Beamforming Based on Specular Component for Massive MIMO Systems in Ricean Fading

This paper is concerned with massive MIMO systems over Ricean fading channels. To reduce the overhead for estimating channel state information (CSI), we investigate transmit/receive beamforming transmission only based on the specular component and treat the scattered component as interference. For the scenario without co-channel interference, we show that the ergodic achievable rate can remain unchanged when the transmit power is scaled down by the multiplication of the two numbers of antennas at the transmitter and the receiver, and can be equal to that of the corresponding beamforming based on perfect CSI when both of the numbers of antennas go without bound. Theoretical analysis is also extended to the scenario with co-channel interference. Simulation results further show that even though the numbers of antennas are not very large, the exact rate is quite close to its limit.