Evaluating Off-the-shelf Hardware for Indoor Positioning

Sammanfattning: An indoor positioning system (IPS) is a system to locate objects in indoor environments using radio waves, magnetic fields, acoustic, optical and video signals or other sensory information with help of a number of known reference positions. Nowadays, indoor positioning based services are used in a wide variety of areas and indoor positioning is getting considerable attention from both research and industry. Building indoor positioning systems using off-the-shelf hardware can considerably reduce the cost of the system implementation. In this master thesis, three kinds of off-the-shelf hardware based on Ultra-Wideband (UWB), WiFi and Bluetooth low energy (BLE) technology respectively are exploited to build up indoor positioning systems. Evaluation and comparison of these three systems are performed through a comprehensive study of the related theory, practical experiments and brief study of off-the-shelf hardware. Commonly used radio positioning technologies and basic indoor positioning techniques are studied as the foundation of the practical experiments. Accuracy, power consumption, cost and ease of deployment are defined as criteria to evaluate and compare the three systems. A systematic method for deploying these three positioning systems for practical experiments is presented and discussed. A trilateration positioning algorithm is implemented for these three systems to estimate positions and compare accuracy. Results from experiments for both line of sight and none line of sight scenarios are given. Results from a brief study of off-the-shelf hardware for a rough qualitative comparison of power consumption and cost of these three evaluated hardware are presented. Furthermore, obstruction experiments were performed to observe influences of the obstacles on accuracy for these three hardware. Finally, suggestions on future work are provided. The evaluation shows that the UWB hardware performs the best accuracy for indoor positioning, in centimeter order, but it costs more than the WiFi and BLE hardware. The BLE hardware provides worst indoor positioning accuracy, around 4.5 m in average. However, it is the cheapest and most power consumption efficient among these three evaluated hardware. The WiFi hardware is a kind of a trade-off between the UWB and BLE hardware in terms of indoor positioning, giving medium level accuracy, power consumption and cost. The BLE hardware is easier to deploy compared to the UWB and WiFi hardware as BLE devices are smaller size and able to be powered by coin batteries and thus can avoid external physical connections. However, the RSS-based BLE IPS need proper propagation model to estimate distances, which adds extra workload for the deployment compared to the UWB and WiFi IPSs. Obstruction experiments show that obstacles degrade ranging performance greatly for all of these three hardware and influence on the BLE hardware is the most severe.