存在窃听用户下基于SWIPT的协作NOMA网络能效分析
Energy Efficiency Analysis of a SWIPT Enable Cooperative NOMA Communication System with the Presence of Eavesdropper
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摘要: 针对基于携能同传(Simultaneous Wireless Information and Power Transfer,SWIPT)的协作非正交多址接入(Non-Orthogonal Multiple Access,NOMA)网络,提出了一种存在窃听用户下远端用户能效最大化的多维资源分配方法。在考虑近端用户安全传输速率与能量因果性的约束下,通过联合优化源节点、近端用户发射功率以及能量收集时间来建立一个远端用户能效最大化的多维资源分配问题。由于目标函数为分式函数且存在优化变量耦合,故所建立的问题非凸且无法采用凸优化技术获取最优解。为此,通过Dinkelbach方法将所提出的非凸问题转化为减法参数形式的凸优化问题,并在此基础上,提出一种交替迭代算法。最后,计算机仿真验证了所提资源分配方法在远端用户能效方面提升的优越性。Abstract: In this paper, we consider a simultaneous wireless information and power transfer (SWIPT) enable cooperative non-orthogonal multiple access (NOMA) communication system with the presence of eavesdropper, and then propose a multidimensional resource allocation scheme maximizing the energy efficiency of the far user. A multidimensional resource allocation problem to maximize energy efficiency of far users is established by jointly optimizing the transmitting power of the source node and near user as well as the energy collection time, subject to the energy-causality constraint and the safe transmission rate of the near users. As the formulated objective function is a fractional function, and includes couplings among optimization variables, it is non-convex and can not be solved by the existing convex tools. Therefore, we leverage the Dinkelbach method to transform the original problem into a convex optimization problem. On this basis, we propose an alternate iteration algorithm to solute this optimization problem. Finally, computer simulations verify the superiority of the proposed resource allocation method in terms of the energy efficiency of the remote user.