Multiuser detection for multiple-access communications using wavelet-packet transforms

A wavelet-packet-based alternating projection joint detector (WPAPJD) for over-saturated multiple-access systems is proposed. By exploiting the structure of the multiple-access interference (MAI) associated with the wavelet packets used, the MAI seen by each user can only occur within a small-size subgroup of users. Further, MAI is reduced by using an APJD as applied to the subgroup. In comparison with a refined multistage joint detector, simulation studies show that our proposed method offers improved bit-error rate (BER) with reduced computational complexity in applications where a signal-to-noise ratio less than 16 dB is acceptable