Vahid Tarokh

Journal article Computer Methods in Applied Mechanics and Engineering · March 1, 2026 Partial differential equations (PDEs) are fundamental to modeling complex physical phenomena across scientific disciplines. While operator learning offers a promising alternative to conventional PDE solvers, it generally requires substantial high-fidelity ... Full text Cite

Asymptotically optimal change detection for unnormalized pre- and post-change distributions

Journal article Sequential Analysis · January 1, 2026 This paper addresses the problem of detecting changes when only unnormalized pre- and post-change distributions are accessible. This situation happens in many scenarios in physics, such as in ferromagnetism, crystallography, magneto-hydrodynamics, and ther ... Full text Cite

Cross-subject mapping of neural activity with restricted Boltzmann machines.

Journal article Frontiers in computational neuroscience · January 2026 Subject-to-subject variability is a common challenge in generalizing neural data models across subjects, discriminating subject-specific and inter-subject features in large neural datasets, and engineering neural interfaces with subject-specific tuning. Wh ... Full text Cite

Conditional Score Learning for Quickest Change Detection in Markov Transition Kernels

Journal article IEEE Transactions on Signal Processing · January 1, 2026 We address the problem of quickest change detection in Markov processes with unknown transition kernels. The key idea is to learn the conditional score ${}_{{y}}{log} {p}{(}{y}{|}{x}{)}$ directly from sample pairs ${(}{x},{y}{)}$, where both ${x}$ and ${y} ... Full text Cite

Indiscriminate disruption of conditional inference on multivariate Gaussians

Journal article European Journal of Operational Research · November 16, 2025 The multivariate Gaussian distribution underpins myriad operations-research, decision-analytic, and machine-learning models (e.g., Bayesian optimization, Gaussian influence diagrams, and variational autoencoders). However, despite recent advances in advers ... Full text Cite

Deep generalized Green's function

Journal article Journal of Computational Physics · October 15, 2025 The Green's function has ubiquitous and unparalleled usage for the efficient solving of partial differential equations (PDEs) and analyzing systems governed by PDEs. However, obtaining a closed-form Green's function for most PDEs on various domains is ofte ... Full text Cite

Neural operators from the Cole–Hopf transformation: Leveraging relations between PDEs for efficient operator learning

Journal article Computer Methods in Applied Mechanics and Engineering · September 1, 2025 Partial differential equations (PDEs) constitute the primary theoretical tool to model complex physical phenomena across diverse scientific disciplines, from materials science to fluid dynamics. While (physics-informed) operator learning approaches have em ... Full text Cite

Black-box Optimization of CT Acquisition and Reconstruction Parameters: A Reinforcement Learning Approach.

Journal article Proc SPIE Int Soc Opt Eng · February 2025 Protocol optimization is critical in Computed Tomography (CT) for achieving desired diagnostic image quality while minimizing radiation dose. Due to the inter-effect of influencing CT parameters, traditional optimization methods rely on the testing of exha ... Full text Link to item Cite

Understanding and Robustifying Sub-domain Alignment for Domain Adaptation

Journal article Transactions on Machine Learning Research · January 1, 2025 In unsupervised domain adaptation (UDA), aligning source and target domains improves the predictive performance of learned models on the target domain. A common method-ological improvement in alignment methods is to divide the domains and align sub-domains ... Cite

Robust Score-Based Quickest Change Detection

Journal article IEEE Transactions on Information Theory · January 1, 2025 Methods in the field of quickest change detection rapidly detect in real-time a change in the data-generating distribution of an online data stream. Existing methods have been able to detect this change point when the densities of the pre- and post-change ... Full text Cite

An Information-Theoretic Lower Bound on the Generalization Error of Autoencoders

Journal article Transactions on Machine Learning Research · January 1, 2025 Quantifying the limitations of classical neural network architectures is a critically underexplored area of machine learning research. Deriving lower bounds on the optimal performance of these architectures can facilitate improved neural architecture searc ... Cite

Neuron synchronization analyzed through spatial-temporal attention.

Journal article Frontiers in computational neuroscience · January 2025 Neuronal synchronization refers to the temporal coordination of activity across populations of neurons, a process that underlies coherent information processing, supports the encoding of diverse sensory stimuli, and facilitates adaptive behavior in dynamic ... Full text Cite

Data-driven target localization using adaptive radar processing and convolutional neural networks

Journal article Iet Radar Sonar and Navigation · October 1, 2024 Leveraging the advanced functionalities of modern radio frequency (RF) modeling and simulation tools, specifically designed for adaptive radar processing applications, this paper presents a data-driven approach to improve accuracy in radar target localizat ... Full text Cite

Fundamental absorption bandwidth to thickness limit for transparent homogeneous layers.

Journal article Nanophotonics (Berlin, Germany) · April 2024 Past work has considered the analytic properties of the reflection coefficient for a metal-backed slab. The primary result established a fundamental relationship for the minimal layer thickness to bandwidth ratio achievable for an absorber. There has yet t ... Full text Cite

Quickest Change Detection for Unnormalized Statistical Models

Journal article IEEE Transactions on Information Theory · February 1, 2024 Classical quickest change detection algorithms require modeling pre-change and post-change distributions. Such an approach may not be feasible for various machine learning models because of the complexity of computing the explicit distributions. Additional ... Full text Cite

Recursive Least Squares With Minimax Concave Penalty Regularization for Adaptive System Identification

Journal article IEEE Access · January 1, 2024 We develop a recursive least squares (RLS) type algorithm with a minimax concave penalty (MCP) for adaptive identification of a sparse tap-weight vector that represents a communication channel. The proposed algorithm recursively yields its estimate of the ... Full text Cite

Bayesian quickest change detection for unnormalized and score-based models

Journal article Sequential Analysis · January 1, 2024 Score-based algorithms are proposed for the quickest detection of changes in unnormalized statistical models. These are models where the densities are known within a normalizing constant. These algorithms can also be applied to score-based models where the ... Full text Cite

Large Deviation Analysis of Score-Based Hypothesis Testing

Journal article IEEE Access · January 1, 2024 Score-based statistical models play an important role in modern machine learning, statistics, and signal processing. For hypothesis testing, a score-based hypothesis test is proposed in Wu et al., (2022). We analyze the performance of this score-based hypo ... Full text Cite

