JP2016082340A - Data receiver, program, and integrated circuit - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a data receiver capable of appropriately executing transmission channel characteristic estimation processing, even when an RI period of a time length equal to a synchronization OFDM symbol SYNCP, is provided, and capable of appropriately executing transmission channel characteristic estimation processing even when a delay amount of a reflection wave is large.SOLUTION: A signal Dp1 corresponding to an OFDM symbol output from an FE part 1 of a data receiver 100 is processed by a system of a preamble FFT part 3 to a buffer part 9. In the processing system, time domain signal adjustment processing is performed by converting the signal into a time domain, and phase adjustment processing is performed in a frequency domain. A transmission characteristic correction part 10 performs transmission characteristic correction processing for a signal output by a payload FFT part 2 using the processing result of the system of the preamble FFT part 3 to the buffer part 9.SELECTED DRAWING: Figure 3A

Description

  The present invention relates to a technique for estimating a transmission path using a pilot signal and performing equalization processing.

  In a communication system, a pilot signal (known signal) and a data signal are transmitted, and on the receiving side, a transmission path is estimated using the pilot signal, and the obtained transmission path information is applied to a signal other than the pilot signal. There is a technique for performing the conversion processing (see, for example, Patent Document 1).

  For example, consider the case of transmitting the transmission signal shown in FIG. 1 in the communication system 9000 shown in FIG.

  FIG. 1 is a diagram showing an extracted part of a transmission signal. As shown in FIG. 1, the transmission signal includes a preamble and a payload.

  As shown in FIG. 1, the preamble includes M (M: natural number, for example, M = 10) synchronization OFDM (Orthogonal Frequency Division Multiplexing) symbols SYNCP. One synchronization OFDM symbol SYNCP includes N (N: natural number) samples (data). Note that the M synchronization OFDM symbols SYNCP are the same.

  As shown in FIG. 1, the payload includes a guard interval GI and an OFDM symbol Data for data. The guard interval GI includes, for example, 1.5 × N samples. Note that 1.5 × N is preferably an integer. The guard interval GI and the data OFDM symbol Data are referred to as “data extended OFDM symbol”.

  The OFDM symbol Data for data includes L × N (L: natural number, for example, L = 8) samples. In the following description, for convenience of explanation, it is assumed that L = 8.

  FIG. 10 is a diagram showing a schematic configuration of a conventional communication system 9000. The communication system 9000 is a communication system that performs data communication using an OFDM modulation scheme. As illustrated in FIG. 10, the communication system 9000 includes a data transmission device Tx1 and a data reception device 900.

  First, processing in the data transmission device Tx1 will be described.

  For example, the data transmission device Tx1 modulates data by PSK (Phase Shift Keying) or QAM (Quadrature Amplitude Modulation) to acquire a transmission data sequence. Then, the data transmission device Tx1 performs serial / parallel conversion on the acquired transmission data series, and further performs inverse discrete Fourier transform processing.

  Specifically, the data transmission device Tx1 performs the inverse discrete Fourier transform process on the OFDM symbol SYNCP acquired by performing the inverse discrete Fourier transform process on certain known data (known pattern) and the data to be transmitted. A transmission frame as shown in FIG. 1 is formed and transmitted from the OFDM symbol Data acquired by performing the processing. In FIG. 1, an OFDM symbol called frame control is inserted between the preamble and the payload.

  The data transmission device Tx1 transmits the signal acquired as described above to the data reception device 900 via a transmission medium (for example, a power line).

  In the following, a case where data communication is performed using a transmission medium as a power line will be described. In FIG. 10, the data transmission device Tx1 and the data reception device 900 are connected to the power line PL and perform data communication via the power line PL.

  For convenience of explanation, as shown in FIG. 10, among the OFDM signals output from the data transmission device Tx1, (1) the signal of the payload portion is denoted as signal D0, and the notation of the signal D0 as a discrete time signal is denoted by d. (N), (2) a signal corresponding to the synchronization OFDM symbol SYNCP is represented as a signal Dp0, and a representation of the signal Dp0 as a discrete time signal is represented by p (n).

  Next, processing in the data receiving apparatus 900 will be described.

  As shown in FIG. 10, the data receiving apparatus 900 includes an FE unit (front end unit) 91, a synchronization detection unit 91A, a payload FFT unit 92, a preamble FFT unit 93, a first division unit 94, An LPF unit 95, an interpolation unit 96, a buffer unit 97, a second division unit 98, and a demodulation unit 99 are provided.

  In the data receiving apparatus 900, the FE unit 91 receives the OFDM signal transmitted from the data transmitting apparatus Tx1. The synchronization detection unit 91A performs synchronization detection processing on the received preamble of the OFDM signal and performs symbol synchronization and the like.

  The preamble FFT unit 93 receives a preamble signal Dp91 of the received OFDM signal. The preamble FFT unit 93 cuts out N samples at a predetermined timing based on the synchronization timing, performs an FFT calculation process on the N samples, and acquires a signal Dp92.

When an impulse response indicating the transmission characteristics of the communication system 9000 is expressed as h (n), the signal Dp91 is
Dp91 = p (n) * h (n)
It can be expressed as Note that “*” indicates an operator that performs a convolution operation (convolution integration operation) (hereinafter the same).

Further, if a signal obtained by Fourier transforming p (n) is P (k) and h (n) is Fourier transformed by the preamble FFT unit 93 and a signal obtained by Hp (k) is expressed as Hp (k), the signal Dp92 is
Dp92 = P (k) × Hp (k)
It can be expressed as

  The preamble FFT unit 93 outputs the signal Dp92 (= P (k) × Hp (k)) acquired as described above to the first division unit 94.

The first division unit 94 converts the signal Dp92 (= P (k) × Hp (k)) output from the preamble FFT unit 93 into a synchronization pattern P (k) (synchronization OFDM symbol SYNCP) that is a known pattern. The process of dividing by the known pattern included) is executed. That is, the first division unit 94
Dp93 = Dp92 / P (k)
= (P (k) × Hp (k)) / P (k)
= Hp (k)
The signal Dp93 (= Hp (k)) is acquired.

  It is assumed that the data receiving device 900 has acquired the synchronization pattern P (k) in advance.

  The first division unit 94 outputs the acquired signal Dp93 (= Hp (k)) to the LPF unit 95.

  The LPF unit 95 performs LPF processing on the signal Dp93 (= Hp (k)) output from the first division unit 94 and suppresses noise components outside the band. Then, the LPF unit 95 outputs the signal after LPF processing to the interpolation unit 96 as a signal Dp94. The signal Dp94 is expressed as Hp1 (k).

  The interpolation unit 96 performs an interpolation process on the signal Dp94 (= Hp1 (k)) output from the LPF unit 95 so that the sample point (the number of discrete data) is eight times. The processed signal is acquired as Dp95. The signal Dp95 is expressed as Hp2 (k).

  The interpolation unit 96 outputs the acquired signal Dp95 to the buffer unit 97.

  The buffer unit 97 stores the signal Dp95 (= Hp2 (k)) output from the interpolation unit 96, and can divide the signal D92 by the signal Dp96 at a predetermined timing (the second division unit 98). (Timing) and output to the second division unit 98 as the signal Dp96. The signal Dp96 is expressed as Hp3 (k).

  After receiving the preamble signal, the FE unit 91 receives the payload signal.

  The payload FFT unit 92 cuts out 8 × N sample OFDM symbols in the extended OFDM symbol for data at a predetermined timing based on the synchronization timing, and performs FFT calculation processing on the 8 × N samples. To obtain the signal D92.

When an impulse response indicating the transmission characteristics of the communication system 9000 is expressed as h (n), the signal D91 is
D91 = d (n) * h (n)
It can be expressed as Note that “*” indicates an operator that performs a convolution operation (convolution integration operation).

Further, if a signal obtained by Fourier transforming d (n) is D (k) and h (n) is Fourier transformed by the payload FFT unit 92 and a signal obtained by Hd (k) is expressed as Hd (k), the signal D92 is
D92 = D (k) × Hd (k)
It can be expressed as

  The payload FFT unit 92 outputs the signal D92 (= D (k) × Hd (k)) acquired as described above to the second division unit 98.

