Method and communication device for handover between systems

Abstract

The present application provides an inter-system handover method and a communication device, which may be applied to an inter-system handover scenario. During the handover process, a source access network device may provide identification information of a terminal device to a target access network device. When determining to add the source access network device as a secondary access network device, the target access network device may send a request message for adding a secondary access network device, carrying the identification information of the terminal device, to the source access network device. When determining to serve as the secondary access network device of the terminal device, the source access network device does not need to forward data corresponding to bearers terminated at the source access network device, so that delays caused by data forwarding can be avoided.

Description

[Technical field]

[0001] This application claims priority to Chinese Patent Application No. 202010093924.6, entitled "INTER-SYSTEM HANDOVER METHOD AND COMMUNICATION APPARATUS," filed with the China State Intellectual Property Office on February 14, 2020, the entire contents of which are incorporated herein by reference.

[0002] The present application relates to the field of communications, and more particularly to an inter-system handover method and communication device. [Background technology]

[0003] In a wireless network, one terminal device may communicate with multiple access network devices. This is multi-radio dual connectivity (MR-DC). There are several types of dual connectivity, such as evolved universal terrestrial radio access (E-UTRA)-new radio dual connectivity (E-UTRA-NR dual connectivity (EN-DC)).

[0004] An inter-system handover may be performed on a terminal. For example, a terminal is handed over from connecting to a 5th generation (5G) core network (5GC) by accessing a base station in a new radio access technology (NR) network to connecting to a 4th generation (4G) core network by accessing a base station in a long term evolution (LTE) network. In an inter-system handover scenario, some data packets sent by a source core network to a source access network device are forwarded to a target access network device in a target system. In one solution, the source access network device first forwards the data packets to a source core network in the source system, which then forwards the data packets to a target core network in the target system, which then forwards the data packets to the target access network device. In another solution, the source access network device directly forwards the data packets to the target access network device. After the data packets are forwarded to the target access network device, the target access network device sends the data packets to the terminal device.

[0005] In the current technology, during inter-system handover, the target access network device may configure MR-DC for the terminal device. In this scenario, how to forward data becomes a technical problem that needs to be urgently solved. Summary of the Invention [Problem to be solved by the invention]

[0006] The present application provides an inter-system handover method and communication apparatus in a scenario where a target secondary access network device is a source access network device, so that data corresponding to a bearer terminated in the source access network device is not forwarded, and delays caused by data forwarding can then be avoided. [Means for solving the problem]

[0007] According to a first aspect, an inter-system handover method is provided. The method includes: a first access network device receives a handover request message from a first core network device, where the handover request message includes an identification information of a terminal device, and the first access network device provides the terminal device with a service for connecting to a first core network, and the first core network device belongs to the first core network. The first access network device determines that a secondary access network device to be added for the terminal device is a second access network device, where the second access network device provides the terminal device with a service for connecting to the second core network. The first access network device sends a request message for adding a secondary access network device to the second access network device, where the request message for adding a secondary access network device includes the identification information of the terminal device.

[0008] Optionally, the identity of the terminal device is a cell radio network temporary identifier (C-RNTI) of the second access network device and allocated to the terminal device in a serving cell in which the terminal device is located, or the identity of the terminal device is an identity of the terminal device on an interface between the second access network device and a second core network device, where the second core network device belongs to the second core network.

[0009] The identification information of the terminal device on the interface between the second access network device and the second core network device may be allocated by the second access network device or may be allocated by the second core network device.

[0010] According to the method provided in the present application, the second access network device may provide the first access network device with the identification information of the terminal device on which the handover procedure will be performed during the handover process. When determining that the secondary access network device and the source access network device (i.e., the second access network device) are the same access network device, the first access network device provides the identification information of the terminal device to the source access network device, so that the source access network device does not forward data corresponding to the bearer terminated at the source access network device, and then the data transmission delay can be shortened.

[0011] Referring to the first aspect, in some implementations of the first aspect, the handover request message may further include identification information of the second access network device.

[0012] Optionally, the first access network device may determine, based on the identification information of the second access network device, that the secondary access network device to be added for the terminal device is the second access network device.

[0013] Optionally, the identification information of the second access network device is an identification information used when the second access network device provides a service to the terminal device for connecting to the first core network.

[0014] For example, the identity of the second access network device may be: a global base station identifier, which is used when the second access network device provides a service for connecting to the first core network to the terminal device and which belongs to the second access network device; a frequency channel number, which is used when the second access network device provides a service for connecting to the first core network to the terminal device and which belongs to a cell managed by the second access network device; a physical cell identifier, which is used when the second access network device provides a service for connecting to the first core network to the terminal device and which belongs to a cell managed by the second access network device; The PCI may include one or more of: a PCI that is used when the second access network device provides services to the terminal device for connecting to the first core network, and that is of the second access network device and of the serving cell in which the terminal device is located; a frequency channel number that is used when the second access network device provides services to the terminal device for connecting to the first core network, and that is of the second access network device and of the serving cell in which the terminal device is located; and a cell global identifier (CGI) that is used when the second access network device provides services to the terminal device for connecting to the first core network, and that is of the second access network device and of the serving cell in which the terminal device is located.

[0015] Optionally, the identification information of the second access network device is an identification information used when the second access network device provides a service to a terminal device for connecting to a second core network.

[0016] For example, the identity of the second access network device may be: a global base station identifier, which is used when the second access network device provides a service for connecting to the second core network to a terminal device and belongs to the second access network device; a frequency channel number, which is used when the second access network device provides a service for connecting to the second core network to a terminal device and belongs to a cell managed by the second access network device; a PCI, which is used when the second access network device provides a service for connecting to the second core network to a terminal device and belongs to a cell managed by the second access network device; The communication interface may include one or more of: a PCI that is used when the second access network device provides services to the terminal device and that is of the second access network device and that is of the serving cell in which the terminal device is located; a frequency channel number that is used when the second access network device provides services to the terminal device for connecting to the second core network and that is of the second access network device and that is of the serving cell in which the terminal device is located; and a CGI that is used when the second access network device provides services to the terminal device for connecting to the second core network and that is of the second access network device and that is of the serving cell in which the terminal device is located.

[0017] For example, the identification information used when the second access network device provides services to a terminal device for connecting to a first core network may be the same as or different from the identification information used when the second access network device provides services to a terminal device for connecting to a second core network.

[0018] Referring to the first aspect, in some implementation forms of the first aspect, before the first access network device sends a request message to add the secondary access network device to the second access network device, the method may further include the first access network device receiving a first mapping relationship from the second access network device, where the first mapping relationship is a mapping relationship between an identification information used when the second access network device provides a service for connecting to the first core network to the terminal device and an identification information used when the second access network device provides a service for connecting to the second core network to the terminal device. The first access network device determining that the secondary access network device to be added for the terminal device is the second access network device includes the first access network device determining that the secondary access network device to be added for the terminal device is the second access network device based on the identification information of the second access network device and the first mapping relationship.

[0019] According to a second aspect, an inter-system handover method is provided. The method includes: a second access network device sends a first message to a second core network device, where the first message includes an identification information of a terminal device, and the second access network device provides the terminal device with a service for connecting to a second core network, and the first message is used to request the first access network device to allocate resources to the terminal device, and the first access network device provides the terminal device with a service for connecting to the first core network. The second access network device receives a request message for adding a secondary access network device from the first access network device, where the first access network device is a master access network device of the terminal device, and the request message for adding the secondary access network device includes an identification information of the terminal device, and the request message for adding the secondary access network device is used to request adding the second access network device as a secondary access network device of the terminal device. The second core network device belongs to a second core network.

[0020] Optionally, the identity of the terminal device is a C-RNTI of the second access network device and allocated to the terminal device in a serving cell in which the terminal device is located, or the identity of the terminal device is an identity of the terminal device on the interface between the second access network device and the second core network device.

[0021] The identification information of the terminal device on the interface between the second access network device and the second core network device may be allocated by the second access network device or may be allocated by the second core network device.

[0022] After the second access network device receives the request message for adding the secondary access network device, if the second access network device determines based on the identification information of the terminal device that the terminal device is a terminal device served by the secondary access network device (in other words, before handover), the second access network device may skip forwarding the data corresponding to the bearer terminated at the second access network device. In other words, it is not required that the data corresponding to the bearer terminated at the second access network device is first sent by the second access network device to the second core network, then forwarded by the second core network to the first core network, and sent by the first core network to the second access network device.

[0023] It should be understood that the bearers terminated at the second access network device may include secondary cell group (SCG) bearers terminated at the second access network device, split bearers terminated at the second access network device, and master cell group (MCG) bearers terminated at the second access network device.

[0024] Therefore, according to the method provided in the present application, the second access network device may provide the identification information of the terminal device on which the handover procedure will be performed to the first access network device in the handover process. Upon determining that the secondary access network device and the source access network device (i.e., the second access network device) are the same access network device, the first access network device provides the identification information of the terminal device to the source access network device, so that the source access network device does not forward data corresponding to the bearer terminated at the source access network device, and then the data transmission delay can be shortened.

[0025] Referring to the second aspect, in some implementations of the second aspect, the first message may further include identification information of the second access network device.

[0026] Optionally, the identification information of the second access network device is an identification information used when the second access network device provides a service to the terminal device for connecting to the first core network.

[0027] Optionally, the identification information of the second access network device is an identification information used when the second access network device provides a service to a terminal device for connecting to a second core network.

[0028] Referring to the second aspect, in some implementations of the second aspect, before the second access network device receives a request message for adding a secondary access network device from the first access network device, the method may further include:

[0029] The second access network device sends a first mapping relationship to the first access network device, where the first mapping relationship is a mapping relationship between an identification information used when the second access network device provides a service for connecting to the first core network to the terminal device and an identification information used when the second access network device provides a service for connecting to the second core network to the terminal device.

[0030] In this way, when the first access network device receives identification information used when the second access network device provides services to the terminal device for connecting to the second core network, the first access network device may determine whether the secondary access network device is the second access network device based on the first mapping relationship.

[0031] Referring to the second aspect, in some implementations of the second aspect, the method may further include the second access network device sending data corresponding to the bearer terminated at the first access network device to the first access network device.

[0032] It should be understood that the data includes data that the second access network device has received and / or will subsequently receive from the second core network. The second access network device may send the data directly to the first access network device. Alternatively, the second access network device may first send the data to the second core network, which then forwards the data to the first core network, which sends the data to the first access network device.

