Low-complexity channel estimation for wireless OFDM systems

Wireless communication systems incorporating coherent OFDM requires the estimation and tracking of the time-varying channel response for accurate demodulation of data at the receiver. In pilot-symbol-assisted (PSA) OFDM systems, the minimum mean-square-error (MMSE) estimator is a good channel estimation technique given that channel statistics are known. However, the major drawback of the MMSE estimator is its high computational complexity, which grows with number of pilots. Piecewise-linear interpolation is a low complexity solution to the channel estimation task. In this paper we derive exact expressions for the channel estimation error as a function of pilot spacing, channel statistics and channel noise, when piecewise-linear interpolation is incorporated. We compare the performance of piecewise-linear interpolation against that of a low complexity MMSE technique (piecewise-MMSE interpolation) under both matched and mismatched conditions of channel statistics. Results show that a piecewise-linear interpolator performs better than a mismatched piecewise-MSSE interpolator of same complexity.