JP3155051B2 - Transmission power control method - 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 system, and more particularly, to a transmission power control system in an earth station of a satellite communication system.

In a satellite communication system, signal power called rain attenuation occurs due to rain due to the frequency used (for example, Ka band or Ku band). Since this appears to the system as a result of deterioration of the line quality, the earth station of the satellite communication system must be designed with a transmission power that allows for rain attenuation.

On the other hand, from the viewpoint of the economics of the system, it is not preferable to always operate with excessively large transmission power. In addition, the use efficiency of the satellite transponder is reduced due to excessive input power, and the transmission to adjacent satellites is reduced. Interference occurs.

[0004] Therefore, in order to maintain the reliability of the system, only the earth station in the area where rain is occurring is considered as the signal reaching the satellite in consideration of the rain attenuation of the uplink from the earth station to the satellite repeater. It is necessary to keep the power constant.

[0005]

2. Description of the Related Art As a conventional example of a transmission power control method, there is a method of using a radio wave unidirectionally transmitted from a satellite called a beacon in addition to a radio wave used for data / information communication in order to obtain control information. is there. This transmission power control method compensates for uplink rain attenuation. However, since the beacon signal is affected only by the downlink rain attenuation from the satellite repeater to the earth station, the uplink and downlink are controlled. The effect of the downlink is removed from the satellite-turned local station signal affected by both links, and the rain attenuation of the uplink is obtained.

In this system, it is necessary to prepare a receiver exclusively for the beacon signal, which inevitably increases the scale of hardware. (Circuit scale issue)

On the other hand, it is also possible to autonomously form a feedback loop and perform transmission power control using the local station signal of the satellite return as an information source. In this scheme, no beacon is used, but the local station signal of the satellite return includes the effects of rain attenuation on both the uplink and the downlink.

In this case, it is impossible to measure the signal power reaching the satellite. Therefore, during rainfall, it is necessary to divide the rain attenuation of both the uplink and the downlink for each link and to estimate whether the power reaching the satellite is the same as the value in fine weather, You just need to know. (The problem of difficulty in generating control information)

By the way, in a transmission power control system in which the amount of deterioration of a satellite return local station signal is measured and used as an information source of transmission power control, the control state, that is, the amount of deterioration of a received signal, is always determined at fixed time units. Observation will be reflected in the control at the next time. Here, the information on the control deviation based on the observation includes error factors such as a statistical error due to the restriction of the observation time and an error due to imperfection of the measuring means,
If the transmission power is controlled directly by using this, the transmission power fluctuates due to the influence of the error, and the transmission power cannot be controlled smoothly and stably against sudden disturbance. (Problems of smoothness and stability of control)

Accordingly, the present invention provides a transmission power control method for compensating rain attenuation in an uplink from an earth station to a satellite repeater and making the power reaching the satellite repeater constant regardless of the rain attenuation. Another object of the present invention is to reduce the circuit scale, facilitate the generation of control information, perform control smoothly, and enhance safety.

[0011]

First, in order not to increase the circuit scale, it is desirable to use only radio waves used for communication. Therefore, it is conceivable to receive the signal of the own station which is turned back to the satellite, measure the influence of rainfall attenuation that is being affected by the signal, and control the transmission power which is constant at a value in fine weather.

By the way, the signal of the satellite return includes both effects of rain attenuation on the uplink and rain attenuation on the downlink. Therefore, in the transmission power control method of making the signal power reaching the satellite constant at the value in fine weather as considered in the present invention, the value of the transmission power at that time (based on the value in fine weather) and It is necessary to estimate the value of the signal power reaching the satellite at that time (also based on the value in fine weather) from the measured value of the rain attenuation included in the local station signal returned by the satellite.

[0013] Here, with respect to the local station signal returned by the satellite, the rain attenuation in the uplink and the downlink can be decomposed into a certain ratio.

First, since the uplink and the downlink physically pass through the same rainfall area as shown by hatching in FIG. 1, the rainfall intensity is equal for both links, and the rain attenuation The amount is related to the rainfall intensity and the frequency of the radio wave, but if the rainfall intensity is equal and the uplink frequency and the downlink frequency are determined, the rainfall attenuation in the uplink and the rainfall attenuation in the downlink This is because a constant ratio depends only on the frequency relationship (see FIG. 2A).

