Patent Description:
The Internet of Everything (IoE), which is a combination of the loT technology and the Big Data processing technology through connection with a cloud server, has emerged. As technology elements, such as "sensing technology""communication and network infrastructure‴‴‴′ have been demanded for loT implementation, a sensor network, a Machine-to-Machine (M2M) communication, Machine Type Communication (MTC), and so forth have been recently researched. Such an loT environment may provide intelligent Internet technology services that create a new value to human life by collecting and analyzing data generated among connected things.

Application of a cloud Radio Access Network (RAN) as the above-described Big Data processing technology may also be considered to be as an example of convergence between the <NUM> technology and the loT technology.

<NUM> refers to the fifth generation of mobile communication technology. Unlike the previous four generations, <NUM> is not a single wireless technology, but a convergence of existing wireless communication technologies. At present, the peak rate of LTE may reach <NUM> Mbps, and the peak rate of <NUM> will reach <NUM> Gbps, which is <NUM> times higher than that of <NUM>. The existing <NUM> network has limited processing ability and cannot support some services, for example, high-definition video, high fidelity voice, augmented reality, virtual reality and the like. <NUM> will introduce more advanced technologies to meet the growth of mobile service traffic through higher spectrum efficiency, more spectrum resources and more dense cells, to solve the problems faced by the <NUM> network, and to build a network with high-speed transmission rate, high capacity, low latency, high reliability, and excellent user experience. As shown in <FIG>, <NUM> architecture includes a <NUM> access network and a <NUM> core network, and a UE communicates with a data network through the access network and the core network.

In network evolution, the first phase will continue to use LTE base station eNB, while being able to support <NUM> terminals and use <NUM> features. Therefore, some base stations gNBs with <NUM> access technologies will be deployed, and the gNBs may serve as secondary base stations, and provide data transmission to the UE together with the LTE base stations. The <NUM> base station has no signaling connection with the core network control node MME, but only has user plane connection with the core network gateway SGW. The LTE base station and the LTE core network may be reused in this architecture, which is attractive to operators and expected for operators. Specifically, the LTE base station configures the <NUM> base station, and uses the dual connectivity technology defined in the LTE system to transmit data to the UE. The LTE base station serves as a master base station and the <NUM> base station serves as a secondary base station. The second phase allows the eNB to connect with the <NUM> core network, and the eNB and gNB connected to the <NUM> core network are both next-generation access network nodes, i.e., NG RAN nodes. A Xn interface is established between the NG RAN nodes to establish a dual connectivity between the NG RAN nodes, which may improve data throughput.

The type of dual connectivity may have multiple bearer types, and as shown in <FIG>, bearers of transmitted data may be divided, according to the locations of the upper layer protocol (the upper layer protocol includes SDAP and/or PDCP protocol) and the lower layer protocol (the lower layer protocol includes RLC, MAC, and physical layer), into the following types:.

