Inter-beam Interference Reduction in Hybrid mmW Beamforming Transceivers

Practical radio frequency beamforming can suffer from high sidelobe levels which cause inter-beam interference (IBI) in multibeam transceivers. IBI can be reduced by shaping the amplitude and phase excitation over the individual antenna elements. However, such methods do not exploit the available power efficiently in practical arrays, where each antenna is driven with a dedicated power amplifier. In this paper, we show a simplified approach for hybrid beam synthesis in subarray-based beamforming architecture and propose a two-stage beamforming method for cancelling the IBI. The proposed technique cancels the interference between the subarrays while it maximizes the effective isotropic radiated powers in the desired directions. Simulation show typically over 40 dB IBI rejection for randomly spread beams and more than 4 dB improvement for radiated power compared to amplitude tapering.