JP4192925B2 - Wireless communication system and transmission power control method thereof - Google Patents

Description

  The present invention relates to a transmission power distribution method and a reception method in a radio station of a radio communication system. It is particularly suitable for communication systems, transmission stations, and reception stations that use error correction codes.

  In order to obtain desired reception quality in a wireless communication system, a technique for performing transmission power control of a wireless communication device is known. For example, in USP5,267,262, Qualcomm Inc., “Transmitter Power Control System”, in a CDMA mobile communication system, the signal reception power from the terminal is measured at the base station, and if it is smaller than the desired value, an instruction to increase the transmission power is given. In this case, the transmission power reduction instruction is transmitted to the mobile station when the transmission power is large, and the mobile station controls the transmission power according to the transmission power control instruction, thereby indicating a technique for maintaining the reception power at the base station substantially constant. Yes.

  Also, according to USP5,559,790, Hitachi Ltd., “Spread Spectrum Communication System and Transmission Power Control Method therefor”, the mobile station measures the reception quality of the pilot signal transmitted by the base station with known power, and based on the measurement result When the reception quality is poor, a transmission power control signal that requires a larger transmission power than when the reception quality is good is transmitted to the base station, and the base station transmits a signal to the mobile station based on the transmission power control signal. A technique is shown in which the transmission power is controlled to keep the signal reception quality from the base station in the mobile station substantially constant.

According to these technologies, the reception quality at the receiving station is controlled to be constant, so that the reception quality is constant, and the reception quality deteriorates due to gain fluctuations in the propagation path and the transmission power in the system is unnecessarily excessive. Interference can be prevented.
However, in order to make the reception quality constant, it is necessary to transmit with a large transmission power in accordance with a temporary decrease in propagation path gain, and this temporarily large transmission power interferes with other communications.
In Japanese Patent Laid-Open No. 10-215219, Hitachi, Ltd., “Mobile Communication System Transmission Power Control Method and Apparatus for Executing the Same”, transmission is performed when the transmission power exceeds a predetermined reference value as a result of control for keeping reception quality constant. Techniques have been shown in which large transmission power does not interfere with other communications by temporarily stopping.

JP-A-10-215219

  In order to increase the number of possible communications at the same time, it is necessary to reduce the transmission power as much as possible so that each communication minimizes the interference with other communications.

  However, since the conventional technology has aimed to stabilize the communication by making the reception quality constant when performing communication, it is necessary to increase the transmission power when the channel quality is poor. There was a limit to the reduction.

  An object of the present invention is to reduce the total amount of power used for transmission in communication using a propagation path whose quality varies, thereby reducing interference to other communications and increasing the communication capacity of the entire system.

  By using the error correction capability of the channel code, the reception quality does not need to be constant within the range of the error correction capability of the channel code, but rather it is the same with less transmission power if the poor quality section is not used It is possible to obtain the reception quality after decoding.

  In the wireless communication system according to the present invention, the above-described error correction code capability is used, and the transmitting station determines the quality of the transmission channel when transmitting the data subjected to channel coding, and the determined quality is constant. If it is above, transmission is performed, and if the quality is below a certain level, the transmission is suppressed without performing transmission to the radio section. When the quality is recovered, transmission data after the portion where transmission is suppressed is transmitted to the receiving station. Prevents transmission of signals that cannot be used effectively, reduces average transmission power, and reduces interference with other communications.

  Further, in the wireless communication system according to the present invention, when assigning codewords created by channel coding, even for a section where the quality of the propagation path is below a certain level and transmission to the radio section is suppressed at the transmitting station. By assigning codewords in the same way as for transmission intervals and restoring at the time of decoding channel codes at the receiving station, the receiving station can transmit without needing to know in which interval transmission to the wireless interval is suppressed It is possible to restore the entire data.

