无速率编码及其应用综述

纠错编码技术通过引入冗余增加可靠性,是现代通信的关键技术之一。无速率编码是一类新兴纠错编码,其速率可以根据信道状态自适应改变,编译码算法较为简单,且性能优异,可以适用于不同的应用场景,因此受到了国内外学者和工业界的关注。介绍了4种经典或新兴的无速率编码方案,包括卢比变换(Luby Transform,LT)码、Raptor码、在线喷泉码(OFC)和BATS(Batched Sparse)码。介绍无速率编码的基本原理,通过其发展过程比较不同无速率编码的特点。阐述了这些无速率编码的编译码方法,并简要介绍其最新的研究进展。最后,介绍无速率编码在广播通信及不等差保护、无线传感器网络、车联网、存储以及分布式计算等新老场景中的应用。无速率编码是一种复杂度低、灵活度高的编码,随着新型无速率编码的发展,在未来的分布式系统等场景中将会有更广泛的应用。

Overview of Rateless Codes and Their Applications

Error control codes(ECC),which introduce redundancy to increase reliability,is a key technology of modern communication system.Rateless codes are a new class of ECC which have no fixed code rate.The rate of rateless codes can adaptive to different channel qualities automatically,and the complexity is low for both encoding and decoding,thus it attracts much attention from both researchers and industry.We introduce four rateless codes,including the classic Luby transform(LT)codes and Raptor codes,as well as the emerging online fountain codes(OFC)and batched sparse(BATS)codes.By introducing the advancement of LT codes,we review the development of rateless codes,and explain how the Raptor codes,OFC and BATS codes are improved from LT codes.We describe the basic principles of each rateless codes respectively and compare their characteristics.More specifically,we present the encoding and decoding algorithm of these codes and introduce the state-of-the-art improvements.We also introduce their applications in broadcast communications and unequal error protection,wireless sensor networks,vehicle communications,storage and distributed computing.Rateless codes are a new kind of ECC with low complexity and high flexibility,which will be applied in wider scenarios in the future.