JP3774168B2 - OFDM signal transmission apparatus, OFDM signal transmission apparatus, and OFDM signal reception apparatus - Google Patents

Description

【００１７】
ここで、ｈ_ijは、送信アンテナ３−２−ｉ（１≦ｉ≦Ｎ）から受信アンテナ４−１−ｊ（１≦ｊ≦Ｎ）への伝達係数である。
以下、本明細書においては、行列Ｈを伝達係数行列と呼ぶ。
行列Ｈⁱを用いると、ｉ番目のサブキャリアにおいて、前記送信パイロット信号Ｐ₁₁〜Ｐ_1N、Ｐ₂₁〜Ｐ_2N、・・・、Ｐ_N1〜Ｐ_NNと前記受信パイロット信号Ｐ_r21〜Ｐ_r1N、Ｐ_r21〜Ｐ_r2N、・・・、Ｐ_rN1〜Ｐ_rNNとの関係は、つぎのようになる。
【００１８】
【数２】

【００１９】
逆行列演算器４−３は、数２を利用して、前記伝達係数行列Ｈⁱの逆行列である（Ｈⁱ）^-1（伝達係数逆行列）を次のように求める。
【００２０】
【数３】

逆行列演算器４−３は、各サブキャリアの伝達係数逆行列をそれぞれ記憶する。
【００２１】
一方、伝達係数行列Ｈⁱを用いると、送信ＯＦＤＭ信号情報系列Ｔ₁、Ｔ₂、・・・Ｔ_Nと受信ＯＦＤＭ信号情報系列Ｒ₁、Ｒ₂、・・・、Ｒ_Nとの関係は、次のように表される。
【００２２】
【数４】

【００２３】
干渉キャンセラ４−４は、数４と、高速フーリエ変換器４−２−１〜４−２−Ｎから入力された受信ＯＦＤＭ信号情報系列Ｒ₁、Ｒ₂、・・・、Ｒ_Nと、逆行列演算器４−３から入力された伝達係数逆行列（Ｈⁱ）^-1と用いて、送信ＯＦＤＭ信号情報系列Ｔ₁、Ｔ₂、・・・Ｔ_Nを次のように復元する。
【００２４】
【数５】

