Wireless communication method, communication device and communication system

Abstract

The invention provides a wireless communication method, a communication device and a communication system. In the method, after receiving the paging message, the first terminal equipment does not need to send an RRC recovery request message to the network side again if the first terminal equipment is in a small data transmission process at present, but can wait for the network side equipment to send the RRC recovery message, so that unnecessary energy consumption overhead can be saved, the processing complexity of the terminal equipment is reduced, and the signaling overhead is reduced.

Description

Wireless communication method, communication device and communication system

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This application claims priority to the Chinese patent application filed with the China Patent Office on August 9, 2022, with application number 202210952890.0 and application name “A Wireless Communication Method, Communication Device and Communication System”, the entire contents of which are incorporated by reference into this application. Technical Field

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

[0004] Currently, a terminal device has three radio resource control (RRC) states, namely, RRC connected state (RRC_connected), RRC idle state (RRC_idle), and RRC inactive state (RRC_inactive).

[0005] For a terminal device in the RRC Inactive state, to avoid increased energy consumption caused by entering the RRC Connected state when traffic is low, when the amount of data to be transmitted by the terminal device in the RRC Inactive state is lower than a preset threshold, the terminal device may not enter the RRC Connected state, but instead transmit data and / or signaling with the radio access network device in the RRC Inactive state. This process is called small data transmission.

[0006] Multicast communication means that the same service and the same data are provided to a specific group of terminal devices at the same time. Generally, the network side can send multicast services to terminal devices in the RRC connected state through a multicast session. When the network side has no multicast session data to send to the terminal device, the network side can allow the terminal device to enter the RRC idle state or the RRC inactive state to save energy consumption of the terminal device. When the multicast session is activated or the data of the multicast session arrives, the network side notifies the terminal devices in the RRC idle state or the RRC inactive state through the group notification mechanism. After receiving the group notification, the terminal device can re-establish a connection with the network side to receive the data of the multicast session. Once the terminal device leaves the multicast session, the terminal device can stop monitoring the group notification related to the multicast session.

[0007] In one scenario, after a multicast session is activated, the network pages a terminal device that has joined the multicast session and is in an RRC inactive state. This terminal device may or may not be in the process of transmitting small data. The specific actions the terminal device should perform remain to be determined.

[0008] Summary of the Invention

[0009] The embodiments of the present application provide a wireless communication method, a communication device, and a communication system to ensure that terminal devices save unnecessary energy consumption during small data transmission, reduce the processing complexity of the terminal devices, and reduce signaling overhead.

[0010] In a first aspect, an embodiment of the present application provides a wireless communication method, which can be executed by a first terminal device or a module (such as a chip) applied to the first terminal device. The method includes: the first terminal device receives a paging message, the paging message includes identification information of at least one multicast session, and the first terminal device is in an RRC inactive state; when a first condition is met, the first terminal device triggers an RRC connection recovery process; wherein the first condition includes: the at least one multicast session includes a multicast session joined by the first terminal device, and the first terminal device is not in a small data transmission process; or, the first condition includes: the paging message also includes identification information of at least one terminal device, the at least one multicast session includes a multicast session joined by the first terminal device, the terminal device is not in a small data transmission process, and the identification information of the at least one terminal device does not include the identification information of the first terminal device; the small data transmission is the transmission of data and / or signaling by the first terminal device in an RRC inactive state, the data volume of which is lower than a preset threshold.

[0011] In the above scheme, if at least one multicast session in the paging message sent by the network side includes a multicast session joined by the first terminal device, it indicates that the network side has multicast session data that needs to be sent to the first terminal device, and the first terminal device can request the network side to restore the RRC connection to receive the multicast session data. However, if the first terminal device is currently in a small data transmission process after receiving the paging message, it means that the first terminal device has already sent an RRC recovery request message to the network side before receiving the paging message, and there is an available data / signaling transmission path between the wireless access network device and the first terminal device. The wireless access network device is aware of the cell where the first terminal device resides. Therefore, if the network side needs to allow the first terminal device to enter the RRC connection state to receive the multicast session, it can send an RRC recovery message to the first terminal device through this transmission path. Therefore, after receiving the paging message, if the first terminal device is currently in the small data transmission process, it does not need to send the RRC recovery request message to the network side again, but can wait for the network side device to send the RRC recovery message. The RRC recovery message can be in response to the RRC recovery request message sent by the first terminal device when triggering small data transmission, thereby saving unnecessary energy consumption overhead, reducing the processing complexity of the terminal device, and reducing signaling overhead.

[0012] In a possible implementation method, the first terminal device triggers the RRC connection recovery process, including: the first terminal device sends an RRC recovery request message to the wireless access network device.

[0013] In one possible implementation method, when the second condition is met, the first terminal device determines not to trigger the RRC connection recovery process; wherein, the second condition includes: the at least one multicast session includes the multicast session joined by the first terminal device, and the first terminal device is in a small data transmission process.

[0014] In the above scheme, when the first terminal device is performing small data transmission, it indicates that the first terminal device has sent an RRC recovery request message to the wireless access network device, and there is an available data / signaling transmission path between the wireless access network device and the first terminal device. The wireless access network device is aware of the cell where the first terminal device resides. Therefore, after the first terminal device receives the paging message for notifying the activation of the multicast session, it does not need to trigger the RRC connection recovery process again, but waits for the wireless access network device to send an RRC recovery message to the first terminal device to make the first terminal device enter the RRC connection state, thereby saving unnecessary energy consumption overhead, reducing the processing complexity of the terminal device, and reducing signaling overhead.

[0015] In one possible implementation method, the first terminal device sends an indication message to the wireless access network device, which indicates that data and / or signaling have arrived on the wireless bearer for non-small data transmission, or that the at least one multicast session includes the multicast session joined by the first terminal device, or that the multicast session joined by the first terminal device has been activated.

[0016] In the above scheme, based on the indication information sent by the first terminal device, the wireless access network device can learn that the first terminal device has data or signaling arriving on the radio bearer for non-small data transmission, or learn that the first terminal device expects to enter the RRC connection state to receive the multicast session, which helps the wireless access network device determine whether to restore the RRC connection state for the first terminal device, thereby facilitating subsequent correct communication between the wireless access network device and the first terminal device. For example, if the first terminal device does not expect to enter the RRC connection state to receive the multicast session indicated in the paging message after receiving the paging message, or has already released the multicast session, the first terminal device may not send the indication information to the wireless access network device, and the wireless access network device does not need to allow the first terminal device to enter the RRC connection state.

[0017] In one possible implementation method, when the third condition is met, the first terminal device enters the RRC idle state and triggers the RRC connection establishment process; wherein, the third condition includes: the paging message also includes identification information of at least one terminal device, the at least one multicast session includes the multicast session joined by the first terminal device, the terminal device is not in the small data transmission process, and the identification information of the at least one terminal device includes the identification information of the first terminal device.

[0018] In a second aspect, an embodiment of the present application provides a wireless communication method, which can be performed by a terminal device or a module (such as a chip) applied to the terminal device. The method includes: the terminal device determines whether to monitor a paging message for group notification based on the state of small data transmission, the terminal device is in an RRC inactive state, and the paging message includes identification information of at least one multicast session; wherein the terminal device has joined one or more multicast sessions, and the small data transmission is the transmission of data and / or signaling by the first terminal device in the RRC inactive state, the data volume of which is lower than a preset threshold.

[0019] In the above scheme, the terminal device decides whether to listen to the paging message for group notification or not according to the status of small data transmission, rather than always listening to the paging message for group notification, which helps to save unnecessary energy consumption, reduce the processing complexity of the terminal device, and reduce signaling overhead.

[0020] In a possible implementation method, the terminal device determines whether to monitor the paging message for group notification according to the state of small data transmission, including: when the terminal device is not performing small data transmission, the terminal device monitors the paging message.

[0021] In the above scheme, when the terminal device in the RRC inactive state is not performing small data transmission, it indicates that the wireless access network device does not know in which cell the terminal device resides, and there is no available data / signaling path between the terminal device and the wireless access network device. Therefore, the terminal device needs to monitor the paging method to promptly determine whether the network side has sent a paging message for notifying the activated multicast session to ensure that the multicast session data can be received in time.

[0022] In a possible implementation method, the terminal device determines whether to monitor the paging message for group notification according to the status of small data transmission, including: when the terminal device is transmitting small data, the terminal device does not monitor the paging message.

[0023] In the above scheme, if the terminal device is currently in the process of small data transmission, it means that the wireless access network device knows in which cell the terminal device resides, and there is an available data / signaling path between the terminal device and the wireless access network device. The terminal device has sent an RRC recovery request message to the network side. Therefore, if the network side needs to allow the terminal device to enter the RRC connection state to receive the multicast session, an RRC recovery message can be sent to the terminal device. Therefore, the terminal device does not need to listen to the paging message used to notify that the multicast session has been activated, and does not need to decode the data block on the physical downlink shared channel (PDSCH) that carries the paging message, thereby saving unnecessary energy consumption, reducing the processing complexity of the terminal device, and reducing signaling overhead.

[0024] In one possible implementation method, the terminal device does not monitor the paging message when it is performing small data transmission, including: when the terminal device is performing small data transmission and the terminal device does not support receiving multicast sessions in the RRC inactive state, the terminal device does not monitor the paging message.

[0025] In this solution, if the terminal device is currently in the process of transmitting small data, it means that the wireless access network device knows which cell the terminal device resides in, there is an available data / signaling path between the terminal device and the wireless access network device, and the terminal device has sent an RRC recovery request message to the network side. Therefore, if the network side needs to allow the terminal device to enter the RRC connection state to receive the multicast session, an RRC recovery message can be sent to the terminal device. And because the terminal device does not support receiving multicast sessions in the RRC inactive state, the terminal device needs to enter the RRC connection state to receive the data of the multicast session. Therefore, the terminal device does not need to listen to the paging message used to notify that the multicast session has been activated, and does not need to decode the data block on the PDSCH carrying the paging message. Instead, it waits for the network side to actively notify the terminal device to enter the RRC connection state. Therefore, this solution can save unnecessary energy consumption, reduce the processing complexity of the terminal device, and reduce signaling overhead.

[0026] In one possible implementation method, the terminal device receives an RRC message including identification information of the at least one multicast session, and the RRC message is used to notify the terminal device that the at least one multicast session has been activated. When the at least one multicast session includes a multicast session to which the terminal device has joined, the terminal device receives the multicast session to which the terminal device has joined in an RRC inactive state. Optionally, the RRC message further instructs the terminal device to remain in the RRC inactive state to receive the multicast session.

[0027] The paging message used for group notification is a broadcast message, which is sent on the initial bandwidth part (BWP). If the sum of the BWP bandwidth range for the terminal device's current small data transmission and the bandwidth range of the initial BWP exceeds the bandwidth supported by the terminal device (for example, the terminal device is a low-capability terminal device), the terminal device cannot perform small data transmission and receive paging messages at the same time. If the terminal device wants to receive group paging during the small data transmission process, it needs to switch the BWP to the initial BWP to receive the group paging, which will cause data packet loss during the small data transmission process. However, through the above solution, the terminal device can receive the notification that the multicast session has been activated through dedicated signaling (i.e., RRC message) on the BWP for small data transmission, instead of notifying that the multicast session has been activated through a paging message. Therefore, there is no need to switch BWP, packet loss can be avoided, and the implementation complexity of the terminal device is reduced.

[0028] In one possible implementation method, the terminal device determines whether to listen to the paging message for group notification based on the status of small data transmission, including: when the terminal device is performing small data transmission and the terminal device supports receiving multicast sessions in the RRC inactive state, the terminal device listens to the paging message.

[0029] If the terminal device is currently in the process of small data transmission, it means that the wireless access network device knows which cell the terminal device resides in, there is an available data / signaling path between the terminal device and the wireless access network device, and the terminal device has sent an RRC recovery request message to the network side. Therefore, if the network side needs to allow the terminal device to enter the RRC connection state to receive the multicast session, it can send an RRC recovery message to the terminal device to trigger the terminal device to enter the RRC connection state to receive the multicast session. Therefore, under normal circumstances, the terminal device does not need to listen to the paging message used to notify that the multicast session has been activated, but only needs to wait for the RRC recovery message sent by the wireless access network device. However, in this solution, if the terminal device is transmitting small data and the terminal device supports receiving multicast sessions in the RRC inactive state, the terminal device needs to listen to the paging message. This is because: since the terminal device supports receiving multicast sessions in the RRC inactive state, the wireless access network device may not send an RRC recovery message to the terminal device to trigger the terminal device to enter the RRC connected state and receive the multicast session data in the RRC connected state. Therefore, the terminal device needs to actively listen to the paging message to know whether the multicast session has been activated to avoid missing the multicast session data sent by the network. When the terminal device listens that the multicast session has been activated, it can receive the multicast session data in the RRC inactive state.

[0030] In one possible implementation method, when the terminal device is performing small data transmission and the terminal device supports receiving multicast sessions in an RRC inactive state, the terminal device listens to the paging message, including: when the terminal device is performing small data transmission, the terminal device supports receiving multicast sessions in an RRC inactive state, and the cell in which the terminal device resides supports providing multicast sessions for terminal devices in an inactive state, the terminal device listens to the paging message.

[0031] The above solution needs to ensure that the cell where the terminal device resides supports providing multicast sessions for terminal devices in an inactive state. When the terminal device monitors the paging message, it can avoid invalid monitoring by the terminal device, which helps to save unnecessary energy consumption.

[0032] In a third aspect, an embodiment of the present application provides a wireless communication method, which can be performed by a terminal device or a module (such as a chip) applied to the terminal device. The method includes: the terminal device receives a first message, the first message including identification information of at least one multicast session, and the terminal device is in an RRC inactive state; when the at least one multicast session includes a multicast session joined by the terminal device, and the terminal device is in a small data transmission process, the terminal device enters an RRC idle state and triggers an RRC connection establishment process; wherein the small data transmission is the transmission of data and / or signaling by the terminal device in the RRC inactive state, the data volume of which is lower than a preset threshold.

[0033] In the above scheme, if at least one multicast session in the first message sent by the network side includes a multicast session to which the terminal device has joined, it indicates that the network side has multicast session data that needs to be sent to the terminal device, and the terminal device can request the network side to restore the RRC connection to receive the multicast session data. However, if the terminal device is currently in a small data transmission process after receiving the paging message, it means that the wireless access network device knows which cell the terminal device resides in, and there is an available data / signaling path between the terminal device and the wireless access network device. The terminal device has already sent an RRC recovery request message to the network side before receiving the paging message. Therefore, if the network side needs to allow the terminal device to enter the RRC connection state to receive the multicast session, it can send an RRC recovery message to the terminal device. Therefore, after receiving the paging message, if the terminal device is currently in a small data transmission process, it does not need to send an RRC recovery request message to the network side again, but can directly enter the RRC idle state and trigger the RRC connection establishment process, thereby achieving rapid entry into the RRC connection state and receiving the multicast session data, and saving unnecessary energy consumption overhead, reducing the processing complexity of the terminal device, and reducing signaling overhead.

