Base station and mobile radio communication system

Abstract

To provide a base station and a mobile radio communication system, capable of securing communication continuity while keeping a function as much as possible even when a system fault occurs, by simplifying control of the base station.SOLUTION: A base station for transmitting a signal received from a connection destination via a communication channel to a mobile station via a radio channel comprises: a memory unit for storing an identifier of a connection destination to be connected via the communication channel; a communication unit for performing communication with only a connection destination to which the identifier stored in the memory unit is assigned; and a control unit capable of changing the identifier stored in the memory unit to another identifier. In the case that the identifier stored in the memory unit is a first identifier, the control unit, when receiving a connection request from a connection destination to which a second identifier differing from a first identifier is assigned, determines whether or not the connection request is a changeover connection request including a connection destination changeover request signal and changes the identifier stored in the memory unit to the second identifier when the connection request is the changeover connection request.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to, for example, a base station for a fire protection system and a mobile radio communication system including the same.

Background Art

[0002] Conventionally, as a fire protection system, there is known a mobile radio communication system including a communication command station that issues communication commands, a line control device that performs switching connection control of communication lines, and a plurality of base stations that perform radio communication control of a plurality of mobile stations under the control of this line control device. In this type of mobile radio communication system, due to the nature of the fire protection system, it is required that communication can be continued as much as possible even when a part of the system fails due to a disaster or the like.

[0003] For example, Patent Document 1 proposes a technique that enables communication between mobile stations within the communication area of a base station even when a failure of the line control device or a disconnection of the communication line occurs.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] In this type of mobile radio communication system, since the line control device controls the entire system, when the function of the line control device stops, a state occurs in which a radio call cannot be made between the command room and the mobile station. Therefore, in order to continue communication as much as possible, it is conceivable to design software that executes communication control of the base station so that it can be switched from the normal control mode executed when the line control device is normal to the degraded control mode that enables a call between the command room and the mobile station without passing through the line control device when the line control device fails.

[0006] However, designing a base station that has both a normal control mode and a degenerate control mode and can switch between them according to the situation has a problem of complicating the communication control of the base station. Generally, the more complicated the control is, the lower the reliability of the control tends to be. The fire protection system requires particularly high reliability due to the nature of the system. In addition, since the base station is often installed on the roof of a building or the top of a mountain, etc., the accessibility to the base station is poor, and every time a problem occurs, a great deal of labor and time are required for its repair work. Therefore, it is desirable that the control of the base station be a simple design with as low a risk of problems as possible.

[0007] In view of the above circumstances, an object of the present invention is to provide a base station and a mobile radio communication system that simplify the control of the base station, preserve functions as much as possible even when a system failure occurs, and ensure the continuity of communication.

Means for Solving the Problems

[0008] A base station according to one embodiment of the present invention is a base station that transmits a signal received from a connection destination via a communication line to a mobile station via a radio line, a memory unit that stores an identifier of a connection destination connected via the communication line, a communication unit that communicates only with a connection destination to which an identifier stored in the memory unit is assigned, and a control unit that can change an identifier stored in the memory unit to another identifier, wherein when there is a connection request from a connection destination to which a second identifier different from the first identifier is assigned when the identifier stored in the memory unit is the first identifier, the control unit determines whether the connection request is a switching connection request including a signal for switching the connection destination, and when the connection request is the switching connection request, changes the identifier stored in the memory unit to the second identifier.

[0009] Since the base station according to the present invention communicates only with a connection destination having the same identifier as the identifier stored in the memory unit, common communication control can be executed for normal control and degraded control only by controlling the identifier stored in the memory unit. This simplifies the control of the base station, and even when a system failure occurs, communication continuity can be ensured while retaining the functions as much as possible.

[0010] The communication line is typically an IP connection line, and the first identifier and the second identifier are IP addresses.

[0011] The first identifier may be an identifier assigned to a line control device that controls communication between the communication command station and the base station. The second identifier may be an identifier assigned to a remote control device that is an alternative device to the communication command station. This enables communication between the remote control device and the base station simply by changing the identifier stored in the memory unit even when the function of the line control device stops, thus ensuring communication continuity.

