Method and apparatus for supporting handover

Abstract

According to the embodiment of the invention, a method and equipment for supporting switching are provided. The method comprises the following steps: receiving a message from a target base station center unit control plane entity; receiving a data packet from a source base station; and discarding a packet data convergence protocol (PDCP) service data unit (SDU) containing a packet data convergence protocol (PDCP) serial number (SN) in the received data packet according to the indication of the message. The problem of coordination work of the source base station and the target base station in the switching process can be solved. Particularly, under the condition that a source base station and / or a target base station support separation of a control plane and a data plane, a source base station center unit control plane entity, a source base station center unit user plane entity, a target base station center unit control plane entity and / or a target base station center unit user plane entity can work in a completely coordinated manner.

Description

[0001] This application is a divisional application of the invention patent application filed on January 8, 2021, with application number 202110024548.X and title "Method and apparatus for supporting switching". Technical Field

[0002] This invention relates to wireless communication technology, and more particularly to methods and devices that support handover. Background Technology

[0003] To meet the increased demand for wireless data communication services since the deployment of 4G communication systems, efforts have been made to develop improved 5G or near-5G communication systems. Therefore, 5G or near-5G communication systems are also referred to as "super 4G networks" or "post-LTE systems".

[0004] Wireless communication is one of the most successful innovations in modern history. Recently, the number of subscribers to wireless communication services surpassed 5 billion and continues to grow rapidly. The demand for wireless data services is growing rapidly due to the increasing prevalence of smartphones and other mobile data devices (such as tablets, laptops, netbooks, e-book readers, and machine-type devices) among consumers and businesses. To meet the rapid growth of mobile data services and support new applications and deployments, improving the efficiency and coverage of wireless interfaces is crucial.

[0005] A base station may include a base station central unit control plane entity and a base station central unit user plane entity.

[0006] When a UE moves between two base stations, in order to ensure service continuity, a handover process needs to be defined, including intra-system handover such as handover between gNBs, handover between a gNB and an eNB connected to the 5GC, and inter-system handover such as handover between a 5G system (5GS) and an evolved packet system (EPS). Summary of the Invention

[0007] Technical issues

[0008] For data forwarding, how the source and destination base stations coordinate their work remains an issue. Especially when the source and / or destination base stations support separate control and data planes, ensuring complete coordination between the source base station central unit control plane entity, the source base station central unit user plane entity, the destination base station central unit control plane entity, and / or the destination base station central unit user plane entity remains a challenge.

[0009] Technical solution

[0010] According to one aspect of the present invention, a method for supporting handover is provided, comprising: receiving a message from a destination base station central unit control plane entity; receiving a data packet from a source base station; and, according to the instruction of the message, discarding a PDCP service data unit (SDU) in the received data packet that contains a Packet Data Convergence Protocol (PDCP) sequence number (SN).

[0011] In one example, the message indication includes indication information sent via a bearer context modification request message, which indicates at least one of the following: full configuration or differential configuration; whether the PDCP SN is retained; whether PDCP is restarted; and whether packets containing PDCP SDUs with PDCP SNs are discarded.

[0012] In one example, according to the message's indication, discarding a received packet containing a PDCP SN as a PDCPSDU includes discarding a received packet containing a PDCP SN as a PDCP SDU when the indication message indicates at least one of the following: full configuration; PDCP SN not retained; PDCP restart; and discarding a PDCP SDU containing a PDCP SN.

[0013] In one example, the message indication includes at least one of the following: no PDCP SN status information was received; no PDCP SN status information for the data radio bearer (DRB) was received; no bearer context modification request message was received; and the received bearer context modification request message did not contain PDCP SN status information for the DRB.

[0014] In one example, discarding a PDCP SDU containing a PDCP SN involves identifying the SDU to be discarded based on the SN in the GTP-U data packet of the General Packet Radio Service (GPRS) Channel Protocol GTP User Plane.

[0015] In one example, the received data packet was sent by the source base station or forwarded by the source base station through the core network.

[0016] In one example, a PDCP SDU without a PDCP SN in the received data packet is new data.

[0017] According to another aspect of the present invention, a method for supporting handover is provided, comprising: receiving a handover request message; receiving a sequence number (SN) state transition message or a downlink radio access network (RAN) state transition message; and sending a message to a destination base station central unit user plane entity, wherein the destination base station central unit user plane entity, according to the instruction of the message, discards PDCP service data units (SDUs) in received data packets that contain a Packet Data Convergence Protocol (PDCP) sequence number (SN).

[0018] In one example, receiving a handover request message includes receiving a handover request message from a source base station, and receiving an SN state transition message includes receiving an SN state transition message from a source base station, wherein the handover request message is an Xn application protocol AP message or other inter-base station message, and wherein the SN state transition message is an Xn AP message or other inter-base station message.

[0019] In one example, receiving a handover request message includes receiving a handover request message from the core network, wherein the handover request message received from the core network is a Next Generation Application Protocol (NGAP) message or other messages between the base station and the core network.

[0020] In one example, the handover request message received from the core network includes the handover type.

[0021] In one example, the method also includes deciding whether to use a full configuration or a differential configuration.

[0022] In one example, sending a message to the destination base station central unit user plane entity includes sending a bearer context modification request message to the destination base station central unit user plane entity when the handover type is inter-system handover or when a decision is made to use full configuration.

[0023] In one example, the message indication includes indication information sent via a bearer context modification request message, which indicates at least one of the following: full configuration or differential configuration; whether the PDCP SN is retained; whether PDCP is restarted; and whether packets containing PDCP SDUs with PDCP SNs are discarded.

[0024] In one example, the message indication includes at least one of the following: no PDCP SN status information was received; no PDCP SN status information for the data radio bearer (DRB) was received; no bearer context modification request message was received; and the received bearer context modification request message did not contain PDCP SN status information for the DRB.

[0025] According to one aspect of the present invention, a method for supporting handover is provided, comprising: a destination base station receiving a handover request message; the destination base station sending information about whether the handover is fully configured or differentially configured to a source base station; and the source base station, based on the information, not sending a PDCP service data unit (SDU) containing a Packet Data Convergence Protocol (PDCP) sequence number (SN) to the destination base station.

[0026] In one example, the destination base station receiving a handover request message includes receiving a handover request message from a source base station or the core network, wherein the handover request message received from the source base station is an Xn Application Protocol (AP) message or other inter-base station message, and the handover request message received from the core network is a Next Generation Application Protocol (NGAP) message or other inter-base station and core network message.

[0027] In one example, the method further includes: the destination base station determining whether to use a full configuration or a differential configuration, which is specific to each data radio bearer.

[0028] In one example, when the source base station supports the separation of the source base station central unit user plane and the source base station central unit control plane, the source base station central unit control plane entity notifies the source base station central unit user plane entity not to send PDCP SDU containing PDCP SN to the destination base station.

[0029] In one example, the source base station central unit control plane entity notifying the source base station central unit user plane entity not to send a PDCP SDU containing a PDCP SN to the destination base station includes: the source base station central unit control plane entity sending indication information to the source base station central unit user plane entity, the indication information indicating at least one of the following: full configuration or differential configuration; whether the PDCP SN state is retained; whether only new data is sent; whether a PDCPSDU containing a PDCP SN is sent; whether PDCP data packets sent to the user equipment UE without acknowledgment by the UE are sent; and whether only PDCP SDUs without a PDCP SN are sent.

[0030] In one example, the source base station central unit control plane entity notifying the source base station central unit user plane entity not to send a PDCP SDU containing a PDCP SN to the destination base station includes: the source base station central unit control plane entity sending channel information for data forwarding to the source base station central unit user plane entity without requesting PDCP SN status information, in order to indicate that the source base station central unit control plane entity has not sent PDCP SN status information to the destination base station.

[0031] According to one aspect of the present invention, a method for supporting handover is provided, comprising: receiving a handover-related message; and indicating information for data forwarding to a source base station central unit user plane entity, wherein the source base station central unit user plane entity sends a PDCP service data unit (SDU) without containing a Packet Data Convergence Protocol (PDCP) SN to a destination base station based on the information for data forwarding.

[0032] In one example, the handover-related message is one of the handover request confirmation message and the handover command message, and receiving the handover-related message includes receiving the handover request confirmation message from the destination base station or receiving the handover command message from the core network, wherein the handover-related message indicates whether it is a full configuration or a differential configuration or indicates whether the Packet Data Convergence Protocol (PDCP) sequence number (SN) status is retained.

[0033] In one example, the information indicating the data forwarding includes sending indication information via a bearer context modification request message, and the indication information indicates at least one of the following: whether the PDCP SN state is preserved; whether only new data is sent; whether a PDCP SDU containing the PDCP SN is sent; whether a PDCP data packet sent to the user equipment UE without acknowledgment by the UE is sent; and whether only a PDCP SDU without the PDCP SN is sent.

[0034] In one example, the information indicated to the source base station central unit user plane entity for data forwarding includes: sending channel information for data forwarding without requesting PDCP SN status information, to indicate that the source base station central unit control plane entity has not sent PDCP SN status information to the destination base station.

[0035] According to one aspect of the present invention, a method for supporting handover is provided, comprising: receiving information indicating data forwarding; and, based on the information indicating data forwarding, sending a PDCP service data unit (SDU) that does not contain a Packet Data Convergence Protocol (PDCP) SN to a destination base station.

[0036] In one example, the information indicating the data forwarding includes indication information received via a bearer context modification request message, and the indication information indicates at least one of the following: whether the PDCP SN state is retained; whether only new data is sent; whether a PDCP SDU containing the PDCP SN is sent; whether a PDCP data packet sent to the user equipment UE without acknowledgment by the UE is sent; and whether only a PDCP SDU without the PDCP SN is sent.

[0037] In one example, receiving information indicating data forwarding includes receiving channel information for data forwarding from the source base station central unit control plane entity without requesting PDCP SN status information, to indicate that the source base station central unit control plane entity did not send PDCP SN status information to the destination base station.

[0038] According to another aspect of the present invention, a method for supporting handover is provided, comprising: a destination base station central unit control plane entity receiving a handover request message; the destination base station central unit control plane entity sending configuration information of the source DRB and configuration information of the destination DRB, and / or a mapping of the source QoS flow to the data radio bearer DRB and a mapping of the destination QoS flow to the DRB to a destination base station central unit user plane entity; and the destination base station central unit user plane entity using the source DRB configuration and / or the source QoS flow to the DRB to process forwarded data received from the source base station, and using the destination DRB configuration and / or the destination QoS flow to the DRB to process new data received from the core network.

[0039] In one example, the handover request message is received from either the source base station or the core network. The handover request message received from the source base station is an application layer message of the inter-base station interface, and the handover request message received from the core network is an application layer message of the base station and core network interface. The handover request message contains the configuration information of the user equipment (UE) at the source base station, and the configuration information includes the mapping from QoS flow to DRB.

[0040] In one example, when the destination base station central unit control plane entity decides to use a different QoS flow to DRB mapping than the source base station, the destination base station central unit control plane entity temporarily configures the same QoS flow to DRB mapping as the source base station to process the data forwarded by the source base station.

[0041] In one example, the destination's QoS flow information is represented by the existing QoS flow information to be established in the DRB information to be established in the interface message between the base station central unit control plane entity and the base station central unit user plane entity, and the source's QoS flow information is represented by a new information element; or, the destination's QoS flow information is represented by the existing QoS flow information to be established in the DRB information to be established in the interface message between the base station central unit control plane entity and the base station central unit user plane entity, and the source's QoS flow information is represented by a new information element; or, the destination's QoS flow is represented by the existing flow mapping information in the DRB information to be modified in the interface message between the base station central unit control plane entity and the base station central unit user plane entity, and the source's QoS flow is represented by a new information element; or, the destination's QoS flow is represented by the existing flow mapping information in the DRB information to be modified in the interface message between the base station central unit control plane entity and the base station central unit user plane entity, and the source's QoS flow is represented by a new information element; or, the destination's QoS flow is represented by the existing flow mapping information in the DRB information to be modified in the interface message between the base station central unit control plane entity and the base station central unit user plane entity, and the source's QoS flow is represented by a new information element. flow.

[0042] In one example, the destination base station central unit control plane entity directly sends the configuration information of the source DRB and the configuration information of the destination DRB to the destination base station central unit user plane entity, or sends the configuration information of the destination DRB and the differential configuration between the source and destination to the destination base station central unit user plane entity, or sends the configuration information of the source DRB and the differential configuration between the source and destination to the destination base station central unit user plane entity.

[0043] According to another aspect of the present invention, a method for supporting handover is provided, comprising: receiving a handover request message; and sending configuration information of the source DRB and the destination DRB, and / or a mapping of the source QoS flow to the data radio bearer DRB and a mapping of the destination QoS flow to the DRB to the user plane entity of the destination base station central unit, wherein the configuration of the source DRB and / or the mapping of the QoS flow to the DRB are used by the user plane entity of the destination base station central unit to process forwarded data received from the source base station, and the configuration of the destination DRB and / or the mapping of the QoS flow to the DRB are used by the user plane entity of the destination base station central unit to process new data received from the core network.

[0044] In one example, the destination's QoS flow information is represented by the existing QoS flow information to be established in the DRB information to be established in the interface message between the base station central unit control plane entity and the base station central unit user plane entity, and the source's QoS flow information is represented by a new information element; or, the destination's QoS flow information is represented by the existing QoS flow information to be established in the DRB information to be established in the interface message between the base station central unit control plane entity and the base station central unit user plane entity, and the source's QoS flow information is represented by a new information element; or, the destination's QoS flow is represented by the existing flow mapping information in the DRB information to be modified in the interface message between the base station central unit control plane entity and the base station central unit user plane entity, and the source's QoS flow is represented by a new information element; or, the destination's QoS flow is represented by the existing flow mapping information in the DRB information to be modified in the interface message between the base station central unit control plane entity and the base station central unit user plane entity, and the source's QoS flow is represented by a new information element; or, the destination's QoS flow is represented by the existing flow mapping information in the DRB information to be modified in the interface message between the base station central unit control plane entity and the base station central unit user plane entity, and the source's QoS flow is represented by a new information element. flow.

[0045] In one example, the destination base station central unit control plane entity directly sends the configuration information of the source DRB and the configuration information of the destination DRB to the destination base station central unit user plane entity, or sends the configuration information of the destination DRB and the differential configuration between the source and destination to the destination base station central unit user plane entity, or sends the configuration information of the source DRB and the differential configuration between the source and destination to the destination base station central unit user plane entity.

[0046] According to another aspect of the present invention, a method for supporting handover is provided, comprising: receiving source DRB configuration information and destination DRB configuration information from a destination base station central unit control plane entity, and / or receiving a mapping of source QoS flow to data radio bearer DRB and a mapping of destination QoS flow to DRB from the destination base station central unit control plane entity; and processing forwarded data received from the source base station using the source DRB configuration and / or the QoS flow to DRB mapping, and processing new data received from the core network using the destination DRB configuration and / or the QoS flow to DRB mapping.

[0047] In one example, the destination's QoS flow information is represented by the existing QoS flow information to be established in the DRB information to be established in the interface message between the base station central unit control plane entity and the base station central unit user plane entity, and the source's QoS flow information is represented by a new information element; or, the destination's QoS flow information is represented by the existing QoS flow information to be established in the DRB information to be established in the interface message between the base station central unit control plane entity and the base station central unit user plane entity, and the source's QoS flow information is represented by a new information element; or, the destination's QoS flow is represented by the existing flow mapping information in the DRB information to be modified in the interface message between the base station central unit control plane entity and the base station central unit user plane entity, and the source's QoS flow is represented by a new information element; or, the destination's QoS flow is represented by the existing flow mapping information in the DRB information to be modified in the interface message between the base station central unit control plane entity and the base station central unit user plane entity, and the source's QoS flow is represented by a new information element; or, the destination's QoS flow is represented by the existing flow mapping information in the DRB information to be modified in the interface message between the base station central unit control plane entity and the base station central unit user plane entity, and the source's QoS flow is represented by a new information element. flow.

[0048] In one example, the destination base station central unit control plane entity directly sends the configuration information of the source DRB and the configuration information of the destination DRB to the destination base station central unit user plane entity, or sends the configuration information of the destination DRB and the differential configuration between the source and destination to the destination base station central unit user plane entity, or sends the configuration information of the source DRB and the differential configuration between the source and destination to the destination base station central unit user plane entity.

[0049] According to another aspect of the present invention, a method for supporting handover is provided, comprising: a destination base station central unit control plane entity receiving a handover request message from a source base station or from a core network; the destination base station central unit control plane entity sending a source-end QoS flow to data radio bearer (DRB) mapping to a destination base station central unit user plane entity; the destination base station central unit user plane entity using the received source-end QoS flow to DRB mapping to process forwarded data received from the source base station; the destination base station central unit control plane entity sending a destination QoS flow to DRB mapping to the base station central unit user plane entity; and the destination base station central unit user plane using the newly received QoS flow to DRB mapping to process new data received from the core network and sending it to a user equipment (UE).

[0050] In one example, the method further includes: the destination base station central element control plane entity including a destination QoS Flow to DRB mapping in a handover command message, the handover command message being sent to the UE via the source base station.

[0051] In one example, the method further includes: the destination base station central unit control plane entity including a source QoS Flow to DRB mapping in a handover command message, the handover command message being sent to the UE via the source base station; the destination base station central unit control plane entity sending a Radio Resource Control (RRC) reconfiguration message to the UE, the RRC reconfiguration message including a destination-determined QoS Flow to DRB mapping; when the destination base station central unit user plane entity receives an endmarker data packet, the destination base station central unit user plane entity sending an indication message to the destination base station central unit control plane entity; and the destination base station central unit control plane entity sending the destination-determined QoS Flow to DRB mapping to the UE via the RRC reconfiguration message.

[0052] In one example, the mapping of source service QoS flow to DRB sent by the destination base station central unit control plane entity to the destination base station central unit user plane entity includes: the QoS flow information to be established is included in the DRB information to be established sent by the destination base station central unit control plane entity to the destination base station central unit user plane entity, and the QoS flow information to be established included in the DRB information to be established is set according to the mapping of source QoS flow to DRB.

[0053] In one example, the mapping of the destination QoS flow to DRB sent by the destination base station central unit control plane entity to the base station central unit user plane entity includes: the QoS flow information to be established is included in the DRB information to be established sent by the destination base station central unit control plane entity to the destination base station central unit user plane entity, and the QoS flow information to be established included in the DRB information to be established is set according to the mapping of the destination QoS flow to DRB.

[0054] According to another aspect of the present invention, a method for supporting handover is provided, comprising: receiving a handover request message from a source base station or from a core network; sending a mapping of a source-end QoS flow to a data radio bearer (DRB) to a destination base station central unit user plane entity, wherein the destination base station central unit user plane entity uses the received source-end QoS flow to DRB mapping to process forwarded data received from the source base station; and sending a destination QoS flow to DRB mapping to the base station central unit user plane entity, wherein the destination base station central unit user plane uses the newly received QoS flow to DRB mapping to process new data received from the core network and send it to a user equipment (UE).

[0055] In one example, sending the mapping of the source-end QoS flow to the data radio bearer (DRB) to the user plane entity of the destination base station central unit includes: including the QoS flow information to be established in the DRB information to be established sent by the control plane entity of the destination base station central unit to the user plane entity of the destination base station central unit, wherein the QoS flow information to be established in the DRB information to be established is set according to the mapping of the source-end QoS flow to the DRB; and wherein sending the mapping of the destination QoS flow to the DRB to the user plane entity of the base station central unit includes: including the QoS flow information to be established in the DRB information to be established sent by the control plane entity of the destination base station central unit to the user plane entity of the destination base station central unit, wherein the QoS flow information to be established in the DRB information to be established is set according to the mapping of the destination-end QoS flow to the DRB.

[0056] According to another aspect of the present invention, a method for supporting handover is provided, comprising: receiving a source-end QoS flow to DRB mapping from a destination base station central unit control plane entity; using the received source-end QoS flow to DRB mapping to process forwarded data received from the source base station; receiving a destination QoS flow to DRB mapping from the destination base station central unit control plane entity; and using the newly received QoS flow to DRB mapping to process new data received from the core network and send it to the user equipment (UE).

[0057] In one example, receiving the mapping from the source end QoS flow to the Data Radio Bearer (DRB) from the destination base station central unit control plane entity includes: the DRB information to be established sent by the destination base station central unit control plane entity to the destination base station central unit user plane entity includes the QoS flow information to be established, wherein the QoS flow information to be established in the DRB information to be established is set according to the mapping from the source end QoS flow to the DRB; and wherein receiving the destination QoS flow to DRB mapping from the destination base station central unit control plane entity includes: the DRB information to be established sent by the destination base station central unit control plane entity to the destination base station central unit user plane entity includes the QoS flow information to be established, wherein the QoS flow information to be established in the DRB information to be established is set according to the mapping from the destination end QoS flow to the DRB.