In <NUM> technology, some technologies different from <NUM> technology are adopted, for example, in the QoS architecture, <NUM> defines a new mode. When establishing the data connection (PDU Session), the core network sends the default QoS policy or/and the authenticated QoS policy to the RAN and the UE. The data connection is the transmission path between the UE and the core network. The transmission path between the core network and the base station, and the radio bearer between the base station and the UE are included. The PDU Session is the connection between the UE and the packet data network, and this connection is used to transmit data units, in which, generally, one PDU Session is established for one service. Data unit types include IP data, Ethernet data, and non-IP data. When establishing the PDU session, the core network sends the QoS policy to the RAN through the NG interface, and sends the QoS policy to the UE through the NAS interface. The QoS policy includes the indication/description information of the QoS Flow, and also includes specific QoS information, for example data delay target, data error rate, data priority, guaranteed data rate, maximum data rate, etc., and may also include other information, for example, information of the application layer. The RAN establishes a default data radio bearer DRB according to the requirement of the QoS, and in addition to the default DRB, the RAN may establish other DRBs at the same time. In the user plane, the core network combines the data packets into the QoS Flow, and adds the QoS indication information to the data header of the QoS Flow. According to the QoS indication information, the RAN may find the corresponding specific parameters according to the received QoS policy, and, according to the parameters in the QoS policy, the user plane data is used for performing corresponding processes to meet quality requirements. The core network sends the data packet with the QoS indication information to the RAN, and the RAN maps the QoS Flow into the resource and the radio bearer of the access network, for example, the RAN determines that the QoS Flow is mapped to a data bearer DRB, or establishes a new data bearer DRB for the QoS Flow. When to establish a new DRB, it is determined by the RAN, and may be established after receiving the signaling of the core network, or after receiving the data of the QoS Flow user, according to the QoS indication information included in the header of the QoS Flow, which the RAN may know the specific QoS requirement corresponding to the QoS Flow through the QoS indication information in combine with the default QoS policy saved by the RAN and/or the pre-authentication QoS policy, if the current established DRB is suitable for carrying the data required by the QoS according to the QoS requirement, then the QoS Flow is transmitted via this DRB. If not, the RAN may determine to establish a new DRB and use the new DRB to carry the QoS Flow. <NPL>, discloses an operation for data offloading in a handover. <NPL>, discloses that an MN offloads data to an SN in a DC situation. <NPL>, discloses as shown below that an MN allocates a DRB ID with regard to an SN or provides a DRB ID based on a request from the SN.

In dual connectivity, both the master base station and the secondary base station are RAN nodes, and the QoS Flow may be offloaded by the master base station to the secondary base station in a dual connectivity manner, or vice versa. Both the master base station and the secondary base station may determine the mapping of QoS Flow to the data radio bearer, so the three following problems are required to be solved:.

in order to solve the above problems, the current dual connectivity process is required to be modified accordingly.

The present application proposes a method for establishing dual connectivity to ensure data continuity when the master base station and the secondary base station determine that the mapping of QoS Flow to DRB is different.

In order to make the objects, technical solutions and advantages of the present application clearer, the present application will be further described in detail below with reference to the accompanying drawings. It should be noted that the present disclosure is illustrated but not limited by the following description. In the following description, numerous specific details are set forth, in order to provide a thorough understanding of the present disclosure. However, it will be apparent to those skilled in the art that the present disclosure may be practiced without these specific details. In other instances, well-known circuits, materials, or methods are not described in detail in order to avoid obscuring the present disclosure.

References throughout this description to "one embodiment", "an embodiment", "one example" or "an example" means that a particular feature, structure, or characteristic described in connection with the embodiment or example is included in at least one embodiment of the present disclosure. Thus, the phrase "in one embodiment", "in an embodiment", "in one example" or "in an example" throughout the description does not necessarily refer to the same embodiment or example. In addition, specific features, structures, or characteristics may be combined in one or more embodiments or examples in any suitable combination and/or subcombination. In addition, it will be understood by these skilled in the art that the drawings provided herein are for the purpose of illustration and that the drawings are not necessarily to scale. The term "and/or" as used herein includes any and all combinations of one or more of the items listed.

