JP2004072203A - Wireless communication method for wireless communication apparatus, wireless communication method for wireless communication system, and wireless communication system, and wireless communication apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a communication system for attaining desired reception quality while preventing an average transmission power from being increased even on the occurrence of propagation path gain variations for a comparatively short period. <P>SOLUTION: The wireless communication system controls the transmission power so as to decrease the transmission power when the propagation path gain is decreased and increase the transmission power when the propagation path gain is increased so as to relieve data missing due to reduction in the transmission power through error correction. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a method for controlling wireless transmission power of a wireless communication system, and is particularly suitably applied to a mobile communication system.
[0002]
[Prior art]
2. Description of the Related Art In a wireless communication system, a technique for controlling transmission power of a wireless communication device to obtain a desired reception quality is known. For example, in USP 5,267,262, in a CDMA mobile communication system, a base station measures the signal reception power from a terminal, and if the signal reception power is smaller than a desired value, an instruction to increase the transmission power is given. There is disclosed a technique for transmitting to a mobile station and controlling the transmission power in accordance with the transmission power control instruction, thereby keeping the reception power at the base station substantially constant.
[0003]
In USP 5,559,790, a mobile station measures the reception quality of a pilot signal transmitted by a base station at a known power, and based on the measurement result, when the reception quality is poor, the reception quality is lower than when the reception quality is good. Transmitting a transmission power control signal requesting a large transmission power to the base station, and the base station controls the transmission power of the signal directed to the mobile station based on the transmission power control signal, so that the base station in the mobile station transmits There is disclosed a technique for keeping the signal reception quality substantially constant.
[0004]
All of these techniques aim at controlling the received power and quality on the receiving side to be constant. That is, in the transmission power control method according to the above-described conventional technology, the reception quality is made constant, and the deterioration of the reception quality due to the gain fluctuation of the propagation path and the interference in the system due to the unnecessarily excessive transmission power are prevented. .
[0005]
[Problems to be solved by the invention]
However, if there is fading, which is a relatively short-period channel gain variation that occurs with the movement of the mobile station, using the conventional technique, when the channel gain decreases instantaneously, a very large transmission It becomes power and the average transmission power increases. The increase in the average transmission power increases the mutual interference given to the entire system, and lowers the communication throughput of the entire system. In a terminal, an increase in average transmission power increases power consumption and shortens a communicable time.
[0006]
If the average transmission power is not increased, the average reception power decreases, and the reception quality (SN ratio, SNR) deteriorates with the reduction in the communication channel capacity. That is, the maximum communicable data rate is reduced.
[0007]
[Means for Solving the Problems]
In one aspect of the present invention, control is performed such that the transmission power is increased when the channel gain is increased, and the transmission power is decreased when the channel gain is decreased. Variations in the quality of received data and loss of received data caused by lowering the transmission power when the channel gain is small are relieved by a strong error correction code such as a turbo code.
[0008]
Other aspects of the present invention will be clarified in the embodiments of the present invention.
[0009]
BEST MODE FOR CARRYING OUT THE INVENTION
First, the power control algorithm of the present invention will be described.
[0010]
Now, consider the case where the channel gain fluctuates as shown in FIG. That is, consider a propagation path in which the gains at times t1, t2, t3, and t4 are 2, 1, 1/3, and 2/3, respectively, and the average gain is 1. Assuming that a constant noise is added at power 1 on the receiving side as shown in FIG. 2, this is equivalently equivalent to power 1/2, 1, 1 at times t1, t2, t3, and t4 on the transmitting side as shown in FIG. This is equivalent to the addition of 3, 3/2 noise. That is, a change in the channel gain can be equivalently regarded as a change in the noise power.
[0011]
On the other hand, it is known that the capacity C of the communication path is theoretically C = W log2 (1 + S / N). Here, C is the number of bits that can be transmitted per second, W is the frequency bandwidth, S is the signal power, N is the noise power, and log2 (x) is the logarithm of x with a base of 2. Therefore, the communication channel capacity in the time-varying propagation path is C = Ave (W log2 (1 + S (t) / N, where S (t) is the signal power at time t and N (t) is the noise power). (T))). Here, Ave (x) represents the time average of x. Therefore, when S (t) is temporally changed by power control, the communication channel capacity changes. In the present invention, the transmission power is controlled so as to increase the channel capacity as much as possible. Specifically, the following is performed.
