Enhancing Physical-Layer Key Generation via Beam Alignment Adaptation in Beam Transmissions

In the context of beam-assisted mobile secrecy transmissions, the beam misalignment due to node movement leads to degradations in physical-layer key generation rate (KGR) between legitimate parties. To address this issue, we propose to optimize the duration of beam alignment to maximize KGR. By establishing the mathematical relationship between beam alignment duration and the KGR metric, we aim to strike the balance between beam misalignment induced by node mobility and the KGR inefficiency arising from frequent beam updates. Through this optimization, the negative impact of beam misalignment is effectively mitigated and the KGR performance is largely improved. Simulation results indicate that our proposed scheme improves KGR compared to the existing schemes in both line-of-sight and non-line-of-sight scenarios.