Noncoherent parallel acquisition in CDMA spread spectrum systems

Abstract

This paper derives the performance of a direct sequence spread spectrum acquisition scheme, effect of multiple access interference on acquisition performance is determined. Noncoherent acquisition performance is of interest because the system can acquire before it achieves carrier phase lock, and parallel schemes are of interest because they significantly reduce acquisition time over serial schemes. The analysis presented is applicable to the reverse link (mobile to base station) of a mobile communications system which employs code division multiple access (CDMA). By deriving results for both long and short spreading sequences, it is also shown that the periodicity of the spreading sequences has a significant effect on acquisition performance. Finally, the issue of capacity determined by acquisition performance criteria is addressed. The results show that, under certain conditions, the capacity is limited by acquisition, thus indicating the importance of the acquisition problem. >