[0033] Referring to the second aspect, in some implementation forms of the second aspect, the method may further include the second access network device mapping a data packet, which is of a quality of service (QoS) flow and is received from the second core network, to a data radio bearer (DRB) corresponding to an Evolved Universal Terrestrial Radio Access Network radio access bearer (E-UTRAN radio access bearer, E-RAB) applicable after the handover, based on a mapping relationship between the QoS flow and the E-RAB, and sending the data packet.

[0034] Referring to the second aspect, in some implementation forms of the second aspect, the method may further include performing data communication with the terminal device by the second access network device by using the applicable key before the handover, and performing data communication with the terminal device by using the applicable key after the handover (i.e., serving as a key for the secondary access network device).

[0035] Based on this solution, data interruption in the handover process can be avoided.

[0036] According to a third aspect, an inter-system handover method is provided. The method includes: a second core network device receives a first message from a second access network device. The second core network device sends a relocation request message to a first core network device based on the first message. The first message includes an identification information of a terminal device, and the first message is used to request the first access network device to allocate resources to the terminal device. The relocation request message includes the identification information of the terminal device. The second access network device provides the terminal device with a service for connecting to a second core network, and the first access network device provides the terminal device with a service for connecting to a first core network. The second core network device belongs to the second core network, and the first core network device belongs to the first core network.

[0037] In the present application, the second core network device may send the identification information of the terminal device to the first access network device by using the first core network device.

[0038] Therefore, according to the method provided in the present application, the second access network device may provide the first access network device with the identification information of the terminal device on which the handover procedure will be performed by using the first core network device and the second core network device in the handover process. Upon determining that the secondary access network device and the source access network device (i.e., the second access network device) are the same access network device, the first access network device provides the identification information of the terminal device to the source access network device, so that the source access network device does not forward data corresponding to the bearer terminated at the source access network device, and then the data transmission delay can be shortened.

[0039] Referring to the third aspect, in some implementations of the third aspect, the relocation request message may include identification information of the second access network device.

[0040] According to a fourth aspect, an inter-system handover method is provided. The method includes: a first core network device receiving a relocation request message from a second core network device, where the relocation request message includes an identification information of a terminal device, the second access network device providing the terminal device with a service for connecting to a second core network, and the first access network device providing the terminal device with a service for connecting to a first core network. The first core network device sends a handover request message to the first access network device, where the handover request message includes an identification information of the terminal device. The second core network device belongs to the second core network, and the first core network device belongs to the first core network.

[0041] Therefore, according to the method provided in the present application, the second access network device may provide the first access network device with the identification information of the terminal device on which the handover procedure will be performed by using the first core network device and the second core network device in the handover process. Upon determining that the secondary access network device and the source access network device (i.e., the second access network device) are the same access network device, the first access network device provides the identification information of the terminal device to the source access network device, so that the source access network device does not forward data corresponding to the bearer terminated at the source access network device, and then the data transmission delay can be shortened.

[0042] Referring to the fourth aspect, in some implementations of the fourth aspect, the relocation request message may include identification information of the second access network device.

[0043] Referring to the fourth aspect, in some implementations of the fourth aspect, the handover request message may include identification information of the second access network device.

[0044] According to a fifth aspect, there is provided a communication apparatus, comprising a module or unit configured to perform a method according to any one of the first aspect or the second aspect and possible implementations of the first aspect or the second aspect.

[0045] According to a sixth aspect, a communication device is provided, comprising a processor. The processor may be coupled to a memory and configured to execute instructions in the memory to perform a method according to any one of the first aspect or the second aspect and possible implementations of the first aspect or the second aspect. Optionally, the communication device further comprises the memory. Optionally, the communication device further comprises a communication interface. The processor is coupled to the communication interface.

[0046] Optionally, the communication interface is a transceiver or an input / output interface.

[0047] Optionally, the transceiver may be a transceiver circuit. Optionally, the input / output interface may be an input / output circuit.

[0048] According to a seventh aspect, there is provided a communication apparatus, comprising a module or unit configured to perform a method according to any one of the third or fourth aspects and possible implementations of the third or fourth aspects.

[0049] According to an eighth aspect, a communication device is provided, comprising a processor. The processor may be coupled to a memory and configured to execute instructions in the memory to perform a method according to any one of the third or fourth aspects and possible implementations of the third or fourth aspects. Optionally, the communication device further comprises the memory. Optionally, the communication device further comprises a communication interface. The processor is coupled to the communication interface.

[0050] Optionally, the communication interface is a transceiver or an input / output interface.

[0051] Optionally, the transceiver may be a transceiver circuit. Optionally, the input / output interface may be an input / output circuit.

[0052] According to a ninth aspect, a processor is provided, including an input circuit, an output circuit, and a processing circuit configured to receive a signal through the input circuit and transmit a signal through the output circuit to enable the processor to perform a method according to any one of the first to fourth aspects and possible implementations of the first to fourth aspects.

[0053] In a particular implementation process, the processor may be a chip, the input circuit may be an input pin, the output circuit may be an output pin, and the processing circuit may be a transistor, a gate circuit, a trigger, various logic circuits, etc. An input signal received through an input circuit may be, for example, but not limited to, received and input by a receiver, and a signal output through an output circuit may be, for example, but not limited to, output to a transmitter and transmitted by a transmitter, and the input circuit and the output circuit may be the same circuit, where a circuit is used as an input circuit and an output circuit at different moments. The particular implementation form of the processor and various circuits is not limited in this embodiment of the present application.

[0054] According to a tenth aspect, a processing device is provided, including a processor and a memory. The processor is configured to read instructions stored in the memory and may receive a signal through a receiver and may transmit a signal through a transmitter to perform a method according to any one of the first to fourth aspects and possible implementation forms of the first to fourth aspects.

[0055] Optionally, there are one or more processors and one or more memories.

[0056] Optionally, the memory may be integrated with the processor, or the memory and the processor are separately located.

[0057] In a particular implementation process, the memory may be a non-transitory memory, such as a read-only memory (ROM). The memory and the processor may be integrated on the same chip, or may be separately arranged on different chips. The type of memory and the manner of arranging the memory and the processor are not limited in this embodiment of the present application.

[0058] It should be understood that the associated information exchange process may be a process of outputting information from a processor, and receiving information may be a process of receiving information by a processor. In particular, information output by a processor may be output to a transmitter, and input information received by a processor may be from a receiver. The transmitter and receiver may be collectively referred to as a transceiver.

[0059] The processing device in the tenth aspect may be a chip. The processor may be implemented by hardware or software. When the processor is implemented by hardware, the processor may be a logic circuit, an integrated circuit, etc. When the processor is implemented by software, the processor may be a general-purpose processor and is implemented by reading software code stored in a memory. The memory may be integrated in the processor or may be located outside the processor and exist independently.

[0060] According to an eleventh aspect, a computer program product is provided. The computer program product includes a computer program (sometimes called code or instructions). When the computer program is executed, the computer is enabled to execute a method according to any one of the first to fourth aspects and possible implementations of the first to fourth aspects.

[0061] According to a twelfth aspect, a computer readable medium is provided. The computer readable medium stores a computer program (sometimes called code or instructions). When the computer program is executed on a computer, the computer is enabled to execute a method according to any one of the first to fourth aspects and possible implementations of the first to fourth aspects.

[0062] According to a thirteenth aspect, a communications system is provided and includes at least two of a first access network device, a second access network device, a first core network device, and a second core network device. [Brief description of the drawings]

[0063] [Figure 1] FIG. 2 is a schematic diagram of a user plane protocol stack. [Diagram 2] 1 is a schematic diagram of the protocol stacks of an MCG bearer, an SCG bearer and a split bearer. [Diagram 3] FIG. 1 is a schematic diagram of a system architecture to which the present application applies; [Figure 4A] 2 is an exemplary flowchart of an inter-system handover method according to the present application; [Figure 4B] 2 is an exemplary flowchart of an inter-system handover method according to the present application; [Diagram 5] 1 is a schematic block diagram of a communication device according to the present application; [Figure 6] FIG. 2 is a schematic diagram of the structure of an access network device according to the present application; [Figure 7] 2 is a schematic diagram of the structure of another communication device according to the present application; DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0064] The following describes the technical solutions in this application with reference to the accompanying drawings.

[0065] In a wireless network, one terminal device may communicate with multiple access network devices. That is, the terminal device may perform dual connectivity (DC) communication. In a DC scenario, the standard of the master access network device and the standard of the secondary access network device, i.e., the radio access technology (RAT) used by the master access network device and the radio access technology used by the secondary access network device, may be the same or different.

[0066] Multi-radio dual connectivity (MR-DC) is one type of DC. The access network devices in MR-DC include a master access network device and a secondary access network device using different RATs or the same RAT. A master access network device is an access network device in MR-DC that exchanges control plane signaling with a core network, and another access network device in MR-DC is a secondary access network device. In general, a master access network device is also called a master node (MN), and a secondary access network device is also called a secondary node (SN).

[0067] There are multiple types of MR-DC, for example, evolved universal terrestrial radio access (E-UTRA)-new radio dual connectivity (E-UTRA-NR dual connectivity, EN-DC), next generation radio access network (NG-RAN) evolved universal terrestrial radio access-new radio dual connectivity (NG-RAN E-UTRA-NR dual connectivity, NGEN-DC), new radio-evolved universal terrestrial radio access dual connectivity (NR-E-UTRA dual connectivity, NE-DC), and new radio-new radio dual connectivity (NR-NR dual connectivity, NR-DC).

[0068] In EN-DC, the master access network device and the secondary access network device provide services to terminal devices for connecting to a 4th generation (4G) core network. The 4G core network is sometimes referred to as evolved packet core (EPC). In addition, the master access network device is a long term evolution (LTE) access network device, also referred to as an evolved Node B (eNB). The secondary access network device is an NR access network device, also referred to as a gNB. EN-DC is sometimes also referred to as non standalone (NSA). In an EN-DC network, terminal devices cannot camp on NR cells. NR access network devices on which terminal devices can camp are sometimes also referred to as standalone (SA) NR access network devices.

[0069] In NGEN-DC, the master access network device and the secondary access network device provide services to terminal devices for connecting to a fifth generation (5th generation, 5G) core network (5G core, 5GC). In addition, the master access network device is an LTE access network device, and the secondary access network device is an NR access network device.

[0070] In the NE-DC, the master access network device and the secondary access network device provide services for connecting to the 5GC to the terminal device. In addition, the master access network device is an NR access network device, and the secondary access network device is an LTE access network device.

