CN114390619B

CN114390619B - Transmission method and device

Info

Publication number: CN114390619B
Application number: CN202011133038.8A
Authority: CN
Inventors: 周叶; 周锐
Original assignee: Datang Mobile Communications Equipment Co Ltd
Current assignee: Datang Mobile Communications Equipment Co Ltd
Priority date: 2020-10-21
Filing date: 2020-10-21
Publication date: 2024-02-09
Anticipated expiration: 2040-10-21
Also published as: CN114390619A; WO2022083627A1

Abstract

The invention provides a transmission method and equipment, belonging to the technical field of wireless communication, wherein the method applied to a first wireless access network element comprises the following steps: the first radio access network element sends first information to the terminal, where the first information is used to indicate a corresponding relation between a PDCP count value of a first bearer and a PDCP count value of a second bearer of the terminal, or indicates a corresponding relation between a PDCP sequence number of the first bearer and a PDCP sequence number of the second bearer of the terminal. The wireless access network informs the corresponding relation between the PDCP count values or the serial numbers of the two wireless bearers before and after the user terminal is switched, thereby ensuring the service continuity.

Description

Transmission method and device

Technical Field

The present invention relates to the field of wireless communications technologies, and in particular, to a transmission method and apparatus.

Background

There are scenarios in which multiple User terminals (UEs) request the same downlink service data in a wireless communication system. For this scenario, in order to reduce radio resource consumption as much as possible, a multicast mechanism is proposed in the related art, which allows a network to transmit a single piece of downlink data using a specific radio resource, and a plurality of user terminals simultaneously receive the piece of downlink data. In contrast, conventional downstream data that can only be received by one user terminal is called a unicast mechanism.

In order to cope with the complex air interface environment and diversified service transmission quality of service (Quality of Service, qoS) requirements, the related art proposes the following requirements: for each downstream data stream that can be sent by a Point-to-multipoint (Point to Multipoint, PTM) mechanism, the network side can still optionally send it to a specific user terminal in a Point-to-Point (PTP) mode. That is, the network should be able to dynamically adjust the downlink transmission mode between PTM and PTP modes for a certain user terminal.

In addition, in the switching process for a certain user terminal, for downlink data which is not received by the user terminal through the switched source cell, the switched source node can forward the downlink data to the target cell for transmission, namely 'data forwarding'; if the downlink data are multicast data, even if the downlink data are sent in the source cell in the PTM mode, since only the switched user terminal needs to receive the data, the data still should be sent in the PTP mode, and new data are sent in the PTM mode after the user terminal receives the data successfully.

Disclosure of Invention

The invention provides a transmission method and equipment, which are used for solving the problem that the data transmission is discontinuous easily when the switching of a downlink transmission mode exists and/or the switching of a network element where a PDCP (packet data convergence protocol) is changed exists in the current downlink data transmission process.

In order to solve the above technical problem, the present invention provides a transmission method applied to a first radio access network element, including:

the first radio access network element sends first information to the terminal, where the first information is used to indicate a corresponding relation between a PDCP count value of a first bearer and a PDCP count value of a second bearer of the terminal, or indicates a corresponding relation between a PDCP sequence number of the first bearer and a PDCP sequence number of the second bearer of the terminal.

Optionally, the first bearer is a source radio bearer or a temporary radio bearer, and the second bearer is a target radio bearer.

Optionally, the first information includes an offset between PDCP count values of the first bearer and the second bearer or an offset between PDCP sequence numbers of the first bearer and the second bearer.

Optionally, the first information includes second information and third information, the second information is a count value or a sequence number of a first PDCP data packet in the first bearer, and the third information is a count value or a sequence number of a second PDCP data packet in the second bearer; the first PDCP data packet is a data packet which is received in the first bearing in a cut-off way, and the second PDCP data packet is a data packet which is received in the second bearing in a start way;

The service data contained in the first PDCP data packet and the second PDCP data packet are both first service data.

Optionally, after the first radio access network element sends the first information to the terminal, the method further includes:

the first radio access network element releases the first bearer.

Optionally, before the first radio access network element sends the first information to the terminal, the method further includes:

the first wireless access network element receives fourth information sent by a user plane function module in a core network, wherein the fourth information comprises a first mark aiming at first service data;

the first wireless access network element receives fifth information sent by a second wireless access network element, wherein the fifth information comprises a second mark aiming at the first service data;

one of the first mark and the second mark is a start mark, and the other is an end mark.

Optionally, the fifth information further includes a count value or a sequence number of a first PDCP packet in the first bearer, where the first PDCP packet is a data packet in the first bearer that is received by the first bearer.

Optionally, the method further comprises:

and the first wireless access network element determines the first information according to the fourth information and the fifth information.

Optionally, before the step of sending the first information to the terminal by the first radio access network element, the method further includes:

the first radio access network element receives sixth information sent by the second radio access network element, where the sixth information is used to indicate the corresponding relationship.

The invention also provides a transmission method, which is applied to the terminal and comprises the following steps:

the terminal receives first information sent by a first radio access network element, wherein the first information is used for indicating the corresponding relation between a PDCP count value of a first bearer and a PDCP count value of a second bearer of the terminal or indicating the corresponding relation between a PDCP sequence number of the first bearer and a PDCP sequence number of the second bearer of the terminal.

Optionally, the method further comprises:

if the terminal has successfully received the third PDCP data packet through the first bearer and successfully received the fourth PDCP data packet through the second bearer, and the count value or sequence number of the fourth PDCP data packet corresponds to the count value or sequence number of the third PDCP data packet, discarding the fourth PDCP data packet;

or,

and if the terminal successfully receives the fourth PDCP data packet through the second bearing and successfully receives the third PDCP data packet through the first bearing, and the count value or the sequence number of the third PDCP data packet corresponds to the count value or the sequence number of the fourth PDCP data packet, discarding the third PDCP data packet.

Optionally, after the terminal receives the first information sent by the first radio access network element, the method further includes:

and if the terminal successfully receives a fifth PDCP data packet through the first bearing, and the count value or the sequence number of the fifth PDCP data packet is larger than or equal to the count value or the sequence number in the first PDCP data packet, discarding the fifth PDCP data packet.

And if the terminal successfully receives the sixth PDCP data packet through the second bearing, and the count value or the sequence number of the sixth PDCP data packet is smaller than or equal to the count value or the sequence number in the second PDCP data packet, discarding the sixth PDCP data packet.

and the terminal releases the first bearing.

The invention also provides a transmission method, which is applied to a user plane function module in a core network and comprises the following steps:

the user plane function module receives seventh information sent by a session management function module in a core network; the seventh information is used for indicating that the downlink transmission address of the terminal is changed from a first address to a second address;

and the user plane function module sends an end mark aiming at the terminal and aiming at the first service data to an access network element corresponding to the first address, and sends a start mark aiming at the terminal and aiming at the first service data to an access network element corresponding to the second address.

The invention also provides a wireless access network element, which comprises a memory, a transceiver and a processor:

A memory for storing a computer program; a transceiver for transceiving data under control of the processor; a processor for reading the computer program in the memory and performing the following operations:

and sending first information to the terminal, wherein the first information is used for indicating the corresponding relation between the PDCP count value of the first bearer and the PDCP count value of the second bearer of the terminal or indicating the corresponding relation between the PDCP sequence number of the first bearer and the PDCP sequence number of the second bearer of the terminal.

Optionally, after the first information is sent to the terminal, the method further includes:

releasing the first bearer.

Optionally, before the first information is sent to the terminal, the method further includes:

receiving fourth information sent by a user plane function module in a core network, wherein the fourth information comprises a first mark aiming at first service data;

receiving fifth information sent by a second radio access network element, wherein the fifth information comprises a second mark aiming at the first service data;

Optionally, the processor is further configured to perform the following operations:

and determining the first information according to the fourth information and the fifth information.

Optionally, before the step of sending the first information to the terminal, the method further includes:

and receiving sixth information sent by the second radio access network element, wherein the sixth information is used for indicating the corresponding relation.

The invention also provides a terminal comprising a memory, a transceiver and a processor:

and receiving first information sent by a network element of a first radio access network, wherein the first information is used for indicating the corresponding relation between the PDCP count value of a first bearer of the terminal and the PDCP count value of a second bearer or indicating the corresponding relation between the PDCP sequence number of the first bearer of the terminal and the PDCP sequence number of the second bearer.

if the third PDCP data packet is successfully received through the first bearer and the fourth PDCP data packet is successfully received through the second bearer, and the count value or the sequence number of the fourth PDCP data packet corresponds to the count value or the sequence number of the third PDCP data packet, discarding the fourth PDCP data packet;

or,

and if the fourth PDCP data packet is successfully received through the second bearer and the third PDCP data packet is successfully received through the first bearer, and the count value or the sequence number of the third PDCP data packet corresponds to the count value or the sequence number of the fourth PDCP data packet, discarding the third PDCP data packet.

Optionally, after receiving the first information sent by the first radio access network element, the method further includes:

and if the fifth PDCP data packet is successfully received through the first bearer and the count value or the sequence number of the fifth PDCP data packet is greater than or equal to the count value or the sequence number in the first PDCP data packet, discarding the fifth PDCP data packet.

And if the sixth PDCP data packet is successfully received through the second bearing, and the count value or the sequence number of the sixth PDCP data packet is smaller than or equal to the count value or the sequence number in the second PDCP data packet, discarding the sixth PDCP data packet.

releasing the first bearer.

The invention also provides a user plane function module, which is located in the core network and comprises a memory, a transceiver and a processor:

receiving seventh information sent by a session management function module in the core network; the seventh information is used for indicating that the downlink transmission address of the terminal is changed from a first address to a second address;

and sending an end mark aiming at the terminal and aiming at the first service data to an access network element corresponding to the first address, and sending a start mark aiming at the terminal and aiming at the first service data to an access network element corresponding to the second address.

