MAC scheduling for high throughput underwater acoustic networks

Underwater acoustic networks (UWANs) have emerged as the primary tool to monitor and act upon the well-being of marine environment. However, the significantly slower propagation speed of acoustic signals, in contrast to RF signals, introduces the spatio-temporal uncertainty, which makes existing medium access control (MAC) solutions for terrestrial RF wireless networks unsuitable for UWANs. In this paper, we investigate transmission scheduling for time-based MAC protocols and design scheduling algorithms that take advantage of the long propagation delay of acoustic signals to facilitate concurrent transmissions and receptions of acoustic communications. Specifically, we specify the constraints that MAC protocols need to satisfy to avoid conflicts and model these constrains into a Mixed Integer Linear Programming model. We also design heuristics that compute conflict-free transmission schedules, and demonstrate via simulation that the heuristics significantly improve network throughput.