Wireless communication system and wireless communication method

Abstract

To provide a wireless communication system having a command center and a base station that can communicate with higher reliability than before in an event of an emergency at a lower cost with a simpler structure and to provide a wireless communication method.SOLUTION: A wireless communication system 100 according to an aspect of the present disclosure has a plurality of base stations including a first base station 10 and a second base station 20 that are controlled by a line control device 30. When communication between the line control device 30 and the second base station 20 is in a disconnected state, communication is carried out between the line control device 30 and the second base station 20 through at least one of a mobile station 101 belonging to the first base station 10 and a mobile station 201 belonging to the second base station 20, which are located in an overlapping area A12 in which a wireless area A1 of the first base station overlaps with a wireless area A2 of the second base station.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present disclosure relates to a wireless communication system and a wireless communication method. [Background technology]

[0002] Firefighting radio systems and disaster prevention radio systems have been developed for use in emergencies such as when a disaster occurs. Patent Document 1 discloses a communication system that, when a wired line connecting a command center and a base station is cut off due to a disaster, connects the base station whose wired line has been cut off to the command center via another base station that has not lost its wired line communication function. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2004-242077 Summary of the Invention [Problem to be solved by the invention]

[0004] In the communication system disclosed in the above-mentioned Patent Document 1, a base station connected to a command center via a wired line is connected to a base station where the wired line to the command center is disconnected via a wireless connection between the base stations, enabling communication between the command center and the base station where the wired line is disconnected. However, improving the base station to enable a wireless connection just to prepare for emergencies that are so infrequent that the wired line is disconnected would have the problem of complicating the system and increasing costs.

[0005] In view of the above-mentioned problems, an object of the present disclosure is to provide a wireless communication system and a wireless communication method having a command center and a base station that can communicate with higher reliability than conventional systems in the event of an emergency, with a simpler configuration and at lower cost. [Means for solving the problem]

[0006] A wireless communication system according to an embodiment of the present disclosure includes: A wireless communication system having a plurality of base stations including a first base station and a second base station controlled by a line control device, When communication between the line control device and the second base station is disconnected, communication is performed between the line control device and the second base station via at least one of a mobile station belonging to the first base station and a mobile station belonging to the second base station that are located in an overlapping area where the wireless area of ​​the first base station and the wireless area of ​​the second base station overlap.

[0007] A wireless communication method according to one aspect of the present disclosure includes: A wireless communication method having a plurality of base stations including a first base station and a second base station controlled by a line control device, When communication between the line control device and the second base station is disconnected, communication is performed between the line control device and the second base station via at least one of a mobile station belonging to the first base station and a mobile station belonging to the second base station that are located in an overlapping area where the wireless area of ​​the first base station and the wireless area of ​​the second base station overlap. [Effects of the Invention]

[0008] The present disclosure makes it possible to provide a wireless communication system and a wireless communication method having a command center and a base station that can communicate with higher reliability than conventional systems in the event of an emergency, with a simpler configuration and at lower cost. [Brief explanation of the drawings]

[0009] [Figure 1] 1 is a schematic diagram showing the configuration of a wireless communication system according to a first embodiment. [Figure 2] 3 is a flowchart showing the flow of a wireless communication method according to the first embodiment. [Figure 3] FIG. 10 is a schematic diagram illustrating a configuration of a wireless communication system according to a second embodiment. [Figure 4] FIG. 10 is an explanatory diagram for explaining processing of the communication system according to the second embodiment. [Figure 5]FIG. 10 is an explanatory diagram for explaining processing of the communication system according to the second embodiment. [Figure 6] FIG. 10 is an explanatory diagram for explaining processing of the communication system according to the second embodiment. [Figure 7] FIG. 10 is an explanatory diagram for explaining processing of the communication system according to the second embodiment. [Figure 8] FIG. 10 is an explanatory diagram for explaining processing of the communication system according to the second embodiment. [Figure 9] FIG. 10 is a schematic diagram illustrating a configuration of a wireless communication system according to a third embodiment. [Figure 10] FIG. 10 is a schematic diagram showing the configuration of a wireless communication system according to a fourth embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0010] The present disclosure will be described below through embodiments, but the disclosure according to the claims is not limited to the following embodiments. Furthermore, not all of the configurations described in the embodiments are necessarily essential as means for solving the problems. In each drawing, the same elements are denoted by the same reference numerals, and redundant explanations are omitted as necessary.

[0011] <Embodiment 1> Hereinafter, a first embodiment of the present disclosure will be described with reference to the drawings. FIG. 1 is a schematic diagram showing a configuration of a wireless communication system according to the first embodiment. The wireless communication system 100 according to the first embodiment includes a command center H1, a line control device 30, a first base station 10, a second base station 20, mobile stations 101 to 103, and mobile stations 201 to 203. The wireless communication system 100 has a hierarchical structure of the command center H1, the line control device 30, the first base station 10, the second base station 20, the mobile stations 101 to 103, and the mobile stations 201 to 203. The wireless communication system 100 is, for example, a disaster prevention wireless system or a firefighting wireless system.

[0012] The line controller 30 and the first base station 10 are connected by a wired path L1, and the line controller 30 and the second base station 20 are connected by a wired path L2.

[0013] The mobile stations 101 to 103 are located in any of the wireless areas A1 of the first base station 10 and belong to the first base station 10. The mobile stations 101 to 103 and the first base station 10 are wirelessly connected.

[0014] On the other hand, the mobile stations 201 to 203 are located in any of the wireless areas A2 of the second base station 20 and belong to the second base station 20. The mobile stations 201 to 203 and the second base station 20 are wirelessly connected.

[0015] Mobile stations 101 to 103 and mobile stations 201 to 203 can move freely within the radio area to which they belong. Mobile stations 101 to 103 and mobile stations 201 to 203 are, for example, in-vehicle radio devices installed in vehicles or portable radio devices that can be carried by hand.

[0016] The mobile stations 101 to 103 can communicate with each other using Wi-Fi (registered trademark), Bluetooth (registered trademark), or other wireless communication systems. The same applies to the mobile stations 201 to 203.

[0017] 1, in the wireless communication system 100, the line control device 30 transmits a downlink signal from a command center H1 to the first base station 10 and the second base station 20. The first base station 10 transmits the downlink signal received from the command center H1 to the mobile stations 101 to 103. The second base station 20 transmits the downlink signal received from the command center H1 to the mobile stations 201 to 203.

[0018] Conversely, the first base station 10 transmits uplink signals from the mobile stations 101 to 103 to the channel control device 30. Also, the second base station 20 transmits uplink signals from the mobile stations 201 to 203 to the channel control device 30. Furthermore, the channel control device 30 transmits the received uplink signals from the mobile stations 101 to 103 and 201 to 203 to the command center H1.

[0019] Here, in the event of an emergency caused by a disaster, the wired path connecting the line control device 30 and the first base station 10 or the second base station 20 may be disconnected. In this case, the first base station 10 or the second base station 20 that can no longer connect to the line control device 30 cannot receive signals from the command center H1. Below, an example will be described in which communication between the line control device 30 and the second base station 20 is disconnected, that is, the wired path L2 is disconnected.

[0020] 1, when the wired path L2 is disconnected, the mobile station 101 or the mobile station 201 moves to be located in an overlapping area A12 where the wireless area A1 of the first base station 10 and the wireless area A2 of the second base station 20 overlap. For example, the mobile station 101 or the mobile station 201 has pre-installed map information or latitude and longitude information indicating the location, and the person carrying the mobile station or the person driving the vehicle equipped with the mobile station moves together with the mobile station based on the map display.

