CN116367249A

CN116367249A - Method and device for switching service cells

Info

Publication number: CN116367249A
Application number: CN202211610771.3A
Authority: CN
Inventors: 汪巍崴; 柯小婉; 王弘; 许丽香
Original assignee: Samsung Electronics Co Ltd
Current assignee: Samsung Electronics Co Ltd
Priority date: 2017-08-10
Filing date: 2017-08-10
Publication date: 2023-06-30
Also published as: CN116112995A; CN109548095A; CN109548095B

Abstract

The embodiment of the invention provides a method and a device for switching a service cell, wherein the method for switching the service cell comprises the following steps: the auxiliary node sends an auxiliary node modification demand message to the main node, so that the main node switches the service cell according to the auxiliary node modification demand message and releases the load to be released; the auxiliary node receives an auxiliary node modification confirmation message returned by the main node aiming at the auxiliary node modification requirement message. The method provided by the embodiment of the invention realizes that when the bearer to be released exists when the service cell is switched, the service cell is switched according to the auxiliary node modification demand message and the bearer to be released on the auxiliary node is released, thereby greatly improving the signaling transmission efficiency and saving signaling resources.

Description

Method and device for switching service cells

The present application is a divisional application of the invention patent application with the application number 201710681888.3 and the invention name of a method and a device for switching a service cell.

Technical Field

The present invention relates to the field of wireless communication technologies, and in particular, to a method and an apparatus for switching a serving cell.

Background

To improve the throughput of users, LTE systems introduce the concept of dual connectivity (dual connectivity), i.e. one user can connect to two different base stations at the same time. In NR (New Radio access) networks or fifth generation 5G networks, the dual connectivity concept has been further extended, introducing multiple connections (MR-DC: multi-RAT Dual Connectivity) for multiple different access technologies, i.e. a user may access base stations supporting different access technologies at the same time, e.g. two base stations accessed by the user support LTE and NR, respectively. In the following discussion, we use MN (Master Node) and SN (Secondary Node) to represent two base stations to which a user has access, as shown in fig. 1. The possible air interface access technologies of each node include LTE, NR, etc., and each node can access the core network of the 5G system or the core network of the 4G/LTE system. In the above scenario, the following concepts are introduced:

■ MCG (Master Cell Group ): cell group accessed by the user on the MN. Among the MCG cells, one is a special Cell (PCell: primary Cell) and the rest is a Secondary Cell (SCell). The change of the PCell triggers a random access procedure for the user, while the first cell the user accesses to the MN is the PCell, and if there is a problem with the user's link with the PCell, the user cannot communicate with the MN (even if there is no problem with the SCell's link). The change of SCell may not trigger the random access procedure of the user.

■ SCG (Secondary Cell Group ): cell group accessed by users on SN. Among the SCG cells, one is a special cell (PScell: primary SCell), and the other is a secondary cell of SCG (SCG SCell: SCG Secondary Cell). A change in PSCell triggers a random access procedure for the user while the first cell that the user accesses the SN is a PSCell, and if there is a problem with the user's link with the PSCell, the user cannot communicate with the SN (even though there is no problem with the SCG SCell's link). A change of SCG SCell may not trigger the random access procedure of the user.

For a detailed description of the concepts described above, see TS36.300 v14.2.0.

Under MN and SN architecture, the radio bearers of a user include four types:

■ MCG Bearer (MCG Bearer): the data of the bearer is transmitted via MN and user, and protocol layer for processing the data of the bearer is located in MN

■ MCG Split Bearer (MCG Split Bearer): the data of the bearer is transmitted to the user via MN and SN, but PDCP (packet data convergence protocol) Layer processing the data of the bearer is located at MN, and other protocol layers (RLC (Radio link control, radio link control)/MAC (Medium Access Control), physical Layer)/PHY (Physical Layer)) processing the data of the bearer are located on both MN and SN.

■ SCG bearer (SCG bearer): the data carried by the user is transmitted with the user via the SN, and the protocol layer for processing the data carried by the user is positioned in the SN

■ SCG split bearer (SCG split bearer): the data of the bearer is transmitted with the user via the MN and SN, but the PDCP layer processing the data of the bearer is located at the SN, and the MN and SN have other protocol layers (RLC/MAC/PHY) processing the data of the bearer.

For a detailed description of the concepts described above, see TS37.340.

The concepts described above with respect to cells and bearers are both for one user.

In addition, in the NR (New Radio access) network or the fifth-generation 5G network, in order to support network function virtualization, more efficient resource management and scheduling, a base station (e.g., a gNB) providing a wireless network interface for a terminal (UE) may be further divided into a centralized unit CU (central unit) and a distributed unit DU (distributed unit). The CU has at least Radio Resource Control (RRC) and Packet Data Convergence Protocol (PDCP) protocol layers, etc., and may also include service data adaptation protocol (SDAP: service Data Adaptation Protocol). The DUs have radio link control protocol (RLC), medium Access Control (MAC), physical layer, etc. Between CU and DU is a standardized public interface F1. The F1 interface is divided into a control plane F1-C and a user plane F1-U. The transport network layer of F1-C is based on IP transport. For more reliable signaling transmission, SCTP (Stream Control Transmission Protocol ) protocols are added over IP. The protocol of the application layer is F1AP. SCTP may provide reliable application layer messaging. The transport layer of F1-U is UDP/IP (User Datagram Protocol/Internet Protocol ), GTP-U (GPRS Tunnelling Protocol for the user plane, user plane GPRS tunneling protocol) is used to carry user plane protocol data units PDU over UDP/IP, and FIG. 2 shows the structure of CUs and DUs.

In the above description, if there is an interface between two nodes serving the user plane of a user (such as X2-U between MN and SN, F1-U between CU and DU, and X2-U between MN and DU), a tunnel is established when transmitting user data between the two nodes, and this tunnel corresponds to two addresses (address 1 and address 2) which are respectively used by the two nodes to transmit data for the user, i.e. the user data is sent from address 1 to address 2 or from address 2 to address 1.

In combination with the above-described techniques of multiple connections and CU-DU separation, the manner in which a user connects to the network may be: the user accesses both the MN and the SN, and the SN includes a CU and at least one DU connected to the CU, as shown in fig. 3. In this scenario, there is a possibility that the PSCell on the SN accessed by the user may change, and the reason for this change may be that the quality of the current PSCell is not good, the current PSCell is overloaded, etc. Such changes may include, but are not limited to, the following:

■ The PSCell is changed from the current PSCell to an SCG SCell belonging to the same DU that has been configured to the user.

■ The PSCell is changed from the current PSCell to a cell belonging to the same DU that is not allocated to the user.

■ The PSCell is changed from the current PSCell to a cell belonging to another DU (the other DU is connected to the same CU as the DU in which the current PSCell is located, i.e. belonging to the same SN), as shown in fig. 4.

■ The PSCell is changed from the current PSCell to a cell belonging to another DU (the other DU is connected to a different CU than the DU in which the current PSCell is located, i.e. belonging to a different SN), as shown in fig. 5.

When the PSCell change occurs, according to the LTE system, an SN modification procedure initiated by an SN node (in which a message sent and received by an SN is actually sent and received by a CU) is triggered:

■ Step 1: the SN sends a secondary node modification need (SN modification required) message to the MN, which contains SCG change indication information (SCG Change Indication: the information indicates PSCell change, in practice, the indication message may also indicate other information) and SCG configuration information (SCG-Config, e.g. configuration of the serving cell, SCG, of the user on the SN, possibly including RLC configuration, MAC layer configuration, etc.).

