JP3689768B2 - Orthogonal frequency division multiplex signal receiving apparatus, orthogonal frequency division multiplex signal receiving method, and program - Google Patents

Description

ここで、ｘ_ｓ（ｍ）＝ｘ_ｍ、ｙ_ｓ（ｎ）＝ｙ_ｎとする。また、＊は、共役複素数であることを示す。
【００３５】
次に、第１及び第２の離散フーリエ変換器４、５は、それぞれ並列データｙ、ｘに離散フーリエ変換を施すことから、１シンボル分のデータ数をＮとすれば、等化後のデータＹ_ｋ及び受信シンボルＸ_ｋは、それぞれ数式２、３を用いて示すことができる。
【００３６】
【数２】

【００３７】
【数３】

【００３８】
ここで、周波数ｆ_ｐｉのキャリアに対応して直交周波数分割多重信号受信装置１００にて既知であるパイロット信号をＧ_ｐｉとし、パイロット信号を伝送するキャリアの周波数ｆ_ｐｉにおける等化後のデータＹ_ｋの値をＹ_ｐｉとすると、これらの残差εは、数式４を用いて求めることができる。
【００３９】
【数４】

なお、Ｐは、パイロット信号の数である。
【００４０】
このようにして求められる残差εを用いたＬＭＳアルゴリズムによると、フィルタ係数ｃ_ｍ（ｍ＝０、１、…、Ｌ−１）は、α＞０となるパラメータαを用いて、数式５のように更新すればよい。
【００４１】
【数５】

