JPH0262132A - Transmission power control method in satellite communication - Google Patents

Abstract

PURPOSE:To unify a satellite arrival electric power by providing plural pilot signal transmitting stations, transmitting a single frequency different from the frequency used by a satellite communication with time division and variably controlling a transmitting electric power in accordance with the minimum attenuation quantity of plural pilot signals. CONSTITUTION:Pilot signal transmitting stations 71-7m mutually transmit the pilot signal of a single frequency different from the frequency used by the communication between earth stations 61-6n with time division. A detecting means 8i of an earth station compares an adjoining receiving pilot signal level which the same number as the transmitting stations 71-7m and detects the minimum attenuating quantity. A control means 9 controls the transmitting electric power in accordance with the minimum attenuating quantity. By the constitution, even in the satellite communication system not having a beacon transmitting function, the attenuating quantity of the uplink due to the rainfall, etc., is detected and the satellite arrival electric power can be constantly controlled.

Description

[Detailed Description of the Invention] (Summary) Regarding a transmission power control method that keeps the power arriving at a satellite constant and reduces line downtime without adversely affecting satellite repeaters, it is possible to reduce the hardware scale without using beacon signals. The purpose of this satellite communication is to control the transmission power of the earth station so that it reaches the satellite at a constant power without increasing the power too much. A plurality of pilot signal transmitting stations are installed that time-divisionally transmit pilot signals of a single frequency different from the frequency used in the satellite communication mentioned above, and the pilot signal transmission stations are sequentially received, and one of the pilot signals is Detection means for detecting the smallest attenuation fu by comparing the levels of the same number of adjacent received pilot signals as signal transmitting stations, and control means for variably controlling transmission power according to the minimum attenuation detected by the detection means. and are provided at each of the earth stations.

[Industrial application field]

The present invention relates to a transmission power control system in satellite communications, and particularly to a transmission power control system that maintains the power arriving at a satellite constant and reduces line unavailability without affecting the satellite repeater.

In satellite communications, in which communication is performed between a large number of earth stations using one satellite as a relay station, the power transmitted from the earth station is reduced mainly due to rainfall, and in severe cases, communication becomes impossible.

For this reason, in satellite communications, it is necessary to know the amount of attenuation due to rain by some method, and increase the transmit power of the earth station by the amount of attenuation, thereby reducing the line downtime. However, if the transmission power is increased by compensating for rain on the downlink, more power than on a clear day will be input to the satellite repeater, which may have an adverse effect on the satellite repeater. Therefore, transmission power is usually controlled to compensate only for uplink rain.

[Prior Art] FIG. 6 shows the configuration of an example of a transmission power control system in conventional satellite communication. In the figure, 1 is a satellite, 2 is an earth station, and earth station 2 uses satellite 1 as a relay station to communicate with other earth stations (not shown).
communicate with.

Conventionally, WI star 1 transmits a beacon signal to earth station 2, and earth station 2 receives this and measures the level or C/N (carrier-to-noise ratio) of the beacon signal. Measure the downlink attenuation due to 3. The earth station 2 estimates the uplink attenuation amount from this downlink attenuation amount, increases the transmission power based on this, and performs transmission.

In this way, even if there is rain 3, the power reaching the satellite 1 is the same as when it is a sunny day, and the line downtime rate is significantly reduced.

This conventional method is effective because it is simple and the hardware scale is quite small.

(Problem to be Solved by the Invention) However, the above conventional method requires the satellite 1 to have a beacon signal transmission function, and therefore has the drawback that it cannot be applied to a satellite that does not have a beacon signal transmission function.

The present invention has been made in view of the above points, and is a satellite communication system that enables the transmission power of an earth station to be controlled so that it reaches the satellite at a constant power level without using beacon signals or without significantly increasing the hardware scale. The purpose of this study is to provide a transmission power control method for

[Means to solve the problem]

In order to achieve the above object, the present invention has a configuration as shown in FIG. In Figure 1, 5 is a satellite, 61-6
n is a large number of earth stations, and in a satellite communication system consisting of these, the present invention provides pilot signal transmitting stations 71 to 7TT+, and detecting means 81 to each of the earth stations 61 to 61.
-8n and control means 91-9Tl are provided.