[0012]
Now, consider S (t) that maximizes the channel capacity C when the average transmission power, that is, the time average Ave (S (t)) of S (t) is constant. Since Ave (S (t)) is constant, if the transmission power at one time is increased, the transmission power at another time must be decreased. Here, the rate of increase of C with respect to a small increase of S is dC / dS = W / log (2) / (N + S) according to the definition formula of the communication channel capacity. Distributing the transmission power to the location where N + S is the smallest increases the channel capacity. As described above, when the transmission power is sequentially distributed to the place where N + S is the smallest, N + S is constant when all the power is finally distributed, and in a time zone where N is larger than the achieved S + N. S is not distributed at all, and this state has the largest channel capacity.
[0013]
Here, assuming that the noise power received by the receiver is a function of time Nr (t) and the channel gain is a function of time g (t), the equivalent noise power N (t) seen on the transmitting side is
N (t) = Nr (t) / g (t)
It becomes. Therefore, the transmission power S (t) that maximizes the channel capacity is:
N (t) + S (t) = Nr (t) / g (t) + S (t) = P_const. (Constant)
The condition is satisfied. That is,
S (t) = P_const Nr (t) / g (t)
What is necessary is just to control so that it may become. However, when S (t) <0, the actual transmission power is set to 0 (that is, transmission is stopped). Note that, if P_const is increased, the average transmission power and the channel capacity increase. Conversely, if P_const is reduced, the average transmission power and the channel capacity decrease. Therefore, P_const may be determined to a value that can obtain a desired communication channel capacity.
[0014]
For example, when the average transmission power is set to 1 under the channel gain variation shown in FIG. 1, the transmission power control result is as shown in FIG. In the figure, a portion surrounded by a thick line is signal power, and a portion surrounded by a thin line is noise power. That is, the transmission powers at times t1, t2, t3, and t4 are 11/6, 4/3, 0, and 5/6, respectively. The average transmit power is
(11/6 + 4/3 + 0 + 5/6) / 4 = 1
As shown in FIG. 5, the reception power when the result of the transmission power control of FIG. 4 is viewed on the reception side is 11/3, 4/3, and 3/3 at times t1, t2, t3, and t4, respectively. 0, 5/9.
[0015]
On the other hand, in the power control according to the related art, in order to keep the reception power or reception quality constant, control is performed so that the transmission power is proportional to the noise power as shown in FIG. That is, the transmission powers at times t1, t2, t3, and t4 are 1/3, 2/3, 2,
It becomes 1. The average transmit power is
(1/3 + 2/3 + 2 + 1) / 4 = 1
As shown in FIG. 7, the reception power when the result of the power distribution (transmission power control) in FIG. 6 is viewed on the receiving side is 2/3 at times t1, t2, t3, and t4, respectively. 2/3,
2/3, 2/3.
[0016]
FIG. 8 compares the control of the transmission power with respect to the fluctuation of the channel gain. The horizontal axis indicates the channel gain, and the vertical axis indicates the transmission power as a result of the transmission power control. In the figure, circles indicate the present invention, and diamonds indicate the conventional technology. That is, in the conventional transmission power control, the channel gain and the transmission power are in an inverse relationship, and the transmission power increases when the channel gain decreases, and the transmission power decreases when the channel gain increases. On the contrary, in the present invention, when the channel gain decreases, the transmission power decreases, and when the channel gain increases, the transmission power increases.
[0017]
The channel capacity achieved by the transmission power control according to the present invention is
C = W (log2 (1 + 1/3) + log2 (1 + 4/3) + log2 (1 + 0) + log2 (1 + 5/9)) / 4 = 0.90W
It becomes. On the other hand, the channel capacity achieved by the transmission power control according to the related art is
C = W log2 (1 + 2/3) = 0.707 W
It becomes.
