This paper explores the use of vehicles as mobile
gateways to enable large-scale connectivity for the Internet of
Things (IoT). The proposed network architecture is referred to
as mesh+vehicular and is based on mesh communication between
IoT devices and short range communication between repositories
located along the roads and vehicular gateways. The main goal
of the paper is to propose a system level model of this
architecture and to demonstrate its advantages over the
conventional mesh+cellular IoT architecture. Using techniques
of stochastic geometry, queuing theory, and wireless networking,
we derive the capacity of such an architecture in terms of maximum
data rate per IoT device that the network can sustain. We show that
if the density of IoT devices is sufficiently large and the density
of repositories scales with that of IoT devices, then the proposed
vehicular+mesh architecture has a capacity scaling that outperforms
that of the conventional mesh+cellular architecture.