[0058] According to another aspect of the present invention, a method for supporting handover is provided, comprising: a destination base station central unit control plane entity receiving a handover request message from a source base station or a core network; the destination base station central unit control plane entity sending a mapping of a source-end QoS flow to a data radio bearer (DRB) to a destination base station central unit user plane entity; the destination base station central unit user plane entity using the received source-end QoS flow to DRB mapping to process forwarded data received from the source base station; the destination base station central unit control plane entity sending a destination QoS flow to DRB mapping to the destination base station central unit user plane entity and sending indication information; and the destination base station central unit user plane entity using the received source-end QoS flow to DRB mapping to process forwarded data received from the source base station, and using a newly received destination QoS flow to DRB mapping to process new data received from the core network.

[0059] In one example, the destination base station central unit user plane entity does not delete the old source-end mappings and / or does not delete DRBs that are temporarily used for processing forwarded data but are not used by the destination end, based on the received indication information.

[0060] According to one aspect of the present invention, a method for supporting handover is provided, comprising: a source base station central unit control plane entity receiving a handover command message; and the source base station central unit control plane entity sending a bearer context modification request message to a source base station central unit user plane entity, wherein the source base station central unit user plane entity forwards data according to information in the received bearer context modification request message.

[0061] In one example, the handover command message includes E-RAB identification information and data forwarding channel information for data forwarding.

[0062] In one example, the bearer context modification request message includes data forwarding information for switching to the Evolved Universal Terrestrial Radio Access Network (E-UTRAN) or inter-system handover data forwarding information to notify the source base station central unit user plane entity of the data forwarding information.

[0063] In one example, the data forwarding information includes downlink data forwarding information, which includes a transport layer address and a channel identifier. The transport layer address and channel identifier are data forwarding channel information allocated to each E-RAB by the destination base station and received by the source base station central unit control plane entity in the handover command message.

[0064] In one example, the downlink data forwarding information further includes at least one of the following: a list of QoS flow streams that forward data through the data forwarding channel; a Data Radio Bearer (DRB) identifier; and an E-RAB identifier.

[0065] In one example, for inter-system handover, the DRB identifier corresponds to each E-RAB identifier and is either the same as or one-to-one with an E-RAB identifier.

[0066] In one example, the source base station central unit user plane entity determines that it is an inter-system handover based on the data forwarding information for switching to E-UTRAN or the data forwarding information for inter-system handover, and does not include the Service Data Adaptation Protocol (SDAP) header in the forwarded data packets; or for intra-system handover, the source base station central unit user plane entity includes the SDAP header in the data packets forwarded on the channel corresponding to each DRB.

[0067] In one example, the source base station central unit is notified of the data forwarding channel information and the QoS flow information forwarded on each channel by the data radio bearer DRB information to be established and / or the DRB information to be modified in the bearer context modification request message.

[0068] In one example, the bearer context modification request message includes indication information for inter-system handover, and the indication information for inter-system handover may be included in at least one of protocol data unit (PDU) session resource modification information, DRB information to be modified, or DRB information to be established.

[0069] In one example, when configuring the DRB of the source base station central unit user plane entity during PDU session establishment, the source base station central unit control plane entity sends the transport layer address and channel identifier allocated by the destination base station through the DRB data forwarding information in the DRB modification item, and sends the QoS flow of the data forwarded on the channel corresponding to the DRB through the flow mapping information in the DRB modification item. The DRB modification item includes the DRB identifier.

[0070] In one example, when the DRB of the source base station central unit user plane entity is not configured during the PDU session establishment process, the source base station central unit control plane entity sends the transport layer address and channel identifier allocated by the destination base station to the source base station central unit user plane entity by adding DRB data forwarding information to the DRB establishment item, and sends the QoS flow for forwarding data on the channel corresponding to the DRB to the source base station central unit user plane entity through the QoS flow information to be established in the DRB establishment item. The DRB establishment item includes the DRB identifier.

[0071] In one example, the source base station central unit user plane entity knows the QoS flow forwarded through the channel based on the DRB data forwarding information and flow mapping information of each DRB in the received DRB information to be modified, or the source base station central unit user plane entity knows the QoS flow forwarded through the channel based on the DRB data forwarding information and QoS flow information of each DRB in the received DRB information to be established.

[0072] In one example, the source base station central unit user plane entity determines the inter-system handover based on the received inter-system handover indication information and does not include the Service Data Adaptation Protocol (SDAP) header in the forwarded data packets. For intra-system handover, the source base station central unit user plane entity includes the SDAP header in the data packets forwarded on the channel corresponding to each DRB.

[0073] According to one aspect of the present invention, a method for supporting handover is provided, comprising: a user plane entity of a source base station central unit receiving a bearer context modification request message from a control plane entity of a source base station central unit; and the user plane entity of the source base station central unit forwarding data according to information in the received bearer context modification request message.

[0074] In one example, the bearer context modification request message includes data forwarding information for switching to the Evolved Universal Terrestrial Radio Access Network (E-UTRAN) or inter-system handover data forwarding information to notify the source base station central unit user plane entity of the data forwarding information.

[0075] In one example, the data forwarding information includes downlink data forwarding information, which includes a transport layer address and a channel identifier. The transport layer address and channel identifier are data forwarding channel information allocated by the source base station central unit control plane entity to each evolved radio access bearer (E-RAB) in a handover command message.

[0076] In one example, the downlink data forwarding information further includes at least one of the following: a list of QoS flow streams that forward data through the data forwarding channel; a Data Radio Bearer (DRB) identifier; and an E-RAB identifier.

[0077] In one example, for inter-system handover, the DRB identifier corresponds to each E-RAB identifier and is either the same as or one-to-one with an E-RAB identifier.

[0078] In one example, the source base station central unit user plane entity determines that it is an inter-system handover based on the data forwarding information for switching to E-UTRAN or the data forwarding information for inter-system handover, and does not include the Service Data Adaptation Protocol (SDAP) header in the forwarded data packets; or for intra-system handover, the source base station central unit user plane entity includes the SDAP header in the data packets forwarded on the channel corresponding to each DRB.

[0079] In one example, the source base station central unit user plane entity is notified of the data forwarding channel information and the QoS flow information forwarded on each channel by the data radio bearer DRB information to be established and / or the DRB information to be modified in the bearer context modification request message; and the source base station central unit user plane entity forwards data according to the information in the received bearer context modification request message.

[0080] In one example, the bearer context modification request message includes indication information for inter-system handover, and the indication information for inter-system handover may be included in at least one of protocol data unit (PDU) session resource modification information, DRB information to be modified, or DRB information to be established.

[0081] In one example, when configuring the DRB of the source base station central unit user plane entity during PDU session establishment, the source base station central unit control plane entity sends the transport layer address and channel identifier allocated by the destination base station through the DRB data forwarding information in the DRB modification item, and sends the QoS flow of the data forwarded on the channel corresponding to the DRB through the flow mapping information in the DRB modification item. The DRB modification item includes the DRB identifier.

[0082] In one example, when the DRB of the source base station central unit user plane entity is not configured during the PDU session establishment process, the source base station central unit control plane entity sends the transport layer address and channel identifier allocated by the destination base station to the source base station central unit user plane entity by adding DRB data forwarding information to the DRB establishment item, and sends the QoS flow for forwarding data on the channel corresponding to the DRB to the source base station central unit user plane entity through the QoS flow information to be established in the DRB establishment item. The DRB establishment item includes the DRB identifier.

[0083] In one example, the source base station central unit user plane entity knows the QoS flow forwarded through the channel based on the DRB data forwarding information and flow mapping information of each DRB in the received DRB information to be modified, or the source base station central unit user plane entity knows the QoS flow forwarded through the channel based on the DRB data forwarding information and QoS flow information of each DRB in the received DRB information to be established.

[0084] In one example, the source base station central unit user plane entity determines the inter-system handover based on the received inter-system handover indication information and does not include the Service Data Adaptation Protocol (SDAP) header in the forwarded data packets. For intra-system handover, the source base station central unit user plane entity includes the SDAP header in the data packets forwarded on the channel corresponding to each DRB.

[0085] According to one aspect of the present invention, a method for supporting handover is provided, comprising: receiving a message from a destination base station central unit control plane entity; receiving a data packet from a source base station; and discarding a PDCP SN contained in the received data packet according to an indication of the message.

[0086] In one example, discarding the PDCP SN contained in the received data packet means that the destination base station central unit user plane entity does not send the PDCP SN received from the source base station to the UE.

[0087] In one example, after the destination base station central unit user plane entity removes the PDCP SN from the PDCP SDU, the data packet is sent to the UE after processing at the destination end.

[0088] In one example, the message may indicate, either explicitly or implicitly, that the PDCP SN contained in the received data packet should be discarded.

[0089] In one example, explicit indications may include indication information in the message, while implicit indications may include PDCP SN status information not in the message.

[0090] In one example, the indication information may indicate at least one of the following: full configuration or differential configuration; whether the PDCP SN is retained; whether the PDCP SN is restarted; discarding packets containing PDCP Service Data Units (SDUs) with PDCP Sequence Numbers (SNs); or discarding PDCP SNs contained in received packets.

[0091] In one example, according to the message's indication, discarding the PDCP SN contained in the received data packet includes discarding the PDCP SN contained in the received data packet when the indication message indicates at least one of the following: full configuration; PDCP SN not being retained; PDCP restart; and discarding the PDCP SDU containing the PDCP SN or discarding the PDCP SN contained in the received data packet.

[0092] In one example, according to the message's indication, discarding the PDCP SN contained in the received data packet includes discarding the PDCP SN contained in the received data packet when the message's indication includes at least one of the following: no PDCP SN status information was received; no PDCP SN status information for the Data Radio Bearer (DRB) was received; no Bearer Context Modification Request (BFR) message was received; and the received BFR message does not contain PDCP SN status information for the DRB.

[0093] According to another aspect of the present invention, a method for supporting handover is provided, comprising: receiving a handover request message; receiving a sequence number (SN) state transition message or a downlink radio access network (RAN) state transition message; and sending a message to a destination base station central unit user plane entity, wherein the destination base station central unit user plane entity, according to the instruction of the message, discards a received data packet containing a Packet Data Convergence Protocol (PDCP) sequence number (SN).

[0094] According to another aspect of the present invention, a method for supporting handover is provided, comprising: a destination base station central unit user plane entity receiving indication information sent by a destination base station central unit control plane entity; the destination base station central unit user plane entity receiving a data packet forwarded from a source base station or from a source base station via a core network; and the destination base station central unit user plane entity receiving the indication information from the destination base station central unit control plane entity, wherein the destination base station central unit user plane entity discards the PDCP SN contained in the received data packet.

[0095] In one example, if the indication information indicates full configuration or that the PDCP SN is not retained or that PDCP is restarted, or indicates that PDCP SDUs containing the PDCP SN are discarded, or indicates that the PDCP SN is discarded, the destination base station central unit user plane entity discards the PDCP SN contained in the received data packet.

[0096] According to another aspect of the present invention, a method for supporting handover is provided, comprising: a destination base station central unit user plane entity receiving a message sent by a destination base station central unit control plane entity; the destination base station central unit user plane entity receiving a data packet forwarded from a source base station or from a source base station via a core network; and if no PDCPSN status information is received, the destination base station central unit user plane entity discards the PDCP SN contained in the received data packet. Figure 7 (New plan)

[0097] According to another aspect of the present invention, a method for supporting handover is provided, comprising: a destination base station receiving a handover request message; the destination base station sending information about whether the handover is fully configured or differentially configured to a source base station; and the source base station forwarding data packets that do not contain a PDCP SN to the destination base station based on the information.

[0098] In one example, the information regarding whether the configuration is full or differential can be at least one of the following: whether the PDCPSN status is retained, whether the PDCP SN is restarted, whether the PDCP SN is not needed, or whether data packets containing the PDCP SN are not needed.

[0099] In one example, if the source base station supports an architecture with separate user plane and control plane, the source base station central unit control plane entity can notify the source base station central unit user plane entity, either explicitly or implicitly, that the PDCP SN is not included in the forwarded data packets.

[0100] In one example, the indication information may indicate at least one of the following: full configuration or differential configuration; whether the PDCPSN state is preserved; whether only new data is sent; whether a PDCP SDU containing the PDCP SN is sent; whether a PDCP data packet sent to the User Equipment (UE) without acknowledgment by the UE is sent; whether the PDCP SN is included in the forwarded data packet; and whether only PDCP SDUs without the PDCP SN are sent.

[0101] According to another aspect of the present invention, a method for supporting handover is provided, comprising: a destination base station or a destination base station central unit control plane entity receiving a handover request message; the destination base station or the destination base station central unit control plane entity sending information on whether it is a full configuration or a Delta configuration to a source base station or a source base station central unit control plane entity; and the source base station forwarding data packets that do not contain a PDCP SN to the destination base station.

[0102] According to another aspect of the present invention, a method for supporting handover is provided, comprising: receiving a handover-related message; and indicating information for data forwarding to a source base station central unit user plane entity, wherein the source base station central unit user plane entity forwards a PDCPSDU that does not contain a PDCP SN to a destination base station based on the information for data forwarding.

[0103] In one example, the source base station central unit control plane entity can indicate information for data forwarding to the source base station central unit user plane entity through explicit or implicit indication methods.

[0104] In one example, when the source base station central unit user plane entity forwards a PDCP SDU that does not contain a PDCP SN to the destination base station when it is determined, based on the indication information, that at least one of the following is true: the PDCP SN state is not retained; only new data is sent; no PDCP SDU containing a PDCP SN is sent; no PDCP data packets sent to the user equipment UE that the UE has not acknowledged are forwarded; and only PDCP SDUs that do not contain a PDCP SN are sent.

[0105] In one example, if the source base station central unit control plane entity requests modification or establishment of a DRB, and the source base station central unit control plane entity does not request PDCP SN status information, then the source base station central unit user plane entity forwards a PDCP SDU that does not contain a PDCP SN to the destination base station.

[0106] According to another aspect of the present invention, a method for supporting handover is provided, comprising: a source base station central unit control plane entity receiving a handover command message or a handover request confirmation message; the source base station central unit control plane entity informing the source base station central unit user plane entity of data forwarding information in an explicit or implicit manner; and the source base station central unit user plane entity forwarding data packets that do not contain a PDCP SN to the destination base station.

[0107] According to another aspect of the present invention, a method for supporting handover is provided, comprising: receiving information indicating data forwarding; and based on the information for data forwarding, not sending a PDCP service data unit (SDU) containing a Packet Data Convergence Protocol (PDCP) SN to a destination base station.

[0108] In one example, information indicating the data forwarding can be received through either an explicit or implicit indication method.

[0109] In one example, when the source base station central unit user plane entity forwards a PDCP SDU that does not contain a PDCP SN to the destination base station when at least one of the following is determined according to the indication information: the PDCP SN state is not retained; only new data is sent; no PDCP SDU containing a PDCP SN is sent; no PDCP data packets sent to the user equipment UE that the UE has not acknowledged are sent; no PDCP SN is sent; and only PDCP SDUs that do not contain a PDCP SN are sent.

[0110] In one example, by not requesting PDCP SN status information, the source base station central unit user plane entity knows that the PDCP SN is not retained or that the source base station central unit control plane entity has not sent PDCP SN status information to the destination base station, and forwards PDCP SDUs that do not contain PDCP SN to the destination base station.

[0111] According to another aspect of the present invention, a method for supporting handover is provided, comprising: a source base station central unit user plane entity receiving data forwarding information and channel information for data forwarding sent by a source base station central unit control plane entity; and the source base station central unit control plane entity forwarding data packets that do not contain a PDCP SN to a destination base station.

[0112] According to another aspect of the present invention, a device supporting switching is provided, comprising: a transceiver for transmitting and receiving signals; a processor; and a memory storing instructions executable by the processor, which, when executed by the processor, cause the processor to perform any of the foregoing methods.

[0113] Technical effect

[0114] According to embodiments of the present invention, the problem of coordinated operation between the source base station and the destination base station during handover can be solved. Specifically, when the source base station and / or the destination base station supports the separation of the control plane and data plane, it ensures that the source base station central unit control plane entity, the source base station central unit user plane entity, the destination base station central unit control plane entity, and / or the destination base station central unit user plane entity can operate in complete coordination.

[0115] Furthermore, the switching support method and device according to embodiments of the present invention can reduce data loss, reduce data interruption time, avoid sending useless data packets over the air interface, improve data forwarding efficiency, and ensure business continuity. Attached Figure Description

[0116] The invention will be more readily understood from the following detailed description with reference to the accompanying drawings, wherein like reference numerals designate units of the same structure, and wherein:

[0117] Figure 1 This is an exemplary system architecture for System Architecture Evolution (SAE);

[0118] Figure 2 These are exemplary system architectures based on various embodiments of this disclosure;

[0119] Figure 3 This is an exemplary flowchart illustrating a method for supporting switching according to an embodiment of the present invention;

[0120] Figure 4 This is an exemplary flowchart illustrating a method for supporting switching according to an embodiment of the present invention;

[0121] Figure 5 This is an exemplary flowchart illustrating a method for supporting switching according to an embodiment of the present invention;

[0122] Figure 6 This is an exemplary flowchart illustrating a method for supporting switching according to an embodiment of the present invention;

[0123] Figure 7 This is an exemplary flowchart illustrating a method for supporting switching according to an embodiment of the present invention;

[0124] Figure 8 This is an exemplary flowchart illustrating a method for supporting switching according to an embodiment of the present invention;

[0125] Figure 9 This is an exemplary flowchart illustrating a method for supporting switching according to an embodiment of the present invention;

[0126] Figure 10 This is an exemplary flowchart illustrating a method for supporting switching according to an embodiment of the present invention;

[0127] Figure 11 This is an exemplary flowchart illustrating a method for supporting switching according to an embodiment of the present invention;

[0128] Figure 12 This is an exemplary flowchart illustrating a method for supporting switching according to an embodiment of the present invention;

[0129] Figure 13 This is an exemplary flowchart illustrating a method for supporting switching according to an embodiment of the present invention;

[0130] Figure 14 This is an exemplary flowchart illustrating a method for supporting switching according to an embodiment of the present invention;

[0131] Figure 15 An exemplary flowchart of a method for supporting switching according to an embodiment of the present invention is shown;

[0132] Figure 16 This is an exemplary flowchart illustrating a method for supporting switching according to an embodiment of the present invention;

[0133] Figure 17 This is an exemplary flowchart illustrating a method for supporting switching according to an embodiment of the present invention;

[0134] Figure 18 An exemplary flowchart of a method for supporting switching according to an embodiment of the present invention is shown;

[0135] Figure 19 This is an exemplary flowchart illustrating a method for supporting switching according to an embodiment of the present invention;

[0136] Figure 20 This is an exemplary flowchart illustrating a method for supporting switching according to an embodiment of the present invention;

[0137] Figure 21 An exemplary flowchart of a method for supporting switching according to an embodiment of the present invention is shown;

[0138] Figure 22 This is an exemplary flowchart illustrating a method for supporting switching according to an embodiment of the present invention;

[0139] Figure 23 This is an exemplary flowchart illustrating a method for supporting switching according to an embodiment of the present invention;

[0140] Figure 24 An exemplary flowchart of a method for supporting switching according to an embodiment of the present invention is shown;

[0141] Figure 25 An exemplary flowchart of a method for supporting switching according to an embodiment of the present invention is shown;

[0142] Figure 26 An exemplary flowchart of a method for supporting switching according to an embodiment of the present invention is shown;

[0143] Figure 27 An exemplary flowchart of a method for supporting switching according to an embodiment of the present invention is shown;

[0144] Figure 28 An exemplary flowchart of a method for supporting switching according to an embodiment of the present invention is shown;

[0145] Figure 29An exemplary flowchart of a method for supporting switching according to an embodiment of the present invention is shown; and

[0146] Figure 30 A schematic block diagram of a device supporting switching according to an embodiment of the present invention is shown. Detailed Implementation

[0147] The following discussion Figures 1 to 8 The various embodiments used to describe the principles of this disclosure in this patent document are for illustrative purposes only and should not be construed as limiting the scope of this disclosure in any way. Those skilled in the art will understand that the principles of this disclosure can be implemented in any suitably arranged system or device.

[0148] Figure 1 This is an exemplary system architecture 100 of System Architecture Evolution (SAE). User Equipment (UE) 101 is a terminal device used to receive data. Evolved Universal Terrestrial Radio Access Network (E-UTRAN) 102 is a radio access network, including macro base stations (eNodeB / NodeB) that provide the UE with an interface to access the wireless network. Mobility Management Entity (MME) 103 is responsible for managing the UE's mobility context, session context, and security information. Serving Gateway (SGW) 104 primarily provides user plane functions; MME 103 and SGW 104 may reside in the same physical entity. Packet Data Network Gateway (PGW) 105 is responsible for functions such as charging and lawful interception, and may also reside in the same physical entity as SGW 104. Policy and Charging Rules Function Entity (PCRF) 106 provides Quality of Service (QoS) policies and charging criteria. Universal Packet Radio Service Support Node (SGSN) 108 is a network node device in the Universal Mobile Telecommunications System (UMTS) that provides routing for data transmission. The Home Subscriber Server (HSS) 109 is the UE's home subsystem, responsible for protecting user information including the UE's current location, the address of the serving node, user security information, and the UE's packet data context.

