FDMA system performance with synchronization errors

The effect of time and frequency synchronization errors on the performance of an FDMA communication system using symmetric differential phase shift keying (SDPSK) is considered. Power and bandwidth efficiency of the system versus channel frequency spacing and adjacent channel power imbalance are investigated for the ordinary SDPSK, guard time demodulated SDPSK, and square root raised-cosine pulse shaped SDPSK signals. It is shown that for an FDMA system affected by synchronization errors and power imbalance, the square root raised-cosine shaped SDPSK signal and the guard time demodulated SDPSK signal can provide significantly higher signaling efficiency than ordinary SDPSK with matched filter detection. We consider an FDMA system of N users where each user communicates with the satellite with an SDPSK modulated signal of the same data rate.