  For example, in an environment where the quality of a transmission channel to be transmitted can be estimated from the quality of a received signal, such as when a TDD (Time Division Duplex) method in which transmission / reception is duplexed by time division of the same band is applied, a receiving station The transmission station transmits a signal whose transmission power is known to the transmission station, and the transmission station determines the propagation path quality from the reception quality of this signal, and determines whether to execute or suppress the transmission to the radio section. Is applicable.

  In addition, when the quality of the channel to be transmitted is not estimated from the quality of the received signal as in the case of applying the FDD (Frequency Division Duplex) method in which duplexing is performed using different bands for transmission and reception, from the transmitting station, A signal whose power is known is transmitted to the receiving station, and the receiving station determines the channel quality based on the reception quality of this signal, transmits quality information to the transmitting station, and this quality information is transmitted to the transmitting station. The present invention can be applied by determining whether to execute or inhibit transmission to a wireless section based on the above.

  According to the present invention, by not assigning transmission power to a low-quality propagation path, it is possible to reduce required transmission power on average and reduce mutual interference between communications.

  The control method of the present invention, the configuration of the radio station, and the operation of each unit will be described based on the drawings. In the following description, a station that transmits a data signal by applying the present invention is referred to as a transmitting station, and a station that receives the data signal is referred to as a receiving station, and is used for data signal communication from the transmitting station to the receiving station. A configuration when the invention is applied will be described. However, the present invention may be applied to communication of data signals in both directions from the transmitting station to the receiving station and from the receiving station to the transmitting station.

  First, an example of transmission power control when the present invention is implemented will be described with reference to FIG. In wireless communication, the propagation gain between the transmitting station and the receiving station varies as shown by 101 due to the influence of fading or the like. When communication is performed via the propagation path, the communication in the section 111 having a small gain reaches the receiving station after the transmission signal is attenuated significantly compared to the communication in the section 110 and the section 112 having a large gain. Therefore, the contribution to transmission of information per transmission power is reduced.

  On the other hand, even when a plurality of communications are made at the same time, propagation path fluctuations due to fading or the like occur independently for each propagation path in which communications are made. For this reason, the power transmitted to the section where the propagation path gain is small as in section 111 has a small contribution to information transmission, but the interference given to other communications does not necessarily decrease.

  Therefore, control is performed so that the transmission power 103 at the transmission station is set to 0 in the section 111 where the propagation path gain is small, and is set to non-zero in the sections 110 and 112 where the propagation path gain is not small. Transmission of power with a small contribution can be eliminated to reduce transmission power on average, and interference to other communications can be reduced by reducing average transmission power. Also, by performing error correction coding on the communication signal, if the section where the transmission power is 0 is sufficiently smaller than the error correction capability of the error correction code, the transmission power is set to 0 in some sections. The communication speed is not lowered due to the influence, and the effect of the present invention can be sufficiently obtained.

  In order to realize the above control, the channel gain is measured to determine the channel quality, and the transmission power is controlled based on the determination result. For the control method, the transmitting station measures the propagation path gain from the receiving station to the transmitting station and controls the transmission power of the transmitting station, and the receiving station measures the propagation path gain from the transmitting station to the receiving station. There is a method in which the transmission station is notified of the measurement result and the transmission station controls the transmission power based on the notified measurement result.

  The measurement of the propagation path gain used in this control is performed by transmitting a signal having a fixed transmission power to the station on the side of measuring the propagation path gain, and the station on the side of measuring the propagation path gain receiving power and the fixed transmission power. And can be measured. If the station that measures the channel gain does not know the fixed transmission power, it simultaneously notifies the transmission power, and the station that measures the channel gain uses the notified transmission power and received power. The channel gain can be measured by comparison. Furthermore, this control can also use the relative magnitude relationship of the channel gain without using the absolute value of the channel gain. It is also possible to transmit a signal with a fixed ratio and measure the relative magnitude of the channel gain from the ratio of the received power between the signals at the station that measures the channel gain and use it for control. is there.

  In the following, the signal used for the purpose of the propagation path gain measurement is referred to as a pilot signal. However, if the transmission power or the ratio of the transmission power between signals can be estimated, the data signal itself and other control signals are used. It can also be handled as a pilot signal.

