CN113873585A

CN113873585A - Method and apparatus for switched data transmission

Info

Publication number: CN113873585A
Application number: CN202010620215.9A
Authority: CN
Inventors: 娄崇; 黄曲芳; 范强; 张宏平
Original assignee: Huawei Technologies Co Ltd
Current assignee: Huawei Technologies Co Ltd
Priority date: 2020-06-30
Filing date: 2020-06-30
Publication date: 2021-12-31
Also published as: WO2022001641A1

Abstract

The embodiment of the application provides a method and a device for switched data transmission. The method comprises the steps that a terminal device receives first indication information from a source network device, the first indication information indicates whether a Packet Data Convergence Protocol (PDCP) copy function of a first Radio Bearer (RB) of the terminal device in the source network device is kept or not when the terminal device is switched from the source network device to a target network device, and the terminal device transmits data of the first RB with the source network device according to the first indication information. By implementing the method, the reliability of data transmission in the switching process can be improved. Meanwhile, the terminal equipment can flexibly determine the data transmission mode of the service with different reliability requirements during switching according to the indication of the source network equipment, so that the flexibility of data transmission is improved.

Description

Method and apparatus for switched data transmission

Technical Field

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

Background

A significant feature of the fifth generation (5th generation,5G) mobile communication system compared with the fourth generation (4th generation, 4G) mobile communication system is the increased support for ultra-reliable low-latency communication (URLLC) services. The types of services of URLLC include many, and typical use cases include industrial control, unmanned driving, telesurgery, smart grid, and the like. For URLLC traffic, a typical requirement is that 32 bytes of data are sent within 1 millisecond (ms) with a reliability of 99.999%. It should be noted that the above performance index is only an example, different URLLC services may have different requirements on reliability, for example, in some extremely harsh industrial control application scenarios, the transmission success probability of URLLC service data needs to reach 99.9999999% within 0.25 ms.

Disclosure of Invention

The application provides a data transmission method and device, which are used for improving the reliability of data transmission.

In a first aspect, the present application provides a method for data transmission, where the method is applied to a terminal device to switch from a source network device to a target network device. The execution subject of the method is the terminal device or a module in the terminal device, and the terminal device is taken as the execution subject for description here. The method comprises the steps that terminal equipment receives first configuration information from source network equipment, wherein the first configuration information is used for configuring a Packet Data Convergence Protocol (PDCP) copy function of a first Radio Bearer (RB) of the terminal equipment in the source network equipment; the terminal equipment receives first indication information from source network equipment, wherein the first indication information indicates whether a PDCP copy function of a first RB at the source network equipment is kept or not when the terminal equipment is switched from the source network equipment to target network equipment; and the terminal equipment transmits the data of the first RB with the source network equipment according to the first indication information. Before the terminal equipment initiates the handover, the terminal equipment performs PDCP copy (also referred to as DC duplicate) transmission based on dual connectivity with the source network equipment and the target network equipment, that is, before the terminal equipment initiates the handover, the terminal equipment uses the RLC entity corresponding to the source network equipment and the RLC entity corresponding to the target network equipment, and performs data transmission with the source network equipment using the DC duplicate function.

By implementing the method described in the first aspect, when the terminal device is handed over from the source network device to the target network device, the terminal device may determine whether to continue to maintain the PDCP copy function of the first RB at the source network device at the time of the handover according to the first indication information of the source network device. For a service with a higher reliability requirement, for example, when the service carried by the first RB is the URLLC service, the source network device may instruct to continue to maintain the PDCP copy function of the first RB in the source network device during handover, so that it may be ensured that the terminal device may transmit the same data packet copied through the PDCP layer through at least two RLC entities and the source network device during handover, thereby implementing 0 ms interruption of the PDCP copy function during handover of the URLLC service, and improving the reliability of the URLLC service during handover. For services with low reliability requirements, for example, when the service carried by the first RB is an eMBB service, the source network device may instruct not to maintain the PDCP copy function of the first RB at the source network device at the time of handover, that is, the PDCP copy function of the first RB at the source network device is released at the time of handover. By implementing the method, the terminal equipment can flexibly determine the data transmission mode of the service with different reliability requirements during switching according to the indication of the source network equipment, thereby improving the flexibility of data transmission.

In a possible implementation manner of the first aspect, the maintaining of the PDCP copy function of the first RB in the source network device specifically includes: and keeping a first Radio Link Control (RLC) entity, wherein the first RLC entity is an RLC entity corresponding to the target network equipment before the handover is initiated. Maintaining the first RLC entity may also be understood as: the first RLC entity is not released or can also be understood as: the first RLC entity is in an available state, and the terminal device can transmit data with the source network device through the first RLC entity.

By implementing the method, the terminal device determines whether to continue to use the first RLC entity corresponding to the target network device before the handover is initiated to transmit the data of the first RB with the source network device according to the first indication information of the source network device. For a service with a higher reliability requirement, for example, when the service carried by the first RB is the URLLC service, the terminal device may continue to use the first RLC entity and the source network device to transmit the data of the first RB during handover, so that it may be ensured that the terminal device may transmit the same data packet copied through the PDCP layer with the source network device through at least two RLC entities (one is the first RLC entity, and the other is the RLC entity corresponding to the source network device), and the reliability of the URLLC service in the handover process is improved.

In a possible implementation manner of the first aspect, when the first indication information indicates to maintain a PDCP copy function of the first RB in the source network device, the transmitting data of the first RB with the source network device according to the first indication information specifically includes: and when the switching is initiated, submitting a data packet encrypted by using the key of the source network equipment to the first RLC entity.

In a possible implementation manner of the first aspect, the terminal device receives second configuration information from the source network device, where the second configuration information is used to configure a PDCP duplication function of the first RB in the target network device, where the PDCP duplication function of the first RB in the target network device may be a carrier aggregation based PDCP duplication (also referred to as CA duplication) function of the first RB in the target network device. And after the switching is completed, the terminal equipment activates the PDCP copy function of the first RB in the target network equipment.

By implementing the method, when the terminal device considers that the handover is completed, the terminal device can immediately activate the PDCP copy function of the first RB in the target network device, so that the terminal device can perform data transmission based on PDCP copy with the source network device before the handover is completed, and after the handover is completed, the terminal device can immediately perform data transmission based on PDCP copy with the target network device, so that the data transmission based on PDCP copy between the terminal device and the network device is not interrupted by the handover, thereby improving the reliability of data transmission.

In a possible implementation manner of the first aspect, the terminal device receives second configuration information from the source network device, where the second configuration information is used to configure a PDCP replication function of the first RB in the target network device; and the terminal equipment receives second indication information from the target network equipment, wherein the second indication information is used for activating a PDCP copy function of the first RB at the target network equipment. The PDCP copy function of the first RB in the target network device may be a capacity function of the first RB in the target network device.

By implementing the method, the terminal device can activate the target network device to perform data transmission based on the PDCP copy according to the second indication information of the target network device, so that the flexibility of data transmission is improved, and meanwhile, the terminal device and the target network device have the same understanding on the activation time through the method of indicating activation by the second indication information, so that the reliability of data transmission is improved.

In a possible implementation manner of the first aspect, the activating a PDCP copy function of the first RB in the target network device specifically includes: and activating the RLC entity associated with the first RB and corresponding to the target network equipment.

In a possible implementation manner of the first aspect, the first indication information further indicates that, after the handover is completed, the first RLC entity is an RLC entity corresponding to the target network device. Specifically, before the handover is completed, the first RLC entity is an RLC entity for performing PDCP duplication transmission between the terminal device and the source network device, and the source network device indicates, by using the first indication information: after the handover is completed, the first RLC entity is an RLC entity for performing PDCP duplication transmission between the terminal device and the target network device.

In a possible implementation manner of the first aspect, the terminal device receives third indication information from the source network device, where the third indication information indicates that, after the handover is completed, the first RLC entity is an RLC entity corresponding to the target network device. Specifically, before the handover is completed, the first RLC entity is an RLC entity for performing PDCP duplication transmission between the terminal device and the source network device, and the source network device indicates, by using the third indication information: after the handover is completed, the first RLC entity is an RLC entity for performing PDCP duplication transmission between the terminal device and the target network device.

In a possible implementation manner of the first aspect, the terminal device submits, to a second RLC entity, the data packet encrypted using the key of the target network device, where the second RLC entity is one of the RLC entities associated with the first RB, and the second RLC entity is an RLC entity corresponding to the target network device after the handover is completed. Wherein the second RLC entity is different from the first RLC entity.

In a possible implementation manner of the first aspect, after the handover is completed, the terminal device submits, to the first RLC entity, a data packet encrypted using a key of the target network device.

By implementing the method, the RLC entity (first RLC entity) corresponding to the target network device before the handover is initiated is converted into the RLC entity corresponding to the target network device after the handover is completed, so that the terminal device can perform data transmission based on CA duplicate with the target network device through the RLC entities (second RLC entities) except the first RLC entity in the RLC entities corresponding to the target network device after the handover is completed and the first RLC entity, and the reliability of data transmission is improved. Meanwhile, in this way, the target network device only needs to configure the second RLC entity, and the terminal device can perform CA duplicate-based data transmission with the target network device after the handover is completed, thereby reducing the overhead of resource configuration.

In a possible implementation manner of the first aspect, after the handover is completed, the terminal device submits, to the first RLC entity, a data packet encrypted using a key of the source network device.

In a possible implementation manner of the first aspect, when receiving a handover command from a source network device, a terminal device indicates initiation of handover; or, when the source network device receives the switching request confirmation message from the target network device, it indicates that the switching is initiated; or, when the source network device sends a handover request command to the target network device, it indicates that handover is initiated.

In a possible implementation manner of the first aspect, after the terminal device initiates a random access process to the target network device, when the terminal device successfully accesses the target network device, the terminal device indicates that the handover is completed; or, when the terminal device sends an RRC reconfiguration message for ending the handover process to the target network device, indicating that the handover is completed; or, the target network device indicates that the handover is completed when receiving the RRC reconfiguration message for ending the handover procedure from the terminal device.

In a second aspect, the present application provides a method for data transmission, which is applied to a terminal device switching from a source network device to a target network device. The execution subject of the method is the source network device or a module in the source network device, and the source network device is taken as the execution subject for description here. The source network equipment sends first configuration information to the terminal equipment, wherein the first configuration information is used for configuring a Packet Data Convergence Protocol (PDCP) copy function of a first Radio Bearer (RB) of the terminal equipment in the source network equipment; the source network equipment sends first indication information to the terminal equipment, wherein the first indication information indicates whether a PDCP copy function of a first RB at the source network equipment is kept or not when the terminal equipment is switched from the source network equipment to the target network equipment; and the source network equipment transmits the data of the first RB with the terminal equipment according to the first indication information.