■ Step 2&3: these two steps are optional steps that are triggered when the MN is to provide an address for data forwarding and/or an encryption key for a new SN.

■ Step 4: if the configuration of the PSCell change is successfully completed, the MN replies to the SN with a secondary node modification acknowledgement (SN modification confirm) message.

The above procedure can be seen in TS36.300 v14.2.0.

According to the existing mechanism, in the above step 1, the SCG change indication information and the SCG configuration information (SCG-Config) must occur simultaneously, and if there is information about releasing the bearer in step 1, the SCG change indication information is not allowed to occur in step 1, that is, the existing mechanism does not support the simultaneous occurrence of the change of PSCell and the release of the bearer.

Disclosure of Invention

The object of the present invention is to solve at least one of the above technical drawbacks, in particular the technical drawbacks of having a bearer to be released when a handover to a serving cell cannot be achieved.

According to one aspect, an embodiment of the present invention provides a method for switching a serving cell, including:

the auxiliary node sends an auxiliary node modification demand message to the main node, so that the main node switches the service cell according to the auxiliary node modification demand message and releases the bearer to be released;

and the auxiliary node receives an auxiliary node modification confirmation message returned by the main node aiming at the auxiliary node modification demand message.

According to another aspect, an embodiment of the present invention further provides a method for switching a serving cell, including:

the method comprises the steps that a main node receives an auxiliary node modification demand message sent by an auxiliary node, switches a service cell according to the auxiliary node modification demand message and releases a bearer to be released;

And the main node returns an auxiliary node modification confirmation message aiming at the auxiliary node modification requirement message to the auxiliary node.

According to another aspect, an embodiment of the present invention further provides an apparatus for switching a serving cell, including:

the first sending module is used for sending an auxiliary node modification demand message to the main node by the auxiliary node so that the main node switches the service cell and releases the bearing to be released according to the auxiliary node modification demand message;

and the first receiving module is used for receiving the auxiliary node modification confirmation message returned by the main node aiming at the auxiliary node modification requirement message by the auxiliary node.

the second receiving module is used for receiving an auxiliary node modification demand message sent by an auxiliary node by the main node, switching a service cell according to the auxiliary node modification demand message and releasing a bearing to be released;

and the second sending module is used for returning an auxiliary node modification confirmation message aiming at the auxiliary node modification requirement message to the auxiliary node by the main node.

The embodiment of the invention provides a method for switching a service cell, which is characterized in that an auxiliary node sends an auxiliary node modification demand message to a main node, so that the main node switches the service cell according to the auxiliary node modification demand message and releases a bearer to be released, thereby providing preconditions for releasing a user bearer on the auxiliary node when the auxiliary node is switched according to the auxiliary node modification demand message, the auxiliary node receives an auxiliary node modification confirmation message returned by the main node aiming at the auxiliary node modification demand message, when the bearer to be released exists in the switching of the service cell, the service cell is switched according to the auxiliary node modification demand message and the bearer to be released on the auxiliary node is released, the signaling transmission efficiency is greatly improved, and signaling resources are saved.

Additional aspects and advantages of the invention will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention.

Drawings

The foregoing and/or additional aspects and advantages of the invention will become apparent and readily appreciated from the following description of the embodiments, taken in conjunction with the accompanying drawings, in which:

fig. 1 is a diagram of a network structure of a UE multi-connection in the prior art;

fig. 2 is a block diagram of a base station concentration unit and a distribution unit in the prior art;

fig. 3 is a diagram showing a network structure in which a UE is connected to a multi-connection including a centralized unit and a distributed unit in the prior art;

FIG. 4 is a schematic diagram of a prior art change service subscriber distribution unit;

FIG. 5 is a schematic diagram of a service auxiliary node for changing users in the prior art;

fig. 6 is a flowchart of a method of switching serving cells according to a first embodiment of the present invention;

fig. 7 is a flowchart of a method for switching serving cells according to a second embodiment of the present invention;

FIG. 8 is a signaling flow diagram of a service distribution unit for changing a user through a user context setup procedure according to an embodiment of the present invention;

fig. 9 is a signaling flow chart for changing the configuration of a distribution unit of a user at the same auxiliary node through a user context establishment procedure according to an embodiment of the present invention;

Fig. 10 is a signaling flow chart of a first modification of PSCell of a user on a distribution element of a secondary node according to an embodiment of the present invention;

fig. 11 is a signaling flow diagram of a second modification of PSCell of a user on a secondary node according to an embodiment of the present invention;

fig. 12 is a signaling flow diagram of a third modification of PSCell of a user on a secondary node distribution element according to an embodiment of the present invention;

fig. 13 is a signaling flow diagram of a secondary node modification triggered by a secondary node according to an embodiment of the present invention;

FIG. 14 is a signaling flow diagram of user context establishment between a centralized unit and a distributed unit according to an embodiment of the present invention;

FIG. 15 is a signaling flow diagram of a centralized unit triggered user context modification in accordance with an embodiment of the present invention;

FIG. 16 is a signaling flow diagram (two steps) of a first distributed element triggered user context modification according to an embodiment of the present invention;

FIG. 17 is a signaling flow diagram (three or four steps) of a second distributed element triggered user context modification according to an embodiment of the present invention

Fig. 18 is a schematic structural diagram of an apparatus for switching serving cells according to a third embodiment of the present invention;

fig. 19 is a schematic structural diagram of an apparatus for switching serving cells according to a fourth embodiment of the present invention.

Detailed Description

Embodiments of the present invention are described in detail below, examples of which are illustrated in the accompanying drawings, wherein like or similar reference numerals refer to like or similar elements or elements having like or similar functions throughout. The embodiments described below by referring to the drawings are illustrative only and are not to be construed as limiting the invention.

As used herein, the singular forms "a", "an", "the" and "the" are intended to include the plural forms as well, unless expressly stated otherwise, as understood by those skilled in the art. It will be further understood that the terms "comprises" and/or "comprising," when used in this specification, specify the presence of stated features, integers, steps, operations, elements, and/or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and/or groups thereof. It will be understood that when an element is referred to as being "connected" or "coupled" to another element, it can be directly connected or coupled to the other element or intervening elements may also be present. Further, "connected" or "coupled" as used herein may include wirelessly connected or wirelessly coupled. The term "and/or" as used herein includes all or any element and all combination of one or more of the associated listed items.

It will be understood by those skilled in the art that all terms (including technical and scientific terms) used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs unless defined otherwise. It will be further understood that terms, such as those defined in commonly used dictionaries, should be interpreted as having a meaning that is consistent with their meaning in the context of the prior art and will not be interpreted in an idealized or overly formal sense unless expressly so defined herein.

