  Over the recent years, the proliferation of smart devices and their
applications has led to a rapid evolution of the concept of the Internet of
Things (IoT), advancing large scale machine type networks which are
characterized by sporadic transmissions of short packets. In contrast to
typical communication models and in order to capture a realistic IoT
environment, we study an asynchronous channel access performed by a primary ad
hoc network underlaid with a cognitive secondary wireless-powered ad hoc
network. Specifically, we consider that the primary transmitters are connected
to the power grid and employ asynchronous transmissions. On the other hand, the
cognitive secondary transmitters have radio frequency energy harvesting
capabilities, and their asynchronous channel access is established based on
certain energy and interference based criteria. We model this sporadic channel
traffic with time-space Poisson point processes and by using tools from
stochastic geometry, we provide an analytical framework for the performance of
this asynchronous system. In particular, we provide closed-form expressions for
the information coverage probability and the spatial throughput for both
networks and we derive the meta distribution of the
signal-to-interference-plus-noise ratio. Finally, we present numerical results
and provide important insights behind the main system parameters.
