Spread spectrum synchronization for a LEO personal communications satellite system
David E. Dodds, M. Moher · 2002
This paper investigates required signal structure and receiver code synchronization techniques for satellite based CDMA personal communications systems. A signal structure is proposed in which different CDMA codes are used to differentiate each satellite (as in the GPS system) and different phases of one code (as in the IS-95 standard) to differentiate spot beams on one satellite. Due to satellite overlap, the number of effective co-users in each cell can be two or three times the number of actual cell users which leads to a required spreading gain in the order of 20 times the actual number of cell users. The paper investigates correlator receiver structures and shows that the optimum correlation time is 400-1000 chips when the number of effective co-users is 100.