By implementing the method described in the second aspect, when the terminal device is handed over from the source network device to the target network device, the source network device indicates, through the first indication information, whether the terminal device continues to maintain the PDCP copy function of the first RB at the source network device during the handover. For a service with a higher reliability requirement, such as a URLLC service, the source network device may instruct to continue to maintain the PDCP copy function of the first RB in the source network device during handover, so that it may be ensured that the terminal device may transmit the same data packet copied through the PDCP layer through at least two RLC entities and the source network device, thereby implementing 0 ms interruption of the PDCP copy function of the URLLC service during handover, and improving the reliability of the URLLC service during handover. For services with low reliability requirements, for example, when the service carried by the first RB is an eMBB service, the source network device may instruct not to maintain the PDCP copy function of the first RB at the source network device at the time of handover, that is, the PDCP copy function of the first RB at the source network device is released at the time of handover. By implementing the method, the source network equipment can flexibly indicate the data transmission mode of the service with different reliability requirements during switching, thereby improving the flexibility of data transmission.

In a possible implementation manner of the second aspect, the maintaining of the PDCP copy function of the first RB in the source network device specifically includes: and keeping a first Radio Link Control (RLC) entity, wherein the first RLC entity is an RLC entity corresponding to the target network equipment before the handover is initiated.

In a possible implementation manner of the second aspect, when the first indication information indicates to maintain the PDCP copy function of the first RB in the source network device, the transmitting data of the first RB with the source network device according to the first indication information specifically includes: when the handover is initiated, a data packet encrypted by using the key of the source network equipment is received from the first RLC entity.

In a possible implementation manner of the second aspect, second configuration information is sent to the terminal device, where the second configuration information is used to configure a PDCP replication function of the first RB in the target network device.

In a possible implementation manner of the second aspect, the first indication information further indicates that, after the handover is completed, the first RLC entity is an RLC entity corresponding to the target network device. Specifically, before the handover is completed, the first RLC entity is an RLC entity for performing PDCP duplication transmission between the terminal device and the source network device, and the source network device indicates, by using the first indication information: after the handover is completed, the first RLC entity is an RLC entity for performing PDCP duplication transmission between the terminal device and the target network device.

In a possible implementation manner of the second aspect, the source network device sends third indication information to the terminal device, where the third indication information indicates that, after the handover is completed, the first RLC entity is an RLC entity corresponding to the target network device. Specifically, before the handover is completed, the first RLC entity is an RLC entity for performing PDCP duplication transmission between the terminal device and the source network device, and the source network device indicates, by using the third indication information: after the handover is completed, the first RLC entity is an RLC entity for performing PDCP duplication transmission between the terminal device and the target network device.

In a possible implementation manner of the second aspect, after the handover is completed, the source network device receives a data packet from the first RLC entity, which is encrypted by using a key of the source network device; the source network device forwards the data packet encrypted using the source network device's key to the target network device. Correspondingly, after the switching is completed, the target network device receives the data packet which is forwarded by the source network device and encrypted by using the secret key of the source network. In one possible design, the target network device receives a data packet encrypted by using a key of the target network device from a second RLC entity, where the second RLC entity is one of the RLC entities associated with the first RB, and the second RLC entity is an RLC entity corresponding to the target network device after the handover is completed. Wherein the second RLC entity is different from the first RLC entity.

By implementing the method, after the handover is completed, the terminal device may transmit the same data as the target network device through the first RLC entity and the second RLC entity. Illustratively, the terminal device sends one piece of data to the target network device through the second RLC entity, the terminal device sends another piece of the same data to the source network device through the first RLC entity, and the source network device forwards the data to the target network device when receiving the data from the terminal device through the first RLC entity, so that after the handover is completed, the terminal device can perform data transmission with the target network device through at least two RLC entities (commonly called as two legs), and the reliability of data transmission is improved.

In a possible implementation manner of the second aspect, when the terminal device receives a handover command from the source network device, it indicates that handover is initiated; or, when the source network device receives the switching request confirmation message from the target network device, it indicates that the switching is initiated; or, when the source network device sends a handover request command to the target network device, it indicates that handover is initiated.

In a possible implementation manner of the second aspect, after the terminal device initiates a random access process to the target network device, when the terminal device successfully accesses the target network device, the terminal device indicates that the handover is completed; or, when the terminal device sends an RRC reconfiguration message for ending the handover process to the target network device, indicating that the handover is completed; or, the target network device indicates that the handover is completed when receiving the RRC reconfiguration message for ending the handover procedure from the terminal device.

In a third aspect, a communication device is provided, which includes functional modules for implementing the methods in the foregoing first aspect and any possible implementation manner of the first aspect.

In a fourth aspect, a communication device is provided, which includes functional modules for implementing the methods in the second aspect and any possible implementation manner of the second aspect.

In a fifth aspect, there is provided a communication device comprising a processor and an interface circuit, wherein the interface circuit is configured to receive signals from other communication devices except the communication device and transmit the signals to the processor or send the signals from the processor to other communication devices except the communication device, and the processor is configured to implement the method in any possible implementation manner of the first aspect and the first aspect through logic circuits or executing code instructions.

In a sixth aspect, there is provided a communication device comprising a processor and an interface circuit, the interface circuit being configured to receive signals from other communication devices than the communication device and transmit the signals to the processor or transmit the signals from the processor to other communication devices than the communication device, and the processor being configured to implement the method of the second aspect or any possible implementation manner of the second aspect through logic circuits or executing code instructions.

In a seventh aspect, a computer-readable storage medium is provided, in which a computer program or instructions are stored, and when executed, implement the method in the foregoing first aspect or any possible implementation manner of the first aspect.

In an eighth aspect, a computer-readable storage medium is provided, in which a computer program or instructions are stored, which, when executed, implement the method of the foregoing second aspect, any possible implementation manner of the second aspect.

A ninth aspect provides a computer program product comprising instructions that, when executed, implement the method of the first aspect, any possible implementation manner of the first aspect.

A tenth aspect provides a computer program product comprising instructions that, when executed, implement the method of the second aspect, any possible implementation of the second aspect.

In an eleventh aspect, a computer program is provided, which comprises code or instructions that, when executed, implement the method of the first aspect, any possible implementation manner of the first aspect.

In a twelfth aspect, a computer program is provided, which comprises code or instructions that, when executed, implement the method of the second aspect, any possible implementation of the second aspect.

In a thirteenth aspect, a chip system is provided, where the chip system includes a processor and may further include a memory, and is configured to implement at least one of the methods described in the foregoing first and second aspects. The chip system may be formed by a chip, and may also include a chip and other discrete devices.

In a fourteenth aspect, a communication system is provided, which includes the apparatus (e.g. terminal device) in the third aspect or the fifth aspect, and the apparatus (e.g. source network device) in the fourth aspect or the sixth aspect.

Drawings

Fig. 1 is a schematic architecture diagram of a communication system applied in the embodiment of the present application;

FIG. 2 is a schematic diagram of a CU and DU separation architecture applied in the embodiment of the present application;

fig. 3 is a schematic diagram of an architecture for implementing a PDCP duplicate function in a DC scenario according to an embodiment of the present application;

fig. 4 is a schematic diagram of an architecture for implementing a PDCP duplicate function in a CA scenario according to an embodiment of the present application;

fig. 5 is a schematic diagram of a handover procedure according to an embodiment of the present application;

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

fig. 7 is a schematic diagram illustrating implementation of a PDCP duplicate function according to an embodiment of the present application;

fig. 8 is a schematic structural diagram of a first message according to an embodiment of the present application;

fig. 9 and fig. 10 are schematic diagrams for implementing PDCP duty function according to the embodiment of the present application;

fig. 11 and 12 are schematic structural diagrams of a possible communication device provided in an embodiment of the present application.

Detailed Description

The technical scheme provided by the embodiment of the application can be applied to various communication systems, such as: a Long Term Evolution (LTE) system, a fifth generation (5G) mobile communication system, a WiFi system, a future communication system, or a system in which multiple communication systems are integrated, which is not limited in the embodiment of the present application. Among them, 5G may also be referred to as New Radio (NR).

The technical scheme provided by the embodiment of the application can be applied to various communication scenes, for example, one or more of the following communication scenes: enhanced mobile broadband (eMBB), ultra-reliable low-latency communication (URLLC), Machine Type Communication (MTC), large-scale Machine Type Communication (MTC), device-to-device (D2D), vehicle-to-outside (V2X), vehicle-to-vehicle (V2V), and internet of things (IoT), among others.

The technical scheme provided by the embodiment of the application can be applied to communication among communication devices. The communication between the communication devices may include: communication between a network device and a terminal device, communication between a network device and a network device, and/or communication between a terminal device and a terminal device. In the embodiments of the present application, the term "communication" may also be described as "transmission", "information transmission", or "signal transmission", and the like. The transmission may include sending and/or receiving. In the embodiment of the present application, a technical solution is described by taking communication between a network device and a terminal device as an example, and those skilled in the art may also use the technical solution to perform communication between other scheduling entities and subordinate entities, for example, communication between a macro base station and a micro base station, for example, communication between a first terminal device and a second terminal device. The scheduling entity may allocate an air interface resource to the subordinate entity. The air interface resources include one or more of the following resources: time domain resources, frequency domain resources, code resources, and spatial resources. In the embodiments of the present application, the plurality of types may be two, three, four, or more, and the embodiments of the present application are not limited.

In this embodiment of the present application, the communication between the network device and the terminal device includes: the network device sends downlink signals/information to the terminal device, and/or the terminal device sends uplink signals/information to the network device.

In the embodiments of the present application, "/" may indicate a relationship in which the objects associated before and after are "or", for example, a/B may indicate a or B; "and/or" may be used to describe that there are three relationships for the associated object, 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. In the embodiments of the present application, the terms "first", "second", and the like may be used to distinguish technical features having the same or similar functions. The terms "first", "second", and the like do not necessarily limit the number and execution order, and the terms "first", "second", and the like do not necessarily differ. In the embodiments of the present application, the words "exemplary" or "such as" are used to indicate examples, illustrations or illustrations, and embodiments or designs described as "exemplary" or "such as" are not to be construed as preferred or advantageous over other embodiments or designs. The use of the terms "exemplary" or "such as" are intended to present relevant concepts in a concrete fashion for ease of understanding.

