CN111757399A

CN111757399A - Switching method, device and system in wireless communication system

Info

Publication number: CN111757399A
Application number: CN201910246863.XA
Authority: CN
Inventors: 严乐; 张宏平; 曾清海; 耿婷婷; 胡星星
Original assignee: Huawei Technologies Co Ltd
Current assignee: Huawei Technologies Co Ltd
Priority date: 2019-03-29
Filing date: 2019-03-29
Publication date: 2020-10-09
Anticipated expiration: 2039-03-29
Also published as: CN111757399B; WO2020199892A1

Abstract

The application provides a switching method, a device and a system in a wireless communication system. A target base station receives a first data packet from core network equipment, wherein the first data packet is a first backup data packet sent by the core network equipment after a backup process is started; a source base station receives a second data packet from the core device, wherein the second data packet is a copy of the first data packet; the source base station receives first indication information from the core network equipment, wherein the first indication information indicates whether the source base station needs to send a serial number state transfer message to the target base station; when the first indication information indicates that the source base station does not need to send a sequence number state transfer message to the target base station, the target base station allocates a packet data convergence protocol sequence number (PDCP SN) to the first data packet to obtain a third data packet, wherein the PDCP SN of the third data packet is a preset value. The scheme can reduce the data transmission time delay and the switching scheme is more flexible to realize.

Description

Switching method, device and system in wireless communication system

Technical Field

The present application relates to the field of communications technologies, and in particular, to a handover method, apparatus, and system in a wireless communication system.

Background

In a mobile communication system, along with movement of User Equipment (UE), a network switches the UE from a source cell to a target cell for data transmission through a switching process, after an air interface sends a command for switching to the UE, a source base station stops performing uplink and downlink data transmission with the UE, and then the source base station sends a sequence number status transfer (SN status transfer) message to the target base station and forwards (forwards) a data packet to the target base station, for example, for an uplink, the SN status transfer message may indicate a Sequence Number (SN) of a UE that is not successfully received by the source base station, the SN status transfer message may also indicate a reception state of a data packet that the UE needs to retransmit in the target cell, and the source base station forwards the received uplink data packet of a sequence to the target base station; for downlink, the SN status transfer message may indicate an initial value when the target base station assigns a sequence number value to a downlink Data Packet to which no sequence number is assigned, where the sequence number may be, for example, a Packet Data Convergence Protocol (PDCP) sequence number, and the source base station may forward to the target base station a downlink Data Packet that has been sent to the user equipment but has not been successfully received by the user equipment, and a Data Packet newly received from the core network. Before and after the switching, for the same load/service, the data transmission which can not be completed by the user equipment at the source base station is continuously completed at the target base station after the user equipment is successfully switched to the target base station.

In the above switching process, the data packet forwarding between the source base station and the target base station may cause a time delay, and especially when the backhaul between the base stations is not ideal, the data transmission time delay is large, thereby reducing the experience of the user on the time delay sensitive service.

Disclosure of Invention

The application provides a switching method, a device and a system, which can reduce data transmission delay and improve switching flexibility.

In a first aspect, a handover method is provided, including: a target base station receives a first data packet from core network equipment, wherein the first data packet is a first backup data packet sent by the core network equipment after a backup process is started; a source base station receives a second data packet from the core device, wherein the second data packet is a copy of the first data packet; the source base station receives first indication information from the core network equipment, wherein the first indication information indicates whether the source base station needs to send a serial number state transfer message to the target base station; when the first indication information indicates that the source base station does not need to send a sequence number state transfer message to the target base station, the target base station allocates a packet data convergence protocol sequence number (PDCP SN) to the first data packet to obtain a third data packet, wherein the PDCP SN of the third data packet is a preset value.

According to the scheme, the data transmission time delay is reduced, and the flexibility of realizing the switching scheme is improved.

With reference to the first aspect, in a first possible implementation, the method further includes: the target base station sends the third data packet to User Equipment (UE); and the source base station sends a fourth data packet to the UE, wherein the payload of the fourth data packet is the same as that of the second data packet.

With reference to the first aspect or the first possible implementation manner of the first aspect, in a second possible implementation manner, the preset value is 0.

With reference to the first aspect or the first or second possible implementation manner of the first aspect, in a third possible implementation manner, a value of a data radio bearer identifier corresponding to the third data packet is different from a value of a data radio bearer identifier corresponding to the fourth data packet.

With reference to the third possible implementation manner of the first aspect, in a fourth possible implementation manner, the method further includes: and the source base station sends the value of the data radio bearer identification corresponding to the third data packet and the value of the data radio bearer identification corresponding to the fourth data packet to the UE.

With reference to the first aspect or the first or second possible implementation manner of the first aspect, in a fifth possible implementation manner, a value of the data radio bearer identifier corresponding to the third data packet is the same as a value of the data radio bearer identifier corresponding to the fourth data packet.

With reference to the fifth possible implementation manner of the first aspect, in a sixth possible implementation manner, the method further includes: and the source base station sends second indication information to the UE, wherein the second indication information indicates the value of the PDCP serial number of the fourth data packet.

In a second aspect, a handover method is provided, including: the method comprises the steps that core network equipment sends a first data packet to a target base station, wherein the first data packet is a first backup data packet sent by the core network equipment after a backup process is started; the core equipment sends a second data packet to a source base station, wherein the second data packet is a copy of the first data packet; the core network equipment sends first indication information to the source base station, and the first indication information indicates whether the source base station needs to send a serial number state transition message to the target base station.

In a third aspect, a handover method is provided, including: the method comprises the steps that User Equipment (UE) receives a third data packet from a target base station, the third data packet is the same as the payload of a first backup data packet sent by core network equipment after a backup process is started, and the value of a Packet Data Convergence Protocol (PDCP) sequence number (PDCP SN) of the third data packet is a preset value; the UE receives a fourth data packet from the source base station.

With reference to the third aspect, in a first possible implementation manner, the payload of the fourth data packet is the same as the payload of the third data packet.

With reference to the third aspect or the first possible implementation manner of the third aspect, in a second possible implementation manner, the preset value is 0.

With reference to the third aspect or the first or second possible implementation manner of the third aspect, in a third possible implementation manner, a value of a data radio bearer identifier corresponding to the third data packet is different from a value of a data radio bearer identifier corresponding to the fourth data packet.

With reference to the third possible implementation manner of the third aspect, in a fourth possible implementation manner, the method further includes: and the UE receives a value of a data radio bearer identification corresponding to the third data packet and a value of a data radio bearer identification corresponding to the fourth data packet from the source base station.

With reference to the third aspect or the first or second possible implementation manner of the third aspect, in a fifth possible implementation manner, a value of the data radio bearer identifier corresponding to the third data packet is the same as a value of the data radio bearer identifier corresponding to the fourth data packet.

With reference to the fifth possible implementation manner of the third aspect, in a sixth possible implementation manner, the method further includes: the UE performs at least one of the following operations on the third data packet and the fourth data packet according to the HRP sequence number: and detecting repeated packets, reordering, and submitting in sequence.

With reference to the fifth possible implementation manner of the third aspect, in a seventh possible implementation manner, the method further includes: in a time period from when the UE receives the third data packet to when the UE disconnects data transmission with the source base station, the UE ignores data packet disorder or duplication of the PDCP layer, and performs at least one of the following operations on the received data packet according to an HRP sequence number: and detecting repeated packets, reordering, and submitting in sequence.

With reference to the fifth possible implementation manner of the third aspect, in an eighth possible implementation manner, the method further includes: the UE receives second indication information from the source base station, wherein the second indication information indicates the value of the PDCP sequence number of the fourth data packet.

With reference to the eighth possible implementation manner of the third aspect, in a ninth possible implementation manner, the method further includes: the UE determines that the third data packet is a copy of the fourth data packet according to the value of the PDCP sequence number of the fourth data packet and the preset value, and performs at least one of the following operations on the third data packet and the fourth data packet: and detecting repeated packets, reordering, and submitting in sequence.

In a fourth aspect, there is provided a communication system comprising: the target base station is used for receiving a first data packet from core network equipment, wherein the first data packet is a first backup data packet sent by the core network equipment after a backup process is started; a source base station, configured to receive a second data packet from the core device, where the second data packet is a copy of the first data packet; the source base station is further configured to receive first indication information from the core network device, where the first indication information indicates whether the source base station needs to send a sequence number state transition message to the target base station; the target base station is further configured to allocate a packet data convergence protocol sequence number PDCP SN to the first data packet to obtain a third data packet when the first indication information indicates that the source base station does not need to send a sequence number state transfer message to the target base station, where the PDCP SN of the third data packet is a preset value.

With reference to the fourth aspect, in a first possible implementation scheme, the target base station is further configured to send the third data packet to a user equipment UE; the source base station is further configured to send a fourth data packet to the UE, where a payload of the fourth data packet is the same as a payload of the second data packet.

With reference to the fourth aspect or the first possible implementation manner of the fourth aspect, in a second possible implementation manner, the preset value is 0.

With reference to the fourth aspect or the first or second possible implementation manner of the fourth aspect, in a third possible implementation manner, a value of a data radio bearer identifier corresponding to the third data packet is different from a value of a data radio bearer identifier corresponding to the fourth data packet.

With reference to the third possible implementation manner of the fourth aspect, in a fourth possible implementation manner, the source base station is further configured to send, to the UE, a value of a data radio bearer identifier corresponding to the third data packet and a value of a data radio bearer identifier corresponding to the fourth data packet.

With reference to the fourth aspect or the first or second possible implementation manner of the fourth aspect, in a fifth possible implementation manner, a value of the data radio bearer identifier corresponding to the third data packet is the same as a value of the data radio bearer identifier corresponding to the fourth data packet.

With reference to the fifth possible implementation manner of the fourth aspect, in a sixth possible implementation manner, the source base station is further configured to send second indication information to the UE, where the second indication information indicates a value of a PDCP sequence number of the fourth packet.

In a fifth aspect, a core network device is provided, including: a processing unit for starting a backup process; a sending unit, configured to send a first data packet to a target base station, where the first data packet is a first backup data packet sent by the core network device after starting a backup process; the sending unit is further configured to send a second data packet to a source base station, where the second data packet is a copy of the first data packet; the sending unit is further configured to send first indication information to the source base station, where the first indication information indicates whether the source base station needs to send a serial number state transition message to the target base station.

In a sixth aspect, a user equipment is provided, including: a receiving unit, configured to receive a third data packet from a target base station, where the third data packet is the same as a payload of a first backup data packet sent after a core network device starts a backup process, and a value of a packet data convergence protocol sequence number PDCP SN of the third data packet is a preset value; the receiving unit is further configured to receive a fourth data packet from the source base station; and the processing unit is used for obtaining the third data packet and the fourth data packet.

With reference to the sixth aspect, in a first possible implementation manner, the payload of the fourth data packet is the same as the payload of the third data packet.

With reference to the sixth aspect or the first possible implementation manner of the sixth aspect, in a second possible implementation manner, the preset value is 0.

With reference to the sixth aspect or the first or second possible implementation manner of the sixth aspect, in a third possible implementation manner, a value of a data radio bearer identifier corresponding to the third data packet is different from a value of a data radio bearer identifier corresponding to the fourth data packet.

