In this paper, we study power and subcarrier allocation in decode-and-forward (DF) cognitive relay network based on orthogonal frequency division multiple access (OFDMA) technology, in which power splitting (PS) is used for the secondary users (SUs) supporting simultaneous wireless information and the power transfer (SWIPT). We attempt to maximize the energy efficiency (EE) of the secondary system subject to the constraints of minimum system rate, maximum transmission power and minimum harvested energy. The optimal power allocation (OPA) algorithm is proposed to determine the optimal solution of relay transmission power, power splitting ratio and subcarrier allocation. To tackle the original non-convex optimization problem, the Dinkelbach method is used for fractional programming and the problem is decomposed into two solvable sub-problems. The Lagrangian dual algorithm is utilized to determine the optimal transmission power and the power splitting ratio. The Hungarian algorithm is then introduced to determine the optimal subcarrier allocation. Compared with some existing algorithms, the simulation results show that the proposed OPA scheme is able to achieve higher energy efficiency when certain communication quality is required.

在本文中，我们研究了基于正交频分多址（OFDMA）技术的解码转发（DF）认知中继网络中的功率和子载波分配，其中功率分配（PS）用于次要用户（SU）同时支持无线信息和电源传输（SWIPT）。我们尝试在最小系统速率，最大传输功率和最小收集能量的约束下，最大化二次系统的能源效率（EE）。提出了最优功率分配（OPA）算法来确定中继传输功率，功率分配比和子载波分配的最优解。为了解决原始的非凸优化问题，将Dinkelbach方法用于分数规划，并将该问题分解为两个可解决的子问题。拉格朗日对偶算法用于确定最佳传输功率和功率分配比。然后引入匈牙利算法来确定最佳子载波分配。与现有算法相比，仿真结果表明，在需要一定通信质量的情况下，提出的OPA方案能够实现更高的能效。