  Millimeter-wave (mmWave) communication opens up tens of giga-hertz (GHz)
spectrum in the mmWave band for use by next-generation wireless systems,
thereby solving the problem of spectrum scarcity. Maintaining connectivity
stands out to be a key design challenge for mmWave networks deployed in urban
regions due to the blockage effect characterizing mmWave propagation.
Specifically, mmWave signals can be blocked by buildings and other large urban
objects. In this paper, we set out to investigate the blockage effect on the
connectivity of mmWave networks in a Manhattan-type urban region modeled using
a random regular lattice while base stations (BSs) are Poisson distributed in
the plane. In particular, we analyze the connectivity probability that a
typical user is within the transmission range of a BS and connected by a
line-of-sight. Using random lattice and stochastic geometry theories, different
lower bounds on the connectivity probability are derived as functions of the
buildings' size and probability of a lattice cell being occupied by a building
as well as BS density and transmission range. The asymptotic connectivity
probability is also derived for cases of dense buildings. Last, the results are
extended to heterogeneous networks. Our study yields closed-form relations
between the parameters of the building process and the BS process, providing
useful guidelines for practical mmWave network deployment.
