【摘要】：針對(duì)傳統(tǒng)TCP協(xié)議在無(wú)線網(wǎng)絡(luò)和高帶寬延遲網(wǎng)絡(luò)中的性能下降問題，本文在對(duì)RTT分布模型進(jìn)行研究的基礎(chǔ)上，提出了基于RTT的端到端網(wǎng)絡(luò)擁塞控制方法。 本文首先建立了端到端的網(wǎng)絡(luò)模型，并在此基礎(chǔ)上提出一個(gè)基于Gamma分布的統(tǒng)一的RTT分布模型。通過對(duì)Internet網(wǎng)絡(luò)測(cè)量獲得的RTT數(shù)據(jù)進(jìn)行統(tǒng)計(jì)分析，發(fā)現(xiàn)在網(wǎng)絡(luò)負(fù)載較輕時(shí)RTT服從指數(shù)分布，在網(wǎng)絡(luò)負(fù)載較重時(shí)RTT服從正態(tài)分布。仿真結(jié)果也表明，無(wú)線網(wǎng)絡(luò)在負(fù)載較重時(shí)的RTT服從正態(tài)分布。理論分析表明，在一定的參數(shù)條件下，Gamma分布可以轉(zhuǎn)換為指數(shù)分布或正態(tài)分布，總之，RTT服從Gamma分布。 其次，本文提出了基于統(tǒng)計(jì)過程控制（SPC）方法的端到端網(wǎng)絡(luò)擁塞控制協(xié)議－TCP SPC。該協(xié)議將RTT的變化作為網(wǎng)絡(luò)擁塞狀態(tài)變化的反饋信息，利用SPC方法處理RTT數(shù)據(jù)，判斷網(wǎng)絡(luò)負(fù)載狀態(tài)的變化趨勢(shì)，采取不同的策略調(diào)整擁塞窗口的大小。本文在Qualnet仿真軟件和Linux操作系統(tǒng)中實(shí)現(xiàn)了TCP SPC協(xié)議。實(shí)驗(yàn)和仿真結(jié)果證明，該協(xié)議在保證一定公平性的前提下，可以提高無(wú)線網(wǎng)絡(luò)的吞吐率。 最后，本文將PI控制理論用于網(wǎng)絡(luò)擁塞控制，提出了基于PI控制理論的端到端網(wǎng)絡(luò)擁塞控制協(xié)議－TCP PI。該協(xié)議建立了一個(gè)端到端的虛擬路由器模型，根據(jù)虛擬路由器實(shí)時(shí)隊(duì)長(zhǎng)與目標(biāo)隊(duì)長(zhǎng)的差值，利用PI控制理論計(jì)算發(fā)送端的發(fā)送速率，控制路由器隊(duì)長(zhǎng)。該協(xié)議利用隊(duì)長(zhǎng)的變化作為網(wǎng)絡(luò)擁塞的標(biāo)識(shí)，可以避免無(wú)線錯(cuò)誤丟包對(duì)傳統(tǒng)TCP性能的影響。仿真結(jié)果表明，，該協(xié)議能較好的控制路由器隊(duì)長(zhǎng)，提高無(wú)線網(wǎng)絡(luò)和高帶寬延遲網(wǎng)絡(luò)的吞吐率及網(wǎng)絡(luò)穩(wěn)定性。
[Abstract]:Aiming at the performance degradation of traditional TCP protocol in wireless networks and high bandwidth delay networks, this paper proposes an end-to-end network congestion control method based on RTT based on the research of RTT distribution model. In this paper, an end-to-end network model is established, and a unified RTT distribution model based on Gamma distribution is proposed. Through the statistical analysis of the RTT data obtained from the Internet network measurement, it is found that the RTT service is exponentially distributed when the network load is light, and the RTT service is normal distribution when the network load is heavy. The simulation results also show that the RTT service of the wireless network is normally distributed when the load is heavy. Theoretical analysis shows that under certain parameter conditions, Gamma distribution can be transformed into exponential distribution or normal distribution, in short, RTT distribution is from Gamma distribution. Secondly, this paper proposes an end-to-end network congestion control protocol, TCP SPC., based on Statistical process Control (SPC) method. The protocol takes the change of RTT as feedback information of network congestion state, processes RTT data by SPC method, judges the changing trend of network load state, and adopts different strategies to adjust the size of congestion window. In this paper, the TCP SPC protocol is implemented in Qualnet simulation software and Linux operating system. Experimental and simulation results show that the proposed protocol can improve the throughput of wireless networks on the premise of ensuring certain fairness. Finally, PI control theory is applied to network congestion control, and an end-to-end network congestion control protocol, TCP PI., is proposed based on PI control theory. The protocol establishes an end-to-end model of virtual router. According to the difference between real-time and target length of virtual router, the transmission rate of the sender is calculated by using PI control theory, and the length of the router is controlled. The protocol uses the change of queue length as the symbol of network congestion, which can avoid the influence of wireless error packet loss on the performance of traditional TCP. The simulation results show that the protocol can control the router length and improve the throughput and network stability of wireless networks and high bandwidth delay networks.
【學(xué)位授予單位】：天津大學(xué)
【學(xué)位級(jí)別】：博士
【學(xué)位授予年份】：2014
【分類號(hào)】：TN915.04

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本文編號(hào)：2276237