With reference to the third possible implementation manner of the sixth aspect, in a fourth possible implementation manner, the receiving unit is further configured to receive a value of a data radio bearer identifier corresponding to the third data packet and a value of a data radio bearer identifier corresponding to the fourth data packet from the source base station.

With reference to the sixth aspect or the first or second possible implementation manner of the sixth aspect, in a fifth possible implementation manner, a value of the data radio bearer identifier corresponding to the third data packet is the same as a value of the data radio bearer identifier corresponding to the fourth data packet.

With reference to the fifth possible implementation manner of the sixth aspect, in a sixth possible implementation manner, the processing unit is further configured to perform, according to an HRP sequence number, at least one of the following operations on the third data packet and the fourth data packet: and detecting repeated packets, reordering, and submitting in sequence.

With reference to the fifth possible implementation manner of the sixth aspect, in a seventh possible implementation manner, the processing unit is further configured to, within a time period from when the UE receives the third data packet to when the UE disconnects data transmission with the source base station, ignore packet misordering or duplication of a PDCP layer, and perform at least one of the following operations on the received data packet according to an HRP sequence number: and detecting repeated packets, reordering, and submitting in sequence.

With reference to the fifth possible implementation manner of the sixth aspect, in an eighth possible implementation manner, the receiving unit is configured to receive second indication information from the source base station, where the second indication information indicates a value of a PDCP sequence number of the fourth data packet.

With reference to the eighth possible implementation manner of the sixth aspect, in a ninth possible implementation manner, the processing unit is further configured to determine, according to the value of the PDCP sequence number of the fourth data packet and the preset value, that the third data packet is a duplicate of the fourth data packet, and perform at least one of the following operations on the third data packet and the fourth data packet: and detecting repeated packets, reordering, and submitting in sequence.

In a seventh aspect, a communication method is provided, including: the source base station generates third indication information; and the source base station sends third indication information to User Equipment (UE), wherein the third indication information indicates the UE to start an HRP layer function.

In the scheme, the UE can normally carry out operations such as repeated packet detection or reordering, and the like, thereby ensuring the data transmission efficiency.

With reference to the seventh aspect, in a first possible implementation manner, after the source base station sends the third indication information, the method further includes: and the source base station sends a switching request message to the target base station.

With reference to the seventh aspect, in a second possible implementation manner, before the source base station sends the third indication information, the method further includes: and the source base station sends a switching request message to the target base station.

With reference to the seventh aspect or any one of the foregoing implementation manners, in a third possible implementation manner, the method further includes: the source base station receives capability information from the UE, wherein the capability information indicates whether the UE supports HRP layer functions.

In an eighth aspect, a communication method is provided, including: user Equipment (UE) receives third indication information from a source base station, wherein the third indication information indicates the UE to start an HRP layer function; and the UE responds to the third indication information and starts HRP layer functions.

With reference to the eighth aspect, in a first possible implementation manner, the method further includes: and the UE sends the capability information of the UE to the source base station, wherein the capability information indicates whether the UE supports the function of an HRP layer.

In a ninth aspect, there is provided a base station comprising: a processing unit for generating third indication information; a sending unit, configured to send third indication information to a user equipment UE, where the third indication information indicates that the UE starts an HRP layer function.

With reference to the ninth aspect, in a first possible implementation manner, after the sending unit sends the third indication information, the sending unit is further configured to send a handover request message to a target base station.

With reference to the ninth aspect, in a second possible implementation manner, before the sending unit sends the third indication information, the sending unit is further configured to send a handover request message to a target base station.

With reference to the ninth aspect or any one of the foregoing implementation manners, in a third possible implementation manner, the method further includes: a receiving unit, configured to receive capability information from the UE, where the capability information indicates whether the UE supports an HRP layer function.

In a tenth aspect, a user equipment UE is provided, including: a receiving unit, configured to receive third indication information from a source base station, where the third indication information indicates that the UE starts an HRP layer function; and the processing unit is used for responding to the third indication information and starting an HRP layer function.

With reference to the tenth aspect, in a first possible implementation manner, the user equipment further includes: a sending unit, configured to send capability information of the UE to the source base station, where the capability information indicates whether the UE supports an HRP layer function.

The units in the communication apparatus described in the above aspects may be implemented by software, or hardware, or a combination of software and hardware. The elements of the above described scheme may be implemented by one or more of software or hardware.

In another aspect, the present application provides a communication system, which includes the foregoing source base station, target base station, and core network device.

In another aspect, the present application provides a communication system, which includes the foregoing source base station, target base station, and user equipment.

In one possible implementation, the communication device of the above aspects includes one or more processors, and one or more memories having stored thereon instructions or agents executable by the one or more processors to cause the communication device to perform the method of the above aspects when the instructions or code are executed.

Yet another aspect of the present application provides a computer-readable storage medium having stored therein instructions, which when executed on a computer, cause the computer to perform the method of the above-described aspects.

Yet another aspect of the present application provides a computer program product containing instructions which, when run on a computer, cause the computer to perform the method of the above-described aspects.

Drawings

In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below.

FIG. 1 is a schematic diagram of a possible system architecture for implementing an embodiment of the present invention;

fig. 2 is a flowchart of a handover method according to an embodiment of the present invention;

fig. 3 is a flowchart of a communication method according to an embodiment of the present invention;

fig. 4 is a schematic diagram of a protocol stack according to an embodiment of the present invention;

fig. 5 is a schematic diagram of another protocol stack provided in the embodiment of the present invention;

fig. 6 is a schematic diagram of another protocol stack provided in the embodiment of the present invention;

fig. 7 is a flowchart of a handover method according to an embodiment of the present invention;

fig. 8 is a flowchart of a communication method according to an embodiment of the present invention;

fig. 9 is a schematic structural diagram of a base station according to an embodiment of the present invention;

fig. 10 is a schematic structural diagram of another base station according to an embodiment of the present invention;

fig. 11 is a schematic structural diagram of a user equipment according to an embodiment of the present invention;

fig. 12 is a schematic structural diagram of another ue according to an embodiment of the present invention;

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

fig. 14 is a schematic structural diagram of a core network device according to an embodiment of the present invention.

Detailed Description

The embodiments of the present invention will be described in detail below with reference to the accompanying drawings. The network architecture and the service scenario described in the embodiment of the present invention are for more clearly illustrating the technical solution of the embodiment of the present invention, and do not form a limitation on the technical solution provided in the embodiment of the present invention, and it can be known by those skilled in the art that the technical solution provided in the embodiment of the present invention is also applicable to similar technical problems along with the evolution of the network architecture and the appearance of a new service scenario.

Fig. 1 shows a schematic diagram of a possible system network of the present application. As shown in fig. 1, at least one terminal 10 communicates with a Radio Access Network (RAN). The RAN includes at least two base stations: base station 20 and base station 30, only two base stations and one user equipment UE being shown in the figure. The RAN is connected to a Core Network (CN). The core network includes one or more core network devices. Optionally, the CN may be coupled to one or more External networks (External networks), such as the Internet, Public Switched Telephone Network (PSTN), etc. In the moving process, the connection between the UE and the radio access network may be switched from the base station 20 to the base station 30, in which case, the base station 20 may be referred to as a source base station, and the base station 30 may be referred to as a target base station.

Some of the terms referred to in this application are described below for the sake of clarity.

In this application, the terms "network" and "system" are often used interchangeably. But the meaning will be understood by those skilled in the art. The communication device described in this application refers to a network element in a communication system, such as a terminal, a base station (a source base station or a target base station), and a core network device.

The terminal is sometimes called User Equipment (UE). A UE is a terminal device with communication capabilities, also referred to as a terminal, and may include a handheld device with wireless communication capabilities, a vehicle mounted device, a wearable device, a computing device or other processing device connected to a wireless modem, etc. The user devices may be called different names in different networks, for example: a terminal, mobile station, subscriber unit, station, cellular telephone, personal digital assistant, wireless modem, wireless communication device, handheld device, laptop computer, cordless telephone, wireless local loop station, or the like. For convenience of description, the UE or the terminal is simply referred to as user equipment UE or terminal in this application.

The Base Station (BS) may be a device having a wireless transceiving function, such as a wireless access device or a relay station in a cloud network. A base station, which may also be referred to as a base station device, is a network device deployed in a radio access network to provide wireless communication functions. The names of base stations may be different in different radio access systems, for example, in a Universal Mobile Telecommunications System (UMTS) network, a base station is called a node B (NodeB), in an LTE network, an evolved node B (eNB or eNodeB), and in a 5G System, a base station is called a Transmission Reception Point (TRP), a G node B (gbodeb, gNB). The base station may contain one or more co-sited or non co-sited TRPs. The base station may also be a radio controller, a Centralized Unit (CU), and/or a Distributed Unit (DU) in a Cloud Radio Access Network (CRAN) scenario. The base station may also be a server, a wearable device, or a vehicle mounted device, etc. For convenience of description, the following description uses a base station. Optionally, the base station in the present invention may also be a user equipment in Device-to-Device D2D (Device to Device). Optionally, the base station and the user equipment in the present invention may also be relay equipment, or network equipment or user equipment implementing a relay function.

The following takes a 5G network as an example to describe the scheme provided in the embodiment of the present invention, but the scheme of the present invention is not limited to the 5G network, for example, the scheme of the present invention may also be applied to LTE, a subsequent evolution network, or a plurality of converged networks, and the like, and the embodiment of the present invention does not limit this.

The following first illustrates the backup process of the data packet during the handover process and the involved protocol stack, but the present invention is not limited to the implementation described below.

And (3) data backup process:

this scheme can be applied to the system shown in fig. 1. As shown in fig. 2:

step 201, the source base station sends a handover request message to the target base station.

In this embodiment, when the source base station determines that the UE needs to be switched from the source base station to the target base station, the source base station sends a switching request message to the target base station to request to switch the UE to the target base station.

Step 202, the target base station, in response to the handover request message, sends a request message to the first core network device to request a copy of a first data packet, where the first data packet is a data packet for the user equipment UE, sent to the source base station by the second core network device.

Optionally, the first core network device may be an Access and mobility management Function (AMF) device, and the second core network device may be a User Plane Function (UPF) device.

Optionally in this embodiment of the present invention, the first core network device and the second core network device may be the same core network device or different core network devices.

For convenience of description, the "core network device" function is described in this application, and the first core network device or the second core network device may include the function of the core network device unless otherwise specified.

The request message may be, for example, a backup request (replication request) message, or the request message may have other representations and names, which are not limited thereto.

In some scenarios, the target base station sends a request message, such as a duplicate request, which may also be understood as requesting a core network device to send the first data packet to the source base station and requesting the core network device to send a copy of the first data packet to the target base station.

The copy of the first packet may be referred to as a second packet. The first packet and the second packet, at least a payload (payload), are identical. The contents of the first and second packets may or may not be identical (e.g., the payloads are the same and other information is different).

