Stability and performance analysis of wireless powered communication networks

In RF-based wireless powered communication networks (WPCNs), the wireless charging rate at a device is usually low or unstable because of health concerns or time-varying characteristics of wireless channels. Under a low charging rate, the data backlog at a wireless device may be continuously increasing, leading to system performance degradation and data loss. To keep a wireless powered device stable and preserve a finite data backlog, the upper limit of data arrival/acquisition rate at a wireless powered device must be solved under the given data transmission rate and wireless charging rate. Hence, in this paper a novel two-dimensional continuous-time Markov chain model was proposed for analyzing the stability condition of a wireless powered device with a finite energy storage buffer. The average number of data packets, average packet delay, and energy shortage probability at a wireless powered device were analyzed as well. Additionally, simulations were conducted to validate the analytic results and demonstrate that the obtained stability condition is necessary and sufficient for the wireless device.