As used herein, a "terminal" or "terminal device" includes both a device of a wireless signal receiver having no transmitting capability and a device of receiving and transmitting hardware having receiving and transmitting hardware capable of bi-directional communication over a bi-directional communication link, as will be appreciated by those skilled in the art. Such a device may include: a cellular or other communication device having a single-line display or a multi-line display or a cellular or other communication device without a multi-line display; a PCS (Personal Communications Service, personal communication system) that may combine voice, data processing, facsimile and/or data communication capabilities; a PDA (Personal Digital Assistant ) that can include a radio frequency receiver, pager, internet/intranet access, web browser, notepad, calendar and/or GPS (Global Positioning System ) receiver; a conventional laptop and/or palmtop computer or other appliance that has and/or includes a radio frequency receiver. As used herein, "terminal," "terminal device" may be portable, transportable, installed in a vehicle (aeronautical, maritime, and/or land-based), or adapted and/or configured to operate locally and/or in a distributed fashion, to operate at any other location(s) on earth and/or in space. The "terminal" and "terminal device" used herein may also be a communication terminal, a network access terminal, and a music/video playing terminal, for example, may be a PDA, a MID (Mobile Internet Device ), and/or a mobile phone with a music/video playing function, and may also be a smart tv, a set top box, and other devices.

In a 5G network, where a user connects to both MN and SN, and SN includes a CU and at least one DU connected to the CU, a change in PSCell may cause a release of the user bearer. For example, because the user's PSCell needs to be changed, e.g. from one DU (DU 1) to another DU (DU 2) connected to the same CU, one PSCell and multiple SCG scells are currently configured for this user on DU1, but only one cell is suitable on DU2, so only one PSCell can be configured for this user on DU2, in other words, in this process the cell serving this user is changed from multiple cells on DU1 to one on DU2, which may have to release some bearers served for the user by SN. Such a scenario is when a PSCell change occurs simultaneously with a bearer release. The existing mechanism does not support the concurrence of PSCell change and bearer release. In addition, in order to support such a scenario, a procedure of establishing and modifying a user context is also performed between the CU and the DU, and an operation of establishing and modifying a context of a serving cell for a user needs to be considered in these procedures, which is not referred to in the prior discussion.

In addition, in a 5G network, a user will connect to both the MN and SN, while SN includes a CU and at least one DU connected to the CU. In this scenario, the user's PSCell may change while the user bearer on the SN may be released. To support this, embodiments of the present invention provide a flow of signaling interactions between MN and SN and a flow of user context establishment and modification between CU and DU, as follows.

In order to solve the technical defect that the bearer to be released exists when the serving cell cannot be switched in the prior art, a first embodiment of the present invention provides a method for switching the serving cell, and a specific flow is shown in fig. 6, including: step 610, the auxiliary node sends an auxiliary node modification demand message to the main node, so that the main node switches the service cell according to the auxiliary node modification demand message and releases the bearer to be released; step 620, the secondary node receives the secondary node modification confirmation message returned by the primary node for the secondary node modification requirement message.

Preferably, the secondary node modification requirement message includes at least one of: the method comprises the steps of carrying information to be released, indication information of SCG change of a secondary cell group, first indication information, second indication information, third indication information, SCG configuration information and unreleased carrying information.

Preferably, the information of the bearer to be released and the information of the unreleased bearer include at least one of the following: the method comprises the steps of carrying identification information, carrying quality of service QoS parameters, carrying type information, transmitting tunnel address information of carried data between two nodes, carrying forward address of uplink data and carrying forward address of downlink data; the indication information of the SCG change is used for indicating a primary cell PScell of the changed SCG; the SCG configuration information is related configuration information about SCGs configured for the UE, which is generated by the secondary node; the first indication information is used for indicating the main node to trigger sending an auxiliary node modification request message to the auxiliary node; the second indication information is used for indicating the master node to prohibit sending SCG configuration information to the user terminal UE; the third indication information is used for indicating the auxiliary node to inhibit updating of the SCG configuration information; the information of the unreleased bearer comprises information of each unreleased bearer and/or information of the unreleased master cell group MCG split bearer, wherein the information of the unreleased master cell group MCG split bearer comprises an identifier of the bearer and address information of a tunnel for transmitting data of the bearer on a secondary node side.

Preferably, after the step of sending the secondary node modification requirement message to the primary node, the secondary node further includes: the secondary node sends the SCG configuration information to the UE.

Preferably, before the step of the secondary node receiving the secondary node modification confirmation message returned by the primary node for the secondary node modification requirement message, the method further comprises: receiving an auxiliary node modification request message sent by a main node; and sending a secondary node modification request confirmation message aiming at the secondary node modification request message to the primary node.

Preferably, the secondary node modification request message comprises at least one of: the method comprises the steps of adding information of a bearer to be modified, information of a bearer to be released, encryption key information of an auxiliary node, SCG change indication information and information for configuring SCG, wherein the information for configuring SCG is information which is generated by a main node and is used for requesting UE to establish or modify or release SCG; the secondary node modification request acknowledgement message includes at least one of: the method comprises the steps of receiving newly added bearer information, receiving bearer information to be modified, receiving bearer information to be released, SCG configuration information and information of unreleased MCG split bearer.

Preferably, before the step of sending the secondary node modification requirement message to the primary node, the method further comprises: the auxiliary node performs corresponding UE context establishment or corresponding UE context modification.

Preferably, the secondary node comprises a centralized unit CU and at least one distributed unit DU connected to said CU, and the step of the secondary node performing a corresponding UE context establishment comprises: sending a UE context establishment request message to the DU through the CU; and receiving a UE context establishment response message returned by the DU for the UE context establishment request message through the CU.

Preferably, the UE context setup request message includes at least one of: cell list information, information of newly added cells sent by CU, context information related to UE load and/or identification, and cause information of UE context are established; the UE context setup response message includes at least one of: the identification information of the non-accepted cell, the context information related to the UE bearing and/or identification, the DU returns the reason information of the UE context establishment response message, and the information of the newly added cell sent by the DU; the cell list information includes at least one of: cell identification, cell measurement result; the information of the newly added cell sent by the CU comprises the information of the newly added cell determined by the CU or the information of the alternative newly added cell determined by the CU; the information of the new cell determined by the CU includes at least one of the following: cell list information, identification information of one or more PCell cells, identification information of one or more SCell cells, identification information of one or more PScell cells, identification information of one or more SCG SCell cells, and measurement information of cells; the information of the new cell which is determined by the CU and is an alternative, at least comprises one of the following: alternative cell list information, alternative identification information of one or more PCell cells, alternative identification information of one or more SCell cells, alternative identification information of one or more PSCell cells, alternative identification information of one or more SCG SCell cells, alternative measurement information of a newly added cell; the information of the newly added cell transmitted by the DU at least comprises one of the following items: an identification of the selected PCell cell, an identification of the selected one or more SCell cells, an identification of the selected PSCell cell, an identification of the selected one or more SCG SCell cells; the context information related to the UE bearer and/or identity includes at least one of the following information: information carried by the user, and identification information of the user; the reason information for establishing the UE context and the reason information for the DU returning the UE context establishment response message include at least one of the following information: cell overload, cell uplink overload, cell downlink overload, cell uplink control channel overload, load balancing, poor signal quality or strength of the UE in the cell, poor quality or strength of the UE in the uplink or downlink signal of the cell; the reason information for establishing the UE context and the DU return UE context establishment response message are per cell or per all cells.

Preferably, the secondary node comprises a centralized unit CU and at least one distributed unit DU connected to the CU, and the step of the secondary node performing a corresponding UE context modification comprises: sending a UE context modification request message to the DU through the CU; and receiving a UE context modification response message returned by the DU for the UE context modification request message through the CU.

Preferably, the secondary node comprises a centralized unit CU and at least one distributed unit DU connected to said CU, the step of the secondary node performing a corresponding UE context modification comprising: sending a UE context modification requirement message to the CU through the DU; and receiving a UE context modification confirmation message returned by the CU for the UE context modification requirement message through the DU.