Optionally, the core network device may include one or more of the following functional entities: access and Mobility Management Function (AMF), Session Management Function (SMF), or User Plane Function (UPF). The AMF is sometimes also referred to as an AMF device, an AMF entity, or other name, the SMF is sometimes also referred to as an SMF device, an SMF entity, or other name, and the UPF is sometimes also referred to as a UPF device, a UPF entity, or other name. In addition, the core network device may further include other functional entities. These functional entities may be separate physical entities, or may be physically combined together, which is not limited to this embodiment of the present invention.

In an implementation manner, the requesting, by the target base station, the second core network device to send a copy of the first data packet to the target base station may specifically be:

the target base station sends the request message to an Access and Mobility Management Function (AMF) device, where the request message may include a Protocol Data Unit (PDU) session identifier (e.g., PDU session ID), a Quality of service (QoS) Flow identifier (e.g., the list of accepted QoS Flow IDs (s)) accepted/allowed by the source base station, and address information and UE identification information of the target base station. Optionally, the request message may further include capability information of the UE, for example, information whether the UE supports a High Reliability Protocol (HRP) layer function. In an embodiment of the present invention, the HRP layer function may include at least one of the following functions: generating/processing a sequence number of QoS flow granularity (or Data Radio Bearer (DRB) granularity), and performing operations such as duplicate packet detection, reordering, and sequential delivery on a Data packet according to the sequence number of QoS flow granularity (or DRB granularity), where specific details may refer to protocol stack description later and are not described herein again. In the embodiment of the present invention, the nomenclature of the HRP layer is only an example, and other naming manners are also possible. The HRP layer function may be implemented by a newly introduced protocol layer, such as a newly introduced HRP (or other naming) layer, or the HPR layer function may be implemented by a certain layer of an existing protocol stack, for example, a GPRS tunneling protocol-user plane (GTP-U) layer or other protocol layers, which is not limited in the present invention.

After receiving the request message, the AMF device performs a Session update (Session update) procedure with a Session Management Function (SMF) device; the SMF device performs a session modification (session modification) procedure with a User Plane Function (UPF) device. Optionally, the address information of the target base station may be at least one of: IP address, or GPRS tunneling protocol tunnel endpoint identification (GTP tunnel endpoint Identifier). The address information of the target base station can be used for the core network equipment to determine the address of the target base station, and a channel for transmitting data can be established between the core network equipment and the target base station; the UE identity information may include at least one of: RAN UE NGAP ID, Source NG-RAN node UE XnAP ID reference, Source AMF UE NGAP ID, wherein RAN UE NGAP ID (new generation application protocol identification of wireless access network user equipment) is identification distributed by a Source base station, and NG interface (interface between NG-RAN node and core network equipment, such as AMF equipment) can identify UE according to the identification; source AMF UE NGAP ID (Source access and mobility management function user equipment new generation application protocol identifier) is an identifier allocated by a Source AMF device, the identifier corresponds to a connection (Source NG-C connection) of a Source new generation control plane, a NG interface (i.e. an interface between an NG-RAN node and a core network device, such as an AMF device) can identify the UE according to the identifier, and the identifier can be used to index UE context information at the Source AMF device (or an AMF device serving the AMF device, i.e. a Source base station is connected to the AMF device); the Source NG-RAN node UE XnAP ID reference (Source new generation radio access network node user equipment Xn application protocol identity reference) is an identity allocated by the Source base station, and the UE can be identified on the Xn interface (i.e. the interface between two base stations) according to the identity. The UE identification information may be used to uniquely identify the UE in an access network RAN (e.g., a base station) or a core network CN (e.g., a core network device), so that the core network device can establish a channel for transmitting data with a target base station. Optionally, when the AMF device and the SMF device perform a session update procedure, the session update request message (e.g., the session update request message) may include at least one of a PDU session ID, a QoS Flow identifier accepted/allowed by the source base station, address information of the target base station, and UE identifier information, which is not limited in the embodiment of the present invention; optionally, when the SMF device and the UPF device perform the session modification procedure, the session modification request message (e.g., the session modification request message) may include at least one of a PDU session ID, a QoS Flow identifier accepted/allowed by the source base station, address information of the target base station, and UE identifier information, which is not limited in the embodiment of the present invention.

Optionally, in this embodiment, a session update (session update) procedure is performed between the AMF device and the SMF device, and a session modification (session modification) procedure is performed between the SMF device and the UPF device.

For example, as shown in fig. 3, the AMF device sends a session update request (session update request) message to the SMF device, and optionally, the session update request (session update request) message may further include capability information of the UE, for example, information whether the UE supports the HRP layer function. The SMF device sends a session modification request (session modification request) message to the UPF device after receiving the request message, and optionally, the session modification request (session modification request) message may further include capability information of the UE, for example, information whether the UE supports an HRP layer function. The method comprises the steps that session modification is carried out by UPF equipment according to a request of SMF equipment, then the UPF equipment replies a sessionmodulation request ACK message to the SMF equipment, after receiving the ACK message, the SMF equipment sends a sessionupdate request ACK message to AMF equipment, after receiving the ACK message, the AMF equipment sends a reply message (such as a backup request acknowledgement message ACK) corresponding to a request message (such as a backup request message) sent to the AMF equipment by a target base station to the target base station, and after receiving the backup request acknowledgement message, the target base station sends a switching request acknowledgement message to a source base station.

In this embodiment, for downlink data transmission, the UPF device performs packet backup (duplication), the UPF device sends the first packet to the source base station, and a process of sending a copy of the first packet to the target base station by the UPF device may be referred to as a backup (duplication) process or a duplication operation, and the first packet and the copy of the first packet may be referred to as a backup (duplication) packet. For uplink data transmission, the user equipment performs packet backup (duplication), that is, a process in which the user equipment sends a fifth packet to the source base station and sends a copy of the fifth packet to the target base station may also be referred to as a backup (duplication) process or a duplication operation, and the fifth packet and the copy of the fifth packet may be collectively referred to as a backup (duplication) packet. It should be noted that the data carried by the data packet and the copy corresponding to the data packet may or may not be identical. For example, the data packets and the copies corresponding to the data packets are identical in at least payload (e.g., payload), but the two data packets may carry the same or different information, and in an example, the two data packets carry different address information, for example, one of the data packets carries address information of the source base station, the copies corresponding to the data packets carry address information of the target base station, and the other differences are not described herein.

In this embodiment, in the handover process, after receiving the handover request message, the target base station starts a channel (tunnel) establishment procedure between the target base station and the core network device (e.g., the AMF device, the SMF device, and the UPF device), that is, establishes a transmission channel between the target base station, the AMF device, the SMF device, and the UPF device. In the switching process, the UPF equipment can respectively send the backup data packets to the source base station and the target base station, and then the source base station and the target base station can respectively send the backup data packets received from the UPF equipment to the user equipment, and the source base station does not need to forward data to the target base station, so that the transmission delay caused by the data forwarding process is reduced.

Optionally, the method further includes:

step 203, the source base station receives the first data packet from the second core network device.

And step 204, the target base station receives a second data packet from the second core network device.

Optionally, the method further includes:

step 205, responding to the first data packet, the source base station sends a third data packet to the user equipment.

And step 206, responding to the second data packet, and sending a fourth data packet to the user equipment by the target base station.

In the embodiment of the present invention, a process in which the source base station sends the third data packet to the UE and the target base station sends the fourth data packet to the UE may also be referred to as a duplicate process. The third packet and the copy of the third packet (i.e., the fourth packet) may also be collectively referred to as a backup (duplication) packet.

In this embodiment of the present invention, optionally, the data for the UE carried by the first packet and the duplicate of the first packet (i.e., the second packet) are the same (e.g., the payload is the same), but the headers may be different (e.g., the address information is different).

In this embodiment, after receiving the first data packet, the source base station may perform corresponding processing on the first data packet, for example, data analysis, header processing, and the like, and then send the data packet to the UE, but the payload of the data packet of the UE is not changed. The target base station processes the copy of the first data packet similarly.

In this embodiment, optionally, after the UPF device starts the duplicate process, (for example, after a channel for transmitting a backup data packet between the target base station, the AMF device, the SMF device, and the UPF device is successfully established), when the UPF device wants to send a first backup data packet, an indication information may be sent to the source base station, where the indication information is, for example, an end marker (endmarker), and the indication information is used to notify the source base station that the UPF device starts the duplicate function, that is, the UPF device is about to start sending the data packet to the source base station and sending a copy corresponding to the data packet to the target base station. The indication information may also be carried in a header of a first backup data packet sent by the UPF device to the source base station after the UPF device starts the duplicate process, for example, the indication information may be included in a GTP-U header, which is not limited in this disclosure. Optionally, if the source base station receives the indication information, the data buffer of the source base station still has a data packet for the UE that is not sent, that is, the data buffer of the source base station buffers a non-backup data packet that is received by the source base station from the UPF device but is not sent to the user equipment before the duplication process is started, then: in one implementation, the source base station preferentially sends the unsent data packet for the UE to the user equipment by default, and the source base station sends the unsent data packet for the UE to the user equipment and then sends the backup data packet received from the UPF device to the user equipment; or, in another implementation, the indication information sent by the UPF device to the source base station may also be understood as that the indication information is used to indicate that the source base station preferentially sends a data packet for the UE that is not sent to the user equipment, that is, after the source base station receives the indication information, for example, the indication information may be an end marker or indication information included in a header of a first backup data packet sent by the UPF device to the source base station, the source base station preferentially sends the data packet for the UE that is not sent to the user equipment, and after sending the data packet for the UE that is not sent to the user equipment, the source base station sends the backup data packet received from the UPF device to the user equipment. This embodiment is not limited to this.

In this embodiment, optionally, for the uplink, after the UPF device starts the duplicate process (for example, after the channels for transmitting the backup data packet between the target base station, the AMF device, the SMF device, and the UPF device are successfully established), and after the connection between the UE and the target base station is established (for example, after the random access process between the UE and the target base station is successful and the UE is successfully switched to the target base station), the UE may also send the data packet to the source base station, and send the copy corresponding to the data packet to the target base station. The source base station and the target base station may respectively send the data packet and a copy corresponding to the data packet to the UPF device. Optionally, in the embodiment of the present invention, a process in which the source base station sends the data packet to the UPF device, and the target base station sends a copy of the data packet to the UPF device may also be referred to as a duplicate process. The packet and the copy of the packet may also be collectively referred to as a backup (replication) packet.

In this embodiment, in the preparation process for handover between the source base station and the target base station, a transmission channel is established between the target base station and the core network device, and duplicate operation is started, so that before the quality of a link between the UE and the source base station deteriorates, a channel for transmitting a backup data packet between the target base station and the core network device is successfully established, and therefore, data that cannot be successfully transmitted by the source base station can be transmitted through the target base station, so that data transmission delay in the handover process is reduced, and reliability of data transmission is ensured.