Therefore, utilizing this fact, in each transmission power control system according to the present invention, as shown in principle in FIG. 1, a modulator 3 and a transmission power control unit for controlling the output of the modulator 3 are provided. 4, an outdoor device 5 that transmits the output of the transmission power control unit 4 to the satellite repeater 2 and receives the local signal returned by the satellite relay 2, and a demodulation that demodulates the preamble signal received by the outdoor device 5. And a C / N conversion unit 7 for calculating the actual measured C / N of the signal of the own station from the output of the demodulator 6, and the transmission power increase rate X at the present time with respect to fine weather and the actual measured C / N. Arithmetic unit 8 for extracting information for controlling transmission power at the next time
And a loop filter 9 for averaging the control signal for controlling the transmission power increase rate X from the arithmetic unit 8 and supplying the control signal to the transmission power control unit 4. A delay unit 10 for correcting a time lag until the control of the transmission power derived from the radio wave propagation time between the earth stations 1 is reflected in the actual measurement C / N, and the signal power reaching the satellite repeater 2 is In order to make the value equal to the value at the time of fine weather, calculation and control are performed by each of the different methods of the present invention in the "calculation unit 8" described below.

[0016] The first calculation method Figure 2 (b) according to the invention shows a relationship between the signal power Y and rainfall intensity R reaching the satellite, to be controlled transmission power (TPC = OF
F: Dotted line) The signal power Y reaching the satellite is attenuated by the uplink rain attenuation Lu, and when transmission power control is ideally performed (TPC = ON: steady state shown by a thick line) ,
The transmission power is increased so as to correct the uplink rain attenuation Lu, and the signal power Y reaching the satellite is fine Y
It has the same value as ₀ .

FIG. 2C shows the rain intensity R and the amount of deterioration of the preamble signal of the local station after the satellite return, when the weather is fine.
(TPC = OFF: dotted line), the C / N suffers both uplink and downlink rain attenuation, but the transmission is not controlled. When the power is ideally controlled (TPC = ON: steady state indicated by a thick line), the signal power Y reaching the satellite should be the same as when the weather is fine, so the satellite repeater 2 transmits The output power to the station 1 is also equal to that in fine weather. Therefore, the reception C / N of the earth station 1 suffers only the downlink rain attenuation Ld.

Now, assuming that the rainfall intensity is R, the frequency of the uplink is fu, and the frequency of the downlink is fd,
The rain attenuation Lu of the uplink and the rain attenuation Ld of the downlink are calculated as follows: Lu = Lu (R; fu) (> 0) [dB] (1) Ld = Ld (R) ; fd) (> 0) [dB] ... (2)

At this time, the transmission power at fine weather transmission power (R = 0)
Assuming that the increase rate with respect to X is [dB], the reception C / N of the local station signal of the satellite return is [C / N] = [C / N] ₀ −Lu−Ld + X (3) Here, [C / N] ₀ is fine weather and the transmission power is the reference value (X
= 0) is the reception C / N.

If the transmission power control is in its steady state (TPC = ON)
If it has reached −L + X = 0, that is, Lu = X... (4), and in this case, the received C / N is [C / N] = [C / N] ₀ −Ld … (5).

From the above equations (1) and (4), in the steady state of the transmission power control, X = Lu (R; fu) (6) as in the graph of Lu in FIG. 2 (a).

Therefore, in the graph of FIG. 2A, the ordinate can be taken for X as well as L, and this is solved for R corresponding to a certain X from the graph, and R ′ = R (X; fu) ... Substituting equation (7) obtained as (7) into equations (2) and (5), [C / N] '= [C / N] ₀ -Ld = [C / N] _0- Ld (R ′ = R (X; fu); fd) (8) is obtained.

Equation (8) is the transmission power value X at that time.
Assuming that Lu has been just corrected, the rainfall intensity R 'corresponding to X at that time is obtained according to the uplink Lu characteristic of FIG. 2 (a), and the obtained R' This means that the reception C / N can be estimated by calculating Ld from the Ld characteristic, and the reception C / N is estimated from the transmission power increase rate X.

However, if the transmission power value is completely
If Lu is not corrected, that is, if Lu> X (9), the estimated rainfall intensity R 'at this time is as shown in FIG.
From the Lu graph, the rainfall intensity is smaller than the actual rainfall intensity R, R> R '= R (X; fu) ... (10), and the estimated [C / N]' (= [C / N] ₀ − Ld (R '= R (X; f
In the case of u); fd)), Ld becomes smaller by estimating the rainfall intensity smaller, so that it becomes higher than the actually measured [C / N].

