Noise optimized eigenfilter design of time-domain equalizers for DMT systems

Tkacenko, A.; Vaidyanathan, P.P.

doi:10.1109/icc.2002.996816

Cited by 11 publications

(9 citation statements)

References 9 publications

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“…Since MDS TEQ design is quite similar to MSSNR TEQ design, except for a quadratic instead of a wall penalty function [73], the advantages and drawbacks mentioned in Section V-B also apply here.…”

Section: E Minimum Delay Spread (Mds)mentioning

confidence: 99%

Unification and evaluation of equalization structures and design algorithms for discrete multitone modulation systems

Martin

Vanbleu

Ding³

et al. 2005

IEEE Trans. Signal Process.

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Abstract-To ease equalization in a multicarrier system, a cyclic prefix (CP) is typically inserted between successive symbols. When the channel order exceeds the CP length, equalization can be accomplished via a time-domain equalizer (TEQ), which is a finite impulse response (FIR) filter. The TEQ is placed in cascade with the channel to produce an effective shortened impulse response. Alternatively, a bank of equalizers can remove the interference tone-by-tone. This paper presents a unified treatment of equalizer designs for multicarrier receivers, with an emphasis on discrete multitone systems. It is shown that almost all equalizer designs share a common mathematical framework based on the maximization of a product of generalized Rayleigh quotients. This framework is used to give an overview of existing designs (including an extensive literature survey), to apply a unified notation, and to present various common strategies to obtain a solution. Moreover, the unification emphasizes the differences between the methods, enabling a comparison of their advantages and disadvantages. In addition, 16 different equalizer structures and design procedures are compared in terms of computational complexity and achievable bit rate using synthetic and measured data.

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Section: E Minimum Delay Spread (Mds)mentioning

confidence: 99%

Unification and evaluation of equalization structures and design algorithms for discrete multitone modulation systems

Martin

Vanbleu

Ding³

et al. 2005

IEEE Trans. Signal Process.

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“…In a similar fashion to recently proposed delay spread equalizers [8], [9], we change the definition of matrix Y in (5) from H T G T GH to H T H. With this change, we aim to minimize the ratio of the weighted sum of ISI power over the total signal power instead of the windowed signal power. Mathematically we reach the same optimum as the original one but with fewer computations when searching for optimal delay.…”

Section: B Review Of the Min-isi Methodsmentioning

confidence: 99%

“…The MSSNR method maximizes the ratio of the energy of the effective channel impulse response inside a target window of ν + 1 samples to that outside the target window. Alternate objective functions include maximizing the ratio of the energy inside the target window to the total energy [9], [16], and minimizing (maximizing) the energy outside (inside) the target window while holding the energy inside (outside) the target window fixed. Finitelength MSSNR TEQs are approximately symmetric [10].…”

Section: Introductionmentioning

confidence: 99%

Minimum intersymbol interference methods for time domain equalizer design

Ding

Evans

Martin

et al.

GLOBECOM '03. IEEE Global Telecommunications Conference (IEEE Cat. No.03CH37489)

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Abstract-During initialization, discrete multitone receivers train a time domain equalizer (TEQ) to shorten the channel impulse response to a preset length, ν + 1. Arslan, Kiaei, and Evans report a Minimum Intersymbol Interference (Min-ISI) method for TEQ design. Min-ISI TEQs give the highest bit rates among single-FIR TEQs amenable to real-time implementation on programmable fixed-point digital signal processors (DSPs). The Min-ISI method, however, has several disadvantages: (1) sensitivity to transmission delay, (2) inability to design TEQs longer than ν + 1 taps, and (3) sensitivity to the fixed-point computation in the Cholesky decomposition. In this paper, we develop an alternate Min-ISI cost function, from which we derive (1) a fast search method for the optimal transmission delay, (2) extensions to design arbitrary-length Min-ISI TEQs, and (3) an iterative Min-ISI method. The iterative Min-ISI method avoids Cholesky decomposition, designs arbitrary length TEQs, and achieves the bit rate performance of the original Min-ISI method.

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“…The optimal equalizer coefficients were found to be related to an eigenvector of a particular matrix. In [8], we generlized this method to also account for the noise present in the system. The equalizer coefficients were chosen to minimize an objective function consisting of a convex combination of a channel shortening objective and a noise-to-signal ratio objective.…”

Section: The Teq Desigin Problem 1 Introductionmentioning

confidence: 99%

A new eigenfilter based method for optimal design of channel shortening equalizers

Tkacenko

Vaidyanathan

2002 IEEE International Symposium on Circuits and Systems. Proceedings (Cat. No.02CH37353)

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Recently much attention has been given to the design of timedomain equalizers or TEQs for discrete multitone modulation (DMT) systems. In this paper, we present a new method for the design of such equalizers which minimizes both the intersymbol interference (ISI) and noise power observed in a DMT system. Furthermore, we show how this method can be used for the design of fractionally spaced equalizers or FSEs. Experimental results are presented showing that our design method performs better than other known techniques in terms of achievable bit rate. ChannelEqualizerFig. 1. SIMO-MIS0 channel and equalizer model. THE TEQ DESIGIN PROBLEM 1. INTRODUCTIONIn recent years, one problem which has been of great interest has been the design of time-domain equalizers or TEQs for discrete multitone modulation or DMT systems [ 1, 4, 61. Due to the long impulse response of typical channels encountered in DMT systems such as twisted pair telephone lines [7], TEQs are needed to shorten the overall channel response to one sample more than the length of the cyclic prefix used.Several methods previously proposed for the design of such TEQs involve the design of the effective channel and not the equalizer coefficients directly [l, 41. With these methods, the equalizer coefficients must then be chosen to best fit the desired optimal effective channel. A new method, however, was recently introduced [6] which deals directly with the equalizer coefficients. In this method, the objective was to minimize the delay spread of the overall channel. The optimal equalizer coefficients were found to be related to an eigenvector of a particular matrix. In [8], we generlized this method to also account for the noise present in the system. The equalizer coefficients were chosen to minimize an objective function consisting of a convex combination of a channel shortening objective and a noise-to-signal ratio objective.In this paper, we consider minimizing a different objective function consisting of a weighted sum of the intersymbol interference (ISI) power and the output noise power. Much like the methods of [6, 81, the optimal equalizer coefficients will also be found to be related to an eigenvector of a particular matrix. Furthermore, we will show that our results can be extended for the design of fractionally spaced equalizers or FSEs. Though FSEs have not been traditionally used as TEQs for DMT systems, the results shown here give merit to their possible future use. Denote the impulse responses of C ( z ) and H(z) by c(n) and h(n), respectively. The effective channel is ~r ( n )and has length L, + Le -1. Here, the output y(n) is of the form,where z f ( n ) and q(n) are, respectively, the filtered input signal and output noise sequences given by the following.We wish to choose H(z) to shorten the effective channel to a length Ld < L,. In other words, we wish to choose H(z) such that most of the substance of cer(n:) resides in a window W A 5[A, A + Ld -11, where A represents the delay of the desired shortened channel. Here we must have 0 5...

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Noise optimized eigenfilter design of time-domain equalizers for DMT systems

Cited by 11 publications

References 9 publications

Unification and evaluation of equalization structures and design algorithms for discrete multitone modulation systems

Unification and evaluation of equalization structures and design algorithms for discrete multitone modulation systems

Minimum intersymbol interference methods for time domain equalizer design

A new eigenfilter based method for optimal design of channel shortening equalizers

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