【００４２】
ここで、数式２〜４を用いると、数式６に示す関係が成立する。
【００４３】
【数６】

【００４４】
従って、数式５は、数式７のように示すことができる。
【００４５】
【数７】

【００４６】
そこで、フィルタ係数ｃ_ｍを生成する係数制御器６を、図３に示すように構成することにより、ＬＭＳアルゴリズムに従ったフィルタ係数ｃ_ｍの更新が可能となる。なお、ここでは一例として、パイロット信号の数Ｐ＝３とした。
また、ｚ計算器２３〜２５は、いずれも図４に示すような同一の構成を有している。
【００４７】
すなわち、各ｚ計算器２３〜２５は、加算器３１により、パイロット信号を伝送するキャリアの周波数ｆ_ｐｉにおける等化後のデータＹ_ｐｉの共役複素数と、直交周波数分割多重信号受信装置１００にて既知であるパイロット信号Ｇ_ｐｉの共役複素数との差を求める。また、各ｚ計算器２３〜２５は移相係数計算器３２により、パイロット信号の挿入位置及びフィルタ係数ｃ_ｍを掛け合わせる信号に加えられた遅延量に対応した移相だけ回転させる作用を有する移相係数ｅｘｐ（−ｊ２πａ／Ｎ）を求める。
各ｚ計算器２３〜２５は、乗算器３３を用いて、加算器３１により求められた値に、移相係数計算器３２により求められた移相係数及び受信シンボルＸ_ｐｉを掛け合わせて、加算器２６に出力する。
【００４８】
加算器２６は、各ｚ計算器２３〜２５から出力された値を加え合わせて合成し、乗算器２７に送る。
乗算器２７は、加算器２６により合成された値にパラメータαを負値化したものを掛け合わせ、加算器２８に送る。
加算器２８は、係数レジスタ２９に記憶されているフィルタ係数ｃ_ｍに、乗算器２７から受けた値を加え合わせ、係数レジスタ２９の記憶内容を更新する。これにより、フィルタ係数ｃ_ｍを更新することができる。
【００４９】
つまり、係数制御器６は、適応フィルタ１の入力となる受信データｘ_ｓをフーリエ変換することにより特定された受信シンボルＸと、適応フィルタ１の出力となる直列データｙ_ｓをフーリエ変換することにより特定されたデータＹとを用いて、適応フィルタ１のフィルタ係数ｃ_ｍをＬＭＳアルゴリズムに従って制御する。
これにより、残差εを低減させるように適応フィルタ１を制御して、受信データｘ_ｓを等化することができ、伝送路応答を適切に補償して伝送データを復調することができる。
【００５０】
以上説明したように、この発明によれば、等化後のデータＹ_ｋ及び受信シンボルＸ_ｋを用いてフィルタ係数ｃ_ｍを求め、受信データｘ_ｓをフィルタリングしたのちフーリエ変換を施すことにより、等化後のデータＹ_ｋを復調する。これにより、伝送路の状態変化に対応してフィルタ係数ｃ_ｍを変更することができ、伝送路応答を適切に補償して伝送データを復調することができる。
また、係数制御器６は、ＬＭＳアルゴリズムに従って、残差εを低減させるようにフィルタ係数ｃ_ｍを制御することから、反射波が複数となる複雑な伝送路であっても、伝送路応答を適切に補償して伝送データを復調することができる。
【００５１】
この発明は、上記実施の形態に限定されず、様々な変形及び応用が可能である。
例えば、図５に示すように、適応フィルタ１がフィルタリングした直列データｙ_ｓを、ＢＰＦ（Band Pass Filter）４０を介してＦＭ（Frequency Modulation）復調器４１に供給することで、同一帯域内で伝送されたアナログ変調波に対しても伝送路応答を補償して、復調することができる。なお、ＦＭ復調器４１は、ＡＭ（Amplitude Modulation）復調器といった任意のアナログ復調器であってもよい。
【００５２】
また、例えば図６に示すように、等化後のデータＹから、従来と同様にしてパイロット信号を検出し、伝送路応答を補償した残差をさらに等化するようにしてもよい。なお、図６において、従来の受信装置と同一の構成には同一の符号を付している。
これにより、適応フィルタ１が受信データｘ_ｓを等化することより補償した伝送路応答の残差を除去することができ、伝送路応答をより適切に補償して伝送データを復調することができる。
【００５３】
上記実施の形態では、直交周波数分割多重信号受信装置１００はハードウェアの回路構成により実現されるものとして説明したが、これに限定されず、コンピュータに動作プログラムを実行させることによっても実現可能である。
すなわち、コンピュータに、上述の直交周波数分割多重信号受信装置１００の各部位に相当する処理を実行させるための動作プログラムを作成してメモリに記憶させる。この動作プログラムを、ＣＰＵ（Central Processing Unit）やＤＳＰ（Digital Signal Processor）といったプロセッサ等を備えて構成されるコンピュータに実行させることにより、上述の動作を実行する直交周波数分割多重信号受信装置を構築することができる。
また、動作プログラムは、ＦＤ、ＣＤ−ＲＯＭ、ＤＶＤなどのコンピュータ読み取り可能な記録媒体に記録して配布するものとしてもよい。さらに、インターネット上のサーバ装置が有するディスク装置等に動作プログラムを記録しておき、コンピュータに、例えば、搬送波に重畳して、ダウンロード等するものとしてもよい。
【００５４】
【発明の効果】
以上の説明のように、この発明によれば、反射波が複数となる複雑な伝送路の場合等であっても、伝送路応答を適切に補償して伝送データを復調することができる。
【図面の簡単な説明】
【図１】この発明の実施の形態に係る直交周波数分割多重信号受信装置の構成を示す図である。
【図２】適応フィルタの構成を示す図である。
【図３】係数制御器の構成を示す図である。
【図４】ｚ計算器の構成を示す図である。
【図５】この発明の実施の形態に係る直交周波数分割多重信号受信装置の変形例を示す図である。
【図６】この発明の実施の形態に係る直交周波数分割多重信号受信装置の変形例を示す図である。
【図７】直交周波数分割多重信号を受信する従来の受信装置の構成を示す図である。
【図８】補間器による伝送路応答の補間について説明するための図である。
【符号の説明】
１ 適応フィルタ
２、３、５０ 直並列変換器
４、５、５１ 離散フーリエ変換器
６ 係数制御器
１０_１〜１０_Ｌ−１ 遅延回路
１１_０〜１１_Ｌ−１、２０〜２２、２７、３３ 乗算器
１２、２６、２８、３１ 加算器
２３〜２５ ｚ計算器
２９ 係数レジスタ
３０ 複素共役器
３２ 移相係数計算器
４０ ＢＰＦ
４１ ＦＭ復調器
５２ 除算器
５３ 補間器
５４ パイロット検出器
１００ 直交周波数分割多重信号受信装置[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an orthogonal frequency division multiplexing signal receiving apparatus that receives a signal subjected to orthogonal frequency division multiplexing and demodulates transmission data, and in particular, can properly demodulate transmission data by properly compensating a transmission path response. The present invention relates to an orthogonal frequency division multiplex signal receiving apparatus.
[0002]
[Prior art]
As one of systems for transmitting digital signals, an orthogonal frequency division multiplexing (OFDM) system is known.
In this orthogonal frequency division multiplexing method, a large number of carriers are multiplexed and transmitted within one channel band, and a predetermined carrier included in the large number of carriers is used to change the amplitude and phase known on the receiving side. A pilot signal having the same is transmitted.
A conventional receiving apparatus that receives an orthogonal frequency division multiplexing signal composed of a large number of carrier signals and demodulates transmission data can compensate the transmission line response to some extent by using the pilot signal.
[0003]
That is, in the conventional receiving apparatus having the configuration as shown in FIG. 7, the serial-parallel converter 50 receives received data obtained by sampling an intermediate frequency signal by an A / D (Analog / Digital) converter, for example. Receives x _s and aggregates it into parallel data x for one symbol. The discrete Fourier transformer 51 demodulates the transmission data by performing Fourier transform on the parallel data x sent from the serial / parallel converter 50 to obtain a reception symbol X. In addition, the pilot detector 54 detects a change in amplitude and phase due to the multipath of the transmission path from the pilot signal extracted from the received symbol X, for example, transmission at the pilot frequency f _pi (i = 1, 2,...). The road response H _pi is specified. The interpolator 53 interpolates the transmission line response H _pi to estimate the transmission line response H _di at the data frequency f _di . The divider 52 can obtain the equalized data Y by calculating Y _di = X _di / H _di .
