We use network tools NS-2 to evaluate our approach and compare it with PBS and TPSN, which are two existing time synchronization protocols. Thus, the accuracy of our approach becomes higher than PBS and the energy consumption is similar to PBS.
#SPANNING SYNC MAC#
The timestamp of Mac layer is applied in our approach.
The method of two points least squares is used to calculate the clock drift and offset. It does not increase the number of broadcast messages compared with the original PBS, but changes the format of messages. In this paper, we present a Mac-Time-Stamping-based High-accuracy Time Synchronization with 2 points Least Squares for Wireless Sensor Networks called PBS-2LS. In PBS, some nodes only need to listen the overhead messages instead of broadcasting any messages. Pairwise Broadcast clock Synchronization (PBS) was proposed to greatly reduce energy consumption, especially in densely connected network. The accuracy and energy consumption are main factors to evaluate a time synchronization protocol. Time synchronization is essential for applications in Wireless Sensor Networks (WSNs). Simulations show the superiority of OTSP, and that it outperforms TPSN, and RTSP in terms of synchronisation tree depth, energy efficiency and synchronisation error, and TSST only in term of synchronisation error. This process continues until the leaf nodes are synchronised. Coordinators will then propagate the synchronisation message and will also select another set of coordinators to continue the synchronisation process. After that, the centre node will synchronise its direct neighbours and will select among them a subset of coordinators nodes. Using neighbours’ tables, the centre node is the localised and a hierarchical tree is created. The purpose of neighbour discovery phase is to provide neighbours’ tables to the base station (BS). The proposed OTSP works in three phases: neighbour discovery phase (NDP), centre node-localisation phase, and synchronisation phase. In this work, we propose a new time synchronisation protocol for wireless sensor networks (WSNs), called OTSP for “Optimised Time Synchronisation Protocol”.
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