JP2021013080A - Wireless communication system - Google Patents

Abstract

To provide a wireless communication system, even if a disconnection failure occurs in an LCX, capable of continuing wireless communication in all areas where the LCX after the occurrence place of the disconnection failure is provided.SOLUTION: A wireless communication system according to the present invention includes: a base station 1 and a plurality of repeaters 31 to 33 connected in series via an LCX; and a mobile body 5 that performs LCX wireless communication, which is wireless communication via the LCX, with the base station 1. When it is detected that the repeater 31 cannot perform LCX wireless communication, the base station 1 instructs at least two switches among the base station and the repeaters connected to both ends of the LCX that cannot perform LCX wireless communication to switch so as to perform spatial wave wireless communication.SELECTED DRAWING: Figure 1

Description

The present invention relates to a wireless communication system that performs wireless communication between a base station and a mobile body using a Leaky Coaxial Cable (hereinafter referred to as LCX).

Conventionally, a wireless communication system that performs wireless communication between a base station and a mobile body using LCX is known (see, for example, Non-Patent Document 1). Further, in a wireless communication system using LCX, when a failure occurs in LCX, a technique for detecting a location where the failure occurs is disclosed (see, for example, Patent Document 1). Here, the disconnection failure in the LCX means that the LCX is disconnected and wireless communication cannot be performed. In the following, a failure that occurs in a device or transmission line provided as a ground facility in a wireless communication system will be described as a failure in LCX.

Japanese Patent No. 6233508

Toshihiko Kishimoto and Shin Sasaki, "LCX Communication System", Institute of Electronics, Information and Communication Engineers, August 20, 1982

In a wireless communication system using LCX, when a failure occurs in LCX, wireless communication cannot be performed in the area where LCX is provided after the location where the failure occurs. Here, the area where the LCX is provided after the location where the failure occurs is the area where the LCX is provided on the side away from the base station with respect to the location where the failure occurs. Therefore, even if a failure occurs in the LCX, it is required to continue wireless communication in all areas where the LCX is provided after the location where the failure occurs.

In Patent Document 1, it is possible to detect the location where the failure occurs, but until the failure is repaired and the LCX is restored, wireless communication can be performed in the area where the LCX is provided after the location where the failure occurred. There is a problem that it cannot be done.

The present invention has been made to solve such a problem, and even if a failure occurs in the LCX, wireless communication can be performed in all areas where the LCX is provided after the location where the failure occurs. The purpose is to provide a wireless communication system that can be continued.

In order to solve the above problems, the wireless communication system according to the present invention includes a base station and a plurality of repeaters connected in series via an LCX (Leaky Coaxial Cable), and wirelessly to the base station via the LCX. It is a wireless communication system including a mobile body that performs LCX wireless communication, which is communication, and each of the base station and each repeater is a space wave antenna that performs space wave wireless communication, which is wireless communication by the space wave wireless system. When the repeater detects that the LCX wireless communication cannot be performed, the base station is equipped with a switch for switching to either LCX wireless communication or space wave wireless communication. Instructs at least two of the base stations and each repeater connected to both ends to switch to perform space wave wireless communication.

According to the present invention, when the wireless communication system detects that the repeater cannot perform LCX wireless communication, the base station is connected to both ends of the LCX which cannot perform LCX wireless communication, and each relay. Since at least two switches of the machine are instructed to switch to perform space wave wireless communication, even if a failure occurs in the LCX, the LCX after the location where the failure occurs is provided. It is possible to continue wireless communication in all areas.

It is a figure which shows an example of the structure of the wireless communication system by Embodiment 1 of this invention. It is a figure which shows an example of the structure of the wireless communication system by Embodiment 1 of this invention. It is a figure which shows an example of the structure of the wireless communication system by Embodiment 1 of this invention. It is a figure which shows an example of the structure of the wireless communication system by Embodiment 3 of this invention. It is a figure which shows an example of the structure of the wireless communication system by Embodiment 3 of this invention. It is a figure which shows an example of the structure of the wireless communication system by Embodiment 4 of this invention. It is a figure which shows an example of the structure of the wireless communication system by Embodiment 4 of this invention. It is a figure which shows an example of the structure of the wireless communication system by a related technology. It is a figure which shows an example of the structure of the wireless communication system by a related technology.