[0004]
Here, the pilot signal is transmitted using a plurality of carriers having a predetermined frequency interval. For example, the pilot signal is transmitted using four carriers having frequencies f _p1 , f _p2 , f _p3 , and f _p4 shown in FIG. The carrier for transmitting the data signal has a predetermined frequency interval narrower than the frequency interval of the carrier transmitting the pilot signal. That is, for example, a data signal is transmitted by a carrier having the frequencies f _d1 , f _d2 ,... Shown in FIG.
The interpolator 53 estimates the transmission line response H _di at the frequency f _di by performing zero-order or primary interpolation on the transmission line response at the frequency f _pi (i = 1, 2, 3, 4).
[0005]
[Problems to be solved by the invention]
In the above prior art, in the case of a simple transmission line with only one reflected wave, interpolation of the transmission line response by the interpolator 53 is effective. However, in the case of a complicated transmission line on which a large number of reflected waves are superimposed, there is a problem that the transmission line response cannot be compensated.
[0006]
In addition, when digital data is transmitted by the orthogonal frequency division multiplexing system and an analog modulated wave is multiplexed and transmitted within the same band, there is a problem that a transmission line response cannot be compensated for the analog modulated wave.
[0007]
The present invention has been made in view of the above circumstances, and an object thereof is to provide an orthogonal frequency division multiplex signal receiving apparatus capable of appropriately compensating a transmission path response and demodulating transmission data.
[0008]
[Means for Solving the Problems]
In order to achieve the above object, an orthogonal frequency division multiplex signal receiving apparatus according to a first aspect of the present invention provides:
Demodulating transmission data from received data obtained by sampling an intermediate frequency signal subjected to orthogonal frequency division multiplexing,
Demodulating means for demodulating transmission data by performing discrete Fourier transform after equalizing received data with an adaptive filter,
The demodulating means includes a received symbol obtained by performing discrete Fourier transform on the received data input to the adaptive filter, and demodulated data obtained by performing discrete Fourier transform on the data output from the adaptive filter. And a coefficient control means for controlling a filter coefficient in the adaptive filter.
It is characterized by that.
[0009]
According to the present invention, the reception data is demodulated by performing the discrete Fourier transform after equalizing the reception data with the adaptive filter.
Thereby, transmission data can be demodulated by appropriately compensating the transmission line response.
[0011]
The demodulator preferably includes an analog demodulator that filters the data output from the adaptive filter and extracts an analog modulated wave.
Thereby, when the analog modulated wave is multiplexed and transmitted in the same band, the transmission line response to the analog modulated wave can be appropriately compensated.
[0012]
Further, the demodulating means detects a pilot signal from demodulated data obtained by performing discrete Fourier transform on the data output from the adaptive filter, and estimates and estimates a transmission line response based on the detection result, It is desirable to equalize by dividing the demodulated data by the estimated transmission line response.
Thereby, the residual of the transmission line response compensated by equalization of the adaptive filter can be removed, and the transmission line response can be compensated more appropriately.
[0013]
An orthogonal frequency division multiplex signal receiver according to a second aspect of the present invention provides:
Demodulating transmission data from received data obtained by sampling an intermediate frequency signal subjected to orthogonal frequency division multiplexing,
Filtering means for filtering and equalizing received data with variable filter coefficients;
First Fourier transform means for specifying demodulated data by performing discrete Fourier transform on the data equalized by the filtering means;
Second Fourier transform means for performing a Fourier transform on received data to identify a received symbol;