[0021] As another example, the mobile station 101 or 201 may have a built-in function for displaying current location information such as a global positioning system (GPS) in addition to map information or latitude and longitude information indicating the location, and display the direction to move from the current location, allowing a person carrying the mobile station or a person driving a vehicle equipped with the mobile station to move while looking at the display.The mobile station 101 or 201 may also move in cooperation with a vehicle equipped with an automatic driving system using the vehicle's automatic driving function. If the mobile station 101 or 201 is located in the overlapping area A12 when the wired route L2 is disconnected, the mobile station 101 or 201 may display a message indicating that it is not necessary to move.

[0022] Communication between the line controller 30 and the second base station 20 is performed via at least one of the mobile station 101 and the mobile station 201 located in the overlapping area A12. That is, communication between the line controller 30 and the second base station 20 is performed via a wired route L1, a wireless route L11, and a wireless route L12. Communication between the line controller 30 and the second base station 20 may also be performed via a wired route L1, a wireless route L22, and a wireless route L21.

[0023] Furthermore, the communication between the line controller 30 and the second base station 20 may be performed via a wired path L1, a wireless path L11, a wireless path L12, a wireless path L21, and a wireless path L22. More specifically, the line control device 30 transmits a downlink signal from the command center H1 to the first base station 10 via the wired path L1. The first base station 10 transmits the received downlink signal from the command center H1 to the mobile station 101 via the wireless path L11. The mobile station 101 transmits the received downlink signal from the command center H1 to the second base station 20 via the wireless path L12. The second base station 20 transmits the received downlink signal from the command center H1 to the mobile station 202 via the wireless path L23. Furthermore, the second base station 20 transmits the received downlink signal from the command center H1 to the mobile station 203 via the wireless path L33. That is, the downlink signals from the command center H1 to the mobile stations 202 and 203 are transmitted via the wired path L1, the wireless path L11, the wireless path L12, the wireless path L23, and the wireless path L33.

[0024] On the other hand, the mobile station 202 transmits an uplink signal (response signal) in response to the signal from the command center H1 to the second base station 20 via the wireless path L23. Also, the mobile station 203 transmits an uplink signal (response signal) in response to the signal from the command center H1 to the second base station 20 via the wireless path L33. The second base station 20 transmits the response signal to the mobile station 201 via the wireless path L21. The mobile station 201 transmits the received response signal to the first base station 10 via the wireless path L22. The first base station 10 transmits the response signal to the line control device 30 via the wired path L1. The line control device 30 transmits the response signal to the command center H1. That is, signals from the mobile stations 202 and 203 to the command center H1 are transmitted via the wireless path L23, the wireless path L33, the wireless path L21, the wireless path L22, and the wired path L1.

[0025] In the example shown in Figure 1, the wireless communication system 100 is composed of two wireless base stations, a first base station 10 and a second base station 20, but is not limited to this and may include three or more base stations.

[0026] Next, a wireless communication method according to the first embodiment will be described. Fig. 2 is a flowchart showing the flow of the wireless communication method according to the first embodiment. Fig. 2 shows the flow of the wireless communication method when communication between the line control device 30 and the second base station 20 is disconnected. First, a mobile station located in an overlapping area A12 where the wireless area A1 of the first base station 10 and the wireless area A2 of the second base station 20 overlap is selected (ST1). Next, communication is performed between the line control device 30 and the second base station 20 via the selected mobile station (ST2).

[0027] As described above, in the wireless communication system 100 according to the first embodiment, when communication between the line control device 30 and the second base station 20 is disconnected, at least one of the mobile station 101 belonging to the first base station 10 and the mobile station 201 belonging to the second base station 20 is located in the overlapping area A12. Communication is performed between the line control device 30 and the second base station 20 via at least one of the mobile station 101 belonging to the first base station 10 and the mobile station 201 belonging to the second base station 20. This allows communication between the command center H1 and the mobile stations 202 and 203 located in the wireless area A2 of the second base station 20 with a simpler, lower-cost configuration in the event of an emergency.

[0028] <Embodiment 2> Hereinafter, a second embodiment of the present disclosure will be described with reference to the drawings. FIG. 3 is a schematic diagram showing a configuration of a wireless communication system according to the second embodiment. In the wireless communication system 200 shown in FIG. 3, wired paths and wireless paths are divided into paths for uplink signals and paths for downlink signals. For example, the wireless path U11 for uplink signals and the wireless path D11 for downlink signals in FIG. 3 correspond to the wireless path L11 in FIG. 1. That is, in the wireless communication system 200, the wireless paths are separated for uplink signals and downlink signals. The separation of the wireless paths is achieved by setting different signal frequencies and time periods for transmitting different signals for uplink and downlink signals.

[0029] The wireless communication system 200 shown in Fig. 3 differs from the wireless communication system 100 shown in Fig. 1 in that the wired and wireless paths are divided into paths for uplink signals and paths for downlink signals, and that the first base station 10 includes a first receiving unit 10R, and the second base station 20 includes a second receiving unit 20R. Since the other configurations are the same as those of the wireless communication system 100 according to the first embodiment, a description thereof will be omitted. In the following, as in the first embodiment, a case where communication between the line control device 30 and the second base station 20 is disconnected will be described.

[0030] 3, the first base station 10 is located in the overlapping area A12 and includes a first receiving unit 10R that receives a signal transmitted from the second base station 20 via a mobile station 201 that belongs to the second base station 20. The first receiving unit 10R includes, for example, an antenna with high directivity.

[0031] 3, the second base station 20 is located in the overlapping area A12 and has a second receiving unit 20R that receives a signal transmitted from the line controller 30 via a mobile station 101 that belongs to the first base station 10. The second receiving unit 20R includes, for example, an antenna with high directivity.

[0032] Here, the wired paths U2 and D2, which are the communication paths between the line control device 30 and the second base station 20, are disconnected. Therefore, the line control device 30 cannot transmit a downlink signal to the second base station 20 via the wired path D2. In addition, the second base station 20 cannot transmit an uplink signal to the line control device 30 via the wired path U2.

[0033] On the other hand, the communication between the line control device 30 and the first base station 10 is not disconnected. Therefore, the line control device 30 can transmit a downlink signal to the first base station 10 via the wired path D1. Also, the first base station 10 can transmit an uplink signal to the line control device 30 via the wired path U1.

[0034] 3, the first base station 10 and the mobile station 101 located in the overlapping area A12 are wirelessly connected and therefore can communicate with each other. More specifically, the first base station 10 transmits a downlink signal to the mobile station 101 via a wireless path D11. The mobile station 101 transmits an uplink signal to the first base station 10 via a wireless path U11.

[0035] 3, the mobile station 101 is located in a wireless area A12. The mobile station 101 transmits an uplink signal to the second base station 20 via a wireless path U12. The second base station 20 receives the signal transmitted from the mobile station 101 located in the overlapping area A12 by the second receiving unit 20R.

[0036] That is, the signal transmitted from the line control device 30 is received by the second receiving unit 20R of the second base station 20 via the mobile station 101 that is located in the overlapping area A12 and belongs to the first base station 10. As a result, the second base station 20 receives the signal transmitted from the line control device 30 via the wired path D1, the wireless path U11, and the wireless path U12.

[0037] 3, the second base station 20 and the mobile station 201 located in the overlapping area A12 are wirelessly connected and therefore can communicate with each other. More specifically, the second base station 20 transmits a downlink signal to the mobile station 201 via a wireless path D21. In addition, the mobile station 201 transmits an uplink signal to the second base station 20 via a wireless path U21.

[0038] 3, the mobile station 201 is located in the wireless area A12. The mobile station 201 transmits an uplink signal to the first base station 10 via the wireless path U22. The first base station 10 receives the signal transmitted from the mobile station 201 located in the overlapping area A12 by the first receiving unit 10R.

