A comparison of coherent and differentially coherent detection schemes for fading channels

The common basis of coherent and differentially coherent detection is considered from the viewpoint of carrier recovery as the estimation of fading distortion. In the differentially coherent receiver a simple estimate of the fading distortion is used whereas the coherent receiver uses the optimal estimate. The bit error rates (BERs) for M-ary PSK (phase-shift keyed) and DPSK (double phase-shift keyed) transmission are calculated using a single method of calculation for both detection schemes. The calculation takes into account nonperfect carrier recovery, cochannel interference, and diversity. The results allow a direct comparison of the two schemes and show that coherent detection is preferable in many realistic fading environments