SBIR Phase I: High resolution channel sounding for indoor TDOA positioning using narrowband RF transceiver

This Small Business Innovation Research Phase I project is focused on wireless Time Difference Of Arrival (TDOA) positioning technology for indoor or cluttered outdoor environments. Indoor TDOA technologies have had little commercial success to date primarily because of multipath - signal reflections off of surfaces that smear the arrival time of the over-the-air signals, making it difficult to determine the arrival time of the location beacon from the Line-Of-Sight or shortest distance path. The best way to combat multipath is to use very wideband beacon signals. The wide signal bandwidth increases the resolution in the time-domain, allowing the receiver to distinguish between paths. A key challenge with using such wide signal bandwidths is that it can?t be done with commercially-available highly-integrated low-cost components. Another constraint is regulatory restrictions that limit the transmit power of such signals. The focus of this research is to develop a way to overcome these practical limitations by defining a special type of narrowband location beacon that gives the same performance as very wideband signals but that can be implemented using affordable, off-the-shelf radio components. A great number of applications could benefit from high-resolution indoor location technology, including: Indoor floor map positioning and route guidance for smartphones, indoor location-based advertising, indoor E911, location-based security, medical staff and asset monitoring and Search and rescue. However, existing solutions such as nearest Access Point or Received Signal Strength triangulation are neither accurate enough nor cost-effective due to the high density required to achieve this accuracy. There are TDOA solutions based on Ultra WideBand that have better accuracy but these networks have limited range due to FCC power limitations and limited market success to date. WiFi has already revolutionized wireless mobility and the solution presented here will leverage WiFi as a go-to-market strategy. If successful, the solution will not be limited by regulatory power restrictions and will, because it is based on WiFi, be affordable.