Multiple-access interference suppression technique employing orthogonal/random spreading sequences and a novel decentralized receiver for B-CDMA^TM forward link systems in multipath channels

In this paper, we study a multiple-access interference (MAI) suppression technique employing concatenated orthogonal/random spreading sequences and a novel decentralized linear receiver for B-CDMA^TM forward link in multipath fading channels. The proposed receiver treats the MAI as additional noise, while exploiting in an optimal way the homogeneous characteristics of the MAI which is partially suppressed at the despreader of the receiver by utilizing orthogonal sequences. The matched filter RAKE receiver and inverse filter are also considered for comparison. The system performance is evaluated in terms of required bit-energy to effective noise (MAI-plus-AWGN) power spectral density to achieve an acceptable quality of service. We show that employing the concatenated orthogonal/random spreading scheme in the synchronous forward link, the proposed receiver results in better system performance relative to the others and show the impact of the concatenated spreading sequences on the forward link system performance, as compared to the use of the nonconcatenated random spreading scheme.