CN116114309A

CN116114309A - Data transmission method, communication device and communication system

Info

Publication number: CN116114309A
Application number: CN202080103916.3A
Authority: CN
Inventors: 徐小英
Original assignee: Huawei Technologies Co Ltd
Current assignee: Huawei Technologies Co Ltd
Priority date: 2020-12-18
Filing date: 2020-12-18
Publication date: 2023-05-12
Also published as: WO2022126666A1

Abstract

The embodiment of the application provides a data transmission method, a communication device and a communication system. The method comprises the following steps: the access network equipment receives a first downlink double-broadcast data packet from a user plane network element, wherein the first downlink double-broadcast data packet carries first data and a first sequence number; the access network equipment determines a first PDCP sequence number corresponding to the first sequence number; the access network device sends a second downlink double-broadcast data packet to the terminal device, wherein the second downlink double-broadcast data packet carries the first data and the first PDCP sequence number. The user plane network element uniformly distributes sequence numbers for the downlink data double-broadcast data packets, and then the source access network device and the target access network device map the sequence numbers distributed by the user plane network element into PDCP sequence numbers, so that the source access network device and the target access network device can be ensured to distribute the same PDCP sequence numbers for the same downlink data double-broadcast data packets, the terminal device is prevented from discarding the data packets which are not repeatedly received when packet loss occurs, and the reliability of data transmission is improved.

Description

Data transmission method, communication device and communication system

Technical Field

The embodiment of the application relates to the technical field of communication, in particular to a data transmission method, a communication device and a communication system.

Background

The terminal equipment causes the access network equipment accessed by the terminal equipment to be switched due to the reasons of position movement and the like. In order to reduce the air interface interruption time delay brought in the switching process of access network equipment, one switching method is as follows: in the switching process, the user plane network element simultaneously sends the same downlink data packet (also referred to as a downlink bi-cast data packet) to the source access network device and the target access network device, and the source access network device and the target access network device respectively allocate packet data convergence protocol (packet data convergence protocol, PDCP) sequence numbers for the downlink data packet, and then respectively send the downlink data packet carrying the PDCP sequence numbers to the same terminal device.

Under normal conditions, the source access network device and the target access network device allocate the same PDCP sequence number for the same downlink double-broadcast data packet, and then the terminal device de-duplicates the received downlink double-broadcast data packet respectively from the source access network device and the target access network device based on the PDCP sequence number, namely, one of the two received same downlink double-broadcast data packets is discarded.

However, when the user plane network element sends a downlink dual-broadcast data packet to the source access network device or the target access network device, packet loss may occur, which may cause the source access network device and the target access network device to allocate different PDCP sequence numbers for the same downlink dual-broadcast data packet, and may also cause the source access network device and the target access network device to allocate the same PDCP sequence number for different downlink dual-broadcast data packets, thereby causing the terminal device to discard the data packet which has not been repeatedly received when the data packet is de-duplicated, so that the terminal device omits information from the access network device, and reduces reliability of data transmission.

Disclosure of Invention

The embodiment of the application provides a data transmission method, a communication device and a communication system, which are used for avoiding that a terminal device discards a data packet which is not repeatedly received, so that the terminal device cannot miss information from an access network device, thereby improving the reliability of data transmission.

In a first aspect, an embodiment of the present application provides a data transmission method, including: the access network equipment receives a first downlink double-broadcast data packet from a user plane network element, wherein the first downlink double-broadcast data packet carries first data and a first sequence number; the access network equipment determines a first packet data convergence protocol PDCP sequence number corresponding to the first sequence number; the access network device sends a second downlink double-broadcast data packet to the terminal device, wherein the second downlink double-broadcast data packet carries the first data and the first PDCP sequence number.

Based on the scheme, the user plane network element uniformly distributes the sequence numbers for the downlink data bi-cast data packets, and then the source access network device and the target access network device map the sequence numbers distributed by the user plane network element into the PDCP sequence numbers, so that the source access network device and the target access network device can be ensured to distribute the same PDCP sequence numbers for the same downlink data bi-cast data packets, and further, the terminal device is prevented from discarding the data packets which are not repeatedly received when packet loss occurs, so that the terminal device cannot miss information from the access network device, data loss or interruption in the switching process is avoided, and the reliability of data transmission is improved.

In one possible implementation, the first sequence number is an N3 sequence number.

In one possible implementation method, the determining, by the access network device, a first PDCP sequence number corresponding to the first sequence number includes: the access network equipment determines a first PDCP COUNT value corresponding to the first sequence number; the access network device determines the first PDCP sequence number corresponding to the first PDCP COUNT value.

In one possible implementation, the access network device is a source access network device; before the source access network device receives a first downlink double-broadcast data packet from a user plane network element, the source access network device receives a third downlink double-broadcast data packet from the user plane network element, wherein the third downlink double-broadcast data packet carries second data and a second sequence number; the source access network device determines a mapping relation according to the second sequence number and the second PDCP sequence number corresponding to the third downlink double-broadcast data packet, wherein the mapping relation is used for determining the first PDCP sequence number corresponding to the first sequence number.

In one possible implementation method, the source access network device sends indication information to the target access network device, where the indication information is used to indicate the mapping relationship.

In a possible implementation method, the indication information carries the second sequence number and the second PDCP sequence number corresponding to the second sequence number; or, the indication information carries a difference value between the second sequence number and the second PDCP sequence number; or the indication information carries the second sequence number and a second PDCP COUNT value corresponding to the second sequence number, and the second PDCP COUNT value corresponds to the second PDCP sequence number; or, the indication information carries a difference value between the second sequence number and a second PDCP COUNT value, where the second PDCP COUNT value corresponds to the second PDCP sequence number.

Based on the above scheme, the source access network device can accurately determine the mapping relationship between the sequence number allocated by the UPF and the PDCP COUNT value (or PDCP sequence number) required to be allocated by the source access network device, and further indicates the mapping relationship to the target access network device through the indication information, so that the target access network device can determine the mapping relationship between the sequence number allocated by the UPF and the PDCP COUNT value (or PDCP sequence number) required to be allocated by the target access network device. Therefore, the subsequent source access network device and the target access network device can accurately determine the PDCP sequence number corresponding to the sequence number in the downlink double-broadcast data packet received from the UPF based on the mapping relation.

In one possible implementation method, the source access network device first requests, to a first device, that the first request carries information of a quality of service QoS flow group requesting bi-casting, the first device being a target access network device or a mobility management network element;

the source access network device receives a first response from the first device, the first response carrying information of a group of QoS flows accepting the bicasting, the group of QoS flows accepting the bicasting being part or all of the group of QoS flows requesting the bicasting.

In one possible implementation method, the access network device targets an access network device; the target access network device receives indication information from the source access network device, wherein the indication information is used for indicating a mapping relation, and the mapping relation is used for determining the first PDCP sequence number corresponding to the first sequence number.

In one possible implementation method, the target access network device receives information of a QoS flow group requesting for bi-casting; the target access network equipment determines the information of the QoS stream group receiving the double broadcasting according to the information of the QoS stream group requesting the double broadcasting; the target access network device sends the information of the QoS flow group accepting the double broadcasting to the session management network element.

In one possible implementation method, the target access network device receives information of a QoS flow group requesting for bi-casting, including: the target access network equipment receives a switching request message from source access network equipment, wherein the switching request message carries information of the QoS stream group requesting double broadcasting; or the target access network equipment receives a switching request message from the mobility management network element, wherein the switching request message carries the information of the QoS flow group requesting the double broadcasting.

In a second aspect, an embodiment of the present application provides a data transmission method, including: the user plane network element receives configuration information, wherein the configuration information carries information of a QoS flow group which receives double broadcasting, the QoS flow group which receives double broadcasting comprises one or more QoS flow groups, and a first QoS flow group is any QoS flow group in the QoS flow group which receives double broadcasting; the user plane network element sequentially allocates N3 sequence numbers for the downlink double-broadcast data packets of the first QoS flow group.

Based on the above scheme, the user plane network element can be configured with the information of the QoS flow group receiving the double broadcasting, and the subsequent user plane network element can sequentially allocate the N3 sequence numbers for the downlink data Bao Yi of the QoS flows in the QoS flow group receiving the double broadcasting.

In one possible implementation method, the user plane network element sends downlink bi-cast data packets of the first QoS flow group to a source access network device and a target access network device.

In one possible implementation, the QoS flows in each of the groups of QoS flows accepting the bicast are associated with the same data radio bearer, and the QoS flows in different groups of QoS flows are associated with different data radio bearers.

In one possible implementation, the N3 sequence number is carried in a downlink protocol data unit PDU session information in a downlink dual-cast packet of the first QoS flow group.

In a third aspect, an embodiment of the present application provides a communication apparatus, which may be an access network device, or may be a chip for an access network device. The apparatus has the function of implementing the above-mentioned first aspect or each possible implementation method based on the first aspect. The functions can be realized by hardware, and can also be realized by executing corresponding software by hardware. The hardware or software includes one or more modules corresponding to the functions described above.

In a fourth aspect, an embodiment of the present application provides a communication device, where the device may be a user plane network element, and may also be a chip for the user plane network element. The apparatus has the function of implementing the above second aspect or each possible implementation method based on the second aspect. The functions can be realized by hardware, and can also be realized by executing corresponding software by hardware. The hardware or software includes one or more modules corresponding to the functions described above.

In a fifth aspect, embodiments of the present application provide a communications apparatus comprising a processor coupled to a memory for storing a program or instructions that, when executed by the processor, cause the apparatus to implement the method of the first aspect, the possible implementations of the first aspect, the method of the second aspect, or the possible implementations of the second aspect. The memory may be located within the device or may be located external to the device. And the processor includes one or more.

In a sixth aspect, embodiments of the present application provide a communication device, including a unit or means (means) for performing the method of the first aspect, each possible implementation method based on the first aspect, the method of the second aspect, or each step of each possible implementation method based on the second aspect.

In a seventh aspect, embodiments of the present application provide a communication device, including a processor and an interface circuit, where the processor is configured to control the interface circuit to communicate with other devices, and perform the method of the first aspect, each possible implementation method based on the first aspect, the method of the second aspect, or each possible implementation method based on the second aspect. The processor includes one or more.

In an eighth aspect, embodiments of the present application further provide a computer-readable storage medium, including instructions, which when run on a computer, cause the computer to perform the method of the first aspect, the possible implementation methods based on the first aspect, the method of the second aspect, or the possible implementation methods based on the second aspect described above.

