JP5542483B2

JP5542483B2 - OFDM receiver

Info

Publication number: JP5542483B2
Application number: JP2010054936A
Authority: JP
Inventors: 行広門田
Original assignee: Mitsubishi Electric Corp
Current assignee: Mitsubishi Electric Corp
Priority date: 2010-03-11
Filing date: 2010-03-11
Publication date: 2014-07-09
Anticipated expiration: 2030-03-11
Also published as: JP2011193045A

Description

本発明は、直交周波数分割多重（ＯＦＤＭ）信号を受信するＯＦＤＭ受信装置に関するものである。 The present invention relates to an OFDM receiver that receives an orthogonal frequency division multiplexing (OFDM) signal.

従来のＯＦＤＭ受信装置は、受信した前後数シンボルのスキャッタードパイロット（ＳＰ）信号をもとに、時間方向の伝送路推定を行い、ＳＰ信号の存在するキャリアの全てのシンボルにおける伝送路推定値を出力する。さらに、ＯＦＤＭ受信装置は、この伝送路推定値をもとに、周波数方向の伝送路推定を行い、１シンボル中の全てのキャリアに対する伝送路推定値を出力する。しかし、このＯＦＤＭ受信装置では、時間方向にＳＰ信号が挿入されている割合で、伝送路の時間変動に対する追従性が決まってしまうので、移動体などが高速移動し、伝送路が激しく変動するような環境においては、十分に高い推定精度を保つことができなかった。 The conventional OFDM receiver estimates the transmission path in the time direction based on the received scattered pilot (SP) signal of several symbols before and after, and estimates the transmission path in all symbols of the carrier in which the SP signal exists. Is output. Further, the OFDM receiver performs transmission path estimation in the frequency direction based on this transmission path estimation value, and outputs transmission path estimation values for all carriers in one symbol. However, in this OFDM receiving apparatus, the followability to the time fluctuation of the transmission path is determined at the rate at which the SP signal is inserted in the time direction, so that the moving body moves at high speed and the transmission path fluctuates severely. In a difficult environment, sufficiently high estimation accuracy could not be maintained.

このような問題の無いＯＦＤＭ受信装置として、時間方向の伝送路推定を行わず、１シンボル中のＳＰ信号のみを用いて１シンボル毎の伝送路推定を行い、全キャリアの伝送路推定値を出力する方法が提案されている（例えば、特許文献１参照）。しかし、１シンボルのみで伝送路推定する方法は、伝送路の時間変化が激しい環境では高い伝送路推定精度を保つことができるが、長い遅延波が存在する環境では伝送路推定精度が低下し、受信性能を劣化させてしまう。 As an OFDM receiver without such a problem, transmission path estimation is performed for each symbol using only the SP signal in one symbol without performing transmission path estimation in the time direction, and transmission path estimation values for all carriers are output. A method has been proposed (see, for example, Patent Document 1). However, the method of estimating the transmission path using only one symbol can maintain high transmission path estimation accuracy in an environment where the time variation of the transmission path is severe, but the transmission path estimation accuracy decreases in an environment where a long delay wave exists, The reception performance is degraded.

また、伝送路の時間変化を検出し、その結果に応じて、時間方向の伝送路推定を行う方法と、１シンボルのみで伝送路推定を行う方法とを切り替えて用いる装置も提案されている（例えば、特許文献２参照）。 There has also been proposed an apparatus that detects a time change of a transmission path and switches between a method of estimating a transmission path in the time direction and a method of performing transmission path estimation using only one symbol according to the result ( For example, see Patent Document 2).

特開２００２−９７２４号公報（段落００４５〜００４７、図５）Japanese Patent Laid-Open No. 2002-9724 (paragraphs 0045 to 0047, FIG. 5) 特開２００６−１４０９８７号公報（段落００１６〜００２７、図１）JP 2006-140987 A (paragraphs 0016 to 0027, FIG. 1)

しかし、伝送路推定を切り替える上記方法では、長い遅延波が存在する環境では、伝送路推定における時間方向の分解能は変わらないため、伝送路が激しく変動するような環境で、十分に高い伝送路推定精度を保つことができず、受信性能は改善されないという問題がある。 However, in the above method of switching the transmission path estimation, the resolution in the time direction in the transmission path estimation does not change in an environment where a long delay wave exists, so that the transmission path estimation is sufficiently high in an environment where the transmission path fluctuates drastically. There is a problem that the accuracy cannot be maintained and the reception performance is not improved.

そこで、本発明は、上記課題を解決するためになされたものであり、その目的は、伝送路の時間変動が激しく、長い遅延波が存在する環境における、高い伝送路推定精度を維持できるＯＦＤＭ受信装置を提供することにある。 Accordingly, the present invention has been made to solve the above-described problems, and an object of the present invention is to provide an OFDM receiver that can maintain high transmission path estimation accuracy in an environment where a long delay wave exists and the time variation of the transmission path is severe. To provide an apparatus.