[0034] In a possible implementation method, the first message is an RRC message or a paging message.

[0035] In a fourth aspect, an embodiment of the present application provides a wireless communication method, which can be performed by a first radio access network device or a module (such as a chip) applied to the first radio access network device. The method includes: the first radio access network device sends a second paging message, where the second paging message indicates that at least one multicast session is activated; the first radio access network device receives indication information from a first terminal device, where the indication information includes a data indication indicating non-small data transmission, and / or a multicast cause value; wherein the at least one multicast session includes a multicast session joined by the first terminal device, the first terminal device is in a radio resource control (RRC) inactive state and is in a small data transmission process; and the first radio access network device is a serving radio access network device of the first terminal device.

[0036] In the above scheme, based on the indication information sent by the first terminal device, the first wireless access network device can be informed that data has arrived at the first terminal device on the wireless bearer of non-small data transmission or that the first terminal device expects to enter the RRC connection state to receive the multicast session, which helps the first wireless access network device to determine whether to restore the RRC connection state of the first terminal device, and facilitates the subsequent correct communication between the first wireless access network device and the first terminal device, such as the first terminal device receiving the multicast session in the RRC connection state.

[0037] In a possible implementation method, after the first wireless access network device receives the indication information from the first terminal device, it also includes: the first wireless access network device sends an RRC recovery message to the first terminal device, and the RRC recovery message is used to restore the RRC connection of the first terminal device.

[0038] In a possible implementation method, before the first wireless access network device sends an RRC recovery message to the first terminal device, it also includes: the first wireless access network device sends an RRC release message to the first terminal device, and the RRC release message is used to instruct the first terminal device to enter an RRC inactive state or an RRC idle state; the first wireless access network device receives an RRC recovery request message from the first terminal device, and the RRC recovery request message is used to request to enter an RRC connection state; or, the first wireless access network device receives an RRC establishment request message from the first terminal device, and the RRC establishment request message is used to request to establish an RRC connection.

[0039] In one possible implementation method, the second paging message is also used to indicate that a terminal device in an RRC connected state receives the at least one multicast session; or, the second paging message is also used to indicate that the at least one multicast session is a multicast session received by a terminal device in an RRC connected state or an RRC non-connected state.

[0040] In a possible implementation method, before the first wireless access network device sends the second paging message, it also includes: the first wireless access network device receives a first paging message, where the first paging message is used to notify the activation of one or more multicast sessions; and determines the second paging message based on the first paging message.

[0041] In a possible implementation method, the first wireless access network device receives a first paging message, including: the first wireless access network device receives the first paging message from a second wireless access network device or a core network device, and the second wireless access network device is the last serving wireless access network device of the first terminal device in the RRC connection state.

[0042] In a possible implementation method, the first paging message also includes information used to paging the terminal device; the first wireless access network device sends the second paging message, including: the first wireless access network device sends the second paging message according to the information used to paging the terminal device.

[0043] In one possible implementation method, the multicast reason value indicates that the at least one multicast session includes the multicast session joined by the first terminal device, or indicates that the multicast session joined by the first terminal device is activated, or indicates that the first terminal device enters the RRC connection state to receive multicast.

[0044] In a possible implementation method, after the first wireless access network device receives the indication information from the first terminal device, it also includes: the first wireless access network device sends a context request message to the second wireless access network device, the context request message is used to request the terminal device context of the first terminal device, and the second wireless access network device is the last serving wireless access network device of the first terminal device in the RRC connection state; the first wireless access network device receives the terminal device context of the first terminal device from the second wireless access network device.

[0045] In a fifth aspect, an embodiment of the present application provides a wireless communication method, which can be performed by a first wireless access network device or a module (such as a chip) applied to the first wireless access network device. The method includes: the first wireless access network device receives a first paging message, the first paging message includes one or more multicast session identifiers, the first paging message is used to notify the activation of the one or more multicast sessions, and the first wireless access network device is a first terminal device serving wireless access network device; wherein, the first terminal device is in a radio resource control (RRC) inactive state and is in a small data transmission process; the first wireless access network device obtains a multicast-related context of the first terminal device, the multicast-related context includes an identifier of the multicast session to which the first terminal device joins; the first wireless access network device sends an RRC recovery message to the first terminal device, the one or more multicast session identifiers include an identifier of the multicast session to which the first terminal device joins, and the RRC recovery message is used to restore the RRC connection of the first terminal device.

[0046] In the above scheme, when the first wireless access network device learns that the activated multicast session includes the multicast session joined by the first terminal device, the RRC connection of the first terminal device is restored through the RRC recovery message, that is, the terminal device is restored to the RRC connection state, so as to facilitate subsequent correct communication between the first wireless access network device and the first terminal device, such as the first terminal device receiving the multicast session in the RRC connection state.

[0047] In a possible implementation method, before the first wireless access network device sends an RRC recovery message to the first terminal device, it also includes: determining a second paging message based on the first paging message, the second paging message indicating that at least one multicast session is activated, and the at least one multicast session includes the multicast session joined by the first terminal device; and sending the second paging message.

[0048] In a possible implementation method, before the first wireless access network device sends an RRC recovery message to the first terminal device, it also includes: the first wireless access network device sends an RRC release message to the first terminal device, and the RRC release message is used to instruct the first terminal device to enter an RRC inactive state or an RRC idle state; the first wireless access network device receives an RRC recovery request message from the first terminal device, and the RRC recovery request message is used to request to enter an RRC connection state; or, the first wireless access network device receives an RRC establishment request message from the first terminal device, and the RRC establishment request message is used to request to establish an RRC connection.

[0049] In a possible implementation method, the first wireless access network device receives a first paging message, including: the first wireless access network device receives the first paging message from a second wireless access network device or a core network device, and the second wireless access network device is the last serving wireless access network device of the first terminal device in the RRC connection state.

[0050] In a possible implementation method, the first wireless access network device obtains the multicast-related context of the first terminal device, including: the first wireless access network device sends a first context request message to the second wireless access network device, and the first context request message is used to request to obtain the context of the first terminal device for small data transmission; the first wireless access network device receives a partial context of the first terminal device from the second wireless access network device, and the partial context of the first terminal device includes a context related to small data transmission and a context related to the multicast, and the second wireless access network device is the last serving wireless access network device of the first terminal device in the RRC connection state.

[0051] In a possible implementation method, the method also includes: the first wireless access network device sends a second context request message to the second wireless access network device, where the second context request message is used to request the context of the first terminal device; and the first wireless access network device receives the terminal device context of the first terminal device from the second wireless access network device.

[0052] In a possible implementation method, the first wireless access network device obtains the multicast-related context of the first terminal device, including: the first wireless access network device receives the terminal device context of the first terminal device from a second wireless access network device, the terminal device context includes the multicast-related context, and the second wireless access network device is the last serving wireless access network device of the first terminal device in the RRC connection state.

[0053] In a sixth aspect, an embodiment of the present application provides a wireless communication method, which can be performed by a second radio access network device or a module (such as a chip) applied to the second radio access network device. The method includes: the second radio access network device determines whether the identifiers of one or more activated multicast sessions include the identifier of the multicast session to which the first terminal device joins; when the identifiers of the one or more activated multicast sessions include the identifier of the multicast session to which the first terminal device joins, the second radio access network device sends the terminal device context of the first terminal device to the first radio access network device; wherein, the first terminal device is in a radio resource control (RRC) inactive state and is in a small data transmission process; the first radio access network device is the serving radio access network device of the first terminal device, and the second radio access network device is the last serving radio access network device of the first terminal device in an RRC connected state.

[0054] In the above scheme, when the second wireless access network device learns that the activated multicast session includes the multicast session joined by the first terminal device, it sends the context of the first terminal device to the first wireless access network device, so that the first wireless access network device can learn that the multicast session joined by the first terminal device has been activated. Then, the first wireless access network device can restore the terminal device to the RRC connection state, so as to facilitate subsequent correct communication between the first wireless access network device and the first terminal device, such as the first terminal device receiving the multicast session in the RRC connection state.

[0055] In a possible implementation method, the terminal device context includes a multicast-related context of the first terminal device.

[0056] In a possible implementation method, before the second wireless access network device sends the terminal device context of the first terminal device to the first wireless access network device, it also includes: the second wireless access network device receives a context request message from the first wireless access network device, and the context request message is used to request to obtain the context of the terminal device for small data transmission; the second wireless access network device sends a partial context of the first terminal device to the first wireless access network device, and the partial context of the first terminal device includes a context related to small data transmission.

[0057] In a possible implementation method, the method further includes: the second radio access network device sending a first paging message to the first radio access network device, where the first paging message is used to notify the activation of the one or more multicast sessions.

[0058] In a possible implementation method, the first paging message includes identifiers of the one or more multicast sessions.

[0059] In a seventh aspect, an embodiment of the present application provides a wireless communication method, which can be performed by a first terminal device or a module (such as a chip) applied to the first terminal device. The method includes: the first terminal device receives a second paging message from a first radio access network device, and the second paging message indicates that at least one multicast session is activated; the first terminal device sends indication information to the first radio access network device, and the indication information includes a non-small data transmission data indication and / or a multicast cause value; wherein, the at least one multicast session includes a multicast session joined by the first terminal device, and the first terminal device is in a radio resource control RRC inactive state and is in a small data transmission process; the first radio access network device is the serving radio access network device of the first terminal device.

[0060] In the above scheme, the first terminal device sends an indication message to the first wireless access network device, so that the first wireless access network device learns from the indication message that data has arrived at the first terminal device on the wireless bearer for non-small data transmission or learns that the first terminal device expects to enter the RRC connection state to receive the multicast session, which helps the first wireless access network device to determine whether to restore the RRC connection state of the first terminal device, and facilitates the subsequent correct communication between the first wireless access network device and the first terminal device, such as the first terminal device receiving the multicast session in the RRC connection state.

[0061] In a possible implementation method, after the first terminal device sends indication information to the first wireless access network device, it also includes: the first terminal device receives an RRC recovery message from the first wireless access network device, and the RRC recovery message is used to restore the RRC connection of the first terminal device.

[0062] In a possible implementation method, before the first terminal device receives the RRC recovery message from the first radio access network device, it also includes: the first terminal device receives an RRC release message from the first radio access network device, and the RRC release message is used to instruct the first terminal device to enter an RRC inactive state or an RRC idle state; the first terminal device sends an RRC recovery request message to the first radio access network device, and the RRC recovery request message is used to request to enter an RRC connected state; or, the first terminal device sends an RRC establishment request message to the first radio access network device, and the RRC establishment request message is used to request to establish an RRC connection.

[0063] In one possible implementation method, the second paging message is also used to indicate that a terminal device in an RRC connected state receives the at least one multicast session; or, the second paging message is also used to indicate that the at least one multicast session is a multicast session received by a terminal device in an RRC connected state or an RRC non-connected state.

[0064] In one possible implementation method, the multicast reason value indicates that the at least one multicast session includes the multicast session joined by the first terminal device, or indicates that the multicast session joined by the first terminal device is activated, or indicates that the first terminal device enters the RRC connection state to receive multicast.

[0065] In an eighth aspect, an embodiment of the present application provides a communication device, which may be a terminal device or a module (such as a chip) applied to a terminal device. The device has the function of implementing any of the implementation methods of the first to seventh aspects above. The function can be implemented by hardware or by executing corresponding software implementations by hardware. The hardware or software includes one or more modules corresponding to the above functions.

[0066] In a ninth aspect, an embodiment of the present application provides a communication device, comprising a processor coupled to a memory, the processor configured to call a program stored in the memory to execute any of the implementation methods described in aspects 1 to 7 above. The memory may be located within or outside the device, and the processor may be one or more.

[0067] In the tenth aspect, an embodiment of the present application provides a communication device, comprising a processor and a memory; the memory is used to store computer instructions, and when the device is running, the processor executes the computer instructions stored in the memory to enable the device to execute any implementation method in the above-mentioned first to seventh aspects.

[0068] In an eleventh aspect, an embodiment of the present application provides a communication device, comprising a unit or means for executing each step of any implementation method in the above-mentioned first to seventh aspects.

[0069] In a twelfth aspect, an embodiment of the present application provides a communication device, comprising a processor and an interface circuit, wherein the processor is configured to communicate with other devices via the interface circuit and execute any of the implementation methods described in aspects 1 to 7 above. The processor comprises one or more.

[0070] In the thirteenth aspect, an embodiment of the present application further provides a chip system, comprising: a processor for executing any implementation method in the above-mentioned first to seventh aspects.

[0071] In the fourteenth aspect, an embodiment of the present application further provides a computer-readable storage medium, wherein instructions are stored in the computer-readable storage medium, which, when run on a communication device, enables any implementation method in the above-mentioned first to seventh aspects to be executed.

[0072] In the fifteenth aspect, an embodiment of the present application further provides a computer program product, which includes a computer program or instructions. When the computer program or instructions are run by a communication device, any implementation method in the above-mentioned first to seventh aspects is executed.

[0073] In a sixteenth aspect, an embodiment of the present application provides a communication system, comprising a first terminal device and a wireless access network device. The first terminal device is configured to send a paging message, the paging message including identification information of at least one multicast session, and the first terminal device is in an RRC inactive state; when a first condition is met, an RRC connection recovery process is triggered; the wireless access network device is configured to send an RRC recovery message to the first terminal device, the RRC recovery message being used to trigger the first terminal device to enter an RRC connected state; wherein the first condition includes: the at least one multicast session includes a multicast session joined by the first terminal device, and the first terminal device is not in a small data transmission process; or, the first condition includes: the paging message also includes identification information of at least one terminal device, the at least one multicast session includes a multicast session joined by the first terminal device, the terminal device is not in a small data transmission process, and the identification information of the at least one terminal device does not include identification information of the first terminal device; the small data transmission is the transmission of data and / or signaling by the first terminal device in the RRC inactive state, the data volume of which is lower than a preset threshold.

[0074] In one possible implementation method, the first terminal device is specifically used to send an RRC recovery request message to a wireless access network device.

[0075] In one possible implementation method, the first terminal device is also used to determine not to trigger the RRC connection recovery process when a second condition is met; wherein the second condition includes: the at least one multicast session includes the multicast session joined by the first terminal device, and the first terminal device is in a small data transmission process.

[0076] In one possible implementation method, the first terminal device is also used to send indication information to the wireless access network device, which indicates that data and / or signaling have arrived on the wireless bearer for non-small data transmission, or that the at least one multicast session includes the multicast session joined by the first terminal device.

[0077] In one possible implementation method, the first terminal device is also used to enter the RRC idle state and trigger the RRC connection establishment process when a third condition is met; wherein, the third condition includes: the paging message also includes identification information of at least one terminal device, the at least one multicast session includes the multicast session joined by the first terminal device, the terminal device is not in a small data transmission process, and the identification information of the at least one terminal device includes the identification information of the first terminal device.

[0078] In a seventeenth aspect, an embodiment of the present application provides a communication system, comprising a terminal device and a wireless access network device. The wireless access network device is configured to send a first message to the terminal device, the first message including identification information of at least one multicast session, and the terminal device is in an RRC inactive state; the terminal device is configured to enter an RRC idle state and trigger an RRC connection establishment process when the at least one multicast session includes a multicast session joined by the terminal device and the terminal device is in a small data transmission process; wherein the small data transmission is the transmission of data and / or signaling by the terminal device in the RRC inactive state, the data volume of which is lower than a preset threshold.

