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標題: | 工業級無線區域網路環境中連網裝置數量最佳化研究 Optimizing the Number of Connected Devices in the Industrial WiFi Environment |
作者: | Cheng-Feng Lin 林正峰 |
指導教授: | 蔡志宏(Zse-Hong Tsai) |
關鍵字: | 自動化工廠,服務品質,感測裝置,AP佈建, Automated factory,QoS,Sensing device,AP deployment, |
出版年 : | 2017 |
學位: | 碩士 |
摘要: | 隨著工業4.0 的興起,工廠透過感測器、數據蒐集及分析等邁向自動化發展,因此如何在工廠內佈建有限數量AP,並最佳化工廠內的聯網裝置能夠滿足其應用的服務品質要求的數量,變成為一個重要的議題,由於每個裝置的服務品質要求皆不相同,所以本研究將感測裝置依據服務品質要求區分為兩種,一種為高流量感測裝置,具有較高的傳輸流量要求,另一種為延遲敏感感測裝置,具有較高的延遲時間要求。再根據裝置移動性本論文將固定位置的高流量感測裝置稱為主要裝置1,固定位置的延遲敏感裝置稱為主要裝置2,會變動位置的高流量裝置為次要裝置,分別分析不同配置下其服務品質及網路涵蓋。
為了提高滿足服務品質的裝置數量,我們針對一個AP 服務兩種不同服務品質要求的感測裝置時,使用NS-3 進行模擬,並觀察其滿足服務品質的裝置數量間的變化。模擬後發現將一個AP 僅服務一種服務品質要求的同類裝置,能夠獲得較多滿足服務品質要求的裝置數量。本論文也發現將AP 的干擾範圍區分為有效傳輸干擾範圍以及無效傳輸干擾範圍能更細分干擾情況,並可用NS-3 模擬兩種干擾對AP 造成的影響,透過這些實驗設計我們的AP 佈建演算法,並在通道分配中使用最大階級優先之圖形著色演算法以及基於著色之改善優先級演算法進行通道分配,考量同頻及鄰頻干擾產生的影響,優先選擇不會遭遇同頻及鄰頻干擾之通道,減少AP 之間的干擾,即可顯著提升頻譜的使用效率。 本研究最後模擬了不同情境的工廠環境,並比較不同演算法的佈建結果,其中我們的AP 佈建演算法能使AP 涵蓋較多的主要裝置,也能使較多的主要裝置滿足服務品質,並且使得次要裝置能夠與AP 的傳輸時間比率保持在水準之上,並且擁有較佳的適應能力。 With the rise of the industry 4.0, the factory is moving towards automation through the use of sensors, data collection and analysis. How to deploy just a limited number of access points and still optimize the number of devices meeting QoS devices in the factory has become an important technique. Due to the fact that each device has different QoS requirement, this research will divide devices into two groups based on the difference of their QoS requirements. One group is for high throughput devices which have a higher traffic demand, another is for delay sensitive devices which have a more strict latency requirement. According to device mobility, we name the high throughput device with fixed position as primary device 1, the delay sensitive device with fixed position as primary device 2, and call mobile high throughput device the secondary device. And we then analyze the QoS and coverage ratio of these types of devices. In order to increase the number of devices meeting QoS requirements. We use NS-3 to simulate how an access point serves devices with two different kinds of QoS requirements, and we observed the change between number of devices meeting QoS requirement.We found if an access point only serves one kind of devices with the same QoS requirement, it can support more devices meeting QoS requirement. We also divide the interference range into effective transmission interference range and invalid transmission interference range. Using NS-3 we are able to simulate the influence caused by two kinds of interference. Through these experiments, we then design our AP deployment algorithm. We use the graph coloring algorithm with maximum degree first and the Improved Priority Based Coloring Algorithm to implement channel allocation. In order to decrease the interference between access points, we consider the influence caused by either co-channel or adjacent-channel interferences. And then we select those channels which will not experience co-channel or adjacent-channel interferences in the priority list. As a result, we can enhance spectrum usage significantly. Finally, we simulate different factory situations and compare the result of AP deployments with different algorithms. Among them, our AP deployment algorithm can cover more primary devices and assure that more primary devices can meet their QoS requirements. Our AP deployment algorithm also can make the ratio of network coverage between APs and secondary devices at the required level and has better adaptability. |
URI: | http://tdr.lib.ntu.edu.tw/jspui/handle/123456789/67720 |
DOI: | 10.6342/NTU201702079 |
全文授權: | 有償授權 |
顯示於系所單位: | 電信工程學研究所 |
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