JPS637060B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a transmission power control method for an earth station device applied to a satellite communication system in which two communication waves are commonly amplified by a satellite repeater.

In recent years, radio waves in the sub-millimeter wave band, which suffer from large propagation losses due to rainfall, have come to be used for satellite communications.
Along with this, various methods have been proposed that can optimize the level diagram of the entire system by controlling the transmission power of each earth station according to fluctuations in line conditions such as during rain. One of the methods is the method shown in Japanese Patent Application No. 52-35404, in which when communicating between two stations, the main earth station and the slave earth station, the transmission power of the main earth station is adjusted to improve the line quality in both directions. is controlled so that they are equal. However, with this method, if the main station has a larger antenna diameter and maximum transmission power than the slave station, and there is some margin,
This is an attempt to achieve optimization by controlling only the transmission power from the main station;
The problem was that it could not be applied to cases where the antenna diameter and maximum transmission power of the stations were similar.

There is also a method shown in the specification of Japanese Patent Application No. 54-39742. This is a method of controlling the transmission power of the transmitting earth station so that the line quality between the transmitting earth station and the receiving earth station for each communication wave matches a predetermined reference value. According to this method, it can be applied even when the scale of each station is similar, but on the other hand, the standard value of line quality is set to a relatively poor value that is optimal under marginal conditions such as during rainy days. Therefore, even though the line quality can be improved when conditions are good, such as during sunny days, there is a drawback that the transmission power is held to a low value so as to reach a relatively poor reference value. Furthermore, if the line conditions are so bad that the line quality is below the reference value even if the transmission power of any station is at its maximum value, there is a drawback that optimization of the level diagram of the entire system cannot be achieved.

An object of the present invention is to eliminate the drawbacks of the above-mentioned prior art, to be applicable even when the scales of two opposing earth stations in a satellite communication system are comparable, and to
It is an object of the present invention to provide a transmission power control method for an earth station that can control the transmission power of both stations to an optimal value according to line conditions such as rain conditions at that time.

According to the present invention, it is applied to a satellite communication system in which two frequencies from opposing earth stations are commonly amplified by a repeater in a communication satellite, and the S/N of the transmission line from the other station is
a first means for detecting the S/N value; a second means for receiving and demodulating S/N value information of a transmission line from the own station to the other station from the other station and detecting the S/N value; third means for comparing the difference between the output of the first means and the output of the second means with a predetermined constant value and detecting a value corresponding to the error value obtained by the comparison; means for varying the transmission power of its own station in response to the output of the third means; and modulating the information on the S/N value detected by the first means together with the input of the transmission baseband signal, A transmission power control method for an earth station device is obtained, which is characterized in that it includes means for applying to the input side a signal varied by the transmission power variable means.

In the transmission power control method according to the present invention, the transmission power of each earth station is such that the line quality from the corresponding earth station to the other earth station is slightly better than the line quality from the other earth station to the own station. It is controlled to have a value that is For example, assume that there is rain in the area of the other station, and as a result the radio waves from the other station to the satellite are attenuated. In this case, due to the two-wave common amplification characteristics of the satellite repeater, on the output side of the satellite repeater, the stronger wave from the own station is further strengthened, and the weaker wave from the other station is further strengthened. The transmitted wave is further weakened. Therefore, even if the transmitted waves from the local station are attenuated due to rain in the area of the other station, the line quality from the other station to the local station is significantly higher than the line quality from the local station to the other station. It deteriorates considerably.

In such a case, according to the present invention, first, the transmission power of the own station is controlled to be weakened, and the transmission power of the other station is controlled to be strengthened. As a result, the transmission power of both stations is controlled so that the line quality in both directions is approximately equal, and then the transmission power of one of the two stations is controlled to continue increasing until it reaches its upper limit. Ru. because,
Both stations control their transmission power so that the line quality sent to their own station is slightly better than the line quality sent to the other station, so if one station improves, the other station will compete with each other to catch up. The transmission power continues to rise, and this competition stops only when the transmission power of the transmitting station on the line with the worse condition reaches its upper limit. At this time, the transmission power of the transmitting station on the line in the direction with good conditions is controlled to the point where the line quality in the direction of the other station is slightly better than the line quality in the direction of the other station, so The line quality will be almost the same.

In addition, in the present invention, it is necessary not only to know the line quality from the other station to the own station, but also to know the line quality from the own station to the other station. As shown in the specification of No. 54-39742, this can be realized by providing both lines with a line quality measurement channel and a line quality information transmission channel.

Next, an embodiment of the earth station transmission power control method according to the present invention will be described with reference to the drawings.