Embodiments of the present invention will be described below with reference to the drawings. In the related technology and each embodiment described below, the case where the radio signal is transmitted from the base station to the mobile body will be described, but the same applies to the case where the radio signal is transmitted from the mobile body to the base station.

<Related technology>
The related technology related to the present embodiment will be described.

FIG. 8 is a diagram showing an example of the configuration of a wireless communication system according to the related technology.

As shown in FIG. 8, the wireless communication system transmits LCX to base station 1 and a plurality of repeaters 31, 32, 33 connected in series via LCX2a, 2b, 2c, 2d, and base station 1. It includes a mobile body 5 that performs wireless communication via the mobile body 5. Hereinafter, wireless communication via LCX is referred to as LCX wireless communication.

In the wireless communication system, the base station 1, LCX2a, 2b, 2c, 2d, the repeaters 31, 32, 33, and the monitoring line 4 form a terrestrial wireless system. The terrestrial wireless system is also called terrestrial equipment.

The base station 1 includes a control unit 1a and a radio 1b. The control unit 1a controls each component (not shown) including the radio 1b. Further, the control unit 1a monitors the status of the repeaters 31, 32, 33 via the monitoring line 4 and controls the repeaters 31, 32, 33. The radio 1b is connected to the LCX2a.

The repeater 31 includes a control unit 31a and an amplifier 31b. The control unit 31a controls each component (not shown) including the amplifier 31b. The amplifier 31b amplifies the radio signal attenuated by the LCX2a. The other repeaters 32 and 33 also have the same configuration.

The mobile body 5 includes a control unit 5a, a radio 5b, and an LCX antenna 5c. The control unit 5a controls each component (not shown) including the radio 5b. The radio 5b uses the LCX antenna 5c to perform LCX wireless communication with the base station 1.

For example, as shown in FIG. 9, when a disconnection failure 6 occurs in the LCX2a, LCX wireless communication is performed in the non-communication area 7 provided with the LCX2a, LCX2b, LCX2c, and LCX2d after the location where the disconnection failure 6 occurs. Can not be done.

This embodiment is made for solving the problem of such related technology, and will be described in detail below.

<Embodiment 1>
FIG. 1 is a diagram showing an example of a configuration of a wireless communication system according to the first embodiment.

As shown in FIG. 1, the base station 1 is characterized by including a switch 1c and a space wave antenna 1d. Since other configurations are the same as those of the base station 1 of the related technology shown in FIG. 8, detailed description thereof will be omitted here.

The space wave antenna 1d is connected to the switch 1c and is used when performing wireless communication by the space wave wireless system. In the following, wireless communication by the space wave wireless system will be referred to as space wave wireless communication. The switch 1c can switch to either the LCX2a or the space wave antenna 1d, and usually LCX2a is selected. That is, the switch 1c switches to either LCX wireless communication or space wave wireless communication.

The repeater 31 is characterized by including switches 31c and 31d and space wave antennas 31e and 31f. Since other configurations are the same as those of the base station 1 of the related technology shown in FIG. 8, detailed description thereof will be omitted here.

The space wave antenna 31e is connected to the switch 31c and is used when performing space wave wireless communication. The space wave antenna 31f is connected to the switch 31d and is used when performing space wave wireless communication. The switch 31c can switch to either the LCX2a or the space wave antenna 31e, and usually LCX2a is selected. The switch 31d can switch to either the LCX2b or the space wave antenna 31f, and usually LCX2b is selected. That is, the switches 31c and 31d switch to either LCX wireless communication or space wave wireless communication. The other repeaters 32 and 33 also have the same configuration.

For example, as shown in FIG. 2, when a disconnection failure 6 occurs in the LCX2a, LCX wireless communication is performed in the non-communication area 7 provided with the LCX2a, LCX2b, LCX2c, and LCX2d after the location where the disconnection failure 6 occurs. Can not be done. Further, the closer the location where the interruption failure 6 occurs to the base station 1, the wider the communication impossible area 7.

