JPH0775331B2 - Adaptive interference canceller - Google Patents
Adaptive interference cancellerInfo
- Publication number
- JPH0775331B2 JPH0775331B2 JP60184734A JP18473485A JPH0775331B2 JP H0775331 B2 JPH0775331 B2 JP H0775331B2 JP 60184734 A JP60184734 A JP 60184734A JP 18473485 A JP18473485 A JP 18473485A JP H0775331 B2 JPH0775331 B2 JP H0775331B2
- Authority
- JP
- Japan
- Prior art keywords
- signal
- output
- recursive filter
- subtractor
- interference
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired - Lifetime
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- Cable Transmission Systems, Equalization Of Radio And Reduction Of Echo (AREA)
Description
【発明の詳細な説明】 （産業上の利用分野） 本発明は、通信やレーダー、ソーナーなどにおいて所要
信号以外の信号、即ち、干渉信号を適応的に除去する適
応干渉除去装置、殊に適応フィルタを用いた干渉除去装
置に関する。Description: TECHNICAL FIELD The present invention relates to an adaptive interference canceller, in particular an adaptive filter, which adaptively cancels signals other than required signals, that is, interference signals in communication, radar, sonar, etc. The present invention relates to an interference canceling device using.
（従来技術とその問題点） ビー・ウィドロウ（B.Widrow）及びエス・デー・ストリ
ームズ（S.D.Stearns）によりプレンティスホール社（P
rentice−Hall Inc）より1985年に刊行された文献「ア
ダプティブシグナルプロセッシィング（Adaptive Signa
l Processing）」第12章にまとめられている従来技術は
全て干渉の参照信号が得られ、これを適応フィルタの入
力信号とするものである（前記文献第304頁図12.1参
照）。干渉の参照信号に所望信号や雑音が重畳している
場合も、干渉電力が所望信号に比べ充分大きい場合は干
渉信号と所望信号の和そのものを干渉の参照信号と見做
せるためパワーインバージョン型の干渉除去が可能とな
る（前記文献p.312〜p.313）。然しながら、干渉信号と
所望信号が重畳しており、しかも、干渉信号が所望信号
に対して充分大きい場合も、同程度の大きさの場合或い
は小さい場合の全ての場合において有効に干渉を除去し
得る手段はなかった。(Prior art and its problems) Prentice Hall (P.) by B. Widrow and SD Streams
rentice-Hall Inc) published in 1985 "Adaptive Signal Processing (Adaptive Signal Processing)".
All of the conventional techniques summarized in Chapter 12 obtain an interference reference signal and use this as the input signal of the adaptive filter (see Fig. 12.1 on page 304 of the document). Even if a desired signal or noise is superposed on the interference reference signal, if the interference power is sufficiently larger than the desired signal, the sum of the interference signal and the desired signal itself can be regarded as the interference reference signal. It becomes possible to remove the interference of the above (References p.312 to p.313). However, even when the interference signal and the desired signal are superposed and the interference signal is sufficiently larger than the desired signal, the interference can be effectively removed in all cases of the same or small size. There was no means.
（発明の目的） 本発明は、所望信号がデータ或いはディジタル信号であ
る場合に、どのような所望信号対干渉信号比（D/U比）
に対しても有効に動作する適応形干渉除去装置を提供す
ることにある。(Object of the Invention) The present invention provides a desired signal-to-interference signal ratio (D / U ratio) when the desired signal is a data or digital signal.
It is another object of the present invention to provide an adaptive interference canceller that operates effectively even in the above.