本発明の一形態に係るＯＦＤＭ受信装置は、複数のＳＰ信号が周波数方向及び時間方向に周期的に挿入されたＯＦＤＭ信号を受信するＯＦＤＭ受信装置であって、受信した前記ＳＰ信号の値と、既知の基準ＳＰ信号の値とを用いて、各シンボルにおける前記ＳＰ信号のキャリア位置での伝送路の周波数特性を推定し、該推定に基づく第１の伝送路推定結果を出力するＳＰ伝送路推定部と、前記第１の伝送路推定結果を用いて、各シンボル内の予め定められた特定のキャリア位置での伝送路の周波数特性を先行推定し、前記特定のキャリア位置の推定結果である第２の伝送路推定結果を出力する第１の先行伝送路推定部と、前記第２の伝送路推定結果を用いて、前記時間方向に伝送路推定を行い、該推定に基づく第３の伝送路推定結果を出力する時間方向伝送路推定部と、前記第３の伝送路推定結果を用いて、前記周波数方向に伝送路推定を行い、該推定に基づく第４の伝送路推定結果を出力する周波数方向伝送路推定部とを備え、前記第１の先行伝送路推定部は、前記第１の伝送路推定結果を複数のシンボルにわたって記憶するＳＰ伝送路推定結果記憶部と、前記ＳＰ伝送路推定結果記憶部から前記特定のキャリア位置の存在するシンボルの前後に隣接するシンボルのＳＰキャリア位置についての前記第１の伝送路推定結果を取り出し、前記隣接するシンボルについての前記第１の伝送路推定結果を、同一シンボル内の伝送路推定結果とみなし、ＦＩＲフィルタによって周波数方向に伝送路推定を行い、前記特定のキャリア位置についての前記第２の伝送路推定結果を出力するＦＩＲフィルタ内挿部とを有することを特徴としている。
また、本発明の他の態様に係るＯＦＤＭ受信装置は、複数のＳＰ信号が周波数方向及び時間方向に周期的に挿入されたＯＦＤＭ信号を受信するＯＦＤＭ受信装置であって、受信した前記ＳＰ信号の値と、既知の基準ＳＰ信号の値とを用いて、各シンボルにおける前記ＳＰ信号のキャリア位置での伝送路の周波数特性を推定し、該推定に基づく第１の伝送路推定結果を出力するＳＰ伝送路推定部と、前記第１の伝送路推定結果を用いて、各シンボル内の予め定められた特定のキャリア位置での伝送路の周波数特性を先行推定し、前記特定のキャリア位置の推定結果である第２の伝送路推定結果を出力する第１の先行伝送路推定部と、前記第２の伝送路推定結果を用いて、前記時間方向に伝送路推定を行い、該推定に基づく第３の伝送路推定結果を出力する時間方向伝送路推定部と、前記第３の伝送路推定結果を用いて、前記周波数方向に伝送路推定を行い、該推定に基づく第４の伝送路推定結果を出力する周波数方向伝送路推定部とを備え、前記第１の先行伝送路推定部は、前記第１の伝送路推定結果を複数のシンボルにわたって記憶するＳＰ伝送路推定結果記憶部と、前記ＳＰ伝送路推定結果記憶部から前記特定のキャリア位置の存在するシンボルの前後に隣接するシンボルのＳＰキャリア位置についての前記第１の伝送路推定結果で、前記特定のキャリア位置に最も近い、２点のＳＰキャリア位置の伝送路推定結果のみを取り出し、前記２点のＳＰキャリア位置についての前記第１の伝送路推定結果を同一シンボル内の伝送路推定結果とみなして、直線補間によって伝送路推定を行い、前記特定のキャリア位置についての前記第２の伝送路推定結果を出力する直線内挿部とを有することを特徴としている。
また、本発明の他の態様に係るＯＦＤＭ受信装置は、複数のＳＰ信号が周波数方向及び時間方向に周期的に挿入されたＯＦＤＭ信号を受信するＯＦＤＭ受信装置であって、受信した前記ＳＰ信号の値と、既知の基準ＳＰ信号の値とを用いて、各シンボルにおける前記ＳＰ信号のキャリア位置での伝送路の周波数特性を推定し、該推定に基づく第１の伝送路推定結果を出力するＳＰ伝送路推定部と、前記第１の伝送路推定結果を用いて、各シンボル内の予め定められた特定のキャリア位置での伝送路の周波数特性を先行推定し、前記特定のキャリア位置の推定結果である第２の伝送路推定結果を出力する第１の先行伝送路推定部と、前記第２の伝送路推定結果を用いて、前記時間方向に伝送路推定を行い、該推定に基づく第３の伝送路推定結果を出力する時間方向伝送路推定部と、前記第３の伝送路推定結果を用いて、前記周波数方向に伝送路推定を行い、該推定に基づく第４の伝送路推定結果を出力する周波数方向伝送路推定部とを備え、前記第１の先行伝送路推定部における予め定められた特定のキャリア位置についての前記第２の伝送路推定結果と、前記第１の先行伝送路推定部の前記第２の伝送路推定結果に含まれる、前記ＳＰ伝送路推定部の前記第１の伝送路推定結果とを用いて、前記第１の先行伝送路推定部における予め定められた特定のキャリア位置と同一のキャリア位置の伝送路推定を行い、該推定結果を第６の伝送路推定結果として前記時間方向伝送路推定部に出力する第２の先行伝送路推定部をさらに備え、前記時間方向伝送路推定部による時間方向の伝送路推定は、前記第６の伝送路推定結果を用いて行われることを特徴としている。 An OFDM receiver according to an aspect of the present invention is an OFDM receiver that receives an OFDM signal in which a plurality of SP signals are periodically inserted in a frequency direction and a time direction, and the received SP signal value; SP channel estimation that estimates the frequency characteristics of the transmission channel at the carrier position of the SP signal in each symbol using the value of the known reference SP signal and outputs the first transmission channel estimation result based on the estimation And the first transmission path estimation result, the frequency characteristic of the transmission path at a predetermined specific carrier position in each symbol is estimated in advance, and the estimation result of the specific carrier position is A first preceding transmission line estimation unit that outputs the transmission line estimation result of 2 and a third transmission line based on the estimation using the second transmission path estimation result in the time direction. Output the estimation result A time direction transmission path estimator and a frequency direction transmission path estimator that performs transmission path estimation in the frequency direction using the third transmission path estimation result and outputs a fourth transmission path estimation result based on the estimation The first preceding transmission path estimation unit includes an SP transmission path estimation result storage unit that stores the first transmission path estimation result over a plurality of symbols, and the identification from the SP transmission path estimation result storage unit. The first transmission path estimation result for the SP carrier positions of adjacent symbols before and after the symbol in which the carrier position exists is extracted, and the first transmission path estimation result for the adjacent symbols is A FI that is regarded as a transmission path estimation result, performs transmission path estimation in the frequency direction by an FIR filter, and outputs the second transmission path estimation result for the specific carrier position It is characterized by having a filter interpolator.
An OFDM receiver according to another aspect of the present invention is an OFDM receiver that receives an OFDM signal in which a plurality of SP signals are periodically inserted in a frequency direction and a time direction. SP that estimates the frequency characteristic of the transmission path at the carrier position of the SP signal in each symbol using the value and the value of the known reference SP signal, and outputs the first transmission path estimation result based on the estimation Using the transmission path estimation unit and the first transmission path estimation result, the frequency characteristic of the transmission path at a predetermined specific carrier position in each symbol is estimated in advance, and the specific carrier position estimation result A first preceding transmission path estimation unit that outputs the second transmission path estimation result, and a second transmission path estimation result to perform transmission path estimation in the time direction, and a third based on the estimation Transmission path estimation results Using the time direction transmission path estimation unit to output and the third transmission path estimation result, perform a transmission path estimation in the frequency direction, and output a fourth transmission path estimation result based on the estimation An estimation unit, wherein the first preceding transmission channel estimation unit includes an SP transmission channel estimation result storage unit that stores the first transmission channel estimation result over a plurality of symbols, and an SP transmission channel estimation result storage unit. Transmission path estimation of two SP carrier positions closest to the specific carrier position as a result of the first transmission path estimation for the SP carrier positions of symbols adjacent before and after the symbol where the specific carrier position exists Only the result is extracted, and the first channel estimation result for the two SP carrier positions is regarded as the channel estimation result in the same symbol, and channel estimation is performed by linear interpolation. There is characterized by having a linear interpolator for outputting said second channel estimation result for the particular carrier position.
An OFDM receiver according to another aspect of the present invention is an OFDM receiver that receives an OFDM signal in which a plurality of SP signals are periodically inserted in a frequency direction and a time direction. SP that estimates the frequency characteristic of the transmission path at the carrier position of the SP signal in each symbol using the value and the value of the known reference SP signal, and outputs the first transmission path estimation result based on the estimation Using the transmission path estimation unit and the first transmission path estimation result, the frequency characteristic of the transmission path at a predetermined specific carrier position in each symbol is estimated in advance, and the specific carrier position estimation result A first preceding transmission path estimation unit that outputs the second transmission path estimation result, and a second transmission path estimation result to perform transmission path estimation in the time direction, and a third based on the estimation Transmission path estimation results Using the time direction transmission path estimation unit to output and the third transmission path estimation result, perform a transmission path estimation in the frequency direction, and output a fourth transmission path estimation result based on the estimation An estimation unit, the second transmission path estimation result for a predetermined specific carrier position in the first preceding transmission path estimation unit, and the second of the first preceding transmission path estimation unit Using the first transmission path estimation result of the SP transmission path estimation unit included in the transmission path estimation result, the same carrier as the predetermined specific carrier position in the first preceding transmission path estimation section A second preceding transmission line estimation unit that performs position transmission path estimation and outputs the estimation result as a sixth transmission path estimation result to the time direction transmission path estimation unit; Transmission path in time direction It is characterized in that which is performed using the transmission path estimation result of the sixth.

本発明によれば、予め特定のキャリアの伝送路推定値を出力することで、時間方向に伝送路推定を行うために必要な伝送路推定結果を増加させることによって、伝送路の時間変動に対する追従性を高めることができるという効果がある。 According to the present invention, a channel estimation value of a specific carrier is output in advance, thereby increasing the channel estimation result necessary for performing channel estimation in the time direction, thereby tracking the time variation of the channel. There is an effect that can improve the nature.

また、本発明によれば、受信した前後の隣接シンボルにおけるＳＰ信号の伝送路信号を用いることによって、周波数方向に伝送路推定を行うために必要な伝送路推定結果を増加させ、長い遅延波が存在する環境においても、伝送路推定精度を向上させることができるという効果がある。 Also, according to the present invention, by using the transmission path signal of the SP signal in the adjacent symbols before and after reception, the transmission path estimation result necessary for performing transmission path estimation in the frequency direction is increased, and a long delay wave is generated. Even in an existing environment, the transmission path estimation accuracy can be improved.