[0012] When the connection request from the connection destination assigned with the second identifier is the switching connection request, the control unit may give priority to communication with the connection destination assigned with the second identifier over communication with the connection destination assigned with the first identifier.

[0013] A mobile radio communication system according to an aspect of the present invention includes a base station connectable via a communication line to a communication command station or a remote control device, a line control device that controls communication between the communication command station and the remote control device and the base station, and a mobile station connectable to the base station via a radio line. The base station includes a memory unit that stores an identifier of a connection destination connected via the communication line, a communication unit that communicates only with a connection destination assigned with the identifier stored in the memory unit, a control unit that can change the identifier stored in the memory unit to another identifier. When the identifier stored in the memory unit is the first identifier assigned to the line control device and there is a connection request from the remote control device to which a second identifier different from the first identifier is assigned, the control unit determines whether the connection request is a switching connection request including a signal for switching the connection destination. When the connection request is the switching connection request, the control unit changes the identifier stored in the memory unit from the first identifier to the second identifier.

[0014] Since the mobile radio communication system according to the present invention communicates only with a connection destination having the same identifier as the identifier stored in the memory unit, only by controlling to change the identifier stored in the memory unit, from the normal control mode executed when the line control device is normal, it is possible to switch to the degraded control mode that enables a call between the communication command station and the mobile station without going through the line control device when the line control device fails.

[0015] The communication line is typically an IP connection line, and the first identifier and the second identifier are IP addresses.

[0016] When the identifier stored in the memory unit is the second identifier and there is a connection request from the line control device, the control unit determines whether the connection request is a switching connection request including a signal for switching the connection destination. When the connection request is the switching connection request, the control unit changes the identifier stored in the memory unit from the second identifier to the first identifier. Thereby, when the line control device recovers from the function stop state, the communication control of the base station can be easily switched from the degraded control mode to the normal control mode.

[0017] When the line control device receives a call signal and a monitor signal transmitted from the mobile station via the base station, the line control device may simultaneously transmit the call signal and the monitor signal to the communication command station. Since the monitor signal (the voice signal collected by the monitor device) contains multiple types of voice signals, its integration processing takes time. For example, in an IP connection line, a delay is likely to occur in the call signal. Therefore, by simultaneously outputting the call signal and the monitor signal from the line control device to the communication command console, the generation of voice echo at the command console can be prevented.

[0018] The line control device may execute a process of delaying the transmission of the call signal to the communication command console by a predetermined time.

Advantages of the Invention

[0019] According to the present invention, the control of the base station can be simplified, and even when a system failure occurs, the communication continuity can be ensured while retaining the functions as much as possible.

Brief Description of the Drawings

[0020]

Figure 1

Figure 2

Figure 3

Figure 4

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Figure 7

Figure 8

Figure 9

Embodiments for Carrying Out the Invention

[0021] Hereinafter, embodiments of the present invention will be described with reference to the drawings.

[0022] FIG. 1 is a schematic configuration diagram of a mobile wireless communication system 100 according to an embodiment of the present invention. In this embodiment, an application example to a fire emergency digital wireless communication system will be described.

[0023] [Overall Configuration] The mobile wireless communication system 100 of this embodiment includes a communication command station 1, a line control device 2, a base station 3, a mobile station 4, and a remote control device 5. The number of base stations 3 is typically plural, and each base station is connected to the line control device 2. Similarly, a plurality of mobile stations 4 are arranged within the communication area of each base station.

[0024] The communication command station 1, also referred to as a command system device, is connected to the line control device 2 and performs wireless communication with the mobile station 4 via the base station 3. The communication command station 1 is installed, for example, at a fire department headquarters or a fire station, and transmits command information to each mobile station 4 from the base station 3 via the line control device 2 and the base station 3. Also, the communication command station 1 receives communication information (voice information, monitor information) from the mobile station 4 via the base station 3 and the line control device 2.

[0025] The line control device 2 controls the communication between the communication command station 1 or the remote control device 5 and each base station 3. The line control device 6 is connected to the communication command station 1, the remote control device 5, and each base station 3 via a communication line 6. The communication line 6 is an IP connection line and includes an approach line (relay line) connecting between the line control device 2 and each base station 3, a communication cable, and various network devices for transferring data such as routers.

