A communication method and device

Abstract

The embodiments of the present application relate to the field of communication technology, and in particular to a communication method and device for improving the reliability of downlink data received by a terminal in the process of switching access network devices and reducing latency. The scheme includes: a source access network device sends a first data packet of a terminal to a target access network device; when the source access network device determines that the target access network device has received the first data packet, the source access network device sends a first message to the terminal, and the first message is used to instruct the terminal to switch to the target access network device.

Description

[0001] This application is a divisional application. The application number of the original application is 201811379025.1, and the original application date is November 19, 2018. The entire contents of the original application are incorporated into this application by reference. Technical Field

[0002] The embodiments of the present application relate to the field of communication technology, and in particular, to a communication method and device. Background Art

[0003] To ensure service continuity, for example, when a terminal moves from the coverage of a source base station to the coverage of a target base station, the source base station may switch the terminal to the target base station so that the target base station provides services for the terminal.

[0004] Usually, before the terminal successfully switches from the source base station to the target base station, the source base station will still send downlink data packets to the terminal. However, in the existing switching process, the signal quality of the air interface may be very poor, and the reliability of the downlink data packets received before the terminal successfully switches to the target base station cannot be guaranteed. Furthermore, in the existing switching process, the source base station starts to send the downlink data packets of the terminal to the target base station after sending the switching command to the terminal. This may result in the target base station being unable to immediately send downlink data packets to the terminal when the terminal is synchronized to the target base station because it has not received the downlink data packets of the terminal from the source base station, thereby causing a large switching delay.

[0005] For example, the 5G system needs to provide a service that supports Ultra Reliable and Low Latency munications (URLLC). In order to ensure the URLLC service, the switching process also needs to ensure high reliability and low latency. Therefore, the switching process in the prior art cannot meet the high reliability and low latency requirements of the URLLC service. Summary of the invention

[0006] The embodiments of the present application provide a communication method and apparatus for improving the reliability of downlink data received by a terminal during a process of switching access network devices and reducing latency.

[0007] In order to achieve the above objectives, the present application provides the following technical solutions:

[0008] In a first aspect, an embodiment of the present application provides a communication method, including: a source access network device sends a first data packet sent to a terminal to a target access network device. When the source access network device determines that the target access network device has received the first data packet, the source access network device sends a first message to the terminal for instructing the terminal to switch to the target access network device.

[0009] The embodiment of the present application provides a communication method, because in the process of switching the terminal to the target access network device (that is, before the source access network device sends the first message to the terminal), the source access network device still needs to send the first data packet to the terminal. If the signal quality of the air interface is poor during the switching process, the terminal may not receive the first data packet. Therefore, the first data packet is sent to the target access network device by the source access network device, so that when the source access network device determines that the target access network device has received the first data packet, it sends a first message to the terminal indicating that the terminal has switched to the target access network device. On the one hand, the first data packet can be provided at the target access network device. On the other hand, after determining that the target access network device has received the first data packet, the first message is sent to the terminal again, so that after the terminal successfully switches from the source access network device to the target access network device, the target access network device will send the first data packet to the terminal again. In this way, it can be ensured that the terminal can obtain the first data packet from the target access network device when it cannot receive the first data packet from the source access network device during the switching process, thereby ensuring the reliability of data transmission. In addition, since the data packet sent by the source access network device to the target access network device is before the switching command is sent to the terminal, the delay can be further reduced compared with the prior art in which the terminal data packet is sent to the target access network device only after the switching command is sent to the terminal.

[0010] In a possible implementation, the method provided in the embodiment of the present application further includes: the source access network device receives first information from the target access network device for indicating that the terminal is allowed to switch to the target access network device, and the source access network device sends a first data packet to the target access network device. That is, the source access network device receives the first information allowing the switch, and the source access network device sends the first data packet to the target access network device.

[0011] In a possible implementation, before the source access network device sends the first data packet to the target access network device, the method provided in the embodiment of the present application further includes: the source access network device determines, based on the first information, that the target access network device allows the terminal to switch to the target access network device. In this way, when the source access network device determines that the target access network device agrees to switch, it starts to send the first data packet, which can avoid the waste of air interface resources caused by blindly sending the first data packet because the target access network device does not agree to switch.

[0012] In one possible implementation, the first data packet includes a duplicate data packet, and the method provided in the embodiment of the present application further includes: the source access network device obtains the duplicate data packet; or, when the conditions for switching the access network device for the terminal are met, the source access network device obtains the duplicate data packet.

[0013] In a possible implementation, the source access network device obtains a duplicate data packet, including: the source access network device duplicates a data packet that meets a preset condition in a data packet of a terminal to obtain a duplicate data packet. The data packet that meets the preset condition includes at least one of the following: a data packet using a preset quality of service QoS flow, a data packet on a preset packet data unit PDU session, a data packet with a packet loss rate less than or equal to a preset threshold value, or a data packet on a preset radio bearer. In this way, the data packet to be duplicated can be selected according to the preset condition to first ensure the reliability of the data packet that meets the preset condition.

[0014] In a possible implementation manner, the source access network device obtains the duplicate data packet, including: the source access network device duplicates the data packet of the terminal to obtain the duplicate data packet.

[0015] In a possible implementation, the method provided by the embodiment of the present application also includes: the source access network device determines that the conditions for switching the access network device for the terminal are met, and the source access network device performs the above-mentioned copying step.

[0016] In a possible implementation, the method provided in the embodiment of the present application further includes: the source access network device sends sequence number SN status information to the target access network device, and the SN status information is used by the target access network device to send a data packet to the terminal. By sending the SN status information, the target access network device is facilitated to set the SN of the data packet.

[0017] In one possible implementation, the source access network device determines that the target access network device has received the first data packet, including: the source access network device receives a second message sent by the target access network device, the second message is used to indicate that the target access network device has received the first data packet; or, the source access network device determines that the target access network device has received the first data packet based on delay information.

[0018] In a possible implementation, the method provided in the embodiment of the present application also includes: the source access network device determines the delay information based on the QoS information of the first data packet; or, the source access network device obtains the delay information from the session management function.

[0019] In a second aspect, an embodiment of the present application provides a communication method, including: a target access network device sends a first information to a source access network device to indicate that a terminal is allowed to switch to the target access network device; the target access network device receives a first data packet from the terminal of the source access network device; when the terminal successfully switches from the source access network device to the target access network device, the target access network device sends a first data packet to the terminal.

[0020] In a possible implementation manner, the method provided by the embodiment of the present application also includes: the target access network device sends a second message to the source access network device to indicate that the target access network device has received the first data packet.

[0021] In a possible implementation, the method provided by the embodiment of the present application further includes: the target access network device receives the sequence number SN status information from the source access network device, and the SN status information is used by the target access network device to send a data packet to the terminal; the target access network device obtains a second data packet based on the SN status information and processes the data packet from the source access network device that does not carry the SN; the data packet that does not carry the SN is a data packet in the first data packet or a data packet of the terminal in the source access network device; the target access network device sends the second data packet to the terminal. The SN of the second data packet is determined according to the SN status information.

[0022] In a third aspect, an embodiment of the present application provides a communication device, which can implement a communication method described in the first aspect or any possible implementation of the first aspect, and thus can also achieve the beneficial effects of the first aspect or any possible implementation of the first aspect. The communication device can be a source access network device, or a device that can support the source access network device to implement the first aspect or any possible implementation of the first aspect. For example, a chip used in a source access network device. The communication device can implement the above method through software, hardware, or by executing corresponding software through hardware.

[0023] In one example, the communication device includes: a sending unit and a processing unit. The sending unit is used to send a first data packet of the terminal to the target access network device. The sending unit is also used to send a first message to the terminal for instructing the terminal to switch to the target access network device when the processing unit determines that the target access network device has received the first data packet.

[0024] In a possible implementation, the communication device also includes: a receiving unit, used to receive first information from the target access network device to indicate that the terminal is allowed to switch to the target access network device; and a sending unit, also used to send a first data packet of the terminal to the target access network device.

[0025] In a possible implementation, the first data packet includes a duplicate data packet, and the processing unit is further configured to obtain the duplicate data packet; or the processing unit is further configured to obtain the duplicate data packet when a condition for switching an access network device for the terminal is met.

[0026] In a possible implementation, the processing unit is further specifically configured to copy a data packet that meets a preset condition in the data packet of the terminal to obtain a copied data packet. The data packet that meets the preset condition includes at least one of the following: a data packet using a preset quality of service QoS flow, a data packet on a preset packet data unit PDU session, a data packet with a packet loss rate less than or equal to a preset threshold value, or a data packet on a preset radio bearer.

[0027] In a possible implementation, the processing unit is further configured to copy the data packet of the terminal to obtain a copied data packet.

[0028] In a possible implementation, the processing unit is further configured to determine that a condition for switching the access network device for the terminal is met and execute the above-mentioned copying step.

[0029] In a possible implementation, the sending unit is further used to send sequence number SN status information to the target access network device, and the SN status information is used by the target access network device to send a data packet to the terminal.

[0030] In a possible implementation, the receiving unit is used to receive a second message sent by the target access network device to indicate that the target access network device has received the first data packet, and the receiving unit is specifically used to determine that the target access network device has received the first data packet according to the second message. Alternatively, the processing unit is used to determine that the target access network device has received the first data packet according to the delay information. In this way, it is convenient for the source access network device to determine that the target access network device has received the first data packet through multiple ways.

[0031] In a possible implementation manner, the processing unit is further configured to determine delay information according to QoS information of the first data packet; or the processing unit is further configured to obtain delay information from a session management function network element.

[0032] As another example, an embodiment of the present application also provides a communication device, which may be a source access network device or a chip used in a source access network device. The communication device includes: a communication interface and one or more processors.

[0033] The source access network device communicates with other devices through a communication interface. When one or more processors execute instructions, the source access network device executes the communication method described in the first aspect above.

[0034] For example, the communication interface is used to support the communication device to perform the steps of receiving and sending messages / data on the communication device side as described in the first aspect to any possible implementation of the first aspect. The processor is used to support the communication device to perform the steps of processing messages / data on the communication device side as described in the first aspect to any possible implementation of the first aspect. The specific corresponding steps can refer to the description in the first aspect to any possible implementation of the first aspect, and will not be repeated here.

[0035] Optionally, the communication interface and processor of the communication device are coupled to each other.

[0036] Optionally, the communication device may further include a memory for storing computer program codes, the computer program codes including instructions. Optionally, the processor, the communication interface and the memory are coupled to each other.

[0037] In a fourth aspect, an embodiment of the present application provides a communication device, which can implement a communication method described in the second aspect or any possible implementation of the second aspect, and thus can also achieve the beneficial effects of the second aspect or any possible implementation of the second aspect. The communication device can be a target access network device, or a device that can support the target access network device to implement the second aspect or any possible implementation of the second aspect. For example, a chip used in a target access network device. The communication device can implement the above method through software, hardware, or by executing corresponding software through hardware.

[0038] Exemplarily, a communication device includes: a sending unit, configured to send first information to a source access network device to indicate that a terminal is allowed to switch to a target access network device. A receiving unit, configured to receive a first data packet from the terminal of the source access network device. A sending unit, configured to send the first data packet to the terminal when the terminal successfully switches from the source access network device to the target access network device.

[0039] In a possible implementation manner, the sending unit is further configured to send a second message to the source access network device, which is used to indicate that the target access network device has received the first data packet.

[0040] In a possible implementation, the receiving unit is further used to receive the sequence number SN status information from the source access network device, and the SN status information is used by the target access network device to send a data packet to the terminal. The sending unit is further used to obtain a second data packet based on the SN status information and processing the data packet from the source access network device that does not carry the SN; the data packet that does not carry the SN is a data packet in the first data packet or a data packet of the terminal in the source access network device, and the sending unit is further used to send the second data packet to the terminal.

[0041] As another example, an embodiment of the present application also provides a communication device, which may be a target access network device or a chip used in the target access network device. The communication device includes: a communication interface and one or more processors.

[0042] The target access network device communicates with other devices through a communication interface. When one or more processors execute instructions, the target access network device executes the communication method described in the second aspect above.

[0043] For example, the communication interface is used to support the communication device to perform the steps of receiving and sending messages / data on the communication device side as described in the second aspect to any possible implementation of the second aspect. The processor is used to support the communication device to perform the steps of processing messages / data on the communication device side as described in the second aspect to any possible implementation of the second aspect. The specific corresponding steps can refer to the description in the second aspect to any possible implementation of the second aspect, and will not be repeated here.

[0044] Optionally, the communication interface and processor of the communication device are coupled to each other.

[0045] Optionally, the communication device may further include a memory for storing computer program codes, the computer program codes including instructions. Optionally, the processor, the communication interface and the memory are coupled to each other.

[0046] In a fifth aspect, an embodiment of the present application provides a computer-readable storage medium, which stores instructions. When the instructions are executed on a computer, the computer executes a communication method described in the first aspect or various possible implementations of the first aspect.

[0047] In a sixth aspect, the present application provides a computer-readable storage medium, which stores instructions. When the instructions are executed on a computer, the computer executes a communication method described in the second aspect or various possible implementations of the second aspect.

[0048] In a seventh aspect, the present application provides a computer program product comprising instructions, which, when executed on a computer, enables the computer to execute a communication method described in the first aspect or various possible implementations of the first aspect.

[0049] In an eighth aspect, the present application provides a computer program product comprising instructions, which, when executed on a computer, enables the computer to execute a communication method described in the second aspect or various possible implementations of the second aspect.

[0050] In a ninth aspect, an embodiment of the present application provides a chip, the chip comprising a processor and a communication interface, the communication interface and the processor are coupled, the processor is used to run a computer program or instruction to implement a communication method described in the first aspect or various possible implementations of the first aspect. The communication interface is used to communicate with other modules outside the chip.

[0051] In a tenth aspect, an embodiment of the present application provides a chip, the chip comprising a processor and a communication interface, the communication interface and the processor are coupled, the processor is used to run a computer program or instruction to implement a communication method described in the second aspect or various possible implementations of the second aspect. The communication interface is used to communicate with other modules outside the chip.

[0052] In the eleventh aspect, an embodiment of the present application provides a communication system, the method comprising: a source access network device described in the third aspect and various possible implementations of the third aspect, and a target access network device described in the fourth aspect and various possible implementations of the fourth aspect.