【００２５】
以上説明したように、従来のＯＦＤＭ信号伝送装置は、ＯＦＤＭ信号送信装置がＯＦＤＭ信号情報系列と既知のパイロット信号と多重化し、ＯＦＤＭ信号受信装置が受信パイロット信号の位相・振幅を既知のパイロット信号で正規化することによって、伝達係数を求めていた。
【００２６】
そして、この従来のＯＦＤＭ信号伝送装置は、干渉キャンセルのための伝達係数逆行列をサブキャリアごとに求め、数５に示した演算を行うことにより、複数の送信アンテナから送信されたＯＦＤＭ信号相互の干渉をキャンセルし、送信ＯＦＤＭ信号情報系列を復元していた。
【００２７】
【発明が解決しようとしている課題】
しかし、上記従来のＯＦＤＭ信号伝送装置における伝達係数逆行列は、任意のＴＤＭＡバーストについて、このＴＤＭＡバーストの先頭にあるパイロット信号に基づき一回推定されるのみである。
一方、ＯＦＤＭ信号伝送装置における干渉キャンセルは、ＴＤＭＡバーストの後方にあるＯＦＤＭ情報信号について順次行われるものである。
【００２８】
したがって、上記従来のＯＦＤＭ信号伝送装置では、フェージングの時間的変動が大きい場合に、すなわち、ＴＤＭＡバーストの先頭にある信号と後方にある信号との信号劣化の度合いが大きく異なる場合に、伝達係数逆行列の推定精度が劣化するという問題があった。
【００２９】
そこで、本発明は、かかる事情に鑑み、フェージングの時間的変動が大きい場合であっても、伝達係数逆行列の推定精度が高く、かつ、十分に干渉キャンセルを行うことができる、ＯＦＤＭ信号伝送装置、ＯＦＤＭ信号送信装置およびＯＦＤＭ信号受信装置を提供することを目的とする。
【００３０】
【課題を解決するための手段】
本発明によれば、上記課題は、前記特許請求の範囲に記載の手段により解決される。
【００３１】
すなわち、請求項１に記載の発明は、Ｎ系統（Ｎは２以上の整数）のＯＦＤＭ信号情報系列のそれぞれに対応するＮ個の既知のパイロット信号を発生させるＮ個のパイロット信号発生器と、
前記Ｎ個のパイロット信号発生器にそれぞれ接続され、前記ＯＦＤＭ信号情報系列と前記パイロット信号とをそれぞれ多重化するＮ個のパイロット信号多重化器と、
【００３２】
前記Ｎ個のパイロット信号多重化器にそれぞれ接続され、該各パイロット信号多重化器が出力するＯＦＤＭ信号系列に対し高速逆フーリエ変換を行うＮ個の高速逆フーリエ変換器と、
【００３３】
前記Ｎ個の高速逆フーリエ変換器にそれぞれ接続され、該各高速逆フーリエ変換器が出力するＯＦＤＭ信号系列を、送信ＯＦＤＭ信号系列として同一の無線周波数で送信するＮ個の送信アンテナと、を有するＯＦＤＭ信号送信装置と、
【００３４】
前記Ｎ個の送信アンテナから送信され、空間で相互に干渉した送信ＯＦＤＭ信号系列を、受信ＯＦＤＭ信号系列として受信するＮ個の受信アンテナと、前記Ｎ個の受信アンテナにそれぞれ接続され、該各受信アンテナで受信された受信ＯＦＤＭ信号系列に対し高速フーリエ変換を行うＮ個の高速フーリエ変換器と、
【００３５】
前記Ｎ個の高速フーリエ変換器がそれぞれ出力する受信ＯＦＤＭ信号系列に含まれる受信パイロット信号をそれぞれ入力され、該各受信パイロット信号の受信振幅および位相と、前記各既知のパイロット信号の振幅および位相とから、各サブキャリアごとに、送信アンテナと受信アンテナの全ての組み合わせについての（Ｎ×Ｎ）個の伝達係数を要素とする行列を算出し、該行列の逆行列である伝達係数逆行列を算出し記憶する逆行列演算器と、
【００３６】
前記Ｎ個の高速フーリエ変換器がそれぞれ出力する受信ＯＦＤＭ信号系列に含まれる任意のサブキャリアに係る受信ＯＦＤＭ信号情報系列と、前記逆行列演算器が記憶する該任意のサブキャリアに係る前記伝達係数逆行列との積を演算し、該任意のサブキャリアに係る前記ＯＦＤＭ信号情報系列を出力する干渉キャンセラと、を有するＯＦＤＭ信号受信装置と、を備えるＯＦＤＭ信号伝送装置において、
【００３７】
前記ＯＦＤＭ信号受信装置における逆行列演算器は、前記各受信パイロット信号の受信振幅および位相と、前記各既知のパイロット信号の振幅および位相とを用いて補正伝達係数逆行列を算出する手段と、該補正伝達係数逆行列の各要素と前記記憶された伝達係数逆行列の各要素との加重平均を要素とする行列を算出する手段と、該算出された行列を新たな伝達係数逆行列として記憶する手段と、を有する、ことを特徴とするＯＦＤＭ信号伝送装置である。
【００３８】
請求項２に記載の発明は、請求項１に記載のＯＦＤＭ信号伝送装置であって、前記ＯＦＤＭ信号送信装置は、さらに、前記ＯＦＤＭ信号受信装置からの応答信号の受信品質に基づいて、前記パイロット信号が前記ＯＦＤＭ信号情報系列と多重化される周期を決定し該決定した周期を示す制御信号を出力するパイロット信号制御器を有し、
【００３９】
前記ＯＦＤＭ信号送信装置が有するパイロット信号多重化器は、前記パイロット信号制御器が出力する制御信号を入力され、該制御信号が示す周期でパイロット信号を前記ＯＦＤＭ信号情報系列と多重化し、
【００４０】
前記ＯＦＤＭ信号受信装置が有する高速フーリエ変換器は、前記パイロット信号制御器が出力する制御信号を入力され、高速フーリエ変換を行った受信パイロット信号を該制御信号が示す周期で前記逆行列演算器へ出力する、ことを特徴とするＯＦＤＭ信号伝送装置である。
【００４１】
請求項３に記載の発明は、Ｎ系統（Ｎは２以上の整数）のＯＦＤＭ信号情報系列のそれぞれに対応するＮ個の既知のパイロット信号を発生させるＮ個のパイロット信号発生器と、前記Ｎ個のパイロット信号発生器にそれぞれ接続され、前記ＯＦＤＭ信号情報系列と前記パイロット信号とをそれぞれ多重化するＮ個のパイロット信号多重化器と、
【００４２】
前記Ｎ個のパイロット信号多重化器にそれぞれ接続され、該各パイロット信号多重化器が出力するＯＦＤＭ信号系列に対し高速逆フーリエ変換を行うＮ個の高速逆フーリエ変換器と、前記Ｎ個の高速逆フーリエ変換器にそれぞれ接続され、該各高速逆フーリエ変換器が出力するＯＦＤＭ信号系列を、送信ＯＦＤＭ信号系列として同一の無線周波数で送信するＮ個の送信アンテナと、
を有するＯＦＤＭ信号送信装置であって、
【００４３】
前記Ｎ個の送信アンテナから送信され、空間で相互に干渉した送信ＯＦＤＭ信号系列を、受信ＯＦＤＭ信号系列として受信するＮ個の受信アンテナと、前記Ｎ個の受信アンテナにそれぞれ接続され、該各受信アンテナで受信された受信ＯＦＤＭ信号系列に対し高速フーリエ変換を行うＮ個の高速フーリエ変換器と、前記Ｎ個の高速フーリエ変換器がそれぞれ出力する受信ＯＦＤＭ信号系列に含まれる受信パイロット信号をそれぞれ入力され、該各受信パイロット信号の受信振幅および位相と、
【００４４】
前記各既知のパイロット信号の振幅および位相とから、各サブキャリアごとに、送信アンテナと受信アンテナの全ての組み合わせについての（Ｎ×Ｎ）個の伝達係数を要素とする行列を算出し、該行列の逆行列である伝達係数逆行列を算出し記憶する逆行列演算器と、
【００４５】
前記Ｎ個の高速フーリエ変換器がそれぞれ出力する受信ＯＦＤＭ信号系列に含まれる任意のサブキャリアに係る受信ＯＦＤＭ信号情報系列と、前記逆行列演算器が記憶する該任意のサブキャリアに係る前記伝達係数逆行列との積を演算し、該任意のサブキャリアに係る前記ＯＦＤＭ信号情報系列を出力する干渉キャンセラと、を有し、
【００４６】
前記逆行列演算器が、さらに、前記各受信パイロット信号の受信振幅および位相と、前記各既知のパイロット信号の振幅および位相とを用いて補正伝達係数逆行列を算出する手段と、該補正伝達係数逆行列の各要素と前記記憶された伝達係数逆行列の各要素との加重平均を要素とする行列を算出する手段と、該算出された行列を新たな伝達係数逆行列として記憶する手段とを有する、ＯＦＤＭ信号受信装置、へＯＦＤＭ信号系列を送信することを特徴とするＯＦＤＭ信号送信装置である。
【００４７】
請求項４に記載の発明は、請求項３に記載のＯＦＤＭ信号送信装置であって、さらに、前記ＯＦＤＭ信号受信装置からの応答信号の受信品質に基づいて、前記パイロット信号が前記ＯＦＤＭ信号情報系列と多重化される周期を決定し該決定した周期を示す制御信号を出力するパイロット信号制御器を有し、
【００４８】
前記パイロット信号多重化器は、前記パイロット信号制御器が出力する制御信号を入力され、該制御信号が示す周期でパイロット信号を前記ＯＦＤＭ信号情報系列と多重化し、前記パイロット信号制御器が出力する制御信号を入力され、高速フーリエ変換を行った受信パイロット信号を該制御信号が示す周期で前記逆行列演算器へ出力する前記高速フーリエ変換器を、請求項３に記載の高速フーリエ変換器に代えて有するＯＦＤＭ信号受信装置へＯＦＤＭ信号系列を送信する、
ことを特徴とするＯＦＤＭ信号送信装置である。
【００４９】
請求項５に記載の発明は、Ｎ系統（Ｎは２以上の整数）のＯＦＤＭ信号情報系列のそれぞれに対応するＮ個の既知のパイロット信号を発生させるＮ個のパイロット信号発生器と、前記Ｎ個のパイロット信号発生器にそれぞれ接続され、前記ＯＦＤＭ信号情報系列と前記パイロット信号とをそれぞれ多重化するＮ個のパイロット信号多重化器と、
【００５０】
前記Ｎ個のパイロット信号多重化器にそれぞれ接続され、該各パイロット信号多重化器が出力するＯＦＤＭ信号系列に対し高速逆フーリエ変換を行うＮ個の高速逆フーリエ変換器と、前記Ｎ個の高速逆フーリエ変換器にそれぞれ接続され、該各高速逆フーリエ変換器が出力するＯＦＤＭ信号系列を、送信ＯＦＤＭ 信号系列として同一の無線周波数で送信するＮ個の送信アンテナと、を有するＯＦＤＭ信号送信装置、から送信されるＯＦＤＭ信号系列を受信するＯＦＤＭ信号受信装置であって、
【００５１】
前記Ｎ個の送信アンテナから送信され、空間で相互に干渉した送信ＯＦＤＭ信号系列を、受信ＯＦＤＭ信号系列として受信するＮ個の受信アンテナと、
前記Ｎ個の受信アンテナにそれぞれ接続され、該各受信アンテナで受信された受信ＯＦＤＭ信号系列に対し高速フーリエ変換を行うＮ個の高速フーリエ変換器と、
【００５２】
前記Ｎ個の高速フーリエ変換器がそれぞれ出力する受信ＯＦＤＭ信号系列に含まれる受信パイロット信号をそれぞれ入力され、該各受信パイロット信号の受信振幅および位相と、前記各既知のパイロット信号の振幅および位相とから、各サブキャリアごとに、送信アンテナと受信アンテナの全ての組み合わせについての（Ｎ×Ｎ）個の伝達係数を要素とする行列を算出し、該行列の逆行列である伝達係数逆行列を算出し記憶する逆行列演算器と、
【００５３】
前記Ｎ個の高速フーリエ変換器がそれぞれ出力する受信ＯＦＤＭ信号系列に含まれる任意のサブキャリアに係る受信ＯＦＤＭ信号情報系列と、前記逆行列演算器が記憶する該任意のサブキャリアに係る前記伝達係数逆行列との積を演算し、該任意のサブキャリアに係る前記ＯＦＤＭ信号情報系列を出力する干渉キャンセラと、を有し、
【００５４】
前記逆行列演算器は、前記各受信パイロット信号の受信振幅および位相と、前記各既知のパイロット信号の振幅および位相とを用いて補正伝達係数逆行列を算出する手段と、該補正伝達係数逆行列の各要素と前記記憶された伝達係数逆行列の各要素との加重平均を要素とする行列を算出する手段と、該算出された行列を新たな伝達係数逆行列として記憶する手段と、を有する、ことを特徴とするＯＦＤＭ信号受信装置である。
【００５５】
請求項６に記載の発明は、請求項５に記載のＯＦＤＭ信号受信装置であって、前記ＯＦＤＭ信号受信装置からの応答信号の受信品質に基づいて、前記パイロット信号が前記ＯＦＤＭ信号情報系列と多重化される周期を決定し該決定した周期を示す制御信号を出力するパイロット信号制御器をさらに有し、前記パイロット信号多重化器が、前記パイロット信号制御器が出力する制御信号を入力され、該制御信号が示す周期でパイロット信号を前記ＯＦＤＭ信号情報系列と多重化する前記ＯＦＤＭ信号送信装置、から送信されるＯＦＤＭ信号系列を受信し、
【００５６】
前記高速フーリエ変換器は、前記パイロット信号制御器が出力する制御信号を入力され、高速フーリエ変換を行った受信パイロット信号を該制御信号が示す周期で前記逆行列演算器へ出力する、ことを特徴とするＯＦＤＭ信号受信装置である。
【００５７】
本発明によれば、逆行列演算器は、任意のＴＤＭＡバーストに含まれる受信パイロット信号に基づいて補正伝達係数逆行列を推定し、この推定した補正伝達係数逆行列の各要素と逆行列演算器が記憶している伝達係数逆行列の各要素との加重平均を各要素とする行列を算出し、この算出した行列を新たな伝達係数逆行列として記憶する。
【００５８】
このため、本発明によれば、逆行列演算器は、ＯＦＤＭ信号受信装置がＯＦＤＭ信号送信装置から繰り返し出射されるパイロット信号を順次受信するたびに、順次補正伝達係数逆行列を算出し、この順次算出した補正伝達係数逆行列を用いて伝達係数逆行列を順次補正することができる。
【００５９】
したがって、本発明によれば、任意のＴＤＭＡバーストについて、一回限り伝達係数逆行列を推定し、この推定した逆行列を補正することがなかった従来と比較して、伝達係数逆行列の推定精度を向上させることができる。
【００６０】
よって、本発明によれば、従来よりも高い精度で推定された伝達係数逆行列を受信ＯＦＤＭ情報信号における相互干渉のキャンセルに用いることができるため、送信ＯＦＤＭ情報信号を従来よりも正確に復元することができる。
【００６１】
【発明の実施の形態】
以下に、図面を参照しつつ、本発明の好適な実施の形態について詳細に説明する。
【００６２】
図１は、本発明の実施の形態に係るＯＦＤＭ信号伝送装置を示す図である。
本ＯＦＤＭ信号伝送装置は、図１に示すとおり、ＯＦＤＭ信号送信装置１とＯＦＤＭ信号受信装置２から構成される。
【００６３】
本実施の形態においては、ＯＦＤＭ信号送信装置１からＯＦＤＭ信号受信装置２へ送信されるべき情報信号系列をＯＦＤＭ信号情報系列とする。ＯＦＤＭ信号情報系列は、長さ（Ｌ×（Ｋ−１）＋Ｌ₀）のＯＦＤＭシンボル（ただしＬ₀≦Ｌ）からなり、Ｎ系統存在する。本実施の形態においては、各系統のＯＦＤＭ信号情報系列を、それぞれ、Ｔ₁、Ｔ₂、・・・Ｔ_Nとする。
【００６４】
パイロット信号発生器１−３−１〜１−３−Ｎは、これら各系統のＯＦＤＭ信号情報系列（Ｔ₁、Ｔ₂、・・・Ｔ_N）にそれぞれ対応する既知のパイロット信号Ｐ₁₁〜Ｐ_1N、Ｐ₂₁〜Ｐ_2N、・・・、Ｐ_N1〜Ｐ_NNを発生させる。
【００６５】
パイロット信号多重化器１−４−１〜１−４−Ｎは、ＯＦＤＭ信号情報系列（Ｔ₁、Ｔ₂、・・・Ｔ_N）と、既知のパイロット信号（Ｐ₁₁〜Ｐ_1N、Ｐ₂₁〜Ｐ_2N、・・・、Ｐ_N1〜Ｐ_NN）と、パイロット信号制御器１−５の制御信号とを入力され、ＯＦＤＭ信号情報系列（Ｔ₁、Ｔ₂、・・・Ｔ_N）と、各ＯＦＤＭ信号情報系列にそれぞれ対応する既知のパイロット信号（Ｐ₁₁〜Ｐ_1N、Ｐ₂₁〜Ｐ_2N、・・・、Ｐ_N1〜Ｐ_NN）とを、制御信号に基づき時間軸上においてそれぞれ多重化する。
【００６６】
図２は、本発明の実施の形態に係るパイロット信号多重化器の詳細な構成を示す図である。図２に示すように、パイロット信号多重化器１−４−ｎ（１≦ｎ≦Ｎ）は、ＯＦＤＭ信号情報系列分割回路１−４−ｎと、パイロット信号多重化回路１−４−ｎ−２とから構成される。
【００６７】
ＯＦＤＭ信号情報系列分割回路１−４−ｎは、ＯＦＤＭ信号情報系列Ｔ_nと、パイロット信号制御器３−５が出力する制御信号を入力される。制御信号は、パイロット信号（Ｐ₁₁〜Ｐ_1N、Ｐ₂₁〜Ｐ_2N、・・・、Ｐ_N1〜Ｐ_NN）とＯＦＤＭ信号情報系列（Ｔ₁、Ｔ₂、・・・Ｔ_N）とを多重化する周期を示す信号であり、本実施の形態においては、ＯＦＤＭシンボル長Ｌを示すものとする。
【００６８】
ＯＦＤＭ信号情報系列分割回路１−４−ｎは、入力されたＯＦＤＭ信号情報系列Ｔ_nを制御信号に従い長さＬのＯＦＤＭシンボルＴ_n1〜Ｔ_nKに分割し、それぞれ出力する。
【００６９】
パイロット信号多重化回路１−４−ｎ−２は、ＯＦＤＭ信号情報系列分割回路１−４−ｎが出力する長さＬのＯＦＤＭシンボルＴ_n1、Ｔ_n2・・・、Ｔ_nKと、パイロット信号発生器１−３−ｎが発生した既知のパイロット信号Ｐ₁₁〜Ｐ_1N、Ｐ₂₁〜Ｐ_2N、・・・、Ｐ_N1〜Ｐ_NNとを入力される。
【００７０】
パイロット信号多重化回路１−４−ｎ−２は、入力された長さＬのＯＦＤＭシンボルＴ_n1、Ｔ_n2・・・、Ｔ_nKの先頭に、入力された既知のパイロット信号Ｐ₁₁〜Ｐ_1N、Ｐ₂₁〜Ｐ_2N、・・・、Ｐ_N1〜Ｐ_NNをそれぞれ配置する。
【００７１】
このようにして、本ＯＦＤＭ信号情報系列分割回路１−４−ｎは、既知のパイロット信号Ｐ₁₁〜Ｐ_1N、Ｐ₂₁〜Ｐ_2N、・・・、Ｐ_N1〜Ｐ_NNを、ＯＦＤＭ信号情報系列（Ｔ₁、Ｔ₂、・・・Ｔ_N）の先頭および途中に、等間隔（Ｌ ＯＦＤＭシンボル）で挿入する。
【００７２】
パイロット信号制御器１−５は、出力するＯＦＤＭシンボル長Ｌを、ＯＦＤＭ信号受信装置２からの応答信号の受信品質に基づいて決定することができる。
したがって、パイロット信号制御器１−５は、ＯＦＤＭ信号受信装置２からの応答信号の受信品質が向上した場合にはＯＦＤＭシンボル長Ｌを長くし、逆に受信品質が劣化した場合はＯＦＤＭシンボル長Ｌを短くして、ＯＦＤＭシンボル長Ｌを適応的に制御する手段を有することができる。
【００７３】
パイロット信号多重化器１−４−ｎは、上記のようにして多重化したＯＦＤＭ信号系列を、各高速逆フーリエ変換器１−１−１〜１−１−Ｎへ出力する。
高速逆フーリエ変換器１−１−１〜１−１−Ｎにおいてそれぞれ高速逆フーリエ変換された各ＯＦＤＭ信号系列は、各送信アンテナ１−２−１〜１−２−Ｎにそれぞれ入力され、送信ＯＦＤＭ信号系列として、ＯＦＤＭ信号受信装置２に向けて送信される。
【００７４】
送信アンテナ１−２−１〜１−２−Ｎから送信されたＯＦＤＭ信号系列は、空間において相互に加算され、ＯＦＤＭ信号受信装置２は、この相互に加算された信号を受信ＯＦＤＭ信号系列として各受信アンテナ２−１−１〜２−１−Ｎで受信する。
【００７５】
受信ＯＦＤＭ信号系列においては、受信ＯＦＤＭ信号情報系列Ｒ₁₁〜Ｒ_1K、Ｒ₂₁〜Ｒ_2K、・・・、Ｒ_N1〜Ｒ_NKと、これらＲ₁₁〜Ｒ_1K、Ｒ₂₁〜Ｒ_2K、・・・、Ｒ_N1〜Ｒ_NKにそれぞれ対応した受信パイロット信号Ｐ_r111〜Ｐ_r1NK、Ｐ_r211〜Ｐ_r2NK、・・・、Ｐ_rN11〜Ｐ_rNNKとがそれぞれ時間軸上において多重化されている。
【００７６】
各高速フーリエ変換器２−２−１〜２−２−Ｎは、各受信アンテナ２−１−１〜２−１−Ｎで受信された信号を入力され、これら信号を高速フーリエ変換する。各高速フーリエ変換器２−２−１〜２−２−Ｎは、前記ＯＦＤＭシンボル長Ｌと同一の間隔で、受信パイロット信号を逆行列演算器４−３へ出力する。
【００７７】
各高速フーリエ変換器２−２−１〜２−２−Ｎに、ＯＦＤＭシンボル長Ｌを通知する手段としては、たとえば、ＯＦＤＭ信号送信装置１からＯＦＤＭ信号受信装置２へ送信される制御用信号に、ＯＦＤＭシンボル長Ｌを含ませる手段が可能である。
【００７８】
図３は、本実施の形態に係る逆行列演算器２−３の詳細な構成を示す図である。伝達係数逆行列演算回路２−３−１は、受信パイロット信号を入力される。伝達係数逆行列演算回路２−３−１は、入力されたｉ番目のサブキャリアにおける前記受信パイロット信号のうち先頭のＰ_r111〜Ｐ_r1N1、Ｐ_r211〜Ｐ_r21、・・・、Ｐ_rN11〜Ｐ_rNN1と、パイロット信号記憶回路２−３−２に記憶されている既知の送信パイロット信号Ｐ₁₁〜Ｐ_1N、Ｐ₂₁〜Ｐ_2N、・・・、Ｐ_N1〜Ｐ_NNと、数３とを用いて、伝達係数逆行列（Ｈ₁ ⁱ）^-1を算出し、伝達係数逆行列記憶回路２−３−３に格納する。
【００７９】
干渉キャンセラ２−４では、高速フーリエ変換器２−２−１〜２−２−Ｎが出力する受信ＯＦＤＭ信号情報系列Ｒ₁₁〜Ｒ_1K、Ｒ₂₁〜Ｒ_2K、・・・、Ｒ_N1〜Ｒ_NKと、逆行列演算器２−３が出力する伝達係数逆行列（Ｈⁱ）^-1を用いて、次のように送信ＯＦＤＭ信号情報系列Ｔ₁₁、Ｔ₂₁・・・、Ｔ_n1を復元する。
【００８０】
【数６】