When establishing dual connectivity, if a master base station notifies a secondary base station that an upper protocol (the upper layer protocol including the SDAP and/or the PDCP protocol) is required to be established on the secondary base station, in one case, the master base station informs the secondary base station a list of all QoS Flows and the DRB identifiers corresponding to the upper layer protocol, and if the secondary base station does not change the mapping of QoS Flow to DRB, it needs to establish a data forwarding tunnel to forward the data saved/cached on the master base station to the secondary base station through the data forwarding tunnel. The data cached on the master base station may be divided into two types, of which one is the data that has been mapped to the DRB, and the other is the data that has not been mapped to the DRB. The cached data has not been successfully sent to the UE, and in order to ensure data continuity, the data should be forwarded from the master base station to the secondary base station and sent by the secondary base station to the UE. The secondary base station may establish two tunnels, of which one is a tunnel established for the DRB to forward the data having been mapped to the DRB, and the other is a tunnel established for PDU Session to forward the data that is not mapped to the DRB. The secondary base station first transmits the forwarded data to the UE, and then transmits the data received from a core network. If the data cached on the master base station is not forwarded to the secondary base station, the data is interrupted. In the other case, the master base station determines to offload partial QoS Flows mapped to a certain DRB to the secondary base station, and the master base station notifies the secondary base station of a list of the partial QoS Flows and the identifiers of the DRB, which the secondary base station cannot correctly distinguish the two cases. If the two cases cannot be distinguished, the secondary base station cannot correctly configure the latter case, for example, for the latter case, the secondary base station needs to allocate a new DRB identifier and only establish a tunnel for the PDU Session. In order to ensure continuity of the data or continuity of services, reduce data loss, and ensure that the secondary base station may correctly configure the UE, the method of the present application is required. In addition, both the master base station and the secondary base station may allocate the data radio bearer identifier for the data radio bearer, wherefore, the method of the present application is required to ensure that the identifier of the data radio bearer allocated by the secondary base station does not conflict with the identifier of the data radio bearer allocated by the master base station. When a problem occurs in some resources on the secondary base station, the normal service cannot be provided, and then the secondary base station is required to release the corresponding resources or the entire data radio bearers, and the master base station is notified which part of the resource has a problem. By adopting the methods of the present application, the master base station may determine new configuration according to the details of the secondary base station resources.

Embodiments of the present application will be described in detail in the following description, examples of which are shown in the accompanying drawings, in which the same or similar elements and elements having same or similar functions are denoted by like reference numerals throughout the description. The embodiments described herein with reference to the accompanying drawings are explanatory and illustrative, which are used to generally understand the present disclosure. The embodiments shall not be construed to limit the present disclosure.

<FIG> illustrates the first method of the present application, wherein the first node may be an eNB connected to the LTE core network, an eNB connected to the <NUM> core network, a gNB, or a node supporting non-3GPP access technologies, and the second node may be an eNB connected to the LTE core network, an eNB connected to the <NUM> core network, a gNB, or a node supporting non-3GPP access technologies. The first node is a master base station in dual connectivity or multiple connectivity, and the second node is a secondary base station in dual connectivity or multiple connectivity.

Step <NUM>: notifying, by the first node, the second node of the information related to the mapping of the QoS Flow to the data radio bearer. The information related to the mapping of the QoS Flow to the data radio bearer indicates one or more of the following information:.

For example, the indication information may be indicated by a displayed information element, for example, the indication information is set to one of the following:.

Alternatively, the indication information may be obtained by using a list of the QoS Flows to be offloaded and mapping information of the QoS Flows to the DRBs included in the message sent by the first node to the second node. The mapping information of the QoS Flows to the DRBs includes the identifiers of the DRBs established on the first node and the list of all QoS Flows borne on the DRB. If the list of the QoS Flows to be offloaded is consistent with a list of all QoS Flows borne on one DRB, then it represents the DRB offloading, and if the list of the QoS Flows to be offloaded includes less QoS Flow identifiers than these included in a list of all QoS Flows on the DRB, then it means the QoS Flow offloading. After the second node receiving the indication information, the actions of the second node are as described above.

Alternatively, the indication information may be obtained by whether the mapping information of the QoS Flows to the DRBs is included in the message sent by the first node to the second node. The mapping information of the QoS Flows to the DRBs includes the identifiers of the DRBs established on the first node and the list of all QoS Flows borne on the DRB. If the mapping information is included in the message, it represents the DRB offloading, and if the mapping information is not included, it represents the QoS Flow offloading. After the second node receiving the indication information, the actions of the second node are as described above.

