On a method to improve correlation properties of orthogonal polyphase spreading sequences, Journal of Telecommunications and Information Technology, 2003, nr 2

Abstract

In this paper, we propose a simple but efficient method for improving correlation properties of polyphase spreading sequences for asynchronous direct sequence code division multiple access (DS CDMA) applications. The proposed method can be used to reduce the mean square value of aperiodic crosscorrelation or the mean square value of aperiodic autocorrelation, the maximum value of aperiodic cross-correlation functions, merit factor or other properties of the sequence set. The important feature of the method is that while it modifies correlation properties of the sequence set, it preserves sequence orthogonality for perfect synchronization, if this is the property of the original sequence set