Communication method and apparatus

Abstract

Embodiments of the present application disclose a communication method and apparatus. The method includes a network device sending first information to a terminal device in an RRC connected state to instruct the terminal device to receive a multicast service in an RRC idle state. The terminal device enters the RRC idle state, and in the RRC idle state, receives the multicast service via a serving cell of the terminal device in the RRC connected state. Thereby, it is possible to avoid interruption of the multicast service due to a change in the serving cell caused by an RRC state change and improve the continuity of the multicast service.

Description

Technical Field

[0001] This application claims the priority of Chinese Patent Application No. 202210899957.9, entitled "Communication Method and Apparatus", filed with the China National Intellectual Property Administration on July 28, 2022, and the entire content thereof is incorporated herein by reference.

[0002] Embodiments of this application relate to the field of communication technologies, and in particular, to communication methods and apparatuses.

Background Art

[0003] In the 3rd generation partnership project (3GPP (registered trademark)) standard release (Rel)-17, when receiving a multicast broadcast service (MBS) multicast service, only terminal devices in the radio resource control (RRC) connected state are supported. However, when the number of terminal devices receiving the MBS multicast service in a cell is excessively large, the number of terminal devices in the RRC connected state may exceed the number of terminal devices that can be accommodated in the cell and be in the RRC connected state. Therefore, in Rel-18, in order to relieve network congestion, it is proposed that terminal devices support receiving the MBS multicast service in the RRC idle state, but the terminal devices need to enter the RRC idle state from the RRC connected state.

[0004] The terminal device needs to enter the RRC idle state from the RRC connected state and perform cell selection. When the terminal device selects another cell that meets the cell camping criteria, the terminal device needs to reacquire the multicast service configuration information of the cell and then receive the multicast service based on the multicast service configuration of the cell. However, reacquiring the multicast service configuration of the cell and then receiving the multicast service causes an interruption of the multicast service and affects the continuity of the multicast service.

Summary of the Invention

[0005] Embodiments of the present application disclose a communication method and apparatus for improving the continuity of multicast services.

Means for Solving the Problems

[0006] According to a first aspect, the present application discloses a communication method. The communication method may be applied to a terminal device, may be applied to a module (e.g., a chip) of the terminal device, or may be applied to a logical module or software that can implement all or part of the functions of the terminal device. Hereinafter, an example in which the method is applied to a terminal device will be used for explanation. The communication method includes the steps of receiving first information from a network device in the RRC connected state, where the first information instructs the terminal device to receive a multicast service in the RRC idle state, entering the RRC idle state, and receiving a multicast service in the RRC idle state via a first cell, where the first cell is the serving cell of the terminal device in the RRC connected state.

[0007] In this embodiment of the present application, after the terminal device receives first information instructing the terminal device to receive a multicast service from a network device and being in the RRC idle state, after the terminal device enters the RRC idle state from the RRC connected state, the terminal device receives the multicast service in the RRC idle state via the serving cell in the RRC connected state. Thereby, it is possible to avoid interruption of the multicast service caused by the change of the serving cell due to the RRC state change, and improve the continuity of the multicast service.

[0008] In a possible implementation form, when the terminal device enters the RRC idle state from the RRC connected state, the step of performing cell selection is skipped.

[0009] In this embodiment of the present application, when the terminal device enters the RRC idle state from the RRC connected state, the step of performing cell selection is skipped. Thereby, it is possible to avoid the case where the terminal device executes the cell selection process, reduce the processing process of the terminal device, and reduce the power consumption of the terminal device.

[0010] In a possible implementation form, the fact that the terminal device skips the step of performing cell selection may include that when the first cell meets the camping condition, the cell camped on by the terminal device is the first cell.

[0011] In this embodiment of the present application, when the first cell meets the camping condition, the cell camped on by the terminal device is the first cell. This can ensure that the terminal device camps on the first cell with good signal quality to receive the multicast service, and meets the service quality requirements of the multicast service. This can avoid the case where the terminal device selects another cell when the serving cell has good coverage, resulting in interruption of the multicast service. In addition, the unnecessary cell selection process is avoided, and the power consumption of the terminal device can be reduced.

[0012] In a possible implementation form, the first information is carried by an RRC release message, and the terminal device entering the RRC idle state may include entering the RRC idle state based on the RRC release message.

[0013] In this embodiment of the present application, the first information is carried by an RRC release message for transmission. Thereby, it is possible to avoid using a dedicated message or dedicated signaling to transmit the first information, save transmission resources, and reduce the quantity of messages or signaling for transmission in order to improve compatibility with existing protocols. In addition, the first information is carried by an RRC release message. When network congestion occurs (for example, the quantity of multicast terminal devices in the RRC connected state of the cell is greater than a preset threshold, or the quantity of RRC connected terminal devices in the cell is greater than a preset threshold), the network device instructs the terminal device to enter the RRC idle state by using the RRC release message, and the purpose of the terminal device entering the RRC idle state indicates that it is to receive a multicast service in the RRC idle state. Therefore, this can improve the efficiency of the step of receiving the multicast service and is more compatible with existing protocols.

[0014] In a possible implementation form, the first information may indicate an identifier of a multicast service or an identifier of a multicast radio bearer (MRB), and the MRB is an MRB associated with the multicast service.

[0015] In this embodiment of the present application, the terminal device may indicate an identifier of a multicast service or an identifier of an MRB associated with the multicast service by using first information to receive one or more specific multicast services. Thereby, the case where the terminal device receives all multicast services is avoided, the number of multicast services received by the terminal device is reduced, and the power consumption of the terminal device can be reduced.

[0016] In a possible implementation form, the communication method may further include the step of receiving first configuration information from a network device, and the first configuration information is used to configure the terminal device to receive a multicast service in an RRC idle state. The terminal device receiving a multicast service in an RRC idle state via a first cell may include the step of receiving a multicast service in an RRC idle state via the first cell based on the first configuration information.

[0017] In this embodiment of the present application, the terminal device may receive a multicast configuration in an RRC idle state from a network device via a first cell in an RRC connected state, and receive a multicast service via the first cell after entering the RRC idle state. In order to improve the efficiency of the step of receiving the multicast service, it is not necessary to reacquire the multicast configuration. In particular, when the terminal device is already receiving a multicast service in an RRC connected state, the terminal device can avoid the case where the multicast service is interrupted due to the reacquisition of the multicast configuration, and improve the continuity of the multicast service.

[0018] In a possible implementation form, the first configuration information is further used to configure the terminal device to receive a multicast service in an RRC connected state.

[0019] In this embodiment of the present application, one piece of configuration information is not only used by the terminal device to receive a multicast service in the RRC idle state, but may also be used by the terminal device to receive a multicast service in the RRC connected state. Thereby, it is possible to avoid a case where one piece of configuration information is separately configured in the RRC idle state and the RRC connected state, and the utilization rate of the configuration information can be improved. In addition, in order to save transmission resources, the number of times of transmitting the configuration information can be further reduced, and the number of times of information transmission can be reduced.

[0020] In a possible implementation form, the first piece of configuration information is carried in an RRC reconfiguration message.

[0021] In this embodiment of the present application, the first piece of configuration information is carried in an RRC reconfiguration message for transmission. Thereby, it is possible to avoid transmitting the first piece of configuration information using a dedicated message or dedicated signaling, save transmission resources, and reduce the quantity of messages or signaling for transmission in order to improve compatibility with existing protocols.

[0022] In a possible implementation form, the communication method may further include a step of transmitting second information to a network device, and the second information indicates that the step of receiving a multicast service in the RRC idle state is supported.

[0023] In this embodiment of the present application, when the terminal device supports the step of receiving a multicast service in the RRC idle state, the terminal device may report the capabilities of the terminal device to the network device, and as a result, the network device can transmit the first information to the terminal device based on the capabilities reported by the terminal device. Thereby, it is possible to avoid a case where the terminal device does not support the step of receiving a multicast service in the RRC idle state and the network device transmits the first information to the terminal device.

[0024] In a possible implementation form, the communication method may further include the step of obtaining system information from a network device, and the system information is the system information required in the RRC idle state.

[0025] In this embodiment of the present application, the terminal device obtains system information after entering the RRC idle state. Thereby, since the terminal device skips the step of receiving the system message used in the RRC idle state, it is possible to avoid the case where the terminal device cannot correctly perform cell reselection.

[0026] In a possible implementation form, the RRC idle state may include the RRC idle state and / or the RRC inactive state.

[0027] In a possible implementation form, the communication method may further include the step of receiving third information from a network device, and the third information indicates skipping the step of entering from the RRC connected state to the RRC idle state and performing cell selection.

[0028] In this embodiment of the present application, after receiving the third information indicating skipping the step of entering from the RRC connected state to the RRC idle state and performing cell selection, which is from a network device, the terminal device skips the step of performing cell selection after entering the RRC idle state. Thereby, it is possible to avoid the case where the terminal device performs cell selection and subsequent processes, reduce the power consumption of the terminal device, and improve the continuity of the multicast service.

[0029] In a possible implementation form, the third information is carried in an RRC release message or an RRC reconfiguration message.

[0030] In this embodiment of the present application, the third information is carried by an RRC release message or an RRC reconfiguration message for transmission. Thereby, the transmission of the third information is avoided from being performed using a dedicated message or dedicated signaling, the transmission resources can be saved, and the quantity of messages or signaling for transmission can be reduced in order to improve the compatibility with existing protocols.

[0031] In a possible implementation, the communication method may further include the step of receiving fourth information from a network device, where the fourth information indicates a frequency priority, and the step of selecting a cell camped in descending order of frequency priority when performing cell selection.

[0032] In this embodiment of the present application, after receiving the fourth information indicating the frequency priority from the network device, the terminal device may select a cell camped in descending order of frequency priority when performing cell selection. In addition, when the frequency of the first cell is the frequency with the highest priority, the terminal device may preferentially select the first cell. Thereby, the interruption of the multicast service can be avoided and the power consumption of the terminal device can be reduced.

[0033] In a possible implementation, the fourth information is carried by a system message or an RRC release message.

[0034] In this embodiment of the present application, the fourth information is carried by a system message or an RRC release message for transmission. Thereby, the transmission of the fourth information is avoided from being performed using a dedicated message or dedicated signaling, the transmission resources can be saved, and the quantity of messages or signaling for transmission can be reduced in order to improve the compatibility with existing protocols.

[0035] According to a second aspect, the present application discloses a communication method. The communication method may be applied to a network device, or may be applied to a module (e.g., a chip) of the network device, or alternatively may be applied to a logical module or software capable of implementing all or part of the functions of the network device. Hereinafter, an example in which the present method is applied to a network device will be used for explanation. The communication method may include a step of transmitting first information to a terminal device in an RRC connected state, where the first information instructs the terminal device to receive a multicast service in an RRC idle state, and the first information is used by the terminal device to receive a multicast service in an RRC idle state via a first cell, and the first cell is the cell camped by the terminal device in the RRC connected state.

[0036] In this embodiment of the present application, the network device transmits first information to the terminal device to instruct the terminal device to receive a multicast service in an RRC idle state. As a result, after entering the RRC idle state from the RRC connected state, the terminal device receives a multicast service in the RRC idle state via the serving cell in the RRC connected state. Thereby, it is possible to avoid interruption of the multicast service caused by a change in the serving cell due to a change in the RRC state of the terminal device and improve the continuity of the multicast service.

[0037] In a possible implementation, the first information is further used by the terminal device to skip the step of performing cell selection when entering the RRC idle state from the RRC connected state.

[0038] In this embodiment of the present application, the first information may enable the terminal device to skip the step of performing cell selection when entering the RRC idle state from the RRC connected state. Thereby, it is possible to avoid the case where the terminal device performs the cell selection process, reduce the processing process of the terminal device, and reduce the power consumption of the terminal device.

[0039] In a possible implementation form, skipping the step in which the terminal device performs cell selection includes that when the first cell meets the camping condition, the camped cell is the first cell.

[0040] In this embodiment of the present application, when the first cell meets the camping condition, the camped cell of the terminal device is the first cell. This can ensure that the terminal device camps on the first cell with good signal quality to receive the multicast service, and meets the service quality requirements of the multicast service. This can avoid the situation where the terminal device selects another cell when the serving cell has good coverage, resulting in the interruption of the multicast service. In addition, the unnecessary cell selection process is avoided, and the power consumption of the terminal device can be reduced.

[0041] In a possible implementation form, the first information is carried in the RRC release message, and the RRC release message is used by the terminal device to enter the RRC idle state.