本発明に係る実施の形態１のＯＦＤＭ受信装置の構成を概略的に示すブロック図である。It is a block diagram which shows schematically the structure of the OFDM receiver of Embodiment 1 which concerns on this invention. 日本の地上デジタル放送におけるＯＦＤＭ信号でＳＰ信号が挿入されるキャリア位置を示す図である。It is a figure which shows the carrier position where SP signal is inserted by the OFDM signal in Japanese terrestrial digital broadcasting. 図１に示される伝送路推定部の構成を概略的に示すブロック図である。It is a block diagram which shows roughly the structure of the transmission-line estimation part shown by FIG. 図３に示される第１の先行伝送路推定部における伝送路推定結果を出力するキャリア位置を示す図である。It is a figure which shows the carrier position which outputs the transmission line estimation result in the 1st preceding transmission line estimation part shown by FIG. 図３に示される時間方向伝送路推定部における伝送路推定結果を出力するキャリア位置を示す図である。It is a figure which shows the carrier position which outputs the transmission path estimation result in the time direction transmission path estimation part shown by FIG. 図３に示される周波数方向伝送路推定部における伝送路推定結果を出力するキャリア位置を示す図である。It is a figure which shows the carrier position which outputs the transmission path estimation result in the frequency direction transmission path estimation part shown by FIG. 図３に示される第１の先行伝送路推定部の構成の一例を概略的に示すブロック図である。It is a block diagram which shows roughly an example of a structure of the 1st preceding transmission line estimation part shown by FIG. 図７に示されるＦＩＲフィルタ内挿部において、入力されるＳＰ信号の伝送路推定結果のキャリア位置と出力する伝送路推定結果のキャリア位置を示す図である。FIG. 8 is a diagram illustrating a carrier position of a transmission path estimation result of an input SP signal and a carrier position of a transmission path estimation result to be output in the FIR filter interpolation unit illustrated in FIG. 7. 図３に示される第１の先行伝送路推定部の構成の他の例を概略的に示すブロック図である。It is a block diagram which shows roughly the other example of a structure of the 1st preceding transmission line estimation part shown by FIG. 図９に示される直線内挿部において、入力されるＳＰ信号の伝送路推定結果のキャリア位置と出力する伝送路推定結果のキャリア位置を示す図である。FIG. 10 is a diagram illustrating a carrier position of a transmission path estimation result of an input SP signal and a carrier position of a transmission path estimation result to be output in the linear interpolation unit illustrated in FIG. 9. 図３に示される第１の先行伝送路推定部の構成のさらに他の例を概略的に示すブロック図である。FIG. 10 is a block diagram schematically showing still another example of the configuration of the first preceding transmission path estimation unit shown in FIG. 3. 本発明に係る実施の形態２のＯＦＤＭ受信装置の構成を概略的に示すブロック図である。It is a block diagram which shows roughly the structure of the OFDM receiver of Embodiment 2 which concerns on this invention. 図１２に示される伝送路推定部の構成を概略的に示すブロック図である。It is a block diagram which shows roughly the structure of the transmission-line estimation part shown by FIG. 図１３に示される第２の先行伝送路推定部の構成の一例を概略的に示すブロック図である。It is a block diagram which shows roughly an example of a structure of the 2nd preceding transmission line estimation part shown by FIG. 図１４に示される第１の周波数方向内挿部において、入力される伝送路推定結果のキャリア位置と出力する伝送路推定結果のキャリア位置を示す図である。It is a figure which shows the carrier position of the transmission path estimation result output and the carrier position of the transmission path estimation result output in the 1st frequency direction interpolation part shown by FIG. 図１４に示される第２の周波数方向内挿部において、入力される伝送路推定結果のキャリア位置と出力する伝送路推定結果のキャリア位置を示す図である。It is a figure which shows the carrier position of the transmission path estimation result input and the carrier position of the transmission path estimation result output in the 2nd frequency direction interpolation part shown by FIG. 図１３に示される第２の先行伝送路推定部の構成の他の例を概略的に示すブロック図である。FIG. 14 is a block diagram schematically showing another example of the configuration of the second preceding transmission path estimation unit shown in FIG. 13. 図１３に示される時間方向内挿部において、入力される伝送路推定結果のキャリア位置と出力する伝送路推定結果のキャリア位置を示す図である。It is a figure which shows the carrier position of the transmission-path estimation result output in the time direction interpolation part shown by FIG. 図１３に示される第２の先行伝送路推定部で、第３の周波数方向内挿部において、入力される伝送路推定結果のキャリア位置と出力する伝送路推定結果のキャリア位置を示す図である。FIG. 14 is a diagram illustrating a carrier position of an input transmission path estimation result and a carrier position of an output transmission path estimation result in a third frequency direction interpolation section in the second preceding transmission path estimation section shown in FIG. 13. .

実施の形態１．
図１は、本発明に係る実施の形態１のＯＦＤＭ受信装置１０の構成を概略的に示すブロック図である。ＯＦＤＭ受信装置１０は、複数のＳＰ信号が周波数方向及び時間方向に周期的に挿入されたＯＦＤＭ信号を受信するＯＦＤＭ受信装置である。図１に示されるように、ＯＦＤＭ受信装置は、アナログ部１１と、アナログ／デジタル（Ａ／Ｄ）変換部１２と、直交復調部１３と、高速フーリエ変換（ＦＦＴ）部１４と、伝送路推定部１５と、等化部１６と、前方誤り訂正（ＦＥＣ）部１７とを備えている。 Embodiment 1 FIG.
FIG. 1 is a block diagram schematically showing a configuration of OFDM receiving apparatus 10 according to Embodiment 1 of the present invention. The OFDM receiver 10 is an OFDM receiver that receives an OFDM signal in which a plurality of SP signals are periodically inserted in the frequency direction and the time direction. As shown in FIG. 1, the OFDM receiver includes an analog unit 11, an analog / digital (A / D) conversion unit 12, an orthogonal demodulation unit 13, a fast Fourier transform (FFT) unit 14, and a transmission path estimation. A unit 15, an equalization unit 16, and a forward error correction (FEC) unit 17 are provided.

図１において、受信されたＯＦＤＭ信号Ｓ０は、アナログ部１１に入力される。アナログ部１１は、入力されたＯＦＤＭ信号Ｓ０に、例えば、増幅器によるゲイン調整、ミキサーによる周波数変換、バンドパスフィルタによる帯域制限などの処理を施し、この処理によって得られた信号Ｓ１をＡ／Ｄ変換部１２に供給する。 In FIG. 1, the received OFDM signal S0 is input to the analog unit 11. The analog unit 11 performs processing such as gain adjustment by an amplifier, frequency conversion by a mixer, band limitation by a bandpass filter, and the like on the input OFDM signal S0, and A / D conversion is performed on the signal S1 obtained by this processing. To the unit 12.

Ａ／Ｄ変換部１２は、信号Ｓ１にアナログ／デジタル変換を行い、その結果の信号Ｓ２を直交復調部１３に供給する。 The A / D converter 12 performs analog / digital conversion on the signal S1 and supplies the resultant signal S2 to the quadrature demodulator 13.

直交復調部１３は、入力された信号Ｓ２を複素ベースバンド信号Ｓ３に変換し、これをＦＦＴ部１４に供給する。 The quadrature demodulator 13 converts the input signal S2 into a complex baseband signal S3 and supplies it to the FFT unit 14.

ＦＦＴ部１４は、入力された複素ベースバンド信号Ｓ３を時間軸の信号から周波数軸の信号Ｓ４に変換し、得られた周波数軸の信号Ｓ４を伝送路推定部１５及び等化部１６に出力する。 The FFT unit 14 converts the input complex baseband signal S3 from a time-axis signal to a frequency-axis signal S4, and outputs the obtained frequency-axis signal S4 to the transmission path estimation unit 15 and the equalization unit 16. .

伝送路推定部１５は、入力された周波数軸の信号Ｓ４からＳＰ信号のみを取り出し、そのＳＰ信号をもとに、シンボル毎に更新される全キャリアの伝送路推定結果を出力する。 The transmission path estimation unit 15 extracts only the SP signal from the input frequency axis signal S4, and outputs the transmission path estimation results of all carriers updated for each symbol based on the SP signal.

等化部１６は、伝送路推定部１５からの伝送路推定結果Ｓ５を用いて、周波数軸の信号Ｓ４に対する等化を行い、復調結果Ｓ６を出力する。 The equalization unit 16 equalizes the frequency axis signal S4 using the transmission path estimation result S5 from the transmission path estimation unit 15 and outputs a demodulation result S6.