[0071] In NR-DC, the master access network device and the secondary access network device provide services to terminal devices for connecting to 5GC. In addition, both the master access network device and the secondary access network device are NR access network devices.

[0072] It should be understood that in this application, the access network device provides a service for connecting to the EPC to the terminal device means that the data plane transmission between the terminal device and the EPC is performed through the access network device. The access network device provides a service for connecting to the 5GC to the terminal device means that the data plane transmission between the terminal device and the 5GC is performed through the access network device.

[0073] It should be noted that when an eNB provides a service to a UE to connect to 5GC, the eNB is also called an ng-eNB. When a gNB provides a service to a UE to connect to an EPC, the gNB is also called an en-gNB. In MR-DC, an access network device has different radio link control (RLC) / medium access control (MAC) entities. In MR-DC, data radio bearers (DRBs) are classified into master cell group (MCG) bearers, secondary cell group (SCG) bearers, and split bearers. MCG bearers mean that the RLC / MAC entity of the DRB only exists on the master access network device. SCG bearers mean that the RLC / MAC entity of the DRB only exists on the secondary access network device. Split bearers mean that the RLC / MAC entity of the DRB exists on both the master access network device and the secondary access network device. A bearer for which packet data convergence protocol (PDCP) is terminated in the master access network device is called an MN terminated bearer. For an MN terminated bearer, downlink data arrives directly from the core network to the master access network device and is processed by using the PDCP / service data adaptation protocol (SDAP) of the master access network device before being sent to the terminal device through RLC / MAC, and uplink data is processed through the PDCP / SDAP of the master access network device before being sent to the core network. A bearer for which PDCP is terminated in the secondary access network device is called an SN terminated bearer.For SN terminated bearers, downlink data arrives directly from the core network to the secondary access network device, is processed through the PDCP / SDAP of the secondary access network device, and is then sent to the terminal device through RLC / MAC, and uplink data is processed through the PDCP / SDAP of the secondary access network device, and is then sent to the core network.

[0074] Figure 1 shows the user plane protocol stack of EN-DC on the network side and the user plane protocol stack of MR-DC with 5GC on the network side. It should be understood that the transmission on each bearer needs to be performed through RLC / MAC and PDCP / SDAP.

[0075] FIG. 2 is a schematic diagram of the protocol stacks of the MCG bearer, the SCG bearer, and the split bearer on the network side at the NGEN-DC / NE-DC / NR-DC.

[0076] The solution in this application is applicable to inter-system handover from non-MR-DC to MR-DC. In other words, before handover, the terminal device accesses the core network through only one access network device. After handover, the terminal device accesses the core network in a DC manner. In addition, the core network before handover is different from the core network after handover. For example, one core network is EPC and the other core network is 5GC.

[0077] Figure 3 is a schematic diagram of a communication scenario to which the present application is applied. The scenario shown in Figure 3 is an inter-system handover from NR to EN-DC. In Figure 3, before the handover, the gNB provides the UE with a service for connecting to 5GC. After the handover, the gNB and eNB provide the UE with a service in a DC manner. The eNB is the master access network device of the UE, and the gNB is the secondary access network device of the UE. In addition, after the handover, the gNB and eNB provide the UE with a service for connecting to EPC.

[0078] It should be understood that in this application, an access network device is an apparatus arranged in a radio access network to provide a wireless communication function to a terminal device. For example, an access network device in a 4G network, i.e., an LTE access network device, includes, but is not limited to, an evolved NodeB (eNB), a Radio Network Controller (RNC), a NodeB (NB), a Base Station Controller (BSC), a Base Transceiver Station (BTS), a home base station (e.g., Home evolved NodeB, or Home NodeB, HNB), a BaseBand Unit (BBU), and an access point (AP), a wireless relay node, a wireless backhaul node, a transmission point (TP), or a transmission and reception point (TRP) in a Wireless Fidelity (Wi-Fi) system. For another example, an access network device in a 5G network, i.e., an NR access network device, includes, but is not limited to, a gNB, a transmission point (TRP or TP), and an antenna panel or a group of antenna panels (including multiple antenna panels) of a gNodeB in a 5G system. Alternatively, an access network device in a 5G network may be a network node applied in a gNB or a transmission point, such as a baseband unit (BBU), a distributed unit (DU), a radio controller in a cloud radio access network (CRAN) scenario, a wearable device, or an in-vehicle device.

[0079] In some arrangements, the gNB may include a centralized unit (CU) and a DU. The gNB may further include a radio unit (RU). The CU implements some functions of the gNB, and the DU implements some functions of the gNB. For example, the CU implements functions of a radio resource control (RRC) layer and a packet data convergence protocol (PDCP) layer. The DU implements functions of a radio link control (RLC) layer, a media access control (MAC) layer, and a physical (PHY) layer. Information at the RRC layer eventually becomes information at the PHY layer or is converted from information at the PHY layer. Therefore, in this architecture, higher layer signaling, such as RRC layer signaling, may also be considered to be sent by the DU or by the DU and CU. It may be understood that the network device may be a CU node, a DU node, or a device including a CU node and a DU node. In addition, the CU may be classified as a network device in an access network (radio access network, RAN) or as a network device in a core network (core network, CN), which is not limited in this application.

[0080] It should be further understood that in the present application, the control plane device in the EPC may be a mobility management entity (MME) or an entity having MME functionality, and the control plane device in the 5GC may be an access and mobility management entity (AMF) or an entity having AMF functionality.

[0081] It should be further understood that the terminal device in this application may also be referred to as user equipment (UE), access terminal, subscriber unit, subscriber station, mobile station, remote station, remote terminal, mobile device, user terminal, terminal, wireless communication device, user agent, or user equipment. The terminal device in the embodiment of this application may be a mobile phone, a tablet, a computer with wireless transceiver function, a virtual reality (VR) terminal device, an augmented reality (AR) terminal device, a wireless terminal in industrial control, a wireless terminal in self driving, a wireless terminal in remote medical, a wireless terminal in smart grid, a wireless terminal in transportation safety, a wireless terminal in smart city, a wireless terminal in smart home, etc.

[0082] In the current technology, for example in the scenario shown in Figure 3, after handover, even data packets corresponding to bearers terminated at the gNB need to be forwarded to the gNB again, which causes data transmission delays.

[0083] In order to solve the above problems, this application provides an inter-system handover method. The following describes the solution in this application.

[0084] Before the solution in this application is described, a first access network device, a second access network device, a first core network device, and a second core network device are first described.

[0085] Before the terminal device is handed over, the second access network device provides the terminal device with a service for connecting to a second core network. After the terminal device is handed over, the second access network device provides the terminal device with a service for connecting to a first core network, and the first access network device provides the terminal device with a service for connecting to the first core network.

[0086] The first core network device is a control plane device in a first core network, and the second core network device is a control plane device in a second core network.

[0087] For example, the first core network may be an EPC, and the second core network may be a 5GC. In this case, for example, the first access network device, the second access network device, the first core network device, and the second core network device may correspond to an eNB, a gNB, a control plane device in the EPC, and a control plane device in the 5GC, respectively, in the scenario shown in FIG. 3.

[0088] In another example, the second core network may be an EPC and the first core network may be a 5GC. In another example, the first core network may be a 5GC and the second core network may be a future 6G core network.

[0089] The first core network device and the second core network device may be completely different or may have some of the same functions.

[0090] It should be understood that Figure 3 is merely an example scenario applicable to the present application, which may alternatively be applied to other scenarios.

[0091] 4A and 4B are a schematic flowchart of an inter-system handover method according to the present application. The steps of the method 400 are described below.

[0092] S401: A second access network device sends a first message to a second core network device. In response, the second core network device receives the first message.

[0093] The first message is used to request the first access network device to allocate resources to the terminal device, which is the terminal device on which the handover procedure will be performed. After the first access network device allocates resources to the terminal device, the terminal device may be handed over to the first access network device.

[0094] The first message may include an identification information of the terminal device, the identification information of the terminal device being an identification information of the terminal device on the second access network device side.

[0095] For example, the identity of the terminal device may be: The C-RNTI may include one or more of: a frequency channel number of a serving cell of the second access network device in which the terminal device is located; a PCI of a serving cell of the second access network device in which the terminal device is located; a C-RNTI allocated to the terminal device by a serving cell of the second access network device in which the terminal device is located; identification information of the terminal device on the interface between the second access network device and the second core network device; and transport layer information (e.g., an IP address of a tunnel port and / or an identifier of a tunnel port) corresponding to a protocol data unit (PDU) session corresponding to a data service of the terminal device on a user plane transport tunnel between the second access network device and the second core network device.

[0096] For example, the identity of the terminal device may be the C-RNTI. In another example, the identity of the terminal device may be jointly represented by a frequency channel number, a PCI, and a C-RNTI.

[0097] For example, the identification information of a terminal device on an interface between a second access network device and a second core network device may be allocated by the second access network device or may be allocated by the second core network device.

[0098] It should be understood that a serving cell of the second access network device and in which the terminal device is located is a serving cell provided to the terminal device by the second access network device.

[0099] For example, the second core network device is a control plane device in 5GC. The interface between the second access network device and the second core network device is an NG interface. The identity of the terminal device on the interface between the second access network device and the second core network device may be a RAN UE NGAP ID, and the second access network device uniquely associates the identity to the terminal device on the NG interface. Alternatively, the identity of the terminal device on the interface between the second access network device and the second core network device may be an AMF UE NGAP ID, and the second core network device uniquely associates the identity to the terminal device on the NG interface. On the user plane transport tunnel between the second access network device and the second core network device, the transport layer information corresponding to the PDU session corresponding to the data service of the terminal device may be NG user plane transport layer information, for example, an IP address of a GPRS tunneling protocol (GTP) tunnel port and an identifier of a GTP tunnel port of the PDU session tunnel on the second access network device side.

[0100] Optionally, the first message may further include an identification information of the second access network device.

[0101] The following describes the first identification information with reference to two scenarios.

[0102] Scenario 1:

[0103] The identification information used when the second access network device provides a service to a terminal device for connecting to the second core network is the same as the identification information used when the second access network device provides a service to a terminal device for connecting to the first core network.

[0104] For ease of understanding, the identity of the second access network device in scenario 1 is herein denoted as identity #1.