[0018]
Thus, in the example shown here, according to the power control of the present invention, the channel capacity is increased by a factor of 1.27 (= 0.90 / 0.707) as compared with the conventional power control method. On the other hand, in order to achieve the same channel capacity as the channel capacity when the present invention is applied using the conventional transmission power control method, 0.90 = log2 (1 + 0.8661). S / N = 0.8661 is required, and the average transmission power is 1.30 (= 0.8661 / (2/3)) times S / N = 2/3 achieved by the conventional transmission power control. Is required. Therefore, according to the present invention, the transmission power for achieving the same channel capacity is reduced by a factor of 0.770 as compared with the case of using the conventional technique.
[0019]
Although the transmission power control algorithm that theoretically maximizes the channel capacity has been described above, substantially the same effect can be obtained without strictly following the above algorithm. That is, it is possible to perform transmission power using a function that approximates the relationship between the propagation path gain and transmission power shown in FIG. This function desirably has a positive slope as a whole. For example, even a simple function that makes the transmission power proportional to the propagation path gain can obtain substantially the same effect.
[0020]
Note that an algorithm for determining the transmission power
S (t) = P_const Nr (t) / g (t)
According to the above, when the channel gain increases stepwise at time t0 as shown in FIG. 9, the transmission power also changes stepwise as shown in FIG. Also, when a control delay occurs, it changes with a certain rise time as shown in FIG.
[0021]
In the control of FIGS. 10A and 10B, when the mobile station is located near the base station having a large channel gain, the communication channel capacity is large, and conversely, the mobile station is located far from the base station. Sometimes the communication path capacity becomes small. If this difference is not desirable in the system design, for example,
P_const = C0 Ave (Nr (t)) / Ave (g (t))
It is practical to control P_const relatively slowly using the average gain and noise power of the current channel condition as shown in FIG. Here, C0 is a constant. This allows the power control to be applied to short-term fluctuations in the communication path while obtaining a substantially constant communication path capacity regardless of the distance from the base station.
[0022]
In this case, with respect to the channel gain variation shown in FIG.
As shown in FIGS. 10 (c) and 10 (d), in a short time,
It becomes the same transmission power, and then, as with the conventional power control
As gradually approaching the transmission power that cancels the channel gain fluctuation
Indicates a response.
[0023]
According to the above power control, the communication path capacity fluctuates with time. In the conventional power control, the communication path capacity is made constant by making the reception quality constant. Therefore, the communication path has characteristics close to AWGN (Additive White Gaussian Noise, additive white noise), and thus is suitable for the AWGN communication path. Error correcting codes were suitable. On the other hand, in the power control described above, the reception quality varies greatly, and some of the received data is in a state close to missing. Therefore, for relatively short time period fluctuations, the time correlation of the reception quality variation is eliminated by interleaving, and a strong error correction code such as a turbo code is applied. It is preferable that received data of poor quality be remedied by received data of good reception quality. It is also preferable to apply an LDPC (Low Density Parity Check) code or a product code instead of the turbo code. More generally, it is known that a high error correction capability can be obtained by applying iterative decoding in which a large number of bits constituting a code word have a complicated chained dependency and perform decoding again using an intermediate result of decoding. It is preferable to apply the error correction code.
Further, if the state of poor reception quality continues for a certain period of time (for example, a time corresponding to a unit of coding of an error correction code or a unit of interleaving), it cannot be remedied by error correction. Therefore, when the reception quality is good for a certain period of time and the communication channel capacity is above the average, communication is performed at a high bit rate by controlling the bit rate. Conversely, when the reception quality is bad and the communication channel capacity is below the average, It is preferable to perform communication at a low bit rate.
[0024]
Also, by making the average time of Ave (Nr (t)) and Ave (g (t)) used for the calculation of P_const substantially coincide with the unit for performing channel coding, explicit bit rate control is not performed. Can improve the average bit rate, which is suitable for a system requiring a constant bit rate.
[0025]
Hereinafter, a system and a device configuration for implementing the above algorithm will be described.
[0026]
FIG. 30 shows the system configuration of the present invention. A plurality of mobile stations 3, 4, and 5 communicate with the base stations 1 and 2 via radio, and the base stations 1 and 2 communicate with each other under the control of the base station control station 6 or connect to the fixed network. Establish communication with the communication device to which it belongs.
