A Time Synchronization Scheme based on RPL for 6LoWPAN Networks

Under the promotion of the Internet of Things (IoT), the IPv6 over Low Power Wireless Personal Area Network (6LoWPAN) technology has been rapidly promoted and applied. Time synchronization is a key supporting technology for maintaining synchrony among nodes in Wireless Sensor Networks (WSNs), and how to maintain the synchronization accuracy and lower the energy consumption have always been a challenge to researchers. With the purpose of realizing time synchronization in 6LoWPAN to reduce energy consumption, synchronization accuracy, synchronization cost, and practical deployment issues need to be considered. Therefore, this paper studied the time synchronization scheme, including the improvement of RPL Control Message and an improved one-way synchronization algorithm based on the IPv6 Routing Protocol for Low-Power and Lossy Networks (RPL). To certify its efficiency, the clock frequency skew estimation of the linear model and the clock frequency skew Maximum Likelihood Estimation (MLE) of the nonlinear model are also derived, and the simulation results prove that the parameter estimation method is efficient.