臺灣博碩士論文加值系統

隨著無線通訊技術快速發展並逐漸在我們日常中普及化，其早已變成我們生活中不可或缺的重要通信方式，但由於可用的無線電頻譜資源有限，可見光通訊技術逐漸嶄露頭角，不但成為未來5G (fifth-generation)無線通訊發展重點關注技術之一。而除了傳輸速度快之外，可見光也可直接當作傳輸介質搭載在燈具上，整合性極高，此特性也恰好搭上物聯網的時代(Internet of things, IoT)，因此良好的可見光通訊品質以及應用是迫切需要的。

市面上可以接收光的接收器有很多，其中手機是最為容易取得而且整合上網需求最大的。本篇論文中，首先我們會介紹互補式金屬氧化物半導體(Complementary metal-oxide-semiconductor, CMOS)感測器所獨特具有的滾動式快門效應，並說明我們如何運用此效應來進行如快速響應矩陣碼(QR條碼)般，利用相機掃描二維圖形來達到簡單的資訊傳輸或儲存；接著，我們會以此為基礎，分別提出可提升傳輸距離和傳輸速度的方法，並透過一系列影像處理的方法使傳輸品質更穩定。

With the rapid development of wireless communications, it is believed that wireless communication using visible light, known as visible light communication (VLC) can become one of the promising candidates for the 5th generation (5G) wireless communication as well as for the internet of things (IOT). VLC can be integrated with the light-emitting-diode (LED)
illuminance systems; hence it can be a value-added service for the lighting industries, and it’s obviously to see the importance of good communication quality and application.

As the mobile phones with embedded complementary-metal-oxide-semiconductor (CMOS) camera become common, using these cameras as VLC receivers (Rxs) can significantly reduce the cost of VLC deployment and increase the user flexibility. In this thesis, we will introduce the rolling shutter effect first, and illustrate the method what we use to build up a communication system. At last, we success to make the data rate can be increased by about two times when compared with previous work, and propose and demonstrate a long-distance visible light signal detection using commercial mobile phone camera.

摘要 i
ABSTRACT ii
致謝 iii
目錄 iv
表目錄 vi
圖目錄 vii
第一章 緒論 1
1-1 前言 1
1-2 研究動機與目的 1
1-3 章節提要 4
第二章 以CMOS感測器作為接收端之通訊系統介紹 5
2-1 前言 5
2-2 基本實驗架構介紹 5
2-2-1 LED傳送端 6
2-2-2 CCD與CMOS影像感測器之介紹 6
2-2-3 CCD與CMOS影像感測器之曝光方式 10
2-2-4 以Rolling shutter effect傳輸訊息之調變 12
2-3 以Rolling shutter effect傳輸訊息之解調 14
2-3-1 解決高光溢出效應問題之影像處理流程 15
2-3-2 同步 17
2-3-3 利用Smoothing做銳利化之影像處理以及資料取樣 20
第三章 提升傳輸速度之方法－Beacon jointed scheme 23
3-1 前言 & 動機 23
3-2 Beacon jointed scheme介紹 24
3-2-1 Tx-Rx之關係 24
3-2-2 Tx-Rx 圓圈模型 25
3-3 Beacon jointed scheme之解調 29
3-3-1 解調流程 29
3-3-2 結果 33
第四章 非直視性(Non-light-of-sight, NLOS)之長距離傳輸 36
4-1 動機 36
4-1-1 基本原理 36
4-1-2 LOS v.s NLOS與實驗設計 38
4-2 實驗架構與解調流程 41
4-2-1 高光溢出效應之處理 42
4-2-2 邏輯1、0的閥值判斷 44
4-2-3 結果 47
第五章 結論與未來發展 51
參考文獻 53
著作列表 55

[1] Haas, Harald, et al. "What is LiFi?." Journal of Lightwave Technology 34.6 (2016): 1533-1544.
[2] Burchardt, Harald, et al. "VLC: Beyond point-to-point communication." IEEE Communications Magazine 52.7 (2014): 98-105.
[3] O'Brien, Dominic C., et al. "Visible light communications: Challenges and possibilities." Personal, Indoor and Mobile Radio Communications, 2008. PIMRC 2008. IEEE 19th International Symposium on. IEEE, 2008.
[4] Roberts, Richard D. "Undersampled frequency shift ON-OFF keying (UFSOOK) for camera communications (CamCom)." Wireless and Optical Communication Conference (WOCC), 2013 22nd. IEEE, 2013.
[5] Soon, Tan Jin. "QR code." Synthesis Journal 2008 (2008): 59-78.
[6] Hao, Tian, Ruogu Zhou, and Guoliang Xing. "COBRA: color barcode streaming for smartphone systems." Proceedings of the 10th international conference on Mobile systems, applications, and services. ACM, 2012.
[7] Danakis, Christos, et al. "Using a CMOS camera sensor for visible light communication." Globecom Workshops (GC Wkshps), 2012 IEEE.
[8] http://kcs.kcjh.ptc.edu.tw/~spt/computer/digital-image/CCD-CMOS.htm\
[9] http://blog.xuite.net/brian923/getter/
[10] http://www.masters.tw/18871/
[11] http://alan594.tian.yam.com/posts/23144912
[12] Chow, Chi-Wai, Chung-Yen Chen, and Shih-Hao Chen. "Enhancement of signal performance in LED visible light communications using mobile phone camera." IEEE Photonics Journal 7.5 (2015): 1-7.
[13] Ji, Peng, et al. "Vehicular visible light communications with LED taillight and rolling shutter camera." Vehicular Technology Conference (VTC Spring), 2014 IEEE 79th. IEEE, 2014.
[14] Luo, Pengfei, et al. "Undersampled phase shift ON-OFF keying for camera communication." Wireless Communications and Signal Processing (WCSP), 2014 Sixth International Conference on. IEEE, 2014.
[15] Luo, Pengfei, et al. "Experimental demonstration of RGB LED-based optical camera communications." IEEE Photonics Journal 7.5 (2015): 1-12.
[16] Liang, Kevin, Chi-Wai Chow, and Yang Liu. "Mobile-phone based visible light communication using region-grow light source tracking for unstable light source." Optics Express 24.15 (2016): 17505-17510.
[17] Rajagopal, Niranjini, Patrick Lazik, and Anthony Rowe. "Visual light landmarks for mobile devices." Proceedings of the 13th international symposium on Information processing in sensor networks. IEEE Press, 2014.
[18] Wang, Wei-Chung, et al. "Long distance non-line-of-sight (NLOS) visible light signal detection based on rolling-shutter-patterning of mobile-phone camera." Optics Express 25.9 (2017): 10103-10108.
[19] Yong heng Dai, and Xuan Tang. "Visual light landmarks for mobile devices High-speed LED-ID reading over large distance based on OCC using rolling shutter camera.
[20] http://blog.sina.com.cn/s/blog_3f549edf0100hk1y.html
[21] Wellner, Pierre D. "Adaptive thresholding for the DigitalDesk." Xerox, EPC1993-110 (1993).
[22] Bradley, Derek, and Gerhard Roth. "Adaptive thresholding using the integral image." Journal of graphics, gpu, and game tools 12.2 (2007): 13-21.