JP2003333008A - Communication system and its method, receiving apparatus and its method, communication apparatus and its method, and program - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a communication system and its method, which can effectively reduce degradation in communication quality accompanying channel state fluctuation in time, and to provide a receiving apparatus and its method, a communication apparatus and its method, and program. <P>SOLUTION: A fluctuation-estimating unit 30 is a unit for estimating the degree of channel state fluctuation in time, and the unit 30 conducts estimation, according to communication apparatus movement state detected by a mobile sensor or fluctuation in temporal change of a channel estimation result at a receiving unit 20. According to the estimation result, a reference signal insertion interval for channel estimation inserted into a transmitted signal column Tx with a constant interval is changed. According to this arrangement, a reference signal insertion interval at a communication destination is changed. <P>COPYRIGHT: (C)2004,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a communication system and its method, a receiving apparatus and its method, a communication apparatus and its method, and a program, for example, a communication system used in a wireless LAN for channel estimation and the like. The present invention relates to a method, a receiving device and its method, a communication device and its method, and a program.

[0002]

2. Description of the Related Art First, a conventional method of estimating a channel (transmission path) state in a wireless LAN will be described. FIG. 19
19A shows a reference signal for channel estimation included in an Ethernet (registered trademark) MAC frame, and FIG.
The structure of this MAC frame is shown. The reference signal for channel estimation is, for example, BPSK (binary phase shift keyin).
It is a signal of a predetermined value that is modulated by a predetermined modulation method such as g). As shown in FIG. 19B, the reference signal for channel estimation is inserted in the preamble portion of the MAC frame, following the preamble signal for frame synchronization.

FIG. 20 shows an OFDM (orthogonal frequency).
A configuration example of a multi-carrier signal modulated by a cy division multiplex) system is shown. In the example of FIG. 20, one OF
The DM symbol is composed of 52 subcarrier signals, and a guard interval for preventing interference between the symbols is provided between the OFDM symbols. Further, a signal having a predetermined value called a pilot subcarrier signal is inserted in a specific subcarrier (four subcarriers in the example of FIG. 20). In the case of the OFDM system, it is necessary to perform channel estimation of each subcarrier signal included in the OFDM symbol, and therefore one or more OFDM symbols are used as one channel estimation reference signal.

FIG. 21A is a signal point arrangement diagram showing a channel estimation reference signal T before transmission and a channel estimation reference signal R after transmission. As shown in FIG. 21A, the phase and amplitude of the reference signal R after transmission change with respect to the reference signal T before transmission, reflecting the state of the transmission channel. Since the reference signal T before transmission is known, the channel state can be estimated on the receiving side from the difference between the known reference signal T and the reference signal R after transmission. In the case of the OFDM method, as shown in FIG. 21B, this channel state estimation is performed for each subcarrier.

The estimated value of the channel state thus estimated is used for equalization of the received signal until the next reference signal for channel estimation is transmitted. For example, in FIG. 19A, since the channel estimation reference signal is transmitted for each MAC frame, at least the same MA is used.
The same channel estimation result is used in the C frame.

[0006]

By the way, in recent years, electronic devices, such as mobile phones and portable information terminals, which perform wireless communication while moving outdoors have been rapidly spreading in recent years. For example, wireless LAN access points. Is provided in a specific area such as a train station or a downtown area, and a service is provided that allows a portable information terminal to connect to the Internet or the like via this access point. Since the wireless LAN has a higher transmission rate than the communication method of a mobile phone, if these access points can be used while walking or moving in a car, for example, a more comfortable communication environment will be provided to the user. can do.

However, the conventional wireless LAN standards such as IEEE802.11a and HIPERLAN / 2 are designed on the assumption that the communication device is stationary indoors, and the low Doppler frequency of about 17 Hz, for example. Is taken into consideration. Therefore, for example, when moving by car or when there are moving objects around,
When the channel state changes faster than in a stationary indoor environment, the process for estimating the channel state and equalizing the received signal cannot keep up with this. That is, if the channel state changes faster than the time interval at which the channel estimation is performed, the received signal is equalized using an inappropriate channel estimation result in this changed state. As a result, there is a problem that the data error rate increases and the communication quality deteriorates significantly.

In wideband wireless communication using the OFDM system, adaptive subcarrier modulation (adaptive modulation) for setting an optimum modulation system for each subcarrier according to the result of channel estimation is a powerful method for improving communication quality. subca
A method called rrier loading) is known. However, in order to set the modulation method for each subcarrier, it is necessary for the transmitter and receiver to negotiate this in advance.Therefore, there is a slight time lag between the channel estimation and the setting of the optimum modulation method. Will occur.
If the fluctuation period of the channel state becomes short with respect to this time difference, the adaptive subcarrier modulation cannot follow this fluctuation, which causes a problem that communication quality is deteriorated.

The present invention has been made in view of the above circumstances, and an object thereof is to provide a communication system and a method therefor capable of effectively reducing the deterioration of the communication quality due to the temporal variation of the channel state. An apparatus and its method, a communication apparatus and its method, and a program.

[0010]

In order to achieve the above object, a communication system according to a first aspect of the present invention is a communication system having a first communication device and a second communication device, The first communication device and the second communication device transmit the signal sequence in which a predetermined reference signal is inserted at constant intervals, and extract the reference signal from the received signal sequence, Transmission path estimation means for estimating the transmission path state according to the difference between the extracted reference signal and the predetermined reference signal, and equalization means for equalizing the received signal sequence according to the estimation result of the transmission path estimation means. The first communication device, the first communication device includes a fluctuation estimating unit that estimates a degree of temporal fluctuation of the transmission path state, and information that corresponds to an estimation result of the fluctuation estimating unit. Means for notifying the second communication device of Further comprising: first setting means for setting an insertion interval of the reference signal in the transmitting means in accordance with an estimation result of the fluctuation estimating means, wherein the second communication device is the same as the first communication device. It further includes second setting means for setting the insertion interval of the reference signal in the transmitting means according to the notified information.

According to the communication system of the first aspect of the present invention, a signal sequence in which a predetermined reference signal is inserted at regular intervals between the first communication device and the second communication device. Is transmitted. In the communication device on the receiving side, the reference signal is extracted from the received signal sequence, and the transmission line state is estimated according to the difference between the extracted reference signal and the predetermined reference signal. Then, the received signal sequence is equalized according to the estimation result. Further, the fluctuation estimating means of the first communication device estimates the temporal fluctuation degree of the transmission path state, and notifies the second communication device of information according to the estimation result. In the first communication device, the insertion interval of the reference signal with respect to the transmission signal sequence is set according to the estimation result of the fluctuation estimating means. In the second communication device, the insertion interval of the reference signal with respect to the transmission signal sequence is set according to the information notified from the first communication device.

The fluctuation estimating means may estimate the temporal fluctuation degree of the transmission path state according to the degree of temporal fluctuation of the estimation result of the transmission path estimating means.
Alternatively, the temporal variation of the transmission path state may be estimated according to the result of detecting the moving state of the communication device of its own.

In a communication method according to a second aspect of the present invention, a signal sequence in which a predetermined reference signal is inserted at a constant interval is transmitted between communication devices that communicate with each other, and the signal sequence after the transmission is transmitted. Is a communication method for equalizing the signal sequence after transmission according to the difference between the extracted reference signal and the predetermined reference signal, wherein the transmission path state is temporal. The degree of fluctuation is estimated, and the reference signal is inserted into the transmission signal sequence at intervals according to the estimation result.

A receiving device according to a third aspect of the present invention is a receiving device for receiving a signal sequence in which a predetermined reference signal is inserted at regular intervals, and extracting the reference signal from the received signal sequence, A transmission line estimating means for estimating a transmission line state according to a difference between the extracted reference signal and the predetermined reference signal,
Fluctuation estimation means for estimating the degree of temporal fluctuation of the transmission path state, and averaging means for averaging the estimation results of the transmission path estimation means with a transfer function according to the estimation result of the fluctuation estimation means; And equalizing means for equalizing the received signal sequence according to the estimation result averaged by the averaging means.

According to the communication apparatus of the third aspect of the present invention, in the transmission path estimating means, the reference signal is extracted from the received signal sequence in which the predetermined reference signal is inserted at a constant interval, The transmission path state is estimated according to the difference between the extracted reference signal and the predetermined reference signal. Further, the fluctuation estimating means estimates the degree of temporal fluctuation of the transmission path state. The estimation result of the transmission path estimation means is averaged by the averaging means with a transfer function according to the estimation result of the fluctuation estimation means, and received by the equalization means according to the averaged estimation result. The signal train is equalized.

In the receiving method according to the fourth aspect of the present invention, the reference signal is extracted from a received signal sequence in which a predetermined reference signal is inserted at regular intervals, and the extracted reference signal and the predetermined reference signal are extracted. A receiving method for estimating a transmission line state according to a difference with a signal and equalizing a received signal sequence according to an estimation result of the transmission line state, and estimating a degree of temporal change of the transmission line state. Then, the transfer path state estimation results are averaged using the transfer function corresponding to the estimation result, and the received signal sequence is equalized according to the averaged estimation result.