【００８１】
次に、伝達係数逆行列演算回路２−３−１は、Ｐ_r112〜Ｐ_r1N2、Ｐ_r212〜Ｐ_r22、・・・、Ｐ_rN12〜Ｐ_rNN2と、パイロット信号記憶回路２−３−２に記憶されている既知の送信パイロット信号Ｐ₁₁〜Ｐ_1N、Ｐ₂₁〜Ｐ_2N、・・・、Ｐ_N1〜Ｐ_NNとを用いて、補正伝達係数逆行列（Ｈ₂ ^ri）^-1を次のように算出する。
【００８２】
【数７】

【００８３】
加重平均演算回路２−３−４は、伝達係数逆行列記憶回路２−３−３に格納された伝達係数逆行列（Ｈⁱ）^-1と、前記補正伝達係数逆行列（Ｈ₂ ^ri）^-1との加重平均（Ｈ₂ ⁱ）^-1を次のように算出する。
【００８４】
【数８】

数８において、μは忘却係数であり、０≦μ≦１である。
【００８５】
干渉キャンセラ２−４では、高速フーリエ変換器２−２−１〜２−２−Ｎが出力する受信ＯＦＤＭ信号情報系列Ｒ₁₂、Ｒ₂₂、・・・、Ｒ_N2と、逆行列演算器２−３が出力する伝達係数逆行列（Ｈ₂ ⁱ）^-1とを用いて、送信ＯＦＤＭ信号情報系列Ｔ₁₂、Ｔ₂₂・・・、Ｔ_n2を次のように復元する。
【００８６】
【数９】

