An Enhanced EM/SAGE-Based H-Infinity Channel Estimator for MIMO-OFDM Systems
This paper proposes a low-complexity and robust H-infinity channel estimator for Multiple-Input Multiple-Output (MIMO) Orthogonal Frequency Division Multiplexing (OFDM) systems. To lessen the complexity, the Expectation Maximization (EM) and Space-Alternating Generalized EM (SAGE) algorithms are adopted respectively. To treat with the effect of Non-Gaussian Noise (NGN) channels, an Equivalent Signal Model (ESM) is used to enhance the robust of the EM-type H-infinity estimator. Furthermore, joint estimation using Phase Shifted Orthogonal (PSO) pilot sequences is applied for improving the estimation and the requirement for pilot. Simulation results show that the H-infinity estimator has almost the same Mean Square Error (MSE) as Maximum A Posteriori (MAP) estimator. By using the ESM, the robustness of EM-type based H-infinity estimator is enhanced against NGN channels.