earticle

영어

We propose a simple multi-user beamforming to assist space-division multiple access (SDMA) as well as to mitigate interference from IMT-Advanced base station (BS) to fixed-satellite service (FSS) earth stations (ESs). The BS with multiple antennas forms multiple beams that steer nulls, i.e., emit quite low power (interference) to the directions of the ESs. The beamforming vectors are designed by inverting the array steering vectors corresponding to the direction angles of the ESs as well as random direction angles of the main beam lobes. In order to show the merits of the proposed method, we model interference power at the ES and compute the minimum separation distances between the BS and the ESs required for their coexistence. Even for the case of the multiple ESs, the proposed method can reduce the minimum separation distance by up to 92 percent without any expense of additional radio spectrum resources.