Robust Two-Tier Beamforming for Distributed Signal Sensing

Collaboratively fusing signals received by multiple unmanned aerial vehicles (UAVs) can significantly enhance the sensing performance of UAVs-based signal sensing systems. Due to various practical uncertainties in a multi-UAV system, robust beamforming becomes crucial to realizing such performance gains. In this paper, we first demonstrate that under ideal condition, the optimal distributed beamforming can be equivalently achieved through a two-tier beamforming scheme, where the beamforming vectors of the UAVs and the coefficient vector of the fusion center are optimized separately. Building on this insight, we further investigate the impact of various inherent sources of uncertainty and subsequently develop a robust distributed two-tier beamforming scheme against these uncertainties. Finally, extensive simulations are conducted to show the efficacy of the proposed robust two-tier beamforming scheme, verifying its enhanced sensing capability and robustness.