The invention also provides a wireless access network element, comprising:

a first information sending unit, configured to send first information to a terminal, where the first information is used to indicate a correspondence between a PDCP count value of a first bearer and a PDCP count value of a second bearer of the terminal, or indicate a correspondence between a PDCP sequence number of the first bearer and a PDCP sequence number of the second bearer of the terminal.

The invention also provides a terminal, comprising:

a first information receiving unit, configured to receive first information sent by a first radio access network element, where the first information is used to indicate a correspondence between a PDCP count value of a first bearer and a PDCP count value of a second bearer of the terminal, or indicate a correspondence between a PDCP sequence number of the first bearer and a PDCP sequence number of the second bearer of the terminal.

The present invention also provides a user plane function module, which is located in a core network and includes:

a change indication unit, configured to receive seventh information sent by a session management function module in the core network; the seventh information is used for indicating that the downlink transmission address of the terminal is changed from a first address to a second address;

The data transmission indicating unit is used for sending an end mark aiming at the terminal and aiming at the first service data to the access network element corresponding to the first address, and sending a start mark aiming at the terminal and aiming at the first service data to the access network element corresponding to the second address.

The present invention also provides a processor-readable storage medium storing a computer program for causing the processor to perform any one of the methods described above.

The technical scheme of the invention has the following beneficial effects:

in the embodiment of the invention, the wireless access network informs the corresponding relation between the PDCP count values or the serial numbers of the two wireless bearers before and after the user terminal is switched, thereby ensuring the service continuity.

Drawings

FIG. 1 is a schematic diagram of a 5G NR network architecture;

fig. 2 is a flow chart of a transmission method according to a first embodiment of the invention;

fig. 3 is a flow chart of a transmission method in the second embodiment of the invention;

fig. 4 is a flow chart of a transmission method in the third embodiment of the invention;

fig. 5 is a schematic flow chart of switching between different gNB-CU-UP in a gNB according to an embodiment of the present invention;

Fig. 6 is a schematic flow chart of switching between different gNB-CU-UP in another gNB according to an embodiment of the invention;

fig. 7 is a schematic flow chart of switching between different gnbs in an embodiment of the invention;

FIG. 8 is a flow chart illustrating a handover between different gNBs according to an embodiment of the present invention;

fig. 9 is a schematic structural diagram of a radio access network element in a fourth embodiment of the present invention;

fig. 10 is a schematic structural diagram of a terminal in a fifth embodiment of the present invention;

fig. 11 is a schematic structural diagram of a user plane function module in a sixth embodiment of the present invention;

fig. 12 is a schematic structural diagram of a radio access network element in a seventh embodiment of the present invention;

fig. 13 is a schematic structural diagram of a terminal according to an eighth embodiment of the present invention;

fig. 14 is a schematic structural diagram of a user plane function module according to a ninth embodiment of the present invention.

Detailed Description

In the embodiment of the invention, the term "and/or" describes the association relation of the association objects, which means that three relations can exist, for example, a and/or B can be expressed as follows: 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.

The term "plurality" in the embodiments of the present application means two or more, and other adjectives are similar thereto.

The related art to which the embodiments of the present application relate will be first described below, and some technical problems found by the inventor in analyzing and researching the related art will be briefly described.

1. Regarding air interface PTM transmission:

there are scenarios in a wireless communication system in which multiple user terminals request the same downlink traffic data. In order to reduce the operation cost, a "air interface PTM transmission" function is proposed in the related art, which allows a network side of a radio cell to transmit a single downlink data by using a specific radio resource, and a plurality of user terminals respectively receive and decode the downlink data at the same time, so as to achieve the purpose that the network transmits the downlink data to the plurality of user terminals by using a radio communication resource. This mode is called PTM. In contrast, the network transmits a single downlink data through a specific radio resource, and a transmission scheme in which only one user terminal receives and decodes it is called PTP.

For the conventional PTP mode, a cell may dynamically adjust air interface transmission parameters, such as modulation and coding schemes (Modulation and Coding Scheme, MCS) and beam directions, according to channel quality between a base station and a unicast receiving terminal, so as to improve spectrum utilization efficiency as much as possible. However, for PTM mode, the signaling of the base station needs to take care of as much as possible of all user terminals within the cell range, which may even include user terminals that are not in radio resource control (Radio Resource Control, RRC) connected state and thus the network does not know their location and channel quality. In view of this, the network side often has to employ relatively conservative air interface transmission parameters, such as MCS with lower code rate and omni-directional transmission, i.e. use more air interface resources to transmit less information.

The method is applicable to various multicast scenes, wherein services with strict time delay requirements and relaxed reliability requirements such as live broadcast of a civil video platform and services with relaxed time delay requirements and strict reliability requirements such as police information distribution are available. In the latter case, it is common to have as much as possible that each terminal receiving the service is able to receive all the data in the service.

2. 5G New air interface (NR) network architecture and switching flow:

referring to fig. 1, in the 5g NR network architecture, the method is divided into two parts, i.e. a core network and an access network. In a 5G core network, network elements closely related to handover include AMF, SMF and UPF.

AMF refers to an access and mobility management function module (Access and Mobility Management Function), which is the most central module in the network. Each user terminal is connected to only one AMF at a time.

SMF refers to session management function (Session Management Function). AMF through N _smf The interface manages the SMF, e.g., requests the SMF to set up, modify, and release the traffic context. The service data in 5G is managed in the form of Session (Session) according to the service attribute, the IP route of the backbone network, and the like. Each session is managed by only one SMF. Each session may be subdivided into one or more traffic flows according to QoS requirements of different traffic data.

UPF refers to a user plane function module (User Plane Function). The SMF manages the UPF through the N4 interface, for example, requests the UPF to set up, modify, and release a transmission channel of service data. In principle, the UPF interacts traffic data with external data networks (e.g. backbone networks) via the N6 interface north and interacts traffic data with the access network via the N3 interface south. If the access network is a 5G radio access network, the N3 interface is also referred to as the NG-U interface, i.e. the user plane part of the NG interface. Sometimes a data link is also sent via two UPFs in succession, the interface between which is called the N9 interface.

The 5G access network is also called NG-RAN, and consists of NG-RAN nodes. The node NG-RAN node using the New Radio (NR) technology is also called gNB. Each gNB may be subdivided into one gNB-CU and one or more gNB-DUs, and each gNB-CU may be further subdivided into one gNB-CU-CP and one or more gNB-CU-UPs.

The gNB-CU-CP refers to the Control Plane part of the Central Unit (Central Unit) in the gNB, which is the most Central module in the gNB, and is connected to the AMF via the N2 interface (also called the NG-C interface in this case, i.e. the Control Plane part in the NG interface). Each ue may be connected to multiple gNB-CU-CPs at the same time, but only one of them is the primary gNB-CU-CP, with an N2 context associated with the ue being present between itself and the AMF. Different gNB-CU-CPs are connected through an Xn-C interface. The gNB-CU-CP maps one or more QoS flows in each session into one radio bearer for air interface transmission according to its own policy. The gNB-CU-CP is also responsible for sending RRC (radio resource control ) messages to the user terminals to indicate how they configure the air interface links. These message RRC messages are sent and received through the packet data convergence protocol (Protocol Data Unit, PDCP) layer.

gNB-CU-UP refers to the User Plane (User Plane) section among the Central units (Central Unit) among gNB. The gNB-CU-CP manages the gNB-CU-UP through an E1 interface, for example, requests the gNB-CU-UP to establish, modify and release a transmission channel of service data. In principle, gNB-CU-UP interacts traffic data with UPF via N3 interface north and gNB-DU via F1-U interface south. The gNB-CU-UP mainly comprises a service data adaptation protocol (Service Data Adaptation Protocol, SDAP) and a PDCP layer, wherein the SDAP layer mainly has the function of mapping the service flow into a radio bearer according to the instruction of the gNB-CU-CP. Each radio bearer is processed using one PDCP instance. For downstream data, PDCP instances are numbered for each packet in time order, with the numbered value being referred to as a PDCP COUNT value (PDCP COUNT). The lowest several bits of the PDCP count value are truncated to the sequence Number (Serial Number).

gNB-DU refers to Distributed units (Distributed units) among gNB. gNB-CU-CP manages gNB-DU through F1-C interface, for example, requests gNB-DU to build, modify and release air interface resource. The gNB-DU mainly includes radio link control (Radio Link Control, RLC), medium access control (Media Access Control, MAC), physical (PHY) and Radio Frequency (RF) layers.

Each network layer in the gNB has a corresponding network layer in the user terminal.

The PDCP layer of the receiver has functions of reordering, de-redundancy, etc., that is, it can ensure that data submitted to the SDAP layer is delivered in order and without redundancy. This point of data absence is often guaranteed by the RLC layer, but in some special scenarios it is also guaranteed by the PDCP layer.

Broadly, a handover refers to the operation of changing the transmission path within its 5G network for a service. In a handover procedure involving a network element where a PDCP is located (i.e., originally transmitted by one PDCP, and at a certain time by another PDCP, for example, a handover procedure between different gNB-CUs-UPs inside one gNB, and a handover procedure between different gnbs), in order to promote continuity of downlink traffic sent in PTP, even to achieve a lossless, on-demand delivery requirement, a handover source PDCP will provide to a handover target PDCP data that it receives from a core network but has not yet been delivered to a user terminal, a mechanism called "data forwarding".

In a 5G network, the radio access network node may autonomously decide which traffic flows map to which Radio Bearers (RBs), which makes it possible for its PDCP sequence numbers to be different even when the same piece of traffic data is transmitted, sent by different nodes, or by different means in the same node.

