A communication method and a communication apparatus for integrated access backhaul (IAB) system

Abstract

This application provides a communication method for an integrated access backhaul (IAB) system, characterized in that the method includes: a child node receiving a first Radio Resource Control (RRC) reconfiguration message from an access network device via a parent node, the first RRC reconfiguration message including an indication of random access exemption; the child node starting a timer; the child node sending a first RRC reconfiguration complete message to the access network device via the parent node; the child node receiving first indication information from the parent node, the first indication information indicating the timer to be stopped; and the child node stopping the timer.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of wireless communication, and in particular to a communication method and a communication device for an integrated access and backhaul (IAB) system. BACKGROUND

[0002] Compared with the fourth generation mobile communication system, the fifth generation (5G) mobile communication system proposes more stringent requirements for all performance indicators of the network. For example, the capacity index is increased by 1000 times, the coverage is wider, and the ultra-high reliability and ultra-low latency are required. The integrated access and backhaul (IAB) system is born at the historic moment. Through a large number of densely deployed nodes, it can provide flexible and convenient access and backhaul services for terminals, improve coverage, and meet the more stringent performance indicators of 5G.

[0003] In a relay system such as an IAB system, due to link quality and other reasons, the relay node may be switched, and the switching of the relay node will affect other nodes or terminals in the IAB system, causing the interruption of service transmission, and greatly reducing the user experience. SUMMARY

[0004] The present application provides a communication method, a communication device and a communication system applied to an integrated access and backhaul (IAB) system, which can make the child node stop the timer in time in the random access-free process, avoid switching failure caused by the timeout of the timer, improve the success rate of switching, reduce the latency of switching, and guarantee the performance of switching.

[0005] The following describes the scheme provided by the embodiments of the present application in combination with the first aspect to the third aspect. It should be noted that the first aspect to the third aspect describe the scheme from the perspective of different network elements, and the contents thereof can be mutually referenced and cited.

[0006] The first aspect of the present application provides a communication method applied to an integrated access and backhaul (IAB) system. The method can be executed by a child node or a chip in the child node. The following takes the execution of the child node as an example for introduction. The method comprises: receiving, by the child node through a parent node, a first radio resource control (RRC) reconfiguration message from an access network device, wherein the first RRC reconfiguration message comprises an indication of random access-free; starting a timer after the child node receives the first RRC reconfiguration message; then sending, by the child node through the parent node, a first RRC reconfiguration complete message to the access network device; receiving, by the child node from the parent node, first indication information, wherein the first indication information indicates to stop the timer; and finally stopping, by the child node, the timer according to the first indication information.

[0007] The first indication information is sent from the parent node to the child node, so that the child node can stop the timer in time, avoid handover failure and cell reselection caused by the timer timeout, reduce the handover delay, and guarantee the communication performance after handover.

[0008] In a possible implementation, the first indication information can indicate to stop the timer in an explicit or implicit manner. Two implicit manners are introduced below.

[0009] Optionally, the first indication information is a first type of medium access control element (MAC CE), and the child node stops the timer by default after receiving the first type of MAC CE.

[0010] Alternatively, the first indication information is a MAC CE carrying a contention resolution identifier. The contention resolution identifier can be the C-RNTI of the child node, or can be the value of one or more bits of the C-RNTI, or the contention resolution identifier can be any value, which is not limited in the present application. The child node can stop the timer after parsing the MAC CE carrying the contention resolution identifier.

[0011] In a possible implementation, the cell radio network temporary identifier (C-RNTI) of the child node before receiving the first RRC reconfiguration message can be the same as the C-RNTI of the child node after receiving the first RRC reconfiguration message.

[0012] Optionally, the first RRC reconfiguration message does not include the C-RNTI of the child node.

[0013] Alternatively, the first RRC reconfiguration message includes second indication information, and the second indication information indicates that the C-RNTI of the child node is unchanged.

[0014] Alternatively, the first RRC reconfiguration message includes the C-RNTI used by the child node before receiving the first RRC reconfiguration message.

[0015] In a possible implementation, the method can further include: receiving, by the parent node, third indication information from the access network device; and then, in response to the third indication information, sending, by the parent node, the first indication information to the child node.

[0016] Optionally, the third indication information includes the identifier of the child node. Since the parent node can have multiple child nodes, the third indication information including the identifier of the child node can facilitate the parent node to know which child node to send the first indication information to.

[0017] In one possible implementation, the access network device is the target access network device during group handover between the child node and the parent node. It is understood that the group undergoing handover includes at least a child node and a parent node, and may also include one or more other nodes. During this group handover, the child node remains connected to its parent node; that is, the parent node of the child node does not change.

[0018] In one possible implementation, the method further includes: after the parent node receives a first RRC reconfiguration message from the access network device or sends it to the child node, the parent node receives a second RRC reconfiguration message from the access network device, and the parent node starts a timer.

[0019] Since the parent node may switch over after receiving the second RRC reconfiguration message, thereby stopping the transmission with the access network device, by having the parent node first receive or send the first RRC reconfiguration message from the access network device to the child node, and then receive the second RRC reconfiguration message, it can be ensured that the parent node sends the first RRC reconfiguration message to the child node, thus guaranteeing the performance of the child node's switchover.

[0020] Optionally, the method may further include: after the parent node receives or sends a first RRC reconfiguration message from the access network device to the child node, the parent node sends a fourth indication message to the source access network device to trigger the source access network device to send a second RRC reconfiguration message to the parent node, wherein the source access network device is the source access network device of the child node and the parent node during the group handover process.

[0021] It is understandable that the second RRC reconfiguration message can be sent by the target access network device to the source access network device, and then sent by the source access network device to the parent node. By sending the fourth indication information to the source access network device through the parent node, it can be ensured that the parent node receives the second RRC reconfiguration message after receiving the first RRC reconfiguration message from the access network device or sending it to the child node.

[0022] In one possible implementation, the child node is a terminal or an IAB node, and the parent node is an IAB node.

[0023] In one possible implementation, the access network device may include a CU; alternatively, the access network device may also include a DU.

[0024] The second aspect of this application provides a communication method applied in an integrated access and backhaul (IAB) system. This method can be executed by a parent node or by a chip within the parent node. The following description uses parent node execution as an example. The method includes: the parent node receiving a first RRC reconfiguration message from the access network device, the first RRC reconfiguration message including an indication of random access exemption; the parent node sending the first RRC reconfiguration message to a child node to trigger the child node to start a timer; the parent node receiving a first RRC reconfiguration completion message from the child node; the parent node sending the first RRC reconfiguration completion message to the access network device; and the parent node sending first indication information to the child node, the first indication information indicating that the timer should be stopped.

[0025] In one possible implementation, the method further includes: the parent node receiving second indication information from the access network device; and in response to the second indication information, the parent node sending first indication information to the child node.

[0026] Optionally, the second indication information includes the identifier of the child node.

[0027] In one possible implementation, the first indication information is a Media Access Control Element (MACCE) of the first type, or the first indication information is a MAC CE carrying a contention resolution identifier.

[0028] In one possible implementation, the cell radio network temporary identifier (C-RNTI) of the child node before receiving the first RRC reconfiguration message can be the same as the cell radio network temporary identifier (C-RNTI) after receiving the first RRC reconfiguration message.

[0029] Optionally, the first RRC reconfiguration message does not include the cell radio network temporary identifier of the child node.

[0030] Alternatively, the first RRC reconfiguration message may include a third indication message indicating that the temporary identifier of the cell radio network of the sub-node remains unchanged.

[0031] Alternatively, the first RRC reconfiguration message may include the child node's cell radio network temporary identifier before the parent node sends the first RRC reconfiguration message to the child node.

[0032] In one possible implementation, the access network device is the target access network device for the subnode during group handover.

[0033] In one possible implementation, the method further includes: after the parent node receives a first RRC reconfiguration message from the access network device or sends it to the child node, the parent node receives a second RRC reconfiguration message from the access network device, and the parent node starts a timer.

[0034] Optionally, the method further includes: after the parent node receives or sends a first RRC reconfiguration message from the access network device to the child node, the parent node sends a fourth indication message to the source access network device to trigger the source access network device to send a second RRC reconfiguration message to the parent node, wherein the source access network device is the source access network device of the child node and the parent node during the group handover process.

[0035] In one possible implementation, the child node is a terminal or an IAB node, and the parent node is an IAB node.

[0036] In one possible implementation, the access network device may include a CU; alternatively, the access network device may also include a DU.

[0037] A third aspect of this application provides a communication method applied in an integrated access and backhaul (IAB) system. This method can be executed by an access network device or by a chip within the access network device. The following description uses the example of execution by an access network device. The method includes: the access network device sending a first Radio Resource Control (RRC) reconfiguration message to a child node through a parent node to trigger the child node to start a timer; the first RRC reconfiguration message including an indication of random access exemption; the access network device receiving a first RRC reconfiguration completion message from the child node through the parent node; and the access network device sending second indication information to the parent node to trigger the parent node to send first indication information to the child node, the first indication information indicating that the timer should be stopped.

[0038] In one possible implementation, the second indication information includes the identifier of the child node.

[0039] In one possible implementation, the first indication information is a Media Access Control Element (MACCE) of the first type, or the first indication information is a MAC CE carrying a contention resolution identifier.

[0040] In one possible implementation, the cell radio network temporary identifier (C-RNTI) of the child node before receiving the first RRC reconfiguration message can be the same as the cell radio network temporary identifier (C-RNTI) after receiving the first RRC reconfiguration message.

[0041] Optionally, the first RRC reconfiguration message does not include the cell radio network temporary identifier of the child node.

[0042] Alternatively, the first RRC reconfiguration message may include a third indication message indicating that the temporary identifier of the cell radio network of the sub-node remains unchanged.

[0043] Alternatively, the first RRC reconfiguration message may include the temporary identifier of the child node's cell radio network before the access network device sends the first RRC reconfiguration completion message to the child node through the parent node.

[0044] In one possible implementation, the access network device is the target access network device for the subnode during group handover.

[0045] Optionally, the method further includes: the target access network device receiving a handover request message from the source access network device, the handover request message including one or more of the following: the temporary identifier of the cell radio network of the child node before the handover, the identifier of the cell accessed by the child node before the handover and the hierarchical information of the child node in the network topology, the source access network device being the source access network device of the child node and the parent node during the group handover process.

[0046] Optionally, the method further includes: the target access network device determining the duration of the timer based on the hierarchical information; wherein the first RRC reconfiguration message includes information about the duration of the timer.

[0047] The target access network device receives the hierarchical information of the sub-nodes in the network topology. Based on this hierarchical information, the target access network device can reasonably determine the timer duration. For example, nodes with a higher hop count on the wireless backhaul link with the migrating IAB node require a longer timer duration, while nodes with a lower hop count require a shorter timer duration. This avoids sub-node handover failures due to improper timer duration settings.

[0048] This application provides a communication method for use in an integrated access and backhaul (IAB) system, which can keep the C-RNTI unchanged before and after the child node switchover, reduce the process of configuring C-RNTI for the child node, reduce the power consumption of the child node, and save power.

[0049] The solutions provided by the embodiments of this application are described below in conjunction with the fourth and fifth aspects. It should be noted that the fourth to fifth aspects describe the solutions from the perspective of different network elements, and their contents can be referenced and cited from each other.

[0050] The fourth aspect of this application provides a communication method applied in an integrated access and backhaul (IAB) system. This method can be executed by a child node or by a chip within the child node. The following description uses child node execution as an example. The method includes: the child node receiving a first Radio Resource Control (RRC) reconfiguration message from the access network device through its parent node; the child node performing a handover based on the first RRC reconfiguration message; wherein the temporary radio network identifier of the cell before the handover is the same as the temporary radio network identifier of the cell after the handover.

[0051] By keeping the C-RNTI of the child node unchanged, the process of configuring the C-RNTI of the child node can be reduced, the power consumption of the child node can be reduced, and the power of the child node can be saved.

[0052] In one possible implementation, the cell radio network temporary identifier (C-RNTI) of the child node before receiving the first RRC reconfiguration message can be the same as the cell radio network temporary identifier (C-RNTI) after receiving the first RRC reconfiguration message.

[0053] Optionally, the first RRC reconfiguration message may not include the cell radio network temporary identifier of the child node, or the first RRC reconfiguration message may include first indication information indicating that the cell radio network temporary identifier of the child node remains unchanged, or the first RRC reconfiguration message may include the cell radio network temporary identifier used by the child node before receiving the first RRC reconfiguration message.

[0054] In one possible implementation, the first RRC reconfiguration message includes an indication of no random access.

[0055] In one possible implementation, the fourth aspect of the method may also include the first aspect of the method, as detailed in the first method. For example, the method may further include: the child node starting a timer; the child node sending a first RRC reconfiguration completion message to the access network device through the parent node; the child node receiving second indication information from the parent node, the second indication information indicating to stop the timer; and the child node stopping the timer.

[0056] In one possible implementation, the child node is a terminal or an IAB node, and the parent node is an IAB node.

[0057] In one possible implementation, the access network device may include a CU; alternatively, the access network device may also include a DU.

[0058] This application's fifth aspect provides a communication method applied in an integrated access and backhaul (IAB) system. This method can be executed by an access network device or by a chip within the access network device. The following description uses the example of execution by an access network device. The method includes: the access network device acquiring a first Radio Resource Control (RRC) reconfiguration message; the access network device sending the first RRC reconfiguration message to a child node through a parent node; wherein the first RRC reconfiguration message is used for handover of the child node, and the temporary radio network identifier of the cell before handover is the same as the temporary radio network identifier of the cell after handover.

[0059] In one possible implementation, the cell radio network temporary identifier (C-RNTI) of the child node before receiving the first RRC reconfiguration message can be the same as the cell radio network temporary identifier (C-RNTI) after receiving the first RRC reconfiguration message.

[0060] Optionally, the first RRC reconfiguration message may not include the cell radio network temporary identifier of the child node, or the first RRC reconfiguration message may include first indication information indicating that the cell radio network temporary identifier of the child node remains unchanged, or the first RRC reconfiguration message may include the cell radio network temporary identifier used by the child node before receiving the first RRC reconfiguration message.

[0061] In one possible implementation, the first RRC reconfiguration message includes an indication of no random access.

[0062] In one possible implementation, the fifth aspect of the method may also include the third aspect of the method, which can be referred to in detail. For example, the fifth aspect of the method may also include: the access network device receiving a first RRC reconfiguration completion message from the child node through the parent node; the access network device sending a second indication message to the parent node to trigger the parent node to send a third indication message to the child node, the third indication message indicating to stop the timer.

[0063] This application provides a solution that ensures, during group handover, that the parent node receives the RRC reconfiguration message from the child node first, and then receives the RRC reconfiguration message from the parent node. This avoids the situation where the parent node stops transmission with the source access network device after receiving its own RRC reconfiguration message, thus preventing it from receiving the RRC reconfiguration message from the child node, thereby ensuring the handover function of the child node.

[0064] The solutions provided by the embodiments of this application are described below in conjunction with the sixth and seventh aspects. It should be noted that the fourth to fifth aspects describe the solutions from the perspective of different network elements, and their contents can be referenced and cited from each other.

[0065] The sixth aspect of this application provides a communication method applied in an integrated access backhaul (IAB) system. This method can be executed by a parent node or by a chip within the parent node. The following description uses parent node execution as an example. The method includes: after the parent node receives a first RRC reconfiguration message from the source access network device or sends it to the child node, the parent node receives a second RRC reconfiguration message from the source access network device.

[0066] In one possible implementation, the first RRC reconfiguration message is used to trigger the child node to start a timer, and the second RRC reconfiguration message is used to trigger the parent node to start a timer.

[0067] In one possible implementation, the source access network device can be the source access network device for both the child node and the parent node during group handover.

[0068] Optionally, the group to which the group is switched may include one or more other nodes.

[0069] In one possible implementation, the method further includes: after the parent node receives or sends a first RRC reconfiguration message from the source access network device to the child node, the parent node sends a first indication information to the source access network device, and in response to the first indication information, the source access network device sends a first RRC reconfiguration message to the parent node.

[0070] In one possible implementation, the sixth aspect may include the content of the second aspect. For details, please refer to the content of the second aspect.