The pilot signal transmitting stations 7+ to 7m time-divisionally transmit pilot signals having a single frequency different from the φ frequency used for communication between the earth stations 6 to 6T1.

Further, the detection means 81 to 8n are the pilot signal transmitting stations 71 to 8n.
The smallest attenuation amount is detected by comparing the levels of the same number of adjacent reception pylon 1 signals as 7m.

Further, the control means 91 to 91 control the transmission power according to the minimum attenuation amount.

[Effect]

Instead of sending out a beacon from a satellite, one idea would be to provide one pilot signal transmitting station and use that pilot signal instead of the beacon signal.

However, with this alone, the rain falling at the pilot signal transmitting station causes the earth station to receive an attenuated signal even though it is a clear day. Since the signal from the receiving pylon 1 is similarly attenuated when the rain is falling, the earth station that is transmitting cannot tell which side it is raining on.

For this reason, even when it is raining at the pilot signal transmitting station, the transmission power is increased, which adversely affects the Gongsei 5.

Therefore, as shown in Fig. 1, multiple pilot signal transmitting stations 71 to 7m are provided geographically apart from each other, and their pilot signals are received, and their received pilot signal levels are compared. Control transmit power based on each received pilot signal level.

The probability that it will rain at all of the pilot signal transmitting stations 71 to 7m at the same time is extremely small, almost zero. here,
Pilot signal transmitting station 71-7m and any earth station 61
When all of the received pilot signals are under clear skies, the attenuation values of all received pilot signals detected by the detection means 81 are zero, so the control means 91 performs transmission at a predetermined transmission power based on this.

Next, when it is raining only at the earth station 61 and it is clear weather at all of the biloft signal transmitting stations 71 to 7m, the attenuation amount of all received pilot signals detected by the detection means 81 is the same, and Since the amount of attenuation depends on the amount of rainfall, the control means 9 controls the transmission to be performed with a power greater than the predetermined transmission power so as to correct this amount of attenuation.

Next, when the earth station 61 and pilot signal transmitting stations 71 to 7yn (m-1) or lower stations are raining, only the received pilot signal from the pilot signal transmitting station that is not raining will be received. This correctly indicates the attenuation due to rain at the earth station 61, and since the amount of attenuation of this received pilot signal is the minimum, the detection means 81 detects this minimum amount of attenuation. The control means 91 controls the transmission power so that this minimum attenuation becomes zero.

The same operation as above is performed for the other earth stations 62 to 6n. Note that the control means 91 to 9η are the detection means 81 to 81.
Since the detected minimum attenuation amount indicates the downlink attenuation amount, the uplink attenuation amount is estimated and the transmission power is controlled.

In addition, if it is not raining at the earth stations 61 to 6n, but it is raining to (m-1) or more of the pilot signal transmitting stations 71 to 7m, the received pilot signal The received pilot signal with the least amount of attenuation among the levels is from a pilot signal transmitting station when it is not raining, and the attenuation for all the stations mentioned above is zero, which is the same as when it is sunny, so increase the transmit power. It will not be stored away, and there will be no negative impact on Satellite 5.

By the way, if the pilot signals transmitted by the pilot signal transmitting stations 71 to 7m are all different from each other, it will be disadvantageous in terms of both frequency and power. Therefore, in the present invention, based on the empirical rule that rainfall does not change rapidly over time, the pilot signal frequency is set to only a single frequency, and it is transmitted in a time-division manner. In this case, the detection means 81 to 8Tl do not know from which pilot signal transmitting station the received pilot signal was transmitted, but the pilot signal is detected by the pilot signal transmitting station 7.
Adjacent m received pilot signals, which are the same number as 1 to 7m, are transmitted from the pilot signal transmitting stations 71 to 7m, respectively.
The minimum capital reduction hI is detected from among these pilot signals.

In this way, according to the present invention, even in satellite communication using a satellite without a beacon transmission function, uplink attenuation 1 due to rain or the like at the earth station can be known using the pilot signal.

