Error performance of circular 16-DAPSK with postdetection diversity reception in Rayleigh fading channels

A closed-form expression for the average error probability of circular 16-ary differential amplitude and phase shift keying with postdetection diversity combining is obtained for frequency-nonselective Rayleigh fading channels. The effect of random FM noise is also considered in the evaluation. Since both amplitude and phase are encoded and decoded independently, their detailed performances are analysed separately. System parameters such as the ring ratio and decision thresholds have been optimised for a number of fading conditions. The optimal and suboptimal decision thresholds are evaluated. The optimal ring ratio of the modulation is generally a function of Doppler frequency. The results have shown that postdetection diversity is a powerful technique for reducing the effects of random FM noise.