基于能量采集的译码转发中继系统功率分配算法

The Algorithm of Power Allocation in Decode-and-Forward Relaying System with Energy Harvesting

本文针对基于能量采集的译码转发(DF)中继蜂窝异构网络,提出了一种系统容量最大化的功率分配算法。中继和用户节点均采集由基站发送的射频信号的能量;利用采集到的能量,通过时分多址方式,用户节点经中继将信息发送给基站。在满足中继和用户节点采集能量的因果性限制及总功率受限条件下,构建了系统容量的优化模型。利用拉格朗日乘子法和KKT(Karush-Kuhn-Tucker)最优条件,为使系统容量最大化,对中继和用户功率进行分配;通过等效信道增益,将中继功率和用户功率联合优化问题简化为用户功率优化问题,然后通过次梯度算法获得功率最优解。仿真结果表明,与受限于中继和用户采集能量因果性的用户平均功率算法相比较,本文算法可以提高系统平均容量。

This paper proposes a power allocation algorithm that can maximize the average throughput of the system on the basis of a cellular heterogeneous network with energy harvesting. Users and relay harvest RF energy from the source, then users use these energy to transmit information to the source via the relay through the way of TDMA. The optimal model is built on the condition that the causality of energy harvested by the users and the relay is satisfied and the total power of them is restricted. We allocate the power of relay and users so as to maximize the average throughput of the system by making use of the Lagrange multiplier method and the KKT optimal conditions. Moreover, we simplify co-optimization of relay power and user power to optimization of user power by way of equivalent channel gains, then we get the optimal power allocation through the gradient algorithm. Simulation results show that, comparing with the average power allocation algorithm subject to the causality of energy harvested by the relay and users, the algorithm stated in this paper can effectively improve the average throughput of the system.