Fig. 1 is an architecture diagram of a communication system to which embodiments of the present application may be applied. As shown in fig. 1, the communication system includes a terminal device 110 and two network devices (e.g., network device 120 and network device 130 in fig. 1). Fig. 1 is a schematic diagram, and the embodiment of the present application does not limit the number of network devices and terminal devices included in the communication system.

The terminal device according to the embodiments of the present application may also be referred to as a terminal, a User Equipment (UE), a mobile station, a mobile terminal, or the like. The terminal device can be a mobile phone, a tablet computer, a computer with a wireless transceiving function, a virtual reality terminal device, an augmented reality terminal device, a wireless terminal in industrial control, a wireless terminal in unmanned driving, a wireless terminal in remote operation, a wireless terminal in a smart grid, a wireless terminal in transportation safety, a wireless terminal in a smart city, a wireless terminal in a smart home and the like. The embodiment of the present application does not limit the specific technology and the specific device form adopted by the terminal device. In the embodiment of the present application, the apparatus for implementing the function of the terminal device may be the terminal device; it may also be a device, such as a chip system, capable of supporting the terminal device to realize the function, and the device may be installed in the terminal device or used in cooperation with the terminal device. In the embodiment of the present application, the chip system may be composed of a chip, and may also include a chip and other discrete devices. In the technical solution provided in the embodiment of the present application, a device for implementing a function of a terminal device is taken as an example of a terminal device, and the technical solution provided in the embodiment of the present application is described.

The network device related to the embodiment of the present application is an access network (RAN) device in which a terminal device accesses to the mobile communication system in a wireless manner, and may include but is not limited to: a base station, an evolved node b (eNodeB), a Transmission Reception Point (TRP), a next generation base station (gNB) in a 5G mobile communication system, a base station in a future mobile communication system or an access node in a WiFi system, and the like. The interface between the network devices is referred to as an Xn interface, and the interface between the network device and the terminal device may be a Uu interface (or referred to as an air interface). Of course, in future communications, the names of these interfaces may be unchanged or replaced by other names, which are not limited in this application.

The communication between the network device and the terminal device follows a certain protocol layer structure, for example, the control plane protocol layer structure may include functions of protocol layers such as an RRC layer, a Packet Data Convergence Protocol (PDCP) layer, a Radio Link Control (RLC) layer, a Media Access Control (MAC) layer, and a physical layer; the user plane protocol layer structure may include functions of protocol layers such as a PDCP layer, an RLC layer, an MAC layer, and a physical layer, and in a possible implementation, the PDCP layer may further include a Service Data Adaptation Protocol (SDAP) layer.

Network devices may include Centralized Units (CUs) and Distributed Units (DUs). The interface between a CU and a DU may be referred to as the F1 interface, as shown in fig. 2. Wherein, the Control Plane (CP) interface may be F1-C, and the User Plane (UP) interface may be F1-U. The CU and the DU may be divided according to protocol layers of the radio network, such as functions of a PDCP layer and above protocol layers are provided in the CU, and functions of protocol layers below the PDCP layer (e.g., an RLC layer, a MAC layer, etc.) are provided in the DU. The signaling generated by the CU may be sent to the terminal device via the DU, or the signaling generated by the terminal device may be sent to the CU via the DU. The DU may directly encapsulate the signaling through a protocol layer without parsing and then transmit the encapsulated signaling to the terminal device or the CU. The embodiments of the present application do not limit the specific technologies and the specific device forms used by the network devices. In the embodiment of the present application, the apparatus for implementing the function of the network device may be a network device; it may also be a device, such as a chip system, capable of supporting the network device to implement the function, and the device may be installed in the network device or used in cooperation with the network device. In this embodiment of the present application, a device for implementing a function of a network device is taken as an example of a network device, and a technical solution provided in this embodiment of the present application is described.

The network equipment and the terminal equipment can be deployed on land, including indoor or outdoor, handheld or vehicle-mounted; can be deployed on the water surface; alternatively, it may be deployed on an airborne airplane, balloon, or artificial satellite. The embodiment of the application does not limit the application scenarios of the network device and the terminal device. The network device and the terminal device may communicate with each other via a licensed spectrum, may communicate via an unlicensed spectrum, or may communicate via both the licensed spectrum and the unlicensed spectrum. The network device and the terminal device may communicate with each other through a frequency spectrum of 6 gigahertz (GHz) or less, through a frequency spectrum of 6GHz or more, or through a frequency spectrum of 6GHz or less and a frequency spectrum of 6GHz or more. The embodiments of the present application do not limit the spectrum resources used between the network device and the terminal device.

Some terms in the embodiments of the present application are explained below to facilitate understanding by those skilled in the art.

Radio Bearer (RB)

Data is transmitted between the terminal equipment and the network equipment by establishing at least one Radio Bearer (RB). The radio bearer may be divided into a Signaling Radio Bearer (SRB) for transmitting signaling data and a Data Radio Bearer (DRB) for transmitting service data, where a set of functional entities of the same radio bearer includes one PDCP entity, at least one radio link control RLC entity corresponding to the PDCP entity, and at least one MAC entity corresponding to the at least one RLC entity. Wherein, the PDCP entity is located at the PDCP layer, the RLC entity is located at the RLC layer, and the MAC entity is located at the MAC layer.

For example, in downlink data transmission, after an SDAP layer entity of a network device obtains data from an upper layer, the data may be mapped to a PDCP layer entity of a corresponding RB according to a quality of service flow identifier (QFI) of the data, and the PDCP layer entity may transmit the data to at least one RLC layer entity corresponding to the PDCP layer entity, and then transmit the data to a corresponding MAC layer entity by the at least one RLC layer entity, generate a transmission block by the MAC layer entity, and perform radio transmission by the corresponding physical layer entity. Data is correspondingly encapsulated in each layer, data received by a layer from an upper layer of the layer is regarded as a Service Data Unit (SDU) of the layer, and the data becomes a Protocol Data Unit (PDU) after layer encapsulation, and is then transmitted to a next layer. For example, data received by the PDCP layer entity from an upper layer is called PDCP SDU, and data transmitted by the PDCP layer entity to a lower layer is called PDCP PDU; data received by the RLC layer entity from the upper layer is called RLC SDU, and data transmitted by the RLC layer entity to the lower layer is called RLC PDU. For example, data may be transmitted between the RLC layer entity and the MAC layer entity through a Logical Channel (LCH), and data may be transmitted between the MAC layer entity and the physical layer entity through a transport channel (transport channel).

(two) Dual Connectivity (DC)

DC means that the terminal device is simultaneously connected to two network devices. The two network devices connected by the terminal device may be base stations in the same radio access technology, for example, both base stations in the LTE communication system or both base stations in the 5G mobile communication system, or the two base stations connected by the terminal device may also be base stations in different radio access technologies, for example, one is a base station in the LTE communication system and the other is a base station in the 5G mobile communication system.

(III) Carrier Aggregation (CA)

CA refers to aggregating a plurality of Component Carriers (CCs) together to provide a service for a terminal device, so as to achieve a larger transmission bandwidth, thereby increasing an uplink and downlink transmission rate.

(IV) PDCP replication (PDCP replication)

PDCP duty means: the data packet of the radio bearer is duplicated into a plurality of identical packets (i.e., duplicated packets) at the PDCP layer, and then the duplicated data packets are respectively delivered to a plurality of different RLC entities for transmission. Illustratively, each RLC entity transmits a data packet to the MAC layer through a logical channel corresponding to the RLC entity. Generally, the PDCP duplication is different from so-called retransmission (retransmission), which means that the same packet is transmitted again after failing to be transmitted, and the PDCP duplication is performed by duplicating one packet into a plurality of packets and transmitting the packets through a plurality of RLC entities.

In the embodiment of the present application, the PDCP duty includes a PDCP duty of a DC scene (which may also be referred to as a DC duty) and a PDCP duty of a CA scene (which may also be referred to as a CA duty). In the following, how the PDCP duty function is implemented is introduced for the DC scenario and the CA scenario, respectively.

(1)DC duplication

Fig. 3 shows a network architecture for implementing the DC duplicate function in a DC scenario. For network devices, the DC scenario involves a primary network device and a secondary network device. For one RB, there are one PDCP entity, one RLC entity, and one MAC entity in the primary network device, and one RLC entity and one MAC entity in the secondary network device. For the RB, one PDCP entity, two RLC entities, and two MAC entities correspond in the terminal device. For one RB, the master network device may further have an SDAP entity on the PDCP entity, and the terminal device may also have an SDAP entity on the PDCP entity.

In a DC scenario, a terminal device connects two network devices, i.e. a primary network device and a secondary network device, and if a DC duplicate function is configured for a certain RB, two identical data packets belonging to the RB copied by the PDCP layer will be transmitted to two different RLC entities and transmitted to two different MAC entities through different logical channels, so that two MAC PDUs are finally formed and transmitted on cell resources respectively scheduled by the two different MAC entities. For the network device, the PDCP layer in the primary network device may transmit the two duplicated data packets to two different RLC entities, where the two RLC entities are located in the primary network device and the secondary network device, respectively, and then the RLC entity in the primary network device transmits the received data packet to the MAC entity in the primary network device, and the RLC entity in the secondary network device transmits the received data packet to the MAC entity in the secondary network device, where the two MAC entities may transmit the data packets through respective cell resources, and for the terminal device, the two RLC entities and the two MAC entities are located in the terminal device. For example, in a DC scenario, there may be two cell groups for serving the terminal device, which are a Master Cell Group (MCG) and a Secondary Cell Group (SCG), respectively, where the master cell group is managed and configured by the master network device and the secondary cell group is managed and configured by the master network device or the secondary network device.

Optionally, the network device may further configure, for the terminal device, one of the two RLC entities as a primary RLC entity (also known as primary leg) and the other as a secondary RLC entity (also known as secondary leg), for example, the network device configures RLC1 in fig. 3 as the primary RLC entity and RLC2 as the secondary RLC entity. In the embodiment of the present application, as the RLC entities and the logical channels are in one-to-one correspondence, the master leg may refer to the master RLC entity, or to the logical channel associated with the master RLC entity, which is also referred to as a master logical channel; the secondary leg may refer to a secondary RLC entity, and may also refer to a logical channel associated with the secondary RLC entity, which is also referred to as a secondary logical channel.

When a network device configures a DC duplicate function for a radio bearer through Radio Resource Control (RRC) signaling, it may indicate whether an initial state of the DC duplicate function of the radio bearer is activated or deactivated. Optionally, the network device may further configure activation/deactivation of the DC duplicate function of the radio bearer through a MAC control element (MAC CE).

