WO2023105572A1 - Base station device, wireless communication system, control method, and non-transitory computer-readable medium - Google Patents

Abstract

Provided are, for example, a base station device, a wireless communication system, and a control method that enable a terminal device to perform communication via an appropriate wireless network. According to the present invention, a PS-LTE system comprises an eNB (10) serving as a base station device, and a terminal device. The eNB (10) comprises: a detection unit (11) which detects a communication state between the eNB (10) and a core network; and a control unit (12) which controls selection of a wireless network by the terminal device, according to the communication state detected by the detection unit (11).

Description

Base station apparatus, wireless communication system, control method, and non-transitory computer-readable medium

The present invention relates to base station apparatuses, wireless communication systems, control methods, and non-transitory computer-readable media.

In recent years, PS-LTE (Public Safety-LTE), a dedicated LTE (Long Term Evolution) for public safety, has been introduced. PS-LTE is a wireless network shared by public safety organizations such as police, fire departments, and local governments. PS-LTE is sometimes called MCA (Multi Channel Access) Advanced. PS-LTE can provide a more stable service than general public networks in the event of a disaster or the like, and can reduce introduction costs because LTE is shared.

As a related technology, for example, Patent Document 1 is known. Patent Document 1 describes selecting a network selection parameter used by a terminal device based on a priority associated with an application or the like in a PS-LTE system.

WO2020/194940

As described above, the PS-LTE system makes it possible to provide stable services in the event of a disaster. For example, in the event of a disaster, communication failures may occur between the base station and the core network. However, related techniques do not take such situations into account, and there are cases where a terminal device cannot communicate via a wireless network such as a suitable base station or cell.

In view of such problems, the present disclosure provides a base station device, a wireless communication system, a control method, and a non-transitory computer-readable medium that enable terminal devices to communicate via an appropriate wireless network. for the purpose.

A base station apparatus according to the present disclosure includes detection means for detecting a communication state between the base station apparatus and a core network, and control for controlling selection of a wireless network by a terminal device according to the detected communication state. and means.

A wireless communication system according to the present disclosure includes a base station apparatus and a terminal apparatus, wherein the base station apparatus includes detection means for detecting a communication state between the base station apparatus and a core network; and control means for controlling selection of a wireless network by the terminal according to the state.

A control method according to the present disclosure is a control method in a base station apparatus, detecting a communication state between the base station apparatus and a core network, and controlling a radio network by a terminal apparatus according to the detected communication state. It controls the selection of

A non-transitory computer-readable medium storing a control program according to the present disclosure causes a computer in a base station device to detect a communication state between the base station device and a core network, It is a non-transitory computer-readable medium storing a control program for executing processing for controlling selection of a wireless network by a terminal device accordingly.

According to the present disclosure, it is possible to provide a base station device, a wireless communication system, a control method, and a non-transitory computer-readable medium that enable terminal devices to communicate via an appropriate wireless network.

1 is a diagram showing a schematic configuration of a PS-LTE system according to an embodiment; FIG. FIG. 4 is a diagram showing an example of communication during failure of the PS-LTE system according to the embodiment; FIG. 4 is a diagram showing an example of communication during failure of the PS-LTE system according to the embodiment; FIG. 2 is a diagram for explaining problems in a PS-LTE system before application of an embodiment; 1 is a diagram showing a schematic configuration of an eNB according to an embodiment; FIG. 1 is a diagram showing a configuration example of a PS-LTE system according to Embodiment 1; FIG. 2 is a diagram showing an operation example of the PS-LTE system according to Embodiment 1; FIG. 2 is a diagram showing an operation example of the PS-LTE system according to Embodiment 1; FIG. FIG. 8 is a diagram showing another operation example of the PS-LTE system according to Embodiment 1; FIG. 8 is a diagram showing another operation example of the PS-LTE system according to Embodiment 1; FIG. 2 is a diagram for explaining the effects of the PS-LTE system according to Embodiment 1; FIG. FIG. 2 is a diagram showing a configuration example of a PS-LTE system according to a modification of Embodiment 1; FIG. FIG. 10 is a diagram showing a configuration example of a PS-LTE system according to Embodiment 2; FIG. 10 is a diagram showing an operation example of the PS-LTE system according to Embodiment 2; FIG. 10 is a diagram showing an operation example of the PS-LTE system according to Embodiment 2; FIG. 10 is a diagram showing a configuration example of a PS-LTE system according to a modification of Embodiment 2; FIG. 10 is a diagram showing an operation example of a PS-LTE system according to a modification of Embodiment 2; FIG. 10 is a diagram showing an operation example of a PS-LTE system according to a modification of Embodiment 2; FIG. 10 is a diagram showing a configuration example of a PS-LTE system according to Embodiment 3; FIG. 10 is a diagram showing an operation example of the PS-LTE system according to Embodiment 3; FIG. 10 is a diagram showing an operation example of the PS-LTE system according to Embodiment 3; FIG. 10 is a diagram for explaining the effects of the PS-LTE system according to Embodiment 3; FIG. 10 is a diagram showing a configuration example of a PS-LTE system according to a modification of Embodiment 3; FIG. 12 is a diagram showing an operation example of a PS-LTE system according to a modification of Embodiment 3; FIG. 12 is a diagram showing an operation example of a PS-LTE system according to a modification of Embodiment 3; 1 is a configuration diagram showing an overview of hardware of a computer according to an embodiment; FIG.

Embodiments will be described below with reference to the drawings. In each drawing, the same elements are denoted by the same reference numerals, and redundant description will be omitted as necessary.

(Overview of Embodiment)
FIG. 1 shows a schematic configuration of a PS-LTE system 1 according to an embodiment. An LTE (PS-LTE) system will be described as an example of an embodiment, but the present invention may be applied to other wireless communication systems such as a 5G system or a hybrid system of LTE and 5G. For example, it may be applied as a method of controlling access of terminals in business wireless systems other than 3GPP-compliant systems such as LTE and 5G.

As shown in FIG. 1, the PS-LTE system 1 includes a base station eNB (evolved Node B: eNodeB) 10 ( eg 10A and 10B), terminals 20 such as smartphones (eg 20-1 and 20-2), It has an EPC (Evolved Packet Core) 30 which is a core network.

The eNB 10 is connected to the EPC 30 via the S1 interface. A connection via the S1 interface may be called an S1 connection. The terminal 20 wirelessly connects with the eNB 10 within the cell range of the eNB 10 and communicates with other terminals 20 via the EPC 30 . The EPC 30 enables mutual communication even between the terminals 20 that are connected to different eNBs 10 .

Furthermore, the PS-LTE system 1 is provided with local EPCs 40 (eg, 40A and 40B), unlike general LTE systems. The local EPC 40 is a smaller-scale core network device than the ECP 30 and is installed in the same office building as the eNB 10 .

　Figures 2 and 3 show an example of communication between terminals when a failure occurs between EPC and eNB in the PS-LTE system. As shown in FIG. 2, when the S1 connection between EPC 30 and eNB 10 (eg 10A) is broken, eNB 10 connects to local EPC 40 (eg 40A). This enables communication between the terminals 20 via the local EPC 40 within the same eNB area (cell). Note that it is also possible to directly perform LTE communication (LTE Direct/LTE D2D) between the terminals 20 .

Also, as shown in FIG. 3, a plurality of eNBs 10 (eg 10A-1 and 10A-2) may be connected to one local EPC 40 (eg 40A). In this case, when the S1 connection between the EPC 30 and the eNB 10 is disconnected, the terminals 20 can communicate with each other via the local EPC 40 within the area of the plurality of eNBs 10 to which the local EPC 40 is connected.

FIG. 4 shows problems in the PS-LTE system before the application of the embodiment. As shown in FIG. 4, before applying the embodiment, in a situation where the S1 connection between the EPC (eg, 930) and the eNB (eg, 910A and 910B) is broken, between the terminals (eg, 920-1 and 920-2) Communication may not be possible. Specifically, when terminal 920-1 connects to eNB 910A and terminal 920-2 determines that eNB 910B is a better connection destination than eNB 910A and connects to eNB 910B, the connection via EPC 930 is disconnected. Therefore, communication cannot be performed between terminals.