  In the following, the flow of the processing and the configuration will be described as a first embodiment with reference to the drawings in the case where the transmitting station measures the channel gain from the received signal and controls the transmission signal in the control of the present invention.

  FIG. 2 is an example of a processing flow in the transmitting station and the receiving station in the first embodiment.

  In process P111, the data receiving station first transmits a signal including a pilot signal for channel quality estimation. The signal including the pilot signal is received by the processing P101 of the data transmission station. Based on the signal received in process P101, the data transmission station determines the quality of the propagation path in process P102, and if the quality is equal to or greater than the threshold based on the determination result, the data transmission power is set to non-zero and is equal to or less than the threshold. For example, the data transmission power is set to 0, and data is transmitted in process P103.

  Here, each process performed in the transmitting station and the receiving station does not have to be a process in which the start and end are completed in order as in the flowchart of FIG. 2, and each continuously operating process transmits a message to each other. A series of processing may be realized.

  As an example, the flow of processing in the transmitting station when processing is performed continuously will be described based on the sequence diagram of FIG. In the processing at the transmitting station in FIG. 3, the signal transmission processing S101 is continuously performed while the signal is transmitted from the transmitting station to the receiving station, and the received signal demodulation processing S103 is continuously performed while the signal is transmitted from the receiving station to the transmitting station. Continue processing. In the reception signal demodulation process, when a pilot signal sufficient for determining the propagation path quality is received, a reception pilot notification message S110 notifying that the pilot signal has been received is notified to the propagation path quality determination process P102. The propagation path quality judgment process starts upon receiving the reception pilot notification message, and when the propagation path quality is judged, a transmission power setting message S111 for notifying the transmission power used for signal transmission is notified to the signal transmission process. To finish the process. The signal transmission processing can be performed with power corresponding to the pilot signal received during the continuous transmission processing by controlling the power of the signal to be transmitted upon receiving the transmission power setting message.

  FIG. 4 shows a configuration example of the transmitting station and FIG. 5 shows a configuration example of the receiving station in the embodiment of the radio station for realizing the control of the first embodiment according to the present invention.

  In the transmitting station of FIG. 4, transmission data is subjected to channel coding and interleaving processing in encoding section 211 and interleaving section 212, and a transmission data signal after encoding is generated and input to transmission signal generating section 210.

  The signal transmission unit 210 multiplexes and modulates the pilot signal and the encoded transmission data signal to create a baseband transmission signal. At this time, the transmission determination unit 215 determines that the propagation path quality determination result is suitable for transmission based on the propagation path quality determination result for each of one or more propagation paths used for transmission of data output from the propagation path quality determination unit 230. The encoded transmission data signal is given a non-zero amplitude for the propagation path, and the amplitude 0 is given for the propagation path whose transmission path quality determination result is inappropriate. Thereby, in the communication using a single propagation path, transmission of data to the radio section is suppressed during the time when the propagation path quality is low. In communication using a plurality of propagation paths, transmission of data to a propagation path having a low propagation path quality is suppressed.

  The baseband transmission signal created by the transmission signal creation unit 210 is given transmission power necessary for reception at the receiving station by the transmission power setting unit 213, converted into a radio frequency signal by the radio unit 200, and transmitted from the antenna. The

In order to sufficiently obtain the effects of the present invention, it is desirable that the quality determination of the propagation path by the propagation path quality determination unit 230 is performed in a cycle shorter than the code length in the encoding unit 211.
Even when the channel quality is low and data transmission to the radio section is suppressed, the channel quality may recover after a section shorter than the code length. In that case, without retransmitting the data signal in the section in which data transmission is suppressed, the transmission of the subsequent data signal is resumed and error correction is performed at the receiving station, so that the transmission is suppressed in the section. It is possible to restore the entire transmission data including the contents of the corresponding data.