The receiving apparatus according to the fifth aspect of the present invention is
A predetermined reference signal is inserted at regular intervals in a signal train of a multicarrier modulation signal generated by multiplexing a subcarrier signal in which a 1-bit signal or a multi-bit signal forming a symbol signal is modulated with a plurality of subcarriers. A receiving device for receiving the received signal sequence, demodulating the received signal sequence, and outputting a signal sequence of a symbol signal including a plurality of subcarrier signals; A reference signal is extracted, and a plurality of subcarrier signals included in the extracted reference signal, and a transmission path in the plurality of subcarriers according to a difference between the corresponding reference subcarrier signals of the plurality of subcarrier signals. A channel estimation means for estimating a state and equalizing each subcarrier signal of the symbol signal according to the estimation result of the channel estimation means. Equalizing means, a fluctuation estimating means for estimating the degree of temporal fluctuation of the transmission line state, and a case where the temporal fluctuation degree estimated by the fluctuation estimating means reaches a predetermined threshold value. Correct the estimation result of the transmission path estimation means supplied to the equalization means according to the difference between the specific subcarrier signal included in the symbol signal and the reference subcarrier signal corresponding to the specific subcarrier signal. Correction means for

According to the receiving apparatus of the fifth aspect of the present invention, the signal train of the received multi-carrier modulated signal is demodulated by the demodulating means and the signal train of the symbol signal including a plurality of sub-carrier signals. Is output. In the transmission path estimation means, the reference signal is extracted from the signal sequence of the symbol signal, a plurality of subcarrier signals included in the extracted reference signal, and a reference subcarrier corresponding to each of the plurality of subcarrier signals The transmission path states in a plurality of subcarriers are estimated according to the difference from the signal. When the temporal fluctuation degree of the transmission path state estimated by the fluctuation estimating means reaches a predetermined threshold value, a specific subcarrier signal included in the symbol signal and a specific subcarrier signal corresponding to the specific subcarrier signal are included. The estimation result of the transmission path estimation means supplied to the equalization means is corrected by the correction means according to the difference from the reference subcarrier signal.

The receiving method according to the sixth aspect of the present invention is
A predetermined reference signal is inserted at regular intervals in a signal train of a multicarrier modulation signal generated by multiplexing a subcarrier signal in which a 1-bit signal or a multi-bit signal forming a symbol signal is modulated with a plurality of subcarriers. Demodulate the received signal sequence generated, to generate a signal sequence of the symbol signal including a plurality of subcarrier signals, extract the reference signal from the signal sequence of the generated symbol signal, the extracted reference signal According to the difference between the plurality of subcarrier signals included in, and the corresponding reference subcarrier signal of each of the plurality of subcarrier signals, the transmission path state in the plurality of subcarriers is estimated, and the estimation result of the transmission path state is obtained. In accordance with the above, it is a receiving method for equalizing each subcarrier signal of the symbol signal, and When the estimated temporal fluctuation reaches a predetermined threshold value, a specific subcarrier signal included in the symbol signal, and a reference subcarrier signal corresponding to the specific subcarrier signal. The correction results of the transmission path states of the plurality of subcarriers are corrected in accordance with the difference between, and the subcarrier signals of the symbol signals are equalized in accordance with the corrected estimation results.

A communication device according to a seventh aspect of the present invention is 1
First modulation means for respectively modulating a 1-bit signal or a plurality of bits constituting a symbol signal by a set modulation method, and a signal modulated by the first modulation means is modulated by a plurality of subcarriers. Second modulation means for multiplexing and outputting a multicarrier modulation signal, and transmission signal sequence forming means for forming a transmission signal sequence in which a predetermined reference signal is inserted at regular intervals in the signal sequence of the multicarrier modulation signal. A first demodulation means for demodulating the received signal sequence and outputting a signal sequence of a symbol signal including a plurality of subcarrier signals; and extracting the reference signal from the signal sequence of the symbol signal, and extracting the reference signal. Depending on the difference between the plurality of subcarrier signals included in the reference signal and the corresponding reference subcarrier signal of each of the plurality of subcarrier signals,
Transmission path estimation means for estimating transmission path states in a plurality of subcarriers, equalization means for equalizing each subcarrier signal of the symbol signal according to the estimation result of the transmission path state, and the equalization means Second demodulation means for demodulating the symbol signal equalized in 1. by a set demodulation method, fluctuation estimation means for estimating the degree of temporal fluctuation of the transmission path state, and estimation results of the fluctuation estimation means. Accordingly, the modulation method in the first modulation means and the demodulation method in the second demodulation means are set to be the same for all subcarriers, or by applying the estimation result of the transmission path estimation means. And transmission method setting means for setting each subcarrier.

According to the communication apparatus of the seventh aspect of the present invention, at the time of transmission, a signal of 1 bit or a plurality of bits forming one symbol signal is transmitted by the first modulation means in a set modulation method. Each is modulated. further,
In the second modulating means, the modulated signal is modulated with a plurality of subcarriers and multiplexed, and output as a multicarrier modulated signal. A predetermined reference signal is inserted into the signal sequence of the multi-carrier modulated signal by the transmission signal sequence forming means at regular intervals to form a transmission signal sequence. At the time of reception, the first demodulation means demodulates the received signal sequence and outputs a symbol signal signal sequence including a plurality of subcarrier signals. Further, in the transmission path estimation means, the reference signal is extracted from the signal sequence of the symbol signal, a plurality of subcarrier signals included in the extracted reference signal, and a reference corresponding to each of the plurality of subcarrier signals. The transmission path states in a plurality of subcarriers are estimated according to the difference from the subcarrier signal. According to the estimation result, each subcarrier signal of the symbol signal is equalized by the equalizing means, and the equalized symbol signal is converted by the second demodulating means by the set demodulation method. Demodulated. The modulation method in the first modulation means and the demodulation method in the second demodulation means are set to be the same for all subcarriers according to the estimation result of the temporal fluctuation degree of the transmission path state by the fluctuation estimating means. Alternatively, it is set for each subcarrier according to the estimation result of the transmission path estimation means.

In a communication method according to an eighth aspect of the present invention, at the time of transmission, a 1-bit signal or a multi-bit signal constituting a 1-symbol signal is modulated by a set modulation method, and the modulated signal is modulated. Are modulated by a plurality of subcarriers and multiplexed, and a predetermined reference signal is inserted at regular intervals into the signal sequence of the multiplexed modulated signal to form a transmission signal sequence, and the received signal is received. Demodulate the sequence,
Generating a signal string of a symbol signal containing a plurality of subcarrier signals, extracting the reference signal from the signal string of the generated symbol signal, a plurality of subcarrier signals included in the extracted reference signal, Depending on the difference between the reference subcarrier signal corresponding to each of the plurality of subcarrier signals, the transmission path state in the plurality of subcarriers is estimated, and in accordance with the estimation result of the transmission path state, A communication method for equalizing a subcarrier signal and demodulating the equalized symbol signal according to a set demodulation method, estimating the degree of temporal change in the transmission path state, and depending on the estimation result. Then, the modulation method and demodulation method of the symbol signal are set to be the same for all subcarriers, or the subkey is applied by adapting to the estimation result of the transmission path state. It is set for each rear.

Further other objects and features of the present invention will become apparent from the more detailed description based on the embodiments of the present invention described later and the accompanying drawings.

[0024]

BEST MODE FOR CARRYING OUT THE INVENTION Four embodiments of the present invention will be described below. <First Embodiment> FIG. 1 is a schematic block diagram showing a configuration example of a communication system according to a first embodiment of the present invention. The communication system shown in FIG. 1 includes, for example, a first communication device 1 as a mobile terminal in a wireless LAN and its access point.
And the second communication device 2 as.

FIG. 2 is a schematic block diagram showing a configuration example of the first communication device 1 in FIG. In the example of FIG. 2, the first communication device 1 includes a transmitter 10, a receiver 20,
The fluctuation estimation unit 30, the notification unit 40, the first setting unit 51, the transmission method setting unit 60, and the antenna duplexer 70 are included.

The transmission section 10 inserts a predetermined reference signal for channel estimation into the transmission signal Tx at intervals set by the first setting section 51, and transmits it from the antenna AT via the antenna duplexer 70. Further, the transmission signal Tx is formed by using the encoding method and the modulation method according to the setting of the transmission method setting unit 60.

For example, when communication is performed with a modulated signal of the OFDM system, the transmission section 10 has a structure as shown in FIG. That is, convolutional encoder 101, interleaver 102, modulator 103, and OFDM modulator 10
6, a transmission signal string formation unit 107, a digital / analog conversion unit, and an RF processing unit 109.

The convolutional encoder 101 uses the transmission data D
Convolutional coding is performed on T with the coding rate set by the transmission method setting unit 60 described later. For example, after performing convolutional coding processing with a predetermined coding rate, signal puncturing (puncturing) is performed according to the coding rate set by the transmission method setting unit 60. The interleaver 102 rearranges each bit of the signal convolutionally coded by the convolutional encoder 101 in a predetermined order, and disperses information in a bit string.

The modulator 103 performs primary modulation on the signals rearranged by the interleaver 102. The primary modulation includes a plurality of predetermined modulation schemes such as BPSK and QPSK (quadrature phase shift keyin).
g), 16QAM (quadrature amplitude modulatio
The modulation method set by the transmission method setting unit 60 is used from among n) and 64QAM.

The OFDM modulator 106 is a unit that performs OFDM modulation as a secondary modulation on the signal that is primary-modulated by the modulator 103. In the example of FIG. 3, the IFFT unit 104 and the guard It has an interval addition unit 105. The IFFT unit 104 sequentially extracts a symbol signal of a predetermined length from the bit string of the first-modulated signal, and uses this as an inverse fast Fourier transform.
er transform). Guard interval addition unit 1
Reference numeral 05 provides a guard interval for preventing these interferences between the signals of the symbol signal subjected to the inverse Fourier transform in the IFFT unit 104. In the guard interval, for example, one end of the inverse Fourier transformed symbol signal is extended by using a part of the data at the other end.

The transmission signal sequence forming section 107 includes a synchronization preamble signal for detecting frame delimiters and a reference signal for channel estimation for the signal sequence of the symbol signal secondarily modulated by the OFDM modulator 106. A preamble including a is inserted to form a transmission signal sequence. Further, the reference signal for channel estimation is inserted into the portion other than the preamble at intervals according to the setting signal S5 from the first setting unit 51.

