1 Introduction In every 5G network, your phone and the base station are constantly whispering to each other. The phone reports back what the wireless channel looks like - this is called Channel State Information (CSI). Think of it as a real-time weather forecast for radio waves. Without it, the base station has no idea which direction to aim your signal or how to shape it so it reaches you cleanly. Here's the problem: the more antennas we add, the thicker that weather report becomes [1].
