  In this paper, we propose a novel channel feedback scheme for frequency
division duplexing massive multi-input multi-output systems. The concept uses
the notion of user statistical separability which was hinted in several prior
works in the massive antenna regime but not fully exploited so far. We here
propose a hybrid statistical-instantaneous feedback scheme based on a user
classification mechanism where the classification metric derives from a rate
bound analysis. According to classification results, a user either operates on
a statistical feedback mode or instantaneous mode. Our results illustrate the
sum rate advantages of our scheme under a global feedback overhead constraint.
