Asymptotic performance analysis for redundant block precoded OFDM systems with MMSE equalization

Linear precoding consists in multiplying by a N/spl times/K matrix a K-dimensional vector obtained by serial to parallel conversion of a symbol sequence to be transmitted. The performance of MMSE receivers for certain large random isometric precoded OFDM systems on fading channels is analyzed. Using new tools, borrowed from free probability theory, it can be shown that the signal to interference plus noise ratio at the equalizer output converges almost surely to a deterministic value depending on the probability distribution of the channel coefficients when N/spl rarr/+/spl infin/ and K/N/spl rarr//spl alpha//spl les/1. These asymptotic results are used to answer the trade-off convolutional coding versus linear precoding issue while preserving a simple MMSE equalization scheme at the receiver.