When the DC duplication function is activated, the terminal device may receive the same data packet from the main network device through the main RLC entity and the auxiliary RLC entity copied through the PDCP layer of the main network device, or the terminal device may copy the data packet in two at the PDCP layer of the terminal device and transmit the same data packet to the main network device and the auxiliary network device through the main RLC entity and the auxiliary RLC entity, respectively. When the terminal equipment and the network equipment transmit the PDCP control PDU, the terminal equipment can only transmit the PDCP control PDU with the network equipment through the main RLC entity.

When the DC duplicate function is deactivated, the terminal device reverts to a split bearer (split bearer), that is, the terminal device may transmit different data packets respectively with the main network device and the auxiliary network device through the main RLC entity and the auxiliary RLC entity on the terminal device side. Illustratively, when the amount of data to be transmitted by the terminal device and the network device exceeds a threshold value, the terminal device transmits different data packets respectively with the main network device and the auxiliary network device through the main RLC entity and the auxiliary RLC entity; and when the data volume does not exceed the threshold value, the terminal equipment transmits data packets with the main network equipment only through the main RLC entity, wherein the threshold value is configured by the network equipment through RRC messages.

(2)CA duplication

Fig. 4 shows a network architecture for implementing PDCP duty function in a CA scenario. In a CA scenario, a terminal device is connected to a network device, and at least two carriers (or cells) serve the terminal device in the same network device. For one RB, there are one PDCP entity, two RLC entities, and one MAC entity in the network device. The terminal device corresponds to one PDCP entity, two RLC entities and one MAC entity. When the network device configures the PDCP duplicate function for a radio bearer, two identical packets duplicated in the PDCP layer are transmitted to two different RLC entities, and the two RLC entities transmit to the same MAC entity through different logical channels. At this time, since two identical data packets are transmitted to the same MAC entity, and the MAC entity may put the two data packets into one MAC PDU for transmission, in order to enable the two data packets to be transmitted through two cells respectively, a parameter, for example, called as parameter a, may be configured for the logical channel, and different cells are indicated by a value of the parameter a, so as to ensure that the two identical data packets can finally form two MAC PDUs for transmission on different cells, thereby improving reliability.

Currently, the CA duplicate can support a data packet of one radio bearer to be duplicated in the PDCP layer and transmitted through two RLC entities respectively. Optionally, the network device may further configure one of the RLC entities as a primary RLC entity and the other RLC entity as a secondary RLC entity, for example, the network device configures RLC1 in fig. 4 as the primary RLC entity and RLC2 as the secondary RLC entity. When the network device configures the PDCP duplication function for a radio bearer through RRC signaling, the network device may indicate whether the initial state of the PDCP duplication function of the radio bearer is activated or deactivated. Optionally, the network device may further configure activation/deactivation of the PDCP duty function of the radio bearer through the MAC CE. When the CA duplicate function is activated, the terminal device may transmit data with the network device through the main RLC entity and the auxiliary RLC entity; when the CAdupling function is deactivated, the terminal equipment can only transmit data with the network equipment through the main RLC entity.

(V) handover procedure

Before a terminal device switches from one network device to another network device, a network device that provides services for at least one RB of the terminal device may be referred to as a source network device; the network device serving the at least one RB of the terminal device after the handover may be referred to as a target network device. Fig. 5 is a schematic diagram of a handover procedure, which includes:

s501, the source network device sends a RRC reconfiguration message to the terminal device in the RRC connected state, where the RRC reconfiguration message includes parameters such as a measurement object, a measurement configuration, and a measurement identifier.

S502, after the terminal device measures the measurement object according to the RRC reconfiguration message, the terminal device reports the measurement result to the source network device, for example, the terminal device reports that the signal strength of the current serving cell is lower than the threshold and the signal strength of the target cell is higher than the threshold.

S503, the source network device determines whether to switch after receiving the measurement report in S502. If the switching is needed, the source network device sends a switching request (handover request) message to the target network device.

S504, if the target network device allows the terminal device to access, the target network device sends a handover request acknowledge (handover request acknowledge) message to the source network device. The handover request acknowledgement message may include an RRC reconfiguration message generated by the target network device for the terminal device, where the RRC reconfiguration message includes a configuration required by the terminal device to access the target network device.

S505, the source network device sends a handover command to the terminal device, where the handover command includes an RRC reconfiguration message.

S506, the terminal device performs handover according to the handover command in S505: the terminal device disconnects from the source network device and accesses to the target network device through a random access process.

And S507, when the terminal equipment is successfully accessed to the target network equipment, the switching is completed. The terminal device finishes the switching process by sending an RRC reconfiguration complete message to the target network device.

In the foregoing handover procedure, after the terminal device receives the handover command of the source network device (i.e. S505 in fig. 5) and before the terminal device successfully accesses the target network device (i.e. S507 in fig. 5), the terminal device may not disconnect from the source network device, that is, the terminal device may continue to communicate with the source network device through an RLC entity (denoted as RLC a) associated with the source network device.

For example, in the DAPS handover procedure, after the terminal device receives a handover command from the source network device, the terminal device may establish an RLC entity (denoted as RLC B) corresponding to the target network device. After receiving the handover command and before successfully accessing the target network device, the terminal device performs data transmission with the source network device through the RLC a, and at this time, the RLC B is in a deactivated state, that is, the terminal device does not perform data transmission with the target network device through the RLC B. After the terminal device successfully accesses the target network device, the terminal device does not perform data transmission with the source network device through the RLC a any more, but performs data transmission with the source network device through the RLC B. By means of the DAPS handover, it is ensured that data transmission between the terminal device and the network device is not interrupted during the handover of the terminal device from one network device to another network device, so that the delay of data transmission can be reduced.

However, although the existing DAPS handover procedure can ensure that data transmission between the terminal device and the network device is not interrupted, the terminal device can only perform data transmission with the source network device or the target network device through one RLC entity, and cannot meet the requirement of URLLC service on high reliability. Based on the above problems, the embodiments of the present application will mainly study how to improve the reliability of data transmission in a scenario where a terminal device is switched.

Fig. 6 is a schematic flow chart of a data transmission method provided in an embodiment of the present application, where this embodiment relates to a specific process of data transmission between a terminal device and a source network device and between the terminal device and a target network device in a process of switching the terminal device from the source network device to the target network device. In the embodiment shown in fig. 6, before the terminal device initiates the handover, the terminal device performs DC duplicate-based transmission with the source network device and the target network device, where the source network device is a main network device of the terminal device before the handover is initiated, and the target network device is an auxiliary network device of the terminal device before the handover is initiated. As shown in fig. 6, the method may include: s601 to S607, wherein S607 is an optional operation. The execution sequence of S601 to S607 is not limited in the embodiment of the present application.

S601, the source network device sends first configuration information to the terminal device, and correspondingly, the terminal device receives the first configuration information from the source network device. Optionally, the first configuration information may be carried in an RRC reconfiguration message, an RRC setup message, or an RRC recovery message.

The first configuration information is used for configuring a PDCP duplicate function of the first RB of the terminal device in the source network device. In this embodiment of the application, the first configuration information configures a PDCPduplication function at the source network device for the first RB of the terminal device, and may be understood as: the terminal device is connected to the source network device and the target network device at the same time, and the terminal device can transmit data of the first RB with the source network device and the target network device by using a DC duplicate function, wherein the source network device is a main network device connected with the terminal device, and the target network device is an auxiliary network device connected with the terminal device.

Illustratively, the first configuration information includes one or more of the following parameters:

1. identification of the first RB.

2. An identity of a primary RLC entity associated with the first RB. Wherein the first RB is associated with a primary RLC entity that cannot be dynamically deactivated. Optionally, the terminal device may transmit the PDCP control PDU with the network device through the master RLC entity.

3. An identity of a secondary RLC entity associated with the first RB. Wherein the first RB may be associated with one or more secondary RLC entities, which may be dynamically deactivated. Optionally, the terminal device may not transmit the PDCP control PDU through the secondary RLC entity, but may transmit the PDCP data PDU copied through the PDCP layer through the secondary RLC entity.

4. DAPS configuration information indicating whether the first RB supports a DAPS handover operation.

After receiving the first configuration information, the terminal device establishes a PDCP entity associated with the first RB (hereinafter referred to as a first PDCP entity) on the terminal device side. Optionally, the first PDCP entity may establish a ciphering function (ciphering function) suitable for the source network device, that is, the first PDCP entity encrypts and decrypts data packets received by the first PDCP entity by using a key (hereinafter, referred to as a first key) suitable for the source station.

Optionally, the first PDCP entity may establish an integrity protection function (integrity protection function) applicable to the source network device, that is, the first PDCP entity performs integrity protection and integrity check on the data packet received by the first PDCP entity by using an integrity protection algorithm and an integrity protection key applicable to the source station. In the embodiments of the present application, integrity protection refers to: the method comprises the steps that a sending end uses an integrity protection algorithm to calculate a message integrity authentication code (MAC-I) of data to be sent, the sending end sends the MAC-I and the data to be sent to a receiving end together, the receiving end calculates an expected MAC-I according to the same integrity protection algorithm and compares the expected MAC-I with the received MAC-I, if the expected MAC-I and the received MAC-I are the same, the receiving end considers that the content of the data is not tampered, and if the expected MAC-I and the received MAC-I are not the same, the data is tampered.

Optionally, the first PDCP entity may further establish a header compression function applicable to the source network device. In the embodiment of the present application, the header compression function refers to: the transmitting end may compress subheaders of a transport layer, a network layer, and the like of data to be transmitted based on a robust header compression (ROHC) architecture and/or an Ethernet Header Compression (EHC) architecture. Illustratively, the transmitting end establishes a compression context (context), which indicates the content of the uncompressed sub-header, thereby reducing the overhead of the sub-header. Correspondingly, the receiving end can recover the content of the uncompressed subheader through context.

After the terminal device receives the first configuration information, the terminal device may further establish an RLC entity associated with the first RB (which may also be referred to as a first PDCP-associated RLC entity). Illustratively, the first RB is associated with 2 RLC entities, RLC1 and RLC2, respectively. The RLC1 is an RLC entity corresponding to the source network device, and the RLC2 is an RLC entity corresponding to the target network device. The terminal device may communicate data with the source network device via RLC1 and/or RLC 2. Illustratively, the PDCP entity of the terminal device encrypts PDCP data PDUs using the first key, and submits the encrypted PDCP data PDUs to the RLC1 and/or RLC2, so that the RLC1 and/or RLC2 transmit data to a corresponding MAC entity, and then the MAC layer entity generates a transport block, and then the corresponding physical layer entity transmits the transport block to the source network device over an air interface.