If the mapping of traffic flows on the source side and the destination side to radio bearers is the same (which is the usual case), data forwarding may be performed at the granularity of the radio bearers, where each packet contains a sequence number. At the same time, the source provides a PDCP transfer status summary of the source to the target, wherein the PDCP packets are indicated in the form of a PDCP count value, and the UE has successfully received over the air. In the handover process, the UPF sends an end marker (end marker) to the old path for each session, and all the data is sent through the new path. When the source PDCP receives the end identifier sent by the UPF, it will know that the session has been no longer transmitted through the N3 channel of the source side, and that the packet it previously received is the last packet transmitted through that channel. Thereafter, for each radio bearer, the source PDCP will send an end identity when all data requiring forwarding on that radio bearer has been sent to the target PDCP. The target PDCP, upon receipt of this end identification for the radio bearer, will know that the data forwarding for the radio bearer has ended. Thereafter, for a new packet it receives from the UPF via the SDAP layer, it will continue numbering above the count value of the last packet that the data forwarded. This mechanism ensures that the count value of PDCP is continuous and the content of the packet is continuous when the user terminal receives data.

However, if the data target PDCP of the service is being transmitted in PTM during handover, it cannot adjust the PDCP count value for the user terminal being handed over in order not to interfere with the service continuity of other user terminals receiving the service, and thus the result of "continue numbering above the count value of the last data packet of the data forwarding" cannot be achieved, and thus the service continuity of the user terminal being handed over cannot be guaranteed.

That is, the inventors found that, according to the related art, in the handover involving PDCP change and the PTP-to-PTM conversion, for various reasons, the count value of the source PDCP and the count value of the target PDCP may not coincide for the same data, resulting in no guarantee of service continuity.

The following description of the technical solutions in the embodiments of the present application will be made clearly and completely with reference to the accompanying drawings in the embodiments of the present application, and it is apparent that the described embodiments are only some embodiments of the present application, but not all embodiments. All other embodiments, which can be made by one of ordinary skill in the art without undue burden from the present disclosure, are within the scope of the present disclosure.

The embodiment of the application provides a transmission method and transmission equipment, which are used for ensuring service continuity.

The method and the device are based on the same application, and because the principles of solving the problems by the method and the device are similar, the implementation of the device and the method can be referred to each other, and the repetition is not repeated.

Referring to fig. 2, fig. 2 is a flowchart of a transmission method according to a first embodiment of the present invention, where the method is applied to a first radio access network element, and includes the following steps:

step 201: the first radio access network element sends first information to the terminal, where the first information is used to indicate a corresponding relation between a PDCP count value of a first bearer and a PDCP count value of a second bearer of the terminal, or indicates a corresponding relation between a PDCP sequence number of the first bearer and a PDCP sequence number of the second bearer of the terminal.

Specifically, the first information may be used to indicate a correspondence between a PDCP count value of the first bearer and a PDCP count value of the second bearer of the terminal, or may be used to indicate a correspondence between a PDCP sequence number of the first bearer and a PDCP sequence number of the second bearer of the terminal.

The embodiment of the invention can be applied to downlink data transmission, for example, a switching process of a downlink data transmission mode from a Point-to-Point (PTP) mode to a Point-to-multipoint (Point to Multipoint, PTM) mode, and/or the downlink data transmission relates to a switching process of a network element where the PDCP is changed to realize the continuity of the downlink data transmission.

The downlink data transmission involves changing the scenario of the network element where the PDCP is located, for example, the scenario of handover between different gnbs-CU-UP within a gNB, handover between different gnbs, etc.

The first radio access network element may be a PDCP instance, may be a gNB-CU-UP, or may be a base station, and may specifically be determined according to an actual application scenario. The first radio access network element may be a PDCP instance before handover, may be a gNB-CU-UP before handover, may be a base station before handover, may be a gNB-CU-UP after handover, or may be a base station after handover, and may specifically be determined according to an actual application scenario. The radio access network element before the handover may be referred to as an old radio access network element or a source radio access network element, and the radio access network element after the handover may be referred to as a new radio access network element or a target radio access network element.

The first information may be carried by an RRC reconfiguration message, or may be carried by a PDCP control protocol data unit (Protocol Data Unit, PDU), or the like.

The embodiment of the invention provides a scheme for realizing continuous transmission of downlink data, wherein in the process of changing service data from transmission via an old radio bearer to transmission via a new radio bearer, a network side informs a user terminal of the corresponding relation between PDCP count values (or sequence numbers) of the new and old bearers, so that service continuity can be ensured.

Specifically, in the switching process involving PDCP change and in the switching process of the downlink data transmission mode from PTP mode to PTM mode, even if the count value of the source PDCP is inconsistent with the count value of the target PDCP, continuous transmission of service data can be ensured, so as to solve the problem that multicast service continuity cannot be ensured in a scenario in which each gNB can autonomously determine the mapping relationship from the multicast data stream to the radio bearer according to the principle of the 5G network.

The above transmission method is exemplified below.

The source radio bearer, i.e. the radio bearer before handover, or called old radio bearer, the target radio bearer, i.e. the radio bearer after handover, or called new radio bearer, and the temporary radio bearer is the radio bearer established by the target radio access network element for handover and used for receiving the data forwarded by the source radio access network element.

In an alternative embodiment, the first information includes an offset between PDCP count values of the first bearer and the second bearer or an offset between PDCP sequence numbers of the first bearer and the second bearer.

In another optional specific embodiment, the first information includes second information and third information, where the second information is a count value or a sequence number of a first PDCP packet in the first bearer, and the third information is a count value or a sequence number of a second PDCP packet in the second bearer; the first PDCP data packet is a data packet which is received in the first bearing in a cut-off way, and the second PDCP data packet is a data packet which is received in the second bearing in a start way;

the first radio access network element releases the first bearer.

Wherein the first bearer may be a temporary bearer.

In an optional specific implementation manner, before the first radio access network element sends the first information to the terminal, the method further includes:

In other optional embodiments, the fifth information may not include a count value or a sequence number of the first PDCP packet in the first bearer, and may implicitly indicate, for example, that the first radio access network element receives the count value or the sequence number of the last PDCP packet forwarded on the first bearer when the second radio access network element sends the second flag.

Optionally, the method further comprises:

In another optional specific embodiment, before the step of sending the first information to the terminal by the first radio access network element, the method further includes:

The second radio access network element can acquire the corresponding relation through prior information. For example, the second radio access network element has previously acquired that a certain PDCP data PDU transmitted by the radio bearer corresponding to the first radio access network element corresponds to which PDCP data PDU transmitted by the radio bearer corresponding to the second radio access network element.

Referring to fig. 3, fig. 3 is a flowchart of a transmission method according to a second embodiment of the present invention, where the method is applied to a terminal, and includes the following steps:

step 301: the terminal receives first information sent by a first radio access network element, wherein the first information is used for indicating the corresponding relation between a PDCP count value of a first bearer and a PDCP count value of a second bearer of the terminal or indicating the corresponding relation between a PDCP sequence number of the first bearer and a PDCP sequence number of the second bearer of the terminal.

Optionally, the method further comprises:

or,

and the terminal releases the first bearing.

The embodiment of the present invention provides a technical solution corresponding to the first embodiment and having the same inventive concept, and can achieve the same technical effects, and the detailed description thereof will not be repeated herein with reference to the first embodiment.

Referring to fig. 4, fig. 4 is a flow chart of a transmission method according to a third embodiment of the present invention, the method is applied to a user plane function module in a core network, and includes the following steps:

step 401: the user plane function module receives seventh information sent by a session management function module in a core network; the seventh information is used for indicating that the downlink transmission address of the terminal is changed from a first address to a second address;

Step 402: and sending an end mark aiming at the terminal and aiming at the first service data to an access network element corresponding to the first address, and sending a start mark aiming at the terminal and aiming at the first service data to an access network element corresponding to the second address.

In the embodiment of the invention, the end mark aiming at the terminal and aiming at the first service data is sent to the access network element corresponding to the address before switching, and the start mark aiming at the terminal and aiming at the same service data is sent to the access network element corresponding to the address after switching, so that the network side can acquire the corresponding relation between the PDCP count value or the serial number before and after switching and inform the terminal, thereby ensuring the service continuity.

The technical scheme provided by the application is exemplified below.

Example 1, a scenario in which the downlink data transmission mode is converted from PTP mode to PTM mode, user plane path:

step 1: the user terminal is connected with the 5G network through a gNB, and receives service data in a PTP mode through the gNB.

Step 2: at some point, the gNB decides to send the service to the user terminal in a PTM manner instead. The gNB sends an RRC reconfiguration message to the user terminal, which contains SDAP and PDCP configuration information, and contains an indication for instructing the user terminal to release the old radio bearer for receiving some traffic flows in a PTP mode, and an indication for establishing a new radio bearer for receiving the same traffic flows in a PTM mode.

Step 3: after receiving the RRC reconfiguration message, the user terminal knows through the SDAP and PDCP configuration information therein that the RRC reconfiguration message involves changing from receiving via the old PTP radio bearer to receiving via the new PTM radio bearer. The user terminal immediately establishes a new PTM radio bearer, but for service continuity reasons, the old PTP radio bearer is not immediately released.

Step 4: after completing the establishment of the new PTM radio bearer, the ue feeds back an RRC reconfiguration complete message to the gNB.

Step 5: after receiving the RRC reconfiguration complete message sent by the ue, the gNB sends a PDCP control protocol data unit (Protocol Data Unit, PDU) to the ue by using the PDCP instance corresponding to the old PTP radio bearer (i.e., the first radio access network element), where the PDCP instance includes:

a bias value (i.e. an offset between PDCP count values (or sequence numbers) of the first bearer and the second bearer) is used to inform the user terminal which PDCP data PDU transmitted over the old PTP radio bearer corresponds to which PDCP data PDU transmitted over the new PTM radio bearer. Or alternatively

Two thresholds Xa (i.e. the count value or sequence number of the first PDCP data packet in the first bearer) and Xb (i.e. the count value or sequence number of the second PDCP data packet in the second bearer) are used to inform the user terminal that it should receive PDCP data PDUs up to which PDCP count value over the old PTP radio bearer and inform the user terminal that it should receive PDCP data PDUs from which PDCP count value over the new PTM radio bearer.

