JPH08256103A - Communication system - Google Patents

Abstract

PURPOSE: To easily control the sending power of every mobile station and to improve the frequency using efficiency by controlling the sending power of a mobile station by itself based on its own position information that is detected and stored and in accordance with the relative distance between the mobile station and a base station. CONSTITUTION: A mobile station detects the longitude X, the latitude Y and the altitude Z, i.e., the position information of the mobile station itself by a GPS(global positioning system) receiver 7 and then uses this information as an address to have an access to a ROM 8. The position information (X, Y, Z) on the mobile station, the calculated relative distance between the mobile station and a base station corresponding to the position information on the base station, and the relative output data secured between the relative distance and the mobile station are stored in the ROM 8. Then the power sent from the mobile station is easily controlled with high economical properties via a power amplifier 3. As a result, the frequency using efficiency is improved.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a radio communication system comprising a base station and a plurality of mobile stations connected to the base station via radio lines, and more particularly, for example, code division multiple access. The present invention relates to a wireless communication system using a multiple access method having excellent frequency utilization efficiency such as a multiple access method or a spread spectrum multiple access method.

[0002]

2. Description of the Related Art Generally, a code division multiple access system (Code
Division Multipule Access: CDMA system, or spread spectrum multiple access system (Spread Spect)
rum multipule access: hereinafter referred to as SSMA method) and the like, the multiple access method is a communication method with extremely excellent frequency utilization efficiency, since multiple communication is possible in a certain frequency band. Usage tends to increase rapidly. In the CDMA system and the SSMA system, since a limited frequency band is used by a plurality of stations,
According to code information (for encryption), a transmission signal is spread and transmitted on the frequency axis and the time axis. on the other hand,
The receiving side compares the signals spread on the frequency axis and the time axis with the same (decoding) code as on the transmitting side, selects only valid information, and reproduces the received data. As a result, the information can be transmitted only to the communication partner who has the code information necessary for the encryption and the decryption, and the communication has a characteristic of being highly confidential. Furthermore, except for the person you want,
Since the signal spread on the frequency axis and the signal spread on the time axis can be treated in the same manner as (white) noise, there is a characteristic that it is difficult to give a specific influence such as interference.

[0003]

However, when performing communication between a base station and a plurality of mobile stations, it is necessary to regulate the transmission power on the mobile station side. The reason for this will be described with reference to FIGS. FIG. 2 shows base stations and mobile stations A and B.
It is a system block diagram which shows an example of the positional relationship of a station. Further, FIG. 3 is a graph showing the frequency on the horizontal axis and the reception level on the vertical axis. In FIG. 3, the hatched portion indicated by Nx indicates the total noise level of the receiver, which is the total of the ambient noise level and the device-generated noise level. Generally, CDMA
In the system and the SSMA system, since there is a spreading gain, communication is possible as long as the total noise level Nx of the receiver exceeds the reception signal level Ca as long as it does not exceed the reception limit C / N. . That is, assuming that only the mobile station A is transmitting, for example, when the base station receives the signal of the level indicated by Ca in FIG. 3, the received signal level Ca
And the total noise level Nx of the receiver (-x = Nx-
If Ca (dB)) is within the reception limit C / N (difference between the total noise level indicated by the double line and the reception signal level Ca), the transmission data can be restored and the communication is established. . However, when the mobile station B station, which is closer to the base station than the mobile station A, starts transmission with the same power as the station A,
As shown in FIG. 3, it is apparently equivalent to the total noise level of the receiver increasing to Ny, and the difference between this noise level Ny and the received signal level Ca (−y = Ny−C
Since a (dB)) exceeds the reception limit C / N, communication becomes impossible.

