Physically Based Information Science of Magnetic Recording

[406197]奥沙利文华盛顿大学在信息理论和通信系统以及磁信息存储方面都有很强的研究项目，在磁存储系统的信息容量方面进行了卓有成效的合作。这项合作的初步结果表明，磁性存储介质的最终容量界限超过了现有的实践和短期预测近三个数量级。完整存储系统的容量边界反映了这些最终边界，但进一步受到其他系统组件的限制，包括换能器、代码和电子设备。该项目分析了这些限制，并寻求组件和通道的设计规则，以最大限度地利用潜在的能力。这一目标得到三个相互关联的研究活动的支持。这些活动中的第一个涉及存储媒体的建模。迄今为止使用的模型已经理想化，以减少其计算复杂性；它们产生了有价值的定性结果。该项目正在开发一种定量分析，需要更真实的建模，同时仍可计算处理。具体来说，热、空间和动态效应将包括在更精细的媒介和通道模型中。退火算法将被纳入研究这一领域。这将允许理解这个通道的基本限制。从信息容量的角度分析完整存储通道的可能实现是我们研究的主要部分。这样的分析不仅考虑了媒介的特性，还考虑了诸如存储和检索的不对称性、电子学和可存档性等问题。最初的研究集中在计算包括读头在内的简化版本的记录信道的容量。这项工作的一个显著结果是发展了存储介质的物理参数与其容量界限之间的关系和等价。这导致了超高密度存储的新介质设计指南的建议。这些结果是针对嵌入在理想系统中的介质开发的，预计将在现有和预计的技术实现中反映出类似的关系。将在其独特的实验室设施中使用各种介质对等效性进行实验测试。这些研究人员首先通过实验证明，由于局部介质特性，介质噪声具有可重复的成分。这些实验激发了用于磁记录系统分析和设计的介质模型的发展，这导致了利用确定性噪声成分来增加磁记录系统容量的建议。实验是研究的一个组成部分。这个研究小组有理论学家和实验学家密切合作。因此，所得到的模型和结果可以立即与物理系统的测量结果进行比较。支持研究将结合起来，以解决最佳的信号处理方案的设计，为可实现的系统，充分利用现有的组件。设计策略将探索磁性存储信息的新方法，以及非常规的信息处理技术。希望这些结果将广泛适用于其他信息系统；这种将设备物理学与信息科学相结合的方法在该领域是无与伦比的。这种基于物理的信息科学方法将为复杂系统开发新的分析技术，激励新组件和系统的设计，并设计新的信号处理策略来接近计算容量限制。通过这种新颖而不受约束的方法，处理和存储信息的新方法将会出现，从而大大提高存储密度。＊＊＊

9406197 O'Sullivan The existence, at Washington University, of strong programs both in information theory and communications systems, and in magnetic information storage, has resulted in fruitful collaboration on the information capacity of magnetic storage systems. The initial results of this collaboration show that the ultimate capacity bounds of magnetic storage media exceed existing practice and short term projections by nearly three orders of magnitude. The capacity bounds of the complete storage system reflect these ultimate bounds, but are further limited by the other system components, including transducers, codes, and electronics. This project analyzes these limits, and seeks design rules for components and channels to maximize the use of the potential capacity. This objective is supported by three connected research activities. The first of these activities addresses the modeling of storage media. The models used to date have been idealized to reduce their computational complexity; they have yielded valuable qualitative results. The project is developing a quantitative analysis requiring more realistic modeling while still being computationally tractable. Specifically, thermal, spatial and dynamic effects will be included in more refined medium and channel models. Annealing algorithms will be incorporated to examine this area. This will allow understanding of the fundamental limits of this channel. The analysis of possible implementations of a complete storage channel from the viewpoint of its information capacity comprises a major part of our research. Such an analysis accounts not only for the properties of the medium, but also for such issues as asymmetries of storage and retrieval, electronics, and archivability. Initial studies focus on computing the capacity of simplified versions of the recording channel that include the read head. A striking result of this work has been the development of relations and equivalences between the ph ysical parameters of storage media and their capacity bounds. This has led to a proposal of new medium design guides for ultra-high density storage. These results were developed for media imbedded in ideal systems, and are expected to be reflected in similar relations in existing and projected technological realizations. The equivalences will be tested experimentally, using a variety of media, in their unique laboratory facilities. These researchers were the first to demonstrate experimentally that medium noise has a repeatable component due to local medium properties. These experiments motivated the development of medium models for use in magnetic recording system analysis and design, which led to the proposal to exploit that deterministic noise component to increase the capacity of magnetic recording systems. Experiments form an integral part of the research. The research team has theorists working closely with experimentalists. As a result, the models and results derived can immediately be compared to measurements of physical systems. The supporting studies will combine to address the design of optimal signal processing schemes, for realizable systems, that take full advantage of the available components. The design strategies will explore new methods for storing information magnetically, and unconventional information processing techniques. It is hoped that the results will have wide applicability to other information systems; the approach, joining device physics with information science, is unparalleled in the field. This physically-based approach to information science will develop new analysis techniques for complex systems, motivate the design of new components and systems, and design new signal processing strategies to approach the computed capacity limits. Through this novel and unconstrained approach new ways to process and store information will emerge yielding dramatic increases in storage density. ***