CN108377567B

CN108377567B - Method, device and system for establishing double-connection data transmission under 5G architecture

Info

Publication number: CN108377567B
Application number: CN201710288179.9A
Authority: CN
Inventors: 王弘; 许丽香; 柯小婉
Original assignee: Beijing Samsung Telecommunications Technology Research Co Ltd; Samsung Electronics Co Ltd
Current assignee: Beijing Samsung Telecommunications Technology Research Co Ltd; Samsung Electronics Co Ltd
Priority date: 2016-11-01
Filing date: 2017-04-27
Publication date: 2021-02-23
Anticipated expiration: 2037-04-27
Also published as: CN108377567A

Abstract

The application discloses a method for establishing dual connection to transmit data under a 5G architecture. The method comprises the following steps: the method comprises the steps that a primary cell PCell of UE realizes a mapping function, a convergence protocol PDCP layer, a radio link control RLC layer, a media access control MAC layer and a physical layer, a secondary cell SCell of the UE performs mapping from quality grouped data to a data radio bearer, the convergence protocol PDCP layer, the MAC layer and the physical layer are realized, a core network sends data of the UE to the PCell, the PCell sends the data of the UE to the data radio bearer from the quality grouped data Qos Flow on the mapping layer, then branches are carried out, then all paths of data are sent to the UE through the PCell and the Scell of the UE, and the UE recombines the data on the PDCP layer and then sends the data to an application layer.

Description

Method, device and system for establishing double-connection data transmission under 5G architecture

Technical Field

The invention relates to a wireless communication technology, in particular to a method, a device and a system for establishing double connection for UE under a base station of a 5G system, wherein data is transmitted to the UE through two or more base stations.

Background

5G refers to a fifth generation mobile communication technology. Unlike the previous four generations, 5G is not a single wireless technology, but is a fusion of existing wireless communication technologies. At present, the peak rate of LTE can reach 100Mbps, and the peak rate of 5G can reach 10Gbps, which is 100 times higher than that of 4G. The existing 4G network has limited processing spontaneous capability and cannot support partial services such as high-definition video, high-quality voice, augmented reality, virtual reality and the like. The 5G will introduce more advanced technology, and meet the demand of mobile service traffic increase through higher spectrum efficiency, more spectrum resources and denser cells, etc. together, solve the problems faced by the 4G network, and construct a network society with high transmission rate, high capacity, low delay, high reliability and excellent user experience. As shown in fig. 1, the 5G architecture includes a 5G access network and a 5G core network, and the UE communicates with the data network through the access network and the core network.

In network evolution, the first phase will continue to use the base station of LTE while being able to support 5G terminals and use the features of 5G. Thus, upgrading to LTE base stations to support the 5G feature is attractive and desirable to operators. If the LTE base station is upgraded, the LTE base station can be connected to a 5G core network. The present invention refers to LTE base stations that can connect to a 5G core network as LTE enbs.

Fig. 1 is an architecture diagram of 5G. Node 101 is a 5G core network that contains control plane nodes and user plane nodes, which may be different entities. Between the 5G core network and the 5G base station is an NG interface, which comprises a control plane and a user plane. The control plane is the interface between the core network control node and the base station and the user plane interface is the interface between the core network user node and the base station. The base station connected to the 5G core network may be a 5G base station gNB, or a base station of enhanced LTE, referred to as an LTE eNB. The interface between the gNB and the gNB is an Xn interface, which includes a user plane interface and a control plane interface. The interface between the gbb and the lte base station is also an Xn interface.

The UE can simultaneously transmit and receive data at two base stations, which is called dual-connectivity. Wherein, only one base station is responsible for sending radio resource control RRC information to UE and interacting with a core network control plane entity, the base station is called a main base station MeNB, and the other base station is called an auxiliary base station SeNB. The UE has a cell which is a primary cell Pcell of the UE at a main base station, and sends RRC information to the UE through the primary cell, and other cells are secondary cells Scell. One cell in the Scell of the secondary base station is the secondary base station primary cell pScell (a function of pScell). There is an uplink physical layer control channel on the pScell, and there is no uplink physical layer control channel on other scells. The master base station cell group is the MCG and the secondary base station cell group is the SCG. The dual connectivity can also be extended to multiple connectivity where there is one main base station and multiple secondary base stations. The base stations transmit data to the UE, so that the throughput of the system and the rate of the UE can be improved, and when the quality of a data radio bearer signal of one base station is poor, the data can be transmitted on the data radio bearer with good quality on other base stations.

The configuration of the UE end auxiliary cell group is configured by the auxiliary base station, and the configuration of the auxiliary base station to the UE is sent to the UE by the main base station through the RRC container. The primary base station does not parse the RRC container. Or resolve but not change the configuration inside the RRC container. The bearers established in the SeNB are of two types, one is called split bearer (split bearer) and the other is called SCG bearer. The convergence protocol PDCP protocol stack carried by the split is on the primary base station and the other user plane protocol layers (e.g. radio link control RLC/medium access control MAC/physical layer) are on the secondary base stations. The SCG bearer is that all user plane protocol stacks are on an auxiliary base station, including PDCPRLC/MAC/physical layer, the auxiliary base station receives data from a core network, and the data is processed by a user plane and is sent to the UE through an air interface.

In 5G technology, some technologies different from 4G technology are adopted, for example, in Qos architecture, 5G defines a new mode. When a data connection (PDU Session) is established, the core network sends a default Qos policy or/and an authenticated Qos policy to the RAN and the UE. The data connection is the transmission path between the UE to the core network. Including the transmission path between the core network and the base station and the data radio bearer between the base station and the UE. A PDU Session is a connection between the UE and the packet data network, which is used to transmit data units, typically a PDU Session is established for a service. The data unit types include IP data, ethernet data, and non-IP data. When the PDU Session is established, the core network sends the Qos strategy to the RAN through the NG interface and sends the Qos strategy to the UE through the NAS interface. The Qos policy includes indication information/description information of the Qos Flow, and also includes specific Qos information, and the specific quality (Qos) information includes at least one of the following: data delay target a, data error rate B, priority of data C, guaranteed data rate D, max data rate E, and may also contain other information, such as information of the application layer. The RAN establishes a default DRB according to the requirement of the Qos, and the RAN can establish other DRBs except the default DRB at the same time. In the user plane, the core network forms the data packets into a Qos Flow, adds Qos indication information to a data header of the Qos Flow, and according to the Qos indication information, the RAN can find corresponding specific parameters according to the received Qos policy, and performs corresponding processing with the data of the user plane according to the parameters in the Qos policy, so as to meet the quality requirement. The core network sends the data packet with the Qos indication information to the RAN, and the RAN maps the Qos Flow to resources of the access network and a data radio bearer, for example, the RAN determines that the Qos Flow is mapped to a certain data bearer DRB, or establishes a new data bearer DRB for the Qos Flow. When to establish a new DRB is determined by the RAN, the DRB may be established after receiving signaling of the core network, or after receiving data of the Qos Flow user, the RAN may learn a specific Qos requirement corresponding to the Qos Flow according to Qos indication information included in a packet header of the Qos Flow, the Qos indication information, a default Qos policy and/or a pre-authentication Qos policy stored in the RAN, and transmit the Qos Flow through the DRB if the currently established DRB is suitable for carrying data of the Qos requirement according to the Qos requirement. If not, the RAN may decide to set up a new DRB to carry the Qos Flow.

