Effects of Subcarrier Interleaving on LDPC Coded MC-CDMA Systems

Abstract

This paper describes the effects of subcarrier interleaving on low density parity check (LDPC) coded multi-carrier code division multiple access (MC-CDMA) system. Subcarrier interleaving in MC-CDMA system can achieve the randomization effect of burst error in frequency domain, but it generates the distortion among the spreading codes due to the destruction of orthogonality. In channel-coded system, however, the achievable frequency diversity effect associated with the subcarrier interleaving in frequency domain also depends on the channel coding gain. So, there is a trade off between frequency diversity gain via subcarrier interleaving or channel coding, and destruction of orthogonality. From the simulation results, frequency diversity gain by channel coding is more effective than subcarrier interleaving, especially for system with high order modulations and with low code rates.