[0079] In a possible implementation method, the first message is an RRC message or a paging message.

[0080] In the eighteenth aspect, an embodiment of the present application provides a communication system, which includes a first wireless access network device for implementing any method of the fourth aspect, and a first terminal device for implementing any method described in the seventh aspect.

[0081] In a nineteenth aspect, an embodiment of the present application provides a communication system, comprising a first terminal device and a first radio access network device configured to implement any method described in aspect five. The first terminal device is configured to receive an RRC recovery message, wherein the RRC recovery message is used to restore an RRC connection of the first terminal device.

[0082] In aspect 20, an embodiment of the present application provides a communication system, comprising a first wireless access network device and a second wireless access network device configured to implement any of the methods described in aspect 6. The first wireless access network device is configured to receive a terminal device context of a first terminal device. BRIEF DESCRIPTION OF THE DRAWINGS

[0083] FIG1 is a schematic diagram of the architecture of a communication system used in an embodiment of the present application;

[0084] FIG2 is a schematic diagram of a flow chart of a wireless communication method provided in an embodiment of the present application;

[0085] FIG3 is a schematic diagram of a flow chart of a wireless communication method provided in an embodiment of the present application;

[0086] FIG3( a ) is a schematic diagram of a flow chart of a wireless communication method provided in an embodiment of the present application;

[0087] FIG3( b ) is a schematic diagram of a flow chart of a wireless communication method provided in an embodiment of the present application;

[0088] FIG3( c ) is a schematic diagram of a flow chart of a wireless communication method provided in an embodiment of the present application;

[0089] FIG3( d ) is a schematic diagram of a flow chart of a wireless communication method provided in an embodiment of the present application;

[0090] FIG3( e) is a schematic flow chart of a wireless communication method provided in an embodiment of the present application;

[0091] FIG3( f) is a schematic diagram of a flow chart of a wireless communication method provided in an embodiment of the present application;

[0092] FIG4 is a schematic diagram of a communication device provided in an embodiment of the present application;

[0093] FIG5 is a schematic diagram of a communication device provided in an embodiment of the present application. DETAILED DESCRIPTION

[0094] Figure 1 is a schematic diagram of the architecture of the communication system used in the embodiment of the present application. The communication system 1000 includes a wireless access network 100 and a core network 200. Optionally, the communication system 1000 also includes the Internet 300. The wireless access network 100 may include at least one wireless access network device, such as 110a and 110b in Figure 1, and may also include at least one terminal device, such as 120a-120j in Figure 1. 110a is a base station, 110b is a micro station, 120a, 120e, 120f and 120j are mobile phones, 120b is a car, 120c is a gas pump, 120d is a home access point (HAP) arranged indoors or outdoors, 120g is a laptop computer, 120h is a printer, and 120i is a drone. The same terminal device or wireless access network device can provide different functions in different application scenarios. For example, in FIG1 , there are mobile phones 120 a , 120 e , 120 f , and 120 j . Mobile phone 120 a can access base station 110 a , connect to car 120 b , communicate directly with mobile phone 120 e , and access HAP. Mobile phone 120 b can access HAP and communicate directly with mobile phone 120 a . Mobile phone 120 f can be connected as micro station 110 b , connect to laptop computer 120 g , and connect to printer 120 h . Mobile phone 120 j can control drone 120 i .

[0095] Terminal devices are connected to radio access network equipment, which in turn is connected to the core network. The core network equipment and radio access network equipment can be independent, distinct physical devices, or they can integrate the core network equipment's functions and the radio access network equipment's logical functions into the same physical device. Alternatively, a single physical device can integrate some core network equipment functions and some radio access network equipment functions. Terminal devices and radio access network equipment can be connected to each other via wired or wireless means. Figure 1 is merely a schematic diagram; the communication system may also include other network devices, such as wireless relay equipment and wireless backhaul equipment, which are not shown in Figure 1.

[0096] The wireless access network device can be a base station, an evolved NodeB (eNodeB), a transmission reception point (TRP), a next generation NodeB (gNB) in a fifth generation (5G) mobile communication system, a base station in a sixth generation (6G) mobile communication system, a base station in a future mobile communication system, or an access node in a wireless fidelity (WiFi) system, etc.; it can also be a module or unit that completes part of the functions of a base station, for example, a centralized unit (CU) or a distributed unit (DU). The wireless access network device can be a macro base station (such as 110a in Figure 1), a micro base station or an indoor station (such as 110b in Figure 1), a relay node or a donor node, etc. The embodiments of the present application do not limit the specific technology and specific device form adopted by the wireless access network device.

[0097] Terminal devices may also be referred to as terminals, user equipment (UE), mobile stations, mobile terminals, etc. Terminal devices can be widely used in various scenarios, for example, device-to-device (D2D), vehicle-to-everything (V2X) communication, machine-type communication (MTC), Internet of Things (IOT), virtual reality, augmented reality, industrial control, autonomous driving, telemedicine, smart grid, smart furniture, smart office, smart wearable, smart transportation, smart city, etc. Terminal devices may be mobile phones, tablet computers, computers with wireless transceiver functions, wearable devices, vehicles, drones, helicopters, airplanes, ships, robots, robotic arms, smart home devices, etc. The embodiments of the present application do not limit the specific technology and specific device form adopted by the terminal devices.

[0098] Wireless access network equipment and terminal devices can be fixed or mobile. They can be deployed on land, including indoors or outdoors, handheld or vehicle-mounted; on water; or in the air on aircraft, balloons, and satellites. The embodiments of this application do not limit the application scenarios of wireless access network equipment and terminal devices.

[0099] The roles of wireless access network equipment and terminal devices can be relative. For example, the helicopter or drone 120i in Figure 1 can be configured as a mobile base station. To terminal devices 120j accessing the wireless access network 100 via 120i, terminal device 120i is a base station. However, to base station 110a, 120i is a terminal device, meaning that communication between 110a and 120i occurs via a wireless air interface protocol. Of course, communication between 110a and 120i can also occur via a base station-to-base station interface protocol. In this case, 120i is also a base station relative to 110a. Therefore, wireless access network equipment and terminal devices can be collectively referred to as communication devices. 110a and 110b in Figure 1 can be referred to as communication devices with wireless access network equipment functionality, while 120a-120j in Figure 1 can be referred to as communication devices with terminal equipment functionality.

[0100] In the embodiments of the present application, the functions of the wireless access network device may also be performed by a module (such as a chip) in the wireless access network device, or by a control subsystem that includes the functions of the wireless access network device. The control subsystem that includes the functions of the wireless access network device here can be a control center in the above-mentioned application scenarios such as smart grid, industrial control, smart transportation, and smart city. The functions of the terminal device may also be performed by a module (such as a chip or modem) in the terminal device, or by a device that includes the functions of the terminal device.

[0101] To facilitate understanding of the solutions of the embodiments of the present application, the following first introduces the nouns or terms involved in the embodiments of the present application, which are also considered part of the present invention.

[0102] 1. Status of terminal devices

[0103] Currently, a terminal device has three radio resource control (RRC) states, namely, RRC connected state (RRC_connected), RRC idle state (RRC_idle), and RRC inactive state (RRC_inactive).

[0104] In the RRC connected state, an RRC connection is established between the terminal device and the radio access network device, and data can be transmitted between the terminal device and the radio access network device. When there is no data transmission, the radio access network device can release the terminal device to the RRC idle state or RRC inactive state.

[0105] In the RRC idle state, no RRC connection is established between the terminal device and the wireless access network device, and data is generally not transmitted between the terminal device and the wireless access network device.

[0106] In the RRC inactive state, the radio access network device suspends the RRC connection and maintains the context information of the terminal device. When it is necessary to restore to the RRC connected state later, the terminal device can quickly restore to the RRC connected state because the context information of the terminal device is maintained in the radio access network device.

[0107] 2. Paging

[0108] Due to the mobility of terminal devices, when a terminal device is in the RRC idle state or RRC inactive state, the network can broadcast a paging message to locate the terminal device. After receiving the paging message, the terminal device can determine whether the paging message contains the terminal device's identification information. If it does, it indicates that the network is paging the terminal device, so the terminal device can trigger the establishment of an RRC connection and enter the RRC connected state.

[0109] Currently, there are two paging methods. One is core network paging, in which the core network sends a paging message within the tracking area (TA) indicated by a tracking area identity (TAI) list. The TAI list includes one or more TAIs, each TAI identifies a TA, and a TA includes one or more cells. This paging message is also called a core network paging message.

[0110] The other is RAN-based notification area (RNA) paging, in which the radio access network equipment sends a paging message within the range of the RNA. An RNA includes one or more cells, and the range of the RNA is smaller than the range of the TA. This paging message is also called a RAN paging message or an RNA paging message.

[0111] 3. Small data transmission (SDT)

[0112] For terminal devices in the RRC inactive state, in order to avoid the increase in energy consumption of the terminal device caused by entering the RRC connected state when the service traffic is small, when the amount of data to be transmitted by the terminal device in the RRC inactive state is lower than a preset threshold, the terminal device may not enter the RRC connected state, but instead transmit data and / or signaling with the radio access network device in the RRC inactive state. This process is called small data transmission. In other words, small data transmission refers to the transmission of data and / or signaling by the terminal device in the RRC inactive state with a data amount lower than a preset threshold.

[0113] Methods for transmitting small amounts of data include but are not limited to the following two methods.

[0114] Method 1 is to transmit small data via a random access channel (RACH) process.

[0115] In one approach, if the RACH process is a four-step RACH, the terminal device may send small uplink data (also called SDT UL data) to the wireless access network device in MSG3, and also send an RRC recovery request (RRCResumeRequest) message in MSG3.

[0116] In another manner, if the RACH process is a two-step RACH, the terminal device may send small uplink data to the wireless access network device in the MSGA, and also send an RRC recovery request message in the MSGA.

[0117] Method 2: Small data transmission is performed through pre-configured grant (CG) resources.

[0118] The terminal device sends uplink small data to the radio access network device through the CG resource, and also sends an RRC recovery request message. The CG resource is configured by the radio access network device to the terminal device through the RRC release (RRCRelease) message.

[0119] In the above-mentioned method 1 and method 2, the RRC recovery request message sent by the terminal device to the wireless access network device is used to trigger the RRC connection recovery for small data transmission.

[0120] The above-mentioned small data transmission solution enables a terminal device in an RRC inactive state to send small data without entering an RRC connected state, thereby reducing the energy consumption overhead of the terminal device caused by entering an RRC connected state for data transmission with a smaller amount of data.

[0121] 4. Multicast Communication

[0122] Multicast communication means that the same service and the same data are provided to a specific group of terminal devices at the same time. Generally, the network side can send multicast services to terminal devices in the RRC connected state through a multicast session. When the network side has no multicast session data to send to the terminal device, the network side can allow the terminal device to enter the RRC idle state or the RRC inactive state to save energy consumption of the terminal device. When the multicast session is activated or the data of the multicast session arrives, the network side notifies the terminal devices in the RRC idle state or the RRC inactive state through the group notification mechanism. After receiving the group notification, the terminal device can re-establish a connection with the network side to receive the data of the multicast session. Once the terminal device leaves the multicast session, the terminal device can stop monitoring the group notification related to the multicast session.

[0123] In one scenario, after a multicast session is activated, the network pages a terminal device that has joined the multicast session and is in an RRC inactive state. This terminal device may or may not be in the process of transmitting small data. The specific actions the terminal device should perform remain to be determined.

[0124] FIG2 is a flow chart of a wireless communication method provided in an embodiment of the present application. The method includes the following steps:

[0125] Step 201: The first terminal device receives a paging message.

[0126] The first terminal device is in an RRC inactive state.

[0127] This paging message is a group notification message that contains identification information for at least one multicast session, notifying the terminal device of an activated multicast session. When the core network notifies the wireless access network device that a multicast session has been activated, or when the wireless access network device receives data for a multicast session, the wireless access network device can use group notification to send a paging message to terminal devices in an RRC-inactive state that have joined the multicast session, notifying them of the multicast session activation. The identification information for the multicast session in the paging message can indicate a specific multicast service within a specific public land mobile network (PLMN).

[0128] In one implementation method, the multicast session may be a multicast broadcast service (MBS) multicast session, and the identification information of the multicast session may be a temporary mobile group identifier (TMGI).

[0129] Step 202: When the first condition is met, the first terminal device triggers the RRC connection recovery process.

[0130] In one implementation method, the first condition includes: at least one multicast session in the paging message includes a multicast session joined by the first terminal device, and the first terminal device is not in a small data transmission process (SDT procedure is not on-going). The fact that the at least one multicast session includes a multicast session joined by the first terminal device indicates that one or some multicast sessions joined by the first terminal device have been activated, or it is understood that there is multicast session data on the network side that needs to be sent to the first terminal device. In the embodiment of the present application, not being in a small data transmission process means that small data transmission is not currently being performed, and the two have the same meaning. Being in a small data transmission process means that small data transmission is currently being performed, and the two have the same meaning. A unified description is given here and will not be repeated later.

[0131] For example, the paging message includes TMGI_1, TMGI_2, TMGI_3, and TMGI_4, indicating that the multicast sessions identified by TMGI_1, TMGI_2, TMGI_3, and TMGI_4 have been activated. If the identification information of the multicast session that UE_1 has joined includes TMGI_5 and TMGI_6, then at least one multicast session in the paging message does not include the multicast session joined by the first terminal device, indicating that the network side has no multicast session data that needs to be sent to the UE_1. If the identification information of the multicast session that UE_1 has joined includes TMGI_1 and TMGI_6, then at least one multicast session in the paging message includes the multicast session joined by the first terminal device, indicating that the network side has multicast session data that needs to be sent to the UE_1. Specifically, the network side needs to send the data of the multicast session identified by TMGI_1 to UE_1.

[0132] Among them, the first terminal device triggers the RRC connection recovery process, which can be specifically: the first terminal device sends an RRC recovery request message to the wireless access network device to request recovery from the RRC inactive state to the RRC connected state. After receiving the RRC recovery request message, the wireless access network device can send an RRC recovery message to the first terminal device to trigger the first terminal device to recover from the RRC inactive state to the RRC connected state.

[0133] In the above scheme, if at least one multicast session in the paging message sent by the network side includes a multicast session joined by the first terminal device, it indicates that the network side has multicast session data that needs to be sent to the first terminal device, and the first terminal device can request the network side to restore the RRC connection to receive the multicast session data. However, if the first terminal device is currently in a small data transmission process after receiving the paging message, it means that the first terminal device has already sent an RRC recovery request message to the network side before receiving the paging message, and there is an available data / signaling transmission path between the wireless access network device and the first terminal device. The wireless access network device is aware of the cell where the first terminal device resides. Therefore, if the network side needs to allow the first terminal device to enter the RRC connection state to receive the multicast session, it can send an RRC recovery message to the first terminal device through this transmission path. Therefore, after receiving the paging message, if the first terminal device is currently in the small data transmission process, it does not need to send the RRC recovery request message to the network side again, but can wait for the network side device to send the RRC recovery message. The RRC recovery message can be in response to the RRC recovery request message sent by the first terminal device when triggering small data transmission, thereby saving unnecessary energy consumption overhead, reducing the processing complexity of the terminal device, and reducing signaling overhead.

