Implementation Complexity and Communication Performance Tradeoffs in Discrete Multitone Modulation Equalizers

Martin, Richard R.; Vanbleu, K.; Ding, Ming; Ysebaert, G.; Milošević, Miloš; Evans, Brian L.; Moonen, Marc; Johnson, C.R.

doi:10.1109/tsp.2006.877637

Cited by 28 publications

(31 citation statements)

References 47 publications

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“…However, this requirement is often restrictive, especially at high sampling rates, where the channel order can extend into many hundreds of samples. In order to overcome this problem, the pre-filter w is placed at the receiver in cascade with the channel to produce an effective shortened impulse response, optimally squeezing the channel energy into a time-frame of less than L + 1 samples [19]. Different solutions to meet the symmetry condition are proposed in [13, p. 915].…”

Section: Discrete Cosine Transform For Multicarrier Modulationmentioning

confidence: 99%

On the Use of Discrete Cosine Transforms for Multicarrier Communications

Cruz–Roldán

Jiménez

Vidal

et al. 2012

IEEE Trans. Signal Process.

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Abstract-In this correspondence, the conditions to use any kind of discrete cosine transform (DCT) for multicarrier data transmission are derived. The symmetric convolution-multiplication property of each DCT implies that when symmetric convolution is performed in the time domain, an element-by-element multiplication is performed in the corresponding discrete trigonometric domain. Therefore, appending symmetric redundancy (as prefix and suffix) into each data symbol to be transmitted, and also enforcing symmetry for the equivalent channel impulse response, the linear convolution performed in the transmission channel becomes a symmetric convolution in those samples of interest. Furthermore, the channel equalization can be carried out by means of a bank of scalars in the corresponding discrete cosine transform domain. The expressions for obtaining the value of each scalar corresponding to these one-tap per subcarrier equalizers are presented. This study is completed with several computer simulations in mobile broadband wireless communication scenarios, considering the presence of carrier frequency offset (CFO). The obtained results indicate that the proposed systems outperform the standardized ones based on the DFT.Index Terms-Carrier-frequency offset (CFO), discrete cosine transform (DCT), discrete multitone modulation (DMT), multicarrier modulation (MCM), multicarrier transceiver, orthogonal frequency-division multiplexing (OFDM).

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Section: Discrete Cosine Transform For Multicarrier Modulationmentioning

confidence: 99%

On the Use of Discrete Cosine Transforms for Multicarrier Communications

Cruz–Roldán

Jiménez

Vidal

et al. 2012

IEEE Trans. Signal Process.

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“…Although MDS is one of the solutions that have the lowest complexity after Chow's method, see [3], it requires matrix operations and especially one linear system solution per iteration to solve (3). Matrix operations are still quite complex and yield problems of numerical stability in microprocessors that prevent their application in most cases.…”

Section: Proposed Solutionmentioning

confidence: 99%

“…For comparison purpose, we also provide here the complexity of CM and MDS by refining the coarse estimation in [3]. Let I CM and I MDS be the number of iterations used for CM and MDS, respectively, we have…”

Section: B Complexity Comparisonmentioning

confidence: 99%

“…Among those, the iterative minimum delay spread (MDS) method of [1] always converges, while computing one matrix inversion per iteration, thus yielding significant computational complexity and memory requirement. All other methods require the computation of eigenvectors of channel-dependent matrices, resulting again in a high computational complexity typically of the order of N 3 , where N is in the order of the total length of the TEQ filter and the channel impulse response [3]. The method proposed by Chow et al in [4] reduces the complexity to the order of N log 2 N by using an iterative solution based on discrete Fourier transform (DFT) instead of matrix inversion.…”

Section: Introductionmentioning

confidence: 99%

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Low complexity channel shortening for discrete multitone modulation systems

Nguyễn

Tomasin

2017

2017 25th European Signal Processing Conference (EUSIPCO)

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Abstract-In discrete multitone (DMT) modulation systems, the channel duration can be longer than the cyclic prefix, yielding both inter-block and inter-carrier interference. In order to avoid these effects, time-domain equalization (TEQ) techniques are usually employed before DMT demodulation. This letter introduces a modification of the iterative minimum delay spread (MDS) method proposed by Lopez-Valcarce in [1] to adapt the TEQ coefficients to the channel. The proposed solution is based on a) the approximation to the solution of a set of equation, and b) a new reference time selection. The resulting scheme requires only a single matrix inversion at the last iteration rather than one per iteration, achieving a significantly lower implementation complexity than iterative MDS, while performing similarly in terms of spectral efficiency.

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“…For a detailed quantitative comparison of the communication performance versus implementation complexity tradeoffs of several equalizer architectures, see the paper by Martin et al [11]. One implementation of a frequencydomain equalizer architecture is the per-tone equalizer (PTEQ) approach [6], [12], which is designed to move the TEQ into the bank of single-tap FEQs to obtain a bank of multitap FEQs.…”

Section: Introductionmentioning

confidence: 99%

Tap Loading of Subcarrier Equalizers for Wireless Multicarrier Transceivers

Wyglinski

Cudnoch²,

Labeau

et al. 2008

IEEE Trans. Veh. Technol.

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Abstract-We present a novel algorithm for defining the lengths of subcarrier equalizers employed by wireless multicarrier transmission systems operating in frequency-selective fading channels. The equalizer lengths across the subcarriers are incrementally varied in a "greedy" fashion until the global cost function is below some prescribed threshold. By varying the equalizer lengths, the overall complexity of the equalization is constrained while the system meets a minimum error performance. Moreover, we investigate four strategies for terminating the proposed algorithm when an adequate number of equalizer taps have been allocated in this process. The results show that a system that employs variable-length equalizers defined by the proposed algorithm can achieve an improvement in error robustness of as much as an order of magnitude, relative to a system that employs constantlength equalizers with the same overall complexity.

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Implementation Complexity and Communication Performance Tradeoffs in Discrete Multitone Modulation Equalizers

Cited by 28 publications

References 47 publications

On the Use of Discrete Cosine Transforms for Multicarrier Communications

On the Use of Discrete Cosine Transforms for Multicarrier Communications

Low complexity channel shortening for discrete multitone modulation systems

Tap Loading of Subcarrier Equalizers for Wireless Multicarrier Transceivers

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