Multi-Beam Multiplexing Design with Phase-Only Excitation Based on Hybrid Beamforming Architectures

Although multi-beam multiplexing can be implemented merely by phase shifters with hybrid beamforming configured by the sub-connected subarray architecture since all the antennas share the same magnitude, they cannot be set to a predetermined value. To tackle this issue, a non-convex constraint to enforce the magnitudes to a fixed value is first introduced in this design and then an iterative method is employed to relax it into a convex one. In doing so, the weighting magnitudes of all antennas can be preset in advance according to given requirements and a more flexible solution with phase-only excitation is obtained for multi-beam multiplexing. Numerical results are presented to verify the effectiveness of the proposed approaches.