[0026] The base station 3 is a radio base station for communicating with a plurality of mobile stations 4 and is typically installed at a specific location (such as the premises of a fire station or the like). When the base station 3 receives command information from the communication command station 1 or the remote control device 5 via the communication line 6, it wirelessly transmits the command information regarding the fire emergency radio information to the mobile station 4 by the downlink radio wave C1. When the base station 3 receives the uplink radio wave C2 including the communication information from the mobile station 4, it transmits the communication information to the communication command station 1 or the remote control device 5 via the communication line 6.

[0027] The mobile station 4 is a radio station that operates while moving or stopped at an unspecified location and is an in-vehicle radio installed in an ambulance or a fire truck, or a portable radio carried by an emergency responder or a firefighter. The mobile station 4 transmits the uplink radio wave C2 for communicating with the communication command station 1 or the remote control device 5, for example, by a press operation.

[0028] In the fire emergency digital radio communication, a digital radio communication network used for commands from the communication command station 1 or the remote control device 5 to the mobile station 4, or reports from the mobile station 4 to the communication command station 1 or the remote control device 5, etc. is formed between the base station 3 and the mobile station 4. The radio frequency band used is, for example, the 260 MHz band. The communication information transmitted from the mobile station 4 is typically voice information, and in addition to this, data communication such as character information, position information, and support information is also possible. The voice information includes, in addition to the call signal, monitor signals captured by a camera, a microphone, etc. installed in the mobile station 4.

[0029] The remote control device 5 is a device for communicating with the base station 3 from another location away from the communication command station 1. The remote control device 5 functions as an alternative device to the communication command station 1 and is used, for example, when the communication command station 1 becomes inoperable due to a failure during the occurrence of a natural disaster such as an earthquake, to transmit command information to the mobile station 4 from a location away from the communication command station 1 or to receive communication information from the mobile station 4.

[0030] Generally, in this type of mobile radio communication system, since the line control device controls the entire system, when the function of the line control device stops, a state occurs where wireless communication cannot be performed between the command system and the mobile station. Therefore, in order to continue communication as much as possible, it is required to be designed so that it can be switched from the normal control mode executed when the line control device is normal to the degradation control mode that enables communication between the command system and the mobile station without passing through the line control device when the line control device fails.

[0031] Here, the command system corresponds to the communication command station 1 and the remote control device 5 in this embodiment. Also, the degradation control refers to an operation means for continuing communication with the mobile station 4 even in a state where the original functions and performance of the mobile radio communication system 100, such as a failure of the line control device 2, are partially stopped. The degradation control only needs to be able to execute the minimum necessary functions (for example, the call function with the mobile station 4), and other functions that can be executed when the line control device 2 is normal (for example, reception of the position information of the mobile station 4) may be partially restricted.

[0032] On the other hand, designing a base station with both a normal control mode and a degradation control mode and being able to switch between them according to the situation has the problem of causing the complication of the communication control of the base station. Generally, the more complicated the control is, the more likely the reliability of the control is to decrease. In particular, the fire protection system requires particularly high reliability due to the nature of the system. In addition, since the base station is often installed on the roof of a building or the top of a mountain, the accessibility to the base station is poor, and each time a malfunction occurs, a great deal of labor and time are required for its repair work. For this reason, it is desirable that the control of the base station has a simple design with as low a risk of malfunction as possible.

[0033] Therefore, in the mobile radio communication system of this embodiment, the base station 3 is configured so that communication continuity can be ensured while preserving functions as much as possible even when a system failure occurs. Hereinafter, the details of the base station 3 will be described.

[0034] [Details of the Base Station] FIG. 2 is a block diagram showing the configuration of the base station 3. As shown in the figure, the base station 3 includes a memory unit 31, an IF (interface) unit 32, a signal processing unit 33, a radio transceiver unit 34, and a base station control unit 35.

[0035] The memory unit 31 is a storage device such as a semiconductor memory or a hard disk drive. The memory unit 31 stores various programs executed by the IF unit 32, the signal processing unit 33, the radio transceiver unit 34, and the base station control unit 35.

