ERROR PERFORMANCE OF MULTIPLE-SYMBOL DIFFERENTIAL DETECTION OF PSK SIGNALS TRANSMITTED OVER CORRELATED RAYLEIGH FADING CHANNELS

We study the error performance of multiple-symbol differential detection of uncoded QPSK signals transmitted over correlated Rayleigh fading channels. The optimal detector is presented, along with an exact expression for the corresponding pairwise error event probability. Subsequently, it is found that multiple-symbol differential detection is a very effective strategy for eliminating the irreducible error floor associated with a conventional differential detector. In all of the cases we have investigated, a detector with an observation interval as small as two symbols is sufficient for this purpose. We have also found that the error performance of a multiple-symbol differential detector is not sensitive to the mismatch between the decoding metric and the channel fading statistics. For example, in a static fading channel, the penalty of using a decoder matched to a Doppler frequency of 1% of the signaling rate is only 2 dB at an error rate of 10(-4).