（発明の構成） 本発明によれば、所望信号がディジタル信号であり、こ
れに所望信号の帯域巾よりも狭い帯域巾を持つ干渉信号
が加えられるシステムにおいて、適応的に重みづけが制
御される巡回形フィルタと、受信した信号から前記巡回
形フィルタの出力信号を減算する第一の減算器と、該第
一の減算器の出力を予め定めたスレショルドレベルに従
って所望信号を判定し、予め定めたレベルを持つ判定結
果を出力する判定器と、判定器の入力から判定器の出力
である判定結果を減算する第二の減算器と、該第二の減
算器の出力である誤差信号を一定時間遅延させ前記巡回
形フィルタの入力に信号を与える遅延素子と、前記誤差
信号と前記巡回形フィルタの内部状態信号との相関をと
り、相関値の大きさに従って前記巡回形フィルタの重み
を逐次的に制御する係数制御装置とを有することを特徴
とする適応干渉除去装置が得られる。(Structure of the Invention) According to the present invention, weighting is adaptively controlled in a system in which a desired signal is a digital signal and an interference signal having a bandwidth narrower than the bandwidth of the desired signal is added thereto. A recursive filter, a first subtractor that subtracts the output signal of the recursive filter from the received signal, and the output of the first subtractor determines a desired signal according to a predetermined threshold level, and the predetermined signal is determined in advance. A judgment device that outputs a judgment result having a level, a second subtracter that subtracts the judgment result that is the output of the judgment device from the input of the judgment device, and an error signal that is the output of the second subtractor A delay element that delays and gives a signal to the input of the recursive filter, the error signal and the internal state signal of the recursive filter are correlated, and the weight of the recursive filter is determined according to the magnitude of the correlation value. An adaptive interference canceller is obtained which has a coefficient controller that controls sequentially.
（構成の詳細な説明） 本発明が対象とするのは、PSKやQAMなどのディジタル信
号変調波ｓ（ｔ）に、ｓ（ｔ）帯域幅より狭い帯域巾を
持つ干渉信号ｉ（ｔ）が重畳している場合である。今、
伝送路の雑音もｉ（ｔ）に含めて考えると、受信信号ｒ
（ｔ）は ｒ（ｔ）＝ｓ（ｔ）＋ｉ（ｔ） と表わされる。受信信号は通常の復調過程により復調さ
れベースバンド信号Ｂ（ｔ）の時刻ｔ＝ｎにおけるサン
プル値が次のように得られる。(Detailed Description of Configuration) The present invention is directed to an interference signal i (t) having a bandwidth narrower than s (t) bandwidth in a digital signal modulated wave s (t) such as PSK or QAM. This is the case when they overlap. now,
Considering the noise of the transmission path as well in i (t), the received signal r
(T) is expressed as r (t) = s (t) + i (t). The received signal is demodulated by the normal demodulation process, and the sample value of the baseband signal B (t) at time t = n is obtained as follows.
Ｂ（ｎ）＝Ｓ（ｎ）＋Ｉ（ｎ） ここでＳ（ｔ）,I（ｔ）は各々ｓ（ｔ）,i（ｔ）が復調
のプロセスを通った信号である。従来のパワーインバー
ジョン型の干渉除去は、Ｓ（ｎ）≪Ｉ（ｎ）と仮定しＢ
（ｎ）Ｉ（ｎ）を利用して、干渉が極めて大きい場合
に出力でのD/U比入力D/U比の逆数にするものであった。
本発明では干渉Ｉ（ｎ）を積極的に予測する機能を持た
せることによってＢ（ｎ）Ｉ（ｎ）の仮定を用いるこ
となしに干渉除去を行なう。予測には移動平均形と自己
回帰形及びその組合せが考えられるが、本発明は次のよ
うな自己回帰形予測を用いる。Ｉ（ｎ）の予測値を
（ｎ）とすると ここでＥ（ｎ−１）は時刻ｎ−１での予測誤差、即ち Ｅ（ｎ−１）＝Ｉ（ｎ−１）−（ｎ−１） であるが、実際にはＩ（ｎ−１）は直接観測されないの
で誤差として Ｅ（ｎ−１） ＝Ｂ（ｎ−１）−（ｎ−１）−（ｎ−１） を用いる。ここで（ｎ−１）はＢ（ｎ−１）−（ｎ
−１）を判定して得られる判定結果で、例えばディジタ
ル信号が４相PSKであれば、４相のうちのどの位相から
判定した結果である。これ等の過程は第３図のブロック
図で実現される。第３図において破線で囲った部分は再
帰形フィルタを構成している。B (n) = S (n) + I (n) Here, S (t) and I (t) are signals whose s (t) and i (t) have passed through the demodulation process. In the conventional power inversion type interference cancellation, it is assumed that S (n) << I (n) and B
(N) I (n) was used to obtain the reciprocal of the D / U ratio input D / U ratio at the output when the interference was extremely large.
