本文選題：深空通信 + 傳輸層協(xié)議��； 參考：《哈爾濱工業(yè)大學(xué)》2014年碩士論文

【摘要】：深空探測是人類在太空活動的主體，是探尋宇宙起源和擴(kuò)展人類未來生存空間的必然舉措。而維系航天探測器與地面通信系統(tǒng)的唯一紐帶就是深空通信系統(tǒng)，，因此深空通信技術(shù)的發(fā)展直接影響著整個深空探測的前進(jìn)方向。在深空探測任務(wù)中所采集到的信息都以文件的形式存儲再發(fā)送，因此文件傳輸協(xié)議的優(yōu)劣直接決定了深空通信系統(tǒng)的性能。 由于深空通信收發(fā)雙方具有極遠(yuǎn)的傳輸路徑以及極高的丟包率，現(xiàn)有的TCP（Transmission Control Protocol）協(xié)議極差，已經(jīng)不能滿足深空通信的基本要求。而CFDP（CCSDS File Protocols）協(xié)議在一些短延時和低丟包率的信道環(huán)境中表現(xiàn)出了優(yōu)良的性能，然而在信道時延及丟包率增加到一定閾值時，CFDP協(xié)議仍需要對丟失數(shù)據(jù)包進(jìn)行多次重傳，文件傳輸時延明顯增加。 經(jīng)過分析論證得出反饋信息的傳輸次數(shù)直接決定了文件傳輸協(xié)議的性能，因此基于前向糾錯技術(shù)的噴泉碼可以引入到文件傳輸協(xié)議之中，這樣就可以減少對丟失數(shù)據(jù)包的反饋。所以結(jié)合研究內(nèi)容，本文針對深空通信環(huán)境的特點(diǎn)提出一種基于LT碼的文件傳輸協(xié)議（Luby Transform based Protocol），解決了高丟包率、長傳輸時延造成反饋次數(shù)增多而引起鏈路性能的下降，減少了文件的傳輸時間，提高通信鏈路的吞吐率。此外在設(shè)計LT-P協(xié)議之前，對可能影響協(xié)議性能的因素進(jìn)行了分析，包括譯碼算法的選擇、度分布函數(shù)的分析以及LT譯碼開銷的估算，并根據(jù)分析結(jié)果給出了相關(guān)建議。 最后通過搭建的深空通信文件傳輸協(xié)議仿真平臺的實(shí)驗(yàn)驗(yàn)證，TCP協(xié)議在單項(xiàng)路徑傳輸時延大于1s的通信場景中表現(xiàn)最差；在單項(xiàng)路徑傳輸時延以及丟包率小于一定閾值時，由于LT-P協(xié)議仍需要發(fā)送一定的額外開銷來保證譯碼的成果，所以CFDP協(xié)議的性能要優(yōu)于LT-P協(xié)議；而在單項(xiàng)路徑傳輸時延較大時，由于CFDP協(xié)議需要對丟包信息進(jìn)行多次反饋重傳，因此CFDP協(xié)議性能明顯下降，LT-P協(xié)議此時表現(xiàn)出了最佳性能。
[Abstract]:Deep space exploration is the main body of human activities in space and is an inevitable measure to explore the origin of the universe and expand the future living space of mankind. The only link between the space probe and the ground communication system is the deep space communication system, so the development of the deep space communication technology directly affects the forward direction of the whole deep space exploration. The information collected in the deep space exploration mission is stored and sent in the form of files, so the performance of the deep space communication system is directly determined by the merits and demerits of the file transfer protocol. Because of the extremely long transmission path and the extremely high packet loss rate, the existing TCP(Transmission Control protocol is extremely poor and can no longer meet the basic requirements of deep space communication. However, CFDP(CCSDS File protocols have good performance in some channel environments with short delay and low packet loss rate. However, when the channel delay and packet loss rate increase to a certain threshold, the CFDP(CCSDS File protocol still needs to retransmit the lost data packets many times. File transfer delay increased significantly. Through analysis and demonstration, it is concluded that the number of times of transmission of feedback information directly determines the performance of file transfer protocol, so the fountain code based on forward error correction technology can be introduced into file transfer protocol, which can reduce the feedback on lost data packets. Therefore, according to the characteristics of deep space communication environment, this paper proposes a file transfer protocol based on LT code, Luby Transform based protocol, which solves the problem of high packet loss rate, long transmission delay and increasing feedback times, which leads to the degradation of link performance. It reduces the transmission time of files and improves the throughput of communication links. In addition, the factors that may affect the performance of LT-P protocol are analyzed, including the selection of decoding algorithm, the analysis of degree distribution function and the estimation of decoding overhead, and the relevant suggestions are given according to the analysis results. Finally, through the experiment of the deep space communication file transfer protocol simulation platform, it is verified that TCP protocol performs the worst in the communication scene where the transmission delay of single path is greater than 1s, and when the transmission delay of single path and the packet loss rate are less than a certain threshold, Because the LT-P protocol still needs to send some extra overhead to ensure the decoding result, the performance of CFDP protocol is better than that of LT-P protocol, but when the transmission delay of single path is large, the CFDP protocol needs to retransmit the packet loss information many times. Therefore, the performance of CFDP protocol obviously drops and the LT-P protocol shows the best performance at this time.
【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】：2014
【分類號】：TN927

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本文編號：1977261