Under new technology, the previous dual connection establishment procedure has not been applicable. For example, in the LTE system, the core network determines a data bearer corresponding to a certain quality requirement, the core network initiates the data bearer, the bearer of the S1 interface (referred to as E-RAB) and the data radio bearer are in a one-to-one correspondence relationship, the bearer of the S1 interface corresponds to a tunnel on the user plane, and the RAN receives data from the tunnel and directly corresponds to the corresponding data radio bearer. In 5G, the NG interface can already have no concept of E-RAB. The previous methods are not applicable to how the RAN decides on the data radio bearer and how to establish the dual connection to transmit data. The invention researches how to establish dual connectivity for UE under a new technology. Including solving the following problems:

1) how to establish split bearers

2) How to establish SCG bearers

3) How to inform the core network of SCG bearers.

Disclosure of Invention

The invention provides a method for establishing double connection to transmit data under the new 5G technology. The method of the invention can establish connection for the UE on two or more base stations, improve the throughput of the system and improve the reliability and transmission speed of data reception.

In order to achieve the purpose, the following technical scheme is adopted in the application:

a method of establishing dual connectivity for transferring data, comprising:

a base station where a PCell is located sends an auxiliary base station addition request message to a base station where the SCell is located, wherein the message comprises configuration information of Qos Flow to be established, and the configuration information comprises identification of the Qos Flow;

a base station where an SCell is located sends an auxiliary base station addition response message to a base station where a PCell is located, wherein the auxiliary base station addition response message contains configuration information of a configured user plane of the SCell, and the configuration information of the user plane comprises: and the identifier of the Qos Flow and the identifier of the user plane tunnel are contained.

The PCell sends a bearer modification message to the core network, where the bearer modification message includes configuration information of a user plane on the SCell, and the configuration information of the user plane includes: including the identification of Qos Flow, IP address of user plane and tunnel identification.

Preferably, the base station where the primary cell PCell is located sends the secondary base station addition request message to the base station where the secondary cell SCell is located, where the secondary base station addition request message carries: and the tunnel identifier TEID of data forwarding distributed by the base station where the primary cell PCell is located.

Preferably, the base station where the primary cell PCell is located sends the secondary base station addition request message to the base station where the secondary cell SCell is located, where the secondary base station addition request message carries an identifier of the QoS flow for suggesting data forwarding.

Preferably, the base station where the PCell is located receives the secondary base station increase response sent by the base station where the SCell is located, where the secondary base station increase response carries the identifier of the QoS flow needing data forwarding and the indication information needing data forwarding.

Preferably, the tunnel determined by the secondary base station includes a tunnel between the secondary base station and the primary base station and/or a tunnel between the secondary base station and the core network, wherein the tunnel determined by the secondary base station is for one PDU Session.

A method for establishing dual connection for transmitting data comprises,

a base station where a PCell is located sends an auxiliary base station increase request message to a base station where the SCell is located, wherein the auxiliary base station increase message comprises configuration information of a split bearer to be established, and the configuration information comprises identification of a DRB or Xn user plane and specific quality information of a data radio bearer;

a base station where an SCell is located sends an auxiliary base station addition response message to a base station where a PCell is located, wherein the auxiliary base station addition response message contains configuration information of a configured user plane of the SCell, and the configuration information of the user plane comprises: the packet contains an identification of the DRB or Xn user plane, a user plane tunnel identification.

A data transmission system under a 5G network, comprising: at least two base stations, further comprising a user equipment UE, wherein:

the method comprises the steps that a primary cell PCell of UE realizes a mapping function, a convergence protocol PDCP layer, a radio link control RLC layer, a media access control MAC layer and a physical layer, and a secondary cell SCell of the UE carries out mapping from quality grouping data to data radio bearer, realizes the convergence protocol PDCP layer, the MAC layer and the physical layer, wherein

The core network sends the data of the UE to the PCell, the PCell enables the data of the UE to Flow quality grouped data Qos to a data radio bearer on a mapping layer, then branches are carried out, then each path of data is sent to the UE through the PCell and the Scell of the UE, and the UE recombines the data on a PDCP layer and then sends the data to an application layer. Or

And the core network sends the data of the UE to a PCell and an Scell, the PCell and the Scell send the data of the UE to a data radio bearer at a mapping layer, then the data is sent to the UE through the PCell and the Scell of the UE, and the UE recombines the data at an application layer.

A data transmission method under a 5G network comprises the following steps: a base station where a secondary cell (SCell) is located receives a downlink data packet sent by a base station where a primary cell is located, wherein the downlink data packet comprises: information of quality packet data Qos Flow; and the base station where the secondary cell SCell is located sends an uplink data packet to the base station where the primary cell is located, wherein the uplink data packet carries the information of the Qos Flow and the cache information of the Qos Flow.

Preferably, the information of the Qos Flow in the downlink data packet includes: the identification of the Qos Flow is indicated indirectly through the position of the data packet header.

Preferably, the information of the Qos Flow in the uplink data packet includes: the identification of the Qos Flow is indicated indirectly through the position of the data packet header.

Drawings

FIG. 15G is a system architecture diagram;

FIG. 2 is a schematic view of the process of the present invention;

FIG. 3 is a schematic diagram of a first embodiment of the present invention;

FIG. 4 is a schematic diagram of a second embodiment of the present invention;

FIG. 5 is a schematic illustration of a third embodiment of the present invention;

FIG. 6 is a schematic illustration of a fourth embodiment of the present invention;

FIG. 7 is a schematic diagram of a fifth embodiment of the present invention.

Detailed Description

For the purpose of making the objects, technical means and advantages of the present application more apparent, the present application will be described in further detail with reference to the accompanying drawings.

In 5G, downlink, the core network user plane sends data to the base station, in the NG interface, the core network sends data to the base station in the form of Qos Flow, and the base station maps the Qos Flow to a Data Radio Bearer (DRB) and sends the DRB to the UE. And uplink, the UE sends data to the base station, the data is carried on the DRB, and the base station maps the data on the DRB into Qos Flow and sends the Qos Flow to the core network. Therefore, a mapping function module is needed in the base station to map the Qos Flow to the DRB (or vice versa, the DRB is mapped to the Qos Flow). The mapping function referred to below contains both the above-described mappings, and for convenience of description, only the mapping of Qos Flow to DRB is described. Fig. 5 is an example illustrating a transmission path of user plane data. Between the core network and the base station, Qos Flow 1, Qos Flow 2, Qos Flow 3, and Qos Flow 4 are data transmitted to a certain UE, where Qos Flow 1 and Qos Flow 2 belong to the same service data connection (PDU Session). Flow 3 and Qos Flow 4 belong to another traffic data connection. The Qos Flow 1, the Qos Flow 2, and the Qos Flow 3 are sent by the MeNB, and according to the Qos service quality requirement of the Qos Flow, the mapping function on the MeNB maps the Qos Flow with the same quality to one DRB, for example, the base station maps the Qos Flow 1 and the Qos Flow 2 to DRBs 1, and maps the Qos Flow 3 to DRBs 2. If the MeNB decides to set up the split bearer, e.g. DRB2 is set up on the SeNB, after PDCP processing by the MeNB, data is sent to the SeNB over the Xn interface. The SeNB sends data on the DRB2 to the UE through RLC/MAC processing. If the MeNB decides to establish the SCG bearer, for example, Qos Flow 4 is to be sent to the UE through the SCG bearer on the SeNB, the MeNB establishes the SCG bearer through the following embodiments, data is sent to the SeNB by the core network, the mapping function of the SeNB maps the Flow to the DRB, and then the DRB is sent to the UE through the processing of other user planes, for example, PDCP/RLC/MAC.