[0053] The beneficial effects of the second, third, fourth, fifth, sixth, seventh, eighth, ninth, tenth and eleventh aspects of this application and their various implementations can be referred to the beneficial effects analysis of the first aspect and its various implementations, and will not be repeated here. BRIEF DESCRIPTION OF THE DRAWINGS

[0054] Figure 1-Figure 4 A schematic diagram of a communication system provided in an embodiment of the present application;

[0055] Figure 5 A schematic diagram of a 5G communication system provided in an embodiment of the present application;

[0056] Figure 6 A schematic diagram of another 5G communication system provided in an embodiment of the present application;

[0057] Figure 7 A schematic diagram of the structure of a base station provided in an embodiment of the present application;

[0058] Figure 8 A schematic diagram of the structure of another base station provided in an embodiment of the present application;

[0059] Fig. 9 A schematic diagram of another communication system provided in an embodiment of the present application;

[0060] Fig.10 A schematic diagram of the structure of an access network device provided in an embodiment of the present application;

[0061] Fig.11A communication method according to an embodiment of the present invention is provided. Figure 1 ;

[0062] Fig.12 A schematic diagram of sending a data packet provided in an embodiment of the present application;

[0063] Fig.13 A communication method according to an embodiment of the present invention is provided. Figure 2 ;

[0064] Fig.14 A communication method according to an embodiment of the present invention is provided. Figure 3 ;

[0065] Fig.15 A communication method according to an embodiment of the present invention is provided. Figure 4 ;

[0066] Fig.16 A schematic diagram of a specific embodiment provided for the present application;

[0067] Fig.17 A flowchart of another specific embodiment provided for the embodiment of the present application;

[0068] Figure 18-Figure 21 A schematic diagram of the structure of a communication device provided in an embodiment of the present application;

[0069] Fig. 22 A schematic diagram of the structure of a chip provided in an embodiment of the present application. DETAILED DESCRIPTION

[0070] The technical solutions of the embodiments of the present application can be applied to various communication systems. For example: global system for mobile communication (GSM), evolved universal terrestrial radio access (E-UTRA) system, universal mobile telecommunications system (UMTS) and UMTS evolution version, long term evolution (LTE) and various versions based on LTE evolution, fifth generation (5th-generation, 5G) communication system, and new radio (NR) and other next generation communication systems. In addition, the above communication system can also be applied to future-oriented communication technologies, and the technical solutions provided by the embodiments of the present application are applicable.

[0071] It should be noted that in the embodiments of the present application, words such as "exemplary" or "for example" are used to indicate examples, illustrations or descriptions. Any embodiment or design described as "exemplary" or "for example" in the embodiments of the present application should not be interpreted as being more preferred or more advantageous than other embodiments or designs. Specifically, the use of words such as "exemplary" or "for example" is intended to present related concepts in a specific way.

[0072] In the present application, "at least one" means one or more, and "plurality" means two or more. "And / or" describes the association relationship of associated objects, indicating that three relationships may exist. For example, A and / or B can represent: A exists alone, A and B exist at the same time, and B exists alone, where A and B can be singular or plural. The character " / " generally indicates that the associated objects before and after are in an "or" relationship. "At least one of the following" or similar expressions refers to any combination of these items, including any combination of single items or plural items. For example, at least one of a, b, or c can represent: a, b, c, ab, ac, bc, or abc, where a, b, c can be single or multiple. In the embodiment of the present application, A or B can represent: A exists alone, A and B exist at the same time, and B exists alone, where A and B can be singular or plural.

[0073] In addition, in order to clearly describe the technical solutions of the embodiments of the present application, in the embodiments of the present application, words such as "first" and "second" are used to distinguish the same items or similar items with substantially the same functions and effects. Those skilled in the art can understand that words such as "first" and "second" do not limit the quantity and execution order, and words such as "first" and "second" do not necessarily limit the difference.

[0074] The system architecture and business scenarios described in the embodiments of the present application are intended to more clearly illustrate the technical solutions of the embodiments of the present application, and do not constitute a limitation on the technical solutions provided in the embodiments of the present application. A person of ordinary skill in the art can appreciate that with the evolution of network architecture and the emergence of new business scenarios, the technical solutions provided in the embodiments of the present application are also applicable to similar technical problems.

[0075] In the current 4G network, the evolved Node Base Station (eNB) in the LTE system (can be called LTE eNB) is connected to the 4G core network (e.g., Evolved Packet Core (EPC)) through the S1 interface, and different LTE eNBs are connected through the X2 interface. For example, Figure 1 LTE eNB1 and LTE eNB2 are connected via an X2 interface. Figure 1 The network architecture of the LTE system is shown, where the X2 interface supports direct transmission of data and signaling between two LTE eNBs.

[0076] Exemplarily, the X2 interface is also divided into two interfaces, for example, an X2-C interface and an X2-U interface. The X2-C interface is used for the control plane, and the X2-U interface is used for the user plane. The X2-C interface is used to transmit signaling between LTE eNBs. The X2-U interface is used to transmit data between LTE eNBs.

[0077] In LTE, terminals perform data transmission or signaling transmission with EPC through the LTE eNBs they access.

[0078] With the continuous development of mobile communication technology, 4G networks are gradually evolving towards 5G networks. During this evolution, LTE systems can evolve into eLTE systems.

[0079] In the eLTE system, the EPC network and the Next-Generation Core (NG-Core) network coexist. The eNB in ​​the eLTE system is called the eLTE eNB, and the terminal with the function of accessing the NG-Core network is called the next-generation terminal (for example, terminal 1 and terminal 2 in the figure). The eLTE eNB can access the EPC network and the NG-Core network. Terminal 1, which is wirelessly connected to the eLTE eNB, can access the EPC network and the NG-Core network through the eLTE eNB. Figure 2 As shown, the eLTE eNB is connected to the EPC network through the S1 interface, and can also be connected through other corresponding interfaces ( Figure 2 Terminal 1 connected to the eLTE eNB can access the EPC network through the eLTE eNB, and can also access the NG-Core network through the eLTE eNB. Terminals connected to the eLTE eNB can access the EPC network through the LTE eNB. Figure 2 NR gNB is used here to represent the base station that is only connected to the NG-Core network. LTE eNBs and eLTE eNBs are connected through the X2 interface, and eLTE eNBs and NR gNBs are connected through the Xn interface.

[0080] The core network equipment of the 4G network can interwork with the core network equipment of the 5G network. Figure 2 , Figure 3 It shows the composition structure of each device in the communication system of the 5G network in the scenario where the core network device of the 4G network communicates with the core network device of the 5G network.

[0081] The core network equipment has user plane functions and control plane functions. Generally, a user plane network element is used to represent a device that can implement the user plane function of the core network equipment, and a control plane network element is used to represent a device that can implement the control plane function of the core network equipment. The user plane network element and the control plane network element can be integrated into the same device or set independently. The embodiment of the present application is described by taking the user plane network element and the control plane network element as an example.

[0082] exist Figure 3 In the 4G network, the Home Subscriber Server (HSS) of the 4G network and the Unified Data Management (UDM) network element of the 5G network are integrated in the same device, the control plane PGW-C network element of the Public Data Network Gateway (PGW) of the 4G network and the Session Management Function (SMF) network element of the 5G network are integrated in the same device, and the PGW-U network element of the 4G network and the User Plane Function (UPF) network element of the 5G network are integrated in the same device. Figure 3 The Mobility Management Entity (MME) in the 4G network is the control plane network element, and the MME is connected to the LTE eNB through the S1-MME interface. The Core Access and Mobility Management Function (AMF) network element is the control plane network element in the 5G network. The AMF network element is connected to the NR gNB / eLTE eNB through the N2 interface and to the terminal 3 through the N1 interface. The MME and AMF network elements can be connected through the Nx interface, or the Nx interface may not exist. Therefore, Figure 3 The dashed line in the middle represents the Nx interface. In 5G, the AMF network element is connected to the PCF network element through the N15 interface, and the PGW-C network element and the SMF network element are connected to the PCF network element through the N7 interface. The Serving GateWay (SGW) is a device responsible for the routing and forwarding of data packets in the 4G network. In addition, Figure 3 Also shown are related interfaces such as S5-U, S5-C, S11, S1-U, S6a, N1, N2, N3, N4, N7, N8, N10, N11, and N15, which will not be described in detail here.

[0083] In the current 5G network, each Next Generation NodeB (gNB) in the NR system, referred to as NR gNB in ​​the embodiment of the present application, is connected to the NG-Core network through the N2 interface, and different NR gNBs are connected through the Xn interface, for example, gNB1 and gNB2 are connected through the Xn interface. Each NR gNB is connected to at least one terminal in the NR system. Figure 4 The network architecture of the NR system is shown. In practical applications, the connections between the above multiple devices are wireless connections. In order to conveniently and intuitively represent the connection relationship between the various devices, Figure 4 Solid lines are used to indicate this.

[0084] Among them, if Figure 4 The communication system shown is applied to a 5G network. Figure 5 As shown, the network element or entity corresponding to the gNB may be RAN, the network element included in the NG-Core network may be an SMF network element, an UPF network element, a policy control network element may be (Policy Control Function, PCF), an application function (Application Function, AF) network element, an authentication server function (Authentication Server Function, AUSF) network element, a UDM network element, a network capability opening function (Network Exposure Function, NEF) network element, a network repository storage function (Network Repository Function, NRF) network element, and a data network (Data Network, DN), a security anchor function (Security Anchor Function, SEAF) network element or a network slice selection function (Network Slice Selection Function, NSSF) network element, etc. The embodiment of the present application does not specifically limit this.

[0085] Among them, the terminal communicates with the AMF network element through the N1 interface (referred to as N1). The AMF network element communicates with the SMF network element through the N11 interface (referred to as N11). The SMF network element communicates with one or more UPF network elements through the N4 interface (referred to as N4). Any two UPF network elements among one or more UPF network elements communicate through the N9 interface (referred to as N9). The UPF network element communicates with the data network (DN) through the N6 interface (referred to as N6). The terminal accesses the network through the access network device (for example, RAN device). The access network device and the AMF network element communicate through the N2 interface (referred to as N2). The SMF network element communicates with the PCF network element through the N7 interface (referred to as N7), and the PCF network element communicates with the AF network element through the N5 interface. The access network device communicates with the UPF network element through the N3 interface (referred to as N3). Any two or more AMF network elements communicate through the N14 interface (referred to as N14). The SMF network element communicates with the UDM network element through the N10 interface (referred to as N10). The AMF network element communicates with the AUSF network element through the N12 interface (referred to as N12). The AUSF network element communicates with the UDM network element through the N13 interface (referred to as N13). The AMF network element communicates with the UDM network element through the N8 interface (referred to as N8).

[0086] It should be noted that Figure 5 The interface name between the network elements in the example is just an example. In a specific implementation, the interface name may be other names, and the embodiments of the present application do not specifically limit this.

[0087] It should be noted that Figure 5 The access network equipment, AF network element, AMF network element, SMF network element, AUSF network element, UDM network element, UPF network element and PCF network element are just names, and the names do not limit the equipment itself. In 5G networks and other future networks, the network elements corresponding to the access network equipment, AF network element, AMF network element, SMF network element, AUSF network element, UDM network element, UPF network element and PCF network element may also be other names, and the embodiments of the present application do not make specific limitations on this. For example, the UDM network element may also be replaced by HSS or user subscription database (USD) or database entity, etc., which are uniformly explained here and will not be repeated later.

[0088] Figure 6 The 5G network of non-roaming architecture based on service-oriented interface is shown. Of course, the 5G network can also adopt Figure 6 As shown, a non-roaming architecture based on reference points.

[0089] Among them, AMF network element: belongs to the core network element, mainly responsible for signaling processing, such as access control, mobility management, attachment and detachment, and gateway selection. When the AMF network element provides services for the session in the terminal, it will provide control plane storage resources for the session to store the session identifier, the SMF network element identifier associated with the session identifier, etc.

[0090] (Radio) Access Network (R)AN) equipment: includes RAN equipment and AN equipment. RAN equipment is mainly the wireless network equipment of the 3rd Generation Partnership Project (3GPP) network, and AN can be access network equipment defined by non-3GPP.

[0091] RAN equipment: mainly responsible for wireless resource management, quality of service (QoS) management, data compression and encryption and other functions on the air interface side. The access network equipment may include various forms of base stations, such as macro base stations, micro base stations (also known as small stations), relay stations, access points, etc. In systems using different wireless access technologies, the names of devices with base station functions may be different. For example, in the fifth generation (5th generation, 5G) system, it is called RAN. In the LTE system, it is called evolved NodeB (eNB or eNodeB). In the third generation (3rd generation, 3G) system, it is called Node B, etc.

[0092] AN equipment: allows the terminals and 3GPP core network to interconnect with each other using non-3GPP technologies, such as Wireless Fidelity (Wi-Fi), Worldwide Interoperability for Microwave Access (WiMAX), Code Division Multiple Access (CDMA) networks, etc.

[0093] SMF network element: responsible for user plane network element selection, user plane network element redirection, Internet protocol (IP) address allocation, bearer establishment, modification and release, and QoS control.

[0094] UPF network element: responsible for forwarding and receiving user data in the terminal. It can receive user data from the data network and transmit it to the terminal through the access network equipment. The UPF network element can also receive user data from the terminal through the access network equipment and forward it to the data network. The transmission resources and scheduling functions that provide services to the terminal in the UPF network element are managed and controlled by the SMF network element.

[0095] PCF network element: mainly supports providing a unified policy framework to control network behavior, provides policy rules to the control layer network functions, and is responsible for obtaining user contract information related to policy decisions.

[0096] AUSF network element: mainly provides authentication and authorization functions.

[0097] NEF network element: mainly supports the secure interaction between 3GPP network and third-party applications. NEF network element can safely open network capabilities and events to third parties to enhance or improve the quality of application services. 3GPP network can also securely obtain relevant data from third parties to enhance the network's intelligent decision-making. At the same time, the NEF network element supports the recovery of structured data from a unified database or the storage of structured data in a unified database.

[0098] Unified data repository (UDR): Mainly responsible for storing structured data, including contract data and policy data, externally exposed structured data and application-related data.

[0099] AF network element: mainly supports interaction with the 3GPP core network to provide services, such as influencing data routing decisions, policy control functions, or providing some third-party services to the network side.

[0100] The terminal in the embodiment of the present application may be a device that provides voice and / or data connectivity to a user, a handheld device with a wireless connection function, or other processing devices connected to a wireless modem. The wireless terminal may communicate with one or more core networks via the RAN. The wireless terminal may be a user equipment (UE), a handheld terminal, a laptop, a subscriber unit, a cellular phone, a smart phone, a wireless data card, a personal digital assistant (PDA) computer, a tablet computer, a wireless modem, a handheld device (handheld), a laptop computer, a cordless phone or a wireless local loop (WLL) station, a machine type communication (MTC) terminal or other device that can access the network. The terminal and the access network device communicate with each other using a certain air interface technology (for example, 3GPP access technology or non-3GPP access technology).

[0101] Since the access network in the future can be implemented using the cloud radio access network (C-RAN) architecture, one possible approach is to split the protocol stack architecture and functions of the traditional base station into two parts, one called the central unit (CU) and the other called the distributed unit (DU). The actual deployment of the CU and DU is relatively flexible. For example, the CU parts of multiple base stations can be integrated together to form a larger functional entity. Figure 7 As shown, it is a schematic diagram of a network architecture provided by an embodiment of the present application. Figure 7As shown, the network architecture includes core network (CN) equipment and access network (taking RAN as an example) equipment. The RAN equipment includes a baseband device and a radio frequency device, wherein the baseband device can be implemented by one node or by multiple nodes, and the radio frequency device can be independently implemented remotely from the baseband device, or integrated into the baseband device, or partially remotely arranged and partially integrated into the baseband device. For example, in an LTE communication system, the RAN equipment (eNB) includes a baseband device and a radio frequency device, wherein the radio frequency device can be arranged remotely relative to the baseband device (for example, the radio remote unit (RRU) is relative to the baseband processing unit (BBU)), and the RAN equipment is implemented by a node, which is used to implement the functions of the protocol layers such as radio resource control (RRC), packet data convergence protocol (PDCP), radio link control (RLC), and medium access control (MAC). For another example, in an evolutionary structure, the baseband device may include a CU and a DU, and multiple DUs may be centrally controlled by one CU. As Figure 7 As shown, CU and DU can be divided according to the protocol layers of the wireless network, for example, the functions of the packet data convergence layer protocol layer and above are set in CU, and the functions of the protocol layers below PDCP, such as the RLC layer and the MAC layer, are set in DU.

