A Low Complexity Interference Cancellation Technique for Multi-User DS-CDMA Communications

A low complexity Parallel Interference Cancellation (PIC) technique is proposed to suppress Multi-Access Interference (MAI) and minimize near-far effect for multi-user communication using Direct-Sequence Code Division Multiple Access (DS-CDMA). Interference signal is estimated using a relationship between cyclic correlation of the received signal and user´s code of the interferer without requiring any knowledge of the channel condition. The user´s codes for the multi-user DS-CDMA communication are constructed by using a set of m-sequences. The cyclic correlation is performed using Fast Walsh-Hadamard Transform (FWHT) which exhibits low computational complexity, i.e., it does not require any multiplication/division operations. In addition to low complexity, the proposed technique does not require complicated channel condition estimation and has no convergence issues. The uncoded Bit Error Rate (BER) performance of the proposed interference cancellation is calculated and compared with the conventional one over three different types of channels: AWGN, slow Rayleigh fading, and multipath channels.