SINR distribution approximation for maximal ratio communications

The SINR distribution is of key importance to wireless network performance analysis, planning and optimization. A realistic and usable SINR distribution has to consider both, the fast and the slow fading, i.e., to utilize a composite fading model. There have been only partial efforts in deriving a closed form and simple SINR distribution, using a realistic composite fading model and valid throughout the full SNR range. Recently, there is also a rising necessity for SINR distribution models that integrate the multi-antenna and multi-user aspects of the emerging 5G systems. This paper derives an analytical lognormal approximation to the SINR distribution in scenarios with maximal ratio communication using multiple transmit or receive antennas. The derivations incorporate a newly derived lognormal composite fading approximation and lognormal approximation to the distribution of the summary interference plus noise, in order to approximate the SINR distribution. The expressions are simple and closed form, which makes them applicable to a variety of communication network optimization and evaluation problems. The paper uses simulation analysis to prove the validity of the analytical SINR distribution approximation in homogeneous and heterogeneous cellular network deployments. The results show only few dBs of mismatch in these realistic cellular network scenarios.