Terminal 920-1 and terminal 920-2 often exist in the area of eNB 910A, and even when the connection between EPC-eNB is disconnected, when it is required to communicate with terminal 920-1 and terminal 920-2 , terminal 920-2 should be controlled to select eNB 910A instead of selecting eNB 910B. Therefore, in the embodiment, in such a situation, the terminal selects an appropriate base station to enable communication between the terminals.

FIG. 5 shows a schematic configuration of the eNB 10 (base station device) according to the embodiment. As shown in FIG. 5 , the eNB 10 includes a detection section 11 and a control section 12 . The detection unit 11 detects the communication state of the S1 connection between the eNB 10 and the EPC 30 (core network).

The control unit 12 controls selection of a wireless network by the terminal 20 according to the detected communication state. A radio network is an accessed base station or cell in a radio access network. The control unit 12 may transmit control information for selecting a wireless network to the terminal 20 when the communication state of the S1 connection is disconnected or when the communication state of the S1 connection is recovered from disconnection. For example, the control information may be information indicating the communication state of the detected S1 connection, or information instructing switching of the wireless network selection method of the terminal. Also, the control information may be information indicating a wireless network accessible by the terminal 20 or priority information indicating the priority of the accessible wireless network. Furthermore, the control information may be call restriction information that restricts transmission of a specific terminal 20 .

Thus, in the embodiment, selection of a wireless network such as a base station or cell by a terminal is controlled based on the communication state of the S1 connection between the base station and the EPC. As a result, when the S1 connection is disconnected or restored after disconnection, the terminal can select an appropriate base station or cell to access the wireless network, enabling communication between the terminals.

(Embodiment 1)
Next, Embodiment 1 will be described. This embodiment will explain an example in which a terminal selects an eNB/cell based on eNB/cell priority information held in advance by the terminal.

<System configuration>
FIG. 6 shows a configuration example of the PS-LTE system 2 according to this embodiment. As shown in FIG. 6, PS-LTE system 2 includes eNB 100, terminal 200, EPC 300, and local EPC 400. FIG.

The EPC 300 constitutes the core network (device) of the LTE (PS-LTE) system. For example, the EPC 300 has core network functions such as MME (Mobility Management Entity), S-GW (Serving Gateway), P-GW (Packet Data Network Gateway), HSS (Home Subscriber Server), PCRF (Policy and Charging Rules Function) and so on. The MME accommodates control signals for the eNB 100 and performs mobility control for the terminal 200 . The S-GW accommodates user data signals of eNB 100 and transfers data packets to and from eNB 100 . The P-GW is connected to an external PDN (Packet Data Network), transfers data packets to and from the S-GW, and assigns an IP address to the terminal 200 . HSS manages subscriber information. The PCRF controls data transfer policies and billing. The EPC 300 may be composed of one device, may be composed of a plurality of arbitrary devices, or may be composed of virtualized devices.

Also, the EPC 300 may be connected to a PTT server for realizing a PTT call of the terminal 200 when the terminal 200 makes a PTT (Push-to-Talk) call, or the EPC 300 may have a PTT server function. good. The PTT server is a call control server such as a SIP (Session Initiation Protocol) server.

The local EPC 400 has core network functions similar to those of the EPC 300. Local EPC 400 is a local core network (device) that provides core network functions to eNB 100 when eNB 100 cannot communicate via EPC 300 . Like the EPC 300, the local EPC 400 may consist of one device, may consist of a plurality of arbitrary devices, or may consist of virtualized devices. Also, the local EPC 400 may be connected to a local PTT server, or the local EPC 400 may have a PTT server function.

The eNB 100 is a base station (device) of the LTE (PS-LTE) system and constitutes a radio access network (E-UTRAN: Evolved Universal Terrestrial Radio Access Network). The eNB 100 has a wireless communication function and necessary control functions as basic functions of a base station, and may be configured by one device or by arbitrary plural devices. For example, the eNB 100 is an arbitrary number of RRHs (Remote Radio Heads) that transmit and receive radio signals to and from the terminal 200, and BBUs (Base Band Units) that accommodate RRHs and perform baseband signal processing and interface processing with the core network. may include

In addition, the eNB 100 mainly includes a terminal communication unit 110, a core communication unit 120, a local core communication unit 130, a detection unit 140, and a notification unit 150 as necessary functions in this embodiment.

The terminal communication unit 110 is a wireless communication unit that performs wireless communication with the terminal 200 located within the eNB 100 cell (communication area). The terminal communication unit 110 is an LTE radio communication unit, and transmits and receives data and control signals to and from the terminal 200 using radio signals in a band allocated for PS-LTE, for example.

The core communication unit 120 is a backhaul communication unit that communicates with the EPC 300. The core communication unit 120 transmits and receives data and control signals to and from the EPC 300 via the S1 interface, which is a core network interface for backhaul (backhaul interface). Note that the S1 interface is an example of an interface for core connection, and may be connected via other interfaces (lines or transmission lines).

The local core communication unit 130 is a local backhaul communication unit that communicates with the local EPC 400. The local core communication unit 130 transmits and receives data and control signals to and from the local EPC 400 via the S1 interface, which is a core network interface for local backhaul (local backhaul interface). The S1 interface is an example of an interface for local core connection, and may be connected via other interfaces. In other words, the eNB 100 is connected to the EPC 300 via an S1 interface and is connected to the local EPC 400 via another S1 interface, but may be connected via different types of interfaces.

The detection unit 140 detects the communication state (connection state) of the S1 connection (backhaul connection) with the EPC 300 via the S1 interface. The detection unit 140 monitors the communication state of the S1 connection (backhaul line or backhaul link) by the core communication unit 120, and determines whether the S1 connection has been disconnected, or whether the S1 connection has been restored from disconnection. To detect. A disconnected (or disconnected) state is a state in which normal communication with the required quality cannot be performed, that is, a state of communication failure.

When the S1 connection with the EPC 300 is disconnected, the eNB 100 switches the connection of the core network from the EPC 300 to the local EPC 400. That is, the local core communication unit 130 establishes a connection with the local EPC 400 when the detecting unit 140 detects disconnection of the S1 connection with the EPC 300 . This enables communication between terminals in the cell by the local EPC 400 when a failure occurs in the S1 connection between the eNB 100 and the EPC 300 .

The notification unit (control unit) 150 notifies the communication state of the S1 connection with the EPC 300 detected by the detection unit 140 from the terminal communication unit 110 to the terminal 200 in the cell. For example, the notification unit 150 transmits (broadcasts) the communication state of S1 to all terminals 200 in the cell. When the disconnection of the S1 connection with the EPC 300 is detected, the notification unit 150 notifies the terminal 200 of the disconnection of the S1 connection (backhaul disconnection). Further, when recovery of the S1 connection with the EPC 300 is detected, the notification unit 150 notifies the terminal 200 of recovery of the S1 connection (backhaul recovery). The information indicating the disconnection or restoration of the S1 connection notified to the terminal 200 can be said to be information instructing the terminal to switch the eNB/cell selection method.

The terminal 200 is a user equipment (UE) of the LTE (PS-LTE) system. The terminal 200 may be a general-purpose terminal such as a smart phone or mobile phone, or may be a dedicated terminal such as a wireless device for business use. The terminal 200 makes a PTT call with the other terminal 200 as communication with the other terminal 200, for example. When the user presses the call button of the terminal 200, a call is made with another selected terminal 200 or a plurality of terminals 200 in the set group via the eNB and EPC (PTT server). Therefore, the terminal 200 has, as basic functions, a wireless communication function, a PTT call function, and the like. Note that the terminal 200 may perform arbitrary communication with other terminals 200 without being limited to the PTT call.

In addition, the terminal 200 mainly includes a communication unit 210, a priority holding unit 220, and a selection unit 230 as necessary functions in this embodiment. The communication unit 210 is a radio communication unit that performs radio communication with the eNB 100 within the cell of the eNB 100 . The communication unit 210 is an LTE radio communication unit, and transmits and receives data and control signals to and from the eNB 100 using radio signals in a band allocated for PS-LTE, for example.