[0149] Figure 2 This is an exemplary system architecture 200 according to various embodiments of the present disclosure. Other embodiments of the system architecture 200 can be used without departing from the scope of the present disclosure.

[0150] User Equipment (UE) 201 is the terminal equipment used to receive data. Next-Generation Radio Access Network (NG-RAN) 202 is the radio access network, which includes base stations (gNBs or eNBs connected to the 5G core network 5GC; eNBs connected to the 5GC are also called ng-gNBs) that provide the UE with access to the wireless network interface. Access Control and Mobility Management Function Entity (AMF) 203 is responsible for managing the UE's mobility context and security information. User Plane Function Entity (UPF) 204 mainly provides user plane functions. Session Management Function Entity (SMF) 205 is responsible for session management. Data Network (DN) 206 includes services such as operator services, Internet access, and third-party services. Base stations can be divided into base station central units and base station distribution units. Base station central units can be divided into base station central unit control plane entities and base station central unit user plane entities. Alternatively, base stations can be divided into base station control plane entities and base station user plane entities.

[0151] Exemplary embodiments of this disclosure are further described below with reference to the accompanying drawings.

[0152] The text and accompanying drawings are provided by way of example only to aid in understanding this disclosure. They should not be construed as limiting the scope of this disclosure in any way. Although certain embodiments and examples have been provided, it will be apparent to those skilled in the art, based on the content disclosed herein, that changes may be made to the illustrated embodiments and examples without departing from the scope of this disclosure.

[0153] The base station central unit control plane entity in this disclosure embodiment can also be referred to as the base station control plane entity, which refers to a logical entity in the base station that includes the Radio Resource Control (RRC) and Packet Data Convergence Protocol (PDCP) control plane portions.

[0154] The base station central unit user plane entity in this embodiment can also be referred to as the base station user plane entity, which refers to a logical entity in the base station that includes the user plane function portion of the Packet Data Convergence Protocol (PDCP). The logical entity may also include the functionality of the Service Data Adaptation Protocol (SDAP).

[0155] During handover, the source base station can send the UE's configuration information at the source base station to the destination base station. The destination base station decides whether to use full configuration or delta configuration. The source base station is unaware of whether the destination base station has decided on full or delta configuration. For Data Radio Bearers (DRBs) that the destination base station receives downlink data forwarding from, the source base station forwards data packets that the UE has not acknowledged, as well as fresh data packets, to the destination base station. In the case of a separate control plane and user plane architecture at the destination base station, the control plane entity of the destination base station decides whether to use full or delta configuration, while the user plane entity of the destination base station is unaware of whether full or delta configuration is used for handover. The user plane entity of the destination base station will send all forwarded data packets received from the source base station to the UE. For full configuration, the PDCP sequence number (SN) status is not saved. Therefore, sending data packets forwarded by the source base station to the UE that the UE has not acknowledged is useless, or the SN contained in the forwarded data packets is also useless, wasting air interface resources and affecting data re-ordering at the UE. This invention provides two methods to solve this problem. include:

[0156] Method 1: The destination base station central unit control plane entity sends indication information to the destination base station central unit user plane entity, thereby the destination base station central unit user plane entity sends appropriate data to the UE according to the indication information. Specifically, as follows... Figures 3 to 8 The method described in [the document / article].

[0157] Method 2: Upon receiving the handover request message, the destination base station sends information regarding whether it uses a full configuration or differential configuration, or whether the PDCP SN state should be retained, to the source base station. The source base station then forwards data to the destination base station based on this information. In the case where the source base station has a separate control plane and user plane architecture, the source base station's central unit control plane entity sends indication information to its central unit user plane entity, which then forwards data to the destination base station based on the received information. Specifically... Figures 9 to 14 The method described in [the document / article].

[0158] During handover, the source base station can send the UE's configuration information at the source base station to the destination base station. This configuration information includes the source base station's DRB configuration information. The configuration information may also include the mapping of QoS flow to the DRB. The destination base station decides whether to use the same DRB configuration and / or the same QoS flow to DRB mapping as the source base station. If the destination base station decides to use a different DRB configuration and / or a different QoS flow to DRB mapping than the source base station, to ensure no data loss during handover, the destination base station can temporarily configure the old DRB and / or the same QoS flow to DRB mapping as the source base station to handle data forwarded by the source base station. For new data received from the core network, the destination base station uses the new DRB and / or the QoS flow to DRB mapping determined by the destination. In the case of a destination base station with a separate control plane and user plane architecture, the destination base station's central unit control plane entity determines the DRB configuration and the QoS flow to DRB mapping. The message sent by the destination base station central unit control plane entity to the destination base station central unit user plane entity includes the DRB to be established or modified and the QoS Flow(s) mapped on the DRB. In the current mechanism, the destination base station central unit user plane entity only receives one set of QoS Flow to DRB mapping information; it does not know whether the mapping information is a new mapping determined by the destination or a mapping from the source. The destination base station central unit user plane entity receives data forwarded from the source base station and new data received from the core network. In the above scenario, using the received QoS Flow(s) mapped on the DRB to process the forwarded data from the source base station and the new data received from the core network can lead to data loss, or the destination QoS Flow to DRB mapping may not be used to process the new data received from the core network. This invention... Figure 15 , Figure 18 , Figure 21 and Figure 24 Four methods are given to solve this problem. Figure 25 Methods for releasing the old DRB configured on the base station distribution unit (gNB-DU) are presented among these methods.

[0159] For UE handover from a 5G system (5GS) to Evolved Packet System (EPS), the source NG-RAN node determines the QoS flow to DRB mapping during PDU session establishment. The source base station central unit control plane entity sends the DRB information to be established and the QoS flow information mapped on the DRB to the source base station central unit user plane entity. The source base station central unit user plane entity processes the data received from the core network according to the mapping. For direct data forwarding from the source NG-RAN to the destination base station, a channel for each E-RAB (Evolved Radio Access Bearer) is established between the source NG-RAN node and the destination base station for data forwarding. The destination base station allocates the channel for each E-RAB and sends it to the source NG-RAN node. The E-RABs mapped by the QoS flow are determined by the core network. If the number of E-RABs mapped by the QoS flow is greater than the number of DRBs determined by the NG-RAN, the source base station central unit control plane entity cannot send the corresponding channel information for each E-RAB to the source base station central unit user plane entity through the existing bearer context modification request message.

[0160] In addition, for inter-system handover from 5GS to EPS, the data packet header forwarded by the source base station does not include the SDAP header. However, for intra-system handover of 5GS, the data forwarded on the DRB channel may include the SDAP header. Data forwarding is done by the source base station central unit user plane entity forwarding data to the destination base station. In the existing technology, the source base station central unit user plane entity does not know when the SDAP header is included or when it is not included in the forwarded data packet. Figures 24 to 25 Two methods for solving the above problem are given.

[0161] Figure 3 This is an exemplary flowchart illustrating a method 300 for supporting handover according to an embodiment of the present invention. The method 300 can be used for intra-system handover or inter-system handover, and can be executed on the user plane entity side of the destination base station central unit.

[0162] like Figure 3 As shown, in method 300, in step S301, a message is received from the control plane entity of the destination base station central unit.

[0163] In step S302, data packets are received from the source base station.

[0164] In step S303, according to the instruction of the message, the PDCP Service Data Unit (SDU) containing the Packet Data Convergence Protocol (PDCP) Sequence Number (SN) in the received data packet is discarded.

[0165] Alternatively, in step S303, according to the instruction of the message, the PDCP SN contained in the received data packet is discarded. Discarding the PDCP SN contained in the received data packet means that the destination base station central unit user plane entity does not send the PDCP SN received from the source base station to the UE. The data packet can be sent to the UE after the destination base station central unit user plane entity removes the PDCP SN from the PDCP SDU, following processing at the destination end.

[0166] According to embodiments of the present invention, the message can indicate, through an explicit indication method or an implicit indication method, to discard a PDCP SDU containing a PDCP SN in a received data packet, or to discard a PDCP SN contained in a received data packet. Explicit indication may include indication information in the message, while implicit indication may include the absence of PDCP SN status information in the message.

[0167] Specifically, in one example of the indication method, in step S301, the message received from the destination base station central unit control plane entity includes indication information. The indication information may indicate at least one of the following: full configuration or delta configuration; whether the PDCP SN is reserved; whether the PDCP SN is restarted; discarding a data packet containing a PDCP service data unit (SDU) with a PDCP sequence number (SN) or discarding the PDCP SN contained in a received data packet. PDCP restart refers to PDCP deletion and then addition.

[0168] The Bearer Context Modification Request message can be used to send indication information from the destination base station central unit control plane entity to the destination base station central unit user plane entity. The Bearer Context Modification Request message is used for bearer establishment or bearer modification.

[0169] The target base station central unit user plane entity stores the received information.

[0170] In one example, in step S302, the destination base station central unit user plane entity receives data packets from the source base station or forwarded by the source base station through the core network. If the source base station also supports a user plane and control plane separation architecture, the data is received from the source base station central unit user plane entity.

[0171] In one example, in step S303, when the indication information indicates at least one of the following, the target base station central unit user plane entity discards the PDCP SDU containing the PDCP SN or discards the PDCP SN contained in the received data packet: full configuration; PDCP SN not retained; PDCP restart; and discards the PDCP SDU containing the PDCP SN or discards the PDCP SN contained in the received data packet.

[0172] In other words, the destination base station central unit user plane entity discards PDCP SDUs containing PDCP SNs that the source base station attempts to send to the user equipment (UE). The destination base station central unit user plane entity identifies and discards these packets based on the presence of an SN in the forwarded General Packet Radio Service (GPRS) Channel Protocol (GTP) User Plane (GTP-U) packets. Alternatively, the destination base station central unit user plane entity discards the PDCP SN from the PDCP SDUs received from the source base station.

[0173] On the other hand, in one example of the implicit indication method, in step S303, when the indication of the message includes at least one of the following, the target base station central unit user plane entity discards the PDCP SDU containing the PDCP SN or discards the PDCP SN contained in the received data packet: no PDCP SN status information was received; no PDCP SN status information of the data radio bearer DRB was received; no bearer context modification request message was received; and no PDCP SN status information of the DRB was included in the received bearer context modification request message.

[0174] Specifically, if the destination base station central unit user plane entity does not receive PDCP SN status information in step S301, the destination base station central unit user plane entity discards the PDCP SDU containing the PDCP SN forwarded from the source base station, and it is not sent to the UE. Alternatively, if the destination base station central unit user plane entity does not receive PDCP SN status information for the data radio bearer (DRB) in step S301, the destination base station central unit user plane entity discards the PDCP SDU containing the PDCP SN forwarded from the source base station, and it is not sent to the UE.

[0175] In other words, the destination base station central unit user plane entity discards PDCP SDUs containing PDCPSNs that the source base station attempts to send to the UE. The destination base station central unit user plane entity identifies these packets based on the presence of the SN in the forwarded GTP-U packets and discards them accordingly.

[0176] Alternatively, if the destination base station central unit user plane entity does not receive the bearer context modification request message, the destination base station central unit user plane entity discards the received PDCPSDU containing the PDCP SN forwarded from the source base station. Or, if the bearer context modification request message received by the destination base station central unit user plane entity does not contain the PDCP SN status information of a certain DRB, the destination base station central unit user plane entity discards the received PDCP SDU containing the PDCP SN of the DRB forwarded from the source base station.

[0177] Specifically, in the example of discarding the PDCP SN contained in the received data packet, if the destination base station central unit user plane entity does not receive PDCP SN status information in step S301, the destination base station central unit user plane entity discards the PDCP SN contained in the received data packet, and the PDCP SN received from the source base station is not sent to the UE. Alternatively, if the destination base station central unit user plane entity does not receive the PDCP SN status information of the data radio bearer (DRB) in step S301, the destination base station central unit user plane entity discards the PDCP SN contained in the received data packet, and the PDCP SN received from the source base station is not sent to the UE.

[0178] Alternatively, if the destination base station central unit user plane entity does not receive the bearer context modification request message, the destination base station central unit user plane entity discards the PDCP SN contained in the received data packet, and the PDCP SN received from the source base station is not sent to the UE. Or, if the bearer context modification request message received by the destination base station central unit user plane entity does not contain the PDCP SN status information of a certain DRB, the destination base station central unit user plane entity discards the PDCP SN contained in the received data packet, and the PDCP SN received from the source base station is not sent to the UE.

[0179] The target base station central unit user plane entity adds the PDCP SN to the PDCP SDU with the PDCP SN removed, and after processing by the PDCP layer and other layers, sends it to the UE.

[0180] Subsequently, the user plane entity of the destination base station central unit adds the PDCP SN to the received PDCP SDU that does not have a PDCP SN, and after processing by the PDCP layer and other layers, sends it to the UE.

[0181] PDCP SDUs without a PDCP SN can be fresh data.

[0182] According to an embodiment of the present invention, the user plane entity of the destination base station central unit can discard data that does not need to be sent to the UE or PDCP SN that does not need to be sent to the UE, and only send the required data to the UE, thereby improving the efficiency of data transmission and avoiding waste of air interface resources.

[0183] Figure 4 This is an exemplary flowchart illustrating a method 400 for supporting handover according to an embodiment of the present invention. The method 400 can be used for intra-system handover or inter-system handover, and can be executed on the control plane entity side of the destination base station central unit.

[0184] like Figure 4 As shown, in method 400, in step S401, a handover request message is received.

[0185] In step S402, receive a sequence number (SN) state transition message or a downlink radio access network (RAN) state transition message.

[0186] In step S403, a message is sent to the user plane entity of the destination base station central unit, wherein the user plane entity of the destination base station central unit discards the PDCP service data unit SDU containing the PDCP sequence number SN in the received data packet according to the instruction of the message.

[0187] Alternatively, in step S403, a message is sent to the target base station central unit user plane entity, wherein the target base station central unit user plane entity discards the PDCP SN contained in the received data packet according to the instruction of the message.

[0188] In one example, in step S401, the destination base station central unit control plane entity can receive a handover request message. This handover request message can be received from the source base station or the source base station central unit control plane entity, or from the core network. The handover request message received from the source base station or the source base station central unit control plane entity is an Xn Application Protocol (AP) message or other inter-base station messages. Furthermore, the handover request message received from the core network is a Next Generation Application Protocol (NGAP) message or other inter-base station and core network messages.

[0189] The handover request message received from the core network contains the handover type, which can include intra-system handover or inter-system handover.

[0190] In addition, the handover request message received from the source base station or the source base station central unit control plane entity indicates by default that the handover type is intra-system handover.

[0191] The choice between full configuration and differential configuration can be determined by the central unit control plane entity of the destination base station.

[0192] In one example, in step S402, the destination base station central unit control plane entity receives an SN state transition message or a downlink RAN ​​state transition message. The SN state transition message may be received from the source base station or the source base station central unit control plane entity. The SN state transition message received from the source base station or the source base station central unit control plane entity may be an Xn application protocol (AP) message or other inter-base station messages. The downlink RAN ​​state transition message may be received from the core network.

[0193] As previously described, in step S403, either an explicit indication method or an implicit indication method can be used to indicate that a PDCP SDU containing a PDCP SN in a received data packet is discarded, or that a PDCP SN contained in a received data packet is discarded. Explicit indication may include indication information in the message, and implicit indication may include the absence of PDCP SN status information in the message.

[0194] The Bearer Context Modification Request message can be used to send indication information from the destination base station central unit control plane entity to the destination base station central unit user plane entity. The Bearer Context Modification Request message is used for bearer establishment or bearer modification.

[0195] Regarding implicit indications, the destination base station central unit control plane entity can determine whether to include PDCPSN status information in the bearer context modification request message sent to the destination base station central unit user plane entity for each DRB to be modified or established. When the destination base station central unit control plane entity decides to use full configuration for a certain DRB, it will not include PDCPSN status information for that DRB in the bearer context modification request message sent to the destination base station central unit user plane entity.

[0196] The explicit or implicit indication method is the same as the one mentioned above. Figure 3 The method described is similar to 300, so it will not be repeated here.

[0197] When a handover is an inter-system handover, the destination base station central unit control plane entity sends an indication message to the destination base station central unit user plane entity. The destination base station central unit control plane entity determines whether it is an inter-system handover based on the handover type contained in the received handover request message.

[0198] It should be noted that the handover preparation message for inter-system handover is sent through the core network, so for inter-system handover, the handover request message can only be received from the core network.

[0199] In another example, the destination base station central unit control plane entity sends an indication message to the destination base station central unit user plane entity when deciding to use the full configuration.

[0200] For intra-system handover, the destination base station central unit control plane entity determines whether to use full configuration or differential configuration. Inter-system handover uses full configuration.

[0201] According to an embodiment of the present invention, the destination base station central unit control plane entity enables the destination base station central unit user plane entity to know how to process the data forwarded from the source base station, thereby discarding data that does not need to be sent to the UE or PDCP SN that does not need to be sent to the UE, and only sending the required data to the UE, thereby improving the efficiency of data forwarding and avoiding waste of air interface resources.

[0202] Figure 5 This is an exemplary flowchart illustrating a method 500 for supporting handover according to an embodiment of the present invention. The method 500 can be used for intra-system handover or inter-system handover. The method includes the following steps.

[0203] In step S501, the user plane entity of the destination base station central unit receives indication information sent by the control plane entity of the destination base station central unit. The indication information may be information regarding full configuration or delta configuration, information regarding whether the PDCP SN is reserved, information regarding whether PDCP should be restarted, information indicating the discarding of data packets containing PDCP service data units (SDUs) with PDCP sequence numbers (SNs), or information indicating the discarding of PDCP SNs. This indication information can be sent from the control plane entity of the destination base station central unit to the user plane entity of the destination base station central unit via a bearer context modification request message. PDCP restart refers to the deletion and re-addition of PDCP.

[0204] The target base station central unit user plane entity stores the received information.

[0205] In step S502, the user plane entity of the destination base station central unit receives data packets from the source base station or forwarded by the source base station through the core network. If the source base station also supports a user plane and control plane separation architecture, the data is received from the user plane entity of the source base station central unit.

[0206] In step S503, the destination base station central unit user plane entity receives the indication information from the destination base station central unit control plane entity. If the indication information indicates full configuration, or that the PDCP SN is not retained, or that PDCP is restarted, or indicates that PDCP SDUs containing the PDCP SN are discarded, or indicates that the PDCP SN is discarded, the destination base station central unit user plane entity discards the PDCP SDUs containing the PDCP SN or discards the PDCP SN contained in the received data packets. That is, the destination base station central unit user plane entity discards the PDCP SDUs that the source base station attempts to send to the UE. The destination base station central unit user plane entity identifies these data packets and discards them based on the presence of an SN in the forwarded General Packet Radio Service (GPRS) Channel Protocol (GTP) User Plane (GTP-U) data packets. Alternatively, the destination base station central unit user plane entity discards the PDCP SN contained in the received data packets, and the PDCP SN received from the source base station is not sent to the UE. The destination base station central unit user plane entity will send the PDCP SDU with the PDCP SN removed, after processing by the PDCP layer and other layers, to the UE.

[0207] The destination base station central unit user plane entity adds the PDCP SN to the received PDCP SDUs without a PDCP SN, processes them through the PDCP layer and other layers, and then sends them to the UE. The PDCP SDUs without a PDCP SN can be fresh data.

[0208] This concludes the description of the handover support method 500 of the present invention. Through this method, the user plane entity of the base station central unit can discard data that does not need to be sent to the UE, thereby improving data transmission efficiency and avoiding waste of air interface resources.

[0209] Figure 6 This is an exemplary flowchart illustrating a method 600 for supporting handover according to an embodiment of the present invention. The method 600 can be used for intra-system handover or inter-system handover. The method includes the following steps.

[0210] In step S601, the destination base station central unit control plane entity receives a handover request message. The handover request message is received from the source base station or its central unit control plane entity, or from the core network. The handover request message received from the source base station or its central unit control plane entity is an Xn Application Protocol (AP) message or other inter-base station message. The handover request message received from the core network is an NGAP message or other inter-base station and core network message.

[0211] The handover request message received from the core network contains a handover type.

[0212] The target base station central unit control plane entity determines whether to use full configuration or differential configuration.

[0213] In step S602, the destination base station central unit control plane entity receives an SN state transition message or a downlink RAN ​​state transition message. The SN state transition message is received from the source base station or the source base station central unit control plane entity. The message received from the source base station or the source base station central unit control plane entity is an Xn Application Protocol (AP) message or other inter-base station message. The downlink RAN ​​state transition message is received from the core network. The handover request message received from the core network is an NGAP message or other inter-base station and core network message.