The digital / analog converter 108 converts the transmission signal sequence formed by the transmission signal sequence formation unit 107 from a digital signal to an analog signal. RF processing unit 1
Reference numeral 09 denotes a transmission signal that is obtained by performing high-frequency signal processing such as filter processing for passing a signal in a predetermined band, frequency conversion processing, and amplification processing on the transmission signal converted into an analog signal by the digital / analog conversion unit 108. Tx is formed and output to the antenna duplexer 70.

The operation of the transmission unit 10 of FIG. 3 having the above-mentioned configuration will be described. The transmission data DT is convolutionally coded in the convolutional encoder 101 with the coding rate set by the transmission method setting unit 60, and the interleaver 1
In 02, they are rearranged in a predetermined order. Next, in the modulator 103, the primary modulation is performed using the modulation method set by the transmission method setting unit 60.

The primary-modulated transmission data is OFDM
The signal is secondarily modulated in the modulator 106 and converted into a symbol signal modulated by the OFDM method. Specifically, the IFFT unit 104 sequentially extracts a symbol signal having a predetermined bit length, and the inverse fast Fourier transform is performed on this. A guard interval is added by the guard interval adding unit 105 between the signals of the symbol signals that have been subjected to the inverse Fourier transform.

In the signal train of the symbol signal secondarily modulated in the OFDM modulator 106, the transmission signal train forming unit 1
In 07, a preamble including a synchronization preamble signal for detecting a frame delimiter and a channel estimation reference signal is inserted, and the first setting unit 5
A reference signal for channel estimation is inserted into a portion other than the preamble at intervals according to the setting signal S5 from 1.

The transmission signal sequence formed by the transmission signal sequence formation unit 107 is converted into an analog signal by the digital / analog conversion unit 108, and then the RF processing unit 109 performs high frequency processing such as filtering, frequency conversion processing, and amplification processing. Signal processing is performed and the signal is output to the antenna duplexer 70 as the transmission signal Tx. The above is the description of the transmission unit 10.

The reception section 20 receives the received signal Rx from the antenna AT via the antenna duplexer 70.
Reception processing is performed using the demodulation method and the decoding method set by the transmission method setting unit 60, and the received data DR is reproduced. In this reception process, a reference signal for channel estimation is extracted from the received signal sequence, the channel state is estimated according to the difference between the extracted reference signal and a predetermined reference signal, and the estimation result A process for equalizing the received signal is performed according to

For example, when communication is performed with a modulated signal of the OFDM system, the receiving section 20 has a structure as shown in FIG. That is, the RF signal processing unit 201, the analog / digital conversion unit 202, the OFDM demodulator 205, the transmission path estimation unit 206, the equalizer 207, the demodulator 208, the
It has an interleaver 209 and a Viterbi decoder 210.

The RF signal processor 201 receives the received signal Rx received from the antenna AT via the antenna duplexer 70.
On the other hand, high-frequency signal processing such as filter processing for passing a signal in a predetermined band, frequency conversion processing, and amplification processing is performed. The analog / digital conversion unit 202 converts the reception signal processed by the RF signal processing unit 201 into a digital signal.

The OFDM demodulator 205 is a unit which demodulates the reception signal digitized by the analog / digital conversion unit 202 and outputs a signal sequence of symbol signals including a plurality of subcarrier signals. In the example,
It has a synchronization unit 203 and an FFT unit 204. Synchronization part 2
03 removes the guard interval part from the received signal by detecting the preamble signal for synchronization from the digitized received signal, and sequentially extracts the symbol signal of a predetermined length. FFT section 204 performs a fast fourier transform on the symbol signal extracted by synchronization section 203, and outputs a plurality of subcarrier signals corresponding to one symbol signal.

The transmission path estimation unit 206 is used for the OFDM demodulator 2
A reference signal for channel estimation is extracted from the signal sequence of the symbol signal output from 05, and the channel state is estimated according to the difference between the extracted reference signal and a predetermined reference signal. That is, the estimated signal S206 corresponding to each subcarrier is generated according to the difference between the plurality of subcarrier signals included in the extracted reference signal and the predetermined reference subcarrier signal corresponding to each of the plurality of subcarrier signals. To generate.

Equalizer 207 equalizes a plurality of subcarrier signals included in the symbol signal output from OFDM demodulator 205, according to the estimation result of channel estimation section 206. For example, by adding the difference between each subcarrier of the reference signal extracted by the transmission path estimation unit 206 and the known reference subcarrier signal to the subcarrier signal output from the OFDM demodulator 205, Perform processing to remove the effect of the state.

The demodulator 208 demodulates each subcarrier signal of the symbol signal equalized by the equalizer 207 using the demodulation method set by the transmission method setting unit 60. This demodulation corresponds to the first-order modulation in the modulator 103 described above.

The de-interleaver 209 is the demodulator 20.
Each bit of the symbol signal sequence demodulated in 8 is rearranged in a predetermined order, and the information distributed by the interleaver 102 is rearranged. Viterbi decoder 210
Performs Viterbi decoding on the signals rearranged by the de-interleaver 209 using the decoding algorithm set by the transmission method setting unit 60, and reproduces the received data DR. For example, according to the coding rate set by the transmission method setting unit 60, depuncturing processing corresponding to the puncturing processing on the transmission side is performed to restore the decimated signal length, and then a predetermined code The received data DR is reproduced by performing the Viterbi decoding process corresponding to the conversion rate.

The operation of the receiving section of FIG. 4 having the above configuration will be described. The received signal Rx received from the antenna AT via the antenna duplexer 70 is the RF signal processing unit 201.
In, the high-frequency signal processing such as the filter processing, the frequency conversion processing, and the amplification processing is performed, and the analog / digital conversion unit 202 converts the signal into a digital signal.

The digitized received signal is demodulated by the OFDM demodulator 205 and converted into a signal string of symbol signals including a plurality of subcarrier signals. Specifically, the synchronization unit 203 detects the preamble signal for synchronization from the digitized reception signal, thereby removing the guard interval portion from the reception signal and sequentially extracting symbol signals of a predetermined length. It And
The FFT unit 204 performs a fast Fourier transform on the extracted symbol signal to generate a plurality of subcarrier signals for each symbol signal.

The symbol signal of the OFDM demodulator 205 is input to the transmission path estimation unit 206, and the reference signal for channel estimation is extracted from this signal sequence. Then, according to the difference between the plurality of subcarrier signals included in the extracted reference signal and the predetermined reference subcarrier signal corresponding to each of the plurality of subcarrier signals, estimation of the channel state corresponding to each subcarrier is performed. The signal S206 is generated.
The symbol signal of the OFDM demodulator 205 is equalizer 2
The plurality of subcarrier signals included in the symbol signal that is input to 07 and is output from the OFDM demodulator 205 are equalized by the estimation signal S206 of the transmission path estimation unit 206.

The symbol signal equalized by the equalizer 207 is demodulated by the demodulator 208 for each subcarrier signal using the demodulation method set by the transmission method setting section 60. The bits of the symbol signal sequence demodulated in the demodulator 208 are rearranged in a predetermined order in the de-interleaver 209, and then in the Viterbi decoder 210, the decoding algorithm set by the transmission method setting unit 60 is set. Is Viterbi decoded. More than,
3 is a description of the receiving unit 20.

Returning to the description of FIG. The fluctuation estimation unit 30 is a unit that estimates the degree of temporal fluctuation of the channel state. For example, the movement state of one's own communication device can be calculated using an acceleration sensor, a gyro sensor, a vibration meter, a speedometer, a GPS
It is detected by using a movement sensor such as (global positioning system), and based on the detection result, the degree of temporal fluctuation of the channel state is estimated. That is, when the communication device is moving, it is estimated that the channel state fluctuates quickly with time. In this case, as the estimation result of the channel state, a signal indicating whether or not the communication device is moving may be output by comparing the detection value of the moving state by the above-described moving sensor with a predetermined threshold value. . Alternatively, a signal indicating the rank of the moving speed may be output according to the detected value of the moving speed of the communication device.

Further, the fluctuation estimating section 30 includes the transmission path estimating section 2
It is also possible to detect the degree of temporal change of the estimated signal S206 of 06 and estimate the degree of temporal change of the channel state based on the detection result. It is possible to make a more direct estimation of the channel state compared to the estimation by detecting the moving state.

FIG. 5 is a diagram for explaining an example of detecting the temporal variation of the channel state by using the reference signal for channel estimation. 5A and 5B are signal point constellation diagrams for each subcarrier in the reference signal extracted by the transmission path estimation unit 206 in the frame k and the next frame k + 1, and FIG. 5C is shown in FIGS. 5A and 5B. The difference between the reference signals shown is shown for each subcarrier. Figure 5
As shown in C, the difference between the frames of the reference signal extracted by the transmission path estimation unit 206 is detected for each subcarrier, and the temporal variation of the channel state is calculated from the combined value obtained by combining this for all subcarriers. Can be estimated. For example, an absolute value or a square value of the above-described combined value (or an average value obtained by dividing the composite value by the number of subcarriers of one symbol) calculated as a complex number is calculated, and the calculated value and a predetermined threshold value are calculated. By the comparison, the temporal variation of the channel state is divided into two or more ranks for determination.

The notifying section 40 carries out a process of causing the transmitting section 10 to transmit information corresponding to the estimation result of the fluctuation estimating section 30 to the second communication device 2. For example, when the fluctuation estimation unit 30 estimates that the rank of the temporal fluctuation degree of the channel state has changed, the transmission unit 10 transmits information about the changed rank to the second communication device. The reference signal insertion interval at is changed.

The first setting section 51 sets the insertion interval of the reference signal in the transmission section 10 according to the estimation result of the fluctuation estimation section 30. Further, the reference signal insertion interval may be changed according to the transmission system of the transmission unit 10 and the reception unit 20 set in the transmission system setting unit 60. Generally, the higher the transmission rate is, the lower the error correction capability with respect to the change of the channel state is. Therefore, in such a transmission method, the error rate can be reduced by inserting the reference signal at a narrower interval.