[0134] In one implementation method, the paging message also includes identification information of at least one terminal device, and the at least one terminal device refers to the terminal device that the core network needs to page. When the identification information (UE-Identity) of at least one terminal device in the paging message includes the identification information of the first terminal device, it indicates that the core network is paging the first terminal device, and the identification information of the terminal device is identification information associated with the core network paging. When the identification information of at least one terminal device in the paging message does not include the identification information of the first terminal device, it indicates that the core network is not paging the first terminal device. The fact that the identification information of at least one terminal device in the paging message does not include the identification information of the first terminal device can also be replaced by / understood as the identification information of at least one terminal device in the paging message does not match the identification information of the first terminal device.

[0135] In one implementation method, the first condition of step 202 can be replaced by: at least one multicast session in the paging message includes a multicast session to which the first terminal device has joined, the identification information of at least one terminal device in the paging message does not include the identification information of the first terminal device, and the first terminal device is not in the process of transmitting small data. That is, when the first terminal device is not in the process of transmitting small data and has not been paged by the core network, but is notified of the activation of a multicast session, the first terminal device triggers the RRC connection recovery process, enters the RRC connected state, and subsequently receives data sent by the network through the activated multicast session.

[0136] In another implementation method, if the first condition described above is not met but the second condition is met, the first terminal device determines not to trigger the RRC connection recovery process. The second condition includes: at least one multicast session in the paging message includes a multicast session to which the first terminal device has joined, and the first terminal device is currently in a small data transmission process. That is, when the first terminal device determines that one or more of the first terminal device's multicast sessions have been activated and the network needs to send data to the first terminal device through the activated multicast session, but the first terminal device is currently in a small data transmission process, the first terminal device determines not to trigger the RRC connection recovery process. Specifically, when the first terminal device is in an RRC inactive state, it determines not to send an RRC recovery request message. This is because, according to the small data transmission process described above, the first terminal device has already sent an RRC recovery request message to the radio access network device during the small data transmission process. An available signaling / data transmission link already exists between the first terminal device and the radio access network device. The network side is aware of which radio access network device the first terminal device is connected to. Therefore, the first terminal device does not need to send the RRC recovery request message again, thereby saving signaling overhead. Since the wireless access network device knows that the first terminal device is performing small data transmission and needs to send multicast session data to the first terminal device, the wireless access network device can send an RRC recovery message to the first terminal device after the small data transmission of the first terminal device is completed, so as to trigger the first terminal device to enter the RRC connection state, and then send the multicast session data to the first terminal device in the RRC connection state. Alternatively, the wireless access network device can first stop the small data transmission of the first terminal device and send an RRC recovery message to the first terminal device to trigger the first terminal device to enter the RRC connection state, and then send the multicast session data to the first terminal device in the RRC connection state.

[0137] In another implementation method, if the above-mentioned first and second conditions are not met, but the third condition is met, the first terminal device enters the RRC idle state and triggers the RRC connection establishment process. The third condition includes: at least one multicast session in the above-mentioned paging message includes the multicast session joined by the first terminal device, the identification information of at least one terminal device in the above-mentioned paging message includes the identification information of the first terminal device, and the first terminal device is not in the small data transmission process. That is, when the first terminal device is not in the small data transmission process, but is paged by the core network, and is also notified that a multicast session is activated, the first terminal device enters the RRC idle state and triggers the RRC connection establishment process, and subsequently receives data sent by the network through the activated multicast session.

[0138] In one possible implementation method, regardless of whether the above-mentioned first condition, second condition or third condition is met, it indicates that at least one multicast session in the above-mentioned paging message includes a multicast session joined by the first terminal device, so the first terminal device can send an indication information to the wireless access network device, and the indication information indicates that at least one multicast session in the above-mentioned paging message includes one or some of the multicast sessions joined by the first terminal device, or indicates that one or some of the multicast sessions joined by the first terminal device have been activated, or indicates that the multicast service has arrived, or indicates that data and / or signaling have arrived on the radio bearer for non-small data transmission (arrival of data and / or signaling mapped to radio bearers not configured for SDT). Optionally, the indication information can be carried in auxiliary information (UEAssistanceInformation) and sent to the wireless access network device. Optionally, the indication information is non-SDT data indication information (nonSDT-DataIndication).

[0139] In the above scheme, based on the indication information sent by the first terminal device, the wireless access network device can learn that the first terminal device has data or signaling arriving on the radio bearer for non-small data transmission, or learn that the first terminal device expects to enter the RRC connection state to receive the multicast session, which helps the wireless access network device determine whether to restore the RRC connection state for the first terminal device, thereby facilitating subsequent correct communication between the wireless access network device and the first terminal device. For example, if the first terminal device does not expect to enter the RRC connection state to receive the multicast session indicated in the paging message after receiving the paging message, or has already released the multicast session, the first terminal device may not send the indication information to the wireless access network device, and the wireless access network device does not need to allow the first terminal device to enter the RRC connection state.

[0140] The following describes an embodiment of whether a terminal device needs to monitor paging messages.

[0141] In one implementation method, a terminal device in an RRC inactive state can determine whether to listen to a paging message for group notification based on the status of small data transmission. The paging message includes identification information of at least one multicast session, and the terminal device has joined one or more multicast sessions. For a detailed description of the paging message, reference can be made to the description in aforementioned step 201. In this solution, the terminal device decides whether to listen to a paging message for group notification or not based on the status of small data transmission, rather than always listening to a paging message for group notification. This helps save unnecessary energy consumption, reduces terminal device processing complexity, and reduces signaling overhead.

[0142] The following describes different implementation methods for a terminal device to determine whether to monitor a paging message for group notification according to the status of small data transmission.

[0143] Implementation method 1: When the terminal device is not transmitting small data, the terminal device monitors the paging message.

[0144] In this solution, when a terminal device in an RRC inactive state is not performing small data transmission, it indicates that the wireless access network device does not know which cell the terminal device resides in, and there is no available data / signaling path between the terminal device and the wireless access network device. Therefore, the terminal device needs to monitor paging to promptly determine whether the network side has sent a paging message for notifying the activated multicast session to ensure that the multicast session data can be received in a timely manner.

[0145] Implementation method 2: When the terminal device is transmitting small data, the terminal device does not monitor the paging message.

[0146] In this solution, if the terminal device is currently in the process of small data transmission, it means that the wireless access network device knows which cell the terminal device resides in, there is an available data / signaling path between the terminal device and the wireless access network device, and the terminal device has sent an RRC recovery request message to the network side. Therefore, if the network side needs to allow the terminal device to enter the RRC connection state to receive the multicast session, the RRC recovery message can be sent to the terminal device. Therefore, the terminal device does not need to listen to the paging message used to notify that the multicast session has been activated, and does not need to decode the data block on the PDSCH carrying the paging message, thereby saving unnecessary energy consumption, reducing the processing complexity of the terminal device, and reducing signaling overhead.

[0147] For the second implementation method mentioned above, since the terminal device is transmitting small data, there is an available data / signaling path between the terminal device and the wireless access network device, so the wireless access network device can send an RRC message to the terminal device through the path, and the RRC message includes identification information of at least one multicast session. The RRC message is used to indicate that at least one multicast session has been activated. Optionally, the RRC message also instructs the terminal device to remain in the RRC inactive state to receive the multicast session. When at least one multicast session includes a multicast session joined by the terminal device, the terminal device receives the joined multicast session in the RRC inactive state. The paging message used for group notification is a broadcast message, which is sent on the initial bandwidth part (bandwidth part, BWP). If the sum of the BWP bandwidth range of the terminal device currently performing small data transmission and the bandwidth range of the initial BWP exceeds the bandwidth supported by the terminal device (for example, the terminal device is a low-capability terminal device), the terminal device cannot perform small data transmission and receive paging messages at the same time. If a terminal device needs to receive group paging during a small data transmission, it needs to switch its BWP to the initial BWP to receive the group paging, which may cause data packet loss during the small data transmission. However, with the above solution, the terminal device can receive notification of the multicast session activation through dedicated signaling (i.e., RRC message) on the BWP for small data transmission, rather than receiving notification of the multicast session activation through a paging message. Therefore, there is no need to switch BWP, packet loss can be avoided, and the implementation complexity of the terminal device can be reduced.

[0148] Implementation method three: when the terminal device is transmitting small data and the terminal device does not support receiving multicast sessions in the RRC inactive state, the terminal device does not monitor paging messages.

[0149] In this solution, if the terminal device is currently in the process of transmitting small data, it means that the wireless access network device knows which cell the terminal device resides in, there is an available data / signaling path between the terminal device and the wireless access network device, and the terminal device has sent an RRC recovery request message to the network side. Therefore, if the network side needs to allow the terminal device to enter the RRC connection state to receive the multicast session, an RRC recovery message can be sent to the terminal device. And because the terminal device does not support receiving multicast sessions in the RRC inactive state, the terminal device needs to enter the RRC connection state to receive the data of the multicast session. Therefore, the terminal device does not need to listen to the paging message used to notify that the multicast session has been activated, and does not need to decode the data block on the PDSCH carrying the paging message. Instead, it waits for the network side to actively notify the terminal device to enter the RRC connection state. Therefore, this solution can save unnecessary energy consumption, reduce the processing complexity of the terminal device, and reduce signaling overhead.

[0150] Implementation method four: when the terminal device is transmitting small data and the terminal device supports receiving multicast sessions in the RRC inactive state, the terminal device monitors the paging message.

[0151] If the terminal device is currently in the process of small data transmission, it means that the wireless access network device knows which cell the terminal device resides in, there is an available data / signaling path between the terminal device and the wireless access network device, and the terminal device has sent an RRC recovery request message to the network side. Therefore, if the network side needs to allow the terminal device to enter the RRC connection state to receive the multicast session, it can send an RRC recovery message to the terminal device to trigger the terminal device to enter the RRC connection state to receive the multicast session. Therefore, under normal circumstances, the terminal device does not need to listen to the paging message used to notify that the multicast session has been activated, but only needs to wait for the RRC recovery message sent by the wireless access network device. However, in this solution, if the terminal device is transmitting small data and the terminal device supports receiving multicast sessions in the RRC inactive state, the terminal device needs to listen to the paging message. This is because: since the terminal device supports receiving multicast sessions in the RRC inactive state, the wireless access network device may not send an RRC recovery message to the terminal device to trigger the terminal device to enter the RRC connected state and receive the multicast session data in the RRC connected state. Therefore, the terminal device needs to actively listen to the paging message to know whether the multicast session has been activated to avoid missing the multicast session data sent by the network. When the terminal device listens that the multicast session has been activated, it can receive the multicast session data in the RRC inactive state.

[0152] Implementation method five: when the terminal device is transmitting small data, the terminal device supports receiving multicast sessions in the RRC inactive state, and the cell where the terminal device resides supports providing multicast sessions for terminal devices in the inactive state, the terminal device monitors the paging message.

[0153] Among them, the cell where the terminal device resides is a multicast session provided by the terminal device in the inactive state, and is a multicast session that the terminal device has joined. Since the terminal device supports receiving multicast sessions in the RRC inactive state, and the current resident cell supports sending the multicast session to the terminal device in the RRC inactive state, the wireless access network device may not send an RRC recovery message to the terminal device to trigger the terminal device to enter the RRC connection state and receive the multicast session data in the RRC connection state. Therefore, the terminal device needs to actively monitor the paging message to know whether the multicast session has been activated to avoid missing the multicast session data sent by the network. When the terminal device monitors that the multicast session has been activated, it can receive the multicast session data in the RRC inactive state.

[0154] The above solution needs to ensure that the cell where the terminal device resides supports providing multicast sessions for terminal devices in an inactive state. When the terminal device monitors the paging message, it can avoid invalid monitoring by the terminal device, which helps to save unnecessary energy consumption.

[0155] FIG3 is a flow chart of a wireless communication method provided in an embodiment of the present application. The method includes the following steps:

[0156] Step 301: The terminal device receives a first message.

[0157] The first message may be a paging message or an RRC message.

[0158] When the first message is a paging message, the specific content and implementation of the paging message are the same as those of the paging message in step 201 above, and reference may be made to the above description.

[0159] When the first message is an RRC message, the RRC message includes identification information of at least one multicast session, the RRC message is used to indicate that the at least one multicast session has been activated, and the RRC message is a unicast message or dedicated signaling.

[0160] Step 302: When at least one multicast session includes a multicast session joined by the terminal device and the terminal device is in a small data transmission process, the terminal device enters an RRC idle state and triggers an RRC connection establishment process.

[0161] When at least one multicast session in the first message includes a multicast session joined by the terminal device, it indicates that one or more multicast sessions joined by the terminal device have been activated, or it is understood that the network side has multicast session data that needs to be sent to the terminal device.

[0162] In the above scheme, if at least one multicast session in the first message sent by the network side includes a multicast session to which the terminal device has joined, it indicates that the network side has multicast session data that needs to be sent to the terminal device, and the terminal device can request the network side to restore the RRC connection to receive the multicast session data. However, if the terminal device is currently in a small data transmission process after receiving the paging message, it means that the wireless access network device knows which cell the terminal device resides in, and there is an available data / signaling path between the terminal device and the wireless access network device. The terminal device has already sent an RRC recovery request message to the network side before receiving the paging message. Therefore, if the network side needs to allow the terminal device to enter the RRC connection state to receive the multicast session, it can send an RRC recovery message to the terminal device. Therefore, after receiving the paging message, if the terminal device is currently in a small data transmission process, it does not need to send an RRC recovery request message to the network side again, but can directly enter the RRC idle state and trigger the RRC connection establishment process, thereby achieving rapid entry into the RRC connection state and receiving the multicast session data, and saving unnecessary energy consumption overhead, reducing the processing complexity of the terminal device, and reducing signaling overhead.

[0163] Because the terminal device will move in the RRC inactive state, if the radio access network device (also known as the serving gNB, receiving gNB, or first radio access network device) to which the terminal device is currently connected is not the last serving gNB (also known as the anchor gNB or second radio access network device), after the terminal device triggers the small data transfer process, the first radio access network device will perform the UE context retrieval process. The first radio access network device sends a UE context retrieval request message to the second radio access network device, indicating a small data transfer (SDT) request, and the second radio access network device decides whether to relocate the UE context (UE context relocation).

[0164] Among them, the last serving wireless access network device or anchor access network device refers to the wireless access network device that last provided services to the terminal device in the RRC connection state before the terminal device entered the RRC inactive state, or the wireless access network device that the terminal device last accessed, or it can be understood as the wireless access network device that maintains the connection between the terminal device and the core network.

[0165] Scenario 1: Small data transmission with context relocation (SDT with UE context relocation).

