Sub-1GHz 射頻訊號相較於WiFi 或Bluetooth 訊號，有著更低的耗電量與更遠的傳輸距離，使其成為物聯網裝置在感測層傳輸協定的首選。然而，目前各種Sub-1GHz 的傳輸技術在無遮蔽的直線環境下，雖然都有公里級以上的傳輸距離，但是當其使用在室內空間或是有其它干擾訊號的環境時，則需提高發射訊號的功率，以增加接收端的訊號強度，因而影響到耗電量。
除此之外，無線傳輸設備在安裝過程當中，為確保有最佳的傳輸品質，常常需要不斷測試與調整發射與接收端的功率與RSSI 值，因此無形中也耗費了不少人力與時間成本。
本文透過幾種不同環境下的量測實驗，評估這些環境下無線訊號的衰減程度，並以程式控制的方式，在傳輸設備安裝時，能夠自動調整發射功率，以減少重複調整所花費的時間。並且讓裝置隨著RSSI 值的變化，適時的調整發射端的功率，以達到維持良好的訊號品質，或是降低耗電量的目的。

Compared with WiFi or Bluetooth signals, Sub-1GHz RF signals have lower power consumption and longer transmission distance, making them the first choice for IOT devices in the transmission protocol of the sensing layer. However, at present, various Sub-1GHz transmission technologies have a transmission distance of more than kilometer in an unobstructed straight line environment, but when they are used in an indoor space or other environment that interferes with the signal, the transmission signal needs to be increased. The power to increase the signal strength at the receiving end, thus affecting the power consumption.
In addition, during the installation process of the wireless transmission equipment, in order to ensure the best transmission quality, it is often necessary to constantly test and adjust the power and RSSI values of the transmitting and receiving terminals, which incurs a lot of manpower and time costs.
This article evaluates the attenuation of wireless signals in these environments through measurement experiments in several different environments, and uses program-controlled methods to automatically adjust the transmit power during installation of the transmission equipment to reduce the time spent on repetitive adjustments. And let the device adjust the power of the transmitting end timely with the change of RSSI value, in order to maintain the good signal quality, or reduce the purpose of power consumption.

目錄
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 研究動機 1
1.2 研究背景 2
1.3 研究目的 2
第二章 文獻探討 3
2.1 物聯網技術介紹 3
2.1.1 Thread 3
2.1.2 eMTC／NB-IOT 4
2.1.3 LoRa／sigfox／Proprietary 5
2.2 Sub-1GHz訊號特性 6
2.3 RF訊號受環境影響的因素 8
2.4 發射功率與耗電 10
2.5 IEEE 802.11ah標準 11
第三章 研究方法 13
3.1 RF傳輸硬體與軟體 13
3.1.1 Sub-1GHz 傳輸模組 13
3.1.2 實驗設備 16
3.1.3 軟體介紹 19
3.1.4 測試系統介紹 20
3.1.5 RSSI接收訊號強度指示 21
3.2 實驗環境定義 22
3.3 實驗流程與方法 23
3.3.1 實驗流程圖 23
3.3.2 實驗參數設定 24
3.3.3 實驗設備量測 25
第四章 研究結果分析 28
4.1 各環境下 RF 傳輸的平均RSSI值 28
4.1.1 無阻隔測試環境 28
4.1.2 金屬阻隔測試環境 31
4.1.3 樓板阻隔測試環境 33
4.1.4 樓梯間阻隔測試環境 35
4.1.5 WiFi干擾測試環境 37
4.1.6 各場域RSSI綜合比較 41
4.2 自動功率控制 43
4.3 自動功率控制與手動調整比較 50
第五章 結論 51
5.1 研究發現 51
5.2 研究限制 51
5.3 建議 51
參考文獻 52
附錄 54

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