Channel Estimation and Space-Time Decoding under MIMO System

Recursive expectation-maximization (EM) algorithm along with stochastic approximation is employed in this paper to estimate unknown time-invariant/variant parameters. In addition, we modify the conventional Viterbi algorithm used in space-time encoder under the MIMO system, and give the recursive metric equation. The modified Viterbi algorithm can be used in the receiver when the MIMO channel information has been estimated. Compared with the conventional decoding algorithm, the improved algorithm can be used in the every receiver respectively. It is shown that the improved algorithm is also an optimal algorithm, however, its metric convergence speed is faster than the standard Viterbi algorithm.