[0071] The seventh aspect of this application provides a communication method applied in an integrated access backhaul (IAB) system. This method can be executed by a source access network device or by a chip within the source access network device. The following description uses the source access network device as an example. The method includes: after the source access network device sends a first RRC reconfiguration message to the parent node, the source access network device sends a second RRC reconfiguration message to the parent node.

[0072] In one possible implementation, the first RRC reconfiguration message is used for switching or reconfiguring the parent node and can be referred to as the parent node's RRC reconfiguration message, and the second RRC reconfiguration message is used for switching or reconfiguring the child node and can be referred to as the child node's RRC reconfiguration message.

[0073] In one possible implementation, the first RRC reconfiguration message is used to trigger the child node to start a timer, and the second RRC reconfiguration message is used to trigger the parent node to start a timer.

[0074] In one possible implementation, the source access network device can be the source access network device for both the child node and the parent node during group handover.

[0075] Optionally, the group to which the group is switched may include one or more other nodes.

[0076] In one possible implementation, the method further includes: after the source access network device sends a first RRC reconfiguration message to the parent node, the source access network device receives a first indication information from the parent node, and in response to the first indication information, the source access network device sends a second RRC reconfiguration message to the parent node.

[0077] The contents of the first and second RRC reconfiguration messages in the methods of the sixth and seventh aspects can refer to the contents of the first to fifth aspects above.

[0078] This application provides a scheme in which, during group handover, the source access network device sends the C-RNTI of one or more nodes in the group undergoing group handover, the cell identifier of the accessed cell, and / or hierarchical information in the network topology to the target access network device.

[0079] The solutions provided by the embodiments of this application are described below in conjunction with aspects eight and nine. It should be noted that aspects eight to nine describe the solutions from the perspective of different network elements, and their contents can be referenced and cited from each other.

[0080] This application's eighth aspect provides a communication method applied in an integrated access backhaul (IAB) system. This method can be executed by a source access network device or by a chip within the source access network device. The following description uses the source access network device as an example. The method includes: the source access network device acquiring a handover request message; the source access network device sending a handover request message to a target access network device, including the C-RNTI of one or more nodes, the cell identifier of the accessed cell, and / or hierarchical information in the network topology.

[0081] By sending one or more nodes' C-RNTIs to the target access network device through the source access network device, the target access network device can send the C-RNTI of each node in the RRC reconfiguration message to that node. As a result, the C-RNTI of that node can remain unchanged before and after the handover, reducing the process of configuring C-RNTI and reducing the power consumption of the node.

[0082] By sending the identifiers and C-RNTs of one or more nodes accessing the cell to the target access network device from the source access network device, the target access network device can uniquely identify the one or more nodes.

[0083] Optionally, the cell identifier of the accessed cell may include one or more of the following: physical cell identifier (PCI), NR cell identity (NCI), NR cell global identifier (NCGI), and E-UTRAN cell global identifier (ECGI).

[0084] Optionally, the PCI of the cell can remain unchanged before and after the handover, while the NCGI and ECGI can be changed.

[0085] By sending the hierarchical information of one or more nodes in the network topology to the target access network device, the target access network device can reasonably determine the timer duration based on this hierarchical information. For example, nodes with a higher hop count on the wireless backhaul link with the migrating IAB node should have a longer timer duration, while nodes with a lower hop count should have a shorter timer duration. This avoids sub-node handover failures due to improperly set timer durations.

[0086] In one possible implementation, the source access network device is the source access network device of the one or more nodes during the group handover process, and the target access network device is the target access network device of the one or more nodes during the group handover process.

[0087] In one possible implementation, the hierarchical information of the one or more nodes in the network topology is used to determine the duration of the timer for the one or more nodes.

[0088] In one possible implementation, the method further includes: the source access network device receiving RRC reconfiguration messages from the target access network device for each of the one or more nodes; the source access network device sending the RRC reconfiguration message for that node to each of the one or more nodes; and each node's RRC reconfiguration message including information about the duration of its timer. It can be understood that the source access network device sending the RRC reconfiguration message to each node may specifically include the source access network device first sending the node's RRC reconfiguration message to the node's parent node, and then the parent node sending the RRC reconfiguration message to the node.

[0089] In one possible implementation, the method of the eighth aspect may also include the method of the seventh aspect. It can be understood that the child nodes and parent nodes of the seventh aspect can be one or more nodes of the method of the eighth aspect.

[0090] The ninth aspect of this application provides a communication method applied in an integrated access backhaul (IAB) system. This method can be executed by a target access network device or by a chip within the target access network device. The following description uses execution by the target access network device as an example. The method includes: the target access network device receiving a handover request message from a source access network device, including the C-RNTI of one or more nodes, the cell identifier of the accessed cell, and / or hierarchical information in the network topology.

[0091] In one possible implementation, the source access network device is the source access network device of the one or more nodes during the group handover process, and the target access network device is the target access network device of the one or more nodes during the group handover process.

[0092] In one possible implementation, the target access network device determines the duration information of the timers for one or more nodes based on the hierarchical information.

[0093] In one possible implementation, the method further includes: the target access network device acquiring RRC reconfiguration messages of one or more nodes respectively; the target access network device sending the RRC reconfiguration messages of the one or more nodes respectively to the source access network device; and the source access network device sending the RRC reconfiguration message of the node to each of the one or more nodes, wherein the RRC reconfiguration message of each node includes information about the duration of the node's timer.

[0094] In one possible implementation, the method of the ninth aspect may also include the method of the third aspect, which will not be described here. For example, the method further includes: the target access network device receiving the RRC reconfiguration message of each node, and after receiving the RRC reconfiguration message of each node, the target access network device sending indication information to the parent node of that node to trigger the parent node to instruct the node to stop the timer.

[0095] In one possible implementation, the method of the ninth aspect may also include the method of the fifth aspect, which will not be described here. For example, the temporary identifier of the cell radio network for each node remains unchanged before and after the handover.

[0096] This application's tenth aspect provides a communication method applied in an integrated access and backhaul (IAB) system. This method can be executed by a target access network device or by a chip within the target access network device. The following description uses execution by the target access network device as an example. The method includes: the target access network device acquiring a group handover command, the group handover command including one or more of the following: indication information for non-random access, the duration of a handover timer, and common configuration information of the serving cell; the target access network device broadcasting the group handover command.

[0097] In one possible implementation, the target access network device is the target access network device during group handover. The group undergoing group handover may include one or more nodes, and correspondingly, these one or more nodes may obtain the group handover command.

[0098] By broadcasting the same information to each node, air interface signaling overhead can be saved. Especially in IAB systems, this broadcasting method avoids the signaling overhead of sending signaling to multiple nodes in the group individually.

[0099] In one possible implementation, the method of the tenth aspect may also include the methods of the third aspect, the fifth aspect, and / or the ninth aspect, which will not be described here.

[0100] The eleventh aspect of this application provides a communication method applicable to single-air interface scenarios. A terminal switches from a source access network device to a target access network device, which includes a CU and a DU. The method may include: the CU sending a first indication message to the DU to trigger the DU to send a second indication message to the terminal; and the terminal stopping a timer based on the second indication message.

[0101] In one possible implementation, before the CU sends the first indication information to the DU, the method may further include: the target CU sending a first RRC reconfiguration message to the terminal through the source access network device; the terminal receiving the first RRC reconfiguration message starting a timer; the terminal sending a first RRC reconfiguration completion message to the DU; and the DU sending a first RRC reconfiguration completion message to the CU.

[0102] Optionally, the first instruction information in the eleventh aspect may refer to the content of the second instruction information in the first aspect, and the second instruction information in the eleventh aspect may refer to the content of the first instruction information in the first aspect, which will not be described here.

[0103] One or more of the methods in the first to eleventh aspects mentioned above can be combined with each other, and in the methods of each aspect, one or more of the multiple possible implementations can be combined with each other.

[0104] The twelfth aspect of this application provides a communication device, which may be a child node or a chip within a child node, or a parent node or a chip within a parent node, or a source access network device or a chip within a source access network device, or a target access network device or a chip within a target access network device, or a CU or a chip within a CU, or a DU or a chip within a DU. The communication device includes a processor for executing computer programs or instructions to cause the communication device to perform the methods of the first to eleventh aspects.

[0105] Optionally, the communication device further includes the memory. The processor is coupled to the memory, which stores computer programs or instructions, and the processor executes the computer programs or instructions stored in the memory.

[0106] Optionally, the communication device may further include a communication unit for communicating with other devices or other components within the communication device. For example, the communication device may be a child node or a parent node, and the communication unit may be a transceiver. For example, if the communication device is an access network device, the communication unit may include an interface between the transceiver and the access network device. The transceiver is used for communication between the access network device and its child nodes, and the interface is used for communication between the access network device and other access network devices. For example, if the communication device is a CU, the communication unit may be an interface between the CU and DU, and an interface between the CU and other access network devices. For example, if the communication device is a DU, the communication unit may be an interface between the CU and DU, and a transceiver for the DU.

[0107] For example, the communication device chip, the communication unit is the chip's input / output circuit or interface.

[0108] A ninth aspect of this application provides a communication device that has the function of implementing the behaviors of a child node, a parent node, a source access network device, a target access network device, a CU of the source access network device or a DU of the target access network device, as described in the above-described method aspects. The device includes means for performing steps or functions corresponding to those described in the first to eleventh aspects of the method. These steps or functions can be implemented in software, hardware, or a combination of both.

[0109] The thirteenth aspect of this application provides a chip including a processor and an interface circuit coupled to the processor. The processor is used to run computer programs or instructions to implement the methods of any one of the first to eleventh aspects. The interface circuit is used to communicate with other modules outside the chip.

[0110] A fourteenth aspect of this application provides a computer storage medium storing a program for implementing the methods of any one of the first to eleventh aspects described above. When the program is run in a wireless communication device, it causes the wireless communication device to execute the methods of any one of the first to eleventh aspects.

[0111] The fifteenth aspect of this application provides a computer program product including a program that, when run, causes the methods of any one of the first to seventh aspects described above to be executed.

[0112] The sixteenth aspect of this application provides a communication system including one or more of the child node, parent node, source access network device, and target access network device involved in the methods of the first to eleventh aspects described above. Attached Figure Description

[0113] To more clearly illustrate the technical solutions in the embodiments of this application or the background art, the accompanying drawings used in the embodiments of this application or the background art will be described below.

[0114] Figure 1 This is a schematic diagram of a mobile communication system 100 provided in an embodiment of this application;

[0115] Figure 2 This is a schematic diagram of the CU-DU split architecture provided in the embodiments of this application;

[0116] Figure 3 This is a schematic diagram of the integrated access and backhaul node (IAB) network provided in the embodiments of this application;

[0117] Figure 4A This is a schematic diagram of the control plane protocol stack for a single air interface provided in an embodiment of this application;

[0118] Figure 4B This is a schematic diagram of the user plane protocol stack for a single air interface provided in an embodiment of this application;

[0119] Figure 5A This is a schematic diagram of the control plane protocol stack in the IAB network provided in the embodiments of this application;

[0120] Figure 5B This is a schematic diagram of the user plane protocol stack in the IAB network provided in the embodiments of this application;

[0121] Figure 6 This is a schematic diagram of group switching provided in an embodiment of this application;

[0122] Figure 7 This application provides a communication method;

[0123] Figure 8 This application provides a method for group switching.

[0124] Figure 9 This is another communication method provided in the embodiments of this application;

[0125] Figure 10 This is a schematic diagram of the structure of a terminal provided in an embodiment of this application;

[0126] Figure 11 This is a schematic diagram of the structure of an access network device provided in an embodiment of this application;

[0127] Figure 12 This is a schematic diagram of the structure of a communication device provided in an embodiment of this application;

[0128] Figure 13 This is a schematic diagram of the structure of a communication device provided in an embodiment of this application. Detailed Implementation

[0129] The embodiments of this application will now be described with reference to the accompanying drawings.

[0130] Figure 1 This is a schematic diagram of the architecture of a communication system 100 provided in an embodiment of this application. The communication system 100 includes at least one terminal (e.g., terminal 110, terminal 120 and terminal 130), at least one relay node 140 (RN), at least one access network device 150 and at least one core network device 160.

[0131] The terminal can be connected to at least one access network device, or the terminal can be connected to at least one access network device through at least one relay node, and the at least one access network device is connected to at least one core network device. For example... Figure 1 As shown, terminals 110 and 120 are both connected to relay node 140, which is connected to access network device 150. Terminal 130 is also connected to access network device 150. Access network device 150 is connected to core network device 160. The connection method between terminals 110, 120, 130, relay node 140, access network device 150, and core network device 160 can be wireless or wired, and is not limited in this application.

[0132] The communication system provided in this application may be, for example, a long term evolution (LTE) system supporting 4G access technology, a new radio (NR) system supporting 5G access technology, any cellular system related to the 3rd generation partnership project (3GPP), a wireless-fidelity (WiFi) system, a worldwide interoperability for microwave access (WiMAX) system, a radio access technology (RAT) system, or other future-oriented communication technologies. The terminal in this application is a device with wireless transceiver capabilities, which can be deployed on land, including indoors or outdoors, handheld, wearable, or vehicle-mounted; it can also be deployed on water (such as on ships); and it can also be deployed in the air (e.g., on drones, airplanes, balloons, and satellites). The terminal can be a mobile phone, tablet computer, computer with wireless transceiver capabilities, virtual reality (VR) terminal device, augmented reality (AR) terminal device, wireless terminal in industrial control, wireless terminal in self-driving, wireless terminal in remote medical care, wireless terminal in smart grid, wireless terminal in transportation safety, wireless terminal in smart city, wireless terminal in smart home, etc. The embodiments of this application do not limit the application scenario. The terminal may also be referred to as terminal equipment, user equipment (UE), access terminal equipment, station, UE unit, UE station, mobile station, mobile station, remote station, remote terminal equipment, mobile device, UE terminal equipment, terminal equipment, wireless communication equipment, UE agent or UE device, or some other suitable term. The terminal can also be fixed or mobile.

[0133] Access network equipment can be devices on the access network side used to support terminal access to the communication system. Access network equipment can be called a base station (BS), such as an evolved NodeB (eNB) in a 4G access technology communication system, a next-generation NodeB (gNB) in a 5G access technology communication system, a transmission reception point (TRP), a relay node, an access point (AP), an access node in a WiFi system, a wireless backhaul node, etc. Alternatively, access network equipment can be called a host node, IAB donor, host IAB, host or host gNB (DgNB, donor gNB), etc. Base stations can be macro base stations, micro base stations, pico base stations, small cells, relay stations, etc. Multiple base stations can support networks using the same technology mentioned above, or they can support networks using different technologies mentioned above. A base station can contain one or more co-located or non-co-located transmission receiving points (TRPs). Access network equipment can also be radio controllers, central units (CUs), and / or distributed units (DUs) in a cloud radio access network (CRAN) scenario. Access network equipment can also be servers, wearable devices, or vehicle-mounted devices, etc. The following explanation uses a base station as an example. Multiple access network devices in a communication system can be base stations of the same type or different types. Base stations can communicate with terminals directly or via relay stations. Terminals can communicate with multiple base stations using different technologies; for example, a terminal can communicate with a base station supporting LTE networks, or with a base station supporting 5G networks, and can also support dual connectivity with both LTE and 5G base stations.

[0134] Core network equipment can connect to one or more access network devices and provide terminals in the system with one or more functions, including session management, access authentication, Internet Protocol (IP) address allocation, and data transmission. For example, core network equipment can be a Mobile Management Entity (MME) or Serving Gateway (SGW) in a 4G access technology communication system, or an Access and Mobility Management Function (AMF) or User Plane Function (UPF) network element in a 5G access technology communication system, etc. Core network equipment can also be referred to as a core network element.

[0135] A relay node can be a node that provides radio access services and / or backhaul services. Radio access services refer to the provision of data and / or signaling through a radio access link, while radio backhaul services refer to the data and / or signaling backhaul services provided through a radio backhaul link. Relay nodes are used to forward data and / or signaling between terminals and access network equipment. On the one hand, relay nodes provide radio access services to terminals through access links (ALs), and on the other hand, they connect to access network equipment through one-hop or multi-hop backhaul links (BLs).

[0136] Relay nodes can have different names in different communication systems. For example, a relay node can be called a wireless backhaul node or a wireless backhaul device. In 5G systems, for instance, a relay node can be called an integrated access and backhaul node (IAB node). Of course, relay nodes may have different names in future communication systems, and this is not a limitation here.

