SBIR Phase II: High Resolution Channel Sounding for Indoor TDOA Positioning Using a Narrowband RF Transceiver

This Small Business Innovation Research Phase II project is focused on high-accuracy wireless positioning technology for indoor environments. Indoor time-of-flight-based positioning technologies have had little commercial success to date primarily because of multipath - signal reflections that smear the arrival time of the over-the-air signals, making it difficult to determine the arrival time from the line-of-sight (LOS) or shortest distance path. The best way to combat multipath is to use ultra-wideband (UWB) location beacon signals with bandwidths in excess of 500 MHz; the wide signal bandwidth increases the resolution in the time-domain, allowing the receiver to distinguish the LOS from other paths. The challenges with UWB are that it is plagued by high manufacturing costs, too much DC power consumption and regulatory issues limiting its range and operating frequencies. The focus of our research is to develop a way to overcome these limitations by defining a method for transmitting a sequence of relatively narrowband standards-based (e.g., WiFi) signals in such a way as to make them behave like UWB signals, yielding UWB-like positioning accuracy at no additional cost and without any of the other aforementioned shortcomings. The broader impact/commercial potential of this project is fueled in part by the ubiquity of the smartphone, whereby a large and growing number of applications could benefit from high-accuracy indoor positioning technology, including: indoor route guidance, mobile retail (find products, receive targeted ads, use proximity-sorted shopping lists), staff and asset tracking for healthcare and manufacturing industries, indoor E911, location-based security, exhibit tracking commentary and route guidance for the blind. However, existing state-of-the-art positioning systems such as WiFi received signal strength (RSS) techniques are not accurate enough (typically 30 feet at 90% confidence) for many of these applications. There are UWB-based solutions available today that are much more accurate than their RSS counterparts, but there is strong resistance to integrating UWB into smartphones due to cost, DC power and regulatory limitations. The goal of this project is to provide a way to make straightforward modifications to a WiFi chipset's MAC and PHY in order to achieve an indoor location accuracy of 3 feet or better with 90% confidence, yielding an order-of-magnitude accuracy improvement at no additional cost, since WiFi is already a standard feature in most smartphones.