[0042] In this embodiment of the present application, the first information is carried by an RRC release message for transmission. This avoids using dedicated messages or dedicated signaling to transmit the first information, saves transmission resources, and reduces the quantity of messages or signaling for transmission in order to improve compatibility with existing protocols. In addition, the first information is carried by an RRC release message. When network congestion occurs (for example, when the quantity of multicast terminal devices in the RRC connected state of a cell is greater than a preset threshold, or when the quantity of RRC connected terminal devices in a cell is greater than a preset threshold), the network device instructs the terminal device to enter the RRC idle state by using the RRC release message, and indicates that the purpose of the terminal device entering the RRC idle state is to receive a multicast service in the RRC idle state. Therefore, this can improve the efficiency of the step of receiving the multicast service and is more compatible with existing protocols.

[0043] In a possible implementation form, the first information may indicate an identifier of a multicast service or an identifier of an MRB, and the MRB is an MRB associated with the multicast service.

[0044] [[ID=۸]]

[0045] In this embodiment of the present application, the network device may indicate an identifier of a multicast service or an identifier of an MRB associated with the multicast service by using the first information in order to enable the terminal device to receive one or more specific multicast services. This avoids the case where the terminal device receives all multicast services, reduces the quantity of multicast services received by the terminal device, and can reduce the power consumption of the terminal device. In a possible implementation form, the communication method may further include a step of transmitting first configuration information to the terminal device, and the first configuration information is used to configure the terminal device to receive a multicast service in the RRC idle state.

[0046] In this embodiment of the present application, the network device may configure a multicast configuration in the RRC idle state for a terminal device in the RRC connected state by using a first cell. As a result, after entering the RRC idle state, the terminal device may receive a multicast service via the first cell based on the configuration information. In order to improve the efficiency of the step of receiving the multicast service, there is no need to re-acquire the multicast configuration. In particular, when the terminal device is already receiving a multicast service in the RRC connected state, the terminal device can avoid the case where the multicast service is interrupted due to the re-acquisition of the multicast configuration, and can improve the continuity of the multicast service.

[0047] In a possible implementation form, the first configuration information is further used to configure the terminal device to receive a multicast service in the RRC connected state.

[0048] In this embodiment of the present application, one piece of configuration information may not only configure the terminal device to receive a multicast service in the RRC idle state, but also configure the terminal device to receive a multicast service in the RRC connected state. Thereby, the case where one piece of configuration information is separately configured in the RRC idle state and the RRC connected state can be avoided, and the utilization rate of the configuration information can be improved. In addition, in order to save transmission resources, the number of times of transmitting the configuration information may be further reduced, and the number of times of information transmission may be reduced.

[0049] In a possible implementation form, the first configuration information is carried in an RRC reconfiguration message.

[0050] In this embodiment of the present application, the first configuration information is carried in an RRC reconfiguration message for transmission. Thereby, in order to avoid transmitting the first configuration information using a dedicated message or dedicated signaling, save transmission resources, and improve compatibility with existing protocols, the quantity of messages or signaling for transmission can be reduced.

[0051] In a possible implementation form, the communication method further includes the step of receiving second information from a terminal device, and the second information indicates that the step of receiving a multicast service in the RRC idle state is supported.

[0052] In this embodiment of the present application, after receiving the capabilities reported by the terminal device, the network device may transmit first information to the terminal device based on the capabilities of the terminal device. Thereby, it is possible to avoid the case where the terminal device does not support the step of receiving a multicast service in the RRC idle state and the network device transmits the first information to the terminal device.

[0053] In a possible implementation form, the communication method may further include the step of transmitting system information to the terminal device, and the system information is the system information required in the RRC idle state.

[0054] In this embodiment of the present application, the network device transmits a system message used in the RRC idle state to the terminal device. Thereby, it is possible to avoid the case where the terminal device cannot correctly perform cell reselection because it has missed the step of receiving the system message used in the RRC idle state.

[0055] In a possible implementation form, the RRC idle state may include the RRC idle state and / or the RRC inactive state.

[0056] In a possible implementation form, the communication method may further include a step of sending third information to a terminal device, where the third information indicates skipping the step of entering from the RRC connected state to the RRC idle state and performing cell selection.

[0057] In this embodiment of the present application, the network device sends third information indicating skipping the step of entering from the RRC connected state to the RRC idle state and performing cell selection to the terminal device. As a result, after entering the RRC idle state, the terminal device skips the step of performing cell selection. Thereby, it is possible to avoid the case where the terminal device performs cell selection and subsequent processes, reduce the power consumption of the terminal device, and improve the continuity of the multicast service.

[0058] In a possible implementation form, the third information is carried in an RRC release message or an RRC reconfiguration message.

[0059] In this embodiment of the present application, the third information is carried in an RRC release message or an RRC reconfiguration message for transmission. Thereby, it is possible to avoid transmitting the third information using dedicated messages or dedicated signaling, save transmission resources, and reduce the quantity of messages or signaling for transmission to improve compatibility with existing protocols.

[0060] In a possible implementation form, the communication method may further include a step of sending fourth information to a terminal device in the RRC connected state, where the fourth information indicates a frequency priority, and the frequency priority is used by the terminal device to select a cell camped in descending order of frequency priority when the terminal device performs cell selection.

[0061] In this embodiment of the present application, the network device transmits fourth information indicating a frequency priority to the terminal device. As a result, when the terminal device performs cell selection, it selects a camped cell in descending order of the frequency priority. In addition, the network device may indicate that the frequency of the first cell is a frequency with the highest priority. As a result, the terminal device may preferentially select the first cell when performing cell selection. Thereby, interruption of the multicast service can be avoided, and power consumption of the terminal device can be reduced.

[0062] In a possible implementation form, the fourth information is carried in a system message or an RRC release message.

[0063] In this embodiment of the present application, the fourth information is carried in a system message or an RRC release message for transmission. Thereby, it is possible to avoid transmitting the fourth information using a dedicated message or dedicated signaling, save transmission resources, and reduce the quantity of messages or signaling for transmission in order to improve compatibility with existing protocols.

[0064] According to a third aspect, the present application discloses a communication method. The communication method may be applied to a terminal device, may be applied to a module (for example, a chip) of the terminal device, or may be applied to a logical module or software capable of realizing all or part of the functions of the terminal device. Hereinafter, an example in which the present method is applied to a terminal device will be used for explanation. The communication method includes a step of receiving third information from a network device in an RRC connected state, where the third information instructs to skip the step of entering from the RRC connected state to the RRC idle state and performing cell selection, and a step of entering the RRC idle state, where the terminal device enters from the RRC connected state to the RRC idle state and skips the step of performing cell selection.

[0065] In this embodiment of the present application, after receiving third information instructing to skip the step of entering from the RRC connected state to the RRC idle state and performing cell selection from a network device, the terminal device enters from the RRC connected state to the RRC idle state and skips the step of performing cell selection. Thereby, it is possible to avoid interruption of the multicast service due to a change in the serving cell caused by an RRC state change, and improve the continuity of the multicast service. In addition, thereby, it is possible to avoid the case where the terminal device performs a cell selection process, reduce the processing process of the terminal device, and reduce the power consumption of the terminal device.

[0066] In a possible implementation form, the step of the terminal device skipping performing cell selection when the first cell satisfies the camping condition, the camping cell may be the first cell, and the first cell may be the serving cell of the terminal device in the RRC connected state.

[0067] In this embodiment of the present application, when the first cell satisfies the camping condition, the cell camped by the terminal device is the first cell. This can ensure that the terminal device camps on the first cell with good signal quality to receive the multicast service, and meets the service quality requirements of the multicast service. This can avoid the case where the terminal device selects another cell when the serving cell has good coverage, resulting in interruption of the multicast service. In addition, an unnecessary cell selection process is avoided, and the power consumption of the terminal device can be reduced.

[0068] In a possible implementation form, the third information is carried in an RRC release message or an RRC reconfiguration message.

[0069] In this embodiment of the present application, the third information is carried in an RRC release message or an RRC reconfiguration message for transmission. Thereby, it is possible to avoid using a dedicated message or dedicated signaling to transmit the third information, save transmission resources, and reduce the quantity of messages or signaling for transmission in order to improve compatibility with existing protocols.

[0070] In a possible implementation form, the RRC idle state may include the RRC idle state and / or the RRC inactive state.

[0071] According to a fourth aspect, the present application discloses a communication method. The communication method may be applied to a network device, may be applied to a module (for example, a chip) of the network device, or may be applied to a logical module or software capable of realizing all or part of the functions of the network device. Hereinafter, an example in which this method is applied to a network device will be used for explanation. The communication method may include a step of transmitting third information to a terminal device in an RRC connected state, where the third information instructs the terminal device to skip the step of entering from the RRC connected state to the RRC idle state and performing cell selection.

[0072] In this embodiment of the present application, the network device transmits third information instructing the terminal device to skip the step of entering from the RRC connected state to the RRC idle state and performing cell selection. As a result, the terminal device enters from the RRC connected state to the RRC idle state and skips the step of performing cell selection. Thereby, it is possible to avoid interruption of the multicast service caused by a change in the serving cell due to the RRC state change and improve the continuity of the multicast service. In addition, this further avoids the case where the terminal device executes the cell selection process, reduces the processing process of the terminal device, and reduces the power consumption of the terminal device.

[0073] In a possible implementation form, the step of the terminal device skipping cell selection may include that when the first cell meets the camping condition, the camped cell is the first cell, and the first cell may be the serving cell before the terminal device enters the RRC connected state.

[0074] In this embodiment of the present application, when the first cell meets the camping condition, the camped cell of the terminal device is the first cell. This can ensure that the terminal device camps on the first cell with good signal quality to receive the multicast service, meeting the service quality requirements of the multicast service. This can avoid the situation where the terminal device selects another cell when the serving cell has good coverage, resulting in the interruption of the multicast service. In addition, unnecessary cell selection processes are avoided, and the power consumption of the terminal device can be reduced.

[0075] In a possible implementation form, the third information is carried in an RRC release message or an RRC reconfiguration message.

[0076] In this embodiment of the present application, the third information is carried in an RRC release message or an RRC reconfiguration message for transmission. This can avoid using dedicated messages or dedicated signaling to transmit the third information, save transmission resources, and reduce the quantity of messages or signaling for transmission to improve compatibility with existing protocols.

[0077] In a possible implementation form, the RRC non-connected state may include the RRC idle state and / or the RRC inactive state.

[0078] According to the fifth aspect, the present application discloses a communication method. The communication method may be applied to a terminal device, may be applied to a module (e.g., a chip) of the terminal device, or may be applied to a logical module or software that can implement all or part of the functions of the terminal device. Hereinafter, an example in which the present method is applied to a terminal device will be used for explanation. The communication method may include a step of receiving fourth information indicating a frequency priority from a network device in an RRC connected state, where the fourth information indicates a frequency priority, and a step of selecting a cell camped in descending order of frequency priority when performing cell selection.

[0079] In this embodiment of the present application, after receiving the fourth information indicating the frequency priority from the network device, the terminal device may select a cell camped in descending order of frequency priority when performing cell selection. In addition, when the frequency of the serving cell of the terminal device in the RRC connected state is the frequency with the highest priority, the terminal device may preferentially select the cell. Thereby, it is possible to avoid interruption of the multicast service caused by the change of the serving cell due to the RRC change and improve the continuity of the multicast service.

[0080] In a possible implementation form, the fourth information is carried by a system message or an RRC release message.

[0081] In this embodiment of the present application, the fourth information is carried by a system message or an RRC release message for transmission. Thereby, it is possible to avoid transmitting the fourth information using a dedicated message or dedicated signaling, save transmission resources, and reduce the quantity of messages or signaling for transmission in order to improve compatibility with existing protocols.

[0082] According to the sixth aspect, the present application discloses a communication method. The communication method may be applied to a network device, or may be applied to a module (e.g., a chip) of the network device, or may be applied to a logical module or software that can implement all or part of the functions of the network device. Hereinafter, an example in which the present method is applied to a network device will be used for explanation. The communication method may include a step of transmitting fourth information to a terminal device in an RRC connected state, where the fourth information indicates a frequency priority, and the frequency priority is used by the terminal device to select a cell camped in descending order of frequency priority when the terminal device performs cell selection.

[0083] In this embodiment of the present application, the network device transmits fourth information indicating a frequency priority to a terminal device in an RRC connected state, so that the terminal device selects a cell camped in descending order of frequency priority when performing cell selection. In addition, the network device may indicate that the frequency of the serving cell of the terminal device in the RRC connected state is the frequency with the highest priority, so that the terminal device may preferentially select a cell when performing cell selection. Thereby, interruption of the multicast service can be avoided and power consumption of the terminal device can be reduced.

[0084] In a possible implementation form, the fourth information is carried in a system message or an RRC release message.