[0105] For example, identification #1 may be: The identification number may include one or more of a global RAN identifier of the second access network device, a frequency channel number of a cell managed by the second access network device, a PCI of a cell managed by the second access network device, a PCI of a serving cell of the second access network device in which the terminal device is located, a frequency channel number of a serving cell of the second access network device in which the terminal device is located, and a cell global identifier (CGI) of a serving cell of the second access network device in which the terminal device is located.

[0106] For example, the global base station identifier may include a public land mobile network (PLMN) identifier and a base station identifier. For example, the global base station identifier may be represented by a PLMN identifier and a base station identifier together. For example, the second access network device is a control plane device in 5GC. The global base station identifier of the second access network device is the global NodeB ID of the second access network device.

[0107] For example, the identification information #1 may be represented by the frequency channel number of the cell managed by the second access network device and the PCI of the cell managed by the second access network device together. Alternatively, the identification information #1 may be represented by the frequency channel number of the serving cell of the second access network device and in which the terminal device is located together with the CGI of the serving cell of the second access network device and in which the terminal device is located together.

[0108] Scenario 2:

[0109] The identification information used when the second access network device provides a service to a terminal device for connecting to the second core network is different from the identification information used when the second access network device provides a service to a terminal device for connecting to the first core network.

[0110] In this scenario, there are two implementations.

[0111] Method 1: The identification information of the second access network device may be identification information used when the second access network device provides a service for connecting to the first core network to the terminal device.

[0112] Method 2: The identification information of the second access network device may be identification information used when the second access network device provides a service for connecting to a second core network to a terminal device.

[0113] Different implementations correspond to different method steps, which are described in detail in the following steps.

[0114] In this specification, for ease of understanding, the identification information of the second access network device in method 1 in scenario 2 is indicated as identification information #2, and the identification information of the second access network device in method 2 in scenario 2 is indicated as identification information #3.

[0115] For example, identification #2 may be: a global base station identifier, which is used when the second access network device provides a service for connecting to the first core network to the terminal device and belongs to the second access network device; a frequency channel number, which is used when the second access network device provides a service for connecting to the first core network to the terminal device and belongs to a cell managed by the second access network device; a PCI, which is used when the second access network device provides a service for connecting to the first core network to the terminal device and belongs to a cell managed by the second access network device; The access network device may include one or more of: a PCI that is used when the second access network device provides services to the terminal device and that is of the second access network device and that is of the serving cell in which the terminal device is located; a frequency channel number that is used when the second access network device provides services to the terminal device for connecting to the first core network and that is of the second access network device and that is of the serving cell in which the terminal device is located; and a CGI that is used when the second access network device provides services to the terminal device for connecting to the first core network and that is of the second access network device and that is of the serving cell in which the terminal device is located.

[0116] For example, the global base station identifier may include a PLMN identifier and a base station identifier. For example, the first network system is a system connected to a 4G core network. The base station identifier of the second access network device is an en-gNB ID.

[0117] For example, the identification information #2 may be represented jointly by a frequency channel number used when the second access network device provides services to a terminal device for connecting to the first core network and which belongs to all cells managed by the second access network device, and a PCI used when the second access network device provides services to a terminal device for connecting to the first core network and which belongs to all cells managed by the second access network device.

[0118] For example, the first core network device is a control plane device in the EPC, and the second core network device is a control plane device in the 5GC. The global base station identifier used when the second access network device provides a service for connecting to the first core network to the terminal device and belongs to the second access network device is the global en-g Node B identifier global en-gNB ID of the second access network device serving as an access network device in the NSA. The frequency channel number used when the second access network device provides a service for connecting to the first core network to the terminal device and belongs to the cell managed by the second access network device is the frequency channel number of the cell managed by the second access network device serving as an access network device in the NSA. Other cases are similar to the above description and will not be described one by one again in this specification.

[0119] For example, identification #3 may be: a global base station identifier, which is used when the second access network device provides a service for connecting to the second core network to a terminal device and belongs to the second access network device; a frequency channel number, which is used when the second access network device provides a service for connecting to the second core network to a terminal device and belongs to a cell managed by the second access network device; a PCI, which is used when the second access network device provides a service for connecting to the second core network to a terminal device and belongs to a cell managed by the second access network device; The communication interface may include one or more of: a PCI that is used when the second access network device provides services to the terminal device and that is of the second access network device and that is of the serving cell in which the terminal device is located; a frequency channel number that is used when the second access network device provides services to the terminal device for connecting to the second core network and that is of the second access network device and that is of the serving cell in which the terminal device is located; and a CGI that is used when the second access network device provides services to the terminal device for connecting to the second core network and that is of the second access network device and that is of the serving cell in which the terminal device is located.

[0120] For example, the global base station identifier may include a PLMN identifier and a base station identifier.

[0121] For example, the first core network device is also a control plane device in the EPC, and the second core network device is also a control plane device in the 5GC. The global base station identifier used when the second access network device provides a service for connecting to the second core network to the terminal device and belongs to the second access network device is the global gNodeB identifier global gNB ID of the second access network device serving as the access network device in the SA. The frequency channel number used when the second access network device provides a service for connecting to the second core network to the terminal device and belongs to the cell managed by the second access network device is the frequency channel number of the cell managed by the second access network device serving as the access network device in the SA. Other cases are similar to the above description. Details will not be described again in this specification.

[0122] Optionally, the first message may be a handover required message, however, this is not a limitation in this application.

[0123] Optionally, the identity of the second access network device and / or the identity of the terminal device may be carried in a source to target transparent container in a handover request type message.

[0124] S402: The second core network device sends a relocation request message to the first core network device. In response, the first core network device receives the relocation request message.

[0125] The relocation request message is used to request the first access network device to allocate resources to the terminal device. The relocation request message may include identification information of the terminal device.

[0126] Optionally, the relocation request message may further include an identification information of the second access network device.

[0127] It should be appreciated that the relocation request message is merely an example name and that the relocation request message may alternatively have another name.

[0128] Optionally, the identification information of the second access network device and / or the identification information of the terminal device may be carried in a source-to-target transparent container in the relocation request message.

[0129] S403: The first core network device sends a handover request message to the first access network device. In response, the first access network device receives the handover request message.

[0130] The handover request message is used to request the terminal device to handover to the first access network device and to request the first access network device to allocate resources to the terminal device. The handover request message may include identification information of the terminal device.

[0131] Optionally, the handover request message may further include an identification information of the second access network device.

[0132] It should be appreciated that the handover request message is merely an example name and that the handover request message may alternatively have another name.

[0133] Optionally, the identification information of the second access network device and / or the identification information of the terminal device may be carried in a source-to-target transparent container in the handover request message.

[0134] S404: The first access network device determines that a secondary access network device to be added for the terminal device is the second access network device.

[0135] For example, the first access network device may determine that the secondary access network device to be added for the terminal device is the second access network device based on the identification information of the second access network device. Alternatively, the first access network device may learn the pre-handover second access network device based on the identifier carried in the handover request message and of the pre-handover serving cell to determine that the secondary access network device to be added for the terminal device is the second access network device (where, for example, the handover request message carries the mobility history information of the terminal device, and the pre-handover serving cell of the terminal device can be learned from the mobility history information of the terminal device, or the handover request message carries the identifier of the pre-handover serving cell directly).

[0136] S405: The first access network device sends a request message for adding a secondary access network device to the second access network device. In response, the second access network device receives the request message for adding a secondary access network device.

[0137] The request message for adding a secondary access network device includes identification information of the terminal device. The request message for adding a secondary access network device is used to request adding a second access network device as a secondary access network device of the terminal device.

[0138] For example, in S404, after receiving the handover request message, the first access network device may determine to add the second access network device corresponding to the identification information of the second access network device as the secondary access network device of the terminal device. Then, S405 is executed.

[0139] For another example, in S404, the first access network device may first determine a secondary access network device, and then determine whether the determined secondary access network device is a second access network device based on the identification information of the second access network device. If the secondary access network device determined by the first access network device is the second access network device, S405 is executed.

[0140] The following explains S404 by using examples for the two scenarios described in S401.

[0141] In the case of scenario 1, since the identification information used when the second access network device provides the terminal device with a service for connecting to the second core network is the same as the identification information used when the second access network device provides the terminal device with a service for connecting to the first core network, the first access network device may determine that the access network device corresponding to the identification information of the second access network device is the second access network device in order to determine that the secondary access network device to be added for the terminal device is the second access network device.

[0142] In the case of the first method in the second scenario, after receiving the handover request message, the first access network device may determine to add the second access network device corresponding to the identification information of the second access network device as the secondary access network device of the terminal device. Alternatively, the first access network device may first determine the secondary access network device, and then compare whether the identification information of the determined secondary access network device is the identification information of the second access network device. If the identification information of the determined secondary access network device is the identification information of the second access network device, the first access network device may determine that the secondary access network device is the second access network device.

[0143] In the case of the method 2 in the scenario 2, the first access network device may determine that the secondary access network device to be added for the terminal device is the second access network device based on the identification information of the second access network device and the first mapping relationship. The first mapping relationship is a mapping relationship between the identification information used when the second access network device provides the terminal device with a service for connecting to the second core network and the identification information used when the second access network device provides the terminal device with a service for connecting to the first core network. That is, the first mapping relationship is a mapping relationship between the identification information #2 and the identification information #3.

[0144] In detail, after receiving the identification information of the second access network device which is actually identified by using the identification information #3, the first access network device may determine that the identification information #3 corresponds to the identification information #2 based on the mapping relationship between the identification information #2 and the identification information #3. In this way, the first access network device may add the access network device (i.e., the second access network device) which is identified by using the identification information #2 (or corresponds to the identification information #2) to be the secondary access network device. Alternatively, the first access network device may first determine the secondary access network device, and then compare whether the identification information of the determined secondary access network device is the identification information #2. If the identification information of the determined secondary access network device is the identification information #2, the first access network device determines that the secondary access network device to be added for the terminal device is the second access network device.

[0145] Optionally, the first mapping relationship may be sent by the second access network device to the first access network device.

[0146] It should be understood that the second access network device may send the first mapping relationship before step S404. For example, when an Xn / X2 interface connection is set up between the second access network device and the first access network device, the second access network device may send the first mapping relationship to the first access network device.

[0147] For example, for EN-DC, the first mapping relationship may be carried in an EN-DC X2 Setup Request message or an EN-DC X2 Setup Response message between the first access network device and the second access network device. If the second access network device initiates an EN-DC X2 setup request message, the second access network device includes the first mapping relationship in the message. If the first access network device initiates an EN-DC X2 setup request message, the second access network device includes the first mapping relationship in the EN-DC X2 setup response message.