[0036] The memory unit 31 stores the identifiers of the connection destinations connected via the communication line 6. In the present embodiment, as the identifiers of the connection destinations, one identifier pre-assigned to the line control device 2 and the remote control device 5 is stored. The identifier is not particularly limited as long as it is an identifier unique to the line control device 2 and the remote control device 5. For example, an identifier that can be transmitted over the communication line 6 such as an IP address or a MAC address is applicable. Note that the above identifiers may also be assigned to communication devices other than the line control device 2 and the remote control device 5, for example, the communication command station 1.

[0037] The IF unit 32 corresponds to a communication unit that communicates only with the connection destination to which the identifier stored in the memory unit 31 is assigned. The IF unit 32 may have a function as a monitoring unit that monitors the presence or absence of a failure in the communication line 6 between the IF unit 32 and the line control device 2. Note that the determination of the presence or absence of the failure may be performed by the base station control unit 35 based on the output from the IF unit 32.

[0038] The signal processing unit 33 performs baseband signal processing such as encoding of a command communication (transmission signal) from the communication command station 1 or the remote control device 5 to be transmitted to the mobile station 4, and decoding of a reception signal of the uplink radio wave C2 transmitted from the mobile station 4.

[0039] The radio transceiver unit 34 modulates and transmits the downlink radio wave C1 with a command communication (transmission signal) from the communication command station 1 or the remote control device 5, and demodulates the reception signal of the uplink radio wave C2 transmitted from the mobile station 4.

[0040] The base station control unit 35 comprehensively controls the operation of the base station 3 including the memory unit 31, the IF unit 32, the signal processing unit 33, and the radio transceiver unit 34. The base station control unit 35 can be realized by hardware elements used in a computer such as a CPU (Central Processing Unit), a RAM (Random Access Memory), a ROM (Read Only Memory), and necessary software.

[0041] The base station control unit 35 corresponds to the control unit of the present invention. When there is a connection request from a connection destination to which a second identifier different from the first identifier is assigned when the identifier stored in the memory unit 31 is the first identifier, the base station control unit 35 determines whether the connection request is a switching connection request including a signal for a switching request of the connection destination. Subsequently, when the connection request is a switching connection request, the base station control unit 35 changes the identifier stored in the memory unit 31 from the first identifier to the second identifier (for example, the second identifier is overwritten in the memory unit).

[0042] That is, the base station control unit 35 sets the identifier of the connection destination connected via the communication line 6 in the memory unit 31 and changes the identifier stored in the memory unit 31 to another identifier. In the present embodiment, when the line control device 2 is functioning normally, the base station control unit 35 sets the identifier (first identifier) of the line control device 2 in the memory unit 31. Thereby, the base station 3 executes a normal control mode in which it responds only to connection requests from the line control device 2 and does not respond to connection requests from other connection destinations (for example, the remote control device 5).

[0043] On the other hand, when the function of the line control device 2 stops due to a failure or the like, when the base station control unit 35 receives a switching connection request including a signal for a switching request of the connection destination from the remote control device 5, it changes the identifier stored in the memory unit 31 from the first identifier to the identifier (second identifier) of the remote control device 5. In this case, as shown in FIG. 3, the remote control device 5 performs a degraded operation in which it is connected to the base station 3 via the communication line 6 without going through the line control device 2.

[0044] Thus, since the base station 3 communicates only with a connection destination having the same identifier as the identifier stored in the memory unit 31, common communication control can be executed for both normal control and fallback control only by controlling the change of the identifier stored in the memory unit 31. This simplifies the control of the base station 3, and ensures the continuity of communication while preserving the functions as much as possible even when a system failure occurs.

[0045] [Operation of Mobile Radio Communication System] FIG. 4 and FIG. 5 are sequence diagrams for explaining an example of the operation of the mobile radio communication system 100.

