Indoor Radio Positioning Using Pseudolites in the UHF Band – Signals and Ranging Precision Survey

<title>Abstract</title> This contribution presents a theoretical and practical analysis of the precision of deep-indoor radio positioning using sub-GHz (ultra-high frequency) band ranging pseudolites, penetrating whole buildings and blocks. Working deep indoors, pseudolite systems face a negative signal-to-noise ratio and a challenging dynamic power range. These challenges lead to small nuances and limitations compared with global navigation satellite systems. Therefore, ranging codes, modulation techniques, and corresponding time-delay/range, clock, carrier, and signal-to-noise estimators are analyzed and discussed to demonstrate the limits of deep-indoor ranging. Then, the ranging precision is evaluated based on the Cramer-Rao lower bound of ranging variance: its analytical development is followed by numerical computation and comparison with results from real measurement campaigns and a particular model of losses.