In a ninth aspect, embodiments of the present application also provide a computer program product, which when run on a computer, causes the computer to perform the method of the first aspect, the possible implementation methods based on the first aspect, the method of the second aspect or the possible implementation methods based on the second aspect described above.

In a tenth aspect, embodiments of the present application further provide a chip system, including a processor, where the processor is coupled to a memory, where the memory is configured to store a program or an instruction, and where the program or the instruction, when executed by the processor, cause the chip system to implement the method of the first aspect, each possible implementation method based on the second aspect, or each possible implementation method based on the second aspect. The memory may be located within the system-on-chip or may be located outside the system-on-chip. And the processor includes one or more.

Drawings

Fig. 1 is a schematic diagram of a 5G network architecture applicable to an embodiment of the present application;

fig. 2 is a schematic diagram of a packet loss process;

fig. 3 (a) is a schematic diagram of a data transmission method according to an embodiment of the present application;

fig. 3 (b) is a schematic diagram of another data transmission method according to an embodiment of the present application;

fig. 3 (c) is a schematic diagram of another data transmission method according to an embodiment of the present application;

fig. 3 (d) is a schematic diagram of another data transmission method according to an embodiment of the present application;

fig. 3 (e) is a schematic diagram of another data transmission method according to an embodiment of the present application;

FIG. 4 is a schematic diagram of a packet transmission process;

fig. 5 is a schematic diagram of another data transmission method according to an embodiment of the present application;

fig. 6 is a schematic diagram of another data transmission method according to an embodiment of the present application;

fig. 7 is a schematic diagram of another data transmission method according to an embodiment of the present application;

fig. 8 is a schematic diagram of a communication device according to an embodiment of the present application;

fig. 9 is a schematic diagram of another communication device according to an embodiment of the present application.

Detailed Description

Referring to fig. 1, a fifth generation (5th generation,5G) network architecture schematic diagram applicable to the embodiments of the present application is shown, where the 5G network architecture shown in fig. 1 includes three parts, namely a terminal device, a Data Network (DN), and an operator network. The following provides a brief description of the functionality of some of the network elements.

Wherein the operator network may comprise one or more of the following network elements: an authentication server function (Authentication Server Function, AUSF) network element, a network opening function (network exposure function, NEF) network element, a policy control function (Policy Control Function, PCF) network element, a unified data management (unified data management, UDM), a unified database (Unified Data Repository, UDR), a network storage function (Network Repository Function, NRF) network element, an application function (Application Function, AF) network element, an access and mobility management function (Access and Mobility Management Function, AMF) network element, a session management function (session management function, SMF) network element, a radio access network (Radio Access Network, RAN) device user plane function (user plane function, UPF) network element, and the like. Of the above-described operator networks, the portion other than the radio access network may be referred to as a core network.

In a specific implementation, the terminal device in the embodiment of the present application may be a device for implementing a wireless communication function. The terminal device may be a User Equipment (UE), an access terminal, a terminal unit, a terminal station, a mobile station, a remote terminal, a mobile device, a wireless communication device, a terminal agent, a terminal apparatus, or the like in a 5G network or a future evolved public land mobile network (public land mobile network, PLMN). An access terminal may be a cellular telephone, cordless telephone, session initiation protocol (session initiation protocol, SIP) phone, wireless local loop (wireless local loop, WLL) station, personal digital assistant (personal digital assistant, PDA), handheld device with wireless communication capability, computing device or other processing device connected to a wireless modem, vehicle-mounted device or wearable device, virtual Reality (VR) terminal device, augmented reality (augmented reality, AR) terminal device, wireless terminal in industrial control, wireless terminal in unmanned, wireless terminal in telemedicine, wireless terminal in smart grid, wireless terminal in transportation security, wireless terminal in smart city, wireless terminal in smart home, etc. The terminal device may be mobile or stationary.

The terminal device may establish a connection with the operator network through an interface (e.g., N1, etc.) provided by the operator network, and use data and/or voice services provided by the operator network. The terminal device may also access the DN through an operator network, use operator services deployed on the DN, and/or services provided by a third party. The third party may be a service party outside the operator network and the terminal device, and may provide other services such as data and/or voice for the terminal device. The specific expression of the third party may be specifically determined according to the actual application scenario, which is not limited herein.

The RAN is a sub-network of the operator network as an access network element, and is an implementation system between a service node and a terminal device in the operator network. The terminal equipment is to access the operator network, firstly through the RAN, and then can be connected with the service node of the operator network through the RAN. The RAN device in the present application is a device that provides a wireless communication function for a terminal device, and the RAN device is also referred to as an access network device. RAN devices in this application include, but are not limited to: a next generation base station (G nodeB, gNB), evolved node B (eNB), radio network controller (radio network controller, RNC), node B (NB), base station controller (base station controller, BSC), base transceiver station (base transceiver station, BTS), home base station (e.g., home evolved nodeB, or home node B, HNB), baseBand unit (BBU), transmission point (transmitting and receiving point, TRP), transmission point (transmitting point, TP), mobile switching center, and the like in 5G.

The AMF network element mainly performs the functions of mobility management, access authentication/authorization and the like. In addition, it is also responsible for passing user policies between the UE and PCF.

The SMF network element mainly performs the functions of session management, PCF issuing control strategy execution, UPF selection, UE internet protocol (internet protocol, IP) address allocation and the like.

The UPF network element is used as interface UPF of data network to complete the functions of user plane data forwarding, charging statistics based on session/stream level, bandwidth limitation, etc.

The UDM network element is mainly responsible for managing subscription data, user access authorization and other functions.

UDR is mainly responsible for access functions of subscription data, policy data, application data, etc.

The NEF network element is mainly used for supporting the opening of the capability and the event.

The AF network element mainly delivers the requirements of the application side to the network side, such as quality of service (Quality of Service, qoS) requirements or user status event subscriptions. The AF may be a third party functional entity or an application service deployed by an operator, such as an IP multimedia subsystem (IP Multimedia Subsystem, IMS) voice call service.

PCF network element is mainly responsible for charging, qoS bandwidth guarantee, mobility management, UE policy decision and other policy control functions aiming at session and service flow level.

The NRF network element may be configured to provide a network element discovery function, and provide network element information corresponding to a network element type based on a request of another network element. NRF also provides network element management services such as network element registration, update, deregistration, and network element state subscription and push.

AUSF network element: it is primarily responsible for authenticating a user to determine whether to allow the user or device to access the network.

The DN is a network outside the operator network, the operator network can be accessed to a plurality of DNs, a plurality of services can be deployed on the DNs, and services such as data and/or voice can be provided for the terminal equipment. For example, the DN is a private network of an intelligent plant, the sensors installed in the plant of the intelligent plant may be terminal devices, a control server of the sensors is disposed in the DN, and the control server may serve the sensors. The sensor may communicate with the control server, obtain instructions from the control server, transmit collected sensor data to the control server, etc., according to the instructions. For another example, DN is an internal office network of a company, where a mobile phone or a computer of an employee of the company may be a terminal device, and the mobile phone or the computer of the employee may access information, data resources, etc. on the internal office network of the company.

Nausf, nnef, npcf, nudm, naf, namf, nsmf, N1, N2, N3, N4, and N6 in fig. 1 are interface serial numbers. The meaning of these interface sequence numbers may be found in the meanings defined in the 3GPP standard protocols, and are not limited herein.

It should be noted that, in this embodiment of the present application, the mobility management element may be an AMF element shown in fig. 1, or another element having a function of the AMF element in the future communication system, the user plane element may be a UPF element shown in fig. 1, or another element having a function of the UPF element in the future communication system, the session management element may be an SMF element shown in fig. 1, or another element having a function of the SMF element in the future communication system, and the access network device may be a RAN device shown in fig. 1, or another element having a function of the RAN device in the future communication system. For convenience of explanation, in the embodiment of the present application, the mobility management network element is an AMF network element, the session management network element is an SMF, and the user plane network element is a UPF network element.

As described in the background art, when the UPF sends the same downstream bi-cast data packet to the source access network device and the target access network device at the same time, when the terminal device de-duplicated, the terminal device may discard the data packet which has not been received repeatedly, so that the terminal device omits the information from the access network device, and the reliability of data transmission is reduced. The following description is made in connection with specific examples. Here, "deduplication" refers to discarding duplicate packets, where the duplicate packets carry the same data. For example, when the terminal device receives multiple data packets with the same PDCP sequence number, the terminal device only retains one data packet and discards other data packets.

For convenience of description, in the embodiment of the present application, PDCP sequence numbers are also abbreviated as PDCP SNs, where SN is an abbreviation of sequence.

Exemplary, referring to fig. 2, a schematic diagram of a packet loss process is shown. The UPF sequentially and simultaneously sends a downlink double-broadcast data packet 1, a downlink double-broadcast data packet 2 and a downlink double-broadcast data packet 3 to the source access network equipment and the target access network equipment, and under normal conditions, the source access network equipment respectively distributes PDCP SN X, PDCP SN X+1 and PDCP SN X+2 for the received downlink double-broadcast data packet 1, and the downlink double-broadcast data packet 2 and the downlink double-broadcast data packet 3. Assuming that the source access network device loses the downlink double-broadcast data packet 3 and the target access network device loses the downlink double-broadcast data packet 2, the source access network device actually allocates PDCP SN X and PDCP SN X+1 for the downlink double-broadcast data packet 1 and the downlink double-broadcast data packet 2 respectively, and the target access network device actually allocates PDCP SN X and PDCP SN X+1 for the downlink double-broadcast data packet 1 and the downlink double-broadcast data packet 3 respectively. After the terminal equipment receives the downlink double-broadcast data packets from the source access network equipment and the target access network equipment respectively, the downlink double-broadcast data packets carrying the same PDCP SN are considered to be the same downlink double-broadcast data packets according to the PDCP SNs carried by the downlink double-broadcast data packets. Therefore, the terminal device considers that the downstream double-broadcast data packet 2 received from the source access network device is the same downstream double-broadcast data packet as the downstream double-broadcast data packet 3 received from the target access network device, and thus performs a deduplication operation, such as deleting the downstream double-broadcast data packet 2 received from the source access network device or deleting the downstream double-broadcast data packet 3 received from the target access network device. In practice, however, the downstream bi-cast data packet 2 received from the source access network device and the downstream bi-cast data packet 3 received from the target access network device only carry the same PDCP SN, but do not carry the same downstream data. Therefore, if the downlink double-broadcast data packet 2 received from the source access network device is deleted, the terminal device is caused to lose the data in the downlink double-broadcast data packet 2, so that the data is wrongly deleted without repeated reception, and if the downlink double-broadcast data packet 3 received from the target access network device is deleted, the terminal device is caused to lose the data in the downlink double-broadcast data packet 3, so that the data is wrongly deleted without repeated reception. Therefore, the packet loss process can cause the terminal device to discard the data packet which is not repeatedly received by the terminal device, thereby causing the terminal device to miss information from the access network device and reducing the reliability of data transmission.