[0039] That is, the signal transmitted from the second base station 20 is located in the overlapping area A12 and is received by the first receiving unit 10R of the first base station 10 via the mobile station 201 that belongs to the second base station 20. As a result, the line control device 30 receives the signal transmitted from the second base station 20 via the wireless path D21, the wireless path U22, and the wired path U1.

[0040] Furthermore, the first receiving unit 10R of the first base station 10 can obtain a gain in receiving the wireless path U22 from the mobile station 201 due to the directivity of the antenna. Furthermore, the second receiving unit 20R of the second base station 20 can obtain a gain in receiving the wireless path U21 from the mobile station 101 due to the directivity of the antenna.

[0041] Here, the first base station 10 may transmit the signal transmitted from the line control device 30 to the second base station 20 to the mobile station 101 located in the overlapping area A12 and belonging to the first base station 10 in priority to signals transmitted to the mobile stations 102 and 103 belonging to the first base station 10.

[0042] <Return signal> 3 and 4, a signal transmitted from the first base station 10 to the second base station 20 will be described in detail. Fig. 4 is an explanatory diagram for explaining the processing of the communication system according to the second embodiment.

[0043] 3 and 4, the line control device 30 and the first base station 10 are connected by wire, so the line control device 30 transmits a downlink signal to the first base station 10 via a path D1. In addition, the first base station 10 transmits the signal transmitted from the line control device 30 to the mobile station 102 via a wireless path D13.

[0044] The mobile station 102 transmits an uplink signal to the first base station 10 via the radio path U13 in response to the received signal or spontaneously. The uplink signal transmitted by the mobile station 102 is transmitted as a downlink signal from the first base station 10 to the mobile stations 101 and 103 in the wireless area A1. This is called base station return. An uplink signal transmitted by the mobile station 102 is transmitted from the first base station 10 to the line control device 30 via wired path U1, and the line control device 30 transmits the uplink signal to the first base station 10 via wired path D1, and the uplink signal is transmitted from the first base station 10 as a downlink signal to the mobile stations 101 and 103 in the wireless area A1. This is called a line control device loopback. In the case of a line control device loopback, an uplink signal transmitted by a mobile station located in the wireless area of ​​another base station, for example, the mobile station 102, is also transmitted to the mobile stations 201, 202, and 203 under the control of the second base station 20 via the second base station 20.

[0045] , That is, as shown in FIGS. 3 and 4, the first base station 10 (1) Downlink signals to the mobile stations 101, 102, and 103 received from the line control device 30 via the wired path D1; (2) A downlink signal that transmits an uplink signal received from the mobile station 102 via the wireless path U13 as a base station return signal or a line control device return signal; (3) A downlink signal to the second base station 20 received from the line control device 30 via the wired path D1; may be transmitted as a downstream signal.

[0046] In this case, the first base station 10 transmits the downlink signal addressed to the second base station 20 received from the line control device 30 to the mobile station 101 with priority over other downlink signals. The mobile station 101 transmits the received signal as an uplink signal to the second base station 20 via the wireless path U12. In FIG. 4, the above-mentioned signals (1) to (3) are shown along with the wireless paths.

[0047] In many cases, the downlink signal transmitted from the channel control device 30 via the path D1 to the second base station 20 is more important than the downlink signal from the channel control device 30 to the mobile stations 101, 102, and 103, or the downlink signal as a base station loopback or channel control device loopback signal. Therefore, the first base station 10 gives priority to transmitting the downlink signal received from the channel control device 30 via the path D1 to the second base station 20 to the mobile station 101. However, this is not limited to this, and the first base station 10 may give priority to transmitting the downlink signal from the channel control device 30 to the mobile stations 101, 102, and 103, or the downlink signal as a base station loopback or channel control device loopback signal to the mobile station 101.

[0048] Here, the mobile station 102 has been described as an example, but the same applies to the mobile station 101 and the mobile station 103.

[0049] Furthermore, the second base station 20 prioritizes signals transmitted from the second base station 20 to the line controller 30 over signals received from the mobile stations 201 to 203 belonging to the second base station 20, The signal may be transmitted to the mobile station 201 located in the overlapping area A12 and belonging to the second base station 20.

[0050] 3 and 5, a signal transmitted from the second base station 20 to the first base station 10 will be described in detail. Fig. 5 is an explanatory diagram for explaining the processing of the communication system according to the second embodiment.

[0051] 3 and 5, the second base station 20 and the mobile station 101 located in the overlapping area A12 are wirelessly connected, so the mobile station 101 transmits an uplink signal to the second base station 20 via a wireless path U12. The second base station 20 also transmits the received signal to the mobile station 202 via a wireless path D23. In response to the received signal, or of its own accord, the mobile station 202 transmits an uplink signal to the second base station 20 via the wireless path U23. The uplink signal transmitted by the mobile station 202 is then transmitted as a downlink signal from the second base station 20 to the mobile stations 201 and 203 in the wireless area A2. This is base station return.

[0052] When the wired routes U2 and D2 connecting the channel control device 30 and the second base station 20 are not disconnected, an uplink signal transmitted by the mobile station 202 is transmitted from the second base station 20 to the channel control device 30 via the wired route U2, the channel control device 30 transmits the uplink signal to the second base station 20 via the wired route D2, and the second base station 20 transmits the signal as a downlink signal to the mobile stations 201 and 203 in the wireless area A2. This is a channel control device loopback. In the case of a channel control device loopback, an uplink signal transmitted by a mobile station located in the wireless area of ​​another base station, for example, mobile station 202, is also transmitted to the mobile stations 101, 102, and 103 under the control of the first base station 10. It should be noted that when the wired route U2 and the wired route D2 are disconnected, the line control device loopback is not executed.

[0053] That is, as shown in FIGS. 3 and 5, the second base station 20 (1) Downlink signals transmitted from the line control device 30 to the mobile station 101 via the radio path U12 and directed to the mobile stations 201, 202, and 203; (2) A base station return signal in response to an uplink signal transmitted from the mobile station 202 via the wireless path U23; may be sent.

[0054] In this case, the second base station 20 transmits the uplink signal received from the mobile station 101, in other words, the downlink signal transmitted from the line control device 30, to the mobile stations 201, 202, and 203 in priority to the base station return signal for the uplink signal transmitted from the mobile station 202. In FIG. 5, the above-mentioned signals (1) and (2) are shown along the wireless path.

[0055] 3 and 6, the second base station 20 (3) an uplink signal transmitted from the mobile station 202 to the channel control device 30; (4) an uplink signal transmitted from the mobile station 203 via the path U33 to the mobile stations 201 and 202; may be received.

[0056] In this case, the second base station 20 prioritizes the signal to be transmitted to the channel control device 30 among the uplink signals from the mobile station 202, and transmits the signal to the mobile station 201 over the uplink signal transmitted from the mobile station 203 to the mobile stations 201 and 202. The mobile station 201 transmits the received signal as an uplink signal to the first base station 10 via the wireless path U22. In FIG. 6, the above-mentioned signals (3) and (4) are shown along the wireless path.

[0057] Here, the mobile station 202 has been described as an example, but the same applies to the mobile station 203.

[0058] <Transmission restrictions> So far, we have explained which signals the first base station 10 and the second base station 20 give priority to transmitting to mobile stations when the line control device 30 and the second base station 20 communicate via the first base station 10. Here, the first base station 10 and the second base station 20 may control the mobile stations belonging to each base station 10 not to transmit uplink signals while communicating with the line control device 30 (transmission restriction).

[0059] <Delayed Send> Furthermore, by recording the received downlink communication information, the mobile stations 101-103 and 201-203 can transmit signals with a delayed transmission time relative to the reception time. This allows the mobile stations 101-103 and 201-203 to transmit the transmission signals recorded while they were subject to transmission restriction after the transmission restriction is lifted (delayed transmission).