Neural network accelerated process design of polycrystalline microstructures

Journal article Materials Today Communications · August 1, 2023 Computational experiments are exploited in finding a well-designed processing path to optimize material structures for desired properties. This requires understanding the interplay between the processing-(micro)structure–property linkages using a multi-sca ... Full text Cite

Region selection in Markov random fields: Gaussian case

Journal article Journal of Multivariate Analysis · July 1, 2023 We consider the problem of model selection in Gaussian Markov fields in the sample deficient scenario. The benchmark information-theoretic results in the case of d-regular graphs require the number of samples to be at least proportional to the logarithm of ... Full text Cite

Identifying Latent Stochastic Differential Equations

Journal article IEEE Transactions on Signal Processing · January 1, 2022 We present a method for learning latent stochastic differential equations (SDEs) from high dimensional time series data. Given a high-dimensional time series generated from a lower dimensional latent unknown Itô process, the proposed method learns the mapp ... Full text Cite

Dimension reduced turbulent flow data from deep vector quantisers

Journal article Journal of Turbulence · January 1, 2022 Analysing large-scale data from simulations of turbulent flows is memory intensive, requiring significant resources. This major challenge highlights the need for data compression techniques. In this study, we apply a physics-informed Deep Learning techniqu ... Full text Cite

Fisher Task Distance and its Application in Neural Architecture Search

Journal article IEEE Access · January 1, 2022 We formulate an asymmetric (or non-commutative) distance between tasks based on Fisher Information Matrices, called Fisher task distance. This distance represents the complexity of transferring the knowledge from one task to another. We provide a proof of ... Full text Cite

Score-Based Hypothesis Testing for Unnormalized Models

Journal article IEEE Access · January 1, 2022 Unnormalized statistical models play an important role in machine learning, statistics, and signal processing. In this paper, we derive a new hypothesis testing procedure for unnormalized models. Our approach is motivated by the success of score matching t ... Full text Cite

Large deviations of convex polyominoes*

Journal article Electronic Journal of Probability · January 1, 2022 Many open problems in machine learning, pattern recognition, and geometric analysis require enumeration of different types of lattice polygons, and in particular convex polyominoes. In this work, we develop a large deviation principle for convex polyominoe ... Full text Cite

Characteristic Neural Ordinary Differential Equations

Journal article · November 25, 2021 We propose Characteristic-Neural Ordinary Differential Equations (C-NODEs), a framework for extending Neural Ordinary Differential Equations (NODEs) beyond ODEs. While NODEs model the evolution of a latent variables as the solution to an ODE, C-NODE models ... Link to item Cite

Blaschke Product Neural Networks (BPNN): A Physics-Infused Neural Network for Phase Retrieval of Meromorphic Functions

Journal article · November 25, 2021 Numerous physical systems are described by ordinary or partial differential equations whose solutions are given by holomorphic or meromorphic functions in the complex domain. In many cases, only the magnitude of these functions are observed on various poin ... Link to item Cite

Decentralized Multi-Target Cross-Domain Recommendation for Multi-Organization Collaborations

Journal article · October 25, 2021 Recommender Systems (RSs) are operated locally by different organizations in many realistic scenarios. If various organizations can fully share their data and perform computation in a centralized manner, they may significantly improve the accuracy of recom ... Link to item Cite

Task Affinity with Maximum Bipartite Matching in Few-Shot Learning

Journal article · October 5, 2021 We propose an asymmetric affinity score for representing the complexity of utilizing the knowledge of one task for learning another one. Our method is based on the maximum bipartite matching algorithm and utilizes the Fisher Information matrix. We provide ... Link to item Cite

CNN-Based Joint SNR and Doppler Shift Classification Using Spectrogram Images for Adaptive Modulation and Coding

Journal article IEEE Transactions on Communications · August 1, 2021 This paper proposes a novel convolutional neural network (CNN) based joint classification method to characterize the signal-to-noise power ratio (SNR) and Doppler shift using spectrogram images, in order to enable efficient adaptive modulation and coding ( ... Full text Cite

Semi-Empirical Objective Functions for MCMC Proposal Optimization

Journal article · June 3, 2021 Current objective functions used for training neural MCMC proposal distributions implicitly rely on architectural restrictions to yield sensible optimization results, which hampers the development of highly expressive neural MCMC proposal architectures. In ... Link to item Cite

GAL: Gradient Assisted Learning for Decentralized Multi-Organization Collaborations

Journal article · June 2, 2021 Collaborations among multiple organizations, such as financial institutions, medical centers, and retail markets in decentralized settings are crucial to providing improved service and performance. However, the underlying organizations may have little inte ... Link to item Cite

SemiFL: Semi-Supervised Federated Learning for Unlabeled Clients with Alternate Training

Journal article · June 2, 2021 Federated Learning allows the training of machine learning models by using the computation and private data resources of many distributed clients. Most existing results on Federated Learning (FL) assume the clients have ground-truth labels. However, in man ... Link to item Cite

A Methodology for Exploring Deep Convolutional Features in Relation to Hand-Crafted Features with an Application to Music Audio Modeling

Journal article · May 31, 2021 Understanding the features learned by deep models is important from a model trust perspective, especially as deep systems are deployed in the real world. Most recent approaches for deep feature understanding or model explanation focus on highlighting input ... Link to item Cite

On Statistical Efficiency in Learning

Journal article IEEE Transactions on Information Theory · April 1, 2021 A central issue of many statistical learning problems is to select an appropriate model from a set of candidate models. Large models tend to inflate the variance (or overfitting), while small models tend to cause biases (or underfitting) for a given fixed ... Full text Cite

Fisher Task Distance and Its Application in Neural Architecture Search

Journal article · March 23, 2021 We formulate an asymmetric (or non-commutative) distance between tasks based on Fisher Information Matrices, called Fisher task distance. This distance represents the complexity of transferring the knowledge from one task to another. We provide a proof of ... Link to item Cite

Talaria: A Framework for Simulation of Permissioned Blockchains for Logistics and Beyond

Journal article · March 3, 2021 In this paper, we present Talaria, a novel permissioned blockchain simulator that supports numerous protocols and use cases, most notably in supply chain management. Talaria extends the capability of BlockSim, an existing blockchain simulator, to include p ... Link to item Cite

Dimension Reduced Turbulent Flow Data From Deep Vector Quantizers

Journal article Journal of Turbulence 2022 · March 1, 2021 Analyzing large-scale data from simulations of turbulent flows is memory intensive, requiring significant resources. This major challenge highlights the need for data compression techniques. In this study, we apply a physics-informed Deep Learning techniqu ... Link to item Cite

