Turbo decoding of error control coded and unitary precoded OFDM

This paper addresses the design of a novel scheme that combines error control coding (EC) and unitary precoding (UP) in order to obtain high diversity gains in OFDM systems with low complexity. The overall diversity of the proposed system is shown to be the product of the individual diversities achievable by the error control coding and by the unitary precoding, while the complexity is just a linear multiple of the sum of their individual complexities. In a practical HiperLan/2 setup, the proposed system achieves a gain of 4 dB, (3.3 dB), at a bit error rate (BER) of 10^-3, relative to conventional OFDM systems that only deploy convolutional (turbo) coding.