  On the other hand, the radio signal received from the antenna in the transmitting station in FIG. 4 is converted into a baseband received signal in the radio unit 200.

  From the baseband received signal, the propagation path estimation unit 223 measures the propagation path gain or noise power, and notifies the propagation path quality determination unit 230 of the propagation path quality. The propagation path quality determination unit 230 determines transmission suitability / transmission unsuitability based on the notified propagation path quality, and notifies the transmission determination unit 215 of the propagation path quality determination result so that the transmission power based on the propagation path quality is Take control.

  In the receiving station of FIG. 5, the received signal is converted into a baseband signal by the radio unit 200. Among the baseband received signals, the data signal is demodulated in the received signal demodulator 220, and a received data signal is created as a result of the demodulating process. The received data signal is deinterleaved by the deinterleaver 222 and the channel code is decoded by the decoder 221 to generate received data. Here, the received signal demodulation unit 220 cannot correctly demodulate the signal given amplitude 0 at the time of transmission, but the error can be corrected by the decoding process in the decoding unit 221, and as a result, communication can be performed correctly. .

  An example of the propagation path quality determination process in the propagation path quality determination unit 230 according to the first embodiment will be described with reference to the block diagram of FIG.

  The block diagram of FIG. 6A is an example of a signal flow in the channel quality determination process when the present invention is applied to the time variation of the channel quality.

  The propagation path gain notified to the propagation path quality determination unit is normalized by noise power, and is notified to the averaging unit 300 and the comparison unit 302 as an instantaneous propagation path gain. Here, in order to sufficiently obtain the effects of the present invention, it is desirable that the interval for notifying the instantaneous channel gain is shorter than the code length of the error correction code used for communication. The averaging unit 300 averages the notified channel gain using a previously reported channel gain and a moving average or LPF (Low Pass Filter). The averaged channel gain is multiplied by a coefficient multiplier 301 by a value determined according to the modulation scheme and coding method used for communication and the channel gain distribution, and is notified to the comparator 302 as a comparison threshold. The comparison unit 302 compares the instantaneous propagation path gain with the comparison threshold value, and if the comparison result shows that the instantaneous propagation path gain is large, the comparison result indicates that the transmission path quality is determined to be suitable. Notify the result of channel quality judgment that is inappropriate for transmission.

  Further, the block diagram of FIG. 6B shows the channel quality when the present invention is applied to the difference in quality between the channels when communication is performed using a plurality of channels at the same time, for example, multi-carrier communication. It is an example of the flow of a signal in determination processing.

  The propagation path gains of the plurality of propagation paths notified to the propagation path quality determination unit are normalized by noise power for each propagation path, and notified to the averaging unit 310 and the comparison unit 312 as instantaneous propagation path gains, respectively. The averaging unit 310 takes the average value of the instantaneous channel gain of each notified channel, and averages the average value temporally by using the average value in the past, the moving average, and the LPF. To obtain the averaged channel gain. The averaged channel gain is multiplied by a coefficient multiplication unit 311 by a value determined according to the modulation scheme and coding method used for communication and the channel gain distribution, and is notified to the comparison unit 312 as a comparison threshold. The comparison unit 312 compares the instantaneous propagation path gain of each propagation path with the comparison threshold value, and if the instantaneous propagation path gain of each propagation path is large as a result of the comparison, the transmission power non-zero is determined as suitable for transmission. If the channel gain is small, a transmission power of 0 is notified as inappropriate transmission.

  Next, in the case where the receiving station controls the transmission signal of the transmitting station by measuring the propagation path gain from the received signal and notifying the transmitting station of the measurement result, the processing flow and configuration as Example 2 are as follows. This will be described with reference to the drawings.

  FIG. 7 shows an example of the processing flow at the transmitting station and the receiving station in the second embodiment.

