Followings are based on Massive MIMO and Small Cells : Improving Energy Efficiency by Optimal Soft-Cell Coordination ([1]).

Reference

[1] Massive MIMO and Small Cells : Improving Energy Efficiency by Optimal Soft-Cell Coordination

Emil Bjornson, Marios Kountouris and Merouane Debbah

Alcatel-Lucent Chair on Flexible Radio, SUPELEC, Gif-sur-Yvette, France

Department of Telecommunications, SUPELEC, Gif-sur-Yvette, France

ACCESS Linnaeus Center, Signal Processing Lab, KTH Royal Institue of Technology, Stockholm, Sweden