Mobile radio communication system, and a line control device and base station for said mobile radio communication system.

Abstract

To perform appropriate return transmission in each base station even when a failure occurs on a communication line.SOLUTION: A mobile radio communication system according to an embodiment of the present invention includes a plurality of base stations, a line control apparatus, and a plurality of mobile stations. Each of the base stations has: a first communication mode which transmits receiving signals from a communication command center to the mobile stations; a second communication mode which executes return transmission to transmit receiving radio waves from one mobile station to another mobile station on the basis of a control command from the line control apparatus; and a third communication mode which executes the return transmission autonomously only when receiving radio waves from a specific mobile station allocated in advance for each base station. The line control apparatus causes other base stations to execute the third communication mode when a failure occurs in a communication line with at least one of the multiple base stations.SELECTED DRAWING: Figure 4

Description

Technical Field

[0001] The present invention relates to a mobile wireless communication system that communicates between a plurality of mobile stations and a communication command station, and a line control device and a base station for the mobile wireless communication system.

Background Art

[0002] Conventionally, a mobile wireless communication system including a communication command station that issues communication commands, a line control device that performs switching connection control of a communication line, and a plurality of base stations that perform wireless communication control of a plurality of mobile stations under the control of this line control device is known (see, for example, Patent Document 1).

[0003] Also, when communication with the line control device is interrupted, a technique is known in which each base station performs loopback transmission that transmits received radio waves from one mobile station to other mobile stations, enabling communication between mobile stations existing within the communication area of each base station (see, for example, Patent Document 2).

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0005] Since loopback transmission by base stations is inherently controlled by a line control device that monitors and controls the communication line, if a failure (line anomaly) occurs in the communication line between the communication command center and the base station, proper loopback transmission may not be possible at each base station. To address this, one could consider, for example, having the base station experiencing the line failure perform loopback transmission according to predetermined conditions. However, in such a case, when a base station with a normal line receives a command from the line control device and performs loopback transmission, the base station with the line failure will perform loopback transmission independently of the line control device's control. As a result, the radio waves transmitted by these multiple base stations may interfere with each other, potentially preventing communication between mobile stations.

[0006] In view of the above circumstances, the object of the present invention is to provide a mobile radio communication system that can achieve proper loopback transmission at each base station even when a communication line failure occurs, as well as a line control device and base station for said mobile radio communication system. [Means for solving the problem]

[0007] A mobile radio communication system according to one embodiment of the present invention comprises a communication command center and a plurality of base stations connected via a communication line, a line control device that controls communication between the communication command center and the plurality of base stations, and a plurality of mobile stations that can be connected to the plurality of base stations via a radio line. The plurality of base stations have a first communication mode, a second communication mode, and a third communication mode. The first communication mode transmits received signals from the communication command center to the plurality of mobile stations. The second communication mode performs loopback transmission, transmitting received radio waves from one mobile station to other mobile stations based on control commands from the line control device. The third communication mode autonomously performs loopback transmission only when it receives radio waves from a specific mobile station pre-assigned to each base station. When a communication line failure occurs between the line control device and at least one of the plurality of base stations, the line control device causes the remaining base stations to execute the third communication mode.

[0008] In the above-described mobile radio communication system, when a communication line failure occurs between the line and at least one of the multiple base stations, the line control device causes the remaining base stations to execute a third communication mode. This prevents multiple base stations from loopback transmitting radio waves received from one mobile station when a communication line failure occurs. Therefore, proper loopback transmission can be achieved at each base station even when a communication line failure occurs.

[0009] The aforementioned multiple base stations may independently execute the third communication mode when they detect the fault.

[0010] When the plurality of base stations receive a radio wave from at least one of the plurality of mobile stations, they may each transmit a notification of the arrival of the radio wave to the line control device. The line control device may determine from the plurality of base stations which base station will execute the second communication mode.

[0011] The plurality of mobile stations may transmit the radio waves along with mobile station information that includes an identifier unique to each mobile station. The plurality of base stations each have a receiving unit that receives the radio waves and a storage unit that stores the identifier of a particular mobile station, and may decide whether or not to perform the third communication mode based on the stored identifier and the received mobile station information.

[0012] The line control device may enable the multiple base stations to execute the first communication mode when none of the multiple base stations are performing the loopback transmission.

[0013] The plurality of base stations may transmit fire and emergency radio information to the plurality of mobile stations in the first communication mode.

