网络信息论-清华大学电子工程系.pdf

第七章网络信息论 Network Information Theory 2007年12月26 日 © THU 2007 – All rights reserved 清华大学电子系－张林 7.1 网络信息论概述 INFORMATION THEORY is the conscience of the theory of communication; it has defined the “playing field” within which communication systems can be studied and understood … it constitutes a scientific success story of almost unparalleled proportions to which we pay tribute during this golden anniversary year of its birth. However, information theory has not yet made a comparable mark in the field of communication networks, the sister field and natural extension of communication theory, that is today, and is likely to remain for many years, the center of activity and attention in most information technology areas. Anthony Ephremides, Bruce Hajek, “Information Theory and Communication Networks: An Unconsummated Union,” 1998. © THU 2007 – All rights reserved 2 Ephremides等人认为， 经典信息论不适用于网络的原因主要有以下两点： 经典信息论未考虑信源的突发特性（Bursty） 经典信息论未考虑延时在“容量－误码率”渐近分析中的影响 事实上，很多其他因素也会导致经典信息论在向网络信息 论推广过程中遇到困难。 B :(X ,Y ) 2 2 A :(X ,Y) 1 1 C:(X ,Y) 3 3 E :(X ,Y ) D :(X ,Y ) 5 5 4 4 网络通信模型 © THU 2007 – All rights reserved 3 研究的范式 模型 参考系统 性能极限 模型