Minimum Length Scheduling for Discrete Rate Based Full Duplex Wireless Powered Communication Networks

In this study, we consider a wireless powered communication network where multiple users with radio frequency energy harvesting capabilities communicate to a hybrid energy and information access point in full duplex mode. We characterize an optimization framework for minimum length scheduling to determine the optimal rate adaptation and transmission scheduling subject to energy causality and traffic demand constraints of the users considering discrete-rate transmission model. We first formulate the problem as a mixed integer nonlinear programming problem which is hard to solve for a global optimum in polynomial-time. Then, based on an analysis on the characteristics of the optimal solution, we derive optimality conditions for rate adaptation and scheduling using which we propose a fast polynomial-time complexity heuristic algorithm. We illustrate through numerical analysis that the proposed algorithm performs very close to optimal for various network scenarios.