Aperiodic correlation properties of quaternary sequences with near-optimum periodic correlation

Quaternary sequences for which the periodic correlation functions are nearly optimum have been constructed by Boztas, Hammons, and Kumar (1992). In this paper we examine the aperiodic autocorrelation functions for these sequences. Attention is focused on the aperiodic autocorrelation properties which influence the acquisition and antimultipath performance of direct-sequence (DS) spread-spectrum systems. Optimization of the phases (i.e., orientations within the data symbols) of the sequences is shown to give a significant reduction in the maximum of the sidelobe magnitudes for the odd autocorrelation functions. It is shown that even for the optimal phases, the odd autocorrelation maxima are still larger than the periodic autocorrelation maxima for most of the sequences considered.