Coded modulation with time diversity, unequal error protection, and low delay for the Rayleigh fading channel

Block coded 8-DPSK modulations are presented for the time selective Rayleigh fading channel for digital cellular radio. These coded modulations are based on multi-level code constructions and utilize short binary block codes of length 2 to 8 (binary symbols) as building blocks to construct 8-DPSK codes of length 2 to 8 respectively. All the constructed block coded modulations have built in time diversity of at least 2 to combat Rayleigh fading. Unequal error protection is obtained by providing higher time diversity through code selection for the important data and by using a nonuniform signal constellation that provides higher signal constellation Euclidean distance components for the more important data. Low transmission delay is obtained by matching the code rate and interleaver to the channel conditions (Doppler spread). Block coded 8-DPSK symbols with rate 1.5-2.25 information bits per symbol and code length 2 to 8 symbols have been designed and simulated for various values of Doppler spread which shows that gains of more than 15 dB can be obtained at a bit error rate of 10^-3 for a fraction of the data that is deemed to be most important