The transmission method setting unit 60 selects a transmission method used for communication from a plurality of predetermined transmission methods and sets it in the transmission unit 10 and the reception unit 20. When the received data DR of the receiving unit 20 includes information designating the transmission method, the transmission method may be set accordingly.

The antenna duplexer 70 transmits the transmission signal Tx supplied from the transmitter 10 to the antenna AT and the antenna AT.
From the received signal Rx input to the receiving unit 20 to allow the transmitting unit 10 and the receiving unit 20 to share the antenna AT. Note that separate antennas may be provided for the transmitter 10 and the receiver 20 without providing the antenna duplexer 70.

FIG. 6 is a schematic block diagram showing a configuration example of the second communication device 2 in FIG. In the example of FIG. 6, the second communication device includes a transmitter 10, a receiver 20, a second setting unit 52, a transmission method setting unit 60, and an antenna duplexer 70. The same reference numerals in FIG. 6 and FIG. 2 indicate the same components.

The second setting section 52 extracts information from the received signal DR of the receiving section 20 according to the estimation result of the temporal fluctuation degree of the channel state transmitted by the notifying section 40 of the first communication device 1. Then, the reference signal insertion interval in the transmission unit 10 is set accordingly. Further, similar to the first setting unit 51, the reference signal insertion interval may be changed according to the transmission method set by the transmission method setting unit 60.

Next, the operation of changing the reference signal insertion interval in the communication system of FIG. 1 having the above configuration will be described with reference to the flowchart of FIG. 7, focusing on the operation of the first communication device 1. . Step ST10: First, the fluctuation estimation unit 30 estimates the temporal fluctuation of the channel state. For example, the movement state of the communication device is detected by the movement sensor, and the temporal fluctuation of the estimation signal S206 of the transmission path estimation unit 206 is detected, and the temporal fluctuation degree of the channel state is estimated from these detection results. .

Step ST11: Based on the temporal variation of the channel state estimated in step ST10, it is determined whether or not the reference signal insertion interval is changed. For example, if the rank of the temporal fluctuation degree of the channel state estimated by the fluctuation estimating unit 30 has changed from the previous estimation due to movement or stop of the communication device, the process proceeds to step ST12. If it has not changed, steps ST12 and ST13 are skipped.

Step ST12: Information according to the estimation result of the temporal fluctuation degree of the channel state is transmitted to the second communication device 2 by the notification unit 40. Step ST13: After the notification of the estimation result in step ST12, the first setting unit 51 sets a new reference signal insertion interval in the transmission unit 10. Also, in the second communication unit 2, the second communication unit 2 which has received the notification from the first communication unit 2
The setting unit 52 of 1 sets a new reference signal insertion interval in the transmitting unit 10. As a result, in the subsequent communication, the reference signal is inserted into the signal train transmitted from both communication devices at this newly set interval. In addition,
Before the communication is performed at the new reference signal insertion interval, the second communication unit 2 may return the reception confirmation signal for the notification of the estimation result to the first communication unit 1.

The above-described processing of FIG. 7 is performed, for example, in parallel with other communication processing while fetching the detection values of the movement sensor included in the fluctuation estimating unit 30 at a constant interrupt interval, or the temporal fluctuation of the estimated signal S206. Iteratively executed, calculating values at regular intervals.

FIG. 8 is a diagram showing an example of the reference signal inserted in the burst. FIG. 8A shows a burst when the temporal fluctuation of the channel state is low, for example, when the communication device is stopped, and in this example, the reference signal is not inserted in addition to the preamble. On the other hand, FIG. 8B and FIG. 8C show bursts when the channel state has a high degree of temporal variation, for example, when the communication device is moving, and examples of different burst lengths are shown. In this example, the reference signal is inserted at intervals of 4 OFDM symbols in addition to the preamble.

FIG. 9 is a diagram for explaining a specific example of the operation of changing the reference signal insertion interval. After the normal burst B1 in which the reference signal other than the preamble is not inserted is transmitted from the second communication device 2 to the first communication device, for example, as shown in FIG. 8A, the first communication device 1 moves. When a change occurs in the estimation result of the temporal fluctuation degree of the channel state in the fluctuation estimation unit 30 due to the start, the normal burst B2 including the information notifying the change is transmitted from the first communication device 1 to the second communication device. It is transmitted to the device 2. After the normal burst B2 is transmitted, in the first communication device 1, the reference signal insertion interval is newly set in accordance with the estimation result in the fluctuation estimation unit 30 and the transmission method set in the transmission method setting unit 60. It Further, the insertion interval is similarly set in the second communication device 2 which has received the normal burst B2. This causes burst B3 to be transmitted next.
In burst B5, reference signals are added at intervals such as shown in FIG. 8B.

When the first communication device returns from the moving state to the stopped state and a change occurs in the estimation result of the temporal fluctuation degree of the channel state in the fluctuation estimating section 30, a burst B6 including information notifying the change is generated. The (burst to which the reference signal is added) is transmitted from the first communication device 1 to the second communication device 2. After transmitting the burst B6, the first communication device 1
In, the insertion interval of the reference signal is returned to the original setting according to the estimation result in the fluctuation estimation unit 30 and the transmission method set in the transmission method setting unit 60. Also, the same setting is made in the second communication device 2 that has received this burst B6. This causes burst B7 to be transmitted next.
Returns to a normal burst with no added reference signal.

The above-mentioned example of FIG. 9 explains the change of the reference signal insertion interval due to the change of the estimation result of the fluctuation estimating unit 30, but in addition to this, the reference signal insertion is also made by the change of the transmission system, for example. The intervals are changed.

FIG. 10 is a diagram showing an example in which the interval of the reference signal inserted in the transmission signal sequence changes according to the transmission method.
FIG. 10A shows bursts in a low transmission rate transmission method, and in this example, a reference signal is inserted every 4 OFDM symbol intervals. On the other hand, FIG. 10B shows bursts in a transmission system with a high transmission rate,
In this example, the reference signal is inserted at intervals of 2 OFDM symbols.

FIG. 11 is a diagram for explaining a specific example of the operation of changing the reference signal insertion interval according to the change of the transmission system. From the second communication device 2 to the first communication device,
For example, as shown in FIG. 8A, after the normal burst B1 ′ in which the reference signal is not inserted other than the preamble is transmitted, the first communication device 1 starts moving, so that the channel state in the fluctuation estimating unit 30 is changed. When a change occurs in the estimation result of the temporal fluctuation degree, a normal burst B2 ′ including information notifying the change is transmitted from the first communication device 1 to the second communication device 2. After the transmission of the normal burst B2 ′, in the first communication device 1, the reference signal insertion interval is, for example, as shown in the figure depending on the estimation result in the fluctuation estimation unit 30 and the transmission method set in the transmission method setting unit 60. 10
Like A, it is set to 4 OFDM symbol intervals. In the second communication device 2 which has received the normal burst B2 ′, the insertion interval is set in the same manner. As a result, in the burst B3 ′ and the burst B4 ′ that are transmitted next, reference signals are inserted at intervals such as shown in FIG. 10A.

Furthermore, when a new transmission method is set in the second communication device 2, the burst B5 '(4 OFDM symbol intervals) including the information notifying the set transmission method is the second communication. Device 2 to first communication device 1
Sent to. After transmitting the burst B5 ′, a new transmission method is set in the second communication device 2, and the reference signal insertion interval according to the set transmission method is set in the transmission unit 10. The same setting is performed in the first communication device 1 that has received the burst B5 ′. As a result, in the next transmitted burst B6 ′, for example, as shown in FIG.
Reference signals are inserted at intervals such as B.

As described above, according to the communication system according to the first embodiment described above, the insertion interval of the channel estimation reference signal to be inserted into the transmission signal sequence is set according to the temporal variation of the channel state. As a result, the error in channel estimation is reduced, and the received signal can be properly equalized.
As a result, it is possible to effectively reduce the deterioration of communication quality due to the temporal change of the channel state. Further, since the performance with respect to the temporal fluctuation of the channel state is improved, for example, by applying this to a communication device of a wireless LAN, it becomes possible to communicate outdoors or while moving. Further, compared to a method of fixedly setting the insertion interval of the reference signal for channel estimation to be small, the number of reference signals to be inserted can be reduced when the temporal fluctuation of the channel state is small, for example, when the communication device is stationary. You can
Throughput can be improved.

The configuration example of the transmission unit 10 in FIG. 3 and the reception unit 20 in FIG. 4 shows the configuration in the case of performing communication by the OFDM system as an example, but the present invention is not limited to this example. For example, the configuration may be such that communication is performed using another multicarrier modulation method, or the configuration may be such that communication is performed using a single carrier modulation method.

Further, a user interface device such as a button, a switch or a contact sensor for inputting information regarding the setting of the reference signal insertion interval may be provided. For example, when the setting information is input from a user interface device (not shown) provided in the first communication device 1, the setting information is notified to the second communication device 2 by the notification unit 40. After the notification of the setting information, the first setting unit 51 of the first communication device 1 transmits the setting information to the transmission unit 1 according to the input setting information.
A reference signal insertion interval of 0 is set. Second communication device 2
In the second setting unit 52, the reference signal insertion interval in the transmission unit 10 is set according to the notified setting information. By providing such a user interface device, the reference signal insertion interval can be set according to the judgment of the user. For example, it is possible to improve communication quality by allowing the user to determine the time of movement and the time of non-movement to set the reference signal insertion interval.