Alternatively, the indication information may be obtained by whether the message sent by the first node to the second node includes the list of the mapped QoS Flows. The mapping information of the QoS Flow to the DRB includes the identifiers of the DRBs established on the first node and the list of all QoS Flows borne on the DRB, and the list of the QoS Flows borne on the DRB is the list of the mapped QoS Flows. If the message includes the DRB identifiers and the list of the mapped QoS Flows, it represents the DRB offloading, and if only the DRB identifiers are included and the list of the mapped QoS Flows is not included, it represents the QoS Flow offloading. After the second node receiving the indication information, the actions of the second node are as described above.

The first node determines to establish a dual connectivity on the second node, and the first node notifies the second node of the required resources of the dual connectivity, for example, where the upper layer resources (the resources including SDAP and PDCP) are established, and/or the lower layer resources (for example, the resources of the SCG, or the resources of the MCG) are established. The first node also notifies the second node of the above-mentioned offloaded QoS Flow identifier, the identifier of the DRB, and the indication information. In addition, an implicit notification manner may also be used, for example, by indicating whether the DRB identifier is included or not. That is, if the QoS Flows established on the DRBs are all offloaded to the second node, the identifiers of the DRBs are included, and if only partial QoS Flows on the DRBs are established on the second node, the identifiers of the DRBs are not required.

Step <NUM>: receiving, by the second node, the indication information, to find out, according to the indication information, whether the first node offloads all QoS Flows mapped to the DRB to the second node, or whether the data is impossible to be lost, or whether to establish a data forwarding tunnel for DRB, which the second node takes different behaviors. Then the second node sends a response message to the first node, and the message carries information for establishing a data forwarding tunnel.

Behavior I: if QoS Flows on the DRB are all offloaded to the second node, or the data is impossible to be lost, or a data forwarding tunnel for the DRB needs to be established, the second node obtains the mapping of the QoS Flow to the DRB determined by the first node, and the second node may determine whether to adopt the same mapping. If the same mapping is adopted, the second node uses the mapping relationship of the QoS Flow to the DRB determined by the first node, and uses the identifier of the DRB allocated by the first node, which the second node allocates a data forwarding tunnel address to the DRB to forward the PDCP packet that has been mapped to the DRB on the first node but has not been successfully sent to the UE. Optionally, the second node may also establish a data forwarding tunnel for the PDU session to forward the data packet received on the first node that have not yet been mapped to the DRB. If the second node determines to adopt new mapping, the second node only allocates a data forwarding address for the PDU session.

Behavior II: if QoS Flows on the DRB are all offloaded to the second node, or the data is impossible to be lost, or a data forwarding tunnel for the DRB needs to be established, that is, only the data forwarding tunnel of the PDU session needs to be established, the second node does not need to refer to the mapping of the QoS Flow to the DRB determined by the master base station, and the second base station determines the mapping of the QoS Flow to the DRB, and establishes a data forwarding tunnel for the PDU session to forward the data pocket received on the first node that has not yet mapped to the DRB. The second node needs to allocate a DRB identifier for the new DRB, and for how to allocate, it may be referred to the second method of the present application.

The first node receives the response message, and sends the cached data to the tunnel according to the information of the data forwarding tunnel carried in the response message.

<FIG> illustrates the second method of the present application.

Step <NUM>: notifying, by the first node, the first related information of the DRB identifier to the second node. Wherein, the first node may be an eNB connected to the LTE core network, an eNB connected to the <NUM> core network, a gNB, or a node supporting non-3GPP access technologies, and the second node may be an eNB connected to the LTE core network, an eNB connected to the <NUM> core network, a gNB, or a node supporting non-3GPP access technologies. The first node is a master base station or a secondary base station in dual connectivity or multiple connectivity, and the second node is a secondary base station or a master base station in dual connectivity or multiple connectivity. The first related information of the DRB identifier may be one or more of the following information:.

Step <NUM>: notifying, by the second node, the first node of the second related information identified by the second node.

The second node determines the mapping relationship of the QoS Flow to the DRB, as well as the identifier of the DRB, and the second node sends a message to the first node, to notify the identifier of the DRB determined by the second node, which may also carry the resource of the upper layer protocol or the lower layer protocol corresponding to the data radio bearer determined by the second node. The second related information of the DRB identifier may be one or more of the following information:.