Preferably, the secondary node comprises a centralized unit CU and at least one distributed unit DU connected to said CU, said secondary node performing the step of corresponding UE context modification, comprising:

sending a UE context modification requirement message to the CU through the DU;

sending a UE context modification request message to the DU through the CU;

and receiving a UE context modification response message returned by the DU for the UE context modification request message through the CU.

Preferably, after the step of receiving, by the CU, a UE context modification response message returned by the DU for the UE context modification request message, the method further includes:

And receiving a UE context modification confirmation message returned by the CU through the DU.

Compared with the prior art, the first embodiment of the invention provides a method for switching the service cell, the auxiliary node sends the auxiliary node modification demand information to the main node, so that the main node switches the service cell according to the auxiliary node modification demand information and releases the bearer to be released, a precondition guarantee is provided for releasing the user bearer on the auxiliary node when the service cell is switched according to the auxiliary node modification demand information, the auxiliary node receives the auxiliary node modification confirmation information returned by the main node aiming at the auxiliary node modification demand information, when the bearer to be released exists when the service cell is switched, the service cell is switched according to the auxiliary node modification demand information and the bearer to be released on the auxiliary node is released, the signaling transmission efficiency is greatly improved, and the signaling resources are saved.

In addition, in order to solve the technical defect that the bearer to be released exists when the serving cell cannot be switched in the prior art, a second embodiment of the present invention further provides a method for switching the serving cell, and a specific flow is shown in fig. 7, including: step 710, the master node receives the auxiliary node modification requirement message sent by the auxiliary node, switches the serving cell according to the auxiliary node modification requirement message, and releases the bearer to be released; in step 720, the master node returns a secondary node modification confirm message for the secondary node modification requirement message to the secondary node.

The second embodiment of the invention provides a method for switching the service cell, which realizes that when the service cell is switched and the bearer to be released exists, the main node can switch the service cell according to the received auxiliary node modification demand message and release the bearer to be released on the SN, thereby greatly improving the signaling transmission efficiency and saving signaling resources.

The above-described embodiments of the present invention will be described in more detail below in terms of various aspects:

among the above embodiments of the present invention mainly solve the problems: when a user connects to both MN and SN, the primary cell PSCell of the user UE changes and some of the SN-serviced bearers of the user need to be released. The primary cell PSCell is hereinafter referred to as a special cell PSCell, and the change of PSCell may occur in the same DU or between different DUs. When this happens between different DUs, the address of the tunnel (the tunnel between MN and DU) used to send the MCG split bearer data will change. The names of the signaling in the signaling flow described below are examples only, and other names may be employed. Some general information that will be used in the following description will be described in detail as follows:

■ The information of the bearer may be a new added bearer, or a bearer to be modified, or a bearer to be released, or an accepted new added bearer, or an accepted bearer to be modified, or an accepted bearer to be released, or a rejected new added bearer, or a rejected bearer to be modified, or a rejected bearer to be released, including one or more of the following information:

■ And carrying identification information.

■ The QoS parameters of the bearer, such as QoS Class Identifier (QoS class identifier), 5G QoS Indicator (5G QoS identifier), allocation and Retention Priority (assign and maintain priority), non-standardised QoS Flow descriptor (Non-standardized QoS flow descriptor), etc. (see protocol TS36.423, protocol TS38.423 for details).

■ Bearer type information, such as MCG bearer, MCG split bearer, SCG split bearer.

■ Address information of tunnels used for transferring data carried between two nodes, such as GTP tunnel endpoint information (GTP Tunnel Endpoint, see protocol TS 36.423), includes transport layer address information (Transport layer address, see protocol TS36.424, TS 36.414) and/or GTP tunnel endpoint identification (GTP Tunnel Endpoint Identifier, see protocol TS 29.281). The two nodes may be MN and SN, or MN and SN centralized units, or MN and SN distributed units, or centralized units and distributed units, respectively, where the address information is address information of a node on one side, such as MN, SN centralized units, SN distributed units, base station centralized units, base station distributed units, etc.

■ A forwarding address (UL forwarding GTP Tunnel Endpoint) of the carried upstream data, such as an address of the node side transmitting the carried information.

■ A forwarding address (DL forwarding GTP Tunnel Endpoint) of the carried downstream data, such as an address of the node side transmitting the carried information.

Indication information (SCG Change Indication) of SCG change, which may indicate PSCell change, but also other content, such as PDCP Count Wrap Around (PDCP count wrap around), etc.

SCG configuration information (SCG-Config), which is related configuration information generated by the SN regarding the SCG configured for the user, such as configuration of PSCell, configuration of SCG SCell, RLC configuration, MAC layer configuration, etc.

A message for configuring SCG (SCG-configmnfo), which is a request user generated by MN to perform establishment, modification and release of SCG, and MN will also provide some auxiliary information for helping SN to generate SCG-Config in the message.

In order to simplify the following text description, the specific contents of the above information are represented by the information carried, the indication information of the SCG change, and the SCG configuration information (SCG-Config), unless otherwise specified.

First, an example of a relevant signaling flow is given:

1) The PSCell and the new PSCell of the embodiments of the present invention belong to different DUs (CU triggered UE context setup procedure), as shown in fig. 8.

2) The PSCell and the new PSCell of the embodiment of the present invention belong to the same DU (CU triggered UE context setup procedure), as shown in fig. 9.

3) The PSCell and the new PSCell of the present invention belong to the same DU (CU triggered UE context modification procedure), as shown in fig. 10.

4) The PSCell and the new PSCell of the present invention belong to the same DU (DU triggered UE context modification procedure), as shown in fig. 11.

5) The signaling flow chart of modifying the PSCell of the user on the distribution unit of the secondary node according to the embodiment of the present invention is shown in fig. 12.

The signaling procedure described above can be divided into two parts: a) Signaling flow between MN and SN (or a centralized unit in SN); b) Signaling flow between centralized unit and distributed unit in SN; these two parts are described below:

signalling flow between MN and SN

Fig. 13 shows a signaling flow between MN and SN in fig. 8 to 12. The signaling flow between MN and SN described below is applicable not only to the signaling flows shown in fig. 8-12, but also to other situations, such as the case of secondary node modification that results in secondary node triggering.

Step 1: the secondary node (or secondary node-hub unit) sends a secondary node modification requirement (SN modification required) message to the primary node, the message containing information of one or more of the following:

■ Information of the bearer to be released;

■ Indication information of SCG change, the information indicating a change of PSCell;

■ New indication information indicating that the master node needs to trigger step 2;

■ No indication information of SCG configuration information (SCG-Config) is required to be sent to the user;

■ No update of the indication information of the SCG configuration information (SCG-Config) is required;

■ SCG configuration information (SCG-Config);

■ The information about the unreleased bearers may be about each unreleased bearer or about a part of the unreleased bearers (e.g. unreleased MCG split bearers). If the user is connected to both MN and SN (or a distribution unit of SN), in this information, the address information refers to address information on the SN side or on the centralized unit side of SN or on the distribution unit side of SN.

Step 2: the master node sends a secondary node modification request (SN modification request) message to the secondary node (or secondary node-hub unit), the message including one or more of the following information:

■ Newly added bearing information;

■ Information of the bearer to be modified;

■ Information of the bearer to be released;

■ Encryption key information of the auxiliary node;

■ Indication of SCG change;

■ Message for configuring SCG (SCG-configmnfo).

