Digital Signal Design Concepts for a Time-Varying Rician Channel

The problem of transmitting digital data reliably over a Rician channel, which is used to model the aircraft-satellite link, is treated by an integrated coding and modulation design approach. The results presented enable one to show that it is quite possible to achieve robust signaling which is fairly insensitive to the channel´s surface scatter parameters, such as scatter path energy and Doppler spreads. These results illustrate that the scatter energy need not limit the effectiveness of transmitting digital data and, in fact, can improve the performance when operating in the region of low direct path SNR´s. These concepts are exemplified by performance curves for frequencyshift keying (FSK) and differential phase-shift keying (DPSK) modulation formats combined with efficient channel measurement decoding algorithms. In addition, general analytical results for evaluating the bit error probability for binary and channel measurement decoders are presented.