[0004] Conventionally, as described above, a mobile station near a base station is provided with a measure for the so-called "far-and-far problem" in which the mobile station near the base station interferes with the communication of other stations located at a point away from the base station. A control signal is transmitted to each mobile station to control the transmission power of each mobile station. That is, in the above example, the maximum transmission power allowed by the Radio Law is requested to the station A far from the base station, while the station B near the base station can receive the radio wave of the station A. A method of sending a control signal for instructing the reduction of the transmission power so that the transmission power becomes / N and controlling the transmission power has been used. However, in the above-mentioned conventional example, the case where the mobile stations are the two stations A station and B station has been described, but as the number of mobile stations accommodated in the system increases, all but the desired mobile stations are converted into noise. Therefore, the above-mentioned transmission power control has a problem that it becomes extremely complicated and cannot be put to practical use. Furthermore, in order to send back different power control information from the base station to a plurality of mobile stations, different channels must be allocated in addition to the original communication system. This causes a problem of significantly lowering frequency utilization efficiency. Also, CDM
In the communication device using the A method or the SSMA method, the circuit scale of the receiver is generally larger than that of the transmitter. However, if bidirectional communication is performed by using the same modulation method for both transmission and reception, the cost and the physical quantity are reduced. There are many disadvantages. In addition, even in the base station, controlling the transmission power that is different for each mobile station while detecting the reception power of each mobile station requires extremely complicated control. It had a problem of causing price increase.

The present invention has been made in view of the above situation, and a first object of the present invention is to reduce the frequency utilization efficiency in a wireless communication system including a base station and a plurality of mobile stations. An object of the present invention is to provide a wireless communication system that can control the transmission power of each mobile station very easily according to the relative distance between the base station and the mobile station and that is also excellent in economic efficiency. Further, a second object of the present invention is that even if the base station is a movable semi-fixed base station (hereinafter, semi-fixed station), similarly, according to the relative distance between the base station and the mobile station,
An object of the present invention is to provide a radio communication system that can control the transmission power of each mobile station very easily and is excellent in economic efficiency. Further, a third object of the present invention is a communication system comprising the semi-fixed station and a plurality of mobile stations connected to the semi-fixed station via a radio line, wherein the semi-fixed station is connected to the radio line. In a remote control system in which a control line for remotely controlling each mobile station is provided in advance, the mobile station of each mobile station can be adjusted according to the relative distance between the semi-fixed station and the mobile station without newly adding a line. An object of the present invention is to provide a remote control system with high frequency utilization efficiency that can control transmission power extremely easily.

[0006]

In order to achieve the first object, the present invention provides a communication system comprising a base station and a plurality of mobile stations connected to the base station via a wireless line, In each of the mobile stations, the relative distance between the own station and the base station is calculated from the position detecting means for detecting the position information of the own station, and the detected position information of the own station and the preset position information of the base station. The calculation means and the control means for controlling the transmission power of the own station according to the calculated relative distance are provided. Further, in order to achieve the second object, the present invention provides a communication system comprising a movable base station (semi-stationary station) and a plurality of mobile stations connected to the base station via a wireless line. The base station side is provided with a first position detecting means for detecting the position of the own station and a transmitting means for transmitting the detected position information of the own station to each mobile station. Is a receiving means for receiving the position information of the base station, a second position detecting means for detecting the position information of the own station,
A means for calculating the relative distance between the own station and the base station from the detected position information of the own station and the received position information of the base station; and a control means for controlling the transmission power according to the calculated relative distance. It was prepared to be equipped. In order to achieve the third object, the present invention is a communication system comprising a semi-fixed station and a plurality of mobile stations connected to the semi-fixed station via a wireless line, wherein the wireless line is In a remote control system in which a control line for remotely controlling each mobile station from a semi-fixed station is provided in advance, on the semi-fixed station side, there is provided a first position detecting means for detecting the position of the own station, The mobile station is provided with transmitting means for transmitting the detected position information of the own station to each mobile station, and each mobile station side receives the position information of the semi-fixed station and detects the position information of the own station. Second position detecting means, means for calculating the relative distance between the own station and the base station from the detected position information of the own station and the received position information of the base station, and transmission according to the calculated relative distance And a control means for controlling electric power, The mobile station share a control line for remotely controlling, which is constituted so as to transmit the location information of the semi-fixed station to each mobile station.