The priority holding unit 220 presets and holds (stores) the priority information of the eNB/cell. The priority is the order of priority for selecting eNB 100 or cell (radio access network) to which terminal 200 connects (accesses). For example, the priority information is a list of priorities of eNB 100 or cells to which terminal 200 connects when backhaul connection failure of eNB 100 occurs, and includes priorities of a plurality of eNB 100 or cells to which terminal 200 can connect. The priority information may be information indicating the eNB 100 or the cell to which the terminal 200 should connect when the backhaul connection failure of the eNB 100 (information on eNB/cell with high priority).

It is preferable to set the same priority information between terminals that communicate (for example, PTT calls). For example, when group communication is performed between terminals 200 used by users belonging to the same organization such as a local government, the same priority list is set for the terminals 200 belonging to the same group. For example, in the case of the terminal 200 for a municipality in a specific prefecture, the priority information includes a list of priorities of the eNB 100 or cells in the prefecture and surrounding prefectures, and the priority of the eNB 100 or cells in the prefecture is higher than the priority of the cells in the prefecture. The priority of the eNB 100 or the cell is set higher.

The selection unit 230 selects the eNB 100 or cell to be connected based on the eNB/cell priority information held by the priority holding unit 220 . In this example, the selection unit 230 switches the eNB/cell selection method according to the communication state of the S1 connection notified from the eNB 100 . The selection method is a selection method based on the priority information of the eNB / cell (first selection method) and a selection method based on the received signal quality (electric field strength) of the signal received from the eNB / cell (second selection method). include. It should be noted that other selection methods may be used instead of the selection method based on the electric field intensity.

The selection unit 230 selects the eNB/cell based on the priority information when the disconnection of the S1 connection is notified from the eNB 100, and when the restoration of the S1 connection is notified from the eNB 100, the eNB/based on the electric field strength. Make a cell selection. In other words, when the S1 connection with the EPC 300 is disconnected, the eNB 100 notifies the terminal 200 of the disconnection of the S1 connection, thereby controlling the terminal 200 to select an eNB/cell based on the priority information, When the S1 connection with the EPC 300 is restored, it can be said that the terminal 200 is controlled to select an eNB/cell based on the electric field strength by notifying the terminal 200 of the restoration of the S1 connection.

When the selection unit 230 selects an eNB / cell based on the priority information, for example, the electric field strength is a threshold (a threshold such as RSRP (Reference Signal Received Power) held in advance by the terminal) eNB 100 that satisfies the priority may select and connect to the eNB 100 with the highest . Alternatively, the eNB 100 or cell with the highest priority may be selected in order and connection may be tried, and if the attach (registration) fails, the eNB 100 or cell with the next highest priority may be selected and connected.

<Action>
7 and 8 show an operation example of the PS-LTE system 2 according to this embodiment. For example, PS-LTE system 2 includes eNBs 100A and 100B, terminals 200A-1 and 200A-2, EPC 300, and local EPCs 400A and 400B. eNB 100A and eNB 100B connected to EPC 300 are adjacent to each other, and part of the cell of eNB 100A and part of the cell of eNB 100B overlap. Terminal 200A-1 is located within the cell of eNB 100A, and terminal 200A-2 is located near the boundary between the cell of eNB 100B and the cell of eNB 100A. The terminal 200A-1 and the terminal 200A-2 are terminals that communicate with each other (for example, terminals in the same group A). holds low priority information.

As shown in FIG. 7, the eNB 100 notifies the terminal 200 of the disconnection of the S1 connection between the eNB and the EPC when the S1 connection with the EPC 300 is disconnected. Upon receiving this notification, terminal 200 uses the priority information held in terminal 200 to switch to select an eNB/cell. Note that eNB 100 connects to local EPC 400 (switches connection to local EPC 400 ) when the S1 connection with EPC 300 is disconnected, and enables communication between accessed terminals 200 by local EPC 400 .

Specifically, when the S1 connection between the eNB 100A and the EPC 300 is disconnected, the eNB 100A notifies the terminal 200A-1 in the cell of the disconnection of the S1 connection (S101). When the terminal 200A-1 receives the disconnection notification of the S1 connection from the eNB 100B, it selects an eNB based on the priority information and connects to the eNB 100A with a higher priority (S102). In this example, the terminal 200A-1 is connected to the eNB 100A even when the eNB is selected based on the electric field strength, so the connection destination of the terminal 200A-1 does not change.

Also, when the S1 connection between the eNB 100B and the EPC 300 is disconnected, the eNB 100B notifies the terminal 200A-2 in the cell of the disconnection of the S1 connection (S103). When the terminal 200A-2 receives the S1 connection disconnection notification from the eNB 100B, the terminal 200A-2 selects an eNB based on the priority information and switches to connect to the eNB 100A with a higher priority (S104). In this example, the terminal 200A-2 is connected to the eNB 100B when the eNB is selected based on the electric field strength, but is connected to the eNB 100A by using the priority information. This allows the terminals 200A-1 and 200A-2 to communicate via the eNB 100A and the local EPC 400A.

As shown in FIG. 8, when the disconnection of the S1 connection between the eNB 100 and the EPC 300 is restored, the eNB 100 notifies the terminal 200 of information indicating that the S1 connection between the eNB and the EPC has been restored. When the terminal 200 receives this information, the terminal 200 stops the eNB/cell selection based on the priority information and changes to the normal eNB/cell selection based on the electric field strength or the like. When the S1 connection with EPC 300 is restored (when the connection is normal), eNB 100 switches the connection to EPC 300 and enables communication between accessed terminals 200 by EPC 300 .

Specifically, when the S1 connection between the eNB 100A and the EPC 300 is restored, the eNB 100A notifies the terminal 200A-1 in the cell of the restoration of the S1 connection (S111). When the terminal 200A-1 receives the S1 connection restoration notification from the eNB 100A, the terminal 200A-1 selects an eNB based on the electric field strength and continues to connect to the eNB 100A with the higher electric field strength (S112).

Also, when the S1 connection between the eNB 100B and the EPC 300 is restored, the eNB 100B notifies the terminal 200A-2 in the cell of the restoration of the S1 connection (S113). Upon receiving the S1 connection restoration notification from the eNB 100B, the terminal 200A-2 selects an eNB based on the electric field strength, and switches the connection to the eNB 100B with the higher electric field strength (S114). This enables the terminals 200A-1 and 200A-2 to communicate via eNB100A-EPC300-eNB100B.

9 and 10 show another operation example of the PS-LTE system 2 according to this embodiment. For example, PS-LTE system 2 includes eNBs 100A and 100B, terminals 200A-1 and 200A-2, terminals 200B-1 and 200B-2, EPC 300, and local EPCs 400A and 400B. Terminal 200A-1 is located within the cell of eNB 100A, and terminal 200A-2 is located near the boundary between the cell of eNB 100A and the cell of eNB 100B. The terminal 200B-2 is located within the cell of the eNB 100B, and the terminal 200B-1 is located near the boundary between the cell of the eNB 100B and the cell of the eNB 100A. The terminal 200A-1 and the terminal 200A-2 are terminals that communicate with each other (for example, terminals belonging to the same group A), and hold priority information indicating that the eNB 100A has a high priority and the eNB 100B has a low priority. The terminal 200B-1 and the terminal 200B-2 are terminals that communicate with each other (for example, terminals belonging to the same group B), and hold priority information indicating that the eNB 100B has a high priority and the eNB 100A has a low priority.

As shown in FIG. 9, when the S1 connection between eNB 100A and EPC 300 is disconnected, eNB 100A transmits information indicating that the S1 connection between eNB 100A and EPC 300 is disconnected to terminal 200A-1 and terminal 200A-2 in the cell. (S121). The terminal 200A-1 and the terminal 200A-2 that have received the information indicating that the S1 connection between the eNB 100A and the EPC 300 has been disconnected select an eNB/cell based on the eNB/cell priority information held by themselves, It connects to the eNB 100A with a higher priority (S122). In this example, the terminal 200A-1 is connected to the eNB 100A even when the eNB is selected based on the electric field strength, so the connection destination of the terminal 200A-1 does not change. The terminal 200A-2 is connected to the eNB 100B when the eNB is selected based on the electric field strength, but is connected to the eNB 100A by using the priority information. This allows the terminals 200A-1 and 200A-2 to communicate via the eNB 100A and the local EPC 400A. The same operation is performed when the terminal 200A-2 receives the S1 disconnection from the eNB 100B.