[0214] In step S603, the control plane entity of the destination base station central unit sends indication information to the user plane entity of the destination base station central unit. The indication information is the same as that in step S501, and will not be described again here.

[0215] The target base station central unit control plane entity sends the indication information to the target base station central unit user plane entity through a bearer context modification request message.

[0216] When the handover is an inter-system handover, the destination base station central unit control plane entity sends the indication information to the destination base station central unit user plane entity. The destination base station central unit control plane entity determines whether it is an inter-system handover based on the handover type contained in the received handover request message. It should be noted that the handover preparation message for inter-system handover is sent through the core network, so for inter-system handover, the handover request message can only be received from the core network. Alternatively, the destination base station central unit control plane entity sends the indication information to the destination base station central unit user plane entity when deciding to use full configuration. For intra-system handover, the destination base station central unit control plane entity decides whether to use full configuration or differential configuration. Inter-system handover uses full configuration.

[0217] This concludes the description of the handover support method 600 of the present invention. Through this method, the destination base station central unit control plane entity enables the destination base station central unit user plane entity to know how to process the data received forwarded from the source base station, thereby discarding data that does not need to be sent to the UE or PDCP SNs that do not need to be sent to the UE, improving data forwarding efficiency and avoiding waste of air interface resources.

[0218] Figure 7 This is an exemplary flowchart illustrating a method 700 for supporting handover according to an embodiment of the present invention. The method 700 can be used for intra-system handover or inter-system handover. The method includes the following steps.

[0219] In step S701, the user plane entity of the destination base station central unit receives a message sent by the control plane entity of the destination base station central unit. The message is used for bearer establishment or bearer modification. The message may be a bearer modification request message.

[0220] The target base station central unit user plane entity stores the received information.

[0221] In step S702, the user plane entity of the destination base station central unit receives data packets from the source base station or forwarded by the source base station through the core network. If the source base station also supports a user plane and control plane separation architecture, the data is received from the user plane entity of the source base station central unit.

[0222] In step S703, if the destination base station central unit user plane entity did not receive PDCP SN status information in step S701, the destination base station central unit user plane entity discards the PDCP SDUs containing the PDCP SN forwarded from the source base station, and the data packets are not sent to the UE. Alternatively, for Data Radio Bearers (DRBs) for which PDCP SN status information was not received in step S701, the destination base station central unit user plane entity discards the PDCP SDUs containing the PDCP SN forwarded from the source base station, and the data packets are not sent to the UE. That is, the destination base station central unit user plane entity discards PDCP SDUs that the source base station attempts to send to the UE. The destination base station central unit user plane entity identifies these data packets and discards them based on the presence of an SN in the forwarded GTP-U data packets. Alternatively, if the destination base station central unit user plane entity did not receive PDCP SN status information, the destination base station central unit user plane entity discards the PDCP SDUs containing the PDCP SN forwarded from the source base station. Alternatively, if the destination base station central unit user plane entity does not receive the bearer context modification request message, the destination base station central unit user plane entity discards the received PDCPSDUs containing the PDCP SN forwarded from the source base station. Alternatively, if the bearer context modification request message received by the destination base station central unit user plane entity does not contain the PDCP SN status information of a certain DRB, the destination base station central unit user plane entity discards the received PDCP SDUs containing the PDCP SN of the DRB forwarded from the source base station.

[0223] If the destination base station central unit user plane entity does not receive PDCP SN status information in step S701, the destination base station central unit user plane entity removes the PDCP SN contained in the received data packet, and the PDCP SN received from the source base station is not sent to the UE. Alternatively, for a Data Radio Bearer (DRB) for which PDCP SN status information is not received in step S701, the destination base station central unit user plane entity removes the PDCP SN contained in the received data packet, and the PDCP SN received from the source base station is not sent to the UE. Or, if the destination base station central unit user plane entity does not receive a Bearer Context Modification Request message, the destination base station central unit user plane entity removes the PDCP SN contained in the received data packet, and the PDCP SN received from the source base station is not sent to the UE. Or, if the Bearer Context Modification Request message received by the destination base station central unit user plane entity does not contain PDCP SN status information for a certain DRB, the destination base station central unit user plane entity removes the PDCP SN contained in the received data packet, and the PDCP SN received from the source base station is not sent to the UE.

[0224] The target base station central unit user plane entity adds a PDCP SN to PDCP SDUs that do not have a PDCP SN, processes them through the PDCP layer and other layers, and then sends them to the UE. The PDCP SDUs without a PDCP SN can be fresh data.

[0225] This concludes the description of the handover support method 700 of the present invention. Through this method, the user plane entity of the target base station central unit can discard data that does not need to be sent to the UE or PDCP SNs that do not need to be sent to the UE, thereby improving data transmission efficiency and avoiding waste of air interface resources.

[0226] Figure 8 This is an exemplary flowchart illustrating a method 800 for supporting handover according to an embodiment of the present invention. The method 800 can be used for intra-system handover or inter-system handover. The method includes the following steps.

[0227] Steps S801 to S802 are the same as steps S601 to S602, and detailed technical descriptions are omitted here.

[0228] In step S803, the destination base station central unit control plane entity decides whether to send a bearer context modification request message to the destination base station central unit user plane entity, or the destination base station central unit control plane entity decides whether the bearer context modification request message sent to the destination base station central unit user plane entity contains PDCP SN status information for each DRB to be modified or established.

[0229] When the handover is an inter-system handover, the destination base station central unit control plane entity may choose not to send a bearer context modification request message to the destination base station central unit user plane entity, or the bearer context modification request message sent to the destination base station central unit user plane entity may not contain PDCP SN status information. The destination base station central unit control plane entity determines whether it is an inter-system handover based on the handover type contained in the received handover request message. It should be noted that the handover preparation message for inter-system handover is sent through the core network, so for inter-system handover, the handover request message can only be received from the core network.

[0230] Alternatively, the destination base station central unit control plane entity may not send a bearer context modification request message to the destination base station central unit user plane entity when deciding to use full configuration. For intra-system handover, the destination base station central unit control plane entity decides whether to use full configuration or differential configuration. Inter-system handover uses full configuration.

[0231] Alternatively, when the destination base station central unit control plane entity decides to use full configuration for a certain DRB, the bearer context modification request message sent to the destination base station central unit user plane entity does not include PDCP SN status information for the DRB.

[0232] This concludes the description of the handover support method 800 of the present invention. Through this method, the destination base station central unit control plane entity enables the destination base station central unit user plane entity to know how to process received forwarded data, thereby discarding data that does not need to be sent to the UE or PDCP SNs that do not need to be sent to the UE, improving data forwarding efficiency and avoiding waste of air interface resources.

[0233] Figure 9 This is an exemplary flowchart illustrating a method 900 for supporting handover according to an embodiment of the present invention. The method 900 can be used for intra-system handover or inter-system handover, and can be performed between a destination base station and a source base station.

[0234] like Figure 9 As shown, in method 900, in step S901, the destination base station receives a handover request message.

[0235] In step S902, the destination base station sends information to the source base station regarding whether it is a full configuration or a differential configuration. This information could also be whether the PDCP SN state is retained, whether the PDCP SN has been restarted, whether the PDCP SN is not needed, or whether data packets containing the PDCP SN are not required.

[0236] In this invention, the information for full configuration or differential configuration can be whether the PDCP SN status is retained, whether the PDCP SN is restarted, whether the forwarded data packet does not need the PDCP SN, or whether the data packet does not need to contain the PDCP SN. The following will not provide further explanation when mentioning the information for full configuration or differential configuration.

[0237] In step S903, based on the information, the source base station does not send PDCP service data units (SDUs) containing the PDCP sequence number (SN) to the destination base station.

[0238] Alternatively, in step S903, the source base station forwards a data packet that does not contain a PDCP SN to the destination base station based on the information. The forwarded data packet may be a PDCP SDU. For data packets that have already been assigned a PDCP SN, the source base station also does not include the PDCP SN in the forwarded data packet.

[0239] In one example, in step S901, the destination base station or the destination base station central unit control plane entity receives a handover request message. The handover request message is received from the source base station or the source base station central unit control plane entity, or from the core network. The handover request message received from the source base station or the source base station central unit control plane entity is an Xn Application Protocol (AP) message or other inter-base station message. The handover request message received from the core network is an NGAP message or other inter-base station and core network message.

[0240] The handover request message received from the core network contains a handover type.

[0241] The destination base station or the destination base station central unit control plane entity can decide whether to use a full configuration or a differential configuration. Furthermore, the destination base station or the destination base station central unit control plane entity can also decide whether to use a full configuration or a differential configuration for each established DRB.

[0242] In this example, in step S902, the destination base station or the destination base station central unit control plane entity can send information about whether it is a full configuration or a differential configuration to the source base station or the source base station central unit control plane entity.

[0243] The destination base station or its central control unit can send the information to the source base station or its central control unit via the interface message between the destination base station and the source base station. Alternatively, the destination base station or its central control unit can send the information to the source base station or its central control unit via the core network, for example, by sending the information regarding whether the configuration is fully configured or differentially configured to the source base station or its central control unit via a destination-to-source transparent transmitter.

[0244] The configuration can be either full or differential, and this can be applied to each DRB.

[0245] In one example, for handover preparation that is performed directly between base stations (e.g., Xn handover), the destination base station can send information about whether it is a full configuration or differential configuration to the source base station or the source base station central unit control plane entity via a request confirmation message.

[0246] In one example, for a handover prepared by the core network (e.g., NG handover), the destination base station can send information about whether it is a full configuration or differential configuration via a handover request confirmation from the destination base station to the core network and a handover command message from the core network to the source base station. Here, to avoid obscuring the subject matter of this invention, a description of the interactions between core network entities is omitted.

[0247] In one example, in step S903, the source base station receives the information from step S902. Based on this information, the source base station does not forward data packets containing the PDCP SN to the destination base station. For PDCP data packets sent by the source base station to the UE but not acknowledged by the UE, the source base station does not forward the data packets to the destination base station. The source base station sends a new (fresh) data packet to the destination base station. The source base station sends fresh data by sending a PDCP SDU that does not contain the PDCP SN to the destination base station.

[0248] In one example, in step S903, the source base station receives the information from step S902. Based on this information, the source base station forwards data packets that do not contain a PDCP SN to the destination base station. For data packets that have already been assigned a PDCP SN, the source base station also does not include the PDCP SN in the forwarded data packets.

[0249] In one example, if the source base station supports an architecture where the source base station central unit user plane and the source base station central unit control plane are separate, the source base station central unit control plane entity can notify the source base station central unit user plane entity, either explicitly or implicitly, that it does not need to forward PDCP SDUs containing PDCP SNs to the destination base station. The source base station central unit control plane entity informs the source base station central unit user plane entity that it does not need to forward PDCP SDUs containing PDCP SNs to the destination base station, or that PDCP SNs are not included in the forwarded data packets, where the data packets may be PDCP SDUs.

[0250] In the explicit indication mode, the source base station central unit control plane entity sends indication information to the source base station central unit user plane entity.

[0251] The source base station's central unit user plane entity, based on the indication information, determines not to forward PDCP SDUs containing PDCP SNs to the destination base station, but only to forward fresh data to the destination base station. Fresh data is PDCP SDUs without PDCP SNs. The source base station's central unit user plane entity forwards PDCP SDUs without PDCP SNs to the destination base station based on the indication information. For data packets with assigned PDCP SNs, the source base station also does not include the PDCP SN in the forwarded data packets.

[0252] In one example, the indication information may indicate at least one of the following: full configuration or differential configuration; whether the PDCPSN state is preserved; whether only new data is sent; whether a PDCP SDU containing the PDCP SN is sent; whether a PDCP data packet sent to the User Equipment (UE) without acknowledgment by the UE is sent; whether the PDCP SN is included in the forwarded data packet; and whether only PDCP SDUs without the PDCP SN are sent.

[0253] In the implicit indication method, the source base station central unit control plane entity sends channel information for data forwarding without requesting PDCP SN status information to indicate the above information, or to indicate that the source base station central unit control plane entity has not sent PDCP SN status information to the destination base station.

[0254] If the source base station central unit (CNTU) user plane entity knows that the PDCP SN status information is not retained or other aforementioned information, or that the source CNTU control plane entity has not sent PDCP SN status information to the destination base station, it will not forward PDCP SDUs containing the PDCP SN to the destination base station, but will only forward fresh data. The fresh data is sent via PDCP SDUs that do not contain the PDCP SN. Alternatively, the source CNTU user plane entity may forward data packets that do not contain the PDCP SN to the destination base station. For data packets that have already been allocated a PDCP SN, the source base station will not include the PDCP SN in the forwarded data packets.

[0255] For a DRB that the source base station central unit control plane entity requests to modify or establish, if the source base station central unit control plane entity does not request PDCP SN status information, the source base station central unit user plane entity knows that the PDCP SN status of the DRB is not retained, and therefore only forwards fresh data to the destination base station, instead of forwarding PDCPSDU containing the PDCP SN to the destination base station. The fresh data is sent via PDCP SDU that does not contain the PDCP SN.

[0256] For a DRB requested for modification or establishment by the source base station central unit control plane entity, if the source base station central unit control plane entity does not request PDCP SN status information, the source base station central unit user plane entity knows that the PDCP SN status of the DRB is not retained, and therefore forwards a PDCP SDU that does not contain a PDCP SN to the destination base station. For data packets that have already been allocated a PDCP SN, the source base station central unit user plane entity also does not include the PDCP SN in the forwarded data packets.

[0257] According to embodiments of the present invention, the source base station, particularly the source base station central unit control plane entity, can determine whether the PDCPSN state is maintained, and thus send appropriate data forwarding information to the source base station central unit user plane entity. Furthermore, the source base station central unit user plane entity only forwards the necessary data packets to the destination base station, avoiding unnecessary data transmission and resource waste, improving data forwarding efficiency, and reducing data loss.

[0258] Figure 10 This is an exemplary flowchart illustrating a method 1000 for supporting handover according to an embodiment of the present invention. The method 1000 can be used for intra-system handover or inter-system handover. The method includes the following steps.

[0259] In step S1001, the destination base station or the destination base station central unit control plane entity receives a handover request message. The handover request message is received from the source base station or the source base station central unit control plane entity, or from the core network. The handover request message received from the source base station or the source base station central unit control plane entity is an Xn Application Protocol (AP) message or other inter-base station messages. The handover request message received from the core network is an NGAP message or other messages between the base station and the core network.

[0260] The handover request message received from the core network contains a handover type.

[0261] The destination base station or the destination base station central unit control plane entity determines whether to use full configuration or differential configuration for each established DRB.

[0262] In step S1002, the destination base station or the destination base station central unit control plane entity sends information regarding whether it is a full configuration or Delta configuration to the source base station or the source base station central unit control plane entity. The destination base station or the destination base station central unit control plane entity can send this information to the source base station or the source base station central unit control plane entity via an interface message between the destination base station and the source base station. Alternatively, the destination base station or the destination base station central unit control plane entity can send this information to the source base station or the source base station central unit control plane entity via the core network, such as by sending the full configuration or Delta configuration information to the source base station or the source base station central unit control plane entity via a destination-to-source transparent transmitter. The full configuration or Delta configuration can be specific to each DRB.

[0263] For handover preparation that is performed directly between base stations (e.g., Xn handover), the destination base station sends the information to the source base station or the source base station central unit control plane entity via a request confirmation message.

[0264] For handover preparation performed through the core network (e.g., NG handover), the destination base station sends a handover request confirmation to the core network and a handover command message from the core network to the source base station. The explanation of the interaction between core network entities is omitted here.

[0265] In step S1003, the source base station receives the information from step S1002. The source base station does not forward data packets containing the PDCP SN to the destination base station. For PDCP data packets sent by the source base station to the UE but not acknowledged by the UE, the source base station does not forward the data packets to the destination base station. The source base station sends new (fresh) data packets to the destination base station. The source base station forwards fresh data to the destination base station by sending PDCP SDUs that do not contain the PDCP SN.

[0266] In one example, the source base station receives the information from step S1002 and forwards a data packet that does not contain a PDCP SN to the destination base station. The forwarded data packet may be a PDCP SDU. For data packets that have already been assigned a PDCP SN, the source base station also does not include the PDCP SN in the forwarded data packet.

[0267] If the source base station supports an architecture that separates the user plane and control plane, the source base station central unit control plane entity can inform the source base station central unit user plane entity in the following ways that it does not need to forward PDCPSDUs containing PDCP SN to the destination base station or forward PDCP SDUs without PDCP SN to the destination base station:

[0268] Method 1: The source base station central unit control plane entity sends indication information to the source base station central unit user plane entity. Based on this indication information, the source base station central unit user plane entity does not forward PDCP SDUs containing the PDCP SN to the destination base station, but only forwards fresh data. The fresh data consists of PDCP SDUs without the PDCP SN. Alternatively, the source base station central unit user plane entity forwards data packets without the PDCP SN to the destination base station based on the indication information. The forwarded data packets can be PDCP SDUs. For data packets with an allocated PDCP SN, the source base station also does not include the PDCP SN in the forwarded data packets. The indication information can be full configuration or delta configuration information, or information on whether the PDCP SN status is retained, or information on whether to forward only fresh data, or information on whether to forward PDC / PSDUs containing the PDCP SN, or information on whether to forward PDCP data packets sent to the UE but not acknowledged by the UE, or information on whether the PDCP SN is not needed, or information on only forwarding PDCP SDUs without the PDCP SN, etc.

[0269] Method 2: The source base station central unit control plane entity sends channel information for data forwarding to the source base station central unit user plane entity, but the source base station central unit control plane entity does not request PDCP SN status information. By not requesting PDCP SN status information, the source base station central unit user plane entity knows that the PDCP SN status is not retained, or other aforementioned information, or that the source base station central unit control plane entity did not send SN status information to the destination base station. Therefore, it does not forward PDCP SDUs containing the PDCP SN to the destination base station, but only forwards fresh data. The fresh data is sent via PDCP SDUs that do not contain the PDCP SN. Alternatively, the source base station central unit user plane entity forwards data packets that do not contain the PDCP SN to the destination base station. For DRBs that the source base station central unit control plane entity requests to modify or establish, if the source base station central unit control plane entity does not request PDCP SN status information, the source base station central unit user plane entity knows that the PDCP SN status of the DRB is not retained, and therefore only forwards fresh data to the destination base station, and does not forward PDCP SDUs containing the PDCP SN to the destination base station. The fresh data is sent via PDCP SDUs that do not contain a PDCP SN. Alternatively, the source base station central unit user plane entity forwards data packets that do not contain a PDCP SN to the destination base station.

[0270] The source base station central unit user plane entity, according to the indicated information, does not forward PDCPSDUs containing the PDCP SN to the destination base station, but only forwards fresh data to the destination base station. The fresh data consists of PDCPSDUs without the PDCP SN. Alternatively, the source base station central unit user plane entity forwards data packets without the PDCP SN to the destination base station. These data packets may be PDCP SDUs. For data packets with an allocated PDCP SN, the source base station also does not include the PDCP SN in the forwarded data packets.

[0271] This concludes the description of the handover support method 1000 of the present invention. Through this method, the source base station, particularly the source base station central unit control plane entity, can determine whether the PDCP SN state is maintained, and thus send appropriate data forwarding information to the source base station central unit user plane entity. The source base station central unit user plane entity only forwards the necessary data packets to the destination base station, avoiding unnecessary data transmission and resource waste, improving data forwarding efficiency, and reducing data loss.

[0272] Figure 11 This is an exemplary flowchart illustrating a method 1100 for supporting handover according to an embodiment of the present invention. The method 1100 can be used for intra-system handover or inter-system handover, and can be executed on the control plane entity side of the source base station central unit.

[0273] like Figure 11 As shown, in method 1100, in step S1101, a switching-related message is received.

[0274] In step S1102, information for data forwarding is indicated to the user plane entity of the source base station central unit, wherein the user plane entity of the source base station central unit sends a PDCP service data unit (SDU) without containing a packet data convergence protocol (PDCP SN) to the destination base station based on the information for data forwarding.

[0275] Alternatively, in step S1102, information for data forwarding is indicated to the source base station central unit user plane entity, wherein the source base station central unit user plane entity forwards a PDCP SDU that does not contain a PDCP SN to the destination base station based on the information for data forwarding.

[0276] In one example, the handover-related message is one of a handover request confirmation message and a handover command message, and the handover-related message indicates whether it is a full configuration or a differential configuration, or indicates whether the Packet Data Convergence Protocol (PDCP) sequence number (SN) status is retained. For example, in step S1101, the source base station central unit control plane entity can receive either a handover command message or a handover request confirmation message. The handover request confirmation message can be received from the destination base station or the destination base station central unit control plane entity. The handover command message is received from the core network.

