DMT Optimality of LR-Aided Linear Decoders for a General Class of Channels, Lattice Designs, and System Models

The work identifies the first general, explicit, and non-random MIMO encoder-decoder structures that guarantee optimality with respect to the diversity-multiplexing tradeoff (DMT), without employing a computationally expensive maximum-likelihood (ML) receiver. Specifically, the work establishes the DMT optimality of a class of regularized lattice decoders, and more importantly the DMT optimality of their lattice-reduction (LR)-aided linear counterparts. The results hold for all channel statistics, for all channel dimensions, and most interestingly, irrespective of the particular lattice-code applied. As a special case, it is established that the LLL-based LR-aided linear implementation of the MMSE-GDFE lattice decoder facilitates DMT optimal decoding of any lattice code at a worst-case complexity that grows at most linearly in the data rate. This represents a fundamental reduction in the decoding complexity when compared to ML decoding whose complexity is generally exponential in rate. The results' generality lends them applicable to a plethora of pertinent communication scenarios such as quasi-static MIMO, MIMO-OFDM, ISI, cooperative-relaying, and MIMO-ARQ channels, in all of which the DMT optimality of the LR-aided linear decoder is guaranteed. The adopted approach yields insight, and motivates further study, into joint transceiver designs with an improved SNR gap to ML decoding.Comment: 16 pages, 1 figure (3 subfigures), submitted to the IEEE Transactions on Information Theor

Rateless Coding for Gaussian Channels

A rateless code-i.e., a rate-compatible family of codes-has the property that codewords of the higher rate codes are prefixes of those of the lower rate ones. A perfect family of such codes is one in which each of the codes in the family is capacity-achieving. We show by construction that perfect rateless codes with low-complexity decoding algorithms exist for additive white Gaussian noise channels. Our construction involves the use of layered encoding and successive decoding, together with repetition using time-varying layer weights. As an illustration of our framework, we design a practical three-rate code family. We further construct rich sets of near-perfect rateless codes within our architecture that require either significantly fewer layers or lower complexity than their perfect counterparts. Variations of the basic construction are also developed, including one for time-varying channels in which there is no a priori stochastic model.Comment: 18 page

A hierarchical structure for automatic meshing and adaptive FEM analysis

A new algorithm for generating automatically, from solid models of mechanical parts, finite element meshes that are organized as spatially addressable quaternary trees (for 2-D work) or octal trees (for 3-D work) is discussed. Because such meshes are inherently hierarchical as well as spatially addressable, they permit efficient substructuring techniques to be used for both global analysis and incremental remeshing and reanalysis. The global and incremental techniques are summarized and some results from an experimental closed loop 2-D system in which meshing, analysis, error evaluation, and remeshing and reanalysis are done automatically and adaptively are presented. The implementation of 3-D work is briefly discussed

Incremental Change in Wills Adjudication

Probate courts must decide which wills are valid and which are not. The traditional law provides courts a straightforward process to make these decisions. If the court determines that a will complies with certain formalities, then the will is valid, but if the court determines that a will does not comply, then it is invalid. This decisionmaking process has been criticized for being overly formalistic. While the traditional law is relatively easy to apply, it places greater importance on the process by which a testator executes a will than on the substance of the testator\u27s intent. Consequently, the traditional wills adjudication process invalidates noncompliant wills that are authentic expressions of testators\u27 intended estate plans. This criticism has led to major reforms being incorporated into the Uniform Probate Code that are designed to make the wills adjudication process more accurate in distinguishing authentic wills from inauthentic wills. Although no state has fully adopted the UPC\u27s comprehensive reform package, few states still cling wholeheartedly to the traditional law. Instead, policymakers in many states have implemented changes that take incremental steps away from the traditional law\u27s formalistic approach to wills adjudication. While the preference of state policymakers for incremental change, rather than for comprehensive reform, is clear, questions remain regarding the merits of these more modest approaches to reform. This Article seeks to better understand why state policymakers might favor partial rather than wholesale change to the wills adjudication process. More importantly, it analyzes whether some incremental changes are preferable to others. Ultimately, by providing a better understanding of the merits and possibilities of incremental change, this Article provides guidance to state policymakers who are wary of comprehensive reform

Incremental Change in Wills Adjudication

Probate courts must decide which wills are valid and which are not. The traditional law provides courts a straightforward process to make these decisions. If the court determines that a will complies with certain formalities, then the will is valid, but if the court determines that a will does not comply, then it is invalid. This decisionmaking process has been criticized for being overly formalistic. While the traditional law is relatively easy to apply, it places greater importance on the process by which a testator executes a will than on the substance of the testator\u27s intent. Consequently, the traditional wills adjudication process invalidates noncompliant wills that are authentic expressions of testators\u27 intended estate plans. This criticism has led to major reforms being incorporated into the Uniform Probate Code that are designed to make the wills adjudication process more accurate in distinguishing authentic wills from inauthentic wills. Although no state has fully adopted the UPC\u27s comprehensive reform package, few states still cling wholeheartedly to the traditional law. Instead, policymakers in many states have implemented changes that take incremental steps away from the traditional law\u27s formalistic approach to wills adjudication. While the preference of state policymakers for incremental change, rather than for comprehensive reform, is clear, questions remain regarding the merits of these more modest approaches to reform. This Article seeks to better understand why state policymakers might favor partial rather than wholesale change to the wills adjudication process. More importantly, it analyzes whether some incremental changes are preferable to others. Ultimately, by providing a better understanding of the merits and possibilities of incremental change, this Article provides guidance to state policymakers who are wary of comprehensive reform

Weighing Vehicles in Motion [1964]

This report describes the construction, installation, testing and performance analysis of three types of dynamic electronic scales; the Taller-Cooper, a commercially developed four load cell scale, the Broke Bridge, an adaptation of a German prototype employing two load cells and the Bean Type Scale, an experimental prototype that uses a pair of instrumented aluminum beams as the weight sensors

Second CLIPS Conference Proceedings, volume 1

Topics covered at the 2nd CLIPS Conference held at the Johnson Space Center, September 23-25, 1991 are given. Topics include rule groupings, fault detection using expert systems, decision making using expert systems, knowledge representation, computer aided design and debugging expert systems