Therefore, if the estimated [C / N] ′ is higher than the actual measurement [C / N], it indicates that the power reaching the satellite repeater 2 is insufficient, and the next time It is sufficient to make the transmission power higher than that at present.

By repeating this operation, the estimated [C / N] 'is measured.
To be equal to [C / N], in other words, the estimated rainfall intensity
Control X so that R (X; fu) is equal to the actual one.

Conversely, when the transmission power value is equal to or greater than Lu, Lu <X... (11), and the estimated rainfall intensity R ′ is larger than the actual rainfall intensity R, and R <R '= R (X; fu)… (12) and estimated [C / N]' (= [C / N] ₀ − Ld (R '= R (X; fu); fd))
Is lower than the actual measurement [C / N], so the estimated [C
/ N] 'is lower than the actual measurement [C / N], the transmission power increase rate X at the next time should be smaller than the current one.

This operation is repeated and the estimated [C / N] '
Is equal to the measurement [C / N], in other words, by controlling the transmission power increase rate X such that the estimated rainfall intensity R ′ = R (X; fu) is equal to the actual rainfall intensity R 1 In addition, the power of the arrival signal of the satellite repeater 2 can be controlled to a constant value in fine weather.

[0029] Even when calculation method the according to the second invention, firstly it is assumed that an increase rate X of the transmission power is exactly correct the rain attenuation Lu uplink, the above equation
Assume (6).

If this assumption is correct, there is no need to further control the transmission power. Conversely, if the assumption is not correct, the transmission power at the next time is controlled based on information on how the transmission power is incorrect.

From equation (6), this is obtained for a certain rainfall intensity R from the graph of FIG. 2 (a) to obtain Ru = Ru (X; fu) (13).

By transforming equation (8), the following equation is obtained: [C / N] _0- [C / N] = Ld (R; fd) (14) That is, the amount of deterioration of C / N from fine weather is
As shown by the bold line in Fig. 2 (c), the rain attenuation of the downlink
Since it should be equal to Ld, this is obtained for the rainfall intensity R, and the following is obtained: Rd = Rd (Z; fd) (15) Here, Z indicates the vertical axis of FIG. 2 (c), and Z = [C / N] ₀ − [C / N] (16).

Then, Ru and Rd are compared, and if they are equal, the above assumption is correct, and if they are not equal, the assumption is incorrect.

That is, the transmission power value at that time does not correctly correct the uplink rain attenuation Lu.

In fact, if Ru> Rd, then X is too large (the rate of increase in transmission power is greater than the uplink rain attenuation Lu), and conversely, if Ru <Rd, X is too small.

Therefore, If the rate of increase X of the transmission power is controlled based on the following algorithm, the hypothetical equation (6) is finally established,
The desired transmission power control can be performed.

Third Calculation Method According to the Present Invention Assuming the equation (6), the transmission power is controlled based on whether or not an estimated value based on this is equal to an actual value.

Also in this case, assuming that the transmission power value at that time correctly corrects the uplink rain attenuation Lu, the equation is obtained from the deterioration amount of the reception C / N in the second method.
From the rain intensity Rd obtained from (15) and Fig. 2 (c), Fig. 2 (a)
In contrast, the transmission power increase rate X '(based on the value in fine weather) can be estimated.

That is, by substituting Rd for R in the equation (6), X '= Lu (Rd; fu) (18) is obtained.

By comparing this with the actual transmission power increase rate X,
If they are equal, the assumption is correct, and if they are not equal, the assumption is incorrect.

In fact, X> X 'is because the transmission power is unnecessarily increased, and conversely, X <X' is when the transmission power is insufficient and the rain attenuation of the uplink is corrected. This is because they have not run out. Therefore, Then, the assumed equation (6) finally holds, and the desired transmission power control can be performed.

Operation of the Loop Filter In each of the methods in the arithmetic unit 8 of the present invention described above, various controls are performed based on the result of the C / N measurement for the local station preamble signal of the satellite return and the transmission power increase rate X at the current time. Although the transmission power increase rate X itself does not have an error-causing factor, the C / N measurement does not include statistical errors due to the finite measurement time and imperfections in the measurement system. It includes the measurement error caused. In addition, since the rainfall intensity and the transmission power increase rate are estimated from the measured C / N values, there is a problem of error propagation in those estimated values.

