Smartphone positioning in multi-floor environments without calibration or added infrastructure

摘要

Indoor positioning for smartphone users has received a lot of attention in recent years. While many solutions have been developed, most rely on a need for pre-deployment of infrastructure or collecting ground truth data to train on. In this paper we see what can be done using existing WiFi-infrastructure and Received Signal Strength from these to smartphones, not using any calibration of the signal environment or manually set WiFi positions. We expand on previous work by using a multi-floor model taking into account dampening between floors, and optimize a target function consisting of least squares residuals, to find positions for WiFis and the smartphone measurement locations simultaneously. Pressure sensors are used to do floor estimation. The method was tested inside two multi-story buildings, with 5 stories each, with median errors of smartphone positions of 12.5m and 16.4m and with WiFi median position errors of 7.16m and 19.4m respectively. Correct floor detection was achieved for 96% of all smartphone positions.