[0085] In this embodiment of the present application, the fourth information is carried in a system message or an RRC release message for transmission. Thereby, it is possible to avoid transmitting the fourth information using a dedicated message or dedicated signaling, save transmission resources, and reduce the quantity of messages or signaling for transmission in order to improve compatibility with existing protocols.

[0086] According to a seventh aspect, the present application discloses a communication device. The communication device may be used in a terminal device, may be used in a module (e.g., a chip) of the terminal device, or may be used in a logical module or software that can implement all or part of the functions of the terminal device. The communication device is a transceiver unit configured to receive first information from a network device in an RRC connected state, where the first information instructs the terminal device to receive a multicast service in an RRC idle state, and may include a processing unit configured to enter the RRC idle state.

[0087] The processing unit is further configured to receive a multicast service in the RRC idle state via a first cell, where the first cell is a serving cell of a terminal device in the RRC connected state.

[0088] In a possible implementation, the terminal device enters from the RRC connected state to the RRC idle state and skips the step of performing cell selection.

[0089] In a possible implementation, the terminal device skipping the step of performing cell selection may include that when the first cell meets the camping condition, the camped cell of the terminal device is the first cell.

[0090] In a possible implementation, the first information is carried in an RRC release message, and the processing unit entering the RRC idle state may include entering the RRC idle state based on the RRC release message.

[0091] In a possible implementation, the first information may indicate an identifier of a multicast service or an identifier of an MRB, where the MRB is an MRB associated with the multicast service.

[0092] In a possible implementation form, the transceiver unit is further configured to receive first configuration information from a network device, and the first configuration information is used to configure the terminal device to receive multicast services in the RRC idle state.

[0093] The processing unit receiving multicast services in the RRC idle state via the first cell may include the step of receiving multicast services in the RRC idle state via the first cell based on the first configuration information.

[0094] In a possible implementation form, the first configuration information is further used to configure the terminal device to receive multicast services in the RRC connected state.

[0095] In a possible implementation form, the first configuration information is carried in an RRC reconfiguration message.

[0096] In a possible implementation form, the transceiver unit is further configured to send second information to the network device, and the second information indicates that the step of receiving multicast services in the RRC idle state is supported.

[0097] In a possible implementation form, the transceiver unit is further configured to obtain system information from the network device, and the system information is the system information required in the RRC idle state.

[0098] In a possible implementation form, the RRC idle state may include the RRC idle state and / or the RRC inactive state.

[0099] In a possible implementation form, the transceiver unit is further configured to receive third information from the network device, and the third information indicates skipping the step of entering the RRC idle state from the RRC connected state and performing cell selection.

[0100] In a possible implementation form, the third information is carried in an RRC release message or an RRC reconfiguration message.

[0101] In a possible implementation form, the transceiver unit is further configured to receive fourth information from a network device, and the fourth information indicates a frequency priority.

[0102] The processing unit is further configured to select a cell camped in descending order of frequency priority when performing cell selection.

[0103] In a possible implementation form, the fourth information is carried in a system message or an RRC release message.

[0104] According to an eighth aspect, the present application discloses a communication device. The communication device may be used in a network device, or may be used in a module (for example, a chip) of a network device, or may be used in a logical module or software capable of realizing all or part of the functions of a network device. The communication device may include a processing unit and a transceiver unit.

[0105] The transceiver unit is configured to transmit first information to a terminal device in an RRC connected state under the control of the processing unit. The first information instructs the terminal device to receive a multicast service in an RRC idle state. The first information is used by the terminal device to receive a multicast service in an RRC idle state via a first cell, and the first cell is a cell camped by the terminal device in an RRC connected state.

[0106] In a possible implementation form, the first information is further used by the terminal device to enter from an RRC connected state to an RRC idle state and skip the step of performing cell selection.

[0107] In a possible implementation form, the terminal device skipping the step of performing cell selection may include that when the first cell meets the camping condition, the camped cell is the first cell.

[0108] In a possible implementation form, the first information is carried in an RRC release message, and the RRC release message is used by the terminal device to enter the RRC idle state.

[0109] In a possible implementation form, the first information may indicate an identifier of a multicast service or an identifier of an MRB, and the MRB is an MRB associated with the multicast service.

[0110] In a possible implementation form, the transceiver unit is further configured to transmit first configuration information to the terminal device under the control of the processing unit, and the first configuration information is used to configure the terminal device to receive a multicast service in the RRC idle state.

[0111] In a possible implementation form, the first configuration information is further used to configure the terminal device to receive a multicast service in the RRC connected state.

[0112] In a possible implementation form, the first configuration information is carried in an RRC reconfiguration message.

[0113] In a possible implementation form, the transceiver unit is further configured to receive second information from the terminal device under the control of the processing unit, and the second information indicates that the step of receiving a multicast service in the RRC idle state is supported.

[0114] In a possible implementation form, the transceiver unit is further configured to transmit system information to the terminal device under the control of the processing unit, and the system information is the system information required in the RRC idle state.

[0115] In a possible implementation form, the RRC idle state may include the RRC idle state and / or the RRC inactive state.

[0116] In a possible implementation form, the transceiver unit is further configured to send third information to the terminal device under the control of the processing unit, and the third information instructs to skip the step of entering from the RRC connected state to the RRC idle state and performing cell selection.

[0117] In a possible implementation form, the third information is carried in an RRC release message or an RRC reconfiguration message.

[0118] In a possible implementation form, the transceiver unit is further configured to send fourth information to the terminal device in the RRC connected state under the control of the processing unit, and the fourth information indicates a frequency priority, and the frequency priority is used by the terminal device to select a cell camped in descending order of frequency priority when the terminal device performs cell selection.

[0119] In a possible implementation form, the fourth information is carried in a system message or an RRC release message.

[0120] According to a ninth aspect, the present application discloses a communication device. The communication device may be used in a terminal device, or may be used in a module (for example, a chip) of the terminal device, or may be used in a logical module or software that can implement all or part of the functions of the terminal device. The communication device is a transceiver unit configured to receive third information from a network device in the RRC connected state, where the third information instructs to skip the step of entering from the RRC connected state to the RRC idle state and performing cell selection, and a processing unit configured to enter the RRC idle state, and the terminal device may include the processing unit that enters from the RRC connected state to the RRC idle state and skips the step of performing cell selection.

[0121] In a possible implementation form, for the terminal device to skip the step of performing cell selection, when the first cell meets the camping condition, the camped cell may be the first cell, and the first cell may be the serving cell of the terminal device in the RRC connected state.

[0122] In a possible implementation form, the third information is carried in an RRC release message or an RRC reconfiguration message.

[0123] In a possible implementation form, the RRC idle state may include the RRC idle state and / or the RRC inactive state.

[0124] According to the tenth aspect, the present application discloses a communication device. The communication device may be used in a network device, or may be used in a module (for example, a chip) of a network device, or may be used in a logical module or software that can implement all or part of the functions of a network device. The communication device may include a processing unit and a transceiver unit.

[0125] The transceiver unit is configured to transmit third information to a terminal device in the RRC connected state under the control of the processing unit, and the third information instructs the terminal device to enter the RRC idle state from the RRC connected state and skip the step of performing cell selection.

[0126] In a possible implementation form, for the terminal device to skip the step of performing cell selection, when the first cell meets the camping condition, the camped cell may be the first cell, and the first cell may be the serving cell before the terminal device enters the RRC connected state.

[0127] In a possible implementation form, the third information is carried in an RRC release message or an RRC reconfiguration message.

[0128] In a possible implementation form, the RRC idle state may include the RRC idle state and / or the RRC inactive state.

[0129] According to an eleventh aspect, the present application discloses a communication device. The communication device may be used in a terminal device, may be used in a module (for example, a chip) of the terminal device, or may be used in a logical module or software capable of realizing all or part of the functions of the terminal device. The communication device a transceiver unit configured to receive fourth information from a network device in an RRC connected state, the fourth information indicating a frequency priority, and may include a processing unit configured to select a cell camped in descending order of frequency priority when performing cell selection.

[0130] In a possible implementation form, the fourth information is carried in a system message or an RRC release message.

[0131] According to a twelfth aspect, the present application discloses a communication device. The communication device may be used in a network device, may be used in a module (for example, a chip) of the network device, or may be used in a logical module or software capable of realizing all or part of the functions of the network device. The communication device may include a processing unit and a transceiver unit.

[0132] The transceiver unit is configured to transmit fourth information to the terminal device under the control of the processing unit, the fourth information indicating a frequency priority, and the frequency priority is used by the terminal device to select a cell camped in descending order of frequency priority when the terminal device performs cell selection.

[0133] In a possible implementation form, the fourth information is carried in a system message or an RRC release message.

[0134] According to the 13th aspect, the present application discloses a communication device. The communication device may be the terminal device (or network device) in the foregoing method embodiment, or a chip or processor disposed in the terminal device (or network device). The communication device includes a processor. The processor is coupled to a memory. The memory is configured to store programs or instructions. When the programs or instructions are executed by the processor, the communication device is enabled to execute the method executed by the terminal device (or network device), or the chip or processor of the terminal device (or network device) in the foregoing method embodiment.

[0135] According to the 14th aspect, the present application discloses a communication device. The communication device may be the terminal device (or network device) in the foregoing method embodiment, or a chip disposed in the terminal device (or network device). The communication device includes a processor and a memory. The memory is configured to store programs or instructions. When the programs or instructions are executed by the processor, the communication device is enabled to execute the method executed by the terminal device (or network device), or the chip or processor of the terminal device (or network device) in the foregoing method embodiment.

[0136] According to the 15th aspect, the present application discloses a communication device. The communication device may be the terminal device (or network device) in the foregoing method embodiment, or a chip disposed in the terminal device (or network device). The communication device includes a communication interface and a processor, and optionally further includes a memory. The memory is configured to store a computer program or instructions. The processor is coupled to the memory and the communication interface. When the processor executes the computer program or instructions, the communication device is enabled to execute the method executed by the terminal device (or network device) or the chip of the terminal device (or network device) in the foregoing method embodiment.

[0137] According to the 16th aspect, the present application discloses a communication system. The communication system may include a terminal device that executes the communication method disclosed in the 1st aspect (or the 3rd aspect, or the 5th aspect) and a network device that executes the communication method disclosed in the 2nd aspect (or the 4th aspect, or the 6th aspect).

[0138] According to the 17th aspect, the present application discloses a computer-readable storage medium. The computer-readable storage medium stores a computer program or computer instructions, and when the computer program or computer instructions are executed by a processor, the communication method disclosed in the foregoing aspect is implemented.

[0139] According to the 18th aspect, the present application discloses a chip including a processor configured to execute a program stored in a memory. When the program is executed, the chip executes the foregoing method.

[0140] In a possible implementation, the memory is located outside the chip.

[0141] According to the 19th aspect, the present application discloses a computer program product. The computer program product includes computer program code, and when the computer program code is executed by a processor, the aforementioned communication method is executed.

[0142] The beneficial effects of the 7th aspect to the 19th aspect are the same as those of the corresponding methods of the 1st aspect to the 6th aspect. For detailed descriptions, please refer to the beneficial effects of the corresponding methods.

Brief Description of Drawings

[0143]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Figure 9

Figure 10

Figure 11

Modes for Carrying Out the Invention

[0144] Embodiments of the present application disclose a communication method and apparatus for improving the continuity of multicast services. Details are described separately below.

[0145] To better understand the embodiments of the present application, the network architecture used in the embodiments of the present application will be first described below. FIG. 1 is a diagram of a network architecture according to an embodiment of the present application. As shown in FIG. 1, the network architecture may include a terminal device 101 and a network device 102. The communication between the terminal device 101 and the network device 102 may include uplink communication (i.e., communication from the terminal device 101 to the network device 102) and downlink communication (i.e., communication from the network device 102 to the terminal device 101). In uplink communication, the terminal device 101 is configured to transmit an uplink signal to the network device 102, and the network device 102 is configured to receive the uplink signal from the terminal device 101. The uplink signal may be uplink control information, and the transmission of the uplink signal may be performed through a physical uplink control channel (PUCCH). Alternatively, the uplink signal may be uplink data, and the transmission of the uplink signal may be performed through a physical uplink share channel (PUSCH). In downlink communication, the network device 102 is configured to transmit a downlink signal to the terminal device 101, and the terminal device 101 is configured to receive the downlink signal from the network device 102. The downlink signal may be downlink control information, and the transmission of the downlink signal may be performed via a physical downlink control channel (PDCCH). Alternatively, the downlink signal may be downlink data, and the transmission of the downlink signal may be performed through a physical downlink share channel (PDSCH).