[0137] Optionally, the relay node can also be a terminal device. Alternatively, the relay node can also be a CPE in a home access scenario. For example, the IAB node can be a customer premises equipment (CPE) or a residential gateway (RG). In this case, the method provided in this application embodiment can also be applied to home access scenarios.

[0138] Figure 2 This is a schematic diagram of the CU-DU split architecture provided in the embodiments of this application. Figure 1The access network device 150 can adopt a CU-DU split architecture. Figure 2 The following explanation uses gNB (new radio node B, gNB) as an example of an access network device.

[0139] gNB can be implemented using a cloud radio access network (C-RAN) architecture. Some of the gNB's functions are implemented by the central unit (CU), while others are implemented by the distributed unit (DU). The separation of CU and DU can be based on the protocol stack. One possible approach is to deploy the radio resource control (RRC) layer, the service data adaptation protocol (SDAP) layer, and the packet data convergence protocol (PDCP) layer in the CU, while the remaining layers—radio link control (RLC), media access control (MAC), and physical (PHY) layers—are deployed in the DU.

[0140] A CU can connect to one or more DUs, facilitating network expansion. CUs and DUs are connected via interfaces (e.g., F1 interfaces), and CUs are connected to the core network (e.g., 5G core network, 5GC) via interfaces (e.g., NG interfaces).

[0141] In one implementation, the CU includes a user plane (UP) (hereinafter referred to as CU-UP) and a control plane (CP) (hereinafter referred to as CU-CP).

[0142] Figure 3 This is a schematic diagram of the integrated access and backhaul node (IAB) network provided in the embodiments of this application. Figure 3 for Figure 1 One application scenario of the communication system 100 shown below, combined with... Figure 3 ,right Figure 1 Further explanation will be provided regarding the terminals, relay nodes, and access network equipment.

[0143] An IAB network includes one or more terminals (for clarity, ...). Figure 3Only terminal 1 is shown in the image, one or more IAB nodes (for clarity, only terminal 1 is shown). Figure 2 The diagram shows two IAB nodes (IAB node 1 and IAB node 2) and one or more host nodes (for clarity, ...). Figure 2 Only IAB donor 1 is shown in the image.

[0144] Terminal 1 can be connected to one or more IAB nodes, each IAB node can be connected to one or more other IAB nodes, and one or more IAB nodes can be connected to one or more host nodes. Optionally, one or more IAB nodes can also be connected to each other, which is not limited in this application.

[0145] The IAB donor may be referred to as the host node, DgNB (i.e., donor gNodeB) or other suitable names, and this application does not limit this.

[0146] exist Figure 3 In the middle, terminal 1 can be Figure 1 Terminal 110 in the middle. IAB node 1 and IAB node 2 can be Figure 1 Relay node 140 in the IAB. IAB donor 1 can be Figure 1 The access network equipment 150 in the middle. The 5G core network (5G Core Network, 5GC) and the evolved packet core (EPC) can provide Figure 1 The core network consists of at least one core network device.

[0147] Figure 3 In the IAB donor 1, it can be Figure 2 In the gNB, IAB donor 1 can be used Figure 2 The CU-DU separation architecture in this context means that IAB donor 1 can consist of a centralized unit (which can be called IAB donor CU 1) and a distributed unit (which can be called IAB donor DU 1). IAB donor CU 1 can be composed of a CP (which can be called IAB donor CU 1-CP) and an UP (which can be called IAB donor CU 1-UP). For details, please refer to [reference needed]. Figure 2 The content in [the document / article].

[0148] IAB networks support standalone (SA) or non-standalone (NSA) networking modes.

[0149] For example,Figure 3 In the SA networking mode, IAB donor 1 can be connected to 5GC. Specifically, IAB donor CU1-CP can be connected to control plane network elements in 5GC, such as access and mobility management function (AMF), and IAB donor CU1-UP can be connected to user plane network elements in 5GC, such as user plane function (UPF).

[0150] For example, Figure 3 In the NSA networking configuration, IAB donor 1 acts as a secondary gNB (SgNB) and establishes a dual connection with the master eNB (MeNB). Specifically, IAB node 1 and IAB node 2 are both connected to the MeNB, IAB donor CU 1-CP is connected to the MeNB, the MeNB is connected to the EPC, and IAB donor CU 1-UP is connected to network elements in the EPC, such as the service gateway (SGW).

[0151] It is understandable that in an IAB network, a transmission path between a terminal and the host node can contain one or more IAB nodes. If an IAB node is the node through which a terminal accesses, the link between that IAB node and its child nodes (i.e., the terminal) can be called an access link. If an IAB node is the node that provides backhaul services to terminals under other IAB nodes, the link between that IAB node and its child nodes (i.e., other IAB nodes) can be called a backhaul link. For example, as... Figure 3 In this configuration, terminal 1 is connected to IAB node 1 via a wireless access link, IAB node 1 is connected to IAB node 2 via a wireless backhaul link, and IAB node 2 is connected to IAB donor 1 via a wireless backhaul link.

[0152] To ensure the reliability of service transmission, the IAB network optionally supports multi-hop IAB nodes and multi-connection IAB node networking. Multiple transmission paths may exist between the terminal and the IAB host. On a single path, there is a defined hierarchical relationship between IAB nodes, and between IAB nodes and the host nodes serving those IAB nodes. Each IAB node or terminal considers the node providing access services to it as its parent node. Correspondingly, each IAB node or terminal can be considered a child node of its parent node.

[0153] Furthermore, in this embodiment, the parent node of the parent node of the IAB node is referred to as the grandparent node of the IAB node, and the child node of the child node of the IAB node is regarded as the grandchild node of the IAB node.

[0154] It's understandable that parent and child nodes are relative concepts; a node can be a child node relative to one node, and a parent node relative to another. For example, Figure 3 In this context, IAB node 1 is the parent node of terminal 1, and terminal 1 is the child node of IAB node 1; IAB node 2 is the parent node of IAB node 1, and IAB node 1 is the child node of IAB node 2; IAB donor 1 (which can specifically be IAB donor DU) is the parent node of IAB node 2, and IAB node 2 is the child node of IAB donor 1 (which can specifically be IAB donor DU).

[0155] Uplink data packets from the terminal can be transmitted to the host node via one or more IAB nodes, and then sent by the host node to core network equipment, such as mobile gateway equipment (e.g., user plane function (UPF) network elements in 5G networks). Downlink data packets from the terminal will be received by the host node from the core network equipment (mobile gateway equipment), and then sent to the terminal via one or more IAB nodes.

[0156] For example, Figure 3 In the above, the transmission path of uplink data packets between terminal 1 and IAB donor 1 is: terminal 1 → IAB node 1 → IAB node 2 → IAB donor 1, and the transmission path of downlink data packets between terminal 1 and IAB donor 1 is: IAB donor 1 → IAB node 2 → IAB node 1 → terminal 1.

[0157] In an IAB network, along a transmission path, the IAB node to which a terminal connects is called the access IAB node, and the other IAB nodes along that path are called intermediate IAB nodes. Intermediate IAB nodes can provide backhaul services to the terminal. An IAB node can act as both an access IAB node for a specific terminal and an intermediate IAB node for other terminals.

[0158] For example, Figure 3 In the path "Terminal 1 → IAB node 1 → IAB node 2 → IAB donor 1", IAB node 1 is the access IAB node, and IAB node 2 is the intermediate IAB node. If terminal 2 ( Figure 2(Not shown in the image) Access IAB node3 ( Figure 3 (Not shown in the image), IAB node 3 is connected to IAB node 1. Therefore, for terminal 2, IAB node 3 is the connected IAB node, and IAB node 1 is the intermediate IAB node.

[0159] In an IAB network, one or more IAB nodes and one or more terminals served by an IAB node can be referred to as descendant nodes of that IAB node. It can be understood that descendant nodes can include the IAB nodes served by the IAB node, or it can be understood that descendant nodes include subordinate IAB nodes connected to the IAB node through at least one hop link, such as child nodes and grandchild nodes, etc., as well as terminals accessing these IAB nodes, such as terminals accessing child nodes and grandchild nodes.

[0160] For example, Figure 3 In this context, the descendant nodes of IAB node 2 include terminal 1 and IAB node 1.

[0161] The above-described IAB network is merely an example. In IAB networks that combine multi-hop and multi-connection, there are many other possibilities, such as a host node and an IAB node under another host node forming a dual connection to provide terminal services, etc., which will not be listed here.

[0162] In an IAB network, when an IAB node acts as a parent node, it can function similarly to an access network device, providing access services to its child nodes. For example, it can allocate uplink resources for transmitting uplink data to its child nodes through scheduling. When an IAB node acts as a child node, it can act as a terminal device to the parent node providing services to that IAB node. For example, it can establish a connection with the parent node through operations such as cell selection and random access, and obtain the uplink resources scheduled by the parent node for transmitting uplink data.

[0163] By way of example and not limitation, in this application, the functional unit in the IAB node that supports the IAB node in fulfilling the role of a terminal device is referred to as the mobile terminal (MT) functional unit of the IAB node, or simply IAB-MT or IAB-UE. The functional unit in the IAB node that supports the IAB node in fulfilling the role of an access network device is referred to as the DU functional unit of the IAB node, or simply IAB-DU. IAB-MT and IAB-DU can be a logical functional unit, both of which are implemented by the IAB node; or IAB-MT and IAB-DU can be a physical division, where IAB-MT and IAB-DU can be different physical devices within the IAB node.

[0164] For example, Figure 3 In this context, IAB node 1 includes MT functional units and DU functional units, and IAB node 2 includes MT functional units and DU functional units.

[0165] Figure 4A and Figure 4B These are schematic diagrams of the control plane protocol stack and the user plane protocol stack of the single air interface provided in the embodiments of this application.

[0166] A single air interface can be understood as the terminal connecting directly to the access network device without needing to connect through a relay node. Figure 4A and Figure 4B The UE in the middle can be Figure 1 Terminal 130 in the middle, Figure 4A and Figure 4B gNB in ​​the middle can be Figure 1 The access network device 150 in the middle can adopt Figure 2 The CU-DU split architecture is shown.

[0167] In a single air interface scenario, the UE can access the CU through the DU. The DU implements the functions of the RLC, MAC, and PHY layers that are equivalent to the UE, while the CU implements the functions of the RRC, SDAP, and PDCP layers that are corresponding to the UE.

[0168] For control surfaces, such as Figure 4A As shown, the UE and CU have peer-to-peer RRC and PDCP layers. The UE and DU are connected via an interface (e.g., Uu interface), and peer-to-peer RLC, MAC, and PHY layers are established between the UE and DU. The DU and CU are connected via a control plane interface (e.g., F1-control plane, F1-C interface), and peer-to-peer F1 application protocol (F1AP) layer, stream control transmission protocol (SCTP) layer, Internet Protocol (IP) layer, layer (L)2, and layer (L)1 are established between the DU and CU.

[0169] From the user's perspective, such as Figure 4BAs shown, the UE and CU have established peer-to-peer SDAP and PDCP layers. The UE and DU are connected via the Uu interface, and peer-to-peer RLC, MAC, and PHY layers are established between them. The DU and CU are connected via the F1 user plane (F1-U) interface, and peer-to-peer General Packet Radio Service (GPRS) Tunneling Protocol-User Plane (GTP-U), User Datagram Protocol (UDP), IP, L2, and L1 layers are established between them.

[0170] Figure 5A and Figure 5B These are schematic diagrams of the control plane protocol stack and the user plane protocol stack in the IAB network provided in this application embodiment. Figure 5A and Figure 5B by Figure 3 Let's take a scenario as an example to illustrate.

[0171] In an IAB network, the PHY, MAC, and RLC layers, which are equivalent to the terminal, are located on the access IAB node, while the PDCP, SDAP, and RRC layers, which are equivalent to the UE, are located on the IAB donor CU. If the IAB donor-CU consists of a CP and an UP, then the RRC layer, which is equivalent to the UE, is located on the CP of the IAB donor CU (i.e., donor-CU-CP), and the PDCP and SDAP layers, which are equivalent to the UE, are located on the UP of the IAB donor CU (i.e., donor-CU-UP).

[0172] For control surfaces, such as Figure 5AAs shown, a Uu interface is established between terminal 1 and the DU of IAB node 1, with peer protocol layers including RLC, MAC, and PHY layers. An F1-C interface is established between the DU of IAB node 1 and IAB donor CU1, with peer protocol layers including F1AP, SCTP, and IP layers. An F1 interface within the IAB host is established between IAB donor DU 1 and IAB donor CU 1, with peer protocol layers including IP, L2, and L1 layers. A BL is established between IAB node 1 and IAB node 2, and between IAB node 2 and IAB donor DU 1, with peer protocol layers including Bakhaul Adaptation Protocol (BAP), RLC, MAC, and PHY layers. Additionally, peer RRC and PDCP layers are established between terminal 1 and IAB donor CU 1, and a peer IP layer is established between the DU of IAB node 1 and IAB donor DU 1.

[0173] In this embodiment, the BAP layer includes one or more of the following capabilities: adding routing information recognizable by the IAB node to data packets; performing routing selection based on the routing information recognizable by the IAB node; adding identification information related to quality of service (QoS) requirements recognizable by the IAB node to data packets; performing QoS mapping on multiple links containing the IAB node for data packets; adding data packet type indication information to data packets; and sending flow control feedback information to nodes with flow control capabilities. It should be noted that the name of the protocol layer possessing these capabilities is not necessarily BAP layer; it can also be other names. Those skilled in the art will understand that any protocol layer possessing these capabilities can be understood as the BAP layer in this embodiment.

[0174] It can be seen that, compared with the control plane protocol stack of a single air interface, the DU accessing the IAB network implements the functions of the DU of a single air interface gNB, namely, establishing peer-to-peer RLC, MAC, and PHY layers with the terminal, and establishing peer-to-peer F1AP, SCTP, and IP layers with the CU. The IAB donor CU implements the functions of the CU of a single air interface gNB.

[0175] From the user's perspective, such as Figure 5BAs shown, a Uu interface is established between terminal 1 and the DU of IAB node 1, with corresponding protocol layers including RLC, MAC, and PHY. An F1-U interface is established between the DU of IAB node 1 and IAB donor CU1, with corresponding protocol layers including GTP-U, UDP, and IP. An F1 interface within the IAB host is established between IAB donor DU 1 and IAB donor CU 1, with corresponding protocol layers including IP, L2, and L1. A BL is established between IAB node 1 and IAB node 2, and between IAB node 2 and IAB donor DU 1, with corresponding protocol layers including BAP, RLC, MAC, and PHY. Additionally, corresponding SDAP and PDCP layers are established between terminal 1 and IAB donor CU 1, and a corresponding IP layer is established between the DU of IAB node 1 and IAB donor DU 1.

[0176] It can be seen that, compared with the user plane protocol stack of a single air interface, the user plane protocol stack of the IAB access node implements some of the functions of the DU of the single air interface gNB, namely, the functions of establishing peer-to-peer RLC, MAC, and PHY layers with the terminal, and the functions of establishing peer-to-peer GTP-U, UDP, and IP layers with the IAB donor CU 1. The IAB donor CU implements the functions of the CU of the single air interface gNB.

[0177] Figure 5A and Figure 5B Only with Figure 3 The protocol stack in the illustrated IAB scenario is described using an example. It should be noted that an IAB node may have one or more roles, and the IAB node can possess the protocol stack for that role; alternatively, an IAB node can have a single protocol stack that can use the corresponding protocol layer for different roles within the IAB node. The following explanation uses an example of an IAB node possessing a protocol stack for one or more roles:

[0178] (1) Terminal protocol stack

[0179] When an IAB node first connects to an IAB network, or after connecting, it can act as a terminal. The MT (Mediator) of this IAB node has the protocol stack of a terminal, for example... Figure 5A and Figure 5B The protocol stack of terminal 1 in the IAB. This IAB node can transmit its own uplink and / or downlink data packets (such as OAM packets) to the IABdonor, perform measurements through the RRC layer, and so on.

[0180] (2) Protocol stack for accessing the IAB node

[0181] After connecting to the IAB network, an IAB node can provide access services to terminals, thus acting as an access IAB node. In this case, the IAB node possesses the protocol stack for accessing the IAB network, for example... Figure 5A and Figure 5B The protocol stack of IABnode 1 in the middle.

