JPH04352529A - Transmission power control system - Google Patents

Abstract

PURPOSE:To change a transmission output without affecting the line quality of an adjacent carrier signal by controlling the transmission output at a control signal generation circuit to simultaneously monitor an AGC voltage and the error pulse signal of an adjacent channel. CONSTITUTION:A control signal generation circuit 101 of a multi-carrier signal reception station II simultaneously monitors the AGC voltage of a variable gain amplifier for each channel and the error pulse signal through a demodulator 213. Based on this monitored result, the circuit 101 outputs a control signal and transmits it through a transmitter 215 and a transmission/reception sharing equipment 206 to a transmission station I, and the transmission output is controlled through a variable attenuator 202 or the like for each channel of the transmission station. Thus, the transmission output can be changed without affecting the line quality of the adjacent carrier signal.

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 system for a microwave communication device that performs multicarrier transmission.

0002

2. Description of the Related Art In a conventional transmission power transmission control system, as shown in FIG. transmitter 203, transmission frequency converter 204,
A transmission power amplifier 205, a duplexer 206, and a receiver 20 that receives control signal transmission waves sent from the receiving station side.
8. Gain control circuits 207 are provided to control the corresponding variable attenuators 202, respectively. On the receiving station side, a duplexer 206, a receiving frequency converter 209, a carrier signal demultiplexer 216, a bandpass filter 210 for demultiplexing three carrier signals, a variable gain amplifier 211, a detector 212,
A control signal generation circuit 214 receives a demodulator 213, an AGC voltage 217 for controlling variable gain restoration 211 and controls a corresponding variable attenuator 202 on the transmitting station side, and a transmitter 215 sends this control signal to the transmitting station. ing. Here, as a transmission power control method, the transmission output of the transmitting station is controlled by monitoring the AGC voltage 217 of the variable gain amplifier 211 of the receiving station for each carrier. For example, the gain of the variable gain amplifier is determined from the AGC voltage, the received input electric field is estimated by calculating backward from the gain, and if the received input electric field is greater than a predetermined threshold, the direction is to lower the transmitting output of the transmitting station. Conversely, when the received input electric field is below a threshold value, the transmission power is controlled by increasing the transmission output of the transmitting station.

0003

[Problems to be Solved by the Invention] In this conventional transmission power control system, the transmission output is controlled for each carrier, so if the received input electric field of only one carrier decreases due to selective fading, etc. , only one carrier of the opposite station is controlled to increase the transmission output. At this time,
Distortion and the like generated in the transmission power amplifier affect adjacent carriers as adjacent channel interference. In other words, even though the received input electric field is above a predetermined threshold, the transmit power of the adjacent carrier has increased, causing the level of interference waves (unwanted waves in the band) to rise, causing the desired wave to There is a drawback that the ratio deteriorates and the line quality deteriorates.

0004

[Means for Solving the Problems] The transmission power control method of the present invention is such that a receiving station of a wireless communication line that transmits a multicarrier signal uses a bandpass filter that branches the output of a receiving frequency converter into the same number of carriers. A variable gain amplifier that amplifies the output of this splitter and controls it to an appropriate level for the demodulator, and inputs the output signal of this variable gain amplifier to output a demodulated signal including an error pulse signal. a control signal generation circuit that inputs the AGC voltage of the variable gain amplifier and the error pulse signal output from the demodulator and outputs a control signal for controlling the transmission output of the opposing transmitting station; a transmitter that transmits the output of the signal generation circuit to the transmitting station; the transmitting station has a receiver that receives the output of the transmitter; and a modulator output of each carrier signal according to the control signal demodulated by the receiver. and a gain control circuit that controls the amount of attenuation of the variable attenuator connected to the variable attenuator.

[0005]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, the present invention will be explained with reference to the drawings. FIG. 1 is a block diagram of an embodiment of the present invention, FIG. 3 is a circuit diagram of a specific example of the control signal generation circuit in FIG. 1, and FIG. 4 is an explanatory diagram of a multicarrier signal of this embodiment. In Figure 1,
The same symbols as in FIG. 2 indicate the same functions and configurations. That is, in this embodiment, the error pulse signal 100 is input from the demodulator 213 to the control signal generation circuit 101 to obtain the control signal.

Next, the operation of this embodiment will be explained. The three multi-carrier transmitted signals are received by a receiving frequency converter 209
The signal is converted into an intermediate frequency by a demultiplexer 216, and then band-limited for each carrier by a bandpass filter 210. The band-limited signal is amplified by the variable gain amplifier 211 so that it can be normally demodulated by the demodulator 213. Furthermore, the demodulator 213 has a function of monitoring the error rate of the transmission signal, and if there is an error in the transmission signal, it outputs an error pulse signal 100 indicating that there is an error. The control signal generation circuit 101 has a function of determining whether the received input level of each carrier is equal to or higher than a threshold value from the AGC voltage 217 of the variable gain amplifier 21, and detecting an error of each carrier from the error pulse signal 100 of the demodulator 213. It has two functions to determine whether the rate is below a threshold value.

