JP2001094524A - Communication system, transmitter, receiver, transmitting method, receiving method, and information recording medium - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a communication system which uses an orthogonal frequency division multiplex transmission system. SOLUTION: A transmitter 102 of the communication system 101 receives and converts a digital signal from serial to parallel, inserts a known data series into the signal at intervals of a specific number of symbols to impart the digital signal after the insertion and a pilot data series as a frequency component input other than a DC component input, and gives zero data to the DC component input and performs inverse Fourier transformation to obtain and send an analog signal to a receiver. A receiver 103 receives and converts the analog signal into a digital signal, accepts a pilot data series as the same frequency component input as the transmitter device 102 and zero data for others, performs inverse Fourier transformation, equalizes the converted digital signal with multipath radio wave propagation characteristics obtained by correlation with two digital signals, equalizes the converted digital signal, performs Fourier transformation and parallel-series conversion, and outputs the resulting signal.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an orthogonal frequency division multiplex transmission.
g; OFDM) system, a transmission device, a reception device, a transmission method, a reception method, and an information recording medium.

[0002]

2. Description of the Related Art Conventionally, an OFDM communication system using Fourier transform and inverse Fourier transform has been proposed. FIG. 1 is a schematic diagram showing a schematic configuration of such an OFDM. Hereinafter, description will be made with reference to FIG.

A transmitting apparatus 102 of an OFDM communication system 101 transmits a plurality of received digital signals (2M
) Digital-to-serial-to-parallel conversion, complex-encoding these into a plurality (M) of complex signals, and performing an inverse Fourier transform to generate a single complex digital signal multiplexed by orthogonal frequency division multiplexing. Are converted to analog signals by a quadrature modulator and a digital-analog converter and transmitted.

On the other hand, a receiving apparatus 103 of such an OFDM communication system 101 receives an analog signal transmitted by a transmitting apparatus 102 and converts the received analog signal into a complex digital signal by a quadrature demodulator and an analog-digital converter. Into a signal, perform a Fourier transform for each of a plurality of (M) complex signals, separate a real part and an imaginary part thereof, decode them into a plurality of (2M) digital signals, and convert them into a single digital signal. , And obtains this as a desired digital signal.

[0005] The transmitting apparatus 102 performs up-conversion at the time of conversion into an analog signal, and the receiving apparatus 10
In No. 3, down conversion is performed at the time of conversion into a digital signal.

[0006] In the Fourier transform and the inverse Fourier transform, a discrete Fast Fourier Transform (FF) is used.
T) and inverse fast Fourier transform (Inverse FFT; IFF)
T). In this specification, for ease of understanding, `` complex encoding, inverse Fourier transform, and orthogonal modulation '' and `` quadrature demodulation, Fourier transform, inverse encoding, and parallel-serial conversion '' are referred to. , Respectively, such as “inverse Fourier transform” and “Fourier transform”.

[0007] The OFDM system is receiving attention as a method of obtaining excellent reception characteristics under a multipath radio wave propagation environment, and is being applied to the field of mobile communication in addition to digital broadcasting. In particular, the OFDM system has a great effect on reducing inter-symbol interference when transmitting wideband data.

[0008]

SUMMARY OF THE INVENTION However, OFD
In the M-system receiving apparatus, the signal received as described above is subjected to processing such as Fourier transform after being converted to a complex digital signal, so that the influence of a delayed wave existing in a symbol can be easily and accurately removed. There is a strong need for a method to do this.

In an electric circuit using the inverse Fourier transform or the Fourier transform, a DC component of a frequency component input is susceptible to fluctuations. Therefore, a method that is less susceptible to such fluctuations is desired.

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and a communication system of an orthogonal frequency division multiplexing transmission system suitable for performing stable communication by removing interference waves due to multipath. An object of the present invention is to provide a transmitting device, a receiving device, a transmitting method, a receiving method, and an information recording medium on which a program for realizing the same is recorded.

[0011]

In order to achieve the above object, the following invention is disclosed in accordance with the principle of the present invention.

[0012] The communication system of the present invention is configured to include a transmitting device and a receiving device that communicate by sharing a known data sequence and a predetermined pilot data sequence.

The transmitting device outputs a plurality of digital signals obtained by serial-to-parallel conversion of the received digital signals and outputs a predetermined symbol to each of the plurality of digital signals converted to serial-parallel. Outputting a plurality of digital signals into which a known data sequence is inserted every other number, and outputting a plurality of digital signals inserted and output as frequency component inputs other than the DC component input;
And a pilot data sequence, accepts zero data as a frequency component of a DC component input, outputs a digital signal subjected to inverse Fourier transform, converts the inverse Fourier-transformed digital signal to an analog signal, and converts the digital signal to a receiving device. Send.

The receiving device receives the analog signal transmitted by the transmitting device, converts the analog signal into a digital signal, and the inverse Fourier transform unit of the transmitting device uses the pilot data as the same frequency component input as the one receiving the pilot data sequence. Accepts a sequence, accepts zero data as the other frequency component input, outputs an inverse Fourier-transformed digital signal,
A multipath radio propagation characteristic is obtained by correlating the digital signal output by the inverse Fourier transform, and a digital signal obtained by equalizing the converted digital signal based on the obtained multipath radio propagation characteristic is output. Outputs a plurality of digital signals obtained by performing a Fourier transform on the equalized digital signal, outputs a single digital signal obtained by performing a parallel / serial conversion on the plurality of digital signals obtained by performing a Fourier transform, and performs a parallel / serial conversion. The output signal is output as a single signal.

Here, the pilot data sequence is used for estimating multipath radio wave propagation characteristics. The known data sequence is used to remove an interference wave that causes inter-symbol interference based on the estimated multipath radio wave propagation characteristics. The multipath radio wave propagation characteristics include a delay time between a preceding wave and a delayed wave, a phase change, an amplitude change, and the like. The same applies hereinafter.

Further, the inverse Fourier transform unit of the transmitting apparatus of the communication system of the present invention receives the pilot data sequence as a plurality of frequency component inputs, and the frequencies of the plurality of frequency component inputs are at predetermined frequency intervals. It can be configured as follows.