[0146] A terminal device can be referred to as a user equipment (UE), mobile station (MS), mobile terminal (MT), etc., and is a device that provides voice and / or data connectivity to a user. The terminal device can be a mobile phone, handheld terminal, customer premise equipment (CPE), notebook computer, subscriber unit, cellular phone, smart phone, computing device, wireless data card, personal digital assistant (PDA) computer, tablet computer, a computer with a wireless transceiver function, wireless modem, tactile terminal device, handheld device, laptop computer, session initiation protocol (SIP) phone, cordless phone, or wireless local loop (WLL) station, machine type communication (MTC) terminal, wearable device (such as a smartwatch, smartband, or pedometer), in-vehicle terminal device (such as a terminal device for a car, bicycle, electric vehicle, airplane, ship, train, or high-speed train), extended reality (XR) terminal device, virtual reality (VR) terminal device, augmented reality (The (AR) terminal device can be a wireless terminal in industrial control, a smart home device (such as a refrigerator, TV, air conditioner, or electricity meter), a smart robot, a workshop device, a wireless terminal for self-driving, a wireless terminal for remote medical surgery, a wireless data card, a wireless terminal for a smart grid, a wireless terminal for transportation safety, a wireless terminal for a smart city, a wireless terminal for a smart home, a flight device (such as a smart robot, a hot air balloon, a drone, or an aircraft), or another device capable of accessing the network.,

[0147] In addition, the terminal device can alternatively be a terminal device of a future communication system (e.g., a 6th generation (6G) communication system), a terminal device of a future evolved public land mobile network (PLMN), etc. For example, the 6G network can further expand the form and functions of the terminal device of the 5th generation (5G) communication, and the 6G terminal device includes, but is not limited to, vehicles, cellular network terminal devices (integrating the functions of satellite terminals), drones, and the internet of things (IoT).

[0148] The aforementioned network device can be an access network device or a core network device.

[0149] An access network device is a radio access network (RAN) device or node that provides wireless access to terminal devices. It has a wireless transceiver function and is mainly responsible for functions such as radio resource management, quality of service (QoS) flow management, and data compression and encryption on the air interface side. The access network device can include various forms of base stations, such as macro base stations, micro base stations (also called small cells), pico base stations, small cells, relay stations, access point satellites, and balloon stations. The access network device may further include an evolved NodeB (eNB or eNodeB) in Long Term Evolution (LTE). The access network device may further include a next generation NodeB (gNB) or a transmitting and receiving point (TRP) in a 5G network. The access network device may further include a base station evolved after the 3rd Generation Partnership Project (3GPP (registered trademark)), or a base station of a future evolved PLMN, a broadband network gateway (BNG), a 3GPP (registered trademark) aggregation switch or a non-3GPP (registered trademark) access device, an access point (AP), a transmitting point (TP), a mobile switching center, or something similar in a Wi-Fi system. Alternatively, it may be a device that undertakes the base station function in device-to-device (D2D), vehicle-to-everything (V2X), or machine-to-machine (M2M) communication.

[0150] A core network device is a device of a core network (CN) that provides service support to terminal devices, and is mainly responsible for providing functions such as registration, call connection, charging, mobility management, as well as user connection, user management, and service bearer completion, data processing, and routing. The core network device can support different devices in different communication systems. For example, in a 4th generation (4G) communication system, it can support one or more such as a mobility management entity (MME), a serving gateway (S-GW). As another example, in a 5G communication system, the core network device can support one or more network elements such as an access and mobility management function (AMF) network element, a session management function (SMF) network element, and a user plane function (UPF) network element. In a next-generation communication system or a future communication system, the core network device may be one or more network elements, devices, or entities that provide service support to terminal devices.

[0151] It should be noted that the network architecture shown in FIG. 1 is not limited to only including the terminal device 101 and the network device 102 shown in the figure, and may further include other terminal devices and network devices not shown in the figure. In this application, details are not listed in this specification.

[0152] The foregoing network architecture can be applied to a 5G system. For example, the system architecture of a 5G system can be shown in FIG. 2. The foregoing network architecture can also be applied to an LTE system. For example, the system architecture of an LTE system can be shown in FIG. 3. The foregoing network architecture may be applied to a stand-alone deployment (i.e., stand-alone networking) 5G system or LTE system, or a non-stand-alone deployment (i.e., non-stand-alone networking) 5G system or LTE system, such as a dual connectivity (DC) scenario, a carrier aggregation (CA) scenario, etc. The DC scenario may include next generation (NG) EN-DC, NE-DC, and new radio (NR)-DC. The E in EN and NE represents evolved universal mobile telecommunications system (UMTS) terrestrial radio access network (E-UTRAN), i.e., a 4G radio access network, and N represents NR. For example, the diagram of the NE-DC scenario can be shown in FIG. 4. For example, the diagram of the CA scenario can be shown in FIG. 5.

[0153] The foregoing network architecture can be applied to communication systems such as a narrow band-internet of things (NB-IoT) system, a global system for mobile communications (GSM) system, an enhanced data rate for GSM evolution (EDGE) system, a wideband code division multiple access (WCDMA (registered trademark)) system, a code division multiple access 2000 (CDMA2000) system, a time division-synchronization code division multiple access (TD-SCDMA) system, and a 6G system evolved after 5G.

[0154] In the following, to better understand the embodiments of the present application, the related technologies in the embodiments of the present application will be first described.

[0155] 1. RRC state In 5G NR, a terminal device has three RRC states, namely, the RRC connected state, the RRC idle state, and the RRC inactive state. In the RRC connected state, an RRC connection is established between the terminal device and the access network device, and signaling and data transmission can be performed between the terminal device and the access network device. When there is no need to perform data transmission between the terminal device and the access network device, the access network device can release the terminal device to the RRC idle state. In the RRC idle state, there is no RRC connection between the access network device and the terminal device. In this case, there is no data transmission or RRC signaling connection between the terminal device and the access network device. In NR, the RRC inactive state is introduced. A terminal device in the RRC inactive state generally stops data transmission (the terminal can also perform small packet transmission, etc. in the RRC inactive state), but the access network device still maintains the context information of the terminal device. The advantage of introducing the RRC inactive state is that compared with a terminal device in the RRC idle state, since the access network device in the RRC inactive state still holds the context information of the terminal device, the RRC connection state can be restored more quickly. When a service arrives, the service transmission delay can be reduced. In addition, compared with a terminal device in the RRC connected state, a terminal device in the RRC inactive state has lower power consumption (which may be the same as in the RRC idle state). Therefore, this also helps to save the energy of the terminal device.

[0156] The access network device may release the terminal device to the RRC idle state or the RRC inactive state by sending an RRC Release message to the terminal device. When the RRC Release message received by the terminal device includes a suspend configuration (suspendConfig), the terminal device enters the RRC inactive state and executes a cell selection procedure. When the RRC Release message received by the terminal device does not include suspendConfig, except for scenarios such as Internet Protocol (IP) Multimedia Subsystem (IMS) voice evolved packet system (EPS) fallback and inter-system cell reselection, the terminal device enters the RRC idle state and executes a cell selection procedure.

[0157] 2. Cell Selection and Cell Reselection Cell Selection When a terminal device in the RRC connected state receives an RRC Release message, the terminal device enters the RRC idle state or the RRC inactive state and performs cell selection to select a cell suitable for camping or an acceptable cell. The terminal device may determine whether a cell is suitable for access by using parameters such as cell received power and cell received quality based on a cell selection criterion (also called the S criterion). The conditions for meeting the S criterion are as follows. S rxlev > 0 and S qual > 0

[0158] S rxlev is the cell selection RX level value in decibels (dB), and S qual is the cell selection quality value in dB. Srxlev and S qual can be expressed as follows. S rxlev = Q rxlevmeas - (Q rxlevmin + Q rxlevminoffset ) - P compensation - Qoffset temp S qual = Q qualmeas - (Q qualmin + Q qualminoffset ) - Qoffset temp

[0159] Q rxlevmeas is the measured cell received power value, Q rxlevmin is the minimum received power value required by the cell, Q rxlevminoffset is the offset value of Q rxlevmin and P compensation is the power compensation value, Qoffset temp is the offset value applied to the cell, Q qualmeas is the measured cell quality value, Q qualmin is the minimum quality value required by the cell, Q qualminoffset is the offset value of Q qualmin and is.

[0160] When performing cell selection, the UE can execute one of the following two processes.

[0161] The first process: Initial cell selection (when the terminal device does not have prior information on radio frequency (RF) channels and NR frequencies)

[0162] The terminal device scans all RF channels in the NR frequency band based on the capabilities of the terminal device. At each frequency other than the shared spectrum, the terminal device only needs to search for the cell with the strongest signal. When a suitable cell (i.e., a cell that meets the S criterion) is found, the terminal device selects that cell.

[0163] Second Process: Selecting a cell by using the stored information

[0164] In this process, the frequency information stored in the terminal device needs to be used. The frequency information is from previously received measurement control information or previously detected cell parameter information. Optionally, the frequency information may further need to be from previously received information regarding cell parameters. When a suitable cell (i.e., a cell that meets the S criterion) is found, the terminal device selects that cell. If no suitable cell is found, the initial cell selection procedure may be started.

[0165] After performing cell selection, the terminal device starts the system message acquisition procedure.

[0166] Cell reselection A terminal device in the RRC idle / inactive state measures the signal quality of the serving cell and adjacent cells. If the signal quality of the serving cell is worse but the signal quality of an adjacent cell is better, the terminal device actively reselects a cell with a higher priority or better signal quality as the serving cell. This process is called cell reselection. The cell reselection procedure consists of three phases, namely, starting neighbor cell measurement (a step of determining whether to start neighbor cell measurement based on the measurement start condition), reselection evaluation and decision (a step of determining whether the signal quality of a neighboring cell meets the cell reselection criterion, performing cell reselection if the signal quality meets the criterion, and camping on the current cell if the signal quality does not meet the criterion), and performing cell reselection (a step of receiving the system message of the target cell and camping on the new cell if the target cell has no access restriction). The following provides separate explanations.

[0167] Phase 1: Starting neighbor cell measurement Based on the measurement start condition, it may be determined whether to start adjacent cell measurement. When the measurement start condition is satisfied, the terminal device may start measuring the cell quality of the corresponding adjacent cell. Based on the reselection priority of the adjacent cell (or the priority of the frequency of the adjacent cell) and the cell quality of the serving cell, it may be determined whether the adjacent cell satisfies the measurement start condition. It should be understood that the adjacent cell is a cell adjacent to the serving cell or the broadcast cell.

[0168] When the reselection priority of the adjacent cell is higher than the reselection priority of the serving cell, adjacent cell measurement can be started unconditionally. In other words, adjacent cell measurement is directly started. When the reselection priority of the adjacent cell is less than or equal to the reselection priority of the serving cell, the cell quality of the serving cell can be measured first, and then the cell quality of the serving cell can be compared with the cell quality threshold value distributed by the network. When the cell quality of the serving cell is greater than or equal to the cell quality threshold value, adjacent cell measurement may not be started. When the cell quality of the serving cell is less than the cell quality threshold value, adjacent cell measurement can be started.

[0169] Phase 2: Reselection Evaluation Decision After the adjacent cell measurement is completed, the terminal device may start evaluating whether to perform cell reselection for the adjacent cell. The reselection evaluation decision varies depending on the reselection priority of the adjacent cell.

[0170] For an adjacent cell with a high reselection priority, in other words, an adjacent cell whose reselection priority is higher than the reselection priority of the serving cell, when the terminal device camps on the current serving cell for more than 1 second and the duration for which the cell quality of the adjacent cell satisfies a specific threshold exceeds a specific duration, cell reselection to the adjacent cell with a high reselection priority can be performed. During the reselection of a cell with a high reselection priority, if multiple cells with the same frequency reselection priority satisfy the reselection criteria, these cells can be sorted according to the cell reselection criteria (R criteria). This problem is converted into an in-frequency reselection problem, and the cell with the highest ranking is selected.

[0171] The R criterion is as follows, namely, the cell quality level R of the serving cell s and the cell quality level R of each cell adjacent to the serving cell (i.e., each adjacent cell) n are calculated. Then, the serving cell and the adjacent cells of the serving cell can be sorted based on the cell quality level, and a cell with the highest quality level or a quality level close to the highest quality level can be selected. Finally, among the selected cells, a cell with the maximum number of beams whose beam signal quality meets the requirements can be selected as the best cell. In addition, a cell may be said to meet the cell reselection criterion. R s and R n can be expressed as follows. R s =Q meas,s +Q hyst -Qoffset temp R n =Q meas,n +Qoffset-Qoffset temp

[0172] Q meas,s is the measured received power value of the serving cell, Q hyst is the cell reselection hysteresis value, Qoffset temp is an additional offset for cell selection and reselection, which is temporarily used when the RRC connection is not established, Q meas,n is the measured received power value of the adjacent cell, and Qoffset is the offset between the serving cell and the adjacent cell.