  In step P201, the transmitting station first transmits a signal including a pilot signal for propagation path quality estimation. The receiving station receives a signal including the pilot signal in the received signal demodulation process P211, creates a quality information signal based on the pilot signal in the propagation path quality determination process P212, and a signal including the quality information in the signal transmission process P213. Send. Based on the quality information received in the received signal demodulation process P202, the transmitting station determines the quality of the propagation path in the quality information determination process P203, and if the quality is equal to or greater than the threshold based on the determination result, the transmission power of the data is non-zero. If it is equal to or less than the threshold, the data transmission power is set to 0, and the data is transmitted in process P204.

  Further, the quality information transmitted in the signal transmission process P213 can be transmitted as a relative relationship such as magnitude or phase difference of power with the pilot signal. In this case, the quality information and the pilot are transmitted in the signal transmission process P213. The transmitting station transmits a signal including the signal, and the transmitting station receives the quality information and the pilot signal in the received signal demodulation process P202. In the quality information determination process P203, the quality of the propagation path is determined from the relative relationship between the quality information and the pilot signal. It is possible.

  Here, each process performed in the transmitting station and the receiving station does not need to be a process in which the start and end are completed in order as in the flowchart of FIG. 7, and the processes that operate continuously communicate messages. A series of processing may be realized.

  FIG. 8 shows a configuration example of the transmitting station and FIG. 9 shows a configuration example of the receiving station in the embodiment of the radio station for realizing the control of the second embodiment according to the present invention.

  8, transmission data is subjected to channel coding and interleaving processing in encoding section 211 and interleaving section 212, and a transmission data signal after encoding is generated and input to transmission signal generating section 210.

  The signal transmission unit 210 multiplexes and modulates the pilot signal and the encoded transmission data signal to create a baseband transmission signal. At this time, in the transmission determination unit 215, based on the quality information determination result for each of one or a plurality of propagation paths used for transmission of data output from the quality information determination unit 231, the quality information determination result is a propagation path suitable for transmission. The encoded transmission data signal is given a non-zero amplitude, and the quality information determination result is given an amplitude of 0 for a transmission path unsuitable for transmission. Thereby, in the communication using a single propagation path, the transmission of data to the wireless section is suppressed for the time when the propagation path quality is determined to be low. In communication using a plurality of propagation paths, transmission of data to the propagation path determined to have a low propagation path quality is suppressed.

  The baseband transmission signal created by the transmission signal creation unit 210 is given transmission power necessary for reception at the receiving station by the transmission power setting unit 213, converted into a radio frequency signal by the radio unit 200, and transmitted from the antenna. The

  On the other hand, the radio signal received from the antenna in the transmitting station of FIG. 8 is converted into a baseband received signal in the radio unit 200. The quality information determination unit 231 is notified of the channel gain or noise power measured by the channel estimation unit 223 and the quality information extracted by the quality information extraction unit 227 from the baseband received signal. The quality information determination unit 231 determines transmission suitability / transmission inappropriateness based on the notified propagation path quality, and notifies the transmission determination unit 215 of the propagation path quality determination result.

  9, the signal transmission unit 210 multiplexes and modulates the pilot signal, the encoded transmission data signal, and the quality information signal created by the quality information creation unit 216 to create a baseband transmission signal. The At this time, the quality information creation unit 216 creates a signal indicating transmission suitability or transmission inappropriateness as quality information based on the propagation path quality determination result output from the propagation path quality determination unit 230.

  The baseband transmission signal created by the transmission signal creation unit 210 is given transmission power necessary for reception at the transmission station by the transmission power setting unit 213, converted into a radio frequency signal by the radio unit 200, and transmitted from the antenna. The

  On the other hand, the radio signal received from the antenna in the radio station in FIG. 9 is converted into a baseband received signal in the radio unit 200. Among the baseband received signals, the data signal is demodulated in the received signal demodulator 220, and a received data signal is created as a result of the demodulating process. The received data signal is deinterleaved by the deinterleaver 222 and the channel code is decoded by the decoder 221 to generate received data. Here, the received signal demodulation unit 220 cannot correctly demodulate the signal given amplitude 0 at the time of transmission, but the error can be corrected by the decoding process in the decoding unit 221, and as a result, communication can be performed correctly. .