In the wireless communication system according to the first embodiment, the wireless signal output by the wireless device 1b of the base station 1 is usually input to the repeater 31 via the switch 1c and the LCX2a. However, when the disconnection failure 6 as shown in FIG. 2 occurs, the radio signal output by the base station 1 is not input to the repeater 31 via the LCX2a. As described above, when the disconnection failure 6 occurs in the LCX2a, the LCX wireless communication cannot be performed between the base station 1 and the repeater 31.

The repeater 31 monitors the arrival of the radio signal output from the base station 1, and when the radio signal does not arrive, a disconnection failure 6 occurs in the LCX2a and the base station 1 and the repeater 31 It is possible to grasp that the LCX wireless communication cannot be performed between the two, that is, the disconnection failure 6 has occurred in the LCX2a. The base station 1 monitors the state of each repeater including the repeater 31 via the monitoring line 4, and the repeater 31 could not receive the radio signal by LCX wireless communication, that is, in LCX2a. It is possible to recognize that the disconnection failure 6 has occurred.

When the base station 1 recognizes that a disconnection failure has occurred in the LCX2a, the switch 1c is switched to the space wave antenna 1d, and the switch 31c is switched to the space wave antenna 1c with respect to the repeater 31 via the monitoring line 4. Give an instruction to switch to 31e. The repeater 31 switches the switch 31c to the space wave antenna 31e according to the instruction from the base station 1. As a result, the wireless communication between the base station 1 and the repeater 31 is switched from the LCX wireless communication via the LCX2a to the spatial wave wireless communication between the spatial wave antennas 1d and 31e, so that the interruption failure generated in the LCX2a occurs. 6 can be bypassed. As a result, as shown in FIG. 3, space wave wireless communication is performed between the base station 1 and the repeater 31 in the space wave wireless communication area 8, and the LCX wireless communication area 9 is between the repeaters 31, 32, and 33. LCX wireless communication will be performed, and the non-communication area 7 as shown in FIG. 2 will not exist.

In a wireless communication system using LCX, a plurality of LCXs may be laid at the same location to improve the fault tolerance of the wireless communication system. In such a case, it is not always necessary to configure the base station and all the repeaters as shown in FIG. 1, and the fault tolerance of the wireless communication system or the location where multiple LCXs cannot be installed in the same location is determined. The base station or repeater provided at the location to be improved may be configured as shown in FIG.

From the above, according to the first embodiment, when the repeater detects that the LCX wireless communication cannot be performed, the base station is connected to both ends of the LCX that cannot perform the LCX wireless communication. Instructs at least two switches of the station and each repeater to switch to perform space wave wireless communication. As a result, even if a disconnection failure occurs in the LCX, wireless communication can be continued in all areas where the LCX is provided after the location where the disconnection failure occurs.

In the above description, the case where a disconnection failure occurs in the LCX laid between the base station 1 and the repeater 31 has been described, but the present invention is not limited to this. The same applies to the case where a disconnection failure occurs in the LCX laid between the repeaters. This also applies to embodiments 2, 3 and 4 described below.

<Embodiment 2>
In the first embodiment, when a disconnection failure occurs in the LCX, the wireless communication in the area where the LCX is laid is switched from the LCX wireless communication to the space wave wireless communication. When changing to space wave wireless communication, there is a problem that the passing loss increases and the communication quality deteriorates. That is, when viewed from the mobile body, the level of the received radio signal is lowered. The second embodiment solves such a problem.

In the second embodiment, the control unit 1a and the radio 1b of the base station 1 and the control unit 5a and the radio 5b of the mobile body 5 each have a C / N ratio (Carrier to Noise ratio) switching function and C. It is characterized by having a / N switching detection function. Since other configurations and operations are the same as those in the first embodiment, detailed description thereof will be omitted here.

The C / N ratio is the carrier-to-noise ratio, and the fact that reception is possible with a low C / N ratio means that data can be decoded from the radio signal even if the received radio signal level is low. It means that there is.

The C / N ratio switching function means switching the control unit and the radio so that reception can be performed at a C / N ratio lower than that during normal LCX wireless communication when a disconnection failure occurs in LCX. Switching the C / N ratio is specifically realized by changing at least one of the modulation method, the transmission rate, and the error correction coding rate.

