Maximum lifetime routing in underwater sensor networks using mobile sink for delay-tolerant applications

Underwater Wireless Sensor Networks (UWSNs) enable a wide range of aquatic applications. But the underlying physical layer technology makes the development of efficient data collection and routing schemes for UWSNs a challenging issue. It is important for the UWSNs to have maximum possible lifetime, because the recharging or replacement of sensor nodes after deployment is almost impossible. We propose a mobile sink (MS) based model for maximizing network lifetime, considering energy-constrained sensor nodes, location-constrained data collection points, and delay-tolerant applications. Maximum lifetime is achieved by deferring the transmission of data until the MS is at the most favourable location for data transfer, and by solving optimally two joint problems of scheduling and routing. To reduce the complexity of solving the optimization scheme, we propose a simplified model for lifetime maximization. The proposed model is compared with other schemes available in the literature. Keeping the analytical solution as a benchmark, a distributed version of the proposed maximum lifetime routing scheme is implemented in the network simulation platform OMNET++, considering all the peculiarities of the underlying physical layer technology. Both analytical and simulation results show that the proposed model exhibits superior lifetime performance at the cost of increased data collection latency. The comparison of the proposed scheme with other schemes permits us to identify the trade-offs in MS-based lifetime maximization scheme and to select the appropriate model according to application requirements and network constraints.