These slightly different conditions allow your device and the receiving antenna at the base station to more easily pick apart the signal streams from one another (there is a higher signal-to-noise ratio/SINR), allowing the device to achieve higher 'ranks'. Direct - the signal travels directly from the transmitting antenna to the receiving antenna Reflected - the signal is reflected off an object towards the receiving antenna Refracted - the signal path is slightly changed by an object towards the receiving antenna Scattered - the signal hits a rounded object and spreads into multiple directions Ground-reflected - the signal is reflected off the ground towards the receiving antenna Rank 2 means there's a high SINR on two streams, rank 3 meaning three streams, and so on.