Communication method and communication apparatus

Abstract

This application provides a communication method and a communications apparatus.SOLUTION: The method includes: A terminal device performs redirection from a source cell to a target cell, where the source cell is managed by a source access network device, and the target cell is managed by a target access network device. A terminal device sends a first report, where the first report includes information indicating that a failure may occur in a process of performing cell redirection by the terminal device, and includes identification information of a target cell. In this way, the first report is used to provide a reference for network parameter optimization, to improve an effect of mobility management performed by the network device on the terminal device.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] This application claims priority to Chinese Patent Application No. 202210295971.8, entitled "COMMUNICATION METHOD AND COMMUNICATION APPARATUS," filed with the State Intellectual Property Office of China on March 24, 2022, and to Chinese Patent Application No. 202210942532.1, entitled "COMMUNICATION METHOD AND COMMUNICATION APPARATUS," filed with the State Intellectual Property Office of China on August 8, 2022, both of which are incorporated herein by reference.

[0002] The present application relates to the field of communications, and more particularly to communication methods and devices. [Background technology]

[0003] Currently, a mobility robustness optimization (MRO) mechanism is supported in mobile communication systems. MRO is an important mechanism for network self-optimization. When a mobility-related failure event (e.g., a handover failure or a radio link failure (RLF) in a target cell) occurs on a terminal device, related parameters of the failure event are reported to a network device, so that the network device can analyze the obtained related parameters. This optimizes network parameters and further avoids the occurrence of failure events. However, the current MRO mechanism is not perfect. Summary of the Invention

[0004] The embodiments of the present application provide a communication method and a communication apparatus for improving the effect of mobility management implemented by a network device on a terminal device.

[0005] According to a first aspect, there is provided a communication method, which may be implemented by a terminal device or a module (e.g., a chip) disposed in (or used in) the terminal device.

[0006] The method includes: a terminal device performs redirection from a source cell to a target cell, the source cell being managed by a source access network device, and the target cell being managed by a target access network device; the terminal device sends a first report, the first report including information indicating a possibility of failure in a process of performing cell redirection by the terminal device, and including identification information of the target cell.

[0007] According to this solution, the terminal device sends a first report to a network device (e.g., a source access network device and / or a target access network device) to notify that there is a potential risk of failure in the process of performing cell redirection by the terminal device, so that the network device can use the first report as a criterion when performing network parameter optimization to reduce the probability of cell redirection failure for the terminal device and improve the effectiveness of mobility management performed by the network device for the terminal device.

[0008] By way of example, and not limitation, the first report includes a redirection success report, a random access report, or a connection setup failure report.

[0009] In relation to the first aspect, in some implementations of the first aspect, the method includes: when the redirection process of the terminal device satisfies a reporting condition, the terminal device records a first report, and the reporting condition is one of the following conditions: an operation period of the first timer is less than or equal to a first threshold and greater than or equal to a second threshold, the operation period of the first timer being a period from when the terminal device receives a radio resource control (RRC) release message from the source access network device to when the terminal device sends a random access preamble to the target access network device; an operation period of the second timer is less than or equal to a third threshold and greater than or equal to a fourth threshold, and the operation period of the second timer is a period from when the terminal device receives an RRC release message from the source access network device to when the terminal device receives an RRC connection setup message from the target access network device; The operation period of the third timer is less than or equal to a fifth threshold and greater than or equal to a sixth threshold, and the operation period of the third timer is a period from when the terminal device sends an RRC connection request message to the target access network device to when the terminal device receives an RRC connection setup message from the target access network device; or The terminal device fails to perform cell redirection on a first frequency and successfully performs cell redirection on a frequency other than the first frequency, where the first frequency is a candidate frequency configured for the terminal device by a source access network device and used for cell redirection, and the frequency of a target cell is a frequency other than the first frequency. Contains one or more of the following:

[0010] According to this solution, when the process of performing cell redirection by the terminal device satisfies one or more of the conditions, it may be considered that there is a potential risk of failure in the terminal device cell redirection process. The terminal device may record a first report and send the first report to the network device, so that the network device can perform network parameter optimization with reference to the first report to improve the effect of mobility management performed by the network device for the terminal device.

[0011] In relation to the first aspect, in some implementations of the first aspect, the second threshold is a product of the first threshold and a first coefficient, and / or the fourth threshold is a product of the third threshold and a second coefficient, and / or the sixth threshold is a product of the fifth threshold and a third coefficient, and the first coefficient, the second coefficient, and the third coefficient are less than 1.

[0012] In relation to the first aspect, in some implementations of the first aspect, the method includes: a terminal device receives first indication information, the first indication information indicating a reporting condition;

[0013] According to this solution, the network device may configure reporting conditions for sending a first report for the terminal device, whereby the terminal device can provide a report used for network parameter optimization for the network device based on the configuration requirements of the network device.

[0014] In relation to the first aspect, in some implementations of the first aspect, receiving the first indication information by the terminal device includes: receiving an RRC message by the terminal device, the RRC message including the first indication information;

[0015] By way of example and not limitation, the RRC messages may include, but are not limited to, one or more of an RRC Setup message, an RRC Reconfiguration message, an RRC Reestablishment message, an RRC Resume message, or an RRC Release message.

[0016] According to this solution, the source access network device may notify the terminal device of the reporting conditions for sending the first report by using an RRC message, so that the terminal device can record the report used for network parameter optimization based on the configuration requirements of the network device and provide the report to the network device.

[0017] In relation to the first aspect, in some implementations of the first aspect, the first report indicates one or more of the following: a reporting condition, source cell identification information, cell measurement information, redirection frequency information, target cell identification information, target cell frequency information, a first timer operation period, a second timer operation period, a third timer operation period, or a fourth timer operation period.

[0018] The cell identification information may include a cell identification information, which may be at least one of a cell global identifier (CGI), a physical cell identifier (PCI) and frequency, a non-public network identifier (NPN ID), a non-terrestrial network identifier (NTN ID), or another cell identifier of the cell. Optionally, the cell identification information may further include a tracking area code (TAC) and / or identification information, for example, a global network device identifier of a network device to which the cell belongs. The CGI may include a public land mobile network (PLMN) ID and a cell ID.

[0019] The cell measurement information includes measurement information of a source cell, measurement information of a target cell, measurement information of a neighboring cell of the source cell, or measurement information of a neighboring cell of the target cell. The cell measurement information may include measurement results obtained by the terminal device by measuring a signal (e.g., a reference signal) of the cell. In addition, the operation period of the fourth timer is the period from when the terminal device receives an RRC release message from the source access network device to when the terminal device successfully establishes a service channel with the target access network device. Alternatively, the operation period of the fourth timer is the period from when the terminal device receives an RRC release message from the source access network device to when the terminal device successfully communicates service data packets with the target access network device.

[0020] According to this solution, the first report may include one or more of the above information, and the terminal device provides information related to redirection of the terminal device to the network device by using the first report, so that the network device can accurately perform network parameter optimization by referring to the information in the first report, thereby improving the effectiveness of mobility management performed by the network device for the terminal device.

[0021] In relation to the first aspect, in some implementations of the first aspect, the terminal device sending the first report includes: the terminal device sending the first report to the target access network device.

[0022] According to this solution, the first report may be a report sent to the target access network device, whereby the target access network device can optimize the configuration of the target cell by referring to the first report.

[0023] In relation to the first aspect, in some implementations of the first aspect, the terminal device sending a first report includes: the terminal device sending a first report to a source access network device, where the first report includes identification information of a source cell.

[0024] According to this solution, the first report may be a report sent to the source access network device, whereby the target access network device can optimize the configuration of the source cell by referring to the first report.

[0025] According to the first aspect, in some implementations of the first aspect, the first report further includes second indication information, and the second indication information indicates whether the cell redirection is triggered by a service or by signal coverage quality. Optionally, the service may be a voice service.

[0026] According to this solution, the terminal device uses the second indication information in the first report to inform the network device that the cell redirection is triggered by the service or the signal coverage quality, so that the network device can determine the cause of triggering the cell redirection based on the second indication information, perform network parameter optimization more accurately, and reduce unnecessary or erroneous network parameter optimization.

[0027] In relation to the first aspect, in some implementations of the first aspect, the cell redirection is triggered by a service, and the target access network device and the source access network device use different radio access technologies (RATs).

[0028] According to a second aspect, there is provided a communication method. For advantageous effects, please refer to the description in the first aspect. Details will not be described again here. The method can be implemented by an access network device or a module (e.g., a chip) disposed in (or used in) an access network device.

[0029] The method includes receiving a first report from a terminal device, the first report including information indicating a possibility of failure in a process of performing cell redirection by the terminal device, and including identification information of a target cell for redirection of the terminal device, the target cell being managed by the target access network device.

[0030] In relation to the second aspect, in some implementations of the second aspect, the method further includes sending a first report to the source access network device, the first report including identification information of a source cell for redirection of the terminal device, the source cell being managed by the source access network device.

[0031] In relation to the second aspect, in some implementations of the second aspect, the method further includes adjusting a network configuration parameter based on the first report.

[0032]

[0023] In relation to the second aspect, in some implementations of the second aspect, the first report indicates a reporting condition for triggering the terminal device to send the first report, and the reporting condition is one of the following conditions: An operation period of the first timer is less than or equal to a first threshold and greater than or equal to a second threshold, and the operation period of the first timer is a period from when the terminal device receives a radio resource control (RRC) release message from the source access network device to when the terminal device sends a random access preamble to the target access network device; an operation period of the second timer is less than or equal to a third threshold and greater than or equal to a fourth threshold, and the operation period of the second timer is a period from when the terminal device receives an RRC release message from the source access network device to when the terminal device receives an RRC connection setup message from the target access network device; The operation period of the third timer is less than or equal to a fifth threshold and greater than or equal to a sixth threshold, and the operation period of the third timer is a period from when the terminal device sends an RRC connection request message to the target access network device to when the terminal device receives an RRC connection setup message from the target access network device; or The terminal device fails to perform cell redirection on a first frequency and successfully performs cell redirection on a frequency other than the first frequency, where the first frequency is a candidate frequency configured for the terminal device by a source access network device and used for cell redirection, and the frequency of a target cell is a frequency other than the first frequency. Contains one or more of the following:

[0033] The source access network device manages the source cell for cell redirection.

[0034] In relation to the second aspect, in some implementations of the second aspect, the second threshold is the product of the first threshold and the first coefficient; and / or the fourth threshold is the product of the third threshold and the second factor; and / or The sixth threshold is the product of the fifth threshold and the third coefficient, The first coefficient, the second coefficient, and the third coefficient are less than one.

[0035] Related to the second aspect, in some implementations of the second aspect, the first report indicates one or more of source cell identification information, target cell identification information, cell measurement information, redirection frequency information, target cell frequency information, a first timer operation period, a second timer operation period, a third timer operation period, or a fourth timer operation period.

[0036] The cell measurement information includes measurement information of a source cell, measurement information of a target cell, measurement information of a neighboring cell of the source cell, or measurement information of a neighboring cell of the target cell. The operation period of the fourth timer is a period from when the terminal device receives an RRC release message from the source access network device to when the terminal device successfully establishes a service channel with the target access network device. Alternatively, the operation period of the fourth timer is a period from when the terminal device receives an RRC release message from the source access network device to when the terminal device successfully communicates service data packets with the target access network device.

[0037] In relation to the second aspect, in some implementations of the second aspect, the method further includes sending first indication information to the terminal device, where the first indication information indicates a reporting condition.

[0038] In relation to the second aspect, in some implementations of the second aspect, sending the first indication information to the terminal device includes sending an RRC message to the terminal device, and the RRC message includes the first indication information.

[0039] In some implementations of the second aspect, the first report further includes second indication information, and the second indication information indicates whether the cell redirection is triggered by a service or by signal coverage quality. Optionally, the service may be a voice service.

[0040] In relation to the second aspect, in some implementations of the second aspect, redirection of the terminal device is triggered by a service, the target access network device and the source access network device use different radio access technologies (RATs), and the source access network device manages the source cell for the cell redirection.

[0041] According to a third aspect, there is provided a communication method, which may be implemented by a terminal device or a module (e.g., a chip) disposed in (or used in) a terminal device.

[0042] The method includes: a terminal device fails to perform handover to a first cell; the terminal device establishes a communication connection with an access network device in a second cell, the access network device managing the second cell; the terminal device sends a second report to the access network device, the second report indicating that the terminal device fails to perform handover to the first cell, the second report including fourth indication information, the fourth indication information indicating that the handover of the terminal device to the first cell is triggered by a service or by signal coverage quality; Optionally, the service may be a voice service.

[0043] By way of example and not limitation, the second report includes a radio link failure report or a connection setup failure report.

[0044] According to this solution, after performing the cell handover, the terminal device sends a second report to the network device to notify the network device that the terminal device fails to perform the handover to the first cell, so that the network device performs network parameter optimization by referring to the second report. The second report indicates a handover cause that indicates a trigger for the cell handover. This can improve the accuracy of the network parameter optimization and reduce unnecessary or erroneous network parameter optimization.

[0045] In relation to the third aspect, in some implementations of the third aspect, the first cell and the second cell use the same radio access technology RAT.

[0046] For example, a terminal device performs an inter-RAT network (or inter-system) cell handover from a source cell, and the source access network device indicates to the terminal device to perform a handover to a first cell whose RAT is different from that of the source cell. If the terminal device fails to perform the handover to the first cell, it continues to perform cell selection in a network whose RAT (or system) is the same as that of the network in which the first cell is located, and attempts to access the network device. In other words, the terminal device selects a cell whose RAT is the same as that of the first cell, and then successfully selects an appropriate cell, for example, a second cell whose RAT is the same as that of the first cell, and the terminal device establishes a communication connection with the access network device in the second cell. Therefore, the RAT of the second cell is the same as that of the first cell.

[0047] In relation to the third aspect, in some implementations of the third aspect, the first cell and the second cell use different radio access technologies (RATs).

[0048] In another example, the source access network device indicates to the terminal device to perform a handover to a first cell whose RAT is different from that of the source cell. If the terminal device fails to perform the handover to the first cell, it continues to perform cell selection in a network whose RAT (or system) is the same as that of the network in which the first cell is located, and attempts to access the network. If the service is a normal voice service, the condition to be met is that of a suitable cell. If the service is an emergency voice service, the condition to be met is that of a suitable cell and an acceptable cell. If the service is an emergency voice service, the terminal device first attempts to select a suitable cell, and if a suitable cell is not selected, the terminal device may select an acceptable cell. However, the terminal device does not select a cell that meets the condition and re-establishes a connection with the source cell. In other words, in this example, the second cell is the source cell of the terminal device, and the RAT of the second cell is different from that of the first cell.

