A Simple Unified Phasor Analysis for PN Multiple Access to Limiting Repeaters

This paper presents a simple phasor model for analyzing coherent direct-sequence, pseudonoise (PN), spread-spectrum carriers accessing limiting repeaters in the presence of strong interference. Limiting repeaters are found in several applications, one being satellite relays. The model used provides a rigorous upper bound on system bit error rate depending only on an equivalent E_b/N₀. Presented for the first time is an application of the model to RF limiters having an AM-to-PM conversion effect. For quadriphase PN, receiver E_b/N₀ is given by the heuristic approach of replacing the limiter with an average power-limited linear device plus an additional loss L due to limiting. As long as there is no AM-to-PM conversion in the limiter, L is the same as that obtained by passing multitone CW plus noise through the limiter. For quadriphase PN carriers passing through a limiter with AM-to-PM conversion, L can depend on the type of coherent phase tracker used. E_b/N₀ for biphase PN, in contrast to quadriphase PN, need not have the usual heuristic form given by quadriphase PN.