Performance Analysis Of Kalman Filtering Based IEEE1588PTP In Multi-hop WSNs

Recent advances in Internet of Things (IoT) have led to active research in Wireless Sensor Networks (WSNs). As emerging distributed networks, WSNs have advantages in self-organizing, deployment flexibility and low cost. However, its reliability and stability are relatively low. The time synchronization mechanism is the key technology to enhance the reliability and stability of WSNs. However, the conflicts between energy and complexity in traditional protocols such as Network Time Protocol (NTP) and Global Position System (GPS), prohibiting their use in WSNs. Developing a new high-precision time synchronization protocol for WSNs is imperative. IEEE1588Precision Time Synchronization Protocol (PTP) can provide the precision of time synchronization in microsecond under certain conditions, much higher than NTP. Meanwhile, compared with other protocols, such as Flooding Time Synchronization Protocol for Sensor Networks (FTSP) and Timing-sync Protocol for Sensor Networks (TPSN), IEEE1588PTP is more suitable for WSNs devices, which are limited in battery energy and communication bandwidth. However, IEEE1588PTP was originally designed for wired Ethernet, it requires symmetric communication paths and accurate time stamping, how to apply it in multi-hop WSNs and achieve high-precision time synchronization are still inconclusive.In accordance to the high accuracy and low power consumption requirements, the research in this thesis proposes a solution of employing Kalman Filter based IEEE1588PTP in multi-hop WSNs. and confirms its feasibility through the simulation process. The main contributions of this thesis are as follows:1. This thesis builds the mathematical model for WSNs node’s clock, due to the analysis of the node’s hardware features.2. On the analysis of the synchronization packet exchange process, a mathematical model is developed to describe the clock synchronization process of the IEEE1588PTP. A state space model is developed on the MATLAB/SIMULINK simulation platform to simulate the synchronization process. The simulation results show that IEEE1588PTP is good suitable for multi-hop WSNs, for it’s high time synchronization precision.3. Based on above mentioned works and the analysis of the Kalman Filter work principle, this thesis employs the Kalman Filter to optimize the time synchronization of IEEE1588PTP in WSNs. A state space model is developed on the MATLAB/SIMULINK simulation platform to simulate the synchronization process. The simulation results show that Kalman Filter is able to upgrade the time synchronization performance of IEEE1588PTP. Thus, Kalman Filter can reduce the synchronization noise and restrain errors accumulation effectively. While keeping high synchronization accuracy, the scheme in this thesis is suitable for large scale multi-hop WSNs.