CN114500271B

CN114500271B - Inter-base station communication method, base station and communication system

Info

Publication number: CN114500271B
Application number: CN202210132702.XA
Authority: CN
Inventors: 许森; 李俊杰; 张乐; 张光辉; 孙震强
Original assignee: China Telecom Corp Ltd
Current assignee: China Telecom Corp Ltd
Priority date: 2018-09-30
Filing date: 2018-09-30
Publication date: 2024-04-30
Anticipated expiration: 2038-09-30
Also published as: CN110972331B; CN110972331A; CN114449682A; CN114500271A

Abstract

The present disclosure proposes an inter-base station communication method, a base station, and a communication system. The communication method between base stations comprises the following steps: when a cell supporting NSA single mode covered by a first base station is switched to support NSA and SA double modes: the method comprises the steps that a first base station sends target mode configuration information of the first base station to a second base station through an inter-base station interface so that the second base station can store the target mode configuration information of the first base station into a neighbor list, wherein the target mode configuration information of the first base station comprises mode information of a cell covered by the first base station for supporting NSA and SA double modes; the first base station receives configuration information from the second base station through the inter-base station interface, wherein the configuration information of the second base station comprises cross-core network switching capability information of the second base station; the first base station stores configuration information of the second base station in a neighbor list. By the method, the updated neighbor list can be conveniently adopted to determine the proper mobility strategy for the terminal, and user experience is ensured.

Description

Inter-base station communication method, base station and communication system

The application is a divisional application of the original application with the application number 201811153260.7 (the application date is 2018, 9 and 30 days, and the application name is a communication method between base stations, a base station and a communication system).

Technical Field

The disclosure relates to the technical field of communication, in particular to a communication method between base stations, a base station and a communication system.

Background

The 5G is used as the main technology of the next generation wireless network and has the characteristics of supporting ultra-wideband, large connection and the like. The 3GPP completes standard freezing work for EUTRAN-NR DC (Dual Connectivity, double connection) (EN-DC for short) in NSA (Non-Stand Alone networking) in 2018, and defines and describes specifications for main key functions in a Stand Alone (Stand Alone networking) architecture.

By the end of 6 months in 2018, the networking architecture and interfaces of several mainstream in the current specifications are as follows:

In the EN-DC networking scenario, as shown in fig. 1, an NR (New Radio, new air interface) base station is called EN-gNB, and is connected with an eNB (E-UTRAN NodeB, E-UTRAN base station node) by using an X2 interface, in this scenario, only the eNB maintains an S1-C interface to an EPC (Evolved Packet Core, evolved packet core network), the EN-gNB needs to support the S1-U interface of the EPC when supporting SCG (Secondary Cell Group ) bearers or SCG Split bearers, and relevant protocol details are defined in TS 37.340.

In comparison with the previous several generations of radio technologies, two types of radio access base stations are supported in the 5G, namely, an NR gNB based on a new air interface and a ng-eNB (Next Generation eNB ) based on LTE evolution, and both types of base stations are connected to the core network 5GC of the 5G, and the radio network structure is shown in fig. 2. The base stations are connected through an Xn interface, the base stations are connected with a 5G core network through an NG interface, and relevant architecture details are defined in TS 38.300.

When the gNB and LTE enbs are connected to the respective core networks, respectively, i.e. the gNB is connected to 5GC and the enbs are connected to EPC, the scenario is as shown in fig. 3, according to the conclusion of 3GPP before 2018, 7 months, i.e. the establishment of an inter-base station interface is not supported between the gNB and the enbs.

In the EN-DC scenario, the eNB and the gNB establish an interface through the procedure of EN-DC X2 Setup, the signaling flow chart is shown in fig. 4, and the specific signaling content is shown in table 1.

Table 1 eNB and gNB establish signaling over EN-DC X2 Setup interface

From the perspective of the eNB, the target base station is an EN-gNB base station supporting EN-DC mode, and no information indicates that the eNB can additionally support SA mode, and EN-DC related signaling, such as EN-DC Configuration Updated and EN-DC Cell Activation, do not involve a change in NSA/SA mode of one or more cells in the base station.

In the network deployment process, one base station can basically have three modes, NSA only, SA only, nsa+sa. In order to explore the mode of the target NR base station in the SON (Self-Organized Networks, self-organizing network) ANR (Automatic Neighbor Relation ), three modes are proposed in the related art for the terminal to report the cell in the measurement report of LTE. ANR is typically used in scenarios where inter-base station or inter-cell neighbor relationships have not been established and there is no inter-base station interface.

In the network deployment process, some operators consider that users' perception is improved by deploying EN-DC architecture when the 5G core network is not deployed in the early stage, namely, the 5GC is not deployed and the gNB is not considered to be connected to the 5 GC. Subsequent direct upgrade of the gNB supporting SA function and connection to 5GC on the SA deployed gNB, the base station supporting NR air interface is formed to support NSA and SA dual mode, and the protocol stack is shown in FIG. 5.

Disclosure of Invention

An object of the present disclosure is to improve the self-adaptive capability of base station configuration to modes, and improve backward compatibility, thereby ensuring that an appropriate mobility policy is determined for a terminal, and ensuring user experience.

According to one aspect of the present disclosure, there is provided a method of inter-base station communication, including: when the first base station and the second base station establish the connection between the base stations: the method comprises the steps that a first base station sends configuration information of the first base station to a second base station through an inter-base station interface so that the second base station can store the configuration information into a neighbor list, wherein if a cell covered by the first base station comprises one or more cells supporting NSA and SA dual modes, the configuration information of the first base station comprises mode information supported by a corresponding cell; the first base station receives configuration information from the second base station through the inter-base station interface, wherein the configuration information of the second base station comprises cross-core network switching capability information of the second base station; the first base station stores configuration information of the second base station in a neighbor list.

In some embodiments, the configuration information of the first base station further includes cell identification, PCI (PHYSICAL CELL IDENTIFIER, physical cell identification) information, TAC (TRACKING AREA Code) information, and frequency point and frame structure information.

In some embodiments, the mode information supported by the cell is carried by an identifier with a predetermined length, and when the identifier is a first predetermined value, the cell supports NSA and SA dual modes; when the identifier is a second preset value or no identifier exists and the length of the TAC information is 3 bits, the cell supports an SA single mode; when the flag is a second predetermined value or no flag exists and the length of the TAC information includes 3 bits and 2 bits, the cell supports NSA single mode.

