Reception of coded OFDM signals in broad-band fading environments with strong cochannel interference

We focus on the channel estimation and the decoding of orthogonal frequency-division multiplexing (OFDM) signals in networking scenarios with multipath propagation and strong cochannel interference (CCI). The receiver views the CCI contained in the subchannel signal observations as additional independent Gaussian noise terms with varying variance from subchannel to subchannel as a consequence of the frequency-selectivity of the radio channels. We find that the capacity of OFDM channels with both the gain and the noise variance subject to broad-band fading may significantly exceed the capacity of a comparable OFDM channel with uniform noise power. Linear minimum mean-square error criterion based subchannel gain and noise variance estimators are presented which can exploit this margin, i.e., improve the spectral efficiency. The performance of the estimators is investigated for bit-interleaved coded OFDM systems and Rayleigh fading channels by computer simulations.