Similarly, when the S1 connection between the eNB 100B and the EPC 300 is disconnected, the eNB 100B notifies the terminal 200B-1 and the terminal 200B-2 in the cell of information indicating that the S1 connection between the eNB 100B and the EPC 300 is disconnected ( S123). The terminal 200B-1 and the terminal 200B-2 that have received the information indicating that the S1 connection between the eNB 100B and the EPC 300 has been disconnected select an eNB/cell based on the eNB/cell priority information held by themselves, It connects to the eNB 100B with a higher priority (S124). In this example, the terminal 200B-2 is connected to the eNB 100B even when the eNB is selected based on the electric field strength, so the connection destination of the terminal 200B-2 does not change. The terminal 200B-1 is connected to the eNB 100A when the eNB is selected based on the electric field strength, but is connected to the eNB 100B by using the priority information. This enables the terminals 200B-1 and 200B-2 to communicate via the eNB 100B and the local EPC 400B. The same operation is performed when the terminal 200B-1 receives the S1 disconnection from the eNB 100A.

As shown in FIG. 10, when the disconnection of the S1 connection between the eNB 100A and the EPC 300 is restored, the eNB 100A transmits information indicating that the S1 connection between the eNB 100A and the EPC 300 has been restored to the terminal 200A-1 and the terminal 200A in the cell. -2 (S131). The terminal 200A-1 and the terminal 200A-2 that have received the information indicating that the S1 connection between the eNB 100A and the EPC 300 has been restored select an eNB/cell based on the electric field strength without using the eNB/cell priority information. , to the eNB 100A or eNB 100B with a high electric field strength (S132). In this example, when the terminal 200A-1 receives the S1 connection recovery notification from the eNB 100A, the terminal 200A-1 continues to connect to the eNB 100A with the higher electric field strength. When the terminal 200A-2 receives the S1 connection restoration notification from the eNB 100A, the terminal 200A-2 switches the connection to the eNB 100B having a higher electric field strength. This enables the terminals 200A-1 and 200A-2 to communicate via eNB100A-EPC300-eNB100B.

Similarly, when the disconnection of the S1 connection between the eNB 100B and the EPC 300 is restored, the eNB 100B notifies the terminals 200B-1 and 200B-2 in the cell of information indicating that the S1 connection between the eNB 100B and the EPC 300 has been restored. (S133). The terminal 200B-1 and the terminal 200B-2 that have received the information indicating that the S1 connection between the eNB 100B and the EPC 300 has been restored select the eNB/cell based on the electric field strength without using the eNB/cell priority information. , to the eNB 100A or eNB 100B with a high electric field strength (S134). In this example, when the terminal 200B-2 receives the S1 connection recovery notification from the eNB 100B, the terminal 200B-2 continues to connect to the eNB 100B with the higher electric field strength. When the terminal 200B-2 receives the S1 connection restoration notification from the eNB 100B, the terminal 200B-2 switches the connection to the eNB 100A having a higher electric field strength. This enables the terminals 200B-1 and 200B-2 to communicate via eNB100A-EPC300-eNB100B.

<effect>
As described above, in the present embodiment, in the PS-LTE system, when the eNB disconnects the S1 connection with the EPC, the terminal is notified of the disconnection of the S1 connection, and the priority of the eNB / cell held by the terminal Select eNBs/cells to connect to based on the information. As a result, as shown in FIG. 11, terminals that are communication partners can appropriately connect to the same eNB based on the priority information, and can communicate with each other. For example, since terminals 200A-1 and 200A-2 using the same priority information are connected to eNB 100A, communication is possible by eNB 100A and local EPC 400A, and terminals 200B-1 and 200B-2 using the same priority information is connected to the eNB 100B, communication is enabled by the eNB 100B and the local EPC 400B. Therefore, even if the S1 connection between ECP and eNB is cut due to the occurrence of a large-scale disaster, communication between terminals is possible by determining in advance the eNB / cell to which the terminal preferentially connects. , eNB.

(Modification of Embodiment 1)
In Embodiment 1, the eNB notifies the terminal of the communication state of the S1 connection, but the terminal may detect the communication state of the S1 connection between the eNB and the EPC without being limited to the notification from the eNB.

<System configuration>
FIG. 12 shows a configuration example of a PS-LTE system 2 according to this modification. As shown in FIG. 12, in this example, terminal 200 further includes detection section 240 in contrast to the configuration of Embodiment 1. FIG. Note that in this example, the eNB 100 does not require the detection unit 140 and the notification unit 150 .

The detection unit 240 of the terminal 200 detects the communication state of the S1 connection (backhaul connection) between the eNB 100 and the EPC 300. The detection unit 240 detects the communication state of the S1 connection between the eNB 100 and the EPC 300 based on the IP address assigned to the terminal 200, for example. When the terminal 200 requests attachment (connection) via the eNB 100, an IP address is assigned by the EPC. The EPC 300 and the local EPC 400 have different IP address systems. Therefore, the terminal 200 can grasp that the core network connected to the eNB 100 has been switched from the EPC 300 to the local EPC 400 (or vice versa) based on the change in the address system of the assigned IP address. Disconnection/restoration of the S1 connection between the eNB 100 and the EPC 300 can be detected. If the address system of the assigned IP address changes, disconnection/restoration of the S1 connection may be detected, or the address system of the IP address assigned by the EPC (or the local EPC) may be stored, and the stored address system may be used. The comparison may detect disconnection/restoration of the S1 connection.

In this example, the selection unit 230 of the terminal 200 switches the eNB/cell selection method according to the communication state of the S1 connection detected by the detection unit 240 . Specifically, when the disconnection of the S1 connection between the eNB 100 and the EPC 300 is detected due to a change in the assigned IP address, the eNB/cell is selected based on the priority information, and the eNB 100 due to a change in the assigned IP address. eNB/cell selection based on field strength when detecting restoration of S1 connectivity between UE and EPC.

As a result, the terminal 200 can automatically select an appropriate eNB/cell without notifying the terminal of the communication status of the S1 connection from the eNB.

(Embodiment 2)
Next, Embodiment 2 will be described. In this embodiment, an example will be described in which a terminal selects an eNB/cell based on eNB/cell priority information notified to the terminal by an eNB.

<System configuration>
FIG. 13 shows a configuration example of the PS-LTE system 2 according to this embodiment. As shown in FIG. 13, in PS-LTE system 2 according to the present embodiment, eNB 100 further includes management unit 160 in contrast to the configuration of the first embodiment.

The management unit 160 manages (stores) priority information to be notified to the terminal 200 . As in the first embodiment, the priority information is, for example, a list of priorities of eNB 100 or cells to which terminal 200 connects when backhaul connection failure of eNB 100 occurs. The management unit 160 manages priority information for each terminal 200 . It is preferable to manage so that terminals communicating with each other or terminals performing group communication have the same priority information. The management unit 160 manages priority information used by all terminals 200 that may connect to the eNB 100 .

The management unit 160 may acquire priority information from the outside. Moreover, the management unit 160 may acquire information on terminals that communicate with each other and terminals that perform group communication from the outside. For example, when the PTT server (or other call control server) has information on terminals that perform group communication, the management unit 160 acquires information on terminals that perform group communication from the PTT server, thereby enabling You may manage the priority information of a terminal.

In this example, the notification unit 150 notifies the terminal 200 in the cell of priority information based on the communication state of the S1 connection with the EPC 300 detected by the detection unit 140 . The notification unit 150 individually notifies each terminal 200 of the priority information managed by the management unit 160 for each terminal 200 . Note that the priority information may be collectively notified to the terminals 200 in the same group (multicast or the like).

When the disconnection of the S1 connection with the EPC is detected, the notification unit 150 notifies the terminal 200 of the priority information of the corresponding terminal 200 . Moreover, the notification unit 150 notifies the terminal 200 of predetermined information when recovery of the S1 connection with the EPC 300 is detected. In this case, all eNBs/cells signal priority information with the same priority or information indicating deselection by priority. That is, the notification unit 150 notifies the terminal 200 of the priority information for the terminal 200 when the S1 connection with the EPC is disconnected, so that the terminal 200 selects the eNB/cell based on the priority information. When the S1 connection with the EPC 300 is restored, the terminal 200 is notified of priority information of the same priority or information indicating cancellation of selection by priority. Control eNB/cell selection based on field strength.

