光通信研究Issue(3)：36-44,9.DOI:10.13756/j.gtxyj.2024.230077
基于记忆多项式的Volterra混合均衡器设计与研究
Design and Study of Memory Polynomial-based Volterra Hybrid Equalizer
摘要
Abstract
[Objective]The non-linear characteristics of Light Emitting Diodes(LEDs)contribute to the degradation of Bit Error Rate(BER)performance in Visible Light Communication(VLC)systems,particularly in Optical Orthogonal Frequency Division Multiplexing(O-OFDM)systems with high Peak-to-Average Power Ratio(PAPR).A single-stage equalizer based on the Volterra series can handle the high-order non-linear distortions of LEDs with low latency.However,solving the traditional Volt-erra series necessitates multiple integration operations,resulting in the high implementation complexity of the Volterra-based equalizer.Additionally,the single-stage equalizer accumulates errors with limited performance improvements.[Methods]Firstly,to address the issue of high computational complexity in the traditional calculations of the Volterra series,a proposition is made to retain only the high-order power series terms of the various nonlinear terms and kernel coefficients within the Volterra series.This approach,known as the Memory Polynomial-based Volterra Series(MPVS),not only reduces the computational complexity compared to the traditional Volterra series but also enhances the accuracy of nonlinear system modeling by considering all input sig-nals at the current moment.Subsequently,the design of channel equalizer considers the Memory Polynomial-based Volterra(MPV)equalizer and the Memory Polynomial-based Volterra Decision Feedback Equalizer(MPV-DFE).For a single-stage MPV-DFE,if an error occurs in the decision part leading to an incorrect symbol decoding,this error tends to manifest as a consec-utive series of errors,thereby impacting the entire symbol sequence.To mitigate this,a proposal is made to cascade the two non-linear equalizers,MPV and MPV-DFE,forming a hybrid equalizer called MPV+MPV-DFE.The MPV equalizer performs a primary equalization on the LED's nonlinear distortion signal,effectively suppressing a portion of the non-linear distortions and thereby reducing symbol decoding errors in the MPV-DFE.Subsequently,a secondary equalization is carried out by the MPV-DFE,leading to improved suppression of residual nonlinear distortions.[Results]Finally,the effectiveness of the system design was validated using Monte Carlo simulation to analyze the BER.The results demonstrate that compared to the single-stage MPV equalizer and the linear-cascade nonlinear hybrid equalizer(LMS+MPV-DFE),the proposed hybrid equalizer achieves approxi-mately 7 dB and 2 dB Signal-to-Noise Ratio(SNR)gains,respectively,in a 4 Quadrature Amplitude Modulation(QAM)-mod-ulated Asymmetrically Clipped Optical OFDM(ACO-OFDM)system at a BER of 10-4.[Conclusion]In conclusion,the imple-mentation of the MPV equalizer is straightforward,and the cascaded design of the two-stage nonlinear equalizers as a hybrid equalizer enables better mitigation of the LED's nonlinearity.关键词
可见光通信/发光二极管非线性/沃尔泰拉级数/混合后均衡器Key words
VLC/LED nonlinear/Volterra series/hybrid post equalizer分类
信息技术与安全科学引用本文复制引用
贾科军,雷蕾,蔺莹,余彩虹..基于记忆多项式的Volterra混合均衡器设计与研究[J].光通信研究,2024,(3):36-44,9.基金项目
国家自然科学基金资助项目(61461026) （61461026）
甘肃省科技计划资助项目(22JR5RA276,22JR5RA274,23YFGA0062,2022A-215) （22JR5RA276,22JR5RA274,23YFGA0062,2022A-215）
兰州理工大学博士科研启动项目(061903) （061903）