The second division unit 98 uses the signal D92 (8 × N sample signal D92) output from the payload FFT unit 92 and the signal Dp96 (8 × N sample signal Dp96) output from the buffer unit 97. ), The division process is performed to obtain the signal D93. That is, the second division unit 98
D93 = D92 / Dp96
= D (k) × Hd (k) / H3 (k)
The signal D93 is acquired by executing the processing corresponding to.

  Specifically, the second division unit 98 performs a process of dividing 8 × N samples (data) of the signal D92 by 8 × N samples (data) of the signal Dp96, and outputs the signal D93. get.

  The second division unit 98 outputs the acquired signal D93 (= D (k) × Hd (k) / Hp3 (k)) to the demodulation unit 99.

  The demodulator 99 corresponds to the demodulation process (modulation process of the data transmission device Tx) for the signal D93 (= D (k) × Hd (k) / Hp3 (k)) output from the second divider 98. Demodulation processing (for example, PSK demodulation processing, QAM demodulation processing) is performed to obtain the signal Dout.

  As described above, the data receiving apparatus 900 estimates the transmission line characteristics (the transmission line transfer function is determined using the synchronization pattern (known pattern included in the synchronization OFDM symbol SYNCP)) in which the signal pattern is known in advance. The signal D93 is acquired by correcting the signal D92 based on the acquired transmission path characteristics (acquired transmission path transfer function).

  In the data receiving apparatus 900, even if the number of samples (N) of the synchronization pattern is different from the number of samples of the OFDM symbol for payload (L × N), the transmission path transfer function Hp estimated from the synchronization pattern By interpolating (k) L times, the transmission path transfer function Hp3 (k) matched with the number of OFDM symbol samples for payload (L × N) can be obtained. That is, in the data receiving apparatus 900, even when the number of synchronization pattern samples (N) is different from the number of payload OFDM symbol samples (L × N), transmission path estimation processing is performed appropriately. be able to.

  In the data receiving apparatus 900, if the above-described payload transmission path transfer function Hd (k) and the transmission path transfer function Hp3 (k) estimated from the synchronization pattern are the same, Hd (k) / The value of Hp3 (k) is “1”. In this case, the signal D93 has the same value as D (k).

  Therefore, in the data receiving device 900, when Hd (k) and Hp3 (k) are equal to each other, the signal D93 becomes a signal equal to D (k), and demodulation processing is performed on the signal D93. The demodulated data Dout that is the same as the transmitted data can be acquired.

JP 2009-141514 A

  However, the transmission line characteristic estimation process in the data receiving apparatus 900 described above is a process under ideal conditions, and the actual process has the following problems.

  First, the first problem will be described.

  In the data receiving apparatus 900, since an error in symbol synchronization processing is unavoidable, it is difficult to accurately specify the cut-out position of the payload OFDM symbol. Even if a symbol synchronization processing error has occurred, in order not to shift the position of the OFDM symbol for the payload, that is, the position of the FFT window for the OFDM symbol for the payload, to an adjacent symbol in advance. It is necessary to shift the FFT window for the payload OFDM symbol within the guard interval GI.

  FIG. 11 is a diagram showing a signal including a preamble and a payload, as in FIG. 1, and is a diagram clearly showing the position of the FFT window when received by the data receiving device 900.

  In FIG. 11, an FFT window FFTw1 indicates the position of the FFT window for the synchronization OFDM symbol SYNCP, and an FFT window FFTw2 indicates the position of the FFT window for the data OFDM symbol Data.

  In FIG. 11, the FFT window FFTw1 for the synchronization OFDM symbol SYNCP (hereinafter referred to as “SYNCF FFT window w1”) is shifted forward by a shift amount δ. Also, in FIG. 11, the FFT window w2 for the data OFDM symbol Data (hereinafter referred to as “Data FFT window w2”) is also shifted forward by the shift amount δ.

  A transmission path transfer function is acquired from samples (N samples) of the OFDM symbol SYNCP for synchronization, and a transmission path estimation process is executed on the sample of the OFDM symbol Data for data using the acquired transmission path transfer function. For this purpose, the shift amount of the FFT window FFTw1 for SYNCP and the shift amount of the FFT window FFTw2 for Data must be equal because of the time shift of Fourier transform.

  Furthermore, in the FFT process for the samples of the OFDM symbol SYNCP for synchronization, the FFT process is performed for N samples, and therefore the shift amount of the FFT window FFTw1 for SYNCP is equivalent to N / 2, which is the Nyquist value. Is greater than the time to transmit (N / 2 samples are transmitted (half the time to transmit one synchronization OFDM symbol SYNCP)), and is obtained by the FFT processing by the preamble FFT unit 93. The signal is not correct.

  Therefore, in the transmission path characteristic estimation process in the data receiving apparatus 900 described above, (1) the shift amount of the SYNCP FFT window FFTw1 is made equal to the shift amount of the Data FFT window FFTw2, and (2) The shift amount of the FFT window FFTw1 for SYNCP and the FFT window FFTw2 for Data is set to a time corresponding to the Nyquist value N / 2 (time when N / 2 samples are transmitted (one OFDM symbol SYNCP for transmission is transmitted). There is a restriction that it must be less than half the time spent))).

  Next, the second problem will be described.

  In FIG. 11, a diagram clearly showing the RI period is added to the diagram showing the transmission signal.

  As shown in FIG. 11, when data is actually transmitted, it is necessary to provide an RI period, which is a period during which a roll-off filter is applied, between extended OFDM symbols for data. When this RI period is larger than the shift amount δ of the FFT window for data FFTw2, FFT processing (FFT processing by the FFT unit 92 for payload) is performed on the sample (sample including the GI portion) cut out by the FFT window FFTw2. ) Does not get correct data. That is, since the RI section is a section in which signal waveforms are superimposed on adjacent symbols (adjacent extended OFDM symbols) in order to ensure phase continuity between adjacent symbols, the RI section includes the RI section, Even if FFT processing is performed, a correct signal cannot be acquired.

  That is, there is a problem that it is necessary to prevent FFTw2 from entering the RI section.

  Next, the third problem will be described.

  FIG. 12 is a diagram illustrating a signal including a preamble and a payload, as in FIG. 1. The main wave and the reflected wave received by the data reception device 900 (delayed by a time t 1 with respect to the main wave). (Received signal).

  In addition, FIG. 12 shows a SYNCP FFT window FFTw1 and a Data FFT window FFTw2 as in FIG.

  For convenience of explanation, the shift amount of the data FFT window FFTw2 in the GI in the GI is δ, the shift amount of the SYNCP FFT window FFTw1 is also δ, and the delay time of the reflected wave with respect to the main wave is t1. To do. Δ is equal to or less than the time corresponding to the Nyquist value N / 2 when performing FFT processing on the synchronization OFDM symbol SYNCP.

  In addition, (δ + t1) is a time longer than the time corresponding to the Nyquist value N / 2 when (1) the OFDM symbol SYNCP for synchronization is subjected to FFT processing, and (2) the OFDM symbol for Data ( It is assumed that the time is shorter than the time corresponding to the Nyquist value (L × N) / 2 in the case of performing the FFT processing for the GI portion (including the GI portion).

  In the case shown in FIG. 12, since the shift amount δ of the FFT window FFTw1 for the OFDM symbol SYNCP for main wave synchronization is equal to or less than the time corresponding to the Nyquist value N / 2 for the OFDM symbol SYNCP for synchronization, Correct data (signal Ds92) can be acquired by the FFT processing by the FFT unit 93.

  On the other hand, the shift amount δ + t1 of the reflected wave SYNCP FFT window FFTw1 is longer than the time corresponding to the Nyquist value N / 2 for the synchronization OFDM symbol SYNCP. Correct data (signal Ds92) cannot be acquired. As a result, the transmission path transfer function acquired by the data receiving apparatus 900 is not appropriate.

