Ultra-dense Radio Access Networks for Smart Cities: Cloud-RAN, Fog-RAN and "cell-free" Massive MIMO

In this paper we discuss the requirements for a radio access network architecture for ultra-dense networks for "smart city" applications, and show that coordination is required between access points to overcome the effects of interference. We propose a new paradigm, Fog Massive MIMO, based on a combination of the "cell-free" massive MIMO concept and the Fog Radio Access Network (F-RAN). In particular we analyze the potential benefit of improved coordination between APs over different coordination ranges.