Further, the pilot data sequence of the communication system of the present invention can be configured to be a pseudo noise sequence.

A communication system according to the present invention is configured to include a transmitting device and a receiving device that share and communicate a known data sequence and a pilot data sequence having the same length as the known data sequence.

The transmitting device receives the digital signal,
A plurality of digital signals obtained by serial-to-parallel conversion of the received digital signals are output, and a known data sequence or a pilot data sequence is output for each of the plurality of digital signals output by serial-to-parallel conversion every predetermined number of symbols. And outputs a plurality of digital signals inserted in a predetermined order, receives a plurality of digital signals inserted and output as frequency component inputs other than the DC component input,
It receives zero data as a frequency component of a DC component input, outputs a digital signal subjected to inverse Fourier transform, converts the digital signal output after inverse Fourier transform into an analog signal, and transmits the analog signal.

The receiving device receives the analog signal transmitted by the transmitting device, converts the signal into a digital signal, and inserts a pilot data sequence into the output digital signal to receive the frequency component received by the inverse Fourier transform unit of the transmitting device. Accepts a pilot data sequence as the same frequency component input as the input, accepts zero data as the other frequency component input, outputs the inverse Fourier transformed digital signal, and outputs the transformed digital signal and the inverse Fourier transformed A multipath radio propagation characteristic is obtained by correlating the digital signal with the obtained digital signal, and a digital signal obtained by equalizing the converted digital signal is output based on the obtained multipath radio propagation characteristic. Output a plurality of digital signals obtained by Fourier-transforming the A plurality of digital signals outputted been converted outputs a single digital signal parallel-to-serial conversion, and outputs a single digital signal output in parallel-serial conversion.

Here, the "pilot data sequence having the same length as the known data sequence" means that both have the same number of symbols and require the same time to be transmitted. Further, these lengths may be any length of one or more symbols.

Further, in the communication system according to the present invention, the predetermined order may be configured such that the pilot data sequence is inserted at a predetermined interval from the known data sequence.

The transmitting apparatus according to the present invention includes a receiving unit, a serial-to-parallel converting unit, an inserting unit, an inverse Fourier transforming unit, a transmitting unit,
It comprises so that it may be provided.

The accepting section accepts a digital signal.

The serial-to-parallel converter outputs a plurality of digital signals obtained by serial-to-parallel conversion of the received digital signals.

The insertion section outputs a plurality of digital signals in which a known data sequence is inserted every predetermined number of symbols for each of the plurality of digital signals output after serial-to-parallel conversion.

The inverse Fourier transform unit receives a plurality of digital signals inserted and output as frequency component inputs other than the DC component input and a pilot data sequence,
It accepts zero data as a frequency component of a DC component input and outputs a digital signal that has been subjected to inverse Fourier transform.

The transmitting section converts the digital signal output after the inverse Fourier transform into an analog signal and transmits the analog signal.

Further, the inverse Fourier transform unit of the transmitting apparatus of the present invention receives the pilot data sequence as a plurality of frequency component inputs, and the frequencies of the plurality of frequency component inputs are arranged at predetermined frequency intervals. can do.

Further, the pilot data sequence of the transmitting apparatus of the present invention can be configured to be a pseudo noise sequence.

A receiving apparatus according to the present invention includes a receiving section, an inverse Fourier transform section, a multipath radio wave propagation characteristic acquiring section, an equalizing section, a Fourier transform section, a parallel / serial converting section, an output section,
It comprises so that it may be provided.

The receiving section receives an analog signal and converts it into a digital signal.

The inverse Fourier transform unit receives a pilot data sequence as a predetermined frequency component input, receives zero data as the other frequency component input, and outputs a digital signal subjected to the inverse Fourier transform.

The multipath radio wave propagation characteristic acquiring section obtains a multipath radio wave propagation characteristic by correlating the converted digital signal with the digital signal output after inverse Fourier transform.

The equalizer outputs a digital signal obtained by equalizing the converted digital signal based on the acquired multipath radio wave propagation characteristics.

The Fourier transform section outputs a plurality of digital signals obtained by Fourier transforming the equalized digital signal.

The parallel-to-serial conversion unit outputs a single digital signal obtained by performing parallel-to-serial conversion on a plurality of digital signals output by Fourier transform.

The output section outputs a single signal that has been converted from parallel to serial and output.

Further, the inverse Fourier transform unit of the receiving apparatus of the present invention receives the pilot data sequence as a plurality of frequency component inputs, and the frequencies of the plurality of frequency component inputs are arranged at predetermined frequency intervals. can do.

Further, the pilot data sequence of the receiving apparatus of the present invention can be configured to be a pseudo noise sequence.

The transmitting apparatus according to the present invention comprises: a receiving unit, a serial-to-parallel converting unit, an inserting unit, an inverse Fourier transform unit, a transmitting unit,
It comprises so that it may be provided.

The receiving section receives a digital signal.

The serial-to-parallel converter outputs a plurality of digital signals obtained by serial-to-parallel conversion of the received digital signals.

The inserting section inserts a known data sequence or a pilot data sequence having the same length as this in a predetermined order into each of a plurality of digital signals output after serial-to-parallel conversion. And outputs a plurality of digital signals.

The inverse Fourier transform unit receives a plurality of digital signals inserted and output as frequency component inputs other than the DC component input, receives zero data as the frequency component of the DC component input, and performs the inverse Fourier transformed digital signal. Is output.

The transmitting unit converts the digital signal output after the inverse Fourier transform into an analog signal and transmits the analog signal.

In the transmitting apparatus according to the present invention, the predetermined order may be configured such that the pilot data sequence is inserted into the known data sequence at predetermined intervals.

[0048] The receiving apparatus of the present invention comprises a receiving section, an inverse Fourier transform section, a multipath radio wave propagation characteristic acquiring section, an equalizing section, a Fourier transform section, a parallel-serial converting section, an output section,
It comprises so that it may be provided.

The receiving section receives an analog signal and converts it into a digital signal.

The inverse Fourier transform unit receives a pilot data sequence as a predetermined frequency component input, receives zero data as other frequency component inputs, and outputs a digital signal subjected to inverse Fourier transform.

