JP2012147390A - Wireless communications system, transmitting device, and receiving device - Google Patents
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本発明は、シングルキャリア伝送の無線通信における通信の秘匿性を向上させる無線通信システム、送信装置および受信装置に関する。 The present invention relates to a wireless communication system, a transmission apparatus, and a reception apparatus that improve communication confidentiality in single-carrier transmission wireless communication.
無線通信は電波の傍受が容易であり、通信の秘匿性を高めることが重要な課題になっている。この対処方法としては、情報を暗号化して伝送する方法がある。情報の暗号化としては、図１２に示すようにスクランブラ／デスクランブラを用いることがよく知られている（非特許文献１）。 Wireless communication is easy to intercept radio waves, and increasing the confidentiality of communication is an important issue. As a coping method, there is a method of transmitting information after encryption. As information encryption, it is well known to use a scrambler / descrambler as shown in FIG. 12 (Non-Patent Document 1).
図１２において、送信装置５０は、スクランブラ５１、擬似ランダムパターン発生器５２、変調手段５３を備える。受信装置６０は、復調手段６１、デスクランブラ６２、擬似ランダムパターン発生器６３を備える。 In FIG. 12, the transmission device 50 includes a scrambler 51, a pseudo random pattern generator 52, and modulation means 53. The receiving device 60 includes a demodulating means 61, a descrambler 62, and a pseudo random pattern generator 63.
スクランブラ５１は送信データを入力し、疑似ランダムパターン発生器５２が発生した特定のスクランブルパターンによりスクランブルする。スクランブルされたデータは変調手段５３で変調され、送信信号が生成される。受信装置の受信信号は復調手段６１で復調され、デスクランブラ６２に入力する。デスクランブラ６２は、復調信号を疑似ランダムパターン発生器６３が発生するスクランブルパターンによりデスクランブルし、受信データを出力する。ここで、送信装置の擬似ランダムパターン発生器５２と、受信装置の擬似ランダムパターン発生器６３において、共通のスクランブルパターンを用いることにより、受信装置では送信装置から送信された送信データを復元することができる。すなわち、従来の無線通信システムでは、疑似ランダムパターン発生器５２，６３が発生するスクランブルパターンを知っている者のみが、送信装置から送信された送信データを復元することができる。 The scrambler 51 receives the transmission data and scrambles with a specific scramble pattern generated by the pseudo random pattern generator 52. The scrambled data is modulated by the modulation means 53, and a transmission signal is generated. The received signal of the receiving device is demodulated by the demodulating means 61 and input to the descrambler 62. The descrambler 62 descrambles the demodulated signal with the scramble pattern generated by the pseudo random pattern generator 63, and outputs received data. Here, in the pseudo random pattern generator 52 of the transmission device and the pseudo random pattern generator 63 of the reception device, the reception device can restore the transmission data transmitted from the transmission device by using a common scramble pattern. it can. That is, in the conventional wireless communication system, only the person who knows the scramble pattern generated by the pseudo random pattern generators 52 and 63 can restore the transmission data transmitted from the transmission apparatus.
従来の無線通信システムでは、不正に傍受を試みるものが、送信装置および受信装置で共通に用いるスクランブルパターンを取得すると、傍受したデータを元データに復元することができるので、十分な秘匿性が得られない問題があった。 In a conventional wireless communication system, a person who attempts unauthorized interception can acquire sufficient confidentiality because the intercepted data can be restored to the original data by acquiring a scramble pattern that is commonly used by the transmission apparatus and the reception apparatus. There was a problem that was not possible.
本発明は、周波数領域での信号処理により通信の秘匿性を向上させることができる無線通信システム、送信装置および受信装置を提供することを目的とする。 An object of this invention is to provide the radio | wireless communications system, the transmitter, and the receiver which can improve the secrecy of communication by the signal processing in a frequency domain.
第１の発明は、無線信号を送受信する送信装置および受信装置により構成される無線通信システムであって、送信装置は、データ信号を変調して変調信号を出力する変調手段と、変調信号を第１の周波数領域の信号に変換する第１の時間−周波数変換手段と、第１の周波数領域の信号に対して、受信装置と共有する所定の周波数特性を用いて演算処理を行う第１の周波数処理手段と、第１の周波数処理手段の出力信号を第１の時間領域の信号に変換して出力する第１の周波数−時間変換手段とを備え、第１の時間領域の信号を無線信号として送信する構成である。受信装置は、受信した無線信号を第２の周波数領域の信号に変換する第２の時間−周波数変換手段と、第２の周波数領域の信号に対して、送信装置と共有する所定の周波数特性の逆特性の周波数特性を用いて演算処理を行う第２の周波数処理手段と、第２の周波数処理手段の出力信号を第２の時間領域の信号に変換して出力する第２の周波数−時間変換手段とを備え、第２の時間領域の信号を復調して送信装置から送信されたデータ信号を復元する構成である。 A first aspect of the present invention is a wireless communication system including a transmission device and a reception device that transmit and receive a radio signal, wherein the transmission device modulates a data signal and outputs a modulation signal, A first time-frequency conversion means for converting the first frequency domain signal, and a first frequency for performing arithmetic processing on the first frequency domain signal using a predetermined frequency characteristic shared with the receiving apparatus. Processing means and first frequency-time conversion means for converting the output signal of the first frequency processing means into a first time domain signal and outputting the signal, and the first time domain signal as a radio signal It is the structure which transmits. The receiving device has a second time-frequency converting means for converting the received radio signal into a second frequency domain signal, and a predetermined frequency characteristic shared with the transmitting device for the second frequency domain signal. Second frequency processing means for performing arithmetic processing using the frequency characteristics of the reverse characteristics, and second frequency-time conversion for converting the output signal of the second frequency processing means into a signal in the second time domain and outputting it Means for demodulating the second time-domain signal and restoring the data signal transmitted from the transmission device.