[0027]
FIG. 11 shows the configuration of the transmitting wireless communication device of the present invention, and FIG. 13 shows the configuration of the receiving wireless communication device of the present invention. Here, the wireless communication device whose transmission power is controlled by the transmission power control of the present invention is defined as a transmitting wireless communication device, and the other wireless communication device is defined as a receiving wireless communication device. In the system configuration shown in FIG. 30, which of the mobile station and the base station may be either wireless communication device, if the base station is the transmitting wireless communication device, the transmission power control of the downlink signal is performed. On the other hand, if the mobile station is used as the transmitting wireless communication device, the transmission power of the uplink signal is controlled.
[0028]
In FIG. 11, the signal received from the antenna is converted by the radio frequency circuit 101 into a baseband signal. The baseband signal is subjected to demodulation processing such as detection by the demodulator 102 and error correction by the communication path decoder 121. On the other hand, the signal of the baseband is input to the power signal generation unit 105, and generates a transmission power control signal according to the power control algorithm. The transmission power control signal is transmitted to the third pilot signal generated by the third pilot signal generation unit 130, the data signal that has been channel-coded by the error correction encoder 106 and the interleaver 107, and the multiplexer 109. Multiplexed. The multiplexed signal has a format as shown in FIG. 14, for example. 303 is a data signal, 304 is a power control signal, and 305 is a third pilot signal. In the figure, the horizontal direction represents time, the vertical direction represents codes used for code division, and multiplexing such as time multiplexing and code division multiplexing. Multiplexed in a way. The multiplexed signal is modulated by the modulator 110 and transmitted to the radio propagation path via the radio frequency circuit 101.
[0029]
The signal transmitted from the receiving wireless communication device is received by the transmitting wireless communication device shown in FIG. The operations of 101, 102, 103, and 104 are the same as those of the receiving wireless communication device. The transmission power control unit 111 extracts the power control signal 304 and calculates the transmission power according to the extracted transmission power control signal 304. On the other hand, the transmission data encoded by the channel encoder 122 is multiplexed by the multiplexer 112 with the second pilot signal generated by the second pilot signal generation means 108 and input to the transmission power variable means 113. . Transmission power varying means 113 varies the signal amplitude so that the transmission power specified by transmission power control section 111 is obtained. The output of the transmission power varying means 113 is multiplexed by the multiplexer 115 with the first pilot signal set to a predetermined power by the first pilot signal generation means 114, and a signal having a format as shown in FIG. It becomes. In FIG. 12, 301 is a first pilot signal, 302 is a second pilot signal, and 303 is a data signal.
[0030]
As shown in FIG. 12, various multiplexing formats are possible. Further, the first pilot signal 301 (P0) is transmitted at a predetermined power without being subjected to power control by the transmission power control unit 111. On the other hand, the second pilot signal 302 is transmitted under the power control together with the data signal 303. The signal multiplexed in the format shown in FIG. 12 is modulated by the modulator 110 and transmitted to the radio propagation path via the radio frequency circuit 101.
[0031]
The transmission power signal generation unit 105 in the reception-side wireless communication device and the transmission power generation unit 111 in the transmission-side wireless communication device are configured, for example, as shown in FIGS. 15 and 16, respectively. The transmission power signal generation unit in FIG. 15 separates a first pilot signal and a second pilot signal with a first pilot signal separation unit 201 and a second pilot signal separation unit 205, respectively.
S (t) = P_const Nr (t) / g (t)
At
P_const = C0 Ave (Nr (t)) / Ave (g (t))
The comparator 211 determines whether the current transmission power is high or low with respect to the transmission power to be transmitted. Generate. Therefore, the transmission power control unit in FIG. 16 extracts the transmission power control signal 304 and increases or decreases the current transmission power according to the transmission power control signal. Although the noise power is obtained from the second pilot signal in FIG. 15, it can be obtained from the first pilot signal (dotted line).
FIG. 31 shows a configuration example of the error correction encoder 106. FIG. 31 illustrates turbo code encoding, in which input transmission data is encoded according to data rate information, and an encoding result is output. The input transmission data is convolutionally coded by a recursive convolutional encoder E1 (231) to become a signal Y1. Further, the transmission data is rearranged by the interleaver 230 and then convolutionally coded by another recursive convolutional encoder E2 (232) to become a signal Y2. Then, the original transmission data X (or U), Y1, and Y2 are combined into one signal by the parallel-serial (P / S) converter 233, and the encoding result is output.