In order to solve the above problems, the embodiments of the present application provide a data transmission method, which is used to ensure that the same PDCP SN is allocated to the same downlink dual-broadcast data packet, and different PDCP SNs are allocated to different downlink dual-broadcast data packets, so that when a source access network device or a target access network device loses a packet, a terminal device will not discard a data packet which has not been repeatedly received when the terminal device removes a duplicate packet, so that the terminal device will not miss information from the access network device, thereby avoiding data loss or interruption in the switching process, and improving the reliability of data transmission.

Referring to fig. 3 (a), a schematic diagram of a data transmission method according to an embodiment of the present application is provided, where the method includes the following steps:

in step 301a, the upf sends a first downlink dual-broadcast packet to the access network device, where the first downlink dual-broadcast packet carries first data and a first sequence number. Correspondingly, the access network device receives the first downlink double-broadcast data packet.

In step 302a, the access network device determines a first PDCP sequence number corresponding to the first sequence number.

In step 303a, the access network device sends a second downlink dual-broadcast packet to the terminal device, where the second downlink dual-broadcast packet carries the first data and the first PDCP sequence number. Correspondingly, the terminal equipment receives the second downlink double-broadcast data packet.

The access network device may be a source access network device or a target access network device, that is, the UPF sends the same downlink bi-cast data packet to the source access network device and the target access network device.

Based on the scheme, the UPF uniformly distributes sequence numbers for the downlink data bi-cast data packets, and then the source access network device and the target access network device map the sequence numbers distributed by the UPF into the PDCP sequence numbers, so that the source access network device and the target access network device can be ensured to distribute the same PDCP sequence numbers for the same downlink data bi-cast data packets, further, the situation that the terminal device discards the data packets which are not repeatedly received once in the process of deduplication is avoided, the terminal device cannot miss information from the access network device, the loss or interruption of data in the switching process is avoided, and the reliability of data transmission is improved.

As an implementation method, the UPF uniformly allocates an N3 sequence number for the downstream bi-cast packet. That is, the first sequence number carried by the first downlink bi-cast data packet is an N3 sequence number.

As an implementation method, in the above step 302a, the method for determining the first PDCP sequence number corresponding to the first sequence number by the access network device may be: the access network equipment determines a first PDCP sequence number corresponding to the first sequence number according to the mapping relation between the sequence number allocated by the UPF and the PDCP sequence number required to be allocated by the access network equipment. For example, it may also be: the access network equipment determines a first PDCP COUNT value corresponding to the first sequence number according to the mapping relation between the sequence number allocated by the UPF and the PDCP COUNT (COUNT) value required to be allocated by the access network equipment, and then determines the first PDCP sequence number corresponding to the first PDCP COUNT value. Wherein a PDCP sequence number may be determined based on a PDCP COUNT value.

Wherein the PDCP COUNT value uniquely identifies one PDCP service data unit (service data unit, SDU). The PDCP COUNT value consists of a superframe number (Hyper Frame Number, HFN) and PDCP SN. Optionally, the length of HNF is equal to 32 minus the length of PDCP SN.

Referring to fig. 3 (b), a schematic diagram of a data transmission method according to an embodiment of the present application is provided, where the method is performed before step 301a above, and the source access network device determines a mapping relationship between a sequence number allocated by a UPF and a PDCP sequence number (or PDCP COUNT value) that needs to be allocated by the source access network device, and then sends indication information for indicating the mapping relationship to the target access network device.

The method comprises the following steps:

step 301b, the upf sends a third downlink dual-broadcast packet to the source access network device, where the third downlink dual-broadcast packet carries the second data and the second sequence number. Correspondingly, the source access network device receives the third downlink double-broadcast data packet.

Step 302b, the upf sends the third downlink dual-broadcast packet to the target access network device. Correspondingly, the target access network device receives the third downlink double-broadcast data packet.

The third downlink double-broadcast data packet is one downlink double-broadcast data packet in the first N downlink double-broadcast data packets sent by the UPF to the source access network equipment and the target access network equipment, wherein N is a positive integer. For example, the first downlink double-broadcast data packet or the second downlink double-broadcast data packet sent by the UPF to the source access network device and the target access network device may be mentioned.

In step 303b, the source access network device determines a mapping relationship according to the second sequence number and the second PDCP sequence number corresponding to the third downlink multicast data packet, where the mapping relationship may be used to determine the first PDCP sequence number corresponding to the first sequence number.

The source access network device may acquire the second sequence number from the third downlink dual-broadcast data packet, determine the second PDCP sequence number corresponding to the third downlink dual-broadcast data packet according to the PDCP sequence number of one downlink data packet before the third downlink dual-broadcast data packet, and further determine the mapping relationship according to the second sequence number and the second PDCP sequence number.

Wherein, the first sequence number and the second sequence number are both allocated by the UPF, and in one possible method, the first sequence number and the second sequence number are both N3 sequence numbers. The method for determining the mapping relationship will be described below by taking the case that the first sequence number and the second sequence number are both N3 sequence numbers as examples.

It should be noted that, the initial number of the N3 sequence number may be predetermined, or may be dynamically configured. For example, the initial value of the downstream N3 sequence number may be indicated to the source access network device by the SMF or UPF.

In an example one, the third downlink dual-cast data packet is a first downlink dual-cast data packet sent by the UPF to the source access network device and the target access network device, where the N3 sequence number carried by the third downlink dual-cast data packet is 1, the PDCP sequence number allocated by the source access network device to one downlink data packet before the third downlink dual-cast data packet (where the downlink data packet is a data packet unicast to the source access network device) is 100, and the source access network device determines that the PDCP sequence number allocated to the third downlink dual-cast data packet is 101, so that the mapping relationship between the N3 sequence number allocated by the UPF and the PDCP sequence number to be allocated by the source access network device is determined by the source access network device is: n3 sequence number 1 corresponds to PDCP sequence number 101.

In example two, the third downlink dual-broadcast packet is a second downlink dual-broadcast packet sent by the UPF to the source access network device and the target access network device, where the N3 sequence number carried by the third downlink dual-broadcast packet is 2, and the first downlink dual-broadcast packet sent by the UPF to the source access network device is lost, where the source access network device does not receive the first downlink dual-broadcast packet, and if the source access network device may determine, according to a preset rule, for example, that the UPF starts numbering from the N3 sequence number 1 in advance, the source access network device may learn that the first downlink dual-broadcast packet sent by the UPF to the source access network device is lost. On the other hand, if the PDCP sequence number allocated by the source access network device to the downstream data packet before the third downstream bi-cast data packet (the downstream data packet is a data packet unicast to the source access network device) is 100, the source access network device determines that the PDCP sequence number allocated to the third downstream bi-cast data packet is 102, so that the source access network device determines that the mapping relationship between the N3 sequence number allocated by the UPF and the PDCP sequence number required to be allocated by the source access network device is: n3 sequence number 2 corresponds to PDCP sequence number 102. Here, the PDCP sequence number 102 is not the PDCP sequence number 101, because: the source access network device recognizes that one downstream multicast packet is lost before the third downstream multicast packet, and therefore needs to skip one PDCP sequence number.

It should be noted that, as another implementation method, the step 303b may be replaced by: the source access network device determines a mapping relation according to the second sequence number and a second PDCP COUNT value corresponding to the third downlink double-broadcast data packet, wherein the mapping relation is used for indicating the mapping relation between the sequence number allocated by the UPF and the PDCP COUNT value required to be allocated by the source access network device, and one PDCP COUNT value can determine one PDCP sequence number.

In step 304b, the source access network device sends indication information to the target access network device, where the indication information is used to indicate the mapping relationship. Accordingly, the target access network device receives the indication information from the source access network device.

As an implementation method, the indication information carries the second sequence number and the second PDCP sequence number corresponding to the second sequence number. For example, in the first example, the indication information carries 1:101. For another example, in the second example described above, the indication information carries 2:102.

As another implementation method, the indication information carries a difference between the second sequence number and the second PDCP sequence number. For example, in the above example, the indication information carries 100 (i.e., the difference between 101 and 1, or the difference between 102 and 2).

As another implementation method, the indication information carries a second sequence number and a second PDCP COUNT value corresponding to the second sequence number, where the second PDCP COUNT value corresponds to the second PDCP sequence number.

As another implementation method, the indication information carries a difference between a second sequence number and a second PDCP COUNT value, where the second PDCP COUNT value corresponds to the second PDCP sequence number.

And the target access network equipment can acquire the mapping relation between the sequence number allocated by the UPF and the PDCP COUNT value (or PDCP sequence number) required to be allocated by the target access network equipment according to the indication information.

In step 305b, the source access network device sends a fourth downlink dual-broadcast packet to the terminal device, where the fourth downlink dual-broadcast packet carries the second data and the second PDCP sequence number. Correspondingly, the terminal equipment receives the fourth downlink double-broadcast data packet.

Step 306b, the target access network device sends the fourth downlink dual-broadcast packet to the terminal device. Correspondingly, the terminal equipment receives the fourth downlink double-broadcast data packet.

And the target access network equipment determines a second PDCP sequence number carried by the fourth downlink double-broadcast data packet according to the mapping relation and the second sequence number in the third downlink double-broadcast data packet.

It should be noted that, there is no strict restriction on the sequence of steps 302b and 304 b. When the target access network device receives the third downlink double-broadcast data packet from the UPF, and then receives the indication information from the source access network device, the target access network device needs to buffer the third downlink double-broadcast data packet, and after receiving the indication information, determines a second PDCP sequence number corresponding to a second sequence number in the third downlink double-broadcast data packet according to a mapping relation indicated by the indication information, and then the target access network device sends a fourth downlink double-broadcast data packet to the terminal device.

