Time Reversal Based MAC for Multi-Hop Underwater Acoustic Networks

Abstract

Constrained-energy underwater acoustic nodes are typically connected via a multi-hop underwater acoustic network (MHUAN) to cover a broad marine region. Recently, protocols for efficiently connecting such nodes have received considerable attention. In this paper, we show that the time reversal (TR) process plays an important role in the medium access control (MAC) because of its physical capability to exploit the multi-path energy from the richly scattering underwater environment, as well as to focus the signal energy in both spatial and temporal domains. In MHUANs, with severe multi-path propagation at the physical layer, the active TR process spatially focuses the signals to the location of the intended receiver; this significantly diminishes the interference among parallel links. We propose an active TR-based MAC protocol for MHUANs, with the aim of minimizing collision and maximizing channel utilization simultaneously. Furthermore, by considering the impact of the cross-correlation between different links on the TR-based medium access, we derive the threshold of the link cross-correlation to resolve collision caused by the high cross-correlation between realistic links. We perform simulations using the OPNET and BELLHOP environments, and show that the proposed TR-based MAC results in significantly improved throughput, decreased delay, and reduced data drop ratio in MHUANs.

Channel Modeling for Underwater Acoustic Network Simulation

“…• Limited to the custom UnetStack software architecture • Custom channel model is more difficult to implement than in DESERT/SUNSET layer that is more realistic than a widely used analytical transmission loss model [16]. Zhao et al [37] develop an OPNETbased "BELLHOP-in-the-loop" network simulator and use it to design and evaluate the Time Reversal Based MAC protocol in [38] -a combined PHY and MAC layer solution that relies on the nodes' knowledge of the channel impulse response to precode their transmissions. Parrish et al [39] incorporate sound speed profile (SSP) data measured in the sea trials into BELLHOP simulations to analyze the performance of a UAN using Frequency-Hopped Frequency Shift Keying (FH-FSK) and ALOHA with Random Backoff under realistic channel conditions.…”

ACOA-AFSA Fusion Dynamic Coded Cooperation Routing for Different Scale Multi-Hop Underwater Acoustic Sensor Networks

“…Underwater acoustic communication and networking technology can be flexibly applied to different scenarios, such as different coverage distances, water depths, network structures, and etc. It can be widely used in practical observations in the ocean to realize information interaction between multiple observation devices in different spatial locations [1]. In recent years, underwater acoustic communication and networking technology has become a research hotspot in the marine field [24,25].…”

Channel Modeling for Underwater Acoustic Network Simulation

“…For example, Yildiz et al [26] propose a framework for jointly optimizing the packet size and transmit power in UANs and use BELLHOP to simulate a PHY layer that is more realistic than a widely used analytical transmission loss model [16]. Zhao et al [27] develop an OPNET-based "BELLHOP-in-the-loop" network simulator and use it to design and evaluate the Time Reversal Based MAC protocol in [28] -a combined PHY and MAC layer solution that relies on the nodes' knowledge of the channel impulse response to precode their transmissions. Parrish et al [29] incorporate sound speed profile (SSP) data measured in the sea trials into BELLHOP simulations to analyze the performance of a UAN using Frequency-Hopped Frequency Shift Keying (FH-FSK) and ALOHA with Random Backoff under realistic channel conditions.…”