Single-user decoder metrics for subtractive interference cancellation detectors in code-division multiple-access (CDMA) communication systems

摘要

Improved branch metrics for Viterbi decoders in CDMA systems take into account the time dependency of the variance of the multiple access interference in any user's signal after the single-user detector, and the time dependency of the residual multiple access interference in any user's signal after subtractive interference cancellation is applied in two-stage detectors. The (residual) multiple access interference can be modeled as a Gaussian random variable with time dependent variance. Modeling the RMAI in such a way reduces the bit error rate in CDMA systems.