WO2025099943A1 - Small base station, network node, and communication method - Google Patents

Abstract

This small base station in a first communication system includes: a reception unit that receives, from a first network node, a comparative table indicating a correspondence relationship between a cell group identifier in the first communication system and a cell group identifier in a second communication system, and a list of cell group identifiers in the first communication system in which access by a terminal is permitted; a control unit that, when a handover to the second communication system is executed, selects a transfer destination small base station having the cell group identifier or a general transfer destination base station, on the basis of the comparative table and the list; and a transmission unit that transmits a message requesting a handover to the transfer destination small base station or the transfer destination base station via the first network node.

Description

Small base station, network node, and communication method

The present invention relates to a small base station, a network node, and a communication method in a communication system.

3GPP (registered trademark) (3rd Generation Partnership Project) is currently studying a wireless communication method called 5G or NR (New Radio) (hereinafter, this wireless communication method will be referred to as "5G" or "NR") in order to achieve even larger system capacity, even faster data transmission speeds, and even lower latency in wireless sections. For 5G, various wireless technologies are being studied to meet the requirements of achieving a throughput of 10 Gbps or more while keeping latency in wireless sections to 1 ms or less.

NR is considering a network architecture including 5GC (5G Core Network), which corresponds to EPC (Evolved Packet Core), the core network in the network architecture of LTE (Long Term Evolution), and NG-RAN (Next Generation-Radio Access Network), which corresponds to E-UTRAN (Evolved Universal Terrestrial Radio Access Network), the RAN (Radio Access Network) in the network architecture of LTE (for example, non-patent document 1).

3GPP TS 23.501 V18.1.0 (2023-03) 3GPP TS 36.413 V17.5.0 (2023-06) 3GPP TS 23.401 V18.4.0 (2023-09) 3GPP TS 38.413 V17.6.0 (2023-09) 3GPP TS 23.502 V18.3.0 (2023-09)

Home eNB (HeNB), a small base station in LTE, uses CSG (Closed Subscriber Group) to control cell access, while Home gNB (HgNB), a small base station in 5G, uses CAG (Closed Access Group) to control cell access. When performing handover (HO) between HeNB and HgNB, handover must be performed within the scope permitted by the subscriber information.

However, existing specifications do not provide a procedure for performing handover between HeNB and HgNB within the scope permitted by the subscriber information.

The present invention has been made in consideration of the above points, and aims to execute handover between HeNB and HgNB in a wireless communication system within the scope permitted by the subscriber information.

According to the disclosed technology, a small base station in a first communication system is provided, the small base station having a receiver that receives from a first network node a comparison table showing the correspondence between cell group identifiers in the first communication system and cell group identifiers in a second communication system and a list of cell group identifiers in the first communication system to which a terminal is permitted to access, a control unit that selects a destination small base station having the cell group identifier or a general destination base station based on the comparison table and the list when a handover to the second communication system is performed, and a transmitter that transmits a message requesting a handover to the destination small base station or the destination base station via the first network node.

The disclosed technology makes it possible to execute handover between HeNB and HgNB in a wireless communication system within the scope permitted by the subscriber information.

FIG. 1 is a diagram illustrating an example of a communication system. FIG. 1 is a diagram illustrating an example of a communication system in a roaming environment. FIG. 2 is a diagram showing an example of a first sequence diagram according to an embodiment of the present invention; FIG. 11 is a diagram showing an example of a second sequence diagram according to an embodiment of the present invention. FIG. 11 is a diagram showing an example of a third sequence diagram according to an embodiment of the present invention. FIG. 13 is a diagram showing an example of a fourth sequence diagram in an embodiment of the present invention. FIG. 2 is a diagram illustrating an example of a functional configuration of a base station 10 and a network node 30 according to an embodiment of the present invention. FIG. 2 is a diagram illustrating an example of a functional configuration of a terminal 20 according to an embodiment of the present invention. 2 is a diagram illustrating an example of the hardware configuration of a base station 10, a terminal 20, and a network node 30 in an embodiment of the present invention. FIG. 2 is a diagram showing an example of the configuration of a vehicle 2001 according to an embodiment of the present invention.

Below, an embodiment of the present invention will be described with reference to the drawings. Note that the embodiment described below is an example, and the embodiment to which the present invention can be applied is not limited to the following embodiment.

In operating the wireless communication system according to the embodiment of the present invention, existing technology is used as appropriate. However, the existing technology is, for example, the existing LTE, but is not limited to the existing LTE. Furthermore, the term "LTE" used in this specification has a broad meaning including LTE-Advanced and systems subsequent to LTE-Advanced (e.g., NR), or wireless LAN (Local Area Network), unless otherwise specified.

Furthermore, in the embodiment of the present invention, "configuring" wireless parameters and the like may mean that predetermined values are pre-configured, or that wireless parameters notified from the network node 30 or the terminal 20 are configured.

FIG. 1 is a diagram for explaining an example of a communication system. As shown in FIG. 1, the communication system is composed of a UE, which is a terminal 20, and multiple network nodes 30. In the following, it is assumed that one network node 30 corresponds to each function, but multiple functions may be realized by one network node 30, or multiple network nodes 30 may realize one function. In addition, the "connection" described below may be a logical connection or a physical connection.

The RAN (Radio Access Network) is a network node 30 having a radio access function, which may include a base station 10, and is connected to a UE, an AMF (Access and Mobility Management Function), and a UPF (User plane function). The AMF is a network node 30 having functions such as RAN interface termination, NAS (Non-Access Stratum) termination, registration management, connection management, reachability management, and mobility management. The UPF is a network node 30 having functions such as a PDU (Protocol Data Unit) session point to the outside that interconnects with a DN (Data Network), packet routing and forwarding, and user plane QoS (Quality of Service) handling. The UPF and DN constitute a network slice. In the wireless communication network in an embodiment of the present invention, multiple network slices are constructed.

The AMF is connected to the UE, RAN, SMF (Session Management function), NSSF (Network Slice Selection Function), NEF (Network Exposure Function), NRF (Network Repository Function), UDM (Unified Data Management), AUSF (Authentication Server Function), PCF (Policy Control Function), and AF (Application Function). The AMF, SMF, NSSF, NEF, NRF, UDM, AUSF, PCF, and AF are network nodes 30 that are interconnected via interfaces based on their respective services: Namf, Nsmf, Nnssf, Nnef, Nnrf, Nudm, Nausf, Npcf, and Naf.

The SMF is a network node 30 having functions such as session management, IP (Internet Protocol) address allocation and management for UEs, DHCP (Dynamic Host Configuration Protocol) function, ARP (Address Resolution Protocol) proxy, and roaming function. The NEF is a network node 30 having a function of notifying other NFs (Network Functions) of capabilities and events. The NSSF is a network node 30 having functions such as selecting a network slice to which the UE connects, determining an allowed NSSAI (Network Slice Selection Assistance Information), determining an NSSAI to be set, and determining an AMF set to which the UE connects. The PCF is a network node 30 having a function of controlling network policies. The AF is a network node 30 having a function of controlling application servers. The NRF is a network node 30 having a function of discovering NF instances that provide services. The UDM is a network node 30 that manages subscriber data and authentication data. The UDM is connected to a User Data Repository (UDR) that holds the data.