ＦＥＣ部１７は、入力された復調結果Ｓ６に対して、デインターリーブや誤り訂正などの処理を行い、受信データＳ７を再生する。 The FEC unit 17 performs processing such as deinterleaving and error correction on the input demodulation result S6 to reproduce the reception data S7.

図２は、日本の地上デジタル放送でのＯＦＤＭ信号におけるＳＰ信号が挿入されるキャリア位置を示す図である。実施の形態１では、日本の地上デジタル放送で採用しているＩＳＤＢ−Ｔ（ＩｎｔｅｇｒａｔｅｄＳｅｒｖｉｃｅｓＤｉｇｉｔａｌＢｒｏａｄｃａｓｔｉｎｇ−Ｔｅｒｒｅｓｔｒｉａｌ）形式のＯＦＤＭ信号を受信する装置について説明する。図２に示されるように、ＩＳＤＢ−Ｔ形式のＯＦＤＭ信号は、各シンボルにおいて周波数ｆ方向に１２キャリア毎にＳＰ信号が挿入されており、シンボル間（時間ｔ方向）において３キャリアずつシフトしてＳＰ信号が挿入されている。ＳＰ信号は既知の値であるため、受信側で受信したＳＰ信号の値と真の（既知の）ＳＰ信号の値とから、ＳＰ信号が挿入されたキャリア位置の周波数における伝送路特性を推定することができる。 FIG. 2 is a diagram showing a carrier position into which an SP signal is inserted in an OFDM signal in Japanese terrestrial digital broadcasting. In the first embodiment, an apparatus that receives an OFDM signal in the ISDB-T (Integrated Services Digital Broadcasting-Terrestrial) format used in Japanese terrestrial digital broadcasting will be described. As shown in FIG. 2, in an OFDM signal in the ISDB-T format, an SP signal is inserted every 12 carriers in the frequency f direction in each symbol, and shifted by 3 carriers between symbols (time t direction). An SP signal is inserted. Since the SP signal is a known value, the channel characteristic at the frequency of the carrier position where the SP signal is inserted is estimated from the value of the SP signal received on the receiving side and the value of the true (known) SP signal. be able to.

図３は、図１に示される伝送路推定部１５の構成を概略的に示すブロック図である。図３に示されるように、実施の形態１による伝送路推定部１５は、ＳＰ伝送路推定部１５１と、第１の先行伝送路推定部１５２（又は１５２ａ、又は１５２ｂ）と、時間方向伝送路推定部１５３と、周波数方向伝送路推定部１５４とを備えている。 FIG. 3 is a block diagram schematically showing the configuration of the transmission path estimation unit 15 shown in FIG. As shown in FIG. 3, the transmission path estimation unit 15 according to the first embodiment includes an SP transmission path estimation unit 151, a first preceding transmission path estimation unit 152 (or 152a or 152b), and a time direction transmission path. An estimation unit 153 and a frequency direction transmission path estimation unit 154 are provided.

ＳＰ伝送路推定部１５１は、ＦＦＴ部１４からの周波数軸の信号Ｓ４に含まれるＳＰ信号の値と、既知のＳＰ信号の値とを用いて、各シンボルにおけるＳＰ信号のキャリア位置での伝送路の周波数特性を推定し、推定結果を第１の先行伝送路推定部１５２に出力する。 The SP transmission path estimator 151 uses the SP signal value included in the frequency axis signal S4 from the FFT section 14 and the known SP signal value to transmit the SP signal at the carrier position of each symbol. And the estimation result is output to the first preceding transmission line estimation unit 152.

第１の先行伝送路推定部１５２は、ＳＰ伝送路推定部１５１から入力された推定結果の内の、前後に隣接するシンボル（時間方向に隣接して並ぶ複数のシンボル）におけるＳＰ信号の伝送路推定結果を用いて、各シンボル内の予め定められた特定のキャリア位置での伝送路の周波数特性を推定（先行推定）し、推定結果を時間方向伝送路推定部１５３に出力する。 The first preceding transmission path estimator 152 includes SP signal transmission paths in the adjacent symbols (a plurality of symbols arranged adjacent to each other in the time direction) in the estimation result input from the SP transmission path estimator 151. Using the estimation result, the frequency characteristic of the transmission line at a predetermined specific carrier position in each symbol is estimated (preceding estimation), and the estimation result is output to the time direction transmission line estimation unit 153.

図４は、図３に示される第１の先行伝送路推定部１５２における伝送路推定結果を出力するキャリア位置を示す図である。図４に示されるように、第１の先行伝送路推定部１５２は、例えば、第１の先行伝送路推定部１５２から出力される推定結果がＳＰ信号のキャリア位置を含み、かつ、各シンボルにおいて６キャリア毎となるようなキャリア位置で推定（先行推定）を行う。すなわち、実施の形態１では、第１の先行伝送路推定部１５２は、各シンボルにおいて、ＳＰ信号の挿入間隔を２等分するキャリア位置で推定（先行推定）を行う場合を説明する。なお、先行推定を行う特定のキャリア位置は、ＯＦＤＭ信号のＳＰ信号の配置にも影響されるものであり、上記のキャリア位置での推定（先行推定）に限定されるものではない。 FIG. 4 is a diagram illustrating a carrier position that outputs a transmission path estimation result in the first preceding transmission path estimation unit 152 shown in FIG. As shown in FIG. 4, the first preceding transmission path estimation unit 152, for example, the estimation result output from the first preceding transmission path estimation unit 152 includes the carrier position of the SP signal, and in each symbol Estimation (advance estimation) is performed at a carrier position that is every six carriers. That is, in Embodiment 1, a case will be described in which first preceding transmission path estimation section 152 performs estimation (preceding estimation) at a carrier position that bisects the SP signal insertion interval in each symbol. Note that the specific carrier position where the preceding estimation is performed is also affected by the arrangement of the SP signal of the OFDM signal, and is not limited to the above estimation at the carrier position (preceding estimation).

図５は、図３に示される時間方向伝送路推定部１５３における伝送路推定結果を出力するキャリア位置を示す図である。時間方向伝送路推定部１５３は、第１の先行伝送路推定部１５２から入力された推定結果を用いて、前後数シンボル（時間方向に並ぶ複数のシンボル）の同一キャリア位置での推定結果を元に時間方向に伝送路推定（図５の破線で囲う部分で示す）を行い、推定結果（図５にハッチングで示す）をシンボル毎に周波数方向伝送路推定部１５４に出力する。 FIG. 5 is a diagram showing a carrier position for outputting a transmission path estimation result in the time direction transmission path estimation unit 153 shown in FIG. The time direction transmission path estimation unit 153 uses the estimation result input from the first preceding transmission path estimation unit 152 to obtain the estimation result at the same carrier position of several symbols (a plurality of symbols arranged in the time direction). Then, the transmission path is estimated in the time direction (indicated by a portion surrounded by a broken line in FIG. 5), and the estimation result (indicated by hatching in FIG. 5) is output to the frequency direction transmission path estimation section 154 for each symbol.

図６は、図３に示される周波数方向伝送路推定部１５４における伝送路推定結果を出力するキャリア位置を示す図である。周波数方向伝送路推定部１５４は、時間方向伝送路推定部１５３から入力された推定結果を用いて、周波数方向に伝送路推定を行い、図６にハッチングで示すように、１シンボル中の全キャリア位置での推定結果Ｓ５をシンボル毎に等化部１６に出力する。 FIG. 6 is a diagram illustrating a carrier position that outputs a transmission path estimation result in the frequency direction transmission path estimation unit 154 shown in FIG. The frequency direction transmission path estimator 154 performs transmission path estimation in the frequency direction using the estimation result input from the time direction transmission path estimator 153, and as shown by hatching in FIG. 6, all carriers in one symbol. The estimation result S5 at the position is output to the equalization unit 16 for each symbol.

