【摘要】：隨著人類(lèi)探索宇宙的進(jìn)度的加快,人類(lèi)能觸及的宇宙范圍越來(lái)越廣泛,深空通信的通信雙方距離遙遠(yuǎn),由于宇宙中的噪聲特性不同于常規(guī)的無(wú)線通信系統(tǒng),信道模型很復(fù)雜,同時(shí)深空通信是典型的資源受限系統(tǒng),其設(shè)備功率和重量等資源有限,因此深空通信相對(duì)于地面通信系統(tǒng)有其獨(dú)特性。遙遠(yuǎn)的距離使得反饋的差錯(cuò)控制成為不可能,為了滿足深空通信的需求,M.Luby等提出了噴泉碼數(shù)據(jù)傳輸技術(shù)。噴泉碼是一種無(wú)速率刪除碼,在數(shù)據(jù)包長(zhǎng)度很長(zhǎng)時(shí)有著很好的性能,編碼過(guò)程中它持續(xù)地產(chǎn)生編碼數(shù)據(jù)包,根據(jù)對(duì)通信環(huán)境的評(píng)估合理的調(diào)節(jié)發(fā)送的編碼數(shù)據(jù)包的數(shù)量,當(dāng)目的節(jié)點(diǎn)接收到比發(fā)送數(shù)據(jù)包數(shù)量稍多的編碼數(shù)據(jù)包后即可以很高的概率譯碼成功。它的編譯碼算法復(fù)雜度很低,是一種不需要反饋就能保證通信的可靠性的低復(fù)雜度數(shù)據(jù)傳輸機(jī)制,而且經(jīng)過(guò)改進(jìn)的LT碼在多信源單中繼的模型中性能更卓越。本論文從深空通信的背景出發(fā),詳細(xì)介紹了深空通信的信道特點(diǎn)和噴泉碼編譯碼原理,根據(jù)噴泉碼的編碼特點(diǎn)對(duì)噴泉碼進(jìn)行了仿真,并從深空通信的網(wǎng)絡(luò)模型中提取出網(wǎng)絡(luò)中比較簡(jiǎn)單常見(jiàn)的多信源單中繼通信模型。再?gòu)膬尚旁磫沃欣^通信模型出發(fā),通過(guò)對(duì)魯棒孤波分布解卷積對(duì)分布式LT碼展開(kāi)算法研究和性能仿真,得出分布式LT碼的傳輸策略要比LT碼數(shù)據(jù)傳輸策略更為高效,比分開(kāi)傳輸數(shù)據(jù)節(jié)省了一定量的數(shù)據(jù)包。再者,考慮到通信中通常會(huì)有數(shù)據(jù)的優(yōu)先級(jí)的不同,針對(duì)這一實(shí)際情況,對(duì)LT碼的編碼機(jī)制進(jìn)行改進(jìn)對(duì)重要的數(shù)據(jù)包進(jìn)行更加高效可靠的傳輸,并對(duì)其性能進(jìn)行仿真驗(yàn)證,在此基礎(chǔ)上將分級(jí)保護(hù)算法應(yīng)用到多信源單中繼模型中去,得到分布式分級(jí)保護(hù)LT碼,仿真表明其性能比分布式LT碼要更好。最后從分級(jí)保護(hù)中可知LT碼的度分布其實(shí)是有很大的改進(jìn)空間,因此提出幾種不同于魯棒孤波分布的度分布,并對(duì)其性能進(jìn)行仿真,在SF-LT碼的基礎(chǔ)上,對(duì)其對(duì)分布進(jìn)行解卷積并將之應(yīng)用到分布式深空通信模型中去,最后得到具有卓越性能的分布式SF-LT碼。
[Abstract]:With the acceleration of human exploration of the universe, the scope of the universe can be reached more and more widely, and the distance between the two sides of the deep space communication is far away. Because of the noise characteristics in the universe is different from the conventional wireless communication system, the channel model is very complex. At the same time, deep space communication is a typical resource-limited system, and its equipment power and weight are limited, so deep space communication is unique to terrestrial communication system. In order to meet the requirement of deep space communication, M.Luby and others put forward the fountain code data transmission technology because of the long distance which makes the feedback error control impossible. Fountain code is a rateless delete code, which has good performance when the packet length is very long. During the coding process, it continuously produces encoded data packets, and adjusts the number of encoded packets according to the evaluation of the communication environment. When the destination node receives a bit more encoded packets than the number of transmitted packets, it can decode successfully with a high probability. Its complexity is very low, and it is a low complexity data transmission mechanism which can guarantee the reliability of communication without feedback. Moreover, the improved LT code has better performance in the model of multi-source and single-relay. Based on the background of deep space communication, this paper introduces the channel characteristics of deep space communication and the encoding and decoding principle of fountain code in detail, and simulates fountain code according to the coding characteristics of fountain code. The simple and common multi-source single-relay communication model is extracted from the network model of deep space communication. Based on the two-source single-relay communication model, through the research of robust solitary wave deconvolution algorithm and performance simulation of distributed LT code, it is concluded that the transmission strategy of distributed LT code is more efficient than that of LT code data transmission strategy. Than separate transmission of data to save a certain amount of data packets. Furthermore, considering the different priority of data in communication, the coding mechanism of LT code is improved to transmit the important data packets more efficiently and reliably, and its performance is verified by simulation. On this basis, the hierarchical protection algorithm is applied to the multi-source single-relay model, and the distributed hierarchical protection LT code is obtained. The simulation results show that its performance is better than that of the distributed LT code. Finally, the degree distribution of LT code is found to have great improvement space from the hierarchical protection. Therefore, several degree distributions which are different from the robust solitary wave distribution are proposed, and their performance is simulated. Based on the SF-LT code, the degree distribution of the code is simulated. The distribution is deconvolution and applied to the distributed deep space communication model. Finally, the distributed SF-LT codes with excellent performance are obtained.
【學(xué)位授予單位】：電子科技大學(xué)
【學(xué)位級(jí)別】：碩士
【學(xué)位授予年份】：2014
【分類(lèi)號(hào)】：TN927

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本文編號(hào)：2287426