Alamouti-OSTBC Wireless Cooperative Networks With Mobile Nodes and Imperfect CSI Estimation

This paper is concerned with investigating the impact of both nodes mobility and imperfect channel-state-information (CSI) estimation on the symbol-error-probability (SEP) performance of a multiple-relay amplify-and-forward cooperative diversity system employing Alamouti-type orthogonal-space-time-block-code transmission at the source and classical Alamouti's space-time-decoder (ALD) at the destination. Due to nodes mobility, the system's links are characterized by time-selective fading channels, which are modeled by the first-order-autoregressive (AR1) process, and due to imperfect CSI estimation, the estimated channel gains are assumed to be corrupted by Gaussian errors. For such a system model, an approach is proposed to derive a tight approximate expression for the system's conditional SEP. This approach is based on utilizing the AR1 model to derive exact expressions for the signal-to-interference-plus-noise ratios of the ALD decoder's decision variables, and on benefiting from the central limit theorem to approximate some of the non-Gaussian interference and noise terms. The obtained conditional SEP expression is function of both the fading channel correlation parameters and the estimation error variances, and thus, it is valid for mobile as well as static nodes for imperfect as well as perfect CSI estimation processes. The system's average SEP is evaluated semianalytically using the obtained conditional SEP expression. Numerical results along with Monte Carlo link-level simulations are provided to validate the accuracy of the presented analyses and to demonstrate the system performance under several realistic scenarios.