Distributed Device Synchronization

Abstract: Generally, synchronization in Wireless Sensor Networks (WSN), allows successful and accurate communication between nodes to occur. Each node in WSN runs independently and have its own clock which can drift from the other device’s clock. Many application in WSN requires a common notion of time between nodes in order to be able to provide a reliable performance and operation. The focus of this research is to study whether a sufficient synchronization accuracy between nodes in WSN using bluetooth mesh communication can be achieved, that would allow us to turn on and off LEDs on distributed devices in such way that we create an LCD-like behavior with 50Hz (20ms) resolution. We use NRF52840-PDK devices in this thesis and for synchronization purpose, we are using FTSP and RBS+FTSP synchronization protocols. The RBS+FTSP protocol is the combination of both RBS and FTSP protocols which have the benefits of both protocols and improves the performance of the synchronization in our use case, this protocol is explained more in detail in later sections (see chapter 2.1.3 ). Based on the results that we have it is possible to achieve low-ms synchronization accuracy using the bluetooth mesh communication technology using FTSP and RBS+FTSP protocols. The synchronization resolution that we achieved using bluetooth mesh technology and our synchronization protocols were below 10ms which are good enough to accomplish the required 50Hz (20ms) resolution of our LCD-like screen with distributed devices. The same method can also be used to perform synchronization between nodes for various other actuation and sensing purposes in wireless sensor networks.