Next, the C / N ratio switching detection function will be described. For example, the base station 1 on the side that transmits the radio signal performs a C / N switching operation (here, the modulation method is assumed) of the control unit 1a and the radio 1b, but moves to receive the radio signal. In the body 5, there is no way to know that the disconnection disorder 6 has occurred in the LCX2a. Therefore, since the modulation method in the control unit 1a and the radio 1b of the base station 1 and the modulation method in the control unit 5a and the radio 5b of the mobile body 5 are different, the radio signal transmitted by the base station 1 in the mobile body 5 is different. Cannot be decrypted. When the C / N ratio switching detection function detects that the radio signal transmitted by the base station 1 cannot be decoded by the control unit 5a and the radio 5b of the mobile body 5, the C / N ratio switching function autonomously performs. The modulation method is switched so that the radio signal transmitted by the base station 1 can be decoded. As a result, the modulation method in the control unit 1a and the radio 1b of the base station 1 and the modulation method in the control unit 5a and the radio 5b of the mobile body 5 match.

From the above, according to the second embodiment, deterioration of communication quality can be suppressed even when the LCX wireless communication is switched to the space wave wireless communication.

<Embodiment 3>
In the second embodiment, a case where the C / N ratio is switched when performing space wave wireless communication has been described. In this case, the deterioration of the communication quality can be suppressed, but the transmission speed in the wireless communication is lowered. Further, for example, as shown in FIG. 2, when a disconnection failure 6 occurs in the LCX2a and space wave wireless communication is performed between the space wave antenna 1d of the base station 1 and the space wave antenna 31e of the repeater 31. Since the mobile body 5 performs space wave wireless communication with the base station 1 using the LCX antenna 5c having a directivity corresponding to the LCX, there is a problem that the communication quality is deteriorated. The third embodiment solves such a problem.

In the third embodiment, as shown in FIG. 4, the mobile body 5 includes a switch 5d and a space wave antenna 5e. Since other configurations and operations are the same as those in the second embodiment, detailed description thereof will be omitted here.

The space wave antenna 5e is connected to the switch 5d and is used when performing wireless communication by the space wave wireless system. The switch 5d can be switched to either the LCX antenna 5c or the space wave antenna 5e. Normally, the LCX antenna 5c is selected and LCX wireless communication is performed with the LCX2a, 2b, 2c, 2d. There is. That is, the switch 5d switches to either LCX wireless communication or space wave wireless communication.

The mobile body 5 constantly monitors the level of the radio signal received from the LCX2a, 2b, 2c, 2d, and when the C / N ratio switching detection function detects a decrease in the level of the received radio signal, the C / N ratio. The switching function autonomously switches the switch 5d to the space wave antenna 5e.

As described above, the LCX antenna 5c included in the mobile body 5 generally has directivity with respect to LCX2a, 2b, 2c, and 2d. Therefore, as shown in FIG. 5, in the space wave radio communication area 8, the level of the radio signal received by the mobile body 5 by the LCX antenna 5c is lowered. However, in the fifth embodiment, since the mobile body 5 performs the space wave wireless communication in the space wave wireless communication area 8 by using the space wave antenna 5e, it is possible to suppress the deterioration of the wireless communication quality.

From the above, according to the third embodiment, the mobile body 5 switches to the space wave antenna 5e in the space wave radio communication area 8 to perform space wave radio communication. Therefore, it is possible to suppress deterioration of wireless communication quality even in the space wave wireless communication area.

<Embodiment 4>
In the second embodiment, a method of decoding a radio signal even when the level of the radio signal is lowered when performing space wave radio communication has been described. In the fourth embodiment, a method of suppressing a decrease in the level of the radio signal when performing space wave wireless communication will be described.

In the fourth embodiment, as shown in FIG. 6, the base station 1 is provided with the frequency converter 1e, and the repeater 31 is provided with the frequency converters 31g and 31h. The repeaters 32 and 33 have the same configuration as the repeater 31. Since other configurations and operations are the same as those in the third embodiment, detailed description thereof will be omitted here.

