Blind Unique Identification of Alamouti Space-Time Coded Channel Via Signal Design and Transmission Technique

In this paper, we present a simple signal design and transmission technique to uniquely and blindly identify Alamouti space-time coded channels under both noise-free and complex Gaussian noise environments in which $p{\rm th}$-order and $q{\rm th}$-order statistics ($p$ and $q$ are co-prime) of the received signals are available. A closed-form solution to determine the channel coefficients is obtained by exploiting specific properties of the Alamouti space-time code and the linear Diophantine equation theory. When only finite received data are given, we propose using the semi-definite relaxation algorithm to approximate maximum likelihood (ML) detection so that the joint estimation of the channel and symbols can be efficiently implemented. Simulation results show that our signal design and transmission method yields lower mean-square error in the estimation of the channel when compared to other existing methods and that the average symbol error rate approaches that of the coherent detector which needs perfect channel information at the receiver.