Pilot Design for MIMO OFDM Channel Estimation regard to Guard Band

In this paper, the problem of placing training sequence for multiple-input multiple-output/orthogonal frequency division multiplexing (MIMO/OFDM) systems in the presence of the guard band is considered and a least square (LS) channel estimation is discussed. First, the minimum mean square error (MSE) of the LS channel estimation is computed and then optimal pilot placement which can achieve the minimum MSE with guard band is derived. We propose pilot placements which are not placed in the guard band and minimize the MSE. We compare our scheme with comb pilots. In contrast with equal-power and equal-distance pilots, this design has better performance and satisfies the minimum MSE. Simulation results demonstrate effectiveness of our method.