[0173] For adjacent cells with equal (i.e., the same) reselection priorities, in other words, for adjacent cells whose reselection priority is equal to the reselection priority of the serving cell, cell reselection can be performed according to the R criterion. Specifically, the cell signal quality levels of each adjacent cell that meets the cell selection criteria and the current serving cell are calculated. Next, based on the cell signal quality level sorting, the cell with the highest cell signal quality level is selected, or the cell with a signal quality level close to the highest cell signal quality level within a specific range is selected under multi-beam operation, and the cell with the maximum number of beams whose beam signal quality meets the requirements is selected as the best cell from these cells. If the best cell continuously meets the cell reselection criteria within a specific duration interval and the terminal device camps on the current serving cell for more than 1 second, the terminal device starts cell reselection to an adjacent cell.

[0174] For adjacent cells with a low reselection priority, in other words, for adjacent cells whose reselection priority is lower than the reselection priority of the serving cell, when the terminal device camps on the serving cell for more than 1 second, the cell quality of the serving cell is lower than a specific threshold, and the duration for which the cell quality of the adjacent cell with a low reselection priority meets another specific threshold exceeds a specific duration, cell reselection to the adjacent cell with a low reselection priority is performed.

[0175] When multiple cells with different reselection priorities meet the cell reselection criteria, cell reselection for the frequency with a higher reselection priority should precede cell reselection for the frequency with a lower reselection priority. In other words, the terminal device preferentially reselects cells of the frequency with a higher reselection priority.

[0176] The third phase: Perform cell reselection After completing the adjacent cell measurement and determining that there is an adjacent cell that meets the cell reselection conditions, the terminal device may start to attempt to camp on the new cell. The terminal device needs to receive system messages from the target adjacent cell, and then may determine whether the camping conditions of the adjacent cell are met based on the system messages. The determining step may include steps such as determining whether the target neighboring cell permits access by the terminal device. When the terminal device determines that the camping conditions of the target adjacent cell (including that the target adjacent cell prohibits access by the terminal device) are not met, the terminal device may exclude the target adjacent cell from being a candidate cell for 300 seconds (or up to 300 seconds). When the terminal device determines that the camping conditions of the target adjacent cell (including that the target adjacent cell permits access by the terminal device) are met, the terminal device may camp on the target adjacent cell.

[0177] Cell reselection priority is related to the frequency of the cell. Cells of the same frequency with the same radio access technology (RAT) have the same cell reselection priority, and cells of different frequencies may have the same cell reselection priority or different cell reselection priorities. Specifically, in-cell neighboring cells have the same cell priority. Inter-frequency cells are classified into high-priority adjacent cells, same-priority adjacent cells, and low-priority adjacent cells. The network may configure frequency priorities in the cell reselection process. The cell reselection priority may be sent to the terminal device by using system messages (cell-specific cell reselection), or may be sent to the terminal device by using dedicated signaling (for example, RRC Release message).

[0178] 3. MBS Broadcast A broadcast communication service is a communication service that provides the same service and the same specific content data to all terminal devices in a broadcast coverage area. In other words, all terminal devices in the broadcast coverage area can receive the data. In NR MBS, broadcast supports reception in the RRC idle state, RRC inactive state, and RRC connected state. Broadcast uses a point-to-multipoint (PTM) transmission mode. Specifically, one access network device can transmit one MBS data packet to multiple terminal devices through the air interface, and the terminal devices can decode the downlink data of the broadcast session scheduled by the access network device by using a common radio network temporary identifier (RNTI), such as a group radio network temporary identifier (G-RNTI).

[0179] In NR MBS broadcast, a two-stage configuration is used. The access network device can broadcast the system information block (SIB) 20. The system information block 20 carries the MBS control channel (MCCH) configuration used for MBS broadcast, including the repetition period and offset of the MCCH, the duration of the MCCH window, the start slot of the MCCH window, and the MCCH modification period. The transmission of the MCCH message (or the information transmitted through the MCCH channel) is executed periodically and is executed in the MCCH transmission window configured based on the configured repetition period. The MCCH is configured per cell. In Rel-17, each cell has only one type of MCCH configuration.

[0180] The MCCH carries MBS broadcast configuration information, provides a list of MBS broadcast sessions provided by the cell for each provided MBS broadcast session, and provides, for example, an identifier (ID) of the broadcast session (temporary multicast group identifier (TMGI)) and a G-RNTI, and optionally provides, for example, a broadcast MRB configuration, a discontinuous reception (DRX) configuration of the MBS traffic channel (multicast traffic channel (MTCH)), and a list of neighboring cells that can provide the broadcast session.

[0181] When a terminal device is interested in receiving an MBS broadcast service, the terminal device needs to execute an MCCH information acquisition process. A terminal device interested in receiving an MBS broadcast service should apply the MCCH information acquisition process when it enters a cell that provides SIB 20 (for example, when the terminal device is powered on and after the terminal device has moved to another cell), and when it receives an MCCH change notification due to the start of a new MBS service.

[0182] 4. MBS Multicast In Rel-17, NR MBS multicast supports receiving the MBS multicast service only by a terminal device in the RRC connected state. In MBS multicast, point to point (PTP) transmission may be used, or PTM transmission may be used. Typical multicast service scenarios include, for example, public security and mission critical, internet protocol television (IPTV), and live video. A terminal device that receives the MBS multicast service can accept the MBS multicast service (or MBS session) only after performing the authentication procedure with the core network. Each MBS session is identified using a TMGI. On the air interface, the terminal device uses dedicated signaling (e.g., an RRC reconfiguration message) to receive a connected state multicast configuration, such as a multicast MRB configuration, delivered by the access network device. Each MBS multicast session can be associated with one or more multicast MRBs. The multicast MRB configuration includes TMGI information indicating the multicast session associated with the multicast MRB.

[0183] However, when the number of terminal devices receiving the MBS multicast service in a cell is excessively large, it may exceed the number of terminal devices that can be accommodated in the cell and are in the RRC connected state. Therefore, in Rel-18, it is proposed that support be provided for a terminal device to receive the MBS multicast service in the RRC inactive state in order to relieve network congestion. For example, when a terminal device has no unicast service and only has a multicast service, the network may release the terminal device to the RRC inactive state to receive the multicast service. This not only helps to relieve network congestion but also helps to conserve the energy of the terminal device.

[0184] The terminal device obtains the multicast configuration in the RRC inactive state in the following possible ways (but not limited to the following ways). That is, in one way similar to Rel-17 broadcast, the terminal device obtains the configuration of one or more multicast control channels by using the system message, and obtains the PTM configuration of the multicast in the RRC inactive state through the multicast control channel. The multicast control channel may be a specific logical channel and may be identified by using a specific logical channel ID. Other ways are similar to Rel-17 multicast. The terminal device obtains the RRC inactive state multicast configuration in the RRC connected state by using dedicated signaling (for example, by using the RRC reconfiguration message).

[0185] However, since the terminal device in the RRC inactive state cannot provide uplink feedback, in the case of a terminal device in the RRC inactive state with poor coverage, the multicast service performance (for example, the data packet decoding success rate) deteriorates. In order to guarantee the performance of receiving multicast in the RRC inactive state, it is proposed that the network releases only the multicast terminal devices with good coverage to the RRC inactive state to receive multicast.

[0186] When the terminal device receives an RRC Release message (including suspendConfig) delivered by the network to instruct it to enter the RRC inactive state, the terminal device enters the RRC inactive state and performs cell selection. When the terminal device selects another cell that meets the S criterion, the terminal device needs to reacquire the RRC inactive state multicast configuration of the cell and then receive the multicast service based on the multicast configuration of the cell. Reacquiring the RRC inactive multicast configuration of the cell and then receiving the multicast causes a temporary interruption in the reception of the multicast service, which in turn affects the continuity of the multicast service. In addition, when the serving cell of the terminal device has good coverage, unnecessary cell selection procedures performed by the terminal device increase the power consumption of the terminal device.

[0187] In view of this, one embodiment of the present application provides a communication method for a terminal device to receive a multicast service via the serving cell of a terminal device in the RRC connected state in the RRC idle state.

[0188] Based on the above-described network architecture, FIG. 6 is a schematic flowchart of a communication method according to an embodiment of the present application. As shown in FIG. 6, the communication method may include the following steps.

[0189] 601: The network device transmits first information to a first terminal device in the RRC connected state.

[0190] Correspondingly, the first terminal device receives the first information from the network device in the RRC connected state.

[0191] When there are a large number of terminal devices that perform RRC connection state communication with a network device, when accessing the cell where the terminal device is located and there are a large number of terminal devices in the RRC connection state, or when performing a multicast service in the RRC connection state and there are a large number of terminal devices in the cell where the terminal device is located, the network device may send first information to a first terminal device in the RRC connection state.

[0192] It should be understood that the first terminal device is the terminal device in the claims and the summary. In this specification, in order to distinguish a specific terminal device, the terminal device in the claims and the summary is referred to as the first terminal device.

[0193] The existence of a large number of terminal devices that perform RRC connection state communication with a network device may be understood as the number of terminal devices that perform RRC connection state communication with the network device being greater than a first threshold, or as the ratio of the number of terminal devices that perform RRC connection state communication with the network device to the number of terminal devices that can be accommodated by the network device in the RRC connection state being greater than a second threshold. The terminal device that performs RRC connection state communication with the network device may be understood as a terminal device that communicates with the network device and is in the RRC connection state, or as a terminal device that establishes an RRC connection with the network device.

[0194] Accessing the cell where the terminal device is located and the existence of a large number of terminal devices in the RRC connection state may be understood as accessing the cell where the terminal device is located and the number of terminal devices in the RRC connection state being greater than a third threshold, or as the ratio of the number of terminal devices in the RRC connection state to the number of terminal devices that can be accommodated in the cell being greater than a fourth threshold when accessing the cell where the terminal device is located.

[0195] Performing a multicast service in the RRC connected state and having a large number of terminal devices in the cell where the terminal device is located may be understood as performing a multicast service in the RRC connected state and having the number of terminal devices in the cell where the terminal device is located greater than a fifth threshold, or performing a multicast service in the RRC connected state and having the ratio of the number of terminal devices in the cell where the terminal device is located to the number of terminal devices that can be accommodated in the cell in the RRC connected state greater than a sixth threshold.

[0196] It should be understood that the multicast service may sometimes be referred to as a multicast session. The multicast service in this specification may be an MBS multicast service or another multicast service. This is not limited in this specification.

[0197] The first terminal device is understood to be a terminal device that establishes an RRC connection with a network device, that is, a terminal device that communicates with the network device and is in the RRC connected state. The first terminal device can be any terminal device that establishes an RRC connection to the network device. This indicates that, in order to relieve network congestion, the network device may enable one or more terminal devices in the RRC idle state to receive a multicast service. Alternatively, the first terminal device may be a terminal device that establishes an RRC connection with the network device and has good coverage. This indicates that, in order to relieve network congestion, the network device may enable one or more terminal devices with good coverage in the RRC idle state to receive a multicast service.

[0198] The first information instructs the first terminal device to receive a multicast service in an RRC disconnected state. The RRC disconnected state may be an RRC idle state, an RRC inactive state, or both an RRC idle state and an RRC inactive state. The first information may be carried in an RRC release message. Specifically, the first information is transmitted to the first terminal device by using the RRC release message. In other words, the network device transmits an RRC release message to the first terminal device, and the RRC release message includes the first information. Alternatively, the first information may be carried in an RRC reconfiguration message. Alternatively, the first information may be carried in another message or other signaling. This is not limited in this specification. The first information may be configuration information for configuring the first terminal device to receive a multicast service in an RRC disconnected state. The configuration information may include a multicast MRB configuration. The first information may also be other information. This is not limited in this specification.

[0199] Instructing the first terminal device to receive a multicast service in an RRC disconnected state may be understood as (or replaced by) indicating that the multicast service configuration of the first terminal device is used in the RRC disconnected state, or indicating that the multicast service of the first terminal device is in an active state or the multicast service is not released, or indicating that the purpose of the first terminal device entering the RRC disconnected state is to receive a multicast service, or indicating that the multicast MRB of the first terminal device is not paused or released.

[0200] The first information can be indicated using 1 bit, a flag bit, or an instruction bit. When a network device needs to send the first information to a first terminal device, the network device may send a message or signaling including the bit, flag bit, or instruction bit corresponding to the first information to the first terminal device. Correspondingly, the first terminal device may receive a message or signaling including the bit, flag bit, or instruction bit corresponding to the first information. When the network device does not need to send the first information to the first terminal device, the network device does not send a message or signaling including the bit, flag bit, or instruction bit corresponding to the first information. Correspondingly, the first terminal device cannot receive a message or signaling including the bit, flag bit, or instruction bit corresponding to the first information.

