Analysis of Channel Hardening and Favorable Propagation in Massive MIMO Systems

Abstract

The evolution of mobile communication systems has been quite disruptive during the last decades. Fifth generation technologies and sixth generation perspectives use a large amount of transmitting antennas in comparison to the number of users, by the use of Massive MIMO (Multiple Input Multiple Output). Two channel features important to the mMIMO are the channel hardening and the favorable propagation. This work analyzes how the features are related to the number of transmitting antennas. It is shown that, for the channels used, the ratio of transmitting antennas to the number of users must be greater than 20 in order to obtain a reduction in gap-to-capacity greater than 75% using the free-space non-fading channel and 55% using the Rayleigh fading channel. This result generates some consequences in the analysis of current propositions for the communication algorithms that suppose the existence of these features.