[0182] (3) Protocol stack of intermediate IAB nodes

[0183] After connecting to the IAB network, an IAB node can act as an intermediate IAB node. In this case, the IAB node possesses the protocol stack of an intermediate IAB node, for example... Figure 5A and Figure 5B The protocol stack of IAB node 2 in the system.

[0184] An IAB node can have a protocol stack that includes one or more of the roles of terminal, access IAB node, and intermediate IAB node mentioned above.

[0185] Figure 6 This is a schematic diagram of group switching provided in an embodiment of this application. The following is in conjunction with... Figure 6 Please provide an explanation.

[0186] Figure 6 In this context, IAB node 1 can provide access and / or backhaul services for one or more terminals and / or other IAB nodes. For ease of description, this one or more terminals and / or other IAB nodes can be referred to as descendant nodes or subordinate nodes. For clarity, Figure 6 The diagram illustrates that IAB node 1 is connected to terminal 1 and IAB node 4, and IAB node 3 is connected to terminal 2. IAB node 1 provides access services to terminal 1 and IAB node 4, IAB node 4 provides access services to terminal 2, and IAB node 1 provides backhaul services to terminal 2. It should be noted that in actual network deployment scenarios, IAB node 1 may also have one or more grandchild nodes, and IAB node 4 may provide access and / or backhaul services to more terminals or IAB nodes. This embodiment does not impose such limitations.

[0187] Due to factors such as link quality or load changes, IAB node 1 may switch over. IAB node 1 switches from IAB node 2 to IAB node 3 (or IAB node 1 switches from the cell served by IAB node 2 to the cell served by IAB node 3). IAB node 2 is connected to IAB donor 1, and IAB node 3 is connected to IAB donor 2.

[0188] Since the IAB donor connected to IAB node 1 changed before and after the switch, the switch of IAB node 1 can be referred to as a cross-host node switch.

[0189] First, IAB node 1 can switch from IAB node 2 to IAB node 3 as an endpoint. Additionally, since IAB node 1 also serves descendant nodes, these descendant nodes can change their connection from IAB node 2 to IAB node 3 along with IAB node 1. Because the host node of the descendant nodes also changes, it can be considered that the descendant nodes have also switched. IAB node 1 and its descendant nodes can be referred to as a group, and the switching between IAB node 1 and its descendant nodes is called a group switch.

[0190] The group undergoing group switching can include one or more IAB nodes. For ease of explanation, in this embodiment, the node whose parent node changes during group switching is referred to as a migrating IAB node or a migrating node. The parent node of the migrating IAB node before the group switching is the source parent node, and the parent node of the migrating IAB node after the group switching is the target parent node. For example... Figure 6 In this context, IAB node 1 can be called the migrating IAB node, IAB node 2 can be called the source parent node of IAB node 1, and IAB node 3 can be called the target parent node of IAB node 1.

[0191] IAB donor 1 can be referred to as the source IAB donor for group switching, or the source IAB donor for one or more nodes in the group, or the source IAB donor for one or more nodes in the group during the group switching process. Similarly, IAB donor 2 can be referred to as the target IAB donor for group switching, or the target IAB donor for one or more nodes in the group, or the target IAB donor for one or more nodes in the group during the group switching process.

[0192] The group handover process can be understood as a group handover process, which may include the handover decision from the source IAB donor to the handover process performed by one or more nodes in the group. One or more nodes in the group may handover successfully or fail to handover, and this application embodiment does not limit this.

[0193] In this application, the source IAB donor may be referred to as the source host node or the source access network device, and the target IAB donor may be referred to as the target host node or the target access network device. This application does not limit this.

[0194] During group handover, because the access network equipment connected to each node changes, each node in the group needs to perform a handover procedure and re-initiate random access in the new cell after the handover. This re-initiation of random access by each node in the group impacts the limited random access resources, and the large amount of signaling during the random access process can cause a signaling storm. To address this issue, considering that, apart from the migrated IAB node, all descendant nodes of the migrated IAB node in the group undergo handover following the migrated IAB node, the parent node of each descendant node can remain unchanged, and the cell served by the parent node that each descendant node accesses can also remain unchanged (the cell identifier itself can change or not; for example, the NCGI or ECGI of the cell may change, while the physical cell identifier (PCI) of the cell may remain unchanged), it is possible to consider allowing the descendant nodes of the migrated IAB node in the group to perform handover without performing random access (i.e., perform handover without random access). However, handover without random access may cause nodes to be unsure when the handover is successful, thus failing to promptly stop the timer used to detect whether the handover was successful. Timer expiration will lead to handover failure, and the node may initiate processes such as RRC reconstruction, resulting in unnecessary latency. To address this issue, this application provides a solution that enables nodes in a group performing handover without random access to receive indication information and stop timers in a timely manner based on this indication information, thereby improving the success rate of handover, reducing handover latency, and ensuring communication performance after handover.

[0195] Figure 7 This application provides a communication method that can be applied to relay systems, such as those in the IAB system.

[0196] Optional, in Figure 7In a relay system, group handover can occur, where a group is switched from a source access network device to a target access network device. A group undergoing handover includes at least child nodes and a parent node. It is understood that the parent node of a child node remains unchanged during the group handover process. Optionally, the group may also include one or more other IAB nodes. For example, a migrating IAB node in the group can be a parent node, and the group may also include other descendant nodes of the parent node besides its child nodes. Alternatively, a migrating IAB node in the group can be a node between the parent node and the source access network device, and the group may also include other descendant nodes of that node besides its parent and child nodes.

[0197] Optionally, the child node can be an IAB node or a terminal, the parent node can be an IAB node, the parent node's superior node can be an IAB node, the source access network device can be a source IAB donor, and the target access network device can be a target IAB donor.

[0198] by Figure 6 For example, the group undergoing group switching includes IAB node 1, terminal 1, IAB node 4, and terminal 2. The child node is terminal 1 or IAB node 4, and the parent node is IAB node 1; or, the child node is terminal 2, the parent node is IAB node 4, the source access network device is IAB donor 1, and the target access network device is IAB donor 2.

[0199] like Figure 7 As shown, the method includes:

[0200] S701: The access network device sends the first message to the parent node.

[0201] The access network device can be the target access network device for the parent node and the parent node's child nodes during group handover.

[0202] Optionally, the parent node can be referred to as the first node, and the child node can be referred to as the second node. Optionally, there can be one or more other nodes between the second node and the access network device. For ease of description, the following description uses child nodes and parent nodes.

[0203] In one possible implementation, S701 may include the target access network device sending a first message to the source access network device, and the source access network device sending the first message to the parent node.

[0204] It is understood that the source access network device can be the source access network device of the parent node and the child node of the parent node during the group handover process.

[0205] It is understood that there may be one or more other nodes between the source access network device and the parent node, and the source access network device can send the first message to the parent node through these other one or more nodes.

[0206] Optionally, the first message sent by the target access network device to the source access network device may be included in a handover request response message, and the first message sent by the source access network device to the parent node may be included in an F1AP message (e.g., a UE context modification request message).

[0207] S702: The parent node sends a first message to the child node.

[0208] Optionally, S701 to S702 can be described as follows: the access network device sends the first message to the child node through the parent node, or the child node receives the first message from the access network device through the parent node.

[0209] Optionally, after receiving the first message, the child node can perform a handover without random access. In this embodiment, the handover can also be referred to as RRC reconfiguration, master cell group (MCG) change, or secondary cell group (SCG) change.

[0210] Optionally, the period before the child node receives the first message can be referred to as before the switchover.

[0211] Optionally, the first message may be a first RRC reconfiguration message. In this application, the RRC reconfiguration message may be referred to as a switching command message.

[0212] Optionally, the first message may not include the configuration information for random access.

[0213] Optionally, the first message may instruct child nodes to avoid random access, and the instruction may be explicit or implicit.

[0214] For example, the instruction can be explicit, and the first message can include an instruction to avoid random access, according to which the child node avoids random access.

[0215] For example, the instruction may be an implication; the first message may not include the instruction to avoid random access; the child node and the target access network device may agree that when the child node receives the first message, random access is avoided; or, the child node and the target access network device may agree that when the first message does not include random access configuration information, the child node is exempt from random access; or, there may be other ways to provide the instruction in the implementation, and this application embodiment does not limit this.

[0216] Optionally, the first message may include a reconfigurationwithsync information cell.

[0217] Optionally, the aforementioned instruction to avoid random access may be carried in the synchronization reconfiguration cell.

[0218] Optionally, the synchronization reconfiguration information cell does not include the configuration information of the random access.

[0219] Optionally, the child node can determine whether it needs to switch based on the synchronization reconfiguration information cell, and avoid random access during the switch.

[0220] Since child nodes follow their parent nodes in group handover, child and parent nodes do not need to resynchronize. In an IAB network, a parent node may have one or more child nodes. By allowing child nodes to access the parent node's cell without random access, the number of times a child node initiates random access can be greatly reduced. This reduces handover latency and avoids the situation where random access resources are limited when a large number of child nodes initiate random access.

[0221] Optionally, the cell radionetwork temporary identifier (C-RNTI) of the child node can remain unchanged before and after the handover.

[0222] Optionally, C-RNTI is used to uniquely identify a child node in the cell of a parent node, or it can be understood as the identifier of a child node in the cell of the parent node it accesses. The name of C-RNTI is not limited in this application embodiment. C-RNTI in this application can be replaced with other identifiers used to identify child nodes in a cell.

[0223] As one implementation, the first message may not include the C-RNTI of the child nodes.

[0224] In this method, the first message does not include the C-RNTI of the child node. After the child node receives the first message, it can continue to use the C-RNTI before receiving the first message by default.

[0225] As another implementation, the first message may include indication information indicating that the C-RNTI of the child node remains unchanged.

[0226] In this method, the child node can determine that its C-RNTI remains unchanged based on the indication information, so that after receiving the first message, it can continue to use the C-RNTI before receiving the first message.

[0227] As another implementation, the first message may include the C-RNTI of the child node prior to receiving the first message.

[0228] In this method, the child node can use the C-RNTI based on the C-RNTI carried in the first message.

[0229] Although the parent node of the child node remains unchanged before and after the handover, the access network equipment serving the child node changes. For example, the access network equipment serving the child node changes from the source access network equipment to the target access network equipment. Since part of the identifier (e.g., NCGI) of the cell accessed by the child node is the identifier of the access network equipment, although the cell accessed by the child node remains the same before and after the handover, the identifier of the accessed cell changes. In other words, part of the configuration of the cell accessed by the child node changes. Through the above implementation methods, the C-RNTI of the child node can remain unchanged, thereby reducing the process of configuring C-RNTI for the child node, avoiding a large amount of C-RNTI reconfiguration work during IAB group handover, and reducing the power consumption of the child node, saving its power.

[0230] Optionally, the C-RNTI of the child node can change before and after the handover. For example, the first message may include an updated C-RNTI, and the child node can use the updated C-RNTI in the first message during the handover process and after the handover is completed. This application does not limit this.

[0231] S703: Child node starts timer.

[0232] Once a child node receives the first message, it can start a timer.

[0233] Optionally, the timer can be used to monitor whether the child node switch was successful. Optionally, the duration of the timer can be included in the first message mentioned above.

[0234] S704: The child node sends a second message to the parent node.

[0235] Optionally, after receiving the first message, the child node can perform a handover without random access. After the handover is completed, the child node sends a second message to the parent node.

[0236] S705: The parent node sends a second message to the target access network device.

[0237] Optionally, S705 and S706 can be described as follows: the child node sends a second message to the target access network device through the parent node; or the target access network device receives a second message from the child node through the parent node.

[0238] Optionally, the second message may be a first RRC reconfiguration completion message, which may be referred to as a handover completion message.

[0239] S706: The target access network device sends the first instruction information to the parent node.

[0240] Optionally, after parsing the second message, the target access network device can determine that the child node reconfiguration is complete. The target access network device can then send the first indication information to the parent node to trigger the parent node to send the second indication information to the child node.

[0241] Optionally, the first indication information may instruct the parent node to send the second indication information to the child node, or it may instruct the child node to complete the reconfiguration, or it may instruct the child node to stop the timer, or the first indication information may instruct other content. Any indication information that can trigger the parent node to send the second indication information to the child node can be the first indication information in this application.

[0242] Optionally, the first indication information may include the identifier of the child node. It is understood that a parent node may have multiple child nodes. By carrying the identifier of the child node in the first indication information, the parent node, upon receiving the first indication information, can determine which child node to send the second indication information to.

[0243] S706 is optional.

[0244] S707: The parent node sends a second instruction message to the child node.

[0245] In one implementation, there is a step S706 where, in response to the first instruction information, the parent node sends a second instruction information to the child node.

[0246] In another implementation, S706 is not present. After the parent node receives the second message from the child node, or after the parent node sends the second message to the target access network device, it can determine that the child node reconfiguration is complete, and the parent node can send the second instruction information to the child node.

[0247] In both of the above embodiments, the second indication information can instruct the timer to be stopped. In the embodiments of this application, the timer can be a T304 timer or the timer can have other names, and this application does not limit this.

[0248] For example, the second indication information can be indicated explicitly, and the second indication information occupies 1 bit or more bits, and the 1 bit or more bits of information indicates to stop the timer.

[0249] For example, the second indication information can be provided through implication. This second indication information can be a first type of MAC CE, where "first type" can be understood as a specific type of MAC CE. When a child node receives a MAC CE of this type, it can stop the timer. This first type of MAC CE may or may not carry information; this application does not limit this. Optionally, the type of MAC CE can be identified by the logical channel ID (LCID) corresponding to the MAC CE as agreed in the protocol. This application does not limit the type of MAC CE.

[0250] For example, the second indication information can be provided implicitly. This second indication information can be a MAC CE carrying the UE Contention Resolution Identity. Optionally, the MAC CE can be a specific type of MAC CE. Optionally, the type of the MAC CE can be identified by the logical channel identifier (LCID) corresponding to the MAC CE as defined in the protocol.

[0251] Optionally, the MAC CE carrying the UE contention resolution identifier can be transmitted in the PDSCH, which is scheduled via the PDCCH and scrambled by the child node's C-RNTI. Therefore, after the child node successfully parses the MAC CE carrying the UE contention resolution identifier, it can assume it has received the second indication information and thus stop the timer.

[0252] Optionally, the MAC CE carrying the UE contention resolution identifier can be any type of MAC CE, and this application embodiment does not limit this.

[0253] Optionally, the UE contention resolution identifier can be any value. For example, the value can be the C-RNTI of the child node, or it can be the value of one or more bits of the C-RNTI. Alternatively, the value may be any value and may not have any meaning. This application does not impose any restrictions on this.

[0254] S709: Stop timer for child nodes.

[0255] After receiving the second instruction information, the child node stops the timer according to the second instruction information.

[0256] Figure 7 In this method, the parent node sends a second indication message to the child node, which allows the child node to stop the timer in time, avoiding handover failures and subsequent failure handling (such as performing recovery operations like RRC reconstruction) due to timer timeout, reducing latency and improving the continuity of service transmission.

[0257] Optional, Figure 7 The method may also include: the target access network device sending a third message to the parent node. Specifically, this may include the target access network device sending a third message to the source access network device, and the source access network device sending a third message to the parent node.

[0258] Optionally, the third message can be a third RRC reconfiguration message.

[0259] As one implementation, the parent node can perform a handover without random access based on the third message. This third message can instruct the parent node to avoid random access, either explicitly or implicitly, as detailed in the first message, which will not be described further here. Optionally, the parent node's C-RNTI before and after the handover can remain unchanged or change, as detailed in S702, which will not be described further here.

[0260] In another implementation, the parent node can perform a random access handover based on this third message. This third RRC reconfiguration message may include random access configuration information.

[0261] In both implementations described above, the parent node can start a timer after receiving the third message. This timer is used to monitor whether the parent node switch was successful.

[0262] Optionally, the parent node can receive the first message first or send the first message to the child node first, and then receive the third message. This avoids the situation where the parent node performs a switch after receiving the third message, stops receiving messages and / or data from the source host node, and is unable to forward the first message to the child node. This can be implemented through the following methods.

[0263] In one implementation, after receiving the first message or sending the first message to the child node, the parent node sends a third indication message to the source access network device to trigger the source access network device to send a third message to the parent node.

