Downlink SINR distribution in multiuser large scale antenna systems with conjugate beamforming

In this paper, the downlink signal-to-interference-plus-noise ratio (SINR) distribution in multiuser large scale antenna systems with conjugate beamforming and Rayleigh fading is investigated. The probability density function (PDF) is derived and the distribution in high signal-to-noise ratio (SNR) regime is studied. Results indicate that the PDF of downlink SINR converges to F distribution when the interference is dominant over noise. It is interesting that the asymptotic SINR is just the reciprocal of the ratio of the number of users U to the number of transmit antennas N, and is irrelevant to the average transmit power when N and U grow with fixed ratio. However, when U is a large constant, the transmit power could be proportional to equation to maintain a specified quality of service (QoS), as a result of the large scale antenna system effect. Simulation results validate the derived PDF and analytical results.