<Second Embodiment> A second embodiment will be described. FIG. 12 is a schematic block diagram showing a configuration example of a receiving device according to the second embodiment of the present invention. The receiving apparatus shown in FIG. 12 includes a fluctuation estimation unit 30, an RF signal processing unit 201, an analog / digital conversion unit 202, an OFDM.
Demodulator 205, transmission path estimation unit 206, equalizer 207a,
The demodulator 208, the de-interleaver 209, the Viterbi decoder 210, and the averaging unit 211 are included. However,
12 and FIG. 2 and FIG. 4 show the same components.

Averaging section 211 averages estimated signal S206 of transmission path estimating section 206 for each subcarrier with a transfer function according to the estimation result of fluctuation estimating section 30.
For example, when the temporal fluctuation of the channel state is small, the transmission path estimation unit 206 over a plurality of past frames.
The averaged estimated signal S206 of the above is averaged, and when the temporal variation of the channel state is large, the estimated signal S206 of the transmission path estimation unit 206 is averaged with a smaller number of frames. Further, when obtaining the average value of the estimated signal S206 over a plurality of frames, each estimated signal S206 may be multiplied by a weighting coefficient. The averaging transfer function can be changed by changing the weighting coefficient according to the estimation result of the variation estimating unit 30.

The equalizer 207a is an OFDM demodulator 205.
Of a plurality of subcarrier signals included in the symbol signal output from
Equalization is performed according to the average value of 206.

The receiving operation of the receiving section of FIG. 12 having the above configuration will be described. The received signal Rx is subjected to predetermined high frequency signal processing in the RF signal processing unit 201, converted into a digital signal in the analog / digital conversion unit 202, and further demodulated in the OFDM demodulator 205 to include a plurality of subcarrier signals. It is converted into a signal sequence of a symbol signal. The symbol signal of the OFDM demodulator 205 is input to the transmission path estimation unit 206, and a reference signal for channel estimation is extracted from this signal sequence. And
An estimated signal S206 corresponding to each subcarrier is generated according to a difference between the plurality of subcarrier signals included in the extracted reference signal and a predetermined reference subcarrier signal corresponding to each of the plurality of subcarrier signals. It The above operation is similar to that of the receiving unit 20 of FIG.

The estimation signal S206 generated corresponding to each subcarrier is averaged in the averaging unit 211 with a transfer function according to the estimation result of the fluctuation estimating unit 30. In the equalizer 207a, the OFDM demodulator 20 according to the averaged estimation result of the transmission path estimation unit 206.
Five symbol signals are equalized for each subcarrier.

The symbol signal equalized by the equalizer 207a is then demodulated by the demodulator 2 as in the receiving section 20 of FIG.
Demodulated at 08, rearranged in a predetermined order at the de-interleaver 209, and the Viterbi decoder 210
Is decoded in Viterbi.

FIG. 13 is a flow chart for explaining the operation of changing the transfer function of averaging section 211. As shown in FIG. 13, first, in step ST20, the fluctuation estimation unit 30 estimates the temporal fluctuation of the channel state, and then in step ST21, an average is calculated based on the estimated temporal fluctuation of the channel state. Conversion unit 21
The transfer function at 1 is set. Such transfer function changing processing is performed, for example, in parallel with other reception processing while taking in the detection values of the movement sensor included in the fluctuation estimating unit 30 at constant interrupt intervals, or the temporal fluctuation value of the estimation signal S206 is constant. It is repeatedly executed while calculating at intervals of.

As described above, according to the receiving apparatus of FIG.
Since the transfer function for averaging the estimated values of the channel estimation can be changed according to the temporal fluctuation of the channel state, this allows the relationship between the temporal fluctuation of the channel state and the speed of the channel estimation. Can be kept properly. That is, in the stable state in which the temporal fluctuation of the channel state is small, the accuracy can be improved by averaging the channel estimation over a longer period. Also, in a fluctuating state in which the temporal fluctuation of the channel state is large, the averaging period is shortened, or the averaging is not performed at all to increase the speed of channel estimation,
It is possible to reduce the error in channel estimation by improving the followability to the fluctuation of the channel state. As a result, it is possible to effectively reduce the deterioration of communication quality due to the temporal change of the channel state.

FIG. 14 is a schematic block diagram showing another configuration example of the receiving apparatus according to the second embodiment of the present invention. The same symbols in FIG. 14 and FIG. 12 indicate the same components. The transmission method setting unit 60a selects a transmission method from among a plurality of predetermined transmission methods according to the transmission method on the transmission side, and according to the selected transmission method, the demodulation method of the demodulator 208 and the Viterbi decoder. Set 210 decoding algorithm. That is, the demodulation method of the demodulator 20 is set to the demodulation method corresponding to the modulation method (BPSK, QPSK, etc.) on the transmission side. Also, the de-puncturing scheme in the Viterbi decoder 210 is set according to the puncturing scheme in the convolutional coding processing on the transmission side.

The averaging unit 211a averages the estimated signal S206 of the transmission path estimating unit 206 with a transfer function according to the estimation result of the fluctuation estimating unit 30 and the transmission method set by the transmission method setting unit 60a.

Therefore, for example, when a transmission method with a high transmission rate is set, the averaging unit 211a can speed up the response of averaging to improve the followability of the channel estimation with respect to the change of the channel state, and reduce the When the transmission method of the transmission rate is set, the accuracy of channel estimation can be improved by lengthening the averaging period.

Note that the configuration examples of FIGS. 12 and 14 are O
Although the configuration in the case of receiving the signal modulated by the FDM system is shown as an example, the present invention is not limited to this example.
For example, the configuration may be such that communication is performed using another multicarrier modulation method, or the configuration may be such that communication is performed using a single carrier modulation method.

Further, the averaging unit 211 or the averaging unit 21
A user interface device such as a button, a switch, or a contact sensor for inputting information regarding the transfer function of 1a may be provided. By providing such a user interface device, it becomes possible to set the averaging transfer function according to the judgment of the user. For example, it is possible for the user to set the transfer function for averaging by himself / herself determining when moving and when not moving, thereby improving communication quality.

<Third Embodiment> A third embodiment will be described. FIG. 15 is a schematic block diagram showing a configuration example of a receiving device according to the third embodiment of the present invention. The receiving apparatus shown in FIG. 15 includes a fluctuation estimation unit 30, an RF signal processing unit 201, an analog / digital conversion unit 202, and an OFDM.
Demodulator 205, transmission path estimation unit 206, equalizer 207a,
It has a demodulator 208, a de-interleaver 209, a Viterbi decoder 210, an averaging unit 211, and a correction unit 212. However, the same reference numerals in FIG. 15 and FIG. 12 indicate the same components.

When the degree of temporal fluctuation of the channel state estimated by fluctuation estimating section 30 reaches a predetermined threshold, correcting section 212 corrects a specific subcarrier signal included in the symbol signal, for example, in FIG. The estimated signal S of the transmission path estimation unit 206 supplied to the averaging unit 211 according to the difference between the indicated pilot subcarrier signal and the reference subcarrier signal corresponding to this specific subcarrier signal.
Correct 206. That is, the estimation signal S206 of each subcarrier is corrected according to the result of channel estimation in a specific subcarrier. The correction of the transmission path state estimation result by the correction unit 212 is performed for each symbol signal output from the OFDM modulator 205.

The receiving operation of the receiving section of FIG. 15 having the above configuration will be described. The reception signal Rx is demodulated by the same process as the reception unit 20 of FIG. 4, and is OFD as a signal sequence of a symbol signal including a plurality of subcarrier signals.
It is output from the M demodulator 205.

The symbol signal of the OFDM demodulator 205 is input to the transmission path estimation unit 206 and the correction unit 212. In the channel estimation unit 206, a reference signal for channel estimation is extracted from the signal sequence of the symbol signal output from the OFDM demodulator 205, a plurality of subcarrier signals included in the reference signal, and the plurality of subcarrier signals. Depending on the difference from the respective predetermined reference subcarrier signals of
The channel state corresponding to each subcarrier is estimated.

When the estimation result of the temporal fluctuation degree of the channel state in the fluctuation estimating unit 30 has not reached the predetermined threshold value, the correction of the estimated signal S206 of the transmission path estimating unit 206 by the correcting unit 212 is invalidated. . Transmission path estimation unit 206
The estimated signal S206 of 1 is averaged by the averaging unit 211 with a transfer function according to the estimation result of the fluctuation estimating unit 30, and the average value is supplied to the equalizer 207a.

On the other hand, when the estimation result of the temporal fluctuation degree of the channel state in fluctuation estimating section 30 reaches a predetermined threshold value, a specific subcarrier signal such as a pilot subcarrier signal included in the symbol signal is received. And the estimated signal S2 of the transmission path estimation unit 206 supplied to the averaging unit 211 according to the difference between the reference subcarrier signal and the corresponding reference subcarrier signal.
06 is corrected by the correction unit 212. Since this correction is performed every time for each symbol signal including this specific subcarrier signal, the response speed to the temporal fluctuation of the channel state is increased.

In this case, the averaging process by the equalizer 207a is invalidated or speeded up in order to speed up the response to the temporal fluctuation of the channel state.

The symbol signal equalized by the equalizer 207a is then demodulated by the demodulator 208 and deinterleaved by the demodulator 208 by the same processing as that of the receiving section 20 of FIG.
The rearrangement by 9 and the Viterbi decoding by the Viterbi decoder 210 are performed.

The correction operation of the channel estimation result in the communication apparatus shown in FIG. 15 will be described with reference to the flowchart of FIG. First, in step ST30,
The fluctuation estimating unit 30 estimates the temporal fluctuation of the channel state, and based on the estimation result, it is determined in step ST31 whether the temporal fluctuation of the channel state has reached a predetermined threshold value. When it is determined that the variation is large, the correction process by the correction unit 212 is validated and the averaging process by the averaging unit 211 is invalidated (or speeded up) in step ST32. As a result, the estimated signal S206 that reflects the temporal variation of the channel state is corrected for each symbol signal. Therefore, the response speed with respect to the temporal fluctuation of the channel state is increased. When it is determined that the temporal change of the channel state is small, the correction process by the correction unit 212 is invalidated and the averaging process by the averaging unit 211 is validated in step ST33. Figure 1 above
The process of 6 is, for example, in parallel with other reception processes, while taking in the detection values of the movement sensor included in the fluctuation estimation unit 30 at a constant interrupt interval, or at the same time the temporal fluctuation value of the estimated signal S206. It is repeatedly executed while calculating.