[0277] The handover request confirmation message or handover command message contains information on whether it is a full configuration or a differential configuration, or whether the PDCP SN status is retained.

[0278] In one example, in step S1102, the source base station central unit control plane entity can indicate information for data forwarding to the source base station central unit user plane entity through an explicit indication method or an implicit indication method.

[0279] In the explicit indication method, the information used for data forwarding may include indication information sent via a bearer context modification request message, and the indication information may indicate at least one of the following: whether the PDCP SN state is preserved; whether only new data is sent; whether a PDCP SDU containing the PDCP SN is sent; whether a PDCP data packet sent to the user equipment UE without acknowledgment by the UE is sent; whether the PDCP SN is included in the forwarded data packet; and whether only PDCP SDUs without the PDCP SN are sent.

[0280] In one example, when the source base station central unit user plane entity determines, based on the indication information, that it only forwards fresh data to the destination base station and does not forward PDCP SDUs containing PDCP SNs to the destination base station: the PDCP SN state is not retained; only new data is sent; PDCP SDUs containing PDCP SNs are not sent; PDCP data packets sent to the user equipment UE that the UE has not acknowledged are not sent; and PDCP SDUs without PDCP SNs are sent.

[0281] In one example, when the source base station central unit user plane entity determines, based on the indication information, that at least one of the following is true, it knows to forward a PDCP SDU that does not contain a PDCP SN to the destination base station: the PDCP SN state is not retained; only new data is sent; no PDCP SDU containing a PDCP SN is sent; no PDCP data packets sent to the user equipment UE that the UE has not acknowledged are forwarded; and only PDCP SDUs that do not contain a PDCP SN are sent.

[0282] In the implicit indication method, the source base station central unit control plane entity can send channel information for data forwarding without requesting PDCP SN status information, indicating that the PDCP SN status has not been retained or that the source base station central unit control plane entity has not sent PDCP SN status information to the destination base station. By not requesting PDCP SN status information, the source base station central unit user plane entity knows that the PDCP SN status has not been retained or that the source base station central unit control plane entity has not sent SN status information to the destination base station, and therefore does not forward PDCP SDUs containing PDCP SNs to the destination base station, but only forwards fresh data to the destination base station. Fresh data is sent via PDCP SDUs that do not contain PDCP SNs. Alternatively, the source base station central unit user plane entity forwards data packets that do not contain PDCP SNs to the destination base station.

[0283] For a DRB that the source base station central unit control plane entity requests to modify or establish, if the source base station central unit control plane entity does not request PDCP SN status information, the source base station central unit user plane entity knows that the PDCP SN status of the DRB is not retained, and therefore only forwards fresh data to the destination base station, instead of forwarding PDCPSDU containing the PDCP SN to the destination base station. The fresh data is sent via PDCP SDU that does not contain the PDCP SN.

[0284] For a DRB requested for modification or establishment by the source base station central unit control plane entity, if the source base station central unit control plane entity does not request PDCP SN status information, the source base station central unit user plane entity knows that the PDCP SN status of the DRB is not retained, and therefore forwards a PDCP SDU that does not contain a PDCP SN to the destination base station. For data packets that have already been allocated a PDCP SN, the source base station central unit user plane entity also does not include the PDCP SN in the forwarded data packets.

[0285] In addition, the source base station central unit user plane entity may not forward data packets sent to the UE but not acknowledged by the UE.

[0286] The source base station central unit user plane entity learns the data forwarding information through either the explicit or implicit indication method in step S1102. Corresponding to the implicit indication method, the source base station central unit user plane entity knows that the PDCP SN status is not retained or that the source base station central unit control plane entity has not sent PDCP SN status information to the destination base station, based on whether the source base station central unit control plane entity requested PDCP SN status information. Therefore, it does not forward PDCP SDUs containing PDCP SNs to the destination base station, but only forwards fresh data. The fresh data is sent via PDCP SDUs that do not contain PDCP SNs. Alternatively, the source base station central unit user plane entity forwards data packets that do not contain PDCP SNs to the destination base station. For data packets that have already been allocated PDCP SNs, the source base station central unit user plane entity also does not include PDCP SNs in the forwarded data packets.

[0287] According to embodiments of the present invention, the source base station central unit control plane entity can send appropriate data forwarding information to the source base station central unit user plane entity, and the source base station central unit user plane entity only forwards the necessary data packets to the destination base station. This avoids unnecessary data transmission and resource waste, improves the efficiency of data forwarding, and reduces data loss.

[0288] Figure 12 This is an exemplary flowchart illustrating a method 1200 for supporting handover according to an embodiment of the present invention. The method can be used for intra-system handover or inter-system handover. The method includes the following steps.

[0289] In step S1201, the source base station central unit control plane entity receives a handover command message or a handover request confirmation message. The handover request confirmation message is received from the destination base station or the destination base station central unit control plane entity. The handover command message is received from the core network.

[0290] The handover request confirmation message or handover command message contains information about whether it is a full configuration or a delta configuration, or whether the PDCP SN status is retained.

[0291] In step S1202, the source base station central unit control plane entity informs the source base station central unit user plane entity of data forwarding information explicitly or implicitly. The data forwarding information may take the form of whether the PDCP SN status is retained, whether only fresh data is forwarded, whether PDCP SDUs containing the PDCP SN are forwarded, whether PDCP data packets sent to the UE but not acknowledged by the UE are forwarded, whether the PDCP SN is not required, or whether only PDCP SDUs without the PDCP SN are forwarded, etc. The explicit method is to indicate the data forwarding information by including information elements. These information elements may be included in the bearer context modification request message.

[0292] The implicit method involves the source base station central unit control plane entity not sending a request for PDCP SN status information to the source base station central unit user plane entity. Instead, the source base station central unit control plane entity sends channel information for data forwarding to the source base station central unit user plane entity. By not requesting PDCP SN status information, the source base station central unit user plane entity knows that the PDCP SN status is not retained, or that it has not sent SN status information to the destination base station. Therefore, it does not forward PDCP SDUs containing the PDCP SN to the destination base station, but only forwards fresh data. This fresh data is sent via PDCP SDUs that do not contain the PDCP SN. Alternatively, the source base station central unit user plane entity forwards data packets that do not contain the PDCP SN to the destination base station. For data packets that have already been allocated a PDCP SN, the source base station central unit user plane entity also does not include the PDCP SN in the forwarded data packets. For a DRB requested for modification or establishment by the source base station central unit control plane entity, if the source base station central unit control plane entity does not request PDCP SN status information, the source base station central unit user plane entity knows that the PDCP SN status of the DRB is not retained, and therefore only forwards fresh data to the destination base station, without forwarding PDCP SDUs containing the PDCP SN to the destination base station. The fresh data is sent through PDCP SDUs that do not contain the PDCP SN. Alternatively, the source base station central unit user plane entity forwards data packets that do not contain the PDCP SN to the destination base station. For data packets that have already been allocated a PDCP SN, the source base station central unit user plane entity also does not include the PDCP SN in the forwarded data packets.

[0293] In step S1203, the source base station central unit user plane entity forwards PDCP SDUs without PDCP SN to the destination base station, but does not forward PDCP SDUs with PDCP SN to the destination base station. Only fresh data is forwarded to the destination base station. This fresh data is sent via PDCP SDUs without PDCP SN. The source base station central unit user plane entity does not forward data packets sent to the UE that the UE has not acknowledged. The source base station central unit user plane entity knows the data forwarding information through either the explicit or implicit method described in step S1202. In the implicit method, the source base station central unit user plane entity knows that the PDCP SN status is not retained because the source base station central unit control plane entity has not requested PDCP SN status information, or because the source base station central unit control plane entity has not sent SN status information to the destination base station. Therefore, it does not forward PDCP SDUs with PDCP SN to the destination base station, but only forwards fresh data. This fresh data is sent via PDCP SDUs without PDCP SN.

[0294] Alternatively, in step S1203, the source base station central unit user plane entity forwards data packets that do not contain a PDCP SN to the destination base station. For data packets that have already been assigned a PDCP SN, the source base station central unit user plane entity also does not include the PDCP SN in the forwarded data packets.

[0295] This concludes the description of the handover support method 1200 of the present invention. Through this method, the source base station central unit control plane entity sends appropriate data forwarding information to the source base station central unit user plane entity. The source base station central unit user plane entity then forwards only the necessary data packets to the destination base station, avoiding unnecessary data transmission and resource waste, improving data forwarding efficiency, and reducing data loss.

[0296] Figure 13 This is an exemplary flowchart illustrating a method 1300 for supporting handover according to an embodiment of the present invention. The method 1300 can be used for intra-system handover or inter-system handover, and can be executed on the user plane entity side of the source base station central unit.

[0297] like Figure 13 As shown, in method 1300, in step S1301, information indicating data forwarding is received.

[0298] In step S1302, based on the information used for data forwarding, a PDCP service data unit (SDU) that does not contain a Packet Data Convergence Protocol (PDCP) SN is sent to the destination base station.

[0299] In step S1302, based on the information used for data forwarding, the PDCP Service Data Unit (SDU) containing the Packet Data Convergence Protocol (PDCP) SN is not sent to the destination base station. For data packets for which a PDCP SN has already been assigned, the source base station also does not include the PDCP SN in the forwarded data packets.

[0300] In one example, in step S1301, information indicating data forwarding can be received through either an explicit indication method or an implicit indication method.

[0301] In the explicit indication method, the source base station central unit user plane entity can receive information for data forwarding sent by the source base station central unit control plane entity. The information indicating data forwarding includes indication information received via a bearer context modification request message, and the indication information can indicate at least one of the following: whether the PDCP SN state is retained; whether only new data is sent; whether a PDCP SDU containing the PDCP SN is sent; whether a PDCP data packet sent to the user equipment UE without acknowledgment by the UE is sent; whether the PDCP SN is sent; and whether only PDCPSDUs without the PDCP SN are sent.

[0302] In one example, when the source base station central unit user plane entity determines, based on the indication information, that it only forwards fresh data to the destination base station and does not forward PDCP SDUs containing PDCP SNs to the destination base station: the PDCP SN state is not retained; only new data is sent; PDCP SDUs containing PDCP SNs are not sent; PDCP data packets sent to the user equipment UE that the UE has not acknowledged are not sent; PDCP SNs are not sent; and PDCP SDUs without PDCP SNs are sent.

[0303] In one example, when the source base station central unit user plane entity determines, based on the indication information, that at least one of the following is true, it knows to forward a PDCP SDU that does not contain a PDCP SN to the destination base station: the PDCP SN state is not retained; only new data is sent; no PDCP SDU containing a PDCP SN is sent; no PDCP data packets sent to the user equipment UE that the UE has not acknowledged are sent; no PDCP SN is sent; and only PDCP SDUs that do not contain a PDCP SN are sent.

[0304] In the implicit indication method, channel information for data forwarding is received from the source base station central unit control plane entity without requesting PDCP SN status information, in order to indicate that the PDCP SN is not reserved or that the source base station central unit control plane entity has not sent PDCP SN status information to the destination base station.

[0305] The source base station central unit control plane entity sends channel information for data forwarding to the source base station central unit user plane entity. Since no PDCP SN status information is requested, the source base station central unit user plane entity knows that the PDCP SN is not retained or that the source base station central unit control plane entity has not sent PDCP SN status information to the destination base station. Therefore, it does not forward PDCP SDUs containing the PDCP SN to the destination base station, but only forwards fresh data. Fresh data is sent via PDCP SDUs that do not contain the PDCP SN.

[0306] The source base station central unit control plane entity sends channel information for data forwarding to the source base station central unit user plane entity. Since no PDCP SN status information is requested, the source base station central unit user plane entity knows that the PDCP SN is not retained or that the source base station central unit control plane entity has not sent PDCP SN status information to the destination base station, and thus forwards PDCP SDUs that do not contain a PDCP SN to the destination base station.

[0307] For a DRB that the source base station central unit control plane entity requests to modify or establish, if the source base station central unit control plane entity does not request PDCP SN status information, the source base station central unit user plane entity knows that the PDCP SN status of the DRB is not retained, and therefore only forwards fresh data to the destination base station, instead of forwarding PDCPSDU containing the PDCP SN to the destination base station. The fresh data is sent via PDCP SDU that does not contain the PDCP SN.

[0308] For a DRB requested for modification or establishment by the source base station central unit control plane entity, if the source base station central unit control plane entity does not request PDCP SN status information, the source base station central unit user plane entity knows that the PDCP SN status of the DRB is not retained, and therefore forwards a PDCP SDU that does not contain a PDCP SN to the destination base station. For data packets that have already been allocated a PDCP SN, the source base station central unit user plane entity also does not include the PDCP SN in the forwarded data packets.

[0309] The source base station central unit (BNU) user plane entity forwards PDCP SDUs without a PDCP SN to the destination base station, but does not forward PDCP SDUs containing a PDCP SN. The PDCP SDU without a PDCP SN can be fresh data. The BNU user plane entity does not forward data packets sent to the UE but not acknowledged by the UE. The BNU user plane entity knows the data forwarding information through the explicit or implicit indication method in step S1301. Corresponding to the implicit indication method, the BNU user plane entity knows that the PDCP SN status is not retained based on the BNU control plane entity not requesting PDCP SN status information or the BNU control plane entity not sending PDCP SN status information to the destination base station, and therefore does not forward PDCP SDUs containing a PDCP SN to the destination base station, but only forwards fresh data. Fresh data is sent via PDCP SDUs without a PDCP SN. The BNU user plane entity does not forward data packets sent to the UE but not acknowledged by the UE. Alternatively, the source base station central unit user plane entity may forward data packets that do not contain a PDCP SN to the destination base station.

[0310] According to embodiments of the present invention, the user plane entity of the source base station central unit can forward only the necessary data packets to the destination base station, avoiding unnecessary data transmission and resource waste, improving the efficiency of data forwarding, and reducing data loss.

[0311] Figure 14 This is an exemplary flowchart illustrating a method 1400 for supporting handover according to an embodiment of the present invention. The method 1400 can be used for intra-system handover or inter-system handover. The method includes the following steps.

[0312] In step S1401, the user plane entity of the source base station central unit receives data forwarding information and channel information for data forwarding sent by the control plane entity of the source base station central unit. The data forwarding information includes information such as whether PDCP SDUs containing a PDCP SN need to be forwarded, whether the PDCP SN status is retained, whether only fresh data needs to be forwarded, whether PDCP data packets sent to the UE but not acknowledged by the UE need to be forwarded, whether the PDCP SN is included in the forwarded data packets, or whether only PDCP SDUs without a PDCP SN need to be forwarded, etc. The data forwarding information can be explicit or implicit. Explicit information directly includes information elements to indicate the aforementioned data forwarding information. These information elements can be included in the bearer context modification request message.

[0313] The implicit method involves the source base station central unit control plane entity not sending a request for PDCP SN status information to the source base station central unit user plane entity. Instead, the source base station central unit control plane entity sends channel information for data forwarding to the source base station central unit user plane entity. By not requesting PDCP SN status information, the source base station central unit user plane entity knows that the PDCP SN status is not retained or that it did not send SN status information to the destination base station. Therefore, it forwards data packets without a PDCP SN to the destination base station, or does not forward PDCP SDUs containing a PDCP SN to the destination base station, or only forwards fresh data to the destination base station, where the fresh data is sent via PDCP SDUs without a PDCP SN. For a DRB that the source base station central unit control plane entity requests to modify or establish, if it does not request PDCP SN status information, the source base station central unit user plane entity knows that the PDCP SN status of the DRB is not retained. Therefore, it only forwards fresh data to the destination base station and does not forward PDCP SDUs containing a PDCP SN to the destination base station. The fresh data is sent via PDCP SDUs that do not contain a PDCP SN. Alternatively, the source base station central unit user plane entity forwards data packets that do not contain a PDCP SN to the destination base station.

[0314] In step S1402, the source base station central unit user plane entity forwards PDCP SDUs that do not contain a PDCP SN to the destination base station, and does not forward PDCP SDUs that do contain a PDCP SN to the destination base station. The PDCP SDUs that do not contain a PDCP SN can be fresh data. The source base station central unit user plane entity does not forward data packets sent to the UE that the UE has not acknowledged. The source base station central unit user plane entity knows the data forwarding information through the explicit or implicit method described in step S1401. Corresponding to the implicit method, the source base station central unit user plane entity knows that the PDCP SN status is not retained or that the source base station central unit control plane entity has not sent SN status information to the destination base station, based on whether the source base station central unit control plane entity has requested PDCP SN status information or not. Therefore, it forwards data packets that do not contain a PDCP SN to the destination base station, or does not forward PDCP SDUs that contain a PDCP SN to the destination base station. Alternatively, it may only forward fresh data to the destination base station, where the fresh data is sent via PDCP SDUs that do not contain a PDCP SN. The source base station central unit user plane entity does not forward data packets sent to the UE that the UE has not acknowledged.

[0315] This concludes the description of the handover support method 1400 of the present invention. Through this method, the source base station central unit user plane entity only forwards the necessary data packets to the destination base station, avoiding unnecessary data transmission and resource waste, improving data forwarding efficiency, and reducing data loss.

[0316] Figure 15 An exemplary flowchart of a method 1500 for supporting handover according to an embodiment of the present invention is shown. The method 1500 can be used for intra-system handover or inter-system handover. The method includes the following steps.

[0317] In step S1501, the destination base station central unit control plane entity receives a handover request message from either the source base station or the core network. The handover request message received from the source base station is an application layer message from the inter-base station interface, such as an XnAP message. The handover request message received from the core network is an application layer message from the base station and core network interface, such as an NGAP message. The handover request message contains the UE's configuration information at the source base station, including DRB configuration information and / or a mapping of QoS flow to the DRB. The message also includes the E-RAB identifier for the QoS flow mapping.

[0318] The destination base station central unit control plane entity determines the destination DRB configuration information and / or the QoS Flow to DRB mapping. The destination base station includes the destination DRB configuration information and / or the QoS Flow to DRB mapping in the handover command message, which is sent to the UE through the source base station.

[0319] In step S1502, the destination base station central unit control plane entity sends the configuration information of the source DRB and the destination DRB to the destination base station central unit user plane entity. And / or, the destination base station central unit control plane entity sends the mapping of the source QoS flow to the DRB and the mapping of the destination QoS flow to the DRB to the destination base station central unit user plane entity. For inter-system handover from a 4G system to a 5G system, the configuration information of the source DRB can also be considered the configuration information of the source E-RAB, and the mapping of the source QoS flow to the DRB is also a mapping of the QoS flow to the E-RAB.

[0320] The target base station central unit control plane entity can decide to use the same DRB configuration as the source end or a different DRB configuration.

[0321] If the destination base station central unit control plane entity decides to use the same DRB configuration and the same QoS flow mapping to the DRB as the source base station, it sends the information—that is, the same DRB configuration as the source base station—to the destination base station central unit user plane entity through the DRB to be established and the QoS flow information to be established on the DRB. The destination base station central unit control plane entity sends this information to the destination base station central unit user plane entity via a bearer context establishment request message or a bearer context modification request message. The destination base station central unit control plane entity sends the mapping relationship to the destination base station central unit user plane entity through the QoS flow(s) information to be established contained in the DRB to be established in the bearer context establishment request message or the bearer context modification request message. The DRB to be established is either a DRB to be established contained in the PDU session resource establishment list in the bearer context establishment request message or a DRB to be established contained in the PDU session resource establishment list (also called the PDU session resource establishment modification list) in the bearer context modification request message. For handover from E-UTRA and NR dual-link (EN-DC) to standalone architecture (SA) where the source base station and destination base station are shared, the destination base station central unit control plane entity can send the mapping relationship to the destination base station central unit user plane entity through the QoS flow(s) information to be established contained in the DRB to be established in the bearer context modification request message.

[0322] If the destination base station central unit control plane entity determines to map the DRB to the same QoS flow as the source base station, it sends the mapping relationship to the destination base station central unit user plane entity. The destination base station central unit control plane entity sends the mapping relationship to the destination base station central unit user plane entity via a bearer context establishment request message or a bearer context modification request message. The destination base station central unit control plane entity sends the mapping relationship to the destination base station central unit user plane entity via the QoS flow(s) information to be established contained in the DRB to be established in the bearer context establishment request message or the bearer context modification request message. The DRB to be established is either a DRB to be established contained in the PDU session resource establishment list in the bearer context establishment request message or a DRB to be established contained in the PDU session resource establishment list (also called the PDU session resource establishment modification list) in the bearer context modification request message. For EN-DC to SA handover where the source base station and destination base station are shared, the destination base station central unit control plane entity can send the mapping relationship to the destination base station central unit user plane entity through the QoS flow(s) information to be established contained in the DRB to be established in the bearer context modification request message.

