IEEE 802.11ah 於地下物聯網之應用

Abstract

近年來物聯網領域發展蓬勃，許多監控案例中需要使用人工紀錄及分析的傳統方法逐漸被感測器及物聯網取代，諸如降雨量、空氣品質、紫外線指數等等，皆已使用感測器加上物聯網的方式自動化收集資料。地下管線作為智慧城市中與人們生活息息相關的一部份也理所當然地引入了物聯網的監控概念，但在實際應用中大家發現有兩大痛點導致地下管線物聯網的監控成效不佳，其一為功耗問題，在地下管線中無法使用如太陽能板的方式為裝置補充電力，因此在僅使用電池供電的情況下低功耗電路設計尤其重要。其二為訊號傳輸問題，裝置於地下封閉環境中，且有鑄鐵人孔蓋的覆蓋，導致無線訊號無法有效傳出，資料妥善率不容易達標。基於以上兩點，本研究將使用IEEE 802.11ah的技術應用於地下物聯網中，解決電力問題以及訊號傳輸問題這兩大痛點。本研究使用的IEEE 802.11ah（WiFi HaLow）為IEEE標準協會制定之基於Sub 1GHz免授權頻段的一種無線網路標準，旨在提供一種低功耗、長距離的無線區域網。本研究的實驗結果顯示透過低功耗設計與IEEE 802.11ah的特性，本研究成功將電池壽命提高到現行方案的8至10倍，顯著減少了電池更換的頻率，降低了系統運維成本。訊號傳輸穩定性方面實驗證實IEEE 802.11ah在鑄鐵人孔蓋覆蓋下的訊號強度達到-80dbm以上，滿足地下物聯網的需求，配合本研究所設計的傳輸流程，使資料完整性高於99%，確保關鍵監控數據的可靠性，特別是在訊號受阻的地下環境中表現優異。最後本研究基於時間空間資料庫的概念，開發了一套使用者友好的數據分析平台，能夠提供即時的資料視覺化與歷史趨勢分析，協助使用者進行決策，如淤積趨勢監測及異常事件判斷。In recent years, the field of Internet of Things has developed rapidly. In many monitoring cases, traditional methods that require manual recording and analysis have gradually been replaced by sensors and the Internet of Things. For example, rainfall, air quality, ultraviolet index, etc., have all been automatically collected using sensors plus the Internet of Things. As a part of smart cities that is closely related to people's lives, underground pipelines have naturally introduced the concept of Internet of Things monitoring. However, in actual applications, we have found that there are two major pain points that lead to poor monitoring results of underground pipeline Internet of Things. One is the power consumption problem. In underground pipelines, it is impossible to use methods such as solar panels to recharge the device. Therefore, low-power circuit design is particularly important when only using batteries for power supply. The second is the signal transmission problem. The device is located in a closed underground environment and is covered by a cast iron manhole cover, which makes it impossible for the wireless signal to be effectively transmitted and the data availability rate is not easy to meet the standard. Based on the above two points, this study will use IEEE 802.11ah technology to apply to Internet of Underground Things to solve the two major pain points of power problems and signal transmission problems. The IEEE 802.11ah (WiFi HaLow) used in this study is a wireless network standard based on the Sub 1GHz unlicensed frequency band developed by the IEEE Standards Association, which aims to provide a low-power, long-distance wireless local area network. The experimental results of this study show that through low-power design and the characteristics of IEEE 802.11ah, this study has successfully increased the battery life to 8 to 10 times that of the current solution, significantly reducing the frequency of battery replacement and reducing system operation and maintenance costs. The signal transmission stability experiment confirmed that the signal strength of IEEE 802.11ah under the cast iron manhole cover reached above -80dbm, meeting the needs of underground IoT. In conjunction with the transmission process designed by this research institute, the data integrity is higher than 99%, ensuring the reliability of key monitoring data, especially in underground environments where signals are blocked. Finally, based on the concept of spatiotemporal database, this study developed a user-friendly data analysis platform that can provide real-time data visualization and historical trend analysis to assist users in making decisions, such as siltation trend monitoring and abnormal event judgment.