FIG. 2 is a diagram for explaining an example of a communication system in a roaming environment. As shown in FIG. 2, the network is composed of a UE, which is a terminal 20, and multiple network nodes 30. In the following, it is assumed that one network node 30 corresponds to each function, but multiple functions may be realized by one network node 30, or multiple network nodes 30 may realize one function. In addition, the "connection" described below may be a logical connection or a physical connection.

The RAN is a network node 30 with radio access functionality, and is connected to the UE, AMF, and UPF. The AMF is a network node 30 with functionality such as RAN interface termination, NAS termination, registration management, connection management, reachability management, and mobility management. The UPF is a network node 30 with functionality such as a PDU session point to the outside that interconnects with the DN, packet routing and forwarding, and user plane QoS handling. The UPF and DN constitute a network slice. In the wireless communication network in the embodiment of the present invention, multiple network slices are constructed.

The AMF is connected to the UE, RAN, SMF, NSSF, NEF, NRF, UDM, AUSF, PCF, AF, and SEPP (Security Edge Protection Proxy). The AMF, SMF, NSSF, NEF, NRF, UDM, AUSF, PCF, and AF are network nodes 30 that are interconnected via interfaces based on their respective services: Namf, Nsmf, Nnssf, Nnef, Nnrf, Nudm, Nausf, Npcf, and Naf.

The SMF is a network node 30 having functions such as session management, UE IP address allocation and management, DHCP function, ARP proxy, and roaming function. The NEF is a network node 30 having a function of notifying other NFs of capabilities and events. The NSSF is a network node 30 having functions such as selecting a network slice to which a UE will connect, determining an allowed NSSAI, determining an NSSAI to be configured, and determining an AMF set to which a UE will connect. The PCF is a network node 30 having a function of performing network policy control. The AF is a network node 30 having a function of controlling application servers. The NRF is a network node 30 having a function of discovering NF instances that provide services. The SEPP is a non-transparent proxy that filters control plane messages between PLMNs (Public Land Mobile Networks). The vSEPP shown in Figure 2 is a SEPP in the visited network, and the hSEPP is a SEPP in the home network.

As shown in Figure 2, the UE is in a roaming environment connected to the RAN and AMF in the VPLMN (Visited PLMN). The VPLMN and the HPLMN (Home PLMN) are connected via vSEPP and hSEPP. The UE can communicate with the UDM of the HPLMN, for example, via the AMF of the VPLMN.

(Example)
An embodiment will be described. In the first and second embodiments shown below, a process of executing a handover between a HeNB and an HgNB will be described. In the existing specifications, a Home eNB (HeNB), which is a small base station in LTE, uses a Closed Subscriber Group (CSG), and a Home gNB (HgNB), which is a small base station in 5G, a communication system different from LTE, uses a Closed Access Group (CAG) to control cell access. Here, when executing a handover (Handover, HO) between a HeNB and an HgNB, it is necessary to execute the handover within the range permitted by the subscriber information.

However, existing specifications do not provide a procedure for performing handover between HeNB and HgNB within the scope permitted by the subscriber information.

In addition, when performing HO between HeNB and HgNB, it is necessary to consider cases where changes to the specifications of HeNB, HgNB, and MME under the existing specifications are not permitted.

In the first embodiment, a method for performing a handover between a HeNB and an HgNB when changes to existing specifications related to the HeNB, HgNB, and MME are permitted will be described.

In the second embodiment, a method for performing a handover between a HeNB and an HgNB in a case where changes to existing specifications related to the HeNB, HgNB, and MME are not permitted will be described.

Furthermore, the communication system accommodating the (H)eNB may be referred to as LTE or EPS (Evolved Packet System), etc., and the communication system accommodating the (H)gNB may be referred to as NR, 5G, or 5GS (5G system), etc. Furthermore, the CSG ID may be referred to as the cell group identifier of the HeNB accommodating the LTE cell, and the CAG ID may be referred to as the cell group identifier of the HgNB accommodating the 5G cell. Furthermore, the information, requests, responses, etc. transmitted and received in the sequence diagram in this embodiment may be referred to as messages.

(First embodiment)
A first embodiment will be described below. In the first embodiment, a procedure for executing a handover between a HeNB and an HgNB in a case where changes to existing specifications related to a HeNB, an HgNB, and an MME are permitted will be described.

(Procedure for Executing Handover in HeNB)
3 is a diagram showing an example of a first sequence diagram according to an embodiment of the present invention. The process of each step in FIG. 3 will be described below.

The following steps S301 to S303 are the procedure for setting up the interface between the (H)eNB and the MME (S1 Setup, see Section 9.1.8.4 of Non-Patent Document 2).

Step S301: HeNB10a sends an S1 setup request to MME30a. The request message includes a CSG ID list (a list including the IDs (identifiers) of the CSGs provided by HeNB10a).

Step S302: Assuming that MME 30a has a mapping table (comparison table) showing the correspondence between CSG IDs and CAG IDs, MME 30a generates a mapping table showing the correspondence between CSG IDs and CAG IDs for the CSG IDs included in the CSG ID list received in step S301.

Step S303: MME 30a transmits the mapping table generated in step S302 to HeNB 10a.

The following steps S304 and S305 are processes in the network connection procedure of terminal 20 (Attach procedure, see step 17 in section 5.3.2.1 of Non-Patent Document 3).

Step S304: MME 30a sends an Initial Context Setup request (see Section 9.1.4.1 of Non-Patent Document 2) to HeNB 10a to request the setting of an initial context. The request message includes a new Allowed CSG list in the Handover Restriction List (see Section 9.2.1.22 of Non-Patent Document 2).

Step S305: HeNB10a stores the permitted CSG list received in step S304 in the terminal context.

The following steps S306 and S307 are processes executed by HeNB10a, which is the source base station, in the handover process from EPS to 5GS.

Step S306: Based on the mapping table received in step S303 and the permitted CSG list received in step S304, HeNB 10a selects a small 5GS base station (HgNB) that is accessible to terminal 20 as the handover destination (target) base station. Alternatively, HeNB 10a may select a general 5GS base station (gNB).

Step S307: HeNB 10a sends a message (Handover required) requesting handover to MME 30a. That is, HeNB 10a sends a message (Handover required) requesting handover to the destination (small) base station via MME 30a. The request message includes the identifier of the destination base station selected in step S306.

The following steps S308 and S309 are processes executed by HeNB10a, which is the target base station, in the handover process.

Step S308: MME 30a sends a Handover request (see Section 9.1.5.4 of Non-Patent Document 2) to HeNB 10a to request execution of a handover. The request message includes a new Allowed CSG list in the Handover Restriction List (see Section 9.2.1.22 of Non-Patent Document 2).

