Iterative multiuser receiver/decoders with enhanced variance estimation

We study the impact of variance estimation on a receiver, where the soft information provided by the channel decoder is utilized in the multiuser detection. Specifically, we consider a receiver structure that resembles the structure of an iterative decoder for a serially concatenated code, but where the inner constituent decoder is replaced by an interference cancellation (IC) unit. The system performance with three different variance estimator methods is studied through numerical simulations. The results show that the variance estimation method has a great impact on the receiver performance especially in the case, where the different users are received with different powers.