Optimal Throughput of Wireless Powered Communication Network with Nonlinear Energy Harvesting under Energy and Latency Constraints

Globecom, pp. 3219–3224

Abstract

This paper studies a wireless powered communication network (WPCN), where a passive user first harvests energy from a wireless power transfer (WPT) base station (BS), and then transmits data to a targeted receiver. To maximize the system throughput under finite BS energy budget and latency constraint, we formulate a joint dynamic WPT power, energy harvesting (EH) duration and wireless information transfer (WIT) duration optimization problem. To ensure the practicality of the design, a realistic nonlinear EH model is considered, making the problem nonconvex, while the infinite number of variables associated to WPT power control makes it more intractable. To address these issues and achieve the optimal solution, we first analytically characterize the structure of the optimal WPT policy for maximizing the harvested energy, following which we prove that the optimal WPT power control can be reduced to a constant-power policy without loss of optimality. Specifically, the optimal WPT power is characterized as a piecewise function determined by the EH duration and BS energy budget. We further reveal the tradeoff between WIT duration and SNR under given WIT energy budget, and prove that the system throughput increases monotonically with WIT duration despite reduced transmit power. These insights, on optimal WPT and WIT solution properties, allow us to equivalently transform the original non-convex problem into a single-variable optimization problem. The globally optimal solution can be efficiently obtained via one-dimensional exhaustive search. Simulation results validate the effectiveness of the proposed optimal WPCN design.

Authors 4

1. Ning Guo

   Wuhan University

   Affiliation as printed

   Wuhan University,School of Electronic Information,China

2. Xiaopeng Yuan Aachen INDA Chair

   RWTH Aachen University

   Affiliation as printed

   RWTH Aachen University,INDA Chair,Germany

3. Yulin Hu

   Wuhan University

   Affiliation as printed

   Wuhan University,School of Electronic Information,China

4. Anke Schmeink Aachen INDA Chair

   RWTH Aachen University

   Affiliation as printed

   RWTH Aachen University,INDA Chair,Germany