近紅外線雷射光(FSO)傳輸性能之分析

在無線網路的應用上，主要是提供無線區域網路(Wireless LAN)及兩定點做無線橋接傳輸的應用，然而在戶外型的無線橋接傳輸上，無非想取代昂貴或不可行的實體線路架設，在光纖時代的來臨，100M甚至Giga bps的傳輸速率已相當普及，已無法在滿足於既有的802.11的網路標準，另一個新的突破性技術-無線光纖雷射傳輸系統FSO(Free-Spac Optics)。由於FSO是透過光線傳輸，可避免無線電波的干擾問題，傳輸速率雖較快，但傳輸的距離較短，且速率亦會隨距離而遞減，同時亦會受天候、遮蔽物的影響。所以在建置時需考慮距離、氣候等環境因素。本篇論文中，最主要是探討近紅外線光無線傳輸性能，利用市面上目前商用之設備分成不同的區域，去做長達六個月實際測量分析，配合中央氣象局的氣象資料，針對此項產品對於氣候因素影響的程度所得到的結論發現：傳輸距離在≦3km時，在未降雨狀態及較差的氣候損失條件下仍可穩定的傳輸，而一旦每小時降雨量大於14.5mm時，設備訊號會接收異常，RSSI低於Sensitivity 100，甚至斷線，已無法滿足客戶的要求。以FSO六個月的測試資料分析，其傳輸可靠度只可達到99.4985%及99.8668%，故建議以FSO來做為備援路由會比較合適。

關鍵字

光無線傳輸；近紅外線雷射光； OOK調變；面射型半導體雷射

並列摘要

Wireless network application is that majorly providing wireless LAN and wireless bridging application between two spots.However, the main reason for outdoor wireless bridge transmission is to replace the expensive and unworkable physical wiring. Traditional 802.11 standard is no more satisfied in fiber-optical era, which 100M and even Giga bps is getting popular. A new cutting edge technology, FSO (Free-Spac Optics), is born to fulfill the needs of high speed transmission. FSO is able to avoid the the radio jam problem, transmission is fast but distance is short. Speed decreases along with increased distance and easy to be affected by buidling and weather as well. Distance and weather are the environmental factors need to be considered during setting up. Infrared optical wireless transmission is the major topic for this essay. Determining its adaption for Taiwan with the method of using equipment in current market in several areas, practically measure and anlyze for 6 months, see how its reliability is and how weather's influence is with weather information from Central Weather Bureau. In rain fall state and worse climate it loses to be still steady transmission very under the terms, and per hour when the rainfall is greater than 14.5mm, the equipment signal will be received unusually, RSSI is lower than Sensitivity 100, even breaks, can't already meet the customer's demand. With the test analysis of six months of FSO, it transmits 99.4985% and 99.8668% that reliability only reaches the following form, is it is it make for is it aid with FSO route can relatively suitable to prepare against to come to propose.

並列關鍵字

Optical wireless ； Near IR Laser ； On-Off-Keying ； VCSEL

參考文獻

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國際替代計量

近紅外線雷射光(FSO)傳輸性能之分析

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