UC Irvine

MOTIVATION • Americans spend, on average, 90% of their time indoors • No single infrastructure-free technology exists today that provides submeter-level or meter-level localization indoors OUR APPROACH Exploit cellular long-term-evolution (LTE) signals of opportunity due to their inherent desirable characteristics: • High received carrier-to-noise-ratio: C/N0 ≈ 55-80 dB-Hz in different indoor environments • Free to use: exploit LTE reference signals (dataless) without being a subscriber • Abundant: dozens of nearby eNodeBs corresponding to different providers are available • High bandwidth: up to 20 MHz and even higher with LTE-Advanced (up to 100 MHz) • Favorable geometry: geometrically diverse by construction to provide maximum communication coverage CHALLENGES • Unknown eNodeBs’ states (position, clock bias, and clock drift) • LTE eNodeBs’ clocks are less stable than GNSS clocks and not perfectly synchronized • Short-delay multipath