The multipath radio wave propagation characteristic obtaining section obtains a multipath radio wave propagation characteristic by correlating the converted digital signal with the digital signal output after inverse Fourier transform.

The equalizer outputs a digital signal obtained by equalizing the converted digital signal based on the acquired multipath radio wave propagation characteristics.

The Fourier transform unit outputs a plurality of digital signals obtained by Fourier transforming the equalized digital signal.

The parallel-to-serial conversion unit outputs a single digital signal obtained by performing parallel-to-serial conversion on a plurality of digital signals output by Fourier transform.

The output section outputs a single digital signal which has been converted from parallel to serial and output.

In the receiving apparatus of the present invention, the predetermined order is
It can be configured such that the pilot data sequence is inserted in the known data sequence at predetermined intervals.

The transmitting method of the present invention includes a receiving step, a serial / parallel converting step, an inserting step, an inverse Fourier transform step, and a transmitting step.

In the receiving step, a digital signal is received.

In the serial / parallel conversion step, a plurality of digital signals obtained by serially / parallel-converting the received digital signals are output.

In the inserting step, a plurality of digital signals in which a known data sequence is inserted every predetermined number of symbols are output to each of the plurality of digital signals output after serial-to-parallel conversion.

In the inverse Fourier transform step, a plurality of digital signals inserted and output as frequency component inputs other than the DC component input and a pilot data sequence are received, and zero data is received as the frequency component of the DC component input. Outputs a digital signal subjected to inverse Fourier transform.

In the transmitting step, the digital signal output after the inverse Fourier transform is converted into an analog signal and transmitted.

In the inverse Fourier transform step of the transmission method of the present invention, the pilot data sequence is received as a plurality of frequency component inputs, and the frequencies of the plurality of frequency component inputs are arranged at predetermined frequency intervals. can do.

The pilot data sequence of the transmission method of the present invention can be configured to be a pseudo noise sequence.

The receiving method according to the present invention includes a receiving step, an inverse Fourier transform step, a multipath radio wave propagation characteristic acquiring step,
It is configured to include an equalizing step, a Fourier transforming step, a parallel-serial converting step, and an output step.

In the receiving step, an analog signal is received and converted into a digital signal.

In the inverse Fourier transform step, a pilot data sequence is received as a predetermined frequency component input, zero data is received as the other frequency component inputs, and a digital signal subjected to the inverse Fourier transform is output.

In the multipath radio wave propagation characteristic obtaining step, a multipath radio wave propagation characteristic is obtained by correlating the converted digital signal with the digital signal output after inverse Fourier transform.

In the equalizing step, a digital signal obtained by equalizing the converted digital signal based on the obtained multipath radio wave propagation characteristics is output.

In the Fourier transform step, a plurality of digital signals obtained by Fourier transforming the equalized digital signal are output.

In the parallel-to-serial conversion step, a single digital signal obtained by performing parallel-to-serial conversion on a plurality of digital signals output by Fourier transform is output.

In the output step, a single signal output after being subjected to parallel-to-serial conversion is output.

In the inverse Fourier transform step of the receiving method of the present invention, the pilot data sequence is received as a plurality of frequency component inputs, and the frequencies of the plurality of frequency component inputs are arranged at predetermined frequency intervals. can do.

Further, the pilot data sequence of the receiving method of the present invention can be configured to be a pseudo noise sequence.

The transmitting method of the present invention is configured to include a receiving step, a serial / parallel converting step, an inserting step, an inverse Fourier transform step, and a transmitting step.

In the receiving step, a digital signal is received.

In the serial-to-parallel conversion step, a plurality of digital signals obtained by serial-to-parallel conversion of the received digital signal are output.

In the inserting step, a known data sequence or a pilot data sequence of the same length as this is inserted in a predetermined order for each of a plurality of digital signals output after serial-to-parallel conversion. And outputs a plurality of digital signals.

In the inverse Fourier transform step, a plurality of digital signals inserted and output as frequency component inputs other than the DC component input are received, and zero data is received as the frequency component of the DC component input, and the inverse Fourier transformed digital signal is received. Is output.

In the transmitting step, the digital signal output after the inverse Fourier transform is converted into an analog signal and transmitted.

Further, in the transmission method of the present invention, the predetermined order may be such that the pilot data sequence is inserted at predetermined intervals with respect to the known data sequence.

The receiving method according to the present invention includes a receiving step, an inverse Fourier transform step, a multipath radio wave propagation characteristic acquiring step,
It is configured to include an equalizing step, a Fourier transforming step, a parallel-serial converting step, and an output step.

In the receiving step, an analog signal is received and converted into a digital signal.

In the inverse Fourier transform step, a pilot data sequence is received as a predetermined frequency component input, zero data is received as other frequency component inputs, and a digital signal subjected to inverse Fourier transform is output.

In the multipath radio wave propagation characteristic obtaining step, a multipath radio wave propagation characteristic is obtained by correlating the converted digital signal with the digital signal output after inverse Fourier transform.

In the equalizing step, a digital signal obtained by equalizing the converted digital signal based on the obtained multipath radio wave propagation characteristics is output.

In the Fourier transform step, a plurality of digital signals obtained by Fourier transforming the equalized digital signal are output.

In the parallel-to-serial conversion step, a single digital signal obtained by performing parallel-to-serial conversion on a plurality of digital signals output by Fourier transform is output.

In the output step, a single digital signal output after being converted from parallel to serial is output.

Further, in the receiving method of the present invention, the predetermined order may be configured such that the pilot data sequence is inserted at predetermined intervals with respect to the known data sequence.

The communication system, the transmitting device, the receiving device, the transmitting method, and the program for realizing the receiving method of the present invention are stored in a compact disk, floppy disk, hard disk, magneto-optical disk, digital video disk,
It can be recorded on a computer-readable information recording medium such as a magnetic tape or a semiconductor memory.

A program recorded on the information recording medium of the present invention can be stored in a general-purpose computer having a storage device, a computing device, an output device, a communication device, etc., a mobile phone, a PHS device,
The transmission device, the reception device, the transmission method, and the reception method described above are realized by being executed by a portable terminal such as a game device or an information processing device such as a parallel computer and functioning as a transmission device or a reception device. Can be.