Step 6: after receiving the PDCP control PDU, the user terminal performs subsequent processing according to the content in the PDCP control PDU to ensure service continuity.

Specifically, if the bias value is included in the PDCP control PDU, the ue may perform the following processing:

for all PDCP packets received over the old radio bearer or over the temporary radio bearer, including buffered and subsequently received, as long as they have not yet been submitted to the SDAP layer or higher, the offset operation is performed on the count value after the decryption, integrity protection verification, etc. operations are completed, as follows:

let the count value of PDCP packets requiring the biasing operation before the operation be Y. If the offset value is sent in Xa-Xb format, the count value of the data packet is modified to Y- (Xa-Xb) (a modulo operation may be required, and the following is not repeated); if the offset value is sent in Xb-Xa format, the count value of the packet is modified to Y+ (Xb-Xa).

The data received over the two radio bearers is then put together and ordered in order of increasing count value. If a duplicate situation occurs, the data received later in time therein is discarded. This means that if the user terminal successfully receives a PDCP packet via an old radio bearer or via a temporary radio bearer, and successfully receives a PDCP packet of the same content via a new radio bearer (transmitted in PTM), the latter is discarded; and, if the user terminal successfully receives a PDCP packet via a new radio bearer (transmitted in PTM), and successfully receives a PDCP packet with the same content via an old radio bearer or via a temporary radio bearer, discarding the same.

And finally, sequentially submitting the ordered data to an SDAP layer or a higher layer.

Optionally, the user terminal may also request network retransmission according to the ordered data. That is, if the ue finds that the counted value is discontinuous in the sorted data, it may inform the network through PDCP status report or the like to request retransmission of the data packets.

If the thresholds Xa and Xb are included in the PDCP control PDU, the user terminal may perform the subsequent processing as follows:

all PDCP packets received for it over the old radio bearer, or over the temporary radio bearer, including buffered and subsequently received, are discarded if their count value is not less than Xa; all PDCP packets received over the new radio bearer (transmitted in PTM) are discarded if their count is lower than Xb. Or,

all PDCP packets received for it over the old radio bearer, or over the temporary radio bearer, including buffered and subsequently received, are discarded if their count value is higher than Xa; all PDCP packets received by the new radio bearer (transmitted in PTM) are discarded if the count value is not higher than Xb.

Then, when delivering data to the SDAP layer or higher, the user terminal delivers the data received through the old radio bearer or through the temporary radio bearer first; after determining that its transmission is complete, the data received over the new radio bearer (transmitted in PTM) is submitted.

Example 2, scenario in which the downlink data transmission mode is converted from PTP mode to PTM mode, control plane approach:

Step 2: at some point, the gNB decides to send the service to the user terminal in a PTM manner instead. The gNB (i.e. the first radio access network element) sends an RRC reconfiguration message to the user terminal, which contains SDAP and PDCP configuration information, contains an indication instructing the user terminal to release old radio bearers which receive some traffic flows in a PTP manner, and an indication establishing new radio bearers which receive the same traffic flows in a PTM manner.

The RRC reconfiguration message further includes:

Two thresholds Xa (count value or sequence number of first PDCP data packet in the first bearer) and Xb (count value or sequence number of second PDCP data packet in the second bearer) are used to inform the user terminal that it should receive PDCP data PDUs up to which PDCP count value over the old PTP radio bearer and inform the user terminal that it should receive PDCP data PDUs from which PDCP count value over the new PTM radio bearer.

That is, the first information indicating the correspondence between PDCP count values (or sequence numbers) of the first bearer and the second bearer of the terminal may be carried by an RRC reconfiguration message.

Step 3: after receiving the RRC reconfiguration message, the ue first establishes a new PTM radio bearer, and then performs subsequent processing according to the content carried by the RRC reconfiguration message to ensure service continuity, which can be referred to in example 1 and will not be described herein.

Example 3, please refer to fig. 5, the scenario of handover between different gNB-CU-UP within a gNB, user plane approach:

step 1: the user terminal 1 is connected to the 5G network through a gNB and receives traffic data belonging to a certain session through the gNB. In the 5G core network, the session traffic is distributed by one UPF. The gNB internally comprises one gNB-CU-CP and a plurality of gNB-CU-UP, and the user terminal 1 receives service data which belongs to the session and is sent by the UPF through the gNB-CU-UP 1. At the same time, some other user terminals are receiving traffic data belonging to the session, sent by the UPF, through the gNB-CU-UP 2. Due to the large number of the latter, in order to save air interface resources, the gNB-CU-UP2 establishes a shared bearer for those user terminals, and sends the service data on the air interface in a PTM mode. The mapping relationship between the service flows executed by the two gNB-CU-UP and the radio bearer is the same except for the radio bearer identification. For example, gNB-CU-UP1 maps traffic flow 1 in the session to radio bearer 1, and traffic flows 2, 3 to radio bearer 2; the gNB-CU-UP2 maps traffic flow 1 in the session to radio bearer 5 and traffic flows 2, 3 to radio bearer 6, which is the case for the "mapping of traffic flows performed by two gNB-CU-UP to radio bearers" case where the traffic flows are identical except for the radio bearer identity.

Step 2: the gNB-CU-CP decides to change the traffic data transmission path for the user terminal 1 from gNB-CU-UP1 to gNB-CU-UP2 due to movement of the user terminal 1 or the like. The gNB-CU-CP then performs a series of control plane signaling interactions with the user terminal 1, gNB-CU-UP2, one or more gNB-DUs, AMFs and SMFs to complete the path change described above.

Step 3: the SMF sends a signaling to the UPF informing it that the downlink address for the user terminal 1 for the session has changed, typically from gNB-CU-UP1 to gNB-CU-UP2. However, there are other UPFs between the UPF and the gNB-CU-UP1 or the gNB-CU-UP2, and at this time, the downlink transmission address of the N9 transmission channel is changed.

Step 4a, 4b: the UPF sends an end mark for the user terminal 1 to the gNB-CU-UP1, and the end mark is attached to a certain data packet; the UPF sends a start tag (i.e. a first tag) for the user terminal 1 to the gNB-CU-UP2 (i.e. the first radio access network element) attached to a certain data packet. The contents of the two packets are identical. Since the packets on the N3 transmission channel are almost always transmitted in sequence, this means that for any packet sent to the gNB-CU-UP1 earlier than the end mark, the content must not be included in any packet sent to the gNB-CU-UP2 later than the start mark.

Step 5a, 5b: and the gNB-CU-UP1 and the gNB-CU-UP2 respectively allocate PDCP count values to each downlink data packet according to the mapping relation of the service flow and the radio bearer, and generate corresponding PDCP data packets. After receiving the end and start flags described in steps 4a, 4b, they calculate the count value for each traffic bearer by themselves, where the count value for a radio bearer calculated by the gNB-CU-UP1 may be denoted Xa (i.e. the count value or sequence number of the first PDCP packet in the first bearer), and the count value for a radio bearer calculated by the gNB-CU-UP2 may be denoted Xb (i.e. the count value or sequence number of the second PDCP packet in the second bearer), both satisfying either of the following two relations:

1) For the PDCP packet generated by the gNB-CU-UP1 (i.e., the first radio access network element), the service data contained therein is received prior to the end tag if and only if its count value is below Xa, and for the PDCP packet generated by the gNB-CU-UP2, the service data contained therein is received prior to the start tag if and only if its count value is below Xb;

2) For the PDCP data packet generated by gNB-CU-UP1, the service data contained therein is received prior to the end tag if and only if the count value thereof is not higher than Xa, and for the PDCP data packet generated by gNB-CU-UP2, the service data contained therein is received prior to the start tag if and only if the count value thereof is not higher than Xb.

Step 6a, 6b: both gNB-CU-UP1 and gNB-CU-UP2 send service data through the air interface. Since terminal 1 has established a connection with the gNB-CU-UP2 in step 2, it can already receive traffic data belonging to the session sent by gNB-CU-UP2 in multicast.

Step 7: for each radio bearer, the gNB-CU-UP1 (i.e., the second radio access network element) sends an end tag (i.e., a second tag) to the gNB-CU-UP2 (i.e., the first radio access network element) that includes Xa for that radio bearer (i.e., the count value or sequence number of the first PDCP packet in the first bearer).

Step 8: and gNB-CU-UP2 (namely the first radio access network element) calculates the corresponding relation between the PDCP data packet of the bearer before the path change and the PDCP data packet of the bearer after the path change by comparing Xa and Xb. That is, the gNB-CU-UP2 can know that the content of the PDCP data packet with the count value Xa before the path change corresponds to the content of the PDCP data packet with the count value Xb after the path change, and the gNB-CU-UP2 can know that the content of the PDCP data packet with the count value Xa-1 before the path change (the modulo operation may be needed and the same will not be repeated hereinafter) corresponds to the content of the PDCP data packet with the count value Xb-1 after the path change, and so on.

Step 9: the gNB-CU-UP2 (i.e. the first radio access network element) sends a PDCP control PDU to the user terminal 1, which includes:

a bias value (i.e. an offset between PDCP count values (or sequence numbers) of the first bearer and the second bearer), such as Xa-Xb, or equivalently Xb-Xa, is used to inform the user terminal 1 which PDCP data PDU transmitted over the old PTP radio bearer corresponds to which PDCP data PDU transmitted over the new PTM radio bearer. Or alternatively

Xa and Xb for informing the user terminal 1 that it should receive PDCP data PDUs up to which PDCP count value over the old PTP radio bearer and informing the user terminal that it should receive PDCP data PDUs from which PDCP count value over the new PTM radio bearer.

Step 10: after receiving the PDCP control PDU, the ue performs subsequent processing according to the content in the PDCP control PDU to ensure service continuity, and the specific processing procedure is described in the above example 1, which is not repeated here.

