Robust Multi-Beam Multiplexing Design Based on a Hybrid Beamforming Structure With Nearly Equal Magnitude Analogue Coefficients

One novel design considering two practical application constraints based on the interleaved subarray architecture is proposed to achieve multi-beam multiplexing for arbitrary directions to serve corresponding users. One is an equal magnitude constraint imposed on the analogue coefficients so that beamforming can be achieved by pure phase shifters after the normalisation of magnitudes; the other one is a robust constraint against steering vector errors. Designed examples are provided to verify the effectiveness of the proposed method.