Optimum single-user detection for DS/CDMA systems achieving complete MAI cancellation

Conventional matched-filter detection (MFD) in a DS/CDMA system is sub-optimal when the channel noise is dominated by multiple access interference (MAI). MAI is a limiting factor to the bit error rate performance. Multi-user detector schemes have been proposed to combat MAI but these schemes have a high degree of complexity. The optimum single-user detector (OSD) considerably reduces the complexity while maintaining an improvement in the BER performance over the MFD. The first realisation of this detector (OSD-1) was proposed by O'Farrel (1989). A new interpretation of this detector architecture (OSD-2) is presented which can completely cancel MAI. A comparison of the OSD-2 with OSD-1 and the MFD is presented.