A new reduced-complexity algorithm for multiple-symbol differential detection of m-ary DDPSK

Although multiple-symbol differential detection (MSDD) of double differential phase-shift keying (DDPSK) provides much better error performance than conventional double differential detection, its complexity is much higher. In this paper, a fast algorithm for MSDD is presented, which reduces the number of trellis paths searched by using a subset search concept. It is proved that its performance is identical to that of the original receiver, while its complexity is only proportional to the (N-1)-th power of 2. By combining it with Viterbi algorithm, a new reduced-complexity algorithm is proposed. Computer simulations demonstrate that the performance of the proposed reduced-complexity receiver can reach the lower bound on the error probability of MSDD with very lower complexity, especially for M is very large.