[0060] <Transmission restriction identification code (downstream)> Here, a signal transmitted from a mobile station located in the overlapping area A12 and belonging to the first base station 10 to the second base station 20 includes a transmission restriction identification code. When the first base station 10 receives a signal with a transmission restriction identification code, the first base station 10 may control itself so as not to transmit a downlink return signal to the mobile station belonging to the first base station 10.

[0061] 3 and 7, a signal to which a transmission restriction identification code is assigned and which is transmitted from a mobile station belonging to the first base station 10 to the second base station 20 will be described. FIG. 7 is an explanatory diagram for describing processing in a communication system according to the second embodiment. In FIG. 7, a solid arrow indicates that a signal is transmitted via the path indicated by the arrow, whereas a dashed arrow indicates that a signal is not transmitted via the path indicated by the arrow. For example, in the solid arrow indicating the wireless path D13 in FIG. 7, the first base station 10 transmits a downlink signal received from the line controller 30 via the wired path D1 to the mobile station 102 via the wireless path D13. On the other hand, in the dashed arrow indicating the wireless path D13 in FIG. 7, the first base station 10 does not transmit an uplink signal to which a transmission restriction identification code is assigned and which is received from the mobile station 101 via the wireless path U11 to the mobile station 102 via the wireless path D13. Hereinafter, a more specific description will be given with reference to FIG. 3 and 7.

[0062] 3 and 7, the line control device 30 and the first base station 10 are connected by wire. Therefore, the line control device 30 transmits a downlink signal to the first base station 10 via a wired path D1. The first base station 10 is connected by wireless to the mobile stations 101 and 102 belonging to the first base station 10. Therefore, the first base station 10 transmits a downlink signal received from the line control device 30 via the wired path D1 to the mobile station 101 via a wireless path D11. Furthermore, the first base station 10 transmits a downlink signal received from the line control device 30 via the wired path D1 to the mobile station 102 via a wireless path D13. Note that the wireless paths D11 and D13 are based on transmission from the first base station 10 at the same frequency.

[0063] The mobile station 101 transmits the signal transmitted from the first base station 10 to the second base station 20 via the wireless path U12. At this time, the mobile station 101 simultaneously transmits the signal transmitted from the first base station 10 to the first base station 10 via the wireless path U11. A transmission restriction identification code is attached to the signal transmitted from the mobile station 101.

[0064] The first base station 10 receives an uplink signal with a transmission restriction identification code attached from the mobile station 101 via the wireless path U11. When the first base station 10 receives an uplink signal with a transmission restriction identification code attached, it controls itself so as not to transmit a downlink return signal corresponding to the uplink signal. In other words, the first base station 10 does not transmit the uplink signal with a transmission restriction identification code attached, received from the mobile station 101 via the wireless path U11, to the mobile station 102 via the wireless path D13. In other words, the transmission restriction identification code is identification information attached by the first base station 10 to the mobile stations 101 and 102 so that the first base station 10 distinguishes a signal directed from the line control device 30 to the second base station 20 from an uplink signal from the mobile station 101 to the first base station 10, and controls the signal so as not to be transmitted twice within the wireless area A1. Here, the mobile station 102 has been taken as an example for explanation, but the same applies to the mobile station 103.

[0065] <Transmission restriction identification code (upstream)> Furthermore, a signal transmitted from a mobile station located in the overlapping area A12 and belonging to the second base station 20 to the first base station 10 includes a transmission restriction identification code. When the second base station 20 receives a signal with a transmission restriction identification code, the second base station 20 may control itself so as not to transmit a downlink return signal to the mobile station belonging to the second base station 20.

[0066] 3 and 8, a signal to which a transmission restriction identification code is assigned and which is transmitted from a mobile station belonging to the second base station 20 to the first base station 10 will be described. FIG. 8 is an explanatory diagram for describing processing in a communication system according to the second embodiment. In FIG. 8, a solid arrow indicates that a signal is transmitted via the path indicated by the arrow, whereas a dashed arrow indicates that a signal is not transmitted via the path indicated by the arrow. For example, in the solid arrow indicating the wireless path D23 in FIG. 8, the second base station 20 transmits a signal received from the line controller 30 via the mobile station 101 to the mobile station 202 via the wireless path D23. On the other hand, in the dashed arrow indicating the wireless path D23 in FIG. 8, the second base station 20 does not transmit to the mobile station 202 an uplink signal to which a transmission restriction identification code is assigned and which is received from the mobile station 201 via the wireless path U21. Hereinafter, a more specific description will be given with reference to FIG. 3 and 8.

[0067] As shown in FIGS. 3 and 8, the second base station 20 and the mobile station 101 located in the overlapping area A12 are wirelessly connected only via a wireless path U12 for uplink communication from the mobile station 101 to the second base station 20. The mobile station 101 transmits an uplink signal to the second base station 20 via the wireless path U12. The second base station 20 is wirelessly connected in both uplink and downlink directions with the mobile stations 201 and 202 belonging to the second base station 20. The second base station 20 transmits a signal to the mobile station 201 via the wireless path D21 to respond to a signal received from the line control device 30 via the mobile station 101. Furthermore, the second base station 20 transmits a signal received from the line control device 30 via the mobile station 101 to the mobile station 202 via the wireless path D23. Note that the wireless paths D21 and D23 are based on transmissions from the second base station 20 using the same frequency.

[0068] The mobile station 201 transmits the signal transmitted from the second base station 20 to the first base station 10 via the wireless path U22. At this time, the mobile station 201 simultaneously transmits the signal transmitted from the second base station 20 to the second base station 20 via the wireless path U21. The signal transmitted from the mobile station 201 is assigned a transmission restriction identification code.

[0069] The second base station 20 receives an uplink signal with a transmission restriction identification code attached from the mobile station 201 via the wireless path U21. When the second base station 20 receives an uplink signal with a transmission restriction identification code attached, the second base station 20 controls itself so as not to transmit a downlink return signal corresponding to the uplink signal. In other words, the second base station 20 does not transmit the uplink signal with a transmission restriction identification code attached, received from the mobile station 201 via the wireless path U21, to the mobile station 202 via the wireless path D23. In other words, the transmission restriction identification code is identification information attached to the signal that the second base station 20 intended for the line control device 30 for the first base station 10, to control the signal so that it is not transmitted in duplicate to the mobile stations 201 and 202 within the wireless area A2. Here, the mobile station 202 has been described as an example, but the same applies to the mobile station 203.

[0070] In the wireless communication system 200 according to the second embodiment, the first base station 10 includes a first receiving unit 10R for receiving a signal transmitted from the second base station 20 to the line control device 30 via a mobile station 201 located in the overlapping area A12 and belonging to the second base station 20. The second base station 20 also includes a second receiving unit 20R for receiving a signal transmitted from the line control device 30 via the first base station 10 via the mobile station 101 located in the overlapping area A12 and belonging to the first base station 10. This allows bidirectional communication between the line control device 30 and the second base station 20 via the mobile station 101 located in the overlapping area A12 and belonging to the first base station 10 and the mobile station 201 located in the overlapping area A12 and belonging to the second base station 20. Therefore, in an emergency in which the communication path between the line control device 30 and the second base station 20 is disconnected, it is possible to restore communication between the command center H1 and the second base station 20 with a simpler configuration.

[0071] Furthermore, in the wireless communication system 200 according to the second embodiment, only the reception function of the base station is added, and there is no need for additional costs such as obtaining a license including antenna specification, or transmission quality control. The power consumption required for the transmission function can also be reduced. Therefore, communication between the command center H1 and the second base station 20 can be performed with an inexpensive and energy-saving configuration.