[0201] Alternatively, the first information may be indicated by using 1 bit. For example, when the network device needs to send the first information to the first terminal device, the value of this bit is 1. When the network device does not need to send the first information to the first terminal device, the value of this bit is 0. The reverse is also true.

[0202]

[0203] The first information may instruct the first terminal device to receive multicast services in the RRC idle state, but does not instruct to receive a specific multicast service or a specific plurality of multicast services.

[0204] ​The multicast service that instructs to receive the first information may be an activated multicast service and / or a multicast service received by a terminal device.

[0205] Alternatively, the first information may indicate a specific multicast service or a specific plurality of multicast services received by a first terminal device in the RRC idle state. In this case, the first information may indicate an identifier of the multicast service or an identifier of the MRB. The multicast service herein is a multicast service that needs to be received by a first terminal device in the RRC idle state. The identifier of the multicast service may be the name of the multicast service, may be a TMGI corresponding to or associated with the multicast service, or may be an RNTI corresponding to or associated with the multicast service. The TMGI corresponding to or associated with the multicast service may be understood as a TMGI that identifies the multicast service. The RNTI corresponding to or associated with the multicast service may be understood as an RNTI used to scramble / descramble the multicast service. The MRB is an MRB associated with the multicast service.

[0206] For example, the first information may instruct the first terminal device to receive a first multicast service in the RRC idle state. Instructing the first terminal device to receive a first multicast service in the RRC idle state may be understood as indicating that the first multicast service configuration is used in the RRC idle state, or as indicating that the first multicast service is in an active state, or that the first multicast service has not been released, or as indicating that the purpose of the first terminal device entering the RRC idle state is to receive the first multicast service, or as indicating that the MRB corresponding to the first multicast service has not been interrupted or released (in this case, one multicast service may correspond to one or more multicast MRBs), or as indicating that the MRB associated with the first multicast service has not been interrupted or released.

[0207] 602: The first terminal device enters the RRC idle state.

[0208] To release the first terminal device to the RRC idle state, the network device may send an RRC release message to the first terminal device in the RRC connected state. Correspondingly, the first terminal device may receive an RRC release message from the network device in the RRC connected state, and then may enter the RRC idle state based on the RRC release message, that is, may switch from the RRC connected state to the RRC idle state.

[0209] When the network device needs to release the first terminal device to the RRC inactive state, the RRC release message includes suspendConfig. When the network device needs to release the first terminal device to the RRC idle state, the RRC release message does not include suspendConfig. Therefore, after the first terminal device receives the RRC release message, when the RRC release message does not include suspendConfig, the first terminal device may enter the RRC idle state based on the RRC release message. When the RRC release message includes suspendConfig, the first terminal device may enter the RRC inactive state based on the RRC release message.

[0210] When the first information is not carried in the RRC release message, the network device may first send the first information to the first terminal device, and then may send the RRC release message to the first terminal device. Correspondingly, the first terminal device may first receive the first information and then receive the RRC release message.

[0211] 603: The first terminal device receives the multicast service in the RRC disconnected state via the first cell.

[0212] After entering the RRC disconnected state, the first terminal device may receive the multicast service in the RRC disconnected state via the first cell, that is, may receive the multicast service in the RRC disconnected state via the first cell based on the first information.

[0213] The first cell is the serving cell of the first terminal device in the RRC connected state. The serving cell may be a primary cell (PCell) or a secondary cell (Scell). The serving cell of the first terminal device in the RRC connected state may be understood as the serving cell before entering the RRC idle state, may be understood as the serving cell in the RRC connected state before entering the RRC idle state, or may be understood as the cell where the first terminal device is located when the first terminal device receives an RRC release message. The first terminal device may receive a multicast service in the RRC connected state via the first cell, may not start receiving a multicast service in the RRC connected state, or may not receive a multicast service in the RRC connected state via the first cell.

[0214] When the first terminal device receives a multicast service in the RRC connected state via the first cell, the first cell may be the PCell of the first terminal device in the RRC connected state or the SCell of the first terminal device in the RRC connected state. When the first terminal device does not start receiving a multicast service in the RRC connected state or does not receive a multicast service in the RRC connected state via the first cell, the first cell is the PCell of the first terminal device in the RRC connected state.

[0215] For example, when a first terminal device receives a first multicast service in an RRC connected state via a first secondary cell, after the first terminal device enters the RRC idle state from the RRC connected state, the first terminal device camps on the first secondary cell. After entering the RRC idle state, the first terminal device does not need to re-acquire the RRC idle state multicast configuration of the first secondary cell, and the configuration for receiving the first multicast service in the first secondary cell in the RRC connected state can be used to receive the first multicast service in the RRC idle state. Thereby, the first terminal device can ensure the continuity of receiving the first multicast service in the first secondary cell.

[0216] When the first terminal device enters the RRC idle state from the RRC connected state, the first terminal device may not perform cell selection. It may be understood that the first terminal device skips the step of performing cell selection when the first terminal device enters the RRC idle state from the RRC connected state, or it may be understood that after the first terminal device changes from the RRC connected state to the RRC idle state, the terminal device skips the step of performing cell selection.

[0217] The first terminal device skipping the step of performing cell selection can be understood as the first terminal device not evaluating the cell signal quality according to the cell selection criteria and continuing to camp on the first cell. However, after entering the RRC idle state, to ensure the mobility of the first terminal device in the RRC idle state, the first terminal device still performs cell reselection and performs cell reselection measurement, evaluation, and execution according to the cell reselection criteria.

[0218] Skipping the step of the first terminal device performing cell selection may also be understood as the camped cell being the first cell when the first cell meets the camp conditions. Meeting the camp conditions may include meeting the S criteria for cell camping. In some cases, the first terminal device may first determine whether the first cell meets the camp conditions. When the first cell meets the camp conditions, the first terminal device skips the step of performing cell selection and directly determines the first cell as the camped cell. When the first cell does not meet the camp conditions, the first terminal device may perform cell selection. In this specification, the process of determining whether the first cell meets the camp conditions does not belong to the cell selection process. In another case, the first terminal device preferentially selects the first cell when performing cell selection. Specifically, after entering the RRC idle state, the first terminal device still performs cell selection once, but preferentially determines whether the first cell meets the camp conditions. When the first cell meets the camp conditions, the first terminal device determines that the camped cell is the first cell. When the first cell does not meet the camp conditions, the first terminal device searches for another cell that meets the S criteria to attempt to camp on.

[0219] Optionally, the communication method may further include the following steps.

[0220] 604: The first terminal device transmits second information to the network device.

[0221] Correspondingly, the network device receives the second information from the first terminal device.

[0222] When the terminal device does not support multicast services in the RRC idle state, the network device sends an RRC release message to the terminal device for cell congestion, instructing the terminal device to enter the RRC idle state to receive multicast services. The terminal device may perform cell selection to request to enter the RRC connected state to receive multicast services in an adjacent cell. The delay in re-establishing the RRC connection is long, resulting in the interruption of receiving multicast services. Alternatively, the terminal device may request to enter the RRC connected state again to receive multicast services from the network device of the serving cell where the terminal device is currently camped, and the network device may reject the RRC connection re-establishment request of the terminal device again. This causes unnecessary signaling overhead. To avoid the above problems, the first terminal device may send second information to the network device. The second information indicates that receiving multicast services in the RRC idle state is supported, in other words, indicates that the first terminal device supports receiving multicast services in the RRC idle state. The first terminal device may report the second information to the network device by using capability information. For example, the first terminal device may send UE Capability Information to the network device, and the UE Capability Information may include or carry the second information. Correspondingly, the network device may receive the UE Capability Information from the first terminal device and then obtain the second information from the UE Capability Information. Alternatively, the first terminal device may report the second information to the network device by using other information, messages, or signaling. This is not limited in this specification.

[0223] When all terminal devices support receiving a multicast service in the RRC idle state, the first terminal device may not need to send the second information to the network device. In other words, step 604 is not executed. This can avoid unnecessary information transmission and save transmission resources. Correspondingly, the network device may send the first information to any terminal device that establishes an RRC connection to the network device.

[0224] When some terminal devices support receiving a multicast service in the RRC idle state but some do not, in order to avoid the case where the network device sends the first information to a terminal device that does not support receiving a multicast service in the RRC idle state, only the terminal devices that support receiving a multicast service in the RRC idle state may send the second information to the network device. In this case, the first terminal device may send the second information to the network device. Correspondingly, the network device may send the first information to the first terminal device based on the second information. The network device may send the first information to the first terminal device based on the second information.

[0225] Alternatively, a terminal device that supports receiving a multicast service in the RRC idle state may send the second information to the network device, and a terminal device that does not support receiving a multicast service in the RRC idle state may send the fifth information to the network device. The fifth information indicates that receiving a multicast service in the RRC idle state is not supported. The network device may determine a specific terminal device to which the first information is to be sent based on the second information and the fifth information.

[0226] Optionally, the communication method may further include the following steps.

[0227] 605: The network device transmits the first configuration information to the first terminal device.

[0228] Correspondingly, the first terminal device receives the first configuration information from the network device.

[0229] The first configuration information can be used to configure the first terminal device to receive multicast services in the RRC idle state. The first configuration information may be carried in an RRC reconfiguration message, or may be carried in another message or other signaling.

[0230] When the network device needs the first terminal device to receive multicast services in the RRC idle state, the network device may transmit the first configuration information to the first terminal device, and as a result, the first terminal device can receive multicast services in the RRC idle state based on the first configuration information. Correspondingly, step 603 may be replaced with the first terminal device receiving multicast services in the RRC idle state based on the first configuration information via the first cell.

[0231] The first configuration information may include a multicast MRB configuration, a multicast common frequency resource (CFR) configuration, etc. The multicast MRB configuration is used to configure the MRBs for carrying multicast services, and the CFR configuration is used to configure the frequency resources for multicast services. The first configuration information may be the configuration information of one or more multicast services.

[0232] The first configuration information may be further used to configure the terminal device to receive multicast services in the RRC connected state. In other words, the network device may send a set of multicast service configurations for the same multicast service, and the set of multicast service configurations may be used in both the RRC connected state and the RRC idle state. In other words, in the RRC connected state and the RRC idle state, there is different configuration information for the same multicast service, that is, configuration information 1 in the RRC connected state and configuration information 2 in the RRC idle state. The fact that the RRC connected state and the RRC idle state have different configuration information may be understood as that some of the multicast configuration parameters are the same and some of the multicast configuration parameters are different. For example, the first configuration information may include a group of configuration parameters, and the different configuration parameters between the RRC idle state and the RRC connected state are only part of the configuration parameters of the group of configuration parameters.

[0233] When the first configuration information is used only to configure the first terminal device to receive multicast services in the RRC idle state, the network device may send the first configuration information to the first terminal device in the RRC connected state or the RRC idle state. When the first configuration information is used to configure the first terminal device to receive multicast services in both the RRC connected state and the RRC idle state, the network device may send the first configuration information to the first terminal device in the RRC connected state.

[0234] The terminal device can be learned to be able to obtain a multicast configuration in the RRC idle state by using dedicated signaling in the RRC connected state. In this way, when the terminal device remains camped on the current cell even after entering the RRC idle state, the terminal device does not need to reacquire the multicast configuration in the RRC idle state in order to improve the efficiency of receiving the multicast service. When the multicast service required to be received by the terminal device in the RRC connected state is activated, or when the terminal device has already started receiving the multicast service in the RRC connected state, the terminal device can obtain the configuration information of the multicast service in the RRC idle state in the RRC connected state. As a result, after entering the RRC idle state from the RRC connected state, the terminal device does not need to reacquire the configuration information of the multicast service in the RRC idle state in the serving cell, but receives the multicast service by using the configuration information received in the RRC connected state of the multicast service in the RRC idle state. Thereby, the continuity of the multicast service can be improved.

[0235] When all terminal devices support receiving the multicast service in the RRC idle state, the network device can directly transmit the first configuration information to the first terminal device.

[0236] When the terminal device does not support receiving a multicast service in the RRC idle state, the network device may send first configuration information to the terminal device based on the second information or the fifth information reported by the terminal device. The network device sends the first configuration information to the first terminal device only when the first terminal device supports receiving a multicast service in the RRC idle state, that is, the first terminal device reports the second information. Thereby, it is possible to avoid configuring the configuration information used for receiving a multicast service in the RRC idle state for a terminal device that does not support receiving a multicast service in the RRC idle state.