Referring to fig. 3 (c), a schematic diagram of a data transmission method is provided in an embodiment of the present application, where the method is performed before the step 301b, and the method is used to implement information of a QoS flow group requesting bi-casting for UPF configuration.

The method comprises the following steps:

in step 301c, the source access network device sends a first request to the target access network device, where the first request carries information of a QoS flow group requesting for bi-casting. Accordingly, the target access network device receives the first request.

The first request may be a handover request message.

The requested dual-cast QoS flow group includes one or more QoS flow groups, each QoS flow group associated with a data radio bearer (data radio bearer, DRB). That is, all QoS flows in one QoS flow group map to the same data radio bearer, and QoS flows of different QoS flow groups map to different data radio bearers. One way of indicating information of a QoS flow group requesting bi-casting may be: the information for each requested dual-cast QoS flow group may include a QoS flow group identification, one or more QoS flow identifications associated with the QoS flow group identification.

For example, a session corresponds to 3 DRBs, each of which contains one QoS flow group consisting of one or more QoS flows. Thus, the first request may carry information for 3 QoS flow groups, with 1 DRB for each QoS flow group. Alternatively, the first request may carry information of 2 QoS flow groups, each corresponding to 1 DRB. Alternatively, the first request may carry information of 1 QoS flow group, where the information of the QoS flow group corresponds to 1 DRB.

In step 302c, the target access network device determines the information of the QoS flow group accepting the bicasting according to the information of the QoS flow group requesting the bicasting.

Wherein the QoS flow group accepting the bicasting is part or all of the QoS flow group requesting the bicasting. The target access network device may determine the information of the QoS flow group accepting the bicasting based on the following method: for example, the target access network device determines a QoS flow group including QoS flows with high QoS priorities (e.g., low latency and high reliability) in the QoS flow group requesting for the bi-casting as the QoS flow group accepting for the bi-casting. As an example, when the air interface resources of the target cell (i.e., the cell accessed by the terminal device) in the target access network device are limited, the target access network device determines the QoS flow group including QoS flows with high QoS priorities (such as low latency and high reliability) in the QoS flow group requesting for the dual-cast as the QoS flow group accepting the dual-cast.

As an implementation method, for a QoS flow group requesting for dual-casting, the target access network device either accepts dual-casting for all QoS flows in the QoS flow group or rejects dual-casting for all QoS flows in the QoS flow group. For example, the QoS flow group requesting the bicasting includes QoS flow group 1, qoS flow group 2, and QoS flow group 3, and the QoS flow group accepting the bicasting may be one or more QoS flow groups of QoS flow group 1, qoS flow group 2, and QoS flow group 3.

As another implementation, for a QoS flow group requesting a bi-cast, the target access network device may accept the bi-cast for a portion of the QoS flows within the QoS flow group, and reject the bi-cast for another portion of the QoS flows. For example, the QoS flow group requesting the bicasting includes QoS flow group 1, qoS flow group 2, and QoS flow group 3, and the QoS flow group accepting the bicasting may be some or all of QoS flows in QoS flow group 1, qoS flow group 2, and QoS flow group 3. Illustratively, the QoS flow group accepting the bicast may be all QoS flows in QoS flow group 1 and part of QoS flows in QoS flow group 2.

In step 303c, the target access network device sends a first response to the source access network device, where the first response carries information of the QoS flow group accepting the bicasting. Accordingly, the source access network device receives the first response.

Wherein the first response may be a handover confirm message.

Alternatively, the first response may indicate information of a QoS flow group rejecting the dual cast, and further may indicate a reason for rejecting the dual cast.

Optionally, if the source access network device receives, in the first response, the information of the QoS flow group that is sent by the target access network device and refuses the dual-cast, when the source access network device receives, from the UPF, data that refuses the QoS flow in the dual-cast QoS flow group, the source access network device discards the data and does not allocate PDCP SN to the data.

In step 304c, the target access network device sends information of the QoS flow group accepting the bicasting to the SMF. Accordingly, the SMF receives the information of the QoS flow group accepting the bicasting.

For example, the target access network device may send information of the QoS flow group accepting the bicasting to the AMF, and then the AMF sends information of the QoS flow group accepting the bicasting to the SMF.

Optionally, the target access network device may further indicate to the SMF information of the QoS flow group rejecting the dual cast, and may further indicate a reason for rejecting to receive the dual cast.

In step 305c, the smf sends configuration information to the UPF, where the configuration information carries information of the QoS flow group that accepts the bi-cast. Accordingly, the UPF receives the configuration information.

Optionally, the SMF may further indicate to the UPF information of the QoS flow group rejecting the dual cast, and may further indicate a reason for rejecting the dual cast. Thus, the UPF stops transmitting QoS flows of the QoS flow group that reject the bicast.

It should be noted that, the method for configuring the information of the QoS flow group for receiving the dual-cast for the UPF is just an alternative implementation, and in practical application, there may also be other configuration manners, for example, the method may also be that the network management device configures the information of the QoS flow group for receiving the dual-cast for the UPF.

Based on the above scheme, the information of the QoS flow group accepting the bicast may be configured for the UPF, and the subsequent UPF may sequentially allocate the N3 sequence numbers to the downlink data Bao Yi of the QoS flows in the QoS flow group accepting the bicast.

As an alternative implementation method, the operation of step 304c may also be performed by the source access network device. For example, after step 303c, the source access network device sends information of the QoS flow group accepting the bi-cast to the SMF through the AMF. At this point, the target access network device need not perform step 304c described above.

As an implementation method, after the step 305c, the UPF sends a configuration response to the SMF to indicate that the configuration is successful, and then the SMF sends a configuration response to the AMF to indicate that the configuration is successful, and the AMF sends a configuration response to the target access network device to indicate that the configuration is successful. The target access network device then performs step 303c described above. That is, the target access network device sends a first response to the source access network device after receiving the configuration response from the AMF, where the first response carries information of the QoS flow group accepting the bi-casting.

Referring to fig. 3 (d), a schematic diagram of a data transmission method is provided in an embodiment of the present application, where the method is performed before the step 301b, and the method is used to implement information of a QoS flow group requesting bi-casting for UPF configuration.

The method comprises the following steps:

in step 301d, the source access network device sends a first request to the AMF, where the first request carries information of a QoS flow group requesting for bi-casting. Accordingly, the AMF receives the first request.

The first request may be a handover request message.

The specific description of the information of the QoS flow group requesting for bi-casting may refer to the foregoing description, and will not be repeated.

In step 302d, the amf sends a handover request message to the target access network device. Accordingly, the target access network device receives the handover request message.

The handoff request message carries information of the QoS flow group requesting the bi-cast.

In step 303d, the target access network device determines the information of the QoS flow group accepting the bicasting according to the information of the QoS flow group requesting the bicasting.

Wherein the QoS flow group accepting the bicasting is part or all of the QoS flow group requesting the bicasting. The method for determining the information of the QoS flow group accepting the bi-cast by the target access network device may refer to the foregoing description, and will not be repeated.

In step 304d, the target access network device sends information of the QoS flow group accepting the bicasting to the AMF. Accordingly, the AMF receives the information of the QoS flow group accepting the bicasting.

In step 305d, the amf sends a first response to the source access network device, where the first response carries information of the QoS flow group accepting the bicasting. Accordingly, the source access network device receives the first response.

Wherein the first response may be a handover command.

In step 306d, the amf sends to the SMF information of the QoS flow group accepting the bicasting. Accordingly, the SMF receives the information of the QoS flow group accepting the bicasting.

Optionally, the AMF may further indicate to the SMF information of the QoS flow group rejecting the dual cast, and may further indicate a reason for rejecting to receive the dual cast.

In step 307d, the smf sends configuration information to the UPF, where the configuration information carries information of the QoS flow group accepting the bi-cast. Accordingly, the UPF receives the configuration information.

As an alternative implementation method, the operation of step 304d may also be performed by the source access network device. For example, after step 305d, the source access network device sends information of the QoS flow group accepting the double broadcast to the AMF, and then the AMF sends information of the QoS flow group accepting the double broadcast to the SMF in step 306 d. At this point, the target access network device need not perform step 304d described above.

As an implementation method, after the step 307d, the UPF sends a configuration response to the SMF to indicate that the configuration is successful, and then the SMF sends a configuration response to the AMF to indicate that the configuration is successful. The AMF then performs step 305d described above. That is, the AMF sends a first response to the source access network device after receiving the configuration response from the SMF, where the first response carries information of the QoS flow group accepting the bi-casting.

Referring to fig. 3 (e), a schematic diagram of a data transmission method is provided in an embodiment of the present application, where after configuring information of a QoS flow group accepting bi-casting for a UPF, the UPF sends a downlink bi-casting packet.

The method comprises the following steps:

in step 301e, the upf receives configuration information, where the configuration information carries information of a QoS flow group that accepts dual-casting, where the QoS flow group that accepts dual-casting includes one or more QoS flow groups, and the first QoS flow group is any one of the QoS flow groups that accept dual-casting.

For example, the information of the QoS flow group accepting the bicasting may be configured for the UPF by the embodiment corresponding to fig. 3 (c) or fig. 3 (d).

Optionally, qoS flows in each of the QoS flow groups accepting the bicast are associated with the same data radio bearer, and QoS flows in different QoS flow groups are associated with different data radio bearers.

Step 302e, the upf sequentially allocates an N3 sequence number to the downstream bi-cast data packet of the first QoS flow group.

Optionally, the N3 sequence number is carried in downlink PDU session information in a downlink unicast packet of the first QoS flow group.

For each QoS flow group in the QoS flow group accepting the bicast, the UPF transmits, when transmitting the packets of the QoS flows in the QoS flow group, the packets of the QoS flows together with the N3 sequence number allocated in sequence. For example, qoS flow 1, qoS flow 2, qoS flow 3, and upf in QoS flow group 1 sequentially assign N3 sequence numbers (e.g., 1,2, …) to data on these 3 QoS flows. QoS flow group 2 has QoS flow 4, qoS flow 5, and upf assigns N3 sequence numbers (e.g., 1,2, …) to data on these 2 QoS flows in sequence.

And subsequently, the UPF transmits the downlink double-broadcast data packet of the first QoS flow group to the source access network equipment and the target access network equipment.

