aLS-Coop-Loc: cooperative combined localization and time-synchronization in underwater acoustic networks

Traditionally, underwater localization and time-synchronization are performed separately. This, however, requires two-way ranging between nodes to determine propagation delays resulting in high power consumption and communication overhead. One-way ranging can be used by using a combined time-synchronization and localization approach. While such an approach exists for non-cooperative networks, to the best of our knowledge no such approach exist for cooperative networks. A cooperative approach has significant benefits in terms of number of reference nodes required, flexibility of reference nodes, and accuracy of localization and time-synchronization. Therefore, in this paper we propose a cooperative combined localization and time-synchronization for underwater acoustic networks. We show our approach requires less communication and improves energy-efficiency of the ranging measurement phase, compared to existing Multi-Dimensional Scaling (MDS) approaches using two-way ranging or prior time-synchronization. Using simulation we evaluate the localization and time-synchronization accuracy of our approach and compare it with existing MDS approaches and a non-cooperative approach. Simulations shows that our cooperative approach outperforms non-cooperative approaches in terms of accuracy of localization and time-synchronization and is able to perform localization with fewer reference nodes. We also show that our approach outperforms MDS with prior time-synchronization in terms of accuracy.