Exact post-scheduling SINR analysis for orthogonal random beamforming systems

Derived are the exact cumulative distribution functions (CDFs) of each user´s feedback signal-to-interference-plus-noise ratio (SINR), and the post-scheduling SINR in orthogonal random beamforming systems with M transmit antennas and K single-antenna users considering both user feedback and scheduling. A key contribution is to derive the exact CDF of the post-scheduling SINR by direct integration, and it is verified by Monte-Carlo simulations. It is also shown that the existing approximate CDF is different from the exact distribution for SINR smaller than 0 dB.