Software based measurement of round trip time observables for location in IEEE 802.11 networks

Time-based multilateration in IEEE 802.11 networks usually involves custom hardware designs, which tend to slow down the implementation and deployment of the location system. This paper presents software for calculating time-based location observables. This software enhances the SoftMAC layer of the Linux operating system by adding location-related measuring capabilities. A plugin for calculating the round trip time between two network entities is included in the software definition. Real data have been collected to test the performance of the proposed system. Despite the relevant noise present in the measurements, the results prove that the round trip time measurements achieved are useful to estimate distances achieving estimates with RMS of the error close to 2 meters.