In addition, the terminal 200 includes a priority acquisition unit 250 instead of the priority holding unit 220 in contrast to the configuration of the first embodiment. The priority acquisition unit 250 acquires priority information notified from the eNB 100 via the communication unit 210 . In this example, the selection unit 230 selects an eNB/cell based on the priority information acquired by the priority acquisition unit 250 . It can be said that the eNB/cell selection method is switched according to the priority information notified from the eNB. For example, when priority information for the terminal 200 (priority information with different priority for each eNB) is notified from the eNB, the selection unit 230 selects the eNB/cell based on the notified priority information. When priority information of the same priority or information indicating cancellation of selection by priority is notified from the eNB, the eNB/cell is selected based on the electric field strength.

<Action>
14 and 15 show an operation example of the PS-LTE system 2 according to this embodiment. 14 and 15, for example, PS-LTE system 2 includes eNBs 100A and 100B, terminals 200A-1 and 200A-2, EPC 300, and local EPCs 400A and 400B, as in FIGS. Terminal 200A-1 is located within the cell of eNB 100A, and terminal 200A-2 is located near the boundary between the cell of eNB 100B and the cell of eNB 100A. eNB 100A and eNB 100B, as priority information to be transmitted to terminals 200A-1 and 200A-2, eNB 100A has a high priority (to be connected when the eNB has a backhaul connection failure), and eNB 100B has a low priority. is managing

As shown in FIG. 14, the eNB 100 notifies the terminal 200 of eNB/cell priority information when the S1 connection with the EPC 300 is disconnected. Terminal 200 connects to the eNB/cell with the best electric field strength until it receives notification of priority information, but when it receives notification of priority information, it connects to the eNB/cell based on the priority information.

Specifically, when the S1 connection between the eNB 100A and the EPC 300 is broken, the eNB 100A notifies the terminal 200A-1 in the cell of priority information for the terminal 200A-1 (S201). Upon receiving the priority information from eNB 100A, terminal 200A-1 selects an eNB based on the received priority information and connects to eNB 100A with a higher priority (S202). In this example, the terminal 200A-1 is connected to the eNB 100A even when the eNB is selected based on the electric field strength, so the connection destination of the terminal 200A-1 does not change.

Also, when the S1 connection between the eNB 100B and the EPC 300 is disconnected, the eNB 100B notifies the terminal 200A-2 in the cell of priority information for the terminal 200A-2 (S203). Upon receiving the priority information from the eNB 100B, the terminal 200A-2 selects an eNB based on the received priority information and switches to connect to the eNB 100A with a higher priority (S204). In this example, the terminal 200A-2 is connected to the eNB 100B when the eNB is selected based on the electric field strength, but is connected to the eNB 100A by using the priority information. This allows the terminals 200A-1 and 200A-2 to communicate via the eNB 100A and the local EPC 400A.

As shown in FIG. 15, when the S1 connection disconnection between the eNB 100 and the EPC is restored, the eNB 100 may notify the terminal 200 of priority information in which all eNBs/cells have the same priority, The terminal 200 may be notified of information that can control the terminal 200 so as not to follow the priority information.

Specifically, when the S1 connection between the eNB 100A and the EPC 300 is restored, the eNB 100A notifies the terminal 200A-1 in the cell of priority information of the same priority, for example (S211). Upon receiving the priority information from eNB 100A, terminal 200A-1 selects an eNB based on the received priority information, and continues to connect to eNB 100A with the same priority and high electric field strength (S212). Also, when the eNB 100A instructs the terminal 200A-1 not to follow the priority, the terminal 200A-1 selects an eNB based on the electric field strength without using the priority information, and continues to connect to the eNB 100A.

Also, when the S1 connection between the eNB 100B and the EPC 300 is restored, the eNB 100B notifies the terminal 200A-2 in the cell of priority information of the same priority, for example (S213). Upon receiving the priority information from the eNB 100B, the terminal 200A-2 selects an eNB based on the received priority information, and switches connection to the eNB 100B with the same priority and higher electric field strength (S214). Also, when the eNB 100B instructs the terminal 200A-2 not to follow the priority, the terminal 200A-2 selects an eNB based on the received electric field without using the priority information, and connects to the eNB 100B with the higher electric field strength. switch. This enables the terminals 200A-1 and 200A-2 to communicate via eNB100A-EPC300-eNB100B.

<effect>
As described above, in the present embodiment, in the PS-LTE system, when the eNB disconnects the S1 connection with the EPC, the eNB / cell priority information is notified to the terminal, and the priority information received by the terminal Select eNB/cell to connect based on As a result, as in Embodiment 1, the terminals that are communication partners can appropriately connect to the same eNB based on the priority information, and can communicate with each other.

(Modification of Embodiment 2)
In the second embodiment, the eNB that detects the disconnection of the S1 connection notifies the terminal of the priority information, but the eNB notifies the terminal of the priority information in response to an instruction from another device such as a system monitoring and control device. may

<System configuration>
FIG. 16 shows a configuration example of a PS-LTE system 2 according to this modification. As shown in FIG. 16, in this example, the PS-LTE system 2 has a system monitoring control device 500 in contrast to the configuration of the second embodiment.

The system monitoring control device 500 is a device that monitors and controls the PS-LTE system 2 as a whole. For example, the system monitoring control device 500 may be an EMS (Element Management System) that manages network equipment or an NMS (Network Management System) that manages a network.

The system monitoring control device 500 includes a monitoring section 510, a management section 520, and a control section 530. The monitoring unit 510 monitors the status of each device in the PS-LTE system 2, the connection status between devices, and the like. For example, the monitoring unit 510 monitors the communication status of the S1 connection (backhaul connection) between each eNB 100 and the EPC 300 .

The management unit 520 manages (stores) setting information and the like of each device in the PS-LTE system 2 . For example, the management unit 520 manages the priority information of the eNB 100 that the eNB 100 notifies the terminal 200 for each terminal 200 . The management unit 520 manages priority information used by terminals 200 that may connect to all eNBs 100 .

The control unit 530 controls the operation of each device in the PS-LTE system 2. Control unit 530 sets (instructs) priority information to other eNB 100 normally connected to EPC 300 according to the communication state of the S1 connection between eNB 100 and EPC 300 . Other eNBs 100 to be set are eNBs connected to the same EPC 300, adjacent to the eNB 100, and having cells partially overlapping. The other eNBs configured may be multiple eNBs. That is, when the S1 connection between the eNB 100 and the EPC 300 is disconnected, the control unit 530 sets the priority information for each terminal 200 managed by the management unit 520 to another eNB 100 that is normally connected to the EPC 300. eNB 100 to notify terminal 200 of priority information. For example, the control unit 530 may set priority information used by each terminal 200 connected (accommodated) to another eNB 100, or all terminals 200 that may be connected to another eNB 100 Priority information to be used may be set.

The notification unit 150 of the eNB 100 notifies the terminal 200 of the priority information acquired from the system monitoring control device 500 when the priority information is set (instructed) by the system monitoring control device 500 . That is, the notification unit 150 acquires the priority information of the terminal 200 according to the communication state between the EPC 300 and other eNBs 100 . Note that the notification unit 150 may notify the terminal 200 of the priority information managed by the eNB 100 when the S1 disconnection of another eNB 100 is notified from the system monitoring control device 500 .

<Action>
17 and 18 show an operation example of the PS-LTE system 2 according to this modification. As shown in FIG. 17 , when the S1 connection between the eNB 100A and the EPC 300 is broken and the eNB 100B overlapping the cell with the eNB 100A is normally connected to the EPC 300, the system monitoring control device 500 connected to the eNB 100B via the EPC 300 It automatically controls notification of priority information in the eNB 100B.

Specifically, the system monitoring and control device 500 monitors the connection status between the EPC 300 and the eNB 100A and eNB 100B, and when detecting disconnection of the S1 connection between the eNB 100A and the EPC 300, the connection between the eNB 100B and the EPC 300 If the S1 connection is established normally, priority information for terminal 200A-2 in the cell of eNB 100B is set (instructed) to eNB 100B via EPC 300 (S221). The eNB 100B notifies the terminal 200A-2 of the priority information for the terminal 200A-2 set by the system monitoring control device 500 (S222).