[0237] Optionally, the communication method may further include that the first terminal device obtains system information from the network device, and the system information is the system information required in the RRC idle state.

[0238] When the first terminal device enters the RRC idle state from the RRC connected state and skips the step of performing cell selection, the first cell needs to execute the system information acquisition procedure once to obtain the system information required by the first terminal device in the RRC idle state.

[0239] Generally, a terminal device enters from the RRC connected state to the RRC idle state and executes a system information acquisition procedure after performing cell selection. Since the first terminal device skips the step of performing cell selection, in order to avoid the case where the first terminal device cannot obtain the system message used when it is in the RRC idle state, the first terminal device needs to re-acquire the system message once in the first cell after entering the RRC idle state. If the first terminal device does not re-acquire the system message, the first terminal device cannot correctly perform cell reselection. For example, system messages related to cell reselection such as SIB 2 / SIB 3 / SIB 4 / SIB 5 are not broadcast by the network device before the first terminal device enters the RRC idle state. As a result, the first terminal device does not have the system information required in the RRC idle state.

[0240] Based on the network architecture described above, FIG. 7 is a schematic flowchart of another communication method according to an embodiment of the present application. As shown in FIG. 7, the communication method may include the following steps.

[0241] 701: The network device transmits third information to a first terminal device in the RRC connected state.

[0242] Correspondingly, the first terminal device receives the third information from the network device in the RRC connected state.

[0243] When the first terminal device needs to receive a multicast service in the RRC idle state, or when the first terminal device enters from the RRC connected state to the RRC idle state, performs cell selection, and another scenario or case where cell handover is not expected to occur, the network device may transmit the third information to the first terminal device in the RRC connected state.

[0244] The first terminal device is a terminal device that establishes an RRC connection with a network device, that is, a terminal device that communicates with the network device and is in the RRC connection state. The first terminal device may be any terminal device that establishes an RRC connection to the network device, or may be a terminal device that establishes an RRC connection to the network device and has good coverage.

[0245] The third piece of information instructs to skip the step of entering from the RRC connected state to the RRC idle state and performing cell selection. The RRC idle state may be the RRC idle state, or the RRC inactive state, or both the RRC idle state and the RRC inactive state. The third piece of information may be carried in an RRC release message, may be carried in an RRC reconfiguration message, or may be carried in another message or other signaling.

[0246] When the network device determines that the first terminal device needs to skip the step of entering from the RRC connected state to the RRC idle state and performing cell selection when entering the RRC idle state, the network device may send the third piece of information to the first terminal device. When the network device determines that the first terminal device needs to perform cell selection when entering from the RRC connected state to the RRC idle state, the network device may not send the third piece of information to the first terminal device. For example, the third piece of information may be indicated by using 1 bit, a flag bit, or an indication bit. When the network device determines that the first terminal device needs to skip the step of entering from the RRC connected state to the RRC idle state and performing cell selection when entering the RRC idle state, the RRC release message or the RRC reconfiguration message may include 1 bit, a flag bit, or an indication bit. When the network device determines that the first terminal device needs to perform cell selection when entering from the RRC connected state to the RRC idle state, the RRC release message or the RRC reconfiguration message does not include 1 bit, a flag bit, or an indication bit.

[0247] In another case, when the network device needs to skip the step of the first terminal device entering the RRC idle state from the RRC connected state and performing cell selection, the network device may send the third information to the first terminal device. When the network device needs the first terminal device to enter the RRC idle state from the RRC connected state and perform cell selection, the network device may send the sixth information to the first terminal device. The sixth information instructs to enter the RRC idle state from the RRC connected state and perform cell selection. In other words, the network device may instruct the first terminal device to enter the RRC idle state from the RRC connected state and perform cell selection or skip the step of performing cell selection. For example, 1 bit may indicate the third information or the sixth information. When the network device needs to skip the step of the first terminal device entering the RRC idle state from the RRC connected state and performing cell selection, the value of this bit in the RRC release message or RRC reconfiguration message is 1, indicating that the network device sends the third information to the first terminal device. When the network device needs the first terminal device to enter the RRC idle state from the RRC connected state and perform cell selection, the value of this bit in the RRC release message or RRC reconfiguration message is 0, indicating that the network device sends the sixth information to the first terminal device.

[0248] 702: The first terminal device enters the RRC idle state.

[0249] To release the first terminal device to the RRC idle state, the network device may send an RRC release message to the first terminal device in the RRC connected state. Correspondingly, the first terminal device may receive the RRC release message from the network device in the RRC connected state and then enter the RRC idle state based on the RRC release message.

[0250] When the third information is not carried in the RRC release message, the network device may first send the third information to the first terminal device and then may send the RRC release message to the first terminal device. Correspondingly, the first terminal device may first receive the third information and then may receive the RRC release message.

[0251] The first terminal device enters from the RRC connected state to the RRC idle state and skips the step of performing cell selection. For a detailed description of skipping the step of performing cell selection by the first terminal device, refer to the related description in step 603. Details will not be described again in this specification.

[0252] In this embodiment, the terminal device enters from the RRC connected state to the RRC idle state and skips the step of performing cell selection. Thereby, when the terminal device changes from the RRC connected state to the RRC idle state and performs cell selection, interruption of receiving the multicast service can be avoided, the continuity of the multicast service can be improved, the power consumption of searching for a cell in the cell selection process can be reduced, and the power consumption of the terminal device can be reduced.

[0253] The communication method corresponding to FIG. 7 may be used alone or in combination with the communication method corresponding to FIG. 6. When FIGS. 6 and 7 are used in combination, when the network device transmits the third information or the sixth information to the first terminal device, instead of determining whether to perform cell selection based on the first information, the first terminal device determines whether to perform cell selection based on the third information or the sixth information. For example, when the RRC release message includes the first information and the third information, the first terminal device skips the step of performing cell selection. When the RRC release message includes the first information but does not include the third information, or includes the first information and the sixth information, the first terminal device performs cell selection. When the protocol stipulates that the third information instructs the terminal device to skip the step of performing cell selection, when the third information is not received, it can be learned that this means that the terminal device performs cell selection instead of skipping the step of performing cell selection based on the first information.

[0254] Based on the network architecture described above, FIG. 8 is a schematic flowchart of another communication method according to an embodiment of the present application. As shown in FIG. 8, the communication method may include the following steps.

[0255] 801: The network device transmits the fourth information indicating the frequency priority to the first terminal device in the RRC connected state.

[0256] Correspondingly, the first terminal device receives the fourth information from the network device indicating the frequency priority in the RRC connected state.

[0257] When a network device needs to release a first terminal device to the RRC idle state, the network device may send fourth information to the first terminal device that is in the RRC connected state. The first terminal device may be a terminal device that establishes an RRC connection with the network device, that is, any terminal device that communicates with the network device and is in the RRC connected state.

[0258] The fourth information indicates frequency priority. The network device may broadcast the fourth information to the first terminal device (for example, the fourth information is included in a system message, or the fourth information is included in an MCCH message), or may send the fourth information to the first terminal device by using an RRC release message.

[0259] The frequency priority is the priority of a frequency. The frequency in this specification is the frequency of a cell. The frequency of a cell is the operating frequency of the cell.

[0260] 802: When the first terminal device performs cell selection, it selects a camped cell in descending order of frequency priority.

[0261] To release the first terminal device to the RRC idle state, the network device may send an RRC release message to the first terminal device that is in the RRC connected state. Correspondingly, the first terminal device may receive the RRC release message from the network device in the RRC connected state, and then may enter the RRC idle state based on the RRC release message.

[0262] When the first information is not carried in the RRC release message, the network device may first send the fourth information to the first terminal device, and then may send the RRC release message to the first terminal device. Correspondingly, the first terminal device may first receive the fourth information, and then may receive the RRC release message.

[0263] When the first terminal device enters the RRC idle state from the RRC connected state and performs cell selection, the first terminal device may select a cell camped in descending order of frequency priority. The frequencies in the frequency priority may be arranged in descending order. Therefore, the first terminal device can preferentially determine whether there is a cell satisfying the S criterion in the cell corresponding to the highest frequency priority. If there is a cell satisfying the S criterion in the cell corresponding to the highest frequency priority, the first terminal device may select the cell satisfying the S criterion. Or if there is no cell satisfying the S criterion in the cell corresponding to the highest frequency priority, the first terminal device may continue to determine whether there is a cell satisfying the S criterion in the cell corresponding to the second frequency priority, and so on. For cells corresponding to the same frequency priority, the order in which the first terminal device performs cell selection may be determined randomly, may be determined based on the distance between the first terminal device and the cell, or may be determined in another manner. This is not limited in this specification.

[0264] Frequency priority may include one or more frequency lists. Frequencies in the same frequency list have the same priority, and frequencies in different frequency lists have different priorities. For example, frequency priority may include one high-priority frequency list, and one or more frequencies in the frequency list are regarded as high-priority, and other frequencies are regarded as low-priority. For example, frequency priority may include one high-priority frequency list and one low-priority frequency list. For example, the high-priority frequency list may be {Frequency 1, Frequency 2}. When performing cell selection, the terminal device may preferentially select cells corresponding to Frequency 1 and Frequency 2. For example, frequency priority may include one high-priority frequency list, one medium-priority frequency list, and one low-priority frequency list. The first terminal device may perform selection based on the high-priority frequency list, the medium-priority frequency list, and the low-priority frequency list. For example, frequency priority may include M frequency lists: 1, 2,..., and M. A higher number may correspond to a higher priority, or a higher number may correspond to a lower priority. M is an integer greater than or equal to 1. When M is greater than 1, the network device

Number

[0265] Frequency priority may also include one frequency list. Different frequencies in the frequency list may correspond to different priorities or the same priority. For example, the frequency list may be shown in Table 1 and Table 2.

[0266]

Table 1

[0267]

Table 2

[0268] N, A, and B are integers greater than or equal to 1.

[0269] The communication method corresponding to FIG. 8 may be used alone or in combination with the communication method corresponding to FIG. 6 and / or FIG. 7. In the case of combined use, the priority of the frequency corresponding to the first cell may be the highest priority in terms of frequency priority, and as a result, the first terminal device preferentially selects the first cell. Thereby, interruption of the multicast service can be avoided, and energy consumption of the first terminal device can be reduced.

[0270] In the case of combined use, the network device can concentrate the terminal devices that receive multicast in the RRC idle state on a specific frequency. For example, it can concentrate the terminal devices on the frequency / cell where the multicast service in the RRC idle state can be provided. In one aspect, this can avoid the case where the multicast is interrupted because the terminal device selects a cell that does not support the multicast service in the RRC idle state. The cells that do not support the multicast service in the RRC idle state may include cells that support the multicast service but only support the provision of the multicast service in the RRC connected state, or cells that cannot provide the multicast service. In the former case, after camping on the cell, the terminal device needs to trigger a request to establish an RRC connection to enter the RRC connected state to receive the multicast service, which causes an interruption of the multicast service. In the latter case, after camping on the cell, the terminal device also needs to trigger a request to establish an RRC connection. After entering the RRC connected state, the terminal device may trigger to establish a unicast PDU session with the multicast server to receive the multicast service. In another aspect, this can avoid the case where the terminal device performs blind cell selection to reduce the power consumption overhead of the terminal device. In yet another aspect, from the perspective of the network, this can also help reduce the network power consumption and the resource overhead and signaling overhead for the network to provide the multicast service in the RRC idle state. For example, the network can provide the multicast service in the RRC idle state only on a specific frequency / specific cell, and there is no need to provide the multicast service in the RRC idle state on another cell.

[0271] In another scenario, the network device may determine, for the corresponding requirements, that the priority of the frequency corresponding to the cell that meets the requirements is a higher priority.

[0272] It should be understood that the same or corresponding information in the foregoing different embodiments or different locations may, in some cases, be cross-referenced to each other.

[0273] It should be understood that the functions executed by the network device in the foregoing communication method may also be executed by a module (e.g., a chip) of the network device, or by a logical module or software capable of implementing all or part of the functions of the network device. The functions executed by the terminal device may also be executed by a module (e.g., a chip) of the terminal device, or by a logical module or software capable of implementing all or part of the functions of the terminal device.

[0274] Based on the foregoing network architecture, FIG. 9 is a diagram of the structure of a communication device according to an embodiment of the present application. As shown in FIG. 9, the communication device may include a processing unit 901 and a transceiver unit 902.

[0275] In some cases, the communication device may be a terminal device, or a chip, a chip system, or a processor that supports the terminal device when implementing the method, or a logical module or software capable of implementing all or part of the functions of the terminal device. For a detailed description of the processing unit 901 and the transceiver unit 902, please refer to the description of the seventh aspect of the summary. For a more detailed description of the processing unit 901 and the transceiver unit 902, please directly refer to the related description of the first terminal device in the method embodiments shown in FIGS. 6 to 8. Details are not described herein.

