Noncoherent Detection and Differential Detection

From the communication channel and implementation aspects of communications, the transmission environement may be sufficiently degraded, e.g. a multipath fading channel, that acquiring and tracking a coherent demodulation reference signal is practically difficult. Coherent receivers require exact knowledge of the channel phase for optimum performance. Due to the difficult task of estimation channel phase, differential detection is an attractive alternative to coherent detection. A conventional differential detector uses the signal received in the previous symbol interval as a phase reference for the received signal in the current interval. As long as the phase distortion introduced by channel varies slowly relative to the symbol rate, conventional differential detection will work quite well. This paper shows a short overview of some algorithms for noncoherent detection and differential detection, particularly with PSK modulation technique.