Improved Automated Machine Learning from Transfer Learning

Journal article · February 27, 2021 In this paper, we propose a neural architecture search framework based on a similarity measure between some baseline tasks and a target task. We first define the notion of the task similarity based on the log-determinant of the Fisher Information matrix. N ... Link to item Cite

Generative Archimedean Copulas

Journal article · February 22, 2021 We propose a new generative modeling technique for learning multidimensional cumulative distribution functions (CDFs) in the form of copulas. Specifically, we consider certain classes of copulas known as Archimedean and hierarchical Archimedean copulas, po ... Link to item Cite

Modeling Extremes with d-max-decreasing Neural Networks

Journal article · February 17, 2021 We propose a novel neural network architecture that enables non-parametric calibration and generation of multivariate extreme value distributions (MEVs). MEVs arise from Extreme Value Theory (EVT) as the necessary class of models when extrapolating a distr ... Link to item Cite

Convergence Rate of Empirical Spectral Distribution of Random Matrices from Linear Codes

Journal article IEEE Transactions on Information Theory · February 1, 2021 It is known that the empirical spectral distribution of random matrices obtained from linear codes of increasing length converges to the well-known Marchenko-Pastur law, if the Hamming distance of the dual codes is at least 5. In this paper, we prove that ... Full text Cite

Model linkage selection for cooperative learning

Journal article Journal of Machine Learning Research · January 1, 2021 We consider the distributed learning setting where each agent or learner holds a specific parametric model and a data source. The goal is to integrate information across a set of learners and data sources to enhance the prediction accuracy of a given learn ... Cite

Fisher Auto-Encoders

Journal article 24TH INTERNATIONAL CONFERENCE ON ARTIFICIAL INTELLIGENCE AND STATISTICS (AISTATS) · 2021 Link to item Cite

Task-aware neural architecture search

Journal article ICASSP IEEE International Conference on Acoustics Speech and Signal Processing Proceedings · January 1, 2021 The design of handcrafted neural networks requires a lot of time and resources. Recent techniques in Neural Architecture Search (NAS) have proven to be competitive or better than traditional handcrafted design, although they require domain knowledge and ha ... Full text Cite

On Statistical Efficiency in Learning.

Journal article IEEE Trans. Inf. Theory · 2021 Full text Cite

Deep Pinsker and James-Stein Neural Networks for Decoding Motor Intentions From Limited Data.

Journal article IEEE transactions on neural systems and rehabilitation engineering : a publication of the IEEE Engineering in Medicine and Biology Society · January 2021 Non-parametric regression has been shown to be useful in extracting relevant features from Local Field Potential (LFP) signals for decoding motor intentions. Yet, in many instances, brain-computer interfaces (BCIs) rely on simple classification methods, ci ... Full text Cite

HeteroFL: Computation and Communication Efficient Federated Learning for Heterogeneous Clients

Journal article · October 2, 2020 Federated Learning (FL) is a method of training machine learning models on private data distributed over a large number of possibly heterogeneous clients such as mobile phones and IoT devices. In this work, we propose a new federated learning framework nam ... Link to item Cite

Deep Cross-Subject Mapping of Neural Activity

Journal article · July 13, 2020 Objective. In this paper, we consider the problem of cross-subject decoding, where neural activity data collected from the prefrontal cortex of a given subject (destination) is used to decode motor intentions from the neural activity of a different subject ... Link to item Cite

GeoStat Representations of Time Series for Fast Classification

Journal article · July 13, 2020 Recent advances in time series classification have largely focused on methods that either employ deep learning or utilize other machine learning models for feature extraction. Though successful, their power often comes at the requirement of computational c ... Link to item Cite

Projected Latent Markov Chain Monte Carlo: Conditional Sampling of Normalizing Flows

Journal article · July 12, 2020 We introduce Projected Latent Markov Chain Monte Carlo (PL-MCMC), a technique for sampling from the high-dimensional conditional distributions learned by a normalizing flow. We prove that a Metropolis-Hastings implementation of PL-MCMC asymptotically sampl ... Link to item Cite

Perception-Distortion Trade-Off with Restricted Boltzmann Machines

Journal article ICASSP IEEE International Conference on Acoustics Speech and Signal Processing Proceedings · May 1, 2020 In this work, we introduce a new procedure for applying Restricted Boltzmann Machines (RBMs) to missing data inference tasks, based on linearization of the effective energy function governing the distribution of observations. We compare the performance of ... Full text Cite

Supervised Encoding for Discrete Representation Learning

Journal article ICASSP IEEE International Conference on Acoustics Speech and Signal Processing Proceedings · May 1, 2020 Classical supervised classification tasks search for a nonlinear mapping that maps each encoded feature directly to a probability mass over the labels. Such a learning framework typically lacks the intuition that encoded features from the same class tend t ... Full text Cite

Speech emotion recognition with dual-sequence LSTM architecture

Journal article ICASSP IEEE International Conference on Acoustics Speech and Signal Processing Proceedings · May 1, 2020 Speech Emotion Recognition (SER) has emerged as a critical component of the next generation of human-machine interfacing technologies. In this work, we propose a new duallevel model that predicts emotions based on both MFCC features and mel-spectrograms pr ... Full text Cite

Learning Partial Differential Equations from Data Using Neural Networks

Journal article ICASSP IEEE International Conference on Acoustics Speech and Signal Processing Proceedings · May 1, 2020 We develop a framework for estimating unknown partial differential equations (PDEs) from noisy data, using a deep learning approach. Given noisy samples of a solution to an unknown PDE, our method interpolates the samples using a neural network, and extrac ... Full text Cite

Robust Marine Buoy Placement for Ship Detection Using Dropout K-Means

Journal article ICASSP IEEE International Conference on Acoustics Speech and Signal Processing Proceedings · May 1, 2020 Marine buoys aid in the battle against Illegal, Unreported and Unregulated (IUU) fishing by detecting fishing vessels in their vicinity. Marine buoys, however, may be disrupted by natural causes and buoy vandalism. In this paper, we formulate marine buoy p ... Full text Cite

DRASIC: Distributed recurrent autoencoder for scalable image compression

Journal article Data Compression Conference Proceedings · March 1, 2020 We propose a new architecture for distributed image compression from a group of distributed data sources. The work is motivated by practical needs of data-driven codec design, low power consumption, robustness, and data privacy. The proposed architecture, ... Full text Cite

Deep clustering of compressed variational embeddings

Journal article Data Compression Conference Proceedings · March 1, 2020 Motivated by the ever-increasing demands for limited communication bandwidth and low-power consumption, we propose a new methodology, named joint Variational Autoencoders with Bernoulli mixture models (VAB), for performing clustering in the compressed data ... Full text Cite

Multimodal Controller for Generative Models

Journal article · February 6, 2020 Class-conditional generative models are crucial tools for data generation from user-specified class labels. Existing approaches for class-conditional generative models require nontrivial modifications of backbone generative architectures to model condition ... Link to item Cite

Cross-subject decoding of eye movement goals from local field potentials.

