Interference reduction between SDD linear array antennas using end-fire arrangement

This paper proposes a self-interference reduction method exploiting antenna arrangement and beamforming for space division duplex (SDD) relay station. When transmitting (Tx) and receiving (Rx) linear array antennas are placed in end-fire arrangement, spatial correlation between Tx and Rx increases. This causes rank degeneracy of the channel matrix between Tx and Rx. With this channel, almost all the self-interference inside SDD relay station can be reduced by forming beam to the nearly-zero space at Tx. Simulation results show that there is the optimum element spacing of linear array, and that the proposed method greatly improves channel capacity of SDD relay system, which is higher than that of the time division duplex (TDD) system.