<FIG> illustrates the first embodiment of the present application, which shows a process of establishing a secondary base station or a process of modifying a secondary base station.

The master base station determines to establish dual connectivity or multiple connectivity on the secondary base station, and the master station notifies the secondary base station of the list of the QoS Flows to be offloaded to the secondary base station, and notifies whether to establish the upper layer protocol resource and the lower layer protocol resource on the secondary base station. If the upper layer resource is established on the secondary base station, the master base station may notify the master base station and the secondary base station to determine the mapping of the QoS Flow to the DRB, and in the case that the mapping determined by the secondary base station is consistent with that by the master base station, the secondary base station uses the downlink receiving tunnel on the Xn interface corresponding to the old DRB adopted by the master base station, and sends the offloaded data to the tunnel to be sent to the UE by the master base station. In the case that the mapping determined by the secondary base station is different from that by the master base station, the secondary base station notifies the master base station of the new DRB identifier.

Step <NUM>: sending, by the master base station, a secondary base station establishment request message or a secondary base station modification request message to the secondary base station.

The master base station/secondary base station may be an LTE base station or a <NUM> base station gNB. It is assumed that both the master base station and the secondary base station are connected to the <NUM> core network. Both the LTE base station and the <NUM> base station belong to the devices of <NUM> access network.

The master base station determines to establish certain QoS Flows on the secondary base station. These QoS Flows may have been previously mapped to one data radio bearer on the master base station, or be a new QoS Flow configured by the core network without corresponding data radio bearers that have been established. In order to reduce the data interruption time and support the continuity of the data, the master base station may request the secondary base station to establish the secondary bearer in two manners, of which, one is an explicit manner, and the other is an implicit manner. Below are details: in the explicit manner, the secondary base station establishment request message or the secondary base station modification request message carries one or more of the following information:.

Alternatively, the indication information may be obtained by using a list of the QoS Flows to be offloaded/established to the secondary base station and mapping information of the QoS Flows to the DRBs included in the message sent by the master base station to the secondary base station. The mapping information of the QoS Flows to the DRBs includes the identifiers of the DRBs established on the master base station and the list of all QoS Flows borne on the DRB. If the list of the QoS Flows to be offloaded is consistent with a list of all QoS Flow carried on one DRB, then it represents the DRB offloading, and if the QoS Flow list to be offloaded includes less QoS Flow identifiers than these in a list of all QoS Flows on the DRB, then it means the QoS Flow offloading. After the secondary base station receiving the indication information, the actions of the secondary base station are as described above.

Alternatively, the indication information may be obtained by whether the mapping information of the QoS Flows to the DRBs is included in the message sent by the master base station to the secondary base station. The mapping information of the QoS Flows to the DRBs includes the identifiers of the DRBs established on the master base station and the list of all QoS Flows borne on the DRB, in which it represents the DRB offloading if the message includes the mapping information, and is represents the QoS Flow offloading if the mapping information is not included. After the secondary base station receiving the indication information, the actions of the secondary base station are as described above.

Alternatively, the indication information may be obtained by whether the message sent by the master base station to the secondary base station includes the list of the mapped QoS Flows. The mapping information of the QoS Flows to the DRBs includes the identifiers of the DRBs established on the master base station and the list of all the QoS Flows borne on the DRB, and the list of the QoS Flows borne on the DRB is the list of the mapped QoS Flows. If the message includes the DRB identifiers and the list of the mapped QoS Flows, it represents the DRB offloading, and if only the DRB identifiers are included and the list of the mapped QoS Flows is not included, it represents the QoS Flow offloading. After the secondary base station receiving the indication information, the actions of the secondary base station are as described above.

In the second implicit manner, the secondary base station establishment request message or the secondary base station modification request message carries one or more of the following information:.

Step <NUM>: sending, by secondary base station, the secondary base station establishment response message or the secondary base station modification response message to the master base station.