  Also, the channel quality determination unit 230 is notified of the channel gain or noise power measured by the channel estimation unit 223 and the quality information extracted by the quality information extraction unit 227 from the baseband received signal. The propagation path quality determination unit 230 determines transmission suitability / transmission inappropriateness based on the notified propagation path quality, and notifies the quality information creation unit 216 of the propagation path quality determination result.

  In the configuration of the second embodiment, the signal and processing flow in the propagation path quality determination unit 230 are the same as those of the propagation path quality determination unit 230 in the configuration of the first embodiment.

  A signal and processing flow in the quality information determination unit 231 in the configuration of the second embodiment will be described with reference to FIG.

  The block diagram of FIG. 10 (a) is an example of a signal flow in the channel quality determination process when the present invention is applied to the channel time variation. The quality information extracted by the quality information extraction unit and the channel gain averaged by the averaging unit 300 are notified to the quality information determination unit 303. The quality information determination unit 303 determines the quality information notified based on the averaged channel gain, and if the quality information is sufficiently good, the quality information determination result is suitable for transmission. The quality information determination result is output.

  The block diagram of FIG. 10 (b) shows the channel quality when the present invention is applied to the quality difference between the channels when communication is performed using a plurality of channels at the same time, for example, multi-carrier communication. It is an example of the flow of a signal in determination processing.

  The quality information of each channel extracted by the quality information extraction unit and the channel gain averaged by the averaging unit 310 are notified to the quality information determination unit 313. The quality information determination unit 313 determines the quality information of each channel that is notified based on the averaged channel gain, and if the quality information is sufficiently good, the quality information determination result that is suitable for transmission is If not, the quality information determination result that is inappropriate for transmission is output. A time average propagation path gain may be obtained by temporally averaging the instantaneous propagation path gain of each propagation path notified to the averaging unit 310.

  In the first embodiment and the second embodiment, it is desirable to use an error correction code having a high error correction capability for the code encoded by the encoding unit 211 and decoded by the decoding unit 221. For example, the Viterbi Algorithm is applied. It is possible to use a convolutional code that can be decoded, a Turbo code that can improve error correction capability by repetitive decoding, and the like.

  When deriving the comparison coefficient in the coefficient multipliers 301 and 311 of the first and second embodiments, for example, depending on the modulation scheme, the lower the modulation multi-value number, the higher the comparison threshold, and the higher the modulation multi-value number, the comparison threshold The comparison threshold value can be appropriately controlled by lowering the threshold value, and for example, by the coding method, the higher the error correction capability of the code, the higher the comparison threshold value, and the lower the error correction capability of the code, the lower the comparison threshold value. Is possible. If the fluctuation of the propagation path gain is large due to the propagation path gain distribution, the communication can be stabilized by lowering the comparison threshold value.

  In addition, when it is necessary to guarantee the minimum communication speed, the comparison threshold is lowered when the ratio of the sections in which the channel quality determination results determined by the comparison units 302 and 312 are determined to be inappropriate for transmission increases. By doing so, it is determined that transmission is unsuitable over a large section, and transmission to the wireless section can be prevented from being suppressed.

  In the first embodiment and the second embodiment, the case where the present control is applied using the channel gain as the channel quality has been described. However, the received power at the station that determines the channel quality instead of the channel gain is It is also possible to use a signal to noise power ratio.

An example of time variation of propagation path gain and control according to the present invention. 2 is an example of a processing flow of a transmitting station and a receiving station in the first embodiment. 4 is a sequence example of a transmitting station in the first embodiment. 2 is a configuration example of a transmission station in the first embodiment. 2 is a configuration example of a receiving station in the first embodiment. 3 is an example of a propagation path quality determination process in the first embodiment. 10 is an example of a processing flow of a transmitting station and a receiving station in the second embodiment. 4 is a configuration example of a transmission station in Embodiment 2. 6 is a configuration example of a receiving station in the second embodiment. 10 is an example of quality information determination processing in the second embodiment.

