Optimal pilot design for space-time coded multi-user MIMO OFDM/SDMA systems

In this paper, we propose an optimal pilot design scheme for multi-user Multiple-Input Multiple-Output (MIMO) Orthogonal Frequency Division Multiplexing/Space Division Multiple Access (OFDM/SDMA) systems. We derive the optimal pilot design criterion with regard to the computational complexity and the Mean Square Error (MSE) of the Least Square (LS) estimator. Furthermore, we propose a binary-tree based search scheme in order to find the optimal position for placement the Space-Time Coded pilot symbols. Through our analysis and simulations, it is shown that the pilot design complied with the our proposed placement criteria could obtain the lowest computational complexity and the optimum estimate performance.