Abstract
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.
Highlights
Over the recent years, there has been a rapid growth of the concept of the Internet of Things (IoT), connecting all kinds of different devices in order to improve the quality of life in various aspects
As the density increases while the energy coverage probability remains π(ǫ) = 1, the probability πρ decreases, which justifies the decrease in πs after its peak value
We studied an ad hoc cognitive secondary network which is wirelessly powered by ambient radio frequency (RF) signals and is underlaid with an ad hoc primary network
Summary
There has been a rapid growth of the concept of the Internet of Things (IoT), connecting all kinds of different devices in order to improve the quality of life in various aspects. The authors in [17] consider macro BSs which are underlaid with CR femtocell BSs and they obtain the optimal spectrum sensing threshold which minimizes the outage probability of the femtocell BSs. By using stochastic geometry, the authors in [18] study a wireless powered underlay CR radio network, where secondary users harvest energy from RF transmissions in the downlink and transmit in the uplink by using the harvested energy with the TDMA scheme. Under an interference power constraint, they derive the optimal power control and the time allocation which maximizes the sum rate of the secondary users in the CR network In this context, the authors in [19] propose a random and a prioritized spectrum access policy for the coexistence of CR networks with primary cellular networks and they show that energy harvesting can be used with the CR transmission providing sufficient quality of service without degrading the primary network’s performance.
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