可见光通信中基于FPGA的信号处理技术研究与实现

发布时间：2018-06-27 04:00

本文选题：可见光通信 + RS纠错码　；参考：《北京邮电大学》2014年硕士论文

【摘要】：白光LED作为第四代半导体照明光源,具有寿命长、光照强和能效高的特点,是未来国家大力推广的照明产品。同时,在无线频谱资源日益枯竭的大背景下,可见光波段具有400THz的带宽,而且无需申请频谱资源牌照,不存在电磁干扰,对人体无害等优点。随着LED制造工艺的提升,目前白光LED有着极高的响应灵敏度(微秒级),因此,可以用来传输高速数据。兼顾照明和室内通信的可见光通信成为近几年快速兴起的一种室内无线宽带接入技术,具有重要的研究价值和应用前景。可见光通信(VLC)在国内还处于起步阶段,目前的研究成果主要集中在信道模型分析、调制方式等方面。对于纠错码技术和多接收技术在VLC中应用的研究几乎是一片空白,目前实现VLC系统的科研单位也屈指可数。将纠错码技术和多接收技术引入到VLC系统具有重要的意义。本文提出了一种全双工可见光通信系统模型,阐述了常用的光通信调制技术(OOK、PPM和DPPM)和纠错码技术(Turbo码、LDPC码和RS码)。实现了OOK、PPM调制,通过对比分析,最终选择了2-PPM作为系统调制方式。本文提出了基于PPM调制和RS纠错码的可见光通信系统方案。设计实现了基于伽罗华域GF(28)的乘法器和RS(160,128)纠错码,并利用Modelsim仿真工具验证了RS码的纠错性能。完成了有无RS码情况下的通信系统误码率测试,得出如下结论：使用RS纠错码的BER性能要明显优于无RS纠错码,在保证系统的正常传输误码率低于10-6时,无RS码时,传输距离可达1.5m；而在有RS码时,传输距离可增加至2.2m,效果非常的明显。在距离大于2.4m时,RS码不再起到纠错的作用。本文提出了基于以太网的可见光通信系统方案。设计实现了MII控制器,包括MDIO接口控制、MAC与PHY之间数据传输模块、4B/5B编码和异步FIFO缓存器,并利用Modelsim仿真工具验证了MII接口的正确性。完成了720P高清视频的传输测试,传输速率10Mb/s,通信距离3.2m。本文探讨了多接收技术引入VLC的价值,并对每接收机平均增益与接收机数量的关系、不同接收机下系统误码率分别进行了仿真。考虑到接收机的成本问题和误码率,提出了采用4接收作为最佳接收方案。
[Abstract]:White LED, as the fourth generation semiconductor lighting source, has the characteristics of long life, strong illumination and high energy efficiency. At the same time, under the background of the depletion of wireless spectrum resources, visible light band has the advantages of 400 THz bandwidth and no application for spectrum resource license, no electromagnetic interference, no harm to human body and so on. With the improvement of LED manufacturing process, white LED has high sensitivity (microsecond), so it can be used to transmit high speed data. The visible light communication with both lighting and indoor communication has become a kind of indoor wireless broadband access technology in recent years, which has important research value and application prospect. Visible light communication (VLC) is still in its infancy in China, and the current research results mainly focus on channel model analysis, modulation methods and so on. The research on the application of error-correcting code technology and multi-receiver technology in VLC is almost a blank. At present, there are only a few scientific research institutes to realize VLC system. It is of great significance to introduce the error-correcting code technology and multi-receiver technology into VLC system. In this paper, a full duplex visible light communication system model is proposed. The commonly used optical communication modulation techniques (OOKPPM and DPPM) and error correction codes (Turbo codes LDPC codes and RS codes) are described. OOKPPM modulation is realized, and 2-PPM is selected as the modulation mode by comparison and analysis. In this paper, a scheme of visible light communication system based on PPM modulation and RS error correction code is proposed. The multiplier and RS (160128) error-correcting code based on GF (28) are designed and implemented, and the error correction performance of RS code is verified by Modelsim simulation tool. The BER test of communication system with or without RS code is completed. The conclusion is as follows: the performance of BER using RS error correction code is obviously better than that of no RS code. When the normal transmission error rate of the system is less than 10-6, the BER performance of the communication system without RS code is obtained. The transmission distance can reach 1.5 m, but the transmission distance can be increased to 2.2 m with RS code, which is very effective. When the distance is more than 2.4 m, the RS code will no longer play an error-correcting role. A scheme of visible light communication system based on Ethernet is presented in this paper. The Mii controller is designed and implemented, including the data transmission module 4B / 5B encoding and asynchronous FIFO buffer between the MDIO interface control and PHY. The correctness of the Mii interface is verified by the Modelsim simulation tool. The transmission test of 720P high-definition video is completed, the transmission rate is 10MB / s and the communication distance is 3.2m. In this paper, the value of introducing VLC into multi-receiver technology is discussed, and the relationship between the average gain per receiver and the number of receivers, and the BER of different receivers are simulated. Considering the cost of receiver and bit error rate (BER), 4 receiver is used as the best receiver.
【学位授予单位】：北京邮电大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：TN929.1;TN911.7

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