JPH0425223A - Transmission power control system - Google Patents

Abstract

PURPOSE:To prevent deterioration in the cross polarized wave identification degree by providing a circuit deciding the reception level of a radio signal of two routes in co-channel transmission to a receiver side. CONSTITUTION:A reception level deciding circuit 10 compares output levels 11A, 11B corresponding to reception levels of V, H polarized waves and decides a level which is larger, and when the V polarized wave is decreased due to fading and the level of the H polarized wave is higher than the level of the V polarized wave, the output level 11B of the H polarized wave and a deciding signal 12 is inputted to a transmitter 114. A station A receives a transmission wave from the transmitter 114 and a receiver 106 inputs the signal corresponding to the signal 12 to a transmission power control circuit 107A. The transmission power control circuit 107A receives the deciding information to control the transmission output of the TX 103B so that the transmission output level is a proper level such as the higher reception level of a station B, e.g. the output of a RX 108B. Thus, the deterioration in cross polarized wave identification degree is prevented.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a transmission power control method in microwave communication, and in particular, the present invention relates to a transmission power control method in microwave communication, and in particular, a co-channel radio frequency that controls V polarization (vertical polarization) and H polarization (horizontal polarization). The present invention relates to a transmission power control method that can suppress the level of interference to receivers of other polarized waves when a two-route radio line is configured using the two routes.

[Conventional technology]

Conventionally, two
When configuring a route wireless line, as shown in the block diagram of Fig. 2, station A uses a baseband signal modulator (
(hereinafter referred to as MOD) 105A, and MOD105 (described later)
A first transmitting section consisting of a variable attenuator (hereinafter referred to as ATT) 104A that controls the output level of A, and a transmitter (hereinafter referred to as TX) 103A; and MOD 105B. ATT104B and TX103
It has an H polarization transmitting section which is a second transmitting section composed of B and B. The transmitted waves of these two routes are combined by a polarization splitter 116 while having polarization identification degrees of (1) polarization and (H) polarization. This combined output is transmitted to station B, which is the opposite station, via the antenna 101 via a duplexer 115 that distributes received waves from the opposite station, which will be described later. Station B has an antenna 102° and a duplexer 115. TX1 of station A via polarization splitter 116
Receive the 03A transmission wave. Receiver (hereinafter referred to as RX)
108A, a variable gain amplifier (hereinafter referred to as AGCA) 109A that controls the output level of RX108A, and AGC
A detector 110A for detecting the output signal of Al 09A and a demodulator (hereinafter referred to as DEM) 1 for demodulating the baseband signal.
11A, and the RX which receives the transmission wave of TX103B of station A.
108B, AGCA109B, detector 110B,
It has an H-polarized wave receiving section which is a second receiving section composed of DEMllllB. Furthermore, at the B station, a detector 110A,
The output levels 113A and 113B of 110B are fed back to AGCA 109A and 109B respectively to keep the output level of AGCA constant, and the output levels 113A and 113B are
113B to the transmitter 114, this output level 1
The information of 13A and 113B is transmitted to the A station. At station A, the transmitted wave from the transmitter 114 is passed through the antenna 101 and the duplexer 115, and is received and demodulated by the receiver 106, and information corresponding to the output levels 113A and 113B is input to the transmission power controller 107. . Here, the transmission power controller 107 monitors two pieces of information corresponding to the V polarization and the H polarization, and if, for example, the is controlled to reduce the amount of attenuation and increase the transmission power of TX103A. Conversely, H
When the polarization becomes lower, the ATT 104B is controlled to increase the transmission power of the TX 103B. When a radio line with two routes is configured using such polarized waves (1) and H (H polarized wave), the mutual interference with other polarized waves will be explained with reference to the explanatory diagram of FIG. Figure 3(a).

(b) and (c) are respectively ■ Standard reception conditions for both polarized waves and H polarized waves; ■ Conditions where fading has occurred on the polarized side;
This is an output spectrum graph of the output 112A of the variable gain amplifier of the B station when the transmission output of the TX 103A is increased due to this fading. The solid lines indicate signal spectra on the V side and H side, and the broken lines V' and H' indicate cross polarization components on the V side and H side, that is, interference components with other polarizations. Third
In the state shown in FIG. 3(b), the power control circuit 107 operates in the direction of increasing the transmission power on the V side, resulting in the cross deviation component V' leaking to the H side as shown in FIG. 3(c>). The level of the signal became large, deteriorating the degree of cross-polarization discrimination on the H side.

