Achieving MAI cancellation in an asynchronous DS/CDMA system by optimum single-user detection

The matched filter detector (MFD) is sub-optimal in DS/CDMA communications systems due to the presence of multiple access interference. This leads to a significant decrease in BER performance and hence system capacity. Multi-user detectors have been proposed to combat this problem but at the expense of a considerable increase in detector complexity. The optimum single-user detector (OSD) is presented, which, for a modest increase in complexity compared with the MFD, achieves MAI cancellation and hence improved BER performance over the MFD. A study of the auto-correlation matrix, R_a, leads to detector designs which perform MAI cancellation for both synchronous and asynchronous systems