The protocol stack related to the embodiment of the invention comprises:

for any embodiment of the present invention, optionally, the corresponding user plane protocol stack may be as shown in fig. 4. Specifically, a Protocol stack corresponding to a core network device, such as a UPF device, includes a Physical (PHY) layer (also referred to as layer 1, L1), a layer 2 (for example, the layer 2 includes a Media Access Control (MAC) layer, a Radio Link Control (RLC) layer, a Packet Data Convergence Protocol (PDCP) layer, a Service Data Adaptation Protocol (SDAP) layer, a User Datagram Protocol/Internet Protocol (UDP/IP) layer, a GTP-U layer, a High Reliability Protocol (HRP) layer, and a Protocol Data Unit (PDU) layer; the access network device, such as a source base station or a target base station, has a corresponding protocol stack including a PHY layer, a layer 2 (e.g., the layer 2 includes a MAC layer, a RLC layer, a PDCP layer, and an SDAP layer), a UDP/IP layer, a GTP-U layer, and an HRP layer; the protocol stack corresponding to the user equipment, e.g. UE, includes PHY layer, layer 2 (e.g. layer 2 includes MAC layer, RLC layer, PDCP layer, and SDAP layer), PDU layer, and application layer. That is, different from the protocol stack structure shown in fig. 4, in the protocol stack architecture shown in fig. 4, a new layer (e.g., HRP layer) is introduced above the GTP-U layer of the base station, and the HRP layer may generate/process sequence numbers of QoS flow granularity (or DRB granularity), for example, the HRP layer of the base station may generate/process HRP SN; in addition, under the protocol stack architecture shown in fig. 4, a new layer (e.g., HRP layer) is introduced above the GTP-U layer of the UPF device, and the HRP layer may generate/process sequence numbers with QoS flow granularity (or DRB granularity), for example, the HRP layer of the UPF device may generate/process HRP SNs.

As shown in fig. 4, for downlink transmission, the UPF device needs to generate a sequence number with QoS flow granularity (or DRB granularity) for the backup data packets sent to the source base station and the target base station, and this function is implemented by an HRP layer, for example, the HRP layer of the UPF device generates an HRP SN; for uplink transmission, the UPF device processes sequence numbers of QoS flow granularity (or DRB granularity) for backup data packets respectively received from the source base station and the target base station, for example, the HRP layer of the UPF device processes HRP SNs, and the HRP layer of the UPF device performs operations of duplicate packet detection, reordering, in-order delivery, and the like according to the HRP SNs contained in the data packet headers.

As shown in fig. 4, for downlink transmission, the source base station or the target base station needs to process a sequence number of QoS flow granularity (or DRB granularity) for a backup data packet received from the core network device; for uplink transmission, the source base station or the target base station generates a sequence number of QoS flow granularity (or DRB granularity) for a backup data packet received from the UE. Specifically, for downlink transmission, a source base station or a target base station receives a backup data packet sent by a UPF device, a PDCP layer of the source base station determines, according to an HRP SN included in a header of the backup data packet, a PDCP SN corresponding to the received backup data packet, and the source base station can determine a mapping relationship between the HRP SN and the PDCP SN; the PDCP layer of the target base station may determine, according to the HRP SN included in the header of the backup data packet and the mapping relationship between the HRP SN and the PDCP SN (the target base station may receive the mapping relationship between the HRP SN and the PDCP SN from the source base station), the PDCP SN corresponding to the received backup data packet; for uplink transmission, a source base station or a target base station receives a backup data packet sent by a UE, the source base station determines, according to a PDCP SN included in a header of the backup data packet, an HRP SN corresponding to the received backup data packet, for example, the sequence number may be generated by an HRP layer, the source base station may determine a mapping relationship between the HRP SN and the PDCP SN, and the target base station may determine, according to a PDCPSN included in the header of the backup data packet and the mapping relationship between the HRP SN and the PDCP SN (the target base station may receive the mapping relationship between the HRP SN and the PDCP SN from the source base station), an HRP SN corresponding to the received backup data packet, for example, the sequence number may be generated by the HRP layer.

As shown in fig. 4, for downlink transmission, the UE needs to perform operations such as duplicate packet detection, reordering, and in-sequence delivery for backup data packets respectively received from the source base station and the target base station, for example, the PDCP layer of the UE may perform operations such as duplicate packet detection, reordering, and in-sequence delivery; for uplink transmission, the UE generates backup data packets to be respectively sent to the source base station and the target base station, for example, a PDCP layer of the UE may generate the backup data packets.

For any embodiment of the present invention, in another implementation manner, a corresponding User plane Protocol stack architecture may also be as shown in fig. 5, and specifically, a core network device, for example, an UPF device, includes a Physical (PHY) layer, a layer 2 (for example, the layer 2 includes a Media Access Control (MAC) layer, a Radio Link Control (RLC) layer, a Packet Data Convergence Protocol (PDCP) layer, a Service Data Adaptation Protocol (SDAP) layer, a User Datagram Protocol/Internet Protocol (User Datagram Protocol/Internet Protocol, UDP/IP) layer, a GTP-U layer, an HRP layer, and a Protocol Data Unit (PDU) layer; an access network device, such as a source base station or a target base station, corresponds to a Protocol stack including a physical layer (PHY), a layer 2 (e.g., the layer 2 includes a Medium Access Control (MAC) layer, a Radio Link Control (RLC) layer, a Packet Data Convergence Protocol (PDCP) layer, a Service Data Adaptation Protocol (SDAP) layer, a User Datagram Protocol/internet Protocol (UDP/IP) layer, a GTP-U layer, a User equipment, such as a UE, corresponding to the Protocol stack including a physical layer (PHY), the layer 2 (e.g., the layer 2 includes a Medium Access Control (MAC) layer, a radio link control (PDCP) layer, a control Protocol (RLC) layer, a packet Data convergence Protocol (RLC) layer, SDAP) layer), HRP layer, Protocol Data Unit (PDU) layer, and application layer.

As shown in fig. 5, for downlink transmission, the UPF device needs to generate a sequence number with QoS flow granularity for backup data packets sent to the source base station and the target base station, because QoS flow is of DRB granularity, that is, only one QoS flow can be mapped to the same DRB, and different QoS flows are mapped to different DRBs, it can also be understood that, for downlink transmission, the UPF device needs to generate a sequence number with DRB granularity for backup data packets sent to the source base station and the target base station, and this function is implemented by an HRP layer, for example, the HRP layer generates an HRP SN; for uplink transmission, the UPF device processes sequence numbers of QoS flow granularity (or DRB granularity) for backup data packets respectively received from the source base station and the target base station, for example, the HRP layer processes hrpn, and the HRP layer may perform operations such as duplicate packet detection, reordering, and in-sequence delivery.

As shown in fig. 5, for downlink transmission, the source base station or the target base station transmits the backup data packet received from the core network device to the user equipment, and the target base station may also transmit the backup data packet received from the core network device to the user equipment. For uplink, the source base station sends the backup data packet received from the user equipment to the UPF device, and the target base station also sends the backup data packet received from the user equipment to the UPF device. It should be noted that in the protocol stack architecture shown in fig. 5, the HRP layer is transparent to the source base station (or the target base station), that is, the base station does not need to process the sequence number of the QoS flow granularity (or DRB granularity), that is, for DL, the base station does not need to process the hrpn included in the data packet received from the UPF device; in response to the UL, the base station does not need to process the HRP SN included in the packet received from the UE.

As shown in fig. 5, for the UE, for downlink transmission, it needs to perform operations such as duplicate packet detection, reordering, and in-sequence delivery on backup data packets respectively received from the source base station and the target base station, for example, the HRP layer of the UE performs operations such as duplicate packet detection, reordering, and in-sequence delivery; for uplink transmission, the UE generates backup data packets and sends the backup data packets to the source base station and the target base station, for example, an HRP layer of the UE performs data packet backup and sends the backup data packets to the source base station and the target base station, and headers of the backup data packets sent by the UE to the source base station and the target base station respectively include HRP SNs.

The protocol stack for one variation of fig. 5 is shown in fig. 6. For any embodiment of the present invention, in another implementation manner, a corresponding user plane protocol stack architecture may also be as shown in fig. 6. Specifically, the protocol stack corresponding to the core network device, such as the UPF device, includes a PHY layer, a layer 2 (e.g., the layer 2 includes a MAC layer, a RLC layer, a PDCP layer, and a SDAP layer), a UDP/IP layer, a GTP-U layer, an HRP layer, and a PDU layer; the access network device, such as a source base station or a target base station, has a corresponding protocol stack including a PHY layer, a layer 2 (e.g., the layer 2 includes a MAC layer, a RLC layer, a PDCP layer, and an SDAP layer), a UDP/IP layer, a GTP-U layer, and an HRP layer; the protocol stack corresponding to the user equipment, for example, UE, includes a PHY layer, a layer 2 (for example, the layer 2 includes a MAC layer, an RLC layer, a PDCP layer, and an SDAP layer), an HRP layer, a PDU layer, and an application layer. That is, unlike the protocol stack structure shown in fig. 5, under the protocol stack architecture shown in fig. 6, a new layer (e.g., HRP layer) is introduced above the GTP-U layer of the base station, and the HRP layer can generate/process numbers of QoS flow granularity (or DRB granularity), for example, the HRP layer of the base station can generate/process HRP SNs.

As shown in fig. 6, for downlink transmission, the UPF device needs to generate a sequence number with QoS flow granularity (or DRB granularity) for the backup data packets sent to the source base station and the target base station, and this function may be implemented by an HRP layer and/or a GTP-U layer, for example, a GTP-U header of the backup data packet sent by the UPF device to the source base station and the target base station includes a GTP-U SN, and/or an HRP header of the backup data packet sent by the UPF device to the source base station and the target base station includes an HRP SN; for uplink transmission, the UPF device processes sequence numbers of QoS flow granularity (or DRB granularity) for backup data packets respectively received from the source base station and the target base station, for example, an HRP layer of the UPF device processes HRP SNs, and the HRP layer may perform operations such as repeated packet detection, reordering, and sequential submission according to the HRP SNs; or, for uplink transmission, the GTP-U layer of the UPF device processes the GTP-USN, and the GTP-U layer of the UPF device may perform operations such as duplicate packet detection, reordering, and sequential delivery according to the GTP-U SN.

As shown in fig. 6, for downlink transmission, the source base station or the target base station needs to process a sequence number of QoS flow granularity (or DRB granularity) for a backup data packet received from the core network device; for uplink transmission, the source base station or the target base station generates a sequence number of QoS flow granularity (or DRB granularity) for a backup data packet received from the UE. Specifically, for downlink transmission, a source base station or a target base station receives a backup data packet sent by a UPF device, in one implementation, a PDCP layer of the source base station determines a PDCPSN corresponding to the received backup data packet according to an HRP SN included in a header of the backup data packet, and the source base station may determine a mapping relationship between the HRP SN and the PDCP SN, or in another implementation, the PDCP layer of the source base station determines a PDCPSN corresponding to the received backup data packet according to a GTP-U SN included in the header of the backup data packet, and the source base station may determine a mapping relationship between the GTP-U SN and the PDCP SN; moreover, in one implementation, the PDCP layer of the target base station may determine the PDCP SN corresponding to the received backup data packet according to the HRP SN included in the header of the backup data packet and the mapping relationship between the HRP SN and the PDCP SN (the target base station may receive the mapping relationship between the HRP SN and the PDCP SN from the source base station), or, in another implementation, the PDCP layer of the target base station may determine the PDCP SN corresponding to the received backup data packet according to the GTP-U SN included in the header of the backup data packet and the mapping relationship between the GTP-U SN and the PDCP SN (the target base station may receive the mapping relationship between the GTP-U SN and the PDCP SN from the source base station); for uplink transmission, a source base station or a target base station receives a backup data packet sent by a UE, in one implementation, the source base station determines an HRP SN corresponding to the received backup data packet according to a PDCP SN included in a header of the backup data packet, and the source base station may determine a mapping relationship between the HRP SN and the PDCP SN, or in another implementation, the source base station determines a GTP-U SN corresponding to the received backup data packet according to the PDCP SN included in the header of the backup data packet, and the source base station may determine a mapping relationship between the GTP-U SN and the PDCP SN; in one implementation, the target base station may determine the HRP SN corresponding to the received backup data packet according to the PDCP SN included in the header of the backup data packet and the mapping relationship between the HRP SN and the PDCP SN (the target base station may receive the mapping relationship between the HRP SN and the PDCP SN from the source base station), or, in another implementation, the target base station may determine the GTP-U SN corresponding to the received backup data packet according to the PDCP SN included in the header of the backup data packet and the mapping relationship between the GTP-U SN and the PDCP SN (the target base station may receive the mapping relationship between the GTP-U SN and the PDCP SN from the source base station).

