李丽　曾凡仔　徐纪胜

摘   要：提出了一种基于能量采集的认知无线网络的单向中继选择和功率分配方案. 方案考虑主用户和次用户都能进行能量采集且信道状态信息不完美的场景. 此方案首先将次用户作为中继协助主用户传输数据，同时次用户采集无线射频信号的能量，联合功率分配和中继选择策略构造了所提方案的系统能量效应优化问题. 由于優化目标是非凸函数，运用分式规划变形和拉格朗日对偶方法求解. 然后在此基础上构造主用户吞吐量离线优化问题，并采用广义Bender分解方法求解. 最后，通过数值仿真分析评估所提方案的性能，验证了所提方案在能效方面的优势.

关键词：认知无线网络;能量采集;中继选择;功率分配

中图分类号：TN925                      文献标志码：A

A Joint Relay Selection and Power Allocation Scheme

Based on Energy Harvesting in Cognitive Radio Networks

LI Li1，2 ，ZENG Fanzi1，XU Jisheng1

（1. College of Information Science and Engineering，Hunan University，Changsha 410082，China;

2. Hunan Post And Telecommunication College，Changsha 410015，China）

Abstract：This paper proposes a joint relay selection and power allocation scheme for the cognitive radio network based on energy harvesting. Under the condition that the primary user performance is guaranteed， this scheme can significantly improve the energy efficiency of system. This paper considers that the transmitters of primary user and secondary user both conduct energy harvesting. In addition， we consider the imperfect channel status information. First，the secondary user is selected as a relay to assist the primary user to transmit data， while the secondary user collects the energy of the radio frequency. Then， we present the relay selection and power allocation tactics to maximize energy efficiency. Since the convex optimization problem is still a fractional programming， we apply fractional deformation and Lagrange method to solve the problem of optimizing the maximum throughput of the primary network. Based on the proposed scheme， an off-line optimization problem is proposed to optimize the throughput of the primary user， and we apply generalized the Bender decomposition to solve this problem. Numerical results show that the proposed scheme has an obvious advantage in energy efficiency.

Key words：cognitive radio networks;energy harvesting;relay selection;power allocation

当认知无线网络中主用户（Primary User，PU）收发机之间的信道增益很弱且无法配置多天线时，可以利用协作通信改善网络性能，提高频谱利用率. 当前认知无线网络有三种频谱共享模式：交织模式、衬底模式和覆盖模式[1]. 中继选择以及中继节点的能量供给是协作通信提升网络性能的关键. 文献[2]研究了衬底模式下协作中继选择策略. 文献[3]研究了覆盖模式下的一种资源调度方案. 文献[4]研究了混合衬底、交织模式下的动态频谱感知与访问模型. 中继节点的能量供给对于认知无线网络十分重要，一旦中继节点的能量消耗殆尽，则数据传输将会被迫中断，而能量采集技术为中继……