Low-complexity time synchronisation for 3-dimensional underwater communications environment using estimated instantaneous node velocity

Underwater time synchronisation is required to use the latest communication technologies. Because propagation time should be estimated to improve time synchronisation accuracy, node mobility is an important factor. In the subaqueous environment, furthermore, it is impossible to exclude the influence of the node movement occurred by environmental factors and underwater nodes could have self-mobility. Conventional time synchronisations have considered node mobility but have an unrealistic assumption of node movement and high computational complexity. In this paper, however, our novel method, Low-complexity time synchronisation for 3-dimensional underwater communications environment using estimated instantaneous node velocity based (V-Sync), shows high accuracy with low complexity and short processing latency. In this paper, it is supposed that mobile nodes could know their instantaneous speeds when they receive the synchronising messages. Time synchronisation errors, skew and offset, are estimated by the instantaneous speeds. The performance and analysis of V-Sync in the underwater mobile environment is demonstrated by simulation results.