Fig. 2 is a schematic diagram of the method of the present invention, which describes how a split bearer and an SCG data bearer are established between a main base station and a secondary base station. In the following, the base station and the cell are not distinguished, the primary base station refers to the base station where the primary cell is located, and the secondary base station refers to the base station where the secondary cell is located.

Step 201: the primary base station (the base station where the primary cell PCell of the UE is located) sends a secondary base station addition request to the secondary base station.

The main base station determines to establish dual connectivity, namely to establish an auxiliary base station (a base station where an auxiliary cell (SCell) of the UE is located) according to the measurement report of the UE and the service quality requirement of the DRB, and provides data transmission for the UE through the bearers on the main base station and the auxiliary base station at the same time. Therefore, the data transmission rate can be improved, and the throughput of the system can be improved. When the base station where the PCell is located decides to add one cell as the SCell, the base station where the PCell is located sends an auxiliary base station addition request message to the base station where the SCell is located. The auxiliary base station addition request message comprises capability information of the UE, information of the auxiliary message on the auxiliary base station and an uplink receiving address allocated by the core network, the base station where the PCell is located acquires the uplink receiving address of the data path from the core network, and the base station where the PCell is located sends the uplink receiving address of the data path to the base station where the SCell is located through the auxiliary base station addition request message.

If the main base station determines to establish the split bearer, namely the main base station on the user plane performs mapping from the QoS Flow to the DRB, the mapped data is processed by the PDCP, then the data is shunted, and partial data of the PDCP PDU is sent to the auxiliary base station. The master base station determines to establish the split bearer, the master base station sends a message of the auxiliary base station increase request to the auxiliary base station, the message carries information capable of indicating the DRB on the MeNB, for example, the message carries an identifier of the DRB, and the corresponding user plane can be uniquely determined through the DRB identifier. Or an identity of a user plane is defined, e.g. MeNB assigns a user plane identity indicating splitting of the user plane carried in the Xn interface. The message also carries QoS information corresponding to the DRB. The quality of service (QoS) information comprises at least one of: data delay target A, data error rate B, priority of data C, guaranteed data rate D, and maximum data rate E. After receiving the message, the assisting base station configures a user plane for the split bearer according to the QoS information, configures user plane configuration information of the UE, and the assisting base station further allocates transport layer information of the user plane on the Xn interface, for example. For each split bearer, the assisting base station allocates a Tunnel identifier (Tunnel Endpoint or Tunnel ID). Or the main base station sends a message of the auxiliary base station increase request to the auxiliary base station, where the message carries the information of the PDU Session, such as the identifier of the PDU Session, the information of the QoS Flow, such as the QoS Flow, and the quality requirement information corresponding to the QoS Flow. After receiving the message, the assisting base station configures a user plane for the split bearer according to the QoS information, configures user plane configuration information of the UE, and the assisting base station further allocates transport layer information of the user plane on the Xn interface, for example. For the bearers belonging to the same PDU Session, the assisting base station allocates a Tunnel identifier (Tunnel Endpoint or Tunnel ID).

If the main base station decides to establish the SCG bearer, for the SCG bearer, there are three methods for data processing, one is that the mapping from the Qos Flow to the DRB is completed by the main base station, the processing of other user planes is performed at the auxiliary base station, then at the user plane, the SCG bearer is established between the main base station and the auxiliary base station, the main base station maps the Qos Flow to the DRB through the processing of the mapping function, and then sends the DRB to the auxiliary base station, and the other processing of the user plane is performed at the auxiliary base station, for example, PDCP/RLC/MAC is performed at the auxiliary base station. The assisting base station then transmits the data to the UE over the air interface.

The second method is that the MeNB determines the mapping rules of Qos Flow to DRB, and informs the secondary base station of the mapping rules, for example, which Qos Flow maps to the same DRB. And a mapping function of the auxiliary base station, wherein the Qos Flow is mapped to the data radio bearer according to the mapping principle. In the method, the auxiliary base station adds the request message carrying the Qos Flow identifier, the Qos Flow identifier may be multiple, and the Qos Flow identifiers correspond to the identifiers of the DRBs, so that the auxiliary base station can map the data indicated by the Qos Flow identifier to the same DRB. The message also carries details of Qos corresponding to the DRB. Or carry Qos policies. The method for policy carrying of Qos is specifically described in method three below.

The third method is that for SCG load bearing, the mapping from Qos Flow to DRB is completed by the auxiliary base station, the auxiliary base station obtains a Qos Flow strategy, and can decide how to map Qos Flow and DRB according to the Qos information of Qos Flow and the resource condition of the auxiliary base station, and send the configuration information of DRB to the UE through the main base station. In this way, the message of step 201 needs to contain an identifier of Qos Flow, which indicates which Qos Flow is to be configured as SCG bearer. May contain an identification of one or more Qos flows. The message also contains specific Qos information for Qos Flow on SCG bearer. Or the message contains a Qos strategy of Qos Flow, the strategy is sent to the main base station by the core network, and the main base station forwards the strategy to the auxiliary base station. The primary base station may send all Qos policies to the secondary base station, or send only Qos policies corresponding to Qos Flow connected to the secondary base station. The message also needs to carry an identifier of a PDU Session corresponding to the Qos Flow. In the second and third methods, because the auxiliary base station needs to allocate a tunnel with the core network, for the same PDU Session, only one tunnel is allocated to reduce the number of tunnels, and the data of the whole PDU Session is sent to the base station through the same tunnel. The PDU Session identifier is sent from the primary base station to the secondary base station, so the primary base station needs to know the relationship between the PDU Session and the Qos Flow, i.e., which Qos flows belong to the same PDU Session. The master base station may obtain the identifier of the PDU Session and the identifier of the Qos Flow corresponding to the PDU Session through a signaling sent by the core network, for example, a PDU Session establishment request message. Or the PDU Session information is carried in the Qos Flow identifier, and whether the PDU Session belongs to the same PDU Session can be known through the Qos Flow identifier. For example, the Qos flows belonging to the same PDU Session have the same part identifier. Therefore, the main base station and the auxiliary base station can know whether the main base station and the auxiliary base station belong to the same PDU Session or not through the identification of the Qos Flow. The auxiliary base station knows which Qos flows belong to the same PDU Session through the PDU Session identifier and the Qos Flow identifier, so as to decide whether to allocate a new tunnel or reuse an established tunnel. For example, the secondary base station has not established a tunnel of the user plane for the PDU Session, the secondary base station allocates a new tunnel identifier for downlink reception of the user plane, and sends the tunnel identifier to the core network through the primary base station. If a tunnel of a user plane is established for the PDU Session between the auxiliary base station and the core network, the auxiliary base station sends the tunnel identification to the core network through the main base station. If a tunnel of a user plane can be established for each Qos Flow between the secondary base station and the core network, the secondary base station only needs to know the information of the Qos Flow, and the primary base station does not need to send the identifier of the PDU Session to the secondary base station.