[0264] Optionally, the third indication information may instruct the source access network device to send a third message to the parent node, or it may indicate that the parent node has received the first message from the source access network device, or has sent the first message to the child node, or it may indicate that the parent node is ready to receive the third message, etc. It should be noted that any information used to trigger the source access network device to send a third message to the parent node can be considered as the third indication information of this application. The third indication information may also indicate other content, and this application embodiment does not limit this.

[0265] This application uses a child node as an example. It can be understood that a parent node can have one or more child nodes, and each child node will receive the first message from the parent node.

[0266] Optionally, the parent node may receive the first message from all child nodes from the source access network device, or after sending the first message of each child node to the source access network device, the parent node may send the third indication information to the source access network device.

[0267] Optionally, the third indication information can be carried in an F1AP message, which can be a non-UE associated F1AP message.

[0268] Alternatively, after receiving the first message from all child nodes or sending the first message of the child node to each child node, the parent node may send an F1AP message to the source access network device, such as a UE context modification response message for the child node. The third indication information may be carried in the UE context modification response message sent by the parent node for the last child node.

[0269] As another implementation, after receiving the first message or sending the first message to the child node, the parent node can send an F1AP message to the source access network device, such as a UE context modification response message for the child node. After receiving the UE context modification response message, the source access network device can send a third message to the parent node.

[0270] It is understandable that if a parent node has multiple child nodes, after receiving the first message from each child node or sending the first message of that child node to each child node, the parent node can send an F1AP message to the source access network device, such as a UE context modification response message for that child node. The source access network device can send a third message to the parent node after receiving the UE context modification response message for all child nodes sent by the parent node.

[0271] Optional, Figure 7The method may further include: the source access network device sending a handover request message to the target access network device, the handover request message including one or more of the following: a temporary identifier of a cell radio network for one or more nodes, an identifier of the cell accessed by the one or more nodes, and hierarchical information of one or more descendant nodes in the network topology. The one or more nodes are one or more nodes in a group, including child nodes and parent nodes.

[0272] Optionally, the hierarchical information of one or more nodes in the network topology is used to determine the duration of the timer for that one or more nodes.

[0273] Optionally, the first message and / or the third message may be carried in the handover request response message sent by the target access network device to the source access network device.

[0274] Optionally, the first message mentioned above includes information about the duration of the timer. The child node in S703 can set the timer and start the timer based on the duration information of the timer.

[0275] Optionally, the third message includes information about the timer's duration. After receiving the third message, the parent node sets the timer according to the timer's duration information in the first message and starts the timer.

[0276] Figure 8 This application provides a group handover method, which can be applied to relay systems such as the IAB system. The following describes a method in conjunction with... Figure 8 right Figure 7 Further explanation is needed.

[0277] Figure 8 In this process, a group undergoes a handover, switching from a source access network device to a target access network device. This group includes at least a first node, a second node, and a third node. The third node is a migrating IAB node; the third node is the parent node of the second node, and the second node is the parent node of the first node. Before the handover, the third node is connected to the source parent node; after the handover, it is connected to the target parent node. Optionally, the source parent node can be the source access network device, and the target parent node can be the target access network device. The migrating IAB node is an IAB node whose parent node needs to be replaced during the handover process.

[0278] Optional, Figure 8 The first and second nodes in the array can be respectively Figure 7 Child nodes and parent nodes in, or Figure 8 The second and third nodes in the data can be respectively Figure 7 The child nodes and parent nodes in the table.

[0279] It should be noted that, optionally, the third node may also have one or more other child nodes, and the content of the second node in this application also applies to the other one or more child nodes of the third node. Alternatively, the second node may also have one or more other child nodes, and the content of the first node in this application also applies to the other one or more child nodes of the second node.

[0280] by Figure 6 For example, the first node is terminal 2, the second node is IAB node 4, the third node is IAB node 1, the source access network device is IAB donor 1, the target access network device is IAB donor 2, the source parent node is IAB node 2, and the target parent node is IAB node 3. Figure 6 If IAB node 1 has a child node terminal 1, the content of IAB node 4 also applies to terminal 1. If IAB node 4 has a child node IAB node 5 (not shown in the diagram), the content of terminal 2 also applies to IAB node 5.

[0281] like Figure 8 As shown, the method includes:

[0282] S801: The third node sends a measurement report to the source parent node.

[0283] S802: The source parent node sends a measurement report to the source access network device.

[0284] S803: The source access network device sends a handover request message to the target access network device.

[0285] Optionally, the source access network device determines, based on the measurement report, whether the third node should switch from the source access network device to the target access network device, and sends a handover request message to the target access network device.

[0286] Optionally, the group handover request message may include one or more of the following: the cell identifier of the cell accessed by each node in the group (e.g., an IAB node or a terminal), the C-RNTI of the node in the accessed cell, and the hierarchical information of the node in the network topology.

[0287] Optionally, the cell identifier of the cell accessed by each node can be the cell identifier of the primary cell accessed by the node. The primary cell can be called a special cell (SpCell).

[0288] Optionally, in the above-described embodiments, the cell identifier may include one or more of the following: physical cell identifier (PCI), NR cell identity (NCI), NR cell global identifier (NCGI), and E-UTRAN cell global identifier (ECGI).

[0289] Optionally, the cell identifier of the cell to which the IAB node (i.e., the third node) is being migrated can be the cell identifier of the target cell of the third node. It is understood that after the source access network device determines the handover, it can decide to include the cell identifier of the target cell of the third node in the handover request message and send it to the target access network device. Optionally, the cell identifier of the target cell can be NGCI or ECGI.

[0290] Optionally, during the group handover process, the parent node of the descendant node of the migrated IAB node remains unchanged. The cell identifier of the cell that the descendant node accesses can be the cell identifier of the cell that the descendant node accessed before the handover.

[0291] Optionally, the cell identifier of the cell a node accesses and the C-RNTI of the node in the accessed cell can uniquely identify the node.

[0292] Optionally, hierarchy information is used to represent the relative position of a node in the network topology or its connection relationship with other nodes.

[0293] For example, the hierarchy information can be a hierarchy or position relative to the migration relay node (i.e., the third node). For instance, assuming the third node's hierarchy is 0 (it can be other values, which are not limited in this embodiment), one or more of the third node's child nodes have a hierarchy of 1, i.e., the second node's hierarchy is 1; one or more of the third node's grandchild nodes have a hierarchy of 2, i.e., the first node's hierarchy is 2, and so on. If a descendant node is connected to the third node via an X-hop link, then the descendant node's hierarchy information can be denoted as X, where X is a positive integer. Alternatively, the hierarchy information can be a hierarchy relative to other nodes, which can be the second node, the first node, or a node from the source parent node to the source host node, etc., which are not limited in this embodiment.

[0294] In one implementation, the handover request message can be a group handover request message, which is used to request a handover for a group.

[0295] Table 1 is a schematic diagram of a group handover request message. As shown in Table 1, the group handover request message includes multiple items, each item corresponding to a node. Each node's items further include one or more items, which include the cell identifier of the cell accessed by each node, C-RNTI, and / or hierarchical information. In Table 1, the items for each node are listed side by side.

[0296]

[0297] Table 1

[0298] Table 2 is another schematic diagram of a group handover request message. As shown in Table 2, the group handover request message includes an item corresponding to a third node. The third node's item further includes one or more items, which include the cell identifier, C-RNTI, and / or hierarchical information of the cell accessed by the third node, and a second node. The second node's item includes the cell identifier, C-RNTI, and / or hierarchical information of the cell accessed by the second node, and a first node. The second node's item includes the cell identifier, C-RNTI, and / or hierarchical information of the cell accessed by the second node. In Table 2, each node's item includes the items of its child nodes.

[0299]

[0300] Table 2

[0301] Optionally, if each node's item includes the items of its child nodes, as shown in Table 2, the node's item may not carry its hierarchical information. The hierarchical information of each node can be obtained through the mutual inclusion relationships of its items. For example, based on the structure of the information in Table 2, the relative topological relationships between the first, second, and third nodes can be inferred (the second node is a child of the third node, and the first node is a child of the second node). Furthermore, the hierarchical information of each node can be obtained (for example, if the third node's hierarchical level is 0, the second node's hierarchical level is 1, and the first node's hierarchical level is 2).

[0302] Tables 1 and 2 above are merely illustrative; group switching request messages may exist in other forms, and this application embodiment does not limit them.

[0303] As another implementation, the switching request message may contain one or more independent switching request messages, where one switching request message corresponds to one node, or it can be understood that one switching request message is a node requesting a switching.

[0304] Optionally, in this implementation, the handover request message of each node includes the cell identifier of the cell to which the node is accessing, the C-RNTI of the node in the cell to which it is accessing, and / or the hierarchical information of the node in the network topology.

[0305] S804: The target access network device sends a handover request response message to the source access network device.

[0306] In one implementation, if the handover request message in S803 is a group handover request message, the handover request response message in S804 can be a group handover request response message, which can be called a group handover request response message.

[0307] Optionally, the group switchover request response message includes an RRC reconfiguration message for each node.

[0308] For clarity, this application refers to the RRC reconfiguration message of the first node as the first RRC reconfiguration message, the RRC reconfiguration message of the second node as the second RRC reconfiguration message, and the RRC reconfiguration message of the third node as the third RRC reconfiguration message.

[0309] In this embodiment, the group handover request response message includes a first RRC reconfiguration message, a second RRC reconfiguration message, and a third RRC reconfiguration message.

[0310] As another implementation, the handover request message in S803 may include one or more independent handover request messages, and the handover request response message in S804 may include one or more independent handover request response messages. Each handover request response message corresponds to a node, and the handover request response message of each node includes the RRC reconfiguration message of that node.

[0311] In this alternative implementation, the handover request message in S803 includes a first handover request message, a second handover request message, and a third handover request message, and the handover request response message in S804 includes a first handover request response message, a second handover request response message, and a third handover request response message. Specifically, the first handover request response message is a handover request response message from a first node, including a first RRC reconfiguration message; the second handover request response message is a handover request response message from a second node, including a second RRC reconfiguration message; and the third handover request response message is a handover request response message from a third node, including a third RRC reconfiguration message.

[0312] Optionally, in the above-described embodiments, the RRC reconfiguration message for each node may include the duration information of the node's timer. The duration information of the node's timer will be further explained below.

[0313] Optionally, the target access network device can determine the duration of the timer for the node based on the hierarchical information of each node in the handover request response message in S803.

[0314] Optionally, the higher the level of the descendant node, the more hops the backhaul link with the migrating node (i.e., the third node) has, and the longer the timer duration. The lower the level of the node, the fewer hops the backhaul link with the third node has, and the shorter the timer duration.

[0315] For example, the first node has a level of 2 and a timer duration of 200ms; the second node has a level of 1 and a timer duration of 150ms; the third node has a level of 0 and a timer duration of 100ms.

[0316] In one implementation, the duration information of the timer can directly indicate the duration of the timer.

[0317] For example, the timer duration information of the first node indicates 200ms, the timer duration information of the second node indicates 150ms, and the timer duration information of the third node indicates 100ms.

[0318] In another implementation, the timer's duration information may include one or more parameters used to determine the timer's duration. After receiving the timer's duration information from its own node, each node can obtain the timer's duration based on the one or more parameters.

[0319] Optionally, the duration of the timer can be obtained by some operation of one or more parameters, such operation may include multiplication or idempotency, and this application does not limit the operation method.

[0320] For example, one or more parameters include the duration of the base timer and the scaling factor. Each node can calculate the duration of its timer using the duration of the base timer and the scaling factor.

[0321] For example, the timer duration information for the first node includes a base timer duration of 50ms and a scaling factor of 4. The first node can multiply 50 by 4 to obtain a timer duration of 200ms. Similarly, the timer duration information for the second node includes a base timer duration of 50ms and a scaling factor of 3. The first node can multiply 50 by 3 to obtain a timer duration of 150ms. Finally, the timer duration information for the first node includes a base timer duration of 50ms and a scaling factor of 2. The first node can multiply 50 by 2 to obtain a timer duration of 100ms.

[0322] By sending hierarchical information from the source access network device to the target access network device, the target access network device can reasonably determine the duration of the timer based on the hierarchy of the node, avoiding handover failures caused by unreasonable timer duration settings, reducing handover latency, and reducing signaling overhead.

[0323] Optionally, the handover request message and handover request response message of S803 to S804 can be combined with... Figure 7 The handover request message and the handover request response message refer to each other.

[0324] S805: The source access network device sends a downlink F1AP message, such as a UE context modification request message, to the second node, which includes a first RRC reconfiguration message. Optionally, the downlink F1AP message (e.g., the UE context modification request message) may also include indication information instructing the second node to stop data transmission with the first node.

[0325] Optionally, this indication information can be carried in a transmission action indicator cell. The second node can read this indication information and then stop data transmission with the first node, including downlink data transmission and / or uplink data transmission with the first node. Specifically, the second node can stop data transmission with the first node after executing step S806.

[0326] S806: The second node sends the first RRC reconfiguration message to the first node.

[0327] Optionally, the first RRC reconfiguration message may not include random access configuration information. Optionally, the first RRC reconfiguration message may instruct child nodes to be exempt from random access, which can be explicit or implicit, and can be referred to the content of the first message in S702.

[0328] Optionally, the C-RNTI of the first node can remain unchanged before and after the handover. Specifically, the first RRC reconfiguration message may not include the C-RNTI of the first node, or may contain indication information indicating that the C-RNTI of the first node remains unchanged, or may include the C-RNTI of the first node before receiving the first message. Alternatively, the C-RNTI of the first node can change before and after the handover. See section S702 for details.

[0329] S807: Start timer for the first node.

[0330] After the first node receives the first RRC reconfiguration message, it can start a timer. Refer to S703 for details.

[0331] Optionally, if the first RRC reconfiguration message includes information about the timer's duration, the first node can obtain the timer's duration based on this information, set the timer, and then start the timer.

[0332] S808: The second node sends an uplink F1AP message to the source host node, such as a UE context modification response (UECONTEXT MODIFICATION RESPONSE) message.

[0333] Step S808 is an optional step. If the downlink F1AP message in step S805 is a UE context modification request message, then step S808 is required.

[0334] The UE context modification response message in S808 can be understood as the UE context modification response message fed back by the second node to the first node.

[0335] S809: The first node sends the first RRC reconfiguration complete message to the second node.

[0336] S810: The source access network device sends a downlink F1AP message, such as a UE context modification request message, to the third node, which includes a second RRC reconfiguration message. Optionally, the downlink F1AP message (e.g., the UE context modification request message) may also include indication information instructing the third node to stop data transmission with the second node. The third node can read this indication information and then stop data transmission with the second node, including downlink data transmission and / or uplink data transmission with the second node. The content of this indication information can be referred to in S805.

[0337] Optionally, S810 can occur after S805 and / or S806. Specifically, it can be done in the following ways:

[0338] In one implementation, after S805 or S806, the second node can send indication information to the source access network device to trigger the source access network device to send a second RRC reconfiguration message to the second node, that is, to trigger the source access network device to execute S810. This indication information can be found in [reference needed]. Figure 7 The content of the third instruction information in the document.

[0339] Optionally, if the second node has other child nodes besides the first node, the second node can receive RRC reconfiguration messages from all child nodes from the source access network device or send RRC reconfiguration messages to all child nodes and then send indication information to the source access network device.

[0340] For example, withFigure 6 For example, the second node is IAB node 4, the first node can be terminal 2, and IAB node 4 can have a child node IAB node 5 in addition to the child node terminal 2. Figure 6 (Not illustrated in the diagram), after IAB node 4 receives the first RRC reconfiguration message (the RRC reconfiguration message of terminal 2) and the RRC reconfiguration message of IAB node 5 from IAB donor 1, IAB node 4 sends an indication message to IAB donor 1. Alternatively, after IAB node 4 sends the first RRC reconfiguration message to terminal 2 and sends the RRC reconfiguration message of IAB node 5 to IAB node 5, IAB node 4 sends an indication message to IAB donor 1.

[0341] Optionally, this indication information can be carried in an uplink F1AP message sent to the source access network device.

[0342] Optionally, this indication information can be carried in an uplink F1AP message (e.g., a UE context modification request response message) sent by the second node to the last child node.