As described above, according to the communication apparatus of FIG. 15 described above, when the temporal fluctuation degree of the channel state is small, channel estimation is performed using the same channel estimation reference signal as in FIG. 12, and this time is used. When the dynamic variation is large, the channel estimation result using the channel estimation reference signal is corrected according to the difference between the specific subcarrier signal included in each symbol signal and its reference signal. Therefore, when the channel state is stable, channel estimation using the channel estimation reference signal can be performed accurately. Further, when the channel state is fluctuating, the result of the channel estimation using the channel estimation reference signal is corrected for each symbol signal according to the channel estimation result in a specific subcarrier. It is possible to improve the followability to the fluctuation of.

As a method of correcting the channel estimation result of another subcarrier according to the channel estimation result of the specific subcarrier, for example, the channel estimation result of this specific subcarrier is calculated using an appropriate interpolation function. A method of calculating the correction amount of the channel estimation result in other subcarriers by interpolation is used.

Further, although the configuration example of FIG. 15 shows the configuration in the case of receiving a signal modulated by the OFDM system as an example, the present invention is not limited to this example. For example, the configuration may be such that communication is performed using another multicarrier modulation method.

In addition, a user interface device such as a button, a switch, or a contact sensor may be provided in order to input information regarding the selection of the channel estimation method in the selection unit 212. By providing such a user interface device, it becomes possible to select a channel estimation method according to the user's judgment. For example, it is possible to improve communication quality by allowing the user to determine the channel estimation method by himself / herself when he / she is moving or not.

<Fourth Embodiment> A fourth embodiment will be described. FIG. 17 is a schematic block diagram showing a configuration example of a communication device according to the fourth embodiment of the present invention. The communication device illustrated in FIG. 17 includes a transmission unit 10, a reception unit 20, a fluctuation estimation unit 30, an antenna duplexer 70, and a transmission method setting unit 100. However, the same reference numerals in FIG. 17 and FIGS. 2 to 4 indicate the same components.

The transmission method setting section 100 includes a fluctuation estimating section 30.
The setting of the modulation method in the modulator 103 of the transmission unit 10 and the demodulation method in the demodulator 208 of the reception unit 20 is changed according to the estimation result of the temporal fluctuation degree of the channel state in. That is, these modulation schemes and demodulation schemes are set to be the same for all subcarriers in one symbol signal, or are set for each subcarrier by adapting to the estimation signal S206 of each subcarrier by the transmission path estimation unit 206. To do.

The operation of changing the setting method of the modulation method and the demodulation method in the communication apparatus shown in FIG. 17 will be described with reference to the flowchart of FIG. First, in step ST40, the fluctuation estimation unit 30 estimates the temporal fluctuation of the channel state, and based on the estimation result, in step ST41, it is determined whether the temporal fluctuation of the channel state exceeds a predetermined threshold value. Is determined. If the variation is large, the modulation method and the demodulation method of all subcarriers of one symbol signal are set to the same in step ST42. If the fluctuation is small, step ST
At 43, a modulation method and a demodulation method adapted to the result of channel estimation are set for each subcarrier. In the processing of FIG. 18, for example, in parallel with other communication processing, the detection value of the movement sensor included in the fluctuation estimation unit 30 is fetched at a constant interrupt interval, or the estimated signal S206 is acquired.
Iteratively executed while calculating the time-varying value of {circle around (3)} at regular intervals.

As described above, according to the communication apparatus of FIG. 17 described above, when the channel state is stable, the modulation method and the demodulation method are set for each subcarrier in accordance with the result of channel estimation. Therefore, communication quality can be improved. Also, when the channel condition is fluctuating, the same modulation method and demodulation method are set for all subcarriers, so that the transmitter and receiver do not need to negotiate the transmission method for each subcarrier. Therefore, the channel estimation time interval can be shortened by that amount, and the channel estimation error can be reduced.

Although the configuration example of FIG. 15 shows the configuration in the case of receiving a signal modulated by the OFDM system as an example, the present invention is not limited to this example. For example, the configuration may be such that communication is performed using another multicarrier modulation method.
Further, in order to input information regarding the method of setting the transmission method in the transmission method setting unit 100, buttons, switches,
A user interface device such as a contact sensor may be provided. By providing such a user interface device, it is possible to determine whether the same transmission method is set for all subcarriers or whether the transmission method is set for each subcarrier according to the channel estimation result. Can be selected. For example, it is possible to improve communication quality by allowing the user to judge by himself whether he is moving or not and select the above-mentioned method of setting the transmission method.

The present invention is not limited to the above embodiment,
Various modifications are possible. For example, the communication device or the receiving device described above replaces part or all of the configuration thereof with a processing device such as a DSP capable of executing processing according to a program including the procedure described in each of the above-described embodiments. May be.

In the above description, the wireless communication device and the receiving device are mentioned as an example. However, for example, the wired communication device and the receiving device, or the communication device and the receiving device by the combination of the wired and the wireless. It is also possible to apply to.

[0105]

According to the present invention, it is possible to effectively reduce the deterioration of communication quality due to the temporal fluctuation of the channel state by changing the communication method according to the temporal fluctuation degree of the channel state. it can.

[Brief description of drawings]

FIG. 1 is a schematic block diagram showing a configuration example of a communication system according to a first embodiment of the present invention.

FIG. 2 is a schematic block diagram showing a configuration example of a first communication device.

FIG. 3 is a schematic block diagram showing a configuration example of a transmission unit.

FIG. 4 is a schematic block diagram showing a configuration example of a reception unit.

FIG. 5 is a diagram for explaining an example of detecting a temporal change in a channel state using a reference signal for channel estimation.

FIG. 6 is a schematic block diagram showing a configuration example of a second communication device.

FIG. 7 is a flowchart for explaining an operation of changing the insertion interval of the reference signal for channel estimation.

FIG. 8 is a diagram showing an example of a reference signal inserted in a burst.

FIG. 9 is a diagram for explaining a specific example of the operation of changing the reference signal insertion interval.

FIG. 10 is a diagram showing an example in which an interval of reference signals inserted in a transmission signal sequence changes according to a transmission method.

FIG. 11 is a diagram for explaining a specific example of the operation of changing the reference signal insertion interval according to the change of the transmission method.

FIG. 12 is a schematic block diagram showing a configuration example of a receiving device according to a second embodiment of the present invention.

FIG. 13 is a flowchart for explaining the operation of changing the transfer function of the averaging unit.

FIG. 14 is a schematic block diagram showing another configuration example of the receiving device according to the second embodiment of the present invention.

FIG. 15 is a schematic block diagram showing a configuration example of a receiving device according to a third embodiment of the present invention.

FIG. 16 is a flowchart for explaining an operation of correcting a channel estimation result.

FIG. 17 is a schematic block diagram showing a configuration example of a communication device according to a fourth embodiment of the present invention.

FIG. 18 is a flowchart for explaining the operation of changing the setting method of the modulation method and the demodulation method.

FIG. 19 is a diagram showing a channel estimation signal included in a MAC frame.

[Fig. 20] Fig. 20 is a diagram illustrating a configuration example of a multicarrier modulation signal modulated by the OFDM system.

FIG. 21 is a diagram for explaining channel estimation using a reference signal for channel estimation.

[Explanation of symbols]

1 ... 1st communication apparatus, 2 ... 2nd communication apparatus, 10 ... Transmission part, 20 ... Reception part, 30 ... Fluctuation estimation part, 40 ... Notification part,
51 ... 1st setting part, 52 ... 2nd setting part, 60, 10
0 ... Transmission method setting unit, 70 ... Antenna duplexer, 101 ...
Convolutional encoder, 102 ... Interleaver, 103 ...
Modulator, 104 ... IFFT, 105 ... Guard interval addition section, 106 ... OFDM modulator, 107 ... Transmission signal string formation section, 108 ... Digital / analog conversion section, 10
9, 201 ... RF processing unit, 202 ... Analog / digital conversion unit, 203 ... Synchronization unit, 204 ... FFT unit, 205 ...
OFDM demodulator, 206, 206a, 206b ... Transmission path estimation unit, 207, 207a, 207b ... Equalizer, 208
... demodulator, 209 ... de-interleaver, 210 ... Viterbi decoder, 211, 211a ... averaging section, 212 ... selecting section.