[Problem to be solved by the invention]

In the conventional transmission power control method described above, AGC control is performed independently in each receiver on the receiving side of the opposite station. Also, when the reception level of one of the two routes of co-channel radio signals drops due to fading, etc., this information is transmitted to the transmitting station and the transmission power control circuit sets a predetermined threshold. If it is determined that the value is below this value, the transmitter operates to increase the transmission power, which has the disadvantage that the degree of cross-polarization discrimination on the receiving side deteriorates.

[Means to solve the problem]

The transmission power control method of the present invention configures two routes of radio links with mutually different polarization planes using co-channel radio frequencies between opposing transmitting stations and receiving stations, and the transmitting station is connected to a first
a transmitter, a second transmitter having a plane of polarization different from that of the first transmitter, and a transmission signal having control information for controlling the transmission output of the first or second transmitter sent from the receiving station. a first receiving section including an automatic gain control amplifier opposite to the first transmitting section; and an automatic gain control amplifier opposite to the second transmitting section. and a transmitter that inputs the control information and transmits it to the receiver of the transmitting station, wherein each of the first and second receivers is provided with: The transmitter has a reception level determination circuit that compares the automatic gain control voltages of the automatic gain control amplifiers obtained and determines the automatic gain control voltage with the higher reception level, and inputs control information corresponding to this determination to the transmitter.

〔Example〕

Next, the present invention will be explained with reference to the drawings.

FIG. 1 is a block diagram showing one embodiment of the present invention. Circuits with the same symbols as those in the conventional example shown in FIG. 2 have the same configuration and operation. That is, the detectors 110A and ll0B at station B
The output levels IIA and 11B are respectively AGCA109.
AGC control is performed to keep the output levels of A and 109B constant, and the signals are input to the reception level determination circuit 10.

The reception level determination circuit 10 compares the output levels IIA and IIB corresponding to the reception levels of V polarization and H polarization and determines which reception level is higher.For example, the V polarization becomes lower due to fading and the H polarization becomes lower. If the level is higher than the V polarization level, the H polarization output level 11B is selected and the determination signal 12 is input to the transmitter 114. Station A is transmitter 11
4 is received, and the receiver 106 inputs a signal corresponding to the determination signal 12 to the transmission power control circuit 107A.

The transmission power control circuit 107A receives this determination information and sets the transmission output level to the higher reception level of station B, for example, RX.
TX103 so that the output of 108B is at the appropriate level.
Controls the transmission output of B. Therefore, as in the conventional example, if the reception level of two stations is compared and becomes lower than a predetermined threshold, the transmission output of the lower route is increased to ensure normal reception. There is no risk of increasing interference with other polarized waves.

〔Effect of the invention〕

As explained above, the present invention provides a circuit on the receiving side to judge the reception level of two routes of wireless signals transmitted through co-channels, and uses this judgment information to control the transmission power on the transmitting side. This has the effect of preventing deterioration of the degree of cross-polarization discrimination between the two polarized waves due to the above.

[Brief explanation of drawings]

FIG. 1 is a block diagram of an embodiment of the present invention, FIG. 2 is a block diagram of a conventional transmission power control system, and FIGS. 3(a) and (b).
) and (c) are explanatory diagrams of the operation of the conventional example. 10... Reception level judgment circuit, IIA, IIB/output level, 12... Judgment signal, 101, 102... Antenna, 103A, 103B... Transmitter (Tχ), 1
04A, 104B... Variable attenuator (ATT), 105
A, 105B... Modulator (MOD), 106... Receiver, 107, 107A... Transmission power control circuit, 10
8A, 108B...Receiver (RX), 109A, 10
9B...Variable gain amplifier (AGCA), ll0A, l
l0B...Detector, 111A. 111B... Demodulator (DEM), 114... Transmitter, 115... Transmitter/receiver duplexer, 116... Polarization demultiplexer.

Claims (1)

[Scope of Claims] Two routes having different polarization planes are constructed using a co-channel radio frequency between an opposing transmitting station and a receiving station, and the transmitting station connects a first transmitting section and a first transmitting section. a second transmitter having a plane of polarization different from that of the transmitter; and a receiver that receives a transmission signal sent from the receiving station and having control information for controlling the transmission output of the first or second transmitter. and the receiving station includes a first receiving section including an automatic gain control amplifier facing the first transmitting section, and a second receiving section including an automatic gain control amplifier facing the second transmitting section. and a transmitter that inputs the control information and transmits it to a receiver of the transmitting station, wherein the automatic gain control amplifier provided in each of the first and second receiving sections A transmission power control method characterized by comprising a reception level determination circuit that compares gain control voltages, determines the automatic gain control voltage with a higher reception level, and inputs control information corresponding to this determination to the transmitter. .