  The shift amount δ of the main data FFT window FFTw2 and the shift amount δ + t1 of the reflected data FFT window FFTw2 correspond to the Nyquist value (8 × N) / 2 for the OFDM symbol Data for data. Therefore, correct data (signal D92) can be acquired by FFT processing by the payload FFT unit 92. However, the transmission path transfer function Hp3 (k) to be divided by the second division unit 98 with respect to the signal D92 is an acquired signal based on the signal Dp92 not acquired as an appropriate signal as described above. Yes, not a proper signal. As a result, the signal D93 output from the second division unit 98 is not an appropriate signal, and the signal Dout output from the demodulation unit 99 is not an appropriate signal (correct signal).

  As described above, in the transmission line characteristic estimation process in the data receiving apparatus 900, there is a problem that an appropriate process is not executed when the delay of the reflected wave is larger than a certain value.

  Therefore, in view of the above-described problems, the present invention appropriately executes the transmission path characteristic estimation process even when a RI period having a time equivalent to that of the synchronization OFDM symbol SYNCP is provided. An object of the present invention is to realize a data receiving device, a program, and an integrated circuit capable of appropriately executing transmission path characteristic estimation processing even when the amount of wave delay is large.

  In order to solve the above-mentioned problem, the first invention is a transmission having a preamble portion including a synchronization signal and a payload portion including a data signal and provided with a roll-off period for preventing phase discontinuity. It is a data receiving apparatus that receives a transmission signal that is a signal and the number of samples of the synchronization signal is smaller than the number of samples of the data signal. The data reception apparatus includes a front end unit, a synchronization detection unit, a preamble FFT unit, a transmission characteristic data acquisition unit, an inverse Fourier transform unit, a time domain signal adjustment unit, a Fourier transform unit, and a phase adjustment unit. A buffer unit, a payload FFT unit, and a transmission characteristic correction unit.

  The front end unit receives a transmission signal.

  The synchronization detection unit executes synchronization detection processing based on the synchronization signal and acquires the synchronization timing.

  The preamble FFT unit sets the preamble FFT window shifted by the first shift amount δ based on the synchronization timing, and executes the FFT processing based on the synchronization timing.

  The transmission characteristic data acquisition unit acquires transmission characteristic data based on the signal acquired by the preamble FFT unit.

  The inverse Fourier transform unit performs an inverse Fourier transform process on the transmission characteristic data acquired by the transmission characteristic data acquisition unit.

  The time domain signal adjustment unit performs a shift process and an interpolation process with the time domain shift amount M on the signal acquired by the inverse Fourier transform unit.

  The Fourier transform unit performs a Fourier transform process on the signal acquired by the time domain signal adjustment unit.

  The phase adjustment unit performs phase adjustment processing corresponding to the reverse shift processing of the shift processing by the time domain signal adjustment unit on the signal acquired by the Fourier transform unit, and acquires transmission path information.

  The buffer unit holds the transmission path information acquired by the phase adjustment unit.

  The payload FFT unit is shifted by the shift amount (RI + δ) with respect to the data signal based on the first shift amount δ and the second shift amount RI corresponding to the roll-off period RI based on the synchronization timing. The data block FFT window is set, and the FFT processing is executed on the data signal by the data block FFT window.

  The transmission characteristic correction unit executes transmission characteristic correction processing on the signal acquired by the payload FFT unit based on the transmission path information held in the buffer unit.

  In this data receiving apparatus, the payload FFT unit shifts the data block FFT window by (RI + δ) to perform the FFT process. Therefore, the FFT process can be performed excluding the RI section, and therefore data cannot be correctly restored. It is possible to reliably prevent the data (sample) in the RI section from being used in the FFT process. In this data receiving apparatus, the signal component is shifted in the time domain, and the phase adjustment process, which is a process corresponding to the reverse shift, is performed in the frequency domain (Fourier transform domain). Thus, in this data receiving apparatus, the amount of deviation of the preamble FFT window with respect to the reflected wave is shifted by a time corresponding to the Nyquist value N / 2 when the FFT processing is performed on the synchronization signal. However, it is possible to obtain a transmission path transfer function that is estimated appropriately.

  Therefore, in this data receiving apparatus, even when an RI period such as SYNCP is provided, the transmission path characteristic estimation process is appropriately performed, and the reflected wave Even if the delay amount is large, the transmission path characteristic estimation process can be appropriately executed.

  Note that the “FFT window” refers to an area that is set to acquire the number of data (samples) necessary for the FFT processing for a signal sequence.

  2nd invention is 1st invention, Comprising: A noise reduction process part, an impulse shift part, and an interpolation part are provided.

  The noise reduction processing unit replaces the signal value of the signal component equal to or less than the threshold Th with respect to the signal acquired by the inverse Fourier transform unit by a signal value having an absolute value smaller than the absolute value of the original signal value. Perform noise reduction processing.

  The impulse shift unit performs a shift process using the time domain shift amount M on the signal acquired by the noise reduction processing unit.

  The interpolation unit performs an interpolation process on the signal acquired by the impulse shift unit such that the number of samples of the signal is the same as the number of samples of the data signal.

  In this data receiving apparatus, since the signal component below the threshold value Th can be suppressed by the noise reduction unit, it is possible to acquire data on the transmission path transfer function with high accuracy effectively. In addition, in this data receiving apparatus, processing for shifting signal components (processing for shifting impulse response components) and interpolation processing are executed in the time domain, so that data relating to a transmission path transfer function with high accuracy can be acquired efficiently. can do.

  3rd invention is 2nd invention, Comprising: A noise reduction process part makes the signal value "0" the signal value of the signal component below threshold value Th with respect to the signal acquired by the inverse Fourier-transform part. By doing so, noise reduction processing is executed.

  In this data receiving apparatus, since the signal component equal to or less than the threshold Th is set to the signal value “0” by the noise reduction unit, it is possible to effectively acquire data on the transmission path transfer function with high accuracy. In addition, in this data receiving apparatus, processing for shifting signal components (processing for shifting impulse response components) and interpolation processing are executed in the time domain, so that data relating to a transmission path transfer function with high accuracy can be acquired efficiently. can do.

  A fourth invention is a transmission signal having a preamble part including a synchronization signal and a payload part including a data signal and provided with a roll-off period for preventing phase discontinuity, This is a program for causing a computer to execute a data reception method for receiving a transmission signal whose number of samples is smaller than the number of samples of a data signal.

  The data reception method includes a front end step, a synchronization detection step, a preamble FFT step, a transmission characteristic data acquisition step, an inverse Fourier transform step, a time domain signal adjustment step, a Fourier transform step, and a phase adjustment step. , A holding step, a payload FFT step, and a transmission characteristic correcting step.

  The front end step receives the transmission signal.

  In the synchronization detection step, synchronization detection processing is executed based on the synchronization signal to acquire synchronization timing.

  In the preamble FFT step, a preamble FFT window shifted by the first shift amount δ is set based on the synchronization timing, and an FFT process is performed on the synchronization signal through the preamble FFT window.

  The transmission characteristics data acquisition step acquires transmission characteristics data based on the signal acquired by the preamble FFT step.

  In the inverse Fourier transform step, an inverse Fourier transform process is performed on the transmission characteristic data acquired in the transmission characteristic data acquisition step.

  In the time domain signal adjustment step, a shift process based on the time domain shift amount M and an interpolation process based on zero insertion are performed on the signal acquired in the inverse Fourier transform step.

  The Fourier transform step performs a Fourier transform process on the signal acquired by the time domain signal adjustment step.

  In the phase adjustment step, a phase adjustment process corresponding to the reverse shift process of the shift process in the time domain signal adjustment step is performed on the signal acquired in the Fourier transform step to acquire transmission path information.

  The holding step holds the transmission path information acquired by the phase adjustment step.

  The payload FFT step acquires a data signal based on the synchronization timing, and shifts the data signal based on the first shift amount δ and the second shift amount RI corresponding to the roll-off period RI. An FFT window for data block shifted by (RI + δ) is set, and an FFT process is executed on the data signal by the FFT window for data block.