[0007]

As a result, in the first invention, each mobile station
For example, using position data from a GPS (Global Positioning System) or the like, the position information of the own station is detected, and the position information of the detected own station and the position information of the base station stored in advance are used to detect the position information of the own station. Conventionally required for both the base station and each mobile station because it is configured to control the transmission power of the local station based on the calculated relative distance information between the station and the base station. The equipment for two-way communication, the C / N detector for power control in the fixed station, etc. are no longer needed, and the receiver is not required especially in the mobile station, which is economical communication. The system can be constructed. Further, in the base station, a complicated control such as transmitting a control signal for controlling the transmission power of each mobile station while detecting the reception level of each mobile station as in the conventional case is performed. It is possible to control the transmission power of each mobile station very easily without the need to perform it. Further, in the second aspect of the invention, even if the base station is a movable semi-station, the base station detects the position of its own station using GPS or the like, and the position information of the detected base station is obtained. While transmitting to each mobile station, each mobile station calculates the relative distance between itself and the base station from the received position information of the base station and the position information of the own station detected by using GPS or the like. Since it is configured to control the transmission power, the complicated transmission power control for each mobile station in the base station becomes unnecessary, and also in each mobile station, the operator is required to move every time the base station moves. The transmission power of each mobile station can be controlled extremely easily without the trouble of resetting the position information of the base station. Further, in the third aspect of the invention, since the control line for remotely controlling each mobile station from the semi-fixed station is shared and the position information of the semi-fixed station is transmitted to each mobile station, It is possible to construct a remote control system with high frequency utilization efficiency without adding a new line.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A first embodiment of the present invention will be described below with reference to FIG. In this embodiment, a case where the base station is a fixed station that does not move will be described. FIG. 1 is a block diagram showing the configuration of a mobile station according to the first embodiment of the present invention. In the figure, the digital data applied to the input terminal 1 is modulated by the modulator 2 and given to the power amplifier 3. The output signal of the power amplifier 3 is radiated into the air via the transmitting antenna 4. The power amplifier 3 is provided with a power control terminal 5, and its transmission output power is controlled by the following method. The position information from the GPS received by the GPS receiving antenna 6 is guided to the GPS receiver 7. The GPS receiver 7 receives radio waves from three or more satellites orbiting the earth and outputs Xr (longitude information), Yr (latitude information), and Zr (altitude information). The received local position information of Xr, Yr, and Zr is stored in the ROM 8
Is added as address data. On the other hand, preset positional information Xp (longitude information), Yp (latitude information), Zp (altitude information) of the fixed base station, and the number n of mobile stations (number information) are applied to the input terminals 9 to 12, respectively. It is stored in the memory 13 and then provided to the ROM 8. R
In the OM8, each information of the above Xr, Yr, Zr (position information of mobile station), Xp, Yp, Zp (position information of fixed station) and the number n of mobile stations (number information) is given as address data, The transmission power control data R stored in advance at the corresponding address is read out and supplied to the power control terminal 5 of the power amplifier 3.

FIG. 4 shows an example of the characteristics of the transmission power control data stored in the ROM 8, showing the relative output of the transmission power (vertical axis) with respect to the distance (horizontal axis). Since the method of calculating the distance between two points in the three-dimensional space is a widely known matter, its description is omitted here. The characteristic of FIG. 4 is a curve that is proportional to the square of the distance in consideration of the propagation state of radio waves in free space. Therefore, in the system, when the base station and the mobile station are most distant from each other, the mobile station is set to output the maximum output (1.0), whereas when the distance is half, , (0.25), which is ¼ of the maximum output, is set to be output. In use, the characteristics of the transmission power control data do not necessarily have to be analog as in FIG. 4, and discrete 4 (2 ² ) to 16 (2 ⁴ ) stages are sufficient.

As described above, in the first embodiment of the present invention,
The case of a fixed station in which the position of the base station does not move has been described. However, for example, install a base station in a safe place in the vicinity of a dangerous area where people cannot approach or work, and install mobile stations in the vicinity of the base station so that the base station can move to the mobile station. On the other hand, it may be necessary to perform remote control. In this case, the base station also moves every time the work area changes, and thus becomes a semi-fixed station. As a result, in each mobile station, every time the semi-fixed station moves, the operator has to reset the position information of the semi-fixed station in each mobile station. Considering this point, an embodiment of a wireless communication system in which the transmission power of each mobile station can be easily controlled even if the base station is a semi-fixed station will be described below.