Journal article Journal of neural engineering · February 2020 ObjectiveWe consider the cross-subject decoding problem from local field potential (LFP) signals, where training data collected from the prefrontal cortex (PFC) of a source subject is used to decode intended motor actions in a destination subject. ... Full text Cite

Proximal gradient algorithm with momentum and flexible parameter restart for nonconvex optimization

Journal article Ijcai International Joint Conference on Artificial Intelligence · January 1, 2020 Various types of parameter restart schemes have been proposed for proximal gradient algorithm with momentum to facilitate their convergence in convex optimization. However, under parameter restart, the convergence of proximal gradient algorithm with moment ... Cite

Sparse Representation-Based Denoising for High-Resolution Brain Activation and Functional Connectivity Modeling: A Task fMRI Study.

Journal article IEEE access : practical innovations, open solutions · January 2020 In the field of neuroimaging and cognitive neuroscience, functional Magnetic Resonance Imaging (fMRI) has been widely used to study the functional localization and connectivity of the brain. However, the inherently low signal-to-noise ratio (SNR) of the fM ... Full text Cite

Prediction in Online Convex Optimization for Parametrizable Objective Functions

Journal article Proceedings of the IEEE Conference on Decision and Control · December 1, 2019 Many techniques for online optimization problems involve making decisions based solely on presently available information: fewer works take advantage of potential predictions. In this paper, we discuss the problem of online convex optimization for parametr ... Full text Cite

Restricted Recurrent Neural Networks

Journal article Proceedings 2019 IEEE International Conference on Big Data Big Data 2019 · December 1, 2019 Recurrent Neural Network (RNN) and its variations such as Long Short-Term Memory (LSTM) and Gated Recurrent Unit (GRU), have become standard building blocks for learning online data of sequential nature in many research areas, including natural language pr ... Full text Cite

A Distributed Online Convex Optimization Algorithm with Improved Dynamic Regret

Journal article Proceedings of the IEEE Conference on Decision and Control · December 1, 2019 In this paper, we consider the problem of distributed online convex optimization, where a network of local agents aim to jointly optimize a convex function over a period of multiple time steps. The agents do not have any information about the future. Exist ... Full text Cite

Distributed Online Convex Optimization with Improved Dynamic Regret

Journal article · November 12, 2019 In this paper, we consider the problem of distributed online convex optimization, where a group of agents collaborate to track the global minimizers of a sum of time-varying objective functions in an online manner. Specifically, we propose a novel distribu ... Link to item Cite

Bayesian Model Comparison with the Hyvärinen Score: Computation and Consistency

Journal article Journal of the American Statistical Association · October 2, 2019 The Bayes factor is a widely used criterion in model comparison and its logarithm is a difference of out-of-sample predictive scores under the logarithmic scoring rule. However, when some of the candidate models involve vague priors on their parameters, th ... Full text Cite

Minimax-optimal decoding of movement goals from local field potentials using complex spectral features.

Journal article Journal of neural engineering · August 2019 ObjectiveWe consider the problem of predicting eye movement goals from local field potentials (LFP) recorded through a multielectrode array in the macaque prefrontal cortex. The monkey is tasked with performing memory-guided saccades to one of eig ... Full text Cite

Peak sidelobe level gumbel distribution of antenna arrays with random phase centers

Journal article IEEE Transactions on Antennas and Propagation · August 1, 2019 The maximum value of an antenna array's sidelobe beampattern, or radiation pattern in the power domain, is an important parameter determining its performance. In this paper, when array antenna elements have random phase centers, we approximate the maximum ... Full text Cite

Sequential Detection of Regime Changes in Neural Data

Journal article International IEEE EMBS Conference on Neural Engineering Ner · May 16, 2019 The problem of detecting changes in firing patterns in neural data is studied. The problem is formulated as a quickest change detection (QCD) problem. Important algorithms from the literature are reviewed. A new algorithmic technique is discussed to detect ... Full text Cite

Asymptotically Optimal Prediction for Time-Varying Data Generating Processes

Journal article IEEE Transactions on Information Theory · May 1, 2019 We develop a methodology (referred to as kinetic prediction) for predicting time series undergoing unknown changes in their data generating distributions. Based on Kolmogorov-Tikhomirov's {\varepsilon } -entropy, we propose a concept called {\varepsilon } ... Full text Cite

Estimation of the evolutionary spectra with application to stationarity test

Journal article IEEE Transactions on Signal Processing · March 1, 2019 In this paper, we propose a new inference procedure for understanding non-stationary processes, under the framework of evolutionary spectra developed by Priestley. Among various frameworks of modeling non-stationary processes, the distinguishing feature of ... Full text Cite

Momentum Schemes with Stochastic Variance Reduction for Nonconvex Composite Optimization

Journal article · February 7, 2019 Two new stochastic variance-reduced algorithms named SARAH and SPIDER have been recently proposed, and SPIDER has been shown to achieve a near-optimal gradient oracle complexity for nonconvex optimization. However, the theoretical advantage of SPIDER does ... Link to item Cite

Spiderboost and momentum: Faster stochastic variance reduction algorithms

Journal article Advances in Neural Information Processing Systems · January 1, 2019 SARAH and SPIDER are two recently developed stochastic variance-reduced algorithms, and SPIDER has been shown to achieve a near-optimal first-order oracle complexity in smooth nonconvex optimization. However, SPIDER uses an accuracy-dependent stepsize that ... Cite

SGD converges to global minimum in deep learning via star-convex path

Journal article 7th International Conference on Learning Representations, ICLR 2019 · January 1, 2019 © 7th International Conference on Learning Representations, ICLR 2019. All Rights Reserved. Stochastic gradient descent (SGD) has been found to be surprisingly effective in training a variety of deep neural networks. However, there is still a lack of under ... Cite

