本文選題：空天信息網(wǎng)絡(luò) + H-ARQ��； 參考：《哈爾濱工業(yè)大學(xué)》2015年碩士論文

【摘要】：空天信息網(wǎng)絡(luò)是一種綜合網(wǎng)絡(luò),其涵蓋了多種空基和天基通信系統(tǒng),包括的網(wǎng)絡(luò)節(jié)點有各種通信平臺、飛行器以及不同軌道、不同種類的衛(wèi)星�？仗煨畔⒕W(wǎng)絡(luò)環(huán)境十分復(fù)雜,由于具有時延長、誤碼率高、信道非對稱、帶寬資源有限、高動態(tài)特性等特征,以及承載的業(yè)務(wù)類型具有多樣性,給信息可靠傳輸帶來挑戰(zhàn),因此保障信息的可靠傳輸是空天信息網(wǎng)絡(luò)的關(guān)鍵問題之一。本文針對空天信息網(wǎng)絡(luò)的特點,從點對點鏈路傳輸和端到端網(wǎng)絡(luò)傳輸兩方面研究空天信息網(wǎng)絡(luò)的可靠傳輸問題,提出基于鏈路層和傳輸層跨層優(yōu)化的可靠傳輸方案,在保障信息可靠傳輸?shù)幕A(chǔ)上提高傳輸效率。本文主要研究空天信息網(wǎng)絡(luò)應(yīng)用于大數(shù)據(jù)量、傳輸類型多樣化的通信業(yè)務(wù),針對空天信息網(wǎng)絡(luò)的特點和傳輸?shù)臉I(yè)務(wù)需求,研究基于QoS(Quality of Service,服務(wù)質(zhì)量)保障的可靠傳輸策略。在數(shù)據(jù)鏈路層提出一種基于業(yè)務(wù)類型、網(wǎng)絡(luò)狀況自適應(yīng)調(diào)整的H-ARQ(Hybrid Automatic Repeat Request,混合自動重傳請求)策略,將前向糾錯方法和自動重傳請求技術(shù)結(jié)合起來,保障點到點的可靠傳輸。研究確定了適用于空天網(wǎng)絡(luò)的前向糾錯編碼方案,選擇合適的自動重傳請求協(xié)議,并且分析推導(dǎo)出延時、吞吐量的表達(dá)式,確定對其具有影響的因素,然后根據(jù)業(yè)務(wù)類型、網(wǎng)絡(luò)狀況調(diào)整傳輸業(yè)務(wù)的重傳次數(shù)、前向糾錯編碼參數(shù)來滿足不同業(yè)務(wù)類型對延時、吞吐量的要求。在傳輸層提出對現(xiàn)有的TCP(Transmission Control Protocol,傳輸控制協(xié)議)協(xié)議進行優(yōu)化的方案,用以適應(yīng)空天網(wǎng)絡(luò)的特殊環(huán)境,保障端到端的可靠傳輸。分別設(shè)計了基于優(yōu)先級的慢啟動算法以及基于業(yè)務(wù)類型自適應(yīng)調(diào)整的算法。本文設(shè)計基于優(yōu)先級的慢啟動算法的原理是定義一個新的慢啟動臨界值應(yīng)用于慢啟動階段,開始時采用較大的發(fā)送窗口和增長速度,當(dāng)發(fā)送窗口大于新的臨界值時改變發(fā)送窗口的增長方式,引入一個與往返時延有關(guān)的限制窗口增長速度的因子,使其增長速度減緩,直至平滑的進入擁塞避免階段。此外,本文采用顯示擁塞通知方法來區(qū)分丟包原因,如果是鏈路錯誤丟包,則立即重傳丟失的數(shù)據(jù)包而發(fā)送窗口cwnd按原來的方式增加,不減小發(fā)送窗口。如果是擁塞丟包,則根據(jù)不同的業(yè)務(wù)類型,決定cwnd的窗口減小方式,以及快速恢復(fù)方式,這即是基于業(yè)務(wù)類型自適應(yīng)調(diào)整發(fā)送窗口的設(shè)計思想。最后,利用NS-2構(gòu)建了網(wǎng)絡(luò)仿真環(huán)境,驗證了提出的算法能夠很好的應(yīng)用在空天信息網(wǎng)絡(luò)中,獲得較高的傳輸效率且滿足不同業(yè)務(wù)類型的QoS要求。
[Abstract]:Space-space information network is a kind of integrated network, which covers a variety of space-based and space-based communication systems, including a variety of communication platforms, aircraft and different orbits, different types of satellites. The space-space information network environment is very complex, because of the characteristics of extended time, high bit error rate, asymmetric channel, limited bandwidth resources, high dynamic characteristics, and the diversity of service types, it brings challenges to the reliable transmission of information. Therefore, ensuring the reliable transmission of information is one of the key problems in space-space information network. According to the characteristics of space-space information network, this paper studies the reliable transmission of space-space information network from two aspects of point-to-point link transmission and end-to-end network transmission, and puts forward a reliable transmission scheme based on link layer and cross-layer optimization of transmission layer. The transmission efficiency is improved on the basis of ensuring reliable transmission of information. This paper mainly studies the application of space-space information network to large amount of data and diversified types of communication services. According to the characteristics of space-space information network and the service requirements of transmission, the reliable transmission strategy based on QoS(Quality of Service (QoS) guarantee is studied. In the data link layer, a hybrid automatic retransmission request (H-ARQ(Hybrid Automatic Repeat Request,) strategy based on service type and adaptive network condition adjustment is proposed, which combines forward error correction method with automatic retransmission request technology to ensure reliable point-to-point transmission. In this paper, the forward error correction coding scheme suitable for space-space network is determined, the appropriate automatic retransmission request protocol is selected, the expressions of delay and throughput are deduced, and the factors affecting it are determined. Network conditions adjust the number of retransmissions and forward error correction coding parameters to meet the requirements of delay and throughput for different traffic types. In the transport layer, a scheme of optimizing the existing TCP(Transmission Control protocol is proposed to adapt to the special environment of the space-space network and to ensure the end-to-end reliable transmission. Slow start algorithm based on priority and adaptive adjustment algorithm based on service type are designed respectively. In this paper, the principle of designing a priority-based slow start algorithm is to define a new slow start threshold to be applied to the slow start phase. When the transmission window is larger than the new critical value, the growth mode of the transmission window is changed, and a factor related to round-trip delay is introduced to limit the growth rate of the window, which slows down the growth rate until it smoothly enters the stage of congestion avoidance. In addition, this paper uses the method of displaying congestion notification to distinguish the cause of packet loss. If it is a link error, the lost packet is retransmitted immediately and the transmission window cwnd is increased in the same way without decreasing the transmission window. In case of congestion loss, the window reduction mode and fast recovery mode of cwnd are determined according to different traffic types, which is the design idea of adaptively adjusting the sending window based on traffic type. Finally, the network simulation environment is constructed by using NS-2, which verifies that the proposed algorithm can be well applied in space-space information networks, and achieve higher transmission efficiency and meet the requirements of different traffic types of QoS.
【學(xué)位授予單位】：哈爾濱工業(yè)大學(xué)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2015
【分類號】：TN915.0

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