Constructive approaches for network source coding

网络信源编码是指网络场景中的数据压缩，即存在多于一个发送器或多于一个接收器，或两者兼有。传统的数据压缩技术是为在单个目的地重建单个源的情况而设计的，对于最近出现的复杂网络场景来说是次优的，因此可能会导致带宽资源的浪费。因此，对网络信源编码技术的研究具有重要意义。他们的研究从信息论的角度确立了性能的基本极限，但这样的结果是基于随机编码的论点，这是非建设性的。为了实际使用，需要采取建设性的方法。该研究将针对以下几种网络场景开发新颖而高效的构造性网络信源编码方案：1)相关信源的稳健分布式压缩；2)具有边信息的单发送器和多接收器网络；3)广播信道上的Slepian-Wolf编码。一般的方法将是设计基于具有结构化码本的矢量量化器(VQ)的编码方案。具体地说，我们将使用具有晶格码本的VQ和具有均匀形状码本的形状增益VQ。我们将从用于导出可达到的率失真区域的随机编码方案中获得灵感，如果有的话，或者从相关问题中使用的结构中获得灵感。我们将分析在高速率假设下的渐近性能，并在此基础上设计渐近最优方案。此外，在形状增益VQ的情况下，我们将设计算法来优化有限速率的代码。本研究旨在设计一种能更有效地利用可用带宽并提供服务质量保证的网络信源编码方案。通过实现这一目标，我们的研究将为新技术奠定基础，这些技术有可能在未来与多媒体网络相关的标准的制定中发挥作用。这些技术的实施将为加拿大信息技术公司提供经济机会，并最终将使互联网服务的消费者受益。在理论方面，本文的研究将促进对网络源代码设计和分析领域的认识和理解。所开发的技术和见解也将适用于未来可能出现的其他更复杂的网络信源编码问题。这项研究的一个重要组成部分将是高素质人才的培训。几名研究生将从事这项研究，并将接受多媒体编码和通信、信息理论和优化方面的培训。这项培训将为他们在信息技术部门的工程或学术生涯做好准备。

Network source coding refers to data compression in network scenarios, i.e., where there is more than one transmitter, or more than one receiver, or both. Traditional data compression techniques, devised for the situation where a single source is to be reconstructed at a single destination, are suboptimal for the complex network scenarios that have emerged lately, and thus, may lead to a waste of bandwidth resources. Therefore, the investigation of techniques for network source coding are of great interest. Their study from an information theoretical point of view establishes fundamental limits of performance, but such results are based on random coding arguments, which are nonconstructive. For practical use, constructive approaches are needed. This research will develop novel and efficient constructive network source coding schemes for several network scenarios, as follows: 1) robust distributed compression of correlated sources; 2) networks with one transmitter and more receivers with side information; 3) Slepian-Wolf coding over broadcast channels. The general approach will be to devise coding schemes based on vector quantizers (VQ) with structured codebooks. Specifically, we will employ VQs with lattice codebooks and shape-gain VQs with uniform shape codebooks. We will draw inspiration from the random coding schemes used to derive the achievable rate-distortion regions, where available, or from constructions used in related problems. We will analyze the asymptotical performance under the high rate assumption and, based on this analysis, design asymptotically optimal schemes. Additionally, in the case of shape-gain VQs, we will design algorithms to optimize the codes for finite rates. This research aims at designing network source coding schemes which use the available bandwidth more efficiently and provide a guarantee on the quality of service. By accomplishing this goal our research will lay the foundation of novel technologies, which have the potential of making their way in the development of future standards related to multimedia networking. The implementation of such technologies will present an economic opportunity to Canadian information technology companies, and will ultimately be of benefit to consumers of internet services. On the theoretical side, the proposed research will advance the knowledge and understanding in the area of network source code design and analysis. The techniques and insights developed will be also applicable to other more complex network source coding problems which may arise in the future.An important component of this research will be the training of highly qualified personnel. Several graduate students will be engaged in this research and will be trained in multimedia coding and communications, information theory and optimization. This training will prepare them for an engineering or academic career in the information technology sector.