Theory and development of cross-layer techniques for localization in environments with Extreme Emitter Densities

As the RF spectrum becomes increasingly congested, localization algorithms which are tolerant of high levels of interference become necessary. A unique opportunity exists to study these issues during any event in a large venue, such as a football game in a large stadium. We report on the development of a RF sensor localization field deployment, LOC-EED, in the football stadium at Georgia Tech as well as a simplified laboratory testbed for controlled experimentation. During football games, cellphones, stadium personnel radios, media organization radios and wireless controlled devices, game official wireless headsets, etc. create an Extreme Emitter Density (EED) background that is a challenge to any algorithm attempting to identify and localize a single emitter. The laboratory testbed and field deployment to study this problem consists of RF sensor nodes (RFSN) using wideband RF digitizers and general purpose processors to sense the RF environment. We are using software radios as an enabling technology for the development of unique cross-layer localization techniques which are typically not realizable on specialized hardware, such as WiFi APs. This paper reports the details of LOC-EED and offers a preliminary analysis of spectrum captures in the 2.4 GHz band during a live football game. The analysis and a simulation of a simple cross-layer localization technique confirm both the need for, and ability to exploit, cross-layer information for localization.