If the RLC1 is the main RLC entity and the initial state of the RLC2 is the deactivation state, the terminal device transmits data with the network device through the RLC 1; if the RLC1 is the main RLC entity and the initial state of the RLC2 is active, the terminal equipment transmits data with the network equipment through the RLC1 and the RLC 2; if the RLC2 is the main RLC entity and the initial state of the RLC1 is the deactivation state, the terminal device transmits data with the network device through the RLC 2; if the RLC2 is the main RLC entity and the initial status of the RLC1 is active, the terminal device transmits data with the network device through the RLC1 and the RLC 2.

Optionally, the source network device further sends a first message to the terminal device, and correspondingly, the terminal device receives the first message from the network device. The first message is used for activating or deactivating a secondary RLC entity associated with the first RB. Optionally, the first message is a MAC CE. Exemplarily, one possible form of the first message is shown in fig. 8, where DRB ID is an identity of a DRB, RLCi is an RLC entity associated with the DRB (i is a non-negative integer), and if RLCi ═ 1 indicates that a PDCP duplicate function of RLCi is activated; if the RLCi is 0, it means that the PDCP duplicate function of the RLCi is deactivated.

The source network device may further send third configuration information to the terminal device, and correspondingly, the terminal device receives the third configuration information from the source network device. The third configuration information is used for configuring a master cell group associated with the source network device and/or a secondary cell group associated with the target network device. The master cell group comprises a master cell and at least one auxiliary cell, the master cell group is associated with an MAC entity, and the MAC entity is associated with at least one RLC entity; the secondary cell group comprises a primary cell and at least one secondary cell, the secondary cell group is associated with a MAC entity, and the MAC entity is associated with at least one RLC entity. Optionally, the third configuration information may be carried on an RRC reconfiguration message, an RRC setup message, or an RRC recovery message. Optionally, the third configuration information and the first configuration information may be carried on the same or different messages. Optionally, the third configuration information and the first configuration information may be sent simultaneously or separately, and the order of sending the third configuration information and the first configuration information is not limited in this application embodiment.

S602, the source network device sends first indication information to the terminal device, and correspondingly, the terminal device receives the first indication information from the source network device. The first indication information may be carried on an RRC reconfiguration message, an RRC setup message, or an RRC recovery message. Optionally, the first indication information and the first configuration information may be carried on the same or different messages.

The first indication information indicates whether to maintain a PDCP copy function of the first RB at the source network device when the terminal device is handed over from the source network device to the target network device.

Specifically, the first indication information indicates whether the terminal device maintains the PDCP copy function of the first RB in the source network device during the period from the start of the handover to the completion of the handover. The manner of indicating whether to maintain the PDCP copy function of the first RB in the source network device by the first indication information includes, but is not limited to, the following manners:

mode 1

If the value of the first indication information is the first value, the terminal equipment keeps the PDCP copy function of the first RB in the source network equipment; and if the value of the first indication information is the second value, not maintaining the PDCP copy function of the first RB at the source network equipment. Illustratively, the first value may be "true" or "enabled"; the second value may be "false", "disabled", or the second value is null.

Mode 2

When the source network equipment sends first indication information to the terminal equipment, namely, when the terminal equipment receives the first indication information from the source network equipment, the first indication information indicates the terminal equipment to keep the PDCP copy function of the first RB in the source network equipment; when the source network equipment does not send the first indication information to the terminal equipment, namely, the terminal equipment does not receive the first indication information from the source network equipment, the first indication information indicates that the terminal equipment does not keep the PDCP copy function of the first RB at the source network equipment; or, when the source network device sends the first indication information to the terminal device, that is, when the terminal device receives the first indication information from the source network device, the first indication information indicates that the terminal device does not maintain the PDCP copy function of the first RB in the source network device; when the source network device does not send the first indication information to the terminal device, that is, the terminal device does not receive the first indication information from the source network device, the first indication information indicates the terminal device to maintain the PDCP copy function of the first RB in the source network device. Optionally, in mode 2, a value of the first indication information may be "true" or false ".

In the above mode 1 and mode 2, the terminal device maintains the PDCP copy function of the first RB in the source network device, and it can be understood that: the terminal equipment keeps transmitting data of the first RB with the source network equipment and the target network equipment by using a DC duplicate function. The terminal device does not maintain the PDCP copy function of the first RB in the source network device, which can be understood as follows: the terminal device releases the PDCP copy function of the first RB in the source network device, that is, the terminal device does not use the DC copy function with the source network device and the target network device to transmit the data of the first RB any more.

In this embodiment of the present application, the flag for handover initiation may include: the terminal equipment receives a switching command from source network equipment; alternatively, the flag for handover initiation may include: the source network equipment receives a switching request confirmation message from the target network equipment; alternatively, the flag for handover initiation may include: the source network device sends a handover request command to the target network device, which is not limited in the embodiments of the present application.

In this embodiment of the present application, the flag indicating that the handover is completed may include: after initiating the random access procedure to the target network device, the terminal device successfully accesses the target network device, or the flag indicating that the handover is completed may include: the terminal equipment sends an RRC reconfiguration message for finishing the switching process to the target network equipment; alternatively, the flag of handover completion may include: the target network device receives an RRC reconfiguration message from the terminal device for ending the handover process, which is not limited in this embodiment of the present application.

S603, the source network device sends a switching request message to the target network device, and correspondingly, the target network device receives the switching request message from the source network device.

S604, if the target network device allows the terminal device to access, the target network device sends a switching request confirmation message to the source network device.

S605, the source network device sends a handover command to the terminal device, where the handover command includes an RRC reconfiguration message. And after the terminal equipment receives the switching command of the source network equipment, starting a switching flow.

And S606, the terminal device transmits the data of the first RB with the source network device according to the first indication information.

Specifically, the function of maintaining the PDCP copy of the first RB in the source network device includes: and keeping a first Radio Link Control (RLC) entity, wherein the first RLC entity is the RLC entity corresponding to the target network equipment before the handover is initiated. The above PDCP copy function not maintaining the first RB between the source network device and the target network device includes: and the first Radio Link Control (RLC) entity is released, wherein the first RLC entity is the RLC entity corresponding to the target network equipment.

In the embodiment of the present application, maintaining the first RLC entity may also be understood as: the first RLC entity is not released or can also be understood as: the first RLC entity is in an available state, and the terminal device can transmit data with the source network device through the first RLC entity. When the first indication information indicates to maintain the PDCP copy function of the first RB in the source network device, the terminal device may transmit data with the source network device through the first RLC entity after the handover is initiated. Illustratively, after the handover is initiated, the terminal device may submit the data packet encrypted by using the first secret key to the first RLC entity.

In the embodiment of the present application, the first RLC entity is released, which may also be understood as: the first RLC entity is suspended or can be understood as: the first RLC entity is in an unavailable state, and the terminal device cannot transmit data with the source network device through the first RLC entity. When the first indication information indicates that the PDCP copy function of the first RB in the source network device is not maintained, the terminal device cannot transmit data with the source network device through the first RLC entity after the handover is initiated.

Exemplarily, as shown in fig. 7, fig. 7(a) illustrates a first PDCP entity associated with a first RB and an RLC entity associated with the first PDCP entity (i.e., the first RLC entity associated with the first RB configured by the first configuration information) before handover initiation. The RLC1 is an RLC entity corresponding to the source network device, and the RLC2 is an RLC entity corresponding to the target network device (i.e., a first RLC entity). If the value of the first indication information is the first value, after the handover is initiated, the terminal device may transmit data with the source network device through the RLC1 and the RLC2, for example, a PDCP entity of the terminal device encrypts PDCP data PDUs by using the first key, and delivers the encrypted PDCP data PDUs to the RLC1 and the RLC 2; if the value of the first indication information is the second value, the terminal device can only transmit data with the source network device through the RLC1 in the period from the initiation of the handover to the completion of the handover, specifically, the PDCP entity of the terminal device encrypts the PDCP data PDU by using the first key, and delivers the encrypted PDCP data PDU to the RLC 1.

S607, optionally, the source network device sends the second configuration information to the terminal device, and correspondingly, the terminal device receives the second configuration information from the target network device, where the second configuration information is used to configure the PDCP copy function of the first RB in the target network device. Illustratively, the PDCP replication function of the first RB at the target network device may be understood as: the first RB is at the CA duplicate function of the target network device. Optionally, the second configuration information may be carried on an RRC reconfiguration message, an RRC setup message, or an RRC recovery message. Optionally, the second configuration information is carried on the same message or a different message as the first configuration information. Optionally, the second configuration information and the third configuration information are carried on the same or different messages. In this embodiment of the present application, the first configuration information, the second configuration information, and the third configuration information may be sent simultaneously or separately, and the order of sending the first configuration information, the second configuration information, and the third configuration information is not limited in this embodiment of the present application.

Optionally, the source network device receives a handover request confirmation message from the target network device before sending the second configuration information to the terminal device (as shown in S604), where the handover request confirmation message includes the second configuration information. That is, the source network device forwards the second configuration information from the target network device to the terminal device. Optionally, the second configuration information may be carried on the RRC reconfiguration message in S605.

Illustratively, the second configuration information includes one or more of the following parameters:

1. identification of the first RB.

2. An identity of a primary RLC entity associated with the first RB. Wherein the first RB is associated with an RLC entity that cannot be dynamically deactivated. Optionally, the terminal device may transmit the PDCP control PDU with the network device through the master RLC entity.

And after receiving the second configuration information, the terminal equipment reconfigures the PDCP entity associated with the first RB on the terminal equipment side. In this embodiment of the present application, reconfiguring the PDCP entity associated with the first RB may also be understood as: and reestablishing the PDCP entity associated with the first RB, wherein the new PDCP entity is the second PDCP entity. In the embodiment of the present application, for convenience of description, a PDCP entity (i.e., the second PDCP entity) for re-establishing the first RB association is illustrated.

In the embodiment of the present application, the second PDCP entity is in a suspended state before the handover is completed, and the second PDCP entity performs the function of the PDCP entity instead of the first PDCP entity only after the handover is completed. It should be understood that the second PDCP entity may also be a PDCP entity after the first PDCP entity is reconfigured by the second configuration information, and there is no substantial difference between the two modes.