As shown in fig. 6, for downlink transmission, the UE needs to perform operations such as duplicate packet detection, reordering, and in-order delivery for backup data packets respectively received from the source base station and the target base station, in one implementation, the HRP layer of the UE performs operations such as duplicate packet detection, reordering, and in-order delivery, or in another implementation, the PDCP layer of the UE performs operations such as duplicate packet detection, reordering, and in-order delivery; for uplink transmission, the UE generates backup data packets and sends the backup data packets to the source base station and the target base station, for example, an HRP layer of the UE performs data packet backup and sends the backup data packets to the source base station and the target base station, and headers of the backup data packets sent by the UE to the source base station and the target base station respectively include HRP SNs.

In the embodiment of the present invention, as another implementation scheme, the function of the HRP layer may be implemented by a certain layer of an existing protocol stack, for example, by a GTP-U layer.

The above-mentioned sequence numbers such as "first", "second", "third", and "fourth" are only for the purpose of explaining the technical solution, and are used again in the following, but do not mean that the data packets or information in the following are the same as the data packets or information in the preceding. For example, the foregoing "first packet", "second packet", "third packet", and "fourth packet" are not the same as the following "first packet", "second packet", "third packet", and "fourth packet", and are described in detail with reference to the actual embodiment.

An embodiment of the present invention provides a handover method, as shown in fig. 7, including:

step 701, a core network device sends a first data packet to a target base station, where the first data packet is a first backup data packet sent to the target base station after the core network device starts a backup process.

The core network device may be a UPF device.

Step 702, the core network device sends a second data packet to a source base station, where the second data packet is a copy of the first data packet. The second data packet is a first backup data packet sent to a source base station after the core network equipment starts a backup process.

The first data packet and the second data packet correspond to the same QoS flow. The payload of the first data packet is the same as the payload of the second data packet.

Step 703, the core network device sends first indication information to a source base station, where the first indication information indicates whether the source base station needs to send a serial number state transfer (SN status transfer) message to the target base station.

Optionally, the first indication information may be an end marker, or the first indication information may be included in a header of a first backup packet sent by the UPF to the source base station, or the first indication information may be included in another message.

Step 704, when the first indication information indicates that the source base station does not need to send a sequence number status transfer (SN status transfer) message to the target base station, the source base station does not need to send a sequence number status transfer message to the target base station.

Step 705, when the first indication information indicates that the source base station needs to send a sequence number status transfer (SN status transfer) message to the target base station, the source base station sends a sequence number status transfer message to the target base station.

In this embodiment, step 701 and step 702 have no strict time sequence, and step 703 and step 701, or step 703 and step 702 also have no strict time sequence.

The scheme in the embodiment can reduce the data transmission delay, and the switching scheme is more flexible to realize.

In this embodiment, as another implementation manner, the core network device may not need to send the first indication information to the source base station, and the source base station may default to send the serial number state transition message to the target base station, so that signaling overhead is saved. Or, the core network device may not need to send the first indication information to the source base station, and the source base station may default to send the sequence number state transition message to the target base station.

For two scenarios, that the source base station sends the serial number state transition message to the target base station and the source base station does not need to send the serial number state transition message to the target base station, detailed progress is described below.

Scene one: the source base station needs to send a serial number state transition message to the target base station

After the source base station learns that the UPF device does not send a data packet to the source base station any more, the source base station sends an SNstatus transfer message to the target base station. The UPF device may notify the source base station that the UPF device no longer sends data packets to the source base station through an indication information, for example, the indication information may be an end marker, or the indication information may be included in a header of a first backup data packet sent by the UPF to the source base station, or the indication information may be included in another message, which is not limited.

And before the target base station receives the SN status transfer message, caching the data packet received from the UPF equipment until the target base station receives the SN status transfer message, and sending the cached data packet and/or the data packet received from the UPF equipment to the UE by the target base station.

Scene two: the source base station does not need to send a serial number state transition message to the target base station

After receiving a first data packet from core network equipment, the target base station allocates PDCP SNs to the first data packet to obtain a third data packet, wherein the PDCP SNs of the third data packet take preset values. The third data packet is a first backup data packet sent by the target base station to the UE.

It can also be considered that the target base station performs PDCP sequence number numbering on the first data packet and the backup data packet after the first data packet from a preset value. For example, after the UPF starts the backup process, the backup data packets D0, D1, and D2 … D10 are sequentially sent to the target base station, and the target base station allocates PDCP SNs from D0 to D10 starting from a preset value (e.g., 0), that is, the PDCP SNs allocated to D0 to D10 are sequentially 0,1, and 2 … 10.

The method may further comprise:

the target base station sends the third data packet to the UE, and the payload of the third data packet is the same as that of the first data packet;

and the source base station sends a fourth data packet to the UE, wherein the payload of the fourth data packet is the same as that of the second data packet. The fourth data packet is a first backup data packet sent by the source base station to the UE.

Optionally, the preset value is 0. The PDCP SN of the third packet takes a value of 0. It should be noted that the preset value may also be 1 or another integer value, which is not limited in the embodiment of the present invention, and only the preset value needs to be agreed.

In scenario two, the data radio bearer used by the target base station to send the third data packet to the UE may be the same as or different from the DRB used by the source base station to send the fourth data packet to the UE. Correspondingly, a value of a data radio bearer identity (DRB ID) corresponding to the third data packet may be the same as or different from a value of a DRB ID corresponding to the fourth data packet. The following describes the two implementations separately.

The first implementation scheme is as follows: and the value of the DRB ID corresponding to the third data packet is different from the value of the DRB ID corresponding to the fourth data packet.

For example, the DRB ID used by the source base station to send the fourth data packet takes a value of m, and the DRB ID used by the target base station to send the third data packet takes a value of n, where m is an integer, n is an integer, and m and n are different from each other.

Optionally, the source base station may notify the target base station of the DRB ID used when the third data packet is sent. For example, the handover request message sent by the source base station to the target base station includes a value (e.g., m) of the DRB ID used by the source base station to send the fourth data packet, and also includes a value (e.g., n) of the DRB ID used by the target base station to send the third data packet.

Optionally, the target base station may determine a value of the DRB ID used when the third data packet is sent. For example, the handover request message sent by the source base station to the target base station only includes a value of the DRB ID used by the source base station, and the value of the DRB ID used by the target base station when transmitting data is different from the value of the DRB ID used by the source base station when transmitting data. The target base station may include a value of the DRB ID used when the target base station transmits data in the handover request acknowledgement message sent to the source base station. Optionally, the handover request acknowledgement message may further include a value of a DRB ID used when the source base station transmits data.

The network device may indicate the association relationship between the two DRB IDs to the UE, so that the UE determines the precedence order of the data packets corresponding to the two DRBs. For example, the source base station includes a value (e.g., m) of a DRB ID used by the source base station and a value (e.g., n) of a DRBID used by the target base station in a Radio Resource Control (RRC) message sent to the UE; or the source base station includes the value (e.g. n) of the DRB ID used by the target base station in the RRC message sent to the UE. The RRC message may be an RRC reconfiguration message including a synchronization reconfiguration (reconfiguration within sync) information element, or an RRC connection reconfiguration message including a mobile control information (mobility control info) information element, or other RRC messages.

After the handover is completed, for example, after the UE disconnects from the source base station, or after the UE successfully switches to the target base station, the UE may delete the DRB ID used when the corresponding source base station transmits data, for example, the DRB ID (e.g., m) used when the UE deletes the source base station transmits data, and the DRB ID (e.g., n) used when the UE maintains the target base station transmits data.

After the UE receives the data packets carried on two different data radio bearers from the source base station and the target base station, the UE may have one PDCP entity for each of the two DRBs, where one PDCP entity processes the data packet from the source base station, and the other PDCP entity processes the data packet from the target base station, for example, the PDCP entity performs operations such as duplicate packet detection, reordering, and sequential delivery on the data packets, and optionally, the HRP layer performs operations such as duplicate packet detection, reordering, and sequential delivery. Or, in another implementation, after the UE receives the data packets carried on two different data radio bearers from the source base station and the target base station, the UE processes the data packets from the source base station and the target base station by using one PDCP entity, and then the HRP layer of the UE performs operations such as duplicate packet detection, reordering, and sequential delivery.

The second implementation scheme is as follows: and the value of the DRB ID corresponding to the third data packet is the same as that of the DRB ID corresponding to the fourth data packet.

The DRBs used by the source base station and the target base station respectively when transmitting data are the same, for example, the DRB ID used by the source base station to transmit the fourth data packet takes the value of r, and the DRB ID used by the target base station to transmit the third data packet also takes the value of r, where r is an integer. The PDCP SN allocated to the third data packet by the target base station takes a preset value, for example, the preset value is 0. Or, the preset value is any natural number, and the preset value may be preset, and the embodiment of the present invention does not limit specific data. And starting from the third data packet, when the target base station distributes the PDCP SN values for the third data packet corresponding to the same DRB and the backup data packet behind the third data packet, sequentially increasing from a preset value.

Optionally, the handover request message sent by the source base station to the target base station includes a value of a DRB ID used by the source base station, that is, a value (e.g., r) of a DRB ID used by the source base station to send a fourth data packet, and the target base station also uses a data radio bearer corresponding to the value of the DRB ID when transmitting data, that is, a value of a DRB ID used by the target base station to send a third data packet is also r, and a value of a PDCP SN allocated to the third data packet by the target base station is a preset value, and when performing PDCP SN value allocation for the third data packet and a data packet subsequent to the third data packet, the target base station sequentially increases from the preset value. Optionally, the handover request message may further include an indication information, where the indication information is used to indicate that the DRB used by the target base station is the same as the DRB used by the source base station, that is, the values of the DRB IDs respectively corresponding to the source base station and the target base station when the source base station and the target base station transmit data are the same, and when the target base station performs PDCP SN value allocation for the third data packet and the data packet subsequent to the third data packet, the values are sequentially increased from a preset value. Or, the default DRB used by the target base station is the same as the default DRB used by the source base station, and when the target base station allocates PDCP SN values for the third data packet and the data packets subsequent to the third data packet, the DRBs are sequentially increased from the preset value.

