Novel receiver structures for systems using differential detection

Novel receiver structures are introduced which improve the bit error rate performance of differentially detected MSK and QPSK systems. These new receiver structures are based on 1) combining with feedback, 2) a simple Viterbi decoder which uses one- and two-bit detector outputs for maximum-likelihood sequence estimation, and 3) using the correlation of noise for the partial removal of its effect prior to decision. The new receiver structures presented are useful in mobile radio and mobile satellite communications where power efficiency, synchronization, and implementation complexity are of primary concern.