1. A method for Differential Phase Shift Keying (DPSK) demodulation, comprising: receiving symbols from a communication channel; estimating the probability of each received symbol being one of its possible constellation values, evaluating the probability of the phase difference of two adjacent received symbols being one of possible phase differences according to a corresponding DPSK modulation table; evaluating soft bit information represented by the phase difference of two adjacent symbols based on a probability set representing probabilities of the phase difference being one of possible phase differences, or based on a probability set of phase difference being one of some possible phase differences having a probability greater than a selected probability.