Varying the Beamwidth of Hybrid Beamforming for mmWave Communications

Availability of large array usage in millimeter wave communications gives the opportunity to create narrow beams that yield to high antenna gains. However, in some cases, wider beams are of interest in order to increase the coverage area or reduce the outages caused by the channel variations. To address this need, beam broadening approaches with no increase in the hardware complexity have been described without studying the implementation difficulties. This paper proposes a simplified broadening model while adopting a strategy in which neighbor beams are concatenated to create a wider beam dividing the antenna into subarrays. The beamwidth and power loss analysis along with the beam broadening bounds in the design parameters are expressed in detail. Next, introduced broadening model is integrated to the hybrid beamforming system without changing its hardware structure. Simulation results that verify the analytical expressions for both broadening system and its hybrid beamforming implementation are provided.