It should be noted that, in the foregoing embodiment, the first downstream bi-cast packet and the third downstream bi-cast packet may be packets of QoS flows of a QoS flow group of the group of QoS flows accepting bi-casting.

The above scheme will be described below with reference to a specific example. Referring to fig. 4, a schematic diagram of a packet transmission process is shown. The example shown in fig. 4 is a solution to the example shown in fig. 2.

Referring to fig. 4, after receiving the information of the QoS flow group accepting the bi-cast, the upf allocates a continuous N3 sequence number to the downlink data of each QoS flow group, and carries the N3 sequence number in the downlink PDU session information. The UPF sends downlink dual-broadcast data packets to the source access network device and the target access network device, and referring to fig. 4, the UPF sends downlink dual-broadcast data packet 1, downlink dual-broadcast data packet 2, and downlink dual-broadcast data packet 3, which respectively carry N3 serial numbers as follows: 1,2,3. Assuming that the source access network device loses the downlink double-broadcast data packet 3 and the target access network device loses the downlink double-broadcast data packet 2, the source access network device firstly determines that the mapping relationship between the N3 sequence number and the PDCP SN is as follows according to the received downlink double-broadcast data packet 1: and if the N3 sequence number is 1 and corresponds to the PDCP sequence number of 101, the source access network device sends indication information (for example, it may be 1:101, or 100 (i.e. the difference between 101 and 1)) to the target access network device. Therefore, the source access network device can respectively allocate PDCP SN 101 and PDCP SN 102 for the received downlink double-broadcast data packet 1 and downlink double-broadcast data packet 2, and the target access network device respectively allocates PDCP SN 101 and PDCP SN 103 for the received downlink double-broadcast data packet 1 and downlink double-broadcast data packet 3. After the terminal equipment receives the downlink double-broadcast data packet from the source access network equipment and the target access network equipment respectively, according to the PDCP SN carried by the downlink double-broadcast data packet, the downlink double-broadcast data packet 1 received from the source access network equipment and the downlink double-broadcast data packet 1 received from the target access network equipment are considered to be the same downlink double-broadcast data packet, so that the deduplication operation is performed to obtain the downlink double-broadcast data packet 1, the downlink double-broadcast data packet 2 and the downlink double-broadcast data packet 3, the correct reception of the downlink data packet is realized, the situation that the terminal equipment discards the data packet which is not repeatedly received when the deduplication is performed is avoided, the terminal equipment does not miss information from the access network equipment, the loss or interruption of data in the switching process is avoided, and the reliability of data transmission is improved.

The above-described embodiments will be described below with reference to specific embodiments.

The handover procedure referred to in the embodiments of the present application may include, but is not limited to, N2-based handover and Xn-based handover. The Xn interface is an interface between two access network devices, and the N2 interface is an interface between the access network devices and the AMF. Besides the switching scene, the scene suitable for the embodiment of the application can also be a scene in which auxiliary access network equipment is added, and further two-way transmission is performed through two double access network equipment.

Referring to fig. 5, a schematic diagram of a data transmission method according to an embodiment of the present application is provided. The scheme is a sending method of downlink double-broadcast data packets in the N2 switching process.

The method comprises the following steps:

in step 501, the terminal device sends a measurement report to the source access network device. Accordingly, the source access network device receives the measurement report.

And the terminal equipment determines reporting events meeting the measurement report of the wireless signal, and sends the measurement report to the source access network equipment. For example, when the terminal device determines that the quality of the serving cell is lower than a set threshold, a measurement report is sent to the source access network device. For another example, when the terminal device determines that the neighbor cell quality is higher than a set threshold, a measurement report is sent to the source access network device.

In step 502, the source access network device sends a handover request to the AMF. Accordingly, the AMF receives the handover request.

As an implementation method, in this step 502, the source access network device sends an initialization context setup response (INITIAL CONTEXT SETUP RESPONSE) message to the AMF, where the message carries the handover requirement described above.

As another implementation method, in this step 502, the source access network device sends a UE context modification response (UE CONTEXT MODIFICATION RESPONSE) message to the AMF, where the message carries the handover requirement described above.

In step 503, the amf sends a handover request message to the target access network device. Accordingly, the target access network device receives the handover request message.

In step 504, the target access network device sends a handover confirm message to the AMF. Accordingly, the AMF receives the handover confirm message.

The handover confirmation message carries information of a group of QoS flows accepting the bicast, and the QoS flows in the group of QoS flows accepting the bicast are part or all of the QoS flows in the group of QoS flows requesting the bicast.

Optionally, the handover confirmation message may further indicate information of the QoS flow refusing the bi-cast, and further may indicate a reason for refusing to receive the bi-cast.

In step 505, the target access network device sends a bi-cast request message to the AMF. Accordingly, the AMF receives the bi-cast request message.

The double-broadcast request message carries information of the QoS stream group which accepts double broadcasting and downlink tunnel address information of the target access network equipment. The downlink tunnel address is an address on the target access network device for receiving the downlink bi-cast data packet.

Optionally, the bi-cast request message further carries an identifier of a session, where the session is a session corresponding to the QoS flow group that accepts bi-casting.

The amf configures the UPF with information of the QoS flow group accepting the bicasting via the SMF, step 506.

For example, the AMF provides information of the source access network device (such as downlink tunnel address information including the target access network device) to the SMF, and the SMF issues a forwarding rule to the UPF, to instruct the UPF to start sending the downlink bi-cast data packet.

Optionally, after the UPF accepts the configuration, the SMF sends a configuration response to the AMF, and the SMF sends the configuration response to the AMF.

In step 507, the amf sends a handover command to the source access network device. Accordingly, the source access network device receives the handover command.

The handover command carries information of the QoS flow group accepting the bicasting.

Step 508, the source access network device sends a handover message to the terminal device. Accordingly, the terminal device receives the handover message.

In step 509, the source access network device sends indication information to the target access network device. Accordingly, the target access network device receives the indication information.

The indication information is used for indicating the mapping relation between the N3 sequence number and the PDCP SN.

For example, after the step 506, the UPF starts sending the downstream bi-cast data packet to the source access network device and the target access network device, where the downstream bi-cast data packet carries the N3 sequence number allocated by the UPF, for example, the UPF may number the downstream data packet from 0 or 1.

The sending mode of the downlink double-broadcast data packet is as follows: the UPF carries the data part and the N3 sequence number in different fields of a general packet radio service (general packet radio service, GPRS) tunneling protocol (GPRS tunneling protocol, GTP) (GTP-U) and sends the data part and the N3 sequence number to the access network equipment together, for example, the data part is placed in the load part of the GTP-U, and the N3 sequence number is placed in the subheader of the GTP-U. Optionally, the N3 sequence number is carried in a data frame of the downlink PDU session information sent by the UPF to the access network device.

It should be noted that, the N3 sequence number is different from the GTP sequence number of the GTP-U header in the prior art, the N3 sequence number is different from the GTP sequence number allocated by the UPF sequentially for the data of all QoS flows in the PDU session, and the N3 sequence number is also different from the N3 sequence number allocated sequentially for the data of only a single QoS flow in the prior art GTP-U header. Note that, the UPF may carry flag information in the first downstream bi-cast packet or the first set number of downstream bi-cast packets, where the flag information is used to indicate that the bi-cast packet is sent. Or, before sending the first downlink bi-cast data packet, the UPF continuously sends one or more instructions for ending sending the uni-cast packet by the UPF, that is, sends one or more instructions for instructing the UPF to start sending the bi-cast packet, so as to inform the source access network device: the UPF will start sending the bi-cast packet.

After receiving a downlink double-broadcast data packet (may be a first downlink double-broadcast data packet or a second downlink double-broadcast data packet, etc., for example, the source access network device may identify the marking information carried in the downlink double-broadcast data packet), obtain an N3 sequence number carried by the downlink double-broadcast data packet, and then determine a mapping relationship between the N3 sequence number and the PDCP SN according to the PDCP SN and the N3 sequence number corresponding to the downlink double-broadcast data packet. For example, the source access network device receives a first downlink dual-broadcast data packet, where the downlink dual-broadcast data packet carries an N3 sequence number of 1, and if the PDCP SN that has been used or allocated by the source access network device is 100, and if the PDCP SN corresponding to the downlink dual-broadcast data packet is 101, it is determined that the mapping relationship between the N3 sequence number and the PDCP SN is: n3 sequence number 1 corresponds to PDCP sequence number 101. And if the subsequent source access network equipment receives other downlink double-broadcast data packets, determining the PDCP SN corresponding to the downlink double-broadcast data packet according to the N3 sequence number carried by the downlink double-broadcast data packet. For example, if a downlink dual-broadcast data packet with the N3 sequence number of 100 is subsequently received, the source access network device adds the PDCP SN 200 to the downlink dual-broadcast data packet.

After receiving the indication information, the target access network device can newly add the PDCP SN into the downlink bi-cast data packet received from the UPF according to the mapping relationship between the N3 sequence number and the PDCP SN indicated by the indication information. For example, when the target access network device receives a downlink dual-broadcast data packet with the N3 sequence number of 100, the target access network device adds the PDCP SN 200 to the downlink dual-broadcast data packet according to the mapping relationship between the N3 sequence number and the PDCP SN indicated by the indication information. One possible implementation is: the target access network device receives the downlink double-broadcast data packet (for example, GTP-U data packet, the target access network device extracts the IP packet from the GTP-U data packet as PDCP SDU, then adds PDCP SN to generate PDCP PDU, and then sends it to the terminal device through protocol layer below PDCP.)

It should be noted that, if the target access network device receives the downlink dual-broadcast data packets from the UPF before receiving the indication information, the target access network device may buffer the downlink dual-broadcast data packets first, and then determine PDCP SN for the buffered downlink dual-broadcast data packets according to the indication information after receiving the indication information.

As an implementation method, the indication information carries a mapping relationship between the N3 sequence number and the PDCP SN. As another implementation method, the indication information carries a difference between the N3 sequence number and the PDCP SN, or carries a difference between the PDCP SN and the N3 sequence number. It can be understood that the indication information is used to indicate the N3 sequence number and the PDCP SN corresponding to the N3 sequence number.

Step 510, the terminal device sends a handover complete message to the target access network device. Accordingly, the target access network device receives the handover complete message.

After the terminal device sends the handover complete message to the target access network device, the terminal device may send a PDCP status report to the target access network device, and the terminal device may send an uplink data packet to the target access network device.

