Performance studies of interleaving schemes for MC-CDMA systems

A novel chip level interleaving (CLI) scheme is proposed for multicarrier code division multiple access (MC-CDMA) system by reordering the chip sequences to achieve frequency diversity and randomization effect in frequency domain. The performance has been evaluated and simulation results show that the proposed CLI scheme increases system capacity significantly compared to the conventional schemes. By using block spread chip interleaving structure, the interleaver structure for the proposed CLI scheme is very simple to implement and has less delay latency. Moreover, the performance comparisons of various frequency domain interleaving schemes, namely bit level interleaving (BLI), symbol level interleaving (SLI) and the proposed CLI for MC-CDMA systems have been subsequently investigated by taking into consideration of complexity. The effects of different interleaving schemes under various scenarios such as outdoor (large delay spread) and indoor (small delay spread) environments have been evaluated and a switching mode has been discussed to choose the optimum interleaving scheme under different scenarios to maximize the system throughput.