[0072] Furthermore, the antennas of the first receiving unit 10R and the second receiving unit 20R can be made directive toward the overlapping area A12 to obtain a gain, so that the transmission power of the mobile stations 101 and 201 that communicate with each other by radio can be reduced by the amount of the gain. If the mobile stations 101 and 201 are powered by secondary batteries, the battery life can be extended.

[0073] <Disconnection detection> So far, we have explained the case where the communication between the line control device 30 and the second base station 20 is disconnected. In order to detect that the communication between the line control device 30 and the first base station 10 or the second base station 20 has been disconnected, a check (health check) is periodically performed to see if the communication is possible between the line control device 30 and the first base station 10 or the second base station 20.

[0074] <Detecting disconnection in downstream communication> For example, in downlink communication transmitted from the line control device 30 to the second base station 20, the line control device 30 has a timer and periodically transmits a confirmation signal (downlink communication confirmation signal) with predetermined content to the second base station 20. The second base station 20 has a timer and determines that the downlink signal from the line control device 30 has been received normally if the downlink communication confirmation signal can be received in the time period when the downlink communication confirmation signal is expected to arrive (expected reception time period).

[0075] On the other hand, if the second base station 20 cannot receive a downlink communication confirmation signal during the expected time period for receiving the communication confirmation signal, it determines that the downlink signal from the line controller has not been received properly. Also, if the received downlink communication confirmation signal differs from the predetermined content that should be received from the line controller 30, the second base station 20 determines that the downlink signal from the line controller has not been received properly. In other words, it determines that the downlink communication from the line controller 30 to the second base station 20 has been disconnected.

[0076] The decision to disconnect may be made when an event in which reception is not possible during the scheduled reception time period occurs a predetermined number of times or more, or when an event in which the received content is different occurs a predetermined number of times or more.

[0077] <Detecting disconnection in upstream communication> For uplink communications transmitted from the second base station 20 to the line control device 30, the second base station 20 has a timer and periodically transmits a confirmation signal (uplink communication confirmation signal) with predetermined contents to the line control device 30. The line control device 30 has a timer and, if it can receive the uplink communication confirmation signal within a time period (expected reception time period) when the uplink communication confirmation signal is expected to arrive, determines that the uplink signal from the second base station 20 has been received normally.

[0078] On the other hand, if the line control device 30 cannot receive an uplink communication confirmation signal within the expected reception time period, it determines that the uplink signal from the second base station 20 has not been received normally. Also, if the received uplink communication confirmation signal differs from the predetermined content that should be received from the second base station 20, the line control device 30 determines that the uplink signal from the second base station 20 has not been received normally. In other words, it determines that the uplink communication from the second base station 20 to the line control device 30 has been disconnected.

[0079] The decision to disconnect may be made when an event in which reception is not possible during the scheduled reception time period occurs a predetermined number of times or more, or when an event in which the received content is different occurs a predetermined number of times or more.

[0080] <Relay by mobile station> 3, the case where the mobile station 101 or the mobile station 201 is located in the overlapping area A12 when the wired routes D2 and U2 are disconnected has been described. Here, the case where the mobile station 101 or the mobile station 201 is located in the overlapping area A12 when the wired routes D2 and U2 are disconnected and starts communication will be described.

[0081] <Relay request (second base station side)> When the second base station 20 determines that communication with the line control device 30 has been disconnected, it requests the mobile stations 201-203 in the communication area A2 to move to the overlapping area A12 and perform relay operation (relay request). For example, when the mobile station 201 receives the relay request, the mobile station 201 moves to the overlapping area A12 and starts relay operation. The mobile station 201 transmits to the second base station 20 a signal indicating that it has received the relay request from the second base station 20 (relay request receipt signal) and a signal indicating that it has started relay operation (relay operation start signal). When the second base station 20 receives at least one of the relay request receipt signal and the relay operation start signal from the mobile station 201, it may withdraw the relay requests to the other mobile stations 202 and 203.

[0082] The mobile station 201 also transmits a relay request acknowledgement signal and a relay operation start signal to the first base station 10. These signals may be common to the signals sent to the second base station 20. The first base station 10 transmits a relay request acceptance signal from the mobile station 201 and a relay operation start signal to the line controller 30. When the second base station 20 receives the relay request acknowledge signal and the relay operation start signal, the second base station 20 switches the communication transmitted from the second base station 20 to the line controller 30 to communication via the mobile station 201 and the first base station 10. When the line controller 30 receives the relay request acceptance signal and / or the relay operation start signal, it switches the communication transmitted from the second base station 20 to the line controller 30 to communication via the mobile station 201 and the first base station 10.

[0083] <Relay request (line control device side)> When the line control device 30 determines that the connection with the second base station 20 has been disconnected, it notifies the first base station 10, which has been pre-registered in the line control device, that the connection with the second base station 20 has been disconnected. Upon receiving the disconnection notification, the first base station 10 requests the mobile stations 101 to 103 in the communication area A1 to move to the overlapping area A12 and perform relay operation (relay request). Upon receiving the relay request, the mobile station 101 moves to the overlapping area A12 and starts relay operation. The mobile station 101 transmits to the first base station 10 a signal indicating that it has received a relay request from the first base station 10 (relay request receipt signal) and a signal indicating that it has started relay operation (relay operation start signal). When the first base station 10 receives at least one of the relay request receipt signal and the relay operation start signal from the mobile station 101, the first base station 10 may withdraw the relay request to the other mobile stations 102 and 103.

[0084] The first base station 10 transmits a relay request acceptance signal and a relay operation start signal to the line control device 30. When the line control device 30 receives the relay request acceptance signal and the relay operation start signal, it switches the communication transmitted from the line control device 30 to the second base station 20 to communication via the first base station 10 and the mobile station 101. The mobile station 101 also transmits a relay request acknowledgement signal and a relay operation start signal to the second base station 20. These signals may be the same as the signal sent to the first base station 10. When the second base station 20 receives a relay request receipt signal and a relay operation start signal from the mobile station 101, the second base station 20 switches the communication sent from the line control device 30 to the second base station 20 to communication via the first base station 10 and the mobile station 101.

[0085] <Embodiment 3> <Frequency channel switching mechanism> Hereinafter, a third embodiment of the present disclosure will be described with reference to the drawings. Fig. 9 is a schematic diagram showing a configuration of a wireless communication system according to the third embodiment. The wireless communication system 300 according to the third embodiment includes a command center H1, a line control device 30, a first base station 10, a second base station 20, mobile stations 101 to 104, and mobile stations 202 and 203.

[0086] Mobile stations 101 to 104 are located in any of the wireless areas A1 of the first base station 10 and belong to the first base station 10. On the other hand, mobile stations 202 and 203 are located in any of the wireless areas A2 of the second base station 20 and belong to the second base station 20.

[0087] The wireless communication system 300 shown in Fig. 9 differs from the wireless communication system 200 shown in Fig. 3 in that the mobile stations 101 and 104 belonging to the first base station are located in the overlapping area A12 and that the mobile stations have a frequency channel switching mechanism. Since the other configurations are the same as those of the wireless communication system 200 according to the second embodiment, a description thereof will be omitted. As in the first and second embodiments, the following describes a case where communication between the line control device 30 and the second base station 20 is disconnected.

[0088] 9, one of the mobile stations located in the overlapping area A12 has a frequency channel switching mechanism so that it can support frequency channels of multiple base stations. For example, the mobile station initially belongs to the first base station 10, then switches to the frequency channel of the second base station 20 and transitions to a state belonging to the second base station 20, and then transmits a signal transmitted from the second base station 20 to the first receiving unit 10R of the first base station 10.