Step 3: the secondary node (or secondary node-hub unit) sends a secondary node modification request acknowledgement (SN modification request acknowledge) message to the primary node, the message containing information of one or more of the following:

■ The accepted newly added bearer information;

■ The received information of the bearer to be modified;

■ The accepted information of the bearer to be released;

■ SCG configuration information (SCG-Config);

step 4: the master node sends a secondary node modification acknowledgement (SN modification confirm) message to the secondary node (or secondary node-hub unit), which may include a message for configuring the SCG (SCG-configmnfo).

It should be noted that, in the above steps, steps 2 and 3 are optional steps. The condition triggering step 2 may be any of the following:

■ The step 1 comprises the indication information triggering the step 2;

■ The following information is contained in step 1:

■ Information-bearing to be released, and

■ One or more of the following information:

indication information of SCG change, which indicates change of PSCell

SCG configuration information (SCG-Config)

The information about the unreleased bearers may be about each unreleased bearer, or about a part of the unreleased bearers (e.g., unreleased MCG split bearers). If the user is connected to both MN and SN (or a distribution unit of SN), in this information, the address information refers to address information on the SN side or on the centralized unit side of SN or on the distribution unit side of SN.

The above procedure has several detailed embodiments (possible trigger conditions of these detailed embodiments are that when the SN determines that the PSCell of the user changes and there is a bearer that needs to be released, the change of PSCell occurs in the same distribution unit or in a different distribution unit; other trigger conditions are not excluded).

Specific examples will be described below.

Specifically, the specific procedure of the detailed embodiment one (including two steps, i.e., step 1 and step 4, and the MN sending SCG-Config to the user equipment UE) is as follows:

step 1: the secondary node (or secondary node-hub unit) sends a secondary node modification requirement (SN modification required) message to the primary node, the message containing the following information:

■ Information of the bearer to be released;

■ Optionally, an indication of the SCG change, the information indicating a change of PSCell;

■ SCG configuration information (SCG-Config);

■ Optionally, the information of the unreleased MCG split bearer at least includes the following information:

■ A carried identifier;

■ The tunnel used for transmitting the carried data is address information on the SN side or the distribution unit side of the SN.

Among the above information, the indication information of the SCG change is an option, which can implicitly indicate that the PSCell of the user is to be changed by including the information of the unreleased MCG split bearer and/or SCG configuration information (SCG-Config) in step 1.

Step 2/3: these two steps are not required.

Step 4: the master node sends a secondary node modification acknowledgement (SN modification confirm) message to the secondary node (or secondary node-hub).

The master node then sends the SCG configuration information (SCG-Config) received in step 1 to the user, which may be after step 1.

Specifically, the specific procedure of the second detailed embodiment (including two steps, i.e., step 1 and step 4, and SN sending SCG-Config to the UE) is as follows:

step 1: the secondary node (or secondary node-hub unit) sends a secondary node modification requirement (SN modification required) message to the primary node, the secondary node containing the following information:

■ Information of the bearer to be released;

the identity of the bearer;

the tunnel used for transmitting the carried data is the address information of the SN side or the SN distribution unit side.

Among the above information, the indication information of SCG change is an option, which can implicitly indicate that the PSCell of the user is changed by including the information of the unreleased MCG split bearer in step 1.

Step 2/3: these two steps are not required.

Wherein the secondary node generates SCG configuration information (SCG-Config) before step 1 or between steps 1 and 4, and the secondary node sends to the user after step 1.

Specifically, the specific procedure of the third embodiment (including four steps, i.e., step 1 to step 4, no SCG configuration information (SCG-Config) in step 1) is as follows:

■ Information of the bearer to be released;

■ Optionally, an indication of SCG change, which indicates a change of PSCell, or, optionally, a new indication, which indicates that the master node needs to trigger step 2;

■ A carried identifier;

Among the above information, the indication information of SCG change is an option, which may implicitly indicate that the PSCell of the user is changed by including the information of the unreleased MCG split bearer in step 1, or implicitly indicate that the master node needs to trigger step 2.

■ Newly added bearing information;

■ The information of the bearer to be modified may include bearer information after the bearer type modification for the bearer to be released in the step 1;

■ Information of the bearer to be released;

■ Encryption key information of the auxiliary node;

■ Indication of SCG change;

■ Message for configuring SCG (SCG-configmnfo).

■ SCG configuration information (SCG-Config);

■ A carried identifier;

In the above steps, the SCG configuration information (SCG-Config) may be sent to the user by the secondary node or may be sent to the user by the primary node. If the secondary node sends the configuration information (SCG-Config) to the user after step 1, the secondary node (e.g., the SCG configuration information (SCG-Config) generated after step 2), and then step 3 does not need to include the SCG configuration information (SCG-Config). Yet another embodiment is that in step 3, the SCG configuration information (SCG-Config) is included, but the configuration information is sent by the secondary node, and the secondary node adds indication information in the secondary node modification requirement (SN modification required) message of step 1 or the secondary node modification request acknowledgement (SN modification request acknowledge) message of step 3, indicating that the primary node does not need to send the SCG configuration information (SCG-Config). If sent by the master node, one implementation is that the SCG configuration information (SCG-Config) is contained in step 3, and the master node sends the SCG configuration information (SCG-Config) received in step 3.

Specifically, the specific procedure of the fourth detailed embodiment (including four steps, i.e., steps 1 to 4, there is SCG configuration information (SCG-Config) in step 1 and SCG-Config is updated in step 3) is as follows:

■ Information of the bearer to be released;

■ SCG configuration information (SCG-Config);

■ A carried identifier;

Among the above information, the indication information of SCG change is an option, which may implicitly indicate that the PSCell of the user is to be changed by including the information of the unreleased MCG split bearer and/or the SCG configuration information (SCG-Config) in step 1, or implicitly indicate that the master node needs to trigger step 2.

■ Newly added bearing information;

■ Information of the bearer to be released;

■ Encryption key information of the auxiliary node;

■ Indication of SCG change;

■ Message for configuring SCG (SCG-configmnfo).

■ SCG configuration information (SCG-Config);

■ A carried identifier;

the tunnel used for transmitting the carried data is address information on the SN side or the distribution unit side of the SN. Step 4: the master node sends a secondary node modification acknowledgement (SN modification confirm) message to the secondary node (or secondary node-hub).

In the above steps, the SCG configuration information (SCG-Config) may be sent to the user by the secondary node or may be sent to the user by the primary node. One implementation is that the secondary node will generate SCG configuration information (SCG-Config) after step 2 if sent by the secondary node, and step 3 need not contain SCG configuration information (SCG-Config). In another embodiment, the secondary node sends the SCG configuration information (SCG-Config) in step 1 to the user, and then sends the SCG configuration information (SCG-Config) generated after step 2 to the user. Yet another embodiment is that in step 3, the SCG configuration information (SCG-Config) is included, but the configuration information is sent by the secondary node after step 3, and the secondary node adds indication information in the secondary node modification requirement (SN modification require) message of step 1 or the secondary node modification request acknowledgement (SN modification request acknowledge) message of step 3, indicating that the primary node does not need to send the SCG configuration information (SCG-Config). If sent by the master node, one embodiment is that step 3 contains SCG configuration information (SCG-Config), and the master node sends the SCG configuration information (SCG-Config) received in step 3. In yet another embodiment, the master node first transmits the SCG configuration information (SCG-Config) in step 1, and then transmits the SCG configuration information (SCG-Config) received in step 3. Or the SCG configuration information (SCG-Config) in the step 1 is sent by the main node, and the SCG configuration information (SCG-Config) generated after the step 2 is sent by the auxiliary node; in another embodiment, the SCG configuration information (SCG-Config) in step 1 is sent by the secondary node, and the SCG configuration information (SCG-Config) generated after step 2 is sent by the primary node, and then the SCG configuration information (SCG-Config) is included in step 3.

