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arXiv 0712.0873cs.ITmath.IT
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无知的代价:边信息对无损信源编码延迟的影响

The price of ignorance: The impact of side-information on delay for lossless source-coding

Cheng Chang, Anant Sahai

摘要:

受加密信源压缩背景的启发,本文考虑了带边信息的无损信源编码的速率、端到端延迟和错误概率之间的一般折衷。端到端延迟的概念通过考虑顺序设置而变得精确,在该顺序设置中,源符号被实时的揭示并且需要在解码器处在某个固定延迟要求内被重构。上界推导出的可靠性函数的延迟时,边信息是已知的解码器,以及当它也是已知的编码器。当编码器并非不知道边信息时(包括当没有边信息时的平凡情况),可以在所有速率下在延迟和错误概率之间具有实质上更好的折衷。这表明,当编码器不知道边信息时,在端到端延迟方面存在无知的基本代价。如果只考虑固定块长度的代码,这种效果是不可见的。这样,信源编码中的边信息起到类似于信道编码中的反馈的作用。虽然本文中的定理是渐近的长延迟和低概率的错误,一个例子是用来表明,这里所描述的定性效果是显着的,即使在短期和中度延迟。

英文摘要:

Inspired by the context of compressing encrypted sources, this paper considers the general tradeoff between rate, end-to-end delay, and probability of error for lossless source coding with side-information. The notion of end-to-end delay is made precise by considering a sequential setting in which source symbols are revealed in real time and need to be reconstructed at the decoder within a certain fixed latency requirement. Upper bounds are derived on the reliability functions with delay when side-information is known only to the decoder as well as when it is also known at the encoder. When the encoder is not ignorant of the side-information (including the trivial case when there is no side-information), it is possible to have substantially better tradeoffs between delay and probability of error at all rates. This shows that there is a fundamental price of ignorance in terms of end-to-end delay when the encoder is not aware of the side information. This effect is not visible if only fixed-block-length codes are considered. In this way, side-information in source-coding plays a role analogous to that of feedback in channel coding. While the theorems in this paper are asymptotic in terms of long delays and low probabilities of error, an example is used to show that the qualitative effects described here are significant even at short and moderate delays.

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

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