Robust Beamforming for Multi-Beam ISAC Systems

Integrated sensing and communication (ISAC) has emerged as a key technology for future 6G wireless networks, enabling simultaneous communication and sensing. However, the time-varying directions of sensing beams, especially in wide field-of-view scenarios, can lead to significant cross-interference with communication beams, particularly in non-line-of-sight conditions. To address this issue, this letter proposes a global beamforming optimization algorithm, which minimizes fluctuations in communication received power while maintaining wide sensing coverage. Specifically, we model the problem as a semidefinite programming problem and solve it efficiently using semidefinite relaxation technique. Additionally, we optimize the scanning directions of sensing beams in order to further suppress the cross-interference. Simulation results demonstrate that our proposed methodology could improve communication stability and minimize cross-interference without compromising sensing performance, validating its superiority in enhancing the robustness of multi-beam ISAC systems.