In the embodiment shown, all operations except the transceiver operation performed by the second terminal device, such as S1011, S1012 and S1016, and / or other processes for supporting the technology described herein. The transceiver unit 1220 may be used to perform Fig.10All receiving and sending operations performed by the second terminal device in the illustrated embodiment, such as S1001, S1002, S1003, S1004, S1010, S1013, S1013a, S1013b, S1013c, S1014, S1015 and S1017, and / or other processes for supporting the technology described herein.

[0512] In one embodiment, when the communication device 1200 is used to implement Fig.10 When the functions of the first network device described in the embodiment shown are performed, the processing unit 1210 can be used to execute Fig.10 In the embodiment shown, all operations except the transceiver operation performed by the first network device, such as S1005, and / or other processes for supporting the technology described herein. The transceiver unit 1220 may be used to perform Fig.10 All receiving and sending operations performed by the first network device in the illustrated embodiment, such as S1001, S1002, S1003, S1004, S1010, S1013, S1013a, S1013b, S1013c, S1014, S1015 and S1017, and / or other processes for supporting the technology described herein.

[0513] In addition, the transceiver unit 1220 may be a functional module that can perform both sending and receiving operations. For example, the transceiver unit 1220 may be used to perform Figure 3 The embodiment shown to Fig.10 All sending operations and receiving operations performed by a terminal device or a network device in any of the embodiments shown. For example, when performing a receiving operation, the transceiver unit 1220 can be considered as a receiving unit, and when performing a sending operation, the transceiver unit 1220 can be considered as a sending unit. Alternatively, the transceiver unit 1220 can also be two functional modules, and the transceiver unit 1220 can be regarded as a general term for the two functional modules, which include a receiving unit and a sending unit. The sending unit is used to complete the sending operation, for example, the sending unit 1220 can be used to perform Figure 3 The embodiment shown to Fig. 9 In any of the embodiments shown in the drawings, all sending operations are performed by the terminal device or the network device; the receiving unit is used to complete the receiving operation, for example, the receiving unit can be used to perform Figure 3 The embodiment shown to Fig.10 All receiving operations performed by a terminal device or a network device in any of the illustrated embodiments.

[0514] For specific functions that can be implemented by the processing unit 1210 and the transceiver unit 1220, please refer to Figure 3The embodiment shown to Fig.10 For an introduction to the operations performed by the terminal device in any of the embodiments shown in the drawings, or referring to Figure 3 The embodiment shown to Fig.10 The description of the operations performed by the network device in any of the illustrated embodiments will not be repeated in detail.

[0515] It should be understood that the processor mentioned in the embodiments of the present application may be a CPU, or other general-purpose processors, digital signal processors (DSP), application-specific integrated circuits (ASIC), field programmable gate arrays (FPGA) or other programmable logic devices, discrete gate or transistor logic devices, discrete hardware components, etc. A general-purpose processor may be a microprocessor or the processor may also be any conventional processor, etc.

[0516] It should be noted that when the processor is a general-purpose processor, DSP, ASIC, FPGA or other programmable logic device, discrete gate or transistor logic device, discrete hardware component, the memory (storage module) is integrated in the processor.

[0517] It should be noted that the memory described herein is intended to include, but is not limited to, these and any other suitable types of memory.

[0518] It should be understood that in the various embodiments of the present application, the size of the serial numbers of the above-mentioned processes does not mean the order of execution. The execution order of each process should be determined by its function and internal logic, and should not constitute any limitation on the implementation process of the embodiments of the present application.

[0519] Those of ordinary skill in the art will appreciate that the units and algorithm steps of each example described in conjunction with the embodiments disclosed herein can be implemented in electronic hardware, or a combination of computer software and electronic hardware. Whether these functions are performed in hardware or software depends on the specific application and design constraints of the technical solution. Professional and technical personnel can use different methods to implement the described functions for each specific application, but such implementation should not be considered to be beyond the scope of this application.

[0520] In the several embodiments provided in the present application, it should be understood that the disclosed systems, devices and methods can be implemented in other ways. For example, the device embodiments described above are only schematic. For example, the division of the units is only a logical function division. There may be other division methods in actual implementation, such as multiple units or components can be combined or integrated into another system, or some features can be ignored or not executed. Another point is that the mutual coupling or direct coupling or communication connection shown or discussed can be through some interfaces, indirect coupling or communication connection of devices or units, which can be electrical, mechanical or other forms.

[0521] The units described as separate components may or may not be physically separated, and the components shown as units may or may not be physical units, that is, they may be located in one place or distributed on multiple network units. Some or all of the units may be selected according to actual needs to achieve the purpose of the solution of this embodiment.

[0522] In addition, each functional unit in each embodiment of the present application may be integrated into one processing unit, or each unit may exist physically separately, or two or more units may be integrated into one unit.