伝達係数逆行列演算回路２−３は、このように、サブキャリアｉに係る受信パイロット信号が入力されるたびに、補正伝達係数逆行列（Ｈ_k-1 ^ri）^-1（２≦ｋ≦Ｋ）を数７〜数９に従い算出し、この算出された（Ｈ_k-1 ^ri）^-1を用いて伝達係数逆行列（Ｈ_k-1 ⁱ）^-1を算出する。
【００８７】
伝達係数逆行列演算回路２−３は、算出した伝達係数逆行列（Ｈ_k-1 ⁱ）^-1を用いて、受信ＯＦＤＭ信号情報系列における相互干渉をキャンセルし、送信ＯＦＤＭ信号情報系列を復元する。
【００８８】
本ＯＦＤＭ信号伝送装置は、以上のようにして、ｉ番目のサブキャリアで送信されたＯＦＤＭ信号情報系列Ｔ₁₁〜Ｔ_1K、Ｔ₂₁〜Ｔ_2K・・・、Ｔ_N1〜Ｔ_NKを復元し、送信ＯＦＤＭ信号情報系列Ｔ₁、Ｔ₂、・・・、Ｔ_Nとして再構成し、出力する。
【００８９】
以上説明したように、本ＯＦＤＭ信号伝送装置におけるＯＦＤＭ信号受信装置は、各サブキャリアについての干渉キャンセルのための伝達係数逆行列をＯＦＤＭシンボル長Ｌ間隔で順次補正する。
【００９０】
したがって、ＯＦＤＭ信号伝送装置によれば、高い精度で伝達係数逆行列を推定できる。よって、本ＯＦＤＭ信号伝送装置によれば、受信ＯＦＤＭ情報信号における相互干渉のキャンセルを高い精度で行うことができる。
【００９１】
【発明の効果】
以上説明したように、本発明によれば、ＯＦＤＭ信号受信装置は、各サブキャリアについての干渉キャンセルのための伝達係数逆行列を、ＯＦＤＭシンボル長Ｌ間隔で補正することができる。
【００９２】
したがって、本発明によれば、伝達係数逆行列を任意のＴＤＭＡバーストの先頭に位置するパイロット信号に基づいて一回推定するのみであった従来のＯＦＤＭ信号伝送と比較して、伝達係数逆行列の推定精度を向上させることができる。
【００９３】
また、本発明によれば、フェージングの時間的変動の大きさに応じて、パイロット信号の挿入の間隔を制御することができるため、フェージングの時間的変動を考慮した、より精度の高い伝達係数逆行列の推定を行うことができる。
【００９４】
よって、本発明によれば、高速なマルチパスフェージング環境下において高品質の信号伝送を行うことができるため、フェージングの時間的変動が大きい場合であっても、飛躍的な周波数利用効率を達成することができ、かつ、大容量・高速の信号伝送を行うことができる。
【図面の簡単な説明】
【図１】本発明の実施の形態に係るＯＦＤＭ信号伝送装置を示す図である。
【図２】本発明の実施の形態に係るパイロット信号多重化器の詳細な構成を示す図である。
【図３】本実施の形態に係る逆行列演算器２−３の詳細な構成を示す図である。
【図４】従来のＯＦＤＭ信号伝送装置を示す図である。
【図５】送信ＯＦＤＭ信号系列の例を示す図である。
【図６】受信アンテナ４−１−１〜４−１−Ｎで受信される受信ＯＦＤＭ信号系列の例を示す図である。
【符号の説明】
【符号の説明】
１ ＯＦＤＭ信号送信装置
１−１−１〜１−１−Ｎ 高速逆フーリエ変換器
１−２−１〜１−２−Ｎ 送信アンテナ
１−３−１〜１−３−Ｎ パイロット信号発生器
１−４−１〜１−４−Ｎ パイロット信号多重化器
１−４−ｎ パイロット信号多重化器
１−４−ｎ−１ ＯＦＤＭ信号情報系列分割回路
１−４−ｎ−２ パイロット信号多重化回路
１−５ パイロット信号制御器
２ ＯＦＤＭ信号受信装置
２−１−１〜２−１−Ｎ 受信アンテナ
２−２−１〜２−２−Ｎ 高速フーリエ変換器
２−３ 逆行列演算器
２−３−１ 伝達係数逆行列演算回路
２−３−２ パイロット信号記憶回路
２−３−３ 伝達係数逆行列記憶回路
２−３−４ 加重平均演算回路
２−４ 干渉キャンセラ
３ ＯＦＤＭ信号送信装置
３−１−１〜３−１−Ｎ 高速逆フーリエ変換器
３−２−１〜３−２−Ｎ 送信アンテナ
３−３−１〜３−３−Ｎ パイロット信号発生器
３−４−１〜３−４−Ｎ パイロット信号多重化器
４ ＯＦＤＭ信号受信装置
４−１−１〜４−１−Ｎ 受信アンテナ
４−２−１〜４−２−Ｎ 高速フーリエ変換器
４−３ 逆行列演算器
４−４ 干渉キャンセラ[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an OFDM (Orthogonal Frequency Division Multiplexing) signal transmission apparatus, an OFDM signal transmission apparatus, and an OFDM signal reception apparatus, and more particularly to an OFDM signal that performs communication using a plurality of transmission antennas and a plurality of reception antennas. The present invention relates to a transmission device, an OFDM signal transmission device, and an OFDM signal reception device.
[0002]
[Prior art]
[Transmission quality]
In broadband mobile communication, it is necessary to take measures against frequency selective fading in order to maintain a certain level of transmission quality in a multipath fading environment in mobile communication. As a countermeasure against this frequency selective fading, an OFDM method is known in which a transmission signal is divided into subcarrier groups orthogonal to each other and multicarrier transmission is performed.
[0003]
[Transmission capacity]
In broadband mobile communications, it is necessary to take measures to improve frequency utilization efficiency in order to increase the capacity in a limited frequency band. As a countermeasure for improving the frequency utilization efficiency, a multiple-input multiple-output (MIMO) channel is configured using a plurality of transmission antennas and a plurality of reception antennas in the same frequency band,
[0004]
The transmission coefficients for all combinations of transmission antennas and reception antennas are measured, and the inverse matrix of the transmission coefficient matrix (hereinafter referred to as “transmission coefficient inverse matrix”) having each of the transmission coefficients as an element is expressed as the received OFDM signal. A method is known in which mutual interference is canceled by multiplying a sequence to restore a transmitted OFDM signal sequence.
[0005]
[Transmission quality and transmission capacity]
Considering the system as described above, the conventional OFDM signal transmission apparatus is configured as shown in FIG. The conventional OFDM signal transmission apparatus will be described below.
[0006]
FIG. 4 is a diagram illustrating a conventional OFDM signal transmission apparatus. The conventional OFDM signal transmission apparatus includes an OFDM signal transmission apparatus 3 and an OFDM signal reception apparatus 4. The pilot signal multiplexers 3-4-1 to 3-4 -N receive OFDM signal information sequences T to be transmitted in the same TDMA burst.₁, T₂... T_NIs entered.
[0007]
The pilot signal multiplexers 3-4-1 to 3-4-N are output from the pilot signal generators 3-3-1 to 3-3-N.₁, T₂... T_NKnown pilot signals P respectively corresponding to₁₁~ P_1N, P_{twenty one}~ P_2N... P_N1~ P_NNIs entered.
[0008]
The pilot signal multiplexers 3-4-1 to 3-4 -N receive the input OFDM signal information sequence T₁, T₂... T_NAnd the known pilot signal P output from the pilot signal generators 3-3-1-3-3-N₁₁~ P_1N, P_{twenty one}~ P_2N... P_N1~ P_NNAre multiplexed on the time axis.
[0009]
Then, the pilot signal multiplexers 3-4-1 to 3-4-N output these multiplexed signals to the fast inverse Fourier transformers 3-1-1 to 3-1-1, respectively. The high-speed inverse Fourier transformers 3-1-1 to 3-1-1-N perform high-speed inverse Fourier transform on the input signal series and output the signals to the transmitting antennas 3-2-1 to 3-2-2N.
[0010]
The signal sequence input to each of the transmission antennas 3-2-1 to 2-2 -N is transmitted toward the OFDM signal receiving device 4 as a transmission OFDM signal sequence. The timing at which each transmission OFDM signal sequence is transmitted from the transmission antennas 3-2-1 to 2-2 -N is synchronized.
[0011]
FIG. 5 is a diagram illustrating an example of a transmission OFDM signal sequence. As shown in FIG. 5, the pilot signal is located at the head of the OFDM signal information sequence.
The transmission OFDM signal sequences transmitted from the transmission antennas 3-2-1 to 2-2 -N are added in space, and the OFDM signal receiving device 4 uses the added signal as a reception OFDM signal sequence for each reception. Reception is performed by the antenna 4-1-1-4-1 -N.
The timing at which each received OFDM signal sequence is received by the receiving antennas 4-2-1 to 4-2 -N is synchronized.
[0012]
FIG. 6 is a diagram illustrating an example of a received OFDM signal sequence received by the receiving antennas 4-1-1 to 4-1 -N. As shown in FIG. 6, in the received OFDM signal sequence, the received OFDM signal information sequence R₁, R₂・ ・ ・ ・ ・ ・ R_NAnd these R₁, R₂・ ・ ・ ・ ・ ・ R_NReceived pilot signals P corresponding to_r21~ P_r1N, P_r21~ P_r2N... P_rN1~ P_rNNAre multiplexed on the time axis.
[0013]
Signals received by the receiving antennas 4-1-1 to 4-1 -N are input to the fast Fourier transformers 4-2-1 to 4-2 -N and subjected to fast Fourier transform.
The transmission coefficient is as follows because each subcarrier of the OFDM signal is a signal having a constant amplitude and a constant phase within the OFDM symbol.
[0014]
There are N × N transmission coefficients, which are products of the number N of transmission antennas and the number N of reception antennas, for each subcarrier.
Therefore, assuming that the total number of subcarriers in the OFDM signal is M (M is an integer equal to or greater than 1), there are a total of N × N × M transfer coefficients.
Therefore, M × N × N transfer coefficients represent combinations of all transmission antennas and reception antennas related to all subcarriers.
[0015]
Focusing on the i-th (1 ≦ i ≦ N) subcarrier, the transfer coefficient of this subcarrier is expressed as a matrix H.ⁱThen the matrix HⁱCan be expressed as an N × N square matrix using the transmission pilot signal and the reception pilot signal as follows.
[0016]
[Expression 1]