Optionally, the second PDCP entity may establish a ciphering function suitable for the target network device, that is, the second PDCP entity ciphers and deciphers the data packets received by the second PDCP entity using a key (hereinafter, referred to as a second key) suitable for the target station. Alternatively, the first and second secret keys may be the same or different. Optionally, the second PDCP entity may establish an integrity protection function suitable for the target network device. Optionally, the second PDCP entity may further establish a header compression function suitable for the target network device.

The terminal device also establishes a new RLC entity associated with the first RB (i.e., an RLC entity associated with the second PDCP). In this embodiment, before the handover is completed, the RLC entity associated with the second PDCP entity is in a suspended state, and only after the handover is completed, the RLC entity associated with the second PDCP entity performs the function of the RLC entity instead of the RLC entity associated with the first PDCP entity.

Fig. 7(b) shows the second PDCP entity associated with the first RB and the RLC entity associated with the second PDCP entity after the handover is completed. The RLC3 and the RLC4 are RLC entities corresponding to the target network device. Optionally, the initial state of the CA duplexing function of RLC3 and RLC4 is deactivated, that is, before the CA duplexing function is activated, the terminal device cannot perform CA duplexing-based data transmission through RLC3 and RLC 4. Optionally, before the handover is completed, the states of the RLC3 and the RLC4 are deactivated, that is, before the handover is completed, the terminal device may not perform data transmission with the target network device through the RLC3 and the RLC 4.

After the handover is completed, the terminal device activates a PDCP replication function (i.e., a caducization function) of the first RB in the target network device. Illustratively, the activating, by the terminal device, the PDCP copy function of the first RB in the target network device specifically includes: and the terminal equipment activates the RLC entity which is associated with the first RB and corresponds to the target network equipment. Specifically, the following two ways of activating the PDCP copy function of the first RB in the target network device by the terminal device are available:

mode 1, the target network device sends the second indication information to the terminal device, and correspondingly, the terminal device receives the second indication information from the terminal device Second indication information of the target network device. The second indication information is used for activating a PDCP reply of the first RB at the target network device And (5) controlling functions.

Taking fig. 7(b) as an example, after receiving the second indication information, the terminal device activates RLC3 and RLC4, that is, the terminal device can perform data transmission with the target network device through RLC3 and RLC 4. Optionally, the second indication information is a MAC CE.

Mode 2, after the above switching is completed, the terminal device activates the PDCP copy function of the first RB in the target network device Can be used.

Exemplarily, when the handover is completed, the terminal device activates a PDCP copy function of the first RB in the target network device, which can also be understood as: and when the terminal equipment considers that the switching is finished, the terminal equipment activates a PDCP copy function of the first RB in the target network equipment.

In a possible mode, after the terminal device considers that the random access process between the terminal device and the target network device is successful, the PDCP copy function of the first RB in the target network device is activated. For example, when the terminal device performs random access with the target network device by using a two-step random access method, when the terminal device receives a message B (the message B includes one or more of an RRC establishment message and an RRC recovery message) of the target network device, and the RRC layer of the terminal device considers that the random access process is successful by analyzing the message B, the RRC layer of the terminal device instructs the PDCP layer to activate a PDCP copy function of the first RB in the target network device; when the terminal device performs random access with the target network device by adopting a four-step random access method, when the terminal device receives a message 4 (the message 4 comprises one or more of an RRC establishment message and an RRC recovery message) of the target network device, and an RRC layer of the terminal device considers that the random access process is successful by analyzing the message 4, the RRC layer of the terminal device indicates the PDCP layer to activate a PDCP copy function of a first RB in the target network device.

In another possible manner, after the terminal device sends a handover complete message (i.e., the RRC reconfiguration complete message in S507) to the target network device on the time-frequency resource of the target network device, the terminal device considers that the handover is completed, and at this time, the terminal device activates the PDCP copy function of the first RB in the target network device. Optionally, this method may be applicable to handover with random access, that is, after the random access procedure between the terminal device and the target network device is successful (S506 in fig. 5), a handover completion message is sent to the target network device (S507 in fig. 5); this method may also be applicable to random access-less (RACH-less), that is, after the target network device allows the terminal device to access (S504 in fig. 5), the terminal device does not initiate a random access procedure with the target network device, but the target network device directly allocates a time-frequency resource to the terminal device, and the terminal device sends a handover completion message to the target network device on the time-frequency resource.

By the method in embodiment 2, the terminal device may determine whether to complete handover, and when the terminal device considers that handover is completed, the terminal device may immediately activate the PDCP copy function of the first RB in the target network device, so that the terminal device may perform data transmission based on PDCP copy with the source network device before handover is completed, and after handover is completed, the terminal device may immediately perform data transmission based on PDCP copy with the target network device, so that data transmission based on PDCP copy is not interrupted by handover, and reliability of data transmission is improved.

It can be understood that, after the handover is completed, the terminal device no longer transmits the data of the first RB with the source network device through the RLC entity corresponding to the source network device. After the terminal device activates the RLC entity associated with the first RB and corresponding to the target network device by using, but not limited to, the methods in the foregoing manner 1 and manner 2, the terminal device transmits data of the first RB to the target network device through the RLC entity associated with the first RB and corresponding to the target network device. Illustratively, the terminal device submits the data packet of the first RB (corresponding to RLC3 and RLC4 in fig. 7) encrypted using the key of the target network device to the RLC entity corresponding to the target network device (i.e., the RLC entity associated with the second PDCP entity). The data packet may be a PDCP control PDU and/or a PDCP data PDU, and the data packet may be a newly transmitted data packet or a retransmitted data packet.

The foregoing embodiment provides a method for data transmission, where when a terminal device is handed over from a source network device to a target network device, the source network device instructs the terminal device whether to continue to use an RLC entity corresponding to the target network device and the source network device to transmit data of a first RB during a period from after the handover is initiated to before the handover is completed. For a service with a higher reliability requirement, for example, a service carried by a first RB is a URLLC service, and a source network device may instruct to continue to use an RLC entity corresponding to a target network device before handover initiation and the source network device to transmit data of the first RB in the period from after the handover initiation to before the handover is completed, so that it may be ensured that, in a handover process, a terminal device may transmit a same data packet copied through a PDCP layer through at least two RLC entities and a network device, thereby implementing 0 millisecond interruption of a PDCP copy function of the URLLC service in the handover process, and improving reliability of the URLLC service in the handover process. For a service with low reliability requirement, for example, the service carried by the first RB is an eMBB service, the source network device may instruct that the RLC entity corresponding to the target network device before handover initiation is no longer used to transmit data of the first RB with the source network device after the handover initiation. By implementing the method, the source network equipment can flexibly indicate the data transmission mode of the service with different reliability requirements during switching, thereby improving the flexibility of data transmission. In addition, by implementing the method, after the handover is completed, the terminal device can immediately transmit the data of the first RB with the target network device by using the PDCP copy function, so that the terminal device can still transmit the data of the first RB with the network device by using the PDCP copy function after the handover to the target network device, thereby improving the reliability of data transmission.

Alternatively, in the embodiment shown in fig. 6, S607 may be replaced with S607 a.

S607a, optionally, the source network device sends the second configuration information to the terminal device, and correspondingly, the terminal device receives the second configuration information from the target network device, where the second configuration information is used to configure the PDCP copy function of the first RB in the target network device. Wherein, the PDCP copy function of the first RB in the target network device may be understood as: the first RB is at the CA duplicate function of the target network device. Optionally, the second configuration information may be carried on an RRC reconfiguration message, an RRC setup message, or an RRC recovery message. Optionally, the second configuration information and the first configuration information may be carried on the same or different messages.

Illustratively, the second configuration information includes an identification of the first RB. The second configuration information further comprises any of the following parameters:

1. an identity of a primary RLC entity associated with the first RB. Illustratively, the first RB is associated with an RLC entity that cannot be dynamically deactivated, and optionally, the terminal device may transmit PDCP control PDUs with the network device via the primary RLC entity.

2. An identity of a secondary RLC entity associated with the first RB. Optionally, the terminal device cannot transmit PDCP control PDUs through the secondary RLC entity, but may transmit PDCP data PDUs copied through the PDCP layer through the secondary RLC entity.

And after receiving the second configuration information, the terminal equipment reconfigures the PDCP entity associated with the first RB on the terminal equipment side. Wherein, reconfiguring the PDCP entity associated with the first RB can also be understood as: and reestablishing the PDCP entity associated with the first RB, wherein the new PDCP entity is the second PDCP entity. In the embodiment of the present application, for convenience of description, a PDCP entity (i.e., the second PDCP entity) for re-establishing the first RB association is illustrated.

The source network device further sends third indication information to the terminal device, and correspondingly, the terminal device receives the third indication information from the source network device. Illustratively, the third indication information indicates whether the first RLC entity is the RLC entity corresponding to the target network device after the handover is completed, where the first RLC entity is the RLC entity corresponding to the target network device before the handover is initiated. In other words, the third indication information is used to indicate whether the terminal device associates the first RLC entity to the second PDCP entity. Optionally, the third indication information may be carried on an RRC reconfiguration message, an RRC setup message, or an RRC recovery message.

In an optional manner, if the value of the third indication information is a third value, the terminal device associates the first RLC entity with the second PDCP entity; and if the value of the third indication information is a fourth value, the terminal equipment does not associate the first RLC entity with the second PDCP. Illustratively, the third value may be "true" or "enabled", and the fourth value may be "false" or "disabled".

Alternatively, the third indication information is the same message as the first indication information. When the value of the first indication information is the first value, indicating that the terminal equipment associates the first RLC entity with the second PDCP; and when the value of the first indication information is the second value, indicating that the terminal equipment does not associate the first RLC entity with the second PDCP.

And the terminal equipment establishes a new RLC entity associated with the first RB (namely, the RLC entity associated with the second PDCP) according to the second configuration information and the third indication information. In this embodiment, before the handover is completed, the RLC entity associated with the second PDCP entity is in a suspended state, and only after the handover is completed, the RLC entity associated with the second PDCP entity performs the function of the RLC entity instead of the RLC entity associated with the first PDCP entity.

Exemplarily, as shown in fig. 9, fig. 9(a) illustrates a first PDCP entity associated with a first RB and an RLC entity associated with the first PDCP entity before handover initiation (i.e., the first PDCP entity configured for the terminal device by the first configuration information and the RLC entity associated with the first PDCP entity). The RLC1 is an RLC entity corresponding to the source network device, and the RLC2 is an RLC entity corresponding to the target network device (i.e., a first RLC entity).