[0049] According to a fourth aspect, there is provided a communication method, which may be implemented by an access network device or a module (e.g., a chip) disposed in (or used in) an access network device.

[0050] The method includes receiving a second report from the terminal device, the second report indicating that the terminal device fails to perform a handover to the first cell, and the second report includes fourth indication information, the fourth indication information indicating that the handover of the terminal device to the first cell is triggered by a service or by signal coverage quality.

[0051] According to a fifth aspect, there is provided a communications apparatus. In design, the apparatus may include modules that correspond one-to-one to the methods / operations / steps / actions described in the first aspect. The modules may be implemented using hardware circuitry, software, or a combination of hardware circuitry and software. In design, the apparatus includes: a processing unit configured to determine that a terminal device performs redirection from a source cell to a target cell, where the source cell is managed by a source access network device and the target cell is managed by the target access network device; and a transceiver unit configured to send a first report, the first report including information indicating a possibility of failure in a process of performing cell redirection by the terminal device and including identification information of a target cell; Includes:

[0052] In relation to the fifth aspect, in some implementations of the fifth aspect, the transceiver unit is specifically configured to send a first report when the cell redirection process satisfies a reporting condition. For the reporting condition, please refer to the above description. For brevity, the details will not be described again here.

[0053] In relation to the fifth aspect, in some implementations of the fifth aspect, the transceiver unit is further configured to receive first indication information, where the first indication information indicates a reporting condition.

[0054] In relation to the fifth aspect, in some implementations of the fifth aspect, the transceiver unit is specifically configured to receive an RRC message, where the RRC message includes the first indication information.

[0055] In relation to the fifth aspect, in some implementations of the fifth aspect, the first report includes one or more of a reporting condition, source cell identification information, target cell identification information, cell measurement information, redirection frequency information, target cell frequency information, a first timer operation period, a second timer operation period, a third timer operation period, or a fourth timer operation period.

[0056] The cell measurement information includes measurement information of a source cell, measurement information of a target cell, measurement information of a neighboring cell of the source cell, or measurement information of a neighboring cell of the target cell. The operation period of the fourth timer is a period from when the terminal device receives an RRC release message from the source access network device to when the terminal device successfully establishes a service channel with the target access network device. Alternatively, the operation period of the fourth timer is a period from when the terminal device receives an RRC release message from the source access network device to when the terminal device successfully communicates service data packets with the target access network device.

[0057] With respect to the fifth aspect, in some implementations of the fifth aspect, the transceiver unit is specifically configured to send a first report to the target access network device.

[0058] In relation to the fifth aspect, in some implementations of the fifth aspect, the transceiver unit is specifically configured to send a first report to the source access network device, where the first report includes identification information of the source cell.

[0059] According to the fifth aspect, in some implementations of the fifth aspect, the first report further includes second indication information, and the second indication information indicates whether the cell redirection is triggered by a service or by signal coverage quality. Optionally, the service may be a voice service.

[0060] In relation to the fifth aspect, in some implementations of the fifth aspect, the sending of the first report by the terminal device includes: the cell redirection is triggered by a voice service, and the target access network device and the source access network device use different radio access technologies (RATs).

[0061] According to a sixth aspect, there is provided a communications apparatus. In a design, the apparatus may include modules corresponding one-to-one to the methods / operations / steps / actions described in the second aspect. The modules may be implemented using hardware circuits, software, or a combination of hardware circuits and software. In a design, the apparatus includes: a transceiver unit configured to receive a first report from a terminal device, the first report including information indicating a likelihood of failure in a process of performing cell redirection by the terminal device and including identification information of a target cell for cell redirection, the target cell being managed by the target access network device; and a processing unit configured to determine, based on the first report, a likelihood of failure in the process of performing cell redirection by the terminal device.

[0062] In relation to the sixth aspect, in some implementations of the sixth aspect, the transceiver unit is further configured to send a first report to the source access network device, the first report including identification information of a source cell for cell redirection, the source cell being managed by the source access network device.

[0063]

[0013] Related to the sixth aspect, in some implementations of the sixth aspect, the processing unit is further configured to adjust a network configuration parameter based on the first report.

[0064] In relation to the sixth aspect, in some implementations of the sixth aspect, the first report indicates a reporting condition for triggering the terminal device to send the first report. For the reporting condition, please refer to the above description. For brevity, the details will not be described again here.

[0065] Related to the sixth aspect, in some implementations of the sixth aspect, the first report indicates one or more of source cell identification information, target cell identification information, cell measurement information, redirection frequency information, target cell frequency, first timer operation period, second timer operation period, third timer operation period, or fourth timer operation period.

[0066] The cell measurement information includes measurement information of a source cell, measurement information of a target cell, measurement information of a neighboring cell of the source cell, or measurement information of a neighboring cell of the target cell. The operation period of the fourth timer is a period from when the terminal device receives an RRC release message from the source access network device to when the terminal device successfully establishes a service channel with the target access network device. Alternatively, the operation period of the fourth timer is a period from when the terminal device receives an RRC release message from the source access network device to when the terminal device successfully communicates service data packets with the target access network device.

[0067] In relation to the sixth aspect, in some implementations of the sixth aspect, the transceiver unit is further configured to send first indication information to the terminal device, where the first indication information indicates a reporting condition.

[0068] In relation to the sixth aspect, in some implementations of the sixth aspect, the transceiver unit is specifically configured to send an RRC release message to the terminal device, and the RRC release message includes first indication information.

[0069] According to the sixth aspect, in some implementations of the sixth aspect, the first report further includes second indication information, and the second indication information indicates whether the cell redirection is triggered by a service or by signal coverage quality. Optionally, the service may be a voice service.

[0070] In relation to the sixth aspect, in some implementations of the sixth aspect, the cell redirection is triggered by a service, the target access network device and the source access network device use different radio access technologies (RATs), and the source access network device manages the source cell for the cell redirection.

[0071] According to a seventh aspect, there is provided a communications apparatus. In a design, the apparatus may include modules corresponding one-to-one to the methods / operations / steps / actions described in the third aspect. The modules may be implemented using hardware circuits, software, or a combination of hardware circuits and software. In a design, the apparatus includes: a processing unit configured to determine that a terminal device fails to perform a handover to a first cell, the processing unit being further configured to determine that the terminal device establishes a communication connection with a second cell; and a transceiver unit configured to send a second report to an access network device, the second report indicating that the terminal device fails to perform a handover to the first cell, the second report including fourth indication information, the fourth indication information indicating that the handover of the terminal device to the first cell is triggered by a service or by signal coverage quality, and the second cell being managed by the access network device.

[0072] According to an eighth aspect, there is provided a communications apparatus. In a design, the apparatus may include modules corresponding one-to-one to the methods / operations / steps / actions described in the fourth aspect. The modules may be implemented using a hardware circuit, software, or a combination of a hardware circuit and software. In a design, the communications apparatus includes: a transceiver unit configured to receive a second report from a terminal device, the second report indicating that the terminal device fails to perform a handover to the first cell, the second report including fourth indication information, the fourth indication information indicating that the handover of the terminal device to the first cell is triggered by a service or by signal coverage quality, the second cell being a cell managed by the access network device; and a processing unit configured to determine, based on the fourth indication information, that the handover of the terminal device to the first cell is triggered by a service or by signal coverage quality.

[0073] According to a ninth aspect, there is provided a communication device. The communication device includes a processor. The processor may implement the method of the first aspect, the third aspect, or any one of possible implementations of the first aspect or the third aspect. Optionally, the communication device further includes a memory. The processor may be coupled to the memory and configured to execute instructions in the memory to implement the method of the first aspect, the third aspect, or any one of possible implementations of the first aspect or the third aspect. Optionally, the communication device further includes a communication interface, and the processor is coupled to the communication interface. In an embodiment of the present application, the communication interface may be a transceiver, a pin, a circuit, a bus, a module, or another type of communication interface. This is not limited thereto.

[0074] In some implementations, the communication device is a terminal device. When the communication device is a terminal device, the communication interface may be a transceiver or an input / output interface.

[0075] In another implementation, the communication device is a chip disposed in a terminal device.When the communication device is a chip disposed in a terminal device, the communication interface may be an input / output interface.

[0076] Optionally, the transceiver may be a transceiver circuit. Optionally, the input / output interface may be an input / output circuit.

[0077] According to a tenth aspect, there is provided a communications device. The communications device includes a processor. The processor may implement the method of the second aspect, the fourth aspect, or any one of possible implementations of the second aspect or the fourth aspect. Optionally, the communications device further includes a memory. The processor may be coupled to the memory and configured to execute instructions in the memory to implement the method of the second aspect, the fourth aspect, or any one of possible implementations of the second aspect or the fourth aspect. Optionally, the communications device further includes a communications interface, and the processor is coupled to the communications interface.

[0078] In one implementation, the communication device is a network device. When the communication device is a network device, the communication interface may be a transceiver or an input / output interface.

[0079] In another implementation, the communication device is a chip disposed in the network device.When the communication device is a chip disposed in the network device, the communication interface may be an input / output interface.

[0080] Optionally, the transceiver may be a transceiver circuit. Optionally, the input / output interface may be an input / output circuit.

[0081] According to an eleventh aspect, there is provided a processor, the processor including an input circuit, an output circuit, and a processing circuit, the processing circuit configured to receive a signal through the input circuit and to transmit a signal through the input circuit, whereby the processor performs a method in any one of the first to fourth aspects or possible implementations of the first to fourth aspects.

[0082] In a specific implementation process, the processor may be one or more chips, the input circuit may be an input pin, the output circuit may be an output pin, and the processing circuit may be a transistor, a gate circuit, a trigger, any logic circuit, etc. For example, but not limited to, an input signal received by an input circuit may be received and input by a receiver, and a signal output by an output circuit may be output to a transmitter and transmitted by the transmitter, and the input circuit and the output circuit may be the same circuit, which is used as an input circuit and an output circuit at different moments, respectively. The specific implementation of the processor and various circuits is not limited to the embodiments of the present application.

[0083] According to a twelfth aspect, there is provided a computer program product. The computer program product includes a computer program (sometimes called code or instructions). When the computer program is executed on a computer, the computer is enabled to perform the method of any one of the first to fourth aspects or possible implementations of the first to fourth aspects.

[0084] According to a thirteenth aspect, there is provided a computer-readable storage medium. The computer-readable storage medium stores a computer program (sometimes called code or instructions). When the computer program is executed on a computer, the computer is enabled to perform the method of any one of the first to fourth aspects or possible implementations of the first to fourth aspects.

[0085] According to a fourteenth aspect, there is provided a communication system, the communication system including at least one communication device provided in the fifth aspect and at least one communication device provided in the sixth aspect, and / or at least one communication device provided in the seventh aspect and at least one communication device provided in the eighth aspect. [Brief explanation of the drawings]

[0086] [Figure 1] 1 is a diagram of a communication system according to an embodiment of the present application; [Figure 2] 1 is a schematic flowchart of a communication method according to an embodiment of the present application; [Figure 3] 3 is a schematic flowchart of a cell redirection process according to an embodiment of the present application; [Figure 4] 1 is a schematic flowchart of a communication method according to an embodiment of the present application; [Figure 5] 4 is another schematic flowchart of a communication method according to an embodiment of the present application; [Figure 6] 4 is another schematic flowchart of a communication method according to an embodiment of the present application; [Figure 7] 4 is another schematic flowchart of a communication method according to an embodiment of the present application; [Figure 7A] 4 is another schematic flowchart of a communication method according to an embodiment of the present application; [Figure 7B] 4 is another schematic flowchart of a communication method according to an embodiment of the present application; [Figure 8] 1 is a block diagram of a communication device according to an embodiment of the present application; [Figure 9] FIG. 2 is a diagram of the structure of a terminal device according to an embodiment of the present application; [Figure 10] FIG. 2 is a diagram of the structure of a network device according to an embodiment of the present application. DETAILED DESCRIPTION OF THE INVENTION

[0087] The technical solutions of the present application are described below with reference to the accompanying drawings.

[0088] In the embodiments of the present application, " / " may represent an "or" relationship between related objects. For example, A / B may represent A or B. "And / or" may be used to describe three relationships between related objects. For example, A and / or B may represent the following three cases: only A exists, both A and B exist, and only B exists. A and B may be singular or plural. To facilitate the description of the technical solutions of the embodiments of the present application, terms such as "first" and "second" may be used for distinction in the embodiments of the present application. Terms such as "first" and "second" do not limit the quantity and execution sequence, and terms such as "first" and "second" do not limit clear differences. In the embodiments of the present application, terms such as "example" or "for example" represent an example, evidence, or explanation. Any embodiment or design solution described as an "example" or "for example" should not be construed as being preferred or having more advantages over another embodiment or design solution. Words such as "example" or "for example" are used to present related concepts in a specific way for ease of understanding. In the embodiments of the present application, "at least one (type)" may alternatively be described as "one (type) or multiple (types)," and "multiple (types)" may be two (types), three (types), four (types), or five or more (types). This is not limited in the embodiments of the present application.

[0089] The technical solutions in the embodiments of the present application are applicable to various communication systems, such as a long term evolution (LTE) system, an LTE frequency division duplex (FDD) system, an LTE time division duplex (TDD) system, a universal mobile telecommunications system (UMTS), a worldwide interoperability for microwave access (WiMAX) communication system, and a fifth generation (5G) communication system. th In addition, the communication method provided in the present application may also be applied to a communication system in a next generation evolved public land mobile network (PLMN), or another communication system, etc. This is not limited in the present application.

[0090] FIG. 1 is a diagram of a wireless communication system 100 applicable to embodiments of the present application.

