Comments on "Partial parallel interference cancellation for CDMA"

In this letter we comment on partial parallel interference cancellation as discussed in the above paper by Divsalar et al. The aforementioned work showed that by multiplying symbol estimates by a factor less than unity in early stages of cancellation, the performance of parallel cancellation can be improved relative to full (“brute force”) cancellation. In this letter we analyze the improvement of parallel cancellation when using partial cancellation, and provide additional insight into the gains. Specifically, we show that the decision statistic is biased when linear (soft) estimates of the symbol or channel are used for cancellation. Partial cancellation improves performance in this case by reducing the decision statistic bias.