Modulation and coding for mobile radio communications: channelswith correlated Rice fading and Doppler frequency shift

摘要

We discuss the relative performance of coherent phase-shift keyingn(PSK), differential PSK (DPSK), and double differential PSK (DDPSK)nmodulation schemes over a mobile radio channel in which transmission isnaffected by additive noise, a constant carrier phase offset, a constantnDoppler frequency shift, and correlated Rice fading. We first comparenthe performance of these schemes to assess the amount of degradationncaused on each one of them by fading. Among our findings, we observenthat DDPSK turns out to be less sensitive to the effects of correlatednfading than the other two schemes and that in these conditionsninterleaving may not be beneficial. We then consider the introduction ofntrellis-coded modulation (TCM). The system we advocate as offering thenbest tradeoff between performance and complexity with the channel modelnassumed here includes double-differential encoding, differentialndetection, an open-loop Doppler phase tracking circuit, and differentialndecoding in addition to a simple TCM scheme