Optimum Power Allocation for Maximum-Likelihood Channel Estimation in Space-Time Coded MIMO Systems

This paper presents an optimum power allocation strategy for the maximum likelihood based channel estimation in the space-time coded multiple-input multiple-output systems employing a data-bearing approach for pilot-embedding. The corresponding channel estimation error, the Chernoff´s upper bound on the detection error probability, and a lower bound on channel capacity of such systems are analyzed. Based on such analysis, the relationship between these two bounds are revealed, then a unified optimum power allocation scheme is proposed based on jointly optimizing both bounds subject to an acceptable channel estimation error. Simulation results indicate that the proposed power allocation scheme yields a better performance in terms of the error probability, whereas the equal power allocation scheme can be reasonably used as a suboptimum approach with an acceptable performance degradation. Furthermore, the unequal power allocation with more power constantly allocated to the data part yields a much better performance than the one with more power constantly allocated to the pilot part