  In a multi-user millimeter (mm) wave communication system, we consider the
problem of estimating the channel response between the central node (base
station) and each of the user equipments (UE). We propose three different
strategies: 1) Each UE estimates its channel separately, 2) Base station
estimates all the UEs channels jointly, and 3) Two stage process with
estimation done at both UE and base station. Exploiting the low rank nature of
the mm wave channels, we propose a generalized block orthogonal matching
pursuit (G.BOMP) framework for channel estimation in all the three strategies.
Our simulation results show that, the average beamforming gain of the G.BOMP
algorithm is higher than that of the conventional OMP algorithm and other
existing works on the multi-user mm wave system.