[0323] If the destination base station central unit control plane entity decides to use a different DRB configuration and / or a different QoS flow to DRB mapping than the source base station, in order to ensure no data loss during handover, the destination base station central unit control plane entity may temporarily configure the same DRB and / or the same QoS flow to DRB mapping as the source base station to process data forwarded by the source base station. The destination DRB configuration and QoS flow to DRB mapping determined by the destination base station central unit control plane entity are used by the destination base station central unit user plane entity to process new data received from the core network. For inter-system handover from 4G to 5G systems, the destination base station central unit control plane entity may temporarily configure the same DRB (or E-RAB) and / or the same QoS flow to DRB (or E-RAB mapping) as the source base station to process data forwarded by the source base station. The destination DRB configuration and QoS flow to DRB mapping determined by the destination base station central unit control plane entity are used by the destination base station central unit user plane entity to process new data received from the core network.

[0324] When the destination base station central unit control plane entity determines that the DRB configuration at the destination end is different from the DRB configuration at the source end, the destination base station central unit control plane entity sends the source end DRB configuration information to the destination base station central unit user plane entity. The destination base station central unit control plane entity can directly send the source end DRB configuration information and the destination end DRB configuration information to the destination base station central unit user plane entity, or send the destination end DRB configuration information and the differential (delta) configuration between the source and destination ends to the destination base station central unit user plane entity, or send the source end DRB configuration information and the differential (delta) configuration between the source and destination ends to the destination base station central unit user plane entity. Through the destination end DRB configuration information and the delta configuration information between the source and destination ends, the destination base station central unit user plane entity knows the source end DRB configuration information, or through the source end DRB configuration information and the delta configuration information between the source and destination ends, the destination base station central unit user plane entity knows the destination end DRB configuration information. If the destination base station central unit control plane entity directly sends the configuration information of the source DRB and the configuration information of the destination DRB to the destination base station central unit user plane entity, then the QoS flow information to be established contained in the configuration information of the corresponding source DRB is the QoS flow(s) mapped from the source to the DRB. The QoS flow information to be established contained in the configuration information of the destination DRB is the QoS flow(s) mapped from the destination to the DRB. The configuration information of the DRB is contained in the DRB information to be established or the DRB information to be modified. The configuration information of the destination DRB can be represented by the DRB to be established or the DRB to be modified in the existing message, and new information elements, such as source DRB configuration information, can be defined to represent the configuration information of the source DRB. The configuration information of the source DRB can be represented by the DRB to be established or the DRB to be modified in the existing message, and new information elements, such as destination DRB configuration information or updated DRB configuration information, can be defined to represent the configuration information of the destination DRB. If the destination base station central unit control plane entity sends the destination DRB configuration information and the differential (delta) configuration between the source and destination ends to the destination base station central unit user plane entity, the DRB to be established or modified information includes the destination DRB configuration information and the QoS flow(s) mapped from the destination end to the DRB. The DRB to be established or modified information also includes the differential configuration and / or the QoS flow(s) mapped from the source end to the DRB. If a DRB is only a configuration at the source end and the destination end does not use the corresponding DRB, then the DRB to be established or modified includes source DRB indication information.If the destination base station central unit control plane entity sends the source DRB configuration information and the differential (delta) configuration between the source and destination ends to the destination base station central unit user plane entity, then the DRB to be established or the DRB to be modified information includes the source DRB configuration information and the QoS flow(s) mapped from the source end to the DRB. Furthermore, the DRB to be established or the DRB to be modified information also includes the differential configuration and / or the QoS flow(s) mapped from the destination end to the DRB. If a DRB is only a configuration at the source end and the destination end does not use the corresponding DRB, then the DRB to be established or the DRB to be modified includes destination DRB indication information.

[0325] If the destination base station central unit control plane entity determines a different QoS flow to DRB mapping than the source base station, to ensure no data loss during handover, the destination base station central unit control plane entity can temporarily configure the same QoS flow to DRB mapping as the source base station to handle data forwarded by the source base station. The destination QoS flow to DRB mapping determined by the destination base station central unit control plane entity is used by the destination base station central unit user plane entity to process new data received from the core network. For inter-system handover from 4G to 5G systems, the destination base station central unit control plane entity can temporarily configure the same QoS flow to DRB (or E-RAB) mapping as the source base station to handle data forwarded by the source base station. The destination DRB configuration and QoS flow to DRB mapping determined by the destination base station central unit control plane entity are used by the destination base station central unit user plane entity to process new data received from the core network.

[0326] The destination base station central unit control plane entity sends the mapping of the source QoS flow to the DRB and / or the mapping of the destination QoS flow to the DRB to the destination base station central unit user plane entity. The DRB information to be established sent by the destination base station central unit control plane entity to the destination base station central unit user plane entity includes the QoS flow information to be established at the destination and / or the QoS flow information to be established at the source. The QoS flow information to be established at the destination includes one or more QoS flows mapped from the destination to the DRB. The QoS flow information to be established at the source includes one or more QoS flows mapped from the source to the DRB. If the DRB information to be established only contains the QoS flow information to be established at the destination, it indicates that the DRB is only used to process new data from the core network, and the source does not use the corresponding DRB. If the DRB information to be established only contains the QoS flow information to be established at the source end, it means that the DRB is only used to process data forwarded from the source base station. The destination end does not use the corresponding DRB, indicating that the DRB is an old DRB configuration at the source end. After the user plane entity of the destination base station central unit receives the end marker data packet, the DRB can be released.

[0327] The QoS flow information to be established at the destination can be represented by the existing QoS flow information to be established in the DRB information to be established in the interface message between the Base Station Central Unit Control Plane Entity and the Base Station Central Unit User Plane Entity. This requires defining a new Information Element (IE), such as the source QoS flow information or the old QoS flow information to be established, to represent the source's mapping information or the source's QoS flow information to be established. The existing QoS flow information to be established in the DRB information to be established is a mandatory field. To indicate that the DRB is an old DRB from the source and not used at the destination, the DRB information to be established only needs to include the source QoS flow information or the old QoS flow information to be established (i.e., the QoS flow information mapped from the source to the DRB). To handle this situation, the DRB information to be established in the interface message between the Base Station Central Unit Control Plane Entity and the Base Station Central Unit User Plane Entity can include a source DRB configuration indicator or an old DRB configuration indicator, allowing the Base Station Central Unit User Plane Entity to ignore the existing QoS flow information to be established. This method can also be used to carry context modification messages.

[0328] The existing QoS Flow information to be established in the DRB information to be established in the interface message between the Base Station Central Unit (BNU) Control Plane Entity and the BNU User Plane Entity can be used to represent the QoS flow information to be established at the source end. This requires defining a new Information Element (IE), such as the destination QoS flow information or the new QoS flow information to be established, to represent the mapping information or the QoS flow information to be established at the destination end. The existing QoS Flow information to be established in the DRB information to be established is a mandatory field. To indicate that the DRB is the destination DRB, the DRB information to be established only needs to include the destination QoS flow information or the new QoS flow information to be established (i.e., the QoS flow information mapped from the destination to the DRB). To handle this situation, the DRB information to be established in the interface message between the BNU Control Plane Entity and the BNU User Plane Entity can include a destination DRB configuration indication or a new DRB configuration indication, allowing the BNU User Plane Entity to ignore the existing QoS flow information to be established. This method can also be used to carry context modification messages.

[0329] The DRB information to be modified, sent by the Destination Base Station Central Unit (DNU) Control Plane Entity to the DNU User Plane Entity, includes destination flow mapping information and / or source flow mapping information. The destination flow mapping information includes one or more QoS flows mapped from the destination to the DRB. The source flow mapping information includes one or more QoS flows mapped from the source to the DRB. If the DRB information to be modified only contains destination flow mapping information, it indicates that the DRB is only used to process new data from the core network, and the source end does not use the corresponding DRB. If the DRB information to be modified only contains source flow mapping information, it indicates that the DRB is only used to process data forwarded from the source base station, and the destination end does not use the corresponding DRB. This indicates that the DRB is an old DRB configuration at the source end, and the DRB can be released by the DNU User Plane Entity upon receiving the end marker data packet.

[0330] The existing flow mapping information in the DRB information to be modified in the interface message of the base station central unit control plane entity and the base station central unit user plane entity can be used to represent the QoS flow(s) of the destination end mapped to the DRB. This requires defining a new information element (IE), such as source flow mapping information or old flow mapping information, to represent the QoS flow(s) of the source end mapped to the DRB.

[0331] The existing flow mapping information in the DRB information to be modified in the interface message of the base station central unit control plane entity and the base station central unit user plane entity can be used to represent the QoS flow(s) of the source end mapped to the DRB. This requires defining a new information element (IE), such as destination flow mapping information or new flow mapping information, to represent the QoS flow(s) of the destination end mapped to the DRB.

[0332] The destination base station central unit control plane entity can send the above information to the destination base station central unit user plane entity using a bearer context establishment request, a bearer context modification request message, or other messages. The DRB to be established is either a DRB included in the PDU session resource establishment list in the bearer context establishment request message or a DRB included in the PDU session resource establishment list (also called the PDU session resource establishment modification list) in the bearer context modification request message. For EN-DC to SA handover where the source and destination base stations are shared, the destination base station central unit control plane entity can send the above information to the destination base station central unit user plane entity by including it in the DRB to be established in the bearer context modification request message.

[0333] In step S1503, the destination base station central unit user plane entity receives the aforementioned information from the destination base station central unit control plane entity, and saves the received information. The destination base station central unit user plane entity allocates channel information for the DRB requesting data forwarding and sends it to the destination base station central unit control plane entity.

[0334] The destination base station central unit control plane entity sends a UE context establishment request message to the destination base station distribution unit (hereinafter referred to as gNB-DU). This message includes the configuration of the source DRB and the DRB configuration determined at the destination. Corresponding to the source DRB, the DRB to be established includes the QoS flow(s) mapped to the DRB at the source. Corresponding to a new DRB determined at the destination, the DRB to be established includes the QoS flow(s) mapped to the DRB determined by the destination base station central unit control plane entity. If the destination uses the same DRB configuration and the same QoS flow to DRB mapping as the source, the DRB to be established includes the QoS flow(s) mapped to the DRB. If the destination uses the same DRB configuration as the source but a different QoS flow to DRB mapping, the DRB to be established may include the QoS flow(s) mapped to the DRB at the source and / or the QoS flow(s) mapped to the DRB at the destination. The gNB-DU assigns a downlink transport layer address and a channel identifier to each DRB to be established. The gNB-DU sends a UE context establishment response message to the destination base station central unit control plane entity. This message contains the downlink transport layer address and channel identifier assigned by the gNB-DU for each DRB. The base station central unit control plane entity sends the downlink transport layer address and channel identifier assigned by the gNB-DU for each DRB to the destination base station central unit user plane entity. The destination base station central unit user plane entity receives the data forwarded from the source base station.

[0335] The destination base station central unit user plane entity processes data forwarded from the source base station using the source DRB configuration and / or the mapping of source QoS flow to the DRB, and processes new data received from the core network using the destination DRB configuration and / or the mapping of destination QoS flow to the DRB. If the corresponding DRB to be established or modified does not contain destination QoS flow information, the destination base station central unit user plane entity can release the DRB after receiving the end marker data packet. The destination base station central unit user plane entity first sends the forwarded data received from the source base station to the UE via gNB-DU. After receiving the end marker, it begins sending data received from the core network.

[0336] The release process of the old DRB on the gNB-DU is as follows: Figure 25 The method described herein or as follows. The old DRB is the source-side DRB, and the destination-side configuration is for processing forwarded data.

[0337] If no new data is received on a DRB within a certain period of time, the gNB-DU sends a UE context modification request message to the destination base station central unit control plane entity. This message contains an identifier indicating that the DRB needs to be released. Upon receiving this message, the destination base station central unit control plane entity can release the old DRB.

[0338] This concludes the description of the handover support method 1500 of the present invention. This method ensures correct processing between the control plane and user plane of the destination base station central unit, even when the destination base station uses a different QoS flow to DRB mapping than the source base station. This avoids data loss, improves data transmission efficiency, and enhances the reliability of data forwarding during handover.

[0339] Figure 16 This is an exemplary flowchart illustrating a method 1600 for supporting handover according to an embodiment of the present invention. The method 1600 can be used for intra-system handover or inter-system handover, and can be executed on the control plane entity side of the destination base station central unit. The method includes the following steps.

[0340] like Figure 16 As shown, in method 1600, in step S1601, a handover request message is received.

[0341] The destination base station central unit control plane entity receives a handover request message from either the source base station or the core network. The handover request message received from the source base station is an application layer message from the inter-base station interface, such as an XnAP message. The handover request message received from the core network is an application layer message from the base station and core network interface, such as an NGAP message. The handover request message contains the UE's configuration information at the source base station, including the mapping of service QoS flow to the DRB. The message also includes the E-RAB identifier for the QoS flow mapping.

[0342] The destination base station central unit control plane entity determines the configuration of the DRB at the destination end.

[0343] The destination base station central unit control plane entity determines the mapping from the destination QoS Flow to the DRB. The destination base station contains the configuration of the destination DRB and / or the mapping from the QoS Flow to the DRB in the handover command message, which is sent to the UE through the source base station.

[0344] In step S1602, the configuration information of the source DRB and the configuration information of the destination DRB are sent to the user plane entity of the destination base station central unit. And / or, the mapping of the source QoS flow to the data radio bearer (DRB) and the mapping of the destination QoS flow to the DRB are sent to the user plane entity of the destination base station central unit. The configuration of the source DRB and / or the mapping of the QoS flow to the DRB are used by the user plane entity of the destination base station central unit to process forwarded data received from the source base station, and the configuration of the destination DRB and / or the mapping of the QoS flow to the DRB are used by the user plane entity of the destination base station central unit to process new data received from the core network. For inter-system handover from a 4G system to a 5G system, the configuration information of the source DRB can also be considered the configuration information of the source E-RAB, and the mapping of the source QoS flow to the DRB is also a mapping of the QoS flow to the E-RAB.

[0345] The destination base station central unit control plane entity can decide to use the same DRB configuration as the source base station or a different DRB configuration. If the destination base station central unit control plane entity decides to use the same DRB configuration as the source base station, it sends the DRB configuration information to the destination base station central unit user plane entity. If the destination base station central unit control plane entity decides to use a different DRB configuration than the source base station, in addition to the destination DRB configuration information, it also needs to send the source DRB configuration information to the destination base station central unit user plane entity. The destination base station central unit control plane entity sends the information to the destination base station central unit user plane entity through a bearer context establishment request message or a bearer context modification request message. The specific sending method is the same as in step 1502, and will not be repeated here.

[0346] As previously mentioned, if the destination base station central unit control plane entity determines to use the same QoS flow to DRB mapping as the source base station, it sends the mapping relationship to the destination base station central unit user plane entity. The destination base station central unit control plane entity sends the mapping relationship to the destination base station central unit user plane entity via a bearer context establishment request message or a bearer context modification request message. The destination base station central unit control plane entity sends the mapping relationship to the destination base station central unit user plane entity via the QoS flow(s) information to be established contained in the DRB to be established in the bearer context establishment request message or the bearer context modification request message. The DRB to be established is either a DRB to be established contained in the PDU session resource establishment list in the bearer context establishment request message or a DRB to be established contained in the PDU session resource establishment list (also called the PDU session resource establishment modification list) in the bearer context modification request message. For EN-DC to SA handover where the source base station and destination base station are shared, the destination base station central unit control plane entity can send the mapping relationship to the destination base station central unit user plane entity through the QoS flow(s) information to be established contained in the DRB to be established in the bearer context modification request message.

[0347] If the destination base station central unit control plane entity determines a different QoS flow to DRB mapping than the source base station, to ensure no data loss during handover, the destination base station central unit control plane entity temporarily configures the same QoS flow to DRB mapping as the source base station for processing data forwarded by the source base station. The destination QoS flow to DRB mapping determined by the destination base station central unit control plane entity is used by the destination base station central unit user plane entity to process new data received from the core network.

[0348] The destination base station central unit control plane entity sends the source QoS flow to DRB mapping and the destination QoS flow to DRB mapping to the destination base station central unit user plane entity. The DRB information to be established sent by the destination base station central unit control plane entity to the destination base station central unit user plane entity includes the destination QoS flow information to be established and / or the source QoS flow information to be established. The destination QoS flow information includes one or more QoS flows mapped from the destination to the DRB. The source QoS flow information includes one or more QoS flows mapped from the source to the DRB. If the DRB information to be established only contains the destination QoS flow information, it indicates that the DRB is only used to process new data from the core network, and the source does not use the corresponding DRB. If the DRB information to be established only contains the QoS flow information to be established at the source end, it means that the DRB is only used to process the data forwarded from the source base station, and the destination end does not use the corresponding DRB. After the user plane entity of the destination base station central unit receives the end marker data packet, the DRB can be released.

[0349] The QoS flow information to be established at the destination can be represented by the existing QoS flow information to be established in the DRB information to be established in the interface message between the base station central unit control plane entity and the base station central unit user plane entity. This requires defining a new information element (IE), such as the source QoS flow information to be established or the old QoS flow information to be established, to represent the source mapping information or the source QoS flow information to be established. The existing QoS flow information to be established in the DRB information to be established is a required field. In order to indicate that a certain DRB is an old DRB of the source and is not used by the destination, the DRB information to be established only needs to include the source QoS flow information to be established or the old QoS flow information to be established, that is, the QoS flow information mapped from the source to the DRB. To handle this situation, the specific method is the same as in step 1502, and will not be repeated here.

[0350] The existing QoS Flow information to be established in the DRB information to be established in the interface messages between the base station central unit control plane entity and the base station central unit user plane entity can be used to represent the QoS flow information to be established at the source. This requires defining a new information element (IE), such as the destination QoS flow information or a new QoS flow information to be established, to represent the mapping information or the QoS flow information to be established at the destination. The existing QoS Flow information to be established in the DRB information to be established is a mandatory field. To indicate that a certain DRB is the destination DRB, the DRB information to be established only needs to include the destination QoS flow information or the new QoS flow information to be established, i.e., the QoS flow information mapped from the destination to the DRB. To handle this situation, the specific method is the same as in step 1502, and will not be repeated here.

[0351] The DRB information to be modified, sent by the Destination Base Station Central Unit (DNU) Control Plane Entity to the DNU User Plane Entity, includes destination flow mapping information and / or source flow mapping information. The destination flow mapping information includes one or more QoS flows mapped from the destination to the DRB. The source flow mapping information includes one or more QoS flows mapped from the source to the DRB. If the DRB information to be modified only contains destination flow mapping information, it indicates that the DRB is only used to process new data from the core network, and the source end does not use the corresponding DRB. If the DRB information to be modified only contains source flow mapping information, it indicates that the DRB is only used to process data forwarded from the source base station, and the destination end does not use the corresponding DRB. The DRB can be released by the DNU User Plane Entity upon receiving the end marker data packet.

[0352] The existing flow mapping information in the DRB information to be modified in the interface message of the base station central unit control plane entity and the base station central unit user plane entity can be used to represent the QoS flow(s) of the destination end mapped to the DRB. This requires defining a new information element (IE), such as source flow mapping information or old flow mapping information, to represent the QoS flow(s) of the source end mapped to the DRB.

[0353] The existing flow mapping information in the DRB information to be modified in the interface message of the base station central unit control plane entity and the base station central unit user plane entity can be used to represent the QoS flow(s) of the source end mapped to the DRB. This requires defining a new information element (IE), such as destination flow mapping information or new flow mapping information, to represent the QoS flow(s) of the destination end mapped to the DRB.

[0354] The destination base station central unit control plane entity can send the above information to the destination base station central unit user plane entity using a bearer context establishment request, a bearer context modification request message, or other messages. The DRB to be established is either a DRB included in the PDU session resource establishment list in the bearer context establishment request message or a DRB included in the PDU session resource establishment list (also called the PDU session resource establishment modification list) in the bearer context modification request message. For EN-DC to SA handover where the source and destination base stations are shared, the destination base station central unit control plane entity can send the above information to the destination base station central unit user plane entity by including it in the DRB to be established in the bearer context modification request message.

[0355] This concludes the description of the handover support method 1600 of the present invention. This method ensures correct processing between the control plane and user plane of the destination base station central unit, even when the destination base station uses a different QoS flow to DRB mapping than the source base station. This avoids data loss, improves data transmission efficiency, and enhances the reliability of data forwarding during handover.

[0356] Figure 17 This is an exemplary flowchart illustrating a method 1700 for supporting handover according to an embodiment of the present invention. The method 1700 can be used for intra-system handover or inter-system handover and can be executed on the user plane entity side of the source base station central unit. The method includes the following steps.

[0357] like Figure 17 As shown, in method 1700, in step S1701, source-end DRB configuration information and destination-end DRB configuration information are received from the destination base station central unit control plane entity. And / or, the mapping of source-end QoS flow to data radio bearer DRB and the mapping of destination-end QoS flow to DRB are received from the destination base station central unit control plane entity.

[0358] In step S1702, the forwarded data received from the source base station is processed using the source DRB configuration and / or the source QoS flow to DRB mapping, and the new data received from the core network is processed using the destination DRB configuration and / or the destination QoS flow to DRB mapping.