第１の発明の無線通信システムにおける第１の周波数処理手段は、第１の周波数領域の信号に対して、受信装置と共有する周波数ごとに異なる重み係数を乗算する構成であり、第２の周波数処理手段は、第２の周波数領域の信号に対して、送信装置と共有する重み係数の逆数を乗算する構成としてもよい。 The first frequency processing means in the wireless communication system of the first invention is configured to multiply the first frequency domain signal by a different weighting factor for each frequency shared with the receiving apparatus, and the second frequency The processing means may be configured to multiply the signal in the second frequency domain by the reciprocal of the weighting factor shared with the transmission device.
第２の発明の無線通信システムにおける第１の周波数処理手段は、第１の周波数領域の信号に対して、受信装置と共有する急峻な位相変化をもたらす通過位相特性によるフィルタリング処理を行う構成であり、第２の周波数処理手段は、第２の周波数領域の信号に対して、送信装置と共有する急峻な位相変化をもたらす通過位相特性と逆特性のフィルタリング処理を行う構成としてもよい。 The first frequency processing means in the radio communication system of the second invention is configured to perform a filtering process based on a passing phase characteristic that causes a steep phase change shared with the receiving apparatus on a signal in the first frequency domain. The second frequency processing means may be configured to perform a filtering process with a reverse characteristic to the passing phase characteristic that causes a steep phase change shared with the transmission apparatus, on the signal in the second frequency domain.
第２の発明は、無線信号を送受信する送信装置および受信装置により構成される無線通信システムの送信装置において、データ信号を変調して変調信号を出力する変調手段と、変調信号を第１の周波数領域の信号に変換する第１の時間−周波数変換手段と、第１の周波数領域の信号に対して、受信装置と共有する所定の周波数特性を用いて演算処理を行う第１の周波数処理手段と、第１の周波数処理手段の出力信号を第１の時間領域の信号に変換して出力する第１の周波数−時間変換手段とを備え、第１の時間領域の信号を無線信号として送信する構成である。 According to a second aspect of the present invention, there is provided a transmitter of a wireless communication system including a transmitter and a receiver that transmit and receive a radio signal, a modulation unit that modulates a data signal and outputs a modulated signal, First time-frequency conversion means for converting the signal into a region signal, and first frequency processing means for performing arithmetic processing on the signal in the first frequency region using a predetermined frequency characteristic shared with the receiving device; A first frequency-time conversion means for converting the output signal of the first frequency processing means into a first time-domain signal and outputting the first time-domain signal, and transmitting the first time-domain signal as a radio signal It is.
第２の発明の送信装置における第１の周波数処理手段は、第１の周波数領域の信号に対して、受信装置と共有する周波数ごとに異なる重み係数を乗算する構成としてもよい。 The first frequency processing means in the transmission apparatus of the second invention may be configured to multiply the first frequency domain signal by a different weighting factor for each frequency shared with the receiving apparatus.
第２の発明の送信装置における第１の周波数処理手段は、第１の周波数領域の信号に対して、受信装置と共有する急峻な位相変化をもたらす通過位相特性によるフィルタリング処理を行う構成とてしもよい。 The first frequency processing means in the transmission device of the second invention is configured to perform filtering processing on the signal in the first frequency domain based on a passing phase characteristic that causes a steep phase change shared with the reception device. Also good.
第３の発明は、無線信号を送受信する送信装置および受信装置により構成される無線通信システムの受信装置において、受信した無線信号を第２の周波数領域の信号に変換する第２の時間−周波数変換手段と、第２の周波数領域の信号に対して、送信装置と共有する所定の周波数特性の逆特性の周波数特性を用いて演算処理を行う第２の周波数処理手段と、第２の周波数処理手段の出力信号を第２の時間領域の信号に変換して出力する第２の周波数−時間変換手段とを備え、第２の時間領域の信号を復調して送信装置から送信されたデータ信号を復元する構成である。 A third invention provides a second time-frequency conversion for converting a received radio signal into a second frequency domain signal in a receiver of a radio communication system including a transmitter and a receiver that transmit and receive radio signals. Means, a second frequency processing means for performing arithmetic processing on a signal in the second frequency domain using a frequency characteristic opposite to the predetermined frequency characteristic shared with the transmission device, and a second frequency processing means And a second frequency-time conversion means for converting the output signal into a second time-domain signal and outputting the signal, and demodulating the second time-domain signal to restore the data signal transmitted from the transmitter It is the structure to do.
第３の発明の受信装置における第２の周波数処理手段は、第２の周波数領域の信号に対して、送信装置と共有する重み係数の逆数を乗算する構成としてもよい。 The second frequency processing means in the receiving apparatus of the third invention may be configured to multiply the signal in the second frequency domain by an inverse number of a weighting factor shared with the transmitting apparatus.
