Aging analysis in large-scale wireless sensor networks

Most research on the lifetime of wireless sensor networks has focused primarily on the energy depletion of the very first node. In this study, we analyze the entire aging process of the sensor network in a periodic data gathering application. In sparse node deployments, it is observed that the existence of multiple alternate paths to a sink leads to a power law relation between connectivity to a sink and hop levels, where the probability of connection to a sink decreases in proportion to the hop level with an exponent, when device failures occur over time. Then, we provide distance-level analysis for the dense deployment case by taking into account the re-construction of a data gathering tree and workload shift caused by the energy depletion of nodes with larger workload. Extensive simulation results obtained with a realistic wireless link model are compared to our analytical results. Finally, we show through an analysis of the aging of first-hop nodes that increasing node density with a fixed radio range does not affect the network disconnection time.