Motorola

About: Motorola is a company organization based out in Schaumburg, Illinois, United States. It is known for research contribution in the topics: Signal & Communications system. The organization has 27298 authors who have published 38274 publications receiving 968710 citations. The organization is also known as: Motorola, Inc. & Galvin Manufacturing Corporation.

Space-time transmit precoding with imperfect feedback

Abstract: The use of channel feedback from receiver to transmitter is standard in wireline communications. While knowledge of the channel at the transmitter would produce similar benefits for wireless communications as well, the generation of reliable channel feedback is complicated by the rapid time variations of the channel for mobile applications. The purpose of this paper is to provide an information-theoretic perspective on optimum transmitter strategies, and the gains obtained by employing them, for systems with transmit antenna arrays and imperfect channel feedback. The spatial channel, given the feedback, is modeled as a complex Gaussian random vector. Two extreme cases are considered: mean feedback, in which the channel side information resides in the mean of the distribution, with the covariance modeled as white, and covariance feedback, in which the channel is assumed to be varying too rapidly to track its mean, so that the mean is set to zero, and the information regarding the relative geometry of the propagation paths is captured by a nonwhite covariance matrix. In both cases, the optimum transmission strategies, maximizing the information transfer rate, are determined as a solution to simple numerical optimization problems. For both feedback models, our numerical results indicate that, when there is a moderate disparity between the strengths of different paths from the transmitter to the receiver, it is nearly optimal to employ the simple beamforming strategy of transmitting all available power in the direction which the feedback indicates is the strongest.

Feature extraction by non parametric mutual information maximization

Abstract: We present a method for learning discriminative feature transforms using as criterion the mutual information between class labels and transformed features. Instead of a commonly used mutual information measure based on Kullback-Leibler divergence, we use a quadratic divergence measure, which allows us to make an efficient non-parametric implementation and requires no prior assumptions about class densities. In addition to linear transforms, we also discuss nonlinear transforms that are implemented as radial basis function networks. Extensions to reduce the computational complexity are also presented, and a comparison to greedy feature selection is made.

Modulation and coding for linear Gaussian channels

Abstract: Shannon's determination of the capacity of the linear Gaussian channel has posed a magnificent challenge to succeeding generations of researchers. This paper surveys how this challenge has been met during the past half century. Orthogonal minimum-bandwidth modulation techniques and channel capacity are discussed. Binary coding techniques for low-signal-to-noise ratio (SNR) channels and nonbinary coding techniques for high-SNR channels are reviewed. Recent developments, which now allow capacity to be approached on any linear Gaussian channel, are surveyed. These new capacity-approaching techniques include turbo coding and decoding, multilevel coding, and combined coding/precoding for intersymbol-interference channels.

Wireless system protocol for telemetry monitoring

Abstract: A wireless, programmable system for medical monitoring includes a base unit (18) and a plurality of individual wireless, remotely programmable biosensor transceivers (20). The base unit (18) manages the transceivers (20) by issuing registration, configuration, data acquisition, and transmission commands using wireless techniques. Physiologic data from the wireless transceivers (20) are demultiplexed and supplied via a standard interface to a conventional monitor (914) for display. Initialization, configuration, registration, and management routines for the wireless transceivers and the base unit are also described.

Electromigration failure modes in aluminum metallization for semiconductor devices

Abstract: Two wear-out type failure modes involving aluminum metallization for semiconductor devices are described. Both modes involve mass transport by momentum exchange between conducting electrons and metal ions. The first failure mode is the formation of an electrically open circuit due to the condensation of vacancies in the aluminum to form voids. The second is the formation of etch pits into silicon by the dissolution of silicon into aluminum, and the transport of the solute ions down the aluminum conductor away from the silicon-aluminum interface by electron wind forces. The process continues until an etch pit grows into the silicon to a depth sufficient to short out an underlying junction.