Eigen-beamspace adaptive antenna for OFDM transmission with zero carriers

OFDM systems are known to outperform single-carrier systems in a multipath environment. However, multipath waves, whose delay times are longer than the guard interval, cause intersymbol interference, because of which the performance of the system degrades. The effectiveness of adaptive arrays in overcoming this problem has been investigated. This paper proposes the use of an adaptive array with eigenvector beams for OFDM transmission with zero carriers. In the proposed method, the eigenvectors are calculated from the zero carriers including the interference wave, and the matrix based on the eigendvectors is used to suppress the undersired waves. Then, maximal-ratio combining is performed in each subcarrier. Simulation results show that the proposed method effectively suppresses undesired waves.