Continued front page    F-term (reference) 5K014 BA10 BA11 FA16                 5K022 DD01 DD13 DD18 DD19 DD23                       DD33 DD34                 5K046 AA05 EE06 EE42                 5K067 AA01 BB04 DD25 GG01 GG11

Claims (46)

[Claims] 1. A communication system having a first communication device and a second communication device, wherein the first communication device and the second communication device insert predetermined reference signals at regular intervals. Transmitting means for transmitting the extracted signal sequence, and a transmission path for extracting the reference signal from the received signal sequence and estimating a transmission path state according to a difference between the extracted reference signal and the predetermined reference signal. The first communication device has an estimating means and a receiving means including an equalizing means for equalizing a received signal sequence according to the estimation result of the transmission path estimating means. According to the estimation result of the fluctuation estimation means, the fluctuation estimation means for estimating the degree of temporal fluctuation, the notification means for notifying the second communication device of information according to the estimation result of the fluctuation estimation means, Insertion of the reference signal in the transmitting means The second communication device further includes a first setting unit that sets an interval, and the second communication device sets an insertion interval of the reference signal in the transmission unit according to information notified from the first communication device. A communication system further comprising second setting means. 2. The communication according to claim 1, wherein the fluctuation estimating means estimates the temporal fluctuation degree of the transmission path state according to the degree of temporal fluctuation of the estimation result of the transmission path estimating means. system. 3. The modulating means for multiplexing a subcarrier signal in which a signal of 1 bit or a plurality of bits forming one symbol signal is modulated with a plurality of subcarriers, and outputting a multicarrier modulated signal. The receiving means includes demodulating means for demodulating the received signal sequence and outputting a signal sequence of a symbol signal including a plurality of subcarrier signals, and the transmission path estimating means includes a signal sequence of the symbol signal. From the reference signal is extracted from, a plurality of subcarrier signals included in the extracted reference signal, and the difference between the corresponding reference subcarrier signal of each of the plurality of subcarrier signals, in the plurality of subcarriers The transmission path state is estimated, and the fluctuation estimating means detects the degree of temporal fluctuation of the estimation result of the transmission path estimating means for each subcarrier. ,
The communication system according to claim 2, wherein the temporal fluctuation degree of the transmission path state is estimated according to a value obtained by combining the detected value for all subcarriers. 4. The communication system according to claim 1, wherein the fluctuation estimating means estimates the temporal fluctuation degree of the transmission path condition according to the result of detecting the moving condition of the communication device of its own. 5. The communication system according to claim 4, wherein the fluctuation estimating means estimates the temporal fluctuation degree of the transmission path state according to the speed at which the communication device of its own moves. 6. The first communication device has an input means for inputting information on the setting of the insertion interval, and the notifying means notifies the second communication device of the input setting information, The first setting means sets an insertion interval of the reference signal in the transmitting means according to the input setting information, and the second setting means notifies the insertion interval from the first communication device. The communication system according to claim 1, wherein an insertion interval of the reference signal in the transmitting means is set according to setting information. 7. The transmitting means and the receiving means perform transmission or reception of a signal string using a transmission method selected from a plurality of predetermined transmission methods, and the first setting means and the second setting means. The communication system according to claim 1, wherein the setting unit changes the insertion interval according to the selected transmission method. 8. The transmission means uses a convolutional encoding process of a transmission signal sequence using an encoding rate corresponding to the selected transmission method, or a modulation method corresponding to the selected transmission method. One or both of the modulation processing of the transmission signal sequence is performed, and the receiving means decodes the reception signal sequence using the decoding algorithm corresponding to the selected transmission method or the selected transmission method. The communication system according to claim 7, wherein one or both of demodulation processing of a received signal sequence using a demodulation method corresponding to the method is performed. 9. A signal sequence in which a predetermined reference signal is inserted at regular intervals is transmitted between communication devices that communicate with each other, and the reference signal is extracted from the signal sequence after the transmission, and the extracted reference signal is extracted. Is a communication method that equalizes the signal sequence after the transmission according to the difference between the reference signal and the predetermined reference signal, and estimates the degree to which the transmission line state fluctuates with time, A communication method in which the reference signal is inserted into the transmission signal sequence at intervals according to. 10. One of the communication devices estimates the degree to which the transmission path state fluctuates with time, notifies one communication device of the information according to the estimation result to the other communication device, and performs the estimation. The communication method according to claim 9, wherein the reference signal is inserted into the transmission signal sequence at an interval according to a result. 11. The one communication apparatus estimates the degree of temporal variation of the transmission path state according to the degree of temporal variation of the difference between the extracted reference signal and the predetermined reference signal. The communication method according to claim 10. 12. A signal transmitted between the communication devices is a multi-channel signal generated by multiplexing a subcarrier signal in which a 1-bit signal or a multi-bit signal forming a 1-symbol signal is modulated with a plurality of subcarriers. Carrier modulated signal, in one of the above communication devices, demodulates the signal sequence after transmission to generate a signal sequence of symbol signals including a plurality of subcarrier signals, and from the signal sequence of the generated symbol signals Extracting the reference signal, the plurality of subcarrier signals included in the extracted reference signal, and the transmission in the plurality of subcarriers according to the difference between the respective corresponding reference subcarrier signals of the plurality of subcarrier signals Estimate the channel state, detect the degree of temporal variation in the estimation result of the channel state for each subcarrier, and use the detected value for all subcarriers. The communication method according to claim 11, wherein the temporal variation of the transmission path state is estimated according to the value combined by the carrier. 13. The communication method according to claim 10, wherein the temporal fluctuation degree of the transmission path state is estimated according to a result of detecting a moving state of the one communication device. 14. The information regarding the insertion interval is input to the one communication device, the input information is notified from the one communication device to the other communication device, and the information is input at an interval according to the input information. The communication method according to claim 10, wherein the reference signal is inserted into the transmission signal sequence. 15. The communication according to claim 9, wherein a transmission method used for communication is selected from a plurality of predetermined transmission methods, and the insertion interval of the reference signal is changed according to the selected transmission method. Method. 16. A signal sequence in which a predetermined reference signal is inserted at a constant interval is transmitted at the time of transmission, and the reference signal is extracted from a received signal sequence at the time of reception, and the extracted reference signal and the above A communication device that equalizes the signal sequence after the transmission according to a difference from a predetermined reference signal, a step of estimating the degree of temporal change of the transmission path state, and information about the estimation result is transmitted to a communication partner. And a step of setting an insertion interval of the reference signal in the transmission signal sequence according to the estimation result. 17. A receiving device for receiving a signal sequence in which a predetermined reference signal is inserted at regular intervals, wherein the reference signal is extracted from the received signal sequence, and the extracted reference signal and the predetermined reference are extracted. A transmission path estimating means for estimating a transmission path state according to a difference with a signal, a fluctuation estimating means for estimating a degree of temporal fluctuation of the transmission path state, and a transfer function according to an estimation result of the fluctuation estimating means. A receiving apparatus having: an averaging means for averaging the estimation results of the transmission path estimating means; and an equalizing means for equalizing a received signal sequence according to the estimation results averaged by the averaging means. 18. The reception according to claim 17, wherein the fluctuation estimating means estimates the temporal fluctuation degree of the transmission path state according to the degree of temporal fluctuation of the estimation result of the transmission path estimating means. apparatus. 19. A signal sequence of a multicarrier modulation signal generated by multiplexing a subcarrier signal in which a signal of 1 bit or a plurality of bits forming one symbol signal is modulated by a plurality of subcarriers is demodulated to obtain a plurality of signals. Demodulation means for outputting a signal sequence of a symbol signal including a subcarrier signal, wherein the transmission path estimation means extracts the reference signal from the signal sequence of the symbol signal and outputs a plurality of signals included in the extracted reference signal. Of the subcarrier signals and the reference subcarrier signals respectively corresponding to the plurality of subcarrier signals, the transmission path states in the plurality of subcarriers are estimated, and the fluctuation estimation means is the transmission path estimation means. Detecting the degree of temporal fluctuation of the estimation result of for each subcarrier,
The receiving device according to claim 18, wherein the temporal fluctuation degree of the transmission path state is estimated according to a value obtained by combining the detected value for all subcarriers. 20. The receiving apparatus according to claim 17, wherein the fluctuation estimating means estimates the temporal fluctuation degree of the transmission path state according to the moving state of the receiving apparatus of itself. 21. The receiving apparatus according to claim 20, wherein the fluctuation estimating means estimates the temporal fluctuation degree of the transmission path state according to the speed at which the receiving apparatus moves. 22. The receiving device according to claim 17, further comprising input means for inputting information relating to the setting of the transfer function, wherein the averaging means sets the transfer function according to the input setting information. 23. The signal sequence is received using a transmission method selected from a plurality of predetermined transmission methods, and the averaging means changes the transfer function according to the selected transmission method. The receiving device according to claim 17. 24. The reference signal is extracted from a received signal sequence in which a predetermined reference signal is inserted at regular intervals, and a transmission path state is set according to a difference between the extracted reference signal and the predetermined reference signal. It is a receiving method that estimates and equalizes the received signal sequence according to the estimation result of the transmission path state, and estimates the degree of temporal variation of the transmission path state, and has a transfer function according to the estimation result. A receiving method for averaging the estimation results of the transmission path states and equalizing the received signal sequence according to the averaged estimation results. 25. The reception method according to claim 24, wherein the temporal variation of the transmission path state is estimated according to the degree of temporal variation of the estimation result of the transmission path state. 26. A signal sequence of a multi-carrier modulated signal generated by multiplexing a sub-carrier signal in which a 1-bit signal or a plurality of bits constituting a 1-symbol signal is modulated with a plurality of sub-carriers is demodulated to obtain a plurality of signals. Generating a signal sequence of the symbol signal including the subcarrier signal of, extracting the reference signal from the signal sequence of the symbol signal,
