Polyphase Pseudo-Noise Sequences with Equivalent Even and Odd Correlation Properties

Abstract

This paper proposes and investigates a method of designing pseudo-noise (PN) sequences having equivalently good properties of both even and odd correlations, i.e. EOE sequences, which are important for acquisition and demodulation in spread-spectrum (SS) communications. Odd correlation property of PN sequences should be designed as well as their even or periodic correlation property so that, interference of data-modulated PN sequences can he reduced as small as possible. We describe a method of designing polyphase EOE sequences from biphase PN sequences with a good a periodic correlation property under a certain condition. Absolute values of both even and odd correlation functions of these sequences at each shift can be equal. We evaluate properties of the derived sequences by peaks of crosscorrelations and out-of-phase autocorrelations and BER. It is shown that the polyphase sequences have lower peaks of crosscorrelations and out of phase autocorrelations and lower BER than the biphase ones by numerical evaluation. Furthermore the generalized odd correlation function which is important in polyphase SS systems is defined, and a method to improve the generalized odd correlation properties are derived.