Hybrid Indoor Positioning with Wi-Fi and Bluetooth: Architecture and Performance

Reliable indoor positioning is an important foundation for emerging indoor location based services. Most existing indoor positioning proposals rely on a single wireless technology, e.g., Wi-Fi, Bluetooth, or RFID. A hybrid positioning system combines such technologies and achieves better positioning accuracy by exploiting the different capabilities of the different technologies. In a hybrid system based on Wi-Fi and Bluetooth, the former works as the main infrastructure to enable fingerprint based positioning, while the latter (via hotspot devices) partitions the indoor space as well as a large Wi-Fi radio map. As a result, the Wi-Fi based online position estimation is improved in a divide-and-conquer manner. We study three aspects of such a hybrid indoor positioning system. First, to avoid large positioning errors caused by similar reference positions that are hard to distinguish, we design a deployment algorithm that identifies and separates such positions into different smaller radio maps by deploying Bluetooth hotspots at particular positions. Second, we design methods that improve the partition switching that occurs when a user leaves the detection range of a Bluetooth hotspot. Third, we propose three architectural options for placement of the computation workload. We evaluate all proposals using both simulation and walkthrough experiments in two indoor environments of different sizes. The results show that our proposals are effective and efficient in achieving very good indoor positioning performance.