[0017]
Where h_ijIs a transfer coefficient from the transmitting antenna 3-2-i (1 ≦ i ≦ N) to the receiving antenna 4-1-j (1 ≦ j ≦ N).
Hereinafter, in the present specification, the matrix H is referred to as a transfer coefficient matrix.
Matrix HⁱIs used for the transmission pilot signal P in the i-th subcarrier.₁₁~ P_1N, P_{twenty one}~ P_2N... P_N1~ P_NNAnd the received pilot signal P_r21~ P_r1N, P_r21~ P_r2N... P_rN1~ P_rNNThe relationship is as follows.
[0018]
[Expression 2]

[0019]
The inverse matrix calculator 4-3 uses Equation 2 to calculate the transfer coefficient matrix H.ⁱIs the inverse matrix of (Hⁱ)^-1(Transfer coefficient inverse matrix) is obtained as follows.
[0020]
[Equation 3]

The inverse matrix calculator 4-3 stores the transmission coefficient inverse matrix of each subcarrier.
[0021]
On the other hand, the transfer coefficient matrix HⁱIs used, the transmission OFDM signal information sequence T₁, T₂... T_NAnd received OFDM signal information sequence R₁, R₂・ ・ ・ ・ ・ ・ R_NThe relationship is expressed as follows.
[0022]
[Expression 4]

[0023]
The interference canceller 4-4 receives Equation 4 and the received OFDM signal information sequence R inputted from the fast Fourier transformers 4-2-1 to 4-2-N.₁, R₂・ ・ ・ ・ ・ ・ R_NAnd the inverse transfer coefficient matrix (Hⁱ)^-1And the transmitted OFDM signal information sequence T₁, T₂... T_NIs restored as follows:
[0024]
[Equation 5]

