A low-complexity ML channel estimator for OFDM

• Published in: IEEE transactions on communications Vol. 51; no. 2; pp. 135 - 140
• Main Authors: Deneire, L., Vandenameele, P., van der Perre, L., Gyselinckx, B., Engels, M.
• Format: Journal Article
• Language: English
• Published: New York IEEE 01.02.2003; The Institute of Electrical and Electronics Engineers, Inc. (IEEE); Institute of Electrical and Electronics Engineers
• Subjects: Channels; Computer Science; Construction; Delay estimation; Distortion measurement; Engineering Sciences; Equalizers; Estimators; Frequency division multiplexing; Frequency measurement; Frequency response; Gain measurement; Impulse response; Mathematical models; Maximum likelihood estimation; OFDM; Orthogonal Frequency Division Multiplexing; Performance gain; Signal and Image processing; Spreads; Symbols
• ISSN: 0090-6778; 1558-0857
• DOI: 10.1109/TCOMM.2003.809234

Orthogonal frequency-division multiplexing with cyclic prefix enables low-cost frequency-domain mitigation of multipath distortion. However, to determine the equalizer coefficients, knowledge of the channel frequency response is required. While a straightforward approach is to measure the response to a known pilot symbol sequence, existing literature reports a significant performance gain when exploiting the frequency correlation properties of the channel. Expressing this correlation by the finite delay spread, we build a deterministic model parametrized by the channel impulse response and, based on this model, derive the maximum-likelihood channel estimator. In addition to being optimal (up to the modeling error), this estimator receives an elegant time-frequency interpretation. As a result, it has a significantly lower complexity than previously published methods.