In underwater networks, achieving precise time synchronization is essential for various critical functions, such as localization and channel access. However, synchronization remains a significant challenge due to substantial propagation delays and the mobility of nodes in underwater environments. While existing methods like D-Sync, Mobi-Sync, and MU-Sync have been developed to address these issues in dynamic underwater settings, they primarily depend on estimating the radial velocity using Doppler shift effects. Additionally, these protocols often involve two-way message exchanges, which contribute to increased signaling overhead and response delays. In our previous study, we introduced a novel time synchronization approach based on the geometric shape of movement. This method, which we call Underwater Geometry-Based Synchronization (UWGS), employs a geometric framework to optimally estimate clock skew and offset for an unsynchronized node. Unlike traditional approaches that estimate radial velocity using Doppler shift, UWGS utilizes multiple one-way pulse signals to establish a geometric relationship between node velocity and range, and its preliminary evolution depicted simulated results in ideal conditions. In this paper, we further investigate the functionality of UWGS and compare its performance with existing methods, such as D-Sync, under more challenging and realistic conditions. Specifically, we consider the presence of random Gaussian noise in the motion of a mobile node and a non-ideal, slightly curved trajectory instead of the straight-line motion assumed in previous studies. Furthermore, we examine the impact of packet loss to assess whether UWGS provides improvements in synchronization accuracy and efficiency across a range of realistic underwater environments.
Ghalkhani et al. (Fri,) studied this question.