Correlation and Kullback matching approaches: Application to blind channel estimation in OSTBC systems

In many practical parameter estimation problems, the statistical properties of the sources can be exploited to improve the quality of the estimates. In this paper we consider the correlation and Kullback matching criteria (CM and KM respectively), which are applied to the problem of blind channel estimation under orthogonal space-time block coded (OSTBC) transmissions. Specifically, it is shown that the special OSTBC structure provides straightforward closed form solutions, which reduce to the extraction of the principal eigenvector of the observation correlation matrix modified by the code matrices and a set of weighting factors. Additionally, we prove that the KM technique is equivalent to the CM approach for low SNRs, and to the relaxed blind maximum likelihood (ML) decoder for high SNRs. Finally, the performance of the proposed techniques is illustrated by means of several simulation examples.