Robust Beamforming for Low-Altitude Wireless Networks With Outage Guarantee

Abstract

As a pivotal direction for future 6G systems, low-altitude wireless networks present a promising application ground for integrated sensing and communication (ISAC) technologies. In a typical use case where a base station performs sensing on unmanned aerial vehicles (UAVs), the system encounters new challenges including highly dynamic targets, rapidly time-varying channels, multipath effects, and complex interference. These demand integrated solutions that jointly support high-precision sensing and highly reliable communication. To address these challenges, this paper adopts the Cramér-Rao Bound (CRB) as the estimation performance metric to introduce an estimation-performance-oriented robust beamforming method, formulating an optimization problem that simultaneously guarantees the CRB-based estimation performance and outage-constrained communication reliability. For the single-user scenario, the optimization problem is reformulated into Semi-Definite Programming (SDP). In the multi-user case, probabilistic SINR constraints are relaxed via Bernstein-type inequalities, ensuring computational tractability while guaranteeing outage performance across multiple users. Simulation results show that the proposed method effectively balances the sensing-communication trade-off, showing notable performance gains, particularly in enhancing target estimation accuracy under low SINR conditions.