〔Example〕

FIG. 2 shows a configuration diagram of an embodiment of the system of the present invention.

In the figure, the same components as in FIG. 1 are given the same reference numerals. In FIG. 2, 6 is any one of the earth stations 61 to 6n (hereinafter referred to as station 0 for convenience), and 71 and 72 are the pilot signal transmitting stations when m=2 (hereinafter these are referred to as station 0). For convenience, it will be referred to as station A and 8 rounds). A station 7
Stations 1 and 8 72 each alternately transmit pilot signals of the same frequency.

Fig. 3 (A> schematically shows the timing of the transmission pilot signal of the A station 7I, and the timer unique to the A station 7I repeats that the period TA pilot signal is transmitted and the period SA transmission is stopped. The period (TA +
SA ) is, for example, about several seconds.

On the other hand, as schematically shown in FIG. 3(B), the 8th station 72 is
The transmission pilot signal of station 71 is received, and the guard time Δ
After B, transmitting a pilot signal for a period Ta (=T^) and then stopping transmitting a pilot signal for a period Ss (=SA) is repeated.

Note that in FIG. 3(B), τ indicates a delay time due to transmission and reception via the satellite 5. There is no problem with the time ΔB using a timer unique to the 8th station 72.

In this way, the transmission timing between the A station 71 and the 8th station 72 can be set as long as there is sufficient guard time such as satellite delay.
There is no need for strict synchronization.

In a more simplified method, after obtaining the - degree timing, the eight stations 72 may use their own timer to repeat period To transmission and period SB transmission stop, and periodically correct the timing at appropriate times.

The pilot signal transmitted in a time-division manner in this way is
As shown in the figure, the signal is relayed by satellite 5 and received by station 0 6. This received pilot signal of station 0 6 is shown in Fig. 3 (C
), one of the two adjacent received pilot signals is from station A 71, and the other is from station 8 72.

Now, among these two adjacent received pilot signals, the level (received power) PA of one received pilot signal changes as shown by the solid line ■ in FIG. 4(A), and the level (received power) of the other received pilot signal It is assumed that the received power) Pa changes as shown by the broken line ■ in FIG. In this case, the attenuation 1ffi shown by α and γ in FIG. 4(A) is smaller than the attenuation amount of the other received pilot signal, and this attenuation amount α,
γ is the received pilot signal from the pilot signal transmitting station that is not raining among the attenuation caused by raining at either station A 7I or station 8 72 (0 station 6). Therefore, at this time, as shown in FIG. 4(B), station 0 6 transmits with transmission power corresponding to α and γ.

Furthermore, when both the above received pilot signals PA and PB have the same attenuation β as shown in FIG. 4(A),
Is it raining at both A station 7I and 8 station 72 at the same time?
Or, it is raining only at station 0 and 6. However, since the A station 71 and the 8th station 72 are located geographically apart from each other so that it does not rain at the same time, it can be assumed that only the 0th station 6 is raining in the above case.

Therefore, in this case, as shown by β in FIG. 4(B), station 0 6 transmits by increasing its transmission power by an amount that compensates for the attenuation amount β.

Next, the configuration of one embodiment of the earth station (0 station) 6 will be described with reference to FIG. 5. In the figure, 8 is a detection means, 9 is a control means, and the detection means 81 to 8n and the control means 91 in FIG.
The detection means and control means for any one of ~9Tl are shown. At J3 in FIG. 5, the received pilot signal that has been discriminated and separated from the signals received by the earth station is supplied from the input terminal 11 to the carrier level detector 12 and the C/N measurement circuit 13, respectively.

The C/N measuring circuit 13 measures the attenuation m (assuming it is a sunny day) from the C/N ratio of the received pilot signal, and uses the measurement result as a buffer? 14 and 15 sequentially. On the other hand, carrier level detector 12 detects the presence or absence of a received pilot signal from its carrier level, outputs a detection signal to buffers 14 and 15 every time a received pilot signal is input, and updates the stored contents.

Therefore, the buffer 14 stores the attenuation m of the received pilot signal at the current time, and the buffer 15 stores the attenuation amount of the previous received pilot signal. The re-accumulated signals (attenuation amounts) of the buffers 14 and 15 are supplied to a comparator 16, where the one with the smaller value (ie, the one with the smaller attenuation amount) is selected.