Next, the operation of the control signal generation circuit 100 is shown in FIG.
This is explained by: AGC voltage 1, AGC voltage 2, AGC
Voltage 3 is the AGC voltage for each multicarrier, and the corresponding multicarrier signals are SIG1 and SIG2, respectively.
, SIG3. Error pulse signal is SIG2, SI
This is an error pulse signal output from the demodulator of G3,
The frequency relationship of SIG1, SIG2, and SIG3 is shown in Figure 4 (a
), SIG2 and SIG3 are multicarrier signals adjacent to SIG1. When no fading occurs on the transmission path, SIG1, SIG2, S
The reception input of both IG3 is at the standard reception input level. Therefore, AGC voltages 1 to 3 are above the threshold value, and the discriminator 301 outputs H level as a logic level. Further, the error pulse signals 2 and 3 are integrated by a counter 302 for a certain period of time, and are held by a latch circuit 303. This output is determined by the discriminator 304 to be less than the threshold value, and the output of the discriminator 304 outputs an H level as a logic level. The output of the control signal generation circuit 101 under this condition becomes L level as a logic level, and at the transmitting station, the variable attenuator 2
Control operates in the direction of increasing the attenuation amount of 02 and lowering the transmission output.

Next, a case where flat fading occurs in a transmission path will be explained. When the AGC voltages 1 to 3 are below the threshold, the discriminator 301 outputs L level as the logic level, the output of the control signal generation circuit 101 becomes H level as the logic level, and the variable attenuator 20 is output at the transmitting station.
Control works in the direction of decreasing the attenuation amount of 2 and increasing the transmission output.

Next, a case where flat fading and selective fading occur simultaneously on a transmission path will be explained. As shown in FIG. 4(b), in the conventional example, the SI of the received signal
G1 raises the transmission level due to the occurrence of selective fading, interferes with SIG2 and SIG3, and mixes unnecessary waves. Therefore, although AGC voltages 1 to 3 are below the thresholds, the error rates of SIGs 2 and 3 are above the thresholds. At this time, since it works in the direction of increasing the transmission output of SIG1, the ratio of desired waves to unnecessary waves of SIG3 deteriorates, and the line quality of SIG3 deteriorates. In the control signal generation circuit 101 of the present invention, when the error pulse signal 3 becomes below the threshold value, the output is set to the L level as a logic level and the transmission output is controlled in the direction of lowering, thereby degrading the quality of the adjacent carrier. You won't have to do anything.

0010

As explained above, in the present invention, since the control signal generation circuit simultaneously monitors the AGC voltage and the error pulse signal of the adjacent channel to control the transmission output, the line quality of the adjacent carrier signal is improved. This has the effect of making it possible to change the transmission output without affecting it.

[Brief explanation of drawings]

FIG. 1 is a block diagram of one embodiment of the present invention.

FIG. 2 is a block diagram of a conventional transmission power control method.

FIG. 3 is a circuit diagram of main parts of the embodiment of FIG. 1;

FIG. 4 is an explanatory diagram of a carrier signal in this embodiment.

[Explanation of symbols]

100 Error pulse signal 101 Control signal generation circuit 201 Modulator 202 Variable attenuator 203 Synthesizer 204 Transmission frequency converter 205 Transmission power amplifier 206　　　　　Sending/receiving device 207 Gain control circuit 208 Receiver 209 Reception frequency converter 210 Bandpass filter 211 Variable gain amplifier 212 Detector 213 Demodulator 215 Transmitter 216 Duplexer 217 AGC voltage 301 Discriminator 302 Counter 303 Latch circuit 304 Discriminator

Claims (2)

[Claims] Claim 1: A receiving station of a wireless communication line that transmits a multicarrier signal comprises a duplexer including a bandpass filter that branches the output of a received frequency converter into the same number of carriers, and amplifies the output of the duplexer. a variable gain amplifier that controls the demodulator to an appropriate level; a demodulator that receives the output signal of the variable gain amplifier and outputs a demodulated signal including an error pulse signal; a control signal generation circuit that receives an error pulse signal output from the demodulator and outputs a control signal for controlling the transmission output of an opposing transmitting station; and a transmitter that transmits the output of the control signal generating circuit to the transmitting station. a receiver for receiving the transmitter output; and a control signal demodulated by the receiver to control the amount of attenuation of a variable attenuator connected to the modulator output of each carrier signal. A transmission power control method comprising a gain control circuit. 2. The control signal generation circuit includes a first discriminator that determines whether the AGC voltage of each wireless communication line is higher or lower than a predetermined threshold; and the error pulse signal of a wireless communication line other than the own wireless communication line. means for integrating and holding the error pulse signal; a second discriminator that inputs the hold output signal of the error pulse signal and determines whether it is higher or lower than a predetermined threshold;
2. The transmission power control method according to claim 1, further comprising means for inputting the output signal of the second discriminator and making a logic determination.