[0166] If the second radio access network device decides to relocate the complete terminal device context, the complete terminal device context is sent to the first radio access network device, which is called small data transmission with context relocation. In this case, the uplink small data is sent from the first radio access network device to the user plane function (UPF) network element. After the small data transmission is completed, the first radio access network device can send an RRC release (RRCRelease) message to the terminal device to release the terminal device to the RRC inactive state or RRC idle state. If downlink non-small data / signaling arrives, or uplink non-small data arrives during the small data transmission process, the first radio access network device can send an RRC resume (RRCResume) message to the terminal device to return the terminal device to the RRC connected state.

[0167] Scenario 2: small data transmission without context relocation (SDT without UE context relocation).

[0168] If the second radio access network device decides not to relocate the complete UE context, it sends a partial UE context to the first radio access network device, which contains the SDT radio link control (RLC) context information required to handle the small data transmission. This is called small data transmission without context relocation. The second radio access network device maintains the packet data convergence protocol (PDCP) entity, while the first radio access network device establishes the SDT-related RLC context and forwards the small data / signaling to the second radio access network device, which then sends it to the core network.

[0169] The following, combined with the embodiments of Figures 3(a) to 3(e), describes how to define the behavior of the terminal device, the first radio access network device, and the second radio access network device when a terminal device is performing small data transmission in an RRC inactive state and one or more multicast sessions to which the terminal device is affiliated are activated, i.e., when multicast services need to be transmitted. The embodiments of Figures 3(a) to 3(e) below are for the aforementioned scenario 2, and Figure 3(f) below is for the aforementioned scenario 1.

[0170] It should be noted that the following embodiments of FIG. 3( a ) to FIG. 3( f ) can be implemented independently, or can be combined with the aforementioned embodiment of FIG. 2 or FIG. 3 , and this application does not limit this.

[0171] FIG3( a ) is a flow chart of a wireless communication method provided in an embodiment of the present application. The method includes the following steps:

[0172] Step 301a: The first terminal device sends an RRC recovery request message to the first radio access network device.

[0173] The RRC recovery request message is used to trigger a small data transmission (SDT).

[0174] For example, the RRC recovery request message is carried in the random access message 3 (MSG3) or random access message A (MSGA) sent by the first terminal device.

[0175] It should be noted that the name of the RRC recovery request message may also change, such as being called RRC message, RRC request message, etc.

[0176] The first terminal device supports receiving multicast services in an RRC inactive state, and the first terminal device has joined one or more multicast sessions. In this application, multicast sessions, multicast services, and multicast can be replaced with each other in some places and have the same meaning.

[0177] Step 302a: The first radio access network device sends a context request message to the second radio access network device.

[0178] The context request message is also called a retrieve UE context request (RETRIEVE UE CONTEXT REQUEST) message, a context retrieval request message, or a retrieval request message, etc. A unified description is given here and no further details are given later.

[0179] The context request message is used to request to obtain the context related to small data transmission of the first terminal device, also known as small data transmission context.

[0180] Step 303a: The second radio access network device sends the partial context (PARTIAL UE CONTEXT) of the first terminal device to the first radio access network device.

[0181] The partial context includes a context for small data transmission (SDT related context).

[0182] The small data transmission context of the first terminal device is part of the terminal device context of the first terminal device. The terminal device context of the first terminal device is also called the full context (full UE context) of the first terminal device.

[0183] Exemplarily, the partial context is carried in a partial context transfer (PARTIAL UE CONTEXT TRANSTER) message and sent to the first radio access network device.

[0184] Step 304a: The first radio access network device receives a first paging message.

[0185] The first paging message comes from a second radio access network device or a core network device. For example, if the first paging message comes from the second radio access network device, the first paging message may also be referred to as a RAN multicast group paging message. For example, if the first paging message comes from an access and mobility management function (AMF) network element, the first paging message may also be referred to as a multicast group paging message. This is explained here for simplicity and will not be further elaborated.

[0186] The first paging message includes the identifier of one or more multicast sessions, and the first paging message is used to notify the activation of one or more multicast sessions. Optionally, the first paging message also includes information for paging the terminal device, which can be the location where the paging is sent, or information for determining the location where the paging is sent, or information for determining the paging occasion. The information for paging the terminal device is determined based on the identifier of the terminal device that joins the at least one multicast session. Exemplarily, the information for paging the terminal device is the value of the terminal device's identifier 5G-S-TMSI modulo 1024.

[0187] Step 305a: The first radio access network device sends a second paging message.

[0188] The second paging message is obtained based on the first paging message. The second paging message indicates that at least one multicast session is activated. That is, it indicates that at least one multicast session is in an activated state or is in an activated state, or indicates that at least one multicast session is converted from an inactivated state to an activated state. This is explained here uniformly and will not be repeated later. The at least one multicast session may be the same as one or more multicast sessions in the first paging message, or may be a subset of one or more multicast sessions in the first paging message. In another implementation method, the first wireless access network device may receive a first paging message from the second wireless access network device and another first paging message from the core network device, and then obtain identifiers of some multicast sessions from the two first paging messages respectively, and generate a second paging message based on the obtained identifiers of the multicast sessions.

[0189] In one possible manner, the second paging message is also used to instruct the terminal device in the RRC connected state to receive the at least one multicast session. That is, the terminal device in the RRC connected state can receive the at least one multicast session, and the terminal device in the RRC non-connected state cannot receive the at least one multicast session. Or it can also be understood as: the at least one multicast session is a multicast session provided for the terminal device in the RRC connected state. Or it can also be understood as: the at least one multicast session is a multicast session received by the terminal device in the RRC connected state. Exemplarily, the second paging message includes a first multicast session identifier list, the first multicast session identifier list indicates the identifier of at least one activated multicast session, and the multicast session indicated by the first multicast session identifier list is a multicast session received in the RRC connected state.

[0190] In another possible embodiment, the second paging message is also used to indicate that the at least one multicast session is a multicast session received by a terminal device in an RRC connected state or an RRC non-connected state. That is, the second paging message also indicates whether each multicast session in the at least one multicast session is received by a terminal device in an RRC connected state or a terminal device in a non-RRC connected state. Exemplarily, the second paging message includes a second multicast session identifier list, and the second multicast session identifier list includes an identifier of at least one activated multicast session and indication information corresponding to each multicast session, and the indication information is used to indicate that the multicast session is a multicast session received in an RRC connected state or an RRC non-connected state, and the RRC non-connected state can be an RRC inactive state and / or an RRC idle state. For example, taking the indication information as 1-bit information, when the indication information is 1, it indicates that the multicast session is a multicast session received in an RRC connected state, and when the indication information is 0, it indicates that the multicast session is a multicast session received in a non-RRC connected state. Assume that the second multicast session identifier list includes the identifier of multicast session 1, the identifier of multicast session 2, the indication information corresponding to multicast session 1, and the indication information corresponding to multicast session 2, and the indication information corresponding to multicast session 1 is 0, and the indication information corresponding to multicast session 2 is 1, so multicast session 1 is received by a terminal device in a non-RRC connected state, and multicast session 2 is received by a terminal device in an RRC connected state. In addition, whether the indication information is included can also be used to indicate whether the multicast session is a multicast session received in an RRC connected state or an RRC non-connected state. For example, when the second multicast session identifier list includes the identifier of multicast session 1 and the indication information corresponding to multicast session 1, it indicates that multicast session 1 is a multicast session received in a non-RRC connected state; when the second multicast session identifier list includes the identifier of multicast session 1, it indicates that multicast session 1 is a multicast session received in an RRC connected state.

[0191] Because the first radio access network device does not have a complete terminal device context, after receiving the first paging message, the first radio access network device does not know which terminal device has joined or wants to receive the activated multicast session indicated in the first paging message. Therefore, the first radio access network device can notify the terminal device of the multicast session activation by sending the first paging message. When the second paging message includes information for paging the terminal device (e.g., information for determining the paging occasion), the first radio access network device determines the location to send the first paging message based on the second paging message. When the second paging message does not include information for paging the terminal device, the first radio access network device sends the first paging message on all paging occasions in at least one default paging cycle.

[0192] In this scenario, when the first radio access network device expects the terminal device to enter the RRC connected state to receive the above-mentioned activated multicast session, because the first radio access network device cannot determine that the terminal device during the SDT process is a terminal device that joins or wants to receive the activated multicast session, it cannot directly send an RRC recovery message to the terminal device to instruct the terminal device to enter the RRC connected state. Here, the terminal device and / or the first radio access network device may support multicast in the RRC inactive state or only support multicast in the RRC connected state, which is not limited by the present invention.

[0193] Step 306a: The first terminal device sends indication information to the first radio access network device.

[0194] The first terminal device monitors the paging and, if a second paging message is received, and the second paging message indicates that at least one multicast session to which the first terminal device has joined is activated, sends indication information to the first wireless access network device, where the indication information includes a data indication indicating non-small data transmission and / or a multicast cause value. The multicast cause value is also referred to as a multicast cause value or a multicast-related cause value, and the multicast cause value can also be understood as an RRC recovery cause value related to multicast.

[0195] Specifically, non-small data transmission data indication (nonSDT-DataIndication) is used to indicate that during the small data transmission process, data and / or signaling have arrived on the non-small data transmission radio bearer. The arrival of the above-mentioned data and / or signaling can be understood as uplink data and / or signaling arriving or about to arrive at the first terminal device, and can also be understood as downlink data and / or signaling arriving or about to arrive at the first terminal device.

[0196] Specifically, the multicast cause value may indicate that the at least one multicast session includes a multicast session to which the first terminal device has joined, or that the multicast session to which the first terminal device has joined has been activated, or that the first terminal device has entered an RRC connection state to receive multicast. The multicast cause value may also be a multicast-related access type, such as MBS-access.

[0197] Exemplarily, the indication information may be in user assistance information (UE assistant information, UAI), or information carried in UAI.

[0198] The first terminal device is in the SDT process.

[0199] Step 307a: The first radio access network device sends a context request message to the second radio access network device according to the instruction information.

[0200] When the first wireless access network device receives the indication information, it determines that the multicast session of the first terminal device is activated, that is, the first terminal device expects to enter the RRC connection state to receive the activated multicast session. Therefore, the first wireless access network device sends a context request message to the second wireless access network device to request the complete context of the first terminal device.

[0201] Step 308a: The second radio access network device sends the terminal device context of the first terminal device to the first radio access network device.

[0202] The terminal device context is the complete context of the terminal device (full UE context).

[0203] Exemplarily, the terminal device context is carried in a context response message and sent to the first radio access network device. The context response message is also called a retrieve UE context response (RETRIEVE UE CONTEXT RESPONSE) message, a context retrieval response message, or a retrieval response message. This is explained here and will not be repeated later.

[0204] Step 309a: The first radio access network device sends an RRC recovery message to the first terminal device.

[0205] The RRC recovery message is used to restore the RRC connection of the first terminal device.

[0206] In the above scheme, when the first terminal device is transmitting small data, if the first terminal device receives a second paging message indicating that one or some multicast sessions it has joined are activated, and indicates that the multicast session is received in the RRC connected state, the first terminal device sends an indication information to the first wireless access network device, so that the first wireless access network device determines that the first terminal device is a terminal device that expects to enter the RRC connected state to receive the activated multicast session, and then retrieves the complete context of the terminal device from the last serving access network device (the second wireless access network device), and instructs the first terminal device to restore the RRC connected state, which can avoid unnecessary signaling overhead and help the first terminal device enter the RRC connected state faster to start receiving the multicast session.

[0207] FIG3( b ) is a flow chart of a wireless communication method provided in an embodiment of the present application. The method includes the following steps:

[0208] Step 301b: The first terminal device sends an RRC recovery request message to the first radio access network device.

[0209] The RRC recovery request message is used to trigger SDT.

[0210] For example, the RRC recovery request message is carried in the random access message 3 (MSG3) or random access message A (MSGA) sent by the first terminal device.

[0211] It should be noted that the name of the RRC recovery request message may also change, such as being called RRC message, RRC request message, etc.

[0212] The first terminal device supports receiving multicast services in an RRC inactive state, and the first terminal device joins one or more multicast sessions.

[0213] Step 302b: The first radio access network device sends a context request message to the second radio access network device.

[0214] The context request message is used to request to obtain the context of the first terminal device for small data transmission. In a possible implementation, the context request message includes a small data transmission indication field.

[0215] Step 303b: The second radio access network device sends a partial context of the first terminal device to the first radio access network device, including a small data transmission context and a multicast-related context.

[0216] The small data transmission context and multicast-related context of the first terminal device are part of the terminal device context of the first terminal device, and the terminal device context is also called the complete context of the first terminal device.

[0217] The multicast-related context may be an identifier of the multicast session joined by the first terminal device, or include an identifier of the multicast session joined by the first terminal device, and optionally also include a point-to-multipoint (PTM) configuration of the multicast session.

[0218] Step 304b: The first radio access network device receives a first paging message.

[0219] The first paging message comes from a second radio access network device or a core network device.

[0220] The first paging message includes identifiers of one or more multicast sessions, and is used to notify activation of one or more multicast sessions, which are activated multicast sessions or a subset of activated multicast sessions.

[0221] Step 305b: The first radio access network device sends a second paging message to the first terminal device.

[0222] Because the first wireless access network device obtains the multicast-related context of the first terminal device, it is aware of the multicast session that the first terminal device has joined. If the one or more multicast session identifiers in the first paging message include the identifier of the multicast session that the first terminal device has joined, a second paging message is sent to the first terminal device, where the second paging message indicates that at least one multicast session is activated, and the at least one multicast session includes the multicast session that the first terminal device has joined.

[0223] The second paging message is determined according to the first paging message, or it can be understood that the second paging message is triggered by the first paging message. The second paging message can be the same as or different from the first paging message.

[0224] Step 306b: The first radio access network device sends a context request message to the second radio access network device.

[0225] The first radio access network device determines that at least one activated multicast session includes the multicast session joined by the first terminal device, and then the first radio access network device sends a context request message to the second radio access network device to request the complete context of the first terminal device.

[0226] Step 307b: The second radio access network device sends the terminal device context of the first terminal device to the first radio access network device.

[0227] The terminal device context is the complete context of the first terminal device.

[0228] Exemplarily, the terminal device context is carried in a context response message and sent to the first radio access network device.

[0229] Step 308b: The first radio access network device sends an RRC recovery message to the first terminal device.

[0230] The RRC recovery message is used to restore the RRC connection of the first terminal device.

[0231] In the above-mentioned scheme, in the SDT scenario without context relocation, part of the context sent by the second wireless access network device to the first wireless access network device also includes multicast-related context. The first wireless access network device can determine that one or some multicast sessions joined by the first terminal device are activated based on the multicast-related context. Therefore, when the first wireless access network device expects the first terminal device to enter the RRC connection state to receive the activated multicast session, after retrieving the complete terminal device context from the last serving access network device (the second wireless access network device), the first terminal device is instructed to restore the RRC connection state, which can avoid unnecessary signaling overhead and help the first terminal device to enter the RRC connection state faster and start receiving the multicast session.