第３の発明の受信装置における第２の周波数処理手段は、第２の周波数領域の信号に対して、送信装置と共有する急峻な位相変化をもたらす通過位相特性と逆特性のフィルタリング処理を行う構成とてもよい。 The second frequency processing means in the receiving apparatus of the third invention is configured to perform filtering processing of a reverse phase characteristic and a reverse characteristic that causes a steep phase change shared with the transmitting apparatus on the signal in the second frequency domain. Very good.
本発明の無線通信システムは、送信装置で変調信号を周波数領域に変換した信号に対して、送受信装置間で共有する所定の周波数特性を用い、周波数領域で位相変化が急峻になる重み付け処理／フィルタリング処理を行い、再度時間領域の信号に戻して送信し、受信装置で受信信号を周波数領域に変換した信号に対して、送受信装置間で共有する所定の周波数特性の逆特性の周波数特性を用いて重み付け処理／フィルタリング処理を行い、再度時間領域の信号に戻して復調する構成である。 The radio communication system of the present invention uses a predetermined frequency characteristic shared between transmitting and receiving apparatuses for a signal obtained by converting a modulated signal into a frequency domain by a transmitting apparatus, and weighting processing / filtering in which a phase change is sharp in the frequency domain Perform processing, send back to the time domain signal again, and use the frequency characteristics that are the inverse of the predetermined frequency characteristics shared between the transmitting and receiving apparatuses for the signals that have been converted into the frequency domain by the receiving apparatus In this configuration, the weighting process / filtering process is performed, and the signal is demodulated again by returning to the signal in the time domain.
このように、送受信装置間で伝送される変調信号に対して、送受信装置間で共有する既知の周波数特性で処理することにより、既知の周波数特性を持たない一般の受信装置には周波数フェージングのある伝搬路のように見え、受信特性が劣化して信号を復調することができない。一方、既知の周波数特性をもつ正規の受信装置では、受信信号の周波数特性を補正して処理し、受信特性を元に戻すことによって高い確率で復調に成功することができる。すなわち、正規の受信装置のみが正常に受信でき、他の受信装置に対しては信号の復調に必要な所用Ｃ／Ｎを大幅に高め、あるいは復調を困難とし、スクランブラ単体で用いる場合よりも秘匿性を高めることができる。 In this way, a general reception apparatus having no known frequency characteristic has frequency fading by processing a modulated signal transmitted between the transmission / reception apparatuses with a known frequency characteristic shared between the transmission / reception apparatuses. It looks like a propagation path, and the reception characteristics deteriorate and the signal cannot be demodulated. On the other hand, a regular receiving apparatus having a known frequency characteristic can correct the frequency characteristic of the received signal, process the signal, and restore the original reception characteristic, thereby succeeding in demodulation with high probability. That is, only a regular receiving device can receive normally, and for other receiving devices, the required C / N required for signal demodulation is greatly increased, or demodulation is difficult, compared to the case where a scrambler is used alone. Confidentiality can be increased.
また、本発明の無線通信システムでは、変調信号の通過位相特性が変わるだけで、送信スペクトラムの状態に顕著な差がない。また、本発明の無線通信システムは、シングルキャリア伝送をベースとしたＳＣ−ＦＤＭＡや帯域分散伝送方式と組み合わせることが可能である。 Further, in the wireless communication system of the present invention, there is no significant difference in the state of the transmission spectrum only by changing the passing phase characteristic of the modulation signal. In addition, the wireless communication system of the present invention can be combined with SC-FDMA based on single carrier transmission or a band dispersion transmission system.
図１は、本発明の無線通信システムの送信装置および受信装置の実施例１を示す。
図１において、送信装置１０は、変調手段１１、フーリエ変換回路（ＤＦＴ）１２、乗算回路１３、重み係数設定回路１４、逆フーリエ変換回路（ＩＤＦＴ）１５により構成される。
FIG. 1 shows a first embodiment of a transmitter and a receiver of a wireless communication system according to the present invention.
In FIG. 1, the transmission device 10 includes a modulation unit 11, a Fourier transform circuit (DFT) 12, a multiplication circuit 13, a weighting factor setting circuit 14, and an inverse Fourier transform circuit (IDFT) 15.
変調手段１１は、送信データを変調した変調信号ｘを出力する。フーリエ変換回路１２は、変調信号ｘを周波数軸上の信号Ｘに変換して乗算回路１３に入力する。乗算回路１３は、フーリエ変換の各周波数ポイントＮ（Ｎは自然数) に対して、重み係数設定回路１４から入力する重み係数ｗi （ｉは１〜Ｎ）を乗算して重み付けを行う。逆フーリエ変換回路１５は、周波数軸上で重み付けされた信号Ｘ′を時間軸上の送信信号ｘ′に変換して送信する。 The modulation means 11 outputs a modulated signal x obtained by modulating transmission data. The Fourier transform circuit 12 converts the modulation signal x into a signal X on the frequency axis and inputs it to the multiplication circuit 13. The multiplication circuit 13 performs weighting by multiplying each frequency point N (N is a natural number) of the Fourier transform by a weighting factor w i (i is 1 to N) input from the weighting factor setting circuit 14. The inverse Fourier transform circuit 15 converts the signal X ′ weighted on the frequency axis into a transmission signal x ′ on the time axis and transmits it.