To summarize, the assisting base station addition request message may contain one or more of the following information:

DRB identification (or/and identification of Split bearer Xn user plane)

Identification of √ Qos Flow

V. Qos Flow strategy (or specific requirements of Qos)

Identification of PDU Session

In this embodiment, the DRB in the present invention may also be replaced by another name, such as an Xn bearer or a data bearer, as long as the bearer and the DRB have a corresponding relationship. If replaced by another name, the identity of the DRB is replaced accordingly, for example by the identity of an Xn bearer or a data bearer. The base station uses DRB to identify the radio bearer in the information sent to the UE, and may use other names to identify the bearers on Xn on the Xn interface, but needs to have a correspondence with DRB, from which the base station can learn that the data of these bearers are in one-to-one correspondence. The same values can be used for the corresponding relations.

Step 202: the auxiliary base station transmits an auxiliary base station addition response message to the main base station.

The message carries bearer configuration information for the UE. And the configuration information of the UE configured by the auxiliary base station is carried in the RRC container and is sent to the main base station. The primary base station does not parse the RRC container and forwards the RRC container to the UE. The message carries transport layer information for the user plane allocated to the bearer, e.g. for each split bearer the secondary base station allocates a tunnel identity. For the SCG bearer, the assisting base station assigns a tunnel identifier to each PDU Session, or assigns a tunnel identifier to each Qos Flow, or assigns a tunnel identifier to one DRB.

To summarize, the assisting base station add response message may contain one or more of the following information:

identification of DRB (or of Xn user plane carried by Split)

Identification of √ Qos Flow

Identification of PDU Session

Information of transport layer, e.g. tunnel identification

V-RRC container

Step 203: the master base station sends a bearer modification message to the core network.

The message includes the Qos Flow identifier and the corresponding downlink received transport layer information, such as an IP address and a tunnel identifier, or includes a PDU Session, the Qos Flow identifier, and a downlink received IP address and a tunnel identifier allocated for the PDU Session.

To summarize, the bearer modification message may contain one or more of the following information:

identification of √ Qos Flow

Identification of PDU Session

V. transport layer information, e.g. IP address and tunnel identification

Fig. 3 is a schematic flow chart of establishing a split bearer for a service according to the present invention. The method comprises the following steps:

step 301, a control plane node of a core network receives a PDU session establishment request message. The message may be sent to the control plane by a core network user plane node or by other nodes of the core network.

The PDU session establishment request establishes a data connection from the core network to the UE for a certain service given to the UE. The message contains configuration information for the PDU data. One PDU session may consist of multiple Qos flows. The Qos requirements of each Qos Flow are different, and the message may contain an identification of the Qos Flow and corresponding specific Qos requirements. The message may also contain a default Qos policy, a preconfigured Qos policy. The Qos policy includes indication information/description information of the Qos Flow, and also includes specific Qos information, and the specific quality (Qos) information includes at least one of the following: data delay target a, data error rate B, priority of data C, guaranteed data rate D, max data rate E, and may also contain other information, such as information of the application layer. .

Step 302, the core network sends a message to a base station of the access network.

A control node of a core network sends a PDU Session establishment request message to a base station, wherein the message carries an identifier of the PDU Session, and the identifier uniquely identifies a service of a certain UE. The message also carries transport layer information of the core network user plane, such as an IP address and a tunnel identification, which identifies the upstream receive address of the data path. The message also carries a default Qos policy, and/or a pre-configured Qos policy. The Qos policy includes indication information/description information (ID or descriptor) of the Qos Flow, and also includes specific Qos information, where the specific quality (Qos) information includes at least one of the following: data delay target a, data error rate B, priority of data C, guaranteed data rate D, max data rate E, and may also contain other information, such as information of the application layer. The data of one PDU Session may have a plurality of different Qos flows, each Qos Flow may have its corresponding processing policy, and one PDU Session establishment request message may include a plurality of Qos policies. The message may also carry information that the core network wants to send to the UE, which may be carried over a container of a non-access stratum (NAS container).

The action after the base station receives: and the base station stores the received Qos strategy and processes the user plane data in the future according to the Qos strategy. The base station receives the PDU Session establishment request message, and at least needs to establish a default data radio bearer DRB according to the Qos strategy. The base station may also establish other data bearers simultaneously.

Step 303, the base station sends a message to the UE.

The base station sends an RRC configuration request message to the UE, the message carries a QoS strategy sent to the UE by a core network, the strategy can be transmitted to the UE through a non-access stratum container (NAS container), and the strategy also comprises configuration information of a DRB configured for the UE by the base station.

In step 304, the UE sends a message to the base station.

The UE sends an RRC configuration completion message to the base station. The message carries the confirmation information that the UE successfully configures the DRB.

Step 305, the base station sends a PDU Session establishment success message to the core network.

And after the base station is configured, the base station sends a successful confirmation message to the control node in the core network. The message carries transport layer information allocated by the base station for the user plane, such as an IP address and a tunnel identifier received by downlink data.

Step 306, the core network control node sends a message to the user plane node.

If the control node and the user node of the core network are not located together, the control node sends a message to the user plane node, where the message carries information of the Qos Flow, such as an identifier of a PDU Session, identifier/description information of the Qos Flow, and transport layer information allocated by the base station to the user plane of the PDU Session, such as an IP address and a tunnel identifier for receiving downlink data.

A pdu session may only establish one tunnel between the core network user plane and the base station.

The data of the user plane may start to be transmitted, step 307. For example, in the downlink, the core network forms a Qos Flow from a packet, adds Qos indication information to a header of the Qos Flow, and transmits the packet with the Qos indication information to the RAN. If the data is not guaranteed to be reliably transmitted (non-GBR), the core network does not need to initiate signaling of a control plane, and the processed data is directly sent to a RAN node, namely a base station.