Step S309: In response to the request message received in step S308, HeNB10a verifies whether or not handover can be performed by checking whether the allowed CSG list included in the request message includes the CSG ID provided by HeNB10a.

(Procedure for executing handover in HgNB)
4 is a diagram showing an example of a second sequence diagram according to an embodiment of the present invention. The process of each step in FIG. 4 will be described below.

The following steps S401 to S403 are the procedure for setting up the interface between the (H)gNB and the AMF (NG Setup, see Section 9.2.6.1 of Non-Patent Document 4).

Step S401: HgNB 10b sends an NG setup request to AMF 30b. The request message includes a CAG ID list (a list including the IDs (identifiers) of the CAGs provided by HgNB 10a).

Step S402: Assuming that AMF 30b has a mapping table (comparison table) showing the correspondence between CAG IDs and CSG IDs, AMF 30b generates a mapping table showing the correspondence between CAG IDs and CSG IDs for the CAG IDs included in the CAG ID list received in step S401.

Step S403: AMF 30b sends the mapping table generated in step S402 to HgNB 10b.

The following steps S404 and S405 are processes in the registration procedure of terminal 20 (see step 21 in section 4.2.2.2.2 of Non-Patent Document 5).

Step S404: AMF 30b sends an Initial Context Setup request (see Section 9.2.2.1 of Non-Patent Document 4) to HgNB 10b to request the setting of an initial context. The request message includes the Allowed CAG list in the Allowed PNI-NPN List (see Section 9.3.3.45 of Non-Patent Document 4) in the Mobility Restriction List (see Section 9.3.1.85 of Non-Patent Document 4).

Step S405: HgNB10b stores the permitted CAG list received in step S404 in the terminal context.

The following steps S406 and S407 are processes executed by HgNB10b, which is the source base station, in the handover process from 5GS to EPS.

Step S406: HgNB 10b selects a small base station (HeNB) in the EPS that is accessible to terminal 20 as the handover destination (target) base station based on the mapping table received in step S403 and the permitted CAG list received in step S404. Alternatively, HgNB 10b may select a general base station (eNB) in the EPS.

Step S407: HgNB 10b sends a message (Handover required) to AMF 30b requesting a handover. That is, HgNB 10b sends a message (Handover required) to the destination (small) base station via AMF 30b requesting a handover. The request message includes the identifier of the destination base station selected in step S406.

The following steps S408 and S409 are executed by the target base station, HgNB10b, during the handover process.

Step S408: AMF 30b sends a Handover request (see Section 9.2.3.4 of Non-Patent Document 4) to HgNB 10b to request execution of handover. The request message includes the Allowed CAG list in the Allowed PNI-NPN List (see Section 9.3.3.45 of Non-Patent Document 4) in the Mobility Restriction List (see Section 9.3.1.85 of Non-Patent Document 4).

Step S409: In response to the request message received in step S408, HgNB10b verifies whether or not handover can be performed by checking whether the CAG ID provided by HgNB10b is included in the permitted CAG list contained in the request message.

(Second Example)
A second embodiment will be described. In the second embodiment, a method in which a HeNB and an HgNB execute handover between them in a case in which changes to existing specifications related to a HeNB, an HgNB, and an MME are not permitted (changes to existing specifications related to a terminal 20, an AMF, an SMF, and the like are permitted) will be described.

(Procedure for executing handover from HeNB to HgNB)
Fig. 5 is a diagram showing an example of a third sequence diagram in an embodiment of the present invention. This sequence includes processing in existing specifications (see Section 4.11.1.2.2 of Non-Patent Document 5) related to handover from EPS to 5GS. The processing of each step in Fig. 5 will be described below.

Step S501: The terminal 20 transmits a measurement result report (Measurement Report) to the HeNB 10a. The report includes a physical layer cell identifier (Physical layer Cell Identification, PCI) for the cell of the measurement result.

Step S502: HeNB 10a transmits a message (Handover required) requesting handover to MME 30a. The request message includes the identifier of the destination base station that corresponds to the cell identifier included in the message received in step S501.

Step S503: MME 30a sends a message (Forward Relocation Request) to AMF 30b requesting continuation of the handover procedure. The request message includes the identifier (Target Identification) of the destination base station included in the message received in step S502.

Step S504: AMF 30b sends a request (Nsmf_PDUSession_CreateSMContext request) to SMF+PGW-C 30c to create a context for the PDU session. SMF+PGW-C 30c is a network node 30 that has the functions of SMF (Session Management Function) and PGW (Packet data network Gateway)-C (C-plane).

Step S505: SMF+PGW-C 30c sends an Nsmf_PDUSession_CreateSMContext response to AMF 30b in response to the request received in step S504. The response message includes the information element cagData, which includes the allowed CAG list (Allowed CAG list).

Step S506: It is assumed that AMF 30b has received a mapping table (comparison table) from OAM (Operation Administration and Maintenance) indicating the correspondence between the identifier of the small base station in 5GS (HgNB ID) and the identifier of the CAG (CAG ID).

Step S507: AMF 30b obtains the CAG ID corresponding to the base station identifier (Target Identification) included in the request message received in step S503 based on a mapping table showing the correspondence between HgNB IDs and CAG IDs.

Step S508: AMF 30b checks whether terminal 20 is permitted to access HgNB 10b (i.e., whether handover to HgNB 10b is possible) based on whether the CAG ID acquired in step S507 is included in the permitted CAG list received in step S505.

Step S509: AMF 30b sends a Handover request to HgNB 10b, which is the destination (target) base station, to request execution of a handover. The request message includes the allowed CAG list.

(Procedure for executing handover from HgNB to HeNB)
Fig. 6 is a diagram showing an example of a fourth sequence diagram in an embodiment of the present invention. This sequence includes processing in existing specifications (see Section 4.11.1.2.1 of Non-Patent Document 5) related to handover from 5GS to EPS. The processing of each step in Fig. 6 will be described below.

Step S601: The terminal 20 transmits a measurement result report (MeasurementReport) to the HgNB 10b. The report includes the physical layer cell identifier (Physical layer Cell Identification, PCI) for the cell of the measurement result.

Step S602: HgNB 10b sends a message (Handover required) to AMF 30b requesting handover. The request message includes the identifier (Target Identification) of the destination base station that corresponds to the cell identifier included in the message received in step S501.

Step S603: It is assumed that AMF 30b has received a mapping table (comparison table) from OAM (Operation Administration and Maintenance) indicating the correspondence between the identifiers of small base stations in 5GS (HeNB IDs) and the CAG identifiers (CAG IDs).

Step S604: AMF 30b obtains the identifier (HgNB ID) of HgNB 10b, which is the source of the handover and sent the request message, from the request message received in step S602, and further obtains the CAG ID=xx corresponding to that identifier.

Step S605: It is assumed that AMF 30b has received a mapping table (comparison table) from OAM indicating the correspondence between the small base station identifier (HeNB ID) in the EPS and the CSG identifier (CSG ID).