After receiving the data packets from the source base station and the target base station, the UE may have a plurality of processing modes. Three examples are given below, but the present invention is not limited to the following three processing modes. The following only takes the third data packet and the fourth data packet as an example to describe the processing of the data packets, and the processing manner of the backup data packets after the third data packet and the fourth data packet is similar, which is not described in detail below.

Treatment method 1:

and the UE performs repeated packet detection, reordering, sequential submission and other operations on the third data packet and the fourth data packet according to the HRP serial number.

The PDCP layer (which may be one PDCP entity or two PDCP entities) of the UE may process data packets (e.g., RLC SDUs) received from the RLC layer, but the PDCP layer ignores the duplication or disorder problem, and even if the data packets (e.g., PDCP SDUs) of the PDCP layer are duplicated or disordered, the PDCP layer delivers the data packets (e.g., PDCP SDUs) to the HRP layer, and the HRP layer of the UE performs operations such as duplicate packet detection, reordering, and in-sequence delivery according to the HRP SN. Alternatively, the PDCP layer (which may be one PDCP entity or two PDCP entities) of the UE may not perform duplicate packet detection, reordering, and in-sequence delivery on a data packet (e.g., RLC SDU) received from the RLC layer, where the PDCP layer delivers the data packet (e.g., PDCP SDU) to the HRP layer, and the HRP layer of the UE performs duplicate packet detection, reordering, and in-sequence delivery according to the HRP SN.

Treatment method 2:

and in a time period from the time when the UE receives the third data packet or the time when the UE receives the fourth data packet to the time when the UE disconnects the data transmission with the source base station, the PDCP layer (which can be one PDCP entity or two PDCP entities) of the UE ignores the problem of data packet disorder or repetition, and the HRP layer of the UE performs operations of repeated packet detection, reordering, sequential delivery and the like on the received data packets according to the HRP sequence number.

Optionally, before the target base station sends the third data packet to the UE, the target base station sends an indication message to the UE to indicate that the PDCP layer ignores the problem of data packet disorder or duplication in a time period from when the UE receives the third data packet to when data transmission with the source base station is disconnected. Optionally, the indication information may be sent through Downlink Control Information (DCI), a Media Access Control (MAC) Control Element (CE), an RRC message, an end marker, and the like, or the indication information may be included in a header of the third packet.

Or, optionally, before the source base station sends the fourth data packet to the UE, the source base station sends an indication message to the UE, indicating that the PDCP layer ignores the problem of data packet disorder or duplication in a time period from when the UE receives the fourth data packet to when data transmission with the source base station is disconnected. Alternatively, the indication information may be transmitted through DCI, MAC CE, RRC message, endmarker, or the like, or the indication information may be included in a header of the fourth packet.

Treatment method 3:

the PDCP layer of the UE performs repeated packet detection, reordering, sequential submission and other operations, and the HRP layer of the UE also performs repeated packet detection, reordering, sequential submission and other operations.

After the source base station receives indication information for starting the backup process from the UPF device (the indication information may be an end marker, or the indication information may be included in a header of a first backup packet sent by the UPF to the source base station, or the indication information may be included in other messages), the source base station sends second indication information to the UE, where the second indication information indicates a value of a PDCP sequence number of a first backup packet (i.e., a fourth packet) sent by the source base station to the UE. The second indication information may be included in an RRC message, where the RRC message may be a newly defined message or reuse an existing message, such as an RRC reconfiguration message, which is not limited in this embodiment. Optionally, the second indication message may also indicate a value of a PDCP SN of a last non-backup data packet before a fourth data packet sent by the source base station to the UE.

Optionally, the preset value may be preset or the source base station sends an RRC message to the UE, where the RRC message includes the preset value, and the RRC message may be an RRC reconfiguration message including a reconfiguration result sync element, an RRC connection reconfiguration message including a MobilityControlInfo element, or another RRC message, which is not limited herein. The preset value can be any natural number.

The UE determines a mapping relation between the PDCP SN of the data packet from the target base station and the PDCP SN of the data packet from the source base station according to the value of the PDCP sequence number of the fourth data packet and the preset value, and performs at least one of the following operations on the data packets from the source base station and the target base station respectively: and detecting repeated packets, reordering, and submitting in sequence.

For example, the PDCP SN of the third packet is 0 (the preset value is 0), and the second indication information indicates that the PDCP SN of the first backup packet (i.e., the fourth packet) sent by the source base station to the UE is 11 (or indicates that the PDCP SN of the last non-backup packet before the first backup packet sent by the source base station to the UE is 10). After the UE receives the third data packet and the fourth data packet, because the third data packet is a copy of the fourth data packet, and the value of the PDCP SN of the fourth data packet — the value of the PDCP SN of the third data packet is 11, if the value of the PDCP SN of the data packet Dm received by the UE from the source base station is 11 greater than the value of the PDCP SN of the data packet Dn received from the target base station, the UE may determine that Dm is a copy of Dn, that is, the payload of Dm is the same as the payload of Dn, and when the PDCP layer of the UE receives Dm and Dn and performs duplicate packet detection, one of Dm and Dn may be discarded, and the PDCP layer only hands one of Dm and Dn to the upper protocol stack. Optionally, Dm is any data packet received by the UE from the source base station, and Dn is any data packet received by the UE from the target base station. For example, the UE may receive data packets with PDCP SNs of 11, 12, and 13 from the source base station, and receive data packets with PDCP SNs of 0,1, and 2 from the target base station, and then the UE may determine that the data packet with PDCP SN of 11 received from the source base station and the data packet with PDCP SN of 0 received from the target base station are copies of each other, and may discard one of them; the data packet with the PDCP SN value of 12 received from the source base station and the data packet with the PDCP SN value of 1 received from the target base station are copies, and one of the data packets can be discarded; the data packet with the PDCP SN value of 13 received from the source base station and the data packet with the PDCP SN value of 2 received from the target base station are copies of each other, and one of the data packets can be discarded; and so on.

In this embodiment, the processing of the data packet is described by taking HRP SN as an example, and the HRP SN may also be SN of other QoS flow granularities (or DRB granularities), and may be in other naming manners.

An embodiment of the present invention further provides a HRP layer function starting scheme, as shown in fig. 8, including:

step 801, the source base station sends third indication information to the UE.

And step 802, the UE responds to the third indication information and starts the function of the HRP layer.

In the embodiment, the UE can normally perform operations such as repeated packet detection or reordering, and the like, thereby ensuring the data transmission efficiency.

Optionally, in the embodiment of the present invention, the UE starts the HRP layer function, and may be described in two scenarios below before the duplicate process is started, or when the duplicate process is started.

Scene one:

the UE starts the HRP layer function before the duplicate procedure is started, or the UE starts the HRP layer function before the handover procedure is triggered. Alternatively, the handover process trigger may refer to the source base station sending a handover request message to the target base station. For example, before the source base station sends the handover request message to the target base station, the UE starts the HRP layer function.

Optionally, the source base station sends third indication information to the UE, and indicates the UE to start an HRP layer function. Optionally, the third indication information may be carried by an RRC message, where the RRC message may be an RRC setup (RRC setup) message, an RRC reestablishment (RRC reestablishment) message, an RRC resume (RRC resume) message, or a message dedicated to indicating to start the HRP layer function, which is not limited in this embodiment.

Optionally, the HRP layer function is started by the UPF before the duplicate process is started, or the HRP layer function is started by the UPF before the handover process is triggered. Before the source base station sends a switching request message to the target base station, the UPF starts the function of an HRP layer. Optionally, the session establishment response (session establishment response) message sent by the UPF to the SMF includes indication information, where the indication information indicates that the UPF has started the HRP layer function.

As described above, the UE and the UPF may respectively start the HRP layer function in the bearer establishment process. In this scenario, before the handover process is triggered, when data transmission is performed between the UE, the source base station (i.e., serving base station), and the UPF device, the HRP layer function of the UE and/or the UPF is already started. After the switching process is triggered, for uplink data, the HRP layer of the UPF carries out operations such as repeated packet detection, reordering or sequential submission; for downlink data, the HRP layer of the UE performs operations such as duplicate packet detection, reordering, or sequential delivery.

Scene two:

the UE starts the HRP layer function in the starting process of the duplicate process, or the UE starts the HRP layer function when the switching process is triggered. For example, after the source base station sends a handover request message to the target base station, the UE starts the HRP layer function.

Optionally, when the UPF device is ready to send the first backup data packet, the UPF device sends an indication information to the source base station, where the indication information may be an end marker, and notifies the source base station that the UPF device starts a replication process; after receiving the indication information sent by the UPF device, the source base station sends the third indication information to the UE, optionally, the third indication information may be sent through DCI or MAC CE, or the third indication information may be included in a header of a first backup data packet sent by the source base station to the UE, which is not limited to this.

Optionally, when the UPF device prepares to send the first backup data packet, the first duplicate data packet sent by the UPF device to the source base station carries an indication information, for example, a header of the first backup data packet sent by the UPF device to the source base station contains the indication information, and the indication information informs the source base station that the UPF device starts a duplicate process; after receiving the indication information sent by the UPF device, the source base station sends the third indication information to the UE, optionally, the third indication information may be sent through DCI or MAC CE, or the third indication information may be included in a header of a first backup data packet sent by the source base station to the UE, which is not limited to this.

Optionally, when the duplicate process is started, the UPF starts the HRP layer function, or when the handover process is triggered, the UPF starts the HRP layer function. For example, after the source base station sends the handover request message to the target base station, the target base station sends a duplicate request message to the AMF, after the AMF receives the duplicate request message, the AMF sends a session update request message to the SMF, and after the SMF receives the session update request message, the SMF sends a session modification request message to the UPF. And after receiving the session modification request message, the UPF starts the function of the HRP layer.

In this scenario, during the handover process, the HRP layer function of the UE and/or the UPF is started. After the functions of the HRP layer of the UE and/or the UPF are started, for uplink data, the HRP layer of the UPF carries out operations such as repeated packet detection, reordering or sequential submission; for downlink data, the HRP layer of the UE performs operations such as duplicate packet detection, reordering, or sequential delivery.

Optionally, in the embodiment of the present invention, the UE may also report capability information, where the capability information indicates whether the UE supports the HRP layer function.

Optionally, the UE reports the capability information to the source base station. Optionally, the core network device (e.g., an SMF device or an UPF device) may notify the source base station that the core network device performs a duplication process on which QoS flows or PDU sessions in the process of establishing a PDU session (PDU session) with the source base station, for example, the core network device backups data packets corresponding to which QoS flows or PDUs and may notify the source base station of a QoS flow ID and/or PDU session ID in the duplication process. The core network device backs up the data packets and then sends the data packets to two RAN nodes (e.g., a source base station and a target base station). The duplicate process is based on an HRP protocol layer, that is, for uplink data, the HRP protocol layer of the UPF performs operations such as duplicate packet detection, reordering or sequential delivery; for downlink data, the HRP protocol layer of the UE performs operations such as duplicate packet detection, reordering, or sequential delivery.

