Iterative interference cancellation for a coded multicarrier frequency-hopping CDMA (MC-FH-CDMA) system

In this paper, we consider a low complexity iterative multiuser receiver for the coded MC-FH-CDMA system, introduced in M. Ebrahimi T.M. and M. Nasiri-Kenari (May 2002). The structure of the proposed receiver consists of a multiuser likelihood calculator (MULC) and a bank of SISO channel decoders one for each active user. Based on the received signal and a priori information about code bits provided by SISO decoders in the previous iteration, MULC computes extrinsic information of coded symbols of active users in the form of log-likelihood ratio (LLR). This information is used by channel decoders as a priori information to compute an update of LLRs. The processing proceeds in an iterative manner similar to the decoding of turbo codes. We evaluate the performance of the proposed receiver in AWGN channels. Our numerical results show that the new receiver significantly improves the system performance. After a few iterations, the receiver reaches its ultimate performance, which is very close to the single-user performance.