FIG. 32 shows a configuration example of the error correction decoder 104. FIG. 32 shows an error correction decoder corresponding to the signal encoded by the turbo encoder shown in FIG. 31. The error correction decoder performs error correction decoding by iterative decoding according to the information of the received signal and the data rate, and outputs a decoding result U ″. . The input received signal is separated by the serial-parallel (S / P) converter 234 into U ′, Y1 ′, and Y2 ′ by the reverse operation of the parallel-serial (P / S) converter 233. . The soft decision decoder D1 (235) performs a soft decision decoding process corresponding to the recursive convolutional encoder E1 (231) using the separated U ′ and Y1 ′. The decoding result of the soft decision decoder D1 (235) is input to the soft decision decoder D2 (238) via the interleaver 237. On the other hand, the output U ′ of the serial-parallel (S / P) converter 234 is rearranged in an interleaver 236 and input to the soft decision decoder D2 (238). Here, interleavers 236 and 237 follow the same order permutation rule as interleaver 230 in FIG. The soft decision decoder D2 (238) performs soft decision decoding using the output Y2 ′ of the serial-parallel (S / P) converter 234, the output of the interleaver 236, and the output of the interleaver 237, and Output. The decoding result of the soft decision decoder D2 (238) is input to the deinterleaver 239, and the order of the data is changed. The deinterleaver 239 works to reverse the order of the data by the reverse operation of the interleaver 230, 236, 237. The output of the deinterleaver 239 is input to the soft decision decoder D1 (235), and the decoding process is performed again. As described above, the decoding accuracy is improved by repeatedly and alternately passing through the soft decision decoders D1 (235) and D2 (238). After performing decoding a sufficient number of times, the decoding result of one of the soft decision decoders D1 (235) and D2 (238) is output as the final decoding result. FIGS. 31 and 32 show examples using a turbo code. As described above, an error correction encoder corresponding to an error correction code such as an LDPC code or a product code capable of exhibiting a high error correction capability by iterative decoding processing, An error correction decoder may be used. In the above embodiment, when the channel capacity is equal to or more than the average over a certain period of time as described above, the bit rate is controlled to perform communication at a high bit rate, and when the channel capacity is equal to or less than the average, It is preferable to perform communication at a low bit rate. For this purpose, a channel encoder and a channel decoder as shown in FIGS. 17 and 18, respectively, are used instead of the channel encoder 122 in FIG. 13 and the channel decoder 121 in FIG. Just fine. The channel encoder illustrated in FIG. 17 includes an error correction encoder 106 that performs encoding at a data rate specified by a data rate instruction, and data rate information that is information on the data rate specified by the data rate instruction. A rate information generator 123 that generates and outputs the information, an interleaver 107 that interleaves the output of the error correction encoder 106, an output of the interleaver 107, and an output of the rate information generator 123 are multiplexed. A multiplexing unit 124. Also, the channel decoder shown in FIG. 18 includes a rate information separation unit 125 for separating data rate information from a received signal, a deinterleave unit 103 for deinterleaving the remaining data from which the data rate information is separated, An error correction decoder 104 for decoding the output of the deinterleave unit based on the separated data rate information.
[0032]
The transmission power control section 105 can also be configured as shown in FIG. In the figure, a function calculation unit 214 calculates a function f (x) whose output increases with an increase in the input signal. Thus, when the channel gain increases from the average value, a transmission power control signal instructing an increase in transmission power is generated. When it can be assumed that the noise power is constant regardless of time, the simplification can be made as shown in FIG.
[0033]
Further, as shown in FIG. 21, even when the second pilot signal 302 is not included in the signal transmitted by the transmitting-side wireless communication device, for example, the standardized transmission power S (t) / P0 is obtained, and this is used as a transmission power control signal, and S (t) can be obtained by the transmission power control unit shown in FIG. More simply, the configuration shown in FIG. 24 can be used instead of FIG. 22, and the configuration shown in FIG. 25 can be used instead of FIG.