A second embodiment of the present invention will be described with reference to FIG. In FIG. 5, the semi-fixed station 108 and the mobile station 10
9 is shown. It is assumed that the semi-fixed station 108 is arranged at a required position and a plurality of mobile stations 109 are arranged around the semi-fixed station 108. (In this figure, only one mobile station 109 is shown for the sake of simplicity of the drawing.) In the semi-fixed station 108, GPS data is received by the GPS antenna 121, and the GPS receiver 118 itself receives the GPS data. Detects absolute position information such as latitude, longitude and altitude of the station.
Next, the detected position information of the semi-fixed station 108 is transmitted to the mobile station 109 side via the console 131 and the data transmission / reception antenna 132. On the other hand, the mobile station 109 receives the position information of the semi-fixed station 108 via the data transmitting / receiving antenna 120, and the position information receiver 1
After the detection at 34, it is temporarily stored in the memory 133.
Further, also in the mobile station 109, the semi-fixed station 10 described above is used.
In the same manner as in 8, the GPS antenna 1 in the mobile station 109
GPS data is received by 21 and the GPS receiver 118
Detects absolute position information such as latitude, longitude and altitude of your station. The detected position information of the own station is supplied to the calculator 106.

Next, in the arithmetic unit 106, the mobile station 10
9 from the absolute position information and the absolute position information of the semi-fixed station 108 temporarily stored in the memory 133.
The distance between 08 and the mobile station 109 is calculated, and the power amplifier 105 is controlled to adjust the power amplification amount according to the calculated relative distance. The calculation process for obtaining the relative distance may be performed only when the semi-fixed station 108 and the mobile station 109 are installed, and may be performed again when the installation location of the semi-fixed station 108 is changed. Furthermore, from the semi-fixed station 108 to the mobile station 10
9 is transmitted, and the remote operation command data is received by the mobile station 109 via the data transmission / reception antenna 120 and then analyzed by the operation command analyzer 124 to control the movement of the mobile station 109. Various other controls within the mobile station 109 are performed. Then, in the semi-fixed station 108, various data sent from a plurality of mobile stations are received by the data transmitting / receiving antenna 132, and the console 1
Monitor at 31.

Hereinafter, a third embodiment of the present invention will be described with reference to FIGS.
Shown in First, work vehicle 101 (mobile station), work order vehicle 1
The internal configuration of 03 (semi-fixed station) will be described with reference to FIG. In FIG. 6, the work instruction vehicle 103 receives GPS data via the GPS antenna 121, and the GPS receiver 118 detects absolute position information of the work instruction vehicle 103. Next, the detected absolute position information of the work instruction vehicle 103 is transmitted from the work instruction vehicle 103 to the work vehicle 101 via the operation console 131 and the data transmission / reception antenna 132. On the other hand, in the work vehicle 101, similarly to the work instruction vehicle 103, GPS data is received via the GPS antenna 121, and the GPS receiver 118 detects the absolute position of the work vehicle 101. Then, the absolute position information of the work command vehicle 103 thus received is received via the receiving antenna 120, and the transmission power controller 116 obtains the absolute position information of the work command vehicle 3 and the GPS receiver 118. The relative distance between the work vehicle 101 and the work instruction vehicle 103 is obtained from the absolute position information of the station. The calculation process for obtaining the relative distance may be performed only when the work instruction vehicle 103 and the work vehicle 101 are installed at the work site, and may be performed again when the installation location of the work instruction vehicle 103 is changed.

Next, the work performed by the work vehicle 101 (for example,
Hoisting materials, etc.) is the camera 11 inside the work vehicle 101.
The image data of the periphery of the work vehicle 101, which is photographed in No. 1, is transmitted to the work instruction vehicle 103 via the data transmission / reception antenna 120. The work instruction vehicle 103 receives this image data via the data transmission / reception antenna 132, and performs remote work of the work vehicle 101 while monitoring the image data on the console 131. Specifically, on the operation console 131 in the work command vehicle 103, a manipulator 119 for moving the work vehicle 101, operating the platform 112 for changing the direction of the camera 111, and lifting materials and the like.
And the like, and transmits these command data to the work vehicle 101 via the data transmission / reception antenna 132. In the work vehicle 101, command data from the work commander is received via the data transmission / reception antenna 120, the command data received by the command analyzer 117 is analyzed, and the camera controller 113 that controls the platform 112 and the manipulator 119. , Or a command is sent to the driving device 114. Note that the image data captured by the camera 111 of the work vehicle 101 has its transmission power controlled by the transmission power control signal provided to the power controller 116 in the transmitter 115, and is transmitted from the data transmission / reception antenna 120. .