[0091] As shown in FIG. 1, the wireless communication system 100 may include at least two access network devices, such as access network device 110 and access network device 120 shown in FIG. 1. The wireless communication system 100 may further include at least one terminal device, such as terminal device 130 shown in FIG. 1. One access network device may manage at least one cell. For example, access network device 110 manages cell 1, and access network device 120 manages cell 2. When a terminal device enters the coverage area of ​​a cell, it may access the cell and communicate with the access network device that manages the cell by using the cell. For example, terminal device 130 enters the coverage area of ​​cell 1. The terminal device 130 may obtain communication services of access network device 110 by accessing and using cell 1. In other words, cell 1 is used as the serving cell of the terminal device. Cell handover or redirection may occur during the mobility process of the terminal device. For example, when the terminal device enters the coverage area of ​​cell 2 and the signal quality of cell 2 is good, the terminal device may perform a handover or redirection from cell 1 to cell 2. The terminal device disconnects from cell 1 and accesses cell 2. Alternatively, the handover or redirection of the terminal device from cell 1 to cell 2 may be triggered by a service. For example, access network device 110 and access network device 120 use different radio access technologies. The handover or redirection of the terminal device from cell 1 to cell 2 may be triggered by a voice service.

[0092] In a scenario where a terminal device performs a handover from cell 1 to cell 2, after exchanging information with the access network device 120, the access network device 110 indicates to the terminal device to perform a handover to cell 2 and provides related access information of cell 2 to the terminal device 130. The terminal device accesses cell 2 based on the indication of the access network device 110 and obtains communication services of the access network device 120 by using cell 2. In other words, cell 2 is used as the serving cell of the terminal device. In this way, handover from cell 1 to cell 2 is completed. Cell 1 may be referred to as a source cell for handover of the terminal device, and cell 2 may be referred to as a target cell for handover of the terminal device.

[0093] In a scenario in which a terminal device performs redirection from cell 1 (which may also be referred to as a source cell for redirection) to cell 2 (which may also be referred to as a target cell for redirection), the terminal device may perform cell selection on candidate frequencies provided by access network device 110, and after determining that cell 2 is to be used as the target cell for redirection, access cell 2 and obtain communication services of access network device 120 by using cell 2. In other words, cell 2 is used as the serving cell of the terminal device. In this way, redirection from cell 1 to cell 2 is completed.

[0094] The terminal device in the embodiments of the present application may also be referred to as user equipment (UE), access terminal, subscriber unit, subscriber station, mobile station, remote station, remote terminal, mobile device, user terminal, terminal, wireless communication device, user agent, or user equipment. The terminal device in the embodiments of the present application may be a mobile phone, a tablet computer (pad), a computer with wireless transceiver function, a virtual reality (VR) terminal device, an augmented reality (AR) terminal device, an in-vehicle device, a wearable device, a terminal device in a next-generation evolved PLMN, etc.

[0095] It should be understood that the embodiments of the present application are not limited to a specific form of the terminal device.

[0096] The access network node in the embodiment of the present application may be a device having wireless transceiver functionality, or may be referred to as an access network device or a network device. The device may include, but is not limited to, a device having some or all of the functionality of a base station, such as an evolved NodeB (eNodeB), th Next generation Node B (gNB) in 5th generation (5G) mobile communication systems, 6 th This includes a next generation NodeB (gNB) in a 6th generation (6G) mobile communication system, a base station, transmission reception point (TRP), or access point (AP) in a next generation mobile communication system, a wireless relay node, or a wireless backhaul node in a wireless fidelity (Wi-Fi) system.

[0097] In some deployments, an access network node may include a central unit (CU) and / or distributed units (DUs). The CU and DU may separately implement some of the base station's functionality. For example, the CU is responsible for processing non-real-time protocols and services and implements radio resource control (RRC) and packet data convergence protocol (PCCP) layer functions. The DU is responsible for processing physical layer protocols and real-time services and implements radio link control (RLC), media access control (MAC), and physical (PHY) layer functions. The access network node may further include an active antenna unit (AAU). The AAU may implement part of the physical layer, processing functions, radio frequency processing, and active antenna-related functions.

[0098] In the following, first, relevant technologies and terms in the embodiments of the present application will be described.

[0099] 1. Cells and carriers

[0100] A cell can be understood as a coverage area of ​​a radio signal identified by a cell identity. From the perspective of resource management, a cell is a unit used by a network device to manage wireless communication resources. The physical layer resources of a cell include a carrier, which is a physical resource used to carry the radio signals of an access network device, and is represented by a carrier frequency and a bandwidth of a carrier frequency band. The carrier may be called the operating carrier of the cell, and the carrier frequency may be called the operating frequency of the cell.

[0101] 2. Cell selection

[0102] The terminal device may perform cell selection on a candidate frequency (or a candidate cell frequency) through frequency scanning. Specifically, the terminal device detects a synchronization signal of the cell on the candidate frequency through frequency scanning, obtains the signal quality of the cell based on the detected synchronization signal, and determines whether to access the cell.

[0103] 3. Cell Handover

[0104] The access network device connected to the terminal device (i.e., the source access network device) determines the target cell to which the terminal device will perform handover based on the measurement result, exchanges information (such as resource request and data transfer) with the target access network device that manages the target cell to complete handover preparation, and uses a handover command to indicate to the terminal device to perform handover to the target cell. After the terminal device successfully accesses the target cell, the target access network device notifies the source access network device to release the resources of the terminal device.

[0105] 4. Cell Redirection

[0106] When a terminal device is in a connected state, a source access network device may configure one or more candidate frequencies for cell redirection. After the terminal device receives a radio resource control (RRC) release message from the source access network device in the source cell, the process of performing cell selection on one or more candidate frequencies, selecting a target cell, and accessing the cell is referred to as a cell redirection process for redirection from a source cell to a target cell. Cell redirection of a terminal device may be triggered by signal coverage quality. For example, the network device may determine the coverage of a serving cell and / or the coverage of a neighboring cell of the serving cell based on measurement results reported by the terminal device to trigger redirection of the terminal device. For example, the network device may determine that the signal quality of the serving cell is insufficient based on the measurement results reported by the terminal device, for example, by determining that the signal quality of the serving cell is below a predetermined threshold or that the signal quality of the serving cell is inferior to the signal quality of a neighboring cell, thereby triggering redirection of the terminal device. Alternatively, the network device determines that the signal quality of the neighboring cell is good based on measurement results reported by the terminal device, for example, determining that the signal quality of the neighboring cell is better than the signal quality of the serving cell based on the measurement report, or that the signal quality of the neighboring cell is higher than a preset threshold, thereby determining that the signal quality of the neighboring cell is good. Alternatively, the cell redirection of the terminal device may be triggered by a voice service.

[0107] The difference between cell redirection and cell handover is that in cell handover, the target cell to which the terminal device performs handover is indicated to the terminal device after the source access network device interacts with the target access network device, and the terminal device accesses the target cell based on the target cell relationship information provided by the source access network device; while in cell redirection, the source access network device provides candidate frequencies for the terminal device, and the target cell for redirection of the terminal device is selected after the terminal device performs cell selection on the candidate frequencies.

[0108] 5. Voice Services

[0109] Voice service is one of the core services of mobile communication networks. thSince the Internet Protocol (IP) era of 4G (5G) mobile communication networks, the packet switched (PS) domain has been replaced by the circuit switched (CS) domain, and the primary voice policy includes voice over LTE (VoLTE) based on IP multimedia subsystem (IMS) and CS fallback. In 5G mobile communication networks, if the NR cell (i.e., a cell using NR radio access technology) connected to the terminal device does not support the IMS-based voice over NR (VoNR) policy, the network may instruct the terminal device to perform cell handover or cell redirection to fall back to a cell in the 4G network (voice fallback) to complete the voice service. If the quality of the VoNR service of the terminal device in the connected NR cell is not ideal, the access network device in the 5G network to which the terminal device is currently connected may indicate to the terminal device to perform cell handover or cell redirection, and the terminal device connects to the access network device in the 4G network by performing cell handover or cell redirection to complete the voice service in the cell in the 4G network. After the voice service is completed, the terminal device returns to the NR cell through a fast return mechanism. The voice service can be a normal voice service or an emergency voice service. In implementation, the "service" in this application can be understood as a "voice service."

[0110] 6. Suitable and acceptable cells in the cell selection process

[0111] A suitable cell is a cell on which a terminal device can camp and obtain normal service. A suitable cell must meet the following requirements:

[0112] - The cell is part of the selected PLMN, the registered PLMN or an equivalent PLMN.

[0113] - Cells are not prohibited.

[0114] - The cell is not part of the list of "Prohibited Tracking Areas for Roaming".

[0115] - The cell meets the cell selection criteria.

[0116] An acceptable cell is a cell on which a terminal device may camp and obtain limited service. An acceptable cell must meet the following requirements:

[0117] - Cells are not prohibited.

[0118] - The cell meets the cell selection criteria.

[0119] The above requirements for an acceptable cell are the minimum requirements for initiating emergency calls and receiving earthquake and tsunami warning system (ETWS) and commercial mobile alert system (CMAS) notifications in an NR network.

[0120] DETAILED DESCRIPTION OF THE INVENTION The communication method provided in the embodiments of the present application will be described below with reference to the accompanying drawings.

[0121] FIG. 2 is a schematic flowchart 200 of a communication method according to an embodiment of the present application.

[0122] S201: A terminal device performs redirection from a source cell to a target cell.

[0123] The source cell is managed by a source access network device, and the target cell is managed by a target access network device. In this embodiment of the present application, the source cell for cell redirection is a serving cell before the terminal device performs cell redirection, and the target cell is a cell from which the terminal device accesses the network through cell redirection, i.e., a serving cell after cell redirection.

[0124] In the implementation, cell redirection of the terminal device is triggered by the voice service.

[0125] For example, the serving cell of a terminal device is an NR cell, and the 5G network in which the NR cell is located does not support VoNR policy and cannot provide voice service to the terminal device. When the terminal device has voice service data to send or receive, the source access network device may instruct the terminal device to fall back to a cell in a 4G network through cell redirection to complete the voice service data transmission. Specifically, the source access network device may send an RRC release message to the terminal device and instruct the terminal device to perform cell redirection by using the RRC release message. The RRC release message may further indicate one or more candidate frequencies for the terminal device to perform cell redirection, and the candidate frequencies indicated by the RRC release message are evolved universal mobile telecommunications system (UMTS) terrestrial radio access (E-UTRA) frequencies of the 4G network. E-UTRA is an access network technology in the 4G network. The E-UTRA frequencies are 4G radio access frequencies, i.e., frequencies used by cells in the 4G network. A cell in a 4G network may be referred to as an E-UTRA cell, i.e., a cell using E-UTRA technology. The terminal device performs cell selection on an E-UTRA candidate frequency to access the 4G network by using a cell in the 4G network, thereby performing voice service data transmission. Alternatively, if the network in which the source cell is located supports VoNR, but the quality of the voice service of the terminal device in a cell that supports VoNR does not meet the service requirements, the source access network device may instruct the terminal device to perform cell redirection. This is not a limitation of the present application.

[0126] In another implementation, cell redirection of the terminal device is triggered by signal coverage quality.

[0127] For example, when the source cell is the serving cell of a terminal device, the terminal device may measure the signal quality of nearby cells (sometimes referred to as neighbor cells), send a measurement report to the source access network device, and notify the source access network device of the measurement results of the signal quality of the neighbor cells. Based on the measurement results, the source access network device may determine that the signal coverage quality of the source cell is insufficient or that the signal coverage quality of the neighbor cells is good, and instruct the terminal device to perform cell redirection. Specifically, the source access network device may instruct the terminal device to perform cell redirection by using an RRC release message. The RRC release message further indicates one or more candidate frequencies for the terminal device to perform cell redirection. The one or more candidate frequencies may be referred to as redirection frequencies. Optionally, the candidate frequencies may include frequencies of neighbor cells whose signal quality is better than that of the source cell. The terminal device performs cell selection on the candidate frequencies to re-access the cell. However, the present application is not limited thereto. The measurement result for triggering cell redirection may be the signal quality of the source cell obtained by the terminal device through measurement. When the signal quality of the source cell does not meet the service requirements or the signal quality of the neighboring cells of the source cell is good, the source access network device may indicate to the terminal device to perform cell redirection.

[0128] For example, a cell redirection process in which a terminal device performs redirection from a source cell to a target cell may be shown in FIG. 3. In S301, the source access network device sends an RRC release message to the terminal device. The RRC release message indicates that the RRC connection between the terminal device and the network is released and further indicates to the terminal device to perform cell redirection. The RRC release message may include information about candidate frequencies for performing cell redirection by the terminal device, and the terminal device selects a cell for redirection on the candidate frequencies indicated by the source access network device. In S302, after determining the target cell, the terminal device sends a random access preamble to the target access network device. In S303, when the target access network device receives the random access preamble, the target access network device sends a random access response message to the terminal device, thereby allowing the terminal device to communicate with the target access network device in the target cell. In S304, the terminal device subsequently sends an RRC connection request message to the target access network device to request establishing a radio resource control connection with the network. The target access network device determines whether to allow the terminal device to access the network based on the RRC connection request message. If the target access network device allows the terminal device to access the network, in S305, the target access network device sends an RRC connection setup message to the terminal device and configures corresponding RRC resources for the terminal device by using the RRC connection setup message. After completing the resource configuration, the terminal device sends an RRC connection setup complete message to the target access network device in S306. The terminal device establishes an RRC connection with the network and completes the cell redirection process for redirection from the source cell to the target cell.

[0129] S202: The terminal device sends a first report, which includes information indicating that the terminal device may fail in the process of performing redirection, and includes identification information of the target cell.

[0130] The first report may indicate information about a cause for the terminal device to perform a cell change, for example, the information about the cause indicates that the cause may be a voice service feedback, or that the cause may be a normal voice service feedback or an emergency voice service feedback.

[0131] After the terminal device successfully performs redirection from the source cell to the target cell, if there is a risk of potential failure in the process in which the terminal device performs redirection from the source cell to the target cell, the terminal device sends a first report to notify the network of the risk of potential failure in the cell redirection process, so that the network can perform network parameter optimization by referring to the first report of the terminal device, thereby improving network performance and reducing the probability of occurrence of a mobility failure event.

[0132] In the example, the first report may be referred to as a redirect success report.

[0133] In another example, the first report may be referred to as a random access report, and the first report may further indicate that the cause of the random access between the terminal device and the target cell is that the random access is triggered by a service.

[0134] For example, the first report indicates that the cause of the random access between the terminal device and the target cell is that the random access is triggered by a service, and the first report further indicates information that there may be a failure in the process of performing cell redirection by the terminal device.

[0135] In yet another example, the first report may be referred to as a connection setup failure report, and the first report indicates a failure to establish a connection between the terminal device and a third-party access network device (a third-party access network device is an access network device other than the source access network device and the target access network device).