In particular, the DSP of the software radio terminal
(Digital Signal Processor) and FPGA (Field Pr
The transmission device, the reception device, the transmission method, and the reception method described above can be realized by causing an (ogrammable gate array) unit to execute the program recorded on the information recording medium of the present invention.

Further, independently of the information processing apparatus, an information recording medium on which the program of the present invention is recorded can be distributed and sold.

[0095]

DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below. The embodiments described below are for explanation, and do not limit the scope of the present invention. Therefore, those skilled in the art can adopt embodiments in which each of these elements or all elements are replaced with equivalents, but these embodiments are also included in the scope of the present invention.

In the following description, in order to facilitate understanding, when the same processing is performed for both the I channel and the Q channel according to the custom in the art, only one channel is appropriately illustrated.

(First Embodiment) FIG. 1 is a schematic diagram showing a schematic configuration of an OFDM communication system, which has the same general configuration as the first embodiment of the communication system of the present invention. Therefore, description will be made with reference to FIG.

The communication system 101 includes a transmitting device 102
And a receiving device 103. The transmitting device 102
It receives a digital signal, performs predetermined processing on the digital signal, and transmits an analog signal. The receiving device 103 receives the analog signal transmitted by the transmitting device 102 and performs a predetermined process on the analog signal to obtain a digital signal.

[0099] Multipath fading may occur between the transmitting apparatus 102 and the receiving apparatus 103.
Of the signals transmitted from the transmitting device 102, the signal that arrives at the receiving device 103 first is called the preceding wave, and the signal that arrives at the receiving device 103 after being delayed due to being reflected by a building or the ionosphere in the middle of the signal. It is called a delayed wave.

(First Embodiment of Transmitting Apparatus) FIG.
FIG. 2 is a schematic diagram illustrating a schematic configuration of a transmission device 102 of the communication system 101 illustrated in FIG. 1. Hereinafter, description will be made with reference to FIG.

The transmitting apparatus 102 includes a receiving unit 201, a serial / parallel converting unit 202, an inserting unit 203, an inverse Fourier transform unit 204, and a transmitting unit 205. Reception unit 201
Receives a digital signal to be transmitted. A digital signal is represented by a sequence of symbols.

The serial-to-parallel converter 202 converts the digital signal received by the receiver 201 into N digital signals.

The inserting section 203 inserts a known data sequence (the number of symbols Y) into each of the N digital signals every predetermined number of symbols X, and
Output digital signals. This known data sequence is shared with the receiving device 103.

The inverse Fourier transform unit 204 has a plurality of input channels. The pilot data sequence and the N digital signals output by insertion section 203 are provided to this input channel. This pilot data sequence is shared with receiving apparatus 103.

The input channels are respectively assigned to predetermined frequency component inputs that are integral multiples of the fundamental frequency. For each frequency component input, two (I channel and Q channel) of a real number input and an imaginary number input are used. There is. Also, a frequency component input of 0 times the fundamental frequency is called a DC component input.

FIG. 3 is an explanatory diagram showing an embodiment of a data frame for providing a pilot data sequence and N digital signals output by the inserting section 203 to each of the input channels. This figure shows a data frame diagram for one of the I channel and the Q channel in accordance with a general notation in the art.

The pilot data sequence includes the first I channel and Q channel, and the (p + 1) th I channel and Q channel.
Channels, 2p + 1th I channel and Q channel, 3p + 1th I channel and Q channel,. Therefore, the signals input to these channels are the same pilot data sequence.

Each of the N digital signals can be divided into a data portion having the number of symbols X and a known data sequence portion having the number of symbols Y. The data part of the symbol number X is the part output by the serial / parallel conversion unit 202. The known data sequence part with the number of symbols Y is the part inserted by the insertion unit 203. The known data sequence section is arranged so as to sandwich the data section. Therefore, the length of one frame is (X + 2 × Y) symbols.

These N digital signals are as follows: the second to p-th I and Q channels; the p + 2 to 2p-th I and Q channels; the 2p + 2 to 3p-th I and Q channels; Then, the pilot data sequence is input to a channel other than the input channel. Therefore, the signals input to these channels are N different digital signals, and different digital signals are input even to the same I channel and Q channel. p
Is called “pilot insertion carrier interval”.

However, DC component input I channel and Q channel
A value 0 is input to the channel. That is, zero data is input. As described above, by inputting zero data to the DC component input, the influence of the fluctuation of the electric circuit is reduced.

Thus, the number of channels (the total number of I and Q channels) used as the input of the inverse Fourier transform is approximately 2N + (N /
2p) × 2 + 2 = L. The total number of carriers is L / 2.

In the example shown in FIG. 3, the number of channels of each of the I channel and the Q channel is 3p, the number of digital signals is N = 3p-4, and the DC component is arranged between channel numbers p + 2 and 2p. ing. Hereinafter, a similar example will be described using a data frame as an example.

The inverse Fourier transform unit 204 performs an inverse Fourier transform on the signal input to each channel, and outputs a digital signal.

The transmitting section 205 is composed of an inverse Fourier transform section 204
Is converted into an analog signal and transmitted to a receiving device via an antenna or the like.

As described above, the result of the inverse Fourier transform is actually a complex digital signal, which is converted into an analog signal using, for example, a quadrature modulator and an analog-digital converter.

(First Embodiment of Receiving Apparatus) FIG.
FIG. 2 is a schematic diagram illustrating a schematic configuration of a receiving device 103 of the communication system 101 illustrated in FIG. 1. Hereinafter, description will be made with reference to FIG.

The receiving apparatus 103 includes a receiving section 401, an inverse Fourier transform section 402, a multipath radio wave propagation characteristic acquiring section 403, an equalizing section 404, a Fourier transform section 405,
A parallel-serial conversion unit 406 and an output unit 407 are provided.