[0359] The similarities between Method 1700 and Methods 1500 and 1600 will not be repeated here.

[0360] This concludes the description of the handover support method 1700 of the present invention. This method ensures correct processing between the control plane and user plane of the destination base station central unit, even when the destination base station uses a different QoS flow to DRB mapping than the source base station. This avoids data loss, improves data transmission efficiency, and enhances the reliability of data forwarding during handover.

[0361] Figure 18 An exemplary flowchart of a method 1800 for supporting handover according to an embodiment of the present invention is shown. The method 1800 can be used for intra-system handover or inter-system handover. The method includes the following steps.

[0362] In step S1801, the destination base station central unit control plane entity receives a handover request message from either the source base station or the core network. The handover request message received from the source base station is an application layer message from the inter-base station interface, such as an XnAP message. The handover request message received from the core network is an application layer message from the base station and core network interface, such as an NGAP message. The handover request message contains the UE's configuration information at the source base station, including DRB configuration information and / or a mapping of QoS flow to the DRB.

[0363] The destination base station central unit control plane entity determines the mapping of DRB configuration information and / or QoS Flow to DRB at the destination end.

[0364] The target base station central unit control plane entity can decide to use the same DRB configuration as the source end or a different DRB configuration.

[0365] If the destination base station central unit control plane entity decides to use the same DRB configuration and the same QoS flow mapping to the DRB as the source base station, it sends the information to the destination base station central unit user plane entity via the DRB to be established and the QoS flow information to be established on the DRB. The destination base station central unit control plane entity sends the information to the destination base station central unit user plane entity via a bearer context establishment request message. The destination base station central unit control plane entity sends the mapping relationship to the destination base station central unit user plane entity via the QoS flow(s) information to be established contained in the DRB to be established in the bearer context establishment request message.

[0366] If the destination base station central unit control plane entity decides to use the same QoS flow to DRB mapping as the source base station, it sends the mapping relationship to the destination base station central unit user plane entity. The destination base station central unit control plane entity sends the mapping relationship to the destination base station central unit user plane entity via a bearer context establishment request message. The destination base station central unit control plane entity also sends the mapping relationship to the destination base station central unit user plane entity via the QoS flow(s) information to be established contained in the DRB to be established within the bearer context establishment request message.

[0367] If the destination base station central unit control plane entity decides to use a different DRB configuration and / or a different QoS flow-to-DRB mapping than the source base station, in order to ensure no data loss during handover, the destination base station central unit control plane entity temporarily configures the same DRB configuration and / or QoS flow-to-DRB mapping as the source base station to process data forwarded by the source base station. The destination DRB configuration and / or QoS flow-to-DRB mapping determined by the destination base station central unit control plane entity are used by the destination base station central unit user plane entity to process new data received from the core network.

[0368] This invention provides two methods for notifying the UE of mapping relationships. One method involves the destination base station central element control plane entity directly including the destination DRB configuration and / or QoS Flow to DRB mapping in the handover command message, which is then sent to the UE via the source base station. The other method involves the destination base station central element control plane entity including the source DRB configuration and / or QoS Flow to DRB mapping in the handover command message, which is also sent to the UE via the source base station. Subsequently, the destination base station central element control plane entity sends a Radio Resource Control (RRC) reconfiguration message to the UE, containing the destination-determined DRB configuration and / or QoS Flow to DRB mapping. When the destination base station central element user plane entity receives the end marker, it sends an indication message to the destination base station central element control plane entity. The destination base station central element control plane entity then sends the destination-determined DRB configuration and / or QoS Flow to DRB mapping to the UE via the RRC reconfiguration message.

[0369] In step S1802, the destination base station central unit control plane entity sends the source-end DRB configuration and / or QoS Flow to DRB mapping to the destination base station central unit user plane entity. The DRB information to be established sent by the destination base station central unit control plane entity to the destination base station central unit user plane entity includes the QoS flow information to be established. The QoS flow information to be established in the DRB information is set according to the source-end QoS flow to DRB mapping. The configuration of the DRB to be established is the source-end configuration. The destination base station central unit control plane entity can send this information to the destination base station central unit user plane entity via a bearer context establishment request message or other messages.

[0370] In step S1803, the user plane entity of the destination base station central unit receives the information described in step S1802 from the control plane entity of the destination base station central unit. The user plane entity of the destination base station central unit saves the received information.

[0371] For the DRB requesting data forwarding, the user plane entity of the destination base station central unit allocates channel information for data forwarding and sends it to the control plane entity of the destination base station central unit.

[0372] The interaction between the target base station central unit control plane entity and the gNB-DU can be achieved through the following two methods:

[0373] Method 1: The destination base station central unit control plane entity sends a UE context establishment request message to the destination base station distribution unit (gNB-DU). This message includes the configuration of the source DRB. Corresponding to the source DRB, the DRB to be established includes the QoS flow(s) mapped from the source DRB to the source DRB. If the destination uses the same DRB configuration and the same QoS flow to DRB mapping as the source DRB, the DRB to be established includes the QoS flow(s) mapped to the source DRB. If the destination uses the same DRB configuration as the source DRB but a different QoS flow to DRB mapping, the DRB to be established may include the QoS flow(s) mapped from the source DRB. The gNB-DU allocates a downlink transport layer address and channel identifier for each DRB to be established. The gNB-DU sends a UE context establishment response message to the destination base station central unit control plane entity, this message containing the downlink transport layer address and channel identifier allocated by the gNB-DU for each DRB. The base station central unit control plane entity sends the downlink transport layer address and channel identifier assigned by the gNB-DU for each DRB to the destination base station central unit user plane entity.

[0374] Method 2: The destination base station central unit control plane entity sends a UE context establishment request message to the destination base station distribution unit (gNB-DU). This message includes the source DRB configuration and the destination-determined DRB configuration. For the source DRB, the DRB to be established includes the QoS flow(s) mapped to the source DRB. For a new DRB determined at the destination, the DRB to be established includes the QoS flow(s) mapped to the destination DRB determined by the destination base station central unit control plane entity. If the destination uses the same DRB configuration and the same QoS flow to DRB mapping as the source, the DRB to be established includes the QoS flow(s) mapped to the DRB. If the destination uses the same DRB configuration but a different QoS flow to DRB mapping as the source, the DRB to be established may include the source-mapped QoS flow(s) and / or the destination-mapped QoS flow(s). The gNB-DU assigns a downlink transport layer address and channel identifier to each DRB to be established. The gNB-DU sends a UE context establishment response message to the destination base station central unit control plane entity. This message includes the downlink transport layer address and channel identifier assigned by the gNB-DU for each DRB. The base station central unit control plane entity then sends the downlink transport layer address and channel identifier assigned by the gNB-DU for each DRB to the destination base station central unit user plane entity. The destination base station central unit user plane entity receives the data forwarded from the source base station and processes the forwarded data using the received QoS flow to DRB mapping.

[0375] After receiving the end marker, the destination base station can send an indication message indicating the end of data forwarding to the control plane entity of the destination base station central unit.

[0376] Step S1804: The destination base station central unit control plane entity sends the destination DRB configuration and / or the destination QoS flow mapping to the DRB to the destination base station central unit user plane entity.

[0377] The DRB information to be established, sent by the destination base station central unit control plane entity to the destination base station central unit user plane entity, includes QoS flow information to be established. This QoS flow information is configured according to the mapping from the destination's QoS flow to the DRB. The configuration of the DRB to be established is the configuration of the destination. The DRB information to be modified, sent by the destination base station central unit control plane entity to the destination base station central unit user plane entity, includes destination flow mapping information. This destination flow mapping information includes one or more QoS flows mapped from the destination to the DRB. The destination base station central unit control plane entity can send this information to the destination base station central unit user plane entity via a bearer context modification request, a bearer context establishment request message, or other messages.

[0378] The method for the destination base station central unit user plane entity to send an indication message indicating the end of forwarding data to the destination base station central unit control plane entity after receiving the end marker includes: the destination base station central unit control plane entity sending the destination DRB configuration and / or the destination QoS flow to DRB mapping to the destination base station central unit user plane entity; and the destination base station central unit control plane entity sending an RRC reconfiguration message to the UE, sending the destination-determined DRB configuration and / or QoS flow to DRB mapping to the UE.

[0379] The DRB information used at the source end but not at the destination end is deleted from the user plane entity of the destination base station center unit.

[0380] In the first interaction method between the destination base station central unit control plane entity and the gNB-DU, the destination base station central unit control plane entity sends a UE context modification request message to the destination gNB-DU. This message contains the DRB configuration determined at the destination. For the new DRB determined at the destination, the DRB to be established contains the QoS flow(s) mapped onto the DRB determined by the destination base station central unit control plane entity. If the destination uses the same DRB configuration as the source but a different QoS flow mapping to the DRB, the DRB to be modified may contain the QoS flow(s) mapped onto the DRB by the destination. The gNB-DU allocates a downlink transport layer address and channel identifier for each DRB to be established. The gNB-DU releases the old DRB configuration, which is the source DRB configured to handle forwarded data. The gNB-DU sends a UE context modification response message to the destination base station central unit control plane entity, this message containing the downlink transport layer address and channel identifier allocated by the gNB-DU for each DRB. The base station central unit control plane entity sends the downlink transport layer address and channel identifier assigned by the gNB-DU for each DRB to the destination base station central unit user plane entity.

[0381] The second interaction method between the target base station central unit control plane entity and the gNB-DU, and the release process of the old DRB on the gNB-DU are as follows: Figure 23 The method described or as follows. The old DRB is the source-side DRB, configured to handle forwarded data.

[0382] If no new data is received on a DRB within a certain period of time, the gNB-DU sends a UE context modification request message to the destination base station central unit control plane entity. This message contains an identifier indicating that the DRB needs to be released. Upon receiving this message, the destination base station central unit control plane entity can release the old DRB.

[0383] In step S1805, the user plane entity of the destination base station central unit receives the information described in step S1804 from the control plane entity of the destination base station central unit. The user plane of the destination base station central unit processes the new data received from the core network using the newly received QoS flow to DRB mapping and sends it to the UE via gNB-DU.

[0384] This concludes the description of the handover support method 1800 of the present invention. This method ensures correct processing of the target base station's central unit control plane, user plane, and gNB-DU, even when the target base station uses a different DRB configuration and / or a different QoS flow to DRB mapping than the source base station. This avoids data loss, improves data transmission efficiency, and enhances the reliability of data forwarding during handover.

[0385] Figure 19 This is an exemplary flowchart illustrating a method 1900 for supporting handover according to an embodiment of the present invention. The method 1900 can be used for intra-system handover or inter-system handover and can be executed on the control plane entity side of the destination base station central unit. The method includes the following steps.

[0386] like Figure 19 As shown, in method 1900, in step S1901, a handover request message is received from the source base station or from the core network.

[0387] In step S1902, the source-end QoS flow mapping to the data radio bearer (DRB) is sent to the user plane entity of the destination base station central unit. The user plane entity of the destination base station central unit uses the received source-end QoS flow mapping to the DRB to process the forwarded data received from the source base station.

[0388] In step S1903, a destination QoS flow to DRB mapping is sent to the user plane entity of the base station central unit, wherein the destination base station central unit user plane uses the newly received QoS flow to DRB mapping to process new data received from the core network and send it to the user equipment UE.

[0389] Method 1900 is similar to Method 1800, and the parts that are repeated will not be repeated here.

[0390] This concludes the description of the handover support method 1900 of the present invention. This method ensures correct processing between the control plane and user plane of the destination base station central unit, even when the destination base station uses a different QoS flow to DRB mapping than the source base station. This avoids data loss, improves data transmission efficiency, and enhances the reliability of data forwarding during handover.

[0391] Figure 20 This is an exemplary flowchart illustrating a method 2000 for supporting handover according to an embodiment of the present invention. The method 2000 can be used for intra-system handover or inter-system handover, and can be executed at the user plane entity side of the destination base station central unit. The method includes the following steps.

[0392] like Figure 20As shown, in method 2000, in step S2001, the source end service quality assurance (QoS) flow is received from the destination base station central unit control plane entity and mapped to the data radio bearer (DRB).

[0393] In step S2002, the forwarded data received from the source base station is processed using the received source QoS flow to DRB mapping.

[0394] In step S2003, the mapping of the destination QoS flow to the DRB is received from the destination base station central unit control plane entity.

[0395] In step S2004, the newly received QoS flow to DRB mapping is used to process the new data received from the core network and send it to the user equipment (UE).

[0396] Method 2000 is similar to Methods 1800 and 1900, and the parts that are repeated will not be described again.

[0397] This concludes the description of the handover support method 2000 of the present invention. This method ensures correct processing between the control plane and user plane of the destination base station central unit, even when the destination base station uses a different QoS flow to DRB mapping than the source base station. This avoids data loss, improves data transmission efficiency, and enhances the reliability of data forwarding during handover.

[0398] Figure 21 An exemplary flowchart of a method 2100 for supporting handover according to an embodiment of the present invention is shown. The method 2100 can be used for intra-system handover or inter-system handover. The method includes the following steps.

[0399] In step S2101, the target base station central unit control plane entity receives a handover request message from either the source base station or the core network. The handover request message received from the source base station is an application layer message from the inter-base station interface, such as an XnAP message. The handover request message received from the core network is an application layer message from the base station and core network interface, such as an NGAP message. The handover request message contains the UE's configuration information at the source base station, including DRB configuration information and / or a mapping of QoS flow to the DRB.

[0400] The destination base station central unit control plane entity determines the mapping of DRB configuration information and / or QoS Flow to DRB at the destination end.

[0401] This invention provides two methods for notifying the UE of mapping relationships. One method involves the destination base station central control plane entity directly including the destination DRB configuration information and / or the mapping from the destination QoS Flow to the DRB in the handover command message, which is then sent to the UE via the source base station. The other method involves the destination base station central control plane entity including the source DRB configuration information and / or the mapping from the source QoS Flow to the DRB in the handover command message, which is also sent to the UE via the source base station. Subsequently, the destination base station central control plane entity sends a Radio Resource Control (RRC) reconfiguration message to the UE, containing the destination-determined DRB configuration information and / or the mapping from the destination QoS Flow to the DRB. The destination base station central control plane entity can determine when to send the RRC reconfiguration message to the UE, depending on the implementation.

[0402] Step S2102 is the same as step S1802, and will not be repeated here.

[0403] In step S2103, the user plane entity of the destination base station central unit receives the information from the control plane entity of the destination base station central unit. The user plane entity of the destination base station central unit stores the received information.

[0404] For the DRB requesting data forwarding, the user plane entity of the destination base station central unit allocates channel information for data forwarding and sends it to the control plane entity of the destination base station central unit.

[0405] The interaction method between the target base station central unit control plane entity and the gNB-DU is the same as described in step 1803, and will not be repeated here.

[0406] The destination base station central unit user plane entity receives data forwarded from the source base station, and uses the received mapping to process the forwarded data received from the source base station.

[0407] In step S2104, the destination base station central unit control plane entity sends the destination DRB configuration and / or the destination QoS flow to the DRB mapping to the destination base station central unit user plane entity and sends indication information.

[0408] The DRB information to be established sent by the destination base station central unit control plane entity to the destination base station central unit user plane entity includes QoS flow information to be established. The QoS flow information to be established in the DRB information is set according to the mapping from the destination QoS flow to the DRB. The DRB information to be modified sent by the destination base station central unit control plane entity to the destination base station central unit user plane entity includes destination flow mapping information. The destination flow mapping information includes one or more QoS flows mapped from the destination to the DRB. The destination base station central unit control plane entity can send this information to the destination base station central unit user plane entity via a bearer context modification request, a bearer context establishment request message, or other messages.

[0409] The destination base station central unit control plane entity sends an RRC reconfiguration message to the UE, sending the destination-determined DRB configuration and / or QoS Flow to DRB mapping to the UE.

[0410] In step S2105, the destination base station central unit user plane entity receives the information from the destination base station central unit control plane entity in step S2104. The destination base station central unit user plane entity does not delete the old mapping relationships at the source end, nor does it delete the DRBs temporarily used at the source end for processing forwarded data but not at the destination end. Based on the received instruction information, the destination base station central unit user plane entity does not delete the old mapping relationships at the source end and / or does not delete the DRBs temporarily used for processing forwarded data but not at the destination end. The destination base station central unit user plane entity processes the data forwarded from the source base station using the previously received mapping from the source end QoS flow to the DRB.

[0411] After receiving the end marker, the destination base station central unit user plane entity deletes the old mapping relationships at the source end and / or deletes DRBs temporarily used for processing forwarded data but not used at the destination end. The destination base station central unit user plane entity processes the new data received from the core network using the newly received QoS flow to DRB mapping. The destination base station central unit user plane entity transmits the data received from the core network to the UE via gNB-DU.

[0412] The release process of the old DRB on the gNB-DU is as follows: Figure 25 The method described or as follows. The old DRB is the source-side DRB, configured to handle forwarded data.

[0413] If no new data is received on a DRB within a certain period of time, the gNB-DU sends a UE context modification request message to the destination base station central unit control plane entity. This message contains an identifier indicating that the DRB needs to be released. Upon receiving this message, the destination base station central unit control plane entity can release the old DRB.

[0414] This concludes the description of the handover support method 2100 of the present invention. This method ensures correct processing of the target base station central unit control plane, target base station central unit user plane, and gNB-DU, even when the target base station uses a different DRB configuration and / or a different QoS flow to DRB mapping than the source base station. This avoids data loss, improves data transmission efficiency, and enhances the reliability of data forwarding during handover.

[0415] Figure 22 This is an exemplary flowchart illustrating a method 2200 for supporting handover according to an embodiment of the present invention. The method 2200 can be used for intra-system handover or inter-system handover, and can be executed on the control plane entity side of the destination base station central unit. The method includes the following steps.

[0416] like Figure 22 As shown, in method 2200, in step S2201, a handover request message is received from the source base station or the core network.

[0417] In step S2202, the source QoS Flow to DRB mapping is sent to the destination base station central unit user plane entity, wherein the destination base station central unit user plane entity uses the received mapping to process the forwarded data received from the source base station.

[0418] In step S2203, the destination QoS flow to DRB mapping is sent to the destination base station central unit user plane entity and indication information is sent. The base station central unit user plane entity uses the newly received destination QoS flow to DRB mapping to process the new data received from the core network.

[0419] Method 2200 is similar to Method 2100, and the repetitions will not be repeated.

[0420] This concludes the description of the handover support method 2200 of the present invention. This method ensures correct processing between the control plane and user plane of the destination base station central unit, even when the destination base station uses a different QoS flow to DRB mapping than the source base station. This avoids data loss, improves data transmission efficiency, and enhances the reliability of data forwarding during handover.

[0421] Figure 23This is an exemplary flowchart illustrating a method 2300 for supporting handover according to an embodiment of the present invention. The method 2300 can be used for intra-system handover or inter-system handover, and can be executed at the user plane entity side of the destination base station central unit. The method includes the following steps.

[0422] like Figure 23 As shown, in method 2300, in step S2301, the source service quality assurance (QOS) flow is received from the destination base station central unit control plane entity and mapped to the data radio bearer (DRB).

[0423] In step S2302, the forwarded data received from the source base station is processed using the received source QoS flow to DRB mapping.

[0424] In step S2303, the target QoS flow to DRB mapping and indication information is received from the target base station central unit control plane entity.

[0425] In step S2304, the newly received destination QoS flow to DRB mapping is used to process the new data received from the core network, wherein, according to the received indication information, the old mapping relationship at the source end is not deleted and / or the DRB temporarily used for processing forwarded data but not used at the destination end is not deleted.

[0426] Method 2300 is similar to Method 2100 and Method 2200, and the repetitions will not be repeated.

[0427] This concludes the description of the handover support method 2300 of the present invention. This method ensures correct processing between the control plane and user plane of the destination base station central unit, even when the destination base station uses a different QoS flow to DRB mapping than the source base station. This avoids data loss, improves data transmission efficiency, and enhances the reliability of data forwarding during handover.

[0428] Figure 24 An exemplary flowchart of a method 2400 for supporting handover according to an embodiment of the present invention is shown. The method 2400 can be used for intra-system handover or inter-system handover. The method includes the following steps.

[0429] In step S2401, the destination base station central unit control plane entity receives a handover request message from either the source base station or the core network. The handover request message received from the source base station is an application layer message from the inter-base station interface, such as an XnAP message. The handover request message received from the core network is an application layer message from the base station and core network interface, such as an NGAP message. The handover request message contains the UE's configuration information at the source base station, including DRB configuration information and / or a mapping of QoS flow to the DRB.

[0430] The destination base station central unit control plane entity determines the mapping of DRB configuration information and / or QoS Flow to DRB at the destination end.

