Optimization of orthogonal polyphase spreading sequences for wireless data applications

We propose a simple but efficient method for optimizing correlation properties of polyphase spreading sequences for asynchronous DS CDMA applications. The proposed method can be used to minimize the mean square value of aperiodic crosscorrelation or the mean square value of aperiodic autocorrelation, the maximum value of aperiodic crosscorrelation functions, merit factor or other properties of the sequence set. The important feature of the method is that when applied to orthogonal sequences, it modifies correlation properties of the sequence set, while it preserves their orthogonality for perfect synchronization.