Receiving section 401 receives the analog signal transmitted from transmitting apparatus 102, separates the analog signal into an I channel and a Q channel using a quadrature demodulator or the like, samples these at predetermined intervals, and converts the signals into digital signals. Convert.
The sampling interval is T / (L / 2) = 2T / L or more, where T is the time required for the inverse Fourier transform unit 204 of the transmitting apparatus 102 to process one input symbol. Is desirable.

On the other hand, inverse Fourier transform section 402 has a plurality of input channels, similarly to inverse Fourier transform section 204 of transmitting apparatus 102.

FIG. 5 is an explanatory diagram showing a state of a data frame provided to inverse Fourier transform section 402 of receiving apparatus 103.

Of the input channels of the inverse Fourier transform unit 402, the first I channel and Q channel, p + 1
2nd + 1st I channel and Q channel
A pilot data sequence used by the transmitting apparatus 102 is input every pth channel, such as a channel and a Q channel, a 3p + 1-th I channel and a Q channel, and so on. All other input channels input zero data.

As described above, an input is given to each input channel of the inverse Fourier transform unit 402 to output a signal subjected to inverse Fourier transform. This signal is called a “correlation processing signal”.

FIG. 6 is a graph showing the appearance of the correlation processing signal.

As shown in FIG. 6, the correlation processing signal has a waveform having p peaks in one symbol length for both the I channel and the Q channel.

The multipath radio wave propagation characteristic acquisition unit 403
The digital signal (sum of the preceding wave and the delayed wave) received and converted by the receiving unit 401 is slid with a correlation processing signal to obtain a correlation. FIG. 7 shows a case where the correlation between the received signal and the correlation processing signal is obtained by sliding.
FIG. 4 is an explanatory diagram showing an output of one of the I channel and the Q channel.

As shown in FIG. 7, the time delay between the preceding wave and the delayed wave can be determined from the large peak component and the small peak component resulting from the correlation. Also, the ratio of the amplitude of the large peak component to the amplitude of the small peak component is found from the result of the sliding correlation. The phase difference between the preceding wave and the delayed wave is also found from the ratio between the time delay and the amplitude.

By performing such processing for both the I channel and the Q channel, it is possible to estimate the multipath radio wave propagation characteristics, that is, changes in delay time and amplitude of delayed waves, and changes in phase. The multipath radio wave propagation characteristic acquisition unit 403 estimates these values.

The equalizer 404 equalizes the digital signal (sum of the preceding wave and the delayed wave) received and converted by the receiver 401 based on the estimated multipath radio wave propagation characteristics. Since signals can be synchronized by the multipath radio propagation characteristic acquisition unit 403, the reception unit 40
It is known which part of the digital signal (sum of the preceding wave and the delayed wave) received and converted by 1 is a part corresponding to the known data sequence.

FIG. 8 is an explanatory diagram showing the relationship between the preceding wave, the delayed wave, and the equalization of the digital signal received and converted by the receiving unit 401. FIG. 8 shows an equalization method when the peak corresponding to the preceding wave is larger than the peak corresponding to the delayed wave.

The following equalization is performed for each of the I channel and the Q channel of the digital signal (sum of the preceding wave and the delayed wave) received and converted by the receiving unit 401.

First, the known data sequence is subjected to an inverse Fourier transform, and this is combined with the variation of the delay time, amplitude, and phase of the delay wave obtained by the multipath radio wave propagation characteristic acquisition unit 403 to obtain the first part in the delay wave. Make a replica of (the part corresponding to the known data series).

When this replica is subtracted from the received signal as shown in FIG. 8, equalized data is obtained. However, from the portion of the preceding wave that does not correspond to the known data sequence, the portion of the delayed wave within the known data sequence can be obtained. From where the part is subtracted, a replica of the delayed wave can be further created.

As described above, equalization is performed by repeatedly making a replica and subtracting it from the received signal. For such an equalization method, the inventors have described "P
OFDM mobile radio transmission system using channel estimation and pre-equalization using N sequence "(Muramatsu, Harada, 1998
IEICE Communications Society Conference, B-5-1
3).

If the peak of the preceding wave is smaller than the peak of the delayed wave, equalization may be performed in the opposite direction. To enable this, the insertion unit 203 of the transmitting device 102
Are arranged so as to sandwich the known data series.

The Fourier transform section 405 performs a Fourier transform on the signal output after being equalized by the equalizing section 404, and outputs a plurality of digital signals. Parallel / serial converter 406
Removes a portion corresponding to a known data sequence from a plurality of digital signals that are not pilot data sequences, performs parallel-to-serial conversion, and demodulates a digital signal to be transmitted.

Output section 407 outputs a demodulated digital signal.

(Second Embodiment) This embodiment is almost the same as the above embodiment. Therefore, in the following description, the same reference numerals are used as in the above-described embodiment. The difference is in the format of the data frame employed. In addition, a guard interval is further provided in accordance with this.

FIG. 9 shows the format of a data frame employed in transmitting apparatus 102.

The known data sequence and the pilot data sequence have the same length Y, and the pilot data sequence is arranged at a predetermined interval p between the known data sequences. The pilot data sequence / known data sequence arranged as described above is arranged so as to be interposed between each of the plurality of signals converted by the serial / parallel conversion unit 202 for every X symbol.
Therefore, the length of one frame is (X + Y × 2) symbols.

In the example of the data frame shown in FIG. 9, the number of channels is 3p. On the other hand, the number of data parts is 1-3p
The number is different from that of the first embodiment. The DC component is disposed between the p + 2 channel and the 2p channel.

The transmitting section 205 of the transmitting apparatus 102 inserts a guard interval into the inverse Fourier transformed signal in the inverse Fourier transform section 204 and then converts the signal into an analog signal.
The data is transmitted to the receiving device 103.

In the present embodiment, since the correlation processing is performed only on the symbol into which the pilot data sequence has been inserted, if the guard interval is not inserted, the measurement result will be distorted due to the delay wave of the adjacent symbol. .

FIG. 10 shows the format of a data frame provided to the inverse Fourier transform unit of the receiving apparatus 103.

In this data frame, the number of symbols is Y, and the same pilot data sequence as that used in transmitting apparatus 102 is arranged at a predetermined interval p, and the other portions are set to zero data.