Further, as shown in FIG. 18, when the S1 connection between the eNB 100B and the EPC 300 is disconnected and the eNB 100A overlapping the cell with the NB 100B is normally connected to the EPC 300, the system monitoring control device that connects to the eNB 100A via the EPC 300 500 automatically controls notification of priority information in eNB 100A.

Specifically, the system monitoring and control device 500 monitors the connection status between the EPC 300 and the eNB 100A and the eNB 100B, and when detecting disconnection of the S1 connection between the eNB 100B and the EPC 300, If the S1 connection is established normally, priority information for terminal 200A-1 in the cell of eNB 100A is set (instructed) to eNB 100A via EPC 300 (S231). The eNB 100A notifies the terminal 200A-1 of the priority information for the terminal 200A-1 set by the system monitoring control device 500 (S232).

As a result, when the connection between the EPC and the eNB is disconnected and the EPC and another eNB are normally connected, the priority information can be notified to the terminal from the other eNB, and the terminal can be reliably enable communication between

(Embodiment 3)
Next, Embodiment 3 will be described. In this embodiment, an example of using call restriction, which is a function of LTE, will be described.

　3GPP stipulates Access Class Barring, which restricts wireless connections of terminals according to Access Class (AC) for each eNB, as a method of regulating terminal transmission. AC is a value stored in the terminal's USIM (Universal Subscriber Identity Module card). AC values are assigned from 0 to 9 for general terminals, 10 for emergency calls, and 11 to 15 for dedicated use (for example, 14 for police and fire departments, 13 for infrastructure operators such as gas and water). 12 for private security). For example, when radio resources of the eNB are expected to increase and congestion is expected, outgoing calls from the eNB are restricted for each AC. The eNB broadcasts the information of the AC to be restricted, and the terminal in which the corresponding AC is set suppresses the connection to the eNB. In this embodiment, this access class control is used to control the eNB/cell selected by the terminal.

<System configuration>
FIG. 19 shows a configuration example of the PS-LTE system 2 according to this embodiment. As shown in FIG. 19, in PS-LTE system 2 according to the present embodiment, eNB 100 is provided with call restriction section 170 instead of notification section 150 in the configurations of the first and second embodiments.

The call restriction unit (control unit) 170 notifies the terminal 200 in the cell of call restriction information based on the communication state of the S1 connection with the EPC 300 detected by the detection unit 140 . For example, the call restriction unit 170 transmits (broadcasts) the call restriction information to all the terminals 200 within the cell. The call restriction information is information for restricting (prohibiting) the call of a specific terminal 200 (access to an eNB/cell). It can be said that call restriction section 170 controls eNB/cell selection by terminal 200 by notifying terminal 200 of call restriction information. That is, by restricting connection to the eNB by a specific terminal using the call restriction information, the specific terminal is encouraged to connect to another eNB.

In this example, LTE access class control is used to restrict the transmission of terminal 200 as described above. The eNB 100 periodically notifies the terminal 200 of notification information SIB (System Information Block). When the disconnection of the S1 connection with the EPC 300 is detected, the call barring unit 170 sets the call barring information (AC-BarringInfo) of the notification information SIB2 so as to bar the call of the terminal 200 of a specific access class (AC). change. That is, the call restriction information is information indicating call restriction or call permission for the access class set in terminal 200 .

When the S1 connection is disconnected, the call regulation unit 170 notifies the AC of the specific terminal 200 that is not desired to be connected to its own eNB (is desired to be connected to another eNB) as call regulation information. The call restriction information (AC) to be notified may be set in advance or may be acquired from the outside. Further, when recovery of disconnection of S1 connection with EPC 300 is detected, call restriction information (AC- BarringInfo).

Note that the terminal 200 does not require the priority holding unit 220 and the priority acquisition unit 250 in contrast to the first and second embodiments. The terminal 200 is set with an access class to be used for the mounted USIM. The same access class is set in the USIMs of terminals that communicate with each other and terminals that perform group communication. Based on the call restriction information received from eNB 100 and the SIM access class, selection unit 230 determines whether or not call to eNB 100 is restricted, and selects an eNB/cell to be connected. The selection unit 230 does not select an eNB/cell whose call is restricted for its own access class, but selects an eNB/cell whose call is not restricted.

<Action>
20 and 21 show an operation example of the PS-LTE system 2 according to this embodiment. 20 and 21, as in FIGS. 9 and 10, for example, the PS-LTE system 2 includes eNBs 100A and 100B, terminals 200A-1 and 200A-2, terminals 200B-1 and 200B-2, EPC 300, local EPCs 400A and 400B are provided. Terminal 200A-1 is located within the cell of eNB 100A, and terminal 200A-2 is located near the boundary between the cell of eNB 100A and the cell of eNB 100B. The terminal 200B-2 is located within the cell of the eNB 100B, and the terminal 200B-1 is located near the boundary between the cell of the eNB 100B and the cell of the eNB 100A.

In this embodiment, when the S1 connection between the EPC-eNB is possible, call restriction is not performed, but when the connection between the EPC-eNB is broken, the connection destination of the terminal is controlled using the call restriction. Specifically, one of 11 to 15 is selected and set as the access class in USIM of the terminal 200 to be connected to the eNB 100 when the S1 connection between the EPC and the eNB is broken. Then, when the S1 connection between the EPC and the eNB is disconnected, the eNB 100 sets the access class in the USIM of a terminal that is not desired to be connected to the eNB 100 to the call restriction information and notifies it.

For example, set the USIM AC (access class) of the terminals 200A-1 and 200A-2 to be connected to the eNB 100A to 11, and set the USIM AC of the terminals 200B-1 and 200B-2 to be connected to the eNB 100B to 12. set to

As shown in FIG. 20, when the S1 connection between the eNB 100B and the EPC 300 is disconnected, the eNB 100B uses AC11 (for example, of the terminals 200A-1 and 200A-2) in the call barring information (AC-BarringInfo) notified by the broadcast information SIB2. AC11) is changed to regulation (barring: Bit string=10000) (S301). That is, the eNB 100B, triggered by the disconnection of the S1 connection between the eNB 100B and the EPC 300 and the switching of the S1 connection with the eNB 100B from the EPC 300 to the local EPC 400B, copies the call regulation information in the notification information SIB2 transmitted by the eNB 100B to all Change the terminal from permitted (Bit string 00000) to the terminal of AC11 that cannot be connected (Bit string 10000). As a result, the terminal set to AC11 does not connect to the eNB100B, that is, the terminal 200A-2 that receives the call restriction information (AC11) from the eNB100B does not connect to the eNB100B because the AC is set to 11. .

Also, when the S1 connection between the eNB 100A and the EPC 300 is disconnected, the eNB 100A includes AC12 other than AC11 (for example, the terminals 200B-1 and 200B-2) in the call barring information (AC-BarringInfo) notified by the notification information SIB2. ) to regulation (barring: Bit string01111) (S302). That is, the eNB 100A, triggered by the fact that the S1 connection between the eNB 100A and the EPC 300 is disconnected and the S1 connection with the eNB 100A is switched from the EPC 300 to the local EPC 400A, copies the call regulation information in the notification information SIB2 transmitted by the eNB 100A to all Change the terminal from permitted (Bit string 00000) to the terminal of AC12-15 that cannot be connected (Bit string 011111). As a result, terminals set to other than AC 11 are not connected to eNB 100A. That is, the terminal 200B-1 that has received the call restriction information (other than AC11) from the eNB 100A does not connect to the eNB 100A because AC is set to 12.

As a result, terminal 200A-2, which has received call restriction information from eNB 100A and eNB 100B, cannot make calls to eNB 100B but can make calls to eNB 100A. Since it is possible to make a call to eNB 100A, it connects to eNB 100A (S303). This allows the terminals 200A-1 and 200A-2 to communicate via the eNB 100A and the local EPC 400A. In addition, terminal 200B-1, which has received the call restriction information from eNB100A and eNB100B, cannot make a call to eNB100A but can make a call to eNB100B. Since it is possible to make a call to the eNB 100B (S304). This enables the terminals 200B-1 and 200B-2 to communicate via the eNB 100B and the local EPC 400B.