[0276] In another case, the communication device may be a network device, or a chip, chip system, or processor that supports a network device when implementing the method, or a logical module or software that can implement all or part of the functions of the network device. For a detailed description of the processing unit 901 and the transceiver unit 902, please refer to the description of the eighth aspect of the overview. For a more detailed description of the processing unit 901 and the transceiver unit 902, please directly refer to the related description of the network device in the method embodiments shown in FIGS. 6 to 8. Details are not described herein.

[0277] In yet another case, the communication device may be a terminal device, or a chip, chip system, or processor that supports a terminal device when implementing the method, or a logical module or software that can implement all or part of the functions of the terminal device. For a detailed description of the processing unit 901 and the transceiver unit 902, please refer to the description of the ninth aspect of the overview. For a more detailed description of the processing unit 901 and the transceiver unit 902, please directly refer to the related description of the first terminal device in the method embodiments shown in FIG. 7. Details are not described herein.

[0278] In yet another case, the communication device may be a network device, or a chip, chip system, or processor that supports a network device when implementing the method, or a logical module or software that can implement all or part of the functions of the network device. For a detailed description of the processing unit 901 and the transceiver unit 902, please refer to the description of the tenth aspect of the overview. For a more detailed description of the processing unit 901 and the transceiver unit 902, please directly refer to the related description of the network device in the method embodiments shown in FIG. 7. Details are not described herein.

[0279] In yet another case, the communication device may be a terminal device, or a chip, chip system, or processor that supports the terminal device when implementing the method, or a logic module or software capable of implementing all or part of the functions of the terminal device. For a detailed description of the processing unit 901 and the transceiver unit 902, refer to the description of the 11th aspect of the overview. For a more detailed description of the processing unit 901 and the transceiver unit 902, directly refer to the related description of the first terminal device of the method embodiment shown in FIG. 8. Details are not described herein.

[0280] In yet another case, the communication device may be a network device, or a chip, chip system, or processor that supports the network device when implementing the method, or a logic module or software capable of implementing all or part of the functions of the network device. For a detailed description of the processing unit 901 and the transceiver unit 902, refer to the description of the 12th aspect of the overview. For a more detailed description of the processing unit 901 and the transceiver unit 902, directly refer to the related description of the network device of the method embodiment shown in FIG. 8. Details are not described herein.

[0281] Based on the foregoing network architecture, FIG. 10 is a diagram of the structure of another communication device according to an embodiment of the present application. As shown in FIG. 10, the communication device may include a processor 1001, a memory 1002, a transceiver 1003, and a bus 1004. The memory 1002 may exist independently or may be connected to the processor 1001 through the bus 1004. Alternatively, the memory 1002 may be integrated with the processor 1001. The bus 1004 is configured to implement connections among these components. In some cases, as shown in FIG. 10, the transceiver 1003 may include a transmitter machine 10031, a receiver machine 10032, and an antenna 10033. In other cases, the transceiver 1003 may include a transmitter (i.e., an output interface) and a receiver (i.e., an input interface). The transmitter may include a transmitter machine and an antenna, and the receiver may include a receiver machine and an antenna.

[0282] The communication device may be a terminal device or a module of a terminal device. When the computer program instructions stored in the memory 1002 are executed, the processor 1001 is configured to execute the operations executed by the processing unit 901 in the foregoing embodiment, and the transceiver 1003 is configured to execute the operations executed by the transceiver unit 902 in the foregoing embodiment. The communication device may be further configured to execute various methods executed by the first terminal device in the method embodiments of FIGS. 6 to 8. Details will not be described again.

[0283] The communication device may be a network device or a module of a network device. When the computer program instructions stored in the memory 1002 are executed, the processor 1001 is configured to execute the operations performed by the processing unit 901 in the foregoing embodiments, and the transceiver 1003 is configured to execute the operations performed by the transceiver unit 902 in the foregoing embodiments. The communication device may be further configured to execute various methods executed by the network device in the method embodiments of FIGS. 6 to 8. Details will not be described again.

[0284] Based on the foregoing network architecture, FIG. 11 is a diagram of the structure of yet another communication device according to an embodiment of the present application. As shown in FIG. 11, the communication device may include an input interface 1101, a logic circuit 1102, and an output interface 1103. The input interface 1101 is connected to the output interface 1103 through the logic circuit 1102. The input interface 1101 is configured to receive information from another communication device, and the output interface 1103 is configured to output, schedule, or transmit information to another communication device. The logic circuit 1102 is configured to perform operations other than the operations of the input interface 1101 and the output interface 1103, for example, to perform the functions implemented by the processor 1001 in the above embodiments. The communication device may be a terminal device (or a module of a terminal device) or a network device (or a module of a network device). For a more detailed description of the input interface 1101, the logic circuit 1102, and the output interface 1103, please directly refer to the relevant descriptions of the first terminal device and the network device in the foregoing method embodiments. Details will not be described in this specification.

[0285] An embodiment of the present application further discloses a computer-readable storage medium storing instructions. When the instructions are executed, the methods in the foregoing method embodiments are executed.

[0286] One embodiment of the present application further discloses a computer program product including instructions. When the instructions are executed, the method in the foregoing method embodiment is executed.

[0287] One embodiment of the present application further discloses a communication system. The communication system may include a network device and a terminal device. For specific descriptions, please refer to the communication methods shown in FIGS. 6 to 8.

[0288] In the foregoing specific implementation forms, the object, technical solution, and beneficial effects of the present application are further described in detail. It should be understood that the foregoing description is only a specific implementation form of the present application and is not intended to limit the protection scope of the present application. Any modifications, equivalent replacements, improvements, etc. made based on the technical solution of the present application shall fall within the protection scope of the present application.

Description of Reference Numerals

[0289] 101 Terminal device 102 Network device 901 Processing unit 902 Transceiver unit 1001 Processor 1002 Memory 1003 Transceiver 10031 Transmitter machine 10032 Receiver machine 10033 Antenna 1004 Bus 1101 Input interface 1102 Logic circuit 1103 Output interface

Claims

1. A communication method, wherein the method is applied to a terminal device, receiving first information from a network device in a Radio Resource Control (RRC) connected state, the first information instructing the terminal device to receive a multicast service in an RRC idle state; entering the RRC idle state; receiving the multicast service in the RRC idle state via a first cell, the first cell being a serving cell of the terminal device in the RRC connected state. The method comprising the above steps.

2. The method according to claim 1, wherein the terminal device skips the step of entering from the RRC connected state to the RRC idle state and performing cell selection.

3. The step of skipping the step of performing cell selection includes that when the first cell meets the camping condition, the camped cell is the first cell. The method according to claim 2.

4. The first information is carried in an RRC release message, and the step of entering the RRC idle state includes entering the RRC idle state based on the RRC release message. The method according to any one of claims 1 to 3.

5. The method according to any one of claims 1 to 4, wherein the first information indicates an identifier of the multicast service or an identifier of a Multicast Broadcast Service Radio Bearer (MRB), and the MRB is an MRB associated with the multicast service.

6. The method further includes: receiving first configuration information from the network device, the first configuration information being used to configure the terminal device to receive the multicast service in the RRC idle state. The step of receiving the multicast service in the RRC idle state via the first cell includes receiving the multicast service in the RRC idle state via the first cell based on the first configuration information. The method according to any one of claims 1 to 5.

7. The method further includes: A step of transmitting second information to the network device, where the second information indicates that the step of receiving the multicast service in the RRC idle state is supported The method according to any one of claims 1 to 6, further comprising **Claim 8** A communication method, which is applied to a network device A step of transmitting first information to a terminal device in a Radio Resource Control (RRC) connected state, where the first information instructs the terminal device to receive a multicast service in the RRC idle state, the first information is used by the terminal device to receive the multicast service in the RRC idle state via a first cell, and the first cell is the cell camped by the terminal device in the RRC connected state The method comprising **Claim 9** The method according to claim 8, wherein the first information is further used by the terminal device to skip the step of entering from the RRC connected state to the RRC idle state and performing cell selection **Claim 10** The step of skipping the step of performing cell selection When the first cell meets the camping condition, the camped cell is the first cell The method according to claim 9, comprising **Claim 11** The method according to any one of claims 8 to 10, wherein the first information is carried in an RRC release message, and the RRC release message is used by the terminal device to enter the RRC idle state **Claim 12** The method according to any one of claims 8 to 11, wherein the first information indicates an identifier of the multicast service or an identifier of a Multicast Broadcast Service Radio Bearer (MRB), and the MRB is an MRB associated with the multicast service **Claim 13** The method A step of transmitting first configuration information to the terminal device, where the first configuration information is used to configure the terminal device to receive the multicast service in the RRC idle state The method according to any one of claims 8 to 12, further comprising **Claim 14** The method A step of receiving second information from the terminal device, where the second information indicates that the step of receiving the multicast service in the RRC disconnected state is supported The method according to any one of claims 8 to 13, further comprising.

15. A communication device, where the device is used in a terminal device A transceiver unit configured to receive first information from a network device in a radio resource control (RRC) connected state, where the first information instructs the terminal device to receive a multicast service in the RRC disconnected state A processing unit configured to enter the RRC disconnected state Including The processing unit is further configured to receive the multicast service in the RRC disconnected state via a first cell, where the first cell is a serving cell of the terminal device in the RRC connected state Device.

16. The device according to claim 15, where the terminal device enters the RRC disconnected state from the RRC connected state and skips the step of performing cell selection

17. The step of skipping the step of performing cell selection is When the first cell meets the camping condition, the camped cell is the first cell The device according to claim 16, including.

18. The first information is carried in an RRC release message, and the processing unit Enters the RRC disconnected state based on the RRC release message The device according to any one of claims 15 to 17, particularly configured as such.

19. The first information indicates an identifier of the multicast service or an identifier of a multicast broadcast service radio bearer (MRB), and the MRB is an MRB associated with the multicast service. The device according to any one of claims 15 to 18

20. The transceiver unit is further configured to receive first configuration information from the network device, and the first configuration information is used to configure the terminal device to receive the multicast service in the RRC disconnected state The processing unit receiving the multicast service in the RRC disconnected state via the first cell is Receiving the multicast service in the RRC idle state via the first cell based on the first configuration information The apparatus according to any one of claims 15 to 19, comprising the step of **Claim 21** The apparatus according to any one of claims 15 to 20, wherein the transceiver unit is further configured to transmit second information to the network device, and the second information indicates that the step of receiving the multicast service in the RRC idle state is supported. **Claim 22** A communication device, wherein the device is used in a network device and comprises a processing unit and a transceiver unit, The transceiver unit is configured to transmit first information to a terminal device in a radio resource control (RRC) connected state under the control of the processing unit, the first information instructing the terminal device to receive a multicast service in the RRC idle state, the first information being used by the terminal device to receive the multicast service in the RRC idle state via a first cell, and the first cell being a camped cell of the terminal device in the RRC connected state. Device **Claim 23** The apparatus according to claim 22, wherein the first information is further used by the terminal device to skip the step of entering from the RRC connected state to the RRC idle state and performing cell selection. **Claim 24** The apparatus according to claim 23, wherein the step of skipping the step of performing cell selection includes that when the first cell meets the camping condition, the camped cell is the first cell. **Claim 25** The apparatus according to any one of claims 22 to 24, wherein the first information is carried in an RRC release message, and the RRC release message is used by the terminal device to enter the RRC idle state. **Claim 26** The apparatus according to any one of claims 22 to 25, wherein the first information indicates an identifier of the multicast service or an identifier of a multicast broadcast service radio bearer (MRB), and the MRB is an MRB associated with the multicast service. **Claim 27** The transceiver unit is further configured to transmit first configuration information to the terminal device under the control of the processing unit, and the first configuration information is used to configure the terminal device to receive the multicast service in the RRC idle state. The apparatus according to any one of claims 22 to 26.

28. The transceiver unit is further configured to receive second information from the terminal device under the control of the processing unit, and the second information indicates that the step of receiving the multicast service in the RRC idle state is supported. The apparatus according to any one of claims 22 to 27.

29. A communication device comprising a processor and a memory, wherein the processor is coupled to the memory and the processor calls a computer program stored in the memory to implement the method according to any one of claims 1 to 14.

30. A computer-readable storage medium storing a computer program or computer instructions, and when the computer program or the computer instructions are executed by a processor, the method according to any one of claims 1 to 14 is implemented.

31. A computer program product comprising computer program code, and when the computer program code is executed by a processor, the method according to any one of claims 1 to 14 is implemented.

Images