Metric weighted diversity combining based on multiple differential phase detection and its performance in mobile communication environments

In diversity reception of differential PSK signals, the theoretical lower l imit of the bit-error rate can be achieved in principle by maximal ratio co mbining after coherent detection. It is difficult, however, to realize comp lete carrier regeneration in a fading environment. This paper tries an appr oach to the theoretical lower limit. The previously proposed signal process ing by multiple differential phase detection is introduced into the diversi ty reception, and the effectiveness of the proposed method is examined. Whe n the channel characteristics fluctuate by fading, the multiple differentia l phase detection must be completed within the period in which the received signal is coherent (i.e., the fading has a high time correlation). Consequ ently, it is expected that the signal processing of the multiple differenti al phase detection is effective for slowly varying fading but less effectiv e for fast-varying fading. From such a viewpoint, the bit-error rate for Ra yleigh fading with various rates of change is examined by computer simulati on. The following properties have been found. (I)The performance is close t o the theoretical lower limit with a difference of 0.5 dB, for the slow fad ing. (2) The performance may also be better than the conventional maximal r atio combining after the differential detection, for fast fading, depending on the case. In other words, it is effective to introduce the signal proce ssing of the multiple differential phase detection into the diversity recep tion. (C) 2001 Scripta Technica.