[0136] For example, the terminal device fails to perform cell redirection on a first frequency in the redirection frequencies. Specifically, the terminal device attempts to establish a connection with a third-party access network device on the first frequency. For example, the terminal device attempts to access the third-party access network device but cannot establish the connection. The terminal device records a first report, where the first report indicates a failure to establish a connection between the terminal device and the third-party access network device. Optionally, the first report alternatively indicates information indicating a failure in the process of performing cell redirection by the terminal device.

[0137] It should be noted that the terminal device sending the first report to the network may be the terminal device sending the first report to the target access network device and / or the terminal device sending the first report to the source access network device. The first report sent by the terminal device to an access network device (e.g., the target access network device and / or the source access network device) may be transmitted to the access network device via another network device in the network. This is not limited in the present application. For example, after establishing a communication connection with the target access network device, the terminal device enters another cell and accesses a third-party access network device that manages this other cell. The third-party access network device is an access network device other than the target access network device and the source access network device. The terminal device may send the first report to the third-party access network device. After receiving the first report, the third-party access network device forwards the first report to the target device of the first report. Specifically, it may be indicated, but not limited to, that the target device of the first report is the target access network device and / or the source access network device by using the first report. The third-party access network device forwarding the first report to the target device may be the third-party access network device forwarding the first report to the target device through a communication interface between the third-party access network device and the target device, or the third-party access network device sending the first report to another network device and forwarding the first report to the target device through a relay of one or more network devices, which is not limited in the present application.

[0138] In this application, possible failures in the cell redirection process include the following: the terminal device successfully performs the cell redirection, but some parameter values ​​related to the cell redirection process may be on the verge of meeting the conditions for cell redirection failure but do not; thus, the terminal device determines that there is a potential risk of failure in the cell redirection process.

[0139] Optionally, when the cell redirection process meets a reporting condition, the terminal device records a first report.

[0140] In the implementation, the network device sends first indication information to the terminal device, where the first indication information indicates a reporting condition. Optionally, an RRC message sent by the network device to the terminal device includes the first indication information. As an example, but not by way of limitation, the RRC message may be an RRC release message.

[0141] The reporting conditions include, but are not limited to, one or more of the following conditions 1 to 4:

[0142] Condition 1: The operation period of the first timer is less than or equal to the first threshold and greater than or equal to the second threshold, and the operation period of the first timer is the period from when the terminal device receives an RRC release message from the source access network device to when the terminal device sends a random access preamble to the target access network device.

[0143] The first timer in condition 1 is used to determine whether the terminal device successfully selects a cell for redirection. The terminal device starts the first timer after receiving an RRC release message from the source access network device, and stops the first timer after the terminal device sends a random access preamble to the target access network device. If the operation period of the first timer is longer than a first threshold and the terminal device does not select a cell that can access the network, the terminal device considers the cell redirection to be unsuccessful, and the terminal device may attempt to re-establish a connection with the source cell or enter an idle state.

[0144] When the reporting condition for recording the first report by the terminal device includes condition 1, if the terminal device successfully selects a target cell for redirection when the operation period of the first timer is less than or equal to the first threshold but greater than or equal to the second threshold, the terminal device may consider that there is a risk of cell redirection failure due to the time for performing cell selection in the cell redirection process being long and the terminal device failing to select a cell. Thus, the terminal device records the first report to the network to notify the network of a potential failure case in the cell redirection process of the terminal device, so that the network performs network parameter optimization.

[0145] Optionally, the first report further indicates that the reporting conditions for triggering recording of the first report include condition 1.

[0146] For example, the first report may include indication information indicating that the reporting conditions for triggering the recording of the first report include condition 1. For example, the indication information may be identification information of condition 1, and notify the network that condition 1 triggers the recording of the sending of the first report by the terminal device, so that the network can determine, based on the first report, that the terminal device performs cell selection for a long time in the cell redirection process and there may be a potential failure case, and perform corresponding network parameter optimization.

[0147] Optionally, the first report further indicates an operating period of the first timer.

[0148] The terminal device notifies the network of the operation period of the first timer by using the first report, so that the network can determine based on the operation period of the first timer that the terminal device will perform cell selection in the cell redirection process for a long time and there may be a potential failure case, and then perform corresponding network parameter optimization.

[0149] Alternatively, the first report indicates both the reporting condition 1 and the operation period of the first timer, whereby, after obtaining the reporting condition including the condition 1 and the operation period of the first timer, the network determines that the terminal device performs cell selection in the cell redirection process for a long time and there may be a potential failure case, and performs corresponding network parameter optimization.

[0150] Condition 2: The operation period of the second timer is less than or equal to the third threshold and greater than or equal to the fourth threshold, and the operation period of the second timer is the period from when the terminal device receives an RRC release message from the source access network device to when the terminal device receives an RRC connection setup message from the target access network device.

[0151] The second timer in condition 2 is used to determine whether the terminal device successfully performs redirection to the target cell. The terminal device starts the second timer after receiving an RRC release message from the source access network device, and stops the second timer after receiving an RRC connection setup message from the target access network device. If the operation period of the second timer is longer than a third threshold and the terminal device has not yet received the RRC connection setup message, the terminal device may consider the cell redirection to the target cell to be unsuccessful, and the terminal device may select another cell to access the network.

[0152] When the reporting condition for recording the first report by the terminal device includes condition 2, if the terminal device successfully performs redirection to the target cell when the operating period of the second timer is less than or equal to the third threshold but greater than or equal to the fourth threshold, the terminal device may consider that the time for performing cell redirection to the target cell is long and there is a risk of potential failure in the cell redirection process for the cell redirection to the target cell. Thus, the terminal device records the first report to the network and sends the first report to the network to notify the network of the potential failure case in the cell redirection process of the terminal device, so that the network performs network parameter optimization.

[0153] Optionally, the first report further indicates that the reporting conditions for triggering the recording of the first report include condition 2 and / or the operation period of the second timer. For specific implementations, please refer to the description in condition 1. For brevity, the details will not be described again here.

[0154] Condition 3: The operation period of the third timer is less than or equal to the fifth threshold and greater than or equal to the sixth threshold, and the operation period of the third timer is the period from when the terminal device sends an RRC connection request message to the target access network device to when the terminal device receives an RRC connection setup message from the target access network device.

[0155] The third timer in condition 3 is used to determine whether the RRC connection between the terminal device and the network in the target cell is successfully established. The terminal device starts the third timer after sending an RRC connection request message to the target access network device, and stops the third timer after receiving an RRC connection setup message from the target access network device. If the operation period of the third timer is longer than the fifth threshold and the terminal device has not yet received an RRC connection setup message from the target access network device, and the terminal device considers that the RRC connection establishment will fail, the terminal device enters an idle state or attempts to re-establish a connection with the source cell.

[0156] The reporting condition for recording the first report by the terminal device may include Condition 3. If the terminal device successfully establishes an RRC connection with the network in the target cell when the operation period of the third timer is less than or equal to the fifth threshold but greater than or equal to the sixth threshold, the terminal device may consider that the time to establish the RRC connection in the target cell is long and there is a risk of a potential failure in the cell redirection process for redirection to the target cell. Therefore, the terminal device records the first report to the network and sends the first report to the network to notify the network of the potential failure case in the cell redirection process of the terminal device, so that the network performs network parameter optimization.

[0157] Optionally, the first report further indicates that the reporting conditions for triggering the recording of the first report include condition 3 and / or the operation period of the third timer. For specific implementation, please refer to the description in condition 1. For brevity, the details will not be described again here.

[0158] One or more of the first threshold, the second threshold, the third threshold, the fourth threshold, the fifth threshold, or the sixth threshold may be predefined in a protocol or may be configured for the terminal device by the source access network device. For example, the source access network device may notify the terminal device of one or more of the second threshold, the fourth threshold, or the sixth threshold by using an RRC release message.

[0159] The source access network device may directly indicate the value of the timer threshold, or may predefine multiple candidate values ​​for one threshold and identification information for each candidate value, and by indicating the identification information for one candidate value, the source access network device notifies the terminal device that the value of the timer threshold is the candidate value corresponding to the identification information.

[0160] For example, for one timer, four candidate values ​​of the timer threshold and an identification number of each candidate value may be predefined or preconfigured in a protocol by a network device. For example, the four candidate values ​​may be T0, T1, T2, and T3, respectively, and the unit of the candidate values ​​may be microseconds, milliseconds, or seconds. The identification number of T0 is 0, the identification number of T1 is 1, the identification number of T2 is 2, and the identification number of T3 is 3. The source access network device may perform the indication by using an RRC message. For example, the RRC message may be an RRC release message. The RRC release message may include an indication having a length of 2 bits, and the indication indicates an identification number of one of the four candidate values. For example, the indication indicates that the identification number is 2. In this case, after receiving the RRC release message, the terminal device may determine that the timer threshold is candidate value T2 corresponding to identification number 2.

[0161] In implementation, the source access network device may indicate one or more of the following first coefficient, second coefficient, or third coefficient and notify the terminal device of the corresponding threshold value.

[0162] Optionally, the second threshold is a product of the first threshold and the first coefficient, and / or the fourth threshold is a product of the third threshold and the second coefficient, and / or the sixth threshold is a product of the fifth threshold and the third coefficient, and the first coefficient, the second coefficient, and the third coefficient are less than 1.

[0163] The first threshold, the third threshold, and the fifth threshold may be notified to the terminal device by the source access network device. If the reporting condition includes condition 1, the source access network device may notify the terminal device of the first coefficient, and the terminal device may determine the value of the second threshold based on the first threshold and the first coefficient. Similarly, if the reporting condition includes condition 2, the source access network device may notify the terminal device of the second coefficient. If the reporting condition includes condition 3, the source access network device may notify the terminal device of the third coefficient.

[0164] For example, the coefficient corresponding to the threshold may be a percentage. For example, the reporting condition includes condition 1. In this case, the source access network device sends an RRC message to the terminal device. For example, the RRC message may be an RRC release message, and the RRC release message indicates that the value of the first coefficient is 90%. In this case, the terminal device may obtain the value of the first coefficient based on the RRC release message and determine the second threshold based on the first coefficient and the first threshold. That is, the second threshold is 90% of the first threshold. The source access network device may similarly notify the terminal device of coefficients corresponding to the fourth threshold and the sixth threshold. However, the present application is not limited thereto. The coefficients may be expressed as decimals or fractions.

[0165] Condition 4: The terminal device fails to perform cell redirection on a first frequency and successfully performs cell redirection on a frequency other than the first frequency, the first frequency is a candidate frequency configured for the terminal device by the source access network device and used for cell redirection, and the frequency of the target cell is a frequency other than the first frequency.

[0166] The reporting condition for recording the first report by the terminal device may include Condition 4. If the terminal device fails to perform cell redirection on a candidate frequency configured for the terminal device by the source access network device and successfully performs cell redirection on a frequency other than the first frequency, the terminal device needs to record a first report, and the terminal device may send the first report to the network to notify the network of a potential risk of failure in the cell redirection process of the terminal device.

[0167] In this implementation, both the first frequency and the frequency of the target cell are candidate frequencies configured by the source access network device for the terminal device to perform cell redirection. In other words, the source access network device configures multiple candidate frequencies for the terminal device, and the multiple candidate frequencies include the first frequency and the frequency of the target cell. After failing to perform cell redirection on the first frequency, the terminal device performs cell redirection on another candidate frequency (i.e., the frequency of the target cell) and successfully performs redirection to the target cell.

[0168] In another implementation, the first frequency is a candidate frequency configured by the source access network device for the terminal device to perform cell redirection. The frequency of the target cell may be a frequency other than the candidate frequency configured for the terminal device by the source access network device. In other words, the candidate frequencies configured for the terminal device by the source access network device include the first frequency but do not include the frequency of the target cell. After failing to perform cell redirection on the candidate frequency, the terminal device performs cell redirection on a frequency other than the candidate frequency and successfully performs redirection to the target cell.

[0169] Optionally, the first report further indicates that reporting conditions for triggering recording of the first report include condition 4 and / or the first frequency.

[0170] For example, the first report may include indication information indicating that the reporting conditions include condition 4, and may notify the network that the cell redirection failure of the terminal device occurs on a candidate frequency configured by the network, thereby causing the network to perform network parameter optimization.

[0171] In another example, the first report may include indication information indicating that the reporting conditions include a first frequency and may notify the network of the first frequency on which the terminal device fails to perform cell redirection, thereby enabling the network to obtain information regarding the frequency on which the terminal device fails to perform cell redirection and perform targeted network parameter optimization.

[0172] Optionally, the first report further indicates one or more of: source cell identification information, target cell identification information, cell measurement information, redirection frequency information, target cell frequency information, indication information indicating whether a suitable cell exists, indication information indicating whether an acceptable cell exists, an operation period of the first timer, an operation period of the second timer, an operation period of the third timer, or an operation period of the fourth timer.

[0173] The cell measurement information includes one or more of measurement information of a source cell, measurement information of a target cell, measurement information of a neighboring cell of the source cell, or measurement information of a neighboring cell of the target cell.

[0174] For example, the cell measurement information may be a measurement result of the cell. Optionally, the cell measurement information further includes measurement information other than that of the source cell and the target cell. For example, the terminal device may perform cell signal quality measurements on the candidate frequency, and the cell measurement information may include a measurement result of the cell obtained by the terminal device through the measurement. In another example, the terminal device fails to perform cell re-establishment on the first frequency, and the cell measurement information may include a measurement result obtained by the terminal device through measurement of the cell on the first frequency.

[0175] The operation period of the fourth timer is the period from when the terminal device receives an RRC release message from the source access network device to when the terminal device successfully establishes a service channel with the target access network device, or the period from when the terminal device receives an RRC release message from the source access network device to when the terminal device successfully communicates service data packets with the target access network device. The terminal device starts the fourth timer after receiving the RRC release message from the source access network device, and the terminal device performs redirection from the source cell to the target cell. The terminal device stops the fourth timer after successfully establishing a service channel with the target access network device, or the terminal device successfully communicates service data packets with the target access network device. The obtained execution period of the fourth timer may be referred to as a service interruption period.