Coefficient control means for controlling the filter coefficient of the filtering means using the demodulated data specified by the first Fourier transform means and the received symbol specified by the second Fourier transform means;
It is characterized by that.
[0014]
According to this invention, the coefficient control means controls the filter coefficient of the filtering means using the demodulated data specified by the first Fourier transform means and the received symbol specified by the second Fourier transform means. . The filtering means specifies the demodulated data by filtering the received data and applying discrete Fourier transform by the first Fourier transform means.
Thereby, transmission data can be demodulated by appropriately compensating the transmission line response.
[0015]
More specifically, the coefficient control means uses an LMS (Least Mean Square) using the demodulated data specified by the first Fourier transform means and the received symbols specified by the second Fourier transform means. It is desirable to control the filter coefficient of the filtering means according to an algorithm.
[0016]
The coefficient control means reduces the residual between the demodulated data specified by the first Fourier transform means and the pilot signal transmitted and the pilot signal whose amplitude and phase are known on the receiving side. It is desirable to control the filter coefficient of the filtering means.
[0017]
An orthogonal frequency division multiplex signal receiving method according to a third aspect of the present invention provides:
A method of demodulating transmission data from received data obtained by sampling an intermediate frequency signal subjected to orthogonal frequency division multiplexing,
A filtering step for filtering and equalizing received data with variable filter coefficients;
A first Fourier transform step of performing a discrete Fourier transform on the data equalized in the filtering step to identify demodulated data;
A second Fourier transform step of performing discrete Fourier transform on the received data to identify a received symbol;
A coefficient control step for controlling a filter coefficient in the filtering step by using the demodulated data specified in the first Fourier transform step and the received symbol specified in the second Fourier transform step;
It is characterized by that.
[0018]
A program according to the fourth aspect of the present invention is:
On the computer,
A filtering process for equalizing the received data by filtering with variable filter coefficients;
A first Fourier transform process for performing a discrete Fourier transform on the data equalized by the filtering process to identify demodulated data;
A second Fourier transform process for performing discrete Fourier transform on received data to identify a received symbol;
Using the demodulated data identified by the first Fourier transform process and the received symbol identified by the second Fourier transform process, to execute a coefficient control process for controlling a filter coefficient in the filtering process,
It is characterized by that.
[0019]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, an orthogonal frequency division multiplex signal receiving apparatus according to an embodiment of the present invention will be described in detail with reference to the drawings.
[0020]
FIG. 1 is a diagram showing a configuration of an orthogonal frequency division multiplex signal receiving apparatus 100 according to an embodiment of the present invention.
As shown in the figure, the orthogonal frequency division multiplex signal receiving apparatus 100 includes an adaptive filter 1, first and second series-parallel converters 2 and 3, and first and second discrete Fourier transformers 4 and 5. The coefficient controller 6 is provided.
[0021]
The adaptive filter 1 is a FIR (Finite Impulse Response) filter having, for example, L taps (L is an integer).
In other words, the adaptive filter 1, the received data x _s obtained by sampling the example received signal filtered by the filter coefficient variable, to generate a serial data y _s.
Therefore, as shown in FIG. 2, the adaptive filter 1 includes (L−1) delay circuits 10 ₁ , 10 ₂ ,..., 10 _L−1 for delaying received data x _s and L pieces of delay circuits. Multipliers 11 ₀ , 11 ₁ ,..., 11 _L−1 and an adder 12 are provided.
[0022]
The delay circuits 10 ₁ to 10 _L-1 are each composed of a delay element having a transfer function z ⁻¹ and are cascade-connected to each other to delay received data x _s .
Here, the transfer function z ⁻¹ is a transfer function indicating an action of delaying a signal by a time corresponding to one sampling step in z conversion.
[0023]