受信装置２０は、フーリエ変換回路（ＤＦＴ）２１、乗算回路２２、重み係数設定回路２３、逆フーリエ変換回路（ＩＤＦＴ）２４、復調手段２５により構成される。 The receiving device 20 includes a Fourier transform circuit (DFT) 21, a multiplier circuit 22, a weighting factor setting circuit 23, an inverse Fourier transform circuit (IDFT) 24, and a demodulation unit 25.
フーリエ変換回路２１は、受信信号ｘ′を周波数軸上の信号Ｘ′に変換して乗算回路２２に入力する。重み係数設定回路２３には、送信装置１０の重み係数設定回路１４が設定する重み係数ｗi の逆数である重み係数ｗi -1 が設定される。乗算回路２２は、フーリエ変換の各周波数ポイントＮに対して、重み係数設定回路２３から入力する重み係数ｗi -1を乗算して重み付けを行う。逆フーリエ変換回路２４は、周波数軸上で重み付けされた信号Ｘを時間軸上の変調信号ｘに変換して復調手段２５に入力し、復調手段２５で受信データを復調する。 The Fourier transform circuit 21 converts the received signal x ′ into a signal X ′ on the frequency axis and inputs it to the multiplication circuit 22. The weighting coefficient setting circuit 23, the weighting factor w i -1 is the inverse of the weighting coefficients w i of the weight coefficient setting circuit 14 sets the transmitter 10 is set. The multiplication circuit 22 performs weighting by multiplying each frequency point N of the Fourier transform by a weighting coefficient w i −1 input from the weighting coefficient setting circuit 23. The inverse Fourier transform circuit 24 converts the signal X weighted on the frequency axis into a modulation signal x on the time axis and inputs it to the demodulation means 25, and the demodulation means 25 demodulates the received data.
ここで、送信装置１０の送信信号ｘ′は、周波数軸上で重み係数ｗi が乗算されているため、位相および振幅が歪んだ信号であり、不正な傍受者が復調しても誤りが発生する可能性が高くなる。受信装置２０で正確に受信するためには、受信信号に対して送信装置１０で付与した重み係数ｗi の逆数の重み係数ｗi -1 を乗算する必要がある。なお、受信装置２０において、受信信号を送信装置１０で付与した重み係数ｗi で除算する構成でもよい。 Here, the transmission signal x ′ of the transmission device 10 is a signal with a distorted phase and amplitude because the weighting factor w i is multiplied on the frequency axis, and an error occurs even if an unauthorized eavesdropper demodulates. Is more likely to do. To correctly received by the receiving apparatus 20, it is necessary to multiply the weight coefficient w i -1 of the reciprocal of the weighting coefficient w i which is applied in the transmission device 10 to the receiving signal. Note that the receiving device 20 may be configured to divide the received signal by the weighting coefficient w i given by the transmitting device 10.
本実施例の動作原理について図２を参照して説明する。
上記の説明では、フーリエ変換した周波数軸上の信号に対して重み付け演算を行う構成を示したが、同様の処理をフィルタの通過位相の周波数特性（通過位相特性）が急峻な位相変化をもつように制御する構成でも実現できる。この場合、送信側と受信側で逆特性の通過位相特性を有するフィルタを用いるか、通過位相特性が可変のフィルタに対して、送信側と受信側で逆特性の通過位相特性を設定する構成をとる。
The operation principle of this embodiment will be described with reference to FIG.
In the above description, a configuration is shown in which weighting is performed on a signal on the frequency axis that has been subjected to Fourier transform, but the same processing is performed so that the frequency characteristic (pass phase characteristic) of the filter pass phase has a steep phase change. This can also be realized with a configuration in which the control is performed. In this case, a configuration is used in which a filter having a reverse pass phase characteristic is used on the transmission side and the reception side, or a reverse pass phase characteristic is set on the transmission side and the reception side for a filter having a variable pass phase characteristic. Take.
一般的な送信装置では、フィルタを用いて帯域外スプリアス等の不要信号成分を除去して送信する。フィルタの周波数特性は通過域において利得（損失）は一定であり、位相は図２(a) に示すように傾きはあるものの連続的である。本実施例は、変調信号を周波数軸上の信号に変換して重み付けを行い、再度時間領域の信号に戻すことで、無線装置における通過位相特性を図２(b) に示すように不連続または急峻な位相変化をもたせることができる。このような位相変化が急峻な通過位相特性をもつ信号を受信すると、非特許文献２に報告されるように周波数フェージングと同様にＣ／Ｎが劣化する。そのため、本実施例の受信装置２０では、送信装置１０で与えた重み係数（フィルタの通過位相特性）を打ち消すように信号処理を行って復調することで、Ｃ／Ｎの劣化を補償する。このとき、送信時に付与した通過位相特性によるＣ／Ｎ劣化分に比例して秘匿性が高まる。すなわち、重み係数ｗi -1 を有する受信装置と比較して、それを知らない第三者は受信信号の復調に失敗する確率が高くなるため、秘匿性が高まる。 In a general transmission device, unnecessary signal components such as out-of-band spurious are removed using a filter and transmitted. In the frequency characteristics of the filter, the gain (loss) is constant in the pass band, and the phase is continuous with a slope as shown in FIG. In the present embodiment, the modulation signal is converted into a signal on the frequency axis, weighted, and returned to the time domain signal again, so that the passing phase characteristic in the radio apparatus is discontinuous or as shown in FIG. A steep phase change can be provided. When a signal having such a passing phase characteristic with a steep phase change is received, C / N deteriorates as in frequency fading as reported in Non-Patent Document 2. Therefore, in the receiving apparatus 20 of the present embodiment, the signal processing is performed so as to cancel the weighting factor (filter pass phase characteristic) given by the transmitting apparatus 10 to demodulate the C / N deterioration. At this time, the secrecy is increased in proportion to the C / N degradation due to the passing phase characteristic given at the time of transmission. That is, as compared with a receiving apparatus having a weighting factor w i −1 , a third party who does not know it has a higher probability of failing to demodulate the received signal, so that confidentiality is improved.
