An Investigaton of the Interaction Between Codes and Decoding Machines

文章摘要：NCR-9415685，约翰·霍普金斯大学，《码与译码机之间相互作用的调查》，Pi-Collins：这项研究的基本概念是将译码本身作为一个通信问题来研究。电子学已经发展到这样的阶段，其中可以有利地用许多芯片(每个芯片包含数万甚至数十万个门)来换取卫星终端中天线孔径的减小或远程浮标或蜂窝电话中的较低发射机功率。由于两个通信方向上的成本不对称，这些后一种应用能够很好地使用极其强大的编码。例如，在蜂窝电话的情况下，从移动单元到移动单元的链路中的节能比到移动单元的链路中的节能重要得多。基站中的复杂解码器从交流电源中获取电力，可以节省移动发射机中的电池电量。同样，大规模的环境数据收集网络只需要在发射机中包含简单和廉价的编码器；卫星或地面站中的一个解码器就可以为所有这些编码器提供服务。不幸的是，利用一片硅的处理能力即使只是一小部分也是困难的，更不用说包含许多芯片的模块了。困难在于在解码机的不同部分之间提供足够的内部通信。如今，布线连接而不是门数限制了信号处理的复杂性。这项研究给出了当解码引擎被划分为单独的部分时，必须流入和流出解码引擎不同部分的信息量的界限。目前，这些界限仅限于基于移位寄存器的码的维特比译码。这项研究将把这些界限扩展到其他码和译码算法，更重要的是探索允许以最小信息流进行译码的码(基于卷积和通用有限状态机)。用于分析解码器信息流的相同技术也将被应用于分区很重要的其他情况，例如非常大的电路交换机。对解码器信息流的剖析可能会产生具有巨大实用价值的新一代代码，并肯定会深入了解所使用的代码类型的最终限制。today.*****************************************************************************Aubrey M.Bush.项目主任，代理副处长网络和通信研究与基础设施司国家科学基金会

ABSTRACT: NCR-9415685, Johns Hopkins University, "An Investigation of the Interaction Between Codes and Decoding Machines", PI-Collins: The essential concept of this research is to study decoding, itself, as a communications problem. Electronics has advanced to the stage where many chips, each containing tens or even hundreds of thousands of gates, can advantageously be exchanged for a decrease in antenna aperture in a satellite terminal or for a lower transmitter power in a remote buoy or cellular telephone. These latter applications are well able to use extremely powerful coding because of the asymmetry of cost in the two directions of communication. In the case of cellular telephones, for example, power savings are much more important in the link from the mobile unit than in the link to the mobile unit. A sophisticated decoder in the base station drawing power from the AC mains can save battery power in the mobile transmitter. Similarly, a large scale environmental data collection network need incorporate only simple and cheap encoders in the transmitters; a single decoder in a satellite or ground station can service all of these encoders. Unfortunately, exploiting even a small fraction of the processing power of a single piece of silicon is hard, let alone that of a module containing many chips. The difficulty is providing sufficient internal communication among the different parts of the decoding machine. Today, wiring connectivity rather than gate count limits the sophistication of signal processing. This research presents bounds on the amount of information which has to flow in and out of the different sections of a decoding engine when it is partitioned into separate parts. At the moment, these bounds are confined to the Viterbi decoding of shift register based codes. This research will extend these bounds to other codes and decoding algorithms and, more importantly, explore codes (both convolutional and general finite state machine based) which allow decoding with minimum information flow. The same techniques used in analyzing decoder information flow will also be applied to other situations where partitioning is important, e.g., very large circuit switches. Dissecting decoder information flow may result in a new generation of codes of great practical use and will certainly yield insights into the ultimate limits of the type of codes in use today.*****************************************************************************Aubrey M. BushProgram Director, Acting Deputy Divison DirectorDivision of Networking and Communications Research and InfrastructureNational Science Foundation