基于OFDM的室内可见光通信关键技术研究

发布时间：2018-08-22 10:53

【摘要】：基于LED的室内可见光通信技术(VLC)可以同时实现室内照明和无线通信功能,因此得到了国、内外科研工作者的广泛关注。由于VLC技术受限于LED芯片本身的低调制带宽和由多径效应诱发的码间干扰等问题,本文提出了一系列基于正交频分复用(OFDM)调制的可见光通信系统的改进方案。OFDM调制技术不仅可以实现高效的频谱利用率,还可以有效地对抗室内多径效应产生的码间干扰,进而保障了室内可见光通信系统的稳定性。在国家留学基金委的资助下,本文的部分实验工作是在英国诺森比亚大学Zabih(Fary)Ghassemlooy教授的光通信实验室完成的。本文主要工作总结如下:1.提出一种基于级联码和频域信道补偿的可见光O-OFDM系统。仿真结果显示,本文提出的方案相对于传统的O-OFDM系统,在相同的误码率10-3的条件下,可以获得~3dB的信噪比增益,保障了可见光通信系统对室内信道响应的鲁棒性。2.提出一种针对室内可见光通信系统非直射链路(NLOS)的自适应信道估计方案。由仿真的均方误差(MSE)和误码率(BER)结果可以看出,本文提出的自适应信道估计方案在高、低信噪比区间都具有很好的估计性能,特别是在高信噪比区间,基于正交匹配追踪(OMP)的信道估计算法可以实现接收信号MSE的改进超过10dB,为NLOS链路下的室内可见光通信信道估计提供了一种新颖的设计方案。3.提出一种基于高斯模糊的O-OFDM系统的峰均值功率比(PAPR)抑制方案。仿真结果表明,对于高斯模糊处理后ACO-OFDM与理想的ACO-OFDM相比,在BER为10-4的情况下,应用OMP恢复算法,可以得到~6 dB的PAPR改进,只需要~2 dB额外SNR处罚,信号的重构误差低于0.1;对于DCO-OFDM信号,应用基追踪(BP)重构算法与理想的DCO-OFDM相比,在BER为10-4的情况下,SNR处罚小于0.1dB,从而为OFDM系统的PAPR抑制问题提供了一种新的解决方案。4.提出一种基于PWM的O-OFDM混合调制方案。仿真和实验结果表明,在相同的实验条件下,与传统的ACO-OFDM系统相比,本文提出的混合调制方案具有更低的PAPR、更高的亮度等级、更低的误码率和更强的抗LED非线性的能力,证明了OFDM-PWM的混合调制算法的优势和应用前景。
[Abstract]:Indoor visible light communication technology based on LED (VLC) can realize indoor lighting and wireless communication functions at the same time. Because the VLC technology is limited by the low-key bandwidth of the LED chip and the inter-symbol interference induced by the multipath effect, In this paper, a series of improved schemes for visible light communication systems based on orthogonal frequency division multiplexing (OFDM) modulation are proposed. The OFDM modulation technology can not only achieve efficient spectrum efficiency, but also effectively resist inter-symbol interference caused by indoor multipath effect. Thus, the stability of indoor visible light communication system is guaranteed. Part of the experiment is done in the Optical Communication Laboratory of Professor Zabih (Fary) Ghassemlooy of the University of Northumbria, England, with the support of the National Fund for study abroad. The main work of this paper is summarized as follows: 1: 1. A visible light O-OFDM system based on concatenated codes and frequency domain channel compensation is proposed. The simulation results show that compared with the traditional O-OFDM system, the proposed scheme can obtain a SNR gain of 3 dB at the same bit error rate (10-3), which ensures the robustness of the visible-light communication system to the indoor channel response. This paper presents an adaptive channel estimation scheme for (NLOS) of indoor visible light communication systems. The simulation results of mean square error (MSE) and bit error rate (BER) show that the proposed adaptive channel estimation scheme has good performance in both high and low SNR range, especially in high SNR range. The channel estimation algorithm based on orthogonal matching tracking (OMP) can realize the improvement of received signal MSE over 10 dB, which provides a novel design scheme for indoor visible light channel estimation under NLOS link. A (PAPR) suppression scheme for O-OFDM system based on Gao Si fuzzy is proposed. The simulation results show that, compared with the ideal ACO-OFDM, when the BER is 10 ~ (-4), the PAPR can be improved by using the OMP recovery algorithm, and only 2 dB extra SNR penalty is needed. The reconstruction error of the signal is less than 0.1. For the DCO-OFDM signal, compared with the ideal DCO-OFDM, the penalty is less than 0.1 dB when the BER is 10-4, which provides a new solution to the PAPR suppression problem of OFDM system. A O-OFDM hybrid modulation scheme based on PWM is proposed. The simulation and experimental results show that the proposed hybrid modulation scheme has lower ACO-OFDM, higher brightness level, lower bit error rate and stronger ability to resist LED nonlinearity than the traditional ACO-OFDM system under the same experimental conditions. The advantages and application prospect of OFDM-PWM hybrid modulation algorithm are proved.
【学位授予单位】：吉林大学
【学位级别】：博士
【学位授予年份】：2016
【分类号】：TN929.1

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