Incorporating Realistic Acoustic Propagation Models in Simulation of Underwater Acoustic Networks: A Statistical Approach

Abstract

"The development of protocols to advance the state of the art in Underwater Acoustic Networks (UANs) relies on the use of computer simulations to analyze protocol performance. It is typical for designers to abstract away much of the detail of the physical environment in order to simplify the development of the simulation and ensure the simulation runtime performance is reasonable. The validity of the simulation results becomes questionable. There are, though, very high fidelity models developed by acoustic engineers and physicists for predicting acoustic propagation characteristics. In addition to these models, empirical data collections have been generated for many geographic regions of interest to UAN planners. However, incorporating these engineering and physics models or data collections into a network simulation is problematic, as the models are computationally complex and the data sets are not directly usable for acoustic signal propagation characterization. This paper presents a statistical method for developing a computationally efficient and simulation friendly approximation of a physics model of path loss. This method may also be used to adapt empirical data sets for use in network simulation in the same manner. The method was applied to the output of the Monterey-Miami Parabolic Equation model to assess its impact on the runtime performance of an OPNET-based simulation. Results of that simulation are compared to results from a previous OPNET simulation that simply used distance to determine reception. The simulation results confirm the incorporation of the MMPE approximation does not noticeably impact the runtime performance of the simulation. Anecdotally, the simulation confirms earlier results indicating that contention based access controls without collision avoidance techniques may outperform the typical access technique adapted from wireless radio network and employing collision avoidance, even in the high load regime, contrary to conventional wisdom."