As shown in FIG. 21, when the EPC 300 is connected to the eNB 100, the transmission control information is set to allow connection of all terminals. Specifically, when the S1 connection between the eNB 100B and the EPC 300 is restored, the eNB 100B transmits the call barring information (AC-BarringInfo) in the notification information SIB2 transmitted by the eNB 100B to the AC 11 so that all terminals can connect. It changes from no connection (Bit string 10000) to all permission for AC 11-15 (not barring: Bit string 00000) (S311). As a result, the terminal set to AC11 becomes connectable to eNB100B.

Further, when the S1 connection between the eNB 100A and the EPC 300 is restored, the eNB 100A transmits the call barring information (AC-BarringInfo) in the notification information SIB2 transmitted by the eNB 100A so that all the terminals can connect to the terminals of the ACs 12-15. is changed from prohibiting connection (Bit string 011111) to permitting all of AC 11-15 (not barring: Bit string 00000) (S312). As a result, terminals set to other than AC 11 can be connected to eNB 100A.

As a result, the terminals 200A-1 and 200A-2 that have received the call restriction information (all permitted) are able to connect to all eNBs, and therefore connect to the eNB 100A or eNB 100B based on the electric field strength (S313). In this example, terminal 200A-1 connects to eNB 100A and terminal 200A-2 connects to eNB 100B. This enables the terminals 200A-1 and 200A-2 to communicate via eNB100A-EPC300-eNB100B.

Similarly, the terminals 200B-1 and 200B-2 that have received the call restriction information (all permitted) connect to the eNB 100A or eNB 100B based on the electric field strength, since they are now able to connect to all eNBs (S314). In this example, terminal 200B-1 connects to eNB 100A and terminal 200B-2 connects to eNB 100B. This enables the terminals 200B-1 and 200B-2 to communicate via eNB100A-EPC300-eNB100B.

<effect>
As described above, in the present embodiment, in the PS-LTE system, eNB regulates the transmission of a specific access class when the S1 connection with the EPC is disconnected, and the terminal is based on the restricted access class. Select the eNB/cell to connect to. As a result, as shown in FIG. 22, terminals set to the same access class can be appropriately connected to the same eNB and can communicate with each other. For example, since terminals 200A-1 and 200A-2 of the same access class are connected to eNB 100A, communication is enabled by eNB 100A and local EPC 400A, and terminals 200B-1 and 200B-2 of the same access class are connected to eNB 100B. Therefore, communication is possible by the eNB 100B and the local EPC 400B. Therefore, even if the S1 connection between the ECP and the eNB changes due to the occurrence of a large-scale disaster, etc., by changing the notification information related to the SIB2 transmission restriction sent by the eNB, the connection destination of the terminal By controlling the eNB that becomes the terminal, communication between terminals can be performed via the eNB.

(Modification of Embodiment 3)
In the third embodiment, the eNB that detects the disconnection of the S1 connection notifies the terminal of the call restriction information. may

<System configuration>
FIG. 23 shows a configuration example of a PS-LTE system 2 according to this modification. As shown in FIG. 23, in this example, the PS-LTE system 2 has a system monitoring control device 500 similar to that of the modified example of the second embodiment in contrast to the configuration of the third embodiment.

In this example, the management unit 520 of the system monitoring control device 500 manages notification information of the eNB 100. The management unit 520 manages call restriction information (AC) that the eNB 100 notifies to the terminal 200 for each eNB 100 .

The control unit 530 sets (instructs) call restriction information to the other eNB 100 normally connected to the EPC 300 according to the communication state of the S1 connection between the eNB 100 and the EPC 300 . That is, when the S1 connection between the eNB 100 and the EPC 300 is disconnected, the control unit 530 sets the call restriction information managed by the management unit 520 to the other eNB 100 normally connected to the EPC 300, and the other eNB 100 notifies control to change the transmission restriction information of the notification information to be sent.

When the call regulation information is set (instructed to change) by the system monitoring and control device 500, the call regulation unit 170 of the eNB 100 notifies the terminal 200 of notification information including the call regulation information acquired from the system monitoring and control device 500. . In other words, call restriction unit 170 acquires call restriction information according to the communication state between EPC 300 and other eNB 100 . Note that the call restriction unit 170 may notify the terminal 200 of predetermined call restriction information when the S1 disconnection of another eNB 100 is notified from the system monitoring control device 500 .

<Action>
24 and 25 show an operation example of the PS-LTE system 2 according to this modification. As shown in FIG. 24, when the S1 connection between the eNB 100A and the EPC 300 is broken and the eNB 100B in which the cell overlaps with the eNB 100A is connected to the EPC 300, the system monitoring control device 500 connected to the eNB 100B via the EPC 300 automatically , changes the broadcast information SIB2 in the eNB 100B.

Specifically, the system monitoring and control device 500 monitors the connection status between the EPC 300 and the eNB 100A and eNB 100B, and when detecting disconnection of the S1 connection between the eNB 100A and the EPC 300, the connection between the eNB 100B and the EPC 300 When the S1 connection is normally established, the eNB 100B is set (instructed) via the EPC 300 to transmit restriction information (for example, AC11 connection disabled: Bit string 10000) to be notified by the eNB 100B (S321). The eNB 100B sets the set call restriction information in the notification information SIB2, and notifies the terminal 200A-2 of it (S322).

As shown in FIG. 25 , when the S1 connection between the eNB 100B and the EPC 300 is disconnected and the eNB 100A overlapping the cell with the NB 100B is connected to the EPC 300, the system monitoring control device 500 connected to the eNB 100A via the EPC 300 automatically , changes the broadcast information SIB2 in the eNB 100A.

Specifically, the system monitoring and control device 500 monitors the connection status between the EPC 300 and the eNB 100A and the eNB 100B, and when detecting disconnection of the S1 connection between the eNB 100B and the EPC 300, When the S1 connection is normally connected, the eNB 100B is set (instructed) via the EPC 300 to transmit restriction information (for example, AC12-15 connection disabled: Bit string 011111) for notification by the eNB 100A (S331). The eNB 100A sets the set call restriction information in the notification information SIB2, and notifies the terminal 200A-1 of it (S332).

As a result, when the connection between the EPC and the eNB is broken and the EPC and another eNB are normally connected, the other eNB can notify the terminal of the call restriction information, and the terminal can reliably enable communication between

It should be noted that the present disclosure is not limited to the above embodiments, and can be modified as appropriate without departing from the scope.

Each configuration in the above-described embodiments is configured by hardware or software, or both, and may be configured from one piece of hardware or software, or may be configured from multiple pieces of hardware or software. Each device and each function (process) may be implemented by a computer 50 having a processor 51 such as a CPU (Central Processing Unit) and a memory 52 as a storage device, as shown in FIG. For example, a program for performing the method (control method) in the embodiment may be stored in the memory 52 and each function may be realized by executing the program stored in the memory 52 with the processor 51 .

These programs contain instructions (or software code) that, when read into a computer, cause the computer to perform one or more of the functions described in the embodiments. The program may be stored in a non-transitory computer-readable medium or tangible storage medium. By way of example, and not limitation, computer readable media or tangible storage media may include random-access memory (RAM), read-only memory (ROM), flash memory, solid-state drives (SSD) or other memory technology, CDs - ROM, digital versatile disc (DVD), Blu-ray disc or other optical disc storage, magnetic cassette, magnetic tape, magnetic disc storage or other magnetic storage device. The program may be transmitted on a transitory computer-readable medium or communication medium. By way of example, and not limitation, transitory computer readable media or communication media include electrical, optical, acoustic, or other forms of propagated signals.

Although the present disclosure has been described above with reference to the embodiments, the present disclosure is not limited to the above embodiments. Various changes that can be understood by those skilled in the art can be made to the configuration and details of the present disclosure within the scope of the present disclosure.

