Noncoherent anti-interference receivers for DS/SS signals

Conventional narrowband interference (NBI) rejection algorithms often assume perfect pseudo-noise (PN) code synchronization and coherent detection. The functions of NBI rejection, data detection and code tracking are performed separately and independently by an adaptive detector and a code tracking loop, respectively. This paper presents three new noncoherent receiver structures for differential phase shift keying (DPSK), direct sequence spread spectrum (DS/SS) signals. Our receivers are designed to suppress NBI, mitigate multipath interference and minimize code tracking jitter at the same time. We first propose a generic receiver structure and evaluate the signal-to-interference ratio (SIR) for its detection decision variable. Optimal interference suppression and code tracking algorithms that maximize SIR are then derived. Other algorithms that use different criteria are also given. Numerical results using both analysis and computer simulation are presented to compare performance of various receiver structures.