When the third indication information indicates that the terminal device associates the first RLC entity to the second PDCP entity, the new RLC entities with which the terminal device establishes the first RB association are RLC2 and RLC3 (as shown in (b) of fig. 9). The terminal device can perform CA duplicate-based data transmission with the target network device using RLC2 and RLC3 after the above handover is completed. The RLC2 and the RLC3 are deactivated in the initial state of the CA duplication function of the target network device, that is, before the CA duplication function is activated, the terminal device cannot perform CA duplication-based data transmission with the target network device through the RLC2 and the RLC 3. Optionally, before the handover is completed, the status of the RLC3 is deactivated, that is, the terminal device may not perform data transmission with the target network device through the RLC 3.

After the handover is completed, the terminal device activates a PDCP replication function (i.e., a caducization function) of the first RB in the target network device. Illustratively, after the handover is completed, the terminal device activates the RLC entity associated with the first RB and corresponding to the target network device. The following two ways of the terminal device activating the PDCP copy function of the first RB in the target network device are:

Taking fig. 9(b) as an example, after receiving the second indication information, the terminal device activates RLC2 and RLC3, that is, the terminal device can perform data transmission with the target network device through RLC2 and RLC 3. Optionally, the second indication information is a MAC CE.

For exemplary purposes, the detailed description of mode 2 refers to the description of mode 2 in S607. By the method in embodiment 2, the terminal device may determine whether to complete handover, and when the terminal device considers that handover is completed, the terminal device may immediately activate the PDCP copy function of the first RB in the target network device, so that the terminal device may perform data transmission based on PDCP copy with the source network device before handover is completed, and after handover is completed, the terminal device may immediately perform data transmission based on PDCP copy with the target network device, so that data transmission based on PDCP copy is not interrupted by handover, and reliability of data transmission is improved.

It is understood that when the above handover is completed, the terminal device no longer transmits data of the first RB with the source network device through the RLC entity (e.g., RLC1 in fig. 9) associated with the source network device. After the terminal device activates the RLC entity associated with the first RB and corresponding to the target network device by using, but not limited to, the methods in the foregoing manner 1 and manner 2, the terminal device transmits data of the first RB with the target network device through the RLC entity associated with the first RB and corresponding to the target network device. Illustratively, the terminal device submits the data packet encrypted by using the key of the target network device to the RLC entity associated with the first RB and corresponding to the target network device. Wherein the RLC entity associated with the first RB corresponding to the target network device includes the first RLC entity (for example, the first RLC entity corresponds to RLC2 in fig. 9). The RLC entity corresponding to the target network device further includes a second RLC entity, where the second RLC entity is another RLC entity (for example, the second RLC entity corresponds to RLC3 in fig. 9) in the RLC entities corresponding to the target network device associated with the first RB, except for the first RLC entity. Optionally, the data packet may be a PDCP control PDU and/or a PDCP data PDU, and the data packet may be a newly transmitted data packet or a retransmitted data packet.

For downlink transmission, before handover is completed, data transmitted to the terminal device by the source network device through the first RLC entity is encrypted by using a first secret key, after handover is completed, data transmitted to the terminal device by the target network device through the first RLC entity is encrypted by using a second secret key, and when the terminal device and the network device have a deviation in judgment of the handover completion time, the terminal device cannot know whether the data received by the first RLC entity is encrypted by using the first secret key or the second secret key. In order to solve this problem, the embodiments of the present application provide two alternative ways:

in the first mode, the source network device sends fourth indication information to the terminal device, and correspondingly, the terminal device receives the fourth indication information from the source network device. The fourth indication information indicates that the data received by the terminal device after receiving the fourth indication information are all encrypted by using the second secret key. Optionally, the fourth indication information may be an RRC message or a MAC CE.

And secondly, the terminal equipment maintains a timer, and starts the timer after the terminal equipment considers that the switching is completed. And when the timer is overtime, the terminal equipment considers that the received data are encrypted by using the second secret key after the timer is overtime. Optionally, the duration of the timer is preset.

By implementing the method of S607a, the RLC entity (first RLC entity) corresponding to the target network device before the handover is initiated is converted into the RLC entity corresponding to the target network device after the handover is completed, so that the terminal device can perform data transmission based on PDCP replication with the target network device through the RLC entities (second RLC entities) except the first RLC entity in the first RLC entity and the RLC entity corresponding to the target network device after the handover is completed, thereby preventing the data transmission based on PDCP replication of the first RB from being interrupted by the handover, and improving reliability of data transmission. Meanwhile, by the method, the target network equipment only needs to configure the second RLC entity, and the terminal equipment can perform data transmission based on PDCP copy with the target network equipment, so that the overhead of resource configuration is reduced.

Optionally, in the embodiment shown in fig. 6, S607 may also be replaced with S607 b.

S607b, optionally, the source network device sends the second configuration information to the terminal device, and correspondingly, the terminal device receives the second configuration information from the target network device, where the second configuration information is used to configure the RLC entity associated with the first RB and corresponding to the target network device. Optionally, the second configuration information may be carried on an RRC reconfiguration message, an RRC setup message, or an RRC recovery message. Optionally, the second configuration information and the first configuration information may be carried on the same or different messages.

Exemplarily, as shown in fig. 10, fig. 10(a) shows a first PDCP entity associated with a first RB and an RLC entity associated with the first PDCP entity before handover initiation. The RLC1 is an RLC entity corresponding to the source network device, and the RLC2 is an RLC entity corresponding to the target network device (i.e., a first RLC entity). Fig. 10(b) shows the second PDCP entity associated with the first RB and the RLC entity (i.e., RLC3) associated with the second PDCP entity after the handover is completed. Before the above handover is completed, the status of the RLC3 is deactivated, that is, the terminal device may not perform data transmission with the target network device through the RLC 3.

And after the switching is completed, the terminal equipment activates the RLC entity corresponding to the target network equipment. Illustratively, the terminal device activates the RLC entity corresponding to the target network device in the following two ways:

mode 1, the target network device sends the second indication information to the terminal device, and correspondingly, the terminal device receives the second indication information from the terminal device Second indication information of the target network device. The second indication informationFor activating the RLC entity corresponding to the target network device.

Taking fig. 10 as an example, after receiving the second indication information, the terminal device activates RLC3, that is, the terminal device may perform data transmission with the target network device through RLC 3. Optionally, the second indication information is a MAC CE.

Mode 2, after the handover is completed, the terminal device activates the RLC entity corresponding to the target network device.

For example, when the handover is completed, the terminal device activates the RLC entity corresponding to the target network device, which may also be understood as: and when the terminal equipment considers that the switching is finished, the terminal equipment activates the RLC entity corresponding to the target network equipment.

In a possible mode, after the terminal device considers that the random access process between the terminal device and the target network device is successful, the RLC entity corresponding to the target network device is activated. Illustratively, after the random access is successful, the MAC layer of the terminal device indicates to the RRC layer that the uplink data handover is completed.

Another possible mode is that after the terminal device sends a handover complete message (i.e., an RRC reconfiguration complete message) to the target network device on the time-frequency resource of the target network device, the terminal device considers that the uplink data handover is completed, and at this time, the terminal device activates an RLC entity corresponding to the target network device. Optionally, this method may be applied to handover with random access, and may also be applied to handover without random access, where the handover with random access and the handover without random access are described in S607.

By the method in embodiment 2, the terminal device may determine whether to complete handover, and when the terminal device considers that handover is completed, the terminal device immediately activates the RLC entity corresponding to the target network device, so that the terminal device may perform data transmission based on PDCP replication with the source network device before handover is completed, and may immediately perform data transmission with the target network device after handover is completed, thereby improving reliability of data transmission.

After the terminal device activates the RLC entity corresponding to the target network device associated with the first RB by using, but not limited to, the method in manner 1 and manner 2 described above, the terminal device submits the data packet encrypted by using the key of the target network device to a second RLC entity, where the second RLC entity is another RLC entity (for example, the second RLC entity corresponds to RLC3 in fig. 10) in the RLC entity corresponding to the target network device except the first RLC entity. The data packet may be a PDCP control PDU and/or a PDCP data PDU, and the data packet may be a newly transmitted data packet or a retransmitted data packet.

Optionally, the terminal device submits the data packet encrypted by using the key of the source network device to the first RLC entity. After receiving the PDCP PDU from the first RLC entity, the PDCP entity of the source network device converts the PDCP PDU into a PDCP SDU, and forwards the PDCP SDU to the target network device.

By implementing the method of S607b, after the handover is completed, for uplink transmission, the PDCP entity of the terminal device duplicates data into two parts, one part may send data to the source network device through the RLC entity (first RLC entity) corresponding to the target network device before the handover is initiated, and then forwards the data to the target network device through the Xn interface by the source network device, and the other part may directly send the data to the target network device through the RLC entity (second RLC entity) corresponding to the target network device after the handover is completed, thereby improving reliability of data transmission. For downlink transmission, the source network device and the target network device may send the same data to the terminal: the source network equipment can also forward another same PDCP SDU to the target network equipment through an Xn interface, and the PDCP entity of the target network equipment converts the PDCP SDU into the PDCP PDU and then sends the PDCP PDU to the terminal equipment through a second RLC entity; or, the PDCP entity of the target network device converts one PDCP SDU into a PDCP PDU and sends the PDCP PDU to the terminal device through the second RLC entity, the target network device may also forward another identical PDCP SDU to the source network device through the Xn interface, and the PDCP entity of the source network device converts the PDCP SDU into a PDCP PDU and sends the PDCP PDU to the terminal device through the first RLC entity, thereby improving reliability of data transmission.

It is to be understood that, in order to implement the functions in the above embodiments, the network device and the terminal device include hardware structures and/or software modules for performing the respective functions. Those of skill in the art will readily appreciate that the various illustrative elements and method steps described in connection with the embodiments disclosed herein may be implemented as hardware, software, or combinations of hardware and software. Whether a function is implemented as hardware, software, or computer software drives hardware depends upon the particular application and design constraints imposed on the implementation.

Fig. 11 and 12 are schematic structural diagrams of a possible communication device provided in an embodiment of the present application. These communication apparatuses can be used to implement the functions of the terminal device or the source network device in the above method embodiments, so that the advantageous effects of the above method embodiments can also be achieved. In the embodiment of the present application, the communication apparatus may be the terminal device 110 shown in fig. 1, the network device 120 or the network device 130 shown in fig. 1, or a module (e.g., a chip) applied to the terminal device or the network device.