Unnecessary fluctuations and control errors occur in the operation of the control system based on the control information including the error as described above. If the loop filter 9 is not introduced into the control loop, FIG.
As shown in, for example, rainfall occurs at time t _1,
Assuming that reached a steady state in the sense of the rainfall intensity at time t _2, the by various error factors, the average ideal control system although the same control as the transmit power value at each time is shown by a dotted line Fluctuates around the ideal value.

Therefore, the error factor included in the control information from the arithmetic unit 8 is regarded as a kind of noise and the low-pass filter 9
By performing filtering (qualitatively averaging in a qualitative manner) to give a transfer function of a response slower than the radio wave propagation delay between the satellite repeater 2 and the earth station 1 as shown in FIG. Controls the transmission power control unit 4.

[0045]

DESCRIPTION OF THE PREFERRED EMBODIMENTS In the following description of the embodiments, it is assumed that the rain attenuation is simply proportional to the rain intensity as follows. Up ring Lu = ku · R (ku = constant) Down ring Ld = kd · R (kd = constant)

FIG. 4 shows a first embodiment of the present invention which is executed by the arithmetic unit 8 shown in FIG.
FIG. 2A shows an embodiment of the present invention, in which the transmission power increase rate x from the delay
A multiplier 81 that multiplies the ratio Kd / Ku between the slope Ku of the uplink rain attenuation characteristic Lu with respect to the rain intensity R and the slope Kd of the downlink rain attenuation characteristic Ld with respect to the rain intensity R shown in FIG.
, A subtractor 82 for subtracting the output of the multiplier 81 from [C / N] ₀ in fine weather, and a reception C / N output from the C / N conversion unit 7.
And a subtracter 83 for subtracting the output of the subtractor 82 from the output of the subtracter 82 and applying the result to the loop filter 9.

Next, the operation of this embodiment will be described. Assuming that the transmission power increase rate X just compensates for the uplink rain attenuation Lu, as described above, X = Lu = kuR. 20). Therefore, the received C / N is represented by [C / N] = [C / N] ₀ −kdR (21), and is affected only by the rainfall attenuation in the downlink as described above.

This is equivalent to assuming that the rainfall intensity of the uplink when the transmission power is increased by X is R '= X / ku (22). Under this assumption,
The received C / N can be estimated by substituting R 'for R on the right side of equation (21). That is, [C / N] ′ = [C / N] ₀ −kdR ′ = [C / N] ₀ −kdX / ku (23)

This corresponds to the multiplier 8 in the operation unit 8 shown in FIG.
1 and the subtraction unit 82. The estimated [C / N] 'and the actual reception [C / N] output from the C / N conversion unit 7 shown in the above equation (3). ] = [C / N] _0- Find the difference from Lu-Ld + X. [Estimated C / N]-[Measured C / N] = [C / N] '-[C / N] = [C / N] _0- kdX / ku-([C / N] _0- kuR-kdR + X) = (KuR-X) + (kd / ku) (kuR-X) = (kuR-X) (1 + kd / ku) ... (24)

Therefore, Becomes That is, when [estimated C / N]> [actual measured C / N], the transmission power increase rate X at that time is calculated from kuR in equation (20), which assumes that the uplink rain attenuation Lu is just compensated. Small, insufficient, [estimated C / N] <[actual C / N]
X indicates that it is too large.

Therefore, [Estimated C / N] − [measured C / N] for performing such control is provided to the transmission power control unit 4 via the filter 9.

FIG. 5 shows a second embodiment of the present invention which is executed by the arithmetic unit 8 shown in FIG.
FIG. 2A shows an embodiment of the present invention, in which the transmission power increase rate x from the delay
A multiplier 84 that multiplies the reciprocal 1 / Ku of the slope Ku with respect to the rain intensity R of the rain attenuation amount characteristic Lu of the uplink shown in FIG. 7 and the reception output from the C / N conversion unit 7 from [C / N] _{0 in} fine weather A subtractor 85 for subtracting C / N; a multiplier 86 for multiplying the output of the subtractor 85 by the reciprocal 1 / Kd of a slope Kd with respect to the rainfall intensity R of the downlink rain attenuation characteristic Ld; And a subtracter 87 which obtains the output difference between the signals and 86 and supplies the output difference to the loop filter 9.