In some embodiments, in the case where the establishment of the connection between the first base station and the second base station is initiated by the first base station, the first base station actively transmits configuration information of the first base station to the second base station so that the second base station feeds back configuration information of the second base station.

In some embodiments, in the case where the connection between the first base station and the second base station is initiated by the second base station, the first base station sends the configuration information of the first base station to the second base station through an inter-base station interface message after receiving the configuration information of the second base station.

In some embodiments, the inter-base station communication method further comprises: when a cell supporting NSA single mode covered by a first base station is switched to support NSA and SA double modes: the first base station sends the target mode configuration information of the first base station to the second base station through the interface between the base stations, wherein the target mode configuration information of the first base station comprises configuration information after each cell covered by the first base station is switched into NSA and SA double modes.

In some embodiments, the inter-base station communication method further comprises: after the first base station sends the configuration information of the target mode of the first base station to the second base station, the first base station receives the configuration information from the second base station through the inter-base station interface and updates the neighbor list.

In some embodiments, the inter-base station communication method further comprises: when the first base station determines that the second base station has the cross-core network switching capability according to the neighbor cell list, the first base station determines that the terminal which is positioned in a cell supporting an SA mode and supports the SA mode can perform the cross-core network switching.

In some embodiments, the inter-base station communication method further comprises: in the case that the mode of all cells in the first base station is switched to the supporting SA single mode: the first base station sends an inter-base station interface release request to the second base station through an inter-base station interface message, wherein the inter-base station interface release request comprises a base station identifier of the first base station and interface deletion reason information; and deleting the application layer configuration of the interface between the base stations and SCTP (Stream Control Transmission Protocol ) connection according to the deletion confirmation information fed back by the second base station.

In some embodiments, the first base station is a gNB or en-gNB and the second base station is an evolved base station eNB or a ng-eNB.

By the method, mode information supported by the base stations and cross-core network switching capability information of the base stations are interacted when connection is established between the base stations, and the mode information and the cross-core network switching capability information of the base stations are mutually stored into the neighbor cell list, so that a proper mobility strategy is conveniently determined for the terminal, and user experience is ensured.

According to another aspect of the present disclosure, there is provided a method of inter-base station communication, including: when a cell supporting NSA single mode covered by a first base station is switched to support NSA and SA double modes: the method comprises the steps that a first base station sends target mode configuration information of the first base station to a second base station through an inter-base station interface so that the second base station can store the target mode configuration information of the first base station into a neighbor list, wherein the target mode configuration information of the first base station comprises mode information of a cell covered by the first base station for supporting NSA and SA double modes; the first base station receives configuration information from the second base station through the inter-base station interface, wherein the configuration information of the second base station comprises cross-core network switching capability information of the second base station; the first base station stores configuration information of the second base station in a neighbor list.

In some embodiments, the target mode configuration information of the first base station further includes a cell identifier, PCI information, TAC information, and frequency point and frame structure information after the cell is switched to support NSA and SA dual modes.

In some embodiments, the inter-base station communication method further comprises: when the first base station and the second base station establish the connection between the base stations: the method comprises the steps that a first base station sends configuration information of the first base station to a second base station through an inter-base station interface, wherein if a cell covered by the first base station comprises one or more cells supporting NSA and SA dual modes, the configuration information of the first base station comprises mode information supported by a corresponding cell; the first base station receives configuration information from the second base station through the inter-base station interface, wherein the configuration information of the first base station comprises cross-core network switching capability information of the second base station; the first base station stores configuration information of the second base station in a neighbor list.

In some embodiments, the inter-base station communication method further comprises: when the first base station determines that the second base station has the cross-core network switching capability information according to the neighbor cell list, the first base station determines that the terminal which is positioned in the cell supporting the SA mode and supports the SA mode can perform the cross-core network switching.

In some embodiments, the inter-base station communication method further comprises: in the case that the mode of all cells in the first base station is switched to the supporting SA single mode: transmitting an inter-base station interface release request to a second base station through an inter-base station interface message, wherein the inter-base station interface release request comprises a base station identifier of a first base station and interface deletion reason information; and deleting the application layer configuration and SCTP connection of the interfaces between the base stations according to the deletion confirmation information fed back by the second base station.

In some embodiments, the first base station is a gNB or en-gNB and the second base station is an eNB or ng-eNB.

By the method, when the cell which is covered by the first base station and supports NSA single mode is switched to support NSA and SA double mode, configuration information can be timely sent to the second base station to update the neighbor cell list of the second base station, so that the updated neighbor cell list is convenient to determine proper mobility strategy for the terminal, and user experience is guaranteed.

According to still another aspect of the present disclosure, there is provided a method of inter-base station communication, including: when all cells of a first base station supporting NSA single mode or supporting NSA and SA dual mode are switched to support SA single mode: the first base station sends an inter-base station interface release request to the second base station through the inter-base station interface so that the second base station deletes the application layer configuration and SCTP connection of the inter-base station interface stored by the second base station, wherein the inter-base station interface release request comprises the base station identifier of the first base station and the interface deletion reason information; and deleting the application layer configuration and SCTP connection of the inter-base station interface stored in the first base station according to the deletion confirmation information fed back by the second base station.

In some embodiments, the inter-base station communication method further comprises: when the first base station and the second base station establish the connection between the base stations: the method comprises the steps that a first base station sends configuration information of the first base station to a second base station through an inter-base station interface so that the second base station can store the configuration information into a neighbor list, wherein if a cell covered by the first base station comprises one or more cells supporting NSA and SA dual modes, the configuration information of the first base station comprises mode information supported by a corresponding cell; the first base station receives configuration information from the second base station through the inter-base station interface, wherein the configuration information of the second base station comprises cross-core network switching capability information of the second base station; the first base station stores configuration information of the second base station in a neighbor list.

By the method, when all cells covered by the first base station are switched to the mode supporting SA single mode, the interfaces between the first base station and the second base station can be released, and the release reasons can be recorded, so that the configuration of the base station meets the requirement of mode updating, and the self-adaption capability of the base station configuration to the mode is improved.

According to still another aspect of the present disclosure, there is provided an inter-base station communication method including: when the first base station and the second base station establish the connection between the base stations: the second base station sends configuration information of the second base station to the first base station through an inter-base station interface so that the first base station stores the configuration information of the second base station into a neighbor list, wherein the configuration information of the second base station comprises cross-core network switching capability information of the second base station; the second base station receives configuration information from the first base station through the inter-base station interface, wherein if a cell covered by the first base station comprises one or more cells supporting NSA and SA dual modes, the configuration information of the first base station comprises mode information supported by a corresponding cell; the second base station stores the configuration information of the first base station into a neighbor list.