Step 308, the base station receives the data of the user plane, and obtains the Qos information of the data packet according to the header information of the data packet, and the base station needs to have a function of mapping Qos Flow to DRB. The mapping function module maps one or more Qos flows onto a DRB, and the mapping principle mainly refers to the Qos of the Qos Flow. For example, the packet header indicates Qos Flow-1, according to the stored Qos policy, a specific Qos requirement corresponding to Qos Flow-1 can be known, the established default DRB or one of the DRBs can satisfy the Qos requirement, and the base station can decide to send the data packet to the UE through the appropriate DRB. If there are multiple Qos flows, such as Qos Flow-1, Qos Flow-2, and Qos Flow-3, where the Qos Flow-1 and Qos Flow-3 have the same or close Qos requirements, the base station may map the data of Qos Flow-1 and Qos Flow-3 to the same DRB for transmission. The data is processed by the mapping function, processed by layer 2, for example, processed by PDCP/RLC/MAC layers, and sent to the UE over the air interface.

In step 309, the primary base station sends a secondary base station add request to the destination secondary base station.

The main cell of the UE on the base station receives the measurement report of the user, the signal quality of a certain cell on the adjacent base station meets the requirement, the main cell on the main base station determines to establish the auxiliary cell on the auxiliary base station, and the data transmission is shared through double connection. The base station decides to send data to one or several DRBs originally on the MeNB through the secondary base station, i.e. to establish a Split bearer. When the base station where the PCell is located decides to add one cell as the SCell, the base station where the PCell is located sends an auxiliary base station addition request message to the base station where the SCell is located. The auxiliary base station addition request message comprises capability information of the UE, information of the auxiliary message on the auxiliary base station and an uplink receiving address allocated by the core network, the base station where the PCell is located acquires the uplink receiving address of the data path from the core network, and the base station where the PCell is located sends the uplink receiving address of the data path to the base station where the SCell is located through the auxiliary base station addition request message.

The main base station sends a message of the auxiliary base station increase request to the auxiliary base station, the message carries information capable of indicating the DRB on the MeNB, for example, the message carries the identification of the DRB, and the corresponding user plane can be uniquely determined through the DRB identification. Or an identity of a user plane is defined, e.g. MeNB assigns a user plane identity, which is used to identify its corresponding user plane. The message also carries the Qos requirement corresponding to the DRB. After receiving the message, the assisting base station configures a user plane for the split bearer according to the Qos requirement, configures user plane configuration information of the UE, and the assisting base station further allocates transport layer information of the user plane on the Xn interface, for example. For each split bearer, the secondary base station assigns a tunnel identity.

Under another implementation method, the primary base station sends a message of the auxiliary base station increase request to the auxiliary base station, where the message carries information of the PDU Session, such as an identifier of the PDU Session, information of the QoS Flow, such as a QoS Flow identifier list, and quality requirement information corresponding to the QoS Flow. After receiving the message, the assisting base station configures a user plane for the split bearer according to the QoS quality requirement, configures user plane configuration information of the UE, and also allocates transport layer information of the user plane on the Xn interface, for example. And for the load bearing belonging to the same PDU Session, the auxiliary base station distributes a tunnel identifier TEID.

In step 310, the secondary base station sends a secondary base station addition response message to the primary base station.

The auxiliary base station determines the configuration information of the load on the UE according to the Qos of the DRB and the capability of the UE, the target base station contains the configuration information of the auxiliary load or the auxiliary cell on the UE in an RRC container, and the container is forwarded to the UE through the main base station. The UE sets up various layer protocols, such as RLC and MAC layer, at the UE end according to the configuration. The message also carries a DRB identifier or an identifier of an Xn user plane, which corresponds to transport layer information, e.g. a tunnel identifier. If the load bearing belonging to the same PDU Session is carried, the auxiliary base station allocates a tunnel identification TEID, and the message of the auxiliary base station sending the auxiliary base station increasing response message contains the PDU Session identification and the tunnel identification TEID allocated to the PDU. In this case, the flow control of the user plane also needs to be modified. The specific flow control process is described in the embodiment corresponding to fig. 7.

In step 311, the primary base station sends an RRC reconfiguration request to the UE.

The primary base station does not parse the RRC container and forwards the RRC container to the UE. The main base station can add the configuration information of the main base station to the UE and send the configuration information of the auxiliary base station to the UE.

Step 312: the UE sends an RRC reconfiguration complete message to the main base station.

And after the UE configuration is successful, sending a response message to the main base station. The response message includes the response to the configuration information transmitted in step 311, that is, the response to the configuration information of the main base station and the response to the configuration information of the auxiliary base station. If necessary, the UE also needs to perform a random access procedure with the new assisting base station and synchronize with the new assisting base station. After synchronization, the assisting base station may start sending data to the UE.

Step 313: and the main base station sends an RRC reconfiguration completion message to the auxiliary base station.

And the main base station informs the auxiliary base station that the configuration of the UE terminal is successful. Since the UE sends the acknowledgement message to the primary base station, the primary base station needs to forward the acknowledgement message to the secondary base station. If the main base station cannot resolve the response of the UE to the configuration information of the auxiliary base station, the main base station can also forward the response of the UE to the configuration information of the auxiliary base station to the auxiliary base station in the form of an RRC container. For example, the primary base station is an lte base station and the secondary base station is a 5G base station gNB, or the primary base station is a 5G base station and the secondary base station is an lte base station.

Thereafter, data is transmitted from the main base station to the subsidiary base station. The secondary base station also sends information of the flow control to the primary base station.

At this point, the Split bearer establishment procedure is completed.

Fig. 4 is a schematic flow chart of establishing an SCG bearer for a service in the present invention. The method comprises the following steps:

step 401, the control plane node of the core network receives the PDU session establishment request message. The message may be sent to the control plane by a core network user plane node or by other nodes of the core network.

The PDU session establishment request establishes a data connection from the core network to the UE for a certain service given to the UE. The message contains configuration information for the PDU data. One PDU session may consist of multiple Qos flows. The Qos requirements of each Qos Flow are different, and the message may contain an identification of the Qos Flow and corresponding specific Qos requirements. The message may also contain a default Qos policy, a preconfigured Qos policy. The Qos policy includes indication information/description information of the Qos Flow, and also includes specific Qos information, and the specific quality (Qos) information includes at least one of the following: data delay target a, data error rate B, priority of data C, guaranteed data rate D, max data rate E, and may also contain other information, such as information of the application layer.

Step 402, the core network sends a message to a base station of the access network.

In step 403, the base station sends a message to the UE.

In step 404, the UE sends a message to the base station.

Step 405, the base station sends a PDU Session establishment success message to the core network.

In step 406, the core network control node sends a message to the user plane node.

In step 407, data of the user plane may start to be transmitted. For example, in the downlink, the core network forms a Qos Flow from a packet, adds Qos indication information to a header of the Qos Flow, and transmits the packet with the Qos indication information to the RAN. If the data is not guaranteed to be reliably transmitted (non-GBR), the core network does not need to initiate signaling of a control plane, and the processed data is directly sent to a RAN node, namely a base station.