[0014] A line control device according to one embodiment of the present invention is a line control device for a mobile radio communication system having a plurality of base stations, each having a first communication mode for transmitting received signals from a communication command center to a plurality of mobile stations, a second communication mode for performing loopback transmission for transmitting received radio waves from one mobile station to other mobile stations, and a third communication mode for autonomously performing the loopback transmission only when radio waves from a specific mobile station assigned in advance are received, and comprises a monitoring unit and a line control unit. The monitoring unit monitors the status of the communication lines connecting the communication command center and the multiple base stations. When the monitoring unit detects a fault in the communication line between the line control unit and at least one of the plurality of base stations, the line control unit causes the remaining base stations to execute the third communication mode.

[0015] A base station according to one embodiment of the present invention comprises a monitoring unit and a communication control unit. The monitoring unit monitors the status of the communication line connected to the communication command center. The communication control unit executes one of the following based on a command from the line control device that controls the connection of the communication line: a first communication mode in which it transmits a received signal from the communication command console to multiple mobile stations; a second communication mode in which it performs loopback transmission, transmitting a received radio wave from one mobile station to another mobile station; and a third communication mode in which it autonomously performs the loopback transmission only when it receives a radio wave from a specific mobile station that has been assigned in advance. The communication control unit executes the third communication mode when the monitoring unit detects a fault in the communication line. [Effects of the Invention]

[0016] According to the present invention, proper loopback transmission at each base station can be achieved even when a communication line malfunction occurs. [Brief explanation of the drawing]

[0017] [Figure 1] This is a schematic diagram of a mobile wireless communication system according to one embodiment of the present invention. [Figure 2]It is a schematic diagram for explaining the problems of a conventional mobile wireless communication system. [Figure 3] It is a block diagram showing the configuration of a base station in the mobile wireless communication system of FIG. 1. [Figure 4] It is an explanatory diagram of one operation of the mobile wireless communication system of FIG. 1. [Figure 5] It is a sequence diagram showing an example of the operation of the mobile wireless communication system of FIG. 1. [Figure 6] It is a sequence diagram showing an example of another operation of the mobile wireless communication system of FIG. 1. [Figure 7] It is an explanatory diagram showing whether or not retransmission is possible at each base station in the normal state in the mobile wireless communication system of FIG. 1. [Figure 8] It is an explanatory diagram showing whether or not retransmission is possible at each base station when a line failure occurs in the mobile wireless communication system of FIG. 1.

Embodiments for Carrying Out the Invention

[0018] Hereinafter, embodiments of the present invention will be described with reference to the drawings.

[0019] 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.

[0020] [Overall Configuration] The mobile wireless communication system 100 of this embodiment includes a communication command station 1, a line control device 2, a plurality of base stations 3, and a plurality of mobile stations 4.

[0021] The communication command station 1, also referred to as a command system device, is connected to the line control device 2 or the base station 3 to perform wireless communication with the mobile station 4. The communication command station 1 is installed, for example, in a fire headquarters or a fire station, and transmits command information to each mobile station 4 from the base station 3.

[0022] The line control device 2 controls communication between the communication command center 1 and multiple base stations 3. This communication line includes approach lines (relay lines) 5 connecting the line control device 2 and the multiple base stations 3, communication cables 6, and various network devices such as routers for transferring data.

[0023] Each base station 3 is a radio base station for communicating with multiple mobile stations and is typically installed at a specific location (e.g., a fire station). The number of base stations 3 is not particularly limited; Figure 1 shows two base stations 3A and 3B, but there may, of course, be three or more.

[0024] When each base station 3 receives command information from the communication command center 1 via the approach line 5, it wirelessly transmits the command information regarding fire and emergency radio information to the mobile station 4 via downlink radio waves C1. When each base station 3 receives an uplink radio wave C2 containing communication information from the mobile station 4, it transmits the communication information to the communication command center 1 via the approach line 5. When each base station 3 receives instructions from the line control device 2, or when a malfunction (line abnormality) such as a break in the communication cable 6 occurs, it autonomously transmits a loopback radio wave C3 for the received uplink radio wave C2, as described later. The downlink radio wave C1 and the uplink radio wave C2 are on different frequencies, while the downlink radio wave C1 and the loopback radio wave C3 are on the same frequency.