In the present invention, interference cancellation is performed without using the assumption of B (n) I (n) by providing a function of actively predicting interference I (n). Although a moving average form, an autoregressive form and a combination thereof can be considered for the prediction, the present invention uses the following autoregressive form prediction. If the predicted value of I (n) is (n), Here, E (n-1) is a prediction error at time n-1, that is, E (n-1) = I (n-1)-(n-1), but actually I (n-1) ) Is not directly observed, so E (n-1) = B (n-1)-(n-1)-(n-1) is used as an error. Where (n-1) is B (n-1)-(n
If the digital signal is a 4-phase PSK, for example, it is the result of the determination from which of the four phases is obtained. These processes are realized by the block diagram of FIG. The part surrounded by the broken line in FIG. 3 constitutes a recursive filter.
時刻ｎにおける誤差Ｅ（ｎ）は となり、Ｅ（ｎ）の２乗平均即ち２乗平均誤差は である。この評価関数が小さくなるようにWiを調整する
手段として極めて一般的に用いられるものは評価関数の
係数Wiに関する を求め、これが減少するようにWiを調整する再急勾配法
であるが、評価関数の中に含まれるＥ（ｎ−１）は過去
のWiの関数であるため厳密な偏微係数は複雑な形とな
る。然しながら、係数が最適な値に近づいた時点で∂ Ｅ（ｎ−１）／∂Wi＝０ となることを考慮してこれを無視すると次式によるWiの
調整が得られる。The error E (n) at time n is And the mean square error of E (n), that is, the mean square error is Is. The most commonly used means for adjusting Wi so that this evaluation function becomes small is the coefficient Wi of the evaluation function. Is a steepest gradient method that adjusts Wi so that it decreases, but since E (n-1) included in the evaluation function is a function of past Wi, the exact partial coefficient is complicated. Be in shape. However, considering that the coefficient becomes ∂E (n−1) / ∂Wi = 0 when the coefficient approaches the optimum value, and ignoring this, the adjustment of Wi by the following equation can be obtained.
Win＝Win-1＋α・（ｎ−ｉ）・Ｅ（ｎ） これは、時刻ｎにおいてｉ番目の係数Wiを係数Wi上にあ
る信号、即ち再帰形フィルタの内部状態信号（ｎ−
ｉ）と誤差信号Ｅ（ｎ）との積に適当な適応係数αを乗
じて時刻ｎ−ｉにおける係数値に加えることによって定
めることに対応する。この収束の過程を概念的に説明す
ると、次のようになる。まず、干渉信号が所望信号に比
べて大きい状態では、判定結果（ｎ）は干渉信号を判
定したものとなり、所望信号とは無関係な雑音となり、
パワーインバージョンと同様の振舞いを行ない誤差信号
は減少する。誤差信号がある所まで減少した状態（例え
ばD/U＝0dB）では、誤差信号は、干渉信号の消去残と所
要信号の和からこれを判定した判定結果を減算した和か
ら成っている。判定結果は時に正しく、時に誤っている
と考えられ、判定結果が正しい時には正確な干渉消去残
が、判定結果が誤っている時には大きな雑音を含んだ干
渉消去残が誤差信号として得られることになる。この状
態で収束速度は減少するが、確率的な偏りによって判定
結果が正しい状態が誤った状態より多く現れると急激に
収束が進行し、最適値に到達する。この過程において干
渉信号の予測値を減算した信号のD/U比は連続的に変化
しており、このアルゴリズムがどのような入力D/U比に
対しても効果的であることは容易にわかる。Wi n = Wi n-1 + α · (n−i) · E (n) This is the signal on the coefficient Wi at the i-th coefficient Wi at time n, that is, the internal state signal (n− of the recursive filter).
