BER Efficient Interleaved OFDM System

Abstract

Precoded orthogonal frequency division multiplexed (OFDM) systems have low bit error rate (BER) performance compared to conventional OFDM systems. In this work, we have proposed a new buffer-interleaver based system architecture. The proposed system is found to have a better BER performance than the conventional precoded OFDM system when minimum mean square error (MMSE) equalization is performed. Using block-diagonal matrices, we have mathematically modelled buffer-interleaver architecture to derive a closed-form expression for the BER performance under frequency-selective fading channels, for zero-forcing (ZF) and MMSE equalizers. Our simulation results match the theoretical expression. It is shown that, as the buffer size increases, BER performance of MMSE equalizer improves, whereas in the case of ZF equalizer the BER performance nearly remains the same as the buffer size increases. A theoretical argument to show the BER performance enhancement is also provided.