[0089] A more detailed explanation will be given with reference to Figure 9. Because mobile station 101 and mobile station 104 belong to the first base station 10, the frequency channel of the first base station 10 is set for them, and they can communicate with the first base station 10. Furthermore, because mobile station 101 and mobile station 104 are located in overlapping area A12, they can also belong to the second base station 20 in terms of location. When mobile station 101 and mobile station 104 switch from the frequency channel of the first base station 10 to the frequency channel of the second base station 20 using a frequency channel switching mechanism, they can communicate with the second base station 20. Here, it is assumed that mobile station 104 has switched from the frequency channel of the first base station 10 to the frequency channel of the second base station 20.

[0090] In this case, as shown in Fig. 9, the line controller 30 transmits a downlink signal to the first base station 10 via a wired path D1. Furthermore, the first base station 10 transmits the downlink signal transmitted from the line controller 30 to the mobile station 101 via a wireless path D11. The mobile station 101 transmits an uplink signal to the second base station 20 via a wireless path U12. As a result, the second base station 20 receives the signal transmitted from the line controller 30 via the wired path D1, the wireless path D11, and the wireless path U12.

[0091] That is, the signal transmitted from the line controller 30 is received by the second receiving unit 20R via the mobile station 101 that is located in the overlapping area A12 and that belongs to the first base station 10.

[0092] 9, the second base station 20 transmits a downlink signal to the mobile station 104 via a wireless path D21. The mobile station 104 transmits an uplink signal to the first base station 10 via a wireless path U22. This allows the line control device 30 to receive the signal transmitted from the second base station 20 via the wireless path D21, the wireless path U22, and the wired path U1.

[0093] That is, a signal transmitted from the second base station 20 is received by the first receiver 10R via the mobile station 104 that is located in the overlapping area A12 and that belongs to the second base station 20.

[0094] 9, when the wired path connecting the line controller 30 and the second base station 20 is disconnected, the mobile station 104 switches from the frequency channel of the first base station 10 to the frequency channel of the second base station 20. This enables communication between the line controller 30 and the second base station 20. In other words, the mobile station 104 in the wireless communication system 300 shown in FIG. 9 plays the same role as the mobile station 201 in the wireless communication system 200 shown in FIG.

[0095] Here, as shown in FIG. 9, two mobile stations, 101 and 104, belonging to the first base station 10 are located in the overlapping area A12, but this is not limited to this, and it is sufficient that at least two or more mobile stations belonging to the first base station 10 are located in the overlapping area A12.

[0096] Furthermore, the at least two or more mobile stations located in the overlapping area A12 are not limited to mobile stations initially belonging to the first base station 10, and may be mobile stations belonging to the second base station 20. In this case, after switching from a state belonging to the second base station 20 to a state belonging to the first base station 10 by switching to the frequency channel of the first base station 10, the signal transmitted from the first base station 10 is transmitted to the second receiving unit 20R of the second base station 20.

[0097] For example, when the mobile station 202 and the mobile station 203 shown in FIG. 9 move and come to be located in the overlapping area A12, the mobile station 203 switches from the frequency channel of the second base station 20 to the frequency channel of the first base station 10. This enables communication between the line control device 30 and the second base station 20. In other words, the mobile station 203 plays the same role as the mobile station 101 in the wireless communication system 200 shown in FIG.

[0098] In this way, communication between the line control device 30 and the second base station 20 can be maintained by a mobile station under either the first base station 10 or the second base station 20. This has the effect of making instructions from the upper base station easier and faster.

[0099] <Embodiment 4> <Frequency channel switching> Hereinafter, a fourth embodiment of the present disclosure will be described with reference to the drawings. Fig. 10 is a schematic diagram showing the configuration of a wireless communication system according to the fourth embodiment.

[0100] The wireless communication system 400 shown in Fig. 10 differs from the wireless communication system 300 shown in Fig. 8 in that only the mobile station 101 belonging to the first base station is located in the overlapping area A12 and that the wireless communication system 400 does not include a first receiving unit 10R and a second receiving unit 20R. Since the other configurations are the same as those of the wireless communication system 300 according to the third embodiment, a description thereof will be omitted. As in the third embodiment, the following describes a case where communication between the line control device 30 and the second base station 20 is disconnected.

[0101] Since the mobile station 101 belongs to the first base station 10, it has the frequency channel of the first base station 10 and can communicate with the first base station 10. Furthermore, since the mobile station 101 is located in the overlapping area A12, it is also geographically capable of communicating with the second base station 20. Since the mobile station 101 has a frequency channel switching mechanism, when the mobile station 101 switches from the frequency channel of the first base station 10 to the frequency channel of the second base station 20, it belongs to the second base station 20 and can communicate with the second base station 20.

[0102] Here, the mobile station 101 having the frequency channel of the first base station 10 and communicating with the first base station 10 is referred to as mobile station 101A1. On the other hand, the mobile station 101 switching from the frequency channel of the first base station 10 to the frequency channel of the second base station 20 and communicating with the second base station 20 is referred to as mobile station 101A2. Naturally, the mobile station 101A2 is located in the same position as the mobile station 101A1, simply because it has switched from the frequency channel of the first base station 10 to the frequency channel of the second base station 20.

[0103] 10, an example will be described in which the mobile station 101 switches the frequency channel to enable communication between the line controller 30 and the second base station 20. Here, it is assumed that the mobile station 101 initially has the frequency channel of the first base station 10 and is a mobile station 101A1.

[0104] In this case, as shown in FIG. 10 , the line control device 30 transmits a signal to the second base station 20 as a downlink signal to the first base station 10 via a wired path D1. The first base station 10 transmits the signal transmitted from the line control device 30 to the mobile station 101A1 via a wireless path D11. Here, the mobile station 101A1 receives the signal from the first base station 10 and records the signal, then switches from the frequency channel of the first base station 10 to the frequency channel of the second base station 20, becoming the mobile station 101A2. The mobile station 101A2 transmits the recorded signal as an uplink signal to the second base station 20 via a wireless path U12. As a result, the second base station 20 can receive the signal transmitted from the line control device 30 via the wired path D1, the wireless path D11, and the wireless path U21.

[0105] 10, the second base station 20 transmits a signal to the line controller 30 as a downlink signal to the mobile station 101A2 via a wireless path D21. Here, the mobile station 101A2 receives a signal from the second base station 20, records the signal, and then switches from the frequency channel of the second base station 20 to the frequency channel of the first base station 10, becoming the mobile station 101A1. The mobile station 101A1 transmits the recorded signal as an uplink signal to the first base station 10 via a wireless path U11. This allows the line controller 30 to receive the signal transmitted from the second base station 20 via the wireless path D21, the wireless path U11, and the wired path U1.

[0106] 10 , the mobile station 101 receives a signal from the line controller 30 via the first base station 10 on the frequency channel of the first base station 10. After receiving the signal from the line controller 30, the mobile station 101 switches from the frequency channel of the first base station 10 to the frequency channel of the second base station 20 and transmits the received signal to the second base station 20.

[0107] Furthermore, after receiving a signal from the second base station 20 via the frequency channel of the second base station 20, the mobile station 101 switches from the frequency channel of the second base station 20 to the frequency channel of the first base station 10 and transmits the signal to the line controller 30 via the first base station 10. This enables communication between the line controller 30 and the second base station 20.

[0108] In this way, multiple mobile stations are not required, and a single mobile station can maintain communication between the line controller 30 and the second base station 20. This has the effect of enabling quick response with fewer hardware resources.

[0109] <Location determination by measuring the field strength of a mobile station> An example of determining whether a mobile station is located in the overlapping area A12 will be described. The mobile station may be equipped with a measurement unit that measures the field strength from the first base station 10 and the second base station 20. In this case, the mobile station determines whether it is located in the overlapping area A12 by comparing the value of the field strength of the radio waves transmitted from the first base station 10 and the second base station 20 measured by the measurement unit with a predetermined value of the field strength from the first base station 10 and the second base station 20 in the overlapping area A12.

