What type of positioning algorithm is used in the RealTrac local positioning system?

The RealTrac local positioning system provides positioning through IMU (inertial measurement unit) and is checked afterwards with trilateration. This process measures the distance between portable devices and access points automatically using the methods of Time-of-Flight and Received Signal Strength Indicator (RSSi). All the obstructions (walls, metal structures etc.) are taken into account while measuring.