JP3393471B2 - Transmission power control method and transmission power control device - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a transmission power control device, and more particularly to a transmission power control method and a transmission power control device used in a microwave radio communication system.

[0002]

2. Description of the Related Art Conventionally, in the field of microwave radio communication systems, various transmission power control devices have been used in order to prevent a reception electric field from being lowered due to fading or the like to reduce communication quality. As one of such transmission power control devices, the technique described in Japanese Patent Laid-Open No. 7-235902 is known.

FIG. 5 is a diagram showing a block diagram of a transmission power control device disclosed in Japanese Patent Laid-Open No. 7-235902. In the figure, the reception signal received by the reception antenna 11 is amplified by the receiver 12, and then input to the demodulator 13 to output the demodulation signal to the reception output 14.

The output of the receiver 12 is input to the reception level detector 15 and the level of the reception burst signal is detected. Then, the output is input to the fading frequency detector 16 and the level averaging device 17 which see the fluctuation within a relatively narrow time width, and further the fading frequency detector 1
The output of 6 is input to the level averager 18. The level averaging unit 18 sets the time width for detecting the original reception level data for obtaining the average reception level according to the detected fading frequency value, and the average value of the reception data thus obtained is set to the desired transmission power. Is input to the level comparator 18 for comparison with the value corresponding to. And the level comparator 1
The transmission power was determined by the transmission power controller 19 based on the output of No. 8 and the transmission power control signal was input to the transmitter 31 to control the transmission level for transmission to the opposite station.

[0005]

In the prior art described above, a method of eliminating unnecessary control by shortening the sampling cycle of the reception input level when fading occurs and lengthening the sampling cycle when fading does not occur. Was used to control the transmission power.
In this transmission power control method, a CPU is generally used for the transmission power control process, and the CPU is always operated to detect the reception input level, detect the fading frequency, etc. regardless of the occurrence of fading. Has been done.

However, as is generally known, 50k
In the case of m relay (plain) microwave communication, the probability of occurrence of Rayleigh fading is as small as p = 0.74%, so for example, fading occurs only for about 5 hours in one month. .

Therefore, during many times when fading does not occur, the CPU for transmission power control processing does not perform any processing, so that this CPU has not been effectively utilized.

[0008]

In order to solve the above problems, a transmission power control apparatus of the present invention is a transmission power control apparatus for compensating a reception level of a wireless line between opposing wireless communication stations. The station detects the reception level only when the reception level becomes equal to or lower than the first threshold, and based on the difference between the detected reception level and the second threshold lower than the level equal to or lower than the first threshold. It has a reception determination means for generating control information and a means for transmitting the control information to the opposite second wireless communication station, and sends the second wireless communication station the transmission level of the transmitter based on the control information. Characterized by having a transmission power control means for controlling

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described with reference to the drawings.

FIG. 1 is a block diagram of a transmission power control apparatus of the present invention.

FIG. 1 is a diagram for explaining a transmission power control device used in a microwave communication system in which a station A transceiver device and a station B transceiver device face each other. Referring to FIG. 1, in station A, a transmission signal input from a signal input terminal 1a is modulated by a modulator 2a, the modulated signal is amplified by a transmitter 3a having a function of varying transmission power, and a transmission antenna 4a is provided. Is transmitted to station B as a radio signal.

On the other hand, in the station B, the radio signal transmitted from the transmitting antenna 4a is received by the receiving antenna 10b, amplified by the receiver 9b, and then input to the demodulator 8b. The demodulator 8b outputs the demodulated signal to the output terminal 7b and detects the frame synchronization signal included in the output signal of the receiver 9b. When the loss of frame synchronization is detected, the frame synchronization alarm 21b is sent to the transmission power controller 6b.

Further, the receiver 9b receives the reception level monitor voltage 23b and the reception level alarm 22b from the reception judgment section 5
output to b.

Here, the reception level monitor voltage 23b
Is a monitor voltage corresponding to the received signal level, and the AGC detection voltage of the AGC amplifier in the receiver is generally used. The reception level alarm 22b is an alarm that is output when the reception input level has not reached the line deterioration yet, but is below the level (in the present invention, referred to as threshold 1 and will be described later in detail) in a state of decreasing. is there. The reception determination unit 5b uses the reception level alarm 2 from the receiver 9b.
Only when 2b is detected, the reception input level is detected based on the input reception level monitor voltage 23b, and the control information 24b for controlling the transmission power of the opposite transmitter is generated.