In some embodiments, the configuration information of the first base station further includes cell identification, PCI information, TAC information, and frequency point and frame structure information.

In some embodiments, the second base station determines a mode supported by the cell according to an identifier with a predetermined length in the configuration information of the first base station, wherein when the identifier is a first predetermined value, the cell is determined to support a NSA and SA dual mode; when the identifier is a second preset value or the configuration information of the first base station does not carry the identifier, and the length of the TAC information is 3 bits, determining that the cell supports an SA single mode; when the identifier is a second predetermined value or the configuration information of the first base station does not carry the identifier, and the length of the TAC information includes 3 bits and 2 bits, the cell supports NSA single mode.

In some embodiments, in the case where the establishment of the connection between the first base station and the second base station is initiated by the second base station, the second base station actively transmits configuration information of the second base station to the first base station so that the first base station feeds back the configuration information of the first base station.

In some embodiments, in the case where the connection between the first base station and the second base station is initiated by the first base station, the second base station, after receiving the configuration information of the first base station, sends the configuration information of the second base station to the first base station through an inter-base station interface message.

In some embodiments, the inter-base station communication method further comprises: when a cell supporting NSA single mode covered by a first base station is switched to support NSA and SA double modes: the second base station acquires target mode configuration information of the first base station through an interface between the base stations, and updates a neighbor cell list, wherein the target mode configuration information of the first base station comprises configuration information after each cell covered by the first base station is switched into NSA and SA modes; and sending the configuration information of the second base station to the first base station through the interface between the base stations.

In some embodiments, the inter-base station communication method further comprises: and when the second base station determines that the second base station has the capability of switching across the core network and determines that the terminal supporting the SA mode is positioned in the cell supporting the SA mode according to the neighbor cell list, the second base station allows the terminal to switch across the core network.

In some embodiments, the inter-base station communication method further comprises: and the second base station determines a cell supporting the SA single mode and/or supporting NSA and SA dual modes and a frequency point where the cell is located according to the neighbor cell list, and frequency point and/or cell reselection parameter information is added in a broadcast message of the second base station.

In some embodiments, the inter-base station communication method further comprises: in case that the first base station is switched to support the SA single mode: receiving an inter-base station interface release request from a first base station through an inter-base station interface, wherein the inter-base station interface release request comprises a base station identifier of the first base station and interface deletion reason information; and deleting the application layer configuration and SCTP connection of the interface between the base stations, and feeding back deletion confirmation information to the first base station.

According to another aspect of the present disclosure, there is provided a method for inter-base station communication, including: when a cell supporting NSA single mode covered by a first base station is switched to support NSA and SA double modes: the second base station receives the target mode configuration information from the first base station through the inter-base station interface and stores the target mode configuration information into a neighbor list, wherein the target mode configuration information of the first base station comprises configuration information after each cell covered by the first base station is switched to support NSA and SA modes; the second base station sends configuration information of the second base station to the first base station through the inter-base station interface so that the first base station stores the configuration information of the second base station in the neighbor cell list, and the configuration information of the second base station comprises cross-core network switching capability information of the second base station.

In some embodiments, the inter-base station communication method further comprises: when the first base station and the second base station establish the connection between the base stations: the second base station sends configuration information of the second base station to the first base station through an inter-base station interface, wherein the configuration information of the second base station comprises cross-core network switching capability information of the second base station; the second base station receives configuration information from the first base station through the inter-base station interface and stores the configuration information into a neighbor list, wherein if a cell covered by the first base station comprises one or more cells supporting NSA and SA dual modes, the configuration information of the first base station comprises mode information supported by the corresponding cell.

In some embodiments, the inter-base station communication method further comprises: and when the second base station determines that the second base station has the capability of switching across the core network and the terminal supporting the SA mode is positioned in the cell supporting the SA mode, the second base station allows the terminal to switch across the core network.

In some embodiments, the inter-base station communication method further comprises: in case that all cells in the first base station are switched to support SA single mode: receiving an inter-base station interface release request from a first base station through an inter-base station interface, wherein the inter-base station interface release request comprises a base station identifier of the first base station and interface deletion reason information; and deleting the application layer configuration and SCTP connection of the interfaces between the base stations, and feeding back deletion confirmation information to the first base station so that the first base station deletes the application layer configuration and SCTP connection of the interfaces between the base stations.

By the method, when the cell which is covered by the first base station and supports NSA single mode is switched to support NSA and SA double mode, the second base station can acquire updated configuration information from the first base station so as to update own neighbor cell list, and can provide own cross-core network switching capability information for the first base station, so that the base station can conveniently determine proper mobility strategy for the terminal by adopting the updated neighbor cell list, and user experience is ensured.

According to one aspect of the present disclosure, there is provided a method of inter-base station communication, including: when all cells of a first base station supporting NSA single mode or supporting NSA and SA dual mode are switched to support SA single mode: the second base station receives an inter-base station interface release request from the first base station through an inter-base station interface, wherein the inter-base station interface release request comprises a base station identifier of the first base station and interface deletion reason information; deleting the application layer configuration and SCTP connection of interfaces between the base stations; and feeding back deletion confirmation information to the first base station so that the first base station deletes the application layer configuration and SCTP connection of the interface between the base stations.

In some embodiments, the inter-base station interface is initiated by the first base station or the second base station; when the first base station and the second base station establish the connection between the base stations: the second base station sends configuration information of the second base station to the first base station through an inter-base station interface, wherein the configuration information of the second base station comprises cross-core network switching capability information of the second base station; the second base station receives configuration information from the first base station through the inter-base station interface and stores the configuration information into a neighbor list, wherein if a cell covered by the first base station comprises one or more cells supporting NSA and SA dual modes, the configuration information of the first base station comprises mode information supported by the corresponding cell.

According to another aspect of the present disclosure, there is provided a base station including: a memory; and a processor coupled to the memory, the processor configured to perform any of the inter-base station communication methods described above based on instructions stored in the memory.

The base station can realize the interaction of mode information and configuration information of each covered cell and cross-core network switching capability information of the base station, and can change the configuration according to the interacted information, thereby improving the self-adaption capability of the base station configuration to the mode, improving backward compatibility, ensuring that a proper mobility strategy is determined for a terminal and ensuring user experience.

