  In the US, people spend 87% of their time indoors and have an average of four
connected devices per person (in 2020). As such, providing indoor coverage has
always been a challenge but becomes even more difficult as carrier frequencies
increase to mmWave and beyond. This paper investigates the outdoor and
outdoor-indoor coverage of an urban network comparing globally standardized
building penetration models and implementing models to corresponding scenarios.
The glass used in windows of buildings in the grid plays a pivotal role in
determining the outdoor-to-indoor propagation loss. For 28 GHz with 1
W/polarization transmit power in the urban street grid, the downlink data rates
for 90% of outdoor users are estimated at over 250 Mbps. In contrast, 15% of
indoor users are estimated to be in outage, with SNR $<-$3 dB when base
stations are 400 m apart with one-fifth of the buildings imposing high
penetration loss ($\sim$ 35 dB). At 3.5 GHz, base stations may achieve over 250
Mbps for 90% indoor users if 400 MHz bandwidth with 100 W/polarization transmit
power is available. The methods and models presented can be used to facilitate
decisions regarding the density and transmit power required to provide high
data rates to majority users in urban centers.
