A mechanism of topology optimization for underwater acoustic sensor networks based on autonomous underwater vehicles

Ming He,Fangxin Liu,Zhuang Miao,Qiuli Chen,Huan Zhou

doi:10.1177/1550147716686979

Abstract

Limited energy, high mobility, and unsteady acoustic communication links render the underwater acoustic sensor networks subject to performance reduction. To solve this problem, a topology optimization method, also called TO-A algorithm, is developed based on topology reconfiguration. First, the proposed method optimizes the coverage rate of underwater acoustic sensor networks by adjusting the location of sensor nodes through simulating fish behaviors. Second, to optimize the connectivity of underwater acoustic sensor networks, the proposed method, using edge nodes, repairs disconnected positions and eliminates key nodes in underwater acoustic sensor networks. Third, a topology optimization strategy, also called TO-DA algorithm, is developed for Double-autonomous underwater vehicles to improve the robustness and adaptability of the network topology. When the inherent law of underwater acoustic sensor networks topology formation is further found, the method for optimizing network topology is proposed, which based on the triangle principle eliminates those key nodes and can help with the survivability of network regeneration. The method proves reasonable and valid by stimulation and contrast examinations. The comparison of TO-A algorithm and TO-DA algorithm shows that under low energy consumption, TO-A algorithm can keep the network coverage at about 97% for a long time, connectivity rate above 89%, while the TO-DA algorithm can improve the survivability of the network by above 50% at the expense of 8.5% of the network coverage.

Highlights

As adopted in Jafri et al.,[6] the connectivity of Underwater acoustic sensor networks (UASNs) has been optimized from the aspect of protocol design, but there are key nodes in the UASNs, making the invulnerability of network topology unable to be improved (the key node means all single-hop neighbor nodes of this node belong to subsets which do not communicate with each other with the number of subsets at k(k ! 2) and these subsets are connected by this node only)
The reasons why we present the TO-DA algorithm for optimizing the topology of the UASNs are as follows: (1) The underwater acoustic sensor has limited energy and the frequent topology evolution for maintaining the connectivity of the network topology leads to the energy of sensor nodes greatly reduced in complex ocean environment; (2) The shadow zone still exists in the process of mission execution, and the communication signal attenuation among the underwater acoustic sensors or the signal-to-noise ratio (SNR) is large, which cannot maintain stable/effective communication
We propose a topology optimization scheme based on reorganization, namely, TO-A algorithm that maintains connectivity and coverage, and a topology optimization mechanism based on DoubleAUVs, namely, TO-DA algorithm that prolongs the life cycle and connectivity of UASNs

Summary

Introduction

Underwater acoustic sensor networks (UASNs) are capable of underwater environment in real time, accurate and effective monitoring, and can be widely applied to various fields such as underwater military target surveillance,[24] marine data collection, monitoring water quality, seabed mineral resources exploration, and assisted navigation.[1,25,26,27,28,29,30] The quality of communication among the sensor nodes and the reliability of topology of UASNs have been seriously affected due to. Each node can control itself, in accordance with the rules of the algorithm to get the global optimal value It requires the step size of each time node to randomly move a size not exceeding its own perceptual range, so as to ensure that any event during the process of foraging operation is not skipped, and when rear-end collision or clustering occurs, there will not be too crowded among sensor nodes. Broadcast the Request(si, Li, hops) message by the key node, including key node’s ID, location, hops of search, and other information, where hops is the counter for counting the number of hops and the initial value of hops is set by si, the Request(si, Li, hops) message is sent each time, and the hops minus 1, until the hops becomes 0, and the Request(si, Li, hops) message is no longer being delivered

The edge node processes the Request message

The key node processes the Response message

The edge node processes the Take message

Experimental study

Findings

Conclusion