MMSE/PIC multi-user detection for DS/CDMA systems with inter- and intra-cell interference

This paper analyses combinations of the linear MMSE detector and a non-linear parallel interference canceller (PIC) for multi-user CDMA detection. Both the case where all users´ codes are known at the receiver, and the case where only some codes are known are considered. An upper bound and an approximate formula for the error probability are derived and verified through simulation It is shown that the combined MMSE/PIC detector can have a considerable performance gain over the MMSE. It is also shown that while the MMSE detector is sensitive to large code cross-correlation values, the combined MMSE/PIC detector is robust to code cross-correlations. Finally, use of the MMSE/PIC detector for cellular systems with both inter- and intra-cell interference is considered