Successive interference cancellation in CDMA systems: log-likelihood ratio approach

We propose a new successive interference cancellation (SIC) scheme that cancels the interference in order of the magnitude of log-likelihood ratio (LLR) in CDMA systems. The motivation is that it provides the reliability information on the maximum a posteriori decision. As a result, the error propagation associated with a wrong data detection can be minimized and the resulting error probability for the remaining users can be reduced. We show that the LLR-ordered SIC outperforms the traditional SNR-ordered SIC significantly. Non-binary signaling and the effect of channel estimation errors are discussed