FIG. 2 is a block diagram of the reception determination unit 5b. The reception level monitor voltage 23b is input to the reception determination unit 5b, converted into a digital signal by the A / D converter 21, and input to the CPU 22. Also, CPU
A reception level alarm 22b is input to the A / D converter 22, and when the reception level alarm 22b is detected, the A / D converter 2
Based on the output of 1, the control information 24b that gives a predetermined transmission level is calculated.

After the control information 24b is modulated by the modulator 2b of the B station, this modulated signal is transmitted to the A station by the transmitter 3b and the transmitting antenna 4b through the wireless line. This transmission signal is received by the receiving antenna 10a and the receiver 9b of the A station and demodulated by the demodulator 8a.
Then, the demodulated control information is sent to the power controller 6a as control information 25a, and transmission power control is performed based on the control information so that the gain of the transmitter 3a becomes a predetermined value.

Now, returning to the operation on the B station side, the receiver 9b does not generate the reception level alarm 22b when the reception input level is higher than the threshold value 1, so that the reception determination unit 5b indicates the reception input level. The control information for controlling the detection and the transmission power is not generated, and naturally, the control information 23b is not transmitted from the B station to the A station.

Therefore, as a case where the transmission power controller 6a of the A station does not detect the control information, the reception input level of the B station is higher than the threshold value 1 and the communication from the B station to the A station is disconnected. It may be interrupted.

In the present invention, in order to distinguish between these two cases, the receiver 9a detects the loss of frame synchronization of the radio signal. As a result, when the station B disconnects from the station A due to a disconnection, the station B always sends the frame synchronization alarm 22a to the transmission power controller 6a, so that the transmission power controller 6a communicates normally. It can be surely discriminated whether it is broken or disconnected.

The frame synchronization alarm 22a is given as an example for knowing the wireless line quality, but other alarms may be used as long as they can identify an abnormality in the wireless line quality state.

If the reception input level of the signal received by the receiver 9b is less than the threshold value 1, it is determined that fading has occurred, and the reception determination unit 5b receives the reception level alarm 2
2b is transmitted.

Upon receiving the reception level alarm 22b from the receiver 9b, the reception determination unit 5b starts detecting the reception input level. The reception input level is detected until the fading is subsided, the reception input level is higher than the threshold 1, and the alarm does not occur and becomes stable. As a result of detecting the reception input level, a control signal for controlling to increase the transmission power is generated if the threshold value becomes 2 (details will be described later) or less.

FIG. 3 is a diagram for explaining the threshold 1 and the threshold 2. It is a figure showing the state where a received input level falls gradually from a fixed level. Here, the threshold value 1 means a level at which the reception input level is lowered but has not yet reached the line deterioration, and the threshold value 2 is raised because the line is deteriorated when the reception input level continues to decrease. Refers to the required level. Optimal values are selected for these values according to the sampling interval for detecting the reception input level and the method of controlling the transmission power.

In the present embodiment, the threshold value 1 is set to a value higher than the threshold value 2 by about 5 dB. Generally, the fading speed is 100 dB / sec at the fastest, and transmission power control is 1
If it is performed for each dB, the sampling interval for detecting the reception input level is 1 in order to immediately respond to fading.
It is necessary to set it to 0 msec or less. When the interval for controlling the transmission power and the sampling interval are determined in this way, fading can be dealt with immediately, so it is not necessary to make the threshold 1 much higher than the level of the threshold 2. However, in order to reliably monitor that fading has subsided, it is necessary to set the threshold value 1 at a level about 5 dB higher than the threshold value 2.

When the reception input level is equal to or lower than the threshold value 1 and higher than the threshold value 2, it may be considered that the reception input level has decreased or the reception input level has increased. When the received input level drops, it is not necessary to generate a control signal to keep the transmission power,
When the reception input level rises, it is necessary to maintain the transmission power until the fading is reliably recovered, that is, the reception input level becomes higher than the threshold 1.