[0102] This division of the protocol layer is only an example. It can also be divided in other protocol layers, such as dividing in the RLC layer, setting the functions of the RLC layer and the protocol layers above in the CU, and the functions of the protocol layers below the RLC layer in the DU; or dividing in a certain protocol layer, for example, setting some functions of the RLC layer and the functions of the protocol layers above the RLC layer in the CU, and setting the remaining functions of the RLC layer and the functions of the protocol layers below the RLC layer in the DU. In addition, it can also be divided in other ways, such as dividing by latency, setting the functions whose processing time needs to meet the latency requirements in the DU, and the functions that do not need to meet the latency requirements in the CU.

[0103] In addition, the radio frequency device can be remote and not placed in the DU, or can be integrated in the DU, or partly remote and partly integrated in the DU, without any limitation here.

[0104] In addition, please continue to refer to Figure 8 , relative to Figure 8The architecture shown can also separate the control plane (CP) and user plane (UP) of the CU and implement them in different entities, namely, the control plane CU entity (CU-CP entity) and the user plane CU entity (CU-UP entity).

[0105] In the above network architecture, the data generated by the CU can be sent to the terminal through the DU, or the data generated by the terminal can be sent to the CU through the DU. The DU can encapsulate the data directly through the protocol layer and transmit it to the terminal or CU without parsing the data. For example, the data of the RRC or PDCP layer will eventually be processed into the physical layer (PHY) data and sent to the terminal, or converted from the received PHY layer data. In this architecture, the data of the RRC or PDCP layer can also be considered to be sent by the DU.

[0106] In the above embodiments, the CU is divided into access network devices in the RAN. In addition, the CU may also be divided into access network devices in the CN, which is not limited here.

[0107] The devices in the following embodiments of the present application may be located in a terminal or an access network device according to the functions implemented. When the above CU-DU structure is adopted, the access network device may be a CU node, or a DU node, or a RAN device including the functions of a CU node and a DU node.

[0108] It is understandable that when the access network equipment can be divided into CU or DU. Figure 7 As shown, if an access network device covers one or more cells, it may mean that the CU of the access network device covers one or more cells, or it may mean that the DU of the access network device covers one or more cells.

[0109] When the access network equipment can be divided into CU and DU, the two access network equipment communicate through the Xn interface. The interface between the 5G core network (5G Core, 5GC) and each access network equipment is an NG interface, where the NG interface includes a control plane interface and a data plane interface, for example, the control plane interface is an N2 interface, and the data plane interface is an N3 interface.

[0110] like Fig. 9 As shown, Fig. 9 Taking the access network device as gNB as an example, switching from gNB1 to gNB2 can refer to switching from the CU of gNB1 to the CU of gNB2, or from gNB1 to the CU of gNB2. Or switching from the DU of gNB1 to the DU of gNB2, or from gNB1 to the DU of gNB2.

[0111] exist Figure 2-Figure 9In the communication system shown, whether it is LTE eNB, eLTE eNB or gNB, a base station can generally cover one or more cells. Each cell has a certain coverage range, which is relatively fixed. If the terminal leaves the serving cell and enters another cell during movement, if the other cell and the serving cell are managed by different base stations (for example, the serving cell belongs to the source base station and the other cell belongs to the target base station). The terminal needs to switch from the source base station to the target base station under the control of the existing mobile management technology.

[0112] The existing fifth-generation mobile communication technology switching process defines a switching process based on the Xn interface and a switching process based on N2. Among them, the Xn interface is an interface between two access network devices, that is, the switching process of the Xn interface can be understood as when the source radio access network (Source Radio Access Network, S-RAN) device determines that the terminal is switching the access network device, the S-RAN device sends a switching request to the target radio access network (target Radio Access Network, T-RAN) device; when the S-RAN device determines that the T-RAN device agrees to switch the terminal to the T-RAN device, the S-RAN device initiates a switching process to the terminal to switch the terminal to the T-RAN device. N2 is an interface between the access network device and the AMF network element, that is, the switching process of N2 can be understood as: when the S-RAN device determines that the terminal is switching the access network device, the S-RAN device sends a switching request to the S-AMF network element. After the S-AMF network element selects the T-AMF network element, the T-AMF network element sends the switching request to the T-RAN device. After the T-AMF network element confirms the switching request from the T-RAN device, it sends the switching request confirmation to the S-AMF network element. When the S-RAN device determines that the T-RAN device agrees to switch the terminal to the T-RAN device, the S-RAN device initiates a switching process to the terminal to switch the terminal to the T-RAN device.

[0113] Regardless of the switching process of the N2 interface or the switching process of the Xn interface, the S-RAN device needs to send a downlink data packet to the terminal before determining to execute the switching process (ie, sending a switching command to the terminal).

[0114] Since the S-RAN device may need to send the terminal's data packets to the terminal during the switching process, in the current switching process, the S-RAN device continues to send the terminal's data packets until a switching command is sent to the terminal when the switching is determined. However, after the S-RAN device determines that the terminal is switching to the access network device, the communication quality of the air interface may become very poor. If the S-RAN device still sends data packets to the terminal during this process, it is possible that the terminal cannot receive the data packets sent by the S-RAN device due to poor communication quality, so the reliability of the data packets is reduced. And the S-RAN device sends data packets to the T-RAN device only after sending the switching command to the terminal, which causes a certain delay.

[0115] Based on this, an embodiment of the present application provides a communication method, which obtains a duplicated data packet by duplicating a data packet (e.g., a source data packet) of a terminal before sending a switching command to the terminal through a source access network device. Then the source access network device sends the duplicated data packet to the target access network device selected for the terminal. In addition, the source access network device needs to continue to send the source data packet to the terminal. Before the terminal successfully switches from the source access network device to the target access network device, the source access network device still needs to send the source data packet to the terminal, and after the terminal successfully switches from the source access network device to the target access network device, the target access network device can send the duplicated data packet obtained based on the source data packet to the terminal. In this way, it can be ensured that if the terminal cannot receive the source data packet from the source access network device during the switching process, the duplicated data packet can also be obtained from the target access network device, thereby ensuring the reliability of data transmission. In addition, since the data packet sent to the target access network device is before the switching command is sent to the terminal, compared with the prior art in which the data packet of the terminal is sent to the target access network device after the switching command is sent to the terminal, the delay can be further reduced.

[0116] It should be pointed out that the various embodiments of the present application can refer to each other, for example, the same or similar steps, method embodiments and device embodiments can refer to each other without limitation.

[0117] Fig.10 The following is a schematic diagram of the composition of an access network device provided in an embodiment of the present application. The source access network device and the target access network device can refer to the following: Fig.10 The structure of the access network equipment is shown in FIG. Fig.10 As shown, the access network device may include at least one processor 41 and a memory 42 .

[0118] Combine the following Fig.10 The following is a detailed introduction to the components of the access network equipment:

[0119] The processor 41 is the control center of the access network device, which can be a processor or a general term for multiple processing elements. For example, the processor 41 is a CPU, or an application specific integrated circuit (ASIC), or one or more integrated circuits configured to implement the embodiments of the present application, such as one or more microprocessors (Digital Signal Processor, DSP), or one or more field programmable gate arrays (Field Programmable Gate Array, FPGA).

[0120] Among them, the processor 41 can execute various functions of the access network device by running or executing software programs stored in the memory 42, and calling data stored in the memory 42, for example, for executing the actions of the source access network device or the target access network device in the various method embodiments of the present application.

[0121] In a specific implementation, as an embodiment, the processor 41 may include one or more CPUs, such as Fig.10 CPU 0 and CPU 1 are shown in .

[0122] In a specific implementation, as an embodiment, the access network device may include multiple processors, such as Fig.10 41 and processor 45 are shown in FIG. Each of these processors may be a single-core processor (single-CPU) or a multi-core processor (multi-CPU). A processor herein may refer to one or more devices, circuits, and / or processing cores for processing data (e.g., computer program instructions).

[0123] The memory 42 can be a read-only memory (ROM) or other types of static storage devices that can store static information and instructions, a random access memory (RAM) or other types of dynamic storage devices that can store information and instructions, or an electrically erasable programmable read-only memory (EEPROM), a compact disc read-only memory (CD-ROM) or other optical disc storage, optical disc storage (including compressed optical discs, laser discs, optical discs, digital versatile discs, Blu-ray discs, etc.), a magnetic disk storage medium or other magnetic storage device, or any other medium that can be used to carry or store the desired program code in the form of instructions or data structures and can be accessed by a computer, but is not limited to this.

[0124] Optionally, the access network device further includes: a bus 44. The memory 42 may exist independently and be connected to the processor 41 via the bus 44. The memory 42 may also be integrated with the processor 41.

[0125] The memory 42 is used to store the software program for executing the solution of the present application.

[0126] Optionally, the access network device further includes: a transceiver 43 .

[0127] The transceiver 43 is used to communicate with other devices or communication networks. For example, it is used to communicate with terminals, core network devices (e.g., AMF network elements, SMF network elements, UPF network elements, etc.), Ethernet, RAN, wireless local area networks (Wireless Local Area Networks, WLAN) and other communication networks. The transceiver 43 may include all or part of a baseband processor, and may also selectively include an RF processor. The RF processor is used to transmit and receive RF signals, and the baseband processor is used to implement the processing of baseband signals converted from RF signals or baseband signals to be converted into RF signals.

[0128] The bus 44 may be an Industry Standard Architecture (ISA) bus, a Peripheral Component Interconnect (PCI) bus, or an Extended Industry Standard Architecture (EISA) bus. The bus may be divided into an address bus, a data bus, a control bus, etc. For ease of representation, Fig.10Only one thick line is used in the diagram, but this does not mean that there is only one bus or only one type of bus.

[0129] Fig.10 The device structure shown in the figure does not constitute a limitation on the access network device, and may include more or fewer components than shown in the figure, or combine certain components, or arrange the components differently.

[0130] It should be understood that the access network device in the embodiments of the present application may be a RAN device or an AN device.

[0131] It should be understood that the execution subject of a communication method in the embodiment of the present application can be a source (or target) access network device, or a chip used in the source (or target) access network device. The embodiment of the present application is not limited to this. The following takes the execution subject of a communication method as a source access network device and a target access network device as an example.

[0132] like Fig.11 As shown, an embodiment of the present application provides a communication method, the method comprising:

[0133] S101. A source access network device sends a first data packet of a terminal to a target access network device.

[0134] It should be understood that the source access network device is the access network device accessed by the terminal before switching, and the target access network device is the access network device selected by the source access network device for the terminal to provide services to the terminal after switching.

[0135] Among them, the first data packet may include a downlink data packet of the terminal processed by the source access network device during the switching process of the terminal. The downlink data packet of the terminal may be a data packet sent to the terminal by the source access network device from the core network during the switching process of the terminal, or a data packet to be sent to the terminal by the source access network device during the switching process of the terminal, or a data packet sent to the terminal by the source access network device during the switching process of the terminal, or a data packet obtained by the source access network device by copying a data packet that needs to be sent to the terminal during the switching process (referred to as a copied data packet), without limitation.

[0136] In addition, the first data packet may include one or more (two or more) downlink data packets of the terminal.

[0137] Exemplarily, when the number of data packets to be sent to the terminal is one, the first data packet is the data packet to be sent to the terminal. When the number of data packets to be sent to the terminal is multiple, the source access network device can send the multiple data packets to be sent to the terminal to the target access network device in batches. At this time, the first data packet can be the first batch of data packets sent by the source access network device to the target access network device, wherein the first data packet can be a data packet re-encapsulated from two or more data packets among the multiple data packets to be sent to the terminal; or it can be any data packet among the multiple data packets to be sent to the terminal. For example, the data packets to be sent to the terminal include: data packets 1 to data packets 15. The first data packet can be data packets 1 to data packets 5.

[0138] Example 1: The source access network device can be Figure 1 In the system shown, LTE eNB1, the target access network device can be Figure 1 LTE eNB2 in the system shown. Or the source access network device can be Figure 2 In the system shown, the target access network device can be an LTE eNB. Figure 2 The eLTE eNB in ​​the system shown in the figure. In this case, the source access network device can send the first data packet to the target access network device through the X2 interface.

[0139] Example 2: The source access network device can be Figure 2 In the eLTE eNB of the system shown, the target access network device can be Figure 2 The NR gNB in ​​the system shown. Alternatively, the source access network device can be Figure 4 In the system shown, gNB1, the target access network device can be Figure 4 gNB2 in the system shown. In this case, the source access network device can send the first data packet to the target access network device through the Xn interface.

[0140] Example 3, if there is no Xn / X2 interface between the source access network device and the target access network device, the source access network device can directly transmit the first data packet to the target access network device. For example, a tunnel is established between the source access network device and the target access network device. The source access network device transmits the first data packet to the target access network device through the tunnel established between the source access network device and the target access network device. Alternatively, the source access network device sends the first data packet to the source UPF network element corresponding to the source access network device, the source UPF network element sends it to the target UPF network element, and the target UPF network element forwards it to the target access network device. If the source UPF network element and the target UPF are the same UPF, the source UPF network element can directly send the first data packet to the target access network device.

[0141] Of course, the source access network device can also be Fig. 9 The target access network device may also be a CU or DU in the gNB1 shown in FIG. Fig. 9 The CU or DU in the gNB2 shown. This embodiment of the present application is not limited to this.

[0142] Exemplarily, the downlink data packet of the terminal in the embodiment of the present application can be obtained from the core network corresponding to the source access network device. The specific acquisition process can refer to the description in the prior art, which will not be repeated here.

[0143] For example, Fig.12 As shown, the downlink data packet of the terminal includes: the downlink data packet of the terminal cached in the buffer of the source access network device (referred to as: cached data packet) (for example, data packet 2 and data packet 3), the new data packet of the terminal received by the source access network device from the UPF network element (referred to as: new data packet), and the copied data packet of the terminal (see the above description). For example, the copied data packet can be a data packet obtained by copying data packet 1.

[0144] Exemplarily, the cached data packet may generally refer to a layer 2 data packet, which has been encapsulated with a PDCP header. The new data packet is a data packet that is not encapsulated with a PDCP header, such as an IP packet. The duplicated data packet mainly refers to a data packet that has been sent to the terminal through the source access device, or a data packet that is ready to be sent to the terminal.

[0145] It should be understood that after the source access network device sends a data packet to the terminal, the source access network device will not have the data packet except for a copy of the data packet.

[0146] It can be understood that the data packet 1 and the duplicate data packet are the same data packets.

[0147] S102: The target access network device receives a first data packet from a terminal of the source access network device.

[0148] It should be understood that the interface on which the target access network device receives the first data packet of the terminal can be combined with the network in which the source access network device and the target access network device are located, and will not be repeated here. For example, if the source access network device sends the first data packet to the target access network device on the Xn interface, the target access network device can receive the first data packet on the Xn interface.

[0149] S103: When the source access network device determines that the target access network device has received the first data packet, the source access network device sends a first message to the terminal.

[0150] The first message is used to instruct the terminal to switch to the target access network device.

