Multi-Dimensional Subcarrier Mapping for Bit-Interleaved Coded OFDM with Iterative Decoding

Multi-dimensional mapping over groups of subcarriers, called subcarrier mapping, is proposed and investigated for bit-interleaved coded in OFDM with iterative decoding (BI-COFDM-ID) over correlated frequency-selective Rayleigh fading channels. A tight bound on the asymptotic error performance is first presented and used to establish the design criterion. It is then shown that one could choose an optimal subcarrier grouping scheme and an optimal multi-dimensional mapping independently to achieve the best overall error performance. Analytical and simulation results show that it is not necessary to implement linear constellation precoding (LCP) in the proposed system while still achieving the full diversity offered by frequency-selective fading channels, and at the same time providing significant coding gains compared to the previously studied BI-COFDM-ID. Such coding gains are obtained without any power nor bandwidth expansion and with the same receiver complexity.