[0046] When the line control device 2 is activated, an IP connection request including a signal for a switching request is transmitted from the line control device 2 to each base station 3 (ST101). Here, the IP connection request corresponds to a switching request for the connection destination to the base station 3. When the base station control unit 35 receives the IP connection request including the signal for the switching request from the line control device 2, it registers the identifier (the first identifier) assigned to the line control device 2 in the memory unit 31 and transmits an IP connection completion notification to the line control device 2 (ST102). Thereafter, the base station 3 communicates only with the line control device 2, which is the connection destination assigned the same identifier (the first identifier) as the identifier stored in the memory unit 31.

[0047] Subsequently, a predetermined startup sequence is executed in the line control device 2 and the base station 3 (ST103). This startup sequence process includes, for example, an instruction for the use band of the radio frequency for the base station 3.

[0048] In this state, in order to make a voice call from the remote control device 5 to the mobile station 4, the remote control device 5 can only transmit command information to the base station 3 via the line control device 2. In this case, the remote control device 5 transmits command information to the line control device (ST104), and the line control device 2 transmits a connection request to the base station 3 (ST105). The connection request is a notification requesting permission for communication with the base station 3. Since the identifier of the transmission source of the connection request matches the identifier (first identifier) stored in the memory unit 31, the base station control unit 35 notifies the line control device 2 of a connection response permitting the connection request (ST106). Thereby, the normal control mode for making a voice call between the remote control device 5 and the mobile station 4 via the line control device 2 is executed (see Case 1 in FIG. 4).

[0049] Note that in this normal control mode, similarly, even when command information is transmitted from the communication command console 1 to the line control device 2 instead of the remote control device 3, a voice call is made between the communication command console 1 and the mobile station 4 via the line control device 2.

[0050] On the other hand, when the remote control device 5 makes a direct connection request to the base station 3 without going through the line control device 2 (ST107), the base station control unit 35 ignores the connection request because the identifier (second identifier) of the transmission source of the connection request is different from the identifier (first identifier) stored in the memory unit 31. At this time, since no connection response is notified from the base station 3 to the remote control device 5, a voice call cannot be made between the remote control device 5 and the mobile station 4 (see Case 2 in FIG. 4).

[0051] Subsequently, an example of the operation of the mobile radio communication system 100 when the function of the line control device 2 stops will be described with reference to FIG. 5.

[0052] When the line control device 2 stops functioning due to some kind of failure, a fallback operation is performed in the remote control device 5 to communicate with the base station 3 without going through the line control device 2. In this case, an IP connection request including a switching request signal is notified from the remote control device 5 to the base station 3 (ST201). When the base station control unit 35 receives an IP connection request including a switching request signal from the remote control device 5, it changes the identifier (the first identifier) stored in the memory unit 31 to the second identifier assigned to the remote control device 5, and transmits an IP connection completion notification to the remote control device 5 (ST202). Thereafter, the base station 3 communicates only with the remote control device 5, which is the connection destination assigned the same identifier (the second identifier) as the identifier stored in the memory unit 31. Subsequently, a predetermined startup sequence is executed in the remote control device 5 and the base station 3 (ST203).

[0053] In this way, when the connection request from the connection destination (remote control device 5) assigned the second identifier is a switching connection request, the base station control unit 35 disconnects the communication with the connection destination (line control device 2) assigned the first identifier and connects to the connection destination assigned the second identifier, and executes so-called post-priority processing.

[0054] When the communication between the remote control device 5 and the base station 3 is established, the remote control device 5 transmits a connection request to the base station 3 (ST204). Since the identifier of the transmission source of the connection request matches the identifier (the second identifier) stored in the memory unit 31, the base station control unit 35 notifies a connection response permitting the connection request to the remote control device 5 (ST205). Thereby, the communication control of the base station 3 is switched from the normal control mode to the fallback control mode in which a voice call is made between the remote control device 5 and the mobile station 4 without going through the line control device 2 (see Case 3 in FIG. 4).

[0055] When the failure of the line control device 2 is recovered and it restarts, the same processing as ST101 to 103 in FIG. 4 described above is executed. That is, when the line control device 2 restarts, an IP connection request including a switching request signal from the line control device 2 to the base station 3 is notified, and the base station control unit 35 changes the identifier (second identifier) stored in the memory unit 31 to the first identifier assigned to the line control device 2 (post-priority processing). As a result, the communication control of the base station 3 is switched from the degraded control mode to the normal control mode.

