| dc.contributor.advisor | 連耀南 | zh_TW |
| dc.contributor.advisor | Lien, Yao Nan | en_US |
| dc.contributor.author (Authors) | 丁諭祺 | zh_TW |
| dc.contributor.author (Authors) | Ting, Yu Chi | en_US |
| dc.creator (作者) | 丁諭祺 | zh_TW |
| dc.creator (作者) | Ting, Yu Chi | en_US |
| dc.date (日期) | 2010 | en_US |
| dc.date.accessioned | 8-Dec-2010 12:13:00 (UTC+8) | - |
| dc.date.available | 8-Dec-2010 12:13:00 (UTC+8) | - |
| dc.date.issued (上傳時間) | 8-Dec-2010 12:13:00 (UTC+8) | - |
| dc.identifier (Other Identifiers) | G0977530141 | en_US |
| dc.identifier.uri (URI) | http://nccur.lib.nccu.edu.tw/handle/140.119/49478 | - |
| dc.description (描述) | 碩士 | zh_TW |
| dc.description (描述) | 國立政治大學 | zh_TW |
| dc.description (描述) | 資訊科學學系 | zh_TW |
| dc.description (描述) | 97753014 | zh_TW |
| dc.description (描述) | 99 | zh_TW |
| dc.description.abstract (摘要) | 近年來，一個具有壅塞控制機制的傳輸協議DCCP被提出，期能取代UDP成為不可靠傳輸的主流協議。我們以NS-2網路模擬器和實際網路進行實驗，發現DCCP無法與其他傳輸協議公平分享頻寬，因此現行DCCP的設計，尚無法完全取代UDP。此外，目前DCCP以調整封包間隔的方式進行壅塞控制，也不適用於講求時效性的網路服務。本研究首先以實驗證明，當網路情況不佳時，DCCP無法與其他傳輸協議公平的分享頻寬；當使用DCCP傳輸越洋長距離網路電話，如遇頻寬不足時，會因頻寬競爭力較弱而無法維持通話品質。本研究提出可變速率方法(Flexible Bit-rate)調整時效性網路服務的封包大小來進行壅塞控制，在維持一定服務品質之前提下，促進網路的和諧。我們在一個實際網路的實驗環境中評估以UDP、DCCP及可變速率三種方式傳輸網路電話封包的效能，結果顯示透過可變速率方法，能有效降低網路電話的封包遺失率，維持通話品質。 | zh_TW |
| dc.description.abstract (摘要) | With congestion-control ability, Datagram Congestion Control Protocol (DCCP) is expected to replace UDP as a mainstream unreliable transport protocol. But our study found that DCCP is not able to get a fair share of bandwidth under the competition of others transport protocols no matter in NS-2 simulation or real world networking environments. Furthermore, any congestion control protocol that postpones the transmission of packets may not be adequate to support time-sensitive network services. To maintain the quality of time-sensitive network services as well as to be TCP-friendly when facing network bandwidth fluctuation, we propose a Flexible Bit-rate congestion control mechanism for VoIP to adjust their data rate. Our experiments show that Flexible Bit-rate congestion control method could effectively reduce the packet loss rate and to maintain VoIP quality as compared with UDP and DCCP. Furthermore, it can have a much better bandwidth efficiency and adjust better to network fluctuation. | en_US |
| dc.description.tableofcontents | 第一章 緒論 11.1數據壅塞控制協定(DCCP) 21.2 DCCP-BASED VOIP 21.3研究目的與方法 31.4章節安排 4第二章 背景與相關研究 52.1壅塞崩潰 52.2壅塞控制 52.3數據壅塞控制協定(DCCP) 62.4 TCP的壅塞控制 62.4.1 TCP Tahoe和Reno 62.4.2 TCP Vegas 72.4.3 其他版本 TCP 82.5 DCCP的壅塞控制 82.5.1 CCID 2: TCP-Like壅塞控制 82.5.2 CCID 3: TFRC壅塞控制 82.6 VOIP語音封包產生流程 92.6.1 取樣與編碼 102.6.2封包封裝與傳輸 102.6.3影響通話品質的參數 112.7 VOIP通話品質評量指標 112.7.1 MOS 112.7.2 E-Model 122.7 現有改變語音壓縮速率的VOIP壅塞控制機制 13第三章 數據壅塞控制協定頻寬競爭分析 153.1實驗設計 153.2頻寬競爭分析 173.3 VOIP通話品質分析 293.4小結 36第四章 調整封包大小的壅塞控制方法 374.1 設計目標 384.1.1手動調整方法 384.1.2自動調整方法 384.2 BIT-RATE調整演算法 384.2.1壅塞偵測方法 384.2.1降低Bit-rate演算法 404.2.2提升Bit-rate演算法 414.2.3調整Bit-rate範例 41第五章 實驗與效能評估 425.1評估指標 425.2實驗環境 425.3實驗一 435.3.1實驗結果與分析 445.4實驗二 445.4.1實驗結果與分析 455.5實驗三 455.5.1 UDP-Based VoIP實驗結果與分析 465.5.2 DCCP-Based VoIP實驗結果與分析 505.5.3 Flexible Bit-rate VoIP實驗結果與分析 545.5.4三種傳輸方式實驗結果與分析 585.6 小結 62第六章 結論與未來研究 63參考文獻 64 | zh_TW |
| dc.format.extent | 1691026 bytes | - |
| dc.format.mimetype | application/pdf | - |
| dc.language.iso | en_US | - |
| dc.source.uri (資料來源) | http://thesis.lib.nccu.edu.tw/record/#G0977530141 | en_US |
| dc.subject (關鍵詞) | 壅塞控制 | zh_TW |
| dc.subject (關鍵詞) | 可變速率 | zh_TW |
| dc.subject (關鍵詞) | 數據壅塞控制協定 | zh_TW |
| dc.subject (關鍵詞) | 網路電話 | zh_TW |
| dc.subject (關鍵詞) | Congestion Control | en_US |
| dc.subject (關鍵詞) | Flexible Bit-rate | en_US |
| dc.subject (關鍵詞) | DCCP | en_US |
| dc.subject (關鍵詞) | VoIP | en_US |
| dc.title (題名) | 利用可變速率方法賦予網路電話壅塞控制能力 | zh_TW |
| dc.title (題名) | Congestion Control Enabled VoIP by Flexible Bit-rate | en_US |
| dc.type (資料類型) | thesis | en |
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