Phase-noise-induced performance limits for DPSK modulation with and without frequency feedback

The effect of phase noise on the performance of differential phase shift keying (DPSK) is analyzed for four different receiver structures. The phase noise model used is more general than the standard Brownian motion model. It allows the observation of the effect of frequency feedback stabilization on system performance. The asymptotic performance in the limit as the signal-to-noise ratio tends to infinity is considered. The results show that feedback stabilization results in a considerable performance improvement. For example, in a narrowband receiver this scheme results in an effective linewidth reduction by a factor of 12.5 when the feedback bandwidth is 0.8 times the bit rate, and by a factor of 42 when the feedback bandwidth is 1.6 times the bit rate. Therefore, frequency feedback reduces the minimum required data rate for a given laser linewidth, or increases the maximum linewidth allowed for a given data rate. The performance of the narrowband receiver in the presence of both additive and phase noises is determined and a dramatic improvement with feedback is shown