According to the difference between the plurality of subcarrier signals included in the extracted reference signal and the corresponding reference subcarrier signal of each of the plurality of subcarrier signals, the transmission path state in the plurality of subcarriers is estimated, and A degree of temporal variation in the estimation result of the transmission path state is detected for each subcarrier, and the temporal variation degree of the transmission path state is estimated according to a value obtained by combining the detected value with all the subcarriers. Item 25. The reception method according to Item 25. 27. The receiving method according to claim 24, wherein the temporal fluctuation degree of the transmission path state is estimated according to the moving state of the receiving apparatus. 28. The receiving method according to claim 24, wherein the information about the setting of the transfer function is input, and the estimation result of the transmission path state is averaged by the transfer function according to the input setting information. . 29. A transmission method used for receiving a signal sequence is selected from a plurality of predetermined transmission methods, and is selected according to the selected transmission method and the estimation result of the temporal fluctuation degree of the transmission path state. 25. The reception method according to claim 24, wherein the transfer path state estimation results are averaged by using the transfer function. 30. The reference signal is extracted from a received signal sequence in which a predetermined reference signal is inserted at regular intervals, and a transmission line state is set according to a difference between the extracted reference signal and the predetermined reference signal. The receiving device that estimates and equalizes the received signal sequence according to the estimation result of the transmission path state has a step of estimating the degree of temporal variation of the transmission path state, and a transfer function according to the estimation result. A program for executing processing including: averaging the transmission path state estimation results; and equalizing the received signal sequence according to the averaged estimation results. 31. A signal sequence of a multi-carrier modulated signal generated by multiplexing a sub-carrier signal in which a 1-bit signal or a multi-bit signal forming a 1-symbol signal is modulated with a plurality of sub-carriers, at regular intervals. A receiving device for receiving a signal sequence in which a predetermined reference signal is inserted, demodulating means for demodulating the received signal sequence and outputting a signal sequence of a symbol signal including a plurality of subcarrier signals, and the symbol Extract the reference signal from the signal sequence of the signal,
A transmission path for estimating transmission path states in a plurality of subcarriers according to a difference between a plurality of subcarrier signals included in the extracted reference signal and a corresponding reference subcarrier signal of each of the plurality of subcarrier signals. Estimating means, equalizing means for equalizing each subcarrier signal of the symbol signal according to the estimation result of the transmission path estimating means, and fluctuation estimation for estimating the degree of temporal fluctuation of the transmission path state. Means, when the temporal fluctuation degree estimated in the fluctuation estimating means reaches a predetermined threshold value, a specific subcarrier signal included in the symbol signal, and a reference corresponding to the specific subcarrier signal A receiving device comprising: a correction unit that corrects the estimation result of the transmission path estimation unit supplied to the equalization unit according to the difference from the subcarrier signal. 32. The fluctuation estimating means detects the degree of temporal fluctuation of the estimation result of the transmission path estimating means for each subcarrier, and according to a value obtained by combining the detected value with all the subcarriers. The receiving device according to claim 31, wherein the temporal variation of the transmission path state is estimated. 33. The receiving apparatus according to claim 31, wherein the variation estimating means estimates the temporal variation of the transmission path state according to the moving state of the receiving apparatus of itself. 34. An input means for inputting information on the selection of the estimation result of the transmission path state is provided, and the selection means selects the estimation result of the transmission path state according to the input selection information. The receiving device according to claim 31. 35. A signal train of a multicarrier modulation signal generated by multiplexing a subcarrier signal in which a signal of 1 bit or a plurality of bits forming one symbol signal is modulated with a plurality of subcarriers, at regular intervals. Demodulating the received signal sequence in which a predetermined reference signal is inserted to generate a signal sequence of a symbol signal containing a plurality of subcarrier signals, and extracting the reference signal from the signal sequence of the generated symbol signal, A plurality of subcarrier signals included in the extracted reference signal, and in accordance with the difference between the reference subcarrier signal corresponding to each of the plurality of subcarrier signals, the transmission path state in the plurality of subcarriers is estimated, A receiving method for equalizing each subcarrier signal of the symbol signal according to the estimation result of the transmission line state, wherein the transmission line state is temporal The degree of fluctuation is estimated, and when the estimated temporal fluctuation reaches a predetermined threshold value, a specific subcarrier signal included in the symbol signal and a reference corresponding to the specific subcarrier signal. Depending on the difference with the subcarrier signal, the estimation result of the transmission path state in the plurality of subcarriers is corrected, and in accordance with the corrected estimation result, the respective subcarrier signals of the symbol signal are equalized, Receiving method. 36. The time of the transmission line state is detected according to a value obtained by detecting the degree of temporal fluctuation of the estimation result of the transmission line state of the plurality of subcarriers and combining the detected value with all the subcarriers. The reception method according to claim 35, wherein the degree of dynamic variation is estimated. 37. The receiving method according to claim 35, wherein the temporal fluctuation degree of the transmission path state is estimated according to the moving state of the receiving apparatus. 38. A signal train of a multi-carrier modulation signal generated by multiplexing a sub-carrier signal in which a 1-bit signal or a plurality of bits constituting a 1-symbol signal is modulated with a plurality of sub-carriers, at regular intervals. Demodulating the received signal sequence in which a predetermined reference signal is inserted to generate a signal sequence of a symbol signal containing a plurality of subcarrier signals, and extracting the reference signal from the signal sequence of the generated symbol signal, A plurality of subcarrier signals included in the extracted reference signal, and in accordance with the difference between the reference subcarrier signal corresponding to each of the plurality of subcarrier signals, the transmission path state in the plurality of subcarriers is estimated, Depending on the estimation result of the channel state, the channel state of the receiving device that equalizes each subcarrier signal of the symbol signal varies with time. And a specific subcarrier signal included in the symbol signal when the estimated temporal variation reaches a predetermined threshold value, and a specific subcarrier signal corresponding to the specific subcarrier signal. A step of correcting the estimation result of the transmission path state in the plurality of subcarriers according to the difference from the reference subcarrier signal; and a step of correcting each subcarrier signal of the symbol signal according to the corrected estimation result. A program for executing a process including a step of changing the process. 39. A first modulation means for respectively modulating a 1-bit or a plurality of bits constituting a 1-symbol signal by a set modulation method, and a plurality of signals modulated by the first modulation means. Second modulation means for modulating and multiplexing with subcarriers to output a multicarrier modulation signal, and a transmission signal sequence in which a predetermined reference signal is inserted at regular intervals in the signal sequence of the multicarrier modulation signal Transmission signal sequence forming means, first demodulation means for demodulating the received signal sequence and outputting a signal sequence of a symbol signal including a plurality of subcarrier signals, and the reference signal from the signal sequence of the symbol signal Extract
A transmission path for estimating transmission path states in a plurality of subcarriers according to a difference between a plurality of subcarrier signals included in the extracted reference signal and a corresponding reference subcarrier signal of each of the plurality of subcarrier signals. Estimating means, equalizing means for equalizing each subcarrier signal of the symbol signal according to the estimation result of the transmission path state, and symbol signal equalized by the equalizing means for the set demodulation Second demodulation means for demodulating by a method, fluctuation estimation means for estimating the degree of temporal fluctuation of the transmission path state, and modulation method for the first modulation means according to the estimation result of the fluctuation estimation means. And the demodulation method of the second demodulation means is set to be the same for all subcarriers, or the subcarriers are adjusted for each subcarrier according to the estimation result of the transmission path estimation means. And a transmission method setting means for setting the communication method. 40. The fluctuation estimating means detects, for each subcarrier, a degree of temporal fluctuation of the estimation result of the transmission path estimating means, and according to a value obtained by combining the detected value with all the subcarriers. 40. The communication device according to claim 39, wherein the degree of temporal variation of the transmission path state is estimated. 41. The communication device according to claim 39, wherein the fluctuation estimating means estimates the temporal fluctuation degree of the transmission path condition according to the movement condition of the communication device of its own. 42. An input device for inputting information on the setting of the transmission method setting device, wherein the transmission method setting device is responsive to the information input to the input device, and the modulation method in the first modulating device and the transmission method. 40. The communication device according to claim 39, wherein the demodulation method of the second demodulation means is set to be the same for all subcarriers, or is set for each subcarrier according to the estimation result of the transmission path estimation means. . 43. At the time of transmission, a 1-bit signal or a multi-bit signal forming a 1-symbol signal is modulated by a set modulation method, and the modulated signal is modulated by a plurality of subcarriers and multiplexed. , A predetermined reference signal is inserted into the signal sequence of the multiplexed modulated signal at regular intervals to form a transmission signal sequence, and at the time of reception, the received signal sequence is demodulated to obtain a plurality of subcarrier signals. Generating a signal sequence of the symbol signal including, extracting the reference signal from the signal sequence of the generated symbol signal, a plurality of subcarrier signals included in the extracted reference signal, and the plurality of subcarriers According to the difference between the signal and the corresponding reference subcarrier signal, the transmission path state in a plurality of subcarriers is estimated,
A communication method for equalizing each subcarrier signal of the symbol signal according to an estimation result of the transmission path state, and demodulating the equalized symbol signal according to a set demodulation method, comprising: Estimate the degree of temporal fluctuation of the state and set the modulation method and demodulation method of the symbol signal to be the same for all subcarriers, or to estimate the transmission path state, according to the estimation result. A communication method that adapts to and is set for each subcarrier. 44. The degree of temporal variation of the estimation result of the transmission path state is detected for each subcarrier, and the temporal variation of the transmission path state is detected according to a value obtained by combining the detected value with all the subcarriers. The communication method according to claim 43, wherein the degree is estimated. 45. The communication method according to claim 43, wherein the temporal variation of the transmission path state is estimated according to the moving state of the communication device. 46. At the time of transmission, a 1-bit signal or a multi-bit signal constituting a 1-symbol signal is modulated by a set modulation method, and the modulated signal is modulated by a plurality of subcarriers and multiplexed. , A predetermined reference signal is inserted into the signal sequence of the multiplexed modulated signal at regular intervals to form a transmission signal sequence, and at the time of reception, the received signal sequence is demodulated to obtain a plurality of subcarrier signals. Generating a signal sequence of the symbol signal including, extracting the reference signal from the signal sequence of the generated symbol signal, a plurality of subcarrier signals included in the extracted reference signal, and the plurality of subcarriers According to the difference between the signal and the corresponding reference subcarrier signal, the transmission path state in a plurality of subcarriers is estimated,
According to the estimation result of the transmission path state, the communication apparatus that equalizes each subcarrier signal of the symbol signal and demodulates the equalized symbol signal by the set demodulation method is used. According to the step of estimating the degree of temporal fluctuation and the estimation result, the modulation method and the demodulation method of the symbol signal are set to be the same for all subcarriers, or the estimation result of the transmission path state is set. And a program for adapting to each sub-carrier and setting each sub-carrier.