[0148] Optionally, the mapping relationship between the identity of the second access network device and the second identity is: A mapping relationship between a global base station identifier used when the second access network device provides a service for connecting to the first core network to the terminal device, and a global base station identifier used when the second access network device provides a service for connecting to the second core network to the terminal device; a mapping relationship between a frequency channel number used when the second access network device provides a service for connecting to the first core network to a terminal device and which belongs to a cell managed by the second access network device, and a frequency channel number used when the second access network device provides a service for connecting to the second core network to a terminal device and which belongs to a cell managed by the second access network device; a mapping relationship between a PCI used when the second access network device provides a service to a terminal device for connecting to a first core network and which belongs to a cell managed by the second access network device, and a PCI used when the second access network device provides a service to a terminal device for connecting to a second core network and which belongs to a cell managed by the second access network device; a mapping relationship between a PCI used when the second access network device provides a service for connecting to a first core network to a terminal device, the PCI being of the second access network device and of a serving cell in which the terminal device is located, and a PCI used when the second access network device provides a service for connecting to a second core network to a terminal device, the PCI being of the second access network device and of a serving cell in which the terminal device is located; A mapping relationship between a frequency channel number used when the second access network device provides a service for connecting to the first core network to the terminal device, the frequency channel number being of the second access network device and of a serving cell in which the terminal device is located, and a frequency channel number used when the second access network device provides a service for connecting to the second core network to the terminal device, the frequency channel number being of the second access network device and of a serving cell in which the terminal device is located; and The method may include one or more of the following mapping relationships between a CGI used when the second access network device provides a service to a terminal device for connecting to a first core network, the CGI being of the second access network device and of a serving cell in which the terminal device is located, and a CGI used when the second access network device provides a service to a terminal device for connecting to a second core network, the CGI being of the second access network device and of a serving cell in which the terminal device is located.

[0149] It should be noted that in practice, the first access network device may alternatively select another access network device different from the second access network device as the secondary access network device.

[0150] After the second access network device receives the request message to add the secondary access network device, if the second access network device determines based on the identification information of the terminal device that the terminal device is a terminal device that the secondary access network device is serving (in other words, before handover), the second access network device may skip forwarding data corresponding to the bearer terminated at the second access network device. In other words, it is not required that the data corresponding to the bearer terminated at the second access network device is first sent by the second access network to the second core network, then forwarded by the second core network to the first core network, and then forwarded by the first core network to the second access network, and it is not required that the data corresponding to the bearer terminated at the second access network device is first sent to the first access network device, and then forwarded by the first access network device to the second access network device.

[0151] It should be understood that the bearers terminated at the second access network device may include SCG bearers terminated at the second access network device, split bearers terminated at the second access network device, and MCG bearers terminated at the second access network device.

[0152] In conclusion, according to the method provided in the present application, the second access network device may provide the identification information of the terminal device on which the handover procedure will be performed to the first access network device in the handover process. When determining that the target secondary access network device (i.e., the above-mentioned secondary access network device) and the source access network device (i.e., the second access network device) are the same access network device, the first access network device provides the identification information of the terminal device to the source access network device, so that the source access network device does not forward data corresponding to the bearer terminated in the source access network device, and then the data transmission delay can be shortened.

[0153] Optionally, the method may further include some or all of steps S406 to S413.

[0154] S406: The second access network device sends a response message to the first access network device for adding the secondary access network device.

[0155] In response, the first access network device receives a response message to add the secondary access network device.

[0156] After the second access network device receives the request message for adding a secondary access network device, if the second access network device agrees to serve as a secondary access network device for the terminal device, the second access network device sends a response message for adding the secondary access network device to the first access network device.

[0157] It should be understood that the first access network device will serve as the master access network device for the terminal device.

[0158] S407: The first access network device sends a handover request recognition response message to the first core network device.

[0159] Optionally, the handover request recognition response message may include indication information for maintaining the context of the terminal device.

[0160] Optionally, indication information for maintaining the context of the terminal device may be carried in a Target to source Transparent container in the handover request acknowledge response message.

[0161] S408: The first core network device sends a relocation response message to the second core network device.

[0162] It should be appreciated that the relocation response message is used to respond to the relocation request message described above.

[0163] Optionally, the relocation response message may include display information for maintaining the context of the terminal device.

[0164] Optionally, display information for preserving the context of the terminal device may be carried in a target-to-source transparent container in the relocation response message.

[0165] S409: The second core network device sends a handover command to the second access network device.

[0166] It should be understood that the handover command is used to respond to the first message above.

[0167] Optionally, the handover command may include indication information for maintaining the context of the terminal device.

[0168] Optionally, indication information for preserving the context of the terminal device may be carried in a target-to-source transparent container in the handover command.

[0169] S410: The second access network device sends an RRC message to the terminal device.

[0170] The RRC message is used to notify the terminal device that it is being handed over to the first access network device.

[0171] For example, in a handover scenario from NR to EN-DC, the RRC message may be a mobility from NRCommand.

[0172] S411: The terminal device and the first access network device perform a random access procedure.

[0173] S412: The terminal device sends an RRC connection reconfiguration complete message to the first access network device.

[0174] Through steps S410 to S412, the terminal device may access the first access network device, and the second access network device may provide the terminal device with services for connecting to the first core network.

[0175] For details of steps S410 to S412, please refer to the current state of the art.

[0176] S413: The terminal device and the second access network device perform a random access procedure.

[0177] This step may or may not be performed. The main function of this step is to adjust the uplink timing for the terminal device so that the terminal device accesses the second access network device and the second access network device avoids interference between the terminal devices served by the second access network device.

[0178] S414: The first access network device sends a secondary access network device reconfiguration complete message to the second access network device.

[0179] S415: The second access network device initiates data forwarding.

[0180] That is, the second access network device sends data corresponding to the bearers terminated at the first access network device to the first access network device (where the bearers terminated at the first access network device are used after the handover). The data includes data that the second access network device has received and / or will subsequently receive from the second core network. The second access network device may send the data directly to the first access network device. Alternatively, the second access network device may first send the data to the second core network, which then forwards the data to the first core network, which sends the data to the first access network device.

[0181] It should be understood that the bearers terminated at the first access network device may include SCG bearers terminated at the first access network device, split bearers terminated at the first access network device, and MCG bearers terminated at the first access network device.

[0182] It should further be appreciated that S415 may alternatively be performed after S409.

[0183] S416: The first access network device sends a handover notification message to the first core network device.

[0184] The handover notification message is used to notify the first core network device that the handover of the terminal device to the first access network device has been completed.

[0185] The first core network device may then send a bearer modification message to a user plane device in the first core network.

[0186] For example, when the first core network device is a control plane device in the EPC, the user plane device in the first core network is an S-GW.

[0187] The bearer modification message is used to notify the target side device that the terminal device is accessing, and the user plane device in the first core network may notify the user plane device in the second core network that the user plane device in the second core network may stop sending data to the second access network device.

[0188] S417: The second access network device performs data transmission with the terminal device.

[0189] For example, when the second core network device is a control plane device in the 5GC and the first core network device is a control plane device in the EPC, the second access network device may map a data packet belonging to a QoS flow and received from the second core network device to a DRB corresponding to an E-RAB applicable after the handover based on a mapping relationship between the QoS flow and the E-RAB, and may send the data packet to the terminal device.

[0190] In another example, when the first core network device is a control plane device in the 5GC and the second core network device is a control plane device in the EPC, the second access network device may map a data packet belonging to an E-RAB and received from the second core network device to a DRB corresponding to the handed over QoS flow based on the mapping relationship between the QoS flow and the E-RAB, and may send the data packet to the terminal device.

[0191] Optionally, when the second access network device performs data transmission with the terminal device, in order to enable data transmission between the second access network device and the terminal device that should not be interrupted, the second access network device may continue to communicate with the terminal device in the handover process. The second access network device continues to perform data communication with the terminal device by using the applicable key before the handover, and the second access network device performs data communication with the terminal device by using the applicable key after the handover (i.e., serving as the key of the secondary access network device).

[0192] For example, in solution 1, the second access network device transmits a data packet received from the second core network on a first DRB by using an applicable key before handover, and the second access network device transmits a data packet (a data packet received from the first core network) corresponding to a bearer terminated in the second access network device on a second DRB by using an applicable key after handover. The first DRB may be one or more DRBs, and the second DRB may be one or more DRBs, and there is no intersection between the first DRB and the second DRB.

[0193] Solution 2: The second access network device first transmits data packets received from the second core network on one or more DRBs by using the applicable key before handover, and after sending the data to the terminal device, the second access network device transmits data packets (data packets received from the first core network) corresponding to the bearers terminated in the second access network device on one or more DRBs by using the applicable key after handover.

[0194] Solution 3: The second access network device sets up two logical channels on one DRB, and transmits data packets received from the second core network on one of the logical channels by using an applicable key before handover, and transmits data packets corresponding to bearers terminated in the second access network device (data packets received from the first core network) on the other logical channel by using an applicable key after handover.

[0195] It should be understood that the above sequence of steps is not limited in the present application. The values ​​of step numbers in method 400 do not represent the actual execution sequence of the method. In practice, not all steps in method 400 need to be executed, and the sequence of steps may alternatively be different from the sequence shown in FIG. 4A and FIG. 4B.

[0196] The method provided in the embodiment of the present application is described in detail above with reference to Figures 4A and 4B. The apparatus provided in the embodiment of the present application is described in detail below with reference to Figures 5 to 7.

[0197] 5 is a schematic block diagram of a communication device according to an embodiment of the present application. As shown in FIG. 5, the communication device 1000 may include a transceiver unit 1100 and a processing unit 1200.

[0198] The transceiver unit 1100 may be configured to send or receive information to or from another device, e.g., send or receive a request message for adding a secondary access network device. The processing unit 1200 may be configured to perform internal processing of the device, e.g., determine that a secondary access network device to be added for a terminal device is a second access network device.

[0199] In one implementation, the communication device 1000 may correspond to a first access network device. The communication device 1000 may be the first access network device or a chip disposed in the first access network device, and may include a unit configured to perform the operations performed by the first access network device. In addition, the units in the communication device 1000 are separately configured to implement the operations performed by the first access network device in the above method.

