Improved Cross-Entropy-Based Tone Injection Scheme With Structured Constellation Extension Design for PAPR Reduction of OFDM Signals
Improved Cross-Entropy-Based Tone Injection Scheme With Structured Constellation Extension Design for PAPR Reduction of OFDM Signals
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DOI：
10.1109/tvt.2017.2780119
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发表时间：
2018-04-01
影响因子：
6.8
通讯作者：
Li, Zan
中科院分区：
文献类型：
--
作者：
Wang, Wei;Hu, Meixia;Li, Zan
将交叉熵（CE）方法应用于调音注入（TI），可以有效地降低正交频分复用（OFDM）信号的峰均功率比（PAPR），大大节省了复杂度。然而，CE方法作为一种基于群体的搜索方法，需要大量的样本才能找到高质量的解，这意味着更高的复杂度和更长的收敛时间。为了在降低算法复杂度的同时获得较好的PAPR性能，本文提出了一种改进的基于CE的TI方案。首先，设计了矩形正交调幅的结构化扩展星座，以提供更大的自由度。通过合理的参数选择，所提出的扩展星座可以提供更大的设计灵活性，并在自由度和功率增加之间实现更好的权衡。然后，通过分析子载波候选种群对传统基于CE的TI方案的影响，导出了确定子载波候选种群大小的显式表达式。并且，根据裁剪信号所携带的先验信息，选择合适的候选子载波。最后，提出了一种改进的基于CE的TI方案，该方案有效地提高了解的质量，大大加快了收敛速度。仿真结果表明，与传统的基于CE的TI方案相比，改进的基于CE的TI方案在PAPR、误码率、功耗增加和复杂度方面都有很大的提高。
The application of the cross entropy (CE) method to tone injection (TI) can make the peak-to-average power ratio (PAPR) of the orthogonal frequency division multiplexing (OFDM) signals reduced efficiently with great complexity savings. However, as a population-based search method, the CE method requires large samples to find a high-quality solution, which means higher complexity and more time consuming concerning convergence. To reduce the complexity while achieving promising PAPR performance, an improved CE based TI scheme is proposed in this paper. First, a structured extended constellation for rectangular quadrature amplitude modulation is designed to provide more freedom degrees. With proper parameter selection, the proposed extended constellation can offer more design flexibilities and achieve a better tradeoff between freedom degree and power increase. Then, by analyzing the impact of the subcarrier candidate population on the conventional CE based TI scheme, we derive an explicit expression for the determination of the size of the subcarrier candidate population. And, based on the prior information carried by the clipping signal, proper candidate subcarriers are selected. Finally, an improved CE based TI scheme is proposed, which can efficiently enhance the solution quality and greatly accelerate the convergence speed. Simulation results demonstrate that the improved CE based TI scheme achieves great improvements on the performance of PAPR, bit error rate, power increase and complexity compared with the conventional CE based TI scheme.