  We introduce OnRMap, an online radio mapping (RMap) approach for the sensing
and localization of active users (AUs), devices that are transmitting radio
signals, and passive elements (PEs), elements that are in the environment and
are illuminated by the AUs' radio signals. OnRMap processes the signals
received by a large intelligent surface and produces a radio map (RM) of the
environment based on signal processing techniques. The method then senses and
locate the different elements without the need for offline scanning phases,
which is important for environments with frequently changing spatial layouts.
Empirical results demonstrate that OnRMap presents a higher localization
accuracy than an offline method, but the price paid for being an online method
is a moderate reduction in the detection rate.