Specifically, the specific procedure of the fifth embodiment (including four steps, i.e., steps 1 to 4, where there is SCG configuration information (SCG-Config) in step 1 and SCG-Config is not updated in step 3) is as follows:

step 1: the secondary node (or secondary node-hub unit) sends a secondary node modification requirement (SN modification require) message to the primary node, the message containing the following information:

■ Information of the bearer to be released;

■ SCG configuration information (SCG-Config);

■ A carried identifier;

Among the above information, the indication information of the SCG change is an option, which may implicitly indicate that the PSCell of the user is to be changed by including the information of the unreleased MCG split bearer and/or the SCG configuration information (SCG-Config) in step 1, or implicitly indicate that the master node needs to trigger step 2.

■ Newly added bearing information;

■ Information of the bearer to be released;

■ Encryption key information of the auxiliary node;

■ Indication of SCG change;

■ Message for configuring SCG (SCG-configmnfo).

Step 3: the secondary node (or secondary node-hub unit) sends a secondary node modification request acknowledgement (SN modification request acknowledge) message to the primary node, which message does not contain SCG configuration information (SCG-Config), optionally containing information of unreleased MCG split bearers.

In the above steps, the secondary node may transmit SCG configuration information (SCG-Config) to the user, or the primary node may transmit SCG configuration information (SCG-Config) to the user. If transmitted by the secondary node, one embodiment is that the secondary node may transmit after step 1/2/3/4, alternatively the secondary node may indicate in step 1 or step 3 that the primary node does not need to transmit SCG configuration information (SCG-Config) to the user. Yet another embodiment is that in step 3 SCG configuration information (SCG-Config) is included, but this configuration information is sent by the secondary node after step 3, and the secondary node adds indication information in a secondary node modification request acknowledge (SN modification request acknowledge) message of step 3, indicating that the primary node does not need to send SCG configuration information (SCG-Config). If sent by the master node, one implementation is that the master node may send after step 1/2/3/4 the SCG configuration information (SCG-Config) received in step 1.

B. Signaling flow between centralized unit and distributed unit

The signaling flow includes a user context setup flow and a user context modification flow. These two flows are used in fig. 8 to 12, respectively, but the user context establishment flow and the user context modification flow described below are not limited to the flows in fig. 8 to 12, and may be used in other cases where user contexts need to be established and modified between the centralized node and the distributed node.

B-1 user context establishment procedure

The procedure comprises two steps, as shown in fig. 14:

step 1: the central unit sends a user context setup request (UE Context Setup Request) message to the distribution units, the message including one or more of the following information:

■ Cell list information, the list comprising one or more cells, the information comprising one or more of the following information:

■ Cell identification;

■ The measurement results of the cell, such as signal quality, signal strength, etc.

■ Information of the newly added cell transmitted by the CU, which may be the newly added cell already determined by the centralizing unit, or may be an alternative newly added cell, and the information includes one or more of the following information:

■ Cell list information including identities of one or more cells;

■ Identification information of one or more PCell cells;

■ Identification information of one or more SCell cells;

■ Identification information of one or more PSCell cells;

■ Identification information of one or more SCG SCell cells;

■ Measurement information of the cell, such as signal quality, signal strength, etc.

■ The context related to the user bearer and/or identification, such as information of the user bearer, identification information of the user (such as an ID used by the user on the interface between the centralized unit and the distributed unit, e.g. a CU UE F1AP ID, which may be newly assigned by the CU or already assigned to the user by the CU, or both).

■ The reason information for establishing the user context can be specific to each cell, or specific to all modifications, and possible reasons include one or more of cell overload, cell uplink or downlink overload, cell uplink control channel overload, load balancing, poor signal quality or strength of the user in the cell, poor quality or strength of the user uplink or downlink signal in the cell, and the like.

Step 2: the distribution unit decides whether to accept the request of step 1 according to its own access control criteria, and then replies a user context establishment response (UE Context Setup Response) message to the concentration unit, where the message contains one or more of the following information:

■ Information of the newly added cell transmitted by the DU, which may include one or more of the following information:

■ Identification of the selected PCell cell;

■ An identity of the selected one or more SCell cells;

■ Identification of the selected PSCell cell;

■ Identification of the selected one or more SCG SCell cells.

■ Identification information of an unacceptable cell indicating that the cell is unsuitable for configuration to a user;

■ Context related to the user bearer, such as information of the user's bearer;

■ The distributing unit performs the reply reason information, which may be specific to each cell or specific to all the modifications, where possible reasons include one or more of cell overload, cell uplink or downlink overload, cell uplink control channel overload, load balancing, poor signal quality or strength of the user in the cell, poor quality or strength of the user uplink or downlink signal in the cell, and the like.

The distribution unit establishes a context of the user according to the determined cell. In addition, if the distribution unit can accept the content about the cell configuration in the request message of step 1, the distribution unit may not include the information of the selected cell in the user context setup response (UE Context Setup Response) message replied in step 2.

The information content included in the two steps may be different according to the decision maker of the cell configuration of the user. The specific embodiments are as follows:

a. cell configuration for determining users by a centralized unit

The user context setup request (UE Context Setup Request) message of step 1 contains one or more of the following:

■ Information of the newly added cell transmitted by the CU, the information including one or more of the following information:

■ Identification information of the PCell cell;

■ Identification information of one or more SCell cells;

■ Identification information of the PScell cell;

■ Identification information of one or more SCG SCell cells;

■ And the measurement information of the cell.

■ A context related to the user bearer and/or identity, such as a message of the user bearer, identification information of the user (such as an ID used by the user on the interface between the centralized unit and the distributed unit, e.g. a CU UE F1AP ID, which may be newly assigned by the CU or already assigned to the user by the CU, or both);

■ The reason information of the user context is established, and the information can be specific to each cell or all the modifications, and possible reasons include one or more of cell overload, cell uplink or downlink overload, cell uplink control channel overload, load balancing, poor signal quality or strength of the user in the cell, poor quality or strength of the user uplink or downlink signal in the cell, and the like.

The user context setup response (UE Context Setup Response) message of step 2 may contain one or more of the following:

In addition, if the distribution unit can accept the content about the cell configuration in the request message of step 1, the distribution unit may not include the above-mentioned information about the cell (i.e., the identification information of the non-accepted cell) and/or other information (i.e., the context about the user bearer, the reason information for the above-mentioned reply by the distribution unit) in the user context setup response (UE Context Setup Response) message replied in step 2.

b. The distribution unit decides the cell configuration of the user and the concentration unit only provides the cell list

■ Identification of the cell;

■ Information of the newly added cell transmitted by the DU, the information including one or more of the following information:

■ Identification information of the PCell cell;

■ Identification information of one or more SCell cells;

■ Identification information of the PScell cell;

■ Identification information of one or more SCG SCell cells.