Since the present invention does not have a function of discriminating whether the received input level is lowered or raised for the sake of simplification of the circuit configuration, in these cases, the control signal is generated so as to keep the transmission power. To do. The control information is from station B to station A
It is transmitted to the transmission power controller 6a via a wireless line to the station, and the transmission power of the transmitter 3a is controlled based on the information.

In the above description, the case where the transmission power of the station A is controlled based on the transmission power control information transmitted from the station B which has received the transmission signal from the station A has been described, but the reverse is also true. Since the operation is performed, the description is omitted.

(Second Embodiment of the Invention) The reception determination section 5
In the description of b, the configuration using the CPU has been described. But,
The present invention reduces unnecessary processing, simplifies the processing, and
Since the load on U is small, it can be realized with a hardware-only configuration.

FIG. 4 is a block diagram showing another embodiment of the reception determination section 5b of the present invention.

The reception judging section 5b has an A / D converter 21 for receiving the reception level monitor voltage 23b and converting it into a digital signal, and a comparator for comparing the output of the A / D converter 21 with the threshold value 2. A transmission power control information generation unit 24 that inputs the output of the comparator 23 and generates transmission power control information.
And a parallel-serial converter 25 that performs parallel-serial conversion on the output of the transmission power control information generation unit 24, and a communication IC 26 that inputs the output of the parallel-serial converter 25 and converts the output to a communication signal.

[0031]

The transmission power control apparatus of the present invention does not detect the reception input level and does not generate the control signal for controlling the transmission power when the fading does not occur, so that the reception determination unit CPU processing can be reduced and the CPU load can be reduced. Therefore, while the fading is not occurring, the CPU can be effectively used by performing other processing.

Further, by reducing the load on the CPU,
Even if you use an inexpensive CPU with low processing capacity, you can fully process.

Furthermore, the reception determination unit simplifies the system configuration by reducing unnecessary processing and simplifying the processing, so that the configuration can be configured by simple hardware without using a CPU. .

[Brief description of drawings]

FIG. 1 is a block diagram of a transmission power control device of the present invention.

FIG. 2 is a block diagram of a reception determination unit 5b shown in FIG.

FIG. 3 is a diagram illustrating threshold values 1 and 2 in FIG.

FIG. 4 is another block diagram of the reception determination unit 5b of FIG.

FIG. 5 is a block diagram of a conventional transmission power control device.

[Explanation of symbols]

1a, 1b Signal input terminal 2a, 2b modulator 3a, 3b transmitter 4a, 4b transmitting antenna 5a, 4b reception determination unit 6a, 6b Transmission power controller 7a, 7b Signal output terminal 8a, 8b demodulator 9a, 9b receiver 10a, 10b antenna

Claims (6)

(57) [Claims] 1. A transmission power control device for compensating the reception level of a wireless line between opposing wireless communication stations, wherein the first wireless communication station receives a reception level only when the reception level is below a first threshold value. And a reception determination unit that generates control information based on a difference between the detected reception level and a second threshold value that is lower than the first threshold value and a second threshold value that opposes the control information. A transmission power control device having means for transmitting to a wireless communication station, and the second wireless communication station having transmission power control means for controlling a transmission level of a transmitter based on the control information. Wherein said transmission power control means, according to claim, further wherein the alarm information of the radio channel quality is transmitted from the first wireless communication station to the second radio communication station, characterized in that the input 1. The transmission power control device according to 1. 3. The reception determination means is processed by using a CPU, and when the received signal is equal to or higher than the first threshold value, the CPU executes other processing. Transmission power control device. 4. The reception input level is low when the first threshold value is low.
4. The transmission power control device according to claim 1, wherein the transmission power control device is at a level at which the line power is not deteriorated yet . 5. The transmission power control apparatus according to claim 1, wherein the second threshold value is a reception level that needs to be increased from the channel quality to the reception input level. 6. A transmission power control method for compensating a reception level of a radio line between opposing radio communication stations, wherein the reception level is detected only when the reception level is equal to or lower than a first threshold, and the detected level is detected. Control information is generated based on a difference between a reception level and a second threshold value that is lower than the first threshold value and lower, and the control information is transmitted to the opposing wireless communication station. A transmission power control method comprising controlling the transmission level of the transmitter to a predetermined level based on the control information.