[0056] As described above, according to the present embodiment, since the base station 3 communicates only with a connection destination having the same identifier as the identifier stored in the memory unit 31, common communication control can be executed in both the normal control and the degraded control only by controlling the change of the identifier stored in the memory unit 31. This simplifies the control of the base station 3 and can ensure the continuity of communication while retaining the functions as much as possible even when a system failure occurs.

[0057] [Details of the Line Control Device] Subsequently, the details of the line control device 2 will be described.

[0058] As shown in FIG. 6, the line control device 2 of the present embodiment includes an audio signal processing unit 21 and an IF connection unit 22.

[0059] (Audio Signal Processing Unit) The audio signal processing unit 21 is for processing the audio signal from the mobile station 4 received via the base station 3.

[0060] The voice information transmitted from the mobile station 4 to the communication command station 1 and the remote control device 5 includes the call voice (call signal) transmitted through the receiver and the monitor voice (monitor signal) transmitted through the monitor device. The call voice and the monitor voice are basically the same voice, and since the monitor voice also captures the ambient environmental sound at the same time, the amount of information in the monitor signal is larger than that of the call signal. As shown in FIG. 7, the communication command station 1 is separately provided with a reproducing device for the call signal and a reproducing device for the monitor signal. The remote control device 5 is equipped with, for example, a reproducing device for the monitor signal.

[0061] Here, when an IP connection line is adopted for the communication line 6, a delay is likely to occur in the signal processing of the monitor signal rather than the call signal due to jitter buffer absorption processing and the like executed at the base station 3. Therefore, since a time difference also occurs between the call signal and the monitor signal transmitted from the base station 3 to the line control device 2, if the monitor signal is transmitted to the communication command station 1 from the line control device 2 with a delay relative to the call signal, an echo may occur between the call voice and the monitor voice reproduced at the communication command station 1, and the voice content may not be accurately heard.

[0062] Therefore, when the voice signal processing unit 21 receives the call signal and the monitor signal transmitted from a plurality of mobile stations 4 via the base station 3, the voice signal processing unit 21 simultaneously transmits the call signal and the monitor signal to the communication command station 1. Thereby, the generation of an echo between the call voice and the monitor voice at the communication command station 1 can be suppressed, and the voice content can be accurately and easily heard.

[0063] The voice signal processing unit 21 adjusts the transmission timing of the call signal to the communication command station 1 in accordance with the time until the monitor signal reaches the line control device 2. For example, the voice signal processing unit 21 waits for the transmission of the call signal until the monitor signal arrives. In this case, the voice signal processing unit 21 may include a delay circuit that executes a process of delaying the transmission of the call signal to the communication command station 1 by a predetermined time. The predetermined time is, for example, 10 milliseconds to 100 milliseconds, and can be arbitrarily set according to the time difference in the transmission processing between the call signal and the monitor signal.

[0064] (IF connection section) The IF connection section 22 is for connecting the interface (IF) between the command system (communication command console 1 and remote control device 5) and the base station 3.

[0065] The line control device 2 needs to support multiple interfaces due to differences in the specifications of the command system and base station, as well as customer needs. For example, as shown in FIG. 8, in order to interconnect three types of interfaces A, B, and C on the command system side and two types of interfaces D and E on the base station side, it is conceivable to construct a program that realizes six types of connection processes 1 to 6 corresponding to each combination. However, such a method leads to an increase in the development volume and complexity of the system. Also, if a problem occurs in one connection, it may also cause problems that affect other connections.

[0066] To solve this problem, in this embodiment, as shown in FIG. 9, the IF connection section 22 has a program structure divided into IF conversion sections 22A, 22B and a common processing section 22C. The IF conversion section 22A converts each signal input to the interfaces A to C into a signal that can be processed by the common processing section 22C and inputs it to the common processing section 22C. The IF conversion section 22B converts each signal input to the interfaces D and E into a signal that can be processed by the common processing section 22C and inputs it to the common processing section 22C. The common processing section 22C executes processing according to the input signal.