[0110] More specifically, if the field strengths of the radio waves transmitted from the first base station 10 and the second base station 20 measured by the mobile station using its measurement unit are both within a predetermined range of field strengths from the first base station 10 and the second base station 20 in the overlapping area A12 (field strengths expected when the mobile station is located in the overlapping area A12), the mobile station is determined to be located in the overlapping area A12. If at least one of the field strengths from the first base station 10 and the second base station 20 measured by the mobile station using its measurement unit is not within the predetermined range of field strengths from the first base station 10 and the second base station 20 in the overlapping area A12, the mobile station is determined not to be located in the overlapping area A12.

[0111] In addition, the first base station 10 may have a first measurement unit (not shown) that measures the field strength of radio waves transmitted from mobile stations belonging to the first base station 10, and the second base station 20 may have a second measurement unit (not shown) that measures the field strength from mobile stations belonging to the second base station 20.

[0112] In this case, the mobile station determines whether it is located in the wireless area A1 of the first base station 10 by comparing a value measured using a first measurement unit (not shown) with a predetermined value of the field strength at the first base station 10 of radio waves transmitted from the mobile station in the overlapping area. On the other hand, the mobile station determines whether it is located in the wireless area A2 of the second base station 20 by comparing a value measured using a second measurement unit (not shown) with a predetermined value of the field strength at the second base station 20 of radio waves transmitted from the mobile station in the overlapping area A12. This determines whether the mobile station is located in the overlapping area A12. The first base station 10 reports to the mobile station the value measured using the first measurement unit (not shown), and the second base station 20 reports to the mobile station the value measured using the second measurement unit (not shown).

[0113] More specifically, if the value measured using a first measurement unit (not shown) is within a predetermined range of the electric field strength from the mobile station to the first base station in the overlapping area, the mobile station is determined to be located in wireless area A1. Furthermore, if the value measured using a second measurement unit (not shown) is within a predetermined range of the electric field strength from the mobile station to the second base station 20 in the overlapping area A12, the mobile station is determined to be located in wireless area A2. In other words, since the mobile station is located in both wireless area A1 and wireless area A2, the mobile station is determined to be located in overlapping area A12.

[0114] A part or all of the above-described embodiments can be described as, but not limited to, the following supplementary notes. (Appendix 1) A wireless communication system having a plurality of base stations including a first base station and a second base station controlled by a line control device, When communication between the line control device and the second base station is disconnected, communication is performed between the line control device and the second base station via at least one of a mobile station belonging to the first base station and a mobile station belonging to the second base station, which are located in an overlapping area where the wireless area of ​​the first base station and the wireless area of ​​the second base station overlap. Wireless communication system. (Appendix 2) the first base station is located in the overlapping area and has a first receiving unit that receives a signal transmitted from the second base station via a mobile station that belongs to the second base station; the second base station is located in the overlapping area and has a second receiving unit that receives a signal transmitted from the line control device via a mobile station that belongs to the first base station; 2. The wireless communication system of claim 1. (Appendix 3) The wireless communication system according to claim 1, wherein the mobile station has a frequency channel switching mechanism so as to be compatible with the frequency channel of the base station, and executes the following transmission processes (a) and (b): (a) when transmitting a signal from the line control device to the second base station, A mobile station located in the overlapping area After receiving a signal from the line control device via the first base station on the frequency channel of the first base station, the frequency channel of the first base station is switched to the frequency channel of the second base station, and the received signal is transmitted to the second base station. (b) when transmitting a signal from the second base station to the line control device, A mobile station located in the overlapping area After receiving a signal from the second base station via the frequency channel of the second base station, the frequency channel is switched from the frequency channel of the second base station to the frequency channel of the first base station and transmitted to the line control device via the first base station. (Appendix 4) any one of the mobile stations located in the overlapping area has a frequency channel switching mechanism so as to be compatible with the frequency channel of the base station, and after switching from a state in which it belongs to the first base station to a frequency channel of the second base station and transitioning to a state in which it belongs to the second base station, transmits a signal transmitted from the second base station to the first receiving unit of the first base station; 3. The wireless communication system of claim 2. (Appendix 5) any one of the mobile stations located in the overlapping area has a frequency channel switching mechanism so as to be compatible with the frequency channel of the base station, and after switching from a state in which it belongs to the second base station to a frequency channel of the first base station and transitioning to a state in which it belongs to the first base station, transmits the signal transmitted from the first base station to the second receiving unit of the second base station; 3. The wireless communication system of claim 2. (Appendix 6) The first base station giving priority to the signal transmitted from the line control device to the second base station, transmitting to a mobile station located in the overlapping area and belonging to the first base station; 3. A wireless communication system according to claim 1 or 2. (Appendix 7) The second base station giving priority to a signal transmitted from the second base station to the line controller, transmitting to a mobile station located in the overlapping area and belonging to the second base station; 3. A wireless communication system according to claim 1 or 2. (Appendix 8) a signal transmitted from a mobile station located in the overlapping area and belonging to the first base station to the second base station includes an identification code; When the first base station receives the signal to which the identification code is attached, Controlling the first base station so as not to transmit a signal to a mobile station belonging to the first base station; 3. A wireless communication system according to claim 1 or 2. (Appendix 9) a signal transmitted from a mobile station located in the overlapping area and belonging to the second base station to the first base station includes an identification code; When the second base station receives the signal to which the identification code is attached, controlling the second base station so as not to transmit a signal to a mobile station belonging to the second base station; 3. A wireless communication system according to claim 1 or 2. (Appendix 10) the mobile station includes a measurement unit for measuring field strength from the first base station and the second base station; determining whether the mobile station is located in the overlapping area by comparing the value measured by the measurement unit with a predetermined value of the electric field strength from the first base station and the second base station in the overlapping area; 3. A wireless communication system according to claim 1 or 2. (Appendix 11) the first base station has a first measurement unit that measures field strength from a mobile station that belongs to the first base station; the second base station has a second measurement unit that measures field strength from a mobile station that belongs to the second base station, comparing the field strength value measured by the first measurement unit with a predetermined value of field strength from the mobile station to the first base station in the overlapping area; By comparing the value measured by the second measurement unit with a predetermined value of the electric field strength from the mobile station to the second base station in the overlapping area, determining whether the vehicle is located in the overlapping area; 3. A wireless communication system according to claim 1 or 2. (Appendix 12) A wireless communication method between a line control device and a base station controlled by the line control device, selecting a mobile station located in an overlapping area where a wireless area of ​​a first base station and a wireless area of ​​the second base station overlap, and belonging to the first base station or the second base station, when communication between the line control device and a second base station is disconnected; performing communication between the line control device and the second base station via the selected mobile station; Wireless communication method. (Appendix 13) the first base station is located in the overlapping area and receives a signal transmitted from the second base station via a mobile station belonging to the second base station; the second base station is located in the overlapping area and receives a signal transmitted from the line control device via a mobile station belonging to the first base station; 13. The wireless communication method of claim 12. (Appendix 14) The wireless communication method according to claim 12, wherein the mobile station has a frequency channel switching mechanism to be compatible with the frequency channel of the base station, and executes the following transmission processes (a) and (b): (a) when transmitting a signal from the line control device to the second base station, A mobile station located in the overlapping area After receiving a signal from the line control device via the first base station on the frequency channel of the first base station, the frequency channel of the first base station is switched to the frequency channel of the second base station, and the received signal is transmitted to the second base station. (b) when transmitting a signal from the second base station to the line control device, A mobile station located in the overlapping area After receiving a signal from the second base station via the frequency channel of the second base station, the frequency channel is switched from the frequency channel of the second base station to the frequency channel of the first base station and transmitted to the line control device via the first base station. (Appendix 15) any one of the mobile stations located in the overlapping area has a frequency channel switching mechanism so as to be compatible with the frequency channel of the base station, and after switching from a state in which it belongs to the first base station to a frequency channel of the second base station and transitioning to a state in which it belongs to the second base station, transmits a signal transmitted from the second base station to the first receiving unit of the first base station; 14. The wireless communication method of claim 13. (Appendix 16) any one of the mobile stations located in the overlapping area has a frequency channel switching mechanism so as to be compatible with the frequency channel of the base station, and after switching from a state in which it belongs to the second base station to a frequency channel of the first base station and transitioning to a state in which it belongs to the first base station, transmits the signal transmitted from the first base station to the second receiving unit of the second base station; 14. The wireless communication method of claim 13. (Appendix 17) The first base station giving priority to the signal transmitted from the line control device to the second base station, transmitting to a mobile station located in the overlapping area and belonging to the first base station; 14. The wireless communication method according to claim 12 or 13. (Appendix 18) The second base station giving priority to a signal transmitted from the second base station to the line controller, transmitting to a mobile station located in the overlapping area and belonging to the second base station; 14. The wireless communication method according to claim 12 or 13. (Appendix 19) a signal transmitted from a mobile station located in the overlapping area and belonging to the first base station to the second base station includes an identification code; When the first base station receives the signal to which the identification code is attached, Controlling the first base station so as not to transmit a signal to a mobile station belonging to the first base station; 14. The wireless communication method according to claim 12 or 13. (Appendix 20) a signal transmitted from a mobile station located in the overlapping area and belonging to the second base station to the first base station includes an identification code; When the second base station receives the signal to which the identification code is attached, controlling the second base station so as not to transmit a signal to a mobile station belonging to the second base station; 14. The wireless communication method according to claim 12 or 13. (Appendix 21) the mobile station measures the field strength of the current transmitted from the first base station and the second base station; determining whether the mobile station is located in the overlapping area by comparing the measured field strength value with a predetermined value of field strength from the first base station and the second base station in the overlapping area; 14. The wireless communication method according to claim 12 or 13. (Appendix 22) the first base station measures a field strength from a mobile station belonging to the first base station; the second base station measures a field strength from a mobile station belonging to the second base station; comparing the value measured by the first base station with a predetermined value of the electric field strength from the mobile station to the first base station in the overlapping area; By comparing the value measured by the second base station with a predetermined value of the electric field strength from the mobile station to the second base station in the overlapping area, determining whether the vehicle is located in the overlapping area; 14. The wireless communication method according to claim 12 or 13. [Explanation of symbols]