According to another aspect of the present disclosure, a computer-readable storage medium is provided, on which computer program instructions are stored which, when executed by a processor, implement the steps of any of the inter-base station communication methods above.

By executing the instructions on the computer readable storage medium, the base station can realize the interaction of the mode information and the configuration information of each cell covered and the cross-core network switching capability information of the base station, and can change the configuration according to the interacted information, thereby improving the self-adaption capability of the base station configuration to the mode, improving backward compatibility, ensuring the determination of proper mobility strategy for the terminal and ensuring the user experience.

Further, according to an aspect of the present disclosure, there is provided a communication system including: a first base station configured to perform any of the methods performed by the first base station above; a second base station configured to perform any of the methods performed by the second base station above; and, a core network.

In the communication system, the base station can realize the interaction of the mode information and the configuration information of each covered cell and the cross-core network switching capability information of the base station, and can change the configuration according to the interacted information, thereby improving the self-adaption capability of the base station configuration to the mode, improving the backward compatibility, being beneficial to determining proper mobility strategies for the terminal and ensuring the user experience.

Drawings

The accompanying drawings, which are included to provide a further understanding of the disclosure, illustrate and explain the present disclosure, and together with the description serve to explain the present disclosure. In the drawings:

fig. 1 is a grid pattern in an EN-DC scene.

Fig. 2 is a diagram of a 5G wireless network architecture.

Fig. 3 is a schematic diagram of an eNB and gNB networking scenario.

Fig. 4 is a signaling flow diagram of the eNB and the gNB establishing an interface connection through EN-DC X2 Setup.

Fig. 5 is a protocol stack schematic diagram of NSA and SA co-sited scenario.

Fig. 6 is a flow chart of one embodiment of a method of inter-base station communication of the present disclosure.

Fig. 7 is a flow chart of another embodiment of an inter-base station communication method of the present disclosure.

Fig. 8 is a flow chart of yet another embodiment of an inter-base station communication method of the present disclosure.

Fig. 9 is a signaling flow diagram of one embodiment of an inter-base station communication method of the present disclosure.

Fig. 10 is a schematic diagram of one embodiment of a base station of the present disclosure.

Fig. 11 is a schematic diagram of another embodiment of a base station of the present disclosure.

Fig. 12 is a schematic diagram of one embodiment of a communication system of the present disclosure.

Detailed Description

The technical scheme of the present disclosure is described in further detail below through the accompanying drawings and examples.

The inventors found that the related art has the following problems:

1) When the mode of the gNB changes, the eNB cannot acquire in real time:

Based on the current X2 interface established through the EN-DC X2 Setup procedure, LTE considers the gNB as an EN-gNB base station, and if the gNB is changed to nsa+sa dual mode, the existing X2 signaling procedure does not support the change of the gNB mode, and the ANR procedure cannot be used to obtain the mode change. Reasons for the inability to obtain a mode change include: (1) The ANR is used in a scene without neighbor relation among cells and an X2 interface, but the scene has an X2 interface between two base stations; (2) The LTE eNB cannot know when the NR gNB has modified state, which would result in the consumption of extra air interface signaling if ANR measurements were continuously made with the terminal.

In the case that the target base station mode cannot be determined, the LTE base station cannot determine whether the terminal supporting the SA or nsa+sa dual mode can be handed over to the gNB through the cross-core network, so this may cause degradation of the terminal experience in some scenarios.

2) The eNB cannot know the mode differences of different cell configurations within the same gNB base station:

One base station can support a plurality of 5G frequency points, such as 3400-3500 MHz and 3500 MHz-3600 MHz, wherein part of the frequency points are suitable for NSA with LTE 1.8GHz, and part of the frequency points are not suitable for NSA with LTE 1.8GHz due to larger uplink double-transmission power backspacing. Thus, there are cases where different frequency points or cells in one base station can be configured as NSA, SA or nsa+sa dual mode.

The current X2 interface signaling does not support cell-level mode interaction, and if an interface is established according to an EN-DC X2 Setup process, LTE can consider that all cells of a target base station support NSA mode, so that all gNB cells in a neighbor cell list of LTE support NSA. If an SeNB (Secondary eNB, secondary E-UTRAN base station node) addition procedure is initiated, this will result in the SeNB refusing the addition.

3) The gNB cannot know whether the eNB supports handover across the core network:

In NSA phase, since all mobility anchors are located on LTE side, eNB may not have a function of supporting handover across core networks, which requires eNB to support additional signaling and formats. When the gNB is upgraded into NSA+SA dual mode, the handover across the core network becomes a necessary requirement, and if the eNB does not support the handover, the handover from the gNB to the eNB may fail.

4) After the gNB is upgraded to the SA single mode, the X2 interface cannot be released:

Since the current protocol does not support the gNB in SA mode to establish the X2 interface with the eNB, the NR base station needs to release the X2 interface established according to EN-DC mode when changing from EN-gNB to gNB, but the existing EN-DC X2 remote does not explicitly indicate why the eNB needs to release, and the eNB cannot change the cell mode in the neighbor relation based on the same.

A flowchart of one embodiment of an inter-base station communication method of the present disclosure is shown in fig. 6, where the left side of the dotted line is performed by a first base station and the right side of the dotted line is performed by a second base station. In one embodiment, the first base station may be a gNB or en-gNB and the second base station may be an eNB or a ng-eNB. When the first base station and the second base station establish the connection between the base stations:

In step 601, the first base station sends configuration information of the first base station to the second base station through an inter-base station interface, where if a cell covered by the first base station includes one or more cells supporting NSA and SA dual mode, the configuration information of the first base station includes mode information supported by a corresponding cell.

In one embodiment, the configuration information of the first base station may include, but is not limited to:

identification information of the cell: NR CGI (Common GATEWAY INTERFACE ) information, 36 bits in length

PCI information of cell

TAC information of cell: 2byte and/or 3byte length

Frequency point and frame structure information of cell

Mode information of the cell.

In one embodiment, the mode information of the cell may be carried by an identifier with a length of 1 bit, where the identifier is a first predetermined value, such as 1, and the cell is dual-mode of NSA and SA, where the identifier is a second predetermined value, such as 2, or where the identifier field is empty, the determination needs to be made according to the format combination of TACs, and if only 3byte TACs are included, only SA mode is considered to be supported, and if 2byte and 3byte TACs are included, only NSA is considered to be supported.

