Low-AoI Data Collection in UAV-Aided Wireless-Powered IoT Based on Aerial Collaborative Relay

In existing Internet-of-Things (IoT) applications, sensor nodes (SNs) are often deployed in wilderness areas to collect environmental data. Due to the lack of infrastructure in these remote areas, unmanned aerial vehicles (UAVs) are dispatched to transfer energy to SNs and collect the data generated by SNs. For areas far from the base station (BS), UAVs need to fly long distances to traverse SNs in those areas and return to the BS. This significantly increases the data transmission delay of the system. How to reduce data transmission delay in wireless-powered IoT is a challenging problem. Therefore, in this study, we propose a data collection mechanism by establishing UAV-to-UAV data relay transmission to reduce data transmission delay. To realize relay transmission between UAVs, we propose a seamless relay-based UAV collaborative scheduling (SRCS) scheme. In this scheme, we first select hover points to ensure that the charging range of UAVs covers all SNs. Next, we divide the task regions and plan paths within each region for UAVs. Then, we establish relay pairing relationships between UAVs to determine which UAVs relay data to others and jointly optimize relay points and hovering time to achieve seamless relay between UAVs. Finally, we achieve energy balance among SNs through reselecting cluster head (CH) nodes and among UAVs through exchanging task regions. Extensive experimental results have shown that the proposed data collection scheme can effectively extend network lifetime and significantly reduce data transmission delay compared with the existing data collection schemes.