Some or all of the above-described embodiments can also be described in the following supplementary remarks, but are not limited to the following.
(Appendix 1)
A base station device,
detection means for detecting a communication state between the base station apparatus and a core network;
a control means for controlling selection of a wireless network by a terminal device according to the detected communication state;
A base station device.
(Appendix 2)
The selection of the wireless network is selection of a base station device or a cell to be accessed by the terminal device,
The base station device according to appendix 1.
(Appendix 3)
The control means transmits control information for selecting the wireless network to the terminal device when the communication state is disconnected or when the communication state is restored from the disconnection.
The base station apparatus according to appendix 1 or 2.
(Appendix 4)
The control information is information indicating the detected communication state,
The base station device according to appendix 3.
(Appendix 5)
The control information is information for instructing switching of the wireless network selection method of the terminal device,
The base station device according to appendix 3 or 4.
(Appendix 6)
The wireless network selection method includes a selection method based on the priority of the wireless network and a selection method based on received signal quality of a signal received from the wireless network.
The base station device according to appendix 5.
(Appendix 7)
The control means controls the terminal device to select the wireless network by the selection method based on the priority when the communication state is disconnected, and controls the terminal device when the communication state is restored from the disconnection. to select the wireless network by a selection method based on the received signal quality;
The base station device according to appendix 6.
(Appendix 8)
The control information is information indicating a wireless network accessible by the terminal device,
The base station device according to appendix 3.
(Appendix 9)
The control information is priority information indicating the priority of a wireless network accessible by the terminal device,
The base station device according to appendix 8.
(Appendix 10)
The priority information to be transmitted to the terminal device is the same as the priority information of another terminal device with which the terminal device communicates.
The base station device according to appendix 9.
(Appendix 11)
comprising management means for managing the priority information for each of the terminal devices;
The base station apparatus according to appendix 9 or 10.
(Appendix 12)
wherein the control means acquires priority information of the terminal device from a control device and transmits the acquired priority information to the terminal device;
The base station apparatus according to any one of appendices 9 to 11.
(Appendix 13)
The control device is a system monitoring control device for a system including the base station device and the core network,
The control means acquires priority information of the terminal device from the system monitoring and control device according to a communication state between the core network and another base station device.
The base station device according to supplementary note 12.
(Appendix 14)
The control information is call regulation information that regulates call origination of a specific terminal device,
The base station device according to appendix 3.
(Appendix 15)
the call restriction information indicates call restriction or call permission of the access class set in the terminal device;
14. The base station apparatus according to appendix 14.
(Appendix 16)
The access class set in the terminal device is the same as the access class set in another terminal device with which the terminal device communicates.
The base station device according to supplementary note 15.
(Appendix 17)
The control means transmits, to the terminal device, call restriction information for restricting transmission of the specific terminal device when the communication state is disconnected, and when the communication state is restored from the disconnection, all the terminal devices transmitting to the terminal device call restriction information that permits the call of
17. The base station apparatus according to any one of appendices 14 to 16.
(Appendix 18)
The control means acquires the call restriction information from a control device and transmits the acquired call restriction information to the terminal device.
18. The base station apparatus according to any one of appendices 14 to 17.
(Appendix 19)
The control device is a system monitoring control device for a system including the base station device and the core network,
The control means acquires the call restriction information from the system monitoring control device according to a communication state between the core network and another base station device.
18. The base station apparatus according to appendix 18.
(Appendix 20)
comprising a base station device and a terminal device,
The base station device
detection means for detecting a communication state between the base station apparatus and a core network;
a control means for controlling selection of a wireless network by a terminal device according to the detected communication state;
A wireless communication system comprising:
(Appendix 21)
A control method in a base station device,
detecting a communication state between the base station device and a core network;
controlling selection of a wireless network by a terminal device according to the detected communication state;
control method.
(Appendix 22)
to the computer in the base station equipment,
detecting a communication state between the base station device and a core network;
controlling selection of a wireless network by a terminal device according to the detected communication state;
Control program for executing processing.
(Appendix 23)
detection means for detecting a communication state between the base station device and the core network;
a control means for controlling selection of a wireless network according to the detected communication state;
A terminal device.
(Appendix 24)
A control method in a terminal device,
detecting a communication state between a base station device and a core network;
controlling selection of a wireless network according to the detected communication state;
control method.
(Appendix 25)
to the computer at the terminal,
detecting a communication state between a base station device and a core network;
controlling selection of a wireless network according to the detected communication state;
Control program for executing processing.
(Appendix 26)
A wireless communication system comprising a base station device and a terminal device,
detection means for detecting a communication state between the base station apparatus and a core network;
Control means for controlling selection of a wireless network by the terminal device according to the detected communication state;
A wireless communication system comprising:

1, 2 PS-LTE system 10 eNB
11 detection unit 12 control unit 20 terminal 30 EPC
40 Local EPC
50 computer 51 processor 52 memory 100 eNB
110 terminal communication unit 120 core communication unit 130 local core communication unit 140 detection unit 150 notification unit 160 management unit 170 call regulation unit 200 terminal 210 communication unit 220 priority holding unit 230 selection unit 240 detection unit 250 priority acquisition unit 300 EPC
400 Local EPC
500 system monitoring control device 510 monitoring unit 520 management unit 530 control unit

Claims (22)

1. A base station device,
   detection means for detecting a communication state between the base station apparatus and a core network;
   a control means for controlling selection of a wireless network by a terminal device according to the detected communication state;
   A base station device.
2. The selection of the wireless network is selection of a base station device or a cell to be accessed by the terminal device,
   The base station apparatus according to claim 1.
3. The control means transmits control information for selecting the wireless network to the terminal device when the communication state is disconnected or when the communication state is restored from the disconnection.
   The base station apparatus according to claim 1 or 2.
4. The control information is information indicating the detected communication state,
   The base station apparatus according to claim 3.
5. The control information is information for instructing switching of the wireless network selection method of the terminal device,
   The base station apparatus according to claim 3 or 4.
6. The wireless network selection method includes a selection method based on the priority of the wireless network and a selection method based on received signal quality of a signal received from the wireless network.
   The base station apparatus according to claim 5.
7. The control means controls the terminal device to select the wireless network by the selection method based on the priority when the communication state is disconnected, and controls the terminal device when the communication state is restored from the disconnection. to select the wireless network by a selection method based on the received signal quality;
   The base station apparatus according to claim 6.
8. The control information is information indicating a wireless network accessible by the terminal device,
   The base station apparatus according to claim 3.
9. The control information is priority information indicating the priority of a wireless network accessible by the terminal device,
   The base station apparatus according to claim 8.
10. The priority information to be transmitted to the terminal device is the same as the priority information of another terminal device with which the terminal device communicates.
    The base station apparatus according to claim 9.
11. comprising management means for managing the priority information for each of the terminal devices;
    The base station apparatus according to claim 9 or 10.
12. wherein the control means acquires priority information of the terminal device from a control device and transmits the acquired priority information to the terminal device;
    The base station apparatus according to any one of claims 9 to 11.
13. The control device is a system monitoring control device for a system including the base station device and the core network,
    The control means acquires priority information of the terminal device from the system monitoring and control device according to a communication state between the core network and another base station device.
    The base station apparatus according to claim 12.
14. The control information is call regulation information that regulates call origination of a specific terminal device,
    The base station apparatus according to claim 3.
15. the call restriction information indicates call restriction or call permission of the access class set in the terminal device;
    The base station apparatus according to claim 14.
16. The access class set in the terminal device is the same as the access class set in another terminal device with which the terminal device communicates.
    The base station apparatus according to claim 15.
17. The control means transmits, to the terminal device, call restriction information for restricting transmission of the specific terminal device when the communication state is disconnected, and when the communication state is restored from the disconnection, all the terminal devices transmitting to the terminal device call restriction information that permits the call of
    The base station apparatus according to any one of claims 14 to 16.
18. The control means acquires the call restriction information from a control device and transmits the acquired call restriction information to the terminal device.
    The base station apparatus according to any one of claims 14 to 17.
19. The control device is a system monitoring control device for a system including the base station device and the core network,
    The control means acquires the call restriction information from the system monitoring control device according to a communication state between the core network and another base station device.
    The base station apparatus according to claim 18.
20. comprising a base station device and a terminal device,
    The base station device
    detection means for detecting a communication state between the base station apparatus and a core network;
    a control means for controlling selection of a wireless network by a terminal device according to the detected communication state;
    A wireless communication system comprising:
21. A control method in a base station device,
    detecting a communication state between the base station device and a core network;
    controlling selection of a wireless network by a terminal device according to the detected communication state;
    control method.
22. to the computer in the base station equipment,
    detecting a communication state between the base station device and a core network;
    controlling selection of a wireless network by a terminal device according to the detected communication state;
    A non-transitory computer-readable medium storing a control program for executing processing.

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