[0151] It should be noted that S103 can be replaced by the following process: the source access network device determines that the target access network device receives the first data packet, and the source access network device sends a first message to the terminal. Alternatively, S103 can be replaced by: when the source access network device receives the second message from the target access network device, the source access network device sends the first message to the terminal. Alternatively, the source access network device determines that the target access network device receives the first data packet based on the delay information. Alternatively, after the source access network device receives the second message from the target access network device, the source access network device sends the first message to the terminal.

[0152] Exemplarily, the first message may be a handover command, and the first message carries at least identification information of the target access network device. The identification information of the target access network device is used to identify the target access network device.

[0153] Optionally, in some embodiments, the method provided in the embodiments of the present application further includes:

[0154] S104: The terminal receives a first message from a source access network device, and switches to a target access network device according to the first message.

[0155] It should be understood that the terminal can switch from the source access network device to the target access network device after receiving the first message from the source access network device.

[0156] Specifically, the first message may carry the identifier of the target cell, and the terminal accesses the target cell, thereby switching to the target access network device. The target cell is a cell in the target access network device. Among them, the identifier of the target cell can be sent by the target access network device to the source access network device. For details, please refer to the description in the prior art, which will not be repeated here.

[0157] The first message may be a switching command.

[0158] S105: When the terminal successfully switches from the source access network device to the target access network device, the target access network device sends a first data packet to the terminal.

[0159] Exemplarily, S105 may be replaced by the following method: the target access network device determines that the terminal is successfully switched from the source access network device to the target access network device, and the target access network device sends a first data packet to the terminal.

[0160] It should be understood that S105 may further include: the terminal receives a first data packet from the target access network device.

[0161] It should be noted that when the first data packet in step 101 includes multiple downlink data packets of the terminal, the first data packet sent to the terminal in step 105 can be sent to the terminal in multiple times. For example, the multiple data packets can be repackaged into at least two downlink data packets and sent to the terminal. Specifically, the multiple data packets can be split into the above-mentioned multiple downlink data packets and sent to the terminal; or they can be sent to the terminal at one time without limitation.

[0162] In the embodiment of the present application, before the source access network device sends the first message to the terminal, the source access network device needs to send the data packet that needs to be sent to the terminal during the switching process to the terminal. In this way, the terminal can obtain the data packet sent to the terminal during the switching process from the source access network device before switching to the target access network device, and after the terminal switches to the target access network device, the terminal can obtain the data packet sent to the terminal from the target access network device. That is, on the one hand, if the terminal does not correctly receive a certain data packet from the source access network device (for example, the data packet is not correctly parsed or the data packet is not successfully received due to poor air interface quality, etc.), the terminal can also receive a copy of the same data packet from the target access network device. On the other hand, if the terminal correctly receives a data packet from the source access network device, it also receives a copy of the same data packet from the target access network device. At this time, the terminal can discard duplicate data packets according to the SN of the data packet, that is, retain one data packet with the same SN, or if the terminal determines that a certain SN already exists, it can discard the newly received data packet of the SN.

[0163] The communication method provided by the embodiment of the present application is that during the process of the terminal switching to the target access network device (i.e., before the source access network device sends the first message to the terminal), the source access network device still needs to send the first data packet to the terminal. If the signal quality of the air interface is poor during the switching process, the terminal may not receive the first data packet. Therefore, the first data packet is sent to the target access network device by the source access network device, so that when the source access network device determines that the target access network device has received the first data packet, it sends a first message to the terminal indicating that the terminal has switched to the target access network device. On the one hand, the first data packet can be provided at the target access network device. On the other hand, after determining that the target access network device has received the first data packet, the first message is sent to the terminal, so that after the terminal successfully switches from the source access network device to the target access network device, the target access network device sends the first data packet to the terminal. In this way, it can be ensured that when the terminal cannot receive the first data packet from the source access network device during the switching process, the first data packet can also be obtained from the target access network device, thereby ensuring the reliability of data transmission. In addition, since the data packet is sent to the target access network device before the switching command is sent to the terminal, the delay can be further reduced compared with the prior art in which the terminal data packet is sent to the target access network device only after the switching command is sent to the terminal.

[0164] In order to ensure the reliability of the data packets received by the terminal, the first data packet includes a copy data packet. In an implementation scenario of the above embodiment, the above method may also include: the source access network device obtains the copy data packet; or, when the conditions for switching the access network device for the terminal are met, the source access network device obtains the copy data packet.

[0165] Exemplarily, the source access network device may obtain the duplicate data packet by the following method 1 or method 2:

[0166] Mode 1: The source access network device copies the data packets that meet the preset conditions in the data packets of the terminal to obtain the copied data packets. That is, during the switching process, when the source access network device determines that the data packets meet the preset conditions, the source access network device copies the data packets that meet the preset conditions to obtain the copied data packets.

[0167] It should be pointed out that the data packet of the terminal in each embodiment of the present application may refer to the downlink data packet of the terminal in step S101, which will not be described in detail.

[0168] The source access network device in the embodiment of the present application has a preset condition. In one example, the preset condition can be pre-configured in the source access network device. In another example, the preset condition can be configured to the source access network device by the core network device. The embodiment of the present application does not limit this.

[0169] Exemplarily, the data packets that meet the preset conditions include at least one of the following situations: data packets using a preset QoS flow, data packets on a preset packet data unit (PDU) session, data packets with a packet loss rate less than or equal to a preset threshold value, or data packets on a preset wireless bearer.

[0170] Optionally, the data packets that meet the preset conditions also include: data packets using a preset service type, and data packets whose reliability requirement is greater than or equal to a second preset threshold value. The second preset threshold value here is used to distinguish from the preset threshold value. Among them, the packet loss rate is less than or equal to the preset threshold value can also be described as "the packet loss rate requirement is less than or equal to the preset threshold value".

[0171] In this case, the source access network device can enable the replication function for a specific data packet to meet the QoS requirements of the service corresponding to the data packet. In this case, the QoS guarantee capability of the corresponding service or data packet can be guaranteed. For example, the QoS guarantee capability of data transmission of the service of the specified terminal can be improved.

[0172] The following describes different situations where data packets meet the preset conditions:

[0173] Case (1): Data packets on a preset radio bearer (radio bearer granularity)

[0174] The preset radio bearer may also be at least one of one or more radio bearers (RBs) of the terminal, wherein the RB may be a signaling radio bearer (SRB) or a data radio bearer (DRB).

[0175] In this case, the source access network device copies all data packets carried on the preset wireless bearer. Among them, the source access network device can determine whether the data packet is a data packet carried on the preset wireless bearer based on the terminal identifier and the terminal wireless bearer identifier carried in the data packet. The source access network device can also determine whether the data packet is a data packet carried on the preset wireless bearer based on the tunnel endpoint identifier (tunnel endpoint identifier, TEID) of the GTP tunnel carried in the data packet (or based on the TEID of the general packet radio service tunneling protocol (general packet radio service tunneling protocol, GTP) tunnel carried in the data packet and the identifier of the source access network device such as the IP address), or the source access network device can also determine whether the data packet is a data packet carried on the preset wireless bearer through the terminal identifier and the TEID of the GTP tunnel.

[0176] Exemplarily, the preset radio bearer may be a radio bearer corresponding to a service with a higher reliability requirement, or the preset radio bearer may be certain preset radio bearers.

[0177] Exemplarily, if DRB1 of the terminal corresponds to a service with a higher reliability requirement, the preset radio bearer may be DRB1. Figure 1 If the source access network device determines that a data packet 1 is transmitted using DRB1, the source access network device copies the data packet 1.

[0178] Case (2): Data packets on a preset packet data unit PDU session (PDU session granularity)

[0179] PDU session: A combination of a group of QoS flows established on a terminal in a 5G network. These QoS flows have the same IP address and data network name (DNN). On the terminal and network side, a PDU session is identified by the IP address and DNN.

[0180] Each PDU session has a unique identifier, which can be one of the following: PDU session identifier, APN, identifier of the user plane core network device, address of the user plane core network device (e.g., IP address), and IP address allocated by the user plane core network device to the terminal.

[0181] Among them, the preset packet data unit PDU session can also be one or more PDU sessions. In this case, the source access network device copies all data packets carried on the preset packet data unit PDU session. Among them, the source access network device can determine whether the data packet is a data packet on the preset packet data unit PDU session based on the TEID of the GTP tunnel carried in the data packet (or based on the TEID of the GTP tunnel carried in the data packet and the identifier of the source access network device such as the IP address). Alternatively, the source access network device can also determine whether the data packet is a data packet on the preset packet data unit PDU session based on the identifier of the terminal carried in the data packet and the TEID of the GTP tunnel. Exemplarily, the TEID can be included in the GTP layer protocol header of the data packet.

[0182] It should be understood that a terminal may have multiple PDU sessions, for example, PDU session 1, PDU session 2, and PDU session 3. If the preset packet data unit PDU sessions are PDU session 1 and PDU session 2, the source access network device copies all data packets carried on PDU session 1 and PDU session 2.

[0183] Case (3), data packets of preset quality of service QoS flow (QoS flow granularity)

[0184] QoS flow refers to the data flow with the same QoS requirements within a PDU session. It can be multiple IP flows with the same QoS requirements.

[0185] In this case, the QoS Flow Identity (QFI) can be obtained by parsing the header information of the GTP layer, or the QFI of the QoS flow can be obtained by parsing the Service Data Adaption Protocol (SDAP) layer. The SDAP layer represents the service adaptation layer, and the SDAP layer has at least one of the following capabilities: adding routing information that can be recognized by the access network device to the data packet, performing routing selection based on the routing information, adding identification information related to the QoS requirement that can be recognized by the access network device to the data packet, performing QoS mapping on multiple links including wireless backhaul nodes for the data packet, adding data packet type indication information to the data packet, and sending flow control feedback information to a node with flow control capability.

[0186] The preset QoS flow may also be one or more QoS flows. In this case, the source access network device copies all data packets in the preset QoS flow. The source access network device may determine whether the data packet is a preset QoS flow based on the QFI in the data packet. Exemplarily, the QFI may be included in the GTP layer protocol header of the data packet.

[0187] For example, if the required QoS flow is the same as the quality of service flow indicated by the QFI carried in the data packet, or is within the range of the required QoS flow, the terminal determines that the data packet is a data packet of the preset QoS flow.

[0188] In case (2) and case (3), the source access network device can be determined according to the reliability requirements of the service, and the reliability of the service may include the service delay, packet loss rate, jitter, etc. The source access network device can replicate the data packets of the service with higher reliability requirements. In this case, the service corresponding to the preset PDU session in case (2) is the service with higher reliability requirements, and the service corresponding to the preset QoS flow in case (3) is the service with higher reliability requirements.

[0189] Case (4): Data packets with a packet loss rate less than or equal to the preset threshold (packet granularity)

[0190] In this case, the data packet usually carries information indicating the packet loss rate. The source access network device determines that the information indicating the packet loss rate in the received data packet indicates that the packet loss rate of the data packet is less than or equal to the preset threshold value, and then the source access network device copies the data packet.

[0191] Case (5): The data packet is a data packet of a preset service type

[0192] The service of the preset service type may be a service with higher reliability requirements, for example, an ultra-reliable low latency communication (URLLC) service. In this case, the data packet may be a data packet of the URLLC service.

[0193] For example, a data packet may carry information indicating the service type of the data packet. If the service type indicated by the data packet is a URLLC service, the source access network device copies the data packet.

[0194] Case (6): The data packet has a reliability requirement greater than or equal to the second preset threshold value.

[0195] The reliability of the data packet can be understood as the reliability of the service to which the data packet belongs. The second preset threshold value can be preset or determined by the source access network device according to a preset rule.

[0196] It should be noted that the data packet satisfies the preset conditions and may also include the above-mentioned multiple situations (that is, when the data packet satisfies the conditions shown in the above-mentioned multiple situations, the data packet satisfies the preset conditions), for example: the data packet satisfies the conditions of any one of the situations (1), (4), and (5) and also satisfies the conditions of any one or more of the situations (2) and (3).

[0197] Mode 2: The source access network device copies the data packet of the terminal to obtain a copied data packet.

[0198] The above-mentioned method 2 is an implementation method based on the terminal granularity. In this case, the source access network device copies all the data packets of the terminal. Exemplarily, the source access network device can identify the data packet of the terminal according to the terminal identifier carried in the data packet, and copy the identified data packet.

[0199] In addition, the core network device may instruct the source access network device to copy all data packets of the terminal during the handover process. Specifically, the core network device may instruct the source access network device to copy data packets of a specific type of terminal during the handover process.

[0200] The above mainly describes the granularity of the source access network device to copy the data packets. On the one hand, the source access network device can select the granularity of the copied data packets as needed. On the other hand, the source access network device can determine the granularity of the copied data packets according to the QoS requirements of the service or according to the default wireless bearer information of the session or according to the instructions of the core network. For example, if the core network instructs to copy the data packets at the terminal granularity, the source access network device copies all the data packets of the terminal to obtain copied data packets. For example, if the QoS flow of the service meets specific QoS requirements, the source access network device determines the QoS flow as the preset QoS flow. Then all the data packets on the preset QoS flow are copied to obtain copied data packets.

[0201] It should be noted that, when the source access network device determines the data packets that meet the preset conditions, it can uniformly copy the data packets that meet the preset conditions. For example, the data packets that meet the preset conditions include: data packet 1 and data packet 2, then the source access network device copies data packet 1, and copies data packet 2. Alternatively, when the source access network device determines the data packets that meet the preset conditions, for each data packet that meets the preset conditions, the source access network device can copy the data packet that meets the preset conditions. For example, when the source access network device sends data packet 1, it copies data packet 1. When the source access network device sends data packet 2, it copies data packet 2.

[0202] The duplicate data packet may be buffered in the source access network device before being sent to the target access network device.

[0203] Among them, the terminal's data packet may include a copied data packet that is copied from the data packet received from the core network, and in this case, the copied data packet does not include a sequence number (SN); it may also include a copied data packet that is copied from the data packet sent by the source access network device to the terminal, and in this case, the copied data packet includes an SN.

[0204] Optionally, in another implementation scenario of the above embodiment, in order to improve the accuracy of the source access network device determining that the target access network device has received the first data packet, the source access network device may determine that the target access network device has received the first data packet in the following manner, such as: Fig.13 As shown, the above method may also include:

[0205] S106. The target access network device sends a second message to the source access network device, where the second message is used to indicate that the target access network device has received the first data packet.

[0206] Correspondingly, the source access network device may receive the second message from the target access network device, and then execute step S103 in which the source access network device sends the first message to the terminal.

[0207] The second message may be a data reception confirmation indication (eg, User Data received indication).

[0208] Accordingly, in the embodiment S103 of the present application, the source access network device determines that the target access network device has received the first data packet, which can be specifically implemented in the following manner: the source access network device can determine that the target access network device has received the first data packet according to the second message. Obviously, at this time, step S103 can be replaced by: when the source access network device receives the second message from the target access network device, the source access network device sends the first message to the terminal.

[0209] Another possible implementation manner, in the embodiment of the present application, the source access network device determines that the target access network device has received the data packet, which can also be implemented by the following method 3:

[0210] Mode 3: The source access network device determines that the target access network device receives the first data packet based on the delay information. Obviously, step S103 can be replaced by: when the source access network device determines that the target access network device receives the first data packet based on the delay information, the source access network device sends a first message to the terminal.

