LT碼及其在不等差錯保護方案中的研究
發(fā)布時間:2018-05-13 06:41
本文選題:數(shù)字噴泉碼 + LT碼; 參考:《鄭州大學》2017年碩士論文
【摘要】:隨著通信技術和互聯(lián)網(wǎng)絡的不斷發(fā)展,急劇增長的數(shù)據(jù)規(guī)模和日趨多樣的業(yè)務需求對通信系統(tǒng)的服務能力提出了越來越高的要求。數(shù)字噴泉碼是近些年來提出的一類新型前向糾錯編碼方式,具有編譯碼原理簡單、碼速不受限制以及不需要反饋信息等特征,已經(jīng)得到學術界的普遍重視。本文以LT碼為研究對象,主要針對其編碼過程中的度分布函數(shù)及其運用到不等差錯保護中的方案展開研究。論文對噴泉碼的基本原理進行概述,主要涉及其應用的二進制刪除信道模型、編碼過程以及兩種譯碼算法—BP算法和GE算法,仿真對比了LT碼在不同碼字長度條件和采用不同譯碼方法時的譯碼性能。度分布函數(shù)在LT編碼過程中起著關鍵性的作用,論文主要研究了幾類常用度分布函數(shù),其中側(cè)重分析了一種改進型的魯棒孤子分布。在開關度分布的構(gòu)造思想下,提出一種結(jié)合二進制指數(shù)分布和改進的魯棒孤子分布優(yōu)勢的新型開關度分布。仿真結(jié)果顯示在開關點?=0.1時,該分布完全譯碼時所需的編碼數(shù)據(jù)包數(shù)目最少,有效提升了LT碼的譯碼性能,并且具有編譯碼復雜度和仿真時間上的優(yōu)勢。為了解決現(xiàn)有擴展窗噴泉編碼方案中編譯碼復雜程度較高的問題,同時在確保低重要性數(shù)據(jù)的抗誤碼性能要求下,結(jié)合與或樹分析,論文提出一種基于擴展窗噴泉碼的優(yōu)化方案,仿真結(jié)果表明該方案對高重要性(MIB)和低重要性(LIB)信息數(shù)據(jù)的譯碼恢復性能均有一定程度的提高。通過聯(lián)合權(quán)重UEP-LT碼和擴展窗噴泉碼的優(yōu)點,并利用反饋信息對LT碼的編譯碼進程以及對未譯出碼字符號釋放概率的顯著影響,論文設計出一種帶反饋的W-EWF編碼方案,仿真結(jié)果顯示該方案既能加強MIB信息的優(yōu)先傳輸力度,又能保證LIB信息的譯出恢復性能。
[Abstract]:With the continuous development of communication technology and Internet, the rapidly increasing data scale and increasingly diverse business requirements put forward more and more high requirements for the service capability of communication systems. Digital fountain code is a new type of forward error correction coding method proposed in recent years. It has the characteristics of simple encoding and decoding principle, unlimited code speed and no need for feedback information. In this paper, the LT code is taken as the research object, and the degree distribution function in the coding process and the scheme applied to unequal error protection are studied. In this paper, the basic principle of fountain code is summarized, including binary delete channel model, coding process and two decoding algorithms-BP algorithm and GE algorithm. The decoding performance of LT codes under different codeword length conditions and different decoding methods is simulated and compared. Degree distribution function plays a key role in the LT coding process. In this paper, several kinds of commonly used degree distribution functions are studied, in which an improved robust soliton distribution is analyzed. Based on the idea of constructing switch degree distribution, a new type of switch degree distribution combining binary exponential distribution and improved robust soliton distribution is proposed. The simulation results show that when the switching point is equal to 0.1, the minimum number of coded packets is required for the distributed complete decoding, which effectively improves the decoding performance of LT codes, and has the advantages of encoding and decoding complexity and simulation time. In order to solve the problem of high complexity of encoding and decoding in the existing extended window fountain coding scheme, and to ensure the error-resistant performance of low-importance data, combining with or tree analysis, An optimization scheme based on extended window fountain code is proposed in this paper. The simulation results show that the scheme can improve the decoding performance of MIB) and LIB-information data to some extent. By combining the advantages of weighted UEP-LT code and extended window fountain code, and utilizing the feedback information on the encoding and decoding process of LT code and the significant influence on the untranslated word symbol release probability, a W-EWF coding scheme with feedback is designed in this paper. The simulation results show that the proposed scheme can not only enhance the priority transmission of MIB information, but also guarantee the translation and recovery performance of LIB information.
【學位授予單位】:鄭州大學
【學位級別】:碩士
【學位授予年份】:2017
【分類號】:TN911.2
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