Class of low cross correlation non-palindromic synchronization sequences for code tracking in synchronous multiple access communication systems

摘要

A method and apparatus are provided which enables all return links from the remote stations in a star configured CDMA system to be maintained in time synchronization. This method employs special synchronization codes in conjunction with a standard CDMA chip time tracking apparatus, such as a Delay Lock Loop. Each of these special synchronization codes possesses an extremely low cross-correlation property with each of the other codes in the set of synchronization codes. The low cross-correlation property exists for time offsets up to plus and minus one CDMA chip period which permits the use of a standard chip timing discriminator apparatus, such as an early-late gate, within the Delay Lock Loop. Given the extremely low cross-correlation of these special synchronization codes, a significant improvement is achieved in time tracking performance and/or return link signal efficiency over prior art.