Assessing Data Freshness Performance in Secure Relay-Oriented Low-Altitude Wireless Networks

Abstract

Low-altitude wireless networks (LAWNs) provide a promising solution for relay-assisted communications and flexible wireless coverage enhancement. In relay-oriented LAWNs, data freshness is affected by relay transmission capability, energy limitation, and aerial eavesdropping. To address this issue, this paper investigates the age of information (AoI) performance of a secure relay-oriented LAWN, where a multi-antenna relay UAV assists communication from a base station to a user terminal while harvesting energy, and a malicious UAV attempts to intercept the relayed signal. A secure relay-oriented LAWN model is established by considering amplify-and-forward relaying, imperfect CSI, wireless energy harvesting, and aerial eavesdropping. Based on the secrecy communication process, the secrecy rate and the closed-form average AoI are derived. Simulation results under different relay UAV antenna numbers, transmit powers, and energy harvesting ratios verify the correctness of the analysis. The results show that increasing the relay UAV antenna number or transmit power improves secrecy performance and reduces the average AoI, while the energy harvesting ratio should be properly configured to achieve better data freshness performance.