  A framework is proposed for developing and evaluating algorithms for
extracting multipath propagation components (MPCs) from measurements collected
by channel sounders at millimeter-wave frequencies. Sounders equipped with an
omnidirectional transmitter and a receiver with a uniform planar array (UPA)
are considered. An accurate mathematical model is developed for the spatial
frequency response of the sounder that incorporates the non-ideal cross-polar
beampatterns for the UPA elements. Due to the limited Field-of-View (FoV) of
each element, the model is extended to accommodate multi-FoV measurements in
distinct azimuth directions. A beamspace representation of the spatial
frequency response is leveraged to develop three progressively complex
algorithms aimed at solving the singlesnapshot maximum likelihood estimation
problem: greedy matching pursuit (CLEAN), space-alternative generalized
expectationmaximization (SAGE), and RiMAX. The first two are based on purely
specular MPCs whereas RiMAX also accommodates diffuse MPCs. Two approaches for
performance evaluation are proposed, one with knowledge of ground truth
parameters, and one based on reconstruction mean-squared error. The three
algorithms are compared through a demanding channel model with hundreds of MPCs
and through real measurements. The results demonstrate that CLEAN gives quite
reasonable estimates which are improved by SAGE and RiMAX. Lessons learned and
directions for future research are discussed.
