JP2007500970A - Rake receiver with multipath interference capability - Google Patents

Abstract

を推定する工程と、フィルタリングされた前記サンプルΨ（τ）のチャネル複合係数
【数４３】

を推定する工程とを含む。フィルタリング済みサンプルΨ（τ）式
【数４４】

の連立方程式の解によって、各パスｌのフィルタリングされたサンプルΨ（τ）からデータｘ（τ_ｌ）が抽出される。ここでｋは特定のパス、Ｎ_ｐは可視パスの数、
【数４５】

はフィルタリング・プロセスの二重畳込み行列、
【数４６】

はその疑似逆関数、Λｓｓ（τ_ｌ）は拡散行列とスクランブル行列との積、
【数４７】

はその逆関数、
【数４８】

は雑音である。
A method for extracting data from a received signal including multipath interference in a rake receiver. This method samples and filters the received signal and the time delay between the paths of the filtered samples Ψ (τ)

And the channel composite coefficient of the filtered sample Ψ (τ)

Estimating. Filtered sample Ψ (τ) formula

The data x (τ _l ) is extracted from the filtered samples Ψ (τ) of each path l by solving the simultaneous equations. Where k is a specific path, N _p is the number of visible paths,
[Equation 45]

Is the two convolution matrix of the filtering process,
[Equation 46]

Is the pseudo inverse function, Λss (τ _l ) is the product of the diffusion matrix and the scramble matrix,
[Equation 47]

Is its inverse function,
[Formula 48]

Is noise.

Description

  The present invention relates to multipath cancellation in wireless communications, and more particularly to coping with multipath interference.

Multipath interference is an undesirable phenomenon unique to the wireless communication field. In some cases, multipath interference can cause significant communication channel failure. This is typical of dense urban areas and closed areas such as shopping malls. One form of multipath interference cancellation (MPIC) is Fock et al., “Channel Tracking for Rake Receivers in Closely Spaced Multipath Environments” (IEEE Journal on Selected Areas, 20th, 19th, 19th, 20th, 19th, 19th, 19th, 19th, 19th, 19th, 19th, 19th, 19th, 19th, 19th, 19th, 19th, 19th, 19th, 19th, 19th, 19th, 19th, 20th It is shown on page 2431. It uses a fading factor and relative delay to calculate a compensation term that can eliminate the effect of other paths on timing errors.
Fock et al., “Channel Tracking for Rake Receivers in Closely Spaced Multipath Environments” (IEEE Journal on Selected Areas Communications), Vol.

  Realization of a useful technique for removing multipath interference is desired.

を推定することと、フィルタリングされたサンプルΨ（τ）のチャネル複合係数

を推定することとを含む。以下のフィルタリングされたサンプルΨ（τ）の式の連立方程式の解によって、各パスｌに対するフィルタリングされたサンプルΨ（τ）から送信データｘ（τ_ｌ）を抽出する。 The method of the present invention extracts data from a received signal including multipath interference at a rake receiver. This method samples and filters the received signal and the time delay between paths for the filtered sample Ψ (τ)

And the channel composite coefficient of the filtered sample Ψ (τ)

Estimating. The transmitted data x (τ _l ) is extracted from the filtered sample ψ (τ) for each path l by solving the simultaneous equations of the following filtered sample ψ (τ) equation.

上式で、ｋは特定のパス、Ｎ_ｐは可視パスの数、

は、フィルタリング・プロセスの二重畳込み行列、

はその疑似逆行列（ｐｓｅｕｄｏ ｉｎｖｅｒｓｅ）、Λ_ｓｓ（τ_ｌ）は拡散行列とスクランブル行列との積、

はその逆行列、

は雑音である。

Where k is a specific path, N _p is the number of visible paths,

Is the two convolution matrix of the filtering process,

Is the pseudo inverse matrix, Λ _ss (τ _l ) is the product of the diffusion matrix and the scramble matrix,

Is its inverse matrix,

Is noise.

について選択的に行われる。時間遅延が１チップを超える場合、抽出は不要である。雑音

のないフィルタリングされたサンプルΨ（τ）式を解く。解の数は、受信機の１チップ当たりのオーバーサンプルの数以下とすることができる。連立方程式の解は、受信機に記憶することができ、この方法はソフトウェアで実行することができる。
本発明の上記およびその他の態様は、以下の詳細な説明を添付図面と共に検討すれば明らかになろう。 The method uses an estimated time delay of less than one chip in the receiver

Is done selectively. If the time delay exceeds 1 chip, no extraction is necessary. noise

Solve the filtered sample Ψ (τ) equation with no. The number of solutions can be less than or equal to the number of oversamples per chip of the receiver. The solution of the simultaneous equations can be stored in the receiver and the method can be performed in software.
These and other aspects of the invention will become apparent from the following detailed description when considered in conjunction with the accompanying drawings.

FIG. 1 is a diagram generally illustrating a rake receiver. Each element is well known and will not be described in detail herein. Only the elements or functional parts used in the method of the invention are shown. The rake receiver 10 receives path delay estimates τ ₁ , τ ₂ . . . τ ₃ and channel coefficients c ₁ , c ₂ . . . The estimate for c ₃ and a RAKE search unit 12 and the channel estimation unit 14 supplies the main processor 16. The main processing unit 16 includes a multi-path interference cancellation (MPIC) unit and a maximum ratio combining (MRC) unit. These can be hardware or software routines, depending on the configuration. As described herein, the MPIC is implemented in software to represent the received filtered signal as a linear equation and from the filtered samples of each path by solving the simultaneous equations of the filtered sample equations. By extracting transmission data, multipath interference cancellation or coping with multipath interference is realized.