For example 4, referring to fig. 6, the scenario of handover between different gNB-CU-UP in the gNB, the user plane path has temporary bearers:

Step 2: the gNB-CU-CP decides to change the traffic data transmission path for the user terminal 1 from gNB-CU-UP1 to gNB-CU-UP2 due to movement of the user terminal 1 or the like. The gNB-CU-CP then performs a series of control plane signaling interactions with the user terminal 1, gNB-CU-UP2, one or more gNB-DUs, AMFs and SMFs to complete the path change described above. Due to hardware limitations, the user terminal 1 can only connect with one of the gNB-CU-UP1 and gNB-CU-UP2 at the same time. To guarantee traffic continuity, the gNB-CU-CP decides to enable the data forwarding mechanism. Specifically, it sends an interface message to the gNB-CU-UP2 requesting that it establish, for each radio bearer that the user terminal 1 is receiving before the path change in the session, a corresponding temporary radio bearer for sending traffic data forwarded from the gNB-CU-UP1 to the user terminal 1 in PTP. The gNB-CU-UP2 accepts the request and assigns a transport layer address for each radio bearer.

Step 3: for each radio bearer, gNB-CU-UP1 starts forwarding the traffic data towards gNB-CU-UP2 through the transport layer address.

Step 4: the SMF sends a signaling to the UPF informing it that the downlink address for the user terminal 1 for the session has changed, typically from gNB-CU-UP1 to gNB-CU-UP2. However, there are other UPFs between the UPF and the gNB-CU-UP1 or the gNB-CU-UP2, and at this time, the downlink transmission address of the N9 transmission channel is changed.

Step 5a, 5b: the UPF sends an end mark for the user terminal 1 to the gNB-CU-UP1, and the end mark is attached to a certain data packet; the UPF sends a start tag (i.e. a first tag) for the user terminal 1 to the gNB-CU-UP2 (i.e. the first radio access network element) attached to a certain data packet. The contents of the two packets are identical. Since the packets on the N3 transmission channel are almost always transmitted in sequence, this means that for any packet sent to the gNB-CU-UP1 earlier than the end mark, the content must not be included in any packet sent to the gNB-CU-UP2 later than the start mark.

Step 6a, 6b: and the gNB-CU-UP1 and the gNB-CU-UP2 respectively allocate PDCP count values to each downlink data packet according to the mapping relation of the service flow and the radio bearer, and generate corresponding PDCP data packets. The gNB-CU-UP1 forwards each downlink data packet required to be received by the user terminal 1 to the gNB-CU-UP2 (i.e. the first radio access network element) as described in step 3, wherein the downlink data packet contains information reflecting the PDCP count value.

Step 7: for each radio bearer described above, after the gNB-CU-UP1 has sent all the packets received earlier than step 5a and mapped to that radio bearer to the gNB-CU-UP2, the gNB-CU-UP1 (i.e. the second radio access network element) sends an end flag (i.e. the second flag) to the gNB-CU-UP2 (i.e. the first radio access network element) to indicate that the data forwarding for that radio bearer for the user terminal 1 has been completed. This end tag implicitly refers to the count value of the last forwarded PDCP packet on the radio bearer, or equivalently, the count value +1.

Step 8a, 8b: and gNB-CU-UP2 sends the service data through an air interface. Wherein, the data forwarded from gNB-CU-UP1 is transmitted in PTP mode through corresponding temporary radio bearer, and the data received directly from UPF is transmitted in PTM mode through the shared bearer described in step 1. Alternatively, the gNB-CU-UP2 releases the temporary radio bearer after all data forwarded from the gNB-CU-UP1 has been successfully received by the user terminal 1.

Step 9: after receiving the end and start flags described in steps 7, 5b, the gNB-CU-UP2 calculates the count value for each service bearer by itself, where the count value for a radio bearer for transmitting data in the form of PTP to the user terminal 1 may be denoted as Xa, and the count value for a radio bearer for transmitting data in the form of PTM for the corresponding (i.e. including the same traffic flow) may be denoted as Xb, both satisfying either of the following two relations:

1) For PDCP packets forwarded from the gNB-CU-UP1, the contained traffic data is received prior to the end tag for the bearer if and only if its count value is below Xa, and for the gNB-CU-UP2 self-generated PDCP packets as described in step 6b, the contained traffic data is received prior to the start tag if and only if its count value is below Xb;

2) For the PDCP packet forwarded from the gNB-CU-UP1, the service data contained therein is received prior to the end tag for the bearer if and only if its count value is not higher than Xa, and for the PDCP packet self-generated as described in step 6b for the gNB-CU-UP2, the service data contained therein is received prior to the start tag if and only if its count value is not higher than Xb.

And gNB-CU-UP2 (namely the first radio access network element) calculates the corresponding relation between the PDCP data packet of the bearer before the path change and the PDCP data packet of the bearer after the path change by comparing Xa and Xb. That is, the gNB-CU-UP2 can know that the content of the PDCP data packet with the count value Xa before the path change corresponds to the content of the PDCP data packet with the count value Xb after the path change, and the gNB-CU-UP2 can know that the content of the PDCP data packet with the count value Xa-1 before the path change (the modulo operation may be needed and the same will not be repeated hereinafter) corresponds to the content of the PDCP data packet with the count value Xb-1 after the path change, and so on.

Step 10: the gNB-CU-UP2 (i.e. the first radio access network element) sends a PDCP control PDU to the user terminal 1, which includes:

a bias value (i.e. an offset between PDCP count values (or sequence numbers) of the first bearer and the second bearer), such as Xa-Xb, or equivalently Xb-Xa, is used to inform the user terminal 1 which PDCP data PDU transmitted over the temporary PTP radio bearer corresponds to which PDCP data PDU transmitted over the common PTM radio bearer. Or alternatively

Xa and Xb for informing the user terminal 1 that it should receive PDCP data PDUs up to which PDCP count value over the temporary PTP radio bearer and informing the user terminal that it should receive PDCP data PDUs from which PDCP count value over the common PTM radio bearer.

Step 11: after receiving the PDCP control PDU, the ue 1 performs subsequent processing according to the content in the PDCP control PDU, so as to ensure service continuity. The specific processing procedure is described in the above example 1, and will not be repeated here. Alternatively, when the processing is completed, the user terminal 1 releases the temporary radio bearer described earlier.

Example 5, handover between different gnbs, control plane approach:

Step 1: the gNB1 and the gNB2 are both transmitting service data in a PTM manner, and the mapping relationship between the service flows of the both to the radio bearer is the same except for the radio bearer identification. For example, gNB1 maps traffic flow 1 in the session to radio bearer 1, and traffic flows 2, 3 to radio bearer 2; the gNB2 maps the traffic stream 1 in the session to the radio bearer 5 and the traffic streams 2, 3 to the radio bearer 6, which is the case for the "mapping of traffic streams performed by two gnbs to radio bearers", which is the same except for the radio bearer identity.

Step 2: the gNB1 (i.e. the first radio access network element) sends an interface message to the gNB2, wherein for each of the radio bearers, an indication (i.e. the sixth information) is included, whose content is the correspondence between PDCP packets, i.e. which content in the PDCP packets transmitted by the gNB1 corresponds to which content in the PDCP packets transmitted by the gNB2.

Step 3: the user terminal is connected with the 5G network through a gNB1, and receives the service data through the gNB 1.

Step 4: the gNB1 decides to switch the user terminal to the gNB2 due to the movement of the user terminal 1 or the like.

Step 5: the gNB2 sends an RRC reconfiguration message to the user terminal, wherein the RRC reconfiguration message contains configuration information after switching. This RRC reconfiguration message is forwarded to the user terminal via the forwarding of the gNB 1.

The RRC reconfiguration message further includes an indication (i.e., first information) generated according to the correspondence between PDCP packets received in step 2, where the specific content is:

a bias value (i.e. an offset between PDCP count values (or sequence numbers) of the first bearer and the second bearer) is used to inform the ue of which PDCP data PDU transmitted over the radio bearer before handover corresponds to which PDCP data PDU transmitted over the radio bearer before handover. Or alternatively

Two thresholds Xa (i.e., a count value or sequence number of a first PDCP packet in the first bearer) and Xb (i.e., a count value or sequence number of a second PDCP packet in the second bearer) are used to inform the user terminal that it should receive PDCP data PDUs up to which PDCP count value over the radio bearer before handover and inform the user terminal that it should receive PDCP data PDUs from which PDCP count value over the radio bearer before handover.

Step 6: after receiving the RRC reconfiguration message, the ue performs handover, and then performs subsequent processing according to the content carried by the RRC reconfiguration message, so as to ensure service continuity, which can be referred to in example 1 specifically and will not be described herein.

For example 6, please refer to fig. 7, the handover between different gnbs, the user plane approach.

Step 1: the user terminal 1 is connected to the 5G network through a gNB1 and receives service data belonging to a certain session. In the 5G core network, the traffic is distributed by one UPF. At the same time, some other user terminals are receiving the service data belonging to the session sent by the UPF through the gNB2. Due to the large number of the latter, in order to save air interface resources, the gNB2 establishes a shared bearer for those user terminals, and sends the service data over the air interface in a PTM manner. The mapping relationship between the traffic flows executed by the two gnbs and the radio bearer is the same except for the radio bearer identification. For example, gNB1 maps traffic flow 1 in the session to radio bearer 1, and traffic flows 2, 3 to radio bearer 2; the gNB2 maps the traffic stream 1 in the session to the radio bearer 5 and the traffic streams 2, 3 to the radio bearer 6, which is the case for the "mapping of traffic streams performed by two gnbs to radio bearers", which is the same except for the radio bearer identity.

Step 2: the gNB1 decides to switch the user terminal 1 to the gNB2 due to the movement of the user terminal 1 or the like. Thus, the gNB1 performs a series of control plane signaling interactions with the user terminals 1, gNB2, AMF and SMF to complete the handover procedure described above.