In step 602, the second base station receives configuration information sent by the first base station through an inter-base station interface.

In step 603, the second base station stores the configuration information of the first base station in the neighbor list.

In one embodiment, the neighbor list stored by the second base station according to the configuration information of the first base station may include, but is not limited to, the following:

Identity of the cell: NR CGI information, which may be 36 bits in length

PCI information of cell

TAC information of cell: 2byte and/or 3byte length

Frequency point of cell

Frame structure of cell

Cell mode information: support only NSA single mode, only SA single mode, or both NSA and SA dual modes

In step 604, the second base station sends configuration information of the second base station to the first base station through the inter-base station interface, where the configuration information of the second base station includes handover capability information of the second base station across the core network.

In one embodiment, the second base station and cell configuration information includes, but is not limited to, the following:

Base station identity of the second base station

Configuration information for each cell, including:

frequency information of cell

TAC of cell

PCI information of cell

Bandwidth and subframe configuration information of a cell

Whether or not handover across EPC and 5GC core networks is supported: 1 bit, 1 for support, 0 or no support for the information carrying no representation.

In step 605, the first base station receives configuration information from the second base station through the inter-base station interface.

In step 606, the first base station stores configuration information of the second base station in the neighbor list. In one embodiment, after receiving the configuration information sent by the second base station, the first base station stores the base station configuration information, the cell configuration information and whether handover information across the core network is supported of the second base station according to the received message content.

In one embodiment, step 601 and step 604 have no context, and steps 601 to 603 may be performed first, then steps 604 to 606 may be performed, or steps 604 to 606 may be performed first, and then steps 601 to 603 may be performed. In one embodiment, if the connection between the first base station and the second base station is established by the first base station, the first base station actively transmits configuration information of the first base station to the second base station, and the second base station feeds back the configuration information of the second base station after receiving the configuration information of the first base station; if the connection between the first base station and the second base station is initiated by the second base station, the first base station sends the configuration information of the first base station to the second base station through the inter-base station interface message after receiving the configuration information of the second base station.

By the method, the core network or the control personnel can initiate the establishment of the inter-base station connection through any one side of the first base station or the second base station, so that the control flexibility is improved.

In one embodiment, the first base station may determine whether the terminal supporting the SA mode may adopt a mode of switching between EPC and 5GC core networks according to the neighbor list information and whether the second base station supports the capability of switching between EPC and 5GC core networks. In one embodiment, the second base station adds the frequency points and/or the reselection parameter information of the cells in the broadcast message of the second base station aiming at the frequency points where the SA single mode and/or NSA and SA dual mode cells are supported in the neighbor cell list. And the second base station determines that the terminal adopts the activated first base station as the SeNB according to neighbor list information, the capability of the terminal and the capability of whether the second base station supports handover across EPC and 5GC core networks or not, and adopts a mobility scheme such as handover across EPC and 5GC core networks or maintenance on LTE carriers, so that a proper mobility strategy is determined for the terminal, and user experience is ensured.

A flowchart of another embodiment of the inter-base station communication method of the present disclosure is shown in fig. 7, wherein the left side of the dotted line is performed by a first base station and the right side of the dotted line is performed by a second base station. In one embodiment, the first base station is a gNB or en-gNB and the second base station is an eNB or ng-eNB. When a cell supporting NSA single mode covered by a first base station is switched to support NSA and SA double modes:

In step 701, the first base station sends, to the second base station through the inter-base station interface, target mode configuration information of the first base station, where the target mode configuration information of the first base station includes configuration information after each cell covered by the first base station is switched to NSA and SA dual modes.

In step 702, a second base station receives target mode configuration information from a first base station through an inter-base station interface.

In step 703, the second base station stores the target mode configuration information of the first base station in the neighbor list.

In step 704, the second base station sends configuration information of the second base station to the first base station through the inter-base station interface, where the configuration information of the second base station includes handover capability information of the second base station across the core network.

In step 705, the first base station receives configuration information from the second base station through the inter-base station interface.

In step 706, the first base station updates the neighbor list with the received configuration information of the second base station.

In an embodiment, the second base station may further increase reselection parameter information of the frequency points and/or cells in its broadcast message for the frequency points where the SA single mode and/or NSA and SA dual mode cells are supported in the neighbor cell list, and delete the reselection parameter configuration of the frequency points and/or cells in its broadcast message for the frequency points and/or cells that are no longer supporting SA.

The second base station checks whether the second base station supports the handover function of the core network crossing EPC and 5GC, if not, the configuration information of the cell and the configuration information of the base station are sent to the first base station through the inter-base station interface message, otherwise, the enhanced configuration information is indicated to the first base station through the inter-base station interface message.

And the first base station determines whether the terminal supporting the SA mode can adopt a mode of switching between the EPC and the 5GC core network according to the neighbor list information and whether the second base station supports the capability of switching between the EPC and the 5GC core network.

In one embodiment, in a terminal communication process, when a first base station determines that a second base station has handover capability information across a core network according to a neighbor cell list, it is determined that a terminal which is located in a cell supporting an SA mode and supports the SA mode can perform handover across the core network. In one embodiment, the second base station allows the terminal to switch across the core network when determining that the second base station has the capability of switching across the core network and the terminal supporting the SA mode is located in the cell supporting the SA mode. For example, when the terminal only supports the SA mode, if the terminal needs to switch to the 5G network due to triggering of the AR/VR service or the like, the terminal can be switched to the gNB by the mode of switching across the core network according to the neighbor list information and the capability of supporting switching across the core network.

By the method, the proper mobility strategy can be ensured to be determined for the terminal, and the user experience is ensured.

A flowchart of yet another embodiment of the inter-base station communication method of the present disclosure is shown in fig. 8, wherein the left side of the dotted line is performed by a first base station and the right side of the dotted line is performed by a second base station. In one embodiment, the first base station is a gNB or en-gNB and the second base station is an eNB or ng-eNB. When all cells within the coverage area of the first base station are switched to support the SA single mode only:

in step 801, a first base station sends an inter-base station interface release request to a second base station through an inter-base station interface, where the inter-base station interface release request includes a base station identifier of the first base station and interface deletion reason information.

In one embodiment, the first base station may notify the second base station that the inter-base station interface X2 connection needs to be released using an inter-base station communication message, such as an EN-DC X2 Setup Request procedure, which includes, but is not limited to, one or a combination of the following information:

base station identity of the first base station: length of 22-32 bits

Delete reason: EN-DC state does not support

In step 802, the second base station receives an inter-base station interface release request from the first base station through the inter-base station interface.