Optionally, after the handover process is triggered, a duplicate request message sent by the source base station or the target base station to the AMF device carries the capability information, the AMF device notifies the SMF device of the capability information, and the SMF device notifies the UPF device of the capability information. Optionally, the capability information may also be exchanged through NAS signaling, for example, the capability information is exchanged between a NAS layer of the UE and a NAS layer of the SMF device.

Alternatively, the capability information may be indicated in different manners, for example, the capability information is represented by a binary value, for example, "1" indicates that the HRP layer function is supported, and "0" indicates that the HRP layer function is not supported; alternatively, the capability information is expressed by boolean values, e.g., "TRUE" indicates support of HRP layer functionality and "FALSE" indicates no support of HRP layer functionality. The specific manner is not limited.

As another implementation manner, after acquiring the capability information of the UE, when it is determined that both the UE and the UPF device support the HRP layer function, the UPF starts the HRP layer function at a proper time, and notifies the UE to start the HRP layer function at a proper time. When the UPF device determines that the UE does not support the HPR layer function, the UPF does not inform the UE to start the HRP layer function.

The schemes of the foregoing embodiments may be applied to a single communication system, or may be applied to a single communication system by combining two schemes or a plurality of schemes.

Corresponding to the communication method provided by the above method embodiment, the present application embodiment also provides a corresponding communication device (sometimes also referred to as a communication device), where the communication device includes a corresponding module or unit for executing each part in the above embodiments. The module or unit may be software, hardware, or a combination of software and hardware.

Fig. 9 shows a schematic structure of a base station, which can be applied to the system shown in fig. 1. The base station may act as a source base station for the UE and/or as a target base station for the UE. The base station includes one or more Remote Radio Units (RRUs) 701 and one or more baseband units (BBUs) 702. RRU701 may be referred to as a transceiver unit, transceiver circuitry, or transceiver, etc., which may include at least one antenna 7011 and a radio frequency unit 7012. The RRU701 is mainly used for transceiving radio frequency signals and converting the radio frequency signals and baseband signals, for example, for sending signaling indication or reference signals in the above embodiments to a terminal. The BBU702 is mainly used for performing baseband processing, controlling a base station, and the like. RRU701 and BBU702 may be physically located together or physically separated, i.e., distributed base stations.

The BBU702 is a control center of the base station, and may also be referred to as a processing unit, and is mainly used for performing baseband processing functions, such as channel coding, multiplexing, modulation, spreading, and the like. In an example, the BBU702 may be formed by one or more boards, and the boards may support a radio access network of a single access system (e.g., a 5G network) together, or may support radio access networks of different access systems respectively. BBU702 also includes a memory 7021 and a processor 7022. The memory 7021 is used to store the necessary instructions and data. A processor 7022 is used to control the base stations to perform the necessary actions. Memory 7021 and processor 7022 may serve one or more boards. That is, the memory and processor may be provided separately on each board. Or multiple boards may share the same memory and processor. In addition, each single board is provided with necessary circuits.

The base station may be configured to implement the method of the foregoing method embodiment, for example, may implement the functions of the source base station or the target base station in the foregoing method embodiment.

In one possible design, the base station may include one or more processors, which may also be referred to as processing units, and may implement certain control functions. The processor may be a general purpose processor, a special purpose processor, or the like. For example, a baseband processor or a central processor. The baseband processor may be configured to process communication protocols and communication data, and the central processor may be configured to control a communication device (e.g., a base station, a baseband chip, a Distributed Unit (DU) or a Centralized Unit (CU)), execute a software program, and process data of the software program. In one implementation, the processor stores instructions executable by the processor to cause the base station to perform the method described in the above method embodiment. In another implementation, the base station includes one or more memories having instructions or code stored thereon, which are executable on the processor to cause the base station to perform the methods described in the above method embodiments. Optionally, the memory may further store data therein. Optionally, instructions and/or data may also be stored in the processor. The processor and the memory may be provided separately or may be integrated together.

In another possible embodiment, the base station includes a circuit, which may implement the functions of transmitting or receiving or communicating in the foregoing method embodiments.

Corresponding to the scheme shown in fig. 7, an embodiment of the present invention provides a communication system, including:

the target base station is used for receiving a first data packet from core network equipment, wherein the first data packet is a first backup data packet sent by the core network equipment after a backup process is started;

a source base station, configured to receive a second data packet from the core device, where the second data packet is a copy of the first data packet;

the source base station is further configured to receive first indication information from the core network device, where the first indication information indicates whether the source base station needs to send a sequence number state transition message to the target base station;

and the target base station is further configured to allocate PDCP SNs to the first data packet to obtain a third data packet when the first indication information indicates that the source base station does not need to send a sequence number state transfer message to the target base station, where the PDCP SN of the third data packet is a preset value.

Optionally, the target base station is further configured to send the third data packet to a user equipment UE; the source base station is further configured to send a fourth data packet to the UE, where a payload of the fourth data packet is the same as a payload of the second data packet.

Optionally, a value of the data radio bearer identifier corresponding to the third data packet is different from a value of the data radio bearer identifier corresponding to the fourth data packet.

Optionally, the source base station is further configured to send, to the UE, a value of a data radio bearer identifier corresponding to the third data packet and a value of a data radio bearer identifier corresponding to the fourth data packet.

Optionally, a value of the data radio bearer identifier corresponding to the third data packet is the same as a value of the data radio bearer identifier corresponding to the fourth data packet.

Optionally, the source base station is further configured to send second indication information to the UE, where the second indication information indicates a value of a PDCP sequence number of the fourth data packet.

Corresponding to the scheme shown in fig. 8, an embodiment of the present invention provides a base station, where the base station may be configured to implement the function of the source base station in the foregoing description, and as shown in fig. 10, the base station includes:

a processing unit 1001 for generating third indication information;

a sending unit 1002, configured to send third indication information to a user equipment UE, where the third indication information indicates that the UE starts an HRP layer function.

Optionally, after the sending unit sends the third indication information, the sending unit is further configured to send a handover request message to a target base station.

Optionally, before the sending unit sends the third indication information, the sending unit is further configured to send a handover request message to a target base station.

Optionally, the base station further includes:

a receiving unit 1003, configured to receive capability information from the UE, where the capability information indicates whether the UE supports an HRP layer function.

Fig. 11 provides a schematic structural diagram of a terminal. The terminal may be adapted for use in the system shown in fig. 1. For convenience of explanation, fig. 11 shows only main components of the terminal. As shown in fig. 11, the terminal 10 includes a processor, a memory, a control circuit or an antenna, and an input-output device. The processor is mainly used for processing communication protocols and communication data, controlling the whole terminal, executing software programs and processing data of the software programs. The memory is mainly used for storing software programs and data, for example, the codebook described in the above embodiments. The control circuit is mainly used for converting baseband signals and radio frequency signals and processing the radio frequency signals. The control circuit and the antenna together, which may also be called a transceiver, are mainly used for transceiving radio frequency signals in the form of electromagnetic waves. The input and output device, such as a touch screen, a display screen or a keyboard, is mainly used for receiving data input by a user and outputting data to the user.

When the terminal is started, the processor can read the software program in the storage unit, interpret and execute the instruction of the software program, and process the data of the software program. When data needs to be sent wirelessly, the processor outputs a baseband signal to the radio frequency circuit after performing baseband processing on the data to be sent, and the radio frequency circuit performs radio frequency processing on the baseband signal and sends the radio frequency signal outwards in the form of electromagnetic waves through the antenna. When data is sent to the terminal, the radio frequency circuit receives radio frequency signals through the antenna, converts the radio frequency signals into baseband signals and outputs the baseband signals to the processor, and the processor converts the baseband signals into the data and processes the data.

Those skilled in the art will appreciate that fig. 11 shows only one memory and processor for ease of illustration. In an actual terminal, there may be multiple processors and memories. The memory may also be referred to as a storage medium or a storage device, and the like, which is not limited in this respect in the embodiment of the present invention.

As an alternative implementation manner, the processor may include a baseband processor and a central processing unit, where the baseband processor is mainly used to process a communication protocol and communication data, and the central processing unit is mainly used to control the whole terminal, execute a software program, and process data of the software program. The processor in fig. 11 integrates the functions of the baseband processor and the central processing unit, and those skilled in the art will understand that the baseband processor and the central processing unit may also be independent processors, and are interconnected through a bus or the like. Those skilled in the art will appreciate that the terminal may include a plurality of baseband processors to accommodate different network formats, a plurality of central processors to enhance its processing capability, and various components of the terminal may be connected by various buses. The baseband processor may also be expressed as a baseband processing circuit or a baseband processing chip. The central processing unit may also be expressed as a central processing circuit or a central processing chip. The function of processing the communication protocol and the communication data may be built in the processor, or may be stored in the storage unit in the form of a software program, and the processor executes the software program to realize the baseband processing function.

For example, in the embodiment of the present invention, the antenna and the control circuit having the transceiving function may be regarded as a transceiving unit of the terminal 10, and the processor having the processing function may be regarded as a processing unit of the terminal 10. Optionally, a device for implementing the receiving function in the transceiving unit may be regarded as a receiving unit, and a device for implementing the sending function in the transceiving unit may be regarded as a sending unit, that is, the transceiving unit includes a receiving unit and a sending unit, the receiving unit may also be referred to as a receiver, a receiving circuit, or the like, and the sending unit may be referred to as a transmitter, a sending circuit, or the like.

The user equipment described above may be used to implement the method in the foregoing embodiments.

Although in the above description of the embodiments, the communication apparatus is described taking a base station or a terminal device as an example, the scope of the communication apparatus described in the present application is not limited thereto, and the structure of the communication apparatus may not be limited. The communication means may be a stand-alone device or may be part of a larger device. For example, the device may be: a stand-alone integrated circuit IC, or chip, or system-on-chip or subsystem; a set of one or more ICs; an application specific integrated circuit ASIC, such as a modem (modem); modules that may be embedded within other devices, and the like.

Corresponding to the scheme shown in fig. 7, an embodiment of the present invention provides a user equipment UE, as shown in fig. 12, including:

a receiving unit 1201, configured to receive a third data packet from a target base station, where the third data packet is the same as a payload of a first backup data packet sent after a core network device starts a backup process, and a value of a PDCP sequence number of the third data packet is a preset value;

the receiving unit 1201 is further configured to receive a fourth data packet from the source base station;

a processing unit 1202, configured to obtain the third data packet and the fourth data packet.

Optionally, the payload of the fourth data packet is the same as the payload of the third data packet.

Optionally, the receiving unit is further configured to receive a value of a data radio bearer identifier corresponding to the third data packet and a value of a data radio bearer identifier corresponding to the fourth data packet from the source base station.

Optionally, the processing unit is further configured to perform, according to an HRP sequence number, at least one of the following operations on the third data packet and the fourth data packet: and detecting repeated packets, reordering, and submitting in sequence.

Optionally, the processing unit is further configured to, within a time period from when the UE receives the third data packet to when the UE disconnects data transmission with the source base station, ignore packet misordering or duplication of the PDCP layer, and perform at least one of the following operations on the received data packet according to an HRP sequence number: and detecting repeated packets, reordering, and submitting in sequence.

Optionally, the receiving unit is further configured to receive second indication information from the source base station, where the second indication information indicates a value of a PDCP sequence number of the fourth data packet.