Step 3: the SMF sends a signaling to the UPF to inform it that the downlink address for the user terminal 1 for the session has changed, typically from gNB1 to gNB2. However, there are cases where another UPF exists between the UPF and the gNB1 or the gNB2, and at this time, the downlink transmission address of the N9 transmission channel is changed.

Step 4a, 4b: the UPF sends an end mark for the user terminal 1 to the gNB1, and the end mark is attached to a certain data packet; the UPF sends a start tag (i.e. a first tag) for the user terminal 1 to the gNB2 (i.e. the first radio access network element) attached to a certain data packet. The contents of the two packets are identical. Since the packets on the N3 transmission channel are almost always transmitted in sequence, this means that, for any packet sent to gNB1 earlier than the end mark, the content must not be included in any packet sent to gNB2 later than the start mark.

Step 5a, 5b: gNB1 and gNB2 respectively allocate PDCP count values to each downlink data packet according to the mapping relation between the service flow and the radio bearer, and generate corresponding PDCP data packets. After receiving the end and start flags described in steps 4a, 4b, they calculate the count value for each traffic bearer by themselves, where the count value for a radio bearer calculated by gNB1 may be denoted Xa, the count value for a corresponding (i.e. including the same traffic flow) radio bearer calculated by gNB2 may be denoted Xb, and either of the following two relationships may be satisfied:

1) For the PDCP packet generated by gNB1, the service data contained therein is received prior to the end tag if and only if its count value is below Xa, and for the PDCP packet generated by gNB2, the service data contained therein is received prior to the start tag if and only if its count value is below Xb;

2) For the PDCP packet generated by gNB1, the service data contained therein is received prior to the end tag if and only if its count value is not higher than Xa, and for the PDCP packet generated by gNB2, the service data contained therein is received prior to the start tag if and only if its count value is not higher than Xb.

Step 6a, 6b: both gNB1 and gNB2 send traffic data over the air interface. Since terminal 1 has established a connection with the gNB2 in step 2, it can already receive traffic data belonging to the session as sent by the gNB2 in multicast.

Step 7: for each radio bearer, gNB1 (i.e., the second radio access network element) sends an end-marker to gNB2 (i.e., the first radio access network element), which contains Xa for that radio bearer.

Step 8: gNB2 calculates the correspondence between the bearer before the path change and the PDCP packet of the bearer after the path change by comparing Xa and Xb. That is, the gNB2 can know that the content of the PDCP data packet with the count value Xa before the path change corresponds to the content of the PDCP data packet with the count value Xb after the path change, and the gNB2 can know that the content of the PDCP data packet with the count value Xa-1 before the path change (the modulo operation may be needed and the same will not be repeated hereinafter) corresponds to the content of the PDCP data packet with the count value Xb-1 after the path change, and so on.

Step 9: the gNB2 transmits a PDCP control PDU (protocol data unit ) to the user terminal 1, which includes:

a bias value (i.e. an offset between PDCP count values (or sequence numbers) of the first bearer and the second bearer), such as Xa-Xb or equivalently Xb-Xa, is used to inform the user terminal 1 which PDCP data PDU transmitted over the old PTP radio bearer corresponds to which PDCP data PDU transmitted over the new PTM radio bearer. Or alternatively

Xa (i.e. the count value or sequence number of the first PDCP data packet in the first bearer) and Xb (i.e. the count value or sequence number of the second PDCP data packet in the second bearer) are used to inform the user terminal 1 that it should receive PDCP data PDUs up to which PDCP count value over the old PTP radio bearer and inform the user terminal that it should receive PDCP data PDUs from which PDCP count value over the new PTM radio bearer.

Step 10: after receiving the PDCP control PDU, the ue 1 performs subsequent processing according to the content in the PDCP control PDU, so as to ensure service continuity. The specific processing procedure is described in the above example 1, and will not be repeated here.

For example 7, referring to fig. 8, there is a temporary bearer in the ue path for handover between different gnbs.

Step 2: the gNB1 decides to switch the user terminal 1 to the gNB2 due to the movement of the user terminal 1 or the like. Thus, the gNB1 performs a series of control plane signaling interactions with the user terminals 1, gNB2, AMF and SMF to complete the handover procedure described above. Due to hardware limitations, the user terminal 1 can only connect with one of the gNB1 and the gNB2 at the same time. To ensure traffic continuity, gNB1 and gNB2 agree to enable the data forwarding mechanism. Specifically, for the ue 1, the gNB2 allocates a transport layer address to each radio bearer that the ue 1 is receiving before handover in the session, so as to receive traffic data forwarded by the gNB 1; and, the gNB2 establishes a corresponding temporary radio bearer for each radio bearer, so as to send the traffic data converted before the gNB1 to the ue 1 in the PTP manner.

Step 3: for each radio bearer, gNB1 starts forwarding the traffic data to gNB2 via the transport layer address.

Step 4: the SMF sends a signaling to the UPF to inform it that the downlink address for the user terminal 1 for the session has changed, typically from gNB1 to gNB2. However, there are cases where another UPF exists between the UPF and the gNB1 or the gNB2, and at this time, the downlink transmission address of the N9 transmission channel is changed.

Step 5a, 5b: the UPF sends an end mark for the user terminal 1 to the gNB1, and the end mark is attached to a certain data packet; the UPF sends a start tag (i.e. a first tag) for the user terminal 1 to the gNB2 (i.e. the first radio access network element) attached to a certain data packet. The contents of the two packets are identical. Since the packets on the N3 transmission channel are almost always transmitted in sequence, this means that, for any packet sent to gNB1 earlier than the end mark, the content must not be included in any packet sent to gNB2 later than the start mark.

Step 6a, 6b: gNB1 and gNB2 respectively allocate PDCP count values to each downlink data packet according to the mapping relation between the service flow and the radio bearer, and generate corresponding PDCP data packets. The gNB1 forwards each downlink data packet that the ue 1 needs to receive to the gNB2, including information reflecting the PDCP count value, as described in step 3.

Step 7: for each radio bearer described above, after the gNB1 has sent all the packets received earlier than step 5a and mapped to that radio bearer to the gNB2, the gNB1 (i.e. the second radio access network element) sends an end flag (i.e. the second flag) to the gNB2 (i.e. the first radio access network element) to indicate that the data forwarding for that radio bearer for the user terminal 1 has been completed. This end tag implicitly refers to the count value of the last forwarded PDCP packet on the radio bearer, or equivalently, the count value +1.

Step 8a, 8b: and gNB2 sends the service data through an air interface. Wherein, the data converted from gNB1 is transmitted in PTP mode through corresponding temporary radio bearer, and the data received directly from UPF is transmitted in PTM mode through the shared bearer described in step 1. Alternatively, the gNB2 releases the temporary radio bearer after all data forwarded from the gNB1 has been successfully received by the user terminal 1.

Step 9: upon receipt of the end and start flags described in steps 7, 5b, the gNB2 calculates the count value for each service bearer by itself, where the count value for a particular radio bearer for transmitting data in PTP form to the user terminal 1 may be denoted Xa, and the count value for a corresponding (i.e. including the same service flow) radio bearer for transmitting data in PTM form may be denoted Xb, both satisfying either of the following two relationships:

1) For PDCP packets forwarded from the gNB1, the contained traffic data is received prior to the end tag for the bearer if and only if its count value is below Xa, and for PDCP packets generated by the gNB2 itself as described in step 6b, the contained traffic data is received prior to the start tag if and only if its count value is below Xb;

2) For the PDCP packet forwarded from the gNB1, the contained service data is received prior to the end tag for the bearer if and only if its count value is not higher than Xa, and for the PDCP packet generated by the gNB2 itself as described in step 6b, the contained service data is received prior to the start tag if and only if its count value is not higher than Xb.

gNB2 calculates the correspondence between the bearer before the path change and the PDCP packet of the bearer after the path change by comparing Xa and Xb. That is, the gNB2 can know that the content of the PDCP data packet with the count value Xa before the path change corresponds to the content of the PDCP data packet with the count value Xb after the path change, and the gNB2 can know that the content of the PDCP data packet with the count value Xa-1 before the path change (the modulo operation may be needed and the same will not be repeated hereinafter) corresponds to the content of the PDCP data packet with the count value Xb-1 after the path change, and so on.

Step 10: the gNB-CU-UP2 sends a PDCP control PDU to the user terminal 1, which includes:

a bias value (i.e. an offset between PDCP count values (or sequence numbers) of the first bearer and the second bearer), such as Xa-Xb or equivalently Xb-Xa, is used to inform the user terminal 1 which PDCP data PDU transmitted over the temporary PTP radio bearer corresponds to which PDCP data PDU transmitted over the common PTM radio bearer. Or alternatively

Xa (i.e. the count value or sequence number of the first PDCP data packet in the first bearer) and Xb (i.e. the count value or sequence number of the second PDCP data packet in the second bearer) are used to inform the user terminal 1 that it should receive PDCP data PDUs up to which PDCP count value over the temporary PTP radio bearer and inform the user terminal that it should receive PDCP data PDUs starting from which PDCP count value over the common PTM radio bearer.

Referring to fig. 9, fig. 9 is a schematic structural diagram of a radio access network element according to a fourth embodiment of the present invention, where the radio access network element includes a memory 910, a transceiver 920, and a processor 930:

a memory 910 for storing a computer program; a transceiver 920 for receiving and transmitting data under the control of the processor; a processor 930 configured to read the computer program in the memory and perform the following operations:

A transceiver 920 for receiving and transmitting data under the control of a processor 930.

Wherein in fig. 9, a bus architecture may comprise any number of interconnected buses and bridges, and in particular one or more processors represented by processor 930 and various circuits of memory represented by memory 910, linked together. The bus architecture may also link together various other circuits such as peripheral devices, voltage regulators, power management circuits, etc., which are well known in the art and, therefore, will not be described further herein. The bus interface provides an interface. Transceiver 920 may be a number of elements, including a transmitter and a receiver, providing a means for communicating with various other apparatus over a transmission medium, including wireless channels, wired channels, optical cables, etc. The processor 930 is responsible for managing the bus architecture and general processing, and the memory 910 may store data used by the processor 930 in performing operations.