The multipliers 11 _{0 to} 11 _{L−1 respectively} convert the received data x _s and the data obtained by delaying the received data x _s by the delay circuits 10 ₁ to 10 _L−1 to the filter coefficients c ₀ and c generated by the coefficient controller 6. ₁ ,..., C for multiplying _L-1 .
[0024]
The adder 12 adds and combines the signals multiplied by the filter coefficients by the multipliers 11 _{0 to} 11 _L−1 to generate serial data y _s .
[0025]
The first and second series-parallel converters 2 and 3 shown in FIG. 1 are for converting serial data constituting one data series into parallel data constituting a plurality of data series.
That is, the first serial-parallel converter 2, aggregate serial data y _s received from the adaptive filter 1, as parallel data y for one symbol, and sends the first discrete Fourier transformer 4. The second serial-parallel converter 3 aggregates the reception data x _s that is serial data obtained by sampling the reception signal, and converts the received data x _s into parallel data x for one symbol as a second discrete Fourier transformer. Send to 5.
[0026]
The first and second discrete Fourier transformers 4 and 5 are for converting time-series data into frequency component data by performing Fourier transform such as Discrete Fourier Transform (DFT) on parallel data. It is.
That is, the first discrete Fourier transformer 4 demodulates the transmission data by performing Fourier transform using the parallel data y received from the first serial / parallel converter 2 and specifies the equalized data Y To do. The second discrete Fourier transformer 5 performs a Fourier transform using the parallel data x received from the second serial / parallel converter 3 and identifies the received symbol X.
[0027]
The coefficient controller 6 is for controlling the filter coefficient of the adaptive filter 1.
That is, the coefficient controller 6 generates filter coefficients c _{0 to} c _L−1 for the multipliers 11 _{0 to} 11 _L−1 to multiply the data such as the received data x _s , and the adaptive filter 1 as the coefficient c. To supply. Here, the coefficient controller 6 uses the equalized data Y specified by the first discrete Fourier transformer 4 and the received symbol X specified by the second discrete Fourier transformer 5, for example, LMS; calculated each filter coefficients _c 0 _{~c L-1} according to (Least Mean Square least square) algorithm, to generate the coefficient c.
[0028]
The operation of orthogonal frequency division multiplex signal receiving apparatus 100 according to the embodiment of the present invention will be described below.
The orthogonal frequency division multiplexing signal receiving apparatus 100 receives received data x _s obtained by sampling an intermediate frequency signal, which is a received signal, by an A / D (Analog / Digital) converter (not shown), for example. This is input to the adaptive filter 1 and the second series-parallel converter 3.
[0029]
The adaptive filter 1 multiplies the coefficient c generated by the coefficient controller 6 while delaying the reception data x _s by the delay circuits 10 ₁ to 10 _{L−1 and} synthesizes the received data x s by the adder 12. to generate a serial data y _s obtained by filtering the _s.
The adaptive filter 1 sends the generated serial data y _s to the first serial / parallel converter 2.
[0030]
The first serial / parallel converter 2 aggregates the serial data y _s received from the adaptive filter 1 and sends it to the first discrete Fourier transformer 4 as parallel data y for one symbol.
The first discrete Fourier transformer 4 demodulates the transmission data by performing Fourier transform on the parallel data y to convert the time series data into frequency component data, and outputs the demodulated data Y as equalized data Y. At this time, the first discrete Fourier transformer 4 sends the equalized data Y to the coefficient controller 6.
[0031]
The second serial / parallel converter 3 aggregates the received data x _s and sends it to the second discrete Fourier transformer 5 as parallel data x for one symbol.
The second discrete Fourier transformer 5 performs a Fourier transform on the parallel data x and converts the time series data into frequency component data to identify the received symbol X and sends it to the coefficient controller 6.
[0032]
Next, an operation in which the coefficient controller 6 determines the coefficient c composed of the filter coefficients c _{0 to} c _L−1 will be described.
In the following, it is assumed that the received data x _s is represented by a complex number as x _s = x _i = x _Ii + jx _Qi . Here, _{x I} is the in-phase component of the received data _{x s, x Q} is the quadrature component of the received data _{x s.}
[0033]
First, from the configuration of the adaptive filter 1, serial data y _s can be shown using Equation 1.
[0034]
[Expression 1]