Step S606: AMF 30b acquires CSG ID=aa corresponding to the identifier (Target Identification) of the HeNB that is the destination of the handover, which is included in the request message received in step S602, based on the mapping table of HeNB ID and CSG ID. Furthermore, AMF 30b has a mapping table (comparison table) that indicates the correspondence between CSG ID and CAG ID, and confirms that CSG ID=aa and CAG=xx correspond to each other based on the mapping table, thereby confirming that handover can be performed.

Step S607: AMF 30b includes the CSG ID=aa corresponding to the destination HeNB 10a in the Forward Relocation request.

Step S608: AMF 30b sends a message (Forward Relocation Request) to MME 30a requesting continuation of the handover procedure. MME 10a can confirm that handover can be performed based on the CSG identifier (CSG ID=aa) corresponding to the destination small base station contained in the request message.

The above-described embodiment allows handover between HeNB and HgNB to be performed within the scope permitted by the subscriber information in a wireless communication system.

(Device configuration)
Next, examples of functional configurations of the base station 10, the network node 30, and the terminal 20 that perform the processes and operations described above will be described. The base station 10, the network node 30, and the terminal 20 each include functions for performing the above-described embodiments. However, the base station 10, the network node 30, and the terminal 20 may each include only a part of the functions in the embodiments.

<Base Station 10 and Network Node 30>
FIG. 7 is a diagram showing an example of the functional configuration of the base station 10 and the network node 30. As shown in FIG. 7, the base station 10 has a transmitting unit 110, a receiving unit 120, a setting unit 130, and a control unit 140. The functional configuration shown in FIG. 7 is merely an example. As long as the operation according to the embodiment of the present invention can be performed, the names of the functional divisions and the functional units may be any. Note that the network node 30 may have the same functional configuration as the base station 10. Furthermore, a network node 30 having a plurality of different functions in the system architecture may be composed of a plurality of network nodes 30 separated by function.

The transmitting unit 110 has a function of generating a signal to be transmitted to the terminal 20 or another network node 30, and transmitting the signal by wire or wirelessly. The receiving unit 120 has a function of receiving various signals transmitted from the terminal 20 or another network node 30, and acquiring, for example, information of a higher layer from the received signal. A communication unit including the transmitting unit 110 and the receiving unit 120 may be configured.

The setting unit 130 stores pre-set setting information and various setting information to be sent to the terminal 20 in a storage device, and reads it from the storage device as needed.

The control unit 140 performs processing related to handover between a HeNB and an HgNB as described in the embodiment. The control unit 140 also performs processing related to communication with the terminal 20. The functional unit in the control unit 140 related to signal transmission may be included in the transmitting unit 110, and the functional unit in the control unit 140 related to signal reception may be included in the receiving unit 120.

<Terminal 20>
Fig. 8 is a diagram showing an example of the functional configuration of the terminal 20. As shown in Fig. 8, the terminal 20 has a transmitting unit 210, a receiving unit 220, a setting unit 230, and a control unit 240. The functional configuration shown in Fig. 8 is merely an example. As long as the operation related to the embodiment of the present invention can be performed, the names of the functional divisions and functional units may be any. In addition, the communication device that becomes the resource holder 20 may have the same functional configuration as the terminal 20.

The transmitting unit 210 creates a transmission signal from the transmission data and transmits the transmission signal wirelessly. The receiving unit 220 wirelessly receives various signals and obtains higher layer signals from the received physical layer signals. The receiving unit 220 also has a function of receiving control signals or reference signals, etc. transmitted from the network node 30. A communication unit including the transmitting unit 210 and the receiving unit 220 may be configured.

The setting unit 230 stores various setting information received from the network node 30 by the receiving unit 220 in a storage device, and reads it from the storage device as necessary. The setting unit 230 also stores setting information that is set in advance.

The control unit 240 performs processing related to handover between a HeNB and an HgNB, as described in the embodiment. The functional unit related to signal transmission in the control unit 240 may be included in the transmitting unit 210, and the functional unit related to signal reception in the control unit 240 may be included in the receiving unit 220.

(Hardware configuration)
The block diagrams (FIGS. 7 and 8) used in the description of the above embodiments show functional blocks. These functional blocks (components) are realized by any combination of at least one of hardware and software. The method of realizing each functional block is not particularly limited. That is, each functional block may be realized using one device that is physically or logically coupled, or may be realized using two or more devices that are physically or logically separated and directly or indirectly connected (for example, using wires, wirelessly, etc.) and these multiple devices. The functional block may be realized by combining the one device or the multiple devices with software.

Functions include, but are not limited to, judgement, determination, judgment, calculation, computation, processing, derivation, investigation, search, confirmation, reception, transmission, output, access, resolution, selection, election, establishment, comparison, assumption, expectation, regarding, broadcasting, notifying, communicating, forwarding, configuring, reconfiguring, allocating, mapping, and assignment. For example, a functional block (component) that performs the transmission function is called a transmitting unit or transmitter. As mentioned above, there are no particular limitations on the method of realization for either of these.

For example, the base station 10, network node 30, terminal 20, etc. in one embodiment of the present disclosure may function as a computer that performs processing of the wireless communication method of the present disclosure. FIG. 9 is a diagram showing an example of the hardware configuration of the base station 10 and terminal 20 in one embodiment of the present disclosure. The network node 30 may have the same hardware configuration as the base station 10. The above-mentioned base station 10 and terminal 20 may be physically configured as a computer device including a processor 1001, a memory device 1002, an auxiliary memory device 1003, a communication device 1004, an input device 1005, an output device 1006, a bus 1007, etc.

In the following description, the term "apparatus" can be interpreted as a circuit, device, unit, etc. The hardware configuration of the base station 10 and the terminal 20 may be configured to include one or more of the devices shown in the figure, or may be configured to exclude some of the devices.

The functions of the base station 10 and the terminal 20 are realized by loading specific software (programs) onto hardware such as the processor 1001 and the storage device 1002, causing the processor 1001 to perform calculations, control communications by the communication device 1004, and control at least one of the reading and writing of data in the storage device 1002 and the auxiliary storage device 1003.

The processor 1001, for example, operates an operating system to control the entire computer. The processor 1001 may be configured as a central processing unit (CPU) including an interface with peripheral devices, a control device, an arithmetic unit, registers, etc. For example, the above-mentioned control unit 140, control unit 240, etc. may be realized by the processor 1001.

The processor 1001 reads out a program (program code), software module, data, etc. from at least one of the auxiliary storage device 1003 and the communication device 1004 to the storage device 1002, and executes various processes according to the program. The program is a program that causes a computer to execute at least a part of the operations described in the above-mentioned embodiment. For example, the control unit 140 of the base station 10 shown in FIG. 7 may be stored in the storage device 1002 and realized by a control program that runs on the processor 1001. For example, the control unit 240 of the terminal 20 shown in FIG. 8 may be stored in the storage device 1002 and realized by a control program that runs on the processor 1001. Although the above-mentioned various processes have been described as being executed by one processor 1001, they may be executed simultaneously or sequentially by two or more processors 1001. The processor 1001 may be implemented by one or more chips. The program may be transmitted from a network via a telecommunication line.