Step 408, the base station receives the data of the user plane, and obtains the Qos information of the data packet according to the header information of the data packet, and the base station needs to have a function of mapping Qos Flow to DRB. The mapping function module maps one or more Qos flows onto a DRB, and the mapping principle mainly refers to the Qos of the Qos Flow. For example, the packet header indicates Qos Flow-1, according to the stored Qos policy, a specific Qos requirement corresponding to Qos Flow-1 can be known, the established default DRB or one of the DRBs can satisfy the Qos requirement, and the base station can decide to send the data packet to the UE through the appropriate DRB. If there are multiple Qos flows, such as Qos Flow-1, Qos Flow-2, and Qos Flow-3, where the Qos Flow-1 and Qos Flow-3 have the same or close Qos requirements, the base station may map the data of Qos Flow-1 and Qos Flow-3 to the same DRB for transmission. The data is processed by the mapping function, processed by layer 2, for example, processed by PDCP/RLC/MAC layers, and sent to the UE over the air interface.

In step 409, the primary base station sends a secondary base station addition request to the secondary base station.

The main cell of the UE on the base station receives the measurement report of the user, the signal quality of a certain cell on the adjacent base station meets the requirement, the main cell on the main base station determines to establish the auxiliary cell on the auxiliary base station, and the data transmission is shared through double connection. The base station decides to transmit data through the auxiliary base station by using one or more Qos flows originally on the MeNB, namely, the SCG bearer is established. The method comprises the steps that a main base station sends an auxiliary base station increase request to an auxiliary base station, the auxiliary base station increase request message comprises capability information of UE (user equipment), information of the auxiliary message on the auxiliary base station and an uplink receiving address distributed by a core network, the base station where the PCell is located obtains the uplink receiving address of a data path from the core network, and the base station where the PCell is located sends the uplink receiving address of the data path to the base station where the SCell is located through the auxiliary base station increase request message.

If the main base station decides to establish the SCG bearer, for the SCG bearer, there are two methods for data processing, one is that the mapping from the Qos Flow to the DRB is completed by the main base station, the processing of other user planes is performed in the auxiliary base station, the main base station maps the Qos Flow to the DRB through the processing of the mapping function, and then sends the DRB to the auxiliary base station, and the other processing of the user plane is performed in the auxiliary base station. The main base station sends a message of the auxiliary base station increase request to the auxiliary base station, the message carries information capable of indicating the DRB on the MeNB, for example, the message carries the identification of the DRB, and the corresponding user plane can be uniquely determined through the DRB identification. Or an identity of a user plane is defined, e.g. MeNB assigns a user plane identity, which is used to identify its corresponding user plane. The message also carries the Qos requirement corresponding to the DRB. After receiving the message, the assisting base station configures a user plane for the SCG bearer according to the Qos requirement, configures user plane configuration information of the UE, and the assisting base station further allocates transport layer information of the user plane on the Xn interface, for example. For each SCG bearer, the assisting base station assigns a tunnel identifier.

The second method is that the MeNB decides the mapping of Qos Flow to DRB, tells the decision to the secondary base station, and the secondary base station maps Qos Flow to DRB according to the configuration of the MeNB. In the method, the auxiliary base station adds the request carrying the Qos Flow identifier, the Qos Flow identifier may be multiple, and the Qos Flow identifier corresponds to the identifier of the DRB, so that the auxiliary base station can map the data indicated by the Qos Flow identifier to the same DRB. The message also carries Qos information corresponding to the DRB. Or a Qos policy carrying Qos Flow. The carrying method is described in detail in method three below.

The third method is that for SCG load bearing, the mapping from Qos Flow to DRB is completed by the auxiliary base station, the auxiliary base station obtains a Qos Flow strategy, and can decide how to map Qos Flow and DRB according to the Qos requirement of Qos Flow and the resource condition of the auxiliary base station, and send the configuration information of DRB to the UE through the main base station. In this method, the message added by the secondary base station in this step includes an identifier of the Qos Flow, which indicates which Qos Flow is to be configured as the SCG bearer. May contain an identification of one or more Qos flows. The message also contains specific Qos requirements for Qos Flow on SCG bearers. Or the message contains a Qos strategy of Qos Flow, the strategy is sent to the main base station by the core network, and the main base station forwards the strategy to the auxiliary base station. The primary base station may send all Qos policies to the secondary base station, or send only Qos policies corresponding to Qos Flow connected to the secondary base station. The message also needs to carry an identifier of a PDU Session corresponding to the Qos Flow. In the second and third methods, because the auxiliary base station needs to allocate a tunnel with the core network, for the same PDU Session, only one tunnel is allocated to reduce the number of tunnels, and the data of the whole PDU Session is sent to the base station through the same tunnel. The PDU Session is sent by the primary base station to the secondary base station, so the primary base station needs to know the relationship between the PDU Session and the Qos Flow, i.e., which Qos flows belong to the same PDU Session. The master base station may obtain the identifier of the PDU Session and the identifier of the Qos Flow corresponding to the PDU Session through a signaling sent by the core network, for example, a PDU Session establishment request message. Or the PDU Session information is carried in the Qos Flow identifier, and whether the PDU Session belongs to the same PDU Session can be known through the Qos Flow identifier. For example, the Qos flows belonging to the same PDU Session have the same part identifier. Therefore, the main base station and the auxiliary base station can know whether the main base station and the auxiliary base station belong to the same PDU Session or not through the identification of the Qos Flow. If a tunnel can be established for each Qos Flow between the secondary base station and the core network, the primary base station does not need to send the identification of the PDU Session to the secondary base station.

For SCG bearers, if the primary base station is handed over to the secondary base station, the primary base station needs to forward the buffered data to the secondary base station. If there are multiple QoS flows on the SCG bearer, the primary base station may decide to switch a certain QoS flow on the secondary base station to the primary base station while the SCG bearer remains on the secondary base station. In the master base station transmitting the supplementary base station addition request message, the master base station assigns an uplink address TEID for data transfer. When a certain QoS flow is switched to the main base station, the auxiliary base station sends the buffered data to the uplink address. According to the quality requirement of QoS flow and the condition of buffering, the main base station can suggest some QoS flow to need data forwarding, so that the auxiliary base station adding request message also carries the identification of QoS flow suggesting data forwarding. Under the second approach above, the proposed identification of data forwarding may be for a DRB.

In step 410, the secondary base station sends a secondary base station addition response message to the primary base station.

The auxiliary base station determines the configuration information of the load on the UE according to the Qos of the DRB and the capability of the UE, the target base station contains the configuration information of the auxiliary load or the auxiliary cell on the UE in an RRC container, and the container is forwarded to the UE through the main base station. The UE sets various layer protocols of the UE end, such as PDCP, RLC and MAC layers according to the configuration. The message also carries a DRB identifier or an identifier of an Xn user plane, which corresponds to transport layer information, e.g., a tunnel identifier. Or the message contains a PDU Session identifier and/or a Qos Flow identifier, and the auxiliary base station allocates a tunnel identifier for each PDU Session or allocates a tunnel identifier for each Qos Flow. If each PDU Session is allocated with a tunnel identifier, the message contains the identifier of the PDU Session. The auxiliary base station refers to the proposal information of the main base station and the configuration information of the auxiliary base station on the radio bearer of the target cell to decide which QoS Flow needs to forward data, and the auxiliary base station sends an auxiliary base station increase response message, wherein the auxiliary base station increase response message also carries the identification of the QoS Flow needing to forward data and the indication information needing to forward. The indication information to be forwarded may include transport layer information, such as an IP address and a tunnel identifier, for the data forwarding by the assisting base station. In addition to data forwarding for one QoS flow, data forwarding for DRB may also be performed, where the message includes an identifier of the DRB and transport layer information for data forwarding by the assisting base station, such as an IP address and a tunnel identifier. In particular, the mechanism of data forwarding may be one of the following ways:

