The effect of oscillator phase noise on DPSK demodulation for picoterminal reverse links

In earlier studies based on the European Space Agency´s Olympus satellite 30/20 GHz payload parameters, it was found that several thousands of simultaneous transmissions of 50 to 200 bits/sec each could be supported from hand-held (10 cm) picoterminal Earth stations. It is well known that such low data rate signals are severely affected by the inevitable phase noise of microwave local oscillators. DPSK modulation is generally preferred for low data rate applications because it is expected to have more robust performance in the presence of oscillator phase noise. The authors present an analysis of the performance degradation of DPSK caused by phase noise. Results are presented showing that DPSK is subject to an irreducible error rate in the phase noise contaminated channel. The irreducible error rate as the data is reduced, and there is a minimum useable data rate for any given bit error rate (BER) requirement. Results of a complete analysis are presented in the form of BER versus E_b/N_o plots, showing good agreement with the predicted irreducible error rates