[0343] For example, IAB node 4 first receives a UE context modification request message from terminal 2 from IAB donor 1, which includes terminal 2's RRC reconfiguration message. IAB node 4 then sends the RRC reconfiguration message to terminal 2. IAB node 4 also sends a UE context modification request response message from terminal 2 to IAB donor 1. Next, IAB node 4 receives a UE context modification request message from IAB node 5 from IAB donor 1, which also includes IAB node 5's RRC reconfiguration message. IAB node 4 sends the RRC reconfiguration information to IAB node 5. Finally, IAB node 4 sends a UE context modification request response message from IAB node 5 to IAB donor 1. This indication information can be carried in the UE context modification request response message sent by IAB node 4 from IAB node 5 to IAB donor 1.

[0344] As another implementation method, the source access network device can execute S810 after S808.

[0345] Optionally, if the second node has other child nodes besides the first node, the source access network device may execute S810 after receiving the UE context modification response message for all child nodes from the second node.

[0346] For example, after IAB donor 1 receives the UE context modification request response message for terminal 2 and the UE context modification request response message for IAB node 5 sent by IAB node 4, it executes S810.

[0347] By implementing the above two methods, we can avoid the situation where, if S810 occurs before S805, the second node will perform a handover action after receiving the second RRC reconfiguration message, stopping data transmission with the source access network device. This would prevent the second node from receiving and forwarding the first RRC reconfiguration message to the first node. This ensures that the second node can forward the first RRC reconfiguration message to the first node, thus guaranteeing the success rate of the first node's handover.

[0348] S811: The third node sends a second RRC reconfiguration message to the second node.

[0349] Optionally, the second RRC reconfiguration message may not include random access configuration information. Optionally, the second RRC reconfiguration message may instruct child nodes to bypass random access; this can be explicit or implicit, as detailed in the reference. Figure 7 The content of the first message in China.

[0350] Optionally, the C-RNTI of the second node can remain unchanged before and after the handover. Specifically, the second RRC reconfiguration message may not include the C-RNTI of the second node, or may contain indication information indicating that the C-RNTI of the second node remains unchanged, or may include the C-RNTI of the second node before receiving the first message. Alternatively, the C-RNTI of the second node can change before and after the handover. See section S702 for details.

[0351] S812: Start the timer on the second node.

[0352] After receiving the second RRC reconfiguration message, the second node can start a timer. Refer to section S703 for details.

[0353] Optionally, if the second RRC reconfiguration message includes information about the timer's duration, the second node can obtain the timer's duration based on this information, set the timer, and then start the timer.

[0354] S813: The third node sends an uplink F1AP message, such as a UE context modification response message, to the source host node.

[0355] Step S813 is optional. If the downlink F1AP message in step S810 is a UE context modification request message, then step S813 is required. The UE context modification response message in S813 can be understood as the UE context modification response message fed back by the third node to the second node.

[0356] S814: The second node sends a second RRC reconfiguration complete message to the third node.

[0357] S815: The source access network device sends downlink F1AP messages to the source parent node, such as UE context modification request messages, including third RRC reconfiguration messages.

[0358] Optionally, the downlink F1AP message (e.g., a UE context modification request message) may also include indication information instructing the source parent node to stop data transmission with the third node. The source parent node can read this indication information and then stop data transmission with the third node, including downlink data transmission and / or uplink data transmission with the third node. The content of this indication information can be referenced in S805 and S810.

[0359] Optionally, similar to how S810 occurs after S805 and / or S806, S815 can occur after S810 and / or S811. Specifically, this can be implemented as follows:

[0360] In one implementation, after S810 or S811, the third node can send indication information to the source access network device to trigger the source access network device to send a third RRC reconfiguration message to the third node. This indication information can be found in [reference needed]. Figure 7 The content of the third instruction information in the document.

[0361] Optionally, if the third node has other child nodes besides the second node, the third node can receive RRC reconfiguration messages from all child nodes from the source access network device or send RRC reconfiguration messages to all child nodes before sending the indication information to the source access network device.

[0362] For example, with Figure 6For example, the third node is IAB node 1, the second node is IAB node 4, and IAB node 1 can have a child node terminal 1 in addition to its child node 4. After receiving the second RRC reconfiguration message (the RRC reconfiguration message from IAB node 4) and the RRC reconfiguration message from terminal 1 from IAB donor 1, IAB node 1 can send this indication information to IAB donor 1. Alternatively, IAB node 1 can send the second RRC reconfiguration message to IAB node 4, and after sending the RRC reconfiguration message from terminal 1 to terminal 1, IAB node 1 can send this indication information to IAB donor 1.

[0363] As an alternative implementation, the source access network device can execute S815 after S813.

[0364] Optionally, if the third node has other child nodes besides the second node, the source access network device may execute S815 after receiving the UE context modification response message for all child nodes from the third node.

[0365] For example, after receiving the UE context modification request response message for terminal 1 and the UE context modification request response message for IAB node 4 sent by IAB node 1, IAB donor 1 executes S815.

[0366] S816: The source parent node sends a third RRC reconfiguration message to the third node.

[0367] In one implementation, the third RRC reconfiguration message can instruct the third node to perform random access in the target cell. The third RRC reconfiguration message can include the cell identifier of the target cell (e.g., the PCI of the target cell). The target cell is the cell served by the target parent node of the third node.

[0368] Optionally, the third RRC reconfiguration message may include configuration information for random access and / or a new C-RNTI.

[0369] As an alternative implementation, the third RRC reconfiguration message can instruct the third node to bypass random access.

[0370] Optionally, the third RRC reconfiguration message may not include random access configuration information. Optionally, the third RRC reconfiguration message may instruct child nodes to bypass random access; this can be explicit or implicit, as detailed in the reference. Figure 7 The content of the first message in China.

[0371] Although the parent node of the third node has changed from the source parent node to the target parent node, if the source parent node and the target parent node are synchronized, the third node does not need to synchronize with the target parent node again. By avoiding random access through the third node, the latency caused by random access can be avoided and the handover latency can be reduced. On the other hand, it can avoid the situation where random access resources are limited.

[0372] Optionally, the C-RNTI of the third node can remain unchanged before and after the handover. Specifically, the third RRC reconfiguration message may not include the third node's C-RNTI, or may contain indication information indicating that the third node's C-RNTI remains unchanged, or may include the third node's C-RNTI before receiving the third RRC reconfiguration message. Alternatively, the third node's C-RNTI can change before and after the handover. See section S702 for details.

[0373] S817: Start the timer on the third node.

[0374] After receiving the third RRC reconfiguration message, the third node can start a timer. Refer to S703 for details.

[0375] Optionally, if the third RRC reconfiguration message includes information about the timer's duration, the third node can obtain the timer's duration based on this information, set the timer, and then start the timer.

[0376] S818: The source parent node sends an uplink F1AP message, such as a UE context modification response message, to the source host node.

[0377] Step S818 is optional. If the downlink F1AP message in step S815 is a UE context modification request message, then step S818 is required. The UE context modification response message in S818 can be understood as the UE context modification response message fed back by the source parent node to the third node.

[0378] Optionally, after receiving the third RRC reconfiguration message, the third node can perform random access or non-random access in the target cell based on the third RRC reconfiguration message. This will be explained below in conjunction with Method 1 and Method 2. It should be noted that Method 1 and Method 2 are mutually exclusive. Method 1 includes S819 and S820, and Method 2 includes S823 to S825. Regardless of whether it is Method 1 or Method 2, S821 and S822 are present.

[0379] S819: The third node can perform random access based on the third RRC reconfiguration message.

[0380] In this implementation, the parent node of the third node has changed, and the third node can resynchronize with the target parent node through a random access procedure to ensure the performance of communication between the third node and the target parent node.

[0381] S820: Stop timer for the third node.

[0382] After the third node successfully accesses the S819 via random connection, the third node can stop the timer.

[0383] S821: The third node sends a third RRC reconfiguration completion message to the target parent node.

[0384] S822: The target parent node sends a third RRC reconfiguration completion message to the target access network device.

[0385] Optionally, the third RRC reconfiguration completion message in S822 can be carried in the uplink F1AP message, such as in the uplink RRC message transfer (UL RRC message transfer) message.

[0386] S823: The target access network device sends the first instruction information to the target parent node.

[0387] In Method 2, the third node is exempt from random access, and there are no S819 and S820. After S821 and S822, the target access network device can determine that the third node handover is complete after parsing the third RRC reconfiguration completion message. The target access network device can then send the first indication information to the target parent node to trigger S824.

[0388] S823 is optional.

[0389] S824: The target parent node sends a second instruction message to the third node.

[0390] In one implementation, there is a step S823, in response to the first instruction information, the target parent node sends the second instruction information to the third node.

[0391] In another implementation, there is no second instruction information sent from the target parent node to the third node after S823, S821 or S822.

[0392] S825: Stop timer for the third node.

[0393] After receiving the second instruction information, the third node stops the timer according to the second instruction information.

[0394] S826: The source access network device sends a message containing data packet transmission status, such as a sequence number (SN) status transfer message, to the target access network device.

[0395] It includes uplink and / or downlink data packet transmission status information of the source access network device, which may be PDCP packet data unit (PDU).

[0396] After receiving the SN Status Transfer message, the target access network device can continue uplink and / or downlink data transmission after the handover is completed at the third node, based on the data packet transmission status in the message, thus avoiding the loss of terminal service data.

[0397] Optionally, if the source access network device (CU) has a separate CP and UP architecture, the CP of the CU can initiate a bearer context modification procedure to obtain the uplink / downlink data packet transmission status (e.g., the SN status information of the PDCP PDU corresponding to each UE data radio bearer) and exchange endpoint configuration information for data forwarding between the source and target access network devices. For example, the CP of the CU can send a bearer context modification request message to the UP of the CU, and the UP of the CU can send a bearer context modification response message to the CP. This response message includes the SN status information of the uplink / downlink PDCP PDU and may also include the tunnel endpoint information used by the UP of the CU for data forwarding.

[0398] Optionally, if the target access network device has a separate CU CP and CU UP architecture, the source access network device sends data and SN status to the CP of the target access network device's CU. The CP of the target access network device's CU can initiate a bearer context modification procedure, thereby sending downlink transport network layer address information (DLTNL) of the F1-U interface and / or the transmission status of data packets (e.g., SN status information corresponding to the PDCP PDU of each UE data radio bearer) to the UP of the target access network device's CU. For example, the CP of the target access network device's CU can send a bearer context modification request message to the UP of the target access network device's CU, the context modification request message including the transmission status of data packets, and the UP of the target access network device's CU can send a bearer context modification response message to the CP of the target access network device's CU.

[0399] Optional, Figure 8 The method may also include: the target access network device sending an RRC reconfiguration message to the third node, wherein the RRC reconfiguration message may include the configuration information of the third node's BAP layer, and / or the configuration information of the backhaul RLC channel between the third node and the target parent node.

[0400] Optionally, the configuration information of the BAP layer of the third node, and / or the configuration information of the backhaul RLC channel between the third node and the target parent node can be included in the third RRC reconfiguration message in S815 and S816.

[0401] Optionally, the configuration information of the third node's BAP may include the BAP layer identifier assigned to the third node by the target access network device, and the default uplink BAP layer routing ID. The configuration information of the third node's BAP may also include one or more other non-default uplink BAP layer routing identifiers, and the BAP layer identifier of the next hop (i.e., the target parent node) of the third node corresponding to each uplink BAP layer routing identifier. Each uplink BAP layer routing identifier (including the default uplink BAP layer routing identifier) ​​contains a BAP address and a BAP path ID. The BAP address identifies the target access network device, or the DU of the target access network device, and the BAP path ID identifies a transmission path from the third node to the device identified by the BAP address.

[0402] It is understandable that the configuration information of the BAP layer of the third node contained in the RRC reconfiguration message can be used to transmit the corresponding data packets in step S827, including, for example, the F1AP message for establishing an F1 interface between the third node and the target access network device, and the SCTP handshake message related to the establishment of the SCTP association process between the third node and the target access network device.

[0403] Optionally, the configuration information for the RLC channel backhaul between the third node and the target parent node may include the configuration information for the default RLC channel backhaul between the third node and the target parent node.

[0404] S827: The third node establishes an F1 interface with the target access network device.

[0405] Optionally, the third node may establish an SCTP association with the target access network device before establishing the F1 interface.

[0406] For example, a third node can initiate an F1 interface establishment process for the target access network device. Alternatively, a third node can initiate an F1 interface reconstruction process for the target access network device, triggering the target access network device to request the context of the F1 interface between the source access network device and the third node, which is maintained by the source access network device. The target access network device then updates the context of that F1 interface. Yet another example is that the target access network device first obtains the context of the F1 interface between the source access network device and the third node, which is maintained by the source access network device, and then initiates an F1 interface context update process to update the context of the F1 interface between the source access network device and the third node.

[0407] Optionally, after S827, the method may further include: the target access network device sending an updated BAP layer configuration to the third node, wherein the configuration information in this step may include one or more of the following:

[0408] When the third node acts as an access IAB node, the uplink mapping configuration includes the BAP layer routing identifier for sending uplink data packets, the identifier of the next-hop node corresponding to the routing identifier, and the identifier of the BH RLC channel between the third node and the next-hop node for carrying such uplink data packets. The uplink data packets here can be any of the following: UE-related F1AP messages, non-UE-related F1AP messages, non-F1 interface messages, and F1-U data packets. The bearer mapping relationship when the third node acts as an intermediate IAB node specifically includes: the identifier of the previous hop node of the third node, the identifier of the BH RLC channel on the link between the third node and the previous hop node, the identifier of the next hop node of the third node, and the identifier of the BH RLC channel on the link between the third node and the next hop node.

[0409] S828: The third node sends an uplink F1AP message to the target access network device, which includes a second RRC reconfiguration completion message.

[0410] Optionally, the second RRC reconfiguration completion message of S828 can be carried in the UL RRC message transfer message.

[0411] S829: The target access network device sends a third instruction message to the third node.

[0412] In S829, after the target access network device receives and parses the second RRC reconfiguration completion message, it can determine that the second node handover is complete. The target access network device can then send a third indication message to the third node to trigger S830.

[0413] S829 is optional.

[0414] S830: The third node sends the fourth instruction information to the second node.

[0415] In one implementation, there is a step S829 where, in response to the third instruction information, the third node sends a fourth instruction information to the second node.

[0416] In another implementation, S829 is not present. After S828, the third node sends a fourth instruction message to the second node.

[0417] S831: Stop timer for the second node.

[0418] After receiving the fourth instruction, the second node stops the timer according to the fourth instruction.

[0419] S832: The second node establishes an F1 interface with the target access network device.

[0420] For details, please refer to the process of establishing the F1 interface between the third node and the target access network device mentioned above, which will not be described here.

[0421] Optionally, the target access network device may also send BAP layer configuration information and / or backhaul RLC channel configuration information to the second node. For details, please refer to the content of the third node. The third node in S827 can be replaced with the second node.

[0422] S833: The second node sends an uplink F1AP message to the target access network device, which includes the first RRC reconfiguration completion message.

[0423] Optionally, the first RRC reconfiguration completion message in S830 can be carried in the UL RRC message transfer message.

[0424] S834: The target access network device sends the fifth instruction information to the second node.

[0425] In S833, after the target access network device receives and parses the first RRC reconfiguration completion message, it can determine that the first node handover is complete. The target access network device can then send the fifth indication information to the second node to trigger S835.

[0426] S835: The second node sends the fifth instruction message to the first node.

[0427] In one implementation, there is a step S8304, in response to the fourth instruction information, the second node sends the fifth instruction information to the first node.

[0428] In another implementation, S834 is not present. After S833, the second node sends a fourth instruction message to the first node.

[0429] S836: Stop timer for the first node.

[0430] After receiving the fifth instruction, the first node stops the timer according to the fifth instruction.

[0431] S837: The target access network device completes the path handover with the core network.

[0432] Optionally, the core network may transfer the user plane path for transmitting services of third nodes and their descendant nodes from the source access network device to the target access network device.

[0433] S838: The target access network device sends a UE context release message to the source access network device.

[0434] Optionally, if the CU of the source access network device has a CP-UP separated architecture, the CP of the CU of the source access network device can receive the UE context release message from the target access network device, and the CP of the CU of the source access network device can send a bearer context release command to the UP of the CU of the source access network device.

[0435] S839 and S840 describe the UE context release procedure for the F1 interface between the source access network device and the source parent node.

[0436] S839: The source access network device sends a UE context release command message to the source parent node.