また、変調信号の位相特性に変化を持たせる代わりに、利得について変化を与えてもよい。また、変調手段１１に入力する送信データは、従来の無線通信システムの技術であるスクランブル処理された信号であってもよい。 Further, instead of changing the phase characteristic of the modulation signal, a change may be given to the gain. The transmission data input to the modulation means 11 may be a scrambled signal that is a technique of a conventional wireless communication system.
ここで、付与する重み係数（フィルタの通過位相特性）が伝送信号に与える影響について、ＱＰＳＫ変調信号（ターボプロダクト符号使用）を用いて評価した結果を示す。評価システムでは、図３に示すようにデータ帯域をＭ等分（Ｍは２以上の自然数) し、データ帯域内に階段状の位相段差を有する通過位相特性を実現するため、変調信号をフーリエ変換した各周波数ポイントに、付与する位相段差θに応じてcosθ＋ｊsinθを乗算した。復調側では、逆特性の重み付けを与えずに復調してビット誤り率（ＢＥＲ）を測定した。重み係数が伝送信号に与える影響の評価結果を図４および図５に示す。 Here, the result of evaluating the influence of the weighting factor to be applied (pass phase characteristic of the filter) on the transmission signal using a QPSK modulation signal (using turbo product code) is shown. In the evaluation system, as shown in FIG. 3, the data band is equally divided into M (M is a natural number of 2 or more), and the modulation signal is subjected to Fourier transform in order to realize a pass phase characteristic having a stepped phase step in the data band. Each frequency point was multiplied by cos θ + jsin θ according to the phase step θ to be applied. On the demodulating side, the bit error rate (BER) was measured by demodulating without weighting the inverse characteristics. The evaluation results of the influence of the weighting factor on the transmission signal are shown in FIGS.
図４は、簡易な評価として位相段差を信号の中心周波数において１段付与したとき（２分割）に対するＢＥＲであり、付与する位相段差が大きいほどＢＥＲ特性が劣化することが確認でき、 120度ではエラーフリーとならなかった。なお、さらなる位相段差を付与すると、変復調装置間の同期確立が不能となった。一方、図５は付与する位相段差数（帯域の分割数）に対するＢＥＲであり、位相段差は60度を与えた時の結果である。この結果、分割数が増えるほど、ＢＥＲ特性が劣化することが確認でき、16分割ではエラーフリーとならなかった。 FIG. 4 is a BER for a simple evaluation when a phase step is given by one step at the center frequency of the signal (2 divisions). It can be confirmed that the larger the applied phase step, the more the BER characteristics deteriorate. It was not error free. When a further phase step is added, synchronization between the modems cannot be established. On the other hand, FIG. 5 shows the BER with respect to the number of phase steps to be applied (number of divisions of the band), and is the result when the phase steps are given 60 degrees. As a result, it was confirmed that as the number of divisions increased, the BER characteristics deteriorated, and error division was not achieved with 16 divisions.
図６は、送信スペクトルにおける重み係数の影響を示す。図６(a) は位相段差数が０（重み係数ｗが１）、図６(b) は位相段差数が２、図６(c) は位相段差数が多数の場合を示す。ここに示すように、送信スペクトルの形状は、位相段差数（帯域の分割数）に応じてほとんど変化せず、比帯域の増加は僅か0.15％程度で測定誤差程度の範囲と言え、顕著な影響はないと言える。なお、ここでの評価では通過位相特性に階段状の変化を与える例を示したが、これによらず任意の形状の通過位相特性を与え、受信側でその逆特性を用いる構成でもよい。 FIG. 6 shows the influence of the weighting factor on the transmission spectrum. 6A shows a case where the number of phase steps is 0 (weight coefficient w is 1), FIG. 6B shows a case where the number of phase steps is 2, and FIG. 6C shows a case where the number of phase steps is large. As shown here, the shape of the transmission spectrum hardly changes according to the number of phase steps (number of band divisions), and the increase of the ratio band is only about 0.15%, which can be said to be in the range of measurement error. I can't say that. In this example, a stepwise change is given to the pass phase characteristic. However, a configuration in which a pass phase characteristic having an arbitrary shape is given and the reverse characteristic is used on the reception side may be used.
ところで、送信信号に付与する通過位相特性は、周波数選択性フェージングと見ることも可能である。その場合、図７に示す従来の受信装置（非特許文献３）において、受信信号を周波数領域の信号に変換し、周波数領域等化回路において伝搬路推定回路で推定した伝搬路係数を用いて補償し、さらに時間領域の信号に変換して復調することができる。このような受信装置を用いることにより、送信側で付与した通過位相特性を推定して傍受が可能となる。そこで、このような受信装置において復調を不能にするための構成を実施例２として示す。 By the way, the pass phase characteristic added to the transmission signal can be regarded as frequency selective fading. In that case, in the conventional receiver shown in FIG. 7 (Non-patent Document 3), the received signal is converted into a frequency domain signal and compensated by using the channel coefficient estimated by the channel estimation circuit in the frequency domain equalization circuit. Further, it can be demodulated by converting to a signal in the time domain. By using such a receiving device, it is possible to intercept by estimating the passing phase characteristic given on the transmission side. Therefore, a configuration for disabling demodulation in such a receiving apparatus is shown as a second embodiment.