以上のことから、第１の先行伝送路推定部１５２にて特定のキャリア位置に対して伝送路推定を行い、推定された伝送路推定結果を用いることによって、時間方向伝送路推定部１５３にて時間方向の伝送路推定を行う際に、伝送路推定を行うために必要な伝送路推定結果の時間的割合を増加させることができる。このため、伝送路の時間変動に対する追従性を高めることができる。 From the above, the first preceding transmission path estimation unit 152 performs transmission path estimation for a specific carrier position, and uses the estimated transmission path estimation result, whereby the time direction transmission path estimation unit 153 When performing transmission path estimation in the time direction, the time ratio of the transmission path estimation result necessary for performing transmission path estimation can be increased. For this reason, the followability with respect to the time fluctuation | variation of a transmission line can be improved.

また、第１の先行伝送路推定部１５２においては、前後に隣接するシンボル（時間方向に隣接して並ぶ複数のシンボル）におけるＳＰ信号の伝送路推定結果を用い、伝送路推定を行うために必要なＳＰ信号の伝送路推定結果を周波数方向に増加させて、伝送路の周波数特性を推定（先行推定）すること、さらには、現シンボルの伝送路変動に対して、独立性の高い、遠く離れたシンボルのＳＰ信号の伝送路推定結果を使用しない。これにより、長い遅延波の存在する環境でも、伝送路の時間変動に対する追従性を高め、伝送路推定精度を向上させることができる。 In addition, the first preceding transmission path estimation unit 152 is necessary for performing transmission path estimation using the SP signal transmission path estimation results in the front and rear adjacent symbols (a plurality of symbols arranged adjacent in the time direction). Increase the SP signal transmission line estimation result in the frequency direction to estimate the frequency characteristic of the transmission line (preceding estimation), and further, far away from the current symbol transmission line fluctuation The transmission path estimation result of the SP signal of the symbol is not used. As a result, even in an environment where a long delay wave exists, it is possible to improve the followability to the time variation of the transmission path and improve the transmission path estimation accuracy.

図７は、図３に示される第１の先行伝送路推定部１５２の構成の一例を概略的に示すブロック図である。図７に示されるように、第１の先行伝送路推定部１５２は、ＳＰ伝送路推定結果記憶部１５２１と、ＦＩＲフィルタ内挿部１５２２とを備えている。 FIG. 7 is a block diagram schematically showing an example of the configuration of the first preceding transmission path estimation unit 152 shown in FIG. As illustrated in FIG. 7, the first preceding transmission path estimation unit 152 includes an SP transmission path estimation result storage unit 1521 and an FIR filter interpolation unit 1522.

ＳＰ伝送路推定結果記憶部１５２１は、ＳＰ伝送路推定部１５１から入力されたＳＰ伝送路推定結果を、直近の３シンボル分（伝送路推定を行うシンボルと、その前後に隣接するシンボルとの合計３シンボル分）記憶する。 The SP transmission path estimation result storage unit 1521 displays the SP transmission path estimation result input from the SP transmission path estimation unit 151 for the three most recent symbols (the sum of the symbols for which transmission path estimation is performed and the symbols adjacent thereto before and after the symbol). 3 symbols).

図８は、図７に示されるＦＩＲフィルタ内挿部１５２２において、入力されるＳＰ信号の伝送路推定結果のキャリア位置と出力する伝送路推定結果のキャリア位置を示す図である。ＦＩＲフィルタ内挿部１５２２は、伝送路推定を行うシンボルの前又は後ろに隣接するシンボルのＳＰ信号の伝送路推定結果をＳＰ伝送路推定結果記憶部１５２１から取り出し、図８に示されるように、伝送路推定を行うシンボルと同一シンボルの伝送路推定結果とみなして、ＦＩＲフィルタによって周波数方向の伝送路推定を行い、図４で示されたキャリア位置の伝送路推定結果を出力する。但し、ＦＩＲフィルタ内挿部１５２２は、ＳＰ信号の伝送路推定結果は、ＳＰ伝送路推定部１５１から入力され、ＳＰ伝送路推定結果記憶部１５２１に記憶されているものをそのまま出力する。 FIG. 8 is a diagram showing the carrier position of the transmission path estimation result of the input SP signal and the carrier position of the transmission path estimation result to be output in the FIR filter interpolation unit 1522 shown in FIG. The FIR filter interpolating unit 1522 takes out the SP channel transmission result of the SP signal of the symbol adjacent to the symbol that performs transmission path estimation before or behind the SP transmission path estimation result storage unit 1521, and as shown in FIG. Considering the transmission path estimation result of the same symbol as the symbol for which transmission path estimation is performed, the transmission path estimation in the frequency direction is performed by the FIR filter, and the transmission path estimation result at the carrier position shown in FIG. 4 is output. However, the FIR filter interpolation unit 1522 outputs the SP signal transmission path estimation result as it is input from the SP transmission path estimation unit 151 and stored in the SP transmission path estimation result storage unit 1521 as it is.

以上に説明したように、前後に隣接するシンボルのＳＰ伝送路推定結果をもとに、ＦＩＲフィルタを用いて精度よく伝送路推定を行うことにより、長い遅延波の存在する環境でも、伝送路の時間変動に対する追従性を高め、伝送路推定精度を向上させることができる。 As described above, by accurately estimating the transmission path using the FIR filter based on the SP transmission path estimation results of adjacent symbols before and after, even in an environment where a long delay wave exists, the transmission path The followability with respect to time fluctuation can be improved, and the transmission path estimation accuracy can be improved.

図９は、図３に示される第１の先行伝送路推定部１５２ａの構成の他の例を概略的に示すブロック図である。図９において、図７に示される構成と同一又は対応する構成には同じ符号を付す。図９に示される第１の先行伝送路推定部１５２ａは、ＦＩＲフィルタ内挿部１５２２の代わりに、直線内挿部１５２３を備える点が、図７に示される第１の先行伝送路推定部１５２と相違する。 FIG. 9 is a block diagram schematically showing another example of the configuration of the first preceding transmission path estimation unit 152a shown in FIG. In FIG. 9, the same or corresponding components as those shown in FIG. The first preceding transmission path estimation unit 152a shown in FIG. 9 includes a straight line interpolation unit 1523 instead of the FIR filter interpolation unit 1522. The first preceding transmission path estimation unit 152 shown in FIG. Is different.

図１０は、図９に示される直線内挿部１５２３において、入力されるＳＰ信号の伝送路推定結果のキャリア位置と出力する伝送路推定結果のキャリア位置を示す図である。直線内挿部１５２３は、図１０に示されるように、ＳＰ伝送路推定結果記憶部１５２１から伝送路推定を行うシンボルの前又は後ろに隣接するシンボルのＳＰキャリア位置の伝送路推定結果で、伝送路推定を行うキャリア位置に最も近い、２点のＳＰ信号の伝送路推定結果のみを取り出す。そして、直線内挿部１５２３は、これら２点の伝送路推定結果を同一シンボル内の伝送路推定結果とみなし、直線補間（図１０に波線で示す長方形）によって伝送路推定を行い、図４で示されたキャリア位置の伝送路推定結果を出力する。但し、直線内挿部１５２３は、ＳＰ信号の伝送路推定結果は、ＳＰ伝送路推定部１５１から入力され、ＳＰ伝送路推定結果記憶部１５２１に記憶されているものをそのまま出力する。 FIG. 10 is a diagram illustrating the carrier position of the transmission path estimation result of the input SP signal and the carrier position of the transmission path estimation result to be output in the linear interpolation unit 1523 shown in FIG. As shown in FIG. 10, the linear interpolation unit 1523 transmits the transmission path estimation result of the SP carrier position of the symbol adjacent to the front or rear of the symbol for performing transmission path estimation from the SP transmission path estimation result storage unit 1521. Only the transmission path estimation results of the two SP signals closest to the carrier position where path estimation is performed are extracted. Then, the linear interpolation unit 1523 regards these two transmission path estimation results as transmission path estimation results within the same symbol, performs transmission path estimation by linear interpolation (a rectangle indicated by a broken line in FIG. 10), and in FIG. The transmission path estimation result of the indicated carrier position is output. However, the linear interpolation unit 1523 receives the SP signal transmission path estimation result input from the SP transmission path estimation unit 151 and outputs the SP signal transmission path estimation result stored in the SP transmission path estimation result storage unit 1521 as it is.