In step 511, the target access network device sends a path switching request message to the AMF. Accordingly, the AMF receives the path switching request message.

Alternatively, the target access network device may carry an indication to stop downstream bi-casting in the path switch request message, and notify the SMF via the AMF.

In step 512, the amf notifies the UPF of path switching via the SMF, and the UPF stops sending the downlink dual-broadcast message.

Alternatively, the AMF informs the UPF via the SMF to stop downstream bi-casting.

In step 513, the amf sends a path switch response message to the target access network device. Accordingly, the target access network device receives the path switching response message.

Based on the scheme, the UPF uniformly distributes N3 sequence numbers for the downlink double-broadcast data packets of the QoS stream which receives double broadcasting, and the N3 sequence numbers are carried in the downlink double-broadcast data packets and are sent to the source access network equipment and the target access network equipment. Subsequently, the source access network device and the target access network device can determine PDCP SNs corresponding to the downlink dual-cast data packet based on a mapping relationship between the N3 sequence number and the PDCP SNs, and newly add the N3 sequence number in the downlink dual-cast data packet. Because the source access network device and the target access network device determine the PDCP SNs corresponding to the received downlink double-broadcast data packets based on the same mapping relation, the same PDCP SNs are determined for the same downlink double-broadcast data packet, so that the terminal device is prevented from discarding the data packet which is not repeatedly received when the packet loss occurs, the terminal device is prevented from missing the information from the access network device, the loss or interruption of the data in the switching process is avoided, and the reliability of the data transmission is improved.

In the above scheme, in the step 509, the source access network device sends the indication information to the target access network device through an Xn interface between the source access network device and the target access network device. As an alternative implementation method of the above step 509, the source access network device may send the indication information to the terminal device, for example, the source access network device carries the indication information through the handover message of the above step 508, and then the terminal device sends the indication information to the target access network device, for example, the terminal device may send the indication information through the handover complete message of the above step 510.

In the above scenario, the information carried in step 505 may also be carried in step 504, in which case it is not necessary to perform step 505.

In the embodiment corresponding to fig. 5, the target access network device determines the information of the QoS flow group receiving the double broadcasting according to the information of the QoS flow group requesting the double broadcasting. As an alternative implementation method, the AMF may request the information of the QoS flow group for bi-casting, determine the information of the QoS flow group for bi-casting, and then carry the information of the QoS flow group for bi-casting in step 503. Thus, the step 504 does not need to carry information of the QoS flow group accepting the bi-cast.

Referring to fig. 6, a schematic diagram of a data transmission method according to an embodiment of the present application is provided. The scheme is a sending method of downlink double-broadcast data packets based on an Xn switching process.

The method comprises the following steps:

in step 601, the terminal device sends a measurement report to the source access network device. Accordingly, the source access network device receives the measurement report.

In step 602, the source access network device sends a handover request message to the target access network device. Accordingly, the target access network device receives the handover request message.

The handoff request message carries information of a requested-to-multicast QoS flow group that includes one or more QoS flow groups, each QoS flow group associated with a data radio bearer.

In step 603, the target access network device determines a QoS flow group that accepts bi-casting.

And the target access network equipment determines the QoS flow group accepting the double broadcasting according to the information of the QoS flow group requesting the double broadcasting.

The specific description of the information of the QoS flow group accepting bi-casting may refer to the foregoing description, and will not be repeated.

In step 604, the target access network device sends a bi-cast request message to the AMF. Accordingly, the AMF receives the bi-cast request message.

In step 605, the amf configures the UPF with information of the QoS flow group accepting the bicasting via the SMF.

Subsequently, the UPF allocates the N3 sequence numbers uniformly for the QoS flows indicated by the information of the QoS flow group accepting the bicast. For example, for each QoS flow group in the QoS flow group that accepts the bicast, when the UPF transmits a packet of a QoS flow in the QoS flow group, the UPF transmits the packet of the QoS flow with the N3 sequence number allocated in sequence in a row.

The amf sends a bi-cast acknowledgement message to the target access network device, step 606. Accordingly, the target access network device receives the bi-cast acknowledgement message.

The bi-cast acknowledgement message carries information of the QoS flow group accepting bi-casting.

In step 607, the target access network device sends a handover confirm message to the source access network device. Accordingly, the source access network device receives the handover confirm message.

The handoff confirm message carries information of the QoS flow group accepting the bicasting.

Steps 608 to 613 are the same as steps 508 to 513, and are not repeated.

In the above solution, in the above step 609, the source access network device sends the above indication information to the target access network device through an Xn interface between the source access network device and the target access network device. As an alternative implementation method of the above step 609, the source access network device may send the indication information to the terminal device, for example, the source access network device carries the indication information through the handover message of the above step 608, and then the terminal device sends the indication information to the target access network device, for example, the terminal device may send the indication information through the handover complete message of the above step 610.

In the embodiment corresponding to fig. 6, the target access network device determines the information of the QoS flow group receiving the double broadcasting according to the information of the QoS flow group requesting the double broadcasting. As an alternative implementation method, the AMF may request the information of the dual-cast QoS flow group, and determine the information of the dual-cast QoS flow group. For example, step 603 is not performed, the information of the QoS flow group requesting for the dual-cast is carried in step 604, then the AMF determines the information of the QoS flow group accepting for the dual-cast according to the information of the QoS flow group requesting for the dual-cast, and sends the information of the QoS flow group accepting for the dual-cast to the target access network device through step 606.

In the embodiment corresponding to fig. 5 or fig. 6, the information of the QoS flow group accepting the bi-cast is configured to the UPF in the handover process. As another implementation method, the information of the QoS flow group accepting the bicasting may be configured to the UPF before the handover, so that the UPF may start to send downlink bicasting data packets to the source access network device and the target access network device before the handover, so that the target access network device may receive the downlink data packets from the UPF in advance, and when the downlink data packets cannot be sent to the terminal device correctly through the source access network device (for example, because the handover is about to happen, the link between the terminal device and the source access network device is abnormal), the downlink data packets may also be sent to the terminal device through the target access network device, so as to avoid that the data packets sent by the UPF cannot reach the terminal device.

As an implementation method, the first measurement report corresponds to a first event detected by the terminal device, and the second measurement report corresponds to a second event detected by the terminal device, and a trigger threshold of the first event is lower than a trigger threshold of the second event. For example, the channel quality trigger threshold for the first event is lower than the channel quality trigger threshold for the second event.

1) Before the handover occurs:

When the source access network equipment receives the first measurement report from the terminal equipment, the source access network equipment informs the SMF to perform the double-broadcast transmission configuration on the UPF. After the SMF completes the configuration of the dual-broadcast transmission on the UPF, the UPF may start sending downlink dual-broadcast data packets to the source access network device and the target access network device, and then the source access network device may determine a mapping relationship between the N3 sequence number and the PDCP SN. The process is similar to steps 501 to 506 in fig. 5 or to steps 601 to 605 in fig. 6.

2) Switching occurs:

when the source access network equipment receives the second measurement report from the terminal equipment, the source access network equipment triggers the switching flow of the prior art, and the switching of the terminal equipment from the access source access network equipment to the access target access network equipment is completed.

In the handover process, the source access network device may send indication information to the target access network device, where the indication information is used to indicate a mapping relationship between the N3 sequence number and the PDCP SN. For example, in the scenario based on N2 handover, the source access network device carries the indication information in the handover request sent to the AMF, and then the AMF carries the indication information in the handover request message sent to the target access network device. For another example, in the context of an Xn-based handover, the source access network device carries the indication information in a handover request message sent to the target access network device.

Compared with the embodiments corresponding to fig. 5 and fig. 6, the solution can implement the advanced dual-cast configuration for the UPF, and the source access network device can send the indication information for indicating the mapping relationship to the target access network device in advance, so that the target access network device can determine the PDCP SN corresponding to the downlink dual-cast data packet received from the UPF earlier, thereby being beneficial to reducing the delay of sending the downlink dual-cast data packet to the terminal device.

The embodiment of the present application is described by taking downlink transmission as an example, and the embodiment of the present application may be applied to uplink transmission as well.

Referring to fig. 7, a schematic diagram of a data transmission method according to an embodiment of the present application is provided, where the method includes the following steps:

in step 701, the terminal device sends a first uplink dual-broadcast data packet to the access network device, where the first downlink dual-broadcast data packet carries third data and a third PDCP sequence number. Correspondingly, the access network device receives the first uplink double-broadcast data packet.

Step 702, the access network device determines a third sequence number corresponding to the third PDCP sequence number.

The third sequence number may be an N3 sequence number or other predetermined sequence numbers, etc.

It should be noted that, the initial number of the N3 sequence number may be predetermined, or may be dynamically configured. For example, the initial value of the upstream N3 sequence number may be indicated to the UPF by the source access network device.

In step 703, the access network device sends a second uplink dual-broadcast packet to the UPF, where the second uplink dual-broadcast packet carries third data and a third sequence number. Correspondingly, the UPF receives the second uplink double-broadcast data packet.

The access network device may be a source access network device or a target access network device, that is, the terminal device sends the same uplink bi-cast data packet to the source access network device and the target access network device.

Based on the scheme, the terminal equipment uniformly distributes sequence numbers for the uplink data bi-cast data packets, and then the source access network equipment and the target access network equipment map the PDCP sequence numbers distributed by the terminal equipment to N3 sequence numbers, so that the source access network equipment and the target access network equipment can be ensured to distribute the same N3 sequence numbers for the same uplink data bi-cast data packets, further, the situation that the UPF discards the data packets which are not repeatedly received when the UPF is de-duplicated is avoided, the UPF does not miss information from the access network equipment, the data loss or interruption in the switching process is avoided, and the reliability of data transmission is improved.

Subsequently, the UPF performs a deduplication operation based on the N3 sequence number.

The method for determining the mapping relationship between the PDCP sequence number and the N3 sequence number in the uplink data transmission process is similar to the method for determining the mapping relationship between the PDCP sequence number and the N3 sequence number in the downlink data transmission process, and will not be described again.

Referring to fig. 8, a schematic diagram of a communication device is provided in an embodiment of the present application. The communication apparatus is configured to implement the steps corresponding to the access network device or the user plane network element in the foregoing embodiments, as shown in fig. 8, where the communication apparatus 800 includes a transceiver unit 810 and a processing unit 820.