[0176] For example, the source access network device indicates to the terminal device to fall back to a cell in a 4G network through cell redirection by using an RRC release message to complete voice service data transmission. After receiving the RRC release message, the terminal device starts a fourth timer and performs cell redirection. The terminal device successfully performs redirection to the target cell. The target cell is a cell managed by an eNodeB in the 4G network, in other words, the target access network device is the eNodeB in the 4G network. The terminal device initiates a tracking area update (TAU) process to the eNodeB. An LTE network coverage area is divided into multiple tracking areas to determine the location of the terminal device, and a tracking area is the basic unit for location updating and paging of the terminal device in the LTE network. After the terminal device and the eNodeB complete the TAU process, the terminal device establishes a VoLTE service channel with the eNodeB. After the VoLTE service channel is successfully established, the terminal device stops the fourth timer. The operation period of the fourth timer is a voice service interruption period, and the first report sent by the terminal device may include the operation period of the fourth timer, thereby allowing the network to obtain the voice service interruption period in a specific cell redirection process of the terminal device and perform targeted network parameter optimization.

[0177] Optionally, the terminal device sending the first report includes: the terminal device sending the first report to the source access network device, where the first report includes identification information of the source cell; alternatively, the terminal device sending the first report to the target access network device; Optionally, as a receiver of the first report, the source access network device or the target access network device may receive the first report via another network device. In other words, the terminal device sends the first report to another network device, and then the other network device forwards the first report to the source access network device or the target access network device. In addition, the source access network device or the target access network device may further send the received first report to the other network device. It may be understood that for the source access network device, the target access network device is the other network device, and for the target access network device, the source access network device is the other network device.

[0178] 4 is a schematic flowchart of a communication method 400 according to an embodiment of the present application. As shown in FIG. 4, a terminal device sends a first report to a target access network device, the target access network device forwards the first report to a source access network device, and the source access network device adjusts network configuration parameters based on the first report.

[0179] S401: A terminal device sends a first report to a target access network device.

[0180] In response, the target access network device receives a first report from the terminal device.

[0181] In the embodiment shown in FIG. 4, the first report is a report sent by the terminal device to the source access network device. Because the access network device currently connected to the terminal device is the target access network device, the terminal device may forward the first report to the source access network device via the target access network device. For example, the target access network device encapsulates the first report in a container and sends the container to the source access network device. The first report includes source cell identification information, and the source cell identification information indicates that the first report is a report to be sent to the access network device of the source cell (i.e., the source access network device). The target access network device may determine that the first report is a report to be sent to the source access network device based on the source cell identification information in the first report.

[0182] For example, when the reporting condition includes one or more of the above condition 1, condition 2, or condition 4, and the process of performing cell redirection by the terminal device satisfies the reporting condition, a potential failure case in the cell redirection process may be caused by an improper configuration of the candidate frequency of the source cell. In this case, the terminal device records a first report and sends the first report to the source access network device, so that the source access network device can refer to the first report to determine whether to optimize the candidate frequency and reduce the probability of cell redirection failure of the terminal device in the network. The first report includes identification information of the source cell. The target access network device can determine that the first report is a report to be sent to the source access network device based on the identification information of the source cell in the first report. The target access network device transparently transmits the first report to the source access network device. In other words, after determining that the target device of the first report is the source access network device, the target access network device does not analyze the content of the first report and forwards the first report to the source access network device.

[0183] In this example, the terminal device determines that the first report is the first report to be sent to the source access network device based on the reporting condition for triggering the terminal device to record the first report. However, the present application is not limited to this. The terminal device may not perform such a determination. When the cell redirection process satisfies the reporting condition, the terminal device records the first report and sends the first report to the source access network device. The source access network device analyzes the cause of a potential risk of failure in the cell redirection process of the terminal device (see the related description in S403).

[0184] S402: The target access network device sends a first report to the source access network device.

[0185] In response, the source access network device receives a first report from the target access network device.

[0186] S403: The source access network device adjusts network configuration parameters based on the first report.

[0187] Based on the first report, the source access network device may determine that the terminal device successfully performs cell redirection from the source cell but there is a potential failure case. The source access network device may adjust a network parameter configuration based on the first report. Optionally, multiple terminal devices perform cell redirection from the source cell to another cell. When the process of performing cell redirection by the terminal device satisfies a reporting condition, the terminal device records the first report and sends the first report to the source access network device. The source access network device collects the first reports. When the source access network device receives first reports sent by a certain amount (e.g., a preset amount) of terminal devices and indicating that there is a potential risk of failure in the cell redirection process, the source access network device may perform network parameter optimization based on the first reports of the multiple terminal devices to reduce the probability of redirection failure. For example, the source access network device optimizes candidate frequency configurations based on the first reports from the multiple terminal devices. For example, the first reports sent by the multiple terminal devices include frequency information of cells successfully accessed by the corresponding terminal devices by performing cell redirection from the source cell. The source access network device configures candidate frequencies for the terminal devices in the source cell to perform cell redirection, referring to the frequencies indicated by the first reports from the multiple terminal devices and on which the terminal devices successfully complete cell redirection. However, the present application is not limited thereto. The source access network device may further adjust network parameter configurations based on other information in the first reports.

[0188] As described above, in this implementation, the terminal device does not determine the cause of a potential failure in the cell redirection process. When the cell redirection process satisfies the reporting condition, the terminal device records a first report and sends the first report to the source access network device, which analyzes the cause of the potential failure in the cell redirection process of the terminal device. If the source access network device analyzes that the cause of the potential failure in the cell redirection process of the terminal device is an improper configuration of parameters of the source access network device, it may perform network parameter optimization with reference to the first report. If the source access network device analyzes that the cause of the potential failure in the cell redirection process of the terminal device is an improper configuration of parameters of the target access network device, it may notify the target access network device. In this implementation, when the terminal device determines that there is a risk of a potential failure in the cell redirection process, it sends a first report to the source access network device indicating to the terminal device to perform cell redirection. The first report may not include information related to cell redirection configured for the terminal device by the source access network device (such as candidate frequency information). The source access network device analyzes the cause of the potential risk of failure based on the first report with reference to configuration information related to cell redirection already provided to the terminal device. This improves the accuracy of network parameter optimization while reducing the information overhead of the first report.

[0189] Optionally, the source access network device sends a first message to the target access network device, where the first message includes information related to the target access network device in the first report.

[0190] After receiving the first report, the source access network device analyzes information in the first report to determine that the problem of the potential risk of failure in the cell redirection process of the terminal device is related to the target access network device, in this case, the source access network device forwards the information related to the target access network device in the first report to the target access network device.

[0191] For example, the first report indicates that the cell redirection process of the terminal device satisfies the reporting condition 1 and the reporting condition 2. This indicates that the terminal device successfully performs redirection to the target cell, but the time between when the terminal device receives the RRC release message from the source access network device and when the terminal device sends a random access preamble to the target access network device is long (in other words, the operation period of the first timer is less than or equal to the first threshold and greater than or equal to the second threshold), and the time between when the terminal device receives the RRC release message from the source access network device and when the terminal device receives the RRC connection setup message from the target access network device is long (in other words, the operation period of the second timer is less than or equal to the third threshold and greater than or equal to the fourth threshold), indicating a potential risk of failure in the cell redirection process. Based on the fact that the cell redirection process of the terminal device satisfies both the reporting condition 1 and the reporting condition 2, the source access network device determines that the cause of the potential risk of failure in the cell redirection process may be related to both the configuration of the source access network device and the configuration of the target access network device. For example, the potential risk of failure in the cell redirection process may be related to the resource configuration (preamble and time-frequency resource) of the random access procedure of the target cell. The source access network device may send a first message to the target access network device, and the first message may indicate that the cell redirection process of the terminal device satisfies reporting condition 1 and reporting condition 2. Optionally, the first message may further include other information in the first report, such as the operation period of the first timer and / or the second timer, thereby causing the target access network device to perform network parameter optimization with reference to the first message. However, the present application is not limited thereto.If the source access network device determines, after analyzing the first report, that the risk of a potential failure in the cell redirection process of the terminal device does not concern the target access network device, it may not send the first message to the target access network device.

[0192] FIG. 5 is a schematic flowchart of a communication method 500 according to an embodiment of the present application.

[0193] S501: A terminal device sends a first report to a target access network device.

[0194] In response, the target access network device receives a first report from the terminal device.

[0195] In the embodiment shown in FIG. 5 , the first report is a report sent by the terminal device to the target access network device; in other words, the target device of the first report is the target access network device. The terminal device sending the first report to the target access network device may be the terminal device sending the first report when establishing a wireless communication connection with the target access network device, and the target access network device receiving the first report over a radio channel. Alternatively, the terminal device sending the first report to the target access network device may be the terminal device moving from the target cell to another cell, the terminal device sending the first report to a third-party access network device with which the communication connection is established, and the third-party access network device forwarding the first report to the target access network device. This is not a limitation in the present application.

[0196] For example, when the reporting condition includes the above condition 3 and the process of performing cell redirection by the terminal device satisfies the reporting condition 3, a potential risk of failure in the cell redirection process in which the terminal device performs redirection to the target cell may be caused by an improper configuration of the network access of the target cell (e.g., an improper configuration of the random access channel preamble). In this case, the terminal device may record a first report and send the first report to the target access network device, whereby the target access network device may refer to the first report to determine whether to optimize network configuration parameters and reduce the probability of cell redirection failure of the terminal device in the network.

[0197] S502: The target access network device adjusts network configuration parameters based on the first report.

[0198] The target access network device may determine, based on the first report, that the terminal device successfully performs cell redirection to the target cell, but that a potential failure case exists. The target access network device may adjust network configuration parameters based on the first report. When the cell redirection process of the terminal device performing cell redirection to the target cell satisfies a reporting condition, the terminal device records the first report and sends the first report to the target access network device. The target access network device collects the first reports. If the target access network device receives a certain amount (e.g., a preset amount) of first reports sent by the terminal device and indicating that a potential failure risk exists in the cell redirection process, the target access network device may adjust network access parameter configurations, such as a random access channel (RACH) configuration. However, the present application is not limited thereto. Optionally, the risk of potential failure in the cell redirection process of the terminal device may be caused by improper configuration of parameters of the target access network (i.e., the network in which the target access network device is located) or may be caused by improper configuration of parameters of the source access network (i.e., the network in which the source access network device is located). The first report may be sent to both the target access network device and the source access network device. After receiving the first report, the target access network device may perform network parameter optimization with reference to the first report and forward the first report to the source access network device. The source access network device may receive the first report and also perform network parameter optimization with reference to the first report.Alternatively, after receiving the first report, the target access network device may send to the source access network device information contained in the first report and used by the source access network device to optimize network parameters.

[0199] In this example, the terminal device determines whether the first report should be sent to the source access network device or the target access network device, or whether both the source access network device and the target access network device require the first report, based on the reporting condition for triggering the terminal device to record the first report. However, the application is not limited thereto. The terminal device may not perform such a determination. When the reporting condition is met, the terminal device records the first report and sends the first report to the target access network device. The first report includes identification information of the source cell. Based on the first report, the target access network device determines whether the first report or part of the information in the first report needs to be forwarded to the source access network device, thereby causing the source access network device to perform network parameter optimization.

[0200] For example, the first report may include information indicating that the reporting conditions include condition 1 and condition 3, an operation period of the first timer, an operation period of the third timer, cell measurement information, and frequency information of the target cell. After receiving the first report, the target access network device may determine that a case of misconfiguration of parameters of the target access network may exist based on the reporting conditions including condition 3, and may perform network parameter configuration by referring to the first report (e.g., the operation period of the third timer and the measurement result of the target cell in the cell measurement information). The target access network device may determine that a case of misconfiguration of parameters of the source access network may exist based on the reporting conditions. The target access network device may send an interface message to the source access network device to indicate that there is a potential risk of failure in the cell redirection process of the terminal device. The interface message may include the operation period of the first timer, the cell measurement information, and the frequency information of the target cell, so that the source access network device can determine whether to perform network parameter optimization by referring to the interface message.

[0201] Optionally, the first report further includes second indication information, where the second indication information indicates whether the cell redirection is triggered by a service or by a measurement result.

[0202] As an example, but not by way of limitation, cell redirection may be triggered by a voice service. For example, if the network in which the source access network device is located does not support VoNR service or the quality of the VoNR service is degraded, the source access network device may indicate to the terminal device to perform cell redirection. If the terminal device records a first report due to a reporting condition being satisfied, and the first report includes second indication information, the second indication information indicates that cell redirection is triggered by a voice service. Alternatively, the source access network device may indicate to the terminal device to perform cell redirection based on cell measurement results reported by the terminal device. When the terminal device sends the first report, the second indication information in the first report indicates that cell redirection is triggered by cell measurement results. The first report includes the second indication information, thereby allowing a network device (e.g., the source access network device and / or the target access network device) that obtains the first report to determine the cause of triggering the terminal device to perform cell redirection. For example, when the cell redirection is triggered by a voice service, the network device may determine based on the second indication information that the cell redirection is not caused by degradation of the signal quality of the serving cell or the signal quality of the neighboring cell being better than that of the serving cell, and may not adjust network parameters related to the measurement configuration with reference to the first report, but may adjust only parameters related to the cell redirection configuration, which may improve the accuracy of network parameter optimization and reduce unnecessary or erroneous network parameter optimization.

[0203] The above describes, by using an example, the solution provided in the present application. In this solution, when there is a potential risk of failure in a redirection process in which a terminal device performs redirection from a source cell to a target cell, the terminal device may send a first report to a network device to notify the network device of the potential risk of failure in the cell redirection process of the terminal device. The network device may then refer to the first report to perform network parameter optimization to improve the performance of mobility management performed by the network device for the terminal device. Currently, the handover failure report of the terminal device may also be used as a reference for the network device to perform network parameter optimization. However, the cell handover performed by the terminal device may be triggered by signal coverage quality or service data, and different trigger causes of cell handover failure result in different directions of network parameter optimization performed by the network device. Therefore, there is a problem that the accuracy of network parameter optimization performed based on the handover failure report is low. In an embodiment of the present application, when the terminal device notifies the network device of a cell handover failure, the terminal device needs to notify the network device of the cause that triggers the terminal device to perform cell handover, so that the network device can more accurately perform network parameter optimization. The following description is provided with reference to FIG. 6.

[0204] FIG. 6 is another schematic flowchart of a communication method according to an embodiment of the present application.

[0205] S601: A terminal device fails to perform handover to a first cell.

[0206] For example, the terminal device receives a handover command in a source cell, and the handover command indicates to the terminal device to perform a handover to a first cell. The terminal device performs the cell handover but fails to perform the handover to the first cell. The terminal device attempts to establish a communication connection with another cell.