a: and establishing a data forwarding tunnel aiming at the PDU Session between the main base station and the auxiliary base station. The auxiliary base station establishes a tunnel identifier for data forwarding for the PDU Session and sends the tunnel identifier to the main base station. And the data belonging to the same PDU Session is forwarded through the same tunnel. And when the data is forwarded, the data packet header contains the QoS Flow identifier, and the auxiliary base station maps the QoS Flow to the DRB according to the QoS Flow identifier. The data stored by the main base station may be data packets that are not mapped to the DRB, and when the data packet is sent from the core network to the main base station, the header already carries the QoS Flow identifier, and the main base station may directly send the data packets to the auxiliary base station. The main base station also stores the data packet mapped to the DRB, the data packet mapped to the DRB is sent to the PDCP protocol layer, and the PDCP protocol layer needs to know the identification of the QoS Flow corresponding to the PDCP data packet and can obtain the identification through the interactive information between the internal protocol layers. When the master base station forwards the PDCP data packet, the PDCP data packet is sent through a tunnel corresponding to the PDU Session, the tunnel protocol is a GTP-U protocol, the header of the GUP-U contains the identification of QoS Flow, and the QoS Flow corresponding to the forwarded PDCP data packet is indicated.

b: and a data forwarding tunnel aiming at the DRB is established between the main base station and the auxiliary base station. And the auxiliary base station allocates a tunnel identifier for data forwarding to each DRB. Under the second method above, the MeNB decides the mapping of Qos Flow to DRB, and informs the secondary base station of the decision, and the secondary base station maps Qos Flow to DRB according to the configuration of the MeNB. The auxiliary base station establishes a tunnel identifier for data forwarding for the DRB and sends the tunnel identifier to the main base station. And the data belonging to the same DRB is forwarded through the same tunnel. The forwarding method is similar to the current data forwarding method of double-join. The data stored in the main base station may be a data packet that is not mapped to the DRB, and when the data packet is sent from the core network to the main base station, the header already carries the QoS Flow identifier, and for data forwarding, the main base station needs to map the data to the DRB, and then forward the data to the auxiliary base station through a tunnel corresponding to the DRB. And the auxiliary base station receives the forwarded data and sends a data packet to the UE on the corresponding DRB.

a: the method a and the method b are combined, and two data forwarding tunnels are established between the main base station and the auxiliary base station, wherein one tunnel is for PDU Session and the other tunnel is for DRB. The assisting base station adds the response message sent by the assisting base station may include the PDU Session identifier and its corresponding tunnel information, such as the IP address and the tunnel identifier, or include the DRB identifier and its corresponding tunnel information, such as the IP address and the tunnel identifier. The data stored in the primary base station may be a data packet that is not mapped to the DRB, and when the data packet is sent from the core network to the primary base station, and the header already carries the identifier of the QoS Flow, the primary base station sends the data packet through a tunnel for the PDU Session. And the auxiliary base station receives the forwarded data, maps the data packet to the DRB, and transmits the data packet to the UE on the DRB. The main base station also stores the data packet mapped to the DRB, the data packet mapped to the DRB is sent to the PDCP protocol layer, and the data packet stored in the PDCP protocol layer is sent through a tunnel aiming at the DRB. And the auxiliary base station receives the forwarded data and sends a data packet to the UE on the corresponding DRB.

It should be noted that, although the data forwarding method is described in the embodiment of SCG bearer establishment, the method of the present invention is also applicable to other bearer manners. Only the bearer type needs to be changed to the corresponding bearer type.

In step 411, the primary base station sends an RRC reconfiguration request to the UE.

Step 412: the UE sends an RRC reconfiguration complete message to the main base station.

And after the UE configuration is successful, sending a response message to the main base station. The response message includes the response to the configuration information transmitted in step 411, that is, the response to the configuration information of the main base station and the response to the configuration information of the auxiliary base station. If necessary, the UE also needs to perform a random access procedure with the new assisting base station and synchronize with the new assisting base station. After synchronization, the assisting base station may start sending data to the UE.

Step 413: and the main base station sends an RRC reconfiguration completion message to the auxiliary base station.

Step 414: the main base station sends a bearing modification request message to the core network control node.

Step 415: the core network control node sends a bearing modification request message to the core network user node and informs the new downlink received transmission layer information.

Step 416: the core network user node sends a bearer modification response message to the core network control node confirming receipt of the message of step 415.

Step 417: the core network control node sends a bearer modification response message to the base station acknowledging receipt 415 of the message of step.

Step 418: if data forwarding exists, the main base station initiates the step of data forwarding and sends the serial number state information to the auxiliary base station. The assisting base station sets the sequence number of the user data with reference to the information.

So far, the SCG bearer establishment procedure is completed.

Fig. 6 is an apparatus diagram of a base station. In the base station, a mapping function module is added, and the module maps the Qos Flow to the DRB or maps the DRB to the Qos Flow.

Fig. 7 shows a data format transmitted between a main base station and a secondary base station, and for a split bearer, the main base station divides data and transmits the data to a UE through the main base station and the secondary base station. In order for the primary base station to perform reasonable data division, the secondary base station needs to transmit information for rate control, and the primary base station determines how to divide data by referring to the information. The first table is the format of the data sent by the primary base station to the secondary base station. The format type indication, the QoS Flow identification and the sequence number of the Xn interface are contained. The format type indicates the type of user data format, for example, "0" represents the data format transmitted by the primary base station to the secondary base station. The sequence number of the Xn interface is the sequence number allocated by the main base station for the data packet on the Xn interface of a certain QoS flow, and the sequence number is increased by 1 every time one data packet is sent.

The first table is the format of the data sent by the primary base station to the secondary base station. The data caching information of the first QoS Flow, the next QoS Flow and the data caching information of the second QoS Flow are contained in the format type indication, and the data caching information of the nth QoS Flow is up to the next QoS Flow. When the split bearer is established, the main base station tells the auxiliary base station which QoS flows are established to the auxiliary base station through a QoS Flow identification list contained in the auxiliary base station establishment request message. The second format includes the buffering information corresponding to these QoS flows. The order coincides with the order of the QoS Flow identification list. If some QoS flows established on the auxiliary base station are established or deleted by the main base station, the position of the corresponding QoS Flow in the table is adjusted correspondingly. For example, if the QoS Flow of the first position is deleted from the assisting base station, the second QoS Flow in the original table moves upward to become the QoS Flow of the first position.

The third table is the data format sent by the secondary base station to the primary base station, and contains format type indication, QoS Flow identification, data cache information, and Xn data loss information. The data buffering information is the expected buffering size information of the auxiliary base station for the QoS flow, and the main base station can adjust the proportion of data division according to the information. The Xn data loss information indicates which data is lost during Xn transmission, and the assisting base station can know which data is lost during Xn transmission according to the sequence number of the Xn interface in the first table.

