  The radio interferometric positioning system (RIPS) is an accurate node
localization method featuring a novel phase-based ranging process. Multipath is
the limiting error source for RIPS in ground-deployed scenarios or indoor
applications. There are four distinct channels involved in the ranging process
for RIPS. Multipath reflections affect both the phase and amplitude of the
ranging signal for each channel. By exploiting untapped amplitude information,
we put forward a scheme to estimate each channel's multipath profile, which is
then subsequently used to correct corresponding errors in phase measurements.
Simulations show that such a scheme is very effective in reducing multipath
phase errors, which are essentially brought down to the level of receiver noise
under moderate multipath conditions. It is further demonstrated that ranging
errors in RIPS are also greatly reduced via the proposed scheme.