Since the output signal of the comparator 16 is the amount of downlink attenuation, the amount of uplink attenuation is estimated through the uplink attenuation amount estimator 17, sieved, and supplied to the high power amplifier (HPA) 18, where the gain is variably controlled. do. As a result, it is taken out from the HPA 18 and sent to the satellite 5 via the antenna.
The transmission power of the radio waves transmitted to the 2-bit is equal to the attenuation of the smaller attenuation of the two adjacent received pilot signals.Actually, this is the downlink attenuation, so estimate the uplink attenuation from this. amount). Thereby, it is possible to always ensure a substantially constant power reaching the satellite regardless of the weather at the 0 station 6.

Station 0 6 with such a configuration has a single pilot signal frequency,
Moreover, since only the attenuation amounts of two temporally consecutive received pilot signals are compared, the hardware scale can be small.

On the other hand, since the eight stations 72 require both reception and transmission functions,
It can be replaced by a communications earth station. In addition, since the A station 71 only needs to transmit the pilot signal and does not need modulation,
The scale of the hardware is extremely small, and it is possible to select a location with little rainfall as the installation location.

Note that the present invention is not limited to the above embodiment, and three or more pilot signal transmitting stations may be provided. In this case, the probability that it will rain simultaneously at the installed pilot signal transmitting stations decreases dramatically as the number of stations increases. but,
Even if there are only two pilot signal transmitting stations, there is a high degree of freedom in the installation location of the pilot signal transmitting station having only a transmitting function, so in practice, only two pilot signal transmitting stations are sufficient.

〔Effect of the invention〕

As described above, according to the present invention, a pilot signal is transmitted using the same transceiver as that used for communication, and the amount of uplink attenuation due to rain, etc. at the earth station can be determined using the pilot signal. Therefore, even in satellite communication systems that use satellites that do not have a beacon transmission function, or satellite communication systems that use earth stations where beacon reception is difficult due to problems such as polarization, uplink attenuation can be detected and the satellite ff
The transmission power can be controlled to keep the 1lJ power constant, and the pilot signal is transmitted on a single frequency in a time-division manner, so the hardware scale for controlling the earth station's transmission power can be kept small. It has the following features.

[Brief explanation of the drawing]

Figure 1 is a diagram showing the principle of the present invention; Figure 2 is a diagram showing the configuration of an embodiment of the method of the present invention; Figure 3 is an explanatory diagram of the timing of transmitting and receiving pilot signals from each earth station; Figure 4 is a diagram showing the pilot received power and FIG. 5 is a block diagram of an embodiment of the earth station, and FIG. 6 is an explanatory diagram of an example of the conventional system. Akira Honmaru's construction diagram; 1. In the diagram, 5 is the satellite, 6.61 to 6n are the earth stations, 71 to 7m are the pilot signal transmitting stations, 8.81 to 81 are the detection means, 9.91 91 indicates control means. 7-nail inspector also goes to lecture on the series of missing criminals in the throat Figure 2 Ohsenun+p Furthermore, the earth station's Ichishoya series of pictures and illustrations 5 Figure-C! ) - Ei 1 An example of oracle drawing of Yarisonkyokutsutsutsumi Toga style

Claims (1)

[Claims] A large number of earth stations (6_1 to 6_
n) In satellite communication that performs wireless communication between satellites, a plurality of pilot signal transmitting stations (7_1 to 7_m) are provided that time-divisionally transmit pilot signals of a single frequency different from the frequency used in the satellite communication, and Detection means (8_1 to 8_n) that sequentially receives the pilot signals and compares the levels of the same number of adjacent received pilot signals as the pilot signal transmitting stations (7_1 to 7_m) to detect the smallest amount of attenuation; The detection means (8_
A satellite communication system characterized in that each of the earth stations (6_1 to 6_n) is provided with a control means (9_1 to 9_n) that variably controls transmission power according to the minimum attenuation detected by the earth stations (6_1 to 6_n). Transmission power control method.