[0025] Each mobile station 4 is a radio station that operates while moving or while stopped at an unspecified location. These are vehicle-mounted radios installed in ambulances or fire trucks, or portable radios carried by ambulance crews or firefighters. A mobile station 4 transmits an uplink radio wave C2 for communication with the communication command center 1, for example, by pressing a button. The number of command center mobile stations 4 is not particularly limited; Figure 1 shows two mobile stations 4A and 4B, but there may be three or more.

[0026] In fire and emergency digital radio communication, a digital radio communication network is formed between base stations and mobile stations, used for commands from the communication command center to mobile stations, or reports from mobile stations to the communication command center. The radio frequency band used is, for example, 260MHz, and it is possible to communicate not only voice information but also data such as text information, location information, and support information.

[0027] For example, as shown in Figure 1, when a press operation is performed in the communication command center 1 to select base stations 3A and 3B and press a press button to start a call, the press signal from the communication command center 1 is notified to the selected base station 3A or 3B via the line control device 2. Upon receiving the notification, base station 3A or 3B transmits a downlink radio wave C1, and when mobile stations 4A and 4B receive this downlink radio wave C1, communication between the communication command center 1 and mobile stations 4A and 4B is established, and the actual transmission of voice begins. Furthermore, based on the uplink radio wave C2 from mobile stations 4A and 4B, after selecting a base station with good communication status from the incoming call information from base stations 3A and 3B that received the uplink radio wave C2, the communication command center 1 can receive the actual voice through the selected base station.

[0028] Furthermore, digital radio communications for fire and emergency services employ a dual-frequency simplex (or duplex) system with different transmission and reception frequencies. This allows for communication between mobile stations by having a base station relay the radio waves transmitted from the mobile station.

[0029] For example, as shown in Figure 1, when a press operation is performed from mobile station 4A, an uplink radio wave C2 is transmitted to base stations 3A and 3B. Upon receiving the uplink radio wave C2, base stations 3A and 3B notify the line control device 2 of the incoming call information. The line control device 2 transmits the incoming call information to the communication command center 1 and selects a base station with good communication status (e.g., base station 3B) from the incoming call information from base stations 3A and 3B, and instructs the selected base station 3B to transmit a return radio wave C3 for the uplink radio wave C2. As a result, within the communication area of ​​base station 3B, mobile station 4B can receive all transmissions sent by mobile station 4A.

[0030] In the following explanation, the operation of base station 3 to return the uplink radio wave C2 from one mobile station 4 to another mobile station 4 is also referred to as loopback transmission. The purpose of loopback transmission is to understand the call status of other mobile stations 4 and to prevent radio wave transmission from multiple mobile stations 4. In this case, a busy signal may be included in the loopback radio wave C3 to prevent transmission from other mobile stations 4.

[0031] As described above, loopback transmission by base station 3 is performed under the control of the line control device 2, which monitors and controls the communication line. Therefore, if a failure occurs in the communication line between the line control device 2 and base station 3, proper loopback transmission may not be possible at each base station 3. To address such situations, one could consider, for example, having the base station experiencing a line failure perform loopback transmission according to predetermined conditions (for example, loopback transmission of all received uplink radio waves C2). However, in such a case, for example, when base station 3A with a normal line receives a command from the line control device 2 and performs loopback transmission, base station 3B, which has a line failure, will perform loopback transmission independently of the control of the line control device 2. As a result, as shown in Figure 2, the radio waves C3 loopback transmitted from multiple base stations 3A and 3B may interfere with each other, potentially preventing communication between mobile stations 4 (4A and 4B).

[0032] Therefore, in the mobile radio communication system 100 of this embodiment, instead of a base station 3 experiencing a line failure automatically looping back all uplink radio waves C2 it receives, the system is configured to autonomously loop back only when it receives radio waves from a specific mobile station pre-assigned to each base station 3 in the event of a line failure. Furthermore, when at least one base station 3 experiences a line failure, all base stations 3 are enabled to perform the autonomous loopback transmission described above. In this way, each base station 3 determines whether or not to loop back based on the presence or absence of pre-registered mobile station information, even without a command from the line control device 2. As shown in Figure 4, this prevents interference of loopback radio waves C3 by avoiding the simultaneous loopback transmission of a single uplink radio wave C2 by multiple base stations 3. The details will be explained below.