The frequency converter 1e of the base station 1 converts the frequency fH of the radio signal output by the radio 1b into the frequency fL when performing space wave radio communication. Here, the frequency fH is a frequency when performing LCX wireless communication, and the frequency fL is a frequency when performing space wave wireless communication. Further, it is assumed that the relationship of frequency fH> frequency fL is established.

For example, as shown in FIG. 6, when the disconnection failure 6 occurs in the LCX2a, the base station 1 transmits a radio signal having a frequency of fL. The frequency converter 31g of the repeater 31 converts the frequency fL of the radio signal received by the space wave antenna 31e into the frequency fH. When the disconnection failure 6 occurs in the LCX2b, the frequency converter 31h of the repeater 31 converts the frequency fH of the radio signal received via the LCX2a into the frequency fL. In this case, space wave wireless communication is performed between the repeater 31 and the repeater 32.

As shown in FIG. 6, when the mobile body 5 exists in the LCX wireless communication area 9, the mobile body 5 performs LCX wireless communication with the LCX2b using the LCX antenna 5c. Further, as shown in FIG. 7, when the mobile body 5 exists in the space wave radio communication area 8, the mobile body 5 performs space wave radio communication with the base station 1 by using the space wave antenna 5e. At this time, the frequency converter 5f of the mobile body 5 converts the frequency fL of the radio signal received by the space wave antenna 5e into the frequency fH.

Generally, the lower the frequency of a radio signal, the smaller the radio wave propagation loss. According to the fourth embodiment, since the frequency of the radio signal in the space wave radio communication area is lowered, the propagation loss of the radio signal can be reduced, and the decrease in the radio signal level can be suppressed.

In the present invention, each embodiment can be freely combined, and each embodiment can be appropriately modified or omitted within the scope of the invention.

1 Base station, 1a control unit, 1b radio, 1c switch, 1d space wave antenna, 1e frequency converter, 2a, 2b, 2c, 2d LCX, 4 monitoring line, 5 mobile unit, 5a control unit, 5b radio Machine, 5c LCX antenna, 5d switch, 5e space wave antenna, 5f frequency converter, 6 failure, 7 incommunicable area, 8 space wave wireless communication area, 9 LCX wireless communication area, 31, 32, 33 relay Machine, 31a, 32a, 33a, 31b, 32b, 33b Amplifier, 31c, 31d, 32c, 32d, 33c, 33d Switcher, 31e, 31f, 32e, 32f, 33e, 33f Space wave antenna, 31g, 31h, 32g , 32h, 33g, 33h frequency converter.

Claims (5)

Wireless communication including a base station and a plurality of repeaters connected in series via an LCX (Leaky Coaxial Cable), and a mobile body that performs LCX wireless communication, which is wireless communication via the LCX, to the base station. It ’s a system,
Each of the base station and each of the repeaters
A space wave antenna that performs space wave wireless communication, which is wireless communication by the space wave wireless method,
A switch that switches to either the LCX wireless communication or the spatial wave wireless communication,
With
When the repeater detects that the LCX wireless communication cannot be performed, the base station is among the base station and each of the repeaters connected to both ends of the LCX that cannot perform the LCX wireless communication. A wireless communication system comprising instructing at least two of the changers to switch to perform the space wave wireless communication. The wireless communication system according to claim 1, wherein each of the base station and the mobile body performs the space wave wireless communication at a C / N ratio (Carrier to Noise ratio) lower than usual. Each of the base station and the mobile performs the spacewave radio communication at a lower C / N ratio than usual based on at least one of a modulation method, a transmission rate, and an error correction coding rate. 2. The wireless communication system according to claim 2. The moving body is
A space wave antenna that performs space wave wireless communication, which is wireless communication by the space wave wireless method,
A switch that switches to either the LCX wireless communication or the spatial wave wireless communication,
With
The switch according to any one of claims 1 to 3, wherein the switch of the mobile body switches to perform the space wave radio communication when passing through the area where the space wave radio communication is performed. Wireless communication system. Each of the base station, each repeater, and the mobile body includes a frequency converter that converts the frequency of a radio signal.
Each of the base station, the repeater, and the frequency converter of the mobile body is characterized in that the frequency of the space wave radio communication is lower than that of the LCX radio communication. , The wireless communication system according to claim 4.

Images