O3BPSK-based Linear Decorrelating Detector for Asynchronous DS/CDMA Systems over Frequency-Selective Rayleigh Fading Channels

In this paper, a convenient signaling scheme, called orthogonal on–off BPSK (O3BPSK), along with a simple one-shot linear decorrelating detector (LDD) and a whitening Rake bank, is proposed for near–far resistant detection in asynchronous DS/CDMA systems. Based on the maximum multi-path spreading delay, a minimum duration of “off” is suggested, during which the temporally adjacent bits (TABs) that contain multi-user interference (MUI) and inter-symbol interference (ISI) from different users at the receiver are decoupled. The O3BPSK signaling scheme is combined with the whitening Rake receiver to preserve multi-path diversity gain in multi-path fading CDMA channels. The scheme offers low complexity, no detection delay, near–far resistance, and compensation for fading channels.