Channel estimation error compensation in OFDM based multi-carrier systems

Orthogonal frequency division multiplexing (OFDM) is shown to be an efficient modulation methodology to combat the frequency selective effects of wireless channels. Frequency domain equalization (FDE) is frequently used in OFDM systems to eliminate the effects caused by the channel. In order to apply FDE, channel taps need to be estimated. In this paper, we investigate the effect of unequal amplitude constellation symbol combined with the channel estimation error on the received signal, for constellations such as M-ary quadrature amplitude modulation (M-QAM) where M >4. We give the problem formulation and propose a constellation distortion methodology in order to improve system error performance. Proposed method is supported by simulation results.