Advantages of Multiple -Estimation in the Frequency- Selective Block Fading MIMO Environments

The performance of the multiple-estimation (ME) is examined in multiple-input multiple-output (MIMO) frequency-selective fading channels. The least squares (LS) technique, the shifted scaled least squares (SSLS) estimator, and the minimum mean square error (MMSE) estimator were probed in this paper. In the uniform and non-uniform power allocation, the closed form equations were obtained for total mean square error (TMSE) of the estimators. Analytical and numerical results showed that the LS estimator has lower error in the case of ME than single-estimation (SE). Moreover, it was seen that the performance of SSLS and MMSE channel estimators in the ME case is better than SE particularly at high signal to noise ratios (SNRs). It was shown that for small numbers of sub-blocks used for channel estimation, the SSLS and MMSE channel estimators are better than LS. However for large numbers of sub-blocks, inversely, the LS channel estimator is better than SSLS and MMSE. The un-equal power allocation was also examined analytically and numerically. Simulation results showed that exponential power allocation is proper for SSLS channel estimator in ME case.