Model Selection Techniques: An Overview

Journal article IEEE Signal Processing Magazine · November 1, 2018 In the era of big data, analysts usually explore various statistical models or machine-learning methods for observed data to facilitate scientific discoveries or gain predictive power. Whatever data and fitting procedures are employed, a crucial step is to ... Full text Cite

Wavelet Shrinkage and Thresholding Based Robust Classification for Brain-Computer Interface

Journal article ICASSP IEEE International Conference on Acoustics Speech and Signal Processing Proceedings · September 10, 2018 A macaque monkey is trained to perform two different kinds of tasks, memory aided and visually aided. In each task, the monkey saccades to eight possible target locations. A classifier is proposed for direction decoding and task decoding based on local fie ... Full text Cite

Evolutionary Spectra Based on the Multitaper Method with Application to Stationarity Test

Journal article ICASSP IEEE International Conference on Acoustics Speech and Signal Processing Proceedings · September 10, 2018 In this work, we propose a new inference procedure for understanding non-stationary processes, under the framework of evolutionary spectra developed by Priestley. Among various frameworks of modeling non-stationary processes, the distinguishing feature of ... Full text Cite

Sequential Event Detection Using Multimodal Data in Nonstationary Environments

Journal article 2018 21st International Conference on Information Fusion Fusion 2018 · September 5, 2018 The problem of sequential detection of anomalies in multimodal data is considered. The objective is to observe physical sensor data from CCTV cameras, and social media data from Twitter and Instagram to detect anomalous behaviors or events. Data from each ... Full text Cite

Asymptotically Pseudo-Independent Matrices

Journal article · September 2, 2018 We show that the family of pseudo-random matrices recently discovered by Soloveychik, Xiang, and Tarokh in their work `Symmetric Pseudo-Random Matrices' exhibits asymptotic independence. More specifically, any two sequences of matrices of matching sizes fr ... Link to item Cite

Online Learning for Multimodal Data Fusion with Application to Object Recognition

Journal article IEEE Transactions on Circuits and Systems II Express Briefs · September 1, 2018 We consider online multimodal data fusion, where the goal is to combine information from multiple modes to identify an element in a large dictionary. We address this problem in the context of object recognition by focusing on tactile sensing as one of the ... Full text Cite

Classification of Local Field Potentials using Gaussian Sequence Model

Journal article 2018 IEEE Statistical Signal Processing Workshop Ssp 2018 · August 29, 2018 A problem of classification of local field potentials (LFPs), recorded from the prefrontal cortex of a macaque monkey, is considered. An adult macaque monkey is trained to perform a memory based saccade. The objective is to decode the eye movement goals fr ... Full text Cite

Communication Complexity of Dual Decomposition Methods for Distributed Resource Allocation Optimization

Journal article IEEE Journal on Selected Topics in Signal Processing · August 1, 2018 Dual decomposition methods are among the most prominent approaches for finding primal/dual saddle point solutions of resource allocation optimization problems. To deploy these methods in the emerging Internet of things networks, which will often have limit ... Full text Cite

Cyclostationary statistical models and algorithms for anomaly detection using multi-modal data

Journal article 2018 IEEE Global Conference on Signal and Information Processing Globalsip 2018 Proceedings · July 2, 2018 A framework is proposed to detect anomalies in multi-modal data. A deep neural network-based object detector is employed to extract counts of objects and sub-events from the data. A cyclostationary model is proposed to model regular patterns of behavior in ... Full text Cite

Stationary Geometric Graphical Model Selection

Journal article · June 9, 2018 We consider the problem of model selection in Gaussian Markov fields in the sample deficient scenario. In many practically important cases, the underlying networks are embedded into Euclidean spaces. Using the natural geometric structure, we introduce the ... Link to item Cite

Convergence of Limited Communication Gradient Methods

Journal article IEEE Transactions on Automatic Control · May 1, 2018 Distributed optimization increasingly plays a central role in economical and sustainable operation of cyber-physical systems. Nevertheless, the complete potential of the technology has not yet been fully exploited in practice due to communication limitatio ... Full text Cite

Analysis of Multistate Autoregressive Models

Journal article IEEE Transactions on Signal Processing · May 1, 2018 In this paper, we consider the inference problem for a wide class of time-series models, referred to as multistate autoregressive models. The time series that we consider are composed of multiple epochs, each modeled by an autoregressive process. The numbe ... Full text Cite

Pseudo-Wigner Matrices

Journal article IEEE Transactions on Information Theory · April 1, 2018 We consider the problem of generating pseudo-random matrices based on the similarity of their spectra to Wigner's semicircular law. We introduce the notion of an r -independent pseudo-Wigner matrix ensemble and prove the closeness of the spectra of its mat ... Full text Cite

Symmetric Pseudo-Random Matrices

Journal article IEEE Transactions on Information Theory · April 1, 2018 We consider the problem of generating symmetric pseudo-random sign (±1) matrices based on the similarity of their spectra to Wigner's semicircular law. Using binary m-sequences (Golomb sequences) of lengths n=2m-1 , we give a simple explicit con ... Full text Cite

Region Detection in Markov Random Fields: Gaussian Case

Journal article · February 11, 2018 We consider the problem of model selection in Gaussian Markov fields in the sample deficient scenario. The benchmark information-theoretic results in the case of d-regular graphs require the number of samples to be at least proportional to the logarithm of ... Link to item Cite

Large Deviations of Convex Polyominoes

Journal article · February 11, 2018 Enumeration of various types of lattice polygons and in particular polyominoes is of primary importance in many machine learning, pattern recognition, and geometric analysis problems. In this work, we develop a large deviation principle for convex polyomin ... Link to item Cite

On data-dependent random features for improved generalization in supervised learning

Journal article 32nd Aaai Conference on Artificial Intelligence Aaai 2018 · January 1, 2018 The randomized-feature approach has been successfully employed in large-scale kernel approximation and supervised learning. The distribution from which the random features are drawn impacts the number of features required to efficiently perform a learning ... Cite

On variability of renewable energy and online power allocation

Journal article IEEE Transactions on Power Systems · January 1, 2018 As electric power system operators shift from conventional energy to renewable energy sources, power distribution systems will experience increasing fluctuations in supply. These fluctuations present the need to not only design online decentralized power a ... Full text Cite

Learning bounds for greedy approximation with explicit feature maps from multiple kernels

Journal article Advances in Neural Information Processing Systems · January 1, 2018 Nonlinear kernels can be approximated using finite-dimensional feature maps for efficient risk minimization. Due to the inherent trade-off between the dimension of the (mapped) feature space and the approximation accuracy, the key problem is to identify pr ... Cite

Model Selection Techniques - An Overview.