この場合、より簡易で規模の小さい回路構成で、長い遅延波の存在する環境でも、伝送路の時間変動に対する追従性を高め、伝送路推定精度を向上させることができる。 In this case, with a simpler and smaller circuit configuration, even in an environment where a long delay wave exists, it is possible to improve the followability to the time variation of the transmission path and improve the transmission path estimation accuracy.

図１１は、図３に示される第１の先行伝送路推定部１５２ｂの構成のさらに他の例を概略的に示すブロック図である。図１１において、図７に示される構成と同一又は対応する構成には同じ符号を付す。図１１に示される第１の先行伝送路推定部１５２ｂは、伝送路推定結果記憶部１５２１とＦＩＲフィルタ内挿部１５２２に加えて、誤差検出部１５２４と係数制御部１５２５とを備える点が、図７に示される第１の先行伝送路推定部１５２と相違する。 FIG. 11 is a block diagram schematically showing still another example of the configuration of the first preceding transmission path estimation unit 152b shown in FIG. In FIG. 11, the same or corresponding components as those shown in FIG. The first preceding transmission path estimation unit 152b illustrated in FIG. 11 includes an error detection unit 1524 and a coefficient control unit 1525 in addition to the transmission path estimation result storage unit 1521 and the FIR filter interpolation unit 1522. 7 is different from the first preceding transmission path estimation unit 152 shown in FIG.

図１１に示すＦＩＲフィルタ内挿部１５２２におけるＦＩＲフィルタは、係数可変のＦＩＲフィルタであり、ＳＰ信号のキャリア位置を含む、特定のキャリア位置の伝送路推定結果を出力する。誤差検出部１５２４は、ＦＩＲフィルタ内挿部１５２２の出力であるＳＰ信号のキャリア位置の伝送路推定結果と、ＳＰ伝送路推定結果記憶部１５２１から取り出した、同一シンボルのＳＰ信号のキャリア位置の伝送路推定結果とを比較し、その誤差情報を生成して係数制御部１５２５に出力する。係数制御部１５２５は、誤差検出部１５２４の出力した誤差情報をもとに、ＦＩＲフィルタ内挿部１５２２におけるフィルタ係数を制御する。 The FIR filter in the FIR filter interpolation unit 1522 shown in FIG. 11 is a variable coefficient FIR filter, and outputs a transmission path estimation result of a specific carrier position including the carrier position of the SP signal. The error detection unit 1524 transmits the SP signal carrier position transmission path estimation result output from the FIR filter interpolation unit 1522 and the SP signal carrier position transmission of the same symbol extracted from the SP transmission path estimation result storage unit 1521. The path estimation result is compared, and error information is generated and output to the coefficient control unit 1525. The coefficient control unit 1525 controls the filter coefficient in the FIR filter interpolation unit 1522 based on the error information output from the error detection unit 1524.

以上に説明したように、同一シンボル内のＳＰ信号の伝送路推定結果を用いて、適応的にＦＩＲフィルタ内挿部１５２２のフィルタ係数を制御し、最適化することによって、ＦＩＲフィルタ内挿部１５２２における伝送路推定精度を向上させることができる。 As described above, the FIR filter interpolation unit 1522 is adaptively controlled and optimized by using the transmission path estimation result of the SP signal in the same symbol to optimize the filter coefficient of the FIR filter interpolation unit 1522. The transmission path estimation accuracy in can be improved.

実施の形態２．
図１２は、本発明に係る実施の形態２のＯＦＤＭ受信装置２０の構成を概略的に示すブロック図である。図１２において、図１（実施の形態１）の構成と同一又は対応する構成には、同じ符号を付す。実施の形態２のＯＦＤＭ受信装置２０は、伝送路推定結果Ｓ８を出力する伝送路推定部１８の構成の点で、実施の形態１のＯＦＤＭ受信装置１０と相違する。 Embodiment 2. FIG.
FIG. 12 is a block diagram schematically showing a configuration of OFDM receiving apparatus 20 according to the second embodiment of the present invention. 12, components that are the same as or correspond to those in FIG. 1 (Embodiment 1) are assigned the same reference numerals. The OFDM receiver 20 of the second embodiment is different from the OFDM receiver 10 of the first embodiment in the configuration of the transmission path estimation unit 18 that outputs the transmission path estimation result S8.

図１３は、図１２に示される伝送路推定部１８の構成を概略的に示すブロック図である。図１３において、図３（実施の形態１）の構成と同一又は対応する構成には、同じ符号を付す。実施の形態２の伝送路推定部１８は、第２の先行伝送路推定部１８１（又は１８１ａ）をさらに備える点において、実施の形態１の伝送路推定部１５と相違する。 FIG. 13 is a block diagram schematically showing the configuration of the transmission path estimation unit 18 shown in FIG. In FIG. 13, the same or corresponding components as those in FIG. 3 (Embodiment 1) are denoted by the same reference numerals. The transmission path estimation unit 18 of the second embodiment is different from the transmission path estimation unit 15 of the first embodiment in that it further includes a second preceding transmission path estimation unit 181 (or 181a).

第２の先行伝送路推定部１８１は、第１の先行伝送路推定部１５２の出力である伝送路推定結果Ｓ４を受け取り、第１の先行伝送路推定部１５２の出力である伝送路推定結果と同一のキャリア位置の伝送路推定結果を出力する。 The second preceding transmission path estimation unit 181 receives the transmission path estimation result S4 that is the output of the first preceding transmission path estimation unit 152, and the transmission path estimation result that is the output of the first preceding transmission path estimation unit 152; Output the transmission path estimation result of the same carrier position.

時間方向伝送路推定部１５３は、第２の先行伝送路推定部１８１から入力された推定結果を用いて時間方向に伝送路推定を行う。上記以外の構成及び動作については、伝送路推定部１８は、実施の形態１の伝送路推定部１５と同じである。 The time direction transmission path estimation unit 153 performs transmission path estimation in the time direction using the estimation result input from the second preceding transmission path estimation unit 181. Regarding configurations and operations other than those described above, the transmission path estimation unit 18 is the same as the transmission path estimation unit 15 of the first embodiment.

第２の先行伝送路推定部１８１は、第１の先行伝送路推定部１５２の出力である伝送路推定結果を用い、さらに、その伝送路推定結果に含まれる、第１の先行伝送路推定部１５２において利用されていないＳＰ信号の伝送路推定結果を利用して、再度伝送路推定を行う。このように、伝送路推定部１８は、同一のキャリア位置の伝送路推定結果をより高精度に出力するため、長い遅延波の存在する環境でも、伝送路の時間変動に対する追従性を高め、伝送路推定精度をより向上させることができる。 The second preceding transmission path estimation unit 181 uses the transmission path estimation result that is the output of the first preceding transmission path estimation unit 152, and further includes a first preceding transmission path estimation unit included in the transmission path estimation result. The transmission path estimation is performed again using the transmission path estimation result of the SP signal not used in 152. As described above, the transmission path estimation unit 18 outputs the transmission path estimation result of the same carrier position with higher accuracy, so that the followability to the time fluctuation of the transmission path is improved even in an environment where a long delay wave exists, and transmission is performed. The path estimation accuracy can be further improved.

図１４は、図１３に示される第２の先行伝送路推定部１８１の構成の一例を概略的に示すブロック図である。第２の先行伝送路推定部１８１は、図１４に示されるように、第１の周波数方向内挿部１８１１と、第２の周波数方向内挿部１８１２とを備えている。第１の周波数方向内挿部１８１１は、第１の先行伝送路推定部１５２が出力する伝送路推定結果に含まれる、第１の先行伝送路推定部１５２において、隣接シンボルのＳＰ信号を利用して生成した伝送路推定結果と、現シンボルのＳＰ信号の伝送路推定結果とをもとに、周波数方向の伝送路推定を行う。このように、第１の周波数方向内挿部１８１１は、第１の先行伝送路推定部１５２の出力において、伝送路推定結果が存在するキャリアとは、異なるキャリア位置の伝送路推定を行う。 FIG. 14 is a block diagram schematically showing an example of the configuration of the second preceding transmission path estimation unit 181 shown in FIG. As illustrated in FIG. 14, the second preceding transmission path estimation unit 181 includes a first frequency direction interpolation unit 1811 and a second frequency direction interpolation unit 1812. The first frequency direction interpolation unit 1811 uses the SP signal of the adjacent symbol in the first preceding transmission path estimation unit 152 included in the transmission path estimation result output from the first preceding transmission path estimation unit 152. Based on the transmission path estimation result generated in this way and the transmission path estimation result of the SP signal of the current symbol, the transmission path in the frequency direction is estimated. As described above, the first frequency direction interpolation unit 1811 performs transmission path estimation at a carrier position different from the carrier in which the transmission path estimation result exists in the output of the first preceding transmission path estimation unit 152.