FIG. 7 shows an embodiment in which the work vehicle 101 and the work instruction vehicle 103 are actually arranged in a dangerous area. This FIG.
In the embodiment shown in Fig. 1, the work vehicle 101 in the dangerous area is provided in a dangerous area where a person cannot approach or contact to work.
And the work command vehicle 103 for remotely operating the work vehicle 101 outside the dangerous work area, and is an example in which materials are hoisted and moved within the dangerous work area. Two work vehicles (work vehicle 101
-1, Work vehicle 101-2) Yes, this work vehicle 101-
1. In the work vehicle 101-2, the material 110 is photographed by the camera mounted on each work vehicle, and the work order vehicle 1
The image data is transmitted to 03. The work order vehicle 103 transmits required command data for remote operation of the work vehicle such as lifting operation and movement of the material 110 while monitoring the images transmitted from the work vehicles 101-1 and 101-2. Control by. Here, in the embodiment shown in FIG. 7, the work vehicle 101-1 and the work instruction vehicle 103
There is a work vehicle 101-2 between them, and the material 110 is photographed at the opposite angle and the image data is transmitted to the work instruction vehicle 113. However, in order to improve the frequency utilization efficiency of the wireless transmission path, when image transmission is performed by the CDMA system, the image data is transmitted from the work vehicle 101-1 and the work vehicle 101-2 at the same carrier frequency. Therefore, the work instruction vehicle 10
In order to stably receive the image transmitted from the work vehicle 101-1 in No. 3, the work vehicle 10 should have a sufficient C / N ratio.
It is necessary to reduce the transmission power of 1-2 image data.

As described above, in order to stably receive the image transmitted from the work vehicle 101-1, the work vehicle 101-1 first uses the GPS 123 to detect the absolute position information of its own station before starting the work. To do. Similarly for the work vehicle 101-2, G
The PS123 is used to detect the absolute position information of the own station.
Further, the work instruction vehicle also uses the GPS 123 to detect the absolute position information of the work instruction vehicle 103 by itself. Then, the absolute position information of the work instruction vehicle 103 is transmitted to the work vehicles 101-1 and 101-2 via a wireless line. Work vehicle 10
In 1-1, the relative distance between the work instruction vehicles 103 is obtained from the received absolute position information of the work instruction vehicle 103 and the absolute position information of the own station that can use the GPS 123 itself. Similarly, in the work vehicle 101-2, the own station and the work instruction vehicle 1
The relative distance between 03 is calculated. In the work vehicles 101-1 and 101-2, the transmission power at the time of image transmission is controlled according to the calculated relative distance between the work instruction vehicles 103. Therefore, the work vehicle 101-2 close to the work order vehicle 103
Is controlled so that the transmission power during image transmission is reduced, and the work vehicle 101-1 far from the work instruction vehicle 103 is increased during image transmission. Therefore, if the transmission power during image transmission is controlled every time the work instruction vehicle 3 moves, stable image transmission can be performed at all times. In the remote control systems of the above-mentioned second and third embodiments, the position information of the semi-fixed station is transmitted to a control line which is provided in advance for remotely controlling each mobile station from the semi-fixed station. It is possible to construct a remote control system having a higher frequency utilization efficiency by configuring a common line for communication.

Further, in the above-described embodiments, an example in which the position information from the GPS is used as an example of means for detecting the position of the own station in each mobile station and base station has been described, but the present invention is not limited to this. Is not limited to, for example,
A distributed transmission station (sign post) that transmits position information unique to each area may be arranged in each area to configure the system. In short, any means that can detect the position of the own station with high accuracy may be used. .

[0018]

As described above, according to the present invention, G
The position information such as PS data is used to control the transmission power of the mobile station, and the frequency band can be used only for data communication, so that the frequency can be effectively used.

Further, the transmission power of each mobile station can be easily controlled according to the relative distance between the base station and the mobile station, and no equipment for bidirectional communication is required, which is economical. An excellent communication system can be constructed.