[0207] S602: The terminal device establishes a communication connection with a second cell.

[0208] In implementation, the RAT of the second cell is the same as the RAT of the first cell.

[0209] For example, a terminal device may perform an inter-RAT network (or inter-system) cell handover, and the source access network device may indicate to the terminal device to perform a handover to a first cell whose RAT is different from that of the source cell. For example, the source cell may be a cell in a 5G network using NR access technology, and the first cell may be a cell in a 4G network using E-UTRA technology, or vice versa. This is not limited in the present application. If the terminal device fails to perform the handover to the first cell, it may continue to perform cell selection on candidate frequencies of the network in which the first cell is located to access another cell whose RAT is the same as that of the first cell. The candidate frequencies in each network are predefined in the protocol. For example, both the candidate frequencies of a cell in a 4G network and the candidate frequencies of a cell in a 5G network are predefined in the protocol. If the terminal device successfully selects a suitable cell (e.g., a cell that meets the signal quality requirements), in other words, a second cell whose RAT is the same as that of the first cell, the terminal device establishes a communication connection in the second cell with an access network device that manages the second cell. Therefore, the RAT of the second cell is the same as that of the first cell.

[0210] In another implementation, the RAT of the second cell is different from the RAT of the first cell.

[0211] In another example, the source access network device indicates to the terminal device to perform a handover to a first cell whose RAT is different from that of the source cell. If the terminal device fails to perform the handover to the first cell, it continues to perform cell selection for the frequency of the network in which the first cell is located, but does not select a suitable cell whose RAT is the same as that of the first cell. The terminal device re-establishes a communication connection with the source cell. In this example, the second cell is the source cell of the terminal device, and the RAT of the second cell is different from that of the first cell. However, the present application is not limited thereto. Alternatively, the second cell may be another cell whose RAT is different from that of the first cell.

[0212] S603: The terminal device sends a second report to a first access network device that manages a second cell, the second report indicating that the terminal device fails to perform handover to the first cell, the second report including fourth indication information, the fourth indication information indicating that the handover of the terminal device to the first cell is triggered by a voice service or a measurement result.

[0213] In response, the first access network device receives a second report from the terminal device and determines, based on the fourth indication information in the second report, a trigger cause for triggering the terminal device to perform a handover to the first cell.

[0214] By way of example and not limitation, the second report includes an RLF report or a connection setup failure report.

[0215] For example, if the fourth indication information indicates that the handover of the terminal device to the first cell is triggered by signal coverage quality, the first access network device may detect that the handover failure may be caused by an improper configuration of measurement parameters and / or measurement-based handover parameters of the source cell, for example, an improper configuration of parameters such as a threshold for measurement reports of the source cell. However, the present application is not limited thereto. The first access network device may send a second message to the source access network device, where the second message indicates to the terminal device to perform a handover from the source cell to the first cell, and the second message may include the second report or part of the information in the second report. The source access network device may perform network parameter optimization by referring to the second message. For example, the network parameter optimization may include, but is not limited to, adjusting measurement configuration parameters and / or measurement-based handover parameters. Optionally, the failure of the terminal device to perform handover to the first cell may alternatively be caused by an improper configuration of network parameters of the first cell, for example, parameters related to a random access procedure. The first network device may send the second report or part of the information in the second report to an access network device managing the first cell, whereby the access network device managing the first cell uses the second report or part of the information in the second report as reference information for network parameter optimization.

[0216] In another example, if the fourth indication information indicates that the handover of the terminal device to the first cell is triggered by a voice service, the first access network device may determine that the handover of the terminal device to the first cell is triggered by the voice service rather than the signal coverage quality. Thus, the first access network device may determine that the failure of the terminal device to perform the handover to the first cell is not caused by an improper configuration of the measurement parameters and / or measurement-based handover parameters of the source cell. The first access network device may not send the second report to the source access network device. Optionally, the first access network device sends the second report or part of the information in the second report to the access network device managing the first cell.

[0217] Optionally, the second report further includes fifth indication information, where the fifth indication information indicates whether the terminal device selects a cell that meets a condition, or indicates whether the terminal device selects a suitable cell.

[0218] For example, the terminal device does not select a cell whose RAT is the same as that of the first cell and re-establishes a connection with the source cell; in other words, the second cell is the source cell before the terminal device performs cell handover. The second report includes fifth indication information, which indicates that a cell satisfying the condition is not selected and notifies the network that the terminal device does not select a cell whose RAT is the same as that of the first cell. This provides detailed information related to the cell handover process for the network, provides a reference for the network device during network parameter optimization, and improves the effectiveness of mobility management performed by the network device for the terminal device. For example, the fifth indication information may be indicated as noSuitableCellFound. When noSuitableCellFound is "True," it indicates that the terminal device does not select a cell that satisfies the condition of a suitable cell.

[0219] In another example, after failing to perform handover to the first cell, the terminal device selects a cell whose RAT is the same as that of the first cell, i.e., the second cell. The second report includes fifth indication information, where the fifth indication information indicates that a cell that satisfies a condition is selected, and notifies the network that after failing to perform handover to the first cell, the terminal device selects a cell whose RAT is the same as that of the first cell. This provides detailed information related to the cell handover process for the network, provides a reference for a network device (e.g., a source access network device and / or an access network device managing the first cell) during network parameter optimization, and can improve the effectiveness of mobility management performed by the network device for the terminal device.

[0220] The above describes a solution in which, after a cell handover of the terminal device fails, the terminal device sends a second report to the connected access network device when the terminal device re-establishes a communication connection with the network, where the second report includes indication information indicating a trigger cause for triggering the cell handover, so that the network can more accurately adjust inappropriate parameter configurations based on the handover trigger cause, reduce unnecessary or erroneous network parameter adjustments, and improve the effectiveness of mobility management performed by the network device for the terminal device.

[0221] When the network device indicates to the terminal device to perform a handover to a cell of an inter-RAT network (e.g., a first cell) due to the voice service of the terminal device, if the terminal device fails to perform the cell handover, the terminal device performs cell selection on the candidate frequencies of the network of the RAT to which the first cell belongs based on the current handover mechanism, and selects a cell that meets the conditions for access. If the voice service is a normal voice service, the condition to be met is the condition of a suitable cell. If the voice service is an emergency voice service, the condition to be met is the condition of a suitable cell and an acceptable cell. In this case, the terminal device first attempts to select a suitable cell, and if a suitable cell is not selected, the terminal device selects an acceptable cell. In an embodiment of the present application, the cell handover of the terminal device is triggered by the voice service. If the handover fails, a cell that meets the conditions is not selected during cell selection, and the terminal device may re-establish a connection with the access network device of the source cell. A description is provided below with reference to FIG. 7.

[0222] FIG. 7 is another schematic flowchart of a communication method according to an embodiment of the present application.

[0223] S701: A second access network device sends a handover command to a terminal device, the handover command indicating a voice service to trigger the terminal device to perform a handover to a first cell.

[0224] For example, the serving cell (i.e., source cell) of the terminal device is an NR cell, and the 5G network where the NR cell is located does not support VoNR policy and cannot provide voice service to the terminal device. When the terminal device has voice service data to send or receive, the second access network device managing the source cell sends a handover command to the terminal device, where the handover command indicates a voice service to trigger the terminal device to perform handover to a first cell in the 4G network. In other words, the second access network device indicates to the terminal device to fall back to a cell in the 4G network and perform voice service data transmission by using a cell handover process according to the handover command. After receiving the handover command, the terminal device performs a cell handover process for handover to the first cell.

[0225] Optionally, the RAT of the first cell is different from the RAT of the source cell.

[0226] S702: The terminal device fails to perform handover to the first cell.

[0227] The first cell is a cell managed by a third access network device, and the terminal device performs a random access procedure in the first cell to attempt to perform a handover to the first cell, but the terminal device fails to perform the handover to the first cell.

[0228] S703: The terminal device performs cell selection, but does not select a cell that meets the conditions.

[0229] After failing to perform handover to the first cell, the terminal device performs cell selection to access a cell whose RAT is the same as the RAT of the first cell, but the terminal device does not select a cell that meets the conditions.

[0230] If the voice service is a normal voice service, the condition to be met is the condition of a suitable cell. If the voice service is an emergency voice service, the condition to be met is the condition of a suitable cell and an acceptable cell. For example, in an emergency voice service scenario, the terminal device first attempts to select a suitable cell. If a suitable cell is not selected, the terminal device may select an acceptable cell.

[0231] For example, the terminal device selects a cell that satisfies a condition on the E-UTRA frequency on which the first cell is located or another E-UTRA frequency, and accesses the cell whose RAT is the same as the RAT of the first cell. For example, the terminal device detects a synchronization signal on one or more E-UTRA frequencies, and performs signal quality measurement when detecting the synchronization signal of the cell. If the measurement result of the cell satisfies the access condition, the terminal device performs a random access procedure in the cell.

[0232] If the terminal device does not select a cell that satisfies the condition on one or more E-UTRA frequencies, the terminal device performs S704. For example, after the terminal device fails to perform handover to a target cell, performing cell selection on a candidate frequency of a cell whose RAT is the same as the RAT of the target cell may be predefined in a protocol or preconfigured by the network. If the terminal device does not select a cell that satisfies the condition within a predefined period after failing to perform handover to the first cell, the terminal device determines that a cell that satisfies the condition is not selected, or the terminal device performs S704 if it does not select a cell that satisfies the condition on a candidate frequency of a cell whose RAT is the same as the RAT of the target cell.

[0233] S704: The terminal device performs an RRC re-establishment process with the source cell.

[0234] The handover of the terminal device to the first cell is triggered by a voice service, not coverage, indicating that the signal quality of the source cell is degraded or that the signal quality of the first cell is better than that of the source cell and the signal quality of the source cell nevertheless meets the communication requirements, and therefore the terminal device may re-establish an RRC connection with the source cell to resume communication with the network.

[0235] S705: The terminal device sends a third report to the second access network device, where the third report indicates that the terminal device fails to perform handover to the first cell.

[0236] The second access network device is a source access network device that manages the source cell. In response, the second access network device receives a third report from the terminal device.

[0237] Optionally, the third report may include fifth indication information in the embodiment shown in FIG. 6, where the fifth indication information indicates that the terminal device does not select a cell that meets the conditions. In a normal voice service scenario, if the terminal device does not select a suitable cell, the fifth indication information may indicate that the terminal does not select a suitable cell in the normal voice service scenario. Alternatively, in an emergency voice service scenario, if the terminal device does not select a suitable cell, the terminal device selects an acceptable cell. The fifth indication information may also indicate that the terminal device does not select a suitable cell or does not select an acceptable cell in an emergency voice service fallback scenario.

[0238] For example, the fifth indication information may be indicated as noSuitableCellFound, which, when "true", indicates that the terminal device does not select a cell that satisfies the conditions.

[0239] Optionally, the third report may further include fourth indication information in the embodiment shown in Figure 6, where the fourth indication information indicates that the cell handover is triggered by the voice service. After receiving the third report, the second access network device may determine based on the fifth indication information and the fourth indication information that the terminal device does not select a satisfying cell on the E-UTRA frequency (i.e., LTE frequency) for a long time due to the cell handover being triggered by the voice service, so that the second access network device can perform network parameter optimization and adjust network configuration parameters by referring to the third report.

[0240] In another example, the third report may not include the fourth indication information. Because the cell handover of the terminal device is indicated by the second access network device (i.e., the source access network device), after the terminal device re-accesses the source cell, the second access network device may determine, based on the identification information of the terminal device, that the cell handover of the terminal device is triggered by the voice service, and may determine, based on the third report, that the terminal device fails to perform the cell handover. The second access network device may perform network parameter optimization by referring to the third report, for example, by adjusting the parameter configuration of the handover triggered by the voice service. This is not limited in the present application.

[0241] According to the solution provided in the embodiment shown in Figure 7, if a terminal device fails to perform cell handover and does not select a cell that meets the conditions during cell selection, the terminal device may re-establish a connection with the access network device of the source cell. Since the cell handover is not caused by a degradation in the signal quality of the source access network device in the source cell, the signal quality of the source access network device in the source cell can meet the communication requirements of the terminal device. This can reduce the cases where the terminal device performs cell selection on E-UTRA frequencies for a long time or loses communication connection with the network due to voice service fallback.

[0242] In a possible implementation, the terminal device performs cell selection and, if it selects an E-UTRA cell that satisfies the conditions, initiates a connection setup procedure in the cell. Optionally, the terminal device stores one piece of indication information in the third report, where the indication information indicates whether the E-UTRA cell accessed by the terminal device is an acceptable cell, or the indication information indicates that the fallback voice service type is a normal voice service or an emergency voice service. In an emergency voice service fallback scenario, if the terminal device does not select an acceptable cell but selects an appropriate cell, the third report further stores one piece of indication information. The indication information may indicate that the terminal device does not select an appropriate cell or an appropriate E-UTRA cell (the E-UTRA cell may also be called a 4G cell) in the emergency voice service fallback scenario.

[0243] When the network device indicates to the terminal device to perform cell redirection due to the voice service of the terminal device, if the terminal device fails to perform cell redirection, the terminal device may perform cell selection to select a cell that meets the conditions for access, or if the terminal device does not select a cell that meets the conditions, it may re-establish a connection with the access network device of the source cell. Hereinafter, a communication method 1100 provided in an embodiment of the present application will be described with reference to Figure 7A.

[0244] S1101: A second access network device sends an RRC release message to a terminal device, The RRC release message indicates a voice service to trigger the terminal device to perform redirection.

[0245] In response, the terminal device receives an RRC release message from the second access network device to determine that the redirection is triggered by the voice service. The RRC release message may include a redirection frequency for performing the redirection.

[0246] 1102: The terminal device performs redirection but does not select a cell that satisfies the conditions on the redirection frequency.

[0247] The terminal device records a fifth report, which indicates that the terminal device fails to perform the redirection.

[0248] In implementation, the fifth report further includes a redirection frequency indicating the redirection process.

[0249] S1103: The terminal device performs cell selection on the E-UTRA frequency, and does not select a cell that meets the conditions nonetheless.

[0250] When the terminal device performs redirection and does not select a cell that satisfies the conditions on the redirection frequency, the terminal device performs cell selection on an E-UTRA frequency other than the redirection frequency, but does not select a cell that satisfies the conditions.

