System Design Considerations for Undersea Networks: Link and Multiple Access Protocols

Abstract

Abstract-We address several inter-related aspects of underwater network design within the context of a cross-layer approach. We first highlight the impact of key characteristics of the acoustic propagation medium on the choice of link layer parameters; in turn, the consequences of these choices on design of a suitable MAC protocol and its performance are investigated.Specifically, the paper makes contributions on the following fronts: a) Based on accepted acoustic channel models, the pointto-point (link) capacity is numerically calculated, quantifying sensitivities to factors such as the sound speed profile, power spectral density of the (colored) additive background noise and the impact of boundary (surface) conditions for the acoustic channel; b) It provides an analysis of the Micromodem-like linklayer based on FH-FSK modulation; and finally c) it undertakes performance evaluation of a simple MAC protocol based on ALOHA with Random Backoff, that is shown to be particularly suitable for small underwater networks.

Propagation and Scattering Effects in Underwater Acoustic Communication Channels

“…The approximation of the acoustic channel in today's network simulations varies from: signal-to-noise ratio (SNR)-based channel models using empirical equations for transmission loss and noise [36]; empirical transmission loss plus the assumption of Rayleigh signal fading [37]; use of ray tracing to more accurately compute the transmission loss for a given scenario [38]; and use of ray tracing to compute a multipath profile and allow for bit errors due to signal self-interference [39]. More involved channel models and simulation tools, which also allow for Doppler effects, have mostly been developed separately from network studies [19], [26], [29], [40]- [46].…”

Frequency selection of an inductive contactless power transmission system for ocean observing

“…Seafloor observatory networks have been deployed successfully in recent years (Parrish et al, 2008). With the benefit of the seafloor observatory networks, it is possible for more undersea equipment to complete tasks entirely undersea.…”

Scheduling granularity in underwater acoustic networks

“…Devices generate traffic for the sink randomly based on a Poisson process where data packet sizes are fixed during the simulation. Simulation results also compare the scheduling methods to two random access protocols: an ALOHA protocol modified for underwater networks [14] and Tone Lohi [19].…”