[0211] For example, the source access network device may start a timer when sending the first data packet to the target access network device. If the timer times out, it is determined that the target access network device has received the first data packet.

[0212] The embodiment of the present application does not limit the method for obtaining delay information.

[0213] Exemplarily, on the one hand, the delay information can be pre-configured for the terminal, or the source access network device can determine the delay information based on the QoS information of the first data packet, or the source access network device obtains the delay information from the session management function unit during the session management process.

[0214] Exemplarily, the source access network device can determine the transmission delay of the core network based on the 5G QoS identification (5QI) information in the QoS parameters, thereby determining the delay information.

[0215] Exemplarily, the session management process may refer to a PDU session establishment process or a PDU session update (also referred to as a PDU session modification) process.

[0216] In an optional implementation, the source access network device may send the data packet of the terminal to the target access network device when determining to switch the terminal to the target access network device, that is, the source access network device may send the data packet of the terminal to the target access network device during the process of sending the switching request message to the target access network device. In this case, if the target access network device allows the terminal to be switched to the target access network device, the delay can be reduced.

[0217] It should be understood that the content of the switching request message can refer to the description in the prior art.

[0218] In another optional implementation, when the source access network device determines that the target access network device allows the terminal to be switched to the target access network device, the source access network device sends the terminal's data packet to the target access network device. This facilitates sending the terminal's data packet to the target access network device only when the target access network device allows the switch, thus avoiding the waste of resources caused by the target access network device refusing the switch. Fig.14 As shown, before S101, the above method may further include:

[0219] S107. The target access network device sends first information to the source access network device, where the first information is used to indicate that the terminal is allowed to switch to the target access network device.

[0220] The first information may be carried in a switching request confirmation message, or the first information is a switching request confirmation message.

[0221] S108. The source access network device receives first information from the target access network device.

[0222] Exemplarily, after the source access network device sends a switching request message to the target access network device, the source access network device receives first information from the target access network device indicating that switching is allowed, and the source access network device sends a first data packet to the target access network device.

[0223] In order to further determine that the target access network device allows the terminal to switch to the target access network device, S101 can also be replaced by the following steps: the source access network device determines that the target access network device allows the terminal to switch to the target access network device based on the first information, and the source access network device sends a first data packet to the target access network device.

[0224] In an optional implementation, the following process is also included before S101: the source access network device obtains the measurement report and the wireless resource management information. The source access network device determines that the conditions for switching the access network device for the terminal are met according to the measurement report and the wireless resource management information, and then the source access network device turns on the data packet replication function, that is, the source access network device activates the data replication function of the source access network device, which can also be understood as the source access network device executing the above-mentioned step of replicating the data packet.

[0225] Exemplarily, the measurement report may be reported by the terminal to the source access network device.

[0226] For example, the source access network device determines, based on the measurement report, that the signal quality or level of the source access network device is lower than a preset threshold, and determines that the condition for switching the access network device for the terminal is met.

[0227] In addition, after the source access network device determines the target access network device, the source access network device may send a switching request message to the target access network device, where the switching request message is used to request that the terminal be switched to the target access network device. If the target access network device allows the terminal to be switched to the target access network device, the target access network device sends a message (i.e., the above-mentioned first information) to the source access network device indicating that the switching is approved, so that the source access network device can determine that the target access network device allows the terminal to be switched to the target access network device.

[0228] Exemplarily, the handover request message may include a cell-Radio Network Temporary Identifier (C-RNTI) of the source access network device, a target cell identifier, a physical layer identifier of the source cell, key parameters, etc. For other contents carried in the specific handover request message, reference may be made to the handover request message in the prior art in which the source access network device requests to handover the terminal to the target access network device.

[0229] It should be understood that if there is an Xn interface or an X2 interface between the source access network device and the target access network device, the source access network device can send a handover request message to the target access network device via the Xn interface or the X2 interface. The target access network device can also send a message indicating consent to the handover to the source access network device via the X2 interface or the Xn interface. Figure 1 The source access network device and the target access network device can exchange handover request messages and messages for indicating handover consent through the X2 interface. Figure 4 The source access network device and the target access network device can exchange switching request messages and messages for indicating consent to switching through the Xn interface.

[0230] If there is an Xn interface or an X2 interface between the source access network device and the target access network device, the source access network device can send a switching request message to the mobile management network element 1 corresponding to the source access network device, and then send the switching request message to the mobile management network element 2 corresponding to the target access network device through the mobile management network element 1. The mobile management network element 2 then sends the switching request message to the target access network device. When the target access network device agrees to the switching, the target access network device sends a message indicating the consent to the switching to the source access network device through the mobile management network element 2 and the mobile management network element 1. It should be understood that the mobile management network element (for example, AMF network element or MME) 1 and the mobile management network element 2 can be the same mobile management network element.

[0231] For example, in Figure 1 In the system shown, the source access network device is LTE eNB1, and the target access network device is LTE eNB2. If there is no X2 interface between LTE eNB1 and LTE eNB2, LTE eNB1 sends a handover request message to EPC, and then EPC sends the handover request message to LTE eNB2 via the S1 interface. Conversely, when LTE eNB2 agrees to the handover, LTE eNB2 sends a message indicating the handover agreement to EPC via the S1 interface, and EPC sends the message indicating the handover agreement to LTE eNB1 via the S1 interface.

[0232] For example, in Figure 4 In the system shown, the source access network device is gNB1 and the target access network device is gNB2. If there is no Xn interface between gNB1 and gNB2, gNB1 sends the handover request message to NG-Core through the N2 interface, and then NG-Core sends the handover request message to gNB2 through the N2 interface. Conversely, when gNB2 agrees to the handover, gNB2 sends a message indicating the handover agreement to NG-Core through the N2 interface, and NG-Core sends a message indicating the handover agreement to gNB1 through the N2 interface.

[0233] If the source access network device and the target access network device belong to different networks and there is no interface between the source access network device and the target access network device, taking the source access network device as eNB and the target access network device as gNB as an example, the eNB sends the switching request message to the EPC through the S1 interface, and then the EPC sends the switching request message to the NG-Core through the interface with the NG-Core, and then the NG-Core sends it to the gNB through the N2 interface. Conversely, when gNB2 agrees to the switching, gNB2 sends the message indicating the consent to the switching to the NG-Core through the N2 interface, and the NG-Core sends the message indicating the consent to the switching to the EPC through the interface. The EPC sends the message indicating the consent to the switching to the LTE eNB1 through the S1 interface.

[0234] It should be understood that the interface through which the source access network device sends a data packet to the target access network device in the embodiment of the present application can refer to the interface through which the source access network device sends a switching request message to the target access network device.

[0235] Optionally, in another implementation scenario of the above embodiment, during the process of the source access network device sending the data packet of the terminal to the target access network device, the source access network device may also send the sequence number SN status information to the target access network device. Fig.15 As shown, the above method may also include:

[0236] S109. The source access network device sends sequence number SN status information to the target access network device.

[0237] The SN status information is used by the target access network device to send a data packet to the terminal. The SN status information may specifically include: downlink PDCP SN sending status. For example, the downlink PDCP SN sending status is used to indicate the next new PDCP SN number that the target access network device needs to allocate.

[0238] Exemplarily, the SN status information may be sent to the target access network device during the process of the source access network device requesting a handover from the target access network device. For example, the SN status information may be carried in a handover request message. In this way, after receiving the first data packet, the target access network device may set the SN of the data packet according to the SN status information.

[0239] It should be understood that in the embodiment of the present application, the source access network device sends the SN status information to the target access network device in the following cases. In one case, the SN status information is used to indicate the SN of the data packet sent by the source access network device to the terminal. In another case, it is used to indicate the SN that the target access network device should carry when sending to the terminal.

[0240] S110. The target access network device receives SN status information from the source access network device.

[0241] Since the data packets sent by the source access network device to the terminal of the target access network device may include data packets without SN in addition to the data packets with SN set, therefore, if the target access network device receives the data packets without SN from the source access network device, then after S110, the above method may further include S111:

[0242] S111. The target access network device processes the data packet without the SN received from the source access network device according to the SN status information to obtain a second data packet, and sends the second data packet to the terminal.

[0243] The SN of the second data packet may be determined according to the SN status information.

[0244] It should be understood that, on the one hand, the data packet not carrying the SN may be a data packet in the first data packet, such as an IP packet, or an Ethernet packet, or other types of data packets.

[0245] For example, the first data packet includes: data packet 1, data packet 2, and data packet 3, wherein the source access network device has set SNs for data packet 1 and data packet 2, that is, data packet 1 and data packet 2 carry SNs. However, data packet 3 does not carry an SN, so when the target access network device receives data packet 3, it can determine the SN of data packet 3 according to the SN status information.

[0246] On the other hand, the data packet not carrying the SN may also be a data packet in the data packet of the terminal except the first data packet. For example, the data packet of the terminal includes a first data packet and a second data packet, wherein the first data packet carries the SN and the second data packet does not carry the SN, and the SN of the second data packet is determined according to the SN status information.

[0247] It should be understood that after S111, the following step may also be included: the terminal receives a second data packet sent by the target access network device.

[0248] like Fig.16 As shown, Fig.16 Another communication method provided in an embodiment of the present application is shown. For the convenience of description, the source access network device is an S-RAN device, the target access network device is a T-RAN device, and an Xn interface between the S-RAN device and the T-RAN device is used as an example for description, as described below.

[0249] Step 201: The S-RAN device obtains the terminal context from the AMF network element.

[0250] Specifically, the S-RAN device obtains mobility control information (Mobility Control Information) from the AMF network element.

[0251] The mobility control information may include terminal context.

[0252] The terminal context may include roaming access restriction information.

[0253] The access restriction information may be provided during a connection establishment or a tracking area (TA) update process, and the access restriction information may include available frequency band information.

[0254] It should be understood that before step 201, the terminal can establish a connection with the core network through the S-RAN device, and data can be transmitted between the terminal and the core network through the established connection. For example, the terminal sends an uplink data packet to the core network through the S-RAN device, or the terminal receives a downlink data packet sent by the core network through the S-RAN device.

[0255] Step 202: The S-RAN device configures measurement configuration parameters for the terminal.

[0256] Among them, the S-RAN device can be a 5G gNB, NR or other RAN device, which is not limited in the embodiments of the present application.

[0257] Step 203: The terminal sends a measurement report (MeasurementReports) to the S-RAN device according to the measurement configuration parameters.

[0258] The measurement report is used to indicate the signal quality measured by the terminal, and may include measurement reports of one or more RAN devices.

[0259] Exemplarily, in a scenario where a terminal accesses the first network through an S-RAN, the S-RAN device is a RAN device to which the service cell of the terminal belongs. The terminal periodically measures the signal quality of the service cell of the terminal and the signal quality of the neighboring cells of the terminal. The terminal may periodically send a measurement report to the S-RAN device, and the measurement report includes: the signal quality of the RAN device to which the service cell belongs and the signal quality of the RAN to which the neighboring cells of the terminal belong. The measurement report may also be sent to the S-RAN device by an event trigger, and may also be sent to the S-RAN device after the TA to which the terminal belongs changes. The S-RAN device determines whether to switch the RAN device for the terminal based on the measurement report reported by the terminal.

[0260] The first network in the embodiment of the present application is an EPC network or an NG-Core network.

[0261] The signal quality may include a reference signal receiving power (RSRP). Alternatively, the signal quality may include a reference signal receiving quality (RSRQ). Alternatively, the signal quality may include RSRP and RSRQ.

[0262] Of course, any parameter that can be used to reflect the signal quality of the RAN device to which the terminal receives the service cell and the signal quality of the RAN to which the terminal's neighboring cell belongs can be used as the signal quality of the RAN device to which the terminal receives the service cell and the signal quality of the RAN to which the terminal's neighboring cell belongs, and the embodiments of the present application are not limited to this.

[0263] In one example, when the terminal determines that the signal quality of the serving cell is less than or equal to the first preset threshold, or the signal quality of the neighboring cell is greater than or equal to the second preset threshold, the terminal sends a measurement report to the S-RAN device. In another example, the terminal sends the acquired signal quality of the serving cell or the signal quality of the neighboring cell as a measurement report to the S-RAN device at a preset period. In another example, the terminal may receive a measurement indication sent by the S-RAN device, and the measurement indication is used to instruct the terminal to measure the signal quality of the serving cell or the signal quality of the neighboring cell. In this way, after receiving the measurement indication, the terminal can measure the signal quality of the serving cell or the signal quality of the neighboring cell according to the measurement configuration parameters. Further optionally, the measurement indication can also be used to instruct the terminal to periodically send a measurement report to the S-RAN device according to a preset period, and when the signal quality of the serving cell is less than or equal to the first preset threshold, or the signal quality of the neighboring cell is greater than or equal to the second preset threshold, the terminal sends a measurement report to the S-RAN device.

[0264] The embodiment of the present application does not limit the first preset threshold, the second preset threshold and the preset period, and they can be set according to requirements.

[0265] Step 204: The S-RAN device determines to perform a handover decision based on the measurement report and radio resource management (RRM) information, and activates (or turns on) a data packet duplication function.

[0266] The data packet replication function may refer to the S-RAN device replicating a data packet that the S-RAN device needs to send to the terminal during the handover process. In addition, activating the data packet replication function is an optional action and may not be performed.

[0267] It should be understood that the following types of user plane data may exist in the S-RAN device: data packets cached in the buffer of the S-RAN device that need to be sent to the terminal, data packets newly received from the air interface that need to be sent to the terminal, and first data packets. Among them, the first data packet is a data packet that needs to be sent to the terminal during the switching process. Since in 204, the S-RAN device only determines that the RAN device needs to be switched for the terminal, but the terminal is not connected to the T-RAN device at this time. Therefore, from the time when the S-RAN device determines that the RAN device needs to be switched for the terminal to the time when the S-RAN device sends a switching command to the terminal, the S-RAN device needs to send the data packet sent to the terminal to the terminal. Therefore, the time from the time when the S-RAN device determines that the RAN device needs to be switched for the terminal to the time when the S-RAN device sends a switching command to the terminal can be defined as the switching process, and the data packet that the S-RAN device needs to send to the terminal during the switching process is defined as the first data packet.

[0268] Since the S-RAN device determines that the communication quality of the air interface may become very poor after the handover is initiated, the reliability of the data packet received before the terminal switches to the T-RAN device cannot be guaranteed. In order to ensure the reliability of the data packet received by the terminal during the handover process, the S-RAN device in the embodiment of the present application can copy the first data packet to obtain a copied data packet. It should be understood that the first data packet and the copied data packet are the same data packet.

[0269] For example, when the S-RAN device determines to initiate a handover, it needs to send data packet 1 and data packet 2 to the terminal. The S-RAN device can copy data packet 1 to obtain data packet 1' and copy data packet 2 to obtain data packet 2'. Then, data packet 1 and data packet 2 are sent to the terminal.

[0270] Exemplarily, the RRM information includes information about the RAN to which one or more neighboring cells belong, so that when the S-RAN device determines, based on the measurement report, that the signal quality of the serving cell does not meet the requirement, a RAN device is determined as a T-RAN device to which the terminal switches based on the radio resource management information. Specifically, the S-RAN device may select, based on the signal quality of one or more neighboring cells, a RAN device to which a neighboring cell with a signal quality greater than or equal to a second preset threshold belongs as a T-RAN device to which the terminal switches.