[0251] For S1103 in the embodiment shown in Figure 7A, please refer to the above description of S703 in the embodiment shown in Figure 7. For the sake of brevity, the details will not be described again here.

[0252] S1104: The terminal device performs cell selection on a frequency other than the E-UTRA frequency and establishes an RRC connection.

[0253] In S1103, the terminal device performs cell selection on an E-UTRA frequency other than the redirection frequency and still does not select a cell that meets the conditions. In this case, the terminal device performs cell selection again in S1104. This time, cell selection may be performed on a frequency other than the E-UTRA frequency, and the terminal device performs cell selection on a frequency at which a suitable cell can be selected. For example, the terminal device may perform cell selection on an NR frequency, select an NR cell that can be used as a suitable cell, and establish an RRC connection with the NR cell.

[0254] S1105: The terminal device sends a fifth report to the second access network device, where the fifth report indicates that the terminal device fails to perform the redirection.

[0255] In an optional implementation, the fifth report may include fifth indication information in the embodiment shown in FIG. 7, where the fifth indication information indicates that the terminal device does not select a cell that meets the conditions.

[0256] In an optional implementation, the fifth report may include indication information indicating that the redirection is triggered by a voice service. After receiving the fifth report, the second access network device may determine that the terminal device does not select a cell that satisfies the condition on the redirection frequency and an E-UTRA frequency other than the redirection frequency for a long period of time due to the redirection being triggered by the voice service, so that the second access network device can perform network parameter optimization and adjust network configuration parameters by referring to the fifth report.

[0257] When the network device indicates to the terminal device to perform a handover to a first cell of the RAT network due to the voice service of the terminal device, if the terminal device successfully performs the handover to the first cell but there is a risk of potential failure, the terminal device may record a fourth report, where the fourth report may be a successful handover report (SHR) or a random access report. The terminal device records relevant information about potential failure issues in the successful handover process. In an embodiment of the present application, the fourth report includes a service interruption period, so that the access network devices (e.g., the source access network device and / or the target access network device) involved in the handover process can perform network configuration parameter optimization with reference to the service interruption period and the context of the terminal device in the fourth report to reduce the probability of handover failure of the terminal device. Hereinafter, a communication method 1200 provided in an embodiment of the present application will be described with reference to FIG. 7B.

[0258] S1201: A source access network device sends a handover command to a terminal device, the handover command indicating a voice service to trigger the terminal device to perform handover to a first cell.

[0259] For details, please refer to the above description in S701. The details will not be described again. Optionally, the RAT of the first cell is different from the RAT of the source cell. After receiving the handover command, the terminal device starts a fifth timer and performs cell handover.

[0260] Optionally, the source access network device sends first configuration information to the terminal device, where the first configuration information is used to configure a trigger condition for triggering recording of the fourth report. The trigger condition includes: The operation period of the timer is equal to or greater than a seventh threshold value; the ratio of the timer's operating period to the timer's maximum execution period is equal to or greater than an eighth threshold; The amount of random access time during which the terminal device attempts to access the target access network device is equal to or greater than a ninth threshold; and The interruption time of data transmission between the terminal device and the access network device (including the source access network device and / or the target access network device) may include one or more of being equal to or greater than a tenth threshold.

[0261] The first configuration information may include one or more of a seventh threshold, an eighth threshold, a ninth threshold, or a tenth threshold.

[0262] In implementation, the trigger condition is determined by the source access network device, and the source access network device sends first configuration information to the terminal device to notify the terminal device of the trigger condition.

[0263] In another implementation, the trigger condition is determined by a target access network device, which sends configuration information to a source access network device, and the source access network device forwards the first configuration information to the terminal device and notifies the terminal device of the trigger condition by using the first setting condition.

[0264] S1202: The terminal device successfully performs handover to a first cell managed by a target access network device.

[0265] The terminal device performs a cell handover according to the handover command to successfully perform a handover to the first cell managed by the target access network device. After successfully performing the handover to the target access network device, the terminal device may initiate a TAU update process to complete the TAU update with the target access network device.

[0266] For example, the target access network device may be an eNodeB in an LTE network.

[0267] S1203: The terminal device establishes a voice service channel with the target access network device.

[0268] The terminal device stops the fifth timer. In this case, the operation period of the fifth timer is the period from when the terminal device receives the handover command to when the voice service channel is successfully established, i.e., the voice service interruption period. Alternatively, the operation period of the fifth timer is the period from when the terminal device receives the handover command to when the terminal device successfully communicates service data packets with the target access network device.

[0269] S1204: The terminal device sends a fourth report to the source access network device, wherein the fourth report includes an operation period of a fifth timer.

[0270] When a trigger condition for recording a fourth report is satisfied by the terminal device, the terminal device records the fourth report. For example, the terminal device successfully completes a random access procedure between the terminal device and the first cell, when a trigger condition for recording a fourth report is satisfied, the terminal device records the fourth report.

[0271] Optionally, the fourth report includes third indication information, where the third indication information indicates that a trigger cause for performing a cell handover by the terminal device is a voice service fallback. Alternatively, the third indication information indicates that a handover trigger cause for performing a cell handover by the terminal device is a normal voice service fallback or an emergency voice service fallback.

[0272] In this embodiment, when the terminal device determines that there is a potential handover failure risk in the process of performing handover from the source cell to the first cell, it records a fourth report. The fourth report includes the operation period of the fifth timer, so that the access network devices involved in the handover process (e.g., the source access network device and / or the target access network device) can perform network configuration parameter optimization by referring to the service interruption period and the context of the terminal device in the fourth report, for example, by reducing the handover threshold to reduce the probability of handover failure and / or shorten the excessively long service interruption time of the terminal device. In this embodiment of the present application, the terminal device sends a report (e.g., one or more of the first report to the fifth report) to the access network device. For example, the terminal device sends a report to access network device A.

[0273] If the target device of the report is the source access network device, in other words, the report needs to be sent to the source access network device, and if access network device A and the source access network device are different network devices, access network device A sends some or all of the information related to the report to the source access network device. Optionally, access network device A may further send report type information to the source access network device. The report type may be a report type of a 5G (e.g., NR or gNB) RAT, a report type of a 4G (e.g., eLTE or ng-eNB) RAT connected to a 5G core network, a report type of a 4G (e.g., LTE or eNB) RAT connected to a 4G core network, or a report type of another RAT. In implementation, if there is an interface between access network device A and the source access network device that can be directly used for communication, access network device A sends some or all of the information related to the report to the source access network device through an interface between the access network devices (e.g., an interface between base stations). For example, the interface between access network device A and the source access network device may be an X2 interface or an Xn interface. Access network device A may send some or all of the information regarding the report to the source access network device by using a FAILURE INDICATION, a RLF INDICATION message, a HANDOVER REPORT message, an ACCESS AND MOBILITY INDICATION message, or another message.

[0274] In another implementation, if access network device A cannot communicate directly with the source access network device, it may send some or all of the information related to the report to the source access network device via the core network device. Optionally, access network device A may further send report type information to the source access network device. Access network device A may send some or all of the information related to the report to the core network device through an interface between the access network device and the core network device. For example, access network device A sends some or all of the information related to the report to the core network device through the S1 interface or the NG interface, and the core network device forwards the information received from access network device A to the source access network device. The access network device A may send some or all of the information related to the report to the source access network device by using at least one of an UPLINK RAN CONFIGURATION TRANSFER message, a DOWNLINK RAN CONFIGURATION TRANSFER message, an eNB CONFIGURATION TRANSFER message, an MME CONFIGURATION TRANSFER message, or another message over the S1 interface / NG interface.

[0275] If the target device of the report is the target access network device, in other words, the report needs to be sent to the target access network device, and if the access network device A and the target access network device are different network devices, the access network device A sends part or all of the information related to the report to the target access network device. For specific sending manners, please refer to the manner in which the access network device A sends a report to the source access network device. For brevity, the details will not be described again here.

[0276] The method provided in the present disclosure has been described in detail above with reference to Figures 2 to 7, 7A, and 7B. The communication apparatus and communication device provided in the present disclosure will be described below with reference to the accompanying drawings. To implement the above functions in the method provided in the present disclosure, each network element may include a hardware structure and / or a software module, and may implement the above functions in the form of a hardware structure, a software module, or a combination of a hardware structure and a software module. Whether the functions in the above functions are implemented by using a hardware structure, a software module, or a combination of a hardware structure and a software module depends on the specific application and design constraints of the technical solution.

[0277] 8 is a block diagram of a communication device according to the present disclosure. As shown in FIG. 8, the communication device 800 may include a transceiver unit 820.

[0278] In a possible design, the communication device 800 may correspond to a terminal device in the above methods, a chip disposed within (or used in) the terminal device, or another apparatus, module, circuit, unit, etc. capable of implementing the methods performed by the terminal device.

[0279] It should be understood that the communication apparatus 800 may include units configured to perform the methods performed by the terminal devices in the methods shown in Figures 2 to 7, 7A, and 7B. In addition, each of the units in the communication apparatus 800 and other operations and / or functions described above is intended to implement the corresponding procedure of the method shown in Figures 2 to 7, 7A, and 7B.

[0280] Optionally, the communication device 800 may further include a processing unit 810. The processing unit 810 may be configured to process instructions or data and implement corresponding operations.

[0281] It should be further understood that when the communication device 800 is a chip disposed in (or used in) a terminal device, the transceiver unit 820 in the communication device 800 may be an input / output interface or circuitry in the chip, and the processing unit 810 in the communication device 800 may be a processor in the chip.

[0282] Optionally, the communication device 800 may further include a storage unit 830. The storage unit 830 may be configured to store instructions or data. The processing unit 810 may execute the instructions or data stored in the storage unit to enable the communication device to implement corresponding operations.

[0283] It should be understood that the transceiver unit 820 in the communication device 800 may be implemented through a communication interface (e.g., a transceiver or an input / output interface) and may, for example, correspond to the transceiver 910 in the terminal device 900 shown in FIG. 9. The processing unit 810 in the communication device 800 may be implemented by using at least one processor and may, for example, correspond to the processor 920 in the terminal device 900 shown in FIG. 9. Alternatively, the processing unit 810 in the communication device 800 may be implemented by using at least one logical unit. The storage unit 830 in the communication device 800 may correspond to the memory in the terminal device 900 shown in FIG. 9.

[0284] Furthermore, it should be understood that the specific process of each unit performing the above corresponding steps has been described in detail in the above method, and for the sake of brevity, the details will not be described again here.

[0285] In another possible design, the communications device 800 may correspond to an access network device in the above methods, a chip disposed within (or used in) the access network device, or another apparatus, module, circuit, unit, etc. capable of implementing the methods performed by the access network device.

[0286] It should be understood that the communications apparatus 800 may include units configured to perform the methods performed by the access network devices in the methods illustrated in Figures 2 to 7, 7A, and 7B. In addition, each of the units in the communications apparatus 800 and other operations and / or functions described above is intended to implement the corresponding procedure of the methods illustrated in Figures 2 to 7, 7A, and 7B.

[0287] Optionally, the communication device 800 may further include a processing unit 810. The processing unit 810 may be configured to process instructions or data and implement corresponding operations.

[0288] It should be further understood that when the communication device 800 is a chip disposed in (or used in) an access network device, the transceiver unit 820 in the communication device 800 may be an input / output interface or circuitry in the chip, and the processing unit 810 in the communication device 800 may be a processor in the chip.

[0289] Optionally, the communication device 800 may further include a storage unit 830. The storage unit 830 may be configured to store instructions or data. The processing unit 810 may execute the instructions or data stored in the storage unit to enable the communication device to implement corresponding operations.

[0290] It should be understood that when the communication device 800 is an access network device, the transceiver unit 820 in the communication device 800 may be implemented through a communication interface (e.g., a transceiver or an input / output interface) and may correspond, for example, to the transceiver 1010 in the network device 1000 shown in FIG. 10. The processing unit 810 in the communication device 800 may be implemented by using at least one processor and may correspond, for example, to the processor 1020 in the network device 1000 shown in FIG. 10. The processing unit 810 in the communication device 800 may be implemented by using at least one logical unit. The storage unit 830 in the communication device 800 may correspond to the memory in the network device 1000 shown in FIG. 10.

[0291] Furthermore, it should be understood that the specific process of each unit performing the above corresponding steps has been described in detail in the above method, and for the sake of brevity, the details will not be described again here.

[0292] 9 is a diagram of the structure of a terminal device 900 according to the present disclosure. The terminal device 900 may be used in the system shown in FIG. 1 to implement the functions of the terminal device in the above-described method. As shown, the terminal device 900 includes a processor 920 and a transceiver 910. Optionally, the terminal device 900 further includes a memory. The processor 920, the transceiver 910, and the memory may communicate with each other through an internal connection path to transfer control signals and / or data signals. The memory is configured to store a computer program, and the processor 920 is configured to execute the computer program in the memory to control the transceiver 910 to receive and send signals.

[0293] The processor 920 may be implemented in the terminal device and configured to perform the actions described in the above method. The transceiver 910 may be configured to perform the actions sent to or received from the network device by the terminal device in the above method. For details, please refer to the description in the above method. The details will not be described again here.

[0294] Optionally, the terminal device 900 may further include a power source configured to provide power to various devices or circuits within the terminal device.

[0295] FIG. 10 is a diagram of the structure of a network device 1000 according to the present disclosure. The network device 1000 may be used in the system shown in FIG. 1 to implement the functionality of the access network device in the above-described method. As shown, the network device 1000 includes a processor 1020 and a transceiver 1010. Optionally, the network device 1000 further includes a memory. The processor 1020, the transceiver 1010, and the memory may communicate with each other through an internal connection path to transfer control and / or data signals. The memory is configured to store a computer program, and the processor 1020 is configured to execute the computer program in the memory to control the transceiver 1010 to receive and send signals.

[0296] The processor 1020 may be implemented within the network device and configured to perform the actions described in the above method. The transceiver 1010 may be configured to perform the actions transmitted to or received from the network device by the network device in the above method. For details, please refer to the description in the above method. The details will not be described again here.

[0297] Optionally, the network device 1000 may further include a power supply configured to provide power to various devices or circuits within the network device.