[0437] S840: The source parent node sends a UE context release Complete message to the source access network device.

[0438] S841: Release the BAP routing configuration on the path between the source access network device and the third node.

[0439] The nodes on the path between the source access network device and the third node include the source access network device itself, as well as other nodes between the source access network device and the third node, such as the source parent node. Specifically, the source access network device in this step can be the DU portion of the source access network device.

[0440] Optionally, S841 may specifically include: the source access network device sending an F1AP message to the nodes on the path respectively, for releasing the BAP layer configuration related to the third node, the first node, or the second node; after receiving the F1AP message, the node on the path releases the corresponding BAP layer configuration of the node.

[0441] Optional, Figure 7 and Figure 8 In this context, actions performed by access network devices (such as source access network devices or target access network devices) can be executed by the CU of the access network device or the CP of the CU.

[0442] Optional, Figure 8 The first node in can be Figure 7 The child node in the middle, the second node can be Figure 7 The parent node in the S804 to S807 can be cross-referenced with the contents of S701 to S703, S809 can be cross-referenced with S704, S833 can be cross-referenced with S705, and S834 to S836 can be cross-referenced with S706 to S708. The content of the second RRC reconfiguration message in S810 to S811 can be cross-referenced with... Figure 7 The content of the third message in each is referenced.

[0443] Optional, Figure 8 The second node in can be Figure 7 child nodes in Figure 8 The third node in can be Figure 7 The parent node in the S804, S810 to S812 content can be cross-referenced with the content of S701 to S703, S814 can be cross-referenced with S704, S828 can be cross-referenced with S705, and S829 to S831 can be cross-referenced with S706 to S708. The content of the third RRC reconfiguration message in S815 to S816 can be cross-referenced with... Figure 7 The content of the third message in each is referenced.

[0444] Optional, Figure 8 In this context, the methods of the first node, the second node, and the third node can all be implemented independently; for example, the method of the third node can be implemented independently.

[0445] Optional, Figure 8 In this context, the methods for the first node, the second node, and the third node can be implemented in combination. For example, the combination may include the first node and the second node, the second node and the third node, the first node and the third node, or the first node, the second node, and the third node.

[0446] Optional, Figure 8The steps in the process can be combined in different ways, as illustrated below with examples of various designs:

[0447] In one possible design, Figure 8 The method may only include S804, S805, and S806, whereby the first node receives the first RRC reconfiguration information from the target access network device through the second node, and the first RRC reconfiguration message indicates that random access is not required. Optionally, the first node's C-RNTI can remain unchanged before and after the handover. Refer to S804, S805, and S806 for details. Optionally, it may also include... Figure 8 One or more other steps in the process.

[0448] By indicating the absence of random access via the first RRC reconfiguration message, node handover time can be reduced, handover latency lowered, signaling overhead saved, and frequent conflicts caused by resource constraints or excessive waiting time for random access resources by a large number of nodes initiating random access can be avoided. Furthermore, by keeping the C-RNTI unchanged, a large amount of reconfiguration work can be avoided, and the power consumption of the first node can be saved.

[0449] In another possible design, Figure 8 The method may include only S805, S806, S810, and S811. S810 can occur after S805 and / or S806. For details, please refer to [reference needed]. Figure 8 The content of the message. Optionally, the first RRC reconfiguration message and / or the second RRC reconfiguration message may indicate random access or no-random access, which is not limited in this embodiment. Optionally, it may also include Figure 8 One or more other steps in the process.

[0450] By enabling S810 to occur after S805 and / or S806, it ensures that the child node receives the RRC reconfiguration message before sending the RRC reconfiguration message to the parent node, thus avoiding the inability to provide services to the child node due to the parent node switching prematurely.

[0451] In yet another possible design, Figure 8 The method may only include S803, whereby the source access network device sends a handover request message to the target access network device, including the C-RNTI of one or more nodes, the cell identifier of the accessed cell, and / or hierarchical information in the network topology. Optionally, the target access network device determines the timer duration based on the hierarchical information and sends it to the one or more nodes in the RRC reconfiguration message. For details, please refer to [reference needed]. Figure 8 The content. Optionally, it may also include... Figure 8 One or more other steps in the process.

[0452] Depend onFigure 8 It can be seen that during group switching, at the beginning of the switching phase, the switch is first sent to the furthest node in the group (e.g., the node at the farthest end of the group). Figure 7 The first node sends an RRC reconfiguration message, then sends the RRC reconfiguration messages of the next higher-level node step by step, and finally sends the RRC reconfiguration message to the migrating IAB node. During the handover completion phase, the first node to send the RRC reconfiguration completion message to the target access network device's IAB node is the one that sends the message, then sends the RRC reconfiguration completion message of the next lower-level node step by step, and finally sends the RRC reconfiguration completion message of the furthest node. Therefore, it can be understood that in group handover, the node with the higher hop count of the radio backhaul link with the migrating IAB node takes longer from the start of the handover to its completion.

[0453] If the timer duration is set improperly, nodes in a group handover may fail due to timer timeout. Upon determining its handover failure, the node will initiate an RRC reconstruction, which introduces latency and unnecessary signaling overhead. Furthermore, if the parent node's handover is not yet complete after the child node initiates an RRC reconstruction, the parent node cannot provide services to the child node, potentially causing the child node's RRC reconstruction to fail as well. The child node will then enter an idle state and re-enter the network, which involves significant latency, severely impacting user experience.

[0454] By sending hierarchy information from the source access network device to the target access network device, the target access network device can reasonably determine the timer duration based on the node's hierarchy. For example, nodes with a higher hop count on the radio backhaul link with the migrating IAB node require a longer timer duration, while nodes with a lower hop count require a shorter timer duration. Avoiding the consequences of improper timer duration settings can reduce handover latency and signaling overhead.

[0455] Optional, such as Figure 8 As shown, during group handover, each node can receive its own reconfiguration message. Considering that some information in the reconfiguration message of each node may be the same, this application provides a scheme in which the target access network device can send this same information by broadcasting.

[0456] For example, the target access network device broadcasts a group reconfiguration message, which includes the common configuration of the primary serving cell, an indication of no random access, and / or timer duration information, etc.

[0457] Optionally, this group reconfiguration message can be called a group switching command.

[0458] Optionally, the duration information of the timer can indicate the duration of the base timer in S804, and then the target access network device can send a message to each node in the group, which includes a scaling factor. The nodes in the group obtain the duration of the timer based on the duration of the base timer and the scaling factor.

[0459] Optionally, the target access network device can also send messages individually to each node in the group, which include information that differs between each node, such as the PDCP layer configuration of each node (e.g., security-related configuration).

[0460] By broadcasting the same information to each node, air interface signaling overhead can be saved. Especially in IAB systems, this broadcasting method avoids the overhead of sending signaling to multiple nodes in the group individually.

[0461] Figure 1 and Figure 9 The method described uses a relay system as an example. It should be noted that the method in this embodiment is also applicable to single-air interface scenarios where the terminal directly accesses the access network device, for example... Figure 9 The scenario where terminal 130 directly connects to access network device 150 for communication.

[0462] Figure 2 This is another communication method provided in the embodiments of this application, which can be applied to scenarios where the terminal directly accesses the access network device. The following describes a method in conjunction with... Figure 1 This will be explained. Access network device 150 can adopt... Figure 2 The CU-DU separated architecture is shown.

[0463] Optionally, terminal 130 can be switched from access network device 150 to another access network device. Figure 7 (Not illustrated in the text), the following text refers to access network device 150 as the source access network device and the other access network device as the target access network device. The target access network device can be adopted... Figure 7 The CU-DU separation architecture shown can be referred to as the target CU and the target DU.

[0464] S901: The target CU sends the first message to the source access network device.

[0465] Optionally, the source access network device can adopt a CU-DU separated architecture, where the CU of the source access network device can be called the source CU, and the DU of the source access network device can be called the source DU. S901 may include: the target CU sending a first message to the source CU.

[0466] S902: The source access network device sends the first message to the terminal.

[0467] Optionally, if the source access network device can adopt a CU-DU separation architecture, S902 may include: the source CU sending a first message to the source DU, and the source DU sending a first message to the terminal.

[0468] S903: Terminal start timer.

[0469] S904: The terminal sends a second message to the target DU.

[0470] S905: Target DU sends a second message to target CU.

[0471] The first and second messages in S901 to S905 can be referenced. Figure 9 The content of the first and second messages.

[0472] S906: The target CU sends the first instruction information to the target DU.

[0473] S907: The target DU sends a second instruction message to the terminal.

[0474] The first and second indication information in S906 to S907 can be referenced. Figure 7 The content of the first and second instruction information.

[0475] S908: Terminal stop timer.

[0476] Figure 9 The target DU in the middle can be executed Figure 7 The actions of the parent node in the middle, Figure 9 The target CU in the middle can execute Figure 7 The actions of the access network equipment Figure 9 The terminal can execute Figure 7 The actions of child nodes in the process. Figure 10 to Figure 13 Other content can be found at [reference]. Figure 10 to Figure 13 This will not be elaborated upon here.

[0477] The following is combined with Figure 7 to Figure 9 The apparatus provided in the embodiments of this application is described below. Figure 10 The device in it can complete Figure 10 The contents of the apparatus can be cross-referenced with the contents of the method.

[0478] Figure 10 This is a schematic diagram of the structure of a terminal provided in an embodiment of this application. This terminal can implement the functions of the terminal in the above method embodiments. For ease of explanation, Figure 10 The main components of the terminal are shown, such as Figure 11 As shown:

[0479] The terminal includes at least one processor 611, at least one transceiver 612, and at least one memory 613. The processor 611, memory 613, and transceiver 612 are connected together. Optionally, the terminal may also include an output device 614, an input device 615, and one or more antennas 616. The antennas 616 are connected to the transceiver 612, and the output device 614 and input device 615 are connected to the processor 611.

[0480] The processor 611 is mainly used to process communication protocols and communication data, control the entire terminal, execute software programs, and process the data of the software programs.

[0481] As an optional implementation, the terminal device may include a baseband processor and a central processing unit (CPU). The baseband processor is mainly used for processing communication protocols and communication data. The CPU is mainly used for controlling the entire terminal device, executing software programs, and processing data from the software programs.

[0482] Figure 11 The processor in the device can integrate the functions of a baseband processor and a central processing unit (CPU). Those skilled in the art will understand that the baseband processor and CPU can also be independent processors interconnected via technologies such as buses. It will also be understood that a terminal device can include multiple baseband processors to adapt to different network standards, and multiple CPUs to enhance its processing capabilities. The various components of the terminal device can be connected via various buses. The baseband processor can also be described as a baseband processing circuit or a baseband processing chip. Similarly, the CPU can be described as a central processing circuit or a central processing chip. The function of processing communication protocols and communication data can be built into the processor or stored in memory as a software program, with the processor executing the software program to implement the baseband processing function.

[0483] The memory 613 is primarily used to store software programs and data. The memory 613 can exist independently, connected to the processor 611. Optionally, the memory 613 can be integrated with the processor 611, for example, integrated within a single chip, i.e., on-chip memory, or the memory 613 can be a separate storage element; this embodiment does not limit this. The memory 613 can store program code that executes the technical solutions of this embodiment, and its execution is controlled by the processor 611. The various types of computer program code being executed can also be considered as drivers for the processor 611.

[0484] Transceiver 612 can be used for converting baseband signals to radio frequency (RF) signals and processing RF signals. Transceiver 612 can be connected to antenna 616. Transceiver 612 includes a transmitter (Tx) and a receiver (Rx). Specifically, one or more antennas 616 can receive RF signals. The receiver Rx of transceiver 612 receives the RF signals from the antennas, converts the RF signals into digital baseband signals or digital intermediate frequency (IF) signals, and provides the digital baseband signals or IF signals to processor 611 so that processor 611 can perform further processing on the digital baseband signals or IF signals, such as demodulation and decoding. Furthermore, the transmitter Tx in transceiver 612 receives the modulated digital baseband signals or IF signals from processor 611, converts the modulated digital baseband signals or IF signals into RF signals, and transmits the RF signals through one or more antennas 616. Specifically, the receiver Rx can selectively perform one or more stages of downmixing and analog-to-digital conversion on the radio frequency signal to obtain a digital baseband signal or a digital intermediate frequency (IF) signal. The order of the downmixing and IF conversion is adjustable. The transmitter Tx can selectively perform one or more stages of upmixing and digital-to-analog conversion on the modulated digital baseband signal or digital IF signal to obtain a radio frequency signal. The order of the upmixing and IF conversion is also adjustable. The digital baseband signal and the digital IF signal can be collectively referred to as digital signals. Optionally, the transmitter Tx and the receiver Rx can be implemented using different physical structures / circuits, or they can be implemented using the same physical structure / circuit; that is, the transmitter Tx and the receiver Rx can be integrated.

[0485] A transceiver can also be called a transceiver unit, transceiver, or transceiver device. Optionally, the device in the transceiver unit that performs the receiving function can be considered the receiving unit, and the device in the transceiver unit that performs the transmitting function can be considered the transmitting unit. That is, the transceiver unit includes a receiving unit and a transmitting unit. The receiving unit can also be called a receiver, input port, or receiving circuit, and the transmitting unit can be called a transmitter, transmitter, or transmitting circuit. Alternatively, the combination of Tx, Rx, and antenna can be considered as a transceiver.

[0486] Output device 614 displays information in various ways. For example, output device 614 can be a liquid crystal display (LCD), a light-emitting diode (LED) display device, a cathode ray tube (CRT) display device, or a projector. Input device 615 can accept user input in various ways. For example, input device 615 can be a mouse, keyboard, touch screen device, or sensing device.

[0487] Figure 1 This is a schematic diagram of the structure of an access network device provided in an embodiment of this application. It can be an exemplary schematic diagram of the structure of an access network device, which may adopt a CU-DU separated architecture. Figure 2 As shown, this base station can be applied to, for example... Figure 3 or Figure 12 or Figure 12 The system shown implements the functions of the access network devices (source access network devices and / or target access network devices) in the above method embodiments.

[0488] The access network equipment may include one or more DU 1101 and one or more CU 1102. The DU 1101 may include at least one antenna 11011, at least one radio frequency unit 11012, at least one processor 11013, and at least one memory 11014. The DU 1101 is mainly used for transmitting and receiving radio frequency signals, converting radio frequency signals to baseband signals, and performing some baseband processing. The CU 1102 may include at least one processor 11022 and at least one memory 11021. The CU 1102 and DU 1101 can communicate via an interface, wherein the control plane interface can be F1-C and the user plane interface can be F1-U.

[0489] The CU 1102 is mainly used for baseband processing and base station control. The DU 1101 and CU 1102 can be physically installed together or separately, i.e., a distributed base station. The CU 1102 is the control center of the base station, also known as a processing unit, and is mainly used to complete baseband processing functions. For example, the CU 1102 can be used to control the base station to execute the network device operation procedures described in the above method embodiments.

[0490] Specifically, the baseband processing on CU and DU can be divided according to the protocol layer of the wireless network, as detailed above.

[0491] In one example, the CU 1102 can be composed of one or more single boards. Multiple single boards can collectively support a single access indication wireless access network (such as a 5G network), or they can each support wireless access networks with different access standards (such as LTE, 5G, or other access networks). The memory 11021 and processor 11022 can serve one or more single boards. That is, each single board can have its own memory and processor, or multiple single boards can share the same memory and processor. Furthermore, each single board can also have necessary circuitry. Similarly, the DU 1101 can be composed of one or more single boards. Multiple single boards can collectively support a single access indication wireless access network (such as a 5G network), or they can each support wireless access networks with different access standards (such as LTE, 5G, or other access networks). The memory 11014 and processor 11013 can serve one or more single boards. That is, each single board can have its own memory and processor, or multiple single boards can share the same memory and processor. Furthermore, each single board can also have necessary circuitry.

[0492] Optionally, CU 1102 can transmit with the child nodes of the access network device through DU 1101. CU 1102 can be connected to other access network devices through an interface. CU 1102 can receive data and / or messages from other access network devices (e.g., CUs of other access network devices) through this interface, or CU 1102 can send data and / or messages to other access network devices through this interface.