It corresponds to the determination by multiplying the product of i) and the error signal E (n) by an appropriate adaptation coefficient α and adding it to the coefficient value at time n−i. The concept of this convergence process is as follows. First, when the interference signal is larger than the desired signal, the determination result (n) is a determination of the interference signal, which is noise unrelated to the desired signal.
It behaves like power inversion and the error signal is reduced. In the state where the error signal is reduced to a certain position (for example, D / U = 0 dB), the error signal is composed of the sum of the unremoved interference signal and the required signal, and the sum obtained by subtracting the determination result. It is considered that the judgment result is sometimes correct and sometimes wrong, and when the judgment result is correct, an accurate interference cancellation residual is obtained as an error signal, and when the judgment result is incorrect, the interference cancellation residual including large noise is obtained as an error signal. . In this state, the convergence speed decreases, but if the number of correct judgment results exceeds the number of erroneous judgments due to stochastic bias, the convergence rapidly advances and reaches the optimum value. In this process, the D / U ratio of the signal after subtracting the predicted value of the interference signal is continuously changing, and it is easy to see that this algorithm is effective for any input D / U ratio. .
第２の発明においては、収束の過程をより早くするため
に次のような手段を続けている。即ち収束の初期段階で
は、判定結果を減算することは収束に良い影響は与えな
いため、判定結果として所定のレベルより低いレベルを
出力することにより不確かな判定結果を減算することに
よる弊害を防止し、収束が進んだ時点で所定のレベルへ
戻すのである。この方法は、特に、受信機の入力で自動
利得調整（AGC）がある場合に、干渉のレベルと判定結
果のレベルが大幅に違わなくなってしまう場合に有効で
ある。この場合、判定レベルを所定のレベルに戻した時
点で、干渉信号を引き算した信号に対するAGCが必要と
なる。In the second invention, the following means are continued in order to accelerate the convergence process. That is, in the initial stage of the convergence, subtraction of the judgment result does not have a good influence on the convergence. Therefore, by outputting a level lower than a predetermined level as the judgment result, the adverse effect of subtracting the uncertain judgment result is prevented. , When the convergence progresses, it returns to a predetermined level. This method is particularly effective when the level of the interference and the level of the determination result are not significantly different when there is automatic gain adjustment (AGC) at the input of the receiver. In this case, the AGC for the signal obtained by subtracting the interference signal is required when the determination level is returned to the predetermined level.
（実施例） 以下本発明の実施例について図面を参照して詳細に説明
する。(Example) Hereinafter, an example of the present invention will be described in detail with reference to the drawings.
第１図は第１の発明の実施例を示すブロック図で端子１
より入来した干渉信号の重畳した所望信号Ｂ（ｎ）は第
１の減算器２において再帰形フィルタ６の出力である干
渉信号の予測値（（ｎ））が減算される。減算器出力
（Ｂ（ｎ）−（ｎ））は判定器３の出力である判定結
果（ｎ）が第２の減算器４で差し引かれてＥ（ｎ）が
得られ遅延素子５により単位時間遅延されＥ（ｎ−１）
として出力される。遅延素子５の出力は前記再帰形フィ
ルタ６に入力する。再帰形フィルタの重み係数（複数）
は第２の減算器４の出力である誤差信号と再帰形フィル
タの内部状態信号との相関値を計算する重み制御回路７
によって制御される。端子８には干渉信号が除去された
ことによって正しく判定された所望信号の判定結果が出
力される。第２の発明の実施例は第２図に示すように第
２の減算器４の一方の入力にセレクタ10を設け、前記第
２の減算器４に、判定器３の出力を直接に入力するか、
減算器９の出力を入力するかを端子13より入来するトリ
ガー信号によって駆動されるタイマー14の信号により選
択すると共に第１の減算器２の出力にAGC11を設け、前
記タイマー14によって動作を開始させる。FIG. 1 is a block diagram showing an embodiment of the first invention.
