Localisation of Wireless LAN Nodes Using Accurate TDoA Measurements

Time based localisation methods like GPS are widely used for outdoor navigation, whereas indoor navigation is typically performed only on a cell-basis or based on the Received Signal Strength Indicator. Since RSSI is not able to fulfil all current requirements, Time of Arrival and Time Difference of Arrival based approaches have recently gained focus. As time based localisation has high demands on the quality of the timestamps, we propose a special receiver architecture for IEEE802.11b capable of a timestamping accuracy in the sub-nanosecond range. The receiver´s operation is demonstrated by an FPGA based wireless physical layer device implementation. Experimental results show an improvement in terms of accuracy by a factor of 100 up to 1000 over COTS wireless LAN hardware. This enables accurate localisation in wireless LANs just by adding of timing receivers.