[0431] This invention provides two methods for notifying the UE of mapping relationships. One method involves the destination base station central control plane entity directly including the destination DRB configuration information and / or the mapping from the destination QoS Flow to the DRB in the handover command message, which is then sent to the UE via the source base station. The other method involves the destination base station central control plane entity including the source DRB configuration information and / or the mapping from the source QoS Flow to the DRB in the handover command message, which is also sent to the UE via the source base station. Subsequently, the destination base station central control plane entity sends a Radio Resource Control (RRC) reconfiguration message to the UE, containing the destination-determined DRB configuration information and / or the mapping from the destination QoS Flow to the DRB. The destination base station central control plane entity can determine when to send the RRC reconfiguration message to the UE, depending on the implementation.

[0432] Step S2402 is the same as step S1802, and will not be repeated here.

[0433] In step S2403, the user plane entity of the destination base station central unit receives the information from the control plane entity of the destination base station central unit. The user plane entity of the destination base station central unit stores the received information.

[0434] For the DRB requesting data forwarding, the user plane entity of the destination base station central unit allocates channel information for data forwarding and sends it to the control plane entity of the destination base station central unit.

[0435] The interaction method between the target base station central unit control plane entity and the gNB-DU is the same as described in step S1803, and will not be repeated here.

[0436] The destination base station central unit user plane entity receives data forwarded from the source base station, and uses the received mapping to process the forwarded data received from the source base station.

[0437] In step S2404, the destination base station central unit control plane entity sends the destination DRB configuration and / or the destination QoS flow to DRB mapping to the destination base station central unit user plane entity.

[0438] The DRB information to be established sent by the destination base station central unit control plane entity to the destination base station central unit user plane entity includes QoS flow information to be established. The QoS flow information to be established in the DRB information is set according to the mapping from the destination QoS flow to the DRB. The DRB information to be modified sent by the destination base station central unit control plane entity to the destination base station central unit user plane entity includes destination flow mapping information. The destination flow mapping information includes one or more QoS flows mapped from the destination to the DRB. The destination base station central unit control plane entity can send this information to the destination base station central unit user plane entity via a bearer context modification request, a bearer context establishment request message, or other messages.

[0439] The destination base station central unit control plane entity sends an RRC reconfiguration message to the UE, sending the destination-determined DRB configuration and / or QoS Flow to DRB mapping to the UE.

[0440] In step S2405, the destination base station central unit user plane entity receives the information described in step S2404 from the destination base station central unit control plane entity. The destination base station central unit user plane entity does not delete the old mapping relationship at the source end, nor does it delete the DRB temporarily used at the source end for processing forwarded data but not at the destination end. The destination base station central unit user plane entity processes the data forwarded from the source base station using the previously received mapping from the source end QoS flow to the DRB.

[0441] After receiving the end marker, the destination base station central unit user plane entity deletes the old mapping relationships at the source end and / or deletes DRBs temporarily used for processing forwarded data but not used at the destination end. The destination base station central unit user plane entity processes the new data received from the core network using the newly received DRB configuration and / or QoS flow to DRB mapping. The destination base station central unit user plane entity transmits the data received from the core network to the UE via gNB-DU.

[0442] The release process of the old DRB on the gNB-DU is as follows: Figure 25 The method described or as follows. The old DRB is the source-end DRB, and the destination-end configuration is for processing forwarded data.

[0443] If no new data is received on a DRB within a certain period of time, the gNB-DU sends a UE context modification request message to the destination base station central unit control plane entity. This message contains an identifier indicating that the DRB needs to be released. Upon receiving this message, the destination base station central unit control plane entity can release the old DRB.

[0444] This concludes the description of the handover support method 2400 of the present invention. This method ensures correct processing of the destination base station central unit control plane, destination base station central unit user plane, and gNB-DU, even when the destination base station uses a different DRB configuration and / or a different QoS flow to DRB mapping than the source base station. This avoids data loss, improves data transmission efficiency, and enhances the reliability of data forwarding during handover.

[0445] Figure 25 An exemplary flowchart of a method 2500 for supporting handover according to an embodiment of the present invention is shown. The method 2500 can be used for inter-system handover or intra-system handover. The method includes the following steps.

[0446] In step S2501, the user plane entity of the destination base station central unit receives the data forwarding end flag data packet.

[0447] In step S2502, the user plane entity of the destination base station central unit sends a data forwarding end indication message to the control plane entity of the destination base station central unit. The user plane entity of the destination base station central unit may send the data forwarding end indication message to the control plane entity of the destination base station central unit after receiving the end flag data packets of the DRBs for all data forwarding.

[0448] In step S2503, the destination base station central unit control plane entity receives the data forwarding end indication information. The destination base station central unit control plane entity sends a message to the destination gNB-DU requesting the release of the old DRB. The old DRB is the source DRB, configured to process forwarded data. The destination base station central unit control plane entity can request the gNB-DU to release the old DRB through a UE context modification message or other messages.

[0449] The gNB-DU receives the information from the destination base station central unit control plane entity. The gNB-DU releases the old DRB. The gNB-DU sends a response message to the destination base station central unit control plane entity.

[0450] This concludes the description of the handover method 2500 of the present invention. This method allows the gNB-DU to promptly release unnecessary DRBs, saving radio resources and increasing system capacity or the ability to serve more users.

[0451] Figure 26 An exemplary flowchart of a handover support method 2600 according to an embodiment of the present invention is shown. The method 2600 can be used for inter-system handover or intra-system handover, and can be executed on the control plane entity side of the destination base station central unit. The method includes the following steps.

[0452] In step S2601, the source base station central unit control plane entity receives the handover command message.

[0453] The handover command message includes an E-RAB identifier for data forwarding and data forwarding channel information. During the PDU session establishment process, the source base station central unit control plane entity receives from the core network the PDU session to be established, information on one or more QoS flows in the PDU session, and the E-RAB identifier mapped to the QoS flows. The source base station central unit control plane entity stores the E-RAB identifier mapped to the QoS flows.

[0454] In step S2602, the source base station central unit control plane entity sends a bearer context modification request message to the source base station central unit user plane entity.

[0455] The message contains data forwarding information for switching to E-UTRAN or inter-system handover data forwarding information. This information element (i.e., data forwarding information for switching to E-UTRAN or inter-system handover data forwarding information) can also have other names or be named in other ways without departing from the scope of the invention. The purpose of this information element is to notify the source base station central unit user plane entity of the data forwarding information. The data forwarding information includes downlink data forwarding information. The downlink data forwarding information includes a transport layer address and a channel identifier. The downlink data forwarding information also includes a list of QoS flows for forwarding data through the data forwarding channels. The transport layer address and channel identifier are the data forwarding channel information allocated by the destination base station to each E-RAB, received by the source base station central unit control plane entity in the handover command message. During PDU session establishment, the source base station central unit control plane entity receives the E-RAB identifier mapped to each QoS flow from the core network, thus knowing the QoS flow(s) for forwarding data through each E-RAB channel. The downlink data forwarding information may also include a DRB identifier. For inter-system handover, the DRB identifier corresponds to each E-RAB identifier, and can be the same as or have a one-to-one correspondence with E-RAB identifiers. The downlink data forwarding information may also include E-RAB identifiers.

[0456] In step S2603, the source base station central unit user plane entity receives a message from the source base station central unit control plane entity. The source base station central unit user plane entity stores the information in the received message. The source base station central unit user plane entity forwards data according to the received information. The information may be, for example, data forwarding information for handover to E-UTRAN or inter-system handover data forwarding information.

[0457] The source base station forwards the data for each QoS flow through the corresponding channel. The source base station's central unit user plane entity, based on new information elements in the received message, switches to E-UTRAN data forwarding information or inter-system handover data forwarding information to determine if it's an inter-system handover, and therefore does not include the SDAP header in the forwarded data packets. The source base station's central unit user plane entity forwards PDCP SDUs without the SDAP header.

[0458] For intra-system handover, the data packets forwarded by the source base station central unit user plane entity on the channel corresponding to each DRB, i.e., the PDCP SDU, can contain SDAP headers.

[0459] This concludes the description of the handover support method 2600 of the present invention. This method allows the source base station's central unit user plane entity to correctly forward data to the destination base station even when the number of E-RABs used by the destination base station differs from the number of DRBs used by the source NG-RAN. The source base station's central unit user plane entity can forward QoS flow data packets to the correct E-RAB channels, and can forward data packets without SDAP headers for inter-system handover, avoiding impact on the destination E-UTRAN base station, ensuring the correct data packet transmission, preventing data loss, improving data transmission efficiency, and enhancing the reliability of data forwarding during handover.

[0460] Figure 27 An exemplary flowchart of a handover support method 2700 according to an embodiment of the present invention is shown. The method 2700 can be used for inter-system handover or intra-system handover, and can be executed on the control plane entity side of the destination base station central unit. The method includes the following steps.

[0461] In step S2701, the source base station central unit control plane entity receives the handover command message.

[0462] The handover command message includes an E-RAB identifier for data forwarding and data forwarding channel information. During the PDU session establishment process, the source base station central unit control plane entity receives from the core network the PDU session to be established, information on one or more QoS flows in the PDU session, and the E-RAB identifier mapped to the QoS flows. The source base station control plane entity stores the E-RAB identifier mapped to the QoS flows.

[0463] In step S2702, the source base station central unit control plane entity sends a bearer context modification request message to the source base station central unit user plane entity. The source base station central unit control plane entity notifies the source base station central unit user plane entity of the data forwarding channel information and the QoS flow information forwarded on each channel through the DRB information to be established and / or the DRB information to be modified in the message.

[0464] The source base station central unit control plane entity notifies the source base station central unit user plane entity of the data forwarding channel information and the QoS flow information forwarded on each channel through the DRB information to be established and / or the DRB information to be modified in the PDU session resource modification item of the message.

[0465] If a DRB has been configured in the user plane entity of the source base station central unit during PDU session establishment, the source base station central unit control plane entity sends the transport layer address and channel identifier allocated by the destination base station through the DRB data forwarding information in the DRB modification item, and sends the QoS flow(s) of forwarding data on the channel corresponding to the DRB through the flow mapping information in the DRB modification item. The DRB modification item contains the DRB identifier.

[0466] When the number of E-RABs at the destination base station exceeds the number of DRBs at the source base station, and no DRB is configured in the user plane entity of the source base station's central unit during PDU session establishment, the source base station's central unit control plane entity sends the transport layer address and channel identifier allocated by the destination base station to the source base station's central unit user plane entity by adding information elements, namely DRB data forwarding information, to the DRB establishment item. It also sends the QoS flow(s) for forwarding data on the corresponding DRB's channel to the source base station's central unit user plane entity through the QoS flow information to be established in the DRB establishment item. The DRB establishment item contains the DRB identifier.

[0467] For inter-system handover, the DRB identifier corresponds to each E-RAB identifier, and can be the same as or have a one-to-one correspondence with E-RAB identifiers. The bearer context modification request message also includes inter-system handover indication information. The inter-system handover indication information can be included in the PDU session resource modification information, the DRB information to be modified, or the DRB information to be established.

[0468] The data forwarding information includes downlink data forwarding information. The downlink data forwarding information includes a transport layer address and a channel identifier. The transport layer address and channel identifier are the data forwarding channel information allocated to each E-RAB by the destination base station upon receiving the handover command message from the source base station central unit control plane entity. During the PDU session establishment process, the source base station control plane entity receives the E-RAB identifier mapped to each QoS flow from the core network, thus knowing the QoS flow(s) through which data is forwarded via each E-RAB channel.

[0469] In step S2703, the source base station central unit user plane entity receives a message from the source base station central unit control plane entity. The source base station central unit user plane entity saves the received information. The source base station central unit user plane entity forwards data based on the received information.

[0470] The source base station central unit user plane entity knows the QoS flow(s) forwarded through the channel based on the DRB data forwarding information and flow mapping information of each DRB in the received DRB information to be modified. Alternatively, the source base station central unit user plane entity knows the QoS flow(s) forwarded through the channel based on the DRB data forwarding information of each DRB in the received DRB information to be established and the QoS flow information to be established.

[0471] The source base station forwards data for each QoS flow through the corresponding channel. For inter-system handover, the source base station's central unit user plane entity knows it is an inter-system handover based on the received inter-system handover indication information, and therefore does not include the SDAP header in the forwarded data packets. The source base station's central unit user plane entity forwards PDCPSDUs without the SDAP header. For intra-system handover, the source base station's central unit user plane entity may include the SDAP header in the PDCPSDUs forwarded on the corresponding channel for each DRB.

[0472] This concludes the description of the handover support method 2700 of the present invention. This method allows the source base station's central unit user plane entity to correctly forward data to the destination base station even when the number of E-RABs used by the destination base station differs from the number of DRBs used by the source NG-RAN. The source base station's central unit user plane entity can forward QoS flow data packets to the correct E-RAB channels, and can forward data packets without SDAP headers for inter-system handover, avoiding impact on the destination E-UTRAN base station, ensuring the correct data packets are sent, preventing data loss, improving data transmission efficiency, and enhancing the reliability of data forwarding during handover.

[0473] Figure 28An exemplary flowchart of a handover support method 2800 according to an embodiment of the present invention is shown. The method 2800 can be used for inter-system handover or intra-system handover, and can be executed at the user plane entity side of the destination base station central unit. The method includes the following steps.

[0474] In step S2801, the user plane entity of the source base station central unit receives a bearer context modification request message from the control plane entity of the source base station central unit.

[0475] In step S2802, the source base station central unit user plane entity forwards data based on the information in the received bearer context modification request message.

[0476] Method 2800 is similar to Method 2600, and the parts that are repeated will not be repeated here.

[0477] This concludes the description of the handover support method 2800 of the present invention. This method allows the source base station's central unit user plane entity to correctly forward data to the destination base station even when the number of E-RABs used by the destination base station and the number of DRBs used by the source NG-RAN differs. The source base station's central unit user plane entity can forward QoS flow data packets to the correct E-RAB channels, and can forward data packets without SDAP headers for inter-system handover, avoiding impact on the destination E-UTRAN base station, ensuring the correct data packets are sent, preventing data loss, improving data transmission efficiency, and enhancing the reliability of data forwarding during handover.

[0478] Figure 29 An exemplary flowchart of a handover support method 2900 according to an embodiment of the present invention is shown. The method 2900 can be used for inter-system handover or intra-system handover, and can be executed at the user plane entity side of the destination base station central unit. The method includes the following steps.

[0479] In step S2901, the user plane entity of the source base station central unit receives a bearer context modification request message from the control plane entity of the source base station central unit. The bearer context modification request message uses the data radio bearer (DRB) information to be established and / or the DRB information to be modified in the bearer context modification request message to notify the user plane entity of the data forwarding channel information and the QoS flow information forwarded on each channel.

[0480] In step S2902, the source base station central unit user plane entity forwards data based on the information in the received bearer context modification request message.

[0481] Method 2900 is similar to Method 2700, and the parts that are repeated will not be repeated here.

[0482] This concludes the description of the handover support method 2900 of the present invention. This method allows the source base station's central unit user plane entity to correctly forward data to the destination base station even when the number of E-RABs used by the destination base station differs from the number of DRBs used by the source NG-RAN. The source base station's central unit user plane entity can forward QoS flow data packets to the correct E-RAB channels, and can forward data packets without SDAP headers for inter-system handover, avoiding impact on the destination E-UTRAN base station, ensuring the correct data packets are sent, preventing data loss, improving data transmission efficiency, and enhancing the reliability of data forwarding during handover.

[0483] The preceding references can be used individually or in combination. Figures 3 to 29 The methods described herein are intended to address the data forwarding problem during system-wide or inter-system switching.

[0484] Figure 30 A schematic block diagram of a handover-supporting device 3000 according to an embodiment of the present invention is shown. The device 3000 can be implemented on the base station side. For example, the device 3000 can be implemented to perform the functions described above. Figures 3 to 29 One or more of the methods described.

[0485] like Figure 30 As shown, device 3000 may include transceiver 3001, processor 3002 and memory 3003.

[0486] Transceiver 3001 transmits and receives signals. Memory 3003 stores instructions executable by processor 3002, which, when executed by processor 3002, cause processor 3002 to perform the previously referenced instructions. Figures 3 to 29 One or more of the methods described.

[0487] According to embodiments of the present invention, the aforementioned handover support method and device can solve the problem of coordinated operation between the source base station and the destination base station during handover. Especially when the source base station and / or the destination base station supports control plane and data plane separation, it ensures that the source base station central unit control plane entity, the source base station central unit user plane entity, the destination base station central unit control plane entity, and / or the destination base station central unit user plane entity can operate in complete coordination. This reduces data loss, reduces data interruption time, avoids sending useless data packets over the air interface, improves data forwarding efficiency, and ensures service continuity.

[0488] The above description is merely a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention should be included within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.

Claims

1. A method for supporting switching, comprising: The source base station central unit control plane entity receives the handover command message; as well as The source base station central unit control plane entity sends a bearer context modification request message to the source base station central unit user plane entity. Among them, the user plane entity of the source base station central unit forwards data based on the information in the received bearer context modification request message.

2. The method according to claim 1, wherein, The handover command message includes E-RAB identification information and data forwarding channel information for data forwarding.

3. The method according to claim 1, wherein, The bearer context modification request message includes data forwarding information for switching to the Evolved Universal Terrestrial Radio Access Network (E-UTRAN) or inter-system handover data forwarding information, in order to notify the source base station central unit user plane entity of the data forwarding information.

4. The method according to claim 3, wherein, The data forwarding information includes downlink data forwarding information, which includes a transport layer address and a channel identifier. The transport layer address and channel identifier are the data forwarding channel information allocated to each E-RAB by the destination base station, which is received by the source base station central unit control plane entity in the handover command message.

5. The method according to claim 1, wherein, The source base station central unit user plane entity determines that it is an inter-system handover based on the data forwarding information for switching to E-UTRAN or the inter-system handover data forwarding information, and the forwarded data packets do not contain the Service Data Adaptation Protocol (SDAP) header; or For intra-system handover, the data packets forwarded by the source base station central unit user plane entity on the channel corresponding to each DRB include SDAP headers.

6. The method according to claim 1, wherein, The data radio bearer (DRB) information to be established and / or the DRB information to be modified in the bearer context modification request message is used to notify the source base station central unit user plane entity of the data forwarding channel information and the service quality assurance (QoS) flow information forwarded on each channel.

7. The method according to claim 6, wherein, The bearer context modification request message includes indication information for inter-system handover, and the indication information for inter-system handover may be included in at least one of protocol data unit (PDU) session resource modification information, DRB information to be modified, or DRB information to be established.

8. The method according to claim 7, wherein, When configuring the DRB of the source base station central unit user plane entity during PDU session establishment, the source base station central unit control plane entity sends the transport layer address and channel identifier allocated by the destination base station through the DRB data forwarding information in the DRB modification item, and sends the QoS flow for forwarding data on the channel corresponding to the DRB through the flow mapping information in the DRB modification item. The DRB modification item includes the DRB identifier.

9. The method according to claim 8, wherein, When the DRB of the source base station central unit user plane entity is not configured during the PDU session establishment process, the source base station central unit control plane entity sends the transport layer address and channel identifier allocated by the destination base station to the source base station central unit user plane entity by adding DRB data forwarding information to the DRB establishment item, and sends the QoS flow for forwarding data on the channel corresponding to the DRB to the source base station central unit user plane entity through the QoS flow information to be established in the DRB establishment item. The DRB creation item includes the DRB identifier.

10. The method according to claim 6, wherein, The source base station central unit user plane entity determines the inter-system handover based on the received inter-system handover indication information, and does not include the Service Data Adaptation Protocol (SDAP) header in the forwarded data packets. For intra-system handover, the data packets forwarded by the source base station central unit user plane entity on the channel corresponding to each DRB include SDAP headers.

11. A method for supporting switching, comprising: The user plane entity of the source base station central unit receives the bearer context modification request message from the control plane entity of the source base station central unit. as well as The source base station central unit user plane entity forwards data based on the information in the received bearer context modification request message.

12. The method according to claim 11, wherein, The bearer context modification request message includes data forwarding information for switching to the Evolved Universal Terrestrial Radio Access Network (E-UTRAN) or inter-system handover data forwarding information, in order to notify the source base station central unit user plane entity of the data forwarding information.

13. The method according to claim 11, wherein, The data radio bearer (DRB) information to be established and / or the DRB information to be modified in the bearer context modification request message is used to notify the source base station central unit user plane entity of the data forwarding channel information and the service quality assurance (QoS) flow information forwarded on each channel. as well as The source base station central unit user plane entity forwards data based on the information in the received bearer context modification request message.

14. The method according to claim 13, wherein, The bearer context modification request message includes indication information for inter-system handover, and the indication information for inter-system handover may be included in at least one of protocol data unit (PDU) session resource modification information, DRB information to be modified, or DRB information to be established.

15. A device supporting switching, comprising: Transceiver, used to send and receive signals; processor; as well as A memory storing instructions executable by the processor, which, when executed by the processor, cause the processor to perform the method of any one of claims 1-14.

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