In step 803, the second base station deletes the SCTP connection and the application layer configuration of the inter-base station interface. In one embodiment, the second base station may determine all cells of the base station in the neighbor cell list according to the base station identifier of the first base station carried in the message, determine that the cells become a state supporting only SA according to the deletion reason, and change the mode of the cells into a state supporting only SA. And adjusting the reselection parameter configuration of the corresponding frequency point and/or the cell in the broadcast message according to the frequency point information of the cells. In one embodiment, after receiving the EN-DC X2 Setup Request message, the second base station may further determine whether the terminal supporting the SA function switches to the gNB through the cross-core network according to whether the terminal supports the switching function of the cross-EPC and the 5 GC.

In step 804, the second base station feeds back deletion confirmation information to the first base station. In one embodiment, the second base station may send an EN-DC X2 Setup Response message to the gNB, including but not limited to the following:

Second base station identifier identification

In step 805, the first base station acquires deletion confirmation information fed back by the second base station.

In step 806, the application layer configuration and SCTP connection of the inter-base station interface are deleted according to the deletion confirmation information fed back by the second base station. In one embodiment, after receiving the acknowledgement message, the first base station adjusts its neighbor cell information, determines that all cells of the first base station and the second base station have no inter-base station interface connection, and deletes all application layer configurations and SCTP connections of inter-base station interfaces in the inter-base station interface connection.

A signaling flow diagram of one embodiment of an inter-base station communication method of the present disclosure is shown in fig. 9.

It is assumed that there are two base station nodes in the scenario, eNB and gNB, respectively, where all cells of the gNB support NSA and SA dual mode, and there is no X2 interface between the two base station nodes. The configuration information of the other party is not contained in the neighbor relation tables of the eNB and the gNB. The gNB includes four cells, namely cell 1/3 and cell 2/4, wherein cells 1 and 3 employ frequency F1 and cells 2 and 4 employ frequency F2.

If OMC (Operation AND MAINTENANCE CENTER, operation maintenance center) of the gNB triggers the X2 interface setup procedure with the gNB, then:

in 901, the gNB sends its own base station configuration and enhanced configuration information for each cell to the eNB through EN-DC X2 Setup Response message.

The configuration information of cells 1 and 3 includes:

Identification information of the cell: NR CGI information, 36 bits in length

PCI information of cell

TAC information of cell: 3byte length

Frequency point and frame structure information of cell

Cell mode information: 1

The configuration information of cells 2 and 4 includes:

Identification information of the cell: NR CGI information, 36 bits in length

PCI information of cell

TAC information of cell: 3byte length

Frequency point and frame structure information of cell

Cell mode information: 0

After receiving the EN-DC X2 Setup Response message sent by the gNB, the eNB stores configuration information of the gNB cell in a neighbor list, where the neighbor list includes:

identity of the cell: NR CGI information

PCI information of cell

TAC information of cell: 3byte length

Frequency point of cell

Frame structure of cell

Mode information of cell

In 902, the eNB sends configuration information of the cell and base station configuration information to the gNB through an EN-DC X2 Setup Request message, where the message includes:

Base station identification for an eNB

Configuration information for each cell, including:

frequency information of cell

TAC of cell

PCI information of cell

Bandwidth and subframe configuration information of a cell

Whether or not handover across EPC and 5GC core networks is supported: 1

In one embodiment, the eNB may increase reselection parameter information of F1 and F2 in its broadcast message for the frequency point F1 where the cells 1 and 3 are located and the frequency point F2 where the cells 2 and 4 are located in the neighbor list. The eNB switches the terminal to the gNB in a mode of switching across the core network according to neighbor list information and self-supporting capability of switching across the core network according to the capability of the terminal only supporting the SA mode and under the condition that the core network needs to be switched due to triggering of AR/VR service.

In one embodiment, if the OMC of the eNB triggers an X2 interface setup procedure with the gNB, then:

In 911, the eNB discovers that the pre-configuration information of the target gNB supports the NSA and SA dual mode, and the eNB discovers that the pre-configuration information of all cells of the target gNB lacks mode information and the eNB supports the handover function across EPC and 5GC core network, then the configuration information of the cell and the configuration information of the base station need to be sent to the gNB through EN-DC X2 Setup Request message, which includes the base station identifier of the eNB. The configuration information of each cell includes:

frequency information of cell

TAC of cell

PCI information of cell

Bandwidth and subframe configuration information of a cell

Whether or not handover across EPC and 5GC core networks is supported: 1

In 912, after the gNB receives the X2 message sent by the eNB, the gNB stores the base station configuration information, the cell configuration information and the handover support information of the cross-core network of the eNB according to the received message content, where if the gNB finds that both cells 1 and 3 support NSA and SA dual mode, and cells 2 and 4 only support SA mode. The gNB sends its base station configuration and enhanced configuration information for each cell to the eNB through an EN-DC X2 Setup Response message.

The configuration information of cells 1 and 3 includes:

Identification information of the cell: NR CGI information, 36 bits in length

PCI information of cell

TAC information of cell: 3byte length

Frequency point and frame structure information of cell

Cell mode information: 1

The configuration information of cells 2 and 4 includes:

Identification information of the cell: NR CGI information, 36 bits in length

PCI information of cell

TAC information of cell: 3byte length

Frequency point and frame structure information of cell

Cell mode information: 0

After receiving the EN-DC X2 Setup Response message sent by the gNB, the eNB saves configuration information or enhanced configuration information of the gNB cell into a neighbor cell list, where the neighbor cell list includes:

identity of the cell: NR CGI information

PCI information of cell

TAC information of cell: 3byte length

Frequency point of cell

Frame structure of cell

Mode information of cell

The eNB aims at a frequency point F1 where cells 1 and 3 are located and a frequency point F2 where cells 2 and 4 are located in the neighbor cell list, and reselection parameter information of the F1 and the F2 is added in a broadcast message of the eNB. The eNB switches the terminal to the gNB in a mode of switching across the core network according to neighbor list information and self-supporting capability of switching across the core network according to the capability of the terminal only supporting the SA mode and under the condition that the core network needs to be switched due to triggering of AR/VR service.