[0298] In the terminal device shown in FIG. 9 and the network device shown in FIG. 10, the processor and the memory may be combined into one processing unit, and the processor is configured to execute program code stored in the memory to implement the above-described functions. In a specific implementation, the memory may alternatively be integrated into the processor or may be separate from the processor. The processor may correspond to the processing unit in FIG. 8. The transceiver may correspond to the transceiver unit in FIG. 8. The transceiver 910 may include a receiver (which may also be referred to as a receiving device or receiver circuit) and a transmitter (which may also be referred to as a transmitting device or transmitter circuit). The receiver is configured to receive signals, and the transmitter is configured to transmit signals.

[0299] In this disclosure, a processor may be a general-purpose processor, a digital signal processor, an application-specific integrated circuit, a field programmable gate array or other programmable logic device, a discrete gate or transistor logic device, or a discrete hardware component, which may implement or execute the methods, steps, and logic block diagrams in this disclosure. A general-purpose processor may be a microprocessor or any conventional processor, etc. The steps of the methods disclosed with reference to this disclosure may be performed and completed directly by a hardware processor, or may be performed and completed using a combination of hardware and software modules in a processor.

[0300] In the present disclosure, memory may be a non-volatile memory, such as a hard disk drive (HDD) or a solid-state drive (SSD), or a volatile memory, such as a random-access memory (RAM). Memory is any other medium capable of carrying or storing expected program code in the form of instruction structures or data structures and capable of being accessed by a computer, but is not limited thereto. Memory in the present application may alternatively be a circuit or any other device capable of implementing a storage function and configured to store program instructions and / or data.

[0301] The present disclosure further provides a processing device, the processing device including a processor and a (communication) interface, the processor configured to perform any one of the above methods.

[0302] It should be understood that the processing device may be one or more chips, for example, a field programmable gate array (FPGA), an application-specific integrated circuit (ASIC), a system on a chip (SoC), a central processing unit (CPU), a network processor (NP), a digital signal processor (DSP), a microcontroller unit (MCU), a programmable logic device (PLD), or another integrated chip.

[0303] According to the methods provided in the present disclosure, the present disclosure further provides a computer program product, which includes computer program code that, when executed by one or more processors, enables an apparatus including the processors to perform the methods shown in Figures 2 to 7, 7A, and 7B.

[0304] All or part of the technical solutions provided in this disclosure may be implemented by using software, hardware, or any combination thereof. When software is used to implement the technical solutions, all or part of the technical solutions may be implemented in the form of a computer program product. The computer program product includes one or more computer instructions. When the computer program instructions are loaded and executed on a computer, all or part of the procedures or functions according to the present invention are generated. The computer instructions may be stored in a computer-readable storage medium or transmitted from one computer-readable storage medium to another. The computer-readable storage medium may be any available medium accessible by a computer, or a storage device, such as a server or data center, that integrates one or more available media. The available medium may be a magnetic medium (e.g., a floppy disk, a hard disk, or a magnetic tape), an optical medium (e.g., a digital video disk (DVD)), a semiconductor medium, etc.

[0305] According to the method provided in the present disclosure, the present disclosure further provides a computer-readable storage medium that stores program code that, when executed by one or more processors, enables an apparatus including the processors to perform the methods shown in Figures 2 to 7, 7A, and 7B.

[0306] According to the method provided in the present disclosure, the present disclosure further provides a system, the system including one or more terminal devices as described above, the system further including one or more access network devices as described above.

[0307] In some embodiments provided in the present application, it should be understood that the disclosed systems, devices, and methods may be implemented in other ways. For example, the described devices are merely examples. For example, the division into units is merely a logical functional division, and other divisions may be used in actual implementation. For example, multiple units or components may be combined or integrated into another system, or some features may be omitted or not implemented. Furthermore, the shown or described mutual couplings or direct couplings or communication connections may be implemented through some interfaces. Indirect couplings or communication connections between devices or units may be implemented in electronic, mechanical, or other forms.

[0308] Units described as separate parts may or may not be physically separate, and parts shown as units may or may not be physical units, in other words, they may be located in one location or distributed over multiple network units. Some or all of the units may be selected based on actual requirements to achieve the objectives of the solution in the embodiments.

[0309] The above description is merely a specific implementation of the present disclosure and does not limit the protection scope of the present disclosure. Any variations or replacements that are easily understood by those skilled in the art within the technical scope disclosed in the present disclosure should fall within the protection scope of the present disclosure. Therefore, the protection scope of the present disclosure should be subject to the protection scope of the claims.

Claims

1. 1. A communication method, the method being applied to a terminal device, the method comprising: performing a redirection from a source cell to a target cell, the source cell being managed by a source access network device and the target cell being managed by a target access network device; transmitting a first report, the first report including information indicating a possibility of failure in a process of performing cell redirection by the terminal device, the first report including identification information of the target cell; A communication method, including:

2. The method comprises: Recording the first report when the cell redirection process satisfies a reporting condition, wherein the reporting condition is one of the following conditions: an operating period of a first timer is less than or equal to a first threshold and greater than or equal to a second threshold, and the operating period of the first timer is a period from when the terminal device receives a radio resource control (RRC) release message from the source access network device to when the terminal device transmits a random access preamble to the target access network device; an operating period of a second timer is less than or equal to a third threshold and greater than or equal to a fourth threshold, and the operating period of the second timer is a period from the time when the terminal device receives the RRC release message from the source access network device to the time when the terminal device receives an RRC connection setup message from the target access network device; an operating period of a third timer is less than or equal to a fifth threshold and greater than or equal to a sixth threshold, and the operating period of the third timer is a period from the time when the terminal device sends an RRC connection request message to the target access network device to the time when the terminal device receives the RRC connection setup message from the target access network device; or the terminal device fails to perform cell redirection on a first frequency and successfully performs cell redirection on a frequency other than the first frequency, the first frequency being a candidate frequency configured for the terminal device by the source access network device and utilized for the cell redirection, and the frequency of the target cell being the frequency other than the first frequency; [0033] The method of claim 1.

3. the second threshold is the product of the first threshold and a first coefficient; and / or the fourth threshold is the product of the third threshold and a second factor; and / or the sixth threshold is a product of the fifth threshold and a third coefficient; the first coefficient, the second coefficient, and the third coefficient are less than 1; The method of claim 2.

4. The method comprises: receiving a first indication, the first indication indicating the reporting condition; The method according to claim 2 or 3.

5. The step of receiving, by the terminal device, first indication information includes: receiving an RRC message, the RRC message including the first indication information; The method of claim 4.

6. The first report is as follows: indicating one or more of the reporting condition, the identity information of the source cell, cell measurement information, redirection frequency information, the identity information of the target cell, frequency information of the target cell, the operation period of the first timer, the operation period of the second timer, the operation period of the third timer, or the operation period of a fourth timer; the cell measurement information includes one or more of measurement information of the source cell, measurement information of the target cell, measurement information of neighboring cells of the source cell, or measurement information of neighboring cells of the target cell; The operating period of the fourth timer is a period from the time when the terminal device receives the RRC release message from the source access network device to the time when the terminal device successfully establishes a service channel with the target access network device, or The operation period of the fourth timer is a period from the time when the terminal device receives the RRC release message from the source access network device to the time when the terminal device successfully communicates a service data packet with the target access network device; The method according to any one of claims 2 to 5.

7. The step of transmitting a first report by the terminal device comprises: transmitting the first report to the target access network device, the first report including the identification information of the source cell. The method according to any one of claims 1 to 6.

8. The first report further includes second indication information, and the second indication information indicates whether the cell redirection is triggered by a service or by signal coverage quality. The method according to any one of claims 1 to 7.

9. the cell redirection is triggered by the service, and the target access network device and the source access network device utilize different radio access technology RATs; The method according to any one of claims 1 to 8.

10. receiving a first report from a terminal device, the first report including information indicating a possibility of failure in a process of performing cell redirection by the terminal device, and including identification information of a target cell for the redirection, the target cell being managed by a target access network device; A communication method, including:

11. The method comprises: sending the first report to a source access network device, the first report including an identity of a source cell for the redirection, the source cell being managed by the source access network device; and / or adjusting network configuration parameters based on the first report. further comprising: The method of claim 10.

12. The first report indicates a reporting condition for triggering the terminal device to send the first report, and the reporting condition is one of the following conditions: an operating period of a first timer is less than or equal to a first threshold and greater than or equal to a second threshold, and the operating period of the first timer is a period from when the terminal device receives a radio resource control (RRC) release message from the source access network device to when the terminal device transmits a random access preamble to the target access network device; an operating period of a second timer is less than or equal to a third threshold and greater than or equal to a fourth threshold, and the operating period of the second timer is a period from the time when the terminal device receives the RRC release message from the source access network device to the time when the terminal device receives an RRC connection setup message from the target access network device; an operating period of a third timer is less than or equal to a fifth threshold and greater than or equal to a sixth threshold, and the operating period of the third timer is a period from the time when the terminal device sends an RRC connection request message to the target access network device to the time when the terminal device receives the RRC connection setup message from the target access network device; or the terminal device fails to perform cell redirection on a first frequency and successfully performs cell redirection on a frequency other than the first frequency, the first frequency being a candidate frequency configured for the terminal device by the source access network device and utilized for the cell redirection, and the frequency of the target cell being the frequency other than the first frequency; and the source access network device manages the source cell for the cell redirection; 12. The method according to claim 10 or 11.

13. the second threshold is the product of the first threshold and a first coefficient; and / or the fourth threshold is the product of the third threshold and a second factor; and / or the sixth threshold is a product of the fifth threshold and a third coefficient; the first coefficient, the second coefficient, and the third coefficient are less than 1; The method of claim 12.

14. The first report is as follows: indicating one or more of the identification information of the source cell, cell measurement information, redirection frequency information, the identification information of the target cell, frequency information of the target cell, the operation period of the first timer, the operation period of the second timer, the operation period of the third timer, or the operation period of a fourth timer; the cell measurement information includes one or more of measurement information of the source cell, measurement information of the target cell, measurement information of neighboring cells of the source cell, or measurement information of neighboring cells of the target cell; The operating period of the fourth timer is a period from the time when the terminal device receives the RRC release message from the source access network device to the time when the terminal device successfully establishes a service channel with the target access network device, or The operation period of the fourth timer is a period from the time when the terminal device receives the RRC release message from the source access network device to the time when the terminal device successfully communicates a service data packet with the target access network device; 14. The method according to claim 12 or 13.

15. The method comprises: sending first indication information to the terminal device, the first indication information indicating the reporting condition; The method according to any one of claims 12 to 14.

16. The step of transmitting first indication information to the terminal device comprises: sending an RRC message to the terminal device, the RRC message including the first indication information; 16. The method of claim 15.

17. The first report further includes second indication information, and the second indication information indicates whether the cell redirection is triggered by a service or by signal coverage quality. The method according to any one of claims 10 to 16.

18. The cell redirection is triggered by a voice service, the target access network device and the source access network device utilize different radio access technologies (RATs), and the source access network device manages the source cell for the cell redirection. The method according to any one of claims 10 to 17.

19. 1. A communication method, the method being applied to a terminal device, the method comprising: failing to perform a handover to the first cell; establishing a communication connection to a second cell managed by the access network device; sending a second report to the access network device, the second report indicating that the terminal device fails to perform handover to the first cell, the second report including fourth indication information, the fourth indication information indicating that the handover of the terminal device to the first cell is triggered by a service or by signal coverage quality; A communication method, including:

20. The second report further includes fifth indication information, and the fifth indication information indicates whether the terminal device selects a cell that meets a condition, or indicates whether the terminal device selects a suitable cell.

20. The method of claim 19.

21. receiving a second report from a terminal device, the second report indicating that the terminal device will fail to perform handover to a first cell, the second report including fourth indication information, the fourth indication information indicating that the handover of the terminal device to the first cell is triggered by a service or by signal coverage quality; Communication method.

22. The second report further includes fifth indication information, and the fifth indication information indicates whether the terminal device selects a cell that meets a condition, or indicates whether the terminal device selects a suitable cell.

22. The method of claim 21.

23. A communication method, the method being applied to a terminal device, the terminal device failing to perform a handover from a source cell to a first cell, the handover being triggered by a voice service, the method comprising: performing cell selection but failing to select a cell that satisfies the condition; sending a third report to a second access network device, the third report indicating that the terminal device will fail to perform handover to the first cell, the second access network device managing the source cell; A communication method, including:

24. the third report includes fourth indication information and / or fifth indication information, the fourth indication information indicating that the handover is triggered by the voice service, and the fifth indication information indicating that the terminal device does not select the cell that satisfies the condition; 24. The method of claim 23.

25. The step of transmitting a third report to a second access network device comprises: performing a connection re-establishment with the second access network device; transmitting the third report to the second access network device; Including, 25. The method of claim 23 or 24.

26. 1. A communication method, the method being applied to a second access network device, the method comprising: receiving a third report from a terminal device, the third report indicating that the terminal device will fail to perform a handover to a first cell, the second access network device managing the source cell; A communication method, including:

27. The third report includes fourth indication information and / or fifth indication information, the fourth indication information indicating that the handover is triggered by a voice service, and the fifth indication information indicating that the terminal device does not select a cell that satisfies a condition.

27. The method of claim 26.

28. The step of receiving a third report from the terminal device includes: performing a connection re-establishment with the terminal device; receiving the third report from the terminal device; Including, 28. The method of claim 26 or 27.

29. A communication device comprising a unit or module adapted to carry out the method according to any one of claims 1 to 9, 19 and 20, or 23 to 25.

30. A communication device comprising a unit or module configured to carry out the method according to any one of claims 10 to 18, 21 and 22 or 26 to 28.

31. A communication device comprising a processor and a communication interface, wherein the processor executes, via the communication interface, a method according to any one of claims 1 to 9, 19 and 20, or 23 to 25, or a method according to any one of claims 10 to 18, 21 and 22, or 26 to 28.

32. A computer readable storage medium storing instructions which, when executed on a computer, enable the computer to perform a method according to any one of claims 1 to 9, 19 and 20, or 23 to 25, or a method according to any one of claims 10 to 18, 21 and 22, or 26 to 28.

33. 1. A computer program product comprising instructions which, when executed, perform the method of any one of claims 1 to 9, 19 and 20, or 23 to 25, or the method of any one of claims 10 to 18, 21 and 22, or 26 to 28.

34. A communication system including an access network device, said access network device being configured to perform the method of any one of claims 10 to 18, 19 and 20, or 23 to 25.

35. A communication system according to claim 34, comprising a terminal device, said terminal device being configured to carry out the method of any one of claims 1 to 9, 21 and 22, or 26 to 28.

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