A Hybrid Approach for Localisation of Sensor Nodes in Remote Locations

A Wireless Sensor Network (WSN) is a network of sensor nodes using low-power wireless technology to collect data in a region of interest (ROI). Due to their low energy, locating sensor nodes in large outdoor areas is challenging, which precludes GPS integration. WSNs typically comprise a small number of beacon nodes (BN) whose locations are known in advance, with most nodes deployed at unknown coordinates within the ROI. Endeavours to determine the locations of such unknown WSN nodes are largely based on the impractical assumption that every unknown node (UN) is within the communication range of BNs. Subsequently, these approaches utilise at least two BNs to determine the position of one UN. The Received Signal Strength Indicator (RSSI) or Angle of Arrival (AoA) values of the signals from the BNs form the basis for such localisation. This article suggests an iterative hybrid approach incorporating AoA and RSSI techniques, achieving accurate localisation with just one BN. The iterative method gradually covers the region, avoiding the unrealistic assumption of having all UNs within range. It also presents an innovative use of a unipolar stepper motor for AoA measurements. Experiments in a simulated environment and a real-world prototype validate the approach’s effectiveness.