CIF: Small: New inroads into finite-length distributed information coding

这个项目的目标是开发一种新的编码技术来解决构成许多网络的三个基本多用户通信问题：(A)分布式信源编码，(B)多描述编码和(C)广播信道。该项目是基于最近的两项初步调查。前者在分布式信源编码中发现了一种新的编码现象。在后者中，为所有三个问题制定了一个新的统一的代数编码框架，加强了它们之间的联系，从而表明这一新现象也在其他两个问题中发挥作用。众所周知，对于点对点通信问题(信源编码和信道编码)，随着码块长度的增加，性能一直在或多或少地一直提高到无穷大。对于分布式信源编码问题，在多个终端使用相同代码的一种称为量化和分组码的特定技术，结果表明，随着块长度的增加，性能最初提高，达到平台期，然后下降。因此，当码块长度为某一有限值而不是无穷大时，性能最佳。该项目通过开发一种基于这些代码的新框架来构建高效的编码和解码系统，从而解决在一般网络上可靠地传输和处理信息的问题。分析了这些码在分布式信源编码问题中的性能，给出了性能极限的可计算界。这个项目使用这个框架来解决广播频道问题和多描述问题，使用了这三个问题之间存在的基本联系。这个项目还致力于用计算效率高的编码和解码算法进行编码构造，以实现上述编码系统的实际应用。该项目将对(I)不同研究领域之间的思想和概念交流，(Ii)设计和开发下一代通信网络，如ad-hoc无线和传感器网络，以及(Iii)通过将研究进展纳入课程开发计划和努力招收代表不足的少数族裔和女性研究生来培养未来的工程师。

The objective of this project is to develop a new coding technique for three basic multiuser communication problems that form the building blocks of many networks: (a) distributed source coding, (b) multiple description coding and (c) broadcast channel. This project is based on two recent preliminary investigations. In the former, a new coding phenomenon was uncovered in distributed source coding. In the latter, a new unified algebraic coding framework for all three problems was developed that strengthened the connection among them, and thus suggesting that the new phenomenon is also at play in the other two. It is well-known that for point-to-point communication problem (both source coding and channel coding), as the block-length of the code is increased the performance keeps improving more or less all the way to infinity. For the problem of distributed source coding, with a particular class of technique called quantization and binning using identical codes at multiple terminals, it turns out that as the block-length is increased, the performance improves initially, reaches a plateau and then decreases after that. So the best performance is achieved when the block-length of the code is at some finite value but not infinity. This project addresses the problem of reliable transmission and processing of information over general networks by developing a new framework based on these codes to construct efficient encoding and decoding systems. The performance of these codes for the distributed source coding problem is analyzed and computable bounds on the performance limits are provided. This project uses this framework for the broadcast channel problem and the multiple description problem using a fundamental connection that exists among the three problems. This project also pursues code construction with computationally efficient encoding and decoding algorithms toward practical implementation of the coding systems developed above.This project will have an impact on (i) the exchange of ideas and concepts among different research fields, (ii) the design and development of the next generation of communication networks such as ad-hoc wireless and sensor networks, and (iii) education of future engineers by incorporating research advances into a curriculum development program and an effort toward recruitment of underrepresented minority and women graduate students.