The predicted value ((n)) of the interference signal, which is the output of the recursive filter 6, is subtracted from the desired signal B (n) on which the incoming interference signal is superimposed in the first subtractor 2. The subtractor output (B (n)-(n)) is the output of the determiner 3 and the determination result (n) is subtracted by the second subtractor 4 to obtain E (n). Delayed E (n-1)
Is output as. The output of the delay element 5 is input to the recursive filter 6. Weighting factor for recursive filter (multiple)
Is a weight control circuit 7 for calculating the correlation value between the error signal output from the second subtractor 4 and the internal state signal of the recursive filter.
Controlled by. The terminal 8 outputs the determination result of the desired signal which is correctly determined by the removal of the interference signal. In the embodiment of the second invention, as shown in FIG. 2, a selector 10 is provided at one input of the second subtractor 4, and the output of the decision device 3 is directly inputted to the second subtractor 4. Or
Whether to input the output of the subtractor 9 is selected by the signal of the timer 14 driven by the trigger signal coming from the terminal 13, and the AGC 11 is provided at the output of the first subtractor 2 to start the operation by the timer 14. Let
（発明の効果） 本発明によれば、どのようなD/U比に対しても有効な干
渉除去が可能となる。(Effects of the Invention) According to the present invention, it is possible to effectively eliminate interference for any D / U ratio.
第１図は第１の発明を示すブロック図、第２図は第２の
発明の実施例を示すブロック図、第３図は第１の発明の
概念を説明するための機能ブロック図である。 図において、2,4は減算器、３は判定器、５は遅延素
子、６は再帰形フィルタ、７は重み制御回路、９は減衰
器、10はセレクタ、11はAGCである。FIG. 1 is a block diagram showing the first invention, FIG. 2 is a block diagram showing an embodiment of the second invention, and FIG. 3 is a functional block diagram for explaining the concept of the first invention. In the figure, 2 and 4 are subtractors, 3 is a decision device, 5 is a delay element, 6 is a recursive filter, 7 is a weight control circuit, 9 is an attenuator, 10 is a selector, and 11 is an AGC.
Claims (2)
所望信号の帯域巾よりも狭い帯域巾を持つ干渉信号が加
えられるシステムにおいて、適応的に重みづけが制御さ
れる巡回形フィルタと、受信した信号から前記巡回形フ
ィルタの出力信号を減算する第一の減算器と、該第一の
減算器の出力を予め定めたスレショルドレベルに従って
所望信号を判定し、予め定めたレベルを持つ判定結果を
出力する判定器と、判定器の入力から判定器の出力であ
る判定結果を減算する第二の減算器と、該第二の減算器
の出力である誤差信号を一定時間遅延させ前記巡回形フ
ィルタの入力に信号を与える遅延素子と、前記誤差信号
と前記巡回形フィルタの内部状態信号との相関をとり、
相関値の大きさに従って前記巡回形フィルタの重みを逐
次的に制御する係数制御装置とを有することを特徴とす
る適応干渉除去装置。1. A recursive filter in which weighting is adaptively controlled in a system in which a desired signal is a digital signal and an interference signal having a bandwidth narrower than the bandwidth of the desired signal is added to the system, and a reception filter. A first subtractor that subtracts the output signal of the recursive filter from the generated signal, and the output of the first subtractor determines a desired signal according to a predetermined threshold level, and a determination result having a predetermined level is obtained. A judging device for outputting, a second subtracter for subtracting the judgment result which is the output of the judging device from the input of the judging device, and the cyclic filter for delaying the error signal which is the output of the second subtracting device for a predetermined time. A delay element for giving a signal to the input of, and the correlation between the error signal and the internal state signal of the recursive filter,
And a coefficient control device for sequentially controlling the weight of the recursive filter according to the magnitude of the correlation value.