  In the transmission characteristic correction step, transmission characteristic correction processing is executed on the signal acquired by the payload FFT step based on the transmission path information held in the holding step.

  As a result, it is possible to realize a program that causes a computer to execute a data receiving method that exhibits the same effects as those of the first invention.

  A fifth invention is a transmission signal having a preamble portion including a synchronization signal and a payload portion including a data signal and provided with a roll-off period for preventing phase discontinuity, This is an integrated circuit used in a data receiving apparatus that receives a transmission signal whose number of samples is smaller than the number of samples of a data signal. The integrated circuit includes a front end unit, a synchronization detection unit, a preamble FFT unit, a transmission characteristic data acquisition unit, an inverse Fourier transform unit, a time domain signal adjustment unit, a Fourier transform unit, a phase adjustment unit, A buffer unit, a payload FFT unit, and a transmission characteristic correction unit are provided.

  The front end unit receives a transmission signal.

  The synchronization detection unit executes synchronization detection processing based on the synchronization signal and acquires the synchronization timing.

  The preamble FFT unit acquires the synchronization signal from the front end unit based on the synchronization timing, sets the preamble FFT window shifted by the first shift amount δ for the synchronization signal, The FFT processing is executed by the preamble FFT window.

  The transmission characteristic data acquisition unit acquires transmission characteristic data based on the signal acquired by the preamble FFT unit.

  The inverse Fourier transform unit performs an inverse Fourier transform process on the transmission characteristic data acquired by the transmission characteristic data acquisition unit.

  The time domain signal adjustment unit performs a shift process with the time domain shift amount M on the signal acquired by the inverse Fourier transform unit.

  The Fourier transform unit performs a Fourier transform process on the signal acquired by the time domain signal adjustment unit.

  The phase adjustment unit performs phase adjustment processing corresponding to the reverse shift processing of the shift processing by the time domain signal adjustment unit on the signal acquired by the Fourier transform unit, and acquires transmission path information.

  The buffer unit holds the transmission path information acquired by the phase adjustment unit.

  The payload FFT unit obtains a data signal from the front end unit based on the synchronization timing, and applies the data signal based on the first shift amount δ and the second shift amount RI corresponding to the roll-off period RI. Thus, the FFT block for data block shifted by the shift amount (RI + δ) is set, and the FFT processing is executed on the data signal by the FFT window for data block.

  The transmission characteristic correction unit executes transmission characteristic correction processing on the signal acquired by the payload FFT unit based on the transmission path information held in the buffer unit.

  Thus, an integrated circuit that exhibits the same effect as that of the first invention can be realized.

  According to the present invention, even when an RI period having a time equivalent to that of the synchronization OFDM symbol SYNCP is provided, the transmission path characteristic estimation process is appropriately executed, and the delay amount of the reflected wave is large. Even in this case, it is possible to realize a data reception device, a program, and an integrated circuit that can appropriately execute the transmission path characteristic estimation process.

The figure which extracted and showed a part of transmission signal. 1 is a schematic configuration diagram of a communication system 1000 according to a first embodiment. 1 is a schematic configuration diagram of a data receiving device 100 of a communication system 1000 according to a first embodiment. The schematic block diagram of the transmission characteristic correction | amendment part 10 of the communication system 1000 which concerns on 1st Embodiment. The schematic block diagram of the time-domain signal adjustment part 6 of the communication system 1000 which concerns on 1st Embodiment. The figure which shows the relationship between the main wave and reflected wave which are the received signals of the data receiver 100, the FFT window w1 for SYNCP, and the FFT window FFTw2 for Data. The figure which showed the impulse response waveform of signal Dp4 (= hp (n-delta)). The figure for demonstrating the impulse shift process by the impulse shift part 62. FIG. The figure for demonstrating the interpolation process by the interpolation part 63. FIG. The figure for demonstrating the phase adjustment process by the phase adjustment part 8. FIG. The figure which shows schematic structure of the conventional communication system 9000. FIG. The figure which showed the transmission signal containing a preamble and a payload. The figure which showed the transmission signal containing a preamble and a payload.

[First Embodiment]
The first embodiment will be described below with reference to the drawings.

<1.1: Configuration of communication system>
FIG. 2 is a schematic configuration diagram of a communication system 1000 according to the first embodiment.

  FIG. 3A is a schematic configuration diagram of the data receiving device 100 of the communication system 1000 according to the first embodiment.

  FIG. 3B is a schematic configuration diagram of the transmission characteristic correction unit 10 of the communication system 1000 according to the first embodiment.

  FIG. 4 is a schematic configuration diagram of the time domain signal adjustment unit 6 of the communication system 1000 according to the first embodiment.

  FIG. 5 is a diagram illustrating a relationship among a main wave and a reflected wave, which are reception signals of the data receiving apparatus 100, a SYNCP FFT window FFTw1, and a Data FFT window FFTw2.

  Note that, in the communication system 1000 as well, as in the communication system 9000, data transmission / reception is performed by the transmission signal shown in FIG.

  The communication system 1000 is a communication system that performs data communication using an OFDM modulation scheme. As shown in FIG. 2, the communication system 1000 includes a data transmission device Tx1 and a data reception device 100.

  The data transmission device Tx1 has the same configuration and function as the data transmission device Tx1 in the communication system 9000, generates an OFDM signal, and outputs the generated OFDM signal to the transmission path.

  Hereinafter, as an example, a case where data communication is performed using a transmission line as a power line carrier network will be described. In FIG. 2, the data transmission device Tx1 and the data reception device 100 are connected to the power line PL and perform data communication via the power line PL.

  For convenience of explanation, as shown in FIG. 2, among the OFDM signals output from the data transmission device Tx1, (1) the signal of the payload portion is denoted as signal D0, and the notation of the signal D0 as a discrete time signal is denoted by d. (N), (2) a signal corresponding to the synchronization OFDM symbol SYNCP is represented as a signal Dp0, and a representation of the signal Dp0 as a discrete time signal is represented by p (n).

  As shown in FIG. 3A, the data receiving apparatus 100 includes an FE unit 1, a synchronization detection unit 1A, a payload FFT unit 2, a preamble FFT unit 3, a division unit 4, an inverse Fourier transform unit 5, A time domain signal adjustment unit 6, a Fourier transform unit 7, a phase adjustment unit 8, a buffer unit 9, a transmission characteristic correction unit 10, and a demodulation unit 11 are provided.

  The FE unit (front end unit) 2 receives the OFDM signal output from the data transmission device Tx1 via the transmission line PL.

  The synchronization detection unit 1A performs synchronization detection processing on the received preamble of the OFDM signal and acquires the synchronization timing. In the synchronization detection unit 1A, processing for performing symbol synchronization and the like is executed.

  The preamble FFT unit 3 inputs a preamble signal Dp1 (= p (n) * h (n)) of the received OFDM signal. The preamble FFT unit 3 cuts out N samples of OFDM symbols (OFDM symbols in the preamble) at a predetermined timing based on the synchronization timing acquired by the synchronization detection unit 1A.

  The preamble FFT unit 3 shifts the signal Dp1 (= p (n) * h (n)) output from the FE unit 2 by δ in the preamble direction as shown in FIG. The FFT processing is executed by the FFT window FFTw1. The preamble FFT unit 3 outputs the signal acquired by the FFT process to the division unit 4 as a signal Dp2.

When an impulse response indicating the transmission characteristics of the communication system 1000 is represented as h (n), the signal Dp1 is
Dp1 = p (n) * h (n)
It can be expressed as Note that “*” indicates an operator that performs a convolution operation (convolution integration operation).

  The division unit 4 receives the signal Dp2 output from the preamble FFT unit 3. The division unit 4 executes a process of dividing the input signal Dp2 by a synchronization pattern P (k) (a known pattern included in the synchronization OFDM symbol SYNCP) that is a known pattern, and the signal after the division process is performed. The signal Dp3 is output to the inverse Fourier transform unit 5.