And the fourth table is a data format sent by the auxiliary base station to the main base station, and comprises a format type indication, data caching information of the first QoS Flow, and next data caching information of the second QoS Flow till the nth QoS Flow. When the split bearer is established, the main base station tells the auxiliary base station which QoS flows are established to the auxiliary base station through a QoS Flow identification list contained in the auxiliary base station establishment request message. The fourth format includes the buffering information corresponding to these QoS flows. The order coincides with the order of the QoS Flow identification list. The data buffering information is the expected buffering size information of the auxiliary base station for the QoS flow, and the main base station can adjust the proportion of data division according to the information. The Xn data loss information indicates which data is lost during Xn transmission, and the assisting base station can know which data is lost during Xn transmission according to the sequence number of the Xn interface in the first table. If some QoS flows established on the auxiliary base station are established or deleted by the main base station, the position of the corresponding QoS Flow in the table is adjusted correspondingly. For example, if the QoS Flow of the first position is deleted from the assisting base station, the second QoS Flow in the original table moves upward to become the QoS Flow of the first position.

The above description is only for the purpose of illustrating the preferred embodiments of the present invention and is not to be construed as limiting the invention, and any modifications, equivalents, improvements and the like made within the spirit and principle of the present invention should be included in the scope of the present invention.

Claims

1. A method performed by a master base station in a wireless communication system, the method comprising:

transmitting a secondary base station addition request message to a secondary base station, the secondary base station addition request message including a quality of service (QoS) flow identifier and a Protocol Data Unit (PDU) session identifier associated with the QoS flow identifier;

receiving a secondary base station addition response message from a secondary base station, the secondary base station addition response message including a Data Radio Bearer (DRB) identifier, the QoS flow identifier associated with the DRB identifier, the PDU session identifier associated with the QoS flow identifier, and tunnel information associated with data reception; and

transmitting a modification request message to a core network entity, the modification request message including the QoS flow identifier, the PDU session identifier associated with the QoS flow identifier, and the tunnel information associated with data reception.

2. The method of claim 1, wherein the first and second light sources are selected from the group consisting of,

wherein the tunnel information comprises an Internet protocol, IP, address and a tunnel endpoint identifier, TEID, associated with the PDU session identifier.

3. The method of claim 1, wherein the first and second light sources are selected from the group consisting of,

wherein the supplementary base station addition request message further includes information on data forwarding between the main base station and the supplementary base station, an

Wherein the information on data forwarding includes information on a suggestion for data forwarding and a QoS flow identifier associated with the data forwarding.

4. The method of claim 3, wherein the first and second light sources are selected from the group consisting of,

wherein the assisting base station adding response message further includes the QoS flow identifier determined for data forwarding to the assisting base station, the DRB identifier associated with the data forwarding, and the tunnel information associated with the data forwarding.

5. The method of claim 1, wherein the first and second light sources are selected from the group consisting of,

wherein the supplementary base station addition request message further includes information associated with mapping of QoS flows to DRBs for the primary base station, an

Wherein the information associated with the mapping of QoS flows to DRBs comprises a DRB identifier associated with the mapping of QoS flows to DRBs and a QoS flow identifier associated with the mapping of QoS flows to DRBs.

6. The method of claim 5, further comprising:

if the secondary base station allows mapping of the QoS flow configured by the primary base station to the DRB,

a data forwarding tunnel is established for each DRB associated with a DRB identifier associated with a mapping of QoS flows to DRBs.

7. The method of claim 5, further comprising:

a data forwarding tunnel for each PDU session is established.

8. The method of claim 1, wherein the first and second light sources are selected from the group consisting of,

wherein the assisting base station addition request message further includes a QoS parameter associated with the QoS flow identifier.

9. A method performed by a assisting base station in a wireless communication system, the method comprising:

receiving a secondary base station addition request message from a master base station, the secondary base station addition request message including a quality of service (QoS) flow identifier and a Protocol Data Unit (PDU) session identifier associated with the QoS flow identifier;

transmitting a secondary base station addition response message to a master base station, the secondary base station addition response message including a Data Radio Bearer (DRB) identifier, the QoS flow identifier associated with the DRB identifier, the PDU session identifier associated with the QoS flow identifier, and tunnel information associated with data reception.

10. The method of claim 9, wherein the first and second light sources are selected from the group consisting of,

11. The method of claim 9, wherein the first and second light sources are selected from the group consisting of,

12. The method of claim 11, wherein the first and second light sources are selected from the group consisting of,

13. The method of claim 9, wherein the first and second light sources are selected from the group consisting of,

14. The method of claim 13, further comprising:

establishing a data forwarding tunnel for each DRB associated with a DRB identifier associated with a mapping of QoS flows to DRBs.

15. The method of claim 13, further comprising:

a data forwarding tunnel is established for each PDU session.

16. The method of claim 9, wherein the first and second light sources are selected from the group consisting of,

17. A master base station in a wireless communication system, the master base station comprising:

a transceiver; and

at least one processor configured to:

transmitting, via the transceiver, a secondary base station addition request message to a secondary base station, the secondary base station addition request message including a quality of service (QoS) flow identifier and a Protocol Data Unit (PDU) session identifier associated with the QoS flow identifier,

receiving, via the transceiver, a secondary base station addition response message from a secondary base station, the secondary base station addition response message including a Data Radio Bearer (DRB) identifier, the QoS flow identifier associated with the DRB identifier, the PDU session identifier associated with the QoS flow identifier, and tunnel information associated with data reception, and

transmitting, via the transceiver, a modification request message to a core network entity, the modification request message including the QoS flow identifier, the PDU session identifier associated with the QoS flow identifier, and the tunnel information associated with data reception.

18. The master base station of claim 17,

19. The master base station of claim 17,

20. The master base station of claim 19,

21. The master base station of claim 17,

22. The master base station of claim 21,

23. The master base station of claim 21,

a data forwarding tunnel for each PDU session is established.

24. The master base station of claim 17,

25. A secondary base station in a wireless communication system, the secondary base station comprising:

a transceiver; and

at least one processor configured to:

receiving, via the transceiver, a secondary base station addition request message from a master base station, the secondary base station addition request message including a quality of service (QoS) flow identifier and a Protocol Data Unit (PDU) session identifier associated with the QoS flow identifier;

transmitting, via the transceiver, a secondary base station addition response message to a master base station, the secondary base station addition response message including a Data Radio Bearer (DRB) identifier, the QoS flow identifier associated with the DRB identifier, the PDU session identifier associated with the QoS flow identifier, and tunnel information associated with data reception.

26. The assisting base station of claim 25,

27. The assisting base station of claim 25,

28. The assisting base station of claim 27,

29. The assisting base station of claim 25,

30. The assisting base station of claim 29, wherein said at least one processor is further configured to:

31. The assisting base station of claim 29, wherein said at least one processor is further configured to:

a data forwarding tunnel is established for each PDU session.

32. The assisting base station of claim 25,