  The present disclosure is independent of the method used for path delay estimation and the channel coefficients. Also, any method developed in the future can be used as well as the conventional method.

ここで、チャネル複合係数ｃ_ｌ（τ_ｌ）の推定は、データ・ブロック期間中一定しているものとし、
Ψ（τ）はフィルタリングされたサンプル、

はフィルタリングされたサンプルΨ（τ）についてのパス間の時間遅延、
ｘ（τ_ｌ）は抽出される送信データ、

はフィルタリング・プロセスの二重畳込み行列、

はその疑似逆行列、
ｋは特定のパス、
Ｎ_ｐは可視パス数、
Λ_ｓｓ（τ_ｌ）は、拡散ｓとスクランブルＳの行列の積、

はその逆行列、

は雑音であり、

である。 The linear equation for finding the solution is as follows.

Here, it is assumed that the estimation of the channel composite coefficient c _l (τ _l ) is constant during the data block period,
Ψ (τ) is the filtered sample,

Is the time delay between paths for the filtered sample Ψ (τ),
x (τ _l ) is extracted transmission data,

Is the two convolution matrix of the filtering process,

Is its pseudo inverse matrix,
k is a specific path,
N _p is the number of visible paths,
Λ _ss (τ _l ) is the product of the matrix of diffusion s and scramble S,

Is its inverse matrix,

Is noise,

It is.

がマルチパス干渉である。 Final sum of right side of equation (1)

Is multipath interference.

となり、送信データｘ（τ_ｌ）の解は

となる。ここで、

はデータ・ブロックの期間中一定であり、

である。 If the path delay is greater than one chip, the final sum of equation (1) is negligible due to the correlation characteristics of the scramble matrix S. Equation (1) is

The transmission data x (τ _l ) solution is

It becomes. here,

Is constant for the duration of the data block,

It is.

を使用して特定の比率ですべてのｘ_ｋを合計する。 If equation (4) is used for path delays greater than one chip, equation (4) represents an equalizer. Therefore, there is a simple solution for each path. Coefficient in MRC

Is used to sum all x _k at a certain ratio.

の各項がメモリに記憶される場合、式（４）はソフトウェアで実行される。

Is stored in the memory, equation (4) is executed by software.

  For path delays less than one chip, the final term is not negligible, and therefore, using equation (1) to solve all simultaneous equations for all paths, including multipath interference terms, the received signal By extracting data from, a better symbol estimate can be obtained.

を使用した推定値の和である。 The final estimate is a coefficient, such as

Is the sum of the estimated values using.

以下は、差が１チップ未満である２つのパス遅延の場合の例である。記述を簡単にするために、以下の表記

および

を使用する。各パス遅延の式（１）は以下のようになる。

The following is an example for two path delays where the difference is less than one chip. To simplify the description, the following notation

and

Is used. Equation (1) for each path delay is as follows.

雑音ｎを無視すると、この２つの連立方程式（６）は、以下の解で解かれる。

If the noise n is ignored, the two simultaneous equations (6) are solved by the following solution.

式（７）は、

と簡約することができ、行列Ｈは予め計算してメモリに記憶されている。

Equation (7) is

The matrix H is calculated in advance and stored in the memory.

の最大数はＮ_ＯＶＳとなる。ここで、値

はサンプリング・レートに等しい。これは、通信フォーマットとメモリ容量に依存する場合がある。 Theoretically, the number of visible paths is less than or equal to the number of oversampled _NOVS . Therefore, the matrix

The maximum number is N _OVS . Where the value

Is equal to the sampling rate. This may depend on the communication format and memory capacity.

  This application example is designed for 3G WCDMA, but can also be applied to other types of networks or communication protocols.

  While the invention has been described and illustrated in detail above, it will be clear that this is illustrative only and should not be construed as limiting. The scope of the invention is limited only by the claims.

It is a block diagram of a rake receiver.

Claims (6)

A method for extracting data from a received signal including multipath interference in a rake receiver, comprising:
Sampling and filtering the received signal;
Time delay between paths of filtered samples Ψ (τ)

Estimating
Channel composite coefficient of the filtered sample Ψ (τ)

Estimating
Formula for filtered sample Ψ (τ)

The transmission data x (τ _l ) is extracted from the sample Ψ (τ) filtered for each path 1 by solving the simultaneous equations of k, where k is a specific path N _p is the number of visible paths,

Is the two convolution matrix of the filtering process,

Is the pseudo inverse function, Λ _ss (τ _l ) is the product of the diffusion matrix and the scramble matrix,

Is its inverse function,

Including a step of being noise. The method includes an estimated time delay of a period of one chip or less of the receiver

The method of claim 1, wherein the method is selectively performed. noise

The method of claim 1, wherein the filtered sample Ψ (τ) equation without any is solved.   The method of claim 1, wherein the number of solutions is less than or equal to the number of oversamples per chip of the receiver.   The method of claim 1, wherein a solution of the simultaneous equations is stored in the receiver and the method is performed in software. The method of claim 5, wherein the number of stored solutions is less than or equal to the number of oversamples per chip of the receiver.

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