[0067] By adopting such a program structure that divides the IF connection unit 22 into the IF conversion units 22A and 22B and the common processing unit 22C, the development for each interface can be minimized, and the program structure can be simplified. Also, since the number of types of processing in the common processing unit 22C is reduced, the processing of the common processing unit 22C itself becomes simple, and the reliability of the common processing unit 22C is improved. That is, each of the IF conversion units 22A and 22B is specialized in converting the input signal into a common event signal, and the common processing unit 22C can perform processing only according to the common event signal regardless of the interface. Therefore, the processing load on the common processing unit 22C is reduced, and thereby the reliability is improved. Moreover, even if a problem occurs, since the structure is simple, the location of the correction is easy to find, and the range of the correction can be limited. Furthermore, by adopting the IF connection unit 22, the delay processing of the call signal by the above-described voice signal processing unit 21 can be easily realized even in communication between different interfaces.

Explanation of Signs

[0068] 1…Communication command station 2…Line control device 3…Base station 4…Mobile station 5…Remote control device 6…Communication line 21…Voice signal processing unit 22…IF connection unit 31…Memory unit 35…Base station control unit 100…Mobile radio communication system

Claims

1. A base station that transmits a signal received from a connection destination via a communication line to a mobile station via a wireless line, a memory unit that stores an identifier of a connection destination connected via the communication line; a communication unit that communicates only with a connection destination to which the identifier stored in the memory unit is assigned; a control unit that can change the identifier stored in the memory unit to another identifier, and when a connection request from a connection destination to which a second identifier different from the first identifier is assigned occurs when the identifier stored in the memory unit is the first identifier, the control unit determines whether the connection request is a switching connection request including a signal for switching the connection destination, and when the connection request is the switching connection request, changes the identifier stored in the memory unit to the second identifier Base station.

2. The base station according to claim 1, wherein the communication line is an IP connection line, and the first identifier and the second identifier are IP addresses Base station.

3. The base station according to claim 1, wherein the first identifier is an identifier assigned to a line control device that controls communication between a communication command station and the base station, and the second identifier is an identifier assigned to a remote control device that is an alternative device of the communication command station Base station.

4. The base station according to any one of claims 1 to 3, wherein when the connection request from the connection destination to which the second identifier is assigned is the switching connection request, the control unit gives priority to communication with the connection destination to which the second identifier is assigned over communication with the connection destination to which the first identifier is assigned Base station.

5. A base station capable of being connected via a communication line to a communication command station or a remote control device, a line control device that controls communication between the communication command station and the remote control device and the base station, and a mobile station capable of being connected to the base station via a wireless line, wherein the base station has a memory unit that stores an identifier of a connection destination connected via the communication line, a communication unit that communicates only with a connection destination to which the identifier stored in the memory unit is assigned, and a control unit that can change the identifier stored in the memory unit to another identifier When a connection request from the remote control device assigned with a second identifier different from the first identifier is received while the identifier stored in the memory unit is the first identifier assigned to the line control device, the control unit determines whether the connection request is a switching connection request including a signal for switching the connection destination. When the connection request is the switching connection request, the control unit changes the identifier stored in the memory unit from the first identifier to the second identifier. Mobile radio communication system.

6. The mobile radio communication system according to claim 5, wherein the communication line is an IP connection line, and the first identifier and the second identifier are IP addresses. Mobile radio communication system.

7. The mobile radio communication system according to claim 5, wherein when a connection request from the line control device is received while the identifier stored in the memory unit is the second identifier, the control unit determines whether the connection request is a switching connection request including a signal for switching the connection destination. When the connection request is the switching connection request, the control unit changes the identifier stored in the memory unit from the second identifier to the first identifier. Mobile radio communication system.

8. The mobile radio communication system according to claim 5, wherein when the line control device receives a call signal and a monitor signal transmitted from the mobile station via the base station, the line control device simultaneously transmits the call signal and the monitor signal to the communication command station. Mobile radio communication system.

9. The mobile radio communication system according to claim 8, wherein the line control device executes a process of delaying the transmission of the call signal to the communication command station by a predetermined time. Mobile radio communication system.

Images