A study on turbo coding systems with /spl pi//4 shifted DQPSK modulation

In this paper some methods of using turbo coding in conjunction with /spl pi//4 shifted differential quadrature phase shift keying (/spl pi//4 shifted DQPSK) modulation are proposed. The models used in the simulation of the running turbo coded system and their BER performances are presented for each case. The turbo coding rate was R=1/3 and R=1/2. The MAP algorithm, 12 iterations were used. A log likelihood ratio (LLR) stop criterion was selected The interleaving length was N=1784 bits. The performances were obtained for AWGN and for flat Rayleigh fading channels.