Maximizing Proportional Fairness in Wireless Powered Communications

This letter investigates the fundamental tradeoff between sum rate and fairness of a wireless-powered uplink communication system, consisting of one base station (BS) and multiple energy harvesting users, which are coordinated through the harvest-then-transmit protocol. To this end, the optimal rate and time allocation, when aiming to maximize the proportional fairness, is investigated. Two well known communication protocols are considered, namely, time division multiple access (TDMA) and nonorthogonal multiple access with time-sharing (NOMA-TS). It is shown that NOMA-TS outperforms the considered benchmark scheme, which is the NOMA with fixed decoding order and adaptive power allocation, while TDMA proves to be an appropriate choice, when all the users are located in similar distances from the BS.