Journal article CoRR · 2018 Cite

SLANTS: Sequential Adaptive Nonlinear Modeling of Time Series

Journal article IEEE Transactions on Signal Processing · October 1, 2017 We propose a method for adaptive nonlinear sequential modeling of time series data. Data are modeled as a nonlinear function of past values corrupted by noise, and the underlying nonlinear function is assumed to be approximately expandable in a spline basi ... Full text Cite

Corrections to “Asymptotic Achievability of the Cramér–Rao Bound for Noisy Compressive Sampling” [Mar 09 1233-1236]

Journal article IEEE Transactions on Signal Processing · September 15, 2017 Full text Cite

Multiple Change Point Analysis: Fast Implementation and Strong Consistency

Journal article IEEE Transactions on Signal Processing · September 1, 2017 One of the main challenges in identifying structural changes in stochastic processes is to carry out analysis for time series with dependency structure in a computationally tractable way. Another challenge is that the number of true change points is usuall ... Full text Cite

On Sequential Elimination Algorithms for Best-Arm Identification in Multi-Armed Bandits

Journal article IEEE Transactions on Signal Processing · August 15, 2017 We consider the best-arm identification problem in multi-armed bandits, which focuses purely on exploration. A player is given a fixed budget to explore a finite set of arms, and the rewards of each arm are drawn independently from a fixed, unknown distrib ... Full text Cite

Nonlinear sequential accepts and rejects for identification of top arms in stochastic bandits

Journal article 55th Annual Allerton Conference on Communication Control and Computing Allerton 2017 · July 1, 2017 We address the M-best-Arm identification problem in multi-Armed bandits. A player has a limited budget to explore K arms (M < K), and once pulled, each arm yields a reward drawn (independently) from a fixed, unknown distribution. The goal is to find the to ... Full text Cite

On the spectral norms of pseudo-wigner and related matrices

Journal article 55th Annual Allerton Conference on Communication Control and Computing Allerton 2017 · July 1, 2017 We investigate the spectral norms of symmetric N × N matrices from two pseudo-random ensembles. The first is the pseudo-Wigner ensemble introduced in 'Pseudo-Wigner Matrices' by Soloveychik, Xiang and Tarokh and the second is its sample covariance-Type ana ... Full text Cite

Fundamental Limits of TOA/DOA and Inertial Measurement Unit-Based Wireless Capsule Endoscopy Hybrid Localization

Journal article International Journal of Wireless Information Networks · June 1, 2017 In this paper, performance analysis of hybrid localization based on radio-frequency (RF) and inertial measurement unit (IMU) measurements for a single wireless capsule endoscopy (WCE) traveling the gastrointestinal tract is studied. Specifically, the multi ... Full text Cite

Robust interferometric imaging via prior-less phase recovery: Redundant spacing calibration with generalized-closure phases

Journal article Monthly Notices of the Royal Astronomical Society · January 11, 2017 Atmospheric turbulence presents a fundamental challenge to Fourier phase recovery in optical interferometry. Typical reconstruction algorithms employ Bayesian inference techniques which rely on prior knowledge of the scene under observation. In contrast, r ... Full text Cite

On Optimal Generalizability in Parametric Learning

Journal article ADVANCES IN NEURAL INFORMATION PROCESSING SYSTEMS 30 (NIPS 2017) · January 1, 2017 Link to item Cite

Pseudo-Wigner Matrices from Dual BCH Codes.

Journal article CoRR · 2017 Cite

On optimal generalizability in parametric learning

Journal article Advances in Neural Information Processing Systems · January 1, 2017 We consider the parametric learning problem, where the objective of the learner is determined by a parametric loss function. Employing empirical risk minimization with possibly regularization, the inferred parameter vector will be biased toward the trainin ... Cite

Nonlinear Sequential Accepts and Rejects for Identification of Top Arms in Stochastic Bandits.

Journal article CoRR · 2017 Cite

Resolving phase ambiguities in the calibration of redundant interferometric arrays: Implications for array design

Journal article Monthly Notices of the Royal Astronomical Society · October 1, 2016 We provide new results enabling robust interferometric image reconstruction in the presence of unknown aperture piston variation via the technique of redundant spacing calibration (RSC). The RSC technique uses redundant measurements of the same interferome ... Full text Cite

Complementary lattice arrays for coded aperture imaging.

Journal article Journal of the Optical Society of America. A, Optics, image science, and vision · May 2016 In this work, we propose the concept of complementary lattice arrays in order to enable a broader range of designs for coded aperture imaging systems. We provide a general framework and methods that generate richer and more flexible designs compared to the ... Full text Cite

Key Pre-Distributions From Graph-Based Block Designs

Journal article IEEE Sensors Journal · March 15, 2016 With the development of wireless communication technologies which considerably contributed to the development of wireless sensor networks (WSNs), we have witnessed ever-increasing WSN-based applications which induced a host of research activities in both a ... Full text Cite

On Sequential Elimination Algorithms for Best-Arm Identification in Multi-Armed Bandits.

Journal article CoRR · 2016 Cite

A novel cyber physical system for 3-D imaging of the small intestine in vivo

Journal article IEEE Access · December 11, 2015 Small intestine is the longest organ in the gastrointestinal tract where much of the digestion and the food absorption take place. Wireless video capsule endoscope (VCE) is the first device taking 2-D pictures from the lesions and the abnormalities in the ... Full text Cite

In vivo and in situ measurement and modelling of intra-body effective complex permittivity.

Journal article Healthcare technology letters · December 2015 Radio frequency tracking of medical micro-robots in minimally invasive medicine is usually investigated upon the assumption that the human body is a homogeneous propagation medium. In this Letter, the authors conducted various trial programs to measure and ... Full text Cite

Comment on "Asymptotic Achievability of the Cramér-Rao Bound for Noisy Compressive Sampling"

Journal article · September 14, 2015 In [1], we proved the asymptotic achievability of the Cramér-Rao bound in the compressive sensing setting in the linear sparsity regime. In the proof, we used an erroneous closed-form expression of $ασ^2$ for the genie-aided Cramér-Rao bound $σ^2 \textrm{T ... Link to item Cite

Sparse Signal Recovery from a Mixture of Linear and Magnitude-Only Measurements.