In one embodiment, when the gNB upgrades from supporting NSA only mode to supporting NSA+SA dual mode:

in 921, after the mode is changed, the gNB sends the configuration information of each cell and the configuration information of the base station to the eNB through EN-DC Configuration update Request message, and the enhanced configuration information of the four cells includes the following:

Identification information of the cell: NR CGI information, 36 bits in length

PCI information of cell

TAC information of cell: 3byte length

Frequency point and frame structure information of cell

Cell mode information: 1

In 922, after receiving the EN-DC Configuration Update Response message sent by the gcb, the eNB changes the mode in the enhanced configuration information of the gcb cell in the neighbor relation list from supporting NSA only to supporting NSA and SA dual mode.

The eNB aims at a frequency point F1 where cells 1 and 3 are located and a frequency point F2 where cells 2 and 4 are located in the neighbor cell list, and reselection parameter information of the F1 and the F2 is added in a broadcast message of the eNB. If the eNB which does not support the cross-EPC and 5GC core network switching function originally supports the cross-EPC and 5GC core network switching function after being upgraded, the configuration information of the cell and the capability of supporting the cross-EPC and 5GC core network switching are sent to the gNB through an EN-DC Configuration update Response message.

In one embodiment, when the gNB changes from supporting only NSA mode to supporting only SA single mode:

In 931, when the mode of all cells in the gNB changes to support the SA-only state, the gNB informs the eNB that the X2 connection needs to be released using an EN-DC X2 Setup Request procedure, wherein the EN-DC X2 Setup Request message contains:

En-gNB base station identity: length of 22-32 bits

Delete reason: EN-DC state does not support

After receiving the EN-DC X2 Setup Request message, the eNB determines all cells of the base station in the neighbor cell list according to the EN-gNB base station identifier carried in the message, determines that the cells become a state supporting only SA according to the deletion reason, and changes the mode of the cells into a state supporting only SA. The eNB aims at a frequency point F1 where cells 1 and 3 are located and a frequency point F2 where cells 2 and 4 are located in the neighbor cell list, and reselection parameter information of the F1 and the F2 is added in a broadcast message of the eNB.

In 932, the eNB sends an EN-DC X2 Setup Response message to the gNB and deletes all application layer configurations in the X2 connection and the SCTP connection for X2. The message carries acknowledgement information for deleting the X2 connection, and the acknowledgement information comprises:

eNBs base station identification

Whether or not handover across EPC and 5GC core networks is supported: 1

And after receiving the confirmation message, the gNB adjusts the neighbor cell information of the gNB, determines that the gNB is not connected with all cells of the eNB by X2, and deletes all application layer configurations and SCTP connection of X2 in the X2 connection. The eNB1 only supports SA mode according to the UE capability of the UE1, and the UE1 is switched to gNB by switching across the core network according to neighbor list information and self-supporting switching capability across the core network because the AR/VR service is triggered.

Through the method, when the supported NSA/SA mode of the gNB changes, the eNB side can automatically sense and adjust the corresponding parameter configuration and mobility strategy, so that manual intervention is reduced; different modes of gNB different cell configuration can be supported, and constraint of the existing protocol system on system mode configuration is reduced; supporting the eNB to support automatic interaction across EPC and 5GC core network capabilities, the gNB can make effective interoperation scheme selection based on the information; the terminal is less changed, and good backward compatibility and deployment feasibility are realized; the enhancement is carried out on the existing protocol, a new protocol process is not introduced, and the implementation difficulty is low.

A schematic structural diagram of one embodiment of a base station of the present disclosure is shown in fig. 10. The base station comprises a memory 1001 and a processor 1002. Wherein: memory 1001 may be a magnetic disk, flash memory, or any other non-volatile storage medium. The memory is used to store instructions in the corresponding embodiments of the inter-base station communication method hereinabove. The processor 1002, coupled to the memory 1001, may be implemented as one or more integrated circuits, such as a microprocessor or microcontroller. The processor 1002 is configured to execute instructions stored in the memory, so that the configuration of the base station meets the requirement of mode updating, and the adaptive capability of the base station configuration to the mode is improved.

In one embodiment, as also shown in fig. 11, base station 1100 includes memory 1101 and processor 1102. The processor 1102 is coupled to the memory 1101 by a BUS 1103. The base station 1100 may also be connected to external storage 1105 via a storage interface 1104 to invoke external data, a network or another computer system (not shown) via a network interface 1106. And will not be described in detail herein.

In this embodiment, the data instruction is stored in the memory, and the processor processes the instruction, so that the configuration of the base station meets the requirement of mode updating, and the self-adaptive capability of the base station configuration to the mode is improved.

In another embodiment, a computer readable storage medium has stored thereon computer program instructions which, when executed by a processor, implement the steps of the method in the corresponding embodiment of the inter-base station communication method. It will be apparent to those skilled in the art that embodiments of the present disclosure may be provided as a method, apparatus, or computer program product. Accordingly, the present disclosure may take the form of an entirely hardware embodiment, an entirely software embodiment, or an embodiment combining software and hardware aspects. Furthermore, the present disclosure may take the form of a computer program product embodied on one or more computer-usable non-transitory storage media (including, but not limited to, disk storage, CD-ROM, optical storage, etc.) having computer-usable program code embodied therein.

A schematic diagram of one embodiment of a communication system 1200 of the present disclosure is shown in fig. 12. The core network 1201 may include EPC, 5GC, and the specific content of the core network may be modified according to the situation of network upgrade. The first base station 1202 may be a gNB or an en-gNB, performing any of the operations performed by the first base station in the inter-base station communication method above; the second base station 1203 may be an eNB or a ng-eNB, performing any of the operations performed by the second base station above.

In the communication system, the base station can realize the interaction of the mode information and the configuration information of each covered cell and the cross-core network switching capability information of the base station, and can change the configuration according to the interacted information, thereby improving the self-adaption capability of the base station configuration to the mode, improving the backward compatibility, ensuring the determination of proper mobility strategies for the terminal and ensuring the user experience.

The present disclosure is described with reference to flowchart illustrations and/or block diagrams of methods, apparatus (systems) and computer program products according to embodiments of the disclosure. It will be understood that each flow and/or block of the flowchart illustrations and/or block diagrams, and combinations of flows and/or blocks in the flowchart illustrations and/or block diagrams, can be implemented by computer program instructions. These computer program instructions may be provided to a processor of a general purpose computer, special purpose computer, embedded processor, or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, create means for implementing the functions specified in the flowchart flow or flows and/or block diagram block or blocks.