The storage device 1002 is a computer-readable recording medium and may be composed of, for example, at least one of a ROM (Read Only Memory), an EPROM (Erasable Programmable ROM), an EEPROM (Electrically Erasable Programmable ROM), a RAM (Random Access Memory), etc. The storage device 1002 may also be called a register, a cache, a main memory, etc. The storage device 1002 can store executable programs (program codes), software modules, etc. for implementing a communication method relating to one embodiment of the present disclosure.

The auxiliary storage device 1003 is a computer-readable recording medium, and may be, for example, at least one of an optical disk such as a CD-ROM (Compact Disc ROM), a hard disk drive, a flexible disk, a magneto-optical disk (e.g., a compact disk, a digital versatile disk, a Blu-ray (registered trademark) disk), a smart card, a flash memory (e.g., a card, a stick, a key drive), a floppy (registered trademark) disk, a magnetic strip, etc. The above-mentioned storage medium may be, for example, a database, a server, or other suitable medium that includes at least one of the storage device 1002 and the auxiliary storage device 1003.

The communication device 1004 is hardware (transmitting/receiving device) for communicating between computers via at least one of a wired network and a wireless network, and is also referred to as, for example, a network device, a network controller, a network card, a communication module, etc. The communication device 1004 may be configured to include a high-frequency switch, a duplexer, a filter, a frequency synthesizer, etc., to realize at least one of, for example, Frequency Division Duplex (FDD) and Time Division Duplex (TDD). For example, the transmitting/receiving antenna, an amplifier unit, a transmitting/receiving unit, a transmission path interface, etc. may be realized by the communication device 1004. The transmitting/receiving unit may be implemented as a transmitting unit or a receiving unit that is physically or logically separated.

The input device 1005 is an input device (e.g., a keyboard, a mouse, a microphone, a switch, a button, a sensor, etc.) that accepts input from the outside. The output device 1006 is an output device (e.g., a display, a speaker, an LED lamp, etc.) that performs output to the outside. Note that the input device 1005 and the output device 1006 may be integrated into one structure (e.g., a touch panel).

Furthermore, each device such as the processor 1001 and the storage device 1002 is connected by a bus 1007 for communicating information. The bus 1007 may be configured using a single bus, or may be configured using different buses between each device.

Furthermore, the base station 10 and the terminal 20 may be configured to include hardware such as a microprocessor, a digital signal processor (DSP), an application specific integrated circuit (ASIC), a programmable logic device (PLD), or a field programmable gate array (FPGA), and some or all of the functional blocks may be realized by the hardware. For example, the processor 1001 may be implemented using at least one of these pieces of hardware.

FIG. 10 shows an example configuration of a vehicle 2001. As shown in FIG. 10, the vehicle 2001 includes a drive unit 2002, a steering unit 2003, an accelerator pedal 2004, a brake pedal 2005, a shift lever 2006, front wheels 2007, rear wheels 2008, an axle 2009, an electronic control unit 2010, various sensors 2021-2029, an information service unit 2012, and a communication module 2013. Each aspect/embodiment described in this disclosure may be applied to a communication device mounted on the vehicle 2001, and may be applied to the communication module 2013, for example.

The drive unit 2002 is composed of, for example, an engine, a motor, or a hybrid of an engine and a motor. The steering unit 2003 includes at least a steering wheel (also called a handlebar), and is configured to steer at least one of the front wheels and the rear wheels based on the operation of the steering wheel operated by the user.

The electronic control unit 2010 is composed of a microprocessor 2031, memory (ROM, RAM) 2032, and a communication port (IO port) 2033. Signals are input to the electronic control unit 2010 from various sensors 2021 to 2029 provided in the vehicle 2001. The electronic control unit 2010 may also be called an ECU (Electronic Control Unit).

Signals from the various sensors 2021-2029 include a current signal from a current sensor 2021 that senses the motor current, a front and rear wheel rotation speed signal obtained by a rotation speed sensor 2022, a front and rear wheel air pressure signal obtained by an air pressure sensor 2023, a vehicle speed signal obtained by a vehicle speed sensor 2024, an acceleration signal obtained by an acceleration sensor 2025, an accelerator pedal depression amount signal obtained by an accelerator pedal sensor 2029, a brake pedal depression amount signal obtained by a brake pedal sensor 2026, a shift lever operation signal obtained by a shift lever sensor 2027, and a detection signal for detecting obstacles, vehicles, pedestrians, etc. obtained by an object detection sensor 2028.

The information service unit 2012 is composed of various devices, such as a car navigation system, an audio system, speakers, a television, and a radio, for providing (outputting) various information such as driving information, traffic information, and entertainment information, and one or more ECUs for controlling these devices. The information service unit 2012 uses information acquired from an external device via the communication module 2013 or the like to provide various multimedia information and multimedia services to the occupants of the vehicle 2001. The information service unit 2012 may include input devices (e.g., a keyboard, a mouse, a microphone, a switch, a button, a sensor, a touch panel, etc.) that accept input from the outside, and may also include output devices (e.g., a display, a speaker, an LED lamp, a touch panel, etc.) that perform output to the outside.

The driving assistance system unit 2030 is composed of various devices that provide functions for preventing accidents and reducing the driving burden on the driver, such as a millimeter wave radar, LiDAR (Light Detection and Ranging), a camera, a positioning locator (e.g., GNSS, etc.), map information (e.g., high definition (HD) maps, autonomous vehicle (AV) maps, etc.), a gyro system (e.g., IMU (Inertial Measurement Unit), INS (Inertial Navigation System), etc.), AI (Artificial Intelligence) chip, and AI processor, as well as one or more ECUs that control these devices. In addition, the driving assistance system unit 2030 transmits and receives various information via the communication module 2013 to realize driving assistance functions or autonomous driving functions.

The communication module 2013 can communicate with the microprocessor 2031 and components of the vehicle 2001 via the communication port. For example, the communication module 2013 transmits and receives data via the communication port 2033 between the drive unit 2002, steering unit 2003, accelerator pedal 2004, brake pedal 2005, shift lever 2006, front wheels 2007, rear wheels 2008, axle 2009, microprocessor 2031 and memory (ROM, RAM) 2032 in the electronic control unit 2010, and sensors 2021 to 29, which are provided in the vehicle 2001.

The communication module 2013 is a communication device that can be controlled by the microprocessor 2031 of the electronic control unit 2010 and can communicate with an external device. For example, it transmits and receives various information to and from the external device via wireless communication. The communication module 2013 may be located either inside or outside the electronic control unit 2010. The external device may be, for example, a base station, a mobile station, etc.