[0034]
Further, as shown in FIG. 26, even when the first pilot signal 301 is not included in the signal transmitted by the transmitting-side wireless communication device, for example, the transmission power control signal generation unit shown in FIG. 27 and the transmission power control signal generation unit shown in FIG. S (t) can be obtained by the transmission power control unit. More simply, the configuration of FIG. 28 can be used instead of FIG. 27, and the configuration of FIG. 29 can be used instead of FIG.
[0035]
As described above, according to the above-described embodiment of the present invention, a transmission power control method for achieving a desired reception quality while preventing an increase in average transmission power even when a relatively short-period channel gain fluctuation occurs. Can be provided,
Also, even when a relatively short-period channel gain variation occurs, the channel capacity can be kept large.
[0036]
【The invention's effect】
According to the present invention, required transmission power is reduced and mutual interference is reduced. Further, according to the present invention, the communication channel capacity increases, and the communicable bit rate can be improved.
[Brief description of the drawings]
FIG. 1 is a diagram for describing a first example of a time variation of a channel gain.
FIG. 2 is a diagram illustrating an example of a temporal change in noise power.
FIG. 3 is a diagram for explaining an example of a temporal change in equivalent noise power at a transmitting end.
FIG. 4 is a diagram illustrating a first example of transmission power control according to the present invention.
FIG. 5 is a diagram showing a change over time in received power when the transmission power control shown in FIG. 4 is applied.
FIG. 6 is a diagram for explaining an example of transmission power control according to the related art.
FIG. 7 is a diagram showing a change over time of received power when the transmission power control shown in FIG. 6 is applied.
FIG. 8 is a comparison of transmission power between transmission power control according to the present invention and transmission power control according to the prior art.
FIG. 9 is a diagram for explaining a second example of the propagation path gain variation.
FIG. 10 is a diagram for explaining a second example of transmission power control according to the present invention.
FIG. 11 is a diagram showing a configuration example of a receiving-side wireless communication device according to the present invention.
FIG. 12 is a diagram for explaining a first example of a transmission signal multiplexing format of a transmission-side wireless communication device according to the present invention.
FIG. 13 is a diagram illustrating a configuration example of a transmission-side wireless communication device according to the present invention.
FIG. 14 is a diagram illustrating an example of a transmission signal multiplexing format of the receiving-side wireless communication device according to the present invention.
FIG. 15 is a diagram illustrating a first configuration example of a transmission power control signal generation unit according to the present invention.
FIG. 16 is a diagram illustrating a first configuration example of a transmission power control unit according to the present invention.
FIG. 17 is a diagram illustrating a configuration example of an encoder with a data rate control function according to the present invention.
FIG. 18 is a diagram showing a configuration example of a decoder with a data rate control function according to the present invention.
FIG. 19 is a diagram illustrating a second configuration example of the transmission power control signal generation unit according to the present invention.
FIG. 20 is a diagram illustrating a third configuration example of the transmission power control signal generation unit according to the present invention.
FIG. 21 is a diagram illustrating a second example of the transmission signal multiplexing format of the transmission-side wireless communication device according to the present invention.
FIG. 22 is a diagram illustrating a fourth configuration example of the transmission power control signal generation unit according to the present invention.
FIG. 23 is a diagram illustrating a second configuration example of the transmission power control unit according to the present invention.
FIG. 24 is a diagram illustrating a fifth configuration example of the transmission power control signal generation unit according to the present invention.
FIG. 25 is a diagram illustrating a third configuration example of the transmission power control unit according to the present invention.
FIG. 26 is a diagram illustrating a third example of the transmission signal multiplexing format of the transmission-side wireless communication device according to the present invention.
FIG. 27 is a diagram illustrating a sixth configuration example of the transmission power control signal generation unit according to the present invention.
FIG. 28 is a diagram illustrating a seventh configuration example of the transmission power control signal generation unit according to the present invention.
FIG. 29 is a diagram illustrating a fourth configuration example of the transmission power control unit according to the present invention.
FIG. 30 is a diagram illustrating a configuration example of a communication system according to the present invention.
FIG. 31 is a diagram illustrating a configuration example of an error correction encoder of a transmission-side wireless device according to the present invention.
FIG. 32 is a diagram illustrating a configuration example of an error correction decoder of a reception-side wireless device according to the present invention.