[0493] Figure 12 This is a schematic diagram of a communication device provided in an embodiment of this application. The communication device can be a relay node, capable of performing the functions of a relay node (e.g., an IAB node) in the above method embodiments; or the communication device can be an access network device, capable of performing the functions of a source access network device or a target access network device in the above method embodiments. For ease of explanation, Figure 10 The main components of the communication device are shown, such as Figure 13 As shown:

[0494] The communication device includes at least one processor 711, at least one memory 712, at least one transceiver 713, at least one network interface 714, and one or more antennas 715. The processor 711, memory 712, transceiver 713, and network interface 714 are connected, for example, via a bus. In this embodiment, the connection may include various interfaces, transmission lines, or buses, etc., and this embodiment is not limited thereto. The antenna 715 is connected to the transceiver 713. The network interface 714 enables the communication device to connect to other network devices via a communication link.

[0495] The transceiver 713, memory 712, and antenna 716 can be referenced. Figure 10 The relevant descriptions in the document aim to achieve similar functionality.

[0496] Figure 10 This is a schematic diagram of a communication device provided in an embodiment of this application. The communication device can execute the methods described in the above method embodiments, and reference can be made to the description of the above method embodiments. The communication device can be used in communication equipment, circuits, hardware components, or chips. For example, the communication device can be a terminal, a chip in a terminal, a host node (including a source host node or a target host node), or a chip in a host node (including a source host node or a target host node).

[0497] The communication device 1300 includes a processing unit 1301 and a communication unit 1302. Optionally, the communication device 1300 also includes a storage unit 1303.

[0498] The processing unit 1301 can be a device with processing capabilities, and may include one or more processors. The processor can be a general-purpose processor or a dedicated processor. The processor can be a baseband processor or a central processing unit (CPU). The baseband processor can be used to process communication protocols and communication data, while the CPU can be used to control the device (e.g., a host node, terminal, or chip), execute software programs, and process data from the software programs.

[0499] The communication unit 1302 may be a device that has signal input (receive) or output (transmit) for transmitting signals with other network devices or other devices in the device.

[0500] Storage unit 1303 may be a device with storage function, and may include one or more memories.

[0501] Optionally, the processing unit 1301, the communication unit 1302, and the storage unit 1303 are connected via a communication bus.

[0502] Optionally, the storage unit 1303 can exist independently and be connected to the processing unit 1301 via a communication bus. Alternatively, the storage unit 1303 can be integrated with the processing unit 1301.

[0503] Optionally, the communication device 1300 may be a chip in the terminal or host node of this application embodiment. The communication unit 1302 may be an input or output interface, pin, or circuit, etc. The storage unit 1303 may be a register, cache, or RAM, etc., and the storage unit 1303 may be integrated with the processing unit 1301; the storage unit 1303 may be a ROM or other type of static storage device capable of storing static information and instructions, and the storage unit 1303 may be independent of the processing unit 1301. Optionally, with the development of wireless communication technology, a transceiver may be integrated into the communication device 1300, for example, the communication unit 1302 may integrate a transceiver. Figure 10 The transceiver 612 shown is shown.

[0504] In one possible design, the processing unit 1301 may include instructions that can be executed on the processor, causing the communication device 1300 to perform the methods of the terminal or host node described in the above embodiments.

[0505] In another possible design, the storage unit 1303 stores instructions that can be executed on the processing unit 1301, causing the communication device 1300 to perform the methods of the terminal or host node described in the above embodiments. Optionally, the storage unit 1303 may also store data. Optionally, the processing unit 1301 may also store instructions and / or data.

[0506] The communication device 1300 can be a terminal as described in the embodiments of this application. A schematic diagram of the terminal can be shown below. Figure 10 As shown. Optionally, the communication unit 1302 of device 1300 may include the antenna and transceiver of the terminal, for example... ​ The communication unit 1302 may also include an antenna and a transceiver. Optionally, the communication unit 1302 may further include output and input devices, such as... ​ Output and input devices in the system.

[0507] When the communication device 1300 can be a terminal or a terminal chip in the embodiments of this application, the communication device 1300 can implement the functions implemented by the terminal in the above method embodiments.

[0508] When the communication device 1300 can be a relay node or a chip of a relay node in the embodiments of this application, the communication device 1300 can implement the functions implemented by the relay node in the above method embodiments.

[0509] When the communication device 1300 can be a chip of the access network device (e.g., source access network device or target access network device) in the embodiments of this application, the communication device 1300 can implement the function of the host node in the above method embodiments.

[0510] The above describes the method flowchart of an embodiment of this application. It should be understood that a terminal may have functional units (means) corresponding to the terminal's methods or steps; a relay node may have functional units corresponding to the relay node's methods or steps; a source host node (e.g., CU and / or DU) may have functional units corresponding to the source host node's methods (e.g., CU and / or DU) or steps; a target host node (e.g., CU and / or DU) may have functional units corresponding to the target host node's methods (e.g., CU and / or DU); the CU of the source host node may have functional units corresponding to the source host node's CU's methods or steps; and other nodes in the relay system may have functional units corresponding to those other nodes. One or more of the above modules or units can be implemented in software, hardware, or a combination of both. When any of the above modules or units is implemented in software, the software exists as computer program instructions and is stored in memory. A processor can execute the program instructions to implement the above method flow.

[0511] The processor in this application may include, but is not limited to, at least one of the following: a central processing unit (CPU), a microprocessor, a digital signal processor (DSP), a microcontroller unit (MCU), or an artificial intelligence processor, etc., and other computing devices that run software. Each computing device may include one or more cores for executing software instructions to perform calculations or processing. The processor may be a standalone semiconductor chip or integrated with other circuits into a single semiconductor chip. For example, it may be integrated with other circuits (such as encoding / decoding circuits, hardware acceleration circuits, or various bus and interface circuits) to form a SoC (system on a chip), or it may be integrated as a built-in processor within an application-specific integrated circuit (ASIC). The ASIC with the integrated processor may be packaged separately or together with other circuits. In addition to the cores for executing software instructions to perform calculations or processing, the processor may further include necessary hardware accelerators, such as field-programmable gate arrays (FPGAs), programmable logic devices (PLDs), or logic circuits that implement dedicated logic operations.

[0512] The memory in the embodiments of this application may include at least one of the following types: read-only memory (ROM) or other types of static storage devices capable of storing static information and instructions; random access memory (RAM) or other types of dynamic storage devices capable of storing information and instructions; or electrically erasable programmable-only memory (EEPROM). In some scenarios, the memory may also be a compact disc read-only memory (CD-ROM) or other optical disc storage, optical disc storage (including compressed optical discs, laser discs, optical discs, digital universal optical discs, Blu-ray discs, etc.), magnetic disk storage media, or other magnetic storage devices, or any other medium capable of carrying or storing desired program code in the form of instructions or data structures and accessible by a computer, but is not limited thereto.

[0513] In addition to the data bus, this bus may also include a power bus, a control bus, and a status signal bus. However, for clarity, all buses are labeled "bus" in the diagram.

[0514] In implementation, each step of the above method can be completed by integrated logic circuits in the processor's hardware or by instructions in software. The steps of the method disclosed in the embodiments of this application can be directly implemented by a hardware processor, or by a combination of hardware and software modules in the processor. The software modules can reside in random access memory, flash memory, read-only memory, programmable read-only memory, electrically erasable programmable memory, registers, or other mature storage media in the art. This storage medium is located in memory, and the processor reads information from the memory and, in conjunction with its hardware, completes the steps of the above method. To avoid repetition, detailed descriptions are omitted here.

[0515] According to the method provided in the embodiments of this application, the embodiments of this application also provide a system, which includes the aforementioned apparatus and one or more network devices.

[0516] It should also be understood that the first, second, third, fourth and various numerical designations mentioned herein are merely distinctions for ease of description and are not intended to limit the scope of the embodiments of this application. These numerical designations can be replaced by other numerical designations.

[0517] It should be understood that the term "and / or" in this article is merely a description of the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent: A existing alone, A and B existing simultaneously, or B existing alone. Additionally, the character " / " in this article generally indicates that the preceding and following related objects have an "or" relationship.

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

[0519] Those skilled in the art will recognize that the various illustrative logical blocks and steps described in conjunction with the embodiments disclosed herein can be implemented in electronic hardware, or a combination of computer software and electronic hardware. Whether these functions are implemented in hardware or software depends on the specific application and design constraints of the technical solution. Those skilled in the art can use different methods to implement the described functions for each specific application, but such implementations should not be considered beyond the scope of this application.

[0520] In the several embodiments provided in this application, it should be understood that the disclosed systems, apparatuses, and methods can be implemented in other ways. For example, the apparatus embodiments described above are merely illustrative; for instance, the division of units is only a logical functional division, and in actual implementation, there may be other division methods. For example, multiple units or components may be combined or integrated into another system, or some features may be ignored or not executed. Furthermore, the coupling or direct coupling or communication connection shown or discussed may be through some interfaces; the indirect coupling or communication connection between apparatuses or units may be electrical, mechanical, or other forms.

[0521] In the above embodiments, implementation can be achieved entirely or partially through software, hardware, firmware, or any combination thereof. When implemented using software, it can be implemented entirely or partially as a computer program product. The computer program product includes one or more computer instructions. When the computer program instructions are loaded and executed on a computer, all or part of the processes or functions described in the embodiments of this application are generated. The computer can be a general-purpose computer, a special-purpose computer, a computer network, or other programmable device. The computer instructions can be stored in a computer-readable storage medium or transmitted from one computer-readable storage medium to another. For example, the computer instructions can be transmitted from one website, computer, server, or data center to another website, computer, server, or data center via wired (e.g., coaxial cable, fiber optic, digital subscriber line (DSL)) or wireless (e.g., infrared, wireless, microwave, etc.) means. The computer-readable storage medium can be any available medium that a computer can access or a data storage device such as a server or data center that integrates one or more available media. The available media can be magnetic media (e.g., floppy disks, hard disks, magnetic tapes), optical media (e.g., digital versatile disks (DVDs)), or semiconductor media (e.g., solid-state drives).

[0522] The above description is merely a specific embodiment of this application, but the scope of protection of this application is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in this application should be included within the scope of protection of this application. Therefore, the scope of protection of this application should be determined by the scope of the claims.

Claims

1. A communication method for accessing an integrated IAB (Integrated Access and Backhaul) system, characterized in that, The method includes: The child node receives a first Radio Resource Control (RRC) reconfiguration message from the access network device through the parent node. The first RRC reconfiguration message includes an indication of non-random access. The child node starts a timer; The child node sends a first RRC reconfiguration complete message to the access network device through the parent node; The child node receives a first indication from the parent node, the first indication indicating to stop the timer; the first indication is a MAC CE carrying a contention resolution identifier. The child node stops the timer.

2. The method according to claim 1, characterized in that, The first RRC reconfiguration message does not include the cell radio network temporary identifier of the child node; or The first RRC reconfiguration message includes second indication information, which indicates that the temporary identifier of the cell radio network of the sub-node remains unchanged; or The first RRC reconfiguration message includes the temporary identifier of the cell radio network used by the child node before receiving the first RRC reconfiguration message.

3. The method according to claim 1, characterized in that, Also includes: The parent node receives third indication information from the access network device; In response to the third indication information, the parent node sends the first indication information to the child node.

4. The method according to claim 3, characterized in that, The third indication information includes the identifier of the child node.

5. The method according to claim 1, characterized in that, The access network device is the target access network device for the child node and the parent node during the group handover process.

6. The method according to claim 5, characterized in that, The method further includes: After the parent node receives the first RRC reconfiguration message from the access network device or sends it to the child node, the parent node receives the second RRC reconfiguration message from the access network device, and the parent node starts a timer.

7. The method according to claim 6, characterized in that, The method further includes: After the parent node receives the first RRC reconfiguration message from the access network device or sends it to the child node, the parent node sends a fourth indication message to the source access network device to trigger the source access network device to send the second RRC reconfiguration message to the parent node. The source access network device is the source access network device of the child node and the parent node during the group handover process.

8. The method according to claim 1, characterized in that, The child node is a terminal or an IAB node, and the parent node is an IAB node.

9. The method according to claim 1, characterized in that, The access network device is the target access network device for the sub-node during the group handover process.

10. A communication method for accessing an integrated IAB (Integrated Access and Backhaul) system, characterized in that, The method includes: The parent node receives a first RRC reconfiguration message from the access network device, the first RRC reconfiguration message including an indication of no random access; The parent node sends the first RRC reconfiguration message to the child node to trigger the child node to start a timer; The parent node receives the first RRC reconfiguration complete message from the child node; The parent node sends the first RRC reconfiguration complete message to the access network device; The parent node sends a first indication message to the child node, the first indication message indicating that the timer should be stopped; the first indication message is a MAC CE carrying a contention resolution identifier.

11. The method according to claim 10, characterized in that, The method further includes: The parent node receives the second indication information from the access network device; In response to the second indication information, the parent node sends the first indication information to the child node.

12. The method according to claim 11, characterized in that, The second indication information includes the identifier of the child node.

13. The method according to any one of claims 10-12, characterized in that, The first RRC reconfiguration message does not include the cell radio network temporary identifier of the child node; or The first RRC reconfiguration message includes third indication information, which indicates that the temporary identifier of the cell radio network of the sub-node remains unchanged; or The first RRC reconfiguration message includes the temporary identifier of the child node's cell radio network before the parent node sends the first RRC reconfiguration message to the child node.

14. The method according to claim 10, characterized in that, The access network device is the target access network device for the sub-node during the group handover process.

15. The method according to claim 14, characterized in that, The method further includes: After the parent node receives the first RRC reconfiguration message from the access network device or sends it to the child node, the parent node receives the second RRC reconfiguration message from the access network device, and the parent node starts a timer.

16. The method according to claim 15, characterized in that, The method further includes: After the parent node receives the first RRC reconfiguration message from the access network device or sends it to the child node, the parent node sends a fourth indication message to the source access network device to trigger the source access network device to send the second RRC reconfiguration message to the parent node. The source access network device is the source access network device of the child node and the parent node during the group handover process.

17. The method according to claim 10, characterized in that, The child node is a terminal or an IAB node, and the parent node is an IAB node.

18. A communication method for accessing an integrated IAB (Integrated Access and Backhaul) system, characterized in that, The method includes: The access network device sends a first Radio Resource Control (RRC) reconfiguration message to the child node through the parent node to trigger the child node to start a timer. The first RRC reconfiguration message includes an indication of no random access. The access network device receives the first RRC reconfiguration complete message from the child node through the parent node; The access network device sends a second indication message to the parent node to trigger the parent node to send a first indication message to the child node. The first indication message indicates that the timer should be stopped. The first indication message is a MAC CE carrying a contention resolution identifier.

19. The method according to claim 18, characterized in that, The second indication information includes the identifier of the child node.

20. The method according to claim 18, characterized in that, The first RRC reconfiguration message does not include the cell radio network temporary identifier of the child node; or The first RRC reconfiguration message includes third indication information, which indicates that the temporary identifier of the cell radio network of the sub-node remains unchanged; or The first RRC reconfiguration message includes the temporary identifier of the child network cell before the access network device sends the first RRC reconfiguration completion message to the child node through the parent node.

21. The method according to claim 20, characterized in that, The method further includes: The target access network device receives a handover request message from the source access network device. The handover request message includes one or more of the following: the temporary identifier of the cell radio network of the child node before the handover, the identifier of the cell accessed by the child node before the handover, and the hierarchical information of the child node in the network topology. The source access network device is the source access network device of the child node and the parent node during the group handover process.

22. The method according to claim 21, characterized in that, The method further includes: The target access network device determines the duration of the timer based on the hierarchical information; The first RRC reconfiguration message includes information about the duration of the timer.

23. A communication device, characterized in that, It includes at least one processor, which is configured to invoke a program stored in memory to perform the method of claim 1 or 2.

24. A communication device, characterized in that, It includes at least one processor, which is configured to invoke a program stored in memory to perform the method according to any one of claims 10 to 17.

25. A communication device, characterized in that, It includes at least one processor, said at least one processor being configured to invoke a program stored in memory to perform the method according to any one of claims 18 to 22.

26. A computer-readable storage medium, characterized in that, The device stores a program or instructions for implementing the method described in any one of claims 1 or 2, 10 to 17, or 18 to 22.

27. A communication system, characterized in that, The communication system includes one or more means for performing the method of claim 1 or 2, means for performing the method of any one of claims 10 to 17, and means for performing the method of any one of claims 18 to 22.

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