The communication module 2013 may transmit at least one of the signals from the various sensors 2021-2028 described above input to the electronic control unit 2010, information obtained based on the signals, and information based on input from the outside (user) obtained via the information service unit 2012 to an external device via wireless communication. The electronic control unit 2010, the various sensors 2021-2028, the information service unit 2012, etc. may be referred to as input units that accept input. For example, the PUSCH transmitted by the communication module 2013 may include information based on the above input.

The communication module 2013 receives various information (traffic information, signal information, vehicle distance information, etc.) transmitted from an external device, and displays it on the information service unit 2012 provided in the vehicle 2001. The information service unit 2012 may be called an output unit that outputs information (for example, outputs information to a device such as a display or speaker based on the PDSCH (or data/information decoded from the PDSCH) received by the communication module 2013). The communication module 2013 also stores various information received from an external device in a memory 2032 that can be used by the microprocessor 2031. Based on the information stored in the memory 2032, the microprocessor 2031 may control the drive unit 2002, steering unit 2003, accelerator pedal 2004, brake pedal 2005, shift lever 2006, front wheels 2007, rear wheels 2008, axles 2009, sensors 2021 to 2029, etc. provided in the vehicle 2001.

(Summary of the embodiment)
As described above, according to an embodiment of the present invention, a small base station in a first communication system is provided, comprising: a receiving unit that receives from a first network node a comparison table showing the correspondence between cell group identifiers in the first communication system and cell group identifiers in a second communication system and a list of cell group identifiers in the first communication system to which a terminal is permitted to access; a control unit that selects a destination small base station having the cell group identifier or a general destination base station based on the comparison table and the list when performing a handover to the second communication system; and a transmitting unit that transmits a message requesting a handover to the destination small base station or the destination base station via the first network node.

The above configuration makes it possible to execute handovers between HeNBs and HgNBs in a wireless communication system within the scope permitted by the subscriber information.

When executing a handover from the second communication system to the first communication system, the receiving unit may receive the list from the first network node, and the control unit may verify whether or not the handover can be executed by checking whether or not the list includes a cell group identifier of the own device.

The above configuration makes it possible to execute handovers between HeNBs and HgNBs in a wireless communication system within the scope permitted by the subscriber information.

The first communication system may be an Evolved Packet System (EPS) and the second communication system may be a 5G system (5GS), or the first communication system may be a 5GS and the second communication system may be an EPS.

The above configuration makes it possible to execute handovers between HeNBs and HgNBs in a wireless communication system within the scope permitted by the subscriber information.

In addition, according to an embodiment of the present invention, a network node is provided that has a receiver that receives an identifier of a destination small base station from a first network node and receives from a second network node a list of cell group identifiers in the second communication system to which the terminal is permitted to access in a handover procedure from a first communication system to a second communication system, a control unit that confirms that the terminal is able to handover to the destination small base station based on the identifier of the destination small base station, a comparison table showing the correspondence between the identifier of the destination small base station and the cell group identifiers in the second communication system held by the destination small base station, and the list, and a transmitter that transmits a message requesting handover to the destination small base station.

The above configuration makes it possible to execute handovers between HeNBs and HgNBs in a wireless communication system within the scope permitted by the subscriber information.

In addition, according to an embodiment of the present invention, a network node is provided that stores a first comparison table showing the correspondence between identifiers of small base stations and cell group identifiers in a first communication system, a second comparison table showing the correspondence between identifiers of small base stations and cell group identifiers in a second communication system, and a third comparison table showing the correspondence between cell group identifiers in the first communication system and cell group identifiers in the second communication system, and the network node has a receiver that receives a message including an identifier of a destination small base station in the second communication system from the small base station of the first communication system in a handover procedure from the first communication system to the second communication system, a control unit that determines the identifier of the small base station of the first communication system and confirms that handover to the destination small base station is possible based on the first comparison table, the second comparison table, and the third comparison table, and a transmitter that transmits a message to continue the handover procedure including the cell group identifier of the second communication system to the network node of the second communication system.

The above configuration makes it possible to execute handovers between HeNBs and HgNBs in a wireless communication system within the scope permitted by the subscriber information.

Also, according to an embodiment of the present invention, there is provided a communication method executed by a small base station in a first communication system, comprising the steps of receiving from a first network node a comparison table showing the correspondence between cell group identifiers in the first communication system and cell group identifiers in a second communication system, and a list of cell group identifiers in the first communication system to which a terminal is permitted to access, selecting a destination small base station having the cell group identifier or a general destination base station based on the comparison table and the list when performing a handover to the second communication system, and transmitting a message requesting a handover to the destination small base station or the destination base station via the first network node.

The above configuration makes it possible to execute handovers between HeNBs and HgNBs in a wireless communication system within the scope permitted by the subscriber information.

(Supplementary description of the embodiment)
Although the embodiment of the present invention has been described above, the disclosed invention is not limited to such an embodiment, and those skilled in the art will understand various modifications, modifications, alternatives, replacements, and the like. Although the description has been given using specific numerical examples to facilitate understanding of the invention, unless otherwise specified, those numerical values are merely examples and any appropriate value may be used. The division of items in the above description is not essential to the present invention, and items described in two or more items may be used in combination as necessary, and items described in one item may be applied to items described in another item (as long as there is no contradiction). The boundaries of functional units or processing units in the functional block diagram do not necessarily correspond to the boundaries of physical parts. The operations of multiple functional units may be physically performed by one part, or the operations of one functional unit may be physically performed by multiple parts. The order of the processing procedures described in the embodiment may be changed as long as there is no contradiction. For convenience of processing description, the base station 10 and the terminal 20 have been described using functional block diagrams, but such devices may be realized by hardware, software, or a combination thereof. The software operated by the processor possessed by the base station 10 in accordance with an embodiment of the present invention and the software operated by the processor possessed by the terminal 20 in accordance with an embodiment of the present invention may each be stored in random access memory (RAM), flash memory, read only memory (ROM), EPROM, EEPROM, register, hard disk (HDD), removable disk, CD-ROM, database, server or any other suitable storage medium.

Furthermore, the notification of information is not limited to the aspects/embodiments described in the present disclosure and may be performed using other methods. For example, the notification of information may be performed by physical layer signaling (e.g., Downlink Control Information (DCI), Uplink Control Information (UCI)), higher layer signaling (e.g., Radio Resource Control (RRC) signaling, Medium Access Control (MAC) signaling), broadcast information (Master Information Block (MIB), System Information Block (SIB)), other signals, or a combination of these. Furthermore, RRC signaling may be referred to as an RRC message, and may be, for example, an RRC Connection Setup message, an RRC Connection Reconfiguration message, etc.