[0200] In detail, the transceiver unit 1100 is configured to receive a handover request message from a first core network device, where the handover request message includes an identification information of the terminal device, and the apparatus provides the terminal device with a service for connecting to a first core network, and the first core network device belongs to the first core network. The processing unit 1200 is configured to determine that a secondary access network device to be added for the terminal device is a second access network device, where the second access network device provides the terminal device with a service for connecting to a second core network. The transceiver unit 1100 is further configured to send a request message for adding a secondary access network device to the second access network device, where the request message for adding a secondary access network device includes the identification information of the terminal device.

[0201] Optionally, the identity of the terminal device is a Cell Radio Network Temporary Identifier C-RNTI of the second access network device and allocated to the terminal device in a serving cell in which the terminal device is located, or the identity of the terminal device is an identity of the terminal device on an interface between the second access network device and a second core network device, where the second core network device belongs to the second core network.

[0202] Optionally, the handover request message further includes an identification information of the second access network device.

[0203] Optionally, the identification information of the second access network device is an identification information used when the second access network device provides a service to the terminal device for connecting to the first core network.

[0204] Optionally, the identification information of the second access network device is an identification information used when the second access network device provides a service to a terminal device for connecting to a second core network.

[0205] Optionally, the transceiver unit 1100 is further configured to receive a first mapping relationship from the second access network device, where the first mapping relationship is a mapping relationship between an identification used when the second access network device provides a service for connecting to the first core network to the terminal device and an identification used when the second access network device provides a service for connecting to the second core network to the terminal device. The processing unit 1200 is specifically configured to determine, based on the identification information of the second access network device and the first mapping relationship, that a secondary access network device to be added for the terminal device is the second access network device.

[0206] In another implementation, the communication device 1000 may correspond to a second access network device. The communication device 1000 may be the second access network device or a chip disposed in the second access network device, and may include a unit configured to perform the operations performed by the second access network device. In addition, the units in the communication device 1000 are separately configured to implement the operations performed by the second access network device in the above method.

[0207] In detail, the transceiver unit 1100 is configured to send a first message to a second core network device, where the first message includes an identification information of the terminal device, the apparatus provides the terminal device with a service for connecting to a second core network, the second core network device belongs to the second core network, the first message is used to request the first access network device to allocate resources to the terminal device, and the first access network device provides the terminal device with a service for connecting to the first core network. The transceiver unit 1100 is further configured to receive a request message for adding a secondary access network device from the first access network device, where the first access network device is a master access network device of the terminal device, the request message for adding the secondary access network device includes an identification information of the terminal device, and the request message for adding the secondary access network device is used to request adding the apparatus as a secondary access network device of the terminal device.

[0208] Optionally, the identity of the terminal device is a Cell Radio Network Temporary Identifier C-RNTI that is of the apparatus and allocated to the terminal device in a serving cell in which the terminal device is located, or the identity of the terminal device is an identity of the terminal device on an interface between the apparatus and the second core network device.

[0209] Optionally, the first message further comprises an identification of the device.

[0210] Optionally, the identity of the second access network device is an identity used when the apparatus provides a service to a terminal device for connecting to the first core network.

[0211] Optionally, the identity of the second access network device is an identity used when the apparatus provides a service to a terminal device for connecting to the second core network.

[0212] Optionally, the transceiver unit 1100 is further configured to send a first mapping relationship to the first access network device, where the first mapping relationship is a mapping relationship between an identification information used when the apparatus provides a service for connecting to the first core network to the terminal device and an identification information used when the apparatus provides a service for connecting to the second core network to the terminal device.

[0213] Optionally, the transceiver unit 1100 is further configured to send data corresponding to the bearer terminated at the first access network device to the first access network device.

[0214] Optionally, the processing unit 1200 is configured to skip forwarding data corresponding to bearers terminated at the device.

[0215] Optionally, the processing unit 1200 is further configured to map a data packet of a quality of service QoS flow received from the second core network device to a data radio bearer DRB corresponding to an evolved universal terrestrial radio access network radio access bearer E-RAB applicable after the handover based on a mapping relationship between the QoS flow and the E-RAB. The sending unit 1100 is further configured to send the data packet mapped to the data radio bearer DRB corresponding to the handed over E-RAB to the terminal device.

[0216] In yet another implementation, the communication device 1000 may correspond to a first core network device. The communication device 1000 may be the first core network device or a chip disposed in the first core network device, and may include a unit configured to perform the operations performed by the first core network device. In addition, the units in the communication device 1000 are separately configured to implement the operations performed by the first core network device in the above method.

[0217] In detail, the transceiver unit 1100 is configured to receive a first message from a second access network device. The transceiver unit 1100 is further configured to send a relocation request message to the first core network device based on the first message. The first message includes an identification information of the terminal device, and the first message is used to request the first access network device to allocate resources to the terminal device. The relocation request message includes the identification information of the terminal device. The second access network device provides the terminal device with a service for connecting to a second core network, and the first access network device provides the terminal device with a service for connecting to a first core network. The apparatus 1000 belongs to the second core network, and the first core network device belongs to the first core network.

[0218] In yet another implementation, the communication device 1000 may correspond to a second core network device. The communication device 1000 may be the second core network device or a chip disposed in the second core network device, and may include a unit configured to perform the operations performed by the second core network device. In addition, the units in the communication device 1000 are separately configured to implement the operations performed by the second core network device in the above method.

[0219] In detail, the transceiver unit 1100 is configured to receive a relocation request message from a second core network device, where the relocation request message includes an identification information of the terminal device, the second access network device provides the terminal device with a service for connecting to a second core network, and the first access network device provides the terminal device with a service for connecting to a first core network. The transceiver unit is further configured to send a handover request message to the first access network device, where the handover request message includes an identification information of the terminal device. The second core network device belongs to a second core network, and the apparatus 1000 belongs to the first core network.

[0220] It should be understood that the specific process in which the unit executes the above corresponding steps performed by the corresponding network element has been described in detail in the above method embodiment, and for the sake of brevity, the details will not be described again herein.

[0221] It should be further understood that when the communication device 1000 is a first access network device or a second access network device, the transceiver unit 1100 in the communication device 1000 may correspond to the RRU 2100 in the access network device 2000 shown in Figure 6, and the processing unit 1200 in the communication device 1000 may correspond to the BBU 2200 in the access network device 2000 shown in Figure 6. When the communication device 1000 is a chip configured in the first access network device or the second access network device, the transceiver unit 1100 in the communication device 1000 may be an input / output interface.

[0222] It should be further understood that when the communication device 1000 is a first core network device or a second core network device, the transceiver unit 1100 in the communication device 1000 may correspond to the transceiver 3002 in the communication device 3000 shown in FIG. 7, and the processing unit 1200 in the communication device 1000 may correspond to the processor 3001 in the communication device 3000 shown in FIG. 7.

[0223] FIG. 6 is a schematic diagram of the structure of an access network device according to an embodiment of the present application, which may be, for example, a schematic diagram of the structure of a base station. The base station 2000 may be used in the system shown in FIG. 3 and performs the functions of the first access network device or the second access network device in the above method embodiment. As shown in the figure, the base station 2000 may include one or more radio frequency units, such as a remote radio unit (RRU) 2100, and one or more baseband units (BBUs) (sometimes referred to as distributed units (DUs)) 2200. The RRU 2100 may be referred to as a transceiver unit or a communication unit, and corresponds to the transceiver unit 1100 in FIG. 5. Optionally, the transceiver unit 2100 may be referred to as a transceiver, a transceiver circuit, etc., and may include at least one antenna 2101 and a radio frequency unit 2102. Optionally, the transceiver unit 2100 may include a receiving unit and a sending unit. The receiving unit may correspond to a receiver (or referred to as a receiver circuit), and the sending unit may correspond to a transmitter (or referred to as a transmitter circuit). The RRU2100 is mainly configured to send and receive radio frequency signals, and perform conversion between radio frequency signals and baseband signals. The BBU2200 is mainly configured to perform baseband processing, control the base station, etc. The RRU2100 and the BBU2200 may be physically co-located or physically separated, i.e., the base station is a distributed base station.

[0224] The BBU 2200 is a control center of the base station and may also be called a processing unit. The BBU 2200 may correspond to the processing unit 1200 in FIG. 5 and is mainly configured to perform baseband processing functions, such as channel coding, multiplexing, modulation, or spreading. For example, the BBU (processing unit) may be configured to control the base station to execute operation procedures related to the access network device in the above method embodiment.

[0225] In one example, the BBU2200 may include one or more boards, and the multiple boards may jointly support a radio access network having a single access standard (e.g., an LTE network) or separately support radio access networks having different access standards (e.g., an LTE network, a 5G network, or another network). The BBU2200 further includes a memory 2201 and a processor 2202. The memory 2201 is configured to store necessary instructions and data. The processor 2202 is configured to control the base station to perform necessary actions, for example, to control the base station to perform operation procedures related to the access network device in the above method embodiment. The memory 2201 and the processor 2202 may be responsible for one or more boards. In other words, the memory and the processor may be separately disposed on each board. Alternatively, the multiple boards may share the same memory and processor. In addition, necessary circuits may be further disposed on each board.

[0226] It should be understood that the base station 2000 shown in Fig. 6 can implement the processes related to the first access network device or the second access network device in the above method embodiments. The operation or function of the module in the base station 2000 is separately used to implement the corresponding procedure in the above method embodiments. For details, please refer to the description in the above method embodiments. In order to avoid repetition, detailed description is omitted in this specification appropriately.

[0227] The BBU2200 may be configured to perform the actions implemented inside the first access network device or the second access network device in the above method embodiments, and the RRU2100 may be configured to perform the sending or receiving actions performed by the first access network device or the second access network device in the above method embodiments. For details, please refer to the descriptions in the above method embodiments. The details will not be described again in this specification.

[0228] 7 is a schematic diagram of a structure of a communication device 3000 according to an embodiment of the present application. As shown in FIG. 7, the communication device 3000 includes a processor 3001 and a transceiver 3002. Optionally, the communication device 3000 may further include a memory 3003. The processor 3001, the transceiver 3002, and the memory 3003 may communicate with each other through an internal connection path to convey control signals and / or data signals. The memory 3003 is configured to store a computer program, and the processor 3001 is configured to call the computer program from the memory 3003 and execute the computer program to implement the above method embodiments.

[0229] The processor 3001 and the memory 3003 may be integrated into a processing unit. It should be understood that the memory 3003 may alternatively be integrated into the processor 3001 or may be separate from the processor 3001. This is not a limitation in the present application.