FIG. 1 is a block diagram showing the structure of an embodiment according to the present invention. In this figure, a signal from a partner station received by an antenna 1 is separated by a duplexer 2, amplified by a low noise amplifier 3, and then applied to a frequency converter 4. The signal frequency-converted by the frequency converter 4 is demodulated by the demodulator 5 to become a baseband signal, which is connected to the telephone 7 via the terminal device 6. On the other hand, the transmission signal from the telephone 7 is turned into a baseband signal by the terminal device 6, and is applied to the modulator 8 and modulated. The modulated signal is applied to a frequency converter 10 after passing through a variable attenuator 9 for controlling transmission power. Here, the modulated signal is transmitted to the high power amplifier 11.
is amplified and transmitted from antenna 1.

On the other hand, the second output branched by the demodulator 5 is S/
The signal is guided to the N detection circuit 12, and a voltage proportional to the S/N value of the sending line from the other station is obtained on the output side.
Additionally, the third output of demodulator 5 is guided to subcarrier demodulator 13 . Information on the S/N value received from the other station on the own-station transmission line is returned using this subcarrier, so the demodulated output obtained from the subcarrier demodulator 13 that receives this information is the S/N value of the own-station transmission line. The voltage is proportional to the value. The voltage of the S/N value of the other station sending line and the voltage of the S/N value of the own station sending line obtained in this way are applied to the differential amplifier 14,
Here, the two are subtracted. Furthermore, this output voltage is applied to the differential amplifier 15 and subtracted by a predetermined constant voltage ΔV. After this difference output is integrated by the integrating circuit 16, it is applied to the variable attenuator 9 of the modulator output, and here, by varying the output given to the frequency converter 10, the output from the high power amplifier 11 is The transmission power of is controlled. As a result of this control, the transmission power is
Since the voltage of the N value is controlled to be larger than the voltage of the S/N value of the sending line of the other station by a constant voltage ΔV, by setting the constant voltage ΔV to an appropriately small value, the voltage of the sending line of the own station is controlled. The S/N value is slightly larger than the S/N value of the transmission line to the other station. In addition,
The output of the S/N detection circuit 12, which is a voltage proportional to the S/N value of the transmission line of the other station, is branched and given to the subcarrier modulator 17, and the output modulated here is sent to the modulator along with the baseband signal. Added to 8. Information on the S/N value of the sending line to the other station is sent back to the other station, and is used for similar control at the other station.

As a result of this operation, among the transmission powers of both stations, the transmission power of the transmitting station on the line in the direction with poor conditions is controlled to its upper limit value, and the transmitting power of the transmitting station on the line in the direction with good conditions is controlled to its upper limit value. The transmission power of is controlled so that the line quality in both directions is approximately equal. Therefore, in both sunny and rainy conditions, the transmission power of the earth station and satellite is used most effectively, and the line quality in both directions is the best value obtainable under the conditions at that time. Optimized.

As is clear from the above explanation, according to the present invention, in satellite communication in which two communication waves are commonly amplified by one satellite repeater, attenuation due to rain etc. can occur in the propagation path of radio waves connecting between earth stations. Even though fluctuation factors occur, it is possible to optimize the level diagram for the entire communication system, which not only improves line quality but also improves system economy through efficient control of transmission power. This has a big effect on this point.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing the configuration of an embodiment according to the present invention. In this figure, 1 is an antenna,
2 is a branching filter, 3 is a low-noise amplifier, 4 is a frequency converter for transmission, 5 is a demodulator, 6 is a terminal equipment, 7 is a telephone, 8 is a modulator, 9 is a variable attenuator, 10 is for reception Frequency converter, 11 is a large power amplifier, 12 is S/
N detection circuit, 13 is a subcarrier demodulator, 14, 15
is a differential amplifier, 16 is an integrating circuit, and 17 is a subcarrier modulator.

Claims (1)

[Claims] 1 Applied to a satellite communication system in which two frequencies from opposing earth stations are commonly amplified by a repeater in a communication satellite, the first means for detecting the S/N value of the transmission line from the other station and the first means for detecting the S/N value of the transmission line from the other station, a second means for receiving and demodulating S/N value information of a transmission line to the other station from the other station and detecting the S/N value; an output of the first means; and an output of the second means. a third means for comparing the difference between the two and a predetermined constant value and detecting a value corresponding to the error value obtained by the comparison;
means for varying the transmission power of its own station in response to the output of the third means; and modulating the information on the S/N value detected by the first means together with the input of the transmission baseband signal, 1. A transmission power control method for an earth station apparatus, comprising: means for applying to an input side a signal varied by a transmission power variable means.