Each aspect/embodiment described in this disclosure may be a mobile communication system (mobile communications system) for mobile communications over a wide range of networks, including LTE (Long Term Evolution), LTE-A (LTE-Advanced), SUPER 3G, IMT-Advanced, 4G (4th generation mobile communication system), 5G (5th generation mobile communication system), 6th generation mobile communication system (6G), xth generation mobile communication system (xG) (xG (x is, for example, an integer or a decimal number)), FRA (Future Radio Access), and LTE (LTE-Advanced). The present invention may be applied to at least one of the following systems using appropriate systems: IEEE 802.11 (Wi-Fi (registered trademark)), IEEE 802.16 (WiMAX (registered trademark)), IEEE 802.20, UWB (Ultra-Wide Band), Bluetooth (registered trademark), NR (new Radio Access), New radio access (NX), Future generation radio access (FX), W-CDMA (registered trademark), GSM (registered trademark), CDMA2000, UMB (Ultra Mobile Broadband), IEEE 802.11 (Wi-Fi (registered trademark)), IEEE 802.16 (WiMAX (registered trademark)), IEEE 802.20, UWB (Ultra-Wide Band), Bluetooth (registered trademark), and next-generation systems that are expanded, modified, created, or defined based on these. In addition, the present invention may be applied to a combination of multiple systems (for example, a combination of at least one of LTE and LTE-A with 5G, etc.).

The processing steps, sequences, flow charts, etc. of each aspect/embodiment described herein may be reordered unless inconsistent. For example, the methods described in this disclosure present elements of various steps using an exemplary order and are not limited to the particular order presented.

In this specification, certain operations that are described as being performed by the base station 10 may in some cases be performed by its upper node. In a network consisting of one or more network nodes having a base station 10, it is clear that various operations performed for communication with a terminal 20 may be performed by at least one of the base station 10 and other network nodes other than the base station 10 (such as, but not limited to, an MME or S-GW). Although the above example shows a case where there is one other network node other than the base station 10, the other network node may be a combination of multiple other network nodes (such as an MME and an S-GW).

The information or signals described in this disclosure may be output from a higher layer (or a lower layer) to a lower layer (or a higher layer). They may be input and output via multiple network nodes.

The input and output information may be stored in a specific location (e.g., memory) or may be managed using a management table. The input and output information may be overwritten, updated, or added to. The output information may be deleted. The input information may be sent to another device.

The determination in this disclosure may be based on a value represented by one bit (0 or 1), a Boolean (true or false) value, or a comparison of numerical values (e.g., a comparison with a predetermined value).

Software shall be construed broadly to mean instructions, instruction sets, code, code segments, program code, programs, subprograms, software modules, applications, software applications, software packages, routines, subroutines, objects, executable files, threads of execution, procedures, functions, etc., whether referred to as software, firmware, middleware, microcode, hardware description language, or otherwise.

Software, instructions, information, etc. may also be transmitted and received via a transmission medium. For example, if the software is transmitted from a website, server, or other remote source using at least one of wired technologies (such as coaxial cable, fiber optic cable, twisted pair, Digital Subscriber Line (DSL)), and/or wireless technologies (such as infrared, microwave), then at least one of these wired and wireless technologies is included within the definition of a transmission medium.

The information, signals, etc. described in this disclosure may be represented using any of a variety of different technologies. For example, the data, instructions, commands, information, signals, bits, symbols, chips, etc. that may be referred to throughout the above description may be represented by voltages, currents, electromagnetic waves, magnetic fields or magnetic particles, optical fields or photons, or any combination thereof.

Note that the terms explained in this disclosure and the terms necessary for understanding this disclosure may be replaced with terms having the same or similar meanings. For example, at least one of the channel and the symbol may be a signal (signaling). Also, the signal may be a message. Also, a component carrier (CC) may be called a carrier frequency, a cell, a frequency carrier, etc.

As used in this disclosure, the terms "system" and "network" are used interchangeably.

In addition, the information, parameters, etc. described in this disclosure may be represented using absolute values, may be represented using relative values from a predetermined value, or may be represented using other corresponding information. For example, radio resources may be indicated by an index.

The names used for the above-mentioned parameters are not limiting in any respect. Furthermore, the formulas etc. using these parameters may differ from those explicitly disclosed in this disclosure. The various channels (e.g., PUCCH, PDCCH, etc.) and information elements may be identified by any suitable names, and therefore the various names assigned to these various channels and information elements are not limiting in any respect.

In this disclosure, terms such as "base station (BS)", "wireless base station", "base station device", "fixed station", "NodeB", "eNodeB (eNB)", "gNodeB (gNB)", "access point", "transmission point", "reception point", "transmission/reception point", "cell", "sector", "cell group", "carrier", and "component carrier" may be used interchangeably. A base station may also be referred to by terms such as macrocell, small cell, femtocell, and picocell.

A base station can accommodate one or more (e.g., three) cells. When a base station accommodates multiple cells, the entire coverage area of the base station can be divided into multiple smaller areas, and each smaller area can also provide communication services by a base station subsystem (e.g., a small indoor base station (RRH: Remote Radio Head)). The term "cell" or "sector" refers to a part or the entire coverage area of at least one of the base station and base station subsystems that provide communication services in this coverage.

In this disclosure, a base station transmitting information to a terminal may be interpreted as the base station instructing the terminal to control or operate based on the information.

In this disclosure, terms such as "Mobile Station (MS)," "user terminal," "User Equipment (UE)," and "terminal" may be used interchangeably.

A mobile station may also be referred to by those skilled in the art as a subscriber station, mobile unit, subscriber unit, wireless unit, remote unit, mobile device, wireless device, wireless communication device, remote device, mobile subscriber station, access terminal, mobile terminal, wireless terminal, remote terminal, handset, user agent, mobile client, client, or some other suitable terminology.

At least one of the base station and the mobile station may be called a transmitting device, a receiving device, a communication device, etc. At least one of the base station and the mobile station may be a device mounted on a moving object, the moving object itself, etc. The moving object is a movable object, and the moving speed is arbitrary. It also includes the case where the moving object is stopped. The moving object includes, but is not limited to, for example, a vehicle, a transport vehicle, an automobile, a motorcycle, a bicycle, a connected car, an excavator, a bulldozer, a wheel loader, a dump truck, a forklift, a train, a bus, a handcar, a rickshaw, a ship and other watercraft, an airplane, a rocket, an artificial satellite, a drone (registered trademark), a multicopter, a quadcopter, a balloon, and objects mounted thereon. The moving object may also be a moving object that travels autonomously based on an operation command. It may be a vehicle (e.g., a car, an airplane, etc.), an unmanned moving object (e.g., a drone, an autonomous vehicle, etc.), or a robot (manned or unmanned). In addition, at least one of the base station and the mobile station may be a device that does not necessarily move during communication operations. For example, at least one of the base station and the mobile station may be an IoT (Internet of Things) device such as a sensor.

Furthermore, the base station in the present disclosure may be read as a user terminal. For example, each aspect/embodiment of the present disclosure may be applied to a configuration in which communication between a base station and a user terminal is replaced with communication between multiple terminals 20 (which may be called, for example, D2D (Device-to-Device) or V2X (Vehicle-to-Everything)). In this case, the terminal 20 may be configured to have the functions of the base station 10 described above. Furthermore, terms such as "uplink" and "downlink" may be read as terms corresponding to terminal-to-terminal communication (for example, "side"). For example, the uplink channel, downlink channel, etc. may be read as a side channel.

