Multi-Sensor Data Synchronization using Mobile Phones

Abstract: Body sensor networking is a rapidly growing technology. Today wearable sensors are used to measure and monitor e.g. pulse, temperature, skin conductance, heart activity, and movement (through GPS or inertial measurement units). Mobile phones can act as coordinating nodes in wireless personal area networks used in home automation, healthcare, sport and wellness e.g. to measure pulse and distance. Integration of data from multiple sources sensors (data fusion) means that data from each sensor node needs to be associated with data from other sensor nodes sampled at approximately the same time. Accurate methods for time synchronization are therefore a necessary prerequisite for reliable data fusion.This thesis studies time synchronization problems in Bluetooth piconets between multiple wireless sensor nodes connected to a mobile phone that acts as coordinating node. Three different algorithms to enable correct data fusion have been developed, implemented and evaluated. The first is a single clock solution that synchronizes multiple wireless sensor nodes based solely on the mobile phone’s clock. The other two algorithms synchronize the clocks in sensor nodes to the clock in the coordinating node.