diff --git a/bachelor-thesis.pdf b/bachelor-thesis.pdf index c1d6ac2..72cb898 100644 Binary files a/bachelor-thesis.pdf and b/bachelor-thesis.pdf differ diff --git a/data/abstract.tex b/data/abstract.tex index 6844409..dbd654f 100644 --- a/data/abstract.tex +++ b/data/abstract.tex @@ -3,37 +3,27 @@ % 中英文摘要和关键字 \begin{abstract} - 论文的摘要是对论文研究内容和成果的高度概括。 - 摘要应对论文所研究的问题及其研究目的进行描述,对研究方法和过程进行简单介绍,对研究成果和所得结论进行概括。 - 摘要应具有独立性和自明性,其内容应包含与论文全文同等量的主要信息。 - 使读者即使不阅读全文,通过摘要就能了解论文的总体内容和主要成果。 + 跨域覆盖网络需要为用户提供稳定的低延迟、高带宽和低丢包传输服务的同时降低运营成本。传统方案通常依赖专线链路保证服务质量,但专线成本较高。已有链路调度方法尝试在公网质量较好时使用公网分流,但实际测量表明,公网链路质量下降时段往往与用户流量高峰重合,难以有效削减专线峰值成本。已有端到端冗余编码方法能够缓解丢包影响,但未区分不同链路片段的质量差异,容易在质量良好的片段上引入额外带宽开销。 - 论文摘要的书写应力求精确、简明。 - 切忌写成对论文书写内容进行提要的形式,尤其要避免“第 1 章……;第 2 章……;……”这种或类似的陈述方式。 + 针对上述问题,本文提出一种面向跨域公网覆盖网络的分段链路质量修复方法。该方法在全公网互联的前提下,仅对低质量链路片段启用前向纠错编码。本文设计了交织XOR分组编码方案,以承载各类数据流并降低连续丢包的影响;建立三状态丢包信道模型,根据解码端上报的丢包统计动态选择编码参数;同时设计基于PI控制器的输出速率控制机制,缓解FEC解码按组恢复导致的突发输出问题。 - 关键词是为了文献标引工作、用以表示全文主要内容信息的单词或术语。 - 关键词不超过 5 个,每个关键词中间用分号分隔。 + 本文使用Rust语言实现了原型系统,并在模拟跨域低质量链路的实验环境中进行验证。实验结果表明,本文方法能够正确识别低质量链路片段并启用FEC修复,在无丢包链路片段上保持普通转发。在0至~\SI{2}{\percent}链路丢包率范围内,与直接转发方案相比,本文方法最高达到约3.6倍吞吐提升,验证了分段链路质量修复方法的有效性。 % 关键词用“英文逗号”分隔,输出时会自动处理为正确的分隔符 \thusetup{ - keywords = {关键词 1, 关键词 2, 关键词 3, 关键词 4, 关键词 5}, + keywords = {覆盖网络, 前向纠错编码, 公网链路优化, 链路质量修复}, } \end{abstract} \begin{abstract*} - An abstract of a dissertation is a summary and extraction of research work and contributions. - Included in an abstract should be description of research topic and research objective, brief introduction to methodology and research process, and summary of conclusion and contributions of the research. - An abstract should be characterized by independence and clarity and carry identical information with the dissertation. - It should be such that the general idea and major contributions of the dissertation are conveyed without reading the dissertation. + Cross-domain overlay networks need to provide users with stable low-latency, high-bandwidth, and low-loss transmission services while reducing operational costs. Traditional approaches usually rely on dedicated links to guarantee service quality, but such links are expensive. Existing traffic scheduling methods try to offload traffic to public Internet links when their quality is good. However, real-world measurements show that quality degradation of public Internet links often overlaps with user traffic peaks, making it difficult to effectively reduce the peak bandwidth cost of dedicated links. Existing end-to-end redundancy coding methods can mitigate packet loss, but they do not distinguish quality differences among individual link segments and may introduce unnecessary bandwidth overhead on high-quality segments. - An abstract should be concise and to the point. - It is a misunderstanding to make an abstract an outline of the dissertation and words “the first chapter”, “the second chapter” and the like should be avoided in the abstract. + To address these problems, this thesis proposes a segment-level link quality repair method for cross-domain public-Internet overlay networks. Under an all-public-Internet interconnection setting, the method applies forward error correction only to low-quality link segments. It consists of three key components. First, an interleaved XOR block code generates independent repair packets and spreads burst losses across different recovery groups, making the scheme suitable for diverse traffic flows. Second, a three-state packet loss channel model estimates link conditions from decoder-side loss statistics and guides the adaptive selection of coding parameters. Third, a PI-controller-based pacer smooths the bursty packet output introduced by group-based FEC recovery before the packets are delivered to upper-layer protocols. - Keywords are terms used in a dissertation for indexing, reflecting core information of the dissertation. - An abstract may contain a maximum of 5 keywords, with semi-colons used in between to separate one another. + This thesis implements a prototype system in Rust and evaluates it in an experimental environment that emulates low-quality cross-domain links. The results show that the proposed method correctly identifies low-quality link segments and enables FEC repair on them, while keeping normal forwarding on loss-free segments. With link loss rates from 0 to \SI{2}{\percent}, the proposed method achieves up to about 3.6x throughput improvement compared with direct forwarding, demonstrating the effectiveness of segment-level link quality repair. % Use comma as separator when inputting \thusetup{ - keywords* = {keyword 1, keyword 2, keyword 3, keyword 4, keyword 5}, + keywords* = {overlay network, forward error correction, public Internet link optimization, link quality repair}, } \end{abstract*}