NONREDUNDANT ERROR-CORRECTION DQPSK FOR THE AERONAUTICAL-SATELLITE CHANNEL

The performance of differentially encoded quadrature phase-shift keyin g (DQPSK) system employing nonredundant error correction (NEC) receive rs with single- and double-error correction capability is analyzed and evaluated for the aeronautical satellite channel. The NEC is an attra ctive coding technique which employs differential detectors with more than one symbol delay elements and which does not introduce any redund ancy as other coding schemes do. As typical for aeronautical satellite communications, a Rician fading channel with Gaussian power spectrum has been considered. Unlike the additive, uncorrelated from symbol to symbol interference such as additive white Gaussian noise (AWGN) or st atic cochannel interference (CCI) which has been investigated in the p ast, analysis of the performance in a fading channel is much more diff icult. The difficulty arises from the multiplicative and correlative n ature of the fading interference. Bit error rate (BER) performance eva luation results have been obtained by means of computer simulation for various channel conditions, including different values of the K-facto r and the fading BDT. These results have indicated that considerable p erformance gains as compared with conventional differentially detected systems are achieved for high values of K and for very fast fading. B oth of these conditions are encountered in typical aeronautical commun ication system. Wherever possible, heuristic explanations of the trend of the obtained BER performance evaluation results are also given.