On The Synchronization Technology In The CDMA Satellite Communications

With the development of satellite communications technology, more and more attention is paid on the CDMA small low-orbit satellite communications system. Frequency offset of receiving signal caused by doopler effect in the satellite channel is a key characteristic of small low-orbit satellite communication. In this paper, the PN acquisition and carrier frequency synchronization technologies in large Doppler frequency shift condition are studied. Based on the characteristic of satellite channel, the formation of doppler is discussed, as well as the effect on signal transmission. The capture technology of spreading code and maximum likelihood criterion in statistical signal processing are analysised. After a brief introduction of the CDMA communication system theory and signal model, the spread spectrum sequence synchronization method which is closely relative with carrier frequency estimate is given. Finally the method using partial matched filter and recirculation loop is dicussed.