_{Here, x s (m) = x} m, and _{y s (n) = y n} . * Indicates that it is a conjugate complex number.
[0035]
Next, since the first and second discrete Fourier transformers 4 and 5 perform discrete Fourier transform on the parallel data y and x, respectively, if the number of data for one symbol is N, the data after equalization Y _k and received symbol X _k can be expressed using Equations 2 and 3, respectively.
[0036]
[Expression 2]

[0037]
[Equation 3]

[0038]
Here, the pilot signal is known at orthogonal frequency division multiplex signal receiving apparatus 100 corresponding to the carrier frequency f _pi and G _pi, data Y _k after equalization in the frequency f _pi carrier that transmits a pilot signal The residual ε can be obtained by using Equation 4 where the value of Y is Y _pi .
[0039]
[Expression 4]

Note that P is the number of pilot signals.
[0040]
According to the LMS algorithm using the residual ε thus obtained, the filter coefficient c _m (m = 0, 1,..., L−1) is expressed by the following equation 5 using the parameter α where α> 0. It should be updated as follows.
[0041]
[Equation 5]

[0042]
Here, when Expressions 2 to 4 are used, the relationship shown in Expression 6 is established.
[0043]
[Formula 6]

[0044]
Therefore, Equation 5 can be expressed as Equation 7.
[0045]
[Expression 7]

