Performance improvement of chip interleaved scheme for MB-OFDM system for 480Mbps

Abstract

Though the introduction of code division multiple access (CDMA) in orthogonal frequency division multiplexing (OFDM) technique, we propose a novel direct sequence spreading with chip interleaved scheme for a multi-band orthogonal frequency division multiplexing (MB-OFDM) system by reordering the chip sequences to achieve frequency diversity and randomization effect in frequency domain. MB-OFDM is a promising technique to implement high data rate ultra-wideband (UWB) transmission over short range in dense multipath environment with low-power consumption and low-cost characteristics. However, the original MB-OFDM proposal for 480 Mbps mode could not achieve satisfactory performance due to the inability of the error correction code at high coding rate such as 3/4 to provide sufficient protection for OFDM to combat the deep fading in some of subcarriers. In this paper, a chip-interleaved MB-OFDM UWB system is introduced and discussed. The performance has been evaluated and simulation results show that the proposed chip interleaved scheme improves the performance for 480 Mbps mode of about 1.5 dB at PER = 0.08. By using block spread chip interleaving structure, the interleaver structure for the proposed chip interleaved scheme is very simple to implement and has less delay latency