  The inverse Fourier transform unit 5 receives the signal Dp3 output from the division unit 4. The inverse Fourier transform unit 5 performs an inverse FFT transform process on the input signal Dp3, and outputs the signal after the inverse FFT transform process to the time domain signal adjustment unit 6 as a signal Dp4.

  The time domain signal adjustment unit 6 receives the signal Dp4 output from the inverse Fourier transform unit 5. The time domain signal adjustment unit 6 performs time domain adjustment processing on the input signal Dp4, and outputs the processed signal to the Fourier transform unit 7 as a signal Dp5.

  As shown in FIG. 4, the time domain signal adjustment unit 6 includes a noise reduction unit 61, an impulse shift unit 62, and an interpolation unit 63.

  The noise reduction unit 61 receives the signal Dp4 output from the inverse Fourier transform unit 5. The noise reduction unit 61 performs noise reduction processing on the signal Dp4, and outputs the processed signal to the impulse shift unit 62 as a signal Dp41.

  The impulse shift unit 62 receives the impulse shift amount setting value M and the signal Dp41 output from the noise reduction unit 61. The impulse shift unit 62 performs an impulse shift process on the input signal Dp41 based on the impulse shift amount setting value M, and outputs the processed signal to the interpolation unit 63 as a signal Dp42.

  The interpolation unit 63 receives the signal Dp42 output from the impulse shift unit 62. The interpolation unit 63 performs an interpolation process so that the number of sample points (the number of discrete data) is eight times, and outputs the signal after the interpolation process to the Fourier transform unit 7 as Dp5.

  The Fourier transform unit 7 receives the signal Dp5 output from the time domain signal adjustment unit 6. The Fourier transform unit 7 performs FFT processing on the input signal Dp5, and outputs the signal after FFT processing to the phase adjustment unit 8 as a signal Dp6.

  The phase adjustment unit 8 receives the signal Dp6 output from the Fourier transform unit 7. The phase adjustment unit 8 performs phase adjustment processing on the input signal Dp6 and outputs the processed signal to the buffer unit 9 as a signal Dp7.

  The buffer unit 9 stores the signal Dp7 output from the phase adjustment unit 8, and stores the signal Dp7 stored in the transmission characteristic correction unit 10 at a predetermined timing (a timing at which the transmission characteristic correction unit 10 can process). Dp7 is output as signal Dp8.

  After receiving the preamble signal, the FE unit 1 receives the payload signal.

  The payload FFT unit 2 cuts out OFDM symbols of L × N (L: natural number) samples in the extended OFDM symbol for data at a predetermined timing based on the synchronization timing acquired by the synchronization detection unit 1A. . The payload FFT unit 2 shifts the signal D1 (= d (n) * h (n)) output from the FE unit 1 by (RI + δ) in the GI direction as shown in FIG. The FFT processing is executed by the FFT window FFTw2. RI is the time of the RI section, and δ is the same shift amount (shift time) as the shift amount (shift time) of the FFT window for SYNCP.

  Then, the payload FFT unit 2 outputs the signal acquired by the FFT process to the transmission characteristic correction unit 10 as a signal D2.

  As illustrated in FIG. 3B, the transmission characteristic correction unit 10 includes a transmission characteristic correction unit first division unit 101 and a transmission characteristic correction unit second division unit 102. The transmission characteristic correction unit 10 receives the signal D2 output from the payload FFT unit 2 and the signal Dp8 output from the buffer unit 9. The transmission characteristic correction unit 10 performs transmission characteristic correction processing on the signal D2 based on the signal Dp8, and outputs the processed signal to the demodulation unit 11 as a signal D3.

  The demodulation unit 11 performs a demodulation process (a demodulation process (for example, a PSK demodulation process, a QAM demodulation process) corresponding to the modulation process of the data transmission device Tx) on the signal D3 output from the transmission characteristic correction unit 10, The signal Dout is acquired.

<1.2: Operation of Communication System 1000>
The operation of the communication system 1000 configured as described above will be described below.

  The FE unit (front end unit) 2 receives the OFDM signal output from the data transmission device Tx1 via the transmission line PL.

  The synchronization detection unit 1A performs synchronization detection processing on the preamble of the received OFDM signal. In other words, the synchronization detection unit 1A executes a process for synchronizing symbols.

  In the preamble FFT unit 3, the signal Dp1 (= p (n) * h (n)) output from the FE unit 1, as shown in FIG. 5, is shifted by δ in the head direction of the preamble. FFT processing is executed by the FFT window FFTw1.

The preamble FFT unit 3 performs an FFT operation on the N samples (data) of the signal Dp1 using the SYNCP FFT window FFTw1 set as described above, and obtains a signal Dp2. When a signal obtained by Fourier transforming p (n) is represented by P (k), and a signal obtained by performing Fourier transform on h (n) by the preamble FFT unit 3 is represented by Hp (k), the signal Dp2 is
Dp2 = P (k) × Hp (k) × f (δ)
f (δ) = exp (−i × 2πkδ / N)
It can be expressed as

  That is, since the preamble is composed of L1 (L1: natural number) synchronization OFDM symbols SYNCP generated based on the same known pattern, the preamble is shown in FIG. 5 due to the nature of the cyclic shift of the discrete Fourier transform. In this way, when the SYNCP FFT window FFTw1 is shifted, the shift amount can be expressed as f (δ) in the discrete Fourier transform domain. For convenience of explanation, the following explanation will be made assuming that L1 = 10.

  The signal Dp2 (= P (k) × Hp (k) × f (δ)) obtained by performing the above-described processing by the preamble FFT unit 3 is output from the preamble FFT unit 3 to the division unit 4. Is done.

In the division unit 4, the signal Dp2 output from the preamble FFT unit 3 is divided by a synchronization pattern P (k) (a known pattern included in the synchronization OFDM symbol SYNCP) that is a known pattern. That is, in the division unit 4,
Dp3 = Dp2 / P (k)
= P (k) × Hp (k) × f (δ) / P (k)
= Hp (k) × f (δ)
The signal Dp3 is acquired by executing the processing corresponding to.

  The signal Dp3 acquired by the dividing unit 4 is output from the dividing unit 4 to the inverse Fourier transform unit 5.

In the inverse Fourier transform unit 5, an inverse FFT operation process is performed on the N pieces of data of the signal Dp3. That is, in the inverse Fourier transform unit 5,
Dp4 = IFFT [Hp (k) × f (δ)]
= Hp (n-δ)
IFFT []: A process corresponding to the inverse FFT operation is executed, and the signal Dp4 is acquired.

  Then, the signal Dp4 acquired by the inverse Fourier transform unit 5 is output from the inverse Fourier transform unit 5 to the noise reduction unit 61 of the time domain signal adjustment unit 6.

  In the noise reduction unit 61, noise reduction processing is performed on the signal Dp4. This will be described with reference to FIG.

  FIG. 6 is a diagram showing an impulse response waveform of the signal Dp4 (= hp (n−δ)). As shown in FIG. 6, the impulse component of the main wave exists at the position of n = a1, the impulse component of the reflected wave exists at the position of n = b1, and the impulse component of the reflected wave is The following description will be made assuming that the impulse component is 0.5 times the impulse component of the main wave.

  As shown in FIG. 5, the delay time of the reflected wave with respect to the main wave is t1. Δ is equal to or less than the time corresponding to the Nyquist value N / 2 when performing FFT processing on the synchronization OFDM symbol SYNCP.

  In addition, (δ + t1) is a time longer than the time corresponding to the Nyquist value N / 2 when (1) the OFDM symbol SYNCP for synchronization is subjected to FFT processing, and (2) the OFDM symbol for Data ( It is assumed that the time is shorter than the time corresponding to the Nyquist value (8 × N) / 2 in the case of performing the FFT processing for the GI portion (including the GI portion).