[0232] FIG3( c ) is a flow chart of a wireless communication method provided in an embodiment of the present application. The method includes the following steps:

[0233] Steps 301c to 306c are the same as steps 301a to 306a in the embodiment of FIG. 3(a).

[0234] Step 307c: The first radio access network device sends a context confirmation message to the second radio access network device according to the instruction information.

[0235] When the first wireless access network device receives the indication information, it determines that the multicast session of the first terminal device is activated, that is, at least one multicast session identifier in the second paging message includes the identifier of the multicast session joined by the first terminal device. Therefore, the first wireless access network device sends a context confirmation message to the second wireless access network device to request to end the small data transmission of the first terminal device.

[0236] The context confirmation message is also called a RETRIEVE UE CONTEXT CONFIRM message, a context retrieval confirmation message, a retrieval confirmation message, or other names.

[0237] Step 308c: The second radio access network device sends a context failure message to the first radio access network device.

[0238] The context failure message is also called a retrieve UE context failure (RETRIEVE UE CONTEXT FAILURE) message, a context retrieval failure message, a retrieval failure message, or other names.

[0239] The context failure message is used to terminate the small data transmission of the first terminal device.

[0240] The context failure message includes an encapsulated RRC release message, which is used to indicate that the first terminal device is released to the RRC inactive state or the RRC idle state.

[0241] Step 309c: The first radio access network device sends an RRC release message to the first terminal device.

[0242] The first terminal device is released to the RRC inactive state or the RRC idle state according to the RRC release message.

[0243] Step 310c: The first terminal device sends an RRC recovery request message or an RRC establishment request message to the first radio access network device.

[0244] The RRC resume request message is used to indicate entering (or resuming) to the RRC connected state.

[0245] The RRC setup request message is used to request to establish an RRC connection.

[0246] Step 311c: The first radio access network device sends an RRC recovery message to the first terminal device.

[0247] The RRC recovery message is used to restore the RRC connection of the first terminal device.

[0248] The first terminal device receives the RRC recovery message and enters the RRC connection state.

[0249] Before the first radio access network device sends the RRC recovery message to the first terminal device, the first radio access network device obtains the context of the first terminal device from the second radio access network device.

[0250] In the above scheme, during the small data transmission process without context relocation, if one or some multicast sessions joined by the first terminal device are activated, and the first wireless access network device instructs to enter the RRC connection state to receive the activated multicast session, the existing non-SDT data arrival process can be reused on the wireless access network device side, and the SDT is terminated first before the terminal device enters the RRC connection state, which has good compatibility with the existing process.

[0251] Figure 3(d) is a flow chart of a wireless communication method provided in an embodiment of the present application. The method includes the following steps:

[0252] Steps 301d to 305d are the same as steps 301b to 305b in the embodiment of FIG3(b).

[0253] Steps 306d to 310d are the same as steps 307c to 311c in the embodiment of FIG. 3(c).

[0254] In the above scheme, during the small data transmission process without context relocation, if one or some multicast sessions joined by the first terminal device are activated, and the first wireless access network device instructs to enter the RRC connection state to receive the activated multicast session, the existing non-SDT data arrival process can be reused on the wireless access network device side, and the SDT is terminated first before the terminal device enters the RRC connection state, which has good compatibility with the existing process.

[0255] Figure 3(e) is a flow chart of a wireless communication method provided in an embodiment of the present application. The method includes the following steps:

[0256] Steps 301e to 303e are the same as steps 301a to 303a in the embodiment of FIG. 3(a).

[0257] Step 304e: The second radio access network device sends the terminal device context of the first terminal device to the first radio access network device.

[0258] The second radio access network device determines that at least one multicast session is activated, and determines that the terminal devices joining the at least one multicast session include the first terminal device, and then sends the terminal device context of the first terminal device to the first radio access network device.

[0259] The terminal device context of the first terminal device is also referred to as the complete context of the first terminal device.

[0260] Optionally, the terminal device context of the first terminal device includes a multicast-related context of the first terminal device. The multicast-related context may be an identifier of the multicast session joined by the first terminal device, or include an identifier of the multicast session joined by the first terminal device, and optionally also includes a PTM configuration of the multicast session.

[0261] Step 305e: The first radio access network device receives the first paging message.

[0262] The first paging message comes from a second radio access network device or a core network device.

[0263] The first paging message includes identifiers of one or more multicast sessions, and is used to notify activation of one or more multicast sessions, which are activated multicast sessions or a subset of activated multicast sessions.

[0264] The order of step 304e and step 305e is not limited.

[0265] Step 306e: The first radio access network device sends a second paging message to the first terminal device.

[0266] This step is optional.

[0267] Since the first wireless access network device obtains the terminal device context of the first terminal device, it determines that one or some multicast sessions joined by the first terminal device are activated based on the above-mentioned first paging message and the terminal device context of the first terminal device, and then sends a second paging message to the first terminal device. The second paging message instructs the first terminal device to enter the RRC connection state to receive multicast services.

[0268] The second paging message may be the same as or different from the first paging message.

[0269] Step 307e: The first radio access network device sends an RRC recovery message to the first terminal device.

[0270] The RRC recovery message is used to restore the RRC connection of the first terminal device.

[0271] In one implementation method, step 307e may also be replaced by steps 308d to 310d in the embodiment of FIG3(d).

[0272] The above solution avoids the unnecessary inclusion of multicast-related context in the partial context transmission triggered by SDT, because a multicast session received by the terminal device may not necessarily be activated during the SDT process. This can reduce signaling overhead on the interface between radio access network devices. In an SDT scenario without context relocation, since the second radio access network device is a network device that stores the complete context of the terminal device, it can send the terminal device context of the first terminal device to the first radio access network device only if it determines that at least one multicast session that the first terminal device has joined or wants to receive is activated, thereby reducing signaling overhead and storage overhead of the first radio access network device.

[0273] Figure 3(f) is a flow chart of a wireless communication method provided in an embodiment of the present application. The method includes the following steps:

[0274] Step 301f, the first terminal device sends an RRC recovery request message to the first radio access network device.

[0275] The RRC recovery request message is used to trigger SDT.

[0276] For example, the RRC recovery request message is carried in the random access message 3 (MSG3) or random access message A (MSGA) sent by the first terminal device.

[0277] It should be noted that the name of the RRC recovery request message may also change, such as being called RRC message, RRC request message, etc.

[0278] The first terminal device supports receiving multicast services in an RRC inactive state, and the first terminal device joins one or more multicast sessions.

[0279] Step 302f: The first radio access network device sends a context request message to the second radio access network device.

[0280] The context request message is used to obtain the context of the first terminal device.

[0281] Step 303f: The second radio access network device sends the terminal device context of the first terminal device to the first radio access network device.

[0282] The terminal device context of the first terminal device is also referred to as the complete context of the first terminal device.

[0283] The terminal device context includes a multicast-related context, which may be an identifier of the multicast session joined by the first terminal device, or include an identifier of the multicast session joined by the first terminal device, and optionally also include a PTM configuration of the multicast session.

[0284] Step 304f: The first radio access network device receives the first paging message.

[0285] The first paging message comes from a second radio access network device or a core network device.

[0286] The first paging message includes identifiers of one or more multicast sessions, and the first paging message instructs terminal devices that have joined the one or more multicast sessions to enter an RRC connected state to receive multicast. The one or more multicast sessions are also activated multicast sessions, or a subset of activated multicast sessions.

[0287] Step 305f: The first radio access network device sends an RRC recovery message to the first terminal device.

[0288] The RRC recovery message is used to restore the RRC connection of the first terminal device.

[0289] The first wireless access network device determines that the multicast session joined by the first terminal device is activated based on the multicast-related context of the first terminal device and the first paging message, and then sends an RRC recovery message to the first terminal device.

[0290] In one implementation method, step 305f may also be replaced by steps 308d to 310d in the embodiment of FIG. 3( d ).

[0291] In the above scheme, during the small data transmission process with context relocation, if one or some multicast sessions joined by the first terminal device are activated, and the first wireless access network device instructs to enter the RRC connection state to receive the activated multicast session, the first terminal device is triggered to enter the RRC connection state, thereby helping the first terminal device to correctly receive the multicast service of the multicast session.

[0292] In another embodiment, if the first terminal device supports receiving multicast (or multicast service) in the RRC inactive state, that is, the first terminal device joins the multicast session, if the first terminal device receives a paging message during small data transmission, and the paging message is used to instruct the first terminal device to remain in the RRC inactive state to receive the multicast service, then the first terminal device remains in the RRC inactive state according to the paging message, and receives the multicast service in the RRC inactive state.

[0293] It is understandable that in order to implement the functions in the above embodiments, the terminal device (or first terminal device) includes hardware structures and / or software modules corresponding to the execution of each function. It should be readily apparent to those skilled in the art that, in combination with the units and method steps of each example described in the embodiments disclosed in this application, the present application can be implemented in the form of hardware or a combination of hardware and computer software. Whether a function is executed in the form of hardware or computer software driving hardware depends on the specific application scenario and design constraints of the technical solution.

[0294] Figures 4 and 5 are schematic diagrams of possible communication devices provided in embodiments of the present application. These communication devices can be used to implement the functions of the terminal device in the above-mentioned method embodiments, thereby also achieving the beneficial effects of the above-mentioned method embodiments. In the embodiments of the present application, the communication device can be one of the terminal devices 120a-120j shown in Figure 1, or a module (such as a chip) applied to the terminal device.

[0295] The communication device 400 shown in Figure 4 includes a processing unit 410 and a transceiver unit 420. The communication device 400 is used to implement the functions of the terminal device in the above method embodiment.

[0296] When the communication device 400 is used to implement the function of the first terminal device in the above method embodiment, the transceiver unit 420 is used to receive a paging message, which includes identification information of at least one multicast session, and the first terminal device is in an RRC inactive state; the processing unit 410 is used to trigger the RRC connection recovery process when a first condition is met; wherein the first condition includes: the at least one multicast session includes a multicast session joined by the first terminal device, and the first terminal device is not in a small data transmission process; or, the first condition includes: the paging message also includes identification information of at least one terminal device, the at least one multicast session includes a multicast session joined by the first terminal device, the terminal device is not in a small data transmission process, and the identification information of the at least one terminal device does not include the identification information of the first terminal device; the small data transmission is the transmission of data and / or signaling by the first terminal device in the RRC inactive state, with a data volume lower than a preset threshold.

[0297] In a possible implementation method, the processing unit 410 is configured to send an RRC recovery request message to the radio access network device through the transceiver unit 420.

[0298] In one possible implementation method, the processing unit 410 is also used to determine not to trigger the RRC connection recovery process when the second condition is met; wherein the second condition includes: the at least one multicast session includes the multicast session joined by the first terminal device, and the first terminal device is in a small data transmission process.

[0299] In one possible implementation method, the transceiver unit 420 is also used to send indication information to the wireless access network device, which indicates that data and / or signaling have arrived on the wireless bearer for non-small data transmission, or that the at least one multicast session includes the multicast session joined by the first terminal device, or that the multicast session joined by the first terminal device has been activated.

[0300] In one possible implementation method, the processing unit 410 is also used to enter the RRC idle state and trigger the RRC connection establishment process when a third condition is met; wherein, the third condition includes: the paging message also includes identification information of at least one terminal device, the at least one multicast session includes the multicast session joined by the first terminal device, the terminal device is not in a small data transmission process, and the identification information of the at least one terminal device includes the identification information of the first terminal device.

[0301] When the communication device 400 is used to implement the functions of the terminal device in the above method embodiment, the processing unit 410 is used for the terminal device to determine whether to monitor the paging message for group notification based on the status of small data transmission. The terminal device is in an RRC inactive state, and the paging message includes identification information of at least one multicast session; wherein the terminal device has joined one or more multicast sessions, and the small data transmission is the transmission of data and / or signaling by the first terminal device in the RRC inactive state with a data volume lower than a preset threshold.

[0302] In a possible implementation method, the processing unit 410 is specifically configured to monitor the paging message when the terminal device is not performing small data transmission.

[0303] In a possible implementation method, the processing unit 410 is specifically configured to not monitor the paging message when the terminal device is transmitting small data.

[0304] In a possible implementation method, the processing unit 410 is specifically configured to not monitor the paging message when the terminal device is transmitting small data and the terminal device does not support receiving multicast sessions in the RRC inactive state.

[0305] In one possible implementation method, the transceiver unit 420 is used to receive an RRC message, which includes identification information of the at least one multicast session, and the RRC message is used to indicate that the at least one multicast session has been activated; when the at least one multicast session includes the multicast session joined by the terminal device, the terminal device receives the multicast session joined by the terminal device in an RRC inactive state.

[0306] In a possible implementation method, the processing unit 410 is specifically configured to monitor the paging message when the terminal device is transmitting small data and the terminal device supports receiving multicast sessions in an RRC inactive state.

[0307] In one possible implementation method, the processing unit 410 is specifically used to monitor the paging message when the terminal device is performing small data transmission, the terminal device supports receiving multicast sessions in the RRC inactive state, and the cell where the terminal device resides supports providing multicast sessions for terminal devices in the inactive state.

[0308] When the communication device 400 is used to implement the functions of the terminal device in the above method embodiment, the transceiver unit 420 is used to receive a first message, which includes identification information of at least one multicast session, and the terminal device is in an RRC inactive state; the processing unit 410 is used to enter the RRC idle state and trigger the RRC connection establishment process when the at least one multicast session includes a multicast session joined by the terminal device and the terminal device is in a small data transmission process; wherein the small data transmission is the transmission of data and / or signaling by the terminal device in the RRC inactive state with a data volume lower than a preset threshold.

[0309] In a possible implementation method, the first message is an RRC message or a paging message.

[0310] When the communication device 400 is used to implement the function of the first wireless access network device in the above method embodiment, the processing unit 410 is used to control the transceiver unit 420 to send a second paging message, and the second paging message indicates that at least one multicast session is activated; receive indication information from the first terminal device, and the indication information includes an indication of non-small data transmission data, and / or a multicast reason value; wherein, the at least one multicast session includes a multicast session joined by the first terminal device, and the first terminal device is in a radio resource control RRC inactive state and is in a small data transmission process; the first wireless access network device is the service wireless access network device of the first terminal device.

[0311] In one possible implementation method, the processing unit 410 is also used to control the transceiver unit 420 to send an RRC recovery message to the first terminal device after receiving indication information from the first terminal device, and the RRC recovery message is used to restore the RRC connection of the first terminal device.

[0312] In one possible implementation method, the processing unit 410 is also used to control the transceiver unit 420 to send an RRC release message to the first terminal device before sending an RRC recovery message to the first terminal device, and the RRC release message is used to indicate that the first terminal device enters an RRC inactive state or an RRC idle state; the first wireless access network device receives an RRC recovery request message from the first terminal device, and the RRC recovery request message is used to request to enter an RRC connection state; or, receives an RRC establishment request message from the first terminal device, and the RRC establishment request message is used to request to establish an RRC connection.

[0313] In one possible implementation method, the second paging message is also used to indicate that a terminal device in an RRC connected state receives the at least one multicast session; or, the second paging message is also used to indicate that the at least one multicast session is a multicast session received by a terminal device in an RRC connected state or an RRC non-connected state.