[0523] If the functions are implemented in the form of software functional units and sold or used as independent products, they can be stored in a computer-readable storage medium. Based on this understanding, the technical solution of the present application, or the part that contributes to the prior art or the part of the technical solution, can be embodied in the form of a software product, which is stored in a storage medium and includes several instructions for a computer device (which can be a personal computer, a server, or a network device, etc.) to perform all or part of the steps of the method described in each embodiment of the present application. The aforementioned computer-readable storage medium can be any available medium that can be accessed by a computer. By way of example and not limitation, computer-readable media may include random access memory (RAM), read-only memory (ROM), programmable read-only memory (PROM), erasable programmable read-only memory (EPROM), electrically erasable programmable read-only memory (EEPROM), compact disc read-only memory (CD-ROM), universal serial bus flash disk, mobile hard disk, or other optical disk storage, magnetic disk storage media or other magnetic storage devices, or any other medium that can be used to carry or store desired program code in the form of instructions or data structures and can be accessed by a computer. In addition, by way of example but not limitation, many forms of RAM are available, such as static random access memory (SRAM), dynamic random access memory (DRAM), synchronous dynamic random access memory (SDRAM), double data rate synchronous dynamic random access memory (DDRSDRAM), enhanced synchronous dynamic random access memory (ESDRAM), synchronous link dynamic random access memory (SLDRAM), or direct rambus RAM (DR RAM).

[0524] The above is only a specific implementation of the present application, but the protection scope of the embodiments of the present application is not limited thereto. Any technician familiar with the technical field can easily think of changes or substitutions within the technical scope disclosed in the embodiments of the present application, which should be included in the protection scope of the embodiments of the present application. Therefore, the protection scope of the embodiments of the present application should be based on the protection scope of the claims.

Claims

1. A communication method, applied to a second terminal device, characterized in that: receiving configuration information from the first network device, the configuration information being used to configure the second terminal device to switch to communicate with the third network device through the first terminal device, wherein the configuration information includes first timer information, and the first timer information is used for path switching; Starting the first timer; Establishing a PC5-S connection with the first terminal device, wherein the PC5-S connection is used for the second terminal device to communicate with the third network device through the first terminal device; An RRC reconfiguration completion message is sent to the first terminal device, wherein the RRC reconfiguration completion message is transmitted through a default PC5 RLC configuration, and the RRC reconfiguration completion message is used to trigger the first terminal device in an RRC idle state or an RRC inactive state to enter an RRC connected state.

2. The method according to claim 1, characterized in that Sending an RRC reconfiguration completion message to the first terminal device also includes: The RRC reconfiguration completion message is an RRC reconfiguration completion message sent by the second terminal device to the third network device.

3. The method according to claim 1 or 2, characterized in that: The configuration information includes first timer information, and the method further includes: The second terminal device configures the first timer according to the first timer information.

4. The method according to claim 1 or 2, characterized in that: The method further comprises: When one or more of the following conditions are met, the first timer is stopped: The second terminal device is connected to the PC5 of the first terminal device; or, The random access between the second terminal device and the third network device is successful; or, The second terminal device sends an RRC reconfiguration completion message to a lower layer of the second terminal device, and receives a confirmation feedback from the lower layer, wherein the lower layer is an RLC layer; or The second terminal device receives second indication information from the third network device, where the second indication information is used to instruct the second terminal device to stop the first timer; or, The second terminal device receives third indication information from the first terminal device, where the third indication information is used to instruct the second terminal device to stop the first timer, or the third indication information is used to indicate that the first terminal device has successfully randomly accessed the third network device; or, The second terminal device receives fourth indication information from the first terminal device, where the fourth indication information is used to indicate that a Uu wireless link failure occurs in the first terminal device or that the first terminal device fails to randomly access the third network device; or, The second terminal device fails to establish a connection with the PC5 of the first terminal device or determines that the PC5 wireless link fails.

5. The method according to claim 1 or 2, characterized in that: The method further comprises: The first timer times out and a reconstruction is performed.

6. The method according to claim 5, characterized in that Reconstruction including: Reconstruction through a relay device; or, Reconstruction through communities.

7. The method according to claim 1, 2 or 6, characterized in that: The first network device and the third network device are the same network device; or, The first network device and the third network device are different network devices.

8. A communication method, applied to a first terminal device, characterized in that: Establishing a PC5-S connection with a second terminal device, wherein the first terminal device is in an RRC idle state or an RRC inactive state, and the PC5-S connection is used for the second terminal device to communicate with a third network device through the first terminal device; Receiving an RRC reconfiguration completion message from the second terminal device through a default PC5 RLC configuration, wherein the RRC reconfiguration completion message is used to trigger the first terminal device in an RRC idle state or an RRC inactive state to enter an RRC connected state; Enter the RRC connected state; Send the RRC reconfiguration completion message to the third network device.

9. The method according to claim 8, characterized in that The first terminal device includes a PC5 RLC entity, and the method further includes: The PC5 RLC entity sends a reception confirmation feedback of the RLC PDU corresponding to the RRC reconfiguration completion message to the PC5 RLC entity of the second terminal device.

10. A communication device, characterized in that: The method comprises a transceiver unit and a processing unit, wherein the transceiver unit and the processing unit are coupled and can execute the method according to any one of claims 1 to 7, or execute the method according to any one of claims 8 to 9.

11. A computer-readable storage medium, characterized in that: The computer-readable storage medium is used to store a computer program, and when the computer program is run on a computer, the computer executes the method according to any one of claims 1 to 7, or the computer executes the method according to any one of claims 8 to 9.

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