These computer program instructions may also be stored in a computer-readable memory that can direct a computer or other programmable data processing apparatus to function in a particular manner, such that the instructions stored in the computer-readable memory produce an article of manufacture including instruction means which implement the function specified in the flowchart flow or flows and/or block diagram block or blocks.

These computer program instructions may also be loaded onto a computer or other programmable data processing apparatus to cause a series of operational steps to be performed on the computer or other programmable apparatus to produce a computer implemented process such that the instructions which execute on the computer or other programmable apparatus provide steps for implementing the functions specified in the flowchart flow or flows and/or block diagram block or blocks.

Thus far, the present disclosure has been described in detail. In order to avoid obscuring the concepts of the present disclosure, some details known in the art are not described. How to implement the solutions disclosed herein will be fully apparent to those skilled in the art from the above description.

The methods and apparatus of the present disclosure may be implemented in a number of ways. For example, the methods and apparatus of the present disclosure may be implemented by software, hardware, firmware, or any combination of software, hardware, firmware. The above-described sequence of steps for the method is for illustration only, and the steps of the method of the present disclosure are not limited to the sequence specifically described above unless specifically stated otherwise. Furthermore, in some embodiments, the present disclosure may also be implemented as programs recorded in a recording medium, the programs including machine-readable instructions for implementing the methods according to the present disclosure. Thus, the present disclosure also covers a recording medium storing a program for executing the method according to the present disclosure.

Finally, it should be noted that: the above embodiments are merely for illustrating the technical solution of the present disclosure and are not limiting thereof; although the present disclosure has been described in detail with reference to preferred embodiments, those of ordinary skill in the art will appreciate that: modifications may be made to the specific embodiments of the disclosure or equivalents may be substituted for part of the technical features; without departing from the spirit of the technical solutions of the present disclosure, it should be covered in the scope of the technical solutions claimed in the present disclosure.

Claims

1. A method of inter-base station communication, comprising:

When a cell which is covered by a first base station and supports the NSA single mode of the independent networking is switched to support the NSA and SA double mode:

The first base station sends target mode configuration information of the first base station to a second base station through an inter-base station interface so that the second base station can store the target mode configuration information of the first base station into a neighbor list, wherein the target mode configuration information of the first base station comprises mode information of NSA and SA dual modes supported by a cell covered by the first base station;

The first base station receives configuration information from the second base station through an inter-base station interface, wherein the configuration information of the second base station comprises cross-core network switching capability information of the second base station;

and the first base station stores the configuration information of the second base station into a neighbor list.

2. The method of claim 1, wherein,

The target mode configuration information of the first base station further comprises cell identification, physical cell identification PCI information, tracking area code TAC information and frequency point and frame structure information after the cell is switched to support NSA and SA dual modes.

3. The method of claim 1, further comprising:

When the first base station establishes an inter-base station connection with the second base station:

The first base station sends configuration information of the first base station to the second base station through an inter-base station interface, wherein if a cell covered by the first base station comprises one or more cells supporting NSA and SA dual modes, the configuration information of the first base station comprises mode information supported by a corresponding cell;

The first base station receives configuration information from the second base station through an inter-base station interface, wherein the configuration information of the first base station comprises cross-core network switching capability information of the second base station;

4. The method of claim 1 or 2, further comprising:

And when the first base station determines that the second base station has the cross-core network switching capability information according to the neighbor cell list, the first base station determines that the terminal which is positioned in the cell supporting the SA mode and supports the SA mode can perform the cross-core network switching.

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

in the case that the mode of all cells in the first base station is switched to the mode supporting the SA single mode:

Transmitting an inter-base station interface release request to the second base station through an inter-base station interface message, wherein the inter-base station interface release request comprises a base station identifier of a first base station and interface deletion reason information;

And deleting the application layer configuration of the interface between the base stations and the stream control transmission protocol SCTP connection according to the deletion confirmation information fed back by the second base station.

6. A method according to any of claims 1-3, wherein the first base station is a 5G base station, gNB, or en-gNB, and the second base station is an evolved base station, eNB, or ng-eNB.

7. A method of inter-base station communication, comprising:

The second base station receives the target mode configuration information from the first base station through an inter-base station interface and stores the target mode configuration information into a neighbor list, wherein the target mode configuration information of the first base station comprises configuration information after each cell covered by the first base station is switched to support NSA and SA dual modes;

the second base station sends configuration information of the second base station to the first base station through an inter-base station interface so that the first base station can store the configuration information into a neighbor list, and the configuration information of the second base station comprises cross-core network switching capability information of the second base station.

8. The method of claim 7, wherein,

9. The method of claim 7, further comprising:

The second base station sends configuration information of the second base station to the first base station through an inter-base station interface, wherein the configuration information of the second base station comprises cross-core network switching capability information of the second base station;

The second base station receives configuration information from the first base station through an inter-base station interface and stores the configuration information into a neighbor list, wherein if a cell covered by the first base station comprises one or more cells supporting NSA and SA dual modes, the configuration information of the first base station comprises mode information supported by a corresponding cell.

10. The method of claim 7 or 8, further comprising:

The second base station allows the terminal to switch across the core network when determining that the second base station has the capability of switching across the core network and the terminal supporting the SA mode is positioned in a cell supporting the SA mode; and/or the number of the groups of groups,

And the second base station determines a cell supporting the SA single mode and/or supporting NSA and SA dual mode and a frequency point where the cell is located according to the neighbor cell list, and frequency point and/or cell reselection parameter information is added in a broadcast message of the second base station.

11. The method of any of claims 7-9, further comprising:

In case that all cells in the first base station are switched to support SA single mode:

receiving an inter-base station interface release request from the first base station through an inter-base station interface, wherein the inter-base station interface release request comprises a base station identifier of the first base station and interface deletion reason information;

And deleting the application layer configuration and Stream Control Transmission Protocol (SCTP) connection of the interface between the base stations, and feeding back deletion confirmation information to the first base station so that the first base station deletes the application layer configuration and the SCTP connection of the interface between the base stations.

12. A base station, comprising:

A memory; and

A processor coupled to the memory, the processor configured to perform the method of any of claims 1 to 11 based on instructions stored in the memory.

13. A computer readable storage medium having stored thereon computer program instructions which, when executed by a processor, implement the steps of the method of any of claims 1 to 11.

14. A communication system, comprising:

A first base station configured to perform the method of any of claims 1 to 6;

A second base station configured to perform the method of any of claims 7 to 11; and, a step of, in the first embodiment,

A core network.