[0314] In one possible implementation method, the processing unit 410 is further configured to control the transceiver unit 420 to receive a first paging message before sending the second paging message, wherein the first paging message is used to notify activation of one or more multicast sessions; and determine the second paging message based on the first paging message.

[0315] In one possible implementation method, the processing unit 410 is used to control the transceiver unit 420 to receive a first paging message, specifically including: receiving the first paging message from a second wireless access network device or a core network device, and the second wireless access network device is the last serving wireless access network device of the first terminal device in the RRC connection state.

[0316] In a possible implementation method, the first paging message also includes information for paging the terminal device; the processing unit 410 is also used to control the transceiver unit 420 to send a second paging message, specifically including: sending the second paging message according to the information for paging the terminal device.

[0317] In one possible implementation method, the multicast reason value indicates that the at least one multicast session includes the multicast session joined by the first terminal device, or indicates that the multicast session joined by the first terminal device is activated, or indicates that the first terminal device enters the RRC connection state to receive multicast.

[0318] In one possible implementation method, the processing unit 410 is also used to control the transceiver unit 420 to send a context request message to the second wireless access network device after receiving the indication information from the first terminal device, wherein the context request message is used to request the terminal device context of the first terminal device, and the second wireless access network device is the last serving wireless access network device of the first terminal device in the RRC connection state; and receive the terminal device context of the first terminal device from the second wireless access network device.

[0319] When the communication device 400 is used to implement the function of the first wireless access network device in the above method embodiment, the transceiver unit 420 is used to receive a first paging message, the first paging message includes one or more multicast session identifiers, the first paging message is used to notify the activation of the one or more multicast sessions, and the first wireless access network device is a first terminal device serving wireless access network device; wherein, the first terminal device is in a radio resource control RRC inactive state and is in a small data transmission process; the processing unit 410 is used to obtain a multicast-related context of the first terminal device, the multicast-related context includes an identifier of the multicast session joined by the first terminal device; the transceiver unit 420 is also used to send an RRC recovery message to the first terminal device, the one or more multicast session identifiers include an identifier of the multicast session joined by the first terminal device, and the RRC recovery message is used to restore the RRC connection of the first terminal device.

[0320] In one possible implementation method, the processing unit 410 is also used to determine a second paging message based on the first paging message before the transceiver unit 420 sends an RRC recovery message to the first terminal device, and the second paging message indicates that at least one multicast session is activated, and the at least one multicast session includes the multicast session joined by the first terminal device; the transceiver unit 420 is also used to send the second paging message.

[0321] In one possible implementation method, the transceiver unit 420 is also used to send an RRC release message to the first terminal device before sending an RRC recovery message to the first terminal device, and the RRC release message is used to instruct the first terminal device to enter an RRC inactive state or an RRC idle state; receive an RRC recovery request message from the first terminal device, and the RRC recovery request message is used to request to enter an RRC connected state; or receive an RRC establishment request message from the first terminal device, and the RRC establishment request message is used to request to establish an RRC connection.

[0322] In one possible implementation method, the transceiver unit 420 is used to receive a first paging message, specifically including: receiving the first paging message from a second wireless access network device or a core network device, and the second wireless access network device is the last serving wireless access network device of the first terminal device in the RRC connection state.

[0323] In one possible implementation method, the processing unit 410 is used to obtain the multicast-related context of the first terminal device, specifically including: sending a first context request message to the second wireless access network device through the transceiver unit 420, wherein the first context request message is used to request to obtain the context of the first terminal device for small data transmission; receiving a partial context of the first terminal device from the second wireless access network device, wherein the partial context of the first terminal device includes a context related to small data transmission and the multicast-related context, and the second wireless access network device is the last serving wireless access network device of the first terminal device in the RRC connection state.

[0324] In one possible implementation method, the transceiver unit 420 is further used to send a second context request message to the second wireless access network device, where the second context request message is used to request the context of the first terminal device; and receive the terminal device context of the first terminal device from the second wireless access network device.

[0325] In one possible implementation method, the processing unit 410 is used to obtain the multicast-related context of the first terminal device, specifically including: receiving the terminal device context of the first terminal device from the second wireless access network device through the transceiver unit 420, the terminal device context including the multicast-related context, and the second wireless access network device is the last serving wireless access network device of the first terminal device in the RRC connection state.

[0326] When the communication device 400 is used to implement the function of the second wireless access network device in the above method embodiment, the processing unit 410 is used to determine whether the identifiers of the one or more activated multicast sessions include the identifier of the multicast session joined by the first terminal device; the transceiver unit 420 is used to send the terminal device context of the first terminal device to the first wireless access network device when the identifiers of the one or more activated multicast sessions include the identifier of the multicast session joined by the first terminal device; wherein the first terminal device is in a radio resource control RRC inactive state and is in a small data transmission process; the first wireless access network device is the serving wireless access network device of the first terminal device, and the second wireless access network device is the last serving wireless access network device of the first terminal device in the RRC connected state.

[0327] In a possible implementation method, the terminal device context includes a multicast-related context of the first terminal device.

[0328] In one possible implementation method, the transceiver unit 420 is also used to receive a context request message from the first wireless access network device before sending the terminal device context of the first terminal device to the first wireless access network device, wherein the context request message is used to request to obtain the context of the terminal device for small data transmission; and send a partial context of the first terminal device to the first wireless access network device, wherein the partial context of the first terminal device includes a context related to small data transmission.

[0329] In a possible implementation method, the method further includes: the second radio access network device sending a first paging message to the first radio access network device, where the first paging message is used to notify the activation of the one or more multicast sessions.

[0330] In a possible implementation method, the first paging message includes identifiers of the one or more multicast sessions.

[0331] When the communication device 400 is used to implement the function of the first terminal device in the above method embodiment, the processing unit 410 is used to control the transceiver unit 420 to receive a second paging message from the first wireless access network device, where the second paging message indicates that at least one multicast session is activated; and to send indication information to the first wireless access network device, where the indication information includes an indication of non-small data transmission data, and / or a multicast reason value; wherein the at least one multicast session includes a multicast session joined by the first terminal device, and the first terminal device is in a radio resource control RRC inactive state and is in a small data transmission process; the first wireless access network device is a serving wireless access network device of the first terminal device.

[0332] In one possible implementation method, the processing unit 410 is also used to control the transceiver unit 420 to send indication information to the first wireless access network device, and then receive an RRC recovery message from the first wireless access network device, where the RRC recovery message is used to restore the RRC connection of the first terminal device.

[0333] In one possible implementation method, the processing unit 410 is also used to control the transceiver unit 420 to receive an RRC release message from the first radio access network device before receiving the RRC recovery message from the first radio access network device, wherein the RRC release message is used to instruct the first terminal device to enter an RRC inactive state or an RRC idle state; send an RRC recovery request message to the first radio access network device, wherein the RRC recovery request message is used to request to enter an RRC connected state; or send an RRC establishment request message to the first radio access network device, wherein the RRC establishment request message is used to request to establish an RRC connection.

[0334] In one possible implementation method, the second paging message is also used to indicate that a terminal device in an RRC connected state receives the at least one multicast session; or, the second paging message is also used to indicate that the at least one multicast session is a multicast session received by a terminal device in an RRC connected state or an RRC non-connected state.

[0335] In one possible implementation method, the multicast reason value indicates that the at least one multicast session includes the multicast session joined by the first terminal device, or indicates that the multicast session joined by the first terminal device is activated, or indicates that the first terminal device enters the RRC connection state to receive multicast.

[0336] For a more detailed description of the processing unit 410 and the transceiver unit 420, reference can be made to the relevant description in the above method embodiment, which will not be repeated here.

[0337] As shown in Figure 5, communication device 500 includes a processor 510 and an interface circuit 520. Processor 510 and interface circuit 520 are coupled to each other. It is understood that interface circuit 520 can be a transceiver or an input / output interface. Optionally, communication device 500 may also include a memory 530 for storing instructions executed by processor 510, input data required by processor 510 to execute instructions, or data generated after processor 510 executes instructions.

[0338] When the communication device 500 is used to implement the above method embodiment, the processor 510 is used to implement the functions of the above processing unit 410 , and the interface circuit 520 is used to implement the functions of the above transceiver unit 420 .

[0339] When the communication device is a chip used in a terminal device, the terminal device chip implements the functions of the terminal device in the above method embodiments. The terminal device chip receives information from other modules in the terminal device (such as a radio frequency module or antenna), and the information is sent to the terminal device by the wireless access network device; or the terminal device chip sends information to other modules in the terminal device (such as a radio frequency module or antenna), and the information is sent to the wireless access network device by the terminal device.

[0340] It is understood that the processor in the embodiments of the present application may be a central processing unit (CPU), or may be other general-purpose processors, digital signal processors (DSP), application-specific integrated circuits (ASIC), field programmable gate arrays (FPGA), or other programmable logic devices, transistor logic devices, hardware components, or any combination thereof. The general-purpose processor may be a microprocessor or any conventional processor.

[0341] The method steps in the embodiments of the present application can be implemented by hardware or by a processor executing software instructions. The software instructions can be composed of corresponding software modules, and the software modules can be stored in random access memory, flash memory, read-only memory, programmable read-only memory, erasable programmable read-only memory, electrically erasable programmable read-only memory, registers, hard disk, mobile hard disk, compact disc read-only memory (CD-ROM) or any other form of storage medium well known in the art. An exemplary storage medium is coupled to the processor so that the processor can read information from the storage medium and write information to the storage medium. Of course, the storage medium can also be an integral part of the processor. The processor and the storage medium can be located in an ASIC. In addition, the ASIC can be located in a wireless access network device or a terminal device. Of course, the processor and the storage medium can also exist as discrete components in a wireless access network device or a terminal device.

[0342] In the above embodiments, they can be implemented in whole or in part by software, hardware, firmware, or any combination thereof. When implemented using software, they can be implemented in whole or in part in the form of a computer program product. The computer program product includes one or more computer programs or instructions. A computer program (English: Computer Program) refers to a set of instructions that instruct an electronic computer or other device with message processing capabilities to perform each step of the action, usually written in a certain programming language and running on a certain target architecture. When the computer program or instructions are loaded and executed on a computer, the processes or functions described in the embodiments of the present application are executed in whole or in part. The computer can be a general-purpose computer, a special-purpose computer, a computer network, a wireless access network device, a terminal device, or other programmable device. The computer program or instructions can be stored in a computer-readable storage medium or transmitted from one computer-readable storage medium to another computer-readable storage medium. For example, the computer program or instructions can be transmitted from one website, computer, server, or data center to another website, computer, server, or data center via wired or wireless means. The computer-readable storage medium can be any available medium that can be accessed by a computer or a data storage device such as a server or data center that integrates one or more available media. The available medium may be a magnetic medium, such as a floppy disk, a hard disk, or a magnetic tape; an optical medium, such as a digital video disk; or a semiconductor medium, such as a solid-state drive. The computer-readable storage medium may be a volatile or non-volatile storage medium, or may include both volatile and non-volatile types of storage media.

[0343] In the various embodiments of the present application, unless otherwise specified or there is a logical conflict, the terms and / or descriptions between different embodiments are consistent and can be referenced by each other. The technical features in different embodiments can be combined to form new embodiments according to their inherent logical relationships.

[0344] In this application, "at least one" means one or more, and "more" means two or more. "And / or" describes the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can mean: A exists alone, A and B exist at the same time, and B exists alone, where A and B can be singular or plural. In the text description of this application, the character " / " generally indicates that the previous and next related objects are in an "or" relationship; in the formulas of this application, the character " / " indicates that the previous and next related objects are in a "division" relationship.

[0345] It is understood that the various numbers used in the embodiments of this application are merely for ease of description and are not intended to limit the scope of the embodiments of this application. The order of the sequence numbers of the above-mentioned processes does not necessarily imply a specific order of execution; the order of execution of the processes should be determined by their functions and inherent logic.

Claims

1. A wireless communication method, characterized in that: include: The first terminal device receives a paging message, where the paging message includes identification information of at least one multicast session, and the first terminal device is in a radio resource control (RRC) inactive state; When a first condition is met, the first terminal device triggers an RRC connection recovery process; The first condition includes: the at least one multicast session includes a multicast session joined by the first terminal device, and the first terminal device is not in a small data transmission process; or The first condition includes: the paging message further includes identification information of at least one terminal device, the at least one multicast session includes a multicast session joined by the first terminal device, the terminal device is not in a small data transmission process, and the identification information of the at least one terminal device does not include the identification information of the first terminal device; The small data transmission is the transmission of data and / or signaling with a data volume lower than a preset threshold by the first terminal device in an RRC inactive state.

2. The method according to claim 1, wherein The first terminal device triggers an RRC connection recovery process, including: The first terminal device sends an RRC recovery request message to the wireless access network device.

3. The method according to claim 1 or 2, wherein: The method further comprises: When the second condition is met, the first terminal device determines not to trigger the RRC connection recovery process; The second condition includes: the at least one multicast session includes a multicast session joined by the first terminal device, and the first terminal device is in a small data transmission process.

4. The method according to any one of claims 1 to 3, characterized in that The method further comprises: The first terminal device sends indication information to the wireless access network device, where the indication information indicates that data and / or signaling has arrived on the wireless bearer for non-small data transmission, or that the at least one multicast session includes the multicast session joined by the first terminal device.

5. The method according to any one of claims 1 to 4, characterized in that The method further comprises: When the third condition is met, the first terminal device enters the RRC idle state and triggers the RRC connection establishment process; Among them, the third condition includes: the paging message also includes the identification information of at least one terminal device, the at least one multicast session includes the multicast session joined by the first terminal device, the terminal device is not in the small data transmission process, and the identification information of the at least one terminal device includes the identification information of the first terminal device.

6. A wireless communication method, characterized in that: include: The terminal device determines, according to a state of small data transmission, whether to monitor a paging message for group notification, the terminal device being in a radio resource control (RRC) inactive state, and the paging message including identification information of at least one multicast session; The terminal device joins one or more multicast sessions, and the small data transmission is the transmission of data and / or signaling with a data volume lower than a preset threshold by the first terminal device in an RRC inactive state.

7. The method according to claim 6, wherein The terminal device determines whether to monitor a paging message for group notification according to a state of small data transmission, including: When the terminal device is not performing small data transmission, the terminal device monitors the paging message.

8. The method according to claim 6, wherein The terminal device determines whether to monitor a paging message for group notification according to a state of small data transmission, including: When the terminal device is transmitting small data, the terminal device does not monitor the paging message.

9. The method according to claim 8, wherein When the terminal device is transmitting small data, the terminal device does not monitor the paging message, including: When the terminal device is transmitting small data and the terminal device does not support receiving multicast sessions in the RRC inactive state, the terminal device does not monitor the paging message.

10. The method according to claim 8 or 9, characterized in that The method further comprises: The terminal device receives an RRC message, where the RRC message includes identification information of the at least one multicast session, and the RRC message is used to indicate that the at least one multicast session has been activated; When the at least one multicast session includes the multicast session joined by the terminal device, the terminal device receives the multicast session joined by the terminal device in an RRC inactive state.

