Reflective Sensing Assisted Communication for DAS: Hybrid Beam Alignment and Power Trade-Off

Passive distributed antenna systems (DAS) are widely used for indoor mobile communication quality enhancement and the market space continues to rise. However, in the beamforming process, the passive nature of DAS causes repeated beam scanning and beam correlation issues. This paper proposes an environment-sensing hybrid beamforming method for passive DAS, by which multi-distributed antennas use sensed environment information while considering beam correlation for hybrid beamforming design to improve communication performance. As the initial study, a DAS-oriented method based on compressed sensing for extracting environmental information from superimposed signals is proposed to achieve short-time and high-precision sensing. The flexible design of the hybrid beam transmit path based on the reflected environmental information considering antenna correlation improves the communication rate and bypasses the obstacles. In addition, a dynamic adjustment mechanism for power trade-off between sensing and communication is analyzed to achieve reasonable power allocation, which optimizes the performance of the whole system. Finally, simulation results validate the effectiveness of our proposed method to improve the communication performance while maintaining the sensing accuracy significantly.