Journal article IEEE signal processing letters · September 2015 We consider the problem of exact sparse signal recovery from a combination of linear and magnitude-only (phaseless) measurements. A k-sparse signal x ∈ ℂ n is measured as r = Bx and y = |Cx|, wher ... Full text Cite

Capacity of Hexagonal Checkerboard Codes

Journal article · June 6, 2015 In this paper, we propose a new method to bound the capacity of checkerboard codes on the hexagonal lattice. This produces rigorous bounds that are tighter than those commonly known. ... Link to item Cite

Data-Driven Learning of the Number of States in Multi-State Autoregressive Models.

Journal article CoRR · 2015 Cite

Bayesian-based localization of wireless capsule endoscope using received signal strength.

Journal article Annual International Conference of the IEEE Engineering in Medicine and Biology Society. IEEE Engineering in Medicine and Biology Society. Annual International Conference · January 2014 In wireless body area sensor networking (WBASN) applications such as gastrointestinal (GI) tract monitoring using wireless video capsule endoscopy (WCE), the performance of out-of-body wireless link propagating through different body media (i.e. blood, fat ... Full text Cite

An augmented Lagrangian based compressed sensing reconstruction for non-Cartesian magnetic resonance imaging without gridding and regridding at every iteration.

Journal article PloS one · January 2014 BackgroundNon-Cartesian trajectories are used in a variety of fast imaging applications, due to the incoherent image domain artifacts they create when undersampled. While the gridding technique is commonly utilized for reconstruction, the incohere ... Full text Cite

Compressed sensing reconstruction for undersampled breath-hold radial cine imaging with auxiliary free-breathing data.

Journal article Journal of magnetic resonance imaging : JMRI · January 2014 PurposeTo improve compressed sensing (CS) reconstruction of accelerated breath-hold (BH) radial cine magnetic resonance imaging (MRI) by exploiting auxiliary data acquired between different BHs.Materials and methodsCardiac function is usu ... Full text Cite

Analysis of the impact of nonlinearity on the capacity of communication channels

Journal article IEEE Transactions on Information Theory · November 4, 2013 We study the impact of nonlinearities on the transmission rate of a communication system by establishing lower and upper bounds on the channel capacity. Our analysis is based on a general transmission model that includes transmitter and receiver nonlineari ... Full text Cite

New Conditions for Sparse Phase Retrieval

Journal article · October 4, 2013 We consider the problem of sparse phase retrieval, where a $k$-sparse signal ${\bf x} \in {\mathbb R}^n \textrm{ (or } {\mathbb C}^n\textrm{)}$ is measured as ${\bf y} = |{\bf Ax}|,$ where ${\bf A} \in {\mathbb R}^{m \times n} \textrm{ (or } {\mathbb C}^{m ... Link to item Cite

Accelerated aortic flow assessment with compressed sensing with and without use of the sparsity of the complex difference image.

Journal article Magnetic resonance in medicine · September 2013 Phase contrast (PC) cardiac MR is widely used for the clinical assessment of blood flow in cardiovascular disease. One of the challenges of PC cardiac MR is the long scan time which limits both spatial and temporal resolution. Compressed sensing reconstruc ... Full text Cite

On the effects of frequency scaling over capacity scaling in underwater networks - Part I: Extended network model

Journal article Wireless Personal Communications · August 1, 2013 In this two-part paper, information-theoretic capacity scaling laws are analyzed in an underwater acoustic network with n regularly located nodes on a square, in which both bandwidth and received signal power can be limited significantly. Parts I and II de ... Full text Cite

On the effects of frequency scaling over capacity scaling in underwater networks - Part II: Dense network model

Journal article Wireless Personal Communications · August 1, 2013 This is the second in a two-part series of papers on information-theoretic capacity scaling laws for an underwater acoustic network. Part II focuses on a dense network scenario, where nodes are deployed in a unit area. By deriving a cut-set upper bound on ... Full text Cite

A peak power efficient cooperative diversity using star-QAM with coherent/noncoherent detection

Journal article IEEE Transactions on Wireless Communications · April 1, 2013 In this paper, we propose a new simple relaying strategy based on bit-interleaved convolutionally coded star-quadrature amplitude modulation (QAM) along with coherent/noncoherent detection. Star-QAM is composed of multiple concentric circles of phase-shift ... Full text Cite

On frequency offset estimation for OFDM

Journal article IEEE Transactions on Wireless Communications · February 8, 2013 This paper presents a comparative study of Schmidl-Cox (SC) and Morelli-Mengali (MM) algorithms for frequency offset estimation in OFDM, along with a new least squares (LS) and a new modified SC algorithm. All algorithms have comparable accuracy approachin ... Full text Cite

Spectral distribution of product of pseudorandom matrices formed from binary block codes

Journal article IEEE Transactions on Information Theory · January 24, 2013 Let {\bf A} \in \{-1,1\}^{N-{a} \times n} and {\bf B} \in \{-1,1\}^{N-{b} \times n} be two matrices whose rows are drawn i.i.d. from the codewords of the binary codes {\cal C}a and {\cal C}b of length n and dual distances {d^{\prime}} ... Full text Cite

A highly scalable key pre-distribution scheme for wireless sensor networks

Journal article IEEE Transactions on Wireless Communications · January 18, 2013 Given the sensitivity of the potential WSN applications and because of resource limitations, key management emerges as a challenging issue for WSNs. One of the main concerns when designing a key management scheme is the network scalability. Indeed, the pro ... Full text Cite

Analysis of network coded HARQ for multiple unicast flows

Journal article IEEE Transactions on Communications · January 14, 2013 In this paper, we consider network coded (NCed) Hybrid-ARQ (HARQ) for multiple unicast flows. The main contribution of the paper is the derivation of throughput expressions for NCed HARQ with arbitrary number of users in identical i.i.d. channels amid pack ... Full text Cite

Near field resonator isolation system: Theory to implementation

Journal article IEEE Transactions on Circuits and Systems I Regular Papers · January 1, 2013 The absence of electromagnetic wave motivates various studies of new communication channels in near field regime. An approach studied here is based on resonant inductive coupling and the use of Resonator Isolation (RI) system. The main concept of the RI sy ... Full text Cite

Compressed sensing reconstruction for whole-heart imaging with 3D radial trajectories: a graphics processing unit implementation.