The parallel-to-serial conversion unit 4 of the receiving apparatus 103
Reference numeral 06 removes portions corresponding to the known data sequence and the pilot data sequence from the plurality of digital signals output from the Fourier transform unit 405, performs parallel-to-serial conversion, and demodulates the digital signal to be transmitted.

[0146]

As described above, according to the present invention,
A communication system of an orthogonal frequency division multiplexing transmission system suitable for performing stable communication by removing interference waves due to multipath, a transmission device, a reception device, a transmission method, a reception method, and a program for realizing these are recorded. An information recording medium can be provided.

[Brief description of the drawings]

FIG. 1 is a schematic diagram illustrating a schematic configuration of an embodiment of a communication system according to the present invention.

FIG. 2 is a schematic diagram showing a schematic configuration of a transmission device of the communication system shown in FIG.

FIG. 3 is an explanatory diagram showing a state of a data frame employed in the transmission device shown in FIG. 2;

FIG. 4 is a schematic diagram showing a schematic configuration of a receiving device of the communication system shown in FIG. 1;

5 is an explanatory diagram showing a state of a data frame provided to an inverse Fourier transform unit of the receiving device shown in FIG.

FIG. 6 is a graph showing a state of a correlation processing signal.

FIG. 6 is an explanatory diagram illustrating an output when a correlation is obtained by sliding a received signal and a correlation processing signal.

FIG. 8 is an explanatory diagram showing a relationship between a leading wave, a delayed wave, and equalization of a digital signal received and converted by a receiving unit 401.

FIG. 9 is an explanatory diagram illustrating a state of a data frame employed in a transmission device according to a second embodiment of the communication system.

FIG. 10 is an explanatory diagram illustrating a state of a data frame employed in a receiving device according to a second embodiment of the communication system.

[Explanation of symbols]

 Reference Signs List 101 communication system 102 transmission device 103 reception device 201 reception unit 202 serial-to-parallel conversion unit 203 insertion unit 204 inverse Fourier transform unit 205 transmission unit 401 reception unit 402 inverse Fourier transform unit 403 multipath radio propagation characteristic acquisition unit 404 equalization unit 405 Fourier Conversion unit 406 Parallel / serial conversion unit 407 Output unit

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[Procedure amendment]

[Submission Date] August 8, 2000 (200.8.8)

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Claims (36)