In a first embodiment, the communication device is configured to implement each step of the corresponding access network device in each embodiment described above:

a transceiver unit 810, configured to receive a first downlink bi-cast data packet from a user plane network element, where the first downlink bi-cast data packet carries first data and a first sequence number; sending a second downlink double-broadcast data packet to terminal equipment, wherein the second downlink double-broadcast data packet carries the first data and a PDCP sequence number of a first packet data convergence protocol; a processing unit 820, configured to determine the first PDCP sequence number corresponding to the first sequence number.

For other operations performed by the communication device, reference may be made to the description related to the foregoing method embodiment, which is not repeated here.

In a second embodiment, the communication device is configured to implement each step of the corresponding user plane network element in each embodiment described above:

a transceiver 810, configured to receive configuration information, where the configuration information carries information of a QoS flow group that accepts dual-casting, where the QoS flow group that accepts dual-casting includes one or more QoS flow groups, and a first QoS flow group is any QoS flow group in the QoS flow group that accepts dual-casting; a processing unit 820, configured to sequentially allocate an N3 sequence number to the downstream bi-cast data packets of the first QoS flow group.

Optionally, the communication device may further include a storage unit, where the storage unit is configured to store data or instructions (which may also be referred to as codes or programs), and the respective units may interact or be coupled with the storage unit to implement the corresponding methods or functions. For example, the processing unit 820 may read data or instructions in a storage unit, so that the communication device implements the method in the above-described embodiment.

It should be understood that the above division of units in the communication device is merely a division of logic functions, and may be fully or partially integrated into one physical entity or may be physically separated. And the units in the communication device may all be implemented in the form of software calls via the processing element; or can be realized in hardware; it is also possible that part of the units are implemented in the form of software, which is called by the processing element, and part of the units are implemented in the form of hardware. For example, each unit may be a processing element that is set up separately, may be implemented integrally in a certain chip of the communication device, or may be stored in a memory in the form of a program, and the function of the unit may be called and executed by a certain processing element of the communication device. Furthermore, all or part of these units may be integrated together or may be implemented independently. The processing element described herein may in turn be a processor, which may be an integrated circuit with signal processing capabilities. In implementation, each step of the above method or each unit above may be implemented by an integrated logic circuit of hardware in a processor element or in the form of software called by a processing element.

In one example, the unit in any of the above communication devices may be one or more integrated circuits configured to implement the above methods, such as: one or more specific integrated circuits (application specific integrated circuit, ASIC), or one or more microprocessors (digital singnal processor, DSP), or one or more field programmable gate arrays (field programmable gate array, FPGA), or a combination of at least two of these integrated circuit forms. For another example, when the unit in the communication device may be implemented in the form of a processing element scheduler, the processing element may be a general purpose processor, such as a central processing unit (central processing unit, CPU) or other processor that may invoke the program. For another example, the units may be integrated together and implemented in the form of a system-on-a-chip (SOC).

Referring to fig. 9, a schematic diagram of a communication apparatus provided in an embodiment of the present application is used to implement the operation of the access network device or the user plane network element in the above embodiment. As shown in fig. 9, the communication apparatus includes: processor 910 and interface 930, and optionally, memory 920. The interface 930 is used to enable communication with other devices.

The method performed by the access network device or the user plane network element in the above embodiment may be implemented by the processor 910 invoking a program stored in a memory (which may be a memory 920 in the access network device or the user plane network element or an external memory). That is, the access network device or the user plane network element may include a processor 910, where the processor 910 may execute the method performed by the access network device or the user plane network element in the above method embodiment by calling a program in a memory. The processor here may be an integrated circuit with signal processing capabilities, such as a CPU. The access network device or user plane network element may be implemented by one or more integrated circuits configured to implement the above methods. For example: one or more ASICs, or one or more microprocessor DSPs, or one or more FPGAs, etc., or a combination of at least two of these integrated circuit forms. Alternatively, the above implementations may be combined.

In particular, the functions/implementation of the transceiver unit 810 and the processing unit 820 in fig. 8 may be implemented by the processor 910 in the communication apparatus 900 shown in fig. 9 invoking computer executable instructions stored in the memory 920. Alternatively, the functions/implementation procedure of the processing unit 820 in fig. 8 may be implemented by the processor 910 in the communication apparatus 900 shown in fig. 9 calling computer-executable instructions stored in the memory 920, the functions/implementation procedure of the transceiver unit 810 in fig. 8 may be implemented by the interface 930 in the communication apparatus 900 shown in fig. 9, and exemplary, the functions/implementation procedure of the transceiver unit 810 may be implemented by the processor calling program instructions in the memory to drive the interface 930.

Those of ordinary skill in the art will appreciate that: the first, second, etc. numbers referred to in this application are merely for convenience of description and are not intended to limit the scope of the embodiments of the present application, but also to indicate the sequence. "and/or", describes an association relationship of an association object, and indicates that there may be three relationships, for example, a and/or B, and may indicate: a exists alone, A and B exist together, and B exists alone. The character "/" generally indicates that the context-dependent object is an "or" relationship. "at least one" means one or more. At least two means two or more. "at least one," "any one," or the like, refers to any combination of these items, including any combination of single item(s) or plural items(s). For example, at least one of a, b, or c (species ) may represent: a, b, c, a-b, a-c, b-c, or a-b-c, wherein a, b, c may be single or plural. "plurality" means two or more, and the like.

It should be understood that, in various embodiments of the present application, the sequence numbers of the foregoing processes do not mean the order of execution, and the order of execution of the processes should be determined by the functions and internal logic of the processes, and should not constitute any limitation on the implementation process of the embodiments of the present invention.

It will be clear to those skilled in the art that, for convenience and brevity of description, specific working procedures of the above-described systems, apparatuses and units may refer to corresponding procedures in the foregoing method embodiments, and are not repeated herein.

In the above embodiments, it may be implemented in whole or in part by software, hardware, firmware, or any combination thereof. When implemented in software, may be implemented in whole or in part in the form of a computer program product. The computer program product includes one or more computer instructions. When loaded and executed on a computer, produces a flow or function in accordance with embodiments of the present application, in whole or in part. The computer may be a general purpose computer, a special purpose computer, a computer network, or other programmable apparatus. The computer instructions may be stored in or transmitted from one computer-readable storage medium to another, for example, by wired (e.g., coaxial cable, optical fiber, digital Subscriber Line (DSL)), or wireless (e.g., infrared, wireless, microwave, etc.). The computer readable storage medium may be any available medium that can be accessed by a computer or a data storage device including one or more servers, data centers, etc. that can be integrated with the available medium. The usable medium may be a magnetic medium (e.g., a floppy disk, a hard disk, a magnetic tape), an optical medium (e.g., a DVD), or a semiconductor medium (e.g., a Solid State Disk (SSD)), or the like.

The various illustrative logical blocks and circuits described in the embodiments of the present application may be implemented or performed with a general purpose processor, a digital signal processor, an Application Specific Integrated Circuit (ASIC), a Field Programmable Gate Array (FPGA) or other programmable logic device, discrete gate or transistor logic, discrete hardware components, or any combination thereof designed to perform the functions described herein. A general purpose processor may be a microprocessor, but in the alternative, the general purpose processor may be any conventional processor, controller, microcontroller, or state machine. A processor may also be implemented as a combination of computing devices, e.g., a digital signal processor and a microprocessor, a plurality of microprocessors, one or more microprocessors in conjunction with a digital signal processor core, or any other similar configuration.

The steps of a method or algorithm described in the embodiments of the present application may be embodied directly in hardware, in a software element executed by a processor, or in a combination of the two. The software cells may be stored in random access Memory (Random Access Memory, RAM), flash Memory, read-Only Memory (ROM), EPROM Memory, EEPROM Memory, registers, hard disk, a removable disk, a CD-ROM, or any other form of storage medium known in the art. In an example, a storage medium may be coupled to the processor such that the processor can read information from, and write information to, the storage medium. In the alternative, the storage medium may be integral to the processor. The processor and the storage medium may reside in an ASIC.

These computer program instructions may also be loaded onto a computer or other programmable data processing apparatus to cause a series of operational steps to be performed on the computer or other programmable apparatus to produce a computer implemented process such that the instructions which execute on the computer or other programmable apparatus provide steps for implementing the functions specified in the flowchart flow or flows and/or block diagram block or blocks.

In one or more exemplary designs, the functions described herein may be implemented in hardware, software, firmware, or any combination of the three. If implemented in software, the functions may be stored on a computer-readable medium or transmitted as one or more instructions or code on the computer-readable medium. Computer readable media includes both computer storage media and communication media that facilitate transfer of computer programs from one place to another. A storage media may be any available media that can be accessed by a general purpose or special purpose computer. For example, such computer-readable media may include, but is not limited to, RAM, ROM, EEPROM, CD-ROM or other optical disk storage, magnetic disk storage or other magnetic storage devices, or any other medium that may be used to carry or store program code in the form of instructions or data structures and other data structures that may be read by a general or special purpose computer, or a general or special purpose processor. Further, any connection is properly termed a computer-readable medium, e.g., if the software is transmitted from a website, server, or other remote source via a coaxial cable, fiber optic computer, twisted pair, digital Subscriber Line (DSL), or wireless such as infrared, radio, and microwave, and is also included in the definition of computer-readable medium. The disks (disks) and disks include compact disks, laser disks, optical disks, digital versatile disks (English: digital Versatile Disc; DVD), floppy disk and blu-ray disk where disks usually reproduce data magnetically, while disks usually reproduce data optically with lasers. Combinations of the above may also be included within the computer-readable media.

Those of skill in the art will appreciate that in one or more of the examples described above, the functions described herein may be implemented in hardware, software, firmware, or any combination thereof. When implemented in software, these functions may be stored on or transmitted over as one or more instructions or code on a computer-readable medium. Computer-readable media includes both computer storage media and communication media including any medium that facilitates transfer of a computer program from one place to another. A storage media may be any available media that can be accessed by a general purpose or special purpose computer.