図１５は、図１４に示される第１の周波数方向内挿部１８１１において、入力される伝送路推定結果のキャリア位置と出力する伝送路推定結果のキャリア位置を示す図である。実施の形態２においては、図１５にクロスハッチングで示されるように、第１の先行伝送路推定部１５２の出力において、伝送路推定結果が存在するキャリア位置（図１５におけるハッチング位置）の中間のキャリア位置の伝送路推定を行う。 FIG. 15 is a diagram illustrating a carrier position of an input transmission path estimation result and a carrier position of a transmission path estimation result to be output in the first frequency direction interpolation unit 1811 illustrated in FIG. In the second embodiment, as shown by cross hatching in FIG. 15, the output of the first preceding transmission path estimation unit 152 is an intermediate between the carrier positions where the transmission path estimation results exist (hatching positions in FIG. 15). The transmission path of the carrier position is estimated.

図１６は、図１４に示される第２の周波数方向内挿部１８１２において、入力される伝送路推定結果のキャリア位置と出力する伝送路推定結果のキャリア位置を示す図である。第２の周波数方向内挿部１８１２は、図１６に示されるように、第１の周波数方向内挿部１８１１の出力する伝送路推定結果（図１６においてクロスハッチングで示す）をもとに、周波数方向の伝送路推定を行い、第１の先行伝送路推定部１５２の出力において、伝送路推定結果が存在するキャリアと同一のキャリア位置の伝送路推定結果（図１６におけるハッチング位置）を出力する。 FIG. 16 is a diagram illustrating a carrier position of an input transmission path estimation result and a carrier position of a transmission path estimation result to be output in the second frequency direction interpolation unit 1812 illustrated in FIG. As shown in FIG. 16, the second frequency direction interpolation unit 1812 uses the frequency estimation result (indicated by cross-hatching in FIG. 16) output from the first frequency direction interpolation unit 1811. The direction of the transmission path is estimated, and the output of the first preceding transmission path estimation unit 152 outputs the transmission path estimation result (hatched position in FIG. 16) at the same carrier position as the carrier on which the transmission path estimation result exists.

以上に説明したように、第１の先行伝送路推定部１５２において、隣接シンボルのＳＰ信号を利用して生成した伝送路推定結果に対して、第１の先行伝送路推定部１５２で利用していない現シンボルのＳＰ信号の伝送路推定結果を反映させることで、さらに伝送路推定精度を向上させることができる。 As described above, in the first preceding transmission path estimation unit 152, the first preceding transmission path estimation unit 152 uses the transmission path estimation result generated using the SP signal of the adjacent symbol. By reflecting the transmission path estimation result of the SP signal with no current symbol, the transmission path estimation accuracy can be further improved.

図１７は、図１３に示される第２の先行伝送路推定部１８１ａの構成の他の例を概略的に示すブロック図である。第２の先行伝送路推定部１８１ａは、図１７に示されるように、伝送路推定結果記憶部１８１３と、時間方向内挿部１８１４と、第３の周波数方向内挿部１８１５とを備えている。 FIG. 17 is a block diagram schematically showing another example of the configuration of the second preceding transmission path estimation unit 181a shown in FIG. As shown in FIG. 17, the second preceding transmission path estimation unit 181a includes a transmission path estimation result storage unit 1813, a time direction interpolation unit 1814, and a third frequency direction interpolation unit 1815. .

図１８は、図１３に示される時間方向内挿部１８１４において、入力される伝送路推定結果のキャリア位置と出力する伝送路推定結果のキャリア位置を示す図である。伝送路推定結果記憶部１８１３は、第１の先行伝送路推定部１５２の出力である伝送路推定結果を、複数シンボル分記憶する。時間方向内挿部１８１４は、図１８に示されるように、伝送路推定結果記憶部１８１３から、同一キャリアの伝送路推定結果を複数シンボル分取り出し、時間方向の伝送路推定を行い、第１の先行伝送路推定部１５２の出力において、伝送路推定結果が存在するキャリアとは、異なるキャリア位置の伝送路推定を行う。時間方向内挿部１８１４は、図１８に示されるように、第１の先行伝送路推定部１５２の出力において、伝送路推定結果が存在するキャリア位置の中間のキャリア位置（図１８にクロスハッチングで示す位置）の伝送路推定を行う。 FIG. 18 is a diagram illustrating a carrier position of an input transmission path estimation result and a carrier position of a transmission path estimation result to be output in the time direction interpolation unit 1814 shown in FIG. The transmission path estimation result storage unit 1813 stores a transmission path estimation result, which is an output of the first preceding transmission path estimation unit 152, for a plurality of symbols. As illustrated in FIG. 18, the time direction interpolation unit 1814 extracts a plurality of symbols of transmission path estimation results for the same carrier from the transmission path estimation result storage unit 1813, performs transmission path estimation in the time direction, The output of the preceding transmission path estimation unit 152 performs transmission path estimation at a carrier position different from the carrier on which the transmission path estimation result exists. As shown in FIG. 18, the time direction interpolation unit 1814 outputs a carrier position in the middle of the carrier position where the transmission path estimation result exists in the output of the first preceding transmission path estimation unit 152 (cross hatching in FIG. 18). (The position shown) is estimated.

図１９は、図１３に示される第３の周波数方向内挿部１８１５において、入力される伝送路推定結果のキャリア位置と出力する伝送路推定結果のキャリア位置を示す図である。第３の周波数方向内挿部１８１５は、図１９に示されるように、時間方向内挿部１８１４の出力する伝送路推定結果をもとに、周波数方向の伝送路推定を行い、第１の先行伝送路推定部１５２の出力において伝送路推定結果が存在するキャリアと同一のキャリア位置の伝送路推定結果を出力する。 FIG. 19 is a diagram illustrating a carrier position of an input transmission path estimation result and a carrier position of a transmission path estimation result to be output in the third frequency direction interpolation unit 1815 illustrated in FIG. As shown in FIG. 19, the third frequency direction interpolation unit 1815 performs frequency direction transmission path estimation based on the transmission path estimation result output from the time direction interpolation unit 1814, and performs the first preceding The output of the transmission path estimation unit 152 outputs the transmission path estimation result at the same carrier position as the carrier on which the transmission path estimation result exists.

以上に説明したように、第１の先行伝送路推定部１５２において、隣接シンボルのＳＰ信号を利用して生成した伝送路推定結果に対して、第１の先行伝送路推定部１５２で利用していない、伝送路推定を行うキャリアの周辺のＳＰ信号の伝送路推定結果を反映させることで、さらに伝送路推定精度を向上させることができる。 As described above, in the first preceding transmission path estimation unit 152, the first preceding transmission path estimation unit 152 uses the transmission path estimation result generated using the SP signal of the adjacent symbol. The transmission path estimation accuracy can be further improved by reflecting the transmission path estimation result of the SP signal around the carrier performing the transmission path estimation.