[0033] [Base station] Figure 3 is a block diagram showing the configuration of base stations 3 (3A, 3B) in the mobile wireless communication system 100 of this embodiment. As shown in the figure, base station 3 has an IF (interface) unit 31, a signal processing unit 32, a wireless transceiver unit 33, a base station control unit 34, and a storage unit 35.

[0034] The IF unit 31 is connected to the approach line 5 and transmits and receives data with the line control device 2. The IF unit 31 also functions as a monitoring unit to check for any faults in the communication line with the line control device 2. The determination of whether or not there are faults may be made by the base station control unit 34 based on the output from the IF unit 31.

[0035] The signal processing unit 32 performs baseband signal processing, such as encoding the command communications (transmitted signals) from the communication control board 1 to be transmitted to the mobile station 4, and decoding the received signals of the uplink radio waves C2 transmitted from the mobile station 4.

[0036] The wireless transceiver unit 33 modulates the command communication (transmitted signal) from the command communication station 1 into a downlink radio wave C1 and demodulates the received signal of the uplink radio wave C2 transmitted from the mobile station 4. The wireless transceiver unit corresponds to the receiver that receives the uplink radio wave C2.

[0037] The base station control unit 34 comprehensively controls the operation of the base station 3, including the IF unit 31, the signal processing unit 32, and the wireless transceiver unit 33. The base station control unit 34 is capable of executing a first communication mode, a second communication mode, and a third communication mode.

[0038] In the first communication mode, the radio transceiver 33 transmits received signals from the communication command board 1 to multiple mobile stations 3. In the second communication mode, based on control commands from the line control device 2, the radio transceiver 33 performs loopback transmission of received radio waves (uplink radio waves C2) from one mobile station 4 to other mobile stations 4. In the third communication mode, the radio transceiver 33 autonomously performs loopback transmission only when it receives uplink radio waves C2 from a specific mobile station 4 pre-assigned to each base station 3. The third communication mode is executed when a communication failure with the line control device 2 is detected, or when the line control device 2 instructs it to switch modes, as will be described later.

[0039] When the base station control unit 34 detects a fault in the communication line with the line control device 2, it executes a third communication mode. For example, when the IF unit 31 of base station 3A detects an abnormality such as a break in the communication cable 6 between base station 3A and approach line 5, the base station control unit 34 of base station 3A enables base station 3A to independently execute the third communication mode. A fault in the communication line includes, for example, when communication with the line control device 2 is interrupted for a certain period of time or longer.

[0040] The base station control unit 34 can be implemented using hardware elements used in a computer, such as a CPU (Central Processing Unit), RAM (Random Access Memory), and ROM (Read Only Memory), as well as the necessary software.

[0041] The memory unit 35 is a storage device such as a semiconductor memory or a hard disk drive. The memory unit 35 stores various programs executed by the IF unit 31, the signal processing unit 32, the wireless transmission / reception unit 33, and the base station control unit 34.

[0042] Furthermore, the memory unit 35 stores the identifier of a specific mobile station 4 that has been assigned in advance. Hereinafter, a mobile station whose identifier is stored in the memory unit 35 will also be referred to as a mobile station registered with the base station. The identifier is not particularly limited as long as it is an identifier unique to the mobile station 4, for example, an in-vehicle device ID or a user ID. In this embodiment, the identifier of mobile station 4A is registered in base station 3A, and the identifier of mobile station 4B is registered in base station 3B.

[0043] Furthermore, the memory unit 35 of base station 3A may store the identifier of mobile station 4B, and the memory unit 35 of base station 3B may store the identifier of mobile station 4A. In addition, the number of mobile stations registered at each base station is not limited to one; multiple mobile stations may be registered at each base station as long as they do not overlap.

[0044] [Platform control device] As shown in Figure 1, the line control device 2 includes a line monitoring unit 21 and a line control unit 22.

[0045] The line monitoring unit 21 detects failures in the communication lines between multiple base stations 3. For example, if there is a base station 3 where communication has been interrupted for a certain period of time or longer, the line monitoring unit 21 determines that there is a problem such as a break in the communication cable 6 connected to that base station 3. For example, if communication is performed at predetermined intervals to confirm that the communication line is properly connected between the line control device 2 and the base station 3, the predetermined interval for detecting a failure in the communication line may be determined by multiplying this predetermined interval by an integer.

