Message-Passing-Based Joint User Association and Time Allocation for Wireless Powered Communication Networks

This work develops a joint design of user association and time allocation for wireless powered communication networks. A harvest-then-transmit protocol is applied with base stations (BSs) transfer wireless energy to users in the first downlink phase. Then, the users utilize the harvested energy for their information transmission to the BS in the subsequent uplink phase. In this configuration, we employ a general $\alpha $ -fair utility to maximize the network throughput. In particular, the maximization of sum-rate, proportional fairness and minimum rate are investigated individually. We introduce a new message-passing based framework to provide an efficient distributed solution for the user association and optimize the time allocation between the downlink and uplink phase. To achieve this joint goal, each user selects a BS in a distributed manner to maximize the $\alpha $ -fair utility. After identifying the user association, the time allocation is determined by an efficient line search technique. Simulation results show that the proposed algorithm outperforms existing approaches.