【摘要】：傳統(tǒng)的基于IP地址的傳輸模式存在大量的重復(fù)內(nèi)容傳輸,為此,內(nèi)容中心網(wǎng)絡(luò)(Content-Centric Network,CCN)提出采用數(shù)據(jù)命名路由協(xié)議,通過路由器緩存內(nèi)容減少重復(fù)傳輸,提高傳輸效率。然而,網(wǎng)絡(luò)中緩存容量遠(yuǎn)小于全網(wǎng)內(nèi)容,緩存每一個(gè)經(jīng)過的內(nèi)容會造成極大的緩存冗余和頻繁的緩存替換。因此,如何高效利用緩存資源是內(nèi)容中心網(wǎng)絡(luò)亟需解決的關(guān)鍵問題。本文從緩存系統(tǒng)架構(gòu)、用戶請求和無線接入等角度出發(fā),著重研究內(nèi)容中心網(wǎng)絡(luò)緩存決策問題。本文主要研究工作如下:1.研究用戶請求分布不均衡情況下的緩存決策問題。本文首先提出基于軟件定義內(nèi)容中心網(wǎng)絡(luò)(Software Defined Content Centric Network,SDCCN)的緩存決策系統(tǒng)框架,并對其中的緩存決策問題進(jìn)行描述和難度分析。然后,以最小化所有用戶請求時(shí)延為目標(biāo)建立整數(shù)線性規(guī)劃模型(CDP-ILP)從而提供問題的最優(yōu)解。為了快速求解,提出了三種快速的啟發(fā)式算法——AlgRelax,AlgGreedy,AlgMix。最后,通過自主設(shè)計(jì)的內(nèi)容中心網(wǎng)絡(luò)網(wǎng)內(nèi)緩存系統(tǒng)仿真實(shí)驗(yàn)平臺,實(shí)現(xiàn)內(nèi)容中心網(wǎng)絡(luò)的轉(zhuǎn)發(fā)機(jī)制以及文中提出的算法和已有的緩存策略。從用戶請求總時(shí)延,緩存命中次數(shù),服務(wù)器負(fù)載三個(gè)方面進(jìn)行算法對比,仿真結(jié)果表明提出的緩存決策算法能夠減少用戶請求總時(shí)延,增加緩存命中次數(shù),降低服務(wù)器負(fù)載。2.進(jìn)一步考慮了無線用戶可以選擇接入路由器的情況。同時(shí)優(yōu)化路由器選擇和緩存決策,以最小化用戶請求的總時(shí)延。為此建立二次規(guī)劃模型,并提出一種基于請求相似度的用戶接入算法——AlgUACC。隨后對緩存決策仿真實(shí)驗(yàn)平臺進(jìn)行擴(kuò)展,加入無線用戶接入模塊,實(shí)現(xiàn)基于請求相似度的用戶接入算法以及隨機(jī)接入算法。實(shí)驗(yàn)結(jié)果表明,提出的算法相比隨機(jī)接入算法能夠減少用戶的請求時(shí)延。
[Abstract]:There is a lot of duplicate content transmission in the traditional IP address transmission mode. For this reason, the content Center Network (Content-Centric Network,CCN) proposes a data named routing protocol to reduce the repeat transmission through the content cache of the router. Improve transmission efficiency. However, the cache capacity in the network is much smaller than that in the whole network. Therefore, how to make efficient use of cache resources is a key problem that needs to be solved in content-centric networks. Based on the architecture of cache system, user request and wireless access, this paper focuses on the content-centric network cache decision-making. The main work of this paper is as follows: 1. In this paper, the cache decision problem in the case of uneven distribution of user requests is studied. In this paper, a framework of cache decision system based on software defined content-centric network (Software Defined Content Centric Network,SDCCN) is proposed, and the cache decision problem is described and analyzed. Then, an integer linear programming model (CDP-ILP) is established to provide the optimal solution to the problem, aiming at minimizing the delay of all user requests. In order to solve the problem quickly, three fast heuristic algorithms, AlgRelax,AlgGreedy,AlgMix., are proposed. Finally, the forwarding mechanism, algorithms and cache strategies of the content-centric network are realized by using the self-designed simulation platform of the cache system in the content-centric network. Compared with the three aspects of user request total delay, cache hit times and server load, the simulation results show that the proposed cache decision algorithm can reduce the total delay of user requests and increase the number of cache hits. Lower server load. 2. Further consideration is given to the situation in which wireless users can choose access routers. At the same time, the router selection and cache decision are optimized to minimize the total delay of user requests. In this paper, a quadratic programming model is established, and a user access algorithm based on request similarity, AlgUACC., is proposed. Then the buffer decision simulation experiment platform is extended to add the wireless user access module to realize the user access algorithm based on request similarity and the random access algorithm. Experimental results show that the proposed algorithm can reduce the request delay compared with the random access algorithm.
【學(xué)位授予單位】：南京航空航天大學(xué)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2017
【分類號】：TP393.0

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