[0230] In one implementation, the communication device 3000 is configured to perform the actions performed by the first core network device in the above method embodiment. In this case, the execution of the program stored in the memory 3003 enables the processor 3001 to be configured to perform the internal processing operation (e.g., the determining step) on the first core network device side in the above method embodiment, and the execution of the program stored in the memory 3003 enables the processor 3001 to control the transceiver 3002 to perform the receiving step and the sending step on the first core network device side in the above method embodiment.

[0231] In one implementation, the communication device 3000 is configured to perform the actions performed by the second core network device in the above method embodiment. In this case, the execution of the program stored in the memory 3003 enables the processor 3001 to be configured to perform the internal processing operation (e.g., the determining step) on the second core network device side in the above method embodiment, and the execution of the program stored in the memory 3003 enables the processor 3001 to control the transceiver 3002 to perform the receiving step and the sending step on the second core network device side in the above method embodiment.

[0232] It should be understood that the processing device or processor may be a chip. For example, the processing device or processor may be a field programmable gate array (FPGA), a general-purpose processor, a digital signal processor (DSP), an application specific integrated circuit (ASIC), a field programmable gate array (FPGA), another programmable logic device, a discrete gate, a transistor logic device, or a discrete hardware component, a system on chip (SoC), a central processor unit (CPU), a network processor (NP), a digital signal processor (DSP), a micro controller unit (MCU), or a programmable logic device (PLD) or another integrated chip. The general-purpose processor may be a microprocessor, or the processor may be any conventional processor, etc. The steps of the method disclosed in relation to the embodiments of the present application may be directly performed and completed by using a hardware decoding processor, or may be performed and completed by using a combination of hardware and software modules in the decoding processor. The software modules may be located in a storage medium well developed in the art, such as a random access memory, a flash memory, a read-only memory, a programmable read-only memory, an electrically erasable programmable memory, or a register. The storage medium is located in the memory, and the processor reads the information in the memory and completes the steps of the above method in combination with the hardware of the processor.

[0233] The memory 3003 may be volatile or nonvolatile memory, or may include volatile and nonvolatile memory. The nonvolatile memory may be read-only memory (ROM), programmable read-only memory (PROM), erasable programmable read-only memory (EPROM), electrically erasable programmable read-only memory (EEPROM), or flash memory. The volatile memory may be random access memory (RAM) used as an external cache. By way of example and not limitation, many forms of RAM are available, such as static random access memory (static RAM, SRAM), dynamic random access memory (dynamic RAM, DRAM), synchronous dynamic random access memory (synchronous DRAM, SDRAM), double data rate synchronous dynamic random access memory (double data rate SDRAM, DDR SDRAM), enhanced synchronous dynamic random access memory (enhanced SDRAM, ESDRAM), synchlink dynamic random access memory (synchlink DRAM, SLDRAM), and direct rambus random access memory (direct rambus RAM, DR RAM).

[0234] It should be noted that the memories in the systems and methods described herein are intended to include, without being limited to, these and any other suitable types of memories.

[0235] The present application further provides a computer program product, which includes computer program code, which, when executed on a computer, enables the computer to execute the method performed by the first access network device, the second access network device, the first core network device, or the second core network device in the above method embodiments.

[0236] The present application further provides a computer-readable medium, which stores a program code, which, when executed on a computer, enables the computer to execute the method executed by the first access network device, the second access network device, the first core network device, or the second core network device in the above method embodiments.

[0237] The present application further provides a system including at least two of a first access network device, a second access network device, a first core network device, and a second core network device.

[0238] An embodiment of the present application further provides a processing device including a processor and an interface, the processor being configured to execute the method performed by the first access network device, the second access network device, the first core network device, or the second core network device in any one of the above method embodiments.

[0239] All or part of the above embodiments may be implemented by using software, hardware, firmware, or any combination thereof. When software is used to implement the embodiments, all or part of the embodiments may be implemented in the form of a computer program product. The computer program product includes one or more computer instructions. When the computer instructions are loaded and executed on a computer, the procedures or functions according to the embodiments of the present application are generated in whole or in part. The computer may be a general-purpose computer, a special-purpose computer, a computer network, or another programmable device. The computer instructions may be stored in a computer-readable storage medium or transmitted from a computer-readable storage medium to another computer-readable storage medium. For example, the computer instructions may be transmitted from a website, computer, server, or data center to another website, computer, server, or data center in a wired (e.g., coaxial cable, optical fiber, or digital subscriber line (DSL)) or wireless (e.g., infrared, radio, or microwave) manner. The computer-readable storage medium may be any available medium accessible by a computer, or a data storage device such as a server or data center that integrates one or more available media. The usable media may be magnetic media (e.g., a floppy disk, hard disk, or magnetic tape), optical media (e.g., a high density digital video disc (DVD)), semiconductor media (e.g., a solid state disc (SSD)), and the like.

[0240] As used herein, terms such as "component," "module," and "system" are used to indicate computer-related entities, hardware, firmware, a combination of hardware and software, software, or software in execution. For example, a component may be, but is not limited to, a process running on a processor, a processor, an object, an executable file, a thread of execution, a program, or a computer. As illustrated by the use of diagrams, both computing devices and applications running on computing devices may be components. One or more components may reside within a process or thread of execution, and a component may be located on one computer or distributed among two or more computers. Additionally, these components may be executed by various computer-readable media that store various data structures. For example, components may communicate by using local or remote processes based on signals having one or more data packets (e.g., data from two components interacting with another component in a local system, in a distributed system, or across a network such as the Internet that interacts with another system by using signals).

[0241] It should be understood that the term "embodiment" as used throughout this specification means that the particular feature, structure, or characteristic associated with this embodiment is included in at least one embodiment of the present application. Thus, the embodiments throughout this specification do not necessarily refer to the same embodiment. In addition, the particular features, structures, or characteristics may be combined in any suitable manner in one or more embodiments.

[0242] It should be understood that in the embodiments of the present application, the numbers "first", "second", etc. are merely used to distinguish between different objects, for example, between different network devices, and do not constitute limitations on the scope of the embodiments of the present application. The embodiments of the present application are not limited thereto.

[0243] It should be further understood that, in this application, both "when" and "if" mean that the network element executes the corresponding processing in a target situation, but do not imply any limitation on time, do not require the network element to have a decision action during implementation, and do not imply any other limitation.

[0244] It should be further understood that, as used in this application, "at least one" means one or more, and "plurality" means two or more.

[0245] It should be further understood that in the embodiment of the present application, "B corresponding to A" indicates that B is related to A and B can be determined based on A. However, it should be further understood that determining B based on A does not mean that B is determined based only on A. That is, B may alternatively be determined based on A and / or other information.

[0246] It should be further understood that the term "and / or" in this specification describes only an association relationship between related objects, and represents that three relationships may exist. For example, A and / or B may represent the following three cases: only A is present, both A and B are present, and only B is present. In addition, the character " / " in this specification generally indicates an "or" relationship between related objects.

[0247] Unless otherwise specified, expressions in this application similar to the expression "the item includes one or more of the following: A, B, and C" usually mean that the item may be any one of the following cases: "A", "B", "C", "A and B", "A and C", "B and C", "A, B, and C", "A and A", "A, A, and A", "A, A, and B", "A, A, and C", "A, B, and B", "A, C, and C", "B and B", "B, B, and B", "B, B, and C", "C and C", "C, C, and C", and other combinations of A, B, and C. In the above description, the three elements A, B, and C are used as an example to explain optional cases of the item. When the expression is "the item includes at least one of the following: A, B, ..., X", in other words, when more elements are included in the expression, the cases to which the item is applicable can also be obtained according to the above rules.

[0248] It may be understood that in the embodiments of the present application, the terminal device and / or the network device may perform some or all of the steps in the embodiments of the present application. These steps or operations are merely examples. In the embodiments of the present application, other operations or variations of various operations may be further performed. In addition, steps may be performed in a sequence different from the sequence presented in the embodiments of the present application, and not all operations in the embodiments of the present application may necessarily be performed.

[0249] In combination with the examples described in the embodiments disclosed herein, those skilled in the art may be aware that the units and algorithm steps can be implemented by electronic hardware, or a combination of computer software and electronic hardware. Whether a function is performed by hardware or software depends on the specific application and design constraints of the technical solution. Those skilled in the art may use different methods to implement the described functions for each specific application, but the implementation form should not be considered as going beyond the scope of this application.

[0250] For the purpose of convenient and concise description, the detailed work processes of the above systems, devices and units may be clearly understood by those skilled in the art by referring to the corresponding processes in the above method embodiments, and the details will not be described again in this specification.

[0251] In some embodiments provided in the present application, it should be understood that the disclosed system, device, and method may be implemented in other manners. For example, the device embodiment described above is only an example. For example, the division into units is only a logical functional division, and may be other divisions in actual implementation. For example, multiple units or components may be combined or integrated into another system, or some features may be ignored or not implemented. In addition, the shown or described mutual couplings or direct couplings or communication connections may be implemented through some interfaces. Indirect couplings or communication connections between devices or units may be implemented in electrical, mechanical, or other forms.

[0252] The units described as separate parts may or may not be physically separate, and the parts shown as units may or may not be physical units, i.e., they may be located in one location or distributed over multiple network units. Some or all of the units may be selected based on the actual requirements to achieve the objectives of the solutions in the embodiments.

[0253] In addition, the functional units in the embodiments of the present application may be integrated into one processing unit, each of the units may exist physically alone, or two or more units may be integrated into one unit.

[0254] When the function is implemented in the form of a software functional unit and sold or used as an independent product, the function may be stored in a computer-readable storage medium. Based on such understanding, the technical solutions in the present application may be essentially implemented in the form of a software product, or the part that contributes to the prior art, or some of the technical solutions. The computer software product is stored in a storage medium and includes some instructions for instructing a computer device (which may be a personal computer, a server, a network device, etc.) to execute all or part of the steps of the method in the embodiments of the present application. The above storage medium includes any medium that can store program code, such as a USB flash drive, a removable hard disk, a read-only memory ROM, a random access memory RAM, a magnetic disk, or an optical disk.