[0046] The line control unit 22 controls the switching connection of the communication line connected between the communication command center 1 and the base stations 3. The line control unit 22 establishes communication with the base station 3 selected by the communication command center 1 and enables the base station 3 to execute a first communication mode in which it transmits the received signal from the communication command center 1 to multiple mobile stations 4. At this time, the line control unit 22 enables the execution of the first communication mode for each base station 3 when none of the multiple base stations 3 are performing loopback transmission.

[0047] When the line control unit 22 receives an incoming notification from the base station 3 regarding the uplink radio wave C3 from the mobile station 4, it displays the incoming notification on the control panel of the communication command console 1. When the line control unit 22 also receives an incoming notification from the base station 3 regarding the uplink radio wave C3 from the mobile station 4, it outputs a control command to the base station 3 to execute a second communication mode in which the uplink radio wave C3 is routed back. When incoming notifications are received simultaneously from multiple base stations 3, the line control unit 22 selects one base station 3 from among the multiple base stations 3, for example, the one with the best reception status for the uplink radio wave C2, and outputs a control command to that base station 3 to execute the second reception mode.

[0048] Furthermore, if the line monitoring unit 21 detects a fault in the communication line at one or more base stations 3, the line control unit 22 outputs a control command to the remaining base stations 3 to execute a third communication mode. This prevents multiple base stations 3 from simultaneously looping back and transmitting the uplink radio waves C2 from a single mobile station 4.

[0049] [Operation of Mobile Radio Communication Systems] Next, the operation of the mobile wireless communication system 100 of this embodiment will be described. Here, the explanation will focus on loopback transmission at the base station 3.

[0050] First, we will explain the case where there is no failure in the communication line between the communication command center 1 and each base station 3. Figure 5 is a sequence diagram showing an example of the operation of the mobile radio communication system 100.

[0051] As shown in Figure 5, the mobile station 4A presses a button to transmit an uplink radio wave C2 (step 101). When base stations 3A and 3B receive the uplink radio wave C2, each base station 3A and 3B notifies the line control device 2 of the incoming call (step 102). The line control device 2 determines which of the base stations 3A and 3B has a good communication status with the mobile station 4 (in this case, base station 3A) and sends a callback command to base station 3A (step 103). Furthermore, the line control device 2 notifies the communication command center 1 of the incoming call from base station 3A, which will perform the callback transmission, and displays the incoming call (step 104).

[0052] Meanwhile, base station 3A, having received a loopback command from line control device 2, executes a second communication mode to loop back the uplink signal C2 from mobile station 4A (step 105). This makes it possible for other mobile stations located within base station 3A's communication area (for example, mobile station 4B) to receive the content of mobile station 4A's conversation.

[0053] According to this embodiment, when an incoming call notification is received from multiple base stations 3A and 3B, the line control device 2 selects one of the base stations to perform a loopback transmission. This prevents loopback transmissions from multiple base stations 3, thereby preventing interference from loopback radio waves C3.

[0054] Next, we will explain what happens when a failure occurs in the communication line of base station 3B. Figure 6 is a sequence diagram showing an example of the operation of the mobile radio communication system 100.

[0055] If a fault occurs in the communication line between the line control device 2 and the base station 3B, the base station 3B detects the fault and switches to the third communication mode (step 201). Similarly, the line control device 2 also detects the fault in the communication line of base station 3B and outputs a command to switch to the third communication mode to base station 3A, which is not experiencing a fault (step 202). In response, base station 3A switches to the third communication mode (step 203).

[0056] In this state, when mobile station 4A presses a button, and mobile station 4A transmits an uplink signal C2 (step 203), base stations 3A and 3B receive the uplink signal C2. Because there is a fault in the communication line of base station 3B, the notification of the incoming uplink signal C2 is sent only from base station 3A (step 204). When the line control device 2 receives the notification of the incoming signal from base station 3A, it displays the incoming signal to the communication command center 1 (step 205).

[0057] On the other hand, base stations 3A and 3B, which receive the uplink radio wave C2, independently determine whether the mobile station 4 that transmitted the received uplink radio wave C2 is a mobile station that has been pre-registered (assigned to each base station). In this embodiment, base station 3A is assigned mobile station 4A and base station 3B is assigned mobile station 4B, so only base station 3A can perform loopback transmission of the uplink radio wave C2 from mobile station 4A. For this reason, base station 3B does not perform loopback transmission, and base station 3A performs loopback transmission (step 206). This prevents multiple base stations 3A and 3B from simultaneously performing loopback transmission of the uplink radio wave C2 from mobile station 4A, and thus prevents interference of loopback radio waves C3 from these multiple base stations 3A and 3B.

