  The evolving Fifth Generation New Radio (5G-NR) cellular standardization
efforts at the Third Generation Partnership Project (3GPP) brings into focus a
number of questions on relevant research problems in physical-layer
communications for study by both academia and industry. To address this
question, we show that the peak download data rates for both WiFi and cellular
systems have been scaling exponentially with time over the last twenty five
years. While keeping up with the historic cellular trends will be possible in
the near-term with a modest bandwidth and hardware complexity expansion, even a
reasonable stretching of this road-map into the far future would require
significant bandwidth accretion, perhaps possible at the millimeter wave,
sub-millimeter wave, or Terahertz (THz) regimes. The consequent increase in
focus on systems at higher carrier frequencies necessitates a paradigm shift
from the reuse of over-simplified (yet mathematically elegant) models, often
inherited from sub-6 GHz systems, to a more holistic view where real
measurements guide, motivate and refine the building of relevant but possibly
complicated models, solution space(s), and good solutions. To motivate the need
for this shift, we illustrate how the traditional abstraction fails to
correctly estimate the delay spread of millimeter wave wireless channels and
hand blockage losses at higher carrier frequencies. We conclude this paper with
a broad set of implications for future research prospects at the physical-layer
including key use-cases, possible research policy initiatives, and structural
changes needed in telecommunications departments at universities.
