High Performance Multiple Description Code Design

在多描述（MD）问题中，目标是生成给定数量（比如K）的比特流（即，描述），使得每个比特流可以被解码到可接受的质量，同时更多的比特流彼此细化，从而改善信号重构。MD编码在分组有损（有线或无线）网络上的多媒体信号传输中找到应用，因为当由于严格的延迟约束而不能选择重传时，MD编码确保从丢失中优雅地恢复。其他应用是在分集通信系统，分布式数据存储和多速率组播。 大多数实际的MD码解决两种描述的情况下，而一般K的实际设计是稀缺的，它们的性能是从理论上的最佳距离。另一方面，虽然传统的MD码的设计，以打击描述损失，他们的能力，打击位错误已成为一个副产品。该特征在无线通信中特别有用。然而，利用这一特性的MD码的设计很少受到关注。提出的研究的目的是开发高性能的MD码，具有增加的能力，以恢复从损失和比特错误。这将通过MD设计的高度灵活性，在控制接收到的描述的不同子集的重建质量之间的权衡，并通过建设良好的汉明距离属性的索引分配来实现。 这项研究的一个重要组成部分将是培训高素质的人员。几个研究生将从事这项研究，并将在多媒体编码和通信，信息理论和优化培训;培训，这将使他们准备在信息技术部门的工程或学术生涯。拟议的研究将推进MD码设计领域的知识和理解，开发的技术和见解也将适用于其他源网络编码问题（例如，在鲁棒分布式信源编码）。

In the multiple description (MD) problem, the goal is to generate a given number, say K, of bitstreams (i.e., descriptions) representing a signal, such that each bitstream can be decoded to an acceptable quality, while more bitstreams refine each other improving the signal reconstruction. MD coding finds applications in transmission of multimedia signals over packet lossy (wired or wireless) networks as it ensures graceful recovery from losses when retransmission is not an option due to stringent delay constraints. Other applications are in diversity communications systems, distributed data storage and multirate multicast. Most practical MD codes address the case of two descriptions, while practical designs for general K are scarce and their performance is some distance from the theoretical optimum. On the other hand, while traditionally MD codes were designed to combat description loss, their ability to combat bit errors has emerged as a side product. This feature is especially useful in wireless communications. However, the design of MD codes to take advantage of this property has received little attention. The purpose of the proposed research is to develop high performance MD codes with increased capability to recover from losses and bit errors. This will be achieved through MD designs of high flexibility in controlling the trade-off between the quality of reconstruction for different subsets of received descriptions and through construction of index assignments with good Hamming distance properties. 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; training that will prepare them for an engineering or academic career in the information technology sector. The proposed research will advance the knowledge and understanding in the area of MD code design and the techniques and insights developed will be also applicable to other source network coding problems (for instance, in robust distributed source coding).