The secondary base station establishment response message or a secondary base station modification response message includes one or more of the following information:.

Step <NUM>: sending, by the master base station, an RRC configuration request message to the UE.

The master base station does not resolve the RRC container sent by the secondary base station, and forwards the RRC container to the UE. The master base station may add its own configuration information to the UE and send it to the UE together with the configuration information of the secondary base station.

Step <NUM>: sending, by the UE, an RRC configuration complete message to the master base station.

After successfully configuring the UE, the response message is sent to the master base station. The response message may include a response to the configuration information of the master base station, as well as a response to the configuration information of the secondary base station. If necessary, the UE also needs to perform a random access procedure with the new secondary base station and synchronize with the new secondary base station. After synchronizing, the secondary base station may begin to transmit data to the UE.

Step <NUM>: sending, by the master base station, a secondary base station reconfiguration complete message to the secondary base station.

The master base station notifies the secondary base station of the information that the configuration of the UE is successful. Since the UE sends an acknowledgment message to the master base station, the master base station needs to forward the acknowledgment message to the secondary base station. If the master base station cannot resolve the response of the UE to the configuration information of the secondary base station, the master base station may forward the response of the UE to the configuration information of the secondary base station to the secondary base station in the form of the RRC container.

Step <NUM>: sending, by the master base station, a PDU Session modification indication core network.

If the secondary base station establishes a new connection with the core network, the master base station needs to send a new downlink data receiving address to the core network. The message carries the PDU Session identifier and the corresponding downlink data receiving address.

The description of this embodiment ends here. It should be noted that this embodiment omits some known information and steps.

<FIG> illustrates the second embodiment of the present application, which shows a modification process initiated by the secondary base station. When the state of the resource on the secondary base station changes, the resource state includes the resource state corresponding to the upper layer protocol (SDAP and/or PDCP) and the resource state corresponding to the lower layer protocol (RLC, MAC, physical layer), the state of the air interface transmission belongs to the resource corresponding to the lower layer protocol, and the secondary base station initiates a modification process of the secondary base station.

Step <NUM>: sending, by the secondary base station, a secondary base station modification requirement message, which the message is sent to the master base station.

The master base station/secondary base station may be an LTE base station or a <NUM> base station gNB. Both the master base station and the secondary base station are connected to the <NUM> core network, or the master base station is connected to the LTE core network and the secondary base station is connected to the <NUM> core network.

The state of the resource established for the radio bearer on the secondary base station has been changed, for example, if the upper layer protocol is originally established on the secondary base station, and the upper layer protocol has insufficient data processing capability currently, then the upper layer protocol (including SDAP and/or PDCP) needs to be established on the master base station, or if the lower layer protocol has insufficient data processing capability, or the lower layer protocol needs to be established on the master base station due to quality deterioration of the air interface signal, then the secondary base station sends the secondary base station modification required message to the master base station.

Specifically, the secondary base station establishment request message carries one or more of the following information:.

Step <NUM>: sending, by the master base station, a secondary base station modification request message to the secondary base station.

If the master base station accepts the modification of the secondary base station, the master base station sends a secondary base station modification request message to the secondary base station. If the master base station rejects the modification of the secondary base station, the messages of Steps <NUM> and <NUM> are not performed, and the master base station directly sends the message of Step <NUM>.

The secondary base station modification request message includes one or more of the following information:.

Step <NUM>: sending, by the secondary base station, a secondary base station modification response message to the master base station.

The secondary base station modification response message includes an identifier for successfully establishing a bearer, or a list of identifiers for successfully establishing a QoS Flow.

Step <NUM>: sending, by the master base station, a secondary base station modification acknowledge to the secondary base station.

The secondary base station modification acknowledge message includes one or more of the following information:
a list of information failed to be established, which the list may include an E-RAB identifier, or a DRB identifier, or a QoS Flow identifier.

