ITR: Information-Theoretic Limits in Data Storage Systems

数据存储系统是现代信息时代的支柱之一。计算和通信技术的进步以及结合它们的网络已经增加了对高容量数据存储设备的需求，这些应用的范围从生物研究（例如，大量多媒体数据集的可视化和分析）到消费电子产品（例如，高分辨率图像、音频和视频数据在数码相机中的存储）。该研究致力于分析和数值方法，以确定记录通道中可实现的存储密度和数据传输速率的信息理论极限。它还开发和评估可以接近或达到这些限制的调制，编码和信号处理技术。该研究考虑了适用于“磁道导向”存储设备（如磁盘和磁带）的一维信道模型，以及与探索性页面导向和体积存储技术（如全息记录和基于原子力显微镜的热机械记录）相关的高维模型。更具体地说，新的信息理论和算法方法被用于研究记录通道容量的上下限，使用用于垂直和垂直记录系统的分析和基于几何的模型。二维和更高维信道的信息速率的界限也在发展，为了达到接近理论极限的性能，需要新的信号处理和编码方法。在约束调制编码领域，本项目正在探索分析和设计一维约束码，使其更有效地结合调制和纠错功能。二维及更高维度的约束编码理论也在研究中，重点是基本问题，如多维约束系统的表示，约束容量的确定，以及有效的编码和解码算法。基于级联结构，图形码模型和迭代解码的信道编码技术已被证明可以在某些无记忆信道上有效地实现容量。该项目的通道编码组件解决了与这些新的和强大的编码概念的数据存储通道的应用相关的理论和算法问题。特别是，该研究考虑了Turbo和低密度奇偶校验码的设计和性能分析的信道与符号间干扰，消息传递解码器架构的延迟和复杂性之间的权衡，以及新的方法来结合编码，均衡和检测，可以更紧密地接近记录信道容量。该项目还解决了二维记录系统中的信道编码和检测的基本问题。

Data storage systems represent one of the pillars supportingthe modern information age. Advances in computing and communicationtechnologies, and the networks that incorporate them, have increasedthe demand for high capacity data storage devices in applicationsranging from biological research (e.g., the visualization and analysisof massive multimedia data-sets) to consumer electronics (e.g., thestorage of high-resolution image, audio, and video data in digital cameras).The research addressesanalytic and numerical methods for determining the information-theoreticlimits on achievable storage densities and data transfer rates inrecording channels. It also develops and evaluates modulation, coding,and signal processing techniques that can approach or achieve these limits.The research considers both one-dimensional channel models applicableto "track-oriented" storage devices, such as disks and tapes, as well ashigher-dimensional models relevant to exploratory page-oriented andvolumetric storage technologies, such as holographic recording andthermomechanical recording based upon atomic force microscopy.More specifically, new information-theoretic and algorithmic methods arebeing used to study lower and upper bounds on the capacity of recordingchannels, using analytical and empirically-based models for both longitudinaland perpendicular recording systems. Bounds on the information rates ofchannels in two and higher dimensions are also being developed.In order to achieve performance approaching the theoretical limits, newsignal processing and coding methods are required. In the areaof constrained modulation coding, the project is exploring the analysisand design of one-dimensional constrained codes that more efficientlycombine the functions of modulation and error-correction. The nascenttheory of constrained coding in two and higher dimensions is also beinginvestigated, with a focus on fundamental problems, such as representationof multi-dimensional constrained systems, determination of constraintcapacity, and efficient encoding and decoding algorithms.Channel coding techniques based upon concatenation architectures,graphical code models, and iterative decoding have been shown to effectivelyachieve capacity on certain memoryless channels. The channel codingcomponent of this project addresses theoretical and algorithmic problemsassociated with the application of these new and powerful coding conceptsto data storage channels. In particular, the research considers the designand performance analysis of turbo-like and low-density parity-check codesfor channels with intersymbol-interference, the trade-offs between latencyand complexity in message-passing decoder architectures, and new approachesto combining coding, equalization, and detection that can more closelyapproach the recording channel capacity. The project also addressesfundamental problems of channel coding and detection in two-dimensionalrecording systems.