Energy efficient design for multiuser downlink energy and uplink information transfer in 5G

Simultaneous wireless information and power transfer (SWIPT) is studied in this paper for the wireless powered downlink (DL) and multiuser information uplink (UL) systems. The objective is to maximize the energy efficiency defined as the ratio of the achieved throughput over the energy cost by optimizing the time allocation for the DL and multi-user UL traffics and its goal is to obtain the analytical expression to the optimal time allocation yet the resulting difficulty comes from the sum throughput of the multiuser in UL as well as the corresponding power consumption. To tackle this, the Jensen inequality is applied to approximating the exact expression of the sum throughput for the UL multi-users, leading to an upper-bound of the counterpart. The final closed form is exact in the single-user scenario yet approximate in the multi-user scenario. Numerical simulations verify the tightness of this approximation and the performances of the proposed analytical scheme.创新点1建立了能量效率最大化的时间分配数学问题,该问题适用于任意多用户的下行能量传输和上行无线信息传输的多用户传输系统2推导得到系统的能量效率函数的上界函数,该函数来能够较紧的逼近原始准确能量效率函数3基于界函数,推导出每个用户的上行链路传输无线信息的持续时间,而且得到解析解,该解析解在单用户场景下具有全局最优性,在任意多用户场景下具有渐进最优性。