[0025]
As described above, in the conventional OFDM signal transmission apparatus, the OFDM signal transmission apparatus multiplexes the OFDM signal information sequence and the known pilot signal, and the OFDM signal reception apparatus uses the known pilot signal for the phase and amplitude of the reception pilot signal. The transfer coefficient was obtained by normalization.
[0026]
And this conventional OFDM signal transmission apparatus calculates | requires the transmission coefficient inverse matrix for interference cancellation for every subcarrier, and performs the operation | movement shown in several 5 by the OFDM signal transmitted from several transmission antennas. The interference was canceled and the transmission OFDM signal information sequence was restored.
[0027]
[Problems to be solved by the invention]
However, the inverse transfer coefficient matrix in the conventional OFDM signal transmission apparatus is only estimated once for any TDMA burst based on the pilot signal at the head of this TDMA burst.
On the other hand, interference cancellation in the OFDM signal transmission apparatus is sequentially performed for the OFDM information signal behind the TDMA burst.
[0028]
Therefore, in the conventional OFDM signal transmission apparatus, when the temporal variation of fading is large, that is, when the degree of signal degradation between the signal at the head of the TDMA burst and the signal at the back of the signal is greatly different, There was a problem that the estimation accuracy of the matrix deteriorated.
[0029]
Therefore, in view of such circumstances, the present invention provides an OFDM signal transmission apparatus that has high accuracy of estimating a transfer coefficient inverse matrix and can sufficiently perform interference cancellation even when fading temporal fluctuation is large. An object of the present invention is to provide an OFDM signal transmitting apparatus and an OFDM signal receiving apparatus.
[0030]
[Means for Solving the Problems]
According to the present invention, the above problem is solved by the means described in the claims.
[0031]
That is, the invention described in claim 1 includes N pilot signal generators that generate N known pilot signals corresponding to each of N systems (N is an integer of 2 or more) of OFDM signal information sequences;
N pilot signal multiplexers that are respectively connected to the N pilot signal generators and multiplex the OFDM signal information sequence and the pilot signals, respectively.
[0032]
N fast inverse Fourier transformers that are respectively connected to the N pilot signal multiplexers and perform fast inverse Fourier transform on the OFDM signal sequences output by the pilot signal multiplexers;
[0033]
N transmission antennas respectively connected to the N fast inverse Fourier transformers and transmitting the OFDM signal sequences output by the fast inverse Fourier transformers at the same radio frequency as transmission OFDM signal sequences. An OFDM signal transmission device;
[0034]
N reception antennas for receiving transmission OFDM signal sequences transmitted from the N transmission antennas and interfering with each other in space as reception OFDM signal sequences, and the N reception antennas, respectively. N fast Fourier transforms for performing a fast Fourier transform on the received OFDM signal sequence received by the antenna;
[0035]
Received pilot signals included in a received OFDM signal sequence output from each of the N fast Fourier transformers are respectively input, and received amplitudes and phases of the received pilot signals, and amplitudes and phases of the known pilot signals, For each subcarrier, a matrix having (N × N) transfer coefficients for all combinations of transmission antennas and reception antennas as elements is calculated, and a transfer coefficient inverse matrix that is an inverse matrix of the matrix is calculated. An inverse matrix calculator for storing and storing,
[0036]
The received OFDM signal information sequence related to an arbitrary subcarrier included in the received OFDM signal sequence output from each of the N fast Fourier transformers, and the transfer coefficient related to the arbitrary subcarrier stored in the inverse matrix calculator In an OFDM signal transmission apparatus comprising: an interference canceller that calculates a product with an inverse matrix and outputs the OFDM signal information sequence related to the arbitrary subcarrier,
[0037]
The inverse matrix calculator in the OFDM signal receiving apparatus calculates a corrected transfer coefficient inverse matrix using the reception amplitude and phase of each received pilot signal and the amplitude and phase of each known pilot signal; Means for calculating a matrix having a weighted average of each element of the corrected transfer coefficient inverse matrix and each element of the stored transfer coefficient inverse matrix, and storing the calculated matrix as a new transfer coefficient inverse matrix Means for transmitting an OFDM signal.
[0038]
  The invention according to claim 2 is the OFDM signal transmission apparatus according to claim 1, wherein the OFDM signal transmission apparatus further receives a response signal from the OFDM signal reception apparatus.Based on reception qualityA pilot signal controller that determines a period in which the pilot signal is multiplexed with the OFDM signal information sequence and outputs a control signal indicating the determined period;
[0039]
A pilot signal multiplexer included in the OFDM signal transmission device receives a control signal output from the pilot signal controller, multiplexes a pilot signal with the OFDM signal information sequence at a period indicated by the control signal,
[0040]
The fast Fourier transformer included in the OFDM signal receiver receives the control signal output from the pilot signal controller, and receives the received pilot signal subjected to the fast Fourier transform in the period indicated by the control signal to the inverse matrix calculator. This is an OFDM signal transmission device characterized in that the output is performed.
[0041]
According to a third aspect of the present invention, there are provided N pilot signal generators for generating N known pilot signals corresponding to each of N systems (N is an integer of 2 or more) of OFDM signal information sequences, and the N N pilot signal multiplexers respectively connected to the pilot signal generators for multiplexing the OFDM signal information sequence and the pilot signal, respectively.
[0042]
N fast inverse Fourier transformers that are respectively connected to the N pilot signal multiplexers and perform fast inverse Fourier transform on the OFDM signal sequence output by each pilot signal multiplexer, and the N fast fast Fourier transforms N transmitting antennas respectively connected to the inverse Fourier transformer and transmitting the OFDM signal sequence output from each fast inverse Fourier transformer at the same radio frequency as a transmission OFDM signal sequence;
An OFDM signal transmission device comprising:
[0043]
N reception antennas for receiving transmission OFDM signal sequences transmitted from the N transmission antennas and interfering with each other in space as reception OFDM signal sequences, and the N reception antennas, respectively. N fast Fourier transformers that perform fast Fourier transform on the received OFDM signal sequence received by the antenna, and a received pilot signal included in the received OFDM signal sequence that is output from each of the N fast Fourier transformers. Received amplitude and phase of each received pilot signal;
[0044]
A matrix having (N × N) transfer coefficients as elements for all combinations of transmission antennas and reception antennas is calculated for each subcarrier from the amplitude and phase of each known pilot signal. An inverse matrix calculator that calculates and stores an inverse matrix of a transfer coefficient that is an inverse matrix of
[0045]
The received OFDM signal information sequence related to an arbitrary subcarrier included in the received OFDM signal sequence output from each of the N fast Fourier transformers, and the transfer coefficient related to the arbitrary subcarrier stored in the inverse matrix calculator An interference canceller that calculates a product with an inverse matrix and outputs the OFDM signal information sequence related to the arbitrary subcarrier,
[0046]
The inverse matrix calculator further includes means for calculating a corrected transfer coefficient inverse matrix using the reception amplitude and phase of each received pilot signal and the amplitude and phase of each known pilot signal; and the corrected transfer coefficient Means for calculating a matrix whose element is a weighted average of each element of the inverse matrix and each element of the stored transfer coefficient inverse matrix, and means for storing the calculated matrix as a new transfer coefficient inverse matrix An OFDM signal transmitting apparatus characterized by transmitting an OFDM signal sequence to an OFDM signal receiving apparatus.
[0047]
  A fourth aspect of the present invention is the OFDM signal transmitting apparatus according to the third aspect, further comprising: a response signal from the OFDM signal receiving apparatus.Based on reception qualityA pilot signal controller that determines a period in which the pilot signal is multiplexed with the OFDM signal information sequence and outputs a control signal indicating the determined period;
[0048]
The pilot signal multiplexer receives a control signal output from the pilot signal controller, multiplexes the pilot signal with the OFDM signal information sequence in a period indicated by the control signal, and outputs the pilot signal controller 4. The fast Fourier transformer, which receives a signal and outputs a received pilot signal subjected to fast Fourier transform to the inverse matrix computing unit at a cycle indicated by the control signal, instead of the fast Fourier transformer according to claim 3. Transmitting an OFDM signal sequence to an OFDM signal receiver having
This is an OFDM signal transmitting apparatus.
[0049]
According to a fifth aspect of the present invention, N pilot signal generators for generating N known pilot signals corresponding to each of N systems (N is an integer of 2 or more) of OFDM signal information sequences, and the N N pilot signal multiplexers respectively connected to the pilot signal generators for multiplexing the OFDM signal information sequence and the pilot signal, respectively.
[0050]
N fast inverse Fourier transformers that are respectively connected to the N pilot signal multiplexers and perform fast inverse Fourier transform on the OFDM signal sequence output by each pilot signal multiplexer, and the N fast fast Fourier transforms An OFDM signal transmission device having N transmission antennas each connected to an inverse Fourier transformer and transmitting an OFDM signal sequence output from each fast inverse Fourier transformer at the same radio frequency as a transmission OFDM signal sequence; An OFDM signal receiving apparatus for receiving an OFDM signal sequence transmitted from
[0051]
N reception antennas that receive transmission OFDM signal sequences transmitted from the N transmission antennas and that interfere with each other in space as reception OFDM signal sequences;
N fast Fourier transformers connected to the N receiving antennas, respectively, for performing a fast Fourier transform on the received OFDM signal sequence received by the receiving antennas;
[0052]
Received pilot signals included in a received OFDM signal sequence output from each of the N fast Fourier transformers are respectively input, and received amplitudes and phases of the received pilot signals, and amplitudes and phases of the known pilot signals, For each subcarrier, a matrix having (N × N) transfer coefficients for all combinations of transmission antennas and reception antennas as elements is calculated, and a transfer coefficient inverse matrix that is an inverse matrix of the matrix is calculated. An inverse matrix calculator for storing and storing,
[0053]
The received OFDM signal information sequence related to an arbitrary subcarrier included in the received OFDM signal sequence output from each of the N fast Fourier transformers, and the transfer coefficient related to the arbitrary subcarrier stored in the inverse matrix calculator An interference canceller that calculates a product with an inverse matrix and outputs the OFDM signal information sequence related to the arbitrary subcarrier,
[0054]
  The inverse matrix calculator includes means for calculating a corrected transfer coefficient inverse matrix using the reception amplitude and phase of each received pilot signal and the amplitude and phase of each known pilot signal, and the corrected transfer coefficient inverse matrix Means for calculating a matrix whose element is a weighted average of each element of the stored transfer coefficient inverse matrix and means for storing the calculated matrix as a new transfer coefficient inverse matrix , Characterized byOFDM signal receiverIt is.
[0055]
  The invention according to claim 6 is the OFDM signal receiving apparatus according to claim 5, wherein the response signal from the OFDM signal receiving apparatus is received.Based on reception qualityA pilot signal controller that determines a period in which the pilot signal is multiplexed with the OFDM signal information sequence and outputs a control signal indicating the determined period, and the pilot signal multiplexer includes the pilot signal Receiving an OFDM signal sequence transmitted from the OFDM signal transmitting apparatus, which receives a control signal output from the controller and multiplexes a pilot signal with the OFDM signal information sequence in a period indicated by the control signal;
[0056]
The fast Fourier transformer receives a control signal output from the pilot signal controller, and outputs a received pilot signal subjected to fast Fourier transform to the inverse matrix calculator at a period indicated by the control signal. Is an OFDM signal receiving apparatus.
[0057]
According to the present invention, the inverse matrix calculator estimates a corrected transfer coefficient inverse matrix based on a received pilot signal included in an arbitrary TDMA burst, and each element of the estimated corrected transfer coefficient inverse matrix and the inverse matrix calculator Calculates a matrix having each element as a weighted average with each element of the transmission coefficient inverse matrix stored in the memory, and stores the calculated matrix as a new transmission coefficient inverse matrix.
[0058]
Therefore, according to the present invention, the inverse matrix calculator sequentially calculates the corrected transfer coefficient inverse matrix each time the OFDM signal receiving apparatus sequentially receives the pilot signals repeatedly emitted from the OFDM signal transmitting apparatus. By using the calculated corrected transfer coefficient inverse matrix, the transfer coefficient inverse matrix can be sequentially corrected.
[0059]
Therefore, according to the present invention, the transmission coefficient inverse matrix is estimated only once for an arbitrary TDMA burst, and the estimated accuracy of the transmission coefficient inverse matrix is compared with the conventional technique in which the estimated inverse matrix is not corrected. Can be improved.
[0060]
Therefore, according to the present invention, since the inverse transfer coefficient matrix estimated with higher accuracy than before can be used for canceling mutual interference in the received OFDM information signal, the transmission OFDM information signal is restored more accurately than before. be able to.
[0061]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the drawings.
[0062]
FIG. 1 is a diagram illustrating an OFDM signal transmission apparatus according to an embodiment of the present invention.
As shown in FIG. 1, the OFDM signal transmission apparatus includes an OFDM signal transmission apparatus 1 and an OFDM signal reception apparatus 2.
[0063]
In the present embodiment, an information signal sequence to be transmitted from OFDM signal transmitting apparatus 1 to OFDM signal receiving apparatus 2 is an OFDM signal information sequence. The OFDM signal information sequence has a length (L × (K−1) + L₀) OFDM symbol (where L₀≦ L), and there are N systems. In the present embodiment, each OFDM signal information sequence of each system is represented by T₁, T₂... T_NAnd
[0064]
The pilot signal generators 1-3-1 to 1-3-N receive OFDM signal information sequences (T₁, T₂... T_N) Known pilot signals P respectively corresponding to₁₁~ P_1N, P_{twenty one}~ P_2N... P_N1~ P_NNIs generated.
[0065]
The pilot signal multiplexers 1-4-1 to 1-4-N receive OFDM signal information sequences (T₁, T₂... T_N) And a known pilot signal (P₁₁~ P_1N, P_{twenty one}~ P_2N... P_N1~ P_NN) And the control signal of the pilot signal controller 1-5, and the OFDM signal information sequence (T₁, T₂... T_N) And known pilot signals (P) respectively corresponding to the respective OFDM signal information sequences₁₁~ P_1N, P_{twenty one}~ P_2N... P_N1~ P_NN) On the time axis based on the control signal.
[0066]
FIG. 2 is a diagram showing a detailed configuration of the pilot signal multiplexer according to the embodiment of the present invention. As shown in FIG. 2, the pilot signal multiplexer 1-4-4-n (1 ≦ n ≦ N) includes an OFDM signal information sequence division circuit 1-4-4-n and a pilot signal multiplexing circuit 1-4-4-n−. 2 is comprised.
[0067]
The OFDM signal information sequence dividing circuit 1-4-n is connected to the OFDM signal information sequence T._nThen, the control signal output from the pilot signal controller 3-5 is input. The control signal is a pilot signal (P₁₁~ P_1N, P_{twenty one}~ P_2N... P_N1~ P_NN) And OFDM signal information sequence (T₁, T₂... T_N), And in the present embodiment, it is an OFDM symbol length L.
[0068]
The OFDM signal information sequence dividing circuit 1-4-n receives the input OFDM signal information sequence T_nOFDM symbol T of length L according to the control signal_n1~ T_nKAnd output each.
[0069]
The pilot signal multiplexing circuit 1-4-4-n-2 has a length L OFDM symbol T output from the OFDM signal information sequence division circuit 1-4-4-n._n1, T_n2... T_nKAnd the known pilot signal P generated by the pilot signal generator 1-3-3-n.₁₁~ P_1N, P_{twenty one}~ P_2N... P_N1~ P_NNIs entered.
[0070]
The pilot signal multiplexing circuit 1-4-4-n-2 receives the input OFDM symbol T of length L._n1, T_n2... T_nKAt the beginning of the input known pilot signal P₁₁~ P_1N, P_{twenty one}~ P_2N... P_N1~ P_NNAre arranged respectively.
[0071]
In this way, the present OFDM signal information sequence dividing circuit 1-4-n is configured to transmit the known pilot signal P₁₁~ P_1N, P_{twenty one}~ P_2N... P_N1~ P_NN, OFDM signal information sequence (T₁, T₂... T_N) Are inserted at equal intervals (L OFDM symbols) at the beginning and in the middle.
[0072]
  The pilot signal controller 1-5 determines the output OFDM symbol length L of the response signal from the OFDM signal receiving apparatus 2.Based on reception qualityCan be determined.
  Therefore, the pilot signal controller 1-5 increases the OFDM symbol length L when the reception quality of the response signal from the OFDM signal receiving apparatus 2 is improved, and conversely when the reception quality deteriorates. TheKeep it shortAnd means for adaptively controlling the OFDM symbol length L.
[0073]
The pilot signal multiplexer 1-4-n outputs the OFDM signal sequence multiplexed as described above to each fast inverse Fourier transformer 1-1-1 to 1-1-N.
The respective OFDM signal sequences subjected to the fast inverse Fourier transform in the fast inverse Fourier transformer 1-1-1 to 1-1-N are respectively input to the transmission antennas 1-2-1 to 1-2N for transmission. It is transmitted toward the OFDM signal receiving apparatus 2 as an OFDM signal sequence.
[0074]
The OFDM signal sequences transmitted from the transmitting antennas 1-2-1 to 1-2N are added to each other in space, and the OFDM signal receiving apparatus 2 uses the mutually added signals as received OFDM signal sequences. Reception is performed by the receiving antennas 2-1-1 to 2-1 -N.
[0075]
In the received OFDM signal sequence, the received OFDM signal information sequence R₁₁~ R_1K, R_{twenty one}~ R_2K・ ・ ・ ・ ・ ・ R_N1~ R_NKAnd these R₁₁~ R_1K, R_{twenty one}~ R_2K・ ・ ・ ・ ・ ・ R_N1~ R_NKReceived pilot signals P corresponding to_r111~ P_r1NK, P_r211~ P_r2NK... P_rN11~ P_rNNKAre multiplexed on the time axis.
[0076]
Each fast Fourier transformer 2-2-1-2-2 -N receives signals received by the respective reception antennas 2-1-1-2-1 -N and performs fast Fourier transform on these signals. Each fast Fourier transformer 2-2-1 to 2-2N outputs the received pilot signal to the inverse matrix calculator 4-3 at the same interval as the OFDM symbol length L.
[0077]
  As means for notifying each fast Fourier transformer 2-2-1 to 2-2N of the OFDM symbol length L, for example, a control signal transmitted from the OFDM signal transmitting apparatus 1 to the OFDM signal receiving apparatus 2 is used. , OFDM symbol length LMeans to includeIs possible.
[0078]
FIG. 3 is a diagram showing a detailed configuration of the inverse matrix calculator 2-3 according to the present embodiment. The reception coefficient is input to the transmission coefficient inverse matrix calculation circuit 2-3-1. The transfer coefficient inverse matrix calculation circuit 2-3-1 uses the first P of the received pilot signal in the input i-th subcarrier._r111~ P_r1N1, P_r211~ P_r21... P_rN11~ P_rNN1And the known transmission pilot signal P stored in the pilot signal storage circuit 2-3-2₁₁~ P_1N, P_{twenty one}~ P_2N... P_N1~ P_NNAnd Equation 3 and the inverse transfer coefficient (H₁ ⁱ)^-1Is stored in the transfer coefficient inverse matrix storage circuit 2-3-3.
[0079]
In the interference canceller 2-4, the received OFDM signal information sequence R output from the fast Fourier transformers 2-2-1 to 2-2N₁₁~ R_1K, R_{twenty one}~ R_2K・ ・ ・ ・ ・ ・ R_N1~ R_NKAnd the inverse transfer coefficient matrix (Hⁱ)^-1Is used to transmit OFDM signal information sequence T as follows:₁₁, T_{twenty one}... T_n1To restore.
[0080]
[Formula 6]