[Claims] 1. A transmitting device for sharing and communicating a known data sequence and a predetermined pilot data sequence, a receiving device,
A communication system comprising: (a) the transmitting device, a receiving unit that receives a digital signal, a serial-to-parallel converting unit that outputs a plurality of digital signals obtained by serial-to-parallel-converting the received digital signal; An insertion unit that outputs a plurality of digital signals into which the known data sequence is inserted every predetermined number of symbols for each of the plurality of digital signals output after being converted in parallel; and as a frequency component input other than the DC component input. An inverse Fourier transform unit that accepts the plurality of inserted and output digital signals and the pilot data sequence, accepts zero data as a DC component input frequency component, and outputs an inverse Fourier transformed digital signal, The digital signal output by inverse Fourier transform is converted to an analog signal and (B) the receiving device receives the analog signal transmitted by the transmitting device and converts the analog signal into a digital signal; and an inverse Fourier transform unit of the transmitting device. An inverse Fourier transform unit that accepts the pilot data sequence as the same frequency component input as the frequency component input that accepted the pilot data sequence, accepts zero data as the other frequency component input, and outputs an inverse Fourier transformed digital signal A multipath radio wave propagation characteristic acquisition unit that acquires a multipath radio wave propagation characteristic by correlating the converted digital signal and the digital signal output by performing the inverse Fourier transform; Digital signal obtained by equalizing the received digital signal according to path radio wave propagation characteristics An equalizing unit that outputs, a Fourier transform unit that outputs a plurality of digital signals obtained by Fourier-transforming the digital signal output after being equalized, and a parallel-serial conversion of the plurality of digital signals that are output by performing the Fourier transform. A communication system comprising: a parallel-to-serial conversion unit that outputs a single digital signal; and an output unit that outputs a single signal that is output after the parallel-to-serial conversion. 2. The transmission apparatus according to claim 1, wherein the inverse Fourier transform unit receives the pilot data sequence as a plurality of frequency component inputs, and the frequencies of the plurality of frequency component inputs are at predetermined frequency intervals. The communication system according to claim 1, wherein: 3. The communication system according to claim 1, wherein said pilot data sequence is a pseudo noise sequence. 4. A transmitting device for sharing and communicating a known data sequence and a pilot data sequence of the same length,
A communication system comprising: a reception device; and (a) the transmission device includes: a reception unit that receives a digital signal; and a serial-to-parallel conversion unit that outputs a plurality of digital signals obtained by serial-to-parallel conversion of the received digital signal. An insertion unit that outputs a plurality of digital signals into which the known data sequence is inserted every predetermined number of symbols for each of the plurality of digital signals output after the serial-to-parallel conversion; An inverse Fourier transform unit that accepts the plurality of digital signals inserted and output as the frequency component input, receives zero data as the frequency component of the DC component input, and outputs an inverse Fourier transformed digital signal; A transmitting unit that converts the converted and output digital signal into an analog signal and transmits the analog signal; (B) a receiving unit that receives the analog signal transmitted by the transmitting device and converts it into a digital signal; and a digital signal received by the inverse Fourier transform unit of the transmitting device, An inverse Fourier transform unit that accepts the pilot data sequence as the same frequency component input as the component input, accepts zero data as the other frequency component input, and outputs an inverse Fourier transformed digital signal, and the converted digital signal A multipath radio propagation characteristic obtaining unit that obtains a multipath radio propagation characteristic by correlating the digital signal output by the inverse Fourier transform, and the converted multipath radio propagation characteristic, An equalizer for outputting a digital signal obtained by equalizing the digital signal A Fourier transform unit that outputs a plurality of digital signals obtained by Fourier-transforming the output digital signal; And an output unit for outputting the single digital signal output after the parallel-to-serial conversion. 5. The communication system according to claim 4, wherein said predetermined order is an order in which said pilot data sequence is inserted at predetermined intervals with respect to said known data sequence. 6. A receiving unit for receiving a digital signal, a serial-to-parallel converter for outputting a plurality of digital signals obtained by serial-to-parallel conversion of the received digital signal, and a plurality of digital signals output after the serial-to-parallel conversion An insertion unit for outputting a plurality of digital signals into which a known data sequence is inserted every predetermined number of symbols, and a plurality of digital signals inserted and output as frequency component inputs other than the DC component input. An inverse Fourier transform unit that accepts zero data as a frequency component of a DC component input and outputs an inverse Fourier-transformed digital signal; and converts the inverse Fourier-transformed digital signal into an analog signal. And a transmitting unit that converts the data into a data and transmits the data. 7. The inverse Fourier transform unit receives the pilot data sequence as a plurality of frequency component inputs,
The transmitting apparatus according to claim 6, wherein the frequencies of the plurality of frequency component inputs are at predetermined frequency intervals. 8. The transmitting apparatus according to claim 6, wherein said pilot data sequence is a pseudo noise sequence. 9. A receiving unit for receiving an analog signal and converting it into a digital signal, receiving a pilot data sequence as a predetermined frequency component input, receiving zero data as another frequency component input, and performing inverse Fourier transform An inverse Fourier transform unit that outputs a signal; and a multipath radio propagation characteristic obtaining unit that obtains a multipath radio propagation characteristic by correlating the converted digital signal with the digital signal output by performing the inverse Fourier transform. Unit, an equalizer that outputs a digital signal equalized from the converted digital signal according to the obtained multipath radio wave propagation characteristic, and a plurality of Fourier-transformed the equalized digital signal output. A Fourier transform unit that outputs a digital signal; and a plurality of the Fourier transform and output. A parallel-to-serial conversion unit that outputs a single digital signal obtained by parallel-to-serial conversion of a digital signal; and an output unit that outputs a single signal output after the parallel-to-serial conversion. . 10. The method according to claim 1, wherein the inverse Fourier transform unit receives the pilot data sequence as a plurality of frequency component inputs, and the frequencies of the plurality of frequency component inputs are at predetermined frequency intervals. The receiving device according to claim 9. 11. The receiving apparatus according to claim 9, wherein said pilot data sequence is a pseudo noise sequence. 12. A receiving unit for receiving a digital signal, a serial-to-parallel converter for outputting a plurality of digital signals obtained by serial-to-parallel conversion of the received digital signal, and a plurality of digital signals output after the serial-to-parallel conversion For each of a predetermined number of symbols, an insertion unit for outputting a plurality of digital signals in which a known data sequence or a pilot data sequence of the same length as this is inserted in a predetermined order, and a frequency component other than the DC component input An inverse Fourier transform unit that accepts the plurality of inserted and output digital signals as input, accepts zero data as a frequency component of a DC component input, and outputs an inverse Fourier transformed digital signal; A transmitting unit that converts the output digital signal into an analog signal and transmits the analog signal; Transmitting device, characterized in that it comprises. 13. The transmitting apparatus according to claim 12, wherein the predetermined order is an order in which the pilot data sequence is inserted at predetermined intervals with respect to the known data sequence. 14. A receiver for receiving an analog signal and converting it to a digital signal, receiving the pilot data sequence as a predetermined frequency component input, and receiving zero data as the other frequency component input, and performing an inverse Fourier transform. An inverse Fourier transform unit that outputs a digital signal; and a multipath radio propagation characteristic that obtains a multipath radio propagation characteristic by correlating the converted digital signal and the digital signal that is output after the inverse Fourier transform. An acquiring unit, an equalizing unit that outputs a digital signal obtained by equalizing the converted digital signal according to the obtained multipath radio wave propagation characteristic, and a plurality of Fourier-transformed digital signals that have been equalized and output. A Fourier transform unit that outputs a digital signal of A parallel-to-serial conversion unit that outputs a single digital signal obtained by parallel-to-serial conversion of a number of digital signals; and an output unit that outputs a single digital signal that is output after the parallel-to-serial conversion. Receiving device. 15. The receiving apparatus according to claim 14, wherein said predetermined order is an order in which said pilot data sequence is inserted at predetermined intervals with respect to said known data sequence. 