Processor 930 may be a Central Processing Unit (CPU), application specific integrated circuit (Application Specific Integrated Circuit, ASIC), field programmable gate array (Field-Programmable Gate Array, FPGA) or complex programmable logic device (Complex Programmable Logic Device, CPLD), or may employ a multi-core architecture.

Releasing the first bearer.

It should be noted that, the radio access network element provided by the embodiment of the present invention can implement all the method steps implemented by the method embodiment applied to the first radio access network element, and can achieve the same technical effects, and detailed descriptions of the same parts and beneficial effects as those of the method embodiment in the embodiment are omitted herein.

Referring to fig. 10, fig. 10 is a schematic structural diagram of a terminal according to a fifth embodiment of the present invention, where the terminal includes a memory 1010, a transceiver 1020, and a processor 1030:

a memory 1010 for storing a computer program; a transceiver 1020 for transceiving data under the control of the processor; a processor 1030 for reading the computer program in the memory 1010 and performing the following operations:

A transceiver 1020 for receiving and transmitting data under the control of a processor 1030.

Where in FIG. 10, a bus architecture may be comprised of any number of interconnected buses and bridges, and in particular one or more processors represented by processor 1030 and various circuits of the memory, represented by memory 1010. The bus architecture may also link together various other circuits such as peripheral devices, voltage regulators, power management circuits, etc., which are well known in the art and, therefore, will not be described further herein. The bus interface provides an interface. The transceiver 1020 may be a number of elements, including a transmitter and a receiver, providing a means for communicating with various other apparatus over transmission media, including wireless channels, wired channels, optical cables, etc. The user interface 1040 may also be an interface capable of interfacing with an inscribed desired device for a different user device, including but not limited to a keypad, display, speaker, microphone, joystick, etc.

Processor 1030 is responsible for managing the bus architecture and general processing, with memory 1010 storing data used by processor 1030 in performing operations.

Alternatively, processor 1030 may be a CPU (Central processing Unit), ASIC (Application Specific Integrated Circuit ), FPGA (Field-Programmable Gate Array, field programmable Gate array) or CPLD (Complex Programmable Logic Device ), or the processor may employ a multicore architecture.

The processor is configured to execute any of the methods provided in the embodiments of the present application by invoking a computer program stored in a memory in accordance with the obtained executable instructions. The processor and the memory may also be physically separate.

Optionally, the processor 1030 is further configured to perform the following operations:

or,

releasing the first bearer.

It should be noted that, the terminal provided by the embodiment of the present invention can implement all the method steps implemented by the method embodiment applied to the terminal, and can achieve the same technical effects, and detailed descriptions of the same parts and beneficial effects as those of the method embodiment in the embodiment are omitted.

Referring to fig. 11, fig. 11 is a schematic structural diagram of a user plane function module according to a sixth embodiment of the present invention, where the user plane function module is located in a core network, and the user plane function module includes a memory 1110, a transceiver 1120, and a processor 1130:

a memory 1110 for storing a computer program; a transceiver 1120 for receiving and transmitting data under the control of the processor; processor 1130 for reading the computer program in the memory and performing the following operations:

A transceiver 1120 for receiving and transmitting data under the control of a processor 1130.

Where in FIG. 11, a bus architecture may comprise any number of interconnected buses and bridges, with one or more processors, specifically represented by processor 1130, and various circuits of memory, represented by memory 1110, being linked together. The bus architecture may also link together various other circuits such as peripheral devices, voltage regulators, power management circuits, etc., which are well known in the art and, therefore, will not be described further herein. The bus interface provides an interface. The transceiver 1120 may be a number of elements, including a transmitter and a receiver, providing a means for communicating with various other apparatus over transmission media, including wireless channels, wired channels, optical cables, and the like. The processor 1130 is responsible for managing the bus architecture and general processing, and the memory 1110 may store data used by the processor 1130 in performing operations.

Processor 1130 may be a Central Processing Unit (CPU), application specific integrated circuit (Application Specific Integrated Circuit, ASIC), field programmable gate array (Field-Programmable Gate Array, FPGA) or complex programmable logic device (Complex Programmable Logic Device, CPLD), and may also employ a multi-core architecture.

It should be noted that, the user plane function module provided in the embodiment of the present invention can implement all the method steps implemented in the method embodiment of the user plane function module applied in the core network, and can achieve the same technical effects, and detailed descriptions of the same parts and beneficial effects as those of the method embodiment in the embodiment are omitted herein.

Referring to fig. 12, fig. 12 is a schematic structural diagram of a radio access network element according to a seventh embodiment of the present invention, where a radio access network element 1200 includes:

a first information sending unit 1201, configured to send first information to a terminal, where the first information is used to indicate a correspondence between a PDCP count value of a first bearer and a PDCP count value of a second bearer of the terminal, or indicate a correspondence between a PDCP sequence number of the first bearer and a PDCP sequence number of the second bearer of the terminal.

Optionally, the radio access network element 1200 further includes:

and the releasing unit is used for releasing the first bearing.

Optionally, the radio access network element 1200 further includes:

a fourth information receiving unit, configured to receive fourth information sent by a user plane function module in a core network, where the fourth information includes a first flag for first service data;

A fifth information receiving unit, configured to receive fifth information sent by a second radio access network element, where the fifth information includes a second flag for the first service data;

Optionally, the radio access network element 1200 further includes:

and a first information determining unit configured to determine the first information according to the fourth information and the fifth information.

Optionally, the radio access network element 1200 further includes:

and a sixth information receiving module, configured to receive sixth information sent by the second radio access network element, where the sixth information is used to indicate the correspondence.

Referring to fig. 13, fig. 13 is a schematic structural diagram of a terminal according to an eighth embodiment of the present invention, where the terminal 1300 includes:

a first information receiving unit 1301, configured to receive first information sent by a first radio access network element, where the first information is used to indicate a correspondence between a PDCP count value of a first bearer and a PDCP count value of a second bearer of the terminal, or indicate a correspondence between a PDCP sequence number of the first bearer and a PDCP sequence number of the second bearer of the terminal.

Optionally, the terminal 1300 further includes:

a first discarding unit, configured to discard a fourth PDCP packet if a third PDCP packet has been successfully received through the first bearer and a fourth PDCP packet has been successfully received through the second bearer, and a count value or a sequence number of the fourth PDCP packet corresponds to a count value or a sequence number of the third PDCP packet;

or,

and the second discarding unit is used for discarding the third PDCP data packet if the fourth PDCP data packet is successfully received through the second bearer and the third PDCP data packet is successfully received through the first bearer and the count value or the sequence number of the third PDCP data packet corresponds to the count value or the sequence number of the fourth PDCP data packet.

Optionally, the terminal 1300 further includes:

and the third discarding unit is configured to discard the fifth PDCP data packet if the fifth PDCP data packet is successfully received through the first bearer and the count value or the sequence number of the fifth PDCP data packet is greater than or equal to the count value or the sequence number of the first PDCP data packet.

Optionally, the terminal 1300 further includes:

and the fourth discarding unit is configured to discard the sixth PDCP data packet if the sixth PDCP data packet is successfully received through the second bearer and the count value or the sequence number of the sixth PDCP data packet is less than or equal to the count value or the sequence number of the second PDCP data packet.

Optionally, the terminal 1300 further includes:

and the bearer releasing unit is used for releasing the first bearer.

Referring to fig. 14, fig. 14 is a schematic structural diagram of a user plane function module according to a ninth embodiment of the present invention, where the user plane function module is located in a core network, and the user plane function module 1400 includes:

a change indication unit 1401, configured to receive seventh information sent by a session management function module in the core network; the seventh information is used for indicating that the downlink transmission address of the terminal is changed from a first address to a second address;

a data transmission indicating unit 1402, configured to send an end tag for the terminal and for the first service data to an access network element corresponding to the first address, and send a start tag for the terminal and for the first service data to an access network element corresponding to the second address.

It should be noted that, in the embodiment of the present application, the division of the units is schematic, which is merely a logic function division, and other division manners may be implemented in actual practice. In addition, each functional unit in each embodiment of the present application may be integrated in one processing unit, or each unit may exist alone physically, or two or more units may be integrated in one unit. The integrated units may be implemented in hardware or in software functional units.

The integrated units, if implemented in the form of software functional units and sold or used as stand-alone products, may be stored in a processor-readable storage medium. Based on such understanding, the technical solution of the present application may be embodied in essence or a part contributing to the prior art or all or part of the technical solution, in the form of a software product stored in a storage medium, including several instructions to cause a computer device (which may be a personal computer, a server, or a network device, etc.) or a processor (processor) to perform all or part of the steps of the methods described in the embodiments of the present application. And the aforementioned storage medium includes: a U-disk, a removable hard disk, a Read-Only Memory (ROM), a random access Memory (Random Access Memory, RAM), a magnetic disk, or an optical disk, or other various media capable of storing program codes.

It should be noted that, the above device provided in the embodiment of the present invention can implement all the method steps implemented in the corresponding method embodiment, and can achieve the same technical effects, and detailed descriptions of the same parts and beneficial effects as those of the method embodiment in the present embodiment are omitted.

An embodiment of the present invention provides a processor-readable storage medium storing a computer program for causing the processor to execute any one of the methods described above. For details, reference is made to the description of the method steps in the corresponding embodiments above.

The processor-readable storage medium may be any available medium or data storage device that can be accessed by a processor, including, but not limited to, magnetic storage (e.g., floppy disks, hard disks, magnetic tape, magneto-optical disks (MOs), etc.), optical storage (e.g., CD, DVD, BD, HVD, etc.), semiconductor storage (e.g., ROM, EPROM, EEPROM, nonvolatile storage (NAND FLASH), solid State Disk (SSD)), and the like.