所望信号の帯域巾よりも狭い帯域巾を持つ干渉信号が加
えられるシステムにおいて、適応的に重みづけが制御さ
れる再帰形フィルタと、受信した信号から前記再帰形フ
ィルタの出力信号を減算する第一の減算器と、該第一の
減算器の出力電力を一定に保つAGCと、該AGC出力を予め
定めたスレショルドレベルに従って所望信号を判定し、
予め定めたレベルを持つ判定結果を出力する判定器と、
判定器の出力を減衰する減衰器と、前記判定器と前記減
衰器の出力のいづれかを選択するセレクタと、前記判定
器の入力から前記セレクタの出力を減算する第二の減算
器と、該第二の減算器の出力である誤差信号を一定時間
遅延させ前記再帰形フィルタの入力に信号を与える遅延
素子と、前記誤差信号と前記再帰形フィルタの内部状態
信号との相関をとり、相関値の大きさに従って前記再帰
形フィルタの重みを逐次的に制御する係数制御装置と、
外部からのトリガー信号によってトリガーされ前記セレ
クタと前記AGCの動作を制御するタイマーとを有するこ
とを特徴とする適応干渉除去装置。2. A recursive filter in which weighting is adaptively controlled in a system in which a desired signal is a digital signal and an interference signal having a bandwidth narrower than the bandwidth of the desired signal is added to the system, and receiving A subtractor that subtracts the output signal of the recursive filter from the generated signal, an AGC that keeps the output power of the first subtractor constant, and a desired signal is determined according to a predetermined threshold level of the AGC output. Then
A determiner that outputs a determination result having a predetermined level,
An attenuator that attenuates the output of the determiner, a selector that selects one of the determiner and the output of the attenuator, a second subtractor that subtracts the output of the selector from the input of the determiner, and A delay element that delays the error signal that is the output of the second subtractor for a fixed time to give a signal to the input of the recursive filter, and takes the correlation between the error signal and the internal state signal of the recursive filter, A coefficient control device for sequentially controlling the weight of the recursive filter according to the size,
An adaptive interference canceller, comprising: a timer triggered by an external trigger signal to control the operation of the selector and the AGC.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP60184734A JPH0775331B2 (en) | 1985-08-21 | 1985-08-21 | Adaptive interference canceller |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP60184734A JPH0775331B2 (en) | 1985-08-21 | 1985-08-21 | Adaptive interference canceller |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPS6243923A JPS6243923A (en) | 1987-02-25 |
| JPH0775331B2 true JPH0775331B2 (en) | 1995-08-09 |
Family
ID=16158428
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP60184734A Expired - Lifetime JPH0775331B2 (en) | 1985-08-21 | 1985-08-21 | Adaptive interference canceller |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPH0775331B2 (en) |
Families Citing this family (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPH0748631B2 (en) * | 1987-10-14 | 1995-05-24 | 日本電気株式会社 | Decision feedback equalizer with built-in cyclic filter |
| JP4872332B2 (en) | 2005-12-05 | 2012-02-08 | 株式会社デンソー | Anti-glare device for moving objects |
Family Cites Families (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS59211314A (en) * | 1983-05-17 | 1984-11-30 | Toshiba Corp | Abnormal operation detecting system in automatic equalizer |
| JPS60112310A (en) * | 1983-11-22 | 1985-06-18 | Nec Corp | Equalizing circuit |
-
1985
- 1985-08-21 JP JP60184734A patent/JPH0775331B2/en not_active Expired - Lifetime
Also Published As
| Publication number | Publication date |
|---|---|
| JPS6243923A (en) | 1987-02-25 |
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