MM-Sync: A Mobility Built-In Model Based Time Synchronization Approach for Underwater Sensor Networks

We study the problem of distributed time synchronization of underwater sensor networks, which is a quite challenging issue under such a dynamic scenario. Due to the high and varying transmission delay caused by the mobile network nodes, the existing works cannot achieve a desirable accuracy of synchronization. To overcome this problem, a mobility built-in model is firstly explored for the time synchronization in consideration of the effect of mobility and transmission delay. Then, a time synchronization equation is formulated according to the proposed model. Based on the equation, a mobility built-in model based time synchronization algorithm, namely MM-sync, is designed. The experiment results show that MM-sync cannot only reduce the consumption of energy, but also achieve a higher accuracy than state-of-art solutions.

1. Introduction

Deploying underwater sensor networks (UWSNs) for various applications, e.g., underwater resource monitoring, has attracted increasing attentions. In the UWSNs, the sensor nodes with a low energy consumption and a short communication distance can be deployed to a specific underwater area, in which the technologies of the underwater acoustic communication and the self-organizing network are employed to establish the UWSN automatically [1]. As a new type of self-organizing networks, time synchronization is nontrivial for task assignment, node scheduling, security authentication, etc [2], , , , , , [8]. Although there exist some developed time synchronization algorithms, such as Tiny-Sync, Mini-Sync, LS (Light weight Tree-Based Synchronization), etc., they can only be suitable for the radio wave communications rather than the UWSN scenarios [9] due to the undesirable time synchronization accuracy caused by the long propagation delay as well as the node mobility.