[0271] Step 205: The S-RAN device sends a handover request message (Handover Request message) to the T-RAN device.

[0272] The handover request message may be used to request handover of the terminal to a T-RAN device.

[0273] The handover request message includes but is not limited to the following information: Handover reason, used to indicate the reason for the handover, such as wireless network layer reasons (handover triggered by signal reasons, resource-based optimization, etc.). Target cell identifier, used to uniquely indicate the identifier of the target cell. Handover restriction list, including service PLMN, equivalent PLMN, prohibited service area, etc. Temporary identifier corresponding to the terminal, used by the CN device to search for the saved terminal context (UE context). Core network control function entity identifier associated with the terminal. Network slice identifiers corresponding to one or more or all network slices selected by the terminal. Radio bearer information that needs to be established corresponding to one or more or all network slices selected by the terminal, such as radio bearer identifier, QoS parameters at the radio bearer level, tunnel termination point, and user plane security information corresponding to the radio bearer. Session information that needs to be established corresponding to one or more or all network slices selected by the terminal, such as session identifier, QoS parameters at the session level, tunnel termination point, and user plane security information corresponding to the session. Flow information that needs to be established corresponding to one or more or all network slices selected by the terminal, such as flow identifier, flow-level QoS parameters, tunnel termination point, and user plane security information corresponding to the flow. Radio bearer information, such as radio bearer identifier, QoS parameters at the radio bearer level, tunnel endpoint, and user plane security information corresponding to the radio bearer. Other session information that needs to be established, such as session identifier, QoS parameters at the session level, tunnel endpoint, and user plane security information corresponding to the session. Other flow information that needs to be established, such as flow identifier, QoS parameters at the flow level, tunnel endpoint, and user plane security information corresponding to the flow. Context information of the terminal device, such as the network slice identifier corresponding to one or more or all network slices subscribed by the terminal device, etc.

[0274] Exemplarily, the UE context includes a mobility management context (MM Context) and a bearer context (Bearer Context), and network slice indication information, wherein the MM Context includes information such as a temporary identifier GUTI, a non-access stratum (NAS) key, and a security algorithm, and the Bearer Context includes information such as a bearer identifier and QoS.

[0275] Optionally, the Handover Request message includes downlink SN status (DL SN Status) information.

[0276] Specifically, the S-RAN device sends a handover request (Handover Required) message to the T-RAN device through an interface (such as an Xn interface) between the S-RAN device and the T-RAN device.

[0277] Step 206: The T-RAN device performs admission control.

[0278] The T-RAN device indicates to the access control that the T-RAN device has prepared resources and is ready for handover. In step 206, the T-RAN device performs access control on the terminal based on its support capability for the flow / session / radio bearer of the network slice in which the terminal communicates with the S-RAN device, resource conditions, and remapping policy information.

[0279] For example, if the T-RAN device determines that the support capability, resource status, and remapping policy information of the flow / session / radio bearer of the network slice communicated by the terminal in the S-RAN device can be met, the T-RAN device performs admission control, otherwise the T-RAN device sends an indication message to the S-RAN device to refuse to switch the terminal to the T-RAN device. For example, if the T-RAN device determines that the radio resource requirements required by the terminal can be met, the T-RAN device performs admission control on the terminal.

[0280] In one case, if the T-RAN device does not support at least one flow / session / radio bearer of at least one network slice communicated by the terminal in the S-RAN device but has the capability supported by the relevant network slice, the T-RAN device may request the CN to remap at least one flow / session / radio bearer of at least one network slice communicated by the terminal in the S-RAN device to the network slice supported by the T-RAN device. For example, the T-RAN device determines that the T-RAN device does not support at least one network slice communicated by the terminal in the S-RAN device through the network slice indication information carried in the handover request message received in step 205, but determines that the QoS requirements of the flow / session / radio bearer currently communicated by the terminal can be met through the radio bearer context received in step 205 and the current resource usage status, then the T-RAN device believes that it has the capability to support the network slice required by the flow / session / radio bearer of the terminal.

[0281] Another possible situation is that the T-RAN device cannot clearly determine whether it supports the network slice communicated by the terminal in the S-RAN device. In this case, the T-RAN device may request the CN to remap at least one flow / session / radio bearer of at least one network slice communicated by the terminal in the S-RAN device to the network slice supported by the T-RAN device if the T-RAN device does not support at least one network slice communicated by the terminal in the S-RAN device. For example, the T-RAN device cannot determine whether it can support at least one network slice communicated by the terminal in the S-RAN device through the network slice indication information carried in the handover request message received in step 205, but determines that the QoS requirements of the current communication flow / session / radio bearer of the terminal can be met through the radio bearer context received in step 205 and the current resource usage status, then the T-RAN device believes that it has the support capability for the relevant network slice.

[0282] Another possible situation is that the T-RAN device does not support at least one flow / session / radio bearer of at least one network slice communicated by the terminal in the S-RAN device, but the T-RAN device can remap the flow / session / radio bearer to the network slice supported by the T-RAN device according to the network slice remapping policy information received from step 205. In this case, the T-RAN device can request the CN to remap at least one flow / session / radio bearer of at least one network slice communicated by the terminal in the S-RAN device to the supported network slice selected by the T-RAN device.

[0283] Step 207: The T-RAN device sends a Handover Request Acknowledge message to the S-RAN device.

[0284] The handover request confirmation message may be used to indicate that the T-RAN device allows the terminal to be handed over to the T-RAN device.

[0285] Exemplarily, the switching request confirmation message may be the first information in the above embodiment.

[0286] Specifically, the T-RAN device may execute step 207 when performing admission control.

[0287] Step 208: Upon receiving the handover request confirmation message sent by the T-RAN device, the S-RAN device starts to send user plane data to the T-RAN device.

[0288] The user plane data at least includes a duplicate data packet, so that the T-RAN device can receive the user plane data of the terminal from the S-RAN device.

[0289] Exemplarily, the user plane data in step 208 may be the first data packet in the above embodiment.

[0290] It should be understood that the user plane data sent by the S-RAN device to the T-RAN device in 208 also includes data packets cached in the buffer of the S-RAN device that need to be sent to the terminal, or newly received data packets that need to be sent to the terminal.

[0291] For example, the data packet cached in the buffer of the S-RAN device that needs to be sent to the terminal is data packet 21, the data packet newly received from the air interface that needs to be sent to the terminal is data packet 22, and the data packets that need to be sent to the terminal during the switching process are data packet 1 and data packet 2. Then, the user plane data that the S-RAN device can send to the T-RAN device in step 208 includes: data packet 21, data packet 22, data packet 1' and data packet 2'.

[0292] It should be understood that when the S-RAN device receives the handover request confirmation message, the S-RAN device not only sends the user plane data to the terminal, but also sends the user plane data to the T-RAN device.

[0293] It should be understood that, as an optional implementation method, when the T-RAN device receives the user plane data of the terminal, the T-RAN device sends a data reception confirmation indication to the S-RAN device, so that the S-RAN device receives the data reception confirmation indication from the T-RAN device, thereby determining that the T-RAN device has received the user plane data.

[0294] Step 209: When the S-RAN device determines that the T-RAN device receives the user plane data, the S-RAN device sends a handover command to the terminal.

[0295] The handover command is used to instruct the terminal to handover to the T-RAN device. For example, the handover command may carry an identifier of a target cell or an identifier of a T-RAN device to which the target cell belongs.

[0296] Exemplarily, the switching command may be the first message in the above embodiment.

[0297] Specifically, the manner in which the S-RAN device determines in step 209 that the T-RAN device receives the user plane data may refer to the above embodiment, and the embodiments of the present application will not be described in detail herein.

[0298] Step 210: The terminal accesses the T-RAN device according to the switching command.

[0299] The specific implementation of step 210 can refer to the description in the prior art and will not be repeated here.

[0300] Step 211: The T-RAN device sends user plane data to the terminal.

[0301] The user plane data may include a duplicate data packet.

[0302] It should be understood that the user plane data in step 211 can refer to the first data packet in the above embodiment, and will not be described in detail.

[0303] It should be understood that the data packets sent by the T-RAN device to the terminal in step 211 include duplicate data packets, processed data packets cached in the buffer of the S-RAN device that need to be sent to the terminal, and processed data packets newly received from the air interface that need to be sent to the terminal.

[0304] It should be understood that when the terminal successfully switches from the S-RAN device to the T-RAN device, the T-RAN device can send user plane data to the terminal. At this time, if the terminal has an uplink data packet, it can also be sent to the UPF network element through the T-RAN device. Since the network side does not know that the terminal has switched to the T-RAN device at this time, in order to enable the downlink data packet sent by the network side to be sent to the terminal through the T-RAN device of the terminal access network, the method provided in the embodiment of the present application may also include the following steps:

[0305] Step 212: The T-RAN device sends a path switch request (Path Switch Request) to the AMF network element.

[0306] Step 213: Execute the path switching process between the AMF network element and the core network.

[0307] The specific path switching process between the AMF network element and the core network can refer to the description in the prior art. Through the path switching process, the UPF network element can determine to send the downlink data packet of the terminal to the T-RAN device.

[0308] Step 214: The AMF network element sends a path switching request confirmation message to the T-RAN device.

[0309] It can be understood that after steps X12 to X14, the AMF network element can confirm that the RAN device serving the terminal is a T-RAN device, that is, the AMF network element can subsequently communicate with the terminal through the T-RAN device.

[0310] Step 215: After receiving the path switch request confirmation message, the T-RAN device sends a terminal context release (UE context release) message to the S-RAN device.

[0311] It should be understood that after receiving the terminal context release message, the S-RAN device releases the context of the terminal.

[0312] In the embodiment of the present application, before switching the terminal to the T-RAN device, the S-RAN device sends the user plane data of the terminal to the T-RAN device, and then during the switching process, the S-RAN device continues to send the user plane data of the terminal that needs to be sent to the terminal. After the terminal successfully switches from the S-RAN device to the T-RAN device, the T-RAN device sends the user plane data of the terminal to the terminal. That is, during the switching process, the terminal can obtain two identical copies of the user plane data of the terminal from the S-RAN device and the T-RAN device respectively, thereby ensuring the transmission reliability of the data packet during the switching process. In addition, by having the S-RAN device send the user plane data of the terminal to the T-RAN device before switching the terminal to the T-RAN device, the transmission delay of the switching can be reduced.

[0313] Fig.16 Taking the example that the T-RAN device and the S-RAN device belong to the same AMF network element, in actual practice, the S-RAN device and the T-RAN device may belong to different AMF network elements.

[0314] In summary, Fig.16 The handover process includes: a handover preparation phase (Handover Preparation) (eg, step 201-step 207), a handover execution phase (Handover Execution) (eg, step 208-step 211), and a handover completion phase (Handover Completion) (eg, step 212-step 215).

[0315] Depend on Fig.17 As shown, Fig.17 A communication method provided by an embodiment of the present application is shown. For ease of description, the following description takes the source access network device as an S-RAN device, the target access network device as a T-RAN device, and the case where there is no Xn interface between the S-RAN device and the T-RAN device, and the S-RAN device initiates a switching process (which may be referred to as an N2 switching process) to the S-AMF as an example. The N2 switching process mainly includes a switching preparation phase and a switching execution phase. The N2-based switching process includes scenarios where the AMF network elements of the S-RAN device and the T-RAN device are the same, and scenarios where the AMF network elements of the S-RAN device and the T-RAN device are different. Fig.17 Take the scenario where the AMF network elements of the S-RAN device and the T-RAN device are different (for example, the S-RAN device corresponds to the S-AMF network element, and the T-RAN device corresponds to the T-AMF network element) as an example. The details are as follows.

[0316] Step 301: The S-RAN device determines to initiate the handover process of N2 and copies the data packet of the terminal during the handover process.

[0317] It should be understood that before step 301, the terminal establishes a connection (e.g., a PDU session) between the terminal and the source user plane (S-UPF) network element through the S-RAN device. The terminal can send uplink (UL) user plane data to the S-UPF network element through the S-RAN device. The S-UPF network element can send downlink (DL) user plane data to the terminal through the S-RAN device.

[0318] The process in step 301 in which the S-RAN device copies the data packet that the S-RAN device needs to send to the terminal during the handover process can refer to the above step 204, which will not be repeated here.

[0319] Step 302: The S-RAN device sends a handover request message to the S-AMF network element.

[0320] The handover request message may include an identifier of the T-RAN device, a target to source transparent container, a session management (SM) N2 information list, a PDU session identifier, and a system internal handover indication.

[0321] The SM N2 information list includes an indication of whether the direct forwarding path is available. The system internal switching indication is used to indicate that the switching is a 5G internal switching.

[0322] Exemplarily, the direct forwarding path may refer to a path between an S-RAN device and a T-RAN device, that is, a network element passed from the S-RAN device to the T-RAN device.

[0323] The source-to-target container includes RAN information used by T-RAN, and the core network is not aware of the information carried in the source-to-target container, that is, it is transparently transmitted to the core network node.

[0324] It should be noted that the target to source transparent container refers to a container sent by the S-RAN device to the T-RAN device. The specific content in the container is not identified and processed by the intermediate network element and can be directly transmitted to the T-RAN device. After receiving the source to target container, the T-RAN device can parse the content inside.

[0325] Optionally, the source-to-target container includes SN status information, and the T-RAN device may set the SN of the data packet according to the SN status information.

[0326] Among them, the S-AMF network element is the AMF network element to which the S-RAN device is connected.

[0327] Step 303: If the S-AMF network element cannot serve the terminal, the S-AMF network element selects a T-AMF network element for the terminal.

[0328] Exemplarily, the S-AMF network element selects an AMF network element connected to the T-RAN device as the T-AMF network element according to the identifier of the T-RAN device.

[0329] Exemplarily, the identifier of the T-RAN device is used to identify the T-RAN device.

[0330] For example, the S-AMF network element determines, based on the identifier of the T-RAN device, that the T-RAN device is not managed by the S-AMF network element, and the S-AMF network element determines that it cannot serve the terminal.

[0331] Step 304: The S-AMF network element sends a request to establish a terminal context connection (Namf_Communication_CreateUEContext Request) message to the T-AMF network element.

[0332] Exemplarily, the Namf_Communication_CreateUEContext Request message includes N2 information, terminal context information.

[0333] The N2 information includes an identifier of the T-RAN device, a source-to-target container of the SN state, an SM N2 information list, a PDU session identifier, and one or more of a service area restriction.

[0334] Exemplarily, one PDU session corresponds to one SM N2 information list, which is sent to the SMF network element.

[0335] Exemplarily, the terminal context includes a subscriber permanent identifier (SUPI), allowed network slice selection assistant information (NSSAI) corresponding to the access type, a PDU session identifier, information of the corresponding SMF network element of the terminal, and a single network slice selection assistant information (Single network slice selection assistant identifier, S-NSSAI), a PCF network element identifier and a data network name (DNN).

[0336] Step 305: The T-AMF network element sends a request to update the PDU session context (Nsmf_PDUSession_UpdateSMContext Request) message to the SMF network element.

[0337] The Nsmf_PDUSession_UpdateSMContext Request message may include an SM N2 information list.

[0338] Exemplarily, the PDU session context includes the IP address used by the PDU session, the access point name (APN), the SMF network element and UPF network element addresses, and the context information of each QoS flow.