Further, according to the present invention, even if the base station is a movable semi-fixed station, the wireless transmission line for remotely controlling the mobile station from the semi-fixed station is shared, and the remote control operation is performed. Since it is configured to send the position information of the semi-fixed station in addition to the information, each mobile station can easily check the relative distance to the semi-fixed station without newly establishing a wireless transmission path for sending the position information of the semi-fixed station. Therefore, it is possible to easily control the transmission power. Therefore, even if a plurality of mobile stations are scattered in the system and the plurality of mobile stations simultaneously transmit image data, the semi-fixed station can stably receive the plurality of image data.

[Brief description of drawings]

FIG. 1 is a block diagram showing a configuration of a mobile station according to a first embodiment of the present invention.

FIG. 2 is a system configuration diagram showing an example of a positional relationship between a base station and a plurality of mobile stations A and B.

FIG. 3 is a graph showing an example of the relationship between reception level and noise.

FIG. 4 is a graph showing an example of relative output data of a ROM 8.

FIG. 5 is a block diagram showing a second embodiment of the present invention.

FIG. 6 is a block diagram showing configurations of a semi-fixed station and a mobile station according to a third embodiment of the present invention.

FIG. 7 is a system configuration diagram showing a third embodiment of the present invention.

[Explanation of symbols]

1, 9 to 12 ... Input terminal 2 ... Modulator 3 ... Power amplifier 4 ... Transmission antenna 6 ... GPS receiving antenna 7 ... GPS receiver 8 ... ROM 13 ... Memory 101 ... Work vehicle 101-1 ... Work vehicle A 101- 2 ... Work vehicle B 103 ... Work instruction vehicle 104 ... Modulator 105 ... Power amplifier 106 ... Calculator 108 ... Semi-fixed station 109 ... Mobile station 110 ... Material 111 ... Camera 112 ... Pan head 113 ... Camera controller 114 ... Driving device 115 … Transmitter 116… Power controller 117… Command analyzer 118… GPS
Receiver 119 ... Manipulator 120 ... Data transmission / reception antenna 121 ... GPS antenna 122 ... Input terminal 123 ... GPS 124 ... Operation command analyzer 131 ... Operation console 132 ... Data transmission / reception antenna 133 ... Memory 134 ... Position information receiver

Claims (8)

[Claims] 1. A communication system comprising a base station and a plurality of mobile stations connected to the base station via a wireless line, wherein each of the mobile stations detects position information of its own station. A means for calculating a relative distance between the base station and the base station based on the detected position information of the base station and preset position information of the base station, and transmission of the base station according to the calculated relative distance. A communication system comprising: a control unit for controlling electric power. 2. A communication system comprising a movable base station and a plurality of mobile stations connected to the base station via a wireless line, wherein the movable base station detects the position of its own station. 1 position detecting means and transmitting means for transmitting the detected position information of its own station to each mobile station, and each of the mobile stations includes a receiving means for receiving the position information of the base station, and a receiving means for receiving the position information of the base station. Second position detecting means for detecting position information of the station; means for calculating a relative distance between the own station and the base station based on the detected position information of the own station and the received position information of the base station; A communication system comprising: control means for controlling transmission power according to the calculated relative distance. 3. The communication system according to claim 1, wherein the multiple access system between the base station and the plurality of mobile stations is a code division multiple access system or a spread spectrum multiple access system. Communications system. 4. The communication system according to claim 1, wherein the position detecting means is position detecting means using position data from GPS. 5. The communication system according to claim 2, wherein the first position detecting means and the second position detecting means are G
A communication system characterized by being position detecting means using position data from a PS. 6. The communication system according to claim 5, wherein a control line for transmitting a control signal for remotely controlling each mobile station from the movable base station is provided in the wireless line in advance. A communication system, characterized in that the position information of the movable base station is transmitted by sharing the control line. 7. The communication system according to claim 1, wherein each of the mobile stations corresponds to the number of mobile stations accommodated in the communication system and a relative distance between the own station and a base station. A communication system comprising control means for controlling the transmission power of its own station. 8. The communication system according to claim 1, wherein the transmission power control unit is a control unit including a table stored in a memory.