Abstract
Wireless powered communication technology has a great potential to power low-power wireless sensor networks and Internet of Things (IoT) for real-time applications in future 5G networks, where age of information (AoI) plays a very important performance metric. This paper studies the system average AoI of a wireless powered network, where a wireless-powered user harvests energy from a wireless power source (WPS) and then transmits data packets to its access point (AP) by using the harvested energy. The user generates data packets with some probability and adopts the first-come-first-served (FCFS) service policy. For such a system, by using the queuing theory and the probability models, we derive a closed-form expression of the system average AoI. We also formulate an optimization problem to minimize the AoI by optimizing the data packet generating probability, and find its solution by simple calculation and search. Simulation results demonstrate the correctness of our obtained analytical results. It also shows that, when the total distance of the two hops is fixed, the system average AoI increases linearly with the increment of the distance of the first hop, and a smaller data packet generating probability should be selected to match a bigger first-hop distance for achieving a smaller system average AoI. Moreover, a smaller data packet size also contributes to a smaller system average AoI.
Highlights
The widespread use of mobile devices and applications has made the real-time information updating applications such as news, weather forecasting and traffic alert more and more popular [1,2,3]
The common key point of above-mentioned real-time applications is how to guarantee the freshness of the collected data
We study the average age of information (AoI) in a wireless powered network, where a wireless-powered user harvests energy from a wireless power source (WPS) and transmits data packets to its access point (AP)
Summary
The widespread use of mobile devices and applications has made the real-time information updating applications such as news, weather forecasting and traffic alert more and more popular [1,2,3]. The common key point of above-mentioned real-time applications is how to guarantee the freshness of the collected data. Delay and throughput are two important and widely adopted indices to evaluate the system performance of communication networks [8,9]. They are insufficient to describe the freshness of the data [10]. A new metric, referred to as age of information (AoI), Entropy 2018, 20, 948; doi:10.3390/e20120948 www.mdpi.com/journal/entropy
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