１０，２０ＯＦＤＭ受信装置、１１アナログ部、１２Ａ／Ｄ変換部、１３直交復調部、１４ＦＦＴ部、１５，１８伝送路推定部、１６等化部、１７ＦＥＣ部、１５１スキャッタードパイロット（ＳＰ）伝送路推定部、１５２，１５２ａ，１５２ｂ第１の先行伝送路推定部、１５３時間方向伝送路推定部、１５４周波数方向伝送路推定部、１８１，１８１ａ第２の先行伝送路推定部、１５２１ＳＰ伝送路推定結果記憶部、１５２２ＦＩＲフィルタ内挿部、１５２３直線内挿部、１５２４誤差検出部、１５２５係数制御部、１８１１第１の周波数方向内挿部、１８１２第２の周波数方向内挿部、１８１３伝送路推定結果記憶部、１８１４時間方向内挿部、１８１５第３の周波数方向内挿部。 10, 20 OFDM receiver, 11 analog section, 12 A / D conversion section, 13 orthogonal demodulation section, 14 FFT section, 15, 18 transmission path estimation section, 16 equalization section, 17 FEC section, 151 scattered pilot ( SP) transmission path estimation section, 152, 152a, 152b first preceding transmission path estimation section, 153 time direction transmission path estimation section, 154 frequency direction transmission path estimation section, 181 and 181a second preceding transmission path estimation section, 1521 SP transmission path estimation result storage unit, 1522 FIR filter interpolation unit, 1523 linear interpolation unit, 1524 error detection unit, 1525 coefficient control unit, 1811 first frequency direction interpolation unit, 1812 second frequency direction interpolation unit , 1813 Transmission path estimation result storage unit, 1814 Time direction interpolation unit, 1815 Third frequency direction The inner insertion portion.

Claims

An OFDM receiver that receives an OFDM signal in which a plurality of SP signals are periodically inserted in a frequency direction and a time direction,
Using the value of the received SP signal and the value of a known reference SP signal, the frequency characteristic of the transmission line at the carrier position of the SP signal in each symbol is estimated, and the first transmission line based on the estimation An SP transmission path estimator that outputs an estimation result;
Using the first transmission path estimation result, the frequency characteristic of the transmission path at a predetermined specific carrier position in each symbol is estimated in advance, and the second transmission which is the estimation result of the specific carrier position A first preceding transmission path estimation unit that outputs a path estimation result;
Using the second transmission path estimation result, perform a transmission path estimation in the time direction, and output a third transmission path estimation result based on the estimation;
A frequency direction transmission path estimator that performs transmission path estimation in the frequency direction using the third transmission path estimation result and outputs a fourth transmission path estimation result based on the estimation;
With
The first preceding transmission path estimator is
An SP transmission path estimation result storage unit for storing the first transmission path estimation result over a plurality of symbols;
The first transmission path estimation result for the SP carrier positions of adjacent symbols before and after the symbol in which the specific carrier position exists is extracted from the SP transmission path estimation result storage unit, and the first for the adjacent symbols. FIR filter that considers the transmission path estimation result of the second transmission path estimation result in the same symbol, performs transmission path estimation in the frequency direction by the FIR filter, and outputs the second transmission path estimation result for the specific carrier position O FDM receiving apparatus you, comprising an inner insertion portion.

An OFDM receiver that receives an OFDM signal in which a plurality of SP signals are periodically inserted in a frequency direction and a time direction,
Using the value of the received SP signal and the value of a known reference SP signal, the frequency characteristic of the transmission line at the carrier position of the SP signal in each symbol is estimated, and the first transmission line based on the estimation An SP transmission path estimator that outputs an estimation result;
Using the first transmission path estimation result, the frequency characteristic of the transmission path at a predetermined specific carrier position in each symbol is estimated in advance, and the second transmission which is the estimation result of the specific carrier position A first preceding transmission path estimation unit that outputs a path estimation result;
Using the second transmission path estimation result, perform a transmission path estimation in the time direction, and output a third transmission path estimation result based on the estimation;
A frequency direction transmission path estimator that performs transmission path estimation in the frequency direction using the third transmission path estimation result and outputs a fourth transmission path estimation result based on the estimation;
With
The first preceding transmission path estimator is
An SP transmission path estimation result storage unit for storing the first transmission path estimation result over a plurality of symbols;
From the SP transmission path estimation result storage unit, the first transmission path estimation result for the SP carrier positions of adjacent symbols before and after the symbol where the specific carrier position is present, which is closest to the specific carrier position, 2 Only the transmission path estimation result of the SP carrier position at the point is extracted, the first transmission path estimation result for the two SP carrier positions is regarded as the transmission path estimation result within the same symbol, and the transmission path estimation is performed by linear interpolation. was carried out, O FDM reception apparatus you; and a linear interpolator for outputting said second channel estimation result for the particular carrier position.

The first preceding channel estimation unit,
Before SL takes out the first channel estimation result for SP carrier position of the symbols adjacent to the front and rear of existing symbols of the particular carrier position from the SP channel estimation result storage unit, wherein for said adjacent symbols second the first transmission path estimation result is regarded as a transmission path estimation result in the same symbol, it performs channel estimation in frequency direction by a FIR filter, and outputs the fifth transmission path estimation result of the for the particular carrier position, coefficient An FIR filter interpolating unit configured by a variable FIR filter;
The fifth transmission path estimation result for the carrier position of the SP signal is compared with the first transmission path estimation result for the carrier position of the SP signal in the same symbol extracted from the SP transmission path estimation result storage unit. An error detection unit that outputs the error information;
The OFDM receiving apparatus according to claim 1 , further comprising: a coefficient control unit that controls a coefficient of the FIR filter in the FIR filter interpolation unit based on the error information.

An OFDM receiver that receives an OFDM signal in which a plurality of SP signals are periodically inserted in a frequency direction and a time direction,
Using the value of the received SP signal and the value of a known reference SP signal, the frequency characteristic of the transmission line at the carrier position of the SP signal in each symbol is estimated, and the first transmission line based on the estimation An SP transmission path estimator that outputs an estimation result;
Using the first transmission path estimation result, the frequency characteristic of the transmission path at a predetermined specific carrier position in each symbol is estimated in advance, and the second transmission which is the estimation result of the specific carrier position A first preceding transmission path estimation unit that outputs a path estimation result;
Using the second transmission path estimation result, perform a transmission path estimation in the time direction, and output a third transmission path estimation result based on the estimation;
A frequency direction transmission path estimator that performs transmission path estimation in the frequency direction using the third transmission path estimation result and outputs a fourth transmission path estimation result based on the estimation;
With
Included in the second transmission path estimation result for a predetermined specific carrier position in the first preceding transmission path estimation section and the second transmission path estimation result in the first preceding transmission path estimation section Using the first transmission path estimation result of the SP transmission path estimation unit, the transmission path estimation of the same carrier position as a predetermined specific carrier position in the first preceding transmission path estimation unit is performed. conducted, further comprising a second prior channel estimation unit to output to the time direction transmission path estimating portion the estimation result as a transmission path estimation result of the sixth,
The channel estimation in the time direction by the time direction transmission channel estimation unit, O FDM reception apparatus you characterized by being performed using the transmission path estimation result of the sixth.

The second preceding transmission path estimator is
Using the second channel estimation result for the specific carrier position that is the output of the first preceding channel estimation unit, the channel estimation in the frequency direction is performed using the channel estimation result in the same symbol. A first frequency direction interpolation unit that outputs a seventh transmission path estimation result of a specific carrier position different from a predetermined specific carrier position in the first preceding transmission path estimation unit;
Using the seventh transmission path estimation result, the transmission path in the frequency direction is estimated, and the transmission path estimation result of the same carrier position as the predetermined specific carrier position in the first preceding transmission path estimation section is obtained. 5. The OFDM receiver according to claim 4 , further comprising: a second frequency direction interpolation unit that outputs to the time direction transmission path estimation unit as the sixth transmission path estimation result.

The second preceding transmission path estimator is
A transmission path estimation result storage section that stores the second transmission path estimation result for the specific carrier position, which is an output of the first preceding transmission path estimation section, over a plurality of symbols;
A transmission path estimation result of a specific carrier position different from a predetermined specific carrier position in the first preceding transmission path estimation section is extracted from the transmission path estimation result storage section for a plurality of symbols, and transmitted in the time direction. A time direction interpolation unit for performing path estimation;
The transmission path in the frequency direction is estimated using the transmission path estimation result of the time direction interpolation section, and the transmission path has the same carrier position as the predetermined specific carrier position in the first preceding transmission path estimation section The OFDM receiving apparatus according to claim 4 , further comprising: a third frequency direction interpolation unit that outputs an estimation result as the sixth transmission path estimation result.