16. A receiving step for receiving a digital signal, a serial-to-parallel conversion step for outputting a plurality of digital signals obtained by serial-to-parallel conversion of the received digital signal, and a plurality of digital signals output after being subjected to the serial-to-parallel conversion. An output step of outputting a plurality of digital signals into which a known data sequence is inserted every predetermined number of symbols, and a plurality of digital signals inserted and output as frequency component inputs other than the DC component input. An inverse Fourier transforming step of accepting zero data as a frequency component of the DC component input and outputting an inverse Fourier transformed digital signal; and And a transmitting step of converting and transmitting Transmission method that. 17. The method according to claim 17, wherein the inverse Fourier transforming step receives the pilot data sequence as a plurality of frequency component inputs, and the frequencies of the plurality of frequency component inputs are at predetermined frequency intervals. The transmission method according to item 16, 18. The transmission method according to claim 16, wherein said pilot data sequence is a pseudo noise sequence. 19. A receiving step of receiving an analog signal and converting it to a digital signal, receiving a pilot data sequence as a predetermined frequency component input, receiving zero data as the other frequency component input, and performing inverse Fourier transform on the digital signal. An inverse Fourier transform step of outputting a signal; obtaining a multipath radio propagation characteristic by obtaining a correlation between the converted digital signal and the digital signal output after the inverse Fourier transform. And an equalizing step of outputting a digital signal obtained by equalizing the converted digital signal according to the obtained multipath radio wave propagation characteristic; and a plurality of Fourier transforms of the equalized and output digital signal. A Fourier transform step of outputting a digital signal; and outputting the Fourier transform. And a parallel-to-serial conversion step of outputting a single digital signal obtained by parallel-to-serial conversion of a plurality of obtained digital signals; and an output step of outputting a single signal output after the parallel-to-serial conversion. And the receiving method. 20. The inverse Fourier transforming step, wherein the pilot data sequence is received as a plurality of frequency component inputs, and the frequencies of the plurality of frequency component inputs are at predetermined frequency intervals. 20. The receiving method according to 19. 21. The receiving method according to claim 19, wherein said pilot data sequence is a pseudo noise sequence. 22. A receiving step of receiving a digital signal, a serial-to-parallel conversion step of outputting a plurality of digital signals obtained by serial-to-parallel conversion of the received digital signal, and a plurality of digital signals output after being subjected to the serial-to-parallel conversion. An output step of outputting a plurality of digital signals in which a known data sequence or a pilot data sequence of the same length as this is inserted in a predetermined order for each of a predetermined number of symbols, and frequency components other than the DC component input. An inverse Fourier transforming step of accepting the plurality of digital signals inserted and output as input, accepting zero data as a frequency component of the DC component input, and outputting an inverse Fourier transformed digital signal; Transmission that converts the output digital signal to an analog signal and sends it A transmission method, comprising: 23. The transmission method according to claim 22, wherein said predetermined order is an order in which said pilot data sequence is inserted at predetermined intervals with respect to said known data sequence. 24. A receiving step of receiving an analog signal and converting it into a digital signal, receiving a pilot data sequence as a predetermined frequency component input, receiving zero data as the other frequency component input, and performing inverse Fourier transform on the digital signal. An inverse Fourier transform step of outputting a signal; obtaining a multipath radio propagation characteristic by obtaining a correlation between the converted digital signal and the digital signal output after the inverse Fourier transform. And an equalizing step of outputting a digital signal obtained by equalizing the converted digital signal according to the obtained multipath radio wave propagation characteristic; and a plurality of Fourier transforms of the equalized and output digital signal. A Fourier transform step of outputting a digital signal; and outputting the Fourier transform. A parallel-to-serial conversion step of outputting a single digital signal obtained by parallel-to-serial conversion of a plurality of obtained digital signals, and an output step of outputting a single digital signal that has been subjected to the parallel-to-serial conversion and output. Characteristic receiving method. 25. The receiving method according to claim 24, wherein said predetermined order is an order in which said pilot data sequence is inserted at predetermined intervals with respect to said known data sequence. 26. A program executed by a transmission device, the program receiving a digital signal, outputting a plurality of digital signals obtained by serial-to-parallel conversion of the received digital signal, and outputting the digital signal after the serial-to-parallel conversion. For each of the plurality of digital signals, a plurality of digital signals in which a known data sequence is inserted every predetermined number of symbols are output, and the plurality of digital signals inserted and output as frequency component inputs other than the DC component input are output. And a pilot data sequence, accepting zero data as a frequency component of the DC component input, outputting an inverse Fourier transformed analog signal, and converting the inverse Fourier transformed and output analog signal into a digital signal. A computer recording a program characterized by realizing a transmission process. Information readable medium. 27. In order to output the analog signal subjected to the inverse Fourier transform, the pilot data sequence is received as a plurality of frequency component inputs, and the frequencies of the plurality of frequency component inputs are at predetermined frequency intervals. The information recording medium according to claim 26, wherein: 28. The information recording medium according to claim 26, wherein said pilot data sequence is a pseudo noise sequence. 29. A program executed by a receiving apparatus, comprising: receiving an analog signal, converting the signal into a digital signal, receiving a pilot data sequence as a predetermined frequency component input, and zero data as other frequency component inputs. Receiving the inverse Fourier-transformed digital signal, obtaining a multipath radio wave propagation characteristic by correlating the converted digital signal and the inverse Fourier-transformed digital signal, Outputting a digital signal obtained by equalizing the converted digital signal according to the obtained multipath radio wave propagation characteristics, outputting a plurality of digital signals obtained by performing a Fourier transform on the equalized and output digital signal; A single digital-to-parallel converter of multiple digital signals converted and output Outputs a signal, the parallel to serial converted by recording a program, characterized in that to realize the process of outputting a single signal output computer readable information recording medium. 30. In order to output the inverse Fourier-transformed digital signal, the pilot data sequence is received as a plurality of frequency component inputs, and the frequencies of the plurality of frequency component inputs are at predetermined frequency intervals. 30. The information recording medium according to claim 29, wherein: 31. The information recording medium according to claim 29, wherein said pilot data sequence is a pseudo noise sequence. 32. A program executed by a transmission device, comprising: receiving a digital signal; outputting a plurality of digital signals obtained by serial-to-parallel conversion of the received digital signal; For each of the plurality of digital signals, a known data sequence or a pilot data sequence of the same length is inserted in a predetermined order for every predetermined number of symbols, and a plurality of digital signals are output. A plurality of digital signals inserted and output as the component input are received, zero data is received as a frequency component of the DC component input, and a digital signal subjected to inverse Fourier transform is output. The feature is to realize the process of converting the signal to an analog signal and transmitting it. Information recording medium for recording a program that. 33. The information recording medium according to claim 32, wherein the predetermined order is an order in which the pilot data sequence is inserted at predetermined intervals with respect to the known data sequence. 34. A program executed by a receiving apparatus, comprising: receiving an analog signal and converting it into a digital signal; receiving a pilot data sequence as a predetermined frequency component input; Receiving the inverse Fourier-transformed digital signal, obtaining a multipath radio wave propagation characteristic by correlating the converted digital signal and the inverse Fourier-transformed digital signal, Outputting a digital signal obtained by equalizing the converted digital signal according to the obtained multipath radio wave propagation characteristics, outputting a plurality of digital signals obtained by performing a Fourier transform on the equalized and output digital signal; A single digital-to-parallel converter of multiple digital signals converted and output Outputs a signal, the parallel serial conversion has been outputted single computer recording a program, characterized in that to realize the process of outputting a digital signal readable information recording medium. 35. The information recording medium according to claim 34, wherein the predetermined order is an order in which the pilot data sequence is inserted at predetermined intervals with respect to the known data sequence. 36. The information according to claim 26, wherein the information recording medium is a compact disk, a floppy disk, a hard disk, a magneto-optical disk, a digital video disk, a magnetic tape, or a semiconductor memory. recoding media.