Similarly, the user terminal in this disclosure may be interpreted as a base station. In this case, the base station may be configured to have the functions of the user terminal described above.

As used in this disclosure, the terms "determining" and "determining" may encompass a wide variety of actions. "Determining" and "determining" may include, for example, judging, calculating, computing, processing, deriving, investigating, looking up, search, inquiry (e.g., searching in a table, database, or other data structure), and considering ascertaining as "judging" or "determining." Also, "determining" and "determining" may include receiving (e.g., receiving information), transmitting (e.g., sending information), input, output, accessing (e.g., accessing data in memory), and considering ascertaining as "judging" or "determining." Additionally, "judgment" and "decision" can include considering resolving, selecting, choosing, establishing, comparing, etc., to have been "judged" or "decided." In other words, "judgment" and "decision" can include considering some action to have been "judged" or "decided." Additionally, "judgment (decision)" can be interpreted as "assuming," "expecting," "considering," etc.

The terms "connected," "coupled," or any variation thereof, refer to any direct or indirect connection or coupling between two or more elements, and may include the presence of one or more intermediate elements between two elements that are "connected" or "coupled" to each other. The coupling or connection between elements may be physical, logical, or a combination thereof. For example, "connected" may be read as "access." As used in this disclosure, two elements may be considered to be "connected" or "coupled" to each other using at least one of one or more wires, cables, and printed electrical connections, as well as electromagnetic energy having wavelengths in the radio frequency range, microwave range, and optical (both visible and invisible) range, as some non-limiting and non-exhaustive examples.

The reference signal may also be abbreviated as RS (Reference Signal) or may be called a pilot depending on the applicable standard.

As used in this disclosure, the phrase "based on" does not mean "based only on," unless expressly stated otherwise. In other words, the phrase "based on" means both "based only on" and "based at least on."

Any reference to an element using a designation such as "first," "second," etc., used in this disclosure does not generally limit the quantity or order of those elements. These designations may be used in this disclosure as a convenient method of distinguishing between two or more elements. Thus, a reference to a first and a second element does not imply that only two elements may be employed or that the first element must precede the second element in some way.

The "means" in the configuration of each of the above devices may be replaced with "part," "circuit," "device," etc.

When the terms "include," "including," and variations thereof are used in this disclosure, these terms are intended to be inclusive, similar to the term "comprising." Additionally, the term "or," as used in this disclosure, is not intended to be an exclusive or.

In this disclosure, where articles have been added through translation, such as a, an, and the in English, this disclosure may include that the nouns following these articles are plural.

In this disclosure, the term "A and B are different" may mean "A and B are different from each other." The term may also mean "A and B are each different from C." Terms such as "separate" and "combined" may also be interpreted in the same way as "different."

Each aspect/embodiment described in this disclosure may be used alone, in combination, or switched depending on the execution. In addition, notification of specific information (e.g., notification that "X is the case") is not limited to being done explicitly, but may be done implicitly (e.g., not notifying the specific information).

　Although the present disclosure has been described in detail above, it is clear to those skilled in the art that the present disclosure is not limited to the embodiments described herein. The present disclosure can be implemented in modified and altered forms without departing from the spirit and scope of the present disclosure as defined by the claims. Therefore, the description of the present disclosure is intended to be illustrative and does not have any limiting meaning on the present disclosure.

10 Base station 110 Transmitter 120 Receiver 130 Setting unit 140 Control unit 20 Terminal 210 Transmitter 220 Receiver 230 Setting unit 240 Control unit 30 Network node 1001 Processor 1002 Memory device 1003 Auxiliary memory device 1004 Communication device 1005 Input device 1006 Output device 2001 Vehicle 2002 Drive unit 2003 Steering unit 2004 Accelerator pedal 2005 Brake pedal 2006 Shift lever 2007 Front wheel 2008 Rear wheel 2009 Axle 2010 Electronic control unit 2012 Information service unit 2013 Communication module 2021 Current sensor 2022 Rotational speed sensor 2023 Air pressure sensor 2024 Vehicle speed sensor 2025 Acceleration sensor 2026 Brake pedal sensor 2027 Shift lever sensor 2028 Object detection sensor 2029 Accelerator pedal sensor 2030 Driving support system unit 2031 Microprocessor 2032 Memory (ROM, RAM)
2033 Communication port (IO port)

Claims (6)

A small base station in a first communication system,
A receiver that receives from a first network node a correspondence table indicating a correspondence relationship between a cell group identifier in the first communication system and a cell group identifier in the second communication system, and a list of cell group identifiers in the first communication system to which a terminal is permitted to access;
A control unit that selects a destination small base station having the cell group identifier or a general destination base station based on the comparison table and the list when a handover to the second communication system is executed;
A transmitter that transmits a message requesting handover to the destination small base station or the destination base station via the first network node;
A small base station having When a handover is performed from the second communication system to the first communication system,
The receiver receives the list from the first network node;
The control unit verifies whether or not handover is executable by checking whether or not the list includes a cell group identifier of the own device.
The compact base station according to claim 1. The small base station according to claim 1, wherein the first communication system is an Evolved Packet System (EPS) and the second communication system is a 5G system (5GS), or the first communication system is a 5GS and the second communication system is an EPS. In a handover procedure from a first communication system to a second communication system,
A receiver that receives an identifier of a destination small base station from a first network node and receives a list of cell group identifiers in the second communication system to which the terminal is permitted to access from a second network node;
An identifier of the destination small base station;
A comparison table showing a correspondence relationship between the identifier of the destination small base station and a cell group identifier in the second communication system that the destination small base station has;
The list;
A control unit that confirms that the terminal is capable of handing over to the destination small base station based on the
A transmitter that transmits a message requesting handover to the destination small base station;
A network node having a A first comparison table showing a correspondence relationship between identifiers of small base stations and cell group identifiers in a first communication system;
A second comparison table showing a correspondence relationship between identifiers of small base stations and cell group identifiers in a second communication system;
a third lookup table indicating a correspondence relationship between a cell group identifier in the first communication system and a cell group identifier in the second communication system;
In a handover procedure from the first communication system to the second communication system,
A receiving unit that receives a message including an identifier of a destination small base station in the second communication system from a small base station of the first communication system;
A control unit that identifies an identifier of a small base station of the first communication system and confirms that handover to the destination small base station is possible based on the first lookup table, the second lookup table, and the third lookup table;
a transmitter for transmitting a message to a network node of the second communication system to continue the handover procedure, the message including a cell group identifier of the second communication system;
A network node having a A communication method executed by a small base station in a first communication system,
receiving from a first network node a lookup table indicating a correspondence between a cell group identifier in the first communication system and a cell group identifier in the second communication system, and a list of cell group identifiers in the first communication system to which a terminal is permitted to access;
When performing handover to the second communication system, selecting a destination small base station having the cell group identifier or a general destination base station based on the comparison table and the list;
Sending a message requesting handover to the destination small base station or the destination base station via the first network node;
A communication method comprising:

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