系統識別號 U0026-3008201602444100
論文名稱(中文) 以軟體定義無線電技術測量Wi-Fi頻道間干擾對通訊品質的影響
論文名稱(英文) Analysis Adjacent Channel Interference of Wi-Fi using Software Defined Radio
校院名稱 成功大學
系所名稱(中) 電信管理研究所
系所名稱(英) Institute of Telecommunications and Management
學年度 104
學期 2
出版年 105
研究生(中文) 羅乾汶
研究生(英文) Chien-Wen Lo
學號 R96031109
學位類別 碩士
語文別 中文
論文頁數 42頁
口試委員 口試委員-林福林
中文關鍵字 Wi-Fi  IEEE802.11  鄰頻干擾  軟體定義無線電  SDR 
英文關鍵字 SDR  Software Defined Radio  Wi-Fi  IEEE802.11  Adjacent Channel Interference 
中文摘要 Wi-Fi經過了多年的發展已經是個成熟的技術,在多年的發展之後已經有非常好的普及性和生產價格。加上近年來物聯網呼聲不斷,Wi-Fi相關的通訊協定不斷因應各種情況進行改進,預期在未來將成為跨領各種應用情境的通訊技術,並成為物聯網的網路架構之一。由於Wi-Fi是一個容易取得和架設的技術,節點間的情況變化萬千,通訊品質並不容易控制。在不同情況的研究中,鄰頻道干擾一直都是一個重要的研究方向,眾多學者試著找出更好的方法來控制,讓Wi-Fi在各種環境中都可以運作良好,並且在頻譜內容納更多的節點同時使用。
本研究使用軟體定義無線電(Software Defined Radio, SDR)進行實驗,借助SDR的彈性來進行驗證,建立了一個實驗平台系統。我們利用開源的程式碼加以修改,模擬Wi-Fi通訊時的實體層。以控制頻譜距離和干擾的強度來進行實驗,測量出不同的配置下的訊框錯誤率(Frame Error Rate, FER)。進而整理出頻譜的距離和干擾強度的改變對訊框錯誤率造成影響,來與其他相關研究做呼應,本研究的結果有助於解釋其中兩篇相關研究的結果相互牴觸的原因,主要由於鄰頻干擾的強度與頻譜重疊的比例均會影響到通訊品質。因此我們認為事先偵測鄰頻干擾的強度即可適當的利用頻譜重疊來增加頻譜使用率。另外,我們所建立的軟體無線電技術(Software Defined Radio, SDR) 研究平台適合用於相關研究,此平台擁有架設簡便及較低的成本,另外方便電腦做後續處理,相關的研究者可善用此平台進行研究。
英文摘要 Wi-Fi is an established technology that will be part of the network architecture for the Internet of Things, serving as a gateway for local devices. However, the resulting increase in device density will cause serious interference, with negative effects on communication quality. As such, many researchers are working to develop ways to arrange channels and reduce interference. Research has shown that two AP with overlapping spectra cause a decrease in throughput, but two APs using the same spectrum get better throughput. Another research finds that partially overlapping don’t affect the throughput. These different results are because the strength of the interference is different. The current research uses SDR (software-defined radio) to develop an experiment platform in order to find out how signal strength and spectrum overlapping relate to communication quality. The communication quality is evaluated by FER (Frame Error Rate), which is a more direct approach then using throughput or another way. Our results show when the overlapping signal strength affects the communication quality, and thus we defined the largest overlapping rate for different signal strengths in order to keep the FER low. This can be used to provide a tradeoff in high device density environments.
論文目次 摘要 i
目錄 vii
表目錄 ix
圖目錄 x
第一章 緒論 1
1.1 研究背景及動機 1
1.2 研究目的 4
1.3 研究流程 4
第二章 相關研究 6
2.1 軟體定義無線電 6
2.1.1 軟體定義無線電之發展 6
2.1.2 軟體定義無線電之架構 6
2.1.3 硬體裝置 8
2.1.4 GNU Radio 8
2.1.5 OFDM benchmark 11
2.2 IEEE 802.11 11
2.2.1 IEEE 802.11g 11
2.2.2 頻道間隔 12
2.2.3 實體層規格 12
2.3 鄰近頻道干擾 14
2.3.1 IEEE 802.11鄰頻道干擾相關研究 14
2.3.2 小結 16
第三章 研究架構 17
3.1 實驗架構 17
3.2 硬體平台 20
3.3 軟體平台 23
3.3.1 OFDM Benchmark和其修改 23
3.3.2 傳送端發射 23
3.3.3 干擾源發射 24
3.3.4 訊號接收 24
3.3.5 實驗數值的取得和計算 24
3.4 實驗流程 25
3.5 實驗參數 26
第四章 實驗結果 28
4.1 與真實Wi-Fi設備的頻譜比較 28
4.2 信號和干擾的頻譜觀察 29
4.3 星座圖觀察 34
4.4 實驗數據 35
第五章 研究結論 38
5.1 頻道間干擾的影響 38
5.2 軟體定義無線用於干擾研究的可行性 38
5.3 後續研究及建議 38
5.4 研究限制 39
參考文獻 40
附錄一、名詞解釋 42
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