The technical scheme provided by the embodiment of the application can be suitable for various systems, in particular to a 5G system. For example, suitable systems may be global system for mobile communications (global system of mobile communication, GSM), code division multiple access (code division multiple access, CDMA), wideband code division multiple access (Wideband Code Division Multiple Access, WCDMA) universal packet Radio service (general packet Radio service, GPRS), long term evolution (long term evolution, LTE), LTE frequency division duplex (frequency division duplex, FDD), LTE time division duplex (time division duplex, TDD), long term evolution-advanced (long term evolution advanced, LTE-a), universal mobile system (universal mobile telecommunication system, UMTS), worldwide interoperability for microwave access (worldwide interoperability for microwave access, wiMAX), 5G New air interface (New Radio, NR), and the like. Terminal devices and network devices are included in these various systems. Core network parts such as evolved packet system (Evloved Packet System, EPS), 5G system (5 GS) etc. may also be included in the system.

The terminal device according to the embodiments of the present application may be a device that provides voice and/or data connectivity to a user, a handheld device with a wireless connection function, or other processing device connected to a wireless modem, etc. The names of the terminal devices may also be different in different systems, for example in a 5G system, the terminal devices may be referred to as User Equipment (UE). The wireless terminal device may communicate with one or more Core Networks (CNs) via a radio access Network (Radio Access Network, RAN), which may be mobile terminal devices such as mobile phones (or "cellular" phones) and computers with mobile terminal devices, e.g., portable, pocket, hand-held, computer-built-in or vehicle-mounted mobile devices that exchange voice and/or data with the radio access Network. Such as personal communication services (Personal Communication Service, PCS) phones, cordless phones, session initiation protocol (Session Initiated Protocol, SIP) phones, wireless local loop (Wireless Local Loop, WLL) stations, personal digital assistants (Personal Digital Assistant, PDAs), and the like. The wireless terminal device may also be referred to as a system, subscriber unit (subscriber unit), subscriber station (subscriber station), mobile station (mobile), remote station (remote station), access point (access point), remote terminal device (remote terminal), access terminal device (access terminal), user terminal device (user terminal), user agent (user agent), user equipment (user device), and the embodiments of the present application are not limited.

The base station according to the embodiment of the application may include a plurality of cells for providing services for the terminal. A base station may also be called an access point or may be a device in an access network that communicates over the air-interface, through one or more sectors, with wireless terminal devices, or other names, depending on the particular application. The network device may be operable to exchange received air frames with internet protocol (Internet Protocol, IP) packets as a router between the wireless terminal device and the rest of the access network, which may include an Internet Protocol (IP) communication network. The network device may also coordinate attribute management for the air interface. For example, the network device according to the embodiments of the present application may be a network device (Base Transceiver Station, BTS) in a global system for mobile communications (Global System for Mobile communications, GSM) or code division multiple access (Code Division Multiple Access, CDMA), a network device (NodeB) in a wideband code division multiple access (Wide-band Code Division Multiple Access, WCDMA), an evolved network device (evolutional Node B, eNB or e-NodeB) in a long term evolution (long term evolution, LTE) system, a 5G base station (gNB) in a 5G network architecture (next generation system), a home evolved base station (Home evolved Node B, heNB), a relay node (relay node), a home base station (femto), a pico base station (pico), and the like. In some network structures, the network device may include a Centralized Unit (CU) node and a Distributed Unit (DU) node, which may also be geographically separated.

Multiple-input Multiple-output (Multi Input Multi Output, MIMO) transmissions, which may be Single-User MIMO (SU-MIMO) or Multiple-User MIMO (MU-MIMO), may each be performed between a base station and a terminal device using one or more antennas. The MIMO transmission may be 2D-MIMO, 3D-MIMO, FD-MIMO, or massive-MIMO, or may be diversity transmission, precoding transmission, beamforming transmission, or the like, depending on the form and number of the root antenna combinations.

It will be appreciated by those skilled in the art that embodiments of the present application may be provided as a method, system, or computer program product. Accordingly, the present application may take the form of an entirely hardware embodiment, an entirely software embodiment, or an embodiment combining software and hardware aspects. Furthermore, the present application may take the form of a computer program product embodied on one or more computer-usable storage media (including, but not limited to, magnetic disk storage, optical storage, and the like) having computer-usable program code embodied therein.

The present application is described with reference to flowchart illustrations and/or block diagrams of methods, apparatus (systems) and computer program products according to embodiments of the application. It will be understood that each flow and/or block of the flowchart illustrations and/or block diagrams, and combinations of flows and/or blocks in the flowchart illustrations and/or block diagrams, can be implemented by computer-executable instructions. These computer-executable instructions may be provided to a processor of a general purpose computer, special purpose computer, embedded processor, or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, create means for implementing the functions specified in the flowchart flow or flows and/or block diagram block or blocks.

These processor-executable instructions may also be stored in a processor-readable memory that can direct a computer or other programmable data processing apparatus to function in a particular manner, such that the instructions stored in the processor-readable memory produce an article of manufacture including instruction means which implement the function specified in the flowchart flow or flows and/or block diagram block or blocks.

These processor-executable 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.

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 spirit or 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 cover such modifications and variations.

Claims

1. A transmission method applied to a first radio access network element, comprising:

the first wireless access network element sends first information to a terminal, wherein the first information is used for indicating the corresponding relation between a PDCP count value of a first bearing of the terminal and a PDCP count value of a second bearing or indicating the corresponding relation between a PDCP sequence number of the first bearing of the terminal and a PDCP sequence number of the second bearing;

the first information comprises second information and third information, the second information is a count value or a sequence number of a first PDCP data packet in the first bearing, and the third information is a count value or a sequence number of a second PDCP data packet in the second bearing; the first PDCP data packet is a data packet which is received in the first bearing in a cut-off way, and the second PDCP data packet is a data packet which is received in the second bearing in a start way; the service data contained in the first PDCP data packet and the second PDCP data packet are both first service data.

2. The method of claim 1, wherein the first bearer is a source radio bearer or a temporary radio bearer and the second bearer is a target radio bearer.

3. The method of claim 1, wherein after the first radio access network element sends the first information to the terminal, further comprising:

the first radio access network element releases the first bearer.

4. The method of claim 1, wherein before the first radio access network element sends the first information to the terminal, further comprising:

5. The method of claim 4, wherein the fifth information further comprises a count value or sequence number of a first PDCP packet in the first bearer, the first PDCP packet being a data packet in the first bearer that was received with a cutoff.

6. The method according to claim 4 or 5, further comprising:

7. The method of claim 1, wherein prior to the step of the first radio access network element sending the first information to the terminal, further comprising:

8. A transmission method applied to a terminal, comprising:

the terminal receives first information sent by a first radio access network element, wherein the first information is used for indicating the corresponding relation between a PDCP count value of a first bearer and a PDCP count value of a second bearer of the terminal or indicating the corresponding relation between a PDCP sequence number of the first bearer and a PDCP sequence number of the second bearer of the terminal;

9. The method as recited in claim 8, further comprising:

or,

10. The method of claim 8, wherein after the terminal receives the first information sent by the first radio access network element, the method further comprises:

11. The method of claim 8, wherein after the terminal receives the first information sent by the first radio access network element, the method further comprises:

12. The method of claim 8, wherein after the terminal receives the first information sent by the first radio access network element, the method further comprises:

and the terminal releases the first bearing.

13. A radio access network element comprising a memory, a transceiver, and a processor:

transmitting first information to a terminal, wherein the first information is used for indicating the corresponding relation between a PDCP count value of a first bearer and a PDCP count value of a second bearer of the terminal or indicating the corresponding relation between a PDCP sequence number of the first bearer and a PDCP sequence number of the second bearer of the terminal;

14. The radio access network element of claim 13, wherein after the sending the first information to the terminal, further comprising:

releasing the first bearer.

15. The radio access network element of claim 13, wherein before the sending the first information to the terminal, further comprises:

16. The radio access network element of claim 15, wherein the fifth information further comprises a count value or a sequence number of a first PDCP packet in the first bearer, the first PDCP packet being a data packet in the first bearer that was received with a cutoff.

17. The radio access network element according to claim 15 or 16, wherein the processor is further configured to:

18. The radio access network element of claim 13, wherein prior to the step of sending the first information to the terminal, further comprising:

19. A terminal comprising a memory, a transceiver, and a processor:

Receiving first information sent by a network element of a first radio access network, wherein the first information is used for indicating the corresponding relation between a PDCP count value of a first bearer of the terminal and a PDCP count value of a second bearer, or indicating the corresponding relation between a PDCP sequence number of the first bearer of the terminal and a PDCP sequence number of the second bearer;

20. The terminal of claim 19, wherein the processor is further configured to:

Or,

21. The terminal of claim 19, wherein after receiving the first information sent by the first radio access network element, further comprises:

22. The terminal of claim 19, wherein after receiving the first information sent by the first radio access network element, further comprises:

23. The terminal of claim 19, wherein after receiving the first information sent by the first radio access network element, further comprises:

Releasing the first bearer.

24. A radio access network element, comprising:

a first information sending unit, configured to send first information to a terminal, where the first information is used to indicate a correspondence between a PDCP count value of a first bearer and a PDCP count value of a second bearer of the terminal, or indicate a correspondence between a PDCP sequence number of the first bearer and a PDCP sequence number of the second bearer of the terminal;

25. A terminal, comprising:

a first information receiving unit, configured to receive first information sent by a first radio access network element, where the first information is used to indicate a correspondence between a PDCP count value of a first bearer and a PDCP count value of a second bearer of the terminal, or indicate a correspondence between a PDCP sequence number of the first bearer and a PDCP sequence number of the second bearer of the terminal;

26. A processor-readable storage medium, characterized in that the processor-readable storage medium stores a computer program for causing the processor to perform the method of any one of claims 1 to 12.