[0046]
Therefore, by configuring the coefficient controller 6 that generates the filter coefficient _cm as shown in FIG. 3, it is possible to update the filter coefficient _cm according to the LMS algorithm. Here, as an example, the number of pilot signals P = 3.
The z calculators 23 to 25 all have the same configuration as shown in FIG.
[0047]
That is, each of the z calculators 23 to 25 is known by the adder 31 from the conjugate complex number of the data Y _pi after equalization at the frequency f _pi of the carrier transmitting the pilot signal and the orthogonal frequency division multiplex signal receiving apparatus 100. The difference from the conjugate complex number of the pilot signal G _pi is obtained. Each of the z calculators 23 to 25 is rotated by a phase shift coefficient calculator 32 by a phase shift corresponding to the delay amount added to the signal multiplied by the pilot signal insertion position and the filter coefficient _cm. A phase coefficient exp (−j2πa / N) is obtained.
Each z calculator 23 to 25 uses the multiplier 33 to multiply the value obtained by the adder 31 by the phase shift coefficient obtained by the phase shift coefficient calculator 32 and the received symbol X _pi and add Output to the device 26.
[0048]
The adder 26 adds and synthesizes the values output from the z calculators 23 to 25, and sends them to the multiplier 27.
The multiplier 27 multiplies the value synthesized by the adder 26 by the negative value of the parameter α and sends the result to the adder 28.
The adder 28 adds the value received from the multiplier 27 to the filter coefficient _cm stored in the coefficient register 29 and updates the stored contents of the coefficient register 29. Thereby, the filter coefficient _cm can be updated.
[0049]
That is, the coefficient controller 6 performs Fourier transform on the received symbol X specified by Fourier transforming the received data x _s that is input to the adaptive filter 1 and the serial data y _s that is output from the adaptive filter 1. Using the identified data Y, the filter coefficient _cm of the adaptive filter 1 is controlled according to the LMS algorithm.
Thus, by controlling the adaptive filter 1 to reduce the residual epsilon, it is possible to equalize the received data x _s, it is possible to demodulate the transmission data properly compensate for the channel response.
[0050]
As described above, according to the present invention, the filter coefficient _cm is obtained using the equalized data Y _k and the received symbol X _k , the received data x _s is filtered, and then subjected to Fourier transform, etc. Demodulated data _Yk is demodulated. As a result, the filter coefficient _cm can be changed in response to a change in the state of the transmission line, and the transmission data can be appropriately compensated to demodulate the transmission data.
In addition, the coefficient controller 6 controls the filter coefficient _cm so as to reduce the residual ε according to the LMS algorithm. Therefore, the transmission line response is appropriately determined even for a complicated transmission line with a plurality of reflected waves. The transmission data can be demodulated with compensation.
[0051]
The present invention is not limited to the above embodiment, and various modifications and applications are possible.
For example, as shown in FIG. 5, the serial data y _s of the adaptive filter 1 is filtered, by supplying the FM (Frequency Modulation) demodulator 41 through a BPF (Band Pass Filter) 40, transmitted in the same band It is also possible to demodulate and compensate the transmission path response for the analog modulated wave that has been made. The FM demodulator 41 may be any analog demodulator such as an AM (Amplitude Modulation) demodulator.
[0052]
Further, for example, as shown in FIG. 6, a pilot signal may be detected from the equalized data Y in the same manner as in the prior art, and the residual obtained by compensating the transmission line response may be further equalized. In FIG. 6, the same components as those of the conventional receiving apparatus are denoted by the same reference numerals.
Thereby, the residual of the transmission path response compensated by the adaptive filter 1 equalizing the reception data x _s can be removed, and the transmission data can be more appropriately compensated to demodulate the transmission data. .
[0053]
In the above embodiment, the orthogonal frequency division multiplex signal receiving apparatus 100 has been described as being realized by a hardware circuit configuration, but is not limited to this, and can also be realized by causing a computer to execute an operation program. .
That is, an operation program for causing a computer to execute processing corresponding to each part of the above-described orthogonal frequency division multiplexing signal receiving apparatus 100 is created and stored in a memory. An orthogonal frequency division multiplex signal receiving apparatus that performs the above-described operation is constructed by causing a computer configured to include a processor such as a CPU (Central Processing Unit) or a DSP (Digital Signal Processor) to execute this operation program. be able to.
Further, the operation program may be recorded and distributed on a computer-readable recording medium such as an FD, a CD-ROM, or a DVD. Furthermore, an operation program may be recorded in a disk device or the like included in a server device on the Internet, and may be downloaded onto a computer, for example, superimposed on a carrier wave.
[0054]
【The invention's effect】
As described above, according to the present invention, even in the case of a complicated transmission line having a plurality of reflected waves, the transmission data can be appropriately compensated and the transmission data can be demodulated.
[Brief description of the drawings]
FIG. 1 is a diagram showing a configuration of an orthogonal frequency division multiplex signal receiving apparatus according to an embodiment of the present invention.
FIG. 2 is a diagram illustrating a configuration of an adaptive filter.
FIG. 3 is a diagram illustrating a configuration of a coefficient controller.
FIG. 4 is a diagram illustrating a configuration of a z calculator.
FIG. 5 is a diagram showing a modification of the orthogonal frequency division multiplex signal receiving apparatus according to the embodiment of the present invention.
FIG. 6 is a diagram showing a modification of the orthogonal frequency division multiplex signal receiving apparatus according to the embodiment of the present invention.
FIG. 7 is a diagram illustrating a configuration of a conventional receiving apparatus that receives orthogonal frequency division multiplexing signals.
FIG. 8 is a diagram for explaining transmission path response interpolation by an interpolator;
[Explanation of symbols]
1 adaptive filter 2,3,50 deserializer 4,5,51 discrete Fourier transformer 6 coefficient controller ₁₀ 1 _{to 10 L-1} delay circuit ₁₁ 0 _~11 L-1, _20~22,27,33 multiplication Units 12, 26, 28, 31 adders 23-25 z calculator 29 coefficient register 30 complex conjugate unit 32 phase shift coefficient calculator 40 BPF
41 FM demodulator 52 Divider 53 Interpolator 54 Pilot detector 100 Orthogonal frequency division multiplex signal receiver

