Abstract
The locations of the pilot subcarriers can’t be equally spaced because the practical system utilize the virtual subcarriers. Thus, the minimum mean square error (MSE) performance of the maximum likelihood (ML) estimate is difficult to be obtained. Previously tried to search the locations of the pilot subcarriers when the virtual subcarriers are used. However, it is difficult to apply to the case of that the number of total pilot subcarriers is 512 or 1024 in the practical MIMO OFDM system of the IEEE 802.16e standards. For the case of the practical system such as the IEEE 802.16e standards, the locations of the pilot subcarriers will be found with proposed methods. One is a modified scheme, the others are new schemes for the practical MIMO OFDM system. Proposed methods result in the MSE performance of the channel estimate lower than 0:5dB degradation from the minimum MSE performance of the ML channel estimate on the time domain in the four transmitted antennas. This paper proposes the methods, which can apply to the practical MIMO OFDM system such as the IEEE 802.16e standards and, the obtained locations, and, the power of the pilot subcarriers.