Throughput per Pass for Data Aggregation from a Wireless Sensor Network via a UAV

Data retrieval from a sensor field by means of unmanned aerial vehicle (UAV) has increasing interests for both commercial, military, and homeland security applications. In these situations, the design of energy-efficient communication links between sensor field and UAV is crucial, owing to battery powered sensor nodes. We propose an energy-efficient cooperative transmission scheme for wireless sensor networks (WSNs) where data gathered by sensor nodes need to be collected into a far receiver. In particular, we consider a network composed of sensor nodes that share a common message that has to be transmitted asynchronously toward a fusion center onboard a UAV. We consider that the communication channels between the nodes and the fusion center are subject to fading and noise. Due to the far communication distance and energy constraint at each node, the fusion center must be able to reliably receive the weak and noisy signals. In our approach the fusion center consists of a Rake receiver capable of collecting multiple replicas of the same information from the nodes in the WSN. The performance of the proposed cooperative diversity scheme is then studied in terms of throughput, bit error probability, and energy efficiency. The results obtained show that, as the number of nodes increases, the proposed approach increases network lifetime, communication reliability, and throughput.