臺灣博碩士論文加值系統

近幾年被廣泛地討論的可見光通訊 (Visible Light Communication，VLC) 系統，能同時具備照明與通訊功能，隨著不同的可見光特性 (如有較高的通訊安全、可自由使用的通道頻寬…等) 而有不同的運用，再者因可見光的頻寬與無線電波不同，有利於解決無線電波頻寬不夠的問題，因而開始有討論利用可見光通訊作為Bluetooth、NFC (Near Field Communication)…等近場無線電波通訊的替代方案。
使用行動裝置上所配備的互補式金屬氧化物半導體(Complementary Metal-Oxide-Semiconductor，CMOS) 影像感測器 (Image Sensor)接收可見光訊號，如今即便是低階的手機，也配備高解析度的CMOS影像感測器，不僅具有相當的普遍性，更可降低無線通訊的成本。而CMOS相機的Rolling Shutter Effect可以用於提高傳輸效能，以遠高於相機畫面率 (Frame Rate) 的速率傳輸數據。然而接收裝置的差異會導致傳送效率不彰，為維持傳輸資料的完整性並進一歩提升此系統的傳輸率，本論文的研究方式仍然是以Rolling Shutter Effect所建立的近場可見光通訊系統進行研究，改良接收端的訊號處理方法來達到高效率的傳輸能力。在本論文中，將提供Grayscale Control並改良Contrast Enhancement，實驗結果顯示Grayscale Control機制能有效地將錯誤率降為0，Contrast Enhancement亦可提升灰階值對比度，並提升29%的資料吞吐量，搭配近期的多鏡頭行動裝置之普及，也可討論對應提高傳輸率的概念。

關鍵字: 近場無線可見光通訊、CMOS、Rolling Shutter Effect

Visible Light Communication (VLC) has been widely discussed in recent years. Being able to realize communication processes while performing illumination, several emerging applications of visible light appear such as data transmission over traffic signal and unlimited channel bandwidth. Furthermore, the bandwidth of visible light communication is less limited compared with the radio-based scheme. This property encourages people to develop VLC as one alternate for short-distance communication such as Bluetooth and NFC (Near Field Communication).
With the improvement of Complementary Metal-Oxide-Semiconductor (CMOS), image sensors are able to effectively receive signals of visible light, which can provide not only convenience, but also low-cost design for wireless communication. Nowadays, even the mobile phones with fundamental functions are equipped with CMOS image sensors. Therefore, the rolling shutter effect of the CMOS camera can be applied to improve the transmission rate which is faster than the frame rate of camera. Based on the rolling shutter effect and several signal processing methods, this thesis aims to further improve the transmission rate by increasing the successful data transmission in the scenario of short-distance visible light communication system. The proposed system is constructed with contrast enhancement and grayscale control. In the experiment, the first component can enhance the contrast of image grayscale. Then, the second one can effectively eliminate the error. Eventually, the transmission efficiency can be improved about 29 %.

Key-word: Near Field Communication, CMOS, Rolling Shutter Effect

致謝詞 I
中文摘要 II
Abstract III
目錄 IV
圖目錄 V
表目錄 VII
第1.1節 研究背景與動機 1
第1.2節 相關研究狀況 5
第1.3節 論文架構 10
第2章 相關研究(前期研究與相關開發資訊) 11
第2.1節 可見光通訊技術 11
第2.2節可見光通訊之關鍵元件 14
第2.2.1節CMOS與CCD差別 14
第2.2.2節 Rolling Shutter and Global Shutter 16
第2.3節 螢幕格式與相機解析度 17
第2.4節 可見光通訊調變技術 18
第2.4.1節 On-Off Keying (OOK) 調變 19
第2.4.2節Color-Shift Keying (CSK) 20
第2.5節 Manchester Code 21
第3章 近場可見光系統之改良 22
第3.1節 簡介與系統架構 22
第3.2節 基本技術原理 24
第3.2.1節 Blooming Mitigation 24
第3.2.2節 Smoothing 26
第3.2.3節 Otsu Thresholding 27
第3.3節 Select Condition 29
第4章 實驗結果分析與討論 31
第4.1節 實驗的環境設定 31
第4.2節 模擬分析 32
第4.3節 實驗結果 36
第5章 結論與未來展望 41
參考文獻 42

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