The cells included in the step 2 may be selected from the cell list given in the step 1, or may be cells not in the cell list given in the step 1.

c. The distribution unit decides the cell configuration of the user and the concentration unit provides a list of candidate cells

The user context setup request (UE Context Setup Request) message of step 1 contains one or more of the following information:

■ Information of the newly added candidate cell transmitted by the CU, the information including one or more of the following information:

■ Alternative cell list information comprising an identification of one or more cells;

■ Identification information of alternative one or more PCell cells;

■ Identification information of alternative one or more SCell cells;

■ Identification information of alternative one or more PSCell cells;

■ Identification information of alternative one or more SCG SCell cells;

■ The measurement information of the cell, such as signal quality, signal strength, etc.

■ Identification information of the PCell cell;

■ Identification information of one or more SCell cells;

■ Identification information of the PScell cell;

■ Identification information of one or more SCG SCell cells.

The cells included in the step 2 may be selected from the candidate cells given in the step 1, or may be cells not given in the step 1. In addition, if the distribution unit can accept the content about the cell configuration in the request message of step 1, the distribution unit may not include the above-mentioned information about the cell (i.e., the information about the newly added cell transmitted by the DU, the identification information of the non-accepted cell) and/or other information (i.e., the context about the user bearer, the reason information for the above-mentioned reply by the distribution unit) in the user context setup response (UE Context Setup Response) message replied in step 2.

B-2, user context modification flow, wherein the modification flow can be triggered by a centralized unit or a distributed unit.

a. The cell configuration modification procedure triggered by the centralized unit includes two steps, as shown in fig. 15:

step 1: the central unit sends a user context modification request (UE Context Modified Request) message to the distribution units, the message including one or more of the following information:

■ Cell identification;

■ The information of the newly added serving cell sent by the CU may be a newly added cell already determined by the concentration unit, or may be an alternative newly added cell, including one or more of the following information:

■ Cell list information including identities of one or more cells;

■ Identification information of one or more PCell cells;

■ Identification information of one or more SCell cells;

■ Identification information of one or more PSCell cells;

■ Identification information of one or more SCG SCell cells;

■ The information of the serving cell to be modified comprises one or more of the following information:

■ An identification of the PCell cell to be modified;

■ Identification of SCell cell to be modified;

■ An identification of a PSCell to be modified;

■ Identification of the SCG SCell cell to be modified;

■ Cell identity with changed cell type and indicating the type of the cell before and after modification: such as an identification of a cell from PCell to SCell, an identification of a cell from SCell to PCell, an identification of a cell from PSCell to SCG SCell, an identification of a cell from SCG SCell to PSCell;

■ Information of a serving cell to be released, such as a cell identifier of the cell to be released;

■ The reason information of the user context is modified, and the information can be used for each cell, or all the modifications, and possible reasons include one or more of cell overload, cell uplink or downlink overload, cell uplink control channel overload, load balancing user signal quality or strength difference in the cell, user uplink or downlink signal quality or strength difference in the cell, and the like.

Step 2: the distribution unit sends a user context modification response (UE Context Modified Response) message to the concentration unit, which may include one or more of the following information:

■ The cell identifier of the newly added cell accepted, or the cell identifier of the newly added cell selected by the distribution unit, optionally, indicates the type of the newly added cell, such as PCell, SCell, PSCell, SCG SCell;

■ Cell identity of the newly added cell that is not accepted.

■ Information of a cell to be modified, the information comprising one or more of the following information:

■ The cell identification of the cell to be modified is accepted;

■ And the cell identification of the cell to be modified which is not accepted.

■ Information of a cell to be released, the information comprising one or more of the following information:

■ The cell identification of the cell to be released is accepted;

■ And the cell identification of the unacceptable cell to be released.

■ The reason information for the response may be for each cell, or may be for all modifications, and possible reasons include one or more of cell overload, cell uplink or downlink overload, cell uplink control channel overload, load balancing user signal quality or strength difference in the cell, user uplink or downlink signal quality or strength difference in the cell, etc.

The newly added cell accepted in the above step 2 may be obtained from the cell list information or the newly added serving cell included in the step 1, or may be another cell. The distribution unit modifies the context of the user according to the information in step 2. In addition, if the distribution unit can accept the content about the cell configuration in the request message of step 1, the distribution unit may not include the above-mentioned information about the cell (i.e., the information about the newly added cell transmitted by the DU, the information about the cell to be modified, the information about the cell to be released) and/or other information (i.e., the context related to the user bearer, the reason information for the above-mentioned response by the distribution unit) in the user context modification response (UE Context Modification Response) message replied in step 2.

b. The cell configuration modification procedure triggered by the distribution unit includes two steps, as shown in fig. 16:

step 1: the distribution unit sends a user context modification need (UE Context Modified Required) message to the concentration unit, the message including one or more of the following information:

■ An identification of the PCell cell to be modified;

■ Identification of SCell cell to be modified;

■ An identification of a PSCell to be modified;

■ Identification of the SCG SCell cell to be modified;

■ Context related to the user bearer, such as messages of the user's bearer;

■ The reason information of the user context is modified, and the information can be used for each cell or all modification, and possible reasons include one or more of cell overload, cell uplink or downlink overload, cell uplink control channel overload, load balancing, poor signal quality or strength of a user in a cell, poor quality or strength of an uplink or downlink signal of the user in the cell, and the like.

Step 2: the central unit sends a user context modification confirmation (UE Context Modified Confirm) message to the distribution units, which may contain one or more of the following information:

■ The cell identification of the cell to be modified is accepted;

■ The cell identification of the cell to be released is accepted;

■ And the cell identification of the unacceptable cell to be released.

■ The centralized unit performs the reason information of the response, which may be specific to each cell, or may be specific to all the modifications, and possible reasons include one or more of cell overload, cell uplink or downlink overload, cell uplink control channel overload, load balancing, poor signal quality or strength of the user in the cell, poor quality or strength of the user uplink or downlink signal in the cell, and the like.

If the concentration unit can accept the content about the cell configuration in the request message of step 1, the concentration unit may not include the above-mentioned information about the cell (i.e. the information about the cell to be modified, the information about the cell to be released) and/or other information (i.e. the context about the user bearer, the reason information for the above-mentioned response by the concentration unit) in the user context modification confirmation (UE Context Modification Confirm) message replied in step 2.

c. The cell configuration modification procedure triggered by the distribution unit includes three or four steps, as shown in fig. 17:

■ An identification of the PCell cell to be modified;

■ Identification of SCell cell to be modified;

■ An identification of a PSCell to be modified;

■ Identification of the SCG SCell cell to be modified;

■ Context related to user bearer, information of the user's bearer;

Step 2: the central unit sends a user context modification request (UE Context Modified Request) message to the distribution units, the message including one or more of the following information:

■ Cell identification;

■ Cell list information including identities of one or more cells;

■ Identification information of one or more PCell cells;

■ Identification information of one or more SCell cells;

■ Identification information of one or more PSCell cells;

■ Identification information of one or more SCG SCell cells;

■ An identification of the PCell cell to be modified;

■ Identification of SCell cell to be modified;

■ An identification of a PSCell to be modified;

■ Identification of the SCG SCell cell to be modified;

The cell indicated by the cell-related information in the above step 2 may or may not include the cell indicated by the cell-related information included in the step 1.