[0081]
Next, the transfer coefficient inverse matrix arithmetic circuit 2-3-1_r112~ P_r1N2, P_r212~ P_r22... P_rN12~ P_rNN2And the known transmission pilot signal P stored in the pilot signal storage circuit 2-3-2₁₁~ P_1N, P_{twenty one}~ P_2N... P_N1~ P_NNAnd the corrected transfer coefficient inverse matrix (H₂ ^ri)^-1Is calculated as follows.
[0082]
[Expression 7]

[0083]
The weighted average arithmetic circuit 2-3-4 has a transfer coefficient inverse matrix (H) stored in the transfer coefficient inverse matrix storage circuit 2-3-3.ⁱ)^-1And the corrected transfer coefficient inverse matrix (H₂ ^ri)^-1And weighted average (H₂ ⁱ)^-1Is calculated as follows.
[0084]
[Equation 8]

In Equation 8, μ is a forgetting factor, and 0 ≦ μ ≦ 1.
[0085]
In the interference canceller 2-4, the received OFDM signal information sequence R output from the fast Fourier transformers 2-2-1 to 2-2N₁₂, R_{twenty two}・ ・ ・ ・ ・ ・ R_N2And the inverse transfer coefficient matrix (H₂ ⁱ)^-1And transmit OFDM signal information sequence T using₁₂, T_{twenty two}... T_n2Is restored as follows:
[0086]
[Equation 9]

In this way, the transfer coefficient inverse matrix computing circuit 2-3, every time the received pilot signal related to the subcarrier i is input, the corrected transfer coefficient inverse matrix (H_k-1 ^ri)^-1(2 ≦ k ≦ K) is calculated according to Equations 7 to 9, and the calculated (H_k-1 ^ri)^-1Using the inverse transfer coefficient (H_k-1 ⁱ)^-1Is calculated.
[0087]
The transmission coefficient inverse matrix computing circuit 2-3 calculates the calculated transmission coefficient inverse matrix (H_k-1 ⁱ)^-1Is used to cancel the mutual interference in the received OFDM signal information sequence and restore the transmitted OFDM signal information sequence.
[0088]
The present OFDM signal transmission apparatus, as described above, transmits the OFDM signal information sequence T transmitted on the i-th subcarrier.₁₁~ T_1K, T_{twenty one}~ T_2K... T_N1~ T_NKAnd transmit OFDM signal information sequence T₁, T₂... T_NAnd reconstruct as
[0089]
As described above, the OFDM signal receiving apparatus in this OFDM signal transmission apparatus sequentially corrects the inverse matrix of the transfer coefficient for interference cancellation for each subcarrier at intervals of the OFDM symbol length L.
[0090]
Therefore, according to the OFDM signal transmission apparatus, the inverse transfer coefficient matrix can be estimated with high accuracy. Therefore, according to this OFDM signal transmission apparatus, it is possible to cancel the mutual interference in the received OFDM information signal with high accuracy.
[0091]
【The invention's effect】
As described above, according to the present invention, the OFDM signal receiving apparatus can correct the inverse transfer coefficient matrix for interference cancellation for each subcarrier with an OFDM symbol length L interval.
[0092]
Therefore, according to the present invention, compared with the conventional OFDM signal transmission in which the transmission coefficient inverse matrix is only estimated once based on the pilot signal located at the head of an arbitrary TDMA burst, The estimation accuracy can be improved.
[0093]
Further, according to the present invention, since the pilot signal insertion interval can be controlled in accordance with the magnitude of the temporal fluctuation of fading, a more accurate transmission coefficient inverse considering the temporal fluctuation of fading is possible. Matrix estimation can be performed.
[0094]
Therefore, according to the present invention, high-quality signal transmission can be performed in a high-speed multipath fading environment, so that dramatic frequency utilization efficiency can be achieved even when fading temporal fluctuation is large. And high-capacity and high-speed signal transmission.
[Brief description of the drawings]
FIG. 1 is a diagram illustrating an OFDM signal transmission apparatus according to an embodiment of the present invention.
FIG. 2 is a diagram showing a detailed configuration of a pilot signal multiplexer according to the embodiment of the present invention.
FIG. 3 is a diagram showing a detailed configuration of an inverse matrix calculator 2-3 according to the present embodiment.
FIG. 4 is a diagram illustrating a conventional OFDM signal transmission apparatus.
FIG. 5 is a diagram illustrating an example of a transmission OFDM signal sequence.
FIG. 6 is a diagram illustrating an example of a received OFDM signal sequence received by receiving antennas 4-1-1 to 4-1-N.
[Explanation of symbols]
[Explanation of symbols]
1 OFDM signal transmitter
1-1-1 to 1-1-N fast inverse Fourier transformer
1-2-1 to 1-2-N transmitting antenna
1-3-1 to 1-3-N pilot signal generator
1-4-1-1-4-N Pilot signal multiplexer
1-4-n pilot signal multiplexer
1-4-4-n-1 OFDM signal information sequence division circuit
1-4-4-n-2 pilot signal multiplexing circuit
1-5 Pilot signal controller
2 OFDM signal receiver
2-1-1 to 2-1-N receiving antenna
2-2-1 to 2-2N Fast Fourier Transform
2-3 Inverse matrix calculator
2-3-1 Transfer coefficient inverse matrix arithmetic circuit
2-3-2 Pilot signal storage circuit
2-3-3 Inverse transfer coefficient memory circuit
2-3-4 Weighted average arithmetic circuit
2-4 Interference canceller
3 OFDM signal transmitter
3-1-1 to 1-3-N Fast Inverse Fourier Transformer
3-2-1-3-2-N Transmitting antenna
3-3-1 to 3-3-3 pilot signal generator
3-4-1 to 3-4-N pilot signal multiplexer
4 OFDM signal receiver
4-1-1 to 4-1-N receiving antenna
4-2-1 to 4-2-N Fast Fourier Transformer
4-3 Inverse matrix calculator
4-4 Interference canceller