図８は、本発明の無線通信システムの送信装置および受信装置の実施例２を示す。
図８において、実施例２の送信装置は、図１に示す実施例１の送信装置の重み係数設定回路１４に代えて、重み係数ｗi を動的に可変設定する重み係数可変設定回路１６を用いる。実施例２の受信装置は、図１に示す実施例１の受信装置の重み係数設定回路２３に代えて、重み係数ｗi の逆数である重み係数ｗi -1 を動的に可変設定する重み係数可変設定回路２６を用いる。重み係数可変設定回路１６の重み係数ｗi および重み係数可変設定回路２６の重み係数ｗi -1 は、送信装置と受信装置でタイミングを合せて変更する。
FIG. 8 shows a second embodiment of the transmission device and the reception device of the wireless communication system of the present invention.
In FIG. 8, the transmission apparatus of the second embodiment includes a weight coefficient variable setting circuit 16 that dynamically variably sets the weight coefficient w i instead of the weight coefficient setting circuit 14 of the transmission apparatus of the first embodiment shown in FIG. Use. The receiving apparatus of the second embodiment, instead of the weighting coefficient setting circuit 23 of the receiving apparatus of the first embodiment shown in FIG. 1, for dynamically variably set the weight coefficient w i -1 is the inverse of the weighting factor w i weight A coefficient variable setting circuit 26 is used. The weighting factor w i of the weighting factor variable setting circuit 16 and the weighting factor w i −1 of the weighting factor variable setting circuit 26 are changed at the same timing in the transmitting device and the receiving device.
図７に示す周波数領域等化回路の解の収束には、非特許文献４にあるように、一定の時間を要するとされている。そのため、重み係数の変更間隔を収束時間以下とすることで、重み係数ｗi を適切に同定することができなくなる。なお、変更前の重み係数と変更後の重み係数は、相関が小さいことが好ましい。また、本実施例は、所定の間隔で重み係数を更新する場合に限らず、連続的に変化させてもよい。 It is said that a certain time is required for convergence of the solution of the frequency domain equalization circuit shown in FIG. For this reason, the weight coefficient w i cannot be appropriately identified by setting the change interval of the weight coefficient to the convergence time or less. In addition, it is preferable that the weight coefficient before change and the weight coefficient after change have a small correlation. Further, the present embodiment is not limited to updating the weighting coefficient at a predetermined interval, and may be continuously changed.
図９は、本発明の無線通信システムの送信装置の実施例３を示す。
図９において、実施例３の送信装置は、図１に示す実施例１の送信装置の変調手段１１とフーリエ変換回路（ＤＦＴ）１２との間に雑音付加回路１７を挿入し、変調信号に所定の雑音を付与してフーリエ変換回路１２に入力する。以下の処理は、実施例１と同様である。これにより送信信号のＣ／Ｎを下げ、傍受者がアンテナ利得の向上等により受信性能を上げても所定のＣ／Ｎを得られなくする。受信装置は実施例１の構成で対応可能である。また、本実施例は、図８に示す実施例２に構成にも適用することができる。
FIG. 9 shows a third embodiment of the transmission apparatus of the wireless communication system of the present invention.
In FIG. 9, the transmission apparatus of the third embodiment inserts a noise adding circuit 17 between the modulation means 11 and the Fourier transform circuit (DFT) 12 of the transmission apparatus of the first embodiment shown in FIG. Are input to the Fourier transform circuit 12. The following processing is the same as in the first embodiment. As a result, the C / N of the transmission signal is lowered, and even if the eavesdropper increases the reception performance by improving the antenna gain or the like, the predetermined C / N cannot be obtained. The receiving apparatus can cope with the configuration of the first embodiment. Further, the present embodiment can also be applied to the configuration of the second embodiment shown in FIG.
本発明は、シングルキャリア伝送における秘匿性向上に効果があるため、シングルキャリア伝送を基本とするＳＣ−ＦＤＭＡ（Single Carrier-Frequency Division Multiple Access)や、非特許文献２に記載される帯域分散伝送方式に適用することができる。 Since the present invention is effective in improving secrecy in single carrier transmission, SC-FDMA (Single Carrier-Frequency Division Multiple Access) based on single carrier transmission and a band distributed transmission method described in Non-Patent Document 2 Can be applied to.
図１０，図１１は、本発明の無線通信システムの送信装置および受信装置の実施例４を示す。図１０の実施例はＳＣ−ＦＤＭＡ方式に対応し、図１１の実施例は帯域分散伝送方式に対応する構成である。送信装置では、変調信号を周波数領域に変換して重み付けを行った信号を周波数マッピング回路１８あるいは帯域分割処理部１９に入力し、さらに時間領域の信号に変換して送信する。受信装置では、受信信号を周波数領域に変換して周波数デマッピング回路２７あるいは帯域合成処理部２８に入力し、さらに逆特性の重み付けを行った信号を時間領域の信号に変換して復調する。 10 and 11 show a fourth embodiment of the transmission device and the reception device of the wireless communication system of the present invention. The embodiment of FIG. 10 corresponds to the SC-FDMA scheme, and the embodiment of FIG. 11 has a configuration corresponding to the band dispersion transmission scheme. In the transmission device, the modulated signal is converted into the frequency domain, and the weighted signal is input to the frequency mapping circuit 18 or the band division processing unit 19 and further converted into a time domain signal and transmitted. In the receiving apparatus, the received signal is converted into the frequency domain and input to the frequency demapping circuit 27 or the band synthesizing processing unit 28, and the inverse weighted signal is converted into a time domain signal and demodulated.