  In the noise reduction unit 61, a threshold value Th is set in the signal Dp, and a signal value whose component value of the signal Dp is smaller than the threshold value Th is set to “0” (replaced with a value in which the absolute value of the signal value is reduced). . Thereby, the noise component contained in the impulse response waveform of the signal Dp4 (= hp (n−δ)) can be effectively reduced. The threshold value Th may be set by a control unit (not shown) that controls each functional unit of the data receiving apparatus 100, for example. Further, the threshold value Th is obtained by analyzing an impulse response waveform of the signal Dp4 (= hp (n−δ)), detecting a signal value having a maximum value assumed to be a main wave and a reflected wave, and taking the detected maximum value. The determination may be made based on the signal value. For example, a value that is k times the minimum value (0 ≦ k ≦ 1) of the signal values that have the maximum values assumed to be the main wave and the reflected wave may be set as the threshold Th.

  In the noise reduction unit 61, the threshold value Th is set in the signal Dp, and the signal value whose component value of the signal Dp is smaller than the threshold value Th is not “0”, but the component value of the signal Dp is higher than the threshold value Th. The signal value may be replaced with a smaller signal value so that the absolute value of the signal value becomes smaller than the absolute value of the original signal value.

  When the above processing is executed by the noise reduction unit 61, the signal Dp41 on which the noise reduction processing has been executed is acquired. The acquired signal Ds41 is output from the noise reduction unit 61 to the impulse shift unit 62.

  In the impulse shift unit 62, impulse shift processing is performed on the signal Dp41. This will be described with reference to FIG.

  FIG. 7 is a diagram for explaining the impulse shift processing by the impulse shift unit 62. FIG. 7 is a diagram illustrating an impulse response waveform of the signal Dp42 (= hp (n−δ + M)) acquired by the impulse shift process by the impulse shift unit 62.

  The impulse shift unit 62 performs an impulse shift process on the signal Dp41 with an impulse shift amount setting value M (for example, N / 4 <M <N / 2). Specifically, as shown in FIG. 7, the impulse shift unit 62 shifts the signal component value (n = a1) of the main wave of the signal Dp41 to the left by the impulse shift amount setting value M. Since a1 <M, the position of the main signal component of the signal Dp41 after the left shift is n = N-1 + a1-M.

  Further, the impulse shift unit 62 shifts the signal component value (n = b1) of the reflected wave of the signal Dp41 to the left by the impulse shift amount setting value M. That is, the position of the signal component of the reflected wave of the signal Dp41 after the left shift is a position of n = b1-M.

  By executing the above process by the impulse shift unit 62, a signal Dp42 (= hp (n−δ + M)) on which the impulse shift process has been executed is acquired. The acquired signal Dp42 is output from the impulse shift unit 62 to the interpolation unit 63.

  In the interpolation unit 63, interpolation processing is executed so that the sample point (the number of discrete data) is eight times the signal Dp42. This will be described with reference to FIG.

  FIG. 8 is a diagram for explaining the interpolation processing by the interpolation unit 63. FIG. 8 is a diagram showing an impulse response waveform of the signal Dp5 (= hp1 (n−δ + M)) acquired by the interpolation processing by the interpolation unit 63. Note that hp1 (n−δ + M) is an impulse response function obtained by interpolating hp (n−δ + M).

In the impulse response signal Dp42, the interpolation unit 63
(1) Hold the signal waveform of 0 ≦ n ≦ N / 2 as it is,
(2) The signal component of the signal value “0” is interpolated into N / 2 <n ≦ 4N.

Further, in the interpolating unit 63, in the impulse response signal Dp42,
(1) The signal waveform in the range of N / 2 <n ≦ N−1 is shifted to the range of 8N−1−N / 2 <n ≦ 8N−1,
(2) The signal component of the signal value “0” is interpolated into 4N <n ≦ 8N−1−N / 2.

  That is, the interpolating unit 63 interpolates the signal component of the signal value “0” in the region R_zero (N / 2 <n <8N−1−N / 2) in FIG. ) Is 8 times the sample point (the number of discrete data) of the signal Dp42.

  By executing the above process by the interpolation unit 63, a signal Dp5 (= hp1 (n−δ + M)) on which the interpolation process has been executed is acquired. The acquired signal Dp5 is output from the interpolation unit 63 to the Fourier transform unit 7.

In the Fourier transform unit 7, an FFT operation process is performed on 8 × N pieces of data of the signal Dp5. That is, in the Fourier transform unit 7,
Dp6 = FFT [hp1 (n−δ + M)]
= Hp1 (k) × f1 (δ) × f1 (−M)
f1 (δ) = exp (−i × 2πkδ / (8 × N))
f1 (−M) = exp (i × 2πkM / (8 × N))
FFT []: A process corresponding to the FFT operation is executed, and the signal Dp6 is acquired.

  Then, the signal Dp6 acquired by the Fourier transform unit 7 is output to the phase adjustment unit 8.

In the phase adjustment unit 8, a phase adjustment process is performed on the signal Dp6. That is, in the phase adjustment unit 8,
Dp7 = Dp6 / f1 (−M)
= Hp1 (k) × f1 (δ)
f1 (−M) = exp (i × 2πkM / (8 × N))
Is performed, and the signal Dp7 is acquired.

  Then, the signal Dp7 acquired by the phase adjustment unit 8 is output to the buffer unit 9.

  Note that the processing by the phase adjustment unit 8 corresponds to shifting right by a value M in the time domain. This will be described with reference to FIG.

  FIG. 9 is a diagram for explaining phase adjustment processing by the phase adjustment unit 8.

  As shown in FIG. 9, the process of dividing the signal Dp6 by f1 (−M) corresponds to the process of shifting the signal component (n = b1−M) after the reflected wave shift process of FIG. To do. Therefore, when the signal component after the reflected wave shift process is shifted to the right by M, the position of the reflected wave signal component after the shift (after the reverse shift) is n = b1. That is, the position of the signal component of the reflected wave returns to the original position before the impulse shift process.

  Further, the process of dividing the signal Dp6 by f1 (−M) corresponds to the process of shifting the signal component (n = 8N−1 + a1−M) after the main wave shift process of FIG. 9 by M to the right. Since 8N-1 + a1> 8N-1, if the signal component after the main wave shift processing (n = 8N-1 + a1-M) is shifted to the right by M, the main wave after the shift (after the reverse shift) is shifted. The position of the signal component is n = a1. That is, the position of the signal component of the main wave returns to the original position before the impulse shift process.

  By processing in this way, the signal Dp6 after the phase adjustment processing becomes a transmission path transfer function that is appropriately estimated. That is, as shown in FIG. 5, the amount of deviation of the SYNCP FFT window is shifted from the reflected wave by a time corresponding to the Nyquist value N / 2 when performing the FFT processing on the synchronization OFDM symbol SYNCP. Even in such a case, the transmission path transfer function estimated appropriately can be acquired by the above processing.

  The signal Dp7 (= Hp1 (k) × f1 (δ)) obtained by executing the above processing by the phase adjustment unit 8 is output from the phase adjustment unit 8 to the buffer unit 9 and held therein.

  In the buffer unit 9, the signal Dp7 (= Hp1 (k) × f1 (δ)) stored in the transmission characteristic correction unit 10 is a signal at a predetermined timing (a timing at which the transmission characteristic correction unit 10 can process). It is output to the transmission characteristic correction unit 10 as Dp8.

  After receiving the preamble signal, the FE unit 1 receives the payload signal.

  The payload FFT unit 2 cuts out OFDM symbols of 8 × N samples in the extended OFDM symbol for data at a predetermined timing based on the synchronization timing acquired by the synchronization detection unit 1A.

  In the payload FFT unit 2, the data D1 (= d (n) * h (n)) output from the FE unit 1 is shifted in the GI direction by (RI + δ) as shown in FIG. The FFT processing is executed by the FFT window FFTw2.

