Differential space-time multi-block decoding

In this paper, we consider the maximum-likelihood multi-block decoding in differential space-time block coding systems. Since the computational complexity of the maximum-likelihood multi-block detector increases exponentially as a function of the number of signal blocks used in the decoding, a trellis-based Viterbi algorithm is proposed to implement multi-block space-time decoding without an increase in the computational complexity in each new branch-metric evaluation stage. It is demonstrated that by increasing the number of blocks, one can more efficiently utilize the differential coding relationship in the decoding process. A forgetting factor is further introduced into the maximum-likelihood decoding and the corresponding branch-metric is derived. Numerical results are presented to demonstrate the effects of fading rate, the value of the forgetting factor, and the number of comparative paths on the performance of the proposed approaches.