[0339] Among them, before step 305, the T-AMF network element may also determine the SMF network element in step S305 according to the SMF information carried in the terminal context.

[0340] Step 306: Based on the identification of the T-RAN device, the SMF network element determines whether N2 switching is allowed.

[0341] Exemplarily, if the SMF determines that the session service of the terminal cannot be transmitted in the target cell of the T-RAN device indicated by the identifier of the T-RAN device, N2 switching is not allowed. For example, some services can only be accessed in a specific area, such as a campus network, and cannot be accessed after leaving the campus.

[0342] Further, the SMF network element can detect whether the UPF network element can provide services for the terminal. For example, if the SMF network element determines that the terminal moves out of the service area of ​​the S-UPF network element, the SMF network element selects a T-UPF network element for the terminal. If the SMF network element selects a T-UPF network element, step 307 is executed.

[0343] Step 307: The SMF network element sends an N4 session establishment request (Session establish request) to the T-UPF network element so that the T-UPF network element can receive the N4 session establishment request.

[0344] The N4 session establishment request may be used to establish a user plane connection, and the N4 session establishment request may carry user plane tunnel information.

[0345] It should be understood that the T-UPF network element can also send an N4 session establishment response to the SMF network element.

[0346] Step 308: The SMF network element sends a PDU session context update response (Nsmf_PDUSession_UpdateSMContext Response) message to the T-AMF network element.

[0347] Exemplarily, if the SMF network element accepts the PDU session switching, the Nsmf_PDUSession_UpdateSMContextResponse message includes the N3 IP address and the uplink (UL) CN tunnel identifier and QoS parameters. If the SMF network element does not accept the PDU session switching, the Nsmf_PDUSession_UpdateSMContextResponse message includes a reason value for not accepting.

[0348] Step 309: The T-AMF network element receives the Nsmf_PDUSession_UpdateSMContextResponse message from the SMF network element.

[0349] Exemplarily, if the T-AMF network element determines to execute the N2 switching process, step 310 is executed.

[0350] For example, when the T-AMF network element receives the Nsmf_PDUSession_UpdateSMContextResponse message sent by the SMF network element, if the Nsmf_PDUSession_UpdateSMContextResponse message indicates that the PDU session switching is accepted, the T-AMF network element determines to execute the N2 switching process. Or the T-AMF network element determines that the maximum waiting time has expired, and the T-AMF network element determines to execute the N2 switching process.

[0351] Step 310: The T-AMF network element sends a handover request message to the T-RAN device.

[0352] The switching request message may include at least one of N2 MM information, N2 session management (SM) information list, source-to-target container, service area restriction, or unaccepted PDU session list, wherein the source-to-target container includes SN status information.

[0353] For example, the N2 MM information includes a security context and the like.

[0354] Exemplarily, the unaccepted PDU session list carries the identifier of the PDU session that failed to switch.

[0355] Step 311: The T-RAN device sends a handover request confirmation message to the T-AMF network element.

[0356] The handover request confirmation message may include at least one of a target to source container, an N2 SM response list, a failed PDU session list, or a T-RAN SM N3 transmission information list.

[0357] Exemplarily, the target-to-source container carries QoS flow information of successful switching.

[0358] The handover request confirmation message in step 311 is the first information in the above embodiment.

[0359] The target-to-source container refers to a container sent by the T-RAN device to the S-RAN device. The specific content in the container is not identified and processed by the intermediate network element and can be directly transmitted to the S-RAN device. After receiving the target-to-source container, the S-RAN device can parse the content inside.

[0360] Exemplarily, the target-to-source container may include a security context, QoS information, and a target cell identifier.

[0361] Step 312: The T-AMF network element sends an Nsmf_PDUSession_UpdateSMContext Request message to the SMF network element, so that the SMF network element receives the Nsmf_PDUSession_UpdateSMContext Request message from the T-AMF network element.

[0362] The Nsmf_PDUSession_UpdateSMContext Request message includes the PDU session identifier, N2SM response, and T-RAN SM N3 forwarding information list.

[0363] For each N2 SM response, the T-AMF network element sends an N2 SM response to the SMF network element; if there is no T-UPF network element, the SMF network element stores the N3 tunnel information.

[0364] Exemplarily, the N3 tunnel information includes a tunnel identifier and a tunnel address.

[0365] It should be understood that if the SMF network element selects the T-UPF network element when executing step 306, the SMF network element executes step 313.

[0366] Step 313: The SMF network element sends an N4 session modification request (N4 session modifyRequest) to the T-UPF network element. The N4 session modification request includes a T-RAN SM N3 forwarding information list and an optional indication of allocating a DL forwarding tunnel.

[0367] Exemplarily, the T-RAN SM N3 forwarding information list includes the N3 address and the N3 tunnel identifier.

[0368] Step 314: The UPF network element sends an N4 session modification response (N4 session modifyResponse) message to the SMF network element.

[0369] Among them, the N4 session modification response message may include the SM N3 forwarding information list.

[0370] Step 315: The SMF network element sends an N4 session modification request to the S-UPF network element.

[0371] The N4 session modification request may include a T-RAN SM N3 forwarding information list or a T-UPF SM N3 forwarding information list, and an indirect forwarding DL forwarding tunnel indication.

[0372] Step 316: The S-UPF network element sends an N4 session modification response to the SMF network element. The N4 session modification response includes the S-UPF SM N3 forwarding information list.

[0373] Step 317: The SMF network element sends an Nsmf_PDUSession_UpdateSMContext Response including the N2 SM information list to the T-AMF network element.

[0374] Step 318: The T-AMF network element sends Namf_Communication_CreateUEContextResponse to the S-AMF network element.

[0375] The response may include at least one of N2 information, a PDU session establishment failure list, or an N2 SM information list.

[0376] Step 319: The S-AMF network element sends a switching command to the S-RAN device.

[0377] The switching command includes the target-to-source container and / or N2 SM information.

[0378] Optionally, the switching command may also include a list of failed PDU sessions.

[0379] Step 320: When the S-RAN device receives the handover request confirmation message sent by the T-RAN device, the S-RAN device starts to send the data packet of the terminal to the T-RAN device.

[0380] The data packet of the terminal may include a duplicate data packet.

[0381] Exemplarily, the switching request confirmation message may be the first information in the above embodiment.

[0382] Optionally, the T-RAN device may also send a data reception confirmation indication (eg, the second message in the above embodiment) to the S-RAN device.

[0383] Step 321: When the S-RAN device determines that the T-RAN device has received a data packet from the terminal, the S-RAN device sends a handover command (Handover Command) to the terminal.

[0384] The switching command may include a container of the terminal.

[0385] Exemplarily, the switching command in step 321 is the first message in the above embodiment.

[0386] Exemplarily, the container of the terminal includes an identifier of the target cell.

[0387] Step 322: The terminal synchronizes to the target cell according to the handover command.

[0388] Step 323: The T-RAN device sends a handover confirmation message to the terminal.

[0389] The switching confirmation message may be used to indicate that the switching is successful.

[0390] It should be understood that after step 323, the T-RAN device can send the data packet of the terminal obtained from the S-RAN device to the terminal.

[0391] Step 324: The T-RAN device sends a switching notification to the T-AMF network element.

[0392] The switching notification may be used to indicate that the switching is successful.

[0393] Step 325: The T-AMF network element sends an N2 communication information notification (Namf_Communication_N2InfoNotify) to the S-AMF network element.

[0394] Step 326: The S-AMF network element sends Namf_Communication_N2InfoNotify to the T-AMF network element.

[0395] Step 327, the S-AMF network element sends a (Nsmf_PDUSession_ReleaseSMContext) request to release the PDU session context to the SMF network element.

[0396] The Nsmf_PDUSession_ReleaseSMContext request may include the SUPI and the PDU session identifier.

[0397] Step 328: The T-AMF network element sends a Nsmf_PDUSession_UpdateSMContext request to the SMF network element.

[0398] The Nsmf_PDUSession_UpdateSMContext request may include a switching completion indication.

[0399] If the SMF network element selects a T-UPF network element, the method provided in the embodiment of the present application may further include:

[0400] Step 329: The SMF network element sends an N4 session modification request to the T-UPF network element.

[0401] Step 330: The T-UPF network element sends an N4 session modification response to the SMF network element.

[0402] If the SMF network element does not select the T-UPF network element, the method provided in the embodiment of the present application may further include:

[0403] Step 331: The SMF network element sends an N4 session modification request to the S-UPF network element.

[0404] Step 332: The S-UPF network element sends an N4 session modification response to the SMF network element.

[0405] Step 333: The SMF network element sends an N4 session modification request to the UPF (PSA).

[0406] Step 334: The S-UPF network element sends an N4 session modification response to the SMF.

[0407] At this point, the downlink user plane data sent from the network side to the terminal is sent to the T-UPF network element through the UPF (PSA), then sent by the T-UPF network element to the T-RAN device, and then sent by the T-RAN device to the terminal.

[0408] Finally, the SMF network element sends an Nsmf_PDUSession_UpdateSMContext response containing the PDU session identifier to the T-AMF network element. The terminal initiates the mobile registration update process. The SMF network element sends an N4 session connection release request to the S-UPF network element. The S-UPF network element sends an N4 session release response to the SMF network element. The AMF network element sends a terminal context release command to the S-RAN device. The S-RAN device sends a terminal context release completion to the AMF network element.

[0409] The above mainly introduces the scheme of the embodiment of the present application from the perspective of the interaction between various network elements. It can be understood that in order to realize the above functions, each network element, such as a communication device, includes a hardware structure and / or software module corresponding to the execution of each function. Those skilled in the art should easily realize that, in combination with the units and algorithm steps of each example described in the embodiments disclosed in this document, the present application can be implemented in the form of hardware or a combination of hardware and computer software. Whether a function is executed in the form of hardware or computer software driving hardware depends on the specific application and design constraints of the technical solution. Professional and technical personnel can use different methods to implement the described functions for each specific application, but such implementation should not be considered to exceed the scope of this application.

[0410] The embodiment of the present application can divide the functional units of the communication device according to the above method example. For example, each functional unit can be divided according to each function, or two or more functions can be integrated into one processing unit. The above integrated unit can be implemented in the form of hardware or in the form of software functional units. It should be noted that the division of units in the embodiment of the present application is schematic and is only a logical function division. There may be other division methods in actual implementation.

[0411] The following is an example of dividing each functional module into corresponding functions:

[0412] like Fig.18 As shown, Fig.18 A structural schematic diagram of a communication device provided in an embodiment of the present application is shown. The communication device can be a source access network device in an embodiment of the present application, or a chip applied to a source access network device. The communication device can be used to execute the actions of the source access network device or the S-RAN device in the above-mentioned method embodiments.

[0413] The communication device includes: a sending unit 101 and a processing unit 102 .

[0414] The sending unit 101 is used to support the communication device to execute S101 and S103 in the above embodiment.

[0415] The processing unit 102 is used to support the communication device to execute the step of determining that the source access network device has received the first data packet in the above embodiment.

[0416] Optionally, the sending unit 101 is further used to support the communication device to execute S109 in the above embodiment.

[0417] Optionally, the communication device may further include: a receiving unit 103, configured to support the communication device to execute S108 in the above embodiment.

[0418] All relevant contents of each step involved in the above method embodiment can be referred to the functional description of the corresponding functional module, and will not be repeated here.

[0419] Based on the hardware implementation, the receiving unit 103 and the sending unit 101 in the present application can be the communication interface or communication interface of the source access network device, or the communication interface or communication interface of the chip applied to the source access network device, and the processing unit 102 can be integrated on the processor of the source access network device or on the processor of the chip applied to the source access network device.

[0420] In the case of an integrated unit, Fig.19 A possible logical structure diagram of the communication device involved in the above embodiments is shown. The communication device can be a source access network device or a chip used in the source access network device, and can be used to perform the actions of the source access network device or S-RAN device in the above method embodiments. The communication device includes: a processing module 112 and a communication module 113.

[0421] Among them, the processing module 112 is used to control and manage the actions of the communication device. For example, the processing module 112 is used to execute the steps of message or data processing on the communication device side, for example, supporting the communication device to execute the step of determining that the source access network device receives the first data packet in S103 in the above embodiment. The communication module 113 is used to support the communication device to execute S101, S103, and S108 in the above embodiment. Optionally, the communication module 113 is also used to support the communication device to execute S109 in the above embodiment. And / or other processes performed by the communication device for the technology described herein.

[0422] Optionally, the communication device may further include a storage module 111 for storing program codes and data of the communication device.

[0423] Among them, the processing module 112 can be a processor or a controller, for example, a central processing unit, a general processor, a digital signal processor, an application-specific integrated circuit, a field programmable gate array or other programmable logic devices, transistor logic devices, hardware components or any combination thereof. It can implement or execute various exemplary logic blocks, modules and circuits described in conjunction with the disclosure of this application. The processor can also be a combination that implements a computing function, such as a combination of one or more microprocessors, a combination of a digital signal processor and a microprocessor, etc. The communication module 113 can be a transceiver, a transceiver circuit or a communication interface, etc. The storage module 111 can be a memory.

[0424] When the processing module 112 is the processor 41 or the processor 45, the communication module 113 is the communication interface or the transceiver 43, and the storage module 111 is the memory 42, the communication device involved in the present application can be Fig.10 The communication device shown.

[0425] For example, Fig.10 When the communication device shown is a source access network device, for example, the processor 41 and / or the processor 45 supports the source access network device to perform the step of determining that the source access network device has received the first data packet in S103 in the above embodiment. The transceiver 43 is used to support the source access network device to perform S101, S103, and S108 in the above embodiment. Optionally, the transceiver 43 is also used to support the source access network device to perform S109 in the above embodiment.

[0426] like Fig. 20 As shown, Fig. 20 A schematic diagram of the structure of another communication device provided in an embodiment of the present application is shown, and the communication device can be a target access network device in an embodiment of the present application, or a chip applied to the target access network device. The communication device can be used to execute the actions of the target access network device or T-RAN device in the above-mentioned method embodiments.

[0427] The communication device includes: a sending unit 201 and a receiving unit 202. The sending unit 201 is used to support the communication device to execute S105 in the above embodiment. The receiving unit 202 is used to support the communication device to execute S102 in the above embodiment.

[0428] Optionally, the sending unit 201 is further configured to support the communication device to execute S105, S106, S107, and S111 in the above embodiment. Optionally, the receiving unit 202 is further configured to support the communication device to execute S110 in the above embodiment.

[0429] In the case of an integrated unit, Fig.21 A possible structural diagram of the communication device involved in the above-mentioned embodiments is shown, and the communication device can be a target access network device or a chip used in the target access network device. The communication device includes: a processing module 212 and a communication module 213. The processing module 212 is used to control and manage the actions of the communication device. For example, the processing module 212 is used to support the communication device to perform the operations of message or data processing on the communication device side in the above-mentioned embodiments. For example, the process of determining that the terminal has successfully switched from the source access network device to the target access network device. The communication module 213 is used to support the communication device to perform the operations of receiving and sending messages or data on the communication device side in the above-mentioned embodiments, for example, S102 and S105 in the above-mentioned embodiments.

[0430] Optionally, the communication module 213 is further used to support the communication device to execute the steps S106, S107, S110, S111 in the above embodiments, and / or other processes executed by the communication device for the technology described herein.