As shown in fig. 11, the communication device 1100 includes a processing unit 1110 and a transceiving unit 1120. The communication apparatus 1100 is used to implement the functions of the terminal device or the source network device in the method embodiment shown in fig. 6. Alternatively, the communication apparatus 1100 may include a module for implementing any function or operation of the terminal device or the source network device in the method embodiment shown in fig. 6, which may be implemented wholly or partially by software, hardware, firmware, or any combination thereof.

When the communication apparatus 1100 is used to implement the function of the terminal device in the method embodiment shown in fig. 6, the transceiving unit 1120 is configured to receive first configuration information from the source network device, where the first configuration information is used to configure a packet data convergence protocol PDCP replication function of the first radio bearer RB of the terminal device at the source network device; the transceiving unit 1120 is further configured to receive first indication information from the source network device, where the first indication information indicates whether to maintain a PDCP copy function of the first RB in the source network device when the terminal device is handed over from the source network device to the target network device; the transceiving unit 1120 is further configured to transmit data of the first RB with the source network device according to the first indication information.

When the communication apparatus 1100 is configured to implement the function of the source network device in the method embodiment shown in fig. 6, the transceiving unit 1120 is configured to send, to the terminal device, first configuration information, where the first configuration information is used to configure a packet data convergence protocol PDCP replication function of the first radio bearer RB of the terminal device at the source network device; the transceiving unit 1120 is further configured to send, to the terminal device, first indication information indicating whether to maintain a PDCP replication function of the first RB at the source network device when the terminal device is handed over from the source network device to the target network device; the transceiving unit 1120 is further configured to transmit data of the first RB with the source network terminal device according to the first indication information.

The more detailed description of the processing unit 1110 and the transceiver 1120 can be directly obtained by referring to the related description in the embodiment of the method shown in fig. 6, which is not repeated herein.

As shown in fig. 12, the communication device 1200 includes a processor 1210 and an interface circuit 1220. The processor 1210 and the interface circuit 1220 are coupled to each other. It is understood that the interface circuit 1220 may be a transceiver or an input-output interface. Optionally, the communication device 1200 may further include a memory 1230 for storing instructions to be executed by the processor 1210 or for storing input data required by the processor 1210 to execute the instructions or for storing data generated by the processor 1210 after executing the instructions.

When the communication apparatus 1200 is used to implement the method shown in fig. 6, the processor 1210 is used to implement the functions of the processing unit 1110, and the interface circuit 1220 is used to implement the functions of the transceiver 1120.

When the communication device is a chip applied to a terminal device, the terminal device chip implements the functions of the terminal device in the above method embodiment. The terminal device chip receives information from other modules (such as a radio frequency module or an antenna) in the terminal device, wherein the information is sent to the terminal device by the network device; or, the terminal device chip sends information to other modules (such as a radio frequency module or an antenna) in the terminal device, where the information is sent by the terminal device to the network device.

When the communication device is a chip applied to a network device, the network device chip implements the functions of the network device in the above method embodiments. The network device chip receives information from other modules (such as a radio frequency module or an antenna) in the network device, wherein the information is sent to the network device by the terminal device; alternatively, the network device chip sends information to other modules (such as a radio frequency module or an antenna) in the network device, and the information is sent by the network device to the terminal device.

It is understood that the Processor in the embodiments of the present Application may be a Central Processing Unit (CPU), other general purpose Processor, a Digital Signal Processor (DSP), an Application Specific Integrated Circuit (ASIC), a Field Programmable Gate Array (FPGA) or other programmable logic device, a transistor logic device, a hardware component, or any combination thereof. The general purpose processor may be a microprocessor, but may be any conventional processor.

In embodiments of the present application, the processor may be a Random Access Memory (RAM), a flash Memory, a Read-Only Memory (ROM), a Programmable ROM (PROM), an Erasable Programmable PROM (EPROM), an electrically Erasable Programmable EPROM (EEPROM), a register, a hard disk, a removable hard disk, a CD-ROM, or any other form of storage medium known in the art. An exemplary storage medium is coupled to the processor such the processor can read information from, and write information to, the storage medium. Of course, the storage medium may also be integral to the processor. The processor and the storage medium may reside in an ASIC. In addition, the ASIC may reside in a network device or a terminal device. Of course, the processor and the storage medium may reside as discrete components in a network device or a terminal device.

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 programs or instructions. When the computer program or instructions are loaded and executed on a computer, the processes or functions described in the embodiments of the present application are performed in whole or in part. The computer may be a general purpose computer, a special purpose computer, a computer network, a network appliance, a terminal device, or other programmable apparatus. The computer program or instructions may be stored in or transmitted over a computer-readable storage medium. 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 that integrates one or more available media. The usable medium may be a magnetic medium, such as a floppy disk, a hard disk, a magnetic tape; or an optical medium, such as a DVD; it may also be a semiconductor medium, such as a Solid State Disk (SSD).

In the embodiments of the present application, unless otherwise specified or conflicting with respect to logic, the terms and/or descriptions in different embodiments have consistency and may be mutually cited, and technical features in different embodiments may be combined to form a new embodiment according to their inherent logic relationship.

It is to be understood that the various numerical references referred to in the embodiments of the present application are merely for descriptive convenience and are not intended to limit the scope of the embodiments of the present application. The sequence numbers of the above-mentioned processes do not mean the execution sequence, and the execution sequence of the processes should be determined by their functions and inherent logic.

Claims

1. A method for data transmission, which is applied to the handover of a terminal device from a source network device to a target network device, and comprises the following steps:

receiving first configuration information from the source network equipment, wherein the first configuration information is used for configuring a Packet Data Convergence Protocol (PDCP) copy function of a first Radio Bearer (RB) of the terminal equipment in the source network equipment;

receiving first indication information from the source network device, wherein the first indication information indicates whether to keep a PDCP copy function of the first RB at the source network device when the terminal device is switched from the source network device to the target network device;

and transmitting the data of the first RB with the source network equipment according to the first indication information.

2. The method of claim 1, wherein the maintaining the PDCP copy function of the first RB at the source network device comprises:

and keeping a first Radio Link Control (RLC) entity, wherein the first RLC entity is the RLC entity corresponding to the target network equipment before the handover is initiated.

3. The method according to claim 1 or 2, wherein when the first indication information indicates that the PDCP copy function of the first RB in the source network device is maintained, the transmitting data of the first RB with the source network device according to the first indication information specifically comprises:

and when the switching is initiated, submitting a data packet encrypted by using the key of the source network equipment to the first RLC entity.

4. The method according to any one of claims 1 to 3, further comprising:

receiving second configuration information from the source network device, wherein the second configuration information is used for configuring a PDCP copy function of the first RB at the target network device;

and after the switching is completed, activating a PDCP copy function of the first RB in the target network equipment.

5. The method according to any one of claims 1 to 3, further comprising:

receiving second indication information from the target network device, wherein the second indication information is used for activating a PDCP copy function of the first RB at the target network device.

6. The method according to claim 4 or 5, wherein the activating the PDCP copy function of the first RB in the target network device specifically comprises: and activating the RLC entity associated with the first RB and corresponding to the target network equipment.

7. The method according to any of claims 4 to 6, wherein the first indication information further indicates that the first RLC entity is an RLC entity corresponding to the target network device after the handover is completed.

8. The method of claim 7, wherein after the handover is completed, the method further comprises:

submitting the data packet encrypted by using the key of the target network equipment to the first RLC entity.

9. A method according to claim 2 or 3, wherein after the handover is completed, the method further comprises:

submitting the data packet encrypted by using the key of the source network equipment to the first RLC entity.

10. The method according to claim 8 or 9, characterized in that the method further comprises:

and submitting a data packet encrypted by using the key of the target network equipment to a second RLC entity, wherein the second RLC entity is one of the RLC entities associated with the first RB, and the second RLC entity is the RLC entity corresponding to the target network equipment after the handover is completed.

11. A method for data transmission, which is applied to the handover of a terminal device from a source network device to a target network device, and comprises the following steps:

sending first configuration information to the terminal equipment, wherein the first configuration information is used for configuring a Packet Data Convergence Protocol (PDCP) copy function of a first Radio Bearer (RB) of the terminal equipment in the source network equipment;

sending first indication information to the terminal device, wherein the first indication information indicates whether to keep a PDCP copy function of the first RB at the source network device when the terminal device is switched from the source network device to the target network device;

and transmitting the data of the first RB with the terminal equipment according to the first indication information.

12. The method of claim 11, wherein the maintaining the PDCP copy function of the first RB at the source network device comprises:

13. The method according to claim 11 or 12, wherein when the first indication information indicates that the PDCP copy function of the first RB in the source network device is maintained, the transmitting data of the first RB with the terminal device according to the first indication information specifically comprises:

and receiving a data packet encrypted by using the key of the source network equipment from the first RLC entity after the handover is initiated.

14. The method according to any one of claims 11 to 13, further comprising:

and sending second configuration information to the terminal equipment, wherein the second configuration information is used for configuring a PDCP copy function of the first RB in the target network equipment.

15. The method of claim 14, wherein the first indication information further indicates that the first RLC entity is an RLC entity corresponding to the target network device after the handover is completed.

16. The method according to any of claims 11 to 13, wherein after the handover is completed, the method further comprises:

receiving a data packet from the first RLC entity encrypted using a key of the source network device;

and forwarding the data packet encrypted by using the key of the source network device to the target network device.

17. A communications device comprising means for performing the method of any of claims 1 to 10.

18. A communications device comprising means for performing the method of any of claims 11 to 16.

19. A communication apparatus comprising a processor and a memory, the processor and the memory coupled, the processor configured to implement the method of any of claims 1 to 10.

20. A communications apparatus comprising a processor and a memory, the processor and the memory coupled, the processor configured to implement the method of any of claims 11 to 16.

21. A communications device comprising a processor and interface circuitry for receiving and transmitting signals from or sending signals to other communications devices than the communications device, the processor being operable by logic circuitry or executing code instructions to implement the method of any of claims 1 to 10.

22. A communications device comprising a processor and interface circuitry for receiving and transmitting signals from or sending signals to a communications device other than the communications device, the processor being operable by logic circuitry or executing code instructions to implement the method of any of claims 11 to 16.

23. A computer-readable storage medium, in which a computer program or instructions is stored which, when executed by a communication apparatus, implements a method according to any one of claims 1 to 10, or implements a method according to any one of claims 11 to 16.

24. A communication system comprising a communication apparatus according to any of claims 17, 19, 21 and a communication apparatus according to any of claims 18, 20, 22.