Title: Massive MIMO 5G Cellular Networks: mm-wave vs. μ-wave Frequencies,
Abstract: Enhanced mobile broadband (eMBB) is one of the key use-cases for the
development of the new standard 5G New Radio for the next generation of mobile
wireless networks. Large-scale antenna arrays, a.k.a. Massive MIMO, the usage
of carrier frequencies in the range 10-100 GHz, the so-called millimeter wave
(mm-wave) band, and the network densification with the introduction of
small-sized cells are the three technologies that will permit implementing eMBB
services and realizing the Gbit/s mobile wireless experience. This paper is
focused on the massive MIMO technology; initially conceived for conventional
cellular frequencies in the sub-6 GHz range (\mu-wave), the massive MIMO
concept has been then progressively extended to the case in which mm-wave
frequencies are used. However, due to different propagation mechanisms in urban
scenarios, the resulting MIMO channel models at \mu-wave and mm-wave are
radically different. Six key basic differences are pinpointed in this paper,
along with the implications that they have on the architecture and algorithms
of the communication transceivers and on the attainable performance in terms of
reliability and multiplexing capabilities.