Claims (6)

N pilot signal generators for generating N known pilot signals corresponding to each of N systems (N is an integer of 2 or more) of OFDM signal information sequences;
N pilot signal multiplexers that are respectively connected to the N pilot signal generators and multiplex the OFDM signal information sequence and the pilot signals, respectively.
N fast inverse Fourier transformers that are respectively connected to the N pilot signal multiplexers and perform fast inverse Fourier transform on the OFDM signal sequences output by the pilot signal multiplexers;
N transmitting antennas respectively connected to the N fast inverse Fourier transformers and transmitting the OFDM signal sequences output by the fast inverse Fourier transformers at the same radio frequency as transmission OFDM signal sequences;
An OFDM signal transmission device having:
N reception antennas that receive transmission OFDM signal sequences transmitted from the N transmission antennas and that interfere with each other in space as reception OFDM signal sequences;
N fast Fourier transformers connected to the N receiving antennas, respectively, for performing a fast Fourier transform on the received OFDM signal sequence received by the receiving antennas;
Received pilot signals included in a received OFDM signal sequence output from each of the N fast Fourier transformers are respectively input, and received amplitudes and phases of the received pilot signals, and amplitudes and phases of the known pilot signals, For each subcarrier, a matrix having (N × N) transfer coefficients for all combinations of transmission antennas and reception antennas as elements is calculated, and a transfer coefficient inverse matrix that is an inverse matrix of the matrix is calculated. An inverse matrix calculator for storing and storing,
The received OFDM signal information sequence related to an arbitrary subcarrier included in the received OFDM signal sequence output from each of the N fast Fourier transformers, and the transfer coefficient related to the arbitrary subcarrier stored in the inverse matrix calculator An interference canceller that calculates a product with an inverse matrix and outputs the OFDM signal information sequence related to the arbitrary subcarrier;
An OFDM signal receiving device comprising:
In an OFDM signal transmission device comprising:
The inverse matrix calculator in the OFDM signal receiver is:
Means for calculating an inverse matrix of a corrected transfer coefficient using the reception amplitude and phase of each received pilot signal and the amplitude and phase of each known pilot signal;
Means for calculating a matrix having as an element a weighted average of each element of the corrected transfer coefficient inverse matrix and each element of the stored transfer coefficient inverse matrix;
Means for storing the calculated matrix as a new transfer coefficient inverse matrix;
Having
An OFDM signal transmission apparatus characterized by the above. The OFDM signal transmission device according to claim 1,
The OFDM signal transmitting apparatus further determines a period in which the pilot signal is multiplexed with the OFDM signal information sequence based on reception quality of a response signal from the OFDM signal receiving apparatus, and performs control indicating the determined period A pilot signal controller for outputting a signal;
A pilot signal multiplexer included in the OFDM signal transmission device receives a control signal output from the pilot signal controller, multiplexes a pilot signal with the OFDM signal information sequence at a period indicated by the control signal,
The fast Fourier transformer included in the OFDM signal receiver receives the control signal output from the pilot signal controller, and receives the received pilot signal subjected to the fast Fourier transform in the period indicated by the control signal to the inverse matrix calculator. Output,
An OFDM signal transmission apparatus characterized by the above. N pilot signal generators for generating N known pilot signals corresponding to each of N systems (N is an integer of 2 or more) of OFDM signal information sequences;
N pilot signal multiplexers that are respectively connected to the N pilot signal generators and multiplex the OFDM signal information sequence and the pilot signals, respectively.
N fast inverse Fourier transformers that are respectively connected to the N pilot signal multiplexers and perform fast inverse Fourier transform on the OFDM signal sequences output by the pilot signal multiplexers;
N transmitting antennas respectively connected to the N fast inverse Fourier transformers and transmitting the OFDM signal sequences output by the fast inverse Fourier transformers at the same radio frequency as transmission OFDM signal sequences;
An OFDM signal transmission device comprising:
N reception antennas for receiving transmission OFDM signal sequences transmitted from the N transmission antennas and interfering with each other in space as reception OFDM signal sequences, and the N reception antennas, respectively. N fast Fourier transformers that perform fast Fourier transform on the received OFDM signal sequence received by the antenna, and a received pilot signal included in the received OFDM signal sequence that is output from each of the N fast Fourier transformers. From the reception amplitude and phase of each received pilot signal and the amplitude and phase of each known pilot signal, (N × N) for all combinations of transmit antennas and receive antennas for each subcarrier. Calculates a matrix whose elements are transfer coefficients of, and calculates and stores a transfer coefficient inverse matrix which is an inverse matrix of the matrix A matrix calculator, a received OFDM signal information sequence related to an arbitrary subcarrier included in the received OFDM signal sequence output by each of the N fast Fourier transformers, and the arbitrary subcarrier stored by the inverse matrix calculator An interference canceller that computes a product of the inverse matrix of the transfer coefficient according to and outputs the OFDM signal information sequence related to the arbitrary subcarrier, and the inverse matrix calculator further includes the reception pilots Means for calculating a corrected transfer coefficient inverse matrix using the received amplitude and phase of the signal and the amplitude and phase of each known pilot signal; each element of the corrected transfer coefficient inverse matrix and the stored transfer coefficient inverse Means for calculating a matrix whose element is a weighted average with each element of the matrix, and means for storing the calculated matrix as a new inverse transfer coefficient matrix Signal receiving device,
An OFDM signal transmitting apparatus, which transmits an OFDM signal sequence to The OFDM signal transmitting apparatus according to claim 3, wherein
Further, pilot signal control for determining a period in which the pilot signal is multiplexed with the OFDM signal information sequence and outputting a control signal indicating the determined period based on reception quality of the response signal from the OFDM signal receiving apparatus Have a bowl,
The pilot signal multiplexer receives a control signal output from the pilot signal controller, multiplexes a pilot signal with the OFDM signal information sequence at a period indicated by the control signal,
4. The fast Fourier transformer, which receives a control signal output from the pilot signal controller and outputs a received pilot signal subjected to fast Fourier transform to the inverse matrix calculator at a period indicated by the control signal. An OFDM signal sequence is transmitted to an OFDM signal receiving device having instead of the described Fast Fourier Transform,
An OFDM signal transmitter characterized by the above. N pilot signal generators for generating N known pilot signals corresponding to each of N systems (N is an integer of 2 or more) of OFDM signal information sequences, and connected to the N pilot signal generators, respectively N pilot signal multiplexers for multiplexing the OFDM signal information sequence and the pilot signal, respectively, and the N pilot signal multiplexers, respectively. N fast inverse Fourier transforms that perform fast inverse Fourier transform on the OFDM signal sequences to be connected to the N fast inverse Fourier transforms, and the OFDM signal sequences output by the fast inverse Fourier transforms are respectively N transmission antennas that transmit at the same radio frequency as a transmission OFDM signal sequence,
An OFDM signal receiving apparatus for receiving an OFDM signal sequence transmitted from
N reception antennas that receive transmission OFDM signal sequences transmitted from the N transmission antennas and that interfere with each other in space as reception OFDM signal sequences;
N fast Fourier transformers connected to the N receiving antennas, respectively, for performing a fast Fourier transform on the received OFDM signal sequence received by the receiving antennas;
Received pilot signals included in a received OFDM signal sequence output from each of the N fast Fourier transformers are respectively input, and received amplitudes and phases of the received pilot signals, and amplitudes and phases of the known pilot signals, For each subcarrier, a matrix having (N × N) transfer coefficients for all combinations of transmission antennas and reception antennas as elements is calculated, and a transfer coefficient inverse matrix that is an inverse matrix of the matrix is calculated. An inverse matrix calculator for storing and storing,
The received OFDM signal information sequence related to an arbitrary subcarrier included in the received OFDM signal sequence output from each of the N fast Fourier transformers, and the transfer coefficient related to the arbitrary subcarrier stored in the inverse matrix calculator An interference canceller that calculates a product with an inverse matrix and outputs the OFDM signal information sequence related to the arbitrary subcarrier,
The inverse matrix calculator is
Means for calculating an inverse matrix of a corrected transfer coefficient using the reception amplitude and phase of each received pilot signal and the amplitude and phase of each known pilot signal;
Means for calculating a matrix having as an element a weighted average of each element of the corrected transfer coefficient inverse matrix and each element of the stored transfer coefficient inverse matrix;
Means for storing the calculated matrix as a new transfer coefficient inverse matrix;
Having
An OFDM signal receiving apparatus . The OFDM signal receiving apparatus according to claim 5, wherein
A pilot signal controller for determining a period in which the pilot signal is multiplexed with the OFDM signal information sequence based on reception quality of the response signal from the OFDM signal receiving apparatus and outputting a control signal indicating the determined period; Further, the OFDM signal transmitting apparatus, wherein the pilot signal multiplexer receives the control signal output from the pilot signal controller, and multiplexes the pilot signal with the OFDM signal information sequence in a period indicated by the control signal ,
Receive the OFDM signal sequence transmitted from
The fast Fourier transformer receives a control signal output from the pilot signal controller, and outputs a received pilot signal subjected to fast Fourier transform to the inverse matrix calculator at a period indicated by the control signal.
An OFDM signal receiving apparatus.

Images