Step 3: the distribution unit sends a user context modification response (UE Context Modified Response) message to the concentration unit, which may include one or more of the following information:

■ Cell identity of the newly added cell that is not accepted.

■ The cell identification of the cell to be modified is accepted;

■ The cell identification of the cell to be released is accepted;

■ And the cell identification of the unacceptable cell to be released.

The newly added cell accepted in the above step 3 may be obtained from the cell list information or the newly added serving cell included in the step 2, or may be another cell. The distribution unit modifies the context of the user according to the information in step 3. In addition, if the distribution unit can accept the content about the cell configuration in the request message of step 2, the distribution unit may not include the above-mentioned information about the cell (i.e., the information about the newly added cell transmitted by the DU, the information about the cell to be modified, the information about the cell to be released) and/or other information (i.e., the context related to the user bearer, the reason information for the above-mentioned response by the distribution unit) in the user context modification response (UE Context Modification Response) message replied in step 3.

Step 4: the centralized unit sends a user context modification confirmation (UE Context Modified Confirm) message to the distributed units, which is an optional step, possibly including one or more of the following:

■ Information of the newly added cell, the information comprising one or more of the following information:

■ A cell identifier of the accepted newly added cell;

■ Cell identification of an unacceptable newly added cell

■ The cell identification of the cell to be modified is accepted;

■ The cell identification of the cell to be released is accepted;

■ And the cell identification of the unacceptable cell to be released.

The newly added cell and/or the cell to be modified and/or the cell to be released in the step 4 may be obtained from the newly added cell and/or the cell to be modified and/or the cell to be released in the step 3, or may be other cells. The distribution unit modifies the context of the user according to the information in step 4. In addition, if the concentration unit can accept the content about the cell configuration in the response message of step 3, the concentration unit may not include the above-mentioned information about the cell (i.e., the information about the newly added cell, the information about the cell to be modified, the information about the cell to be released) and/or other information (i.e., the context about the user bearer, the reason information for the above-mentioned response by the concentration unit) in the user context modification confirmation (UE Context Modification Confirm) message replied in step 4.

The third embodiment of the present invention further provides an apparatus for switching a serving cell, as shown in fig. 18, including a first transmitting module S10 and a first receiving module S11.

A first sending module S10, configured to send an auxiliary node modification requirement message to the master node, so that the master node switches a serving cell and releases a bearer to be released according to the auxiliary node modification requirement message;

The first receiving module S11 is configured to receive, by the secondary node, a secondary node modification confirmation message returned by the primary node for the secondary node modification requirement message.

According to the device for switching the service cell, disclosed by the embodiment of the invention, the auxiliary node sends the auxiliary node modification demand message to the main node, so that the main node switches the service cell according to the auxiliary node modification demand message and releases the bearer to be released, a precondition guarantee is provided for releasing the user bearer on the auxiliary node when the service cell is switched according to the auxiliary node modification demand message, the auxiliary node receives the auxiliary node modification confirmation message returned by the main node aiming at the auxiliary node modification demand message, when the bearer to be released exists when the service cell is switched, the service cell is switched according to the auxiliary node modification demand message and the bearer to be released on the auxiliary node is released, the signaling transmission efficiency is greatly improved, and the signaling resources are saved.

The fourth embodiment of the present invention further provides an apparatus for switching a serving cell, as shown in fig. 19, including a second receiving module S13 and a second transmitting module S12.

A second receiving module S13, configured to receive, by the master node, an auxiliary node modification requirement message sent by the auxiliary node, switch a serving cell according to the auxiliary node modification requirement message, and release a bearer to be released;

The second sending module S12 is configured to return, to the secondary node, a secondary node modification confirmation message for the secondary node modification requirement message.

According to the embodiment, when the service cell is switched and the bearer to be released exists, the main node can switch the service cell according to the received auxiliary node modification demand message and release the bearer to be released on the auxiliary node, so that the signaling transmission efficiency is greatly improved, and signaling resources are saved.

Those skilled in the art will appreciate that the present invention includes apparatuses related to performing one or more of the operations described herein. These devices may be specially designed and constructed for the required purposes, or may comprise known devices in general purpose computers. These devices have computer programs stored therein that are selectively activated or reconfigured. Such a computer program may be stored in a device (e.g., a computer) readable medium or any type of medium suitable for storing electronic instructions and respectively coupled to a bus, including, but not limited to, any type of disk (including floppy disks, hard disks, optical disks, CD-ROMs, and magneto-optical disks), ROMs (Read-Only memories), RAMs (Random Access Memory, random access memories), EPROMs (Erasable Programmable Read-Only memories), EEPROMs (Electrically Erasable Programmable Read-Only memories), flash memories, magnetic cards, or optical cards. That is, a readable medium includes any medium that stores or transmits information in a form readable by a device (e.g., a computer).

It will be understood by those within the art that each block of the block diagrams and/or flowchart illustrations, and combinations of blocks in the block diagrams and/or flowchart illustrations, can be implemented by computer program instructions. Those skilled in the art will appreciate that the computer program instructions can be implemented in a processor of a general purpose computer, special purpose computer, or other programmable data processing method, such that the blocks of the block diagrams and/or flowchart illustration are implemented by the processor of the computer or other programmable data processing method.

Those of skill in the art will appreciate that the various operations, methods, steps in the flow, acts, schemes, and alternatives discussed in the present invention may be alternated, altered, combined, or eliminated. Further, other steps, means, or steps in a process having various operations, methods, or procedures discussed herein may be alternated, altered, rearranged, disassembled, combined, or eliminated. Further, steps, measures, schemes in the prior art with various operations, methods, flows disclosed in the present invention may also be alternated, altered, rearranged, decomposed, combined, or deleted.

The foregoing is only a partial embodiment of the present invention, and it should be noted that it will be apparent to those skilled in the art that modifications and adaptations can be made without departing from the principles of the present invention, and such modifications and adaptations are intended to be comprehended within the scope of the present invention.

Claims

1. A method performed by a network entity of a centralized unit CU corresponding to a network node in a wireless communication system, comprising:

transmitting a request message for requesting context establishment of a User Equipment (UE) to a network entity corresponding to a Distribution Unit (DU), wherein the request message comprises first identification information of at least one secondary cell (SCell) to be established;

and receiving a response message sent by the network entity corresponding to the DU, wherein the response message comprises second identification information of at least one SCell with failed establishment.

2. The method of claim 1, wherein the response message further comprises a cause associated with at least one SCell that failed to establish, wherein the cause indicates an SCell overload that failed to establish a DU.

3. A network entity corresponding to a central unit CU of a network node, comprising: a transceiver configured to transmit signals and receive signals; and at least one processor configured to perform the method of any of claims 1-2.

4. A method performed by a network entity of a distribution unit DU corresponding to a network node in a wireless communication system, comprising:

receiving a request message sent by a network entity corresponding to a centralized unit CU and used for requesting the context establishment of user equipment UE, wherein the request message comprises first identification information of at least one secondary cell SCell to be established;

and sending a response message to the network entity corresponding to the CU, wherein the response message comprises second identification information of at least one SCell with failed establishment.

5. The method of claim 4, wherein the response message further comprises a cause associated with at least one SCell that failed to establish, wherein the cause indicates an SCell overload that failed to establish a DU.

6. A network entity corresponding to a distribution unit DU of a network node, comprising: a transceiver configured to transmit signals and receive signals; and at least one processor configured to perform the method of any of claims 4-5.