１０ 送信装置
１１ 変調手段
１２ フーリエ変換回路（ＤＦＴ）
１３ 乗算回路
１４ 重み係数設定回路
１５ 逆フーリエ変換回路（ＩＤＦＴ）
１６ 重み係数可変設定回路
１７ 雑音付加回路
１８ 周波数マッピング回路
１９ 帯域分割処理部
２０ 受信装置
２１ フーリエ変換回路（ＤＦＴ）
２２ 乗算回路
２３ 重み係数設定回路
２４ 逆フーリエ変換回路（ＩＤＦＴ）
２５ 復調手段
２６ 重み係数可変設定回路
２７ 周波数デマッピング回路
２８ 帯域合成処理部
DESCRIPTION OF SYMBOLS 10 Transmitter 11 Modulation means 12 Fourier transform circuit (DFT)
13 Multiplier Circuit 14 Weighting Factor Setting Circuit 15 Inverse Fourier Transform Circuit (IDFT)
16 Weight coefficient variable setting circuit 17 Noise adding circuit 18 Frequency mapping circuit 19 Band division processing unit 20 Receiver 21 Fourier transform circuit (DFT)
22 Multiplier circuit 23 Weight coefficient setting circuit 24 Inverse Fourier transform circuit (IDFT)
25 Demodulating means 26 Weight coefficient variable setting circuit 27 Frequency demapping circuit 28 Band synthesis processor
Claims (9)
前記送信装置は、
データ信号を変調して変調信号を出力する変調手段と、
前記変調信号を第１の周波数領域の信号に変換する第１の時間−周波数変換手段と、
前記第１の周波数領域の信号に対して、前記受信装置と共有する所定の周波数特性を用いて演算処理を行う第１の周波数処理手段と、
前記第１の周波数処理手段の出力信号を第１の時間領域の信号に変換して出力する第１の周波数−時間変換手段と
を備え、前記第１の時間領域の信号を無線信号として送信する構成であり、
前記受信装置は、
受信した前記無線信号を第２の周波数領域の信号に変換する第２の時間−周波数変換手段と、
前記第２の周波数領域の信号に対して、前記送信装置と共有する所定の周波数特性の逆特性の周波数特性を用いて演算処理を行う第２の周波数処理手段と、
前記第２の周波数処理手段の出力信号を第２の時間領域の信号に変換して出力する第２の周波数−時間変換手段と
を備え、第２の時間領域の信号を復調して前記送信装置から送信されたデータ信号を復元する構成である
ことを特徴とする無線通信システム。 A wireless communication system including a transmission device and a reception device for transmitting and receiving a wireless signal,
The transmitter is
Modulation means for modulating a data signal and outputting a modulated signal;
First time-frequency conversion means for converting the modulated signal into a signal in a first frequency domain;
First frequency processing means for performing arithmetic processing on a signal in the first frequency domain using a predetermined frequency characteristic shared with the receiving device;
First frequency-time conversion means for converting an output signal of the first frequency processing means into a first time-domain signal and outputting the signal, and transmitting the first time-domain signal as a radio signal Configuration,
The receiving device is:
Second time-frequency conversion means for converting the received radio signal into a signal in a second frequency domain;
Second frequency processing means for performing arithmetic processing on a signal in the second frequency domain using a frequency characteristic that is a reverse characteristic of a predetermined frequency characteristic shared with the transmission device;
Second frequency-time conversion means for converting the output signal of the second frequency processing means into a second time-domain signal and outputting the signal, and demodulating the second time-domain signal to transmit the transmitter A wireless communication system, characterized in that the data signal transmitted from is restored.
前記第１の周波数処理手段は、前記第１の周波数領域の信号に対して、前記受信装置と共有する周波数ごとに異なる重み係数を乗算する構成であり、
前記第２の周波数処理手段は、前記第２の周波数領域の信号に対して、前記送信装置と共有する前記重み係数の逆数を乗算する構成である
ことを特徴とする無線通信システム。 The wireless communication system according to claim 1, wherein
The first frequency processing means is configured to multiply the first frequency domain signal by a different weighting factor for each frequency shared with the receiving device,
The wireless communication system, wherein the second frequency processing means is configured to multiply the signal in the second frequency domain by an inverse of the weighting factor shared with the transmission device.
前記第１の周波数処理手段は、前記第１の周波数領域の信号に対して、前記受信装置と共有する急峻な位相変化をもたらす通過位相特性によるフィルタリング処理を行う構成であり、
前記第２の周波数処理手段は、前記第２の周波数領域の信号に対して、前記送信装置と共有する前記急峻な位相変化をもたらす通過位相特性と逆特性のフィルタリング処理を行う構成である
ことを特徴とする無線通信システム。 The wireless communication system according to claim 1, wherein
The first frequency processing means is configured to perform a filtering process based on a passing phase characteristic that causes a steep phase change shared with the receiving apparatus on the signal in the first frequency domain,
The second frequency processing means is configured to perform a filtering process having a reverse characteristic to a pass phase characteristic that causes the steep phase change shared with the transmission apparatus, with respect to the signal in the second frequency domain. A wireless communication system.