The payload FFT unit 2 performs an FFT operation on 8 × N data of the signal D1 by the Data FFT window FFTw2 set as described above, and acquires the signal D2. When a signal obtained by Fourier transforming d (n) is represented as D (k), and a signal obtained by performing Fourier transform on h (n) by the payload FFT unit 2 is represented as Hd (k), the signal D2 is
D2 = D (k) × Hd (k) × f1 (RI + δ)
f1 (RI + δ) = exp (−i × 2πk (RI + δ) / (8 × N))
It can be expressed as

  That is, in the payload, the samples included in the GI section are samples existing in the same section of the GI section from the end of the OFDM symbol Data for data, and therefore, due to the nature of the cyclic shift of the discrete Fourier transform, FIG. As shown, when the Data FFT window FFTw2 is shifted, the shift amount can be expressed as f1 (RI + δ) in the discrete Fourier transform region.

  The signal D2 (= D (k) × Hd (k) × f1 (RI + δ)) obtained by the above processing performed by the payload FFT unit 2 is transmitted from the payload FFT unit 2 to the transmission characteristic correction unit 10. Is output.

In the transmission characteristic correction unit 10, the signal Dp8 (==) output from the buffer unit 9 with respect to the signal D2 (= D (k) × Hd (k) × f1 (RI + δ)) output from the payload FFT unit 2. Transmission characteristic correction processing is executed by Hp1 (k) × f1 (δ)). Specifically, the transmission characteristic correction unit 10
D30 = D2 / Dp8
= D (k) × Hd (k) × f1 (RI + δ) / (Hp1 (k) × f1 (δ))
The process corresponding to is executed. When Hd (k) = Hp1 (k), the result is as follows.

f1 (RI + δ) and f1 (δ) are
f1 (RI + δ) = exp (−i × 2πk (RI + δ) / (8 × N))
f1 (δ) = exp (−i × 2πkδ / (8 × N))
So
D30 = D2 / Dp8
= D (k) × f1 (RI)
f1 (RI) = exp (−i × 2πk (RI) / (8 × N))
It becomes.

  The transmission characteristic correction unit first division unit 101 of the transmission characteristic correction unit 10 executes processing equivalent to the above (division processing).

Furthermore, in the transmission characteristic correction unit first division unit 102 of the transmission characteristic correction unit 10,
D3 = D30 / f1 (RI)
= D (k)
f1 (RI) = exp (−i × 2πk (RI) / (8 × N))
The signal D3 (= D (k)) is acquired by executing the processing corresponding to.

  Then, the signal D3 (= D (k)) acquired by the transmission characteristic correction unit 10 is output to the demodulation unit 11.

  The demodulation unit 11 performs demodulation processing (for example, PSK demodulation processing, QAM, etc.) on the signal D3 (= D (k)) output from the transmission characteristic correction unit 10 corresponding to the modulation processing of the data transmission device Tx. Demodulation processing)) is executed, and the signal Dout (= d (n)) is acquired.

  As described above, the data receiving apparatus 100 appropriately executes the transmission path characteristic estimation process even when the RI period having the same time as the synchronization OFDM symbol SYNCP is provided, and the reflected wave Even if the delay amount is large, the transmission path characteristic estimation process can be appropriately executed.

  That is, in the data receiving apparatus 100, the inverse Fourier transform unit 5 performs the inverse operation on the signal Dp3 (= Hp (k) × f (δ)) obtained by performing the FFT process by shifting the SYNCP FFT window FFTw1 by δ. A time domain signal Dp4 (= hp (n−δ)) is acquired by executing a Fourier transform process (for example, IFFT process). In the data receiving apparatus 100, the noise reduction process by the noise reduction unit 61 and the impulse shift process by the value M are performed on the time domain signal Dp4, and then the interpolation process of 8 times is performed in the time domain. Then, an 8 times interpolated signal Dp5 (= hp1 (n−δ + M)) is obtained. In the data receiving apparatus 100, the Fourier transform unit 7 performs Fourier transform processing (for example, FFT processing) on the signal Dp5, and the acquired signal Dp6 (= Hp1 (k) × f1 (δ) × f1 (−M) ) Is divided by f1 (−M) in the frequency domain (Fourier transform domain). That is, in the data receiving apparatus 100, the signal component is shifted in the time domain, and processing corresponding to the reverse shift is performed in the frequency domain (Fourier transform domain). As a result, in the data receiving apparatus 100, as shown in FIG. 5, the deviation amount of the FFT window FFTw1 for SYNCP with respect to the reflected wave is the Nyquist value N / N when the FFT processing is performed on the synchronization OFDM symbol SYNCP. Even when the time is shifted by a time corresponding to 2 or more, a properly estimated transmission path transfer function (signal Hp1 (k) × f1 (δ) obtained by shifting by δ) can be acquired.

  In the data receiving apparatus 100, the payload FFT unit 2 performs the FFT process by shifting the FFT window FFTw2 for Data by (RI + δ). Therefore, the FFT process can be performed excluding the RI section. It is possible to reliably prevent the symbols in the RI section from which data cannot be restored from being used in the FFT processing. In the data receiving apparatus 100, the signal D2 (= D (k) × Hd (k) × f1 (RI + δ)) acquired by the payload FFT unit 2 is acquired using the synchronization OFDM symbol SYNCP. By dividing by the signal Dp8 (= Hp1 (k) × f1 (δ)), the signal D30 (= D (k) × f1 (RI)) is acquired by the transmission characteristic correction unit 10 (Hd (k) = Hp1 (k)). Further, in the data receiving apparatus 100, the transmission characteristic correction unit 10 executes a process of dividing the signal D30 by f1 (RI), and acquires the signal D3 (= D (k)).

  Therefore, in the data receiving apparatus 100, the sample of the RI section in which data cannot be correctly restored is not used for processing, and the signal Hp1 (k ) × f1 (δ)) can be used to appropriately execute the transmission estimation process.

  As described above, the data receiving apparatus 100 appropriately executes the transmission path characteristic estimation process even when the RI period having the same time as the synchronization OFDM symbol SYNCP is provided, and the reflected wave Even if the delay amount is large, the transmission path characteristic estimation process can be appropriately executed.

[Other Embodiments]
In the above-described embodiment, the case where processing is performed on the signal illustrated in FIG. 1 has been described. However, the present invention is not limited to this, and the configuration of the signal to be processed may be another configuration. .

  In the above embodiment, the case where the number of samples of the data OFDM symbol Data is eight times the number of samples of the synchronization OFDM symbol SYNCP has been described. However, the present invention is not limited to this. The number of samples of the OFDM symbol Data for data may be m times the number of samples of the OFDM symbol SYNCP for synchronization (m: natural number). Even in this case, in the data receiving apparatus 100, the interpolation unit 63 By changing the interpolation process or the like in, the transmission path estimation process can be executed by the same process as described above.

  Moreover, although the case where the main wave and one reflected wave were received was demonstrated to the example in the said embodiment, it is not limited to this, The number of reflected waves may be two or more. . Also in this case, the data receiving apparatus 100 can execute an appropriate transmission path estimation process by performing the same process as described above.

  In the state estimation device described in the above embodiment, each block may be individually made into one chip by a semiconductor device such as an LSI, or may be made into one chip so as to include a part or all of the blocks.

  Here, although LSI is used, it may be called IC, system LSI, super LSI, or ultra LSI depending on the degree of integration.

  Further, the method of circuit integration is not limited to LSI, and implementation with a dedicated circuit or a general-purpose processor is also possible. An FPGA (Field Programmable Gate Array) that can be programmed after manufacturing the LSI or a reconfigurable processor that can reconfigure the connection and setting of circuit cells inside the LSI may be used.

  In addition, part or all of the processing of each functional block in each of the above embodiments may be realized by a program. A part or all of the processing of each functional block in each of the above embodiments is performed by a central processing unit (CPU) in the computer. In addition, a program for performing each processing is stored in a storage device such as a hard disk or a ROM, and is read out and executed in the ROM or the RAM.

  Each processing of the above embodiment may be realized by hardware, or may be realized by software (including a case where the processing is realized together with an OS (Operating System), middleware, or a predetermined library). Further, it may be realized by mixed processing of software and hardware.

  Moreover, the execution order of the processing method in the said embodiment is not necessarily restricted to description of the said embodiment, The execution order can be changed in the range which does not deviate from the summary of invention.

