DA chip synchronizers for bandlimited DS/SS M-PSK signals using CDMA on mobile satellite communication channels

Derives two maximum-likelihood (ML) oriented decision/data-aided (DA) chip synchronization algorithms for bandlimited sequence spread spectrum (DS/SS) M-PSK transmitted over a multi-user mobile communication channel. The authors also investigate their tracking performance in the presence of multi-user interference. The performance of the channel aided (CA) algorithm was found to be independent of the fading characteristics, whereas the non-channel aided (NCA) algorithm is strongly influenced by the carrier-to-noise ratio C/M, but not by the fading bandwidth. The CA algorithm outperforms the NCA algorithm, whose performance degrades rapidly with decreasing C/M. The performance of both algorithms is better for synchronous than for asynchronous CDMA. For large signal-to-noise ratio, the tracking error variances approach asymptotic values that are proportional to the number of interfering users