Accurate positioning using short-range communications

Satellite-based positioning systems such as GPS have been used for positioning by the transportation industry for decades. Accurate positioning (<1 cm error) requires the availability of multiple (5+) GPS signals which is 'possible' only in suburban communities but utterly unachievable in urban areas. We are motivated by the inevitably and imperative need to resolve accurate positioning issues for transportation and industrial applications. In this research we focus on developing positioning scheme based on short-range wireless signals. To achieve that, we develop a system assuming the availability of multiple fixed access points (5+) and employ Time-Difference-of-Arrival (TDoA) with Kalman Filter. We also discuss multi/tri-lateration and evaluate some of the root causes for Dilution of Precision (DoP) of calculated positioning. We use fixed calibrated 2.4 GHz access points. We use realtime observed data while applying our model off-line. We extended the model to mimic the 5.9 GHz Dedicated Short Range Communications (DSRC) signals as defined in IEEE 1609.x. Results are compared in each case and compared to accurately calibrated Differential Global Positioning System (DGPS) record captured on the same testing. We maintained clear Line-of-Sight (LoS) throughout our evaluation and used low speed of the moving vehicles (< 60 Km/h).