[0431] Optionally, the communication device may further include a storage module 211 for storing program codes and data of the communication device.

[0432] Among them, the processing module 212 can be a processor or a controller, for example, a central processing unit, a general processor, a digital signal processor, an application-specific integrated circuit, a field programmable gate array or other programmable logic devices, transistor logic devices, hardware components or any combination thereof. It can implement or execute various exemplary logic blocks, modules and circuits described in conjunction with the disclosure of this application. The processor can also be a combination that implements a computing function, such as a combination of one or more microprocessors, a combination of a digital signal processor and a microprocessor, etc. The communication module 213 can be a transceiver, a transceiver circuit or a communication interface, etc. The storage module 211 can be a memory.

[0433] When the processing module 212 is the processor 41 or the processor 45, the communication module 213 is the communication interface or the transceiver 43, and the storage module 211 is the memory 42, the communication device involved in the present application can be Fig.10 Device shown.

[0434] For example, Fig.10 When the communication device shown is a target access network device, the processor 41 or the processor 45 is used to support the target access network device to perform the operations of message or data processing on the target access network device side in the above embodiment. The transceiver 43 is used to support the communication device to perform the operations of receiving and sending messages or data on the communication device side in the above embodiment, for example, S102 and S105 in the above embodiment. Optionally, the transceiver 43 is also used to support the communication device to perform S106, S107, S110, and S111 in the above embodiment.

[0435] It should be understood that the division of units in a communication device is only a division of logical functions. In actual implementation, they can be fully or partially integrated into one physical entity, or they can be physically separated. And the units in the device can all be implemented in the form of software calling through processing elements; they can also be all implemented in the form of hardware; some units can also be implemented in the form of software calling through processing elements, and some units can be implemented in the form of hardware. For example, each unit can be a separately established processing element, or it can be integrated in a certain chip of the device. In addition, it can also be stored in a memory in the form of a program, and called and executed by a certain processing element of the device. The function of the unit. In addition, all or part of these units can be integrated together, or they can be implemented independently. The processing element described here can be an integrated circuit with signal processing capabilities. In the implementation process, each step of the above method or each unit above can be implemented by an integrated logic circuit of hardware in a processor element or in the form of software calling through a processing element.

[0436] In one example, the unit in any of the above devices may be one or more integrated circuits configured to implement the above methods, such as one or more application specific integrated circuits (ASIC), or one or more digital singnal processors (DSP), or one or more field programmable gate arrays (FPGA), etc. For another example, when the unit in the device can be implemented in the form of a processing element scheduler, the processing element can be a general-purpose processor, such as a central processing unit (CPU) or other processor that can call a program. For another example, these units can be integrated together and implemented in the form of a system-on-a-chip (SOC).

[0437] The above receiving unit (or unit for receiving) is a communication interface or communication interface of the device, which is used to receive signals from other devices. For example, when the device is implemented in the form of a chip, the receiving unit is a communication interface or communication interface of the chip for receiving signals from other chips or devices. The above sending unit (or unit for sending) is a communication interface of the device, which is used to send signals to other devices. For example, when the device is implemented in the form of a chip, the sending unit is a communication interface or communication interface of the chip for sending signals to other chips or devices.

[0438] Fig. 221 is a schematic diagram of the structure of a chip 150 provided in an embodiment of the present application. The chip 150 includes at least one processor 1510 and a communication interface 1530 .

[0439] Optionally, the chip 150 further includes a memory 1540, which may include a read-only memory and a random access memory, and provides operation instructions and data to the processor 1510. A portion of the memory 1540 may also include a non-volatile random access memory (NVRAM).

[0440] In some embodiments, the memory 1540 stores the following elements, executable modules or data structures, or a subset thereof, or an extended set thereof:

[0441] In the embodiment of the present application, the corresponding operation is performed by calling the operation instruction stored in the memory 1540 (the operation instruction may be stored in the operating system).

[0442] One possible implementation is that the structures of the chips used by the source access network device and the target access network device are similar, and different devices can use different chips to implement their respective functions.

[0443] The processor 1510 controls the operation of the source access network device and the target access network device. The processor 1510 may also be referred to as a CPU (central processing unit). The memory 1540 may include a read-only memory and a random access memory, and provides instructions and data to the processor 1510. A portion of the memory 1540 may also include a non-volatile random access memory (NVRAM). In specific applications, the memory 1540, the communication interface 1530, and the memory 1540 are coupled together through the bus system 1520, wherein the bus system 1520 may include a power bus, a control bus, and a status signal bus in addition to a data bus. However, for the sake of clarity, in Fig. 22 Various buses are labeled as bus system 1520.

[0444] The method disclosed in the above embodiment of the present application can be applied to the processor 1510, or implemented by the processor 1510. The processor 1510 may be an integrated circuit chip with signal processing capabilities. In the implementation process, each step of the above method can be completed by the hardware integrated logic circuit or software instructions in the processor 1510. The above processor 1510 can be a general processor, a digital signal processor (digital signal processing, DSP), an application specific integrated circuit (application specific integrated circuit, ASIC), a field-programmable gate array (field-programmable gate array, FPGA) or other programmable logic devices, discrete gates or transistor logic devices, discrete hardware components. The methods, steps and logic block diagrams disclosed in the embodiments of the present application can be implemented or executed. The general processor can be a microprocessor or the processor can also be any conventional processor, etc. The steps of the method disclosed in the embodiment of the present application can be directly embodied as a hardware decoding processor to execute, or the hardware and software modules in the decoding processor can be executed. The software module can be located in a mature storage medium in the field such as a random access memory, a flash memory, a read-only memory, a programmable read-only memory or an electrically erasable programmable memory, a register, etc. The storage medium is located in the memory 1540, and the processor 1510 reads the information in the memory 1540 and completes the steps of the above method in combination with its hardware.

[0445] Optionally, the communication interface 1530 is used to perform Fig.11 , Figure 13-Figure 17 The steps of receiving and sending of the source access network device and the target access network device in the illustrated embodiment.

[0446] Processor 1510 is used to execute Fig.11 , Figure 13-Figure 17 The processing steps of the source access network device and the target access network device in the illustrated embodiment.

[0447] In the above embodiments, the instructions stored in the memory for execution by the processor may be implemented in the form of a computer program product. The computer program product may be pre-written in the memory, or may be downloaded and installed in the memory in the form of software.

[0448] The computer program product includes one or more computer instructions. When the computer program instructions are loaded and executed on the computer, the process or function according to the embodiment of the present application is generated in whole or in part. The computer can be a general-purpose computer, a special-purpose computer, a computer network, or other programmable devices. The computer instructions can be stored in a computer-readable storage medium, or transmitted from one computer-readable storage medium to another computer-readable storage medium. For example, the computer instructions can be transmitted from a website site, a computer, a server or a data center by wired (e.g., coaxial cable, optical fiber, digital subscriber line (digital subscriber line, DSL)) or wireless (e.g., infrared, wireless, microwave, etc.) mode to another website site, computer, server or data center. The computer-readable storage medium can be any available medium that a computer can store or a data storage device such as a server or a data center that includes one or more available media integration. The available medium can be a magnetic medium, (e.g., a floppy disk, a hard disk, a tape), an optical medium (e.g., a DVD), or a semiconductor medium (e.g., a solid state hard disk solid state disk, SSD), etc.

[0449] On the one hand, a computer storage medium is provided, in which instructions are stored. When the instructions are executed, the source access network device or the chip applied to the source access network device executes S101, S103, S108, and S109 in the embodiment.

[0450] On the other hand, a computer storage medium is provided, in which instructions are stored. When the instructions are executed, the target access network device or the chip applied in the target access network device executes S102, S105, S106, S107, S110, and S111 in the embodiment.

[0451] The aforementioned readable storage medium may include: a USB flash drive, a mobile hard disk, a read-only memory, a random access memory, a magnetic disk or an optical disk, and other media that can store program codes.

[0452] On the one hand, a computer program product comprising instructions is provided. The computer program product stores instructions. When the instructions are executed, the source access network device or a chip applied to the source access network device executes the source access network device in the embodiment to execute S101, S103, S108, and S109 in the above-mentioned embodiment.

[0453] On the other hand, a computer program product comprising instructions is provided. The computer program product stores instructions, and when the instructions are executed, the target access network device or the chip applied in the target access network device executes S102, S105, S106, S107, S110, and S111 in the embodiment.

[0454] On the one hand, a chip is provided, which is applied to a source access network device. The chip includes at least one processor and a communication interface. The communication interface is coupled to at least one processor, and the processor is used to run instructions to execute S101, S103, S108, and S109 in the embodiment.

[0455] On the other hand, a chip is provided, which is applied to a target access network device, the chip includes at least one processor and a communication interface, the communication interface is coupled to at least one processor, and the processor is used to run instructions to execute S102, S105, S106, S107, S110, and S111 in the embodiments.

[0456] In one aspect, the present application provides a communication system, the communication system comprising: Fig.18 The communication device described Fig. 20 The described communication device and terminal.

[0457] In another aspect, the present application provides a communication system, the communication system comprising: Fig.19 The communication device described Fig.21 The described communication device and terminal.

[0458] Although the present application has been described in conjunction with specific features and embodiments thereof, it is obvious that various modifications and combinations may be made thereto without departing from the spirit and scope of the present application. Accordingly, this specification and the drawings are merely exemplary illustrations of the present application as defined by the appended claims, and are deemed to have covered any and all modifications, variations, combinations or equivalents within the scope of the present application. Obviously, those skilled in the art may make various modifications and variations to the present application without departing from the spirit and scope of the present application. Thus, if these modifications and variations of the present application fall within the scope of the claims of the present application and their equivalents, the present application is also intended to include these modifications and variations.

Claims

1. A communication method, characterized in that: include: Sending first information to the source access network device, where the first information is used to indicate that the terminal is allowed to switch to the target access network device; Receiving a first data packet from the terminal of the source access network device, where the first data packet carries a sequence number SN; When the terminal is synchronized to the target access network device, sending the first data packet to the terminal; Receiving serial number SN status information from the source access network device; Receiving a data packet without an SN from the source access network device, wherein the data packet without an SN is a data packet of the terminal in the source access network device; A second data packet is sent to the terminal, where the second data packet is obtained based on the SN status information and the data packet not carrying the SN.

2. The method according to claim 1, characterized in that The method further comprises: A second message is sent to the source access network device, where the second message is used to indicate that the target access network device has received the first data packet.

3. The method according to claim 1 or 2, characterized in that: The method further comprises: The data packet not carrying the SN is processed according to the SN status information to obtain the second data packet carrying the SN.

4. The method according to claim 1 or 2, characterized in that: The first data packet is a data packet on one or more radio bearers of the terminal.

5. The method according to claim 1 or 2, characterized in that: The first data packet is a data packet carrying an SN in the data packet of the terminal in the source access network device.

6. A communication method, characterized in that: include: The terminal receives first information from a source access network device, where the first information is used to indicate that the terminal is allowed to switch to a target access network device; The terminal receives a first data packet from the source access network device, where the first data packet carries a sequence number SN; After the terminal is synchronized to the target access network device according to the first information, receiving the first data packet from the target access network device; A second data packet is received from the target access network device, where the second data packet is obtained based on the SN status information and a data packet not carrying the SN, and the data packet not carrying the SN is a data packet of the terminal in the source access network device.

7. The method according to claim 6, characterized in that The first data packet is sent from the source access network device to the target access network device before the terminal is synchronized to the target access network device.

8. The method according to claim 6 or 7, characterized in that: The method further comprises: The terminal discards the first data packet from the source access network device or the first data packet from the target access network device according to the SN.

9. A communication device, characterized in that: include: A sending unit, configured to send first information to a source access network device, wherein the first information is used to indicate that the terminal is allowed to switch to the communication device; A receiving unit, configured to receive a first data packet from the terminal of the source access network device, where the first data packet carries a sequence number SN; The sending unit is configured to send the first data packet to the terminal when the terminal is synchronized to the communication device; The receiving unit is further configured to receive the sequence number SN status information from the source access network device; The receiving unit is further configured to receive a data packet without an SN from the source access network device, wherein the data packet without an SN is a data packet of the terminal in the source access network device. The sending unit is further configured to send a second data packet to the terminal, where the second data packet is obtained based on the SN status information and the data packet not carrying the SN.

10. The communication device according to claim 9, characterized in that: The sending unit is further used to send a second message to the source access network device, where the second message is used to indicate that the communication device has received the first data packet.

11. The communication device according to claim 9 or 10, characterized in that: The processing unit is used to process the data packet not carrying the SN according to the SN status information to obtain a second data packet carrying the SN.

12. The communication device according to claim 9 or 10, characterized in that: The first data packet is a data packet on one or more radio bearers of the terminal.

13. The communication device according to claim 9 or 10, characterized in that: The first data packet is a data packet carrying an SN in the data packet of the terminal in the source access network device.

14. A communication device, characterized in that: The communication device is a terminal, and the communication device includes: A receiving unit, configured to receive first information from a source access network device, wherein the first information is used to indicate that the terminal is allowed to switch to a target access network device; The receiving unit is further configured to receive a first data packet from the source access network device; The receiving unit is further configured to receive the first data packet from the target access network device after being synchronized to the target access network device through the processing unit according to the first information, wherein the first data packet carries a sequence number SN; The receiving unit is also used to receive a second data packet from the target access network device, where the second data packet is obtained based on the SN status information and a data packet not carrying an SN, and the data packet not carrying an SN is a data packet of the terminal in the source access network device.

15. The communication device according to claim 14, characterized in that: The first data packet is sent from the source access network device to the target access network device before the terminal is synchronized to the target access network device.

16. The communication device according to claim 14 or 15, characterized in that: The processing unit is further configured to discard the first data packet from the source access network device or the first data packet from the target access network device according to the SN.

17. A chip, characterized in that: The chip includes a processor and a communication interface, the communication interface is coupled to the processor, the processor is used to run a computer program or instructions to implement the communication method as described in any one of claims 1 to 5, or to implement the communication method as described in any one of claims 6 to 8, and the communication interface is used to communicate with other modules outside the chip.

18. A computer-readable storage medium, characterized in that: The computer-readable storage medium stores a computer program or instruction. When the computer program or instruction is executed, the communication method according to any one of claims 1 to 5 is implemented, or the communication method according to any one of claims 6 to 8 is implemented.

19. A computer program product, characterized in that When the computer program product is run on a computer, the computer is enabled to execute the method according to any one of claims 1 to 5, or the computer is enabled to execute the method according to any one of claims 6 to 8.

20. A communication device, characterized in that: include: A memory and a processor coupled to the memory, the memory being used to store a program, and the processor being used to execute the program stored in the memory; when the communication device is running, the processor runs the program, so that the communication device executes the method described in any one of claims 1 to 5 above, or the communication device executes the method described in any one of claims 6 to 8 above.

21. A communication system, characterized in that: include: Source access network equipment and target access network equipment, The source access network device is used to send a first data packet to the terminal, where the first data packet carries a sequence number SN; The target access network device is configured to send the first data packet to the terminal when the terminal successfully switches from the source access network device to the target access network device; The source access network device is further used to send the sequence number SN status information of the target access network device and send the data packet of the terminal without carrying the SN to the target access network device; The target access network device is used to execute the method described in any one of claims 1 to 5.

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