In the case of the second present invention, as in the first present invention, the increase rate X of the transmission power is estimated from the transmission power on the assumption that it is just compensating for the rainfall attenuation of the uplink. The rain intensity is Ru ′ = X / ku (27), and is given by the multiplier 84.

The rainfall intensity from the downlink from the received C / N is given by [C / N] = [C / N] ₀ −kdR (28), and solving for R gives Rd ′ = Z / kd (29), which is given by the multiplication unit 86. This is Figure 2
The rainfall intensity shown in (c) is shown.

Here, Z = [C / N] ₀ − [C / N] = kuR + kdR−X (30) is given by the subtraction unit 85, and Rd ′ = 1 / kd · (kuR + kdR− X) ... (31) Comparing this with Ru ', Ru'-Rd' = X / ku-1 / kd. (KuR + kdR-X) = (X-kuR) / ku + (X-kuR) / kd = (X-kuR) ( 1 / ku + 1 / kd)… (32)

From this, It has become.

That is, when Ru′−Rd ′> 0, the transmission power is too high, and conversely, when Ru′−Rd ′ <0, the transmission power is too low.

Therefore, the output Ru′−Rd ′ of the subtractor 87 gives The transmission power control unit 4 is controlled via the filter 9 such that

FIG. 6 shows a third embodiment of the present invention which is executed by the arithmetic unit 8 shown in FIG.
In this embodiment, the reception C / N output from the C / N conversion unit 7 from [C / N] _{0 in} fine weather is shown.
Subtractor 88, and the output of the subtractor 88 is compared with the ratio Ku.
/ Kd, and a subtractor 90 for subtracting the output of the multiplier 89 from the transmission power increase rate X from the delay unit 10.
It is composed of

This embodiment is based on estimating the transmission power increase rate X at that time from Rd 'in the second present invention.

That is, when the rainfall intensity of the downlink is Rd ′, the required increase rate of the transmission power is as follows: X ′ = kuRd ′ (35) = ku (1 / kd · (kuR + kdR−X)) (36) ). This equation (36) is represented by ku / kd · Z from the above, and can be generated by the subtractor 88 and the multiplier 89. By comparing this with the actual transmission power X, X−X ′ = X−ku / kd · (kuR + kdR−X) = (X−kuR) + ku / kd · (X−kuR) = (X−kuR) (1 + ku / kd) (37) It has become.

That is, when X−X ′> 0, the transmission power is too high, and conversely, when X−X ′ <0, the transmission power is too low.

Therefore, May be performed on the transmission power control unit 4 from the subtractor 90 via the filter 9.

Embodiment of Loop Filter A specific configuration example of a loop filter of a transmission power control loop usable in each of the above embodiments will be described.

(I) Moving average type low-pass filter As the simplest embodiment of the loop filter, as shown in FIG. 7, N-1 delay elements T, an adder ADD, and a divider A
And a moving average type filter that outputs the average value of the control deviation information over the past N data can be used.

The frequency characteristic of this filter has a form of sin (f) / f where f is the frequency. As shown in FIG. 8, when the average is calculated, appropriate weighting coefficients a ₀ to a _N−1 are set. It is also possible to multiply and output a weighted average. In this case, the loop filter is equivalent to a general transversal digital filter, and a weighting coefficient that realizes a desired frequency characteristic may be selected.

(Ii) Completely integrating low-pass filter As the loop filter, a completely integrating low-pass filter can be used. For example, a multiplier M1 having multiplication coefficients α and β as shown in FIG. , M2, adders 91 and 92, and a delay element T.
A non-linear integrator including a sign determination unit 94 and an up / down counter 95 as shown in FIG. When these are used, the control deviation information required for this control system need not be a strict control deviation. In this embodiment, at least, control can be performed such that the control deviation is set to 0 in the steady state of the control loop only by knowing the sign of the control deviation.

[0068]

As described above, in the transmission power control method according to the present invention, it is assumed that the increase rate of the transmission power at the present time with respect to the fine weather compensates for the rain attenuation in the uplink. Rain attenuation
The C / N is estimated as being equal to the degradation of the C / N, and the estimated C / N and the measured C / N are equal, and the uplink and downlink rainfall intensities are estimated. And the transmission power increase rate at the next time is controlled so that the transmission power increase rate is estimated to be equal to the actual transmission power increase rate. And without the need for hardware for it, it is possible to control the transmission power with gentle and stable operation by introducing a loop filter based on the transmission power value and the control information based on the C / N measurement of the local signal of the satellite loopback. Become.