データ信号を変調して変調信号を出力する変調手段と、
前記変調信号を第１の周波数領域の信号に変換する第１の時間−周波数変換手段と、
前記第１の周波数領域の信号に対して、前記受信装置と共有する所定の周波数特性を用いて演算処理を行う第１の周波数処理手段と、
前記第１の周波数処理手段の出力信号を第１の時間領域の信号に変換して出力する第１の周波数−時間変換手段と
を備え、前記第１の時間領域の信号を無線信号として送信する構成である
ことを特徴とする送信装置。 In a transmission device of a wireless communication system configured by a transmission device and a reception device that transmit and receive wireless signals,
Modulation means for modulating a data signal and outputting a modulated signal;
First time-frequency conversion means for converting the modulated signal into a signal in a first frequency domain;
First frequency processing means for performing arithmetic processing on a signal in the first frequency domain using a predetermined frequency characteristic shared with the receiving device;
First frequency-time conversion means for converting an output signal of the first frequency processing means into a first time-domain signal and outputting the signal, and transmitting the first time-domain signal as a radio signal A transmitter characterized by having a configuration.
前記第１の周波数処理手段は、前記第１の周波数領域の信号に対して、前記受信装置と共有する周波数ごとに異なる重み係数を乗算する構成である
ことを特徴とする送信装置。 The transmission device according to claim 4, wherein
The transmission apparatus according to claim 1, wherein the first frequency processing means is configured to multiply the signal in the first frequency domain by a different weighting factor for each frequency shared with the reception apparatus.
前記第１の周波数処理手段は、前記第１の周波数領域の信号に対して、前記受信装置と共有する急峻な位相変化をもたらす通過位相特性によるフィルタリング処理を行う構成である
ことを特徴とする送信装置。 The transmission apparatus according to claim 1,
The first frequency processing means is configured to perform a filtering process based on a pass phase characteristic that causes a steep phase change shared with the receiving apparatus on the signal in the first frequency domain. apparatus.
受信した前記無線信号を第２の周波数領域の信号に変換する第２の時間−周波数変換手段と、
前記第２の周波数領域の信号に対して、前記送信装置と共有する所定の周波数特性の逆特性の周波数特性を用いて演算処理を行う第２の周波数処理手段と、
前記第２の周波数処理手段の出力信号を第２の時間領域の信号に変換して出力する第２の周波数−時間変換手段と
を備え、第２の時間領域の信号を復調して前記送信装置から送信されたデータ信号を復元する構成である
ことを特徴とする受信装置。 In a receiving device of a wireless communication system including a transmitting device and a receiving device for transmitting and receiving a radio signal,
Second time-frequency conversion means for converting the received radio signal into a signal in a second frequency domain;
Second frequency processing means for performing arithmetic processing on a signal in the second frequency domain using a frequency characteristic that is a reverse characteristic of a predetermined frequency characteristic shared with the transmission device;
Second frequency-time conversion means for converting the output signal of the second frequency processing means into a second time-domain signal and outputting the signal, and demodulating the second time-domain signal to transmit the transmitter A receiving apparatus, wherein the data signal transmitted from the terminal is restored.
前記第２の周波数処理手段は、前記第２の周波数領域の信号に対して、前記送信装置と共有する重み係数の逆数を乗算する構成である
ことを特徴とする受信装置。 The receiving device according to claim 7,
The receiving device, wherein the second frequency processing means is configured to multiply the signal in the second frequency domain by an inverse number of a weighting factor shared with the transmitting device.
前記第２の周波数処理手段は、前記第２の周波数領域の信号に対して、前記送信装置と共有する急峻な位相変化をもたらす通過位相特性と逆特性のフィルタリング処理を行う構成である
ことを特徴とする受信装置。 The receiving device according to claim 7,
The second frequency processing means is configured to perform a filtering process having a reverse characteristic to a pass phase characteristic that causes a steep phase change shared with the transmission apparatus, on the signal in the second frequency domain. A receiving device.
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| JP2001507875A (en) * | 1995-09-06 | 2001-06-12 | ソラナ・テクノロジー・デベロップメント・コーポレイション | Method and apparatus for transferring auxiliary data in an audio signal |
| JP2010501142A (en) * | 2006-08-16 | 2010-01-14 | ハリス コーポレイション | Data communication system and method using orthogonal frequency division multiplexing (OFDM) with symbol-based randomization |
| JP2010268040A (en) * | 2009-05-12 | 2010-11-25 | Mitsubishi Electric Corp | Transmitter, receiver and communication apparatus |
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| JP2001507875A (en) * | 1995-09-06 | 2001-06-12 | ソラナ・テクノロジー・デベロップメント・コーポレイション | Method and apparatus for transferring auxiliary data in an audio signal |
| JP2010501142A (en) * | 2006-08-16 | 2010-01-14 | ハリス コーポレイション | Data communication system and method using orthogonal frequency division multiplexing (OFDM) with symbol-based randomization |
| JP2010268040A (en) * | 2009-05-12 | 2010-11-25 | Mitsubishi Electric Corp | Transmitter, receiver and communication apparatus |
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