11. The method according to claim 6, wherein The terminal device determines whether to monitor a paging message for group notification according to a state of small data transmission, including: When the terminal device is transmitting small data and the terminal device supports receiving multicast sessions in the RRC inactive state, the terminal device monitors the paging message.

12. The method according to claim 11, wherein The terminal device is performing small data transmission and the terminal device supports receiving a multicast session in an RRC inactive state, and the terminal device monitors the paging message, including: When the terminal device is performing small data transmission, the terminal device supports receiving multicast sessions in the RRC inactive state, and the cell where the terminal device resides supports providing multicast sessions for terminal devices in the inactive state, the terminal device monitors the paging message.

13. A wireless communication method, characterized in that: include: The terminal device receives a first message, where the first message includes identification information of at least one multicast session, and the terminal device is in a radio resource control (RRC) inactive state; When the at least one multicast session includes a multicast session joined by the terminal device, and the terminal device is in a small data transmission process, the terminal device enters an RRC idle state and triggers an RRC connection establishment process; The small data transmission refers to the transmission of data and / or signaling with a data volume lower than a preset threshold value performed by the terminal device in an RRC inactive state.

14. The method according to claim 13, wherein The first message is an RRC message or a paging message.

15. A communication device, characterized in that: The method comprises a processor and an interface circuit, wherein the interface circuit is used to receive signals from other communication devices outside the communication device and transmit them to the processor or send signals from the processor to other communication devices outside the communication device, and the processor is used to implement the method according to any one of claims 1 to 5, or to implement the method according to any one of claims 6 to 12, or to implement the method according to claim 13 or 14 through a logic circuit or executing code instructions.

16. A communication system, characterized in that: including a first terminal device and a wireless access network device; The first terminal device is used for a paging message, the paging message including identification information of at least one multicast session, the first terminal device is in a radio resource control (RRC) inactive state; when a first condition is met, an RRC connection recovery process is triggered; The radio access network device is used to send an RRC recovery message to the first terminal device, where the RRC recovery message is used to trigger the first terminal device to enter an RRC connected state; The first condition includes: the at least one multicast session includes a multicast session joined by the first terminal device, and the first terminal device is not in a small data transmission process; or The first condition includes: the paging message further includes identification information of at least one terminal device, the at least one multicast session includes a multicast session joined by the first terminal device, the terminal device is not in a small data transmission process, and the identification information of the at least one terminal device does not include the identification information of the first terminal device; The small data transmission is the transmission of data and / or signaling with a data volume lower than a preset threshold by the first terminal device in an RRC inactive state.

17. The system according to claim 16, wherein: The first terminal device is specifically used to send an RRC recovery request message to a wireless access network device.

18. The system according to claim 16 or 17, wherein: The first terminal device is further configured to determine not to trigger the RRC connection recovery process when the second condition is met; The second condition includes: the at least one multicast session includes a multicast session joined by the first terminal device, and the first terminal device is in a small data transmission process.

19. The system according to any one of claims 16 to 18, characterized in that The first terminal device is also used to send indication information to the wireless access network device, where the indication information indicates that data and / or signaling have arrived on the wireless bearer for non-small data transmission, or that the at least one multicast session includes the multicast session joined by the first terminal device.

20. The system according to any one of claims 16 to 19, characterized in that The first terminal device is further configured to enter the RRC idle state and trigger the RRC connection establishment process when a third condition is met; Among them, the third condition includes: the paging message also includes the identification information of at least one terminal device, the at least one multicast session includes the multicast session joined by the first terminal device, the terminal device is not in the small data transmission process, and the identification information of the at least one terminal device includes the identification information of the first terminal device.

21. A communication system, characterized in that: Including terminal equipment and wireless access network equipment; The radio access network device is configured to send a first message to the terminal device, where the first message includes identification information of at least one multicast session, and the terminal device is in a radio resource control (RRC) inactive state; The terminal device is configured to enter an RRC idle state and trigger an RRC connection establishment process when the at least one multicast session includes a multicast session joined by the terminal device and the terminal device is in a small data transmission process; The small data transmission refers to the transmission of data and / or signaling with a data volume lower than a preset threshold value performed by the terminal device in an RRC inactive state.

22. The system of claim 21, wherein: The first message is an RRC message or a paging message.

23. A wireless communication method, characterized in that: include: The first radio access network device sends a second paging message, where the second paging message indicates that at least one multicast session is activated; The first radio access network device receives indication information from the first terminal device, the indication information including an indication of non-small data transmission data and / or a multicast reason value; wherein the at least one multicast session includes a multicast session joined by the first terminal device, and the first terminal device is in a radio resource control RRC inactive state and in a small data transmission process; The first wireless access network device is a serving wireless access network device of the first terminal device.

24. The method according to claim 23, wherein After the first radio access network device receives the indication information from the first terminal device, the method further includes: The first radio access network device sends an RRC recovery message to the first terminal device, where the RRC recovery message is used to restore the RRC connection of the first terminal device.

25. The method of claim 24, wherein: Before the first radio access network device sends the RRC recovery message to the first terminal device, the method further includes: The first radio access network device sends an RRC release message to the first terminal device, where the RRC release message is used to instruct the first terminal device to enter an RRC inactive state or an RRC idle state; The first radio access network device receives an RRC recovery request message from the first terminal device, where the RRC recovery request message is used to request entry into an RRC connection state; or, the first radio access network device receives an RRC establishment request message from the first terminal device, where the RRC establishment request message is used to request establishment of an RRC connection.

26. The method according to any one of claims 23 to 25, characterized in that The second paging message is further used to instruct a terminal device in an RRC connected state to receive the at least one multicast session; or, The second paging message is further used to indicate that the at least one multicast session is a multicast session received by a terminal device in an RRC connected state or an RRC non-connected state.

27. The method according to any one of claims 23 to 26, characterized in that Before the first radio access network device sends the second paging message, the method further includes: The first radio access network device receives a first paging message, where the first paging message is used to notify activation of one or more multicast sessions; The second paging message is determined according to the first paging message.

28. The method of claim 27, wherein: The first radio access network device receiving a first paging message includes: The first radio access network device receives the first paging message from a second radio access network device or a core network device, where the second radio access network device is the last serving radio access network device of the first terminal device in an RRC connected state.

29. The method according to claim 27 or 28, wherein The first paging message also includes information for paging the terminal device; The first radio access network device sending a second paging message includes: The first radio access network device sends the second paging message according to the information used to paging the terminal device.

30. The method according to any one of claims 23 to 29, wherein The multicast reason value indicates that the at least one multicast session includes the multicast session joined by the first terminal device, or indicates that the multicast session joined by the first terminal device is activated, or indicates that the first terminal device enters the RRC connection state to receive multicast.

31. The method according to any one of claims 23 to 30, wherein After the first radio access network device receives the indication information from the first terminal device, the method further includes: The first radio access network device sends a context request message to the second radio access network device, where the context request message is used to request a terminal device context of the first terminal device, and the second radio access network device is the last serving radio access network device of the first terminal device in the RRC connected state; The first radio access network device receives the terminal device context of the first terminal device from the second radio access network device.

32. A wireless communication method, characterized in that: include: A first radio access network device receives a first paging message, where the first paging message includes identifiers of one or more multicast sessions, and the first paging message is used to notify activation of the one or more multicast sessions. The first radio access network device is a serving radio access network device of a first terminal device; wherein the first terminal device is in a radio resource control (RRC) inactive state and is in a small data transmission process. The first wireless access network device obtains the multicast-related context of the first terminal device, and the multicast-related context The context includes an identifier of the multicast session to which the first terminal device joins; The first wireless access network device sends an RRC recovery message to the first terminal device, where the RRC recovery message is used to restore the RRC connection of the first terminal device. The one or more multicast session identifiers include an identifier of the multicast session joined by the first terminal device.

33. The method of claim 32, wherein: Before the first radio access network device sends the RRC recovery message to the first terminal device, the method further includes: Determining a second paging message according to the first paging message, where the second paging message indicates activation of at least one multicast session, where the at least one multicast session includes a multicast session joined by the first terminal device; Send the second paging message.

34. The method according to claim 32 or 33, wherein Before the first radio access network device sends the RRC recovery message to the first terminal device, the method further includes: The first radio access network device sends an RRC release message to the first terminal device, where the RRC release message is used to instruct the first terminal device to enter an RRC inactive state or an RRC idle state; The first radio access network device receives an RRC recovery request message from the first terminal device, where the RRC recovery request message is used to request entry into an RRC connection state; or, the first radio access network device receives an RRC establishment request message from the first terminal device, where the RRC establishment request message is used to request establishment of an RRC connection.

35. The method according to any one of claims 32 to 34, characterized in that The first radio access network device receiving a first paging message includes: The first radio access network device receives the first paging message from a second radio access network device or a core network device, where the second radio access network device is the last serving radio access network device of the first terminal device in an RRC connected state.

36. The method according to any one of claims 32 to 35, wherein The first wireless access network device obtaining a multicast-related context of the first terminal device includes: The first radio access network device sends a first context request message to the second radio access network device, where the first context request message is used to request obtaining the context of the first terminal device for small data transmission; The first wireless access network device receives a partial context of the first terminal device from the second wireless access network device, where the partial context of the first terminal device includes a context related to small data transmission and a context related to the multicast. The second wireless access network device is the last serving wireless access network device of the first terminal device in the RRC connection state.

37. The method of claim 36, wherein: The method further comprises: The first radio access network device sends a second context request message to the second radio access network device, where the second context request message is used to request to obtain the context of the first terminal device; The first radio access network device receives the terminal device context of the first terminal device from the second radio access network device.

38. The method according to any one of claims 32 to 35, wherein The first radio access network device acquiring a multicast-related context of the first terminal device includes: The first wireless access network device receives the terminal device context of the first terminal device from the second wireless access network device, where the terminal device context includes the multicast-related context. The second wireless access network device is the last serving wireless access network device of the first terminal device in the RRC connection state.

39. A wireless communication method, characterized in that: include: The second radio access network device determines whether the identifiers of the one or more activated multicast sessions include the identifier of the multicast session joined by the first terminal device; When the identifiers of the one or more activated multicast sessions include an identifier of the multicast session joined by the first terminal device, the second radio access network device sends the terminal device context of the first terminal device to the first radio access network device; The first terminal device is in a radio resource control RRC inactive state and is in a small data transmission process; The first radio access network device is the serving radio access network device of the first terminal device, and the second radio access network device is the last serving radio access network device of the first terminal device in the RRC connection state.

40. The method of claim 39, wherein The terminal device context includes the multicast-related context of the first terminal device.

41. The method according to claim 39 or 40, wherein Before the second radio access network device sends the terminal device context of the first terminal device to the first radio access network device, the method further includes: The second radio access network device receives a context request message from the first radio access network device, where the context request message is used to request obtaining a context of the terminal device for small data transmission; The second radio access network device sends a partial context of the first terminal device to the first radio access network device, where the partial context of the first terminal device includes a context related to small data transmission.

42. The method according to any one of claims 39 to 41, wherein The method further comprises: The second radio access network device sends a first paging message to the first radio access network device, where the first paging message is used to notify activation of the one or more multicast sessions.

43. The method of claim 42, wherein: The first paging message includes identifiers of the one or more multicast sessions.

44. A wireless communication method, characterized in that: include: The first terminal device receives a second paging message from the first radio access network device, where the second paging message indicates that at least one multicast session is activated; The first terminal device sends indication information to the first radio access network device, where the indication information includes a non-small data transmission indication and / or a multicast reason value; wherein the at least one multicast session includes a multicast session joined by the first terminal device, and the first terminal device is in a radio resource control RRC inactive state and in a small data transmission process; The first wireless access network device is a serving wireless access network device of the first terminal device.

45. The method of claim 44, wherein: After the first terminal device sends the indication information to the first radio access network device, the method further includes: The first terminal device receives an RRC recovery message from the first radio access network device, where the RRC recovery message is used to restore the RRC connection of the first terminal device.

46. ​​The method of claim 45, wherein Before the first terminal device receives the RRC recovery message from the first radio access network device, the method further includes: The first terminal device receives an RRC release message from the first radio access network device, where the RRC release message is used to instruct the first terminal device to enter an RRC inactive state or an RRC idle state; The first terminal device sends an RRC recovery request message to the first radio access network device, and the RRC recovery request message is used to request to enter the RRC connection state; or, the first terminal device sends an RRC establishment request message to the first radio access network device, and the RRC establishment request message is used to request to establish an RRC connection.

47. The method according to any one of claims 44 to 46, wherein The second paging message is further used to instruct a terminal device in an RRC connected state to receive the at least one multicast session; or, The second paging message is further used to indicate that the at least one multicast session is a multicast session received by a terminal device in an RRC connected state or an RRC non-connected state.

48. The method according to any one of claims 44 to 47, wherein The multicast reason value indicates that the at least one multicast session includes the multicast session joined by the first terminal device, or indicates that the multicast session joined by the first terminal device is activated, or indicates that the first terminal device enters the RRC connection state to receive multicast.

49. A communication device, characterized in that The invention comprises a processor and an interface circuit, wherein the interface circuit is used to receive signals from other communication devices outside the communication device and transmit them to the processor or send signals from the processor to other communication devices outside the communication device, and the processor is used to implement the method as claimed in any one of claims 23 to 31 through a logic circuit or execute code instructions, or to implement the method as claimed in any one of claims 32 to 38, or to implement the method as claimed in any one of claims 39 to 43, or to implement the method as claimed in any one of claims 44 to 48.

50. A communication system, characterized in that It comprises a first radio access network device for implementing the method as claimed in any one of claims 23 to 31, and a first terminal device for implementing the method as claimed in any one of claims 44 to 48.

51. A communication system, characterized in that comprising a first terminal device, and a first radio access network device for implementing the method according to any one of claims 32 to 38; The first terminal device is used to receive an RRC recovery message, and the RRC recovery message is used to restore the RRC connection of the first terminal device.

52. A communication system, characterized in that comprising a first radio access network device, and a second radio access network device for implementing the method according to any one of claims 39 to 43; The first wireless access network device is used to receive the terminal device context of the first terminal device.

53. A computer program product, characterized in that Comprising a computer program which, when executed by a communication device, implements the method according to any one of claims 1 to 5, or is used to implement the method according to any one of claims 6 to 12, or is used to implement the method according to claim 13 or 14, or is used to implement the method according to any one of claims 23 to 31, or is used to implement the method according to any one of claims 32 to 38, or is used to implement the method according to any one of claims 39 to 43, or is used to implement the method according to any one of claims 44 to 48.

54. A computer-readable storage medium, characterized in that The storage medium stores a computer program or instruction, which, when executed by the communication device, implements the method as claimed in any one of claims 1 to 5, or is used to implement the method as claimed in any one of claims 6 to 12, or is used to implement the method as claimed in claim 13 or 14, or is used to implement the method as claimed in any one of claims 23 to 31, or is used to implement the method as claimed in any one of claims 32 to 38, or is used to implement the method as claimed in any one of claims 39 to 43, or is used to implement the method as claimed in any one of claims 44 to 48.

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