[Explanation of symbols]
1, 2 base stations
3,4,5 mobile station
6 base station control stations
7 Fixed net
101 Radio frequency circuit
102 demodulator
103 Deinterleaver
104 error correction decoder
121 channel decoder
105 transmission power control signal generator
106 error correction encoder
107 Interleaver
109, 112, 115, 124 signal multiplexer
110 modulator
111 transmission power control unit
122 channel encoder
108 second pilot signal generator
113 Transmission power variable means
114 first pilot signal generator
130 third pilot signal generator
301 first pilot signal
302 Second pilot signal
303 data signal
304 power control signal
305 Third pilot signal
201 first pilot signal separating means
202, 210 signal power measuring means
203, 207, 223 Signal averaging means
204, 212, 216, 217, 228 Divider
205 Second pilot signal separating means
206 noise power measuring means
208, 213, 215, 218, 222, 224, 226 Multiplier
209, 219, 225 Adder
211 means of comparison
220 Power control signal separation means
221 Transmission power calculation means
123 Data Rate Information Generation Means
125 Data rate information separating means
214 Function operation means
227 Signal delay means
230, 236 interleaver
231 and 232 recursive convolutional encoder
233 parallel-serial (P / S) converter
234 Serial-parallel (S / P) converter
235,238 Soft Decision Decoder
239 Deinterleaver.

Claims (10)

A communication method of a wireless communication device,
The transmission-side wireless communication device performs error correction encoding of transmission data and transmits the data,
When the channel gain between the wireless communication devices is increased, the transmission power of the transmitting wireless communication device is increased,
Reduce the transmission power when the channel gain is reduced,
A wireless communication method for correcting a reception error by applying iterative decoding to a received signal in a receiving wireless communication device. The wireless communication method according to claim 1, wherein
From the receiving side wireless communication device, when the propagation path gain is increased, control information for instructing an increase in transmission power is received, and when the propagation path gain is decreased, control information for instructing a decrease in transmission power is received. Receive information. The wireless communication method according to claim 1 or 2,
Set the data rate high when the propagation path gain is large,
When the channel gain is reduced, the data rate is set low. A wireless communication method of a wireless communication device,
When the propagation path gain measured by the receiving wireless communication device becomes larger than a predetermined value, receiving control information instructing an increase in transmission power,
The transmission power is increased based on the control information. A wireless communication method in a wireless communication system having a first wireless communication device and a second wireless communication device,
In the first wireless communication device, a propagation path gain is measured,
Transmitting control information generated based on the propagation path gain from the first wireless communication device to the second wireless communication device,
In transmitting the transmission data subjected to the error correction coding for which iterative decoding is effective in the second wireless communication device, based on the control information, when the propagation path gain is increased, the transmission power is increased. When the channel gain is reduced, the transmission power is reduced. The wireless communication method according to claim 5, wherein
In the second wireless communication device, the data rate is set high when the channel gain is increased, and the data rate is set low when the channel gain is reduced. A wireless communication system,
A first wireless communication device;
Having a second wireless communication device,
The first wireless communication device includes:
Means for measuring the channel gain;
A transmission power information generation unit that generates transmission power control information using the measured channel gain,
Means for transmitting the transmission power control information,
Means for performing error correction decoding by iterative decoding,
The second wireless communication device includes:
Means for performing error correction encoding;
A transmission power control unit that controls transmission power based on the transmission power information received from the first wireless communication device,
The transmission power control unit increases transmission power when the channel gain increases, and decreases transmission power when the channel gain decreases. The wireless communication system according to claim 7, wherein
The second wireless communication device has an encoder that sets a high data rate when the channel gain increases and sets a low data rate when the channel gain decreases. The wireless communication system according to claim 8, wherein:
The second wireless communication device has a multiplexing unit that multiplexes information on a data rate set by the encoder with transmission data and transmits the multiplexed transmission data,
A first demultiplexing unit that demultiplexes information on the data rate multiplexed on received data;
A decoder for decoding received data based on the information on the separated data rate. A wireless communication device,
Means for determining the channel gain by measuring the received power of the signal received from another wireless communication device,
When the propagation path gain is greater than a predetermined value, a means for transmitting control information instructing an increase in transmission power to the other wireless communication device,
It has means for performing error correction decoding by iterative decoding.

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