<FIG> illustrates the third embodiment of the present application, which shows a modification process initiated by the secondary base station. When the state of the resource on the secondary base station changes, the resource state includes the resource state corresponding to the upper layer protocol (SDAP and/or PDCP) and the resource state corresponding to the lower layer protocol (RLC, MAC, physical layer), the state of the air interface transmission belongs to the resource corresponding to the lower layer protocol, and the secondary base station initiates a modification process of the secondary base station.

After receiving the indication information, the master base station may further determine which part of the resources on the secondary base station is still available, thereby determining whether to configure corresponding resources on the secondary base station. For example, the secondary base station indicates to release a certain bearer, and indicates that the resources corresponding to the upper layer protocol are overloaded, and the master base station may establish the upper layer resources of the bearer on the master base station, the lower layer resources of the bearer on the secondary base station. If the master base station does not know the indication information, the master base station may only release all the resources established on the secondary base station, including the resources corresponding to the upper layer protocol and the resource corresponding to the lower layer protocol.

Alternatively, it indicates which part of the resources is still available, for example, indicating one or more of the following:.

After receiving the indication information, the master base station may further determine which part of the resources on the secondary base station is still available, thereby determining whether to configure corresponding resources on the secondary base station. For example, the secondary base station indicates to release a certain bearer, and indicates that the resources corresponding to the upper layer protocol are overloaded, and the master base station may establish the upper layer resources of the bearer on the master base station, the lower layer resources of the bearer on the secondary base station. If the master base station does not know the indication information, the master base station may only release all the resources established on the secondary base station, including the resources corresponding to the upper layer protocol and the resource corresponding to the lower layer protocol. If the master base station determines to continue to use these resources, or configure to use a part of the resources on the secondary base station, the master base station sends a secondary base station modification request message to the secondary base station, in which the message including configuration information for the corresponding resources.

The message of the secondary base station modification acknowledge may include an RRC transparent container, which may include an RRC configuration complete message sent by the UE.

<FIG> schematically shows a structural block diagram of a master base station or a secondary base station that performs the method for establishing dual connectivity, according to an exemplary embodiment of the present application. As shown in <FIG>, the master or secondary base station includes a communication interface <NUM> for external communication; a processing unit or processor <NUM>, which may be a single unit or a combination of multiple units for performing different steps of the method; a memory <NUM>, storing computer executable instructions therein, that, when executed by the processor <NUM>, enable the master base station or the secondary base station to perform the embodiments of the present application.

When the instructions are executed by the processor <NUM>, if that shown in <FIG> is a master base station, the master base station <NUM> performs the following operations:.

In an exemplary embodiment, the secondary base station establishment request message may include one or more pieces of the following information:.

In an exemplary embodiment, the secondary base station establishment response message may include one or more of the following information:.

The processor <NUM> may be a single CPU (Central processing unit), but may also include two or more processing units. For example, the processor may include a general purpose microprocessor; an instruction set processor and/or a related chip sets and/or a special purpose microprocessor such as Application Specific Integrated Circuit (ASICs). The processor may also include board memory for caching purposes. The computer program may be carried by a computer program product connected to the processor. The computer program product may include a computer readable medium on which the computer program is stored. For example, the computer program product may be a flash memory, a Random-Access Memory (RAM), a Read-Only Memory (ROM), or an EEPROM, and the computer program modules described above in alternative embodiments could be distributed on different computer program products in the form of memories within the UE.

Claim 1:
A method for allocating a data radio bearer, DRB, identifier, ID, performed by a first node in a wireless communication system, the method comprising:
transmitting (<NUM>), to a second node, a request message for configuring the second node as a secondary node, SN, of a dual connectivity, DC, for a terminal, the first node being a master node, MN, of the DC, and the request message including information on a list of at least one available DRB ID for a bearer of the SN, wherein the at least one available DRB ID is not configured for the terminal by the first node; and
receiving (<NUM>), from the second node, a response message for the request message including information on a DRB ID assigned based on the list of the at least one available DRB ID, and a quality of service, QoS, flow ID mapped by the SN to the assigned DRB ID.