The foregoing embodiments have been provided for the purpose of illustrating the technical solution and advantageous effects of the present application in further detail, and it should be understood that the foregoing embodiments are merely illustrative of the present application and are not intended to limit the scope of the present application, and any modifications, equivalents, improvements, etc. made on the basis of the technical solution of the present application should be included in the scope of the present application. The foregoing description of the specification may enable any person skilled in the art to make or use the content of the application, and any modifications may be made based on the disclosure as will be apparent to the person skilled in the art, and the basic principles described herein may be applied to other variations without departing from the spirit and scope of the invention of the application. Thus, the disclosure is not limited to the embodiments and designs described herein but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Although the present application has been described in connection with specific features and embodiments thereof, it will be apparent that various modifications and combinations can be made without departing from the spirit and scope of the application. Accordingly, the specification and drawings are merely exemplary illustrations of the present application as defined in the appended claims and are considered to cover any and all modifications, variations, combinations, or equivalents that fall within the scope of the present application. It will be apparent to those skilled in the art that various modifications and variations can be made in the present application without departing from the scope of the application. Thus, if such modifications and variations of the present application fall within the scope of the claims and the equivalents thereof, the present application is intended to include such modifications and variations as well.

Claims

A data transmission method, comprising:

the access network equipment receives a first downlink double-broadcast data packet from a user plane network element, wherein the first downlink double-broadcast data packet carries first data and a first sequence number;

the access network equipment determines a first packet data convergence protocol PDCP sequence number corresponding to the first sequence number;

the access network device sends a second downlink double-broadcast data packet to the terminal device, wherein the second downlink double-broadcast data packet carries the first data and the first PDCP sequence number.
The method of claim 1, wherein the first sequence number is an N3 sequence number.
The method of claim 1 or 2, wherein the access network device determining a first PDCP sequence number corresponding to the first sequence number comprises:

the access network equipment determines a first PDCP COUNT value corresponding to the first sequence number;

and the access network equipment determines the first PDCP sequence number corresponding to the first PDCP COUNT value.
A method according to any of claims 1-3, wherein the access network device is a source access network device;

before the source access network device receives the first downlink bi-cast data packet from the user plane network element, the source access network device further includes:

the source access network equipment receives a third downlink double-broadcast data packet from the user plane network element, wherein the third downlink double-broadcast data packet carries second data and a second sequence number;

and the source access network equipment determines a mapping relation according to the second sequence number and the second PDCP sequence number corresponding to the third downlink double-broadcast data packet, wherein the mapping relation is used for determining the first PDCP sequence number corresponding to the first sequence number.
The method as recited in claim 4, further comprising:

And the source access network equipment sends indication information to the target access network equipment, wherein the indication information is used for indicating the mapping relation.
The method of claim 5, wherein,

the indication information carries the second sequence number and the second PDCP sequence number corresponding to the second sequence number; or alternatively, the process may be performed,

the indication information carries the difference value between the second sequence number and the second PDCP sequence number; or alternatively, the process may be performed,

the indication information carries a second PDCP COUNT value corresponding to the second sequence number and the second sequence number, and the second PDCP COUNT value corresponds to the second PDCP sequence number; or alternatively, the process may be performed,

the indication information carries a difference value between the second sequence number and a second PDCP COUNT value, where the second PDCP COUNT value corresponds to the second PDCP sequence number.
The method of any of claims 4-6, further comprising:

the source access network device requests first to first equipment, wherein the first request carries information of a QoS flow group requesting for double broadcasting, and the first equipment is target access network equipment or a mobility management network element;

the source access network device receives a first response from the first device, wherein the first response carries information of a QoS flow group accepting double broadcasting, and the QoS flow group accepting double broadcasting is part or all of the QoS flow group requesting double broadcasting.
A method according to any of claims 1-3, wherein the access network device is a target access network device; the method further comprises the steps of:

the target access network equipment receives indication information from source access network equipment, wherein the indication information is used for indicating a mapping relation, and the mapping relation is used for determining the first PDCP sequence number corresponding to the first sequence number.
The method as recited in claim 8, further comprising:

the target access network equipment receives information of QoS flow groups requesting double broadcasting;

the target access network equipment determines the information of the QoS stream group receiving the double broadcasting according to the information of the QoS stream group requesting the double broadcasting;

and the target access network equipment sends the information of the QoS flow group accepting the double broadcasting to a session management network element.
The method of claim 9, wherein the target access network device receiving information of the QoS flow group requesting bi-casting comprises:

the target access network equipment receives a switching request message from source access network equipment, wherein the switching request message carries the information of the QoS stream group requesting the double broadcasting; or alternatively, the process may be performed,

and the target access network equipment receives a switching request message from the mobility management network element, wherein the switching request message carries the information of the QoS flow group requesting the double broadcasting.
A data transmission method, comprising:

the user plane network element receives configuration information, wherein the configuration information carries information of a QoS flow group which receives double broadcasting, the QoS flow group which receives double broadcasting comprises one or more QoS flow groups, and a first QoS flow group is any QoS flow group in the QoS flow group which receives double broadcasting;

and the user plane network element sequentially allocates N3 sequence numbers for the downlink double-broadcast data packets of the first QoS flow group.
The method as recited in claim 11, further comprising:

and the user plane network element sends the downlink double-broadcast data packet of the first QoS flow group to source access network equipment and target access network equipment.
The method of claim 12, wherein,

the QoS flows in each QoS flow group in the QoS flow group receiving double broadcasting are associated with the same data radio bearer, and the QoS flows in different QoS flow groups are associated with different data radio bearers.
The method of claim 13 wherein the N3 sequence number is carried in downlink protocol data unit PDU session information in a downlink bi-cast data packet of the first QoS flow group.
A communication device, comprising:

The receiving and transmitting unit is used for receiving a first downlink double-broadcast data packet from the user plane network element, wherein the first downlink double-broadcast data packet carries first data and a first sequence number; sending a second downlink double-broadcast data packet to terminal equipment, wherein the second downlink double-broadcast data packet carries the first data and a PDCP sequence number of a first packet data convergence protocol;

and the processing unit is used for determining the first PDCP sequence number corresponding to the first sequence number.
The apparatus of claim 15, wherein the first sequence number is an N3 sequence number.
The apparatus according to claim 15 or 16, wherein the processing unit is specifically configured to:

determining a first PDCP COUNT value corresponding to the first sequence number;

and determining the first PDCP sequence number corresponding to the first PDCP COUNT value.
The apparatus according to any one of claims 15 to 17, wherein the transceiver unit is further configured to receive a third downlink bi-cast data packet from a user plane network element before receiving the first downlink bi-cast data packet from the user plane network element, the third downlink bi-cast data packet carrying the second data and the second sequence number;

the processing unit is further configured to determine a mapping relationship according to the second sequence number and a second PDCP sequence number corresponding to the third downlink dual-cast data packet, where the mapping relationship is used to determine the first PDCP sequence number corresponding to the first sequence number.
The apparatus of claim 18, wherein the transceiver unit is further configured to send indication information to a target access network device, the indication information being used to indicate the mapping relationship.
The apparatus of claim 19, wherein the device comprises a plurality of sensors,

the indication information carries the second sequence number and the second PDCP sequence number corresponding to the second sequence number; or alternatively, the process may be performed,

the indication information carries the difference value between the second sequence number and the second PDCP sequence number; or alternatively, the process may be performed,

the indication information carries a second PDCP COUNT value corresponding to the second sequence number and the second sequence number, and the second PDCP COUNT value corresponds to the second PDCP sequence number; or alternatively, the process may be performed,

the indication information carries a difference value between the second sequence number and a second PDCP COUNT value, where the second PDCP COUNT value corresponds to the second PDCP sequence number.
The apparatus of any of claims 18 to 20, wherein the transceiver unit is further configured to:

a first request carries information of a quality of service (QoS) flow group requesting bi-casting from a first device, wherein the first device is a target access network device or a mobility management network element;

a first response from the first device is received, wherein the first response carries information of a QoS flow group accepting double broadcasting, and the QoS flow group accepting double broadcasting is part or all of the QoS flow group requesting double broadcasting.
The apparatus of any of claims 15 to 17, wherein the transceiver unit is further configured to:

and receiving indication information from source access network equipment, wherein the indication information is used for indicating a mapping relation, and the mapping relation is used for determining the first PDCP sequence number corresponding to the first sequence number.
The apparatus of claim 22, wherein the transceiver unit is further configured to receive information of a QoS flow group requesting bi-casting; transmitting information of QoS stream group for accepting double broadcasting to session management network element;

the processing unit is further configured to determine, according to the information of the QoS flow group requesting for the bicasting, information of the QoS flow group accepting for the bicasting.
The apparatus of claim 23, wherein the transceiver unit is specifically configured to:

receiving a switching request message from source access network equipment, wherein the switching request message carries information of the QoS stream group requesting double broadcasting; or alternatively, the process may be performed,

and receiving a switching request message from the mobility management network element, wherein the switching request message carries the information of the QoS flow group requesting the double broadcasting.
A communication device, comprising:

a transceiver unit, configured to receive configuration information, where the configuration information carries information of a QoS flow group that accepts dual-casting, where the QoS flow group that accepts dual-casting includes one or more QoS flow groups, and a first QoS flow group is any QoS flow group in the QoS flow group that accepts dual-casting;

And the processing unit is used for sequentially distributing N3 sequence numbers to the downlink double-broadcast data packets of the first QoS flow group.
The apparatus of claim 25, wherein the transceiver unit is further configured to send downstream bi-cast data packets of the first QoS flow group to a source access network device and a target access network device.
The apparatus of claim 26, wherein the device comprises,

the QoS flows in each QoS flow group in the QoS flow group receiving double broadcasting are associated with the same data radio bearer, and the QoS flows in different QoS flow groups are associated with different data radio bearers.
The apparatus of claim 27, wherein the N3 sequence number is carried in downlink protocol data unit PDU session information in a downlink bi-cast data packet of the first QoS flow group.
A communication device, comprising: a processor coupled to a memory for storing a program or instructions that, when executed by the processor, cause the apparatus to perform the method of any one of claims 1 to 10.
A communication device, comprising: a processor coupled to a memory for storing a program or instructions that, when executed by the processor, cause the apparatus to perform the method of any of claims 11 to 14.
A communication device for performing the method of any of claims 1 to 10.
A communication device for performing the method of any of claims 11 to 14.
A communication system comprising a communication device according to any of claims 15-24, 29, 31 and a communication device according to any of claims 25-28, 30, 32.
A computer readable storage medium comprising instructions which, when run on a computer, cause the computer to perform the method of any of claims 1 to 14.
A computer program product comprising instructions which, when executed, implement the method of any one of claims 1 to 14.