Topology Optimization of Long-Thin Sensor Networks in Under-Ice Environments

Long-thin network topologies are useful in monitoring tunnels and bridges because of their linear structure. In this paper, we apply the long-thin concept to under-ice acoustic sensor networks in the Arctic Ocean. We develop an acoustic wave propagation model for the under-ice environments using the ray-tracing method. Specifically, we derive the reflection coefficients of plane acoustic waves penetrating from seawater to ice in a ray-based model. The impulse responses and transmission loss, including their dependencies on the communication range, are examined in the under-ice environment. Furthermore, to maximize the operational lifetime of the under-ice long-thin network, we optimize the network topology by integrating Monte Carlo simulations with a differential evolution technique. The optimization results are presented for long-thin sensor network scenarios under the Arctic sea ice. Computer simulations show that by optimizing the sensor locations in the long-thin topology, one can take advantage of the sound convergent and divergent effects of the under-ice acoustic channel. As a result, the energy consumption of the long-thin sensor network can be significantly reduced so that its operational lifetime can be extended in the Arctic environment.