Explanation of symbols

100 Channel gain threshold
101 Propagation gain fluctuation
103 Transmitted signal power
110, 112 High channel gain section
111 Low channel gain section
200 Radio section
210 Signal transmitter
211 Encoder
212 Interleave section
213 Transmission power setting section
214 Multiplexer / Modulator
215 Transmission judgment unit
216 Quality Information Creation Department
220 Received signal demodulator
221 Decryption unit
222 Deinterleaving section
223 Propagation path estimation unit
224 Detector / Demodulator
225 Pilot extractor
226 Data extraction unit
227 Quality information extraction unit
230 Channel quality judgment unit
231 Quality information judgment unit
300, 310 Averaging part
301, 311 Count remainder
302, 312 comparator
303, 313 Quality information judgment unit
P101, P201 Received signal demodulation (pilot) processing
P102, P212 Channel quality judgment (pilot) processing
P103, P204 Signal transmission (data) processing
P111, P211 Signal transmission (pilot) processing
P112, P214 Received signal demodulation (data) processing
P213 Signal transmission (pilot / quality information) processing
P202 Received signal demodulation (pilot / quality information) processing
P203 Quality information judgment (pilot / quality information) processing.

Claims (6)

A transmitting station in a wireless communication system that performs data transmission from a transmitting station to a receiving station,
An encoding unit for encoding a data signal;
A transmission determination unit that determines at a predetermined frequency whether or not to transmit the encoded data signal based on channel quality between the transmission station and the reception station;
When the transmission determination unit determines to transmit the encoded data signal, the transmission power of the encoded data signal is set to non-zero for at least a predetermined period,
A transmission station characterized by setting the transmission power of the encoded data signal to 0 for a predetermined period when the transmission determination unit determines not to transmit the encoded data signal. A transmitting station in a wireless communication system that performs data transmission from a transmitting station to a receiving station,
An encoding unit for encoding a data signal;
A transmission determination unit that determines at a predetermined frequency whether or not to transmit the encoded data signal based on channel quality between the transmission station and the reception station;
If the transmission determination unit determines to transmit the encoded data signal, the encoded data signal is given a non-zero amplitude for at least a predetermined period,
A transmission station characterized in that, when the transmission determination unit determines that the encoded data signal is not transmitted, an amplitude of 0 is given to the encoded data signal for a predetermined period. The transmitting station according to claim 1 or 2, wherein
A propagation path quality determination unit,
The transmission station characterized in that the propagation path quality determination unit determines the propagation path quality based on a state of a propagation path from the reception station to the transmission station. 3. The transmitting station according to claim 1, wherein the predetermined period is shorter than a period corresponding to a code length of the data signal, and the transmission power or the signal amplitude is determined to be non-zero by the determination after the predetermined period. A transmitting station characterized in that, when set, a data signal can be restored by a decoding process of the receiving station. A data transmission method to a receiving station in a transmitting station that performs wireless communication with the receiving station,
Encode the data signal to be transmitted,
Determine whether to transmit the encoded data signal based on the propagation path quality between the transmitting station and the receiving station,
If it is determined to transmit the encoded data signal, the encoded data signal is transmitted with a non-zero transmission power for at least a predetermined period of time,
A data transmission method characterized in that if it is determined not to transmit the encoded data signal, a transmission power of 0 is set in the encoded data signal for a predetermined period. A data transmission method to a receiving station in a transmitting station that performs wireless communication with the receiving station,
Encode the data signal to be transmitted,
Determining whether to transmit the encoded data signal based on the channel quality between the transmitting station and the receiving station at a predetermined frequency;
If it is determined to transmit the encoded data signal, a non-zero amplitude is set in the encoded data signal for at least a predetermined period;
A data transmission method characterized in that, when it is determined not to transmit the encoded data signal, an amplitude of 0 is set in the encoded data signal for a predetermined period.

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