[0058] In this case, mobile station 4B can only receive the loopback signal C3 when it is located within the communication area of ​​base station 3A. In this case, mobile station 4B is not affected by interference from the loopback signal C3 from base station 3B because base station 3B does not loopback transmission, and can understand the content of the call from mobile station 4A by properly receiving the loopback signal C3 from base station 3A.

[0059] Figures 7(A) and 7(B) are explanatory diagrams showing whether loopback transmission is possible at each base station 3A and 3B, summarized for each case.

[0060] In each of the cases shown below, there is an abnormality (line failure) in at least one of base stations 3A and 3B, and all base stations 3A and 3B have transitioned to the third communication mode. Also, in "Uplink" in Figure 7(B), "Mobile Station 4A (Area A)" indicates that the source of the uplink signal C2 is mobile station 4A located in the communication area (Area A) of base station 3A (see Figure 7(A)), and "Mobile Station 4B (Area B)" indicates that the source of the uplink signal C2 is mobile station 4B located in the communication area (Area B) of base station 3B (see Figure 7(A)). In addition, in each case of Figure 7(B), the mobile station transmitting the uplink signal C2 and the base station performing the return transmission are indicated with "○", and all others are indicated with "-" (the same applies to Figure 8(B)).

[0061] Cases 1 and 2 illustrate situations where there is a malfunction (communication failure) at base station 3A. If the source of the uplink signal C2 is mobile station 4A (Area A), only base station 3A will perform the return transmission. If the source of the uplink signal C2 is mobile station 4B (Area B), only base station 3B will perform the return transmission. Cases 3 and 4 show situations where there is a malfunction (communication failure) at base station 3B, while cases 5 and 6 show situations where there is a malfunction (communication failure) at all base stations 3A and 3B. In all cases from 3 to 6, the relationship between the source of the uplink radio wave C2 and the base station that performs the return transmission is the same as in cases 1 and 2.

[0062] On the other hand, as shown in Figures 8(A) and 8(B), if mobile station 4A is located in area B (the communication area of ​​base station 3B) and mobile station 4B is located in area A (the communication area of ​​base station 3A), then in all of the above cases 1 to 6, base stations 3A and 3B will not perform loopback transmission. In other words, even if each base station 3A and 3B receives the uplink radio waves C2 from mobile stations 4A and 4B, since it is not a reception from a registered mobile station for either base station 3A or 3B, neither base station 3A nor 3B will perform loopback transmission. That is to say, in this embodiment, the objective is to eliminate communication failures between mobile stations caused by interference from loopback radio waves from multiple base stations, so communication failures between mobile stations when a mobile station is located outside the communication area of ​​a base station are permitted.

[0063] In this case, it is also possible to change the communication mode (second communication mode) to one in which a base station that is not experiencing a communication failure performs loopback transmission under the control of the line control device 2. In this case, when an uplink radio wave C2 is received from a mobile station not registered with the base station, loopback transmission from that base station becomes possible.

[0064] Furthermore, in Figure 8(A), if at least one of the mobile stations 4A or 4B is located in an area where the communication area of ​​base station 3A and the communication area of ​​base station 3B overlap, a loopback transmission will be performed by base station 3A or base station 3B, and communication between mobile stations 4A and 4B will be established.

[0065] As described above, according to this embodiment, when a communication line failure occurs between the line control device 2 and at least one of the multiple base stations 3, the remaining base stations are instructed to execute a third communication mode in which they loop back only the radio waves received from a pre-registered mobile station. Therefore, when a communication line failure occurs, multiple base stations will not loop back and transmit the radio waves received from one mobile station. For this reason, proper loopback transmission can be achieved at each base station 3 even when a communication line failure occurs.

[0066] Furthermore, according to this embodiment, when a communication failure is detected, the third communication mode is executed independently, so the system can autonomously switch to the third communication mode without receiving a command from the line control device 2.

[0067] Furthermore, according to this embodiment, when none of the base stations 3 are performing loopback transmission, each base station 3 is capable of executing a first communication mode in which instruction information from the communication command center 1 is transmitted to the mobile station 4. This prevents interference between the downlink radio waves C1 from the base stations 3 and the loopback radio waves C3, ensuring proper reception of radio waves at each mobile station 4. As a result, a good communication state can be maintained between the communication command center 1 and the mobile station 4.

