Unsynchronized Dual-Hop Scheduling for Practical Data Gathering in Underwater Sensor Networks

In this paper, we propose a centralized dual-hop scheduling approach for efficient and practical data gathering in underwater acoustic sensor networks - Sequential Dual-Hop Transmit Delay Allocation MAC (SDH-TDA-MAC). The practical advantages of this approach include scalability to large networks, little control overhead, no requirement for clock synchronization and low energy consumption and computational complexity. BELLHOP-based simulations reveal that our proposed protocol can achieve full network connectivity with 15 dB lower transmit power, compared with standard single-hop TDA-MAC, while still achieving network throughput in excess of 50% of the theoretical maximum. Furthermore, a comparison with sequential polling show that our proposed protocol can facilitate multiple times faster data gathering by utilizing TDA-MAC for all many-to-one connections at the surface gateway and relay nodes.