Multi-level block coded modulations for the Rayleigh fading channel

Block coded 8-phase differentially phase shift keyed (8-DPSK) modulations for the time selective Rayleigh fading channel are presented. These block coded modulations (BCMs) are based on multi-level code constructions and utilize short binary block codes as building blocks. All the block codes presented have a time diversity of at least 2. These codes are suited for communication systems with severe delay constraints such as speech transmission over digital cellular radio links. Block codes of length 4 to 16 symbols and rates of 1-3/4 to 2-9/16 bits/symbol are constructed using low complexity component block codes. The proposed schemes provide 10-14 dB channel SNR (signal-to-noise ratio) gain over uncoded 4-DPSK modulations at a bit error rate of 10^-3. Additional gain is also obtained for a fraction of the data due to the unequal error protection nature of these codes