[0068] Although embodiments of the present invention have been described above, it goes without saying that the present invention is not limited to the embodiments described above and can be modified in various ways.

[0069] For example, in the embodiments described above, an example of application to a fire and emergency digital wireless communication system was explained as a mobile wireless communication system, but the present invention is not limited to this and can also be applied to wireless systems in other fields such as transportation and logistics. [Explanation of symbols]

[0070] 1…Communication Command Center 2…Circuit control device 3,3A,3B…Base station 4,4A,4B…Mobile station 5…Approach Circuit 6…Communication cable 21…Line Monitoring Department 22...Circuit Control Unit 31...IF section 32... Signal Processing Unit 33…Wireless Transceiver Unit 34…Base Station Control Unit 35...Storage section 100... Mobile radio communication system C1...downlink C2...Uplink C3...Folded radio waves

Claims

1. A mobile radio communication system comprising a communication command center and a plurality of base stations connected via a communication line, a line control device that controls communication between the communication command center and the plurality of base stations, and a plurality of mobile stations that can be connected to the plurality of base stations via a radio line, Each of the aforementioned multiple base stations has a first communication mode in which it transmits received signals from the communication command center to the multiple mobile stations; a second communication mode in which it performs loopback transmission, transmitting received radio waves from one mobile station to other mobile stations based on control commands from the line control device; and a third communication mode in which it autonomously performs loopback transmission only when it receives radio waves from a specific mobile station that is pre-assigned to each base station and does not overlap with other base stations. When a communication line failure occurs between the line control device and at least one of the multiple base stations, the line control device causes the remaining base stations to execute the third communication mode. Mobile radio communication system.

2. A mobile radio communication system according to claim 1, When the aforementioned multiple base stations detect the fault, they independently execute the third communication mode. Mobile radio communication system.

3. A mobile radio communication system according to claim 1 or 2, When the plurality of base stations receive a radio wave from at least one of the plurality of mobile stations, they each transmit a notification of the arrival of the radio wave to the line control device. The aforementioned line control device determines one base station from among the plurality of base stations to execute the second communication mode. Mobile radio communication system.

4. A mobile radio communication system according to any one of claims 1 to 3, The aforementioned multiple mobile stations transmit the radio waves along with mobile station information, which includes an identifier unique to each mobile station. Each of the aforementioned base stations has a receiving unit for receiving radio waves and a storage unit for storing an identifier for a specific mobile station, and determines whether or not to execute the third communication mode based on the stored identifier and the received mobile station information. Mobile radio communication system.

5. A mobile radio communication system according to any one of claims 1 to 4, The line control device enables the multiple base stations to execute the first communication mode when none of the multiple base stations are performing the loopback transmission. Mobile radio communication system.

6. A mobile radio communication system according to any one of claims 1 to 5, The plurality of base stations transmit fire and emergency radio information to the plurality of mobile stations in the first communication mode. Mobile radio communication system.

7. A line control device for a mobile radio communication system comprising multiple base stations, each having a first communication mode for transmitting received signals from a communication command center to multiple mobile stations, a second communication mode for performing loopback transmission for transmitting received radio waves from one mobile station to other mobile stations, and a third communication mode for autonomously performing the loopback transmission only when radio waves from a specific mobile station that is pre-assigned and does not overlap at each base station. A monitoring unit that monitors the status of the communication line connecting the communication command center and the plurality of base stations, When the monitoring unit detects a fault in the communication line between at least one of the plurality of base stations, the line control unit causes the remaining base stations to execute the third communication mode. A circuit control device equipped with a circuit control device.

8. A monitoring unit that monitors the status of the communication line connected to the communication command center, Based on a command from a line control device that controls the connection of the communication line, the communication control unit executes one of the following: a first communication mode in which a received signal from the communication command console is transmitted to multiple mobile stations; a second communication mode in which a received radio wave from one mobile station is transmitted to another mobile station via loopback transmission; and a third communication mode in which the loopback transmission is performed autonomously only when a radio wave from a specific mobile station that is pre-assigned and does not overlap with other base stations is received. When the monitoring unit detects a fault in the communication line, the third communication mode is executed. A base station equipped with the following features.

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