  A computer program that causes a computer to execute the above-described method and a computer-readable recording medium that records the program are included in the scope of the present invention. Here, examples of the computer-readable recording medium include a flexible disk, hard disk, CD-ROM, MO, DVD, DVD-ROM, DVD-RAM, large-capacity DVD, next-generation DVD, and semiconductor memory. .

  The computer program is not limited to the one recorded on the recording medium, and may be transmitted via a telecommunication line, a wireless or wired communication line, a network represented by the Internet, or the like.

  The specific configuration of the present invention is not limited to the above-described embodiment, and various changes and modifications can be made without departing from the scope of the invention.

1000 Communication system Tx1 Data transmission device 1 FE part (front end part)
2 FFT unit for payload 3 FFT unit for preamble 4 Division unit 5 Inverse Fourier transform unit 6 Time domain signal adjustment unit 61 Noise reduction unit 62 Impulse shift unit 63 Interpolation unit 7 Fourier transform unit 8 Phase adjustment unit 10 Transmission characteristic correction unit

Claims (5)

A transmission signal having a preamble portion including a synchronization signal and a payload portion including a data signal, and having a roll-off period for preventing phase discontinuity, wherein the number of samples of the synchronization signal is equal to that of the data signal A data receiving device for receiving the transmission signal smaller than the number of samples,
A front end for receiving the transmission signal;
Based on the synchronization signal, a synchronization detection unit that executes synchronization detection processing and acquires synchronization timing;
Based on the synchronization timing acquired by the synchronization detection unit, the synchronization signal is acquired from the front end unit, a preamble FFT window shifted by a first shift amount δ is set for the synchronization signal, A preamble FFT unit that performs FFT processing on the synchronization signal by the preamble FFT window;
A transmission characteristic data acquisition unit that acquires transmission characteristic data based on the signal acquired by the preamble FFT unit;
An inverse Fourier transform unit that performs an inverse Fourier transform process on the transmission characteristic data acquired by the transmission characteristic data acquisition unit;
A time domain signal adjustment unit that performs a shift process and an interpolation process with a time domain shift amount M on the signal acquired by the inverse Fourier transform unit;
A Fourier transform unit that performs a Fourier transform process on the signal acquired by the time domain signal adjustment unit;
A phase adjustment unit that performs phase adjustment processing corresponding to the reverse shift processing of the shift processing by the time domain signal adjustment unit, and acquires transmission path information, on the signal acquired by the Fourier transform unit;
A buffer unit for holding the transmission path information acquired by the phase adjustment unit;
Based on the synchronization detection timing acquired by the synchronization detection unit, the data signal is acquired from the front end unit, and based on the first shift amount δ and the second shift amount RI corresponding to the roll-off period RI. Then, an FFT window for a data block that is shifted by a shift amount (RI + δ) is set for the data signal, and an FFT process is performed on the data signal by the FFT block for the data block. And
Based on the transmission path information held in the buffer unit, a transmission characteristic correction process is performed on the signal acquired by the payload FFT unit, and the second shift amount RI corresponding to the roll-off period RI is set. A transmission characteristic correction unit for performing phase correction based on
A data receiving apparatus comprising: The time domain signal adjustment unit
For the signal acquired by the inverse Fourier transform unit, noise reduction processing is performed by replacing the signal value of the signal component equal to or less than the threshold Th with a signal value whose absolute value is smaller than the absolute value of the original signal value. A noise reduction processing unit,
An impulse shift unit that performs shift processing by the time domain shift amount M on the signal acquired by the noise reduction processing unit;
An interpolation unit that performs an interpolation process on the signal acquired by the impulse shift unit such that the number of samples of the signal is the same as the number of samples of the data signal;
Comprising
The data receiving device according to claim 1. The noise reduction processing unit
A noise reduction process is executed by setting the signal value of the signal component equal to or less than the threshold Th to the signal value “0” for the signal acquired by the inverse Fourier transform unit.
The data receiving device according to claim 2. A transmission signal having a preamble portion including a synchronization signal and a payload portion including a data signal, and having a roll-off period for preventing phase discontinuity, wherein the number of samples of the synchronization signal is equal to that of the data signal A data receiving method for receiving the transmission signal smaller than the number of samples,
A front end step for receiving the transmission signal;
Based on the synchronization signal, a synchronization detection step of performing synchronization detection processing and acquiring synchronization timing;
Based on the synchronization timing acquired by the synchronization detection step, the synchronization signal is acquired, a preamble FFT window shifted by a first shift amount δ is set for the synchronization signal, and the synchronization signal is A preamble FFT step for performing FFT processing by the preamble FFT window;
A transmission characteristic data acquisition step for acquiring transmission characteristic data based on the signal acquired by the preamble FFT step;
An inverse Fourier transform step of performing an inverse Fourier transform process on the transmission characteristic data acquired by the transmission characteristic data acquisition step;
A time domain signal adjustment step of performing a shift process and an interpolation process with a time domain shift amount M on the signal acquired by the inverse Fourier transform step;
A Fourier transform step for performing a Fourier transform process on the signal acquired by the time domain signal adjustment step;
A phase adjustment step for obtaining transmission path information by performing a phase adjustment process corresponding to the reverse shift process of the shift process by the time domain signal adjustment step on the signal obtained by the Fourier transform step;
Holding step for holding the transmission path information acquired by the phase adjustment step;
The data signal is acquired based on the synchronization timing acquired by the synchronization detection step, and the data signal is determined based on the first shift amount δ and the second shift amount RI corresponding to the roll-off period RI. On the other hand, an FFT window for payload that sets an FFT window for data block shifted by a shift amount (RI + δ) and executes FFT processing on the data signal by the FFT window for data block;
Based on the transmission path information held in the holding step, a transmission characteristic correction process is performed on the signal acquired by the payload FFT step, and based on a second shift amount RI corresponding to the roll-off period RI. A transmission characteristic correction step for performing phase correction;
A program for causing a computer to execute a data receiving method. A transmission signal having a preamble portion including a synchronization signal and a payload portion including a data signal, and having a roll-off period for preventing phase discontinuity, wherein the number of samples of the synchronization signal is equal to that of the data signal An integrated circuit used in a data receiving apparatus that receives the transmission signal smaller than the number of samples,
A front end for receiving the transmission signal;
Based on the synchronization signal, a synchronization detection unit that executes synchronization detection processing and acquires synchronization timing;
Based on the synchronization timing acquired by the synchronization detection unit, the synchronization signal is acquired from the front end unit, a preamble FFT window shifted by a first shift amount δ is set for the synchronization signal, A preamble FFT unit that performs FFT processing on the synchronization signal by the preamble FFT window;
A transmission characteristic data acquisition unit that acquires transmission characteristic data based on the signal acquired by the preamble FFT unit;
An inverse Fourier transform unit that performs an inverse Fourier transform process on the transmission characteristic data acquired by the transmission characteristic data acquisition unit;
A time domain signal adjustment unit that performs a shift process and an interpolation process with a time domain shift amount M on the signal acquired by the inverse Fourier transform unit;
A Fourier transform unit that performs a Fourier transform process on the signal acquired by the time domain signal adjustment unit;
A phase adjustment unit that performs phase adjustment processing corresponding to the reverse shift processing of the shift processing by the time domain signal adjustment unit, and acquires transmission path information, on the signal acquired by the Fourier transform unit;
A buffer unit for holding the transmission path information acquired by the phase adjustment unit;
Based on the synchronization timing acquired by the synchronization detection unit, the data signal is acquired from the front end unit, and based on the first shift amount δ and the second shift amount RI corresponding to the roll-off period RI. A payload FFT unit that sets an FFT window for a data block shifted by a shift amount (RI + δ) for the data signal, and performs an FFT process on the data signal by the FFT block for the data block When,
Based on the transmission path information held in the buffer unit, a transmission characteristic correction process is performed on the signal acquired by the payload FFT unit, and the second shift amount RI corresponding to the roll-off period RI is set. A transmission characteristic correction unit for performing phase correction based on
An integrated circuit comprising:

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