[0255] The above description is only a specific implementation form of the present application, but the protection scope of the present application is not limited thereto. Any variation or replacement that is easily understood by a person skilled in the art within the technical scope disclosed in this application shall fall within the protection scope of the present application. Therefore, the protection scope of the present application shall be subject to the protection scope of the claims. [Explanation of symbols]

[0256] 1000 Communication Equipment 1100 Transceiver Unit 1200 Processing Units 2000 Access Network Devices 2100 Remote Radio Unit (RRU) 2101 Antenna 2102 Radio Frequency Unit 2200 Baseband Unit (BBU) 2201 Memory 2202 Processor 3000 Communication Equipment 3001 Processor 3002 Transceiver 3003 Memory

Claims

1. 1. A method for inter-system handover, comprising: receiving, by a first access network device, a handover request message from a first core network device of a first core network, the handover request message comprising an identification of a second access network device and an identification of a terminal device, the identification of the terminal device corresponding to the second access network device, and the identification of the second access network device indicating a secondary access network device to be added for the terminal device; sending, by the first access network device to the second access network device, a request message for adding the secondary access network device, the request message being usable for adding the second access network device as the secondary access network device of the terminal device and comprising the identification information of the terminal device; The first access network device provides the terminal device with a service for connecting to the first core network, and the second access network device provides the terminal device with a service for connecting to a second core network before serving as the secondary access network device of the terminal device. A method for inter-system handover.

2. The method of claim 1 , wherein the identification information of the terminal device is an identification information of the terminal device on an interface between the second access network device and a second core network device of the second core network.

3. The method of claim 1, wherein the identification information of the second access network device is identification information used when the second access network device provides the service for connecting to the second core network to the terminal device.

4. The method according to claim 1, further comprising the steps of: prior to the step of sending, by the first access network device, the request message for adding the secondary access network device to the second access network device; receiving, by the first access network device, a first mapping relationship from the second access network device, the first mapping relationship being a mapping relationship between an identification used when the second access network device provides the service for connecting to the first core network to the terminal device and the identification used when the second access network device provides the service for connecting to the second core network to the terminal device; determining, by the first access network device, that the secondary access network device to be added for the terminal device is the second access network device based on the identification information of the second access network device and the first mapping relationship; The method of claim 3, further comprising:

5. 1. A method for inter-system handover, comprising: sending a first message by a second access network device to a second core network device of a second core network, the first message comprising an identification of the second access network device and an identification of a terminal device, the identification of the terminal device corresponding to the second access network device, the identification of the second access network device indicating a secondary access network device to be added for the terminal device, the first message being usable to request the first access network device to allocate resources to the terminal device; receiving, by the second access network device from the first access network device, a request message for adding the secondary access network device, wherein the first access network device provides a service for connecting to a first core network to the terminal device, the request message for adding the secondary access network device comprises the identification information of the terminal device, the request message for adding the secondary access network device is usable to request adding the second access network device as the secondary access network device of the terminal device, and the second access network device provides the terminal device with a service for connecting to the second core network before serving as the secondary access network device of the terminal device. A method for inter-system handover.

6. The method of claim 5, wherein the identification information of the terminal device is an identification information of the terminal device on an interface between the second access network device and the second core network device.

7. The method of claim 5, wherein the identification information of the second access network device is identification information used when the second access network device provides the service for connecting to the second core network to the terminal device.

8. The method according to claim 7, further comprising the steps of: prior to the step of receiving, by the second access network device from the first access network device, the request message for adding the secondary access network device; The method further comprises a step of sending a first mapping relationship by the second access network device to the first access network device, the first mapping relationship being a mapping relationship between an identification used when the second access network device provides the service for connecting to the first core network to the terminal device and the identification used when the second access network device provides the service for connecting to the second core network to the terminal device. The method of claim 7.

9. sending, by the second access network device, to the first access network device, data corresponding to bearers terminated at the first access network device; 9. The method of claim 5, further comprising:

10. skipping, by the second access network device, forwarding of data corresponding to bearers terminated at the second access network device via any one of the first core network, the second core network, and the first access network device to the second access network device.

10. The method of claim 5, further comprising:

11. Mapping, by the second access network device, a data packet of a quality of service QoS flow received from the second core network device to a data radio bearer DRB corresponding to an evolved universal terrestrial radio access network radio access bearer E-RAB applicable after handover according to a mapping relationship between the QoS flow and the E-RAB; and sending the data packet to the terminal device.

11. The method of claim 5, further comprising:

12. 1. A method for inter-system handover, comprising: receiving, by a first core network device of a first core network, a message from a second core network device of a second core network, the message comprising an identification of a second access network device and an identification of a terminal device, the identification of the terminal device corresponding to the second access network device, and the identification of the second access network device indicating a secondary access network device to be added for the terminal device; sending a handover request message by the first core network device to a first access network device, the handover request message comprising the identification information of the second access network device and the identification information of the terminal device; Equipped with The first access network device provides the terminal device with a service for connecting to the first core network, and the second access network device provides the terminal device with a service for connecting to the second core network before serving as the secondary access network device of the terminal device. A method for inter-system handover.

13. 1. A method for inter-system handover, comprising: sending a first message by a second access network device to a second core network device of a second core network, the first message comprising an identification of the second access network device and an identification of a terminal device, the identification of the terminal device corresponding to the second access network device, the identification of the second access network device indicating a secondary access network device to be added for the terminal device, the first message being usable to request the first access network device to allocate resources to the terminal device; receiving the first message by the second core network device; sending, by the second core network device, a second message to a first core network device of a first core network, the second message comprising the identity of the second access network device and the identity of the terminal device; receiving the second message by the first core network device; sending a handover request message by the first core network device to the first access network device, the handover request message comprising the identification information of the terminal device; sending, by the first access network device to the second access network device, a request message for adding the secondary access network device, the request message being usable for adding the second access network device as the secondary access network device of the terminal device and comprising the identification information of the terminal device; The first access network device provides the terminal device with a service for connecting to the first core network, and the second access network device provides the terminal device with a service for connecting to a second core network before serving as the secondary access network device of the terminal device. A method for inter-system handover.

14. A communications apparatus for a first access network device, comprising: a receiving unit configured to receive a handover request message from a first core network device of a first core network, the handover request message comprising an identification information of a second access network device and an identification information of a terminal device, the identification information of the terminal device corresponding to a second access network device, and the identification information of the second access network device indicating a secondary access network device to be added for the terminal device; a sending unit configured to send a request message for adding the secondary access network device to the second access network device, the request message being usable for adding the second access network device as the secondary access network device of the terminal device and comprising the identification information of the terminal device; The first access network device provides the terminal device with a service for connecting to the first core network, and the second access network device provides the terminal device with a service for connecting to a second core network before serving as the secondary access network device of the terminal device. Communications equipment.

15. The apparatus of claim 14, wherein the identification information of the terminal device is an identification information of the terminal device on an interface between the second access network device and a second core network device of the second core network.

16. The apparatus of claim 14, wherein the identification information of the second access network device is identification information used when the second access network device provides the service for connecting to the second core network to the terminal device.

17. The receiving unit: The method is further configured to receive a first mapping relationship from the second access network device, the first mapping relationship being a mapping relationship between an identification used when the second access network device provides the service for connecting to the first core network to the terminal device and the identification used when the second access network device provides the service for connecting to the second core network to the terminal device; The apparatus further comprises a processing unit, the processing unit comprising: configured to determine that the secondary access network device to be added for the terminal device is the second access network device based on the identification information of the second access network device and the first mapping relationship; 17. The apparatus of claim 16.

18. A communications apparatus for a second access network device, comprising: a sending unit configured to send a first message to a second core network device of a second core network, the first message comprising an identification of the second access network device and an identification of a terminal device, the identification of the second access network device indicating a secondary access network device to be added for the terminal device, the identification of the terminal device corresponding to the second access network device, and the first message usable to request the first access network device to allocate resources to the terminal device; a receiving unit configured to receive a request message for adding the secondary access network device from the first access network device, the first access network device providing a service for connecting to a first core network to the terminal device, the request message for adding the secondary access network device comprising the identification information of the terminal device, the request message for adding the secondary access network device being usable to request adding the second access network device as the secondary access network device of the terminal device, and the second access network device providing a service for connecting to the second core network to the terminal device before serving as the secondary access network device of the terminal device; A communication device comprising:

19. The apparatus of claim 18, wherein the identification information of the terminal device is an identification information of the terminal device on an interface between the second access network device and the second core network device.

20. The apparatus of claim 18, wherein the identification information of the second access network device is identification information used when the second access network device provides the service for connecting to the second core network to the terminal device.

21. The sending unit is further configured to send a first mapping relationship to the first access network device, the first mapping relationship being a mapping relationship between an identification used when the second access network device provides the service for connecting to the first core network to the terminal device and the identification used when the second access network device provides the service for connecting to the second core network to the terminal device.

21. The apparatus of claim 20.

22. The delivery unit comprises: and further configured to send data corresponding to the bearer terminated at the first access network device to the first access network device.

22. Apparatus according to any one of claims 18 to 21.

23. and a processing unit configured to skip forwarding data corresponding to a bearer terminated at the second access network device to the second access network device via any one of the first core network, the second core network, and the first access network device.

23. Apparatus according to any one of claims 18 to 22.

24. The apparatus according to any one of claims 18 to 23, further comprising a processing unit configured to map data packets belonging to a quality of service QoS flow and received from the second core network device to a data radio bearer DRB corresponding to an evolved universal terrestrial radio access network radio access bearer E-RAB applicable after handover based on a mapping relationship between the QoS flow and the E-RAB, and send the data packets to the terminal device.

25. A communication device for a first core network device, the first core network device belonging to a first core network, the communication device comprising: a receiving unit configured to receive a message from a second core network device of a second core network, the message comprising an identification of a second access network device and an identification of a terminal device, the identification of the terminal device corresponding to the second access network device, and the identification of the second access network device indicating a secondary access network device to be added for the terminal device; a sending unit configured to send a handover request message to a first access network device, the handover request message comprising the identification information of the second access network device and the identification information of the terminal device; The first access network device provides the terminal device with a service for connecting to the first core network, and the second access network device provides the terminal device with a service for connecting to the second core network before serving as the secondary access network device of the terminal device. Communications equipment.

26. A communications device comprising a memory and a processor, the memory storing a program to be executed on the processor, the processor performing a method according to any one of claims 1 to 4 or claims 5 to 11 when the program is executed.

27. A communications device comprising a memory and a processor, the memory storing a program for execution on the processor, the program, when executed, causing the processor to implement the method of claim 12.

28. A communication system comprising a first access network device and a first core network device, wherein the first access network device performs the method of any one of claims 1 to 4 and the first core network device performs the method of claim 12.

29. 29. The system of claim 28, further comprising a second access network device, said second access network device performing the communication method of any one of claims 5 to 11.

30. 12. A computer readable storage medium having a computer program stored therein, the computer program being capable of performing the communication method according to any one of claims 1 to 11 when executed.

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