Claims (8)

An orthogonal frequency division multiplex signal receiving apparatus for demodulating transmission data from reception data obtained by sampling an intermediate frequency signal subjected to orthogonal frequency division multiplexing,
Demodulating means for demodulating transmission data by performing discrete Fourier transform after equalizing received data with an adaptive filter,
The demodulating means includes a received symbol obtained by performing discrete Fourier transform on the received data input to the adaptive filter, and demodulated data obtained by performing discrete Fourier transform on the data output from the adaptive filter. And a coefficient control means for controlling a filter coefficient in the adaptive filter.
An orthogonal frequency division multiplex signal receiving apparatus. The demodulating means includes analog demodulating means for filtering the data output from the adaptive filter and extracting an analog modulated wave .
The orthogonal frequency division multiplex signal receiver according to claim 1 . The demodulating means detects a pilot signal from demodulated data obtained by subjecting the data output from the adaptive filter to discrete Fourier transform, estimates and interpolates a transmission line response based on the detection result, and generates demodulated data Is divided by the estimated channel response,
The orthogonal frequency division multiplex signal receiver according to claim 1 . An orthogonal frequency division multiplex signal receiving apparatus for demodulating transmission data from reception data obtained by sampling an intermediate frequency signal subjected to orthogonal frequency division multiplexing,
Filtering means for filtering and equalizing received data with variable filter coefficients;
First Fourier transform means for specifying demodulated data by performing discrete Fourier transform on the data equalized by the filtering means;
Second Fourier transform means for performing a Fourier transform on received data to identify a received symbol;
Coefficient control means for controlling the filter coefficient of the filtering means using the demodulated data specified by the first Fourier transform means and the received symbol specified by the second Fourier transform means;
An orthogonal frequency division multiplex signal receiving apparatus. The coefficient control means uses the demodulated data specified by the first Fourier transform means and the received symbol specified by the second Fourier transform means, and uses the filtering means according to an LMS (Least Mean Square) algorithm. Control the filter coefficients of
The orthogonal frequency division multiplex signal receiver according to claim 4 . The coefficient control means reduces the residual between the demodulated data specified by the first Fourier transform means and the pilot signal transmitted and the pilot signal whose amplitude and phase are known on the receiving side. Controlling filter coefficients of the filtering means;
The orthogonal frequency division multiplex signal receiver according to claim 4 or 5 , An orthogonal frequency division multiplexing signal reception method for demodulating transmission data from reception data obtained by sampling an intermediate frequency signal subjected to orthogonal frequency division multiplexing,
A filtering step for filtering and equalizing received data with variable filter coefficients;
A first Fourier transform step of performing a discrete Fourier transform on the data equalized in the filtering step to identify demodulated data;
A second Fourier transform step of performing discrete Fourier transform on the received data to identify a received symbol;
A coefficient control step for controlling a filter coefficient in the filtering step by using the demodulated data specified in the first Fourier transform step and the received symbol specified in the second Fourier transform step;
An orthogonal frequency division multiplex signal receiving method. On the computer,
A filtering process for equalizing the received data by filtering with variable filter coefficients;
A first Fourier transform process for performing a discrete Fourier transform on the data equalized by the filtering process to identify demodulated data;
A second Fourier transform process for performing discrete Fourier transform on received data to identify a received symbol;
Using the demodulated data identified by the first Fourier transform process and the received symbol identified by the second Fourier transform process, to execute a coefficient control process for controlling a filter coefficient in the filtering process,
A program characterized by that.

Images