臺灣博碩士論文加值系統

長期演進技術(LTE)是由3GPP Release 8所定義的高速無線網路的標準，提供下行100Mbps、上行50Mbps。可用頻寬被認為是比較電信營運商在特定區域中的評估指標，大部分文獻皆是用於估測有線網路可用頻寬。針對行動網路可用頻寬估測的研究非常有限，4G LTE可用頻寬的文獻就更少，可能的原因是行動網路可用頻寬變異性高於一般固網可用頻寬。
目前常用的行動網路可用頻寬估測技術是批量傳輸容量(BTC)技術，基本原理是：利用下載或上傳一個大的數據，估測可用頻寬。最大的挑戰是：必須找到適當的檔案大小。如果使用的檔案太小，只是顯示當時負載的吞吐量，不是路徑上最大的可用頻寬。如果使用的檔案太大，將造成網路其他數據傳輸延遲，浪費網路傳輸流量。
因此在本論文中，提出在Android手機運行4G LTE測速平台測試可用頻寬。利用傳輸UDP封包，提出等差或等比公式設定封包大小與間隔，可以測試多種演算法獲得可用頻寬，測試完成後上傳資料庫。利用MySQL結合PHP進行可用頻寬運算並以圖型化介面顯示，測速平台實現多種可用頻寬估測技術。
本論文提出封包串可用頻寬估測方法，利用傳送固定封包大小與間隔的封包串塞滿頻寬，達到網路負載的最大吞吐量測得可用頻寬。封包串間隔一段時間發送，封包串傳送之間不發送其他封包，達到低負載的目的。本論文討論PathChirp可用頻寬估測技術，並提出VPS-PathChirp可用頻寬估測方法。根據模擬結果，封包串可用頻寬估測與批量傳輸容量技術測得可用頻寬相當，只使用批量傳輸容量技術8%測試檔案量即可測得可用頻寬。

Long Term Evolution (LTE) was introduced in 3GPP release 8. LTE provides asymmetric data rate of up to 100 Mbps for downlink and 50 Mbps uplink, respectively. In specific area, available bandwidth is one of the metrics to evaluate the performance among mobile operators. Most of literatures discuss the estimation of available bandwidth in wired networks and researches of estimating available bandwidth in mobile networks is limited, especially in LTE networks. One of the possible reasons is that available bandwidth in mobile networks is very random and unstable in comparison with in wired networks.
Bulk transfer capacity (BTC) technique is commonly used to estimate available bandwidth in mobile networks. It measures available bandwidth by the way of downloading or uploading a bulk of data file. Its challenge is to find a suitable value of file size. If a smaller bulk of data file is used, the throughput of current load is measured, instead of maximum available bandwidth. On the other hand, if a larger bulk of data file is used, extra network delay will be introduced.
In this thesis, the available bandwidth in LTE networks is measured by applying Android smart phones. The use of arithmetic or geometric formula to set the packet size as well as transmission gap of UDP packets in packet trains is proposed. A test platform is set up to evaluate a variety of existing algorithms for measuring available bandwidth, and it can also be used to upload measurement data into a MySQL database.
The performance of using packet trains which consist of separated, fixed-sized packets are evaluated, where packet trains are designed to fill up the 4G LTE bandwidth. The performance of existing PathChirp method is also evaluated and a modified method with variable packet size is proposed. The measurement results show that the value of the available bandwidth estimated by packet trains method is close to that estimated by BTC method, however, the quantity of data used by packet trains method is less than 8% than that used by BTC method.

摘要 I
ABSTRACT II
誌謝 IV
目錄 V
圖目錄 VII
表格目錄 IX
第一章 緒論 1
1.1可用頻寬（Available Bandwidth） 1
1.2 LTE標準 6
1.3 Android簡介 8
1.4可用頻寬探測技術分類與架構 11
1.5研究動機與目的 15
1.6論文架構 16
第二章　相關研究 17
2.1主動式探測技術以封包數量分類 17
2.2 主動探測技術以模型分類 20
2.2.1間隙模型 20
2.2.2速率模型 21
2.3 4G LTE可用頻寬估測 23
第三章　4G LTE測速平台 24
3.1測試平台架構 24
3.2測試平台變數定義 26
3.2.1傳送端變數定義 26
3.2.2接收端變數定義 27
3.2.3傳送封包格式與組成結構 28
3.2.4 4G LTE網路速率測試設定 30
3.3測試平台程式流程圖 32
3.3.1下載程式 32
3.3.2上傳程式 37
3.3.3資料庫架構 42
3.4 提出可用頻寬估測方法 44
3.4.1批量傳輸容量技術 44
3.4.2封包串可用頻寬估測 45
3.4.3 PathChirp可用頻寬估測技術 46
3.5 4G LTE測速平台可用頻寬分析程式 53
第四章　模擬實驗與分析 56
4.1測試封包串可用頻寬量測與分析 56
4.2測試VPS-PathChirp可用頻寬估測 60
4.3比較各種量測與估測方法 62
第五章 結論與未來工作 66
參考文獻 67

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