Optionally, the processing unit is further configured to determine, according to the value of the PDCP sequence number of the fourth data packet and the preset value, that the third data packet is a duplicate of the fourth data packet, and perform at least one of the following operations on the third data packet and the fourth data packet: and detecting repeated packets, reordering, and submitting in sequence.

Corresponding to the scheme shown in fig. 8, an embodiment of the present invention provides a user equipment UE, as shown in fig. 13, including:

a receiving unit 1301, configured to receive third indication information from a source base station, where the third indication information indicates that the UE starts an HRP layer function;

a processing unit 1302, configured to start an HRP layer function in response to the third indication information.

Optionally, the user equipment further includes:

a sending unit 1303, configured to send capability information of the UE to the source base station, where the capability information indicates whether the UE supports an HRP layer function.

Corresponding to the scheme shown in fig. 7, an embodiment of the present invention provides a core network device, as shown in fig. 14, including:

a processing unit 1401 for starting a backup process;

a sending unit 1402, configured to send a first data packet to a target base station, where the first data packet is a first backup data packet sent by the core network device after starting a backup process;

the sending unit is further configured to send a second data packet to a source base station, where the second data packet is a copy of the first data packet;

the sending unit is further configured to send first indication information to the source base station, where the first indication information indicates whether the source base station needs to send a serial number state transition message to the target base station.

The core network device provided by the embodiment of the invention can be composed of a plurality of devices. The core network device may include a memory, a processor, transceiver circuitry, and the like.

It should be noted that the numbers "first", "second", "third", and the like in the embodiments of the present invention are merely for distinguishing a plurality of terms having the same name in one embodiment, and do not indicate the order or the order of the device processes. Different embodiments having different numbers of nouns may have the same meaning; different embodiments having the same numbered nouns may have different meanings. The specific meaning is determined according to the specific scheme.

Reference in the present application to an element using the singular is intended to mean "one or more" rather than "one and only one" unless specifically stated otherwise. "some" means one or more. "at least one" means one or more, "a plurality" means two or more. "and/or" describes the association relationship of the associated objects, meaning that there may be three relationships, e.g., a and/or B, which may mean: a exists alone, A and B exist simultaneously, and B exists alone, wherein A and B can be singular or plural. The character "/" generally indicates that the former and latter associated objects are in an "or" relationship. "at least one of the following" or similar expressions refer to any combination of these items, including any combination of the singular or plural items. For example, at least one (one) of a, b, or c, may represent: a, b, c, a-b, a-c, b-c, or a-b-c, wherein a, b, c may be single or multiple.

In the above embodiments, the implementation may be wholly or partially realized by software, hardware, firmware, or any combination thereof. When implemented in software, may be implemented in whole or in part in the form of a computer program product. The computer program product includes one or more computer instructions. When loaded and executed on a computer, cause the processes or functions described in accordance with the embodiments of the invention to occur, in whole or in part. The computer may be a general purpose computer, a special purpose computer, a network of computers, or other programmable device. The computer instructions may be stored in a computer readable storage medium or transmitted from one computer readable storage medium to another, for example, from one website site, computer, server, or data center to another website site, computer, server, or data center via wired (e.g., coaxial cable, fiber optic, Digital Subscriber Line (DSL)) or wireless (e.g., infrared, wireless, microwave, etc.). The computer-readable storage medium can be any available medium that can be accessed by a computer or a data storage device, such as a server, a data center, etc., that incorporates one or more of the available media. The usable medium may be a magnetic medium (e.g., floppy Disk, hard Disk, magnetic tape), an optical medium (e.g., DVD), or a semiconductor medium (e.g., Solid State Disk (SSD)), among others.

Claims

1. A method of handover, comprising:

a target base station receives a first data packet from core network equipment, wherein the first data packet is a first backup data packet sent by the core network equipment after a backup process is started;

a source base station receives a second data packet from the core device, wherein the second data packet is a copy of the first data packet;

the source base station receives first indication information from the core network equipment, wherein the first indication information indicates whether the source base station needs to send a serial number state transfer message to the target base station;

when the first indication information indicates that the source base station does not need to send a sequence number state transfer message to the target base station, the target base station allocates a packet data convergence protocol sequence number (PDCP SN) to the first data packet to obtain a third data packet, wherein the PDCP SN of the third data packet is a preset value.

2. The method of claim 1, further comprising:

the target base station sends the third data packet to User Equipment (UE);

and the source base station sends a fourth data packet to the UE, wherein the payload of the fourth data packet is the same as that of the second data packet.

3. The method according to claim 1 or 2, wherein the preset value is 0.

4. The method according to any one of claims 1 to 3, wherein a value of the data radio bearer identity corresponding to the third data packet is different from a value of the data radio bearer identity corresponding to the fourth data packet.

5. The method of claim 4, further comprising:

and the source base station sends the value of the data radio bearer identification corresponding to the third data packet and the value of the data radio bearer identification corresponding to the fourth data packet to the UE.

6. The method according to any one of claims 1 to 3, wherein a value of the data radio bearer identity corresponding to the third data packet is the same as a value of the data radio bearer identity corresponding to the fourth data packet.

7. The method of claim 6, further comprising:

and the source base station sends second indication information to the UE, wherein the second indication information indicates the value of the PDCP serial number of the fourth data packet.

8. A method of handover, comprising:

the method comprises the steps that core network equipment sends a first data packet to a target base station, wherein the first data packet is a first backup data packet sent by the core network equipment after a backup process is started;

the core equipment sends a second data packet to a source base station, wherein the second data packet is a copy of the first data packet;

the core network equipment sends first indication information to the source base station, and the first indication information indicates whether the source base station needs to send a serial number state transition message to the target base station.

9. A method of handover, comprising:

the method comprises the steps that User Equipment (UE) receives a third data packet from a target base station, the third data packet is the same as the payload of a first backup data packet sent by core network equipment after a backup process is started, and the value of a Packet Data Convergence Protocol (PDCP) sequence number (PDCP SN) of the third data packet is a preset value;

the UE receives a fourth data packet from the source base station.

10. The method of claim 9, wherein the payload of the fourth data packet is the same as the payload of the third data packet.

11. The method according to claim 9 or 10, wherein the preset value is 0.

12. The method according to any one of claims 9 to 11,

and the value of the data radio bearer identification corresponding to the third data packet is different from the value of the data radio bearer identification corresponding to the fourth data packet.

13. The method of claim 12, further comprising:

and the UE receives a value of a data radio bearer identification corresponding to the third data packet and a value of a data radio bearer identification corresponding to the fourth data packet from the source base station.

14. The method according to any one of claims 9 to 11,

and the value of the data radio bearer identification corresponding to the third data packet is the same as the value of the data radio bearer identification corresponding to the fourth data packet.

15. The method of claim 14, further comprising:

the UE performs at least one of the following operations on the third data packet and the fourth data packet according to a High Reliability Protocol (HRP) sequence number: and detecting repeated packets, reordering, and submitting in sequence.

16. The method of claim 14, further comprising:

in a time period from when the UE receives the third data packet to when the UE disconnects data transmission with the source base station, the UE ignores data packet disorder or duplication of the PDCP layer, and performs at least one of the following operations on the received data packet according to an HRP sequence number: and detecting repeated packets, reordering, and submitting in sequence.

17. The method of claim 14, further comprising:

the UE receives second indication information from the source base station, wherein the second indication information indicates the value of the PDCP sequence number of the fourth data packet.

18. The method of claim 17, further comprising:

the UE determines that the third data packet is a copy of the fourth data packet according to the value of the PDCP sequence number of the fourth data packet and the preset value, and performs at least one of the following operations on the third data packet and the fourth data packet: and detecting repeated packets, reordering, and submitting in sequence.

19. A communication system, comprising:

the target base station is further configured to allocate a packet data convergence protocol sequence number PDCP SN to the first data packet to obtain a third data packet when the first indication information indicates that the source base station does not need to send a sequence number state transfer message to the target base station, where the PDCP SN of the third data packet is a preset value.

20. The communication system of claim 19, wherein:

the target base station is further configured to send the third data packet to a user equipment UE;

the source base station is further configured to send a fourth data packet to the UE, where a payload of the fourth data packet is the same as a payload of the second data packet.

21. The communication system according to claim 19 or 20, wherein the predetermined value is 0.

22. The communication system according to any of claims 19-21, wherein a value of the data radio bearer identity corresponding to the third data packet is different from a value of the data radio bearer identity corresponding to the fourth data packet.

23. The communication system of claim 22, wherein:

the source base station is further configured to send, to the UE, a value of a data radio bearer identifier corresponding to the third data packet and a value of a data radio bearer identifier corresponding to the fourth data packet.

24. The communication system according to any of claims 19 to 21, wherein a value of the data radio bearer identity corresponding to the third data packet is the same as a value of the data radio bearer identity corresponding to the fourth data packet.

25. The communication system of claim 24, wherein:

the source base station is further configured to send second indication information to the UE, where the second indication information indicates a value of a PDCP sequence number of the fourth packet.

26. A core network device, comprising:

a processing unit for starting a backup process;

a sending unit, configured to send a first data packet to a target base station, where the first data packet is a first backup data packet sent by the core network device after starting a backup process;

27. A User Equipment (UE), comprising:

a receiving unit, configured to receive a third data packet from a target base station, where the third data packet is the same as a payload of a first backup data packet sent after a core network device starts a backup process, and a value of a packet data convergence protocol sequence number PDCP SN of the third data packet is a preset value;

the receiving unit is further configured to receive a fourth data packet from the source base station;

and the processing unit is used for obtaining the third data packet and the fourth data packet.

28. The UE of claim 27, wherein the payload of the fourth data packet is the same as the payload of the third data packet.

29. The UE of claim 27 or 28, wherein the preset value is 0.

30. The user equipment according to any of claims 27-29,

31. The user equipment of claim 30, wherein:

the receiving unit is further configured to receive a value of a data radio bearer identifier corresponding to the third data packet and a value of a data radio bearer identifier corresponding to the fourth data packet from the source base station.

32. The user equipment according to any of claims 27-29,

33. The user equipment of claim 32, wherein:

the processing unit is further configured to perform at least one of the following operations on the third data packet and the fourth data packet according to a High Reliability Protocol (HRP) sequence number: and detecting repeated packets, reordering, and submitting in sequence.

34. The user equipment of claim 32, wherein:

the processing unit is further configured to, in a time period from when the UE receives the third data packet to when the UE disconnects data transmission with the source base station, ignore packet misordering or duplication of the PDCP layer, and perform at least one of the following operations on the received data packet according to an HRP sequence number: and detecting repeated packets, reordering, and submitting in sequence.

35. The user equipment of claim 32, wherein:

the receiving unit is configured to receive second indication information from the source base station, where the second indication information indicates a value of a PDCP sequence number of the fourth packet.

36. The user equipment of claim 35, wherein:

the processing unit is further configured to determine, according to the value of the PDCP sequence number of the fourth data packet and the preset value, that the third data packet is a duplicate of the fourth data packet, and perform at least one of the following operations on the third data packet and the fourth data packet: and detecting repeated packets, reordering, and submitting in sequence.