[Brief description of the drawings]

FIG. 1 is a block diagram illustrating the principle of a transmission power control method according to the present invention.

FIG. 2 is a graph showing various control characteristics used in the present invention.

FIG. 3 is a graph for comparing characteristics when a loop filter is used and when it is not used.

FIG. 4 is a diagram showing one embodiment of the first present invention.

FIG. 5 is a diagram showing an embodiment of the second invention.

FIG. 6 is a diagram showing an embodiment of the third invention.

FIG. 7 is a diagram showing an embodiment of a low-pass filter.

FIG. 8 is a diagram showing another embodiment of the low-pass filter.

FIG. 9 is a diagram showing still another embodiment of the low-pass filter.

FIG. 10 is a diagram showing still another embodiment of the low-pass filter.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Earth station 2 Satellite repeater 3 Modulator 4 Transmission power control part 5 Outdoor equipment 6 Demodulator 7 C / N conversion part 8 Operation part 9 Loop filter 10 Delay device In the figure, the same code shows the same or corresponding part.

──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Tokihiro Miyo 1015 Uedanaka, Nakahara-ku, Kawasaki City, Kanagawa Prefecture Inside Fujitsu Limited (72) Inventor Hiroshi Kazama 1-1-6 Uchisaiwaicho, Chiyoda-ku, Tokyo Nippon Telegraph and Telephone (56) References JP-A-62-188438 (JP, A) JP-A-63-173426 (JP, A) JP-A-1-115227 (JP, A) JP-A-2-241234 (JP, A A) JP-A-5-63622 (JP, A) JP-A-62-7223 (JP, A) JP-A-62-154926 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) ) H04B 7/14-7/22 H04B 1/04

Claims (3)

(57) [Claims] 1. A transmission power control for compensating rain attenuation in an uplink from an earth station (1) to a satellite repeater (2) so that power reaching the satellite repeater is constant regardless of the rain attenuation. In the system, a modulator (3), a transmission power control unit (4) for controlling the output of the modulator (3), and an output of the transmission power control unit (4) are transmitted to the satellite repeater (2). And an outdoor device (5) for receiving the local signal returned by the satellite repeater (2), and a demodulator for demodulating the local signal received by the outdoor device (5).
(6), a C / N conversion unit (7) for calculating an actual measurement C / N of the own station signal from an output of the demodulator (6), and a transmission power increase rate (X) at the present time with respect to fine weather. An arithmetic unit (8) for extracting control information of transmission power at the next time from the measured C / N and the control signal for controlling the rate of increase (X) of the transmission power from the arithmetic unit (8). A loop filter (9) to be provided to the transmission power control section (4) and a control signal indicating an increase rate (X) of the transmission power.
(2) a delay unit (10) for correcting a time lag until the control of the transmission power derived from the radio wave propagation time between the earth stations (1) is reflected in the actually measured C / N. An arithmetic unit (8) inputs a control signal indicating the actual measurement C / N and the transmission power increase rate (X) from the delay unit (10),
It is assumed that the current transmission power increase rate (X) with respect to the fine weather just compensates for the rain attenuation (Lu) in the uplink, and that the downlink from the satellite repeater (2) to the earth station (1) is down. Assuming that the rain attenuation of the link (Ld) is equal to the degradation of the measured C / N, the reception C / N is estimated from the increase rate (X) of the transmission power, and the estimated C / N ([C / N N] ') and the transmission power increase rate (X) at the next time is controlled so that the measured C / N becomes equal to the measured C / N. 2. The arithmetic unit (8) estimates an uplink rain intensity (Ru) corresponding to the transmission power increase rate (X) instead of estimating the C / N, and C / from fine weather
Assuming that the N degradation amount ([C / N] _0- [C / N]) is due to the rain attenuation of the downlink, the rainfall intensity (R
2. The transmission power control method according to claim 1, wherein d) is estimated, and the transmission power increase rate (X) at the next time is controlled so that both rainfall intensities (Ru, Rd) become equal. 3. The arithmetic unit (8) further estimates a transmission power increase rate (X ′) based on a value in fine weather from the rainfall intensity (Rd) corresponding to the C / N deterioration amount, The transmission power control method according to claim 2, wherein the transmission power increase rate (X) at the next time is controlled so that the transmission power increase rate (X) becomes equal to the actual transmission power increase rate (X).