[0115] 10 1st base station 20 2nd base station 30 Line control device 100, 200, 300, 400 wireless communication systems 101, 102, 103, 104, 201, 202, 203 mobile stations 101A1, 101A2 Mobile station A1 Wireless Area A2 Wireless Area A12 Overlapping Area L1, L2, D1, D2, U1, U2 Wired Routes L11, L12, L21, L22 wireless paths D11, D13, D21, D23 wireless paths U11, U12, U13, U21, U22, U23 wireless paths H1 Command Headquarters

Claims

1. A wireless communication system having a plurality of base stations including a first base station and a second base station controlled by a line control device, When communication between the line control device and the second base station is disconnected, communication is performed between the line control device and the second base station via at least one of a mobile station belonging to the first base station and a mobile station belonging to the second base station, which are located in an overlapping area where a wireless area of ​​the first base station and a wireless area of ​​the second base station overlap, the mobile station includes a measurement unit for measuring field strengths from the first base station and the second base station; determining whether or not the mobile station is located in the overlapping area by comparing the value measured by the measurement unit with a predetermined value of the electric field strength from the first base station and the second base station in the overlapping area; Wireless communication system.

2. A wireless communication system having a plurality of base stations including a first base station and a second base station controlled by a line control device, When communication between the line control device and the second base station is disconnected, communication is performed between the line control device and the second base station via at least one of a mobile station belonging to the first base station and a mobile station belonging to the second base station, which are located in an overlapping area where a wireless area of ​​the first base station and a wireless area of ​​the second base station overlap, the first base station has a first measurement unit that measures field strength from a mobile station that belongs to the first base station; the second base station has a second measurement unit that measures field strength from a mobile station that belongs to the second base station, comparing the field strength value measured by the first measurement unit with a predetermined value of field strength from the mobile station to the first base station in the overlapping area; By comparing the electric field strength value measured by the second measurement unit with a predetermined value of the electric field strength from the mobile station to the second base station in the overlapping area, determining whether the mobile station is located in the overlap area; Wireless communication system.

3. 3. The wireless communication system according to claim 1, wherein the mobile station has a frequency channel switching mechanism so as to be compatible with the frequency channel of the base station, and executes the following transmission processes (a) and (b): (a) when transmitting a signal from the line control device to the second base station, A mobile station located in the overlapping area After receiving a signal from the line control device via the first base station on the frequency channel of the first base station, the frequency channel of the first base station is switched to the frequency channel of the second base station, and the received signal is transmitted to the second base station. (b) when transmitting a signal from the second base station to the line control device, A mobile station located in the overlapping area After receiving a signal from the second base station via the frequency channel of the second base station, the frequency channel of the second base station is switched to the frequency channel of the first base station and transmitted to the line control device via the first base station.

4. the first base station is located in the overlapping area and has a first receiving unit that receives a signal transmitted from the second base station via a mobile station that belongs to the second base station; the second base station is located in the overlapping area and has a second receiving unit that receives a signal transmitted from the line control device via a mobile station that belongs to the first base station; 3. The wireless communication system according to claim 1 or 2.

5. any one of the mobile stations located in the overlapping area has a frequency channel switching mechanism so as to be compatible with the frequency channel of the base station, and after switching from a state in which it belongs to the first base station to a frequency channel of the second base station and transitioning to a state in which it belongs to the second base station, transmits a signal transmitted from the second base station to the first receiving unit of the first base station; 5. The wireless communication system according to claim 4.

6. any one of the mobile stations located in the overlapping area has a frequency channel switching mechanism so as to be compatible with the frequency channel of the base station, and after switching from a state in which it belongs to the second base station to a state in which it belongs to the first base station by switching to the frequency channel of the first base station, transmits a signal transmitted from the first base station to the second receiving unit of the second base station; 5. The wireless communication system according to claim 4.

7. A wireless communication method between a line control device and a base station controlled by the line control device, selecting a mobile station located in an overlapping area where a wireless area of ​​a first base station and a wireless area of ​​a second base station overlap, and belonging to the first base station or the second base station, when communication between the line control device and a second base station is disconnected; performing communication between the line control device and the second base station via the selected mobile station; the mobile station includes a measurement unit for measuring field strengths from the first base station and the second base station; determining whether or not the mobile station is located in the overlapping area by comparing the value measured by the measurement unit with a predetermined value of the electric field strength from the first base station and the second base station in the overlapping area; Wireless communication method.

8. A wireless communication method between a line control device and a base station controlled by the line control device, selecting a mobile station located in an overlapping area where a wireless area of ​​a first base station and a wireless area of ​​a second base station overlap, and belonging to the first base station or the second base station, when communication between the line control device and a second base station is disconnected; performing communication between the line control device and the second base station via the selected mobile station; the first base station has a first measurement unit that measures field strength from a mobile station that belongs to the first base station; the second base station has a second measurement unit that measures field strength from a mobile station that belongs to the second base station, comparing the field strength value measured by the first measurement unit with a predetermined value of field strength from the mobile station to the first base station in the overlapping area; By comparing the electric field strength value measured by the second measurement unit with a predetermined value of the electric field strength from the mobile station to the second base station in the overlapping area, determining whether the mobile station is located in the overlap area; Wireless communication method.

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