Journal article Magnetic resonance in medicine · January 2013 A disadvantage of three-dimensional (3D) isotropic acquisition in whole-heart coronary MRI is the prolonged data acquisition time. Isotropic 3D radial trajectories allow undersampling of k-space data in all three spatial dimensions, enabling accelerated ac ... Full text Cite

Rate assignment in wireless networks: Stability analysis and controller design

Journal article IEEE Transactions on Control Systems Technology · January 1, 2013 In this brief, data-rate assignment in IS-856 uplink (reverse link) is studied. The problem is first formulated using an interference model, and then a dynamic control strategy is developed for efficient rate assignment. In the first step, the controller i ... Full text Cite

Two-stage constellation partition algorithm for reduced-complexity multiple-input multiple-output–maximum-likelihood detection systems

Journal article IET Communications · December 18, 2012 Full text Cite

Bayesian source localization in networks with heterogeneous transmission medium

Journal article Navigation Journal of the Institute of Navigation · September 1, 2012 Precise positioning and tracking information in networks with a heterogeneous transmission medium presents a novel networking paradigm. Most of the localization algorithms are vulnerable to the variations of signal propagation speed, dielectric constant, a ... Full text Cite

Interference aware-coordinated beamforming in a multi-cell system

Journal article IEEE Transactions on Wireless Communications · August 27, 2012 In this paper, we propose jointly optimized linear transceiver algorithms called interference aware-coordinated beamforming (IA-CBF) for a two-cell system where each base station is equipped with multiple transmit antennas. To generalize IA-CBF to more tha ... Full text Cite

A practical transmit beamforming strategy for closed-loop MIMO communication

Journal article International Journal of Communication Systems · August 1, 2012 A new beamforming strategy is proposed for multiuser systems with N transmit antennas at the transmitter and M ≤ N single antenna receivers. The proposed scheme remarkably improves on the classical spatial division multiple access, and achieves the same da ... Full text Cite

Bounds on the capacity of discrete memoryless channels corrupted by synchronization and substitution errors

Journal article IEEE Transactions on Information Theory · June 25, 2012 We study the capacity of discrete memoryless channels with synchronization errors and additive noise. We first show that with very large alphabets, their capacity can be achieved by independent and identically distributed input sources, and establish prove ... Full text Cite

DiBa: a data-driven Bayesian algorithm for sleep spindle detection.

Journal article IEEE transactions on bio-medical engineering · February 2012 Although the spontaneous brain rhythms of sleep have commanded much recent interest, their detection and analysis remains suboptimal. In this paper, we develop a data-driven Bayesian algorithm for sleep spindle detection on the electroencephalography (EEG) ... Full text Cite

Accelerated phase contrast imaging using compressed sensing with complex difference sparsity

Journal article Journal of Cardiovascular Magnetic Resonance · February 1, 2012 Full text Cite

Distributed dynamic spectrum allocation for secondary users in a vertical spectrum sharing scenario

Journal article IEICE Transactions on Communications · January 1, 2012 In this paper, we study the problem of distributed spectrum allocation under a vertical spectrum sharing scenario in a cognitive radio network. The secondary users share the spectrum licensed to the primary user by observing the activity statistics of the ... Full text Cite

Guest editorial: Special issue on high mobility wireless communications

Journal article Journal of Modern Transportation · January 1, 2012 Full text Cite

New codes from dual BCH codes with applications in Low PAPR OFDM

Journal article IEEE Transactions on Wireless Communications · December 1, 2011 Dual Bose-Ray-Chaudhuri (BCH) codes, despite their favorable peak to average power ratio (PAPR) properties, have not been used in coded orthogonal frequency division multiplexing (OFDM) systems. This is due to unavailability of a practical decoder and larg ... Full text Cite

Compressed-sensing motion compensation (CosMo): a joint prospective-retrospective respiratory navigator for coronary MRI.

Journal article Magnetic resonance in medicine · December 2011 Prospective right hemidiaphragm navigator (NAV) is commonly used in free-breathing coronary MRI. The NAV results in an increase in acquisition time to allow for resampling of the motion-corrupted k-space data. In this study, we are presenting a joint prosp ... Full text Cite

A coding theory approach to noisy compressive sensing using low density frames

Journal article IEEE Transactions on Signal Processing · November 1, 2011 We consider the compressive sensing of a sparse or compressible signal x ∈ R M. We explicitly construct a class of measurement matrices inspired by coding theory, referred to as low density frames, and develop decoding algorithms that produce an ... Full text Cite

Beam selection gain versus antenna selection gain

Journal article IEEE Transactions on Information Theory · October 1, 2011 We consider beam selection using a fixed beamforming network (FBN) at a base station with M array antennas. In our setting, a Butler matrix is deployed at the RF stage to form M beams, and then the best beam is selected for transmission. We introduce some ... Full text Cite

Achievable rate regions and performance comparison of half duplex bi-directional relaying protocols

Journal article IEEE Transactions on Information Theory · October 1, 2011 In a bi-directional relay channel, two nodes wish to exchange independent messages over a shared wireless half-duplex channel with the help of a relay. In this paper, we derive achievable rate regions for four new half-duplex protocols and compare these to ... Full text Cite

Low-dimensional-structure self-learning and thresholding: regularization beyond compressed sensing for MRI reconstruction.

Journal article Magnetic resonance in medicine · September 2011 An improved image reconstruction method from undersampled k-space data, low-dimensional-structure self-learning and thresholding (LOST), which utilizes the structure from the underlying image is presented. A low-resolution image from the fully sampled k-sp ... Full text Cite

Adaptive algorithms for sparse system identification

Journal article Signal Processing · August 1, 2011 In this paper, identification of sparse linear and nonlinear systems is considered via compressive sensing methods. Efficient algorithms are developed based on Kalman filtering and Expectation-Maximization. The proposed algorithms are applied to linear and ... Full text Cite

Near shannon limit and low peak to average power ratio turbo block coded OFDM

Journal article IEEE Transactions on Communications · August 1, 2011 In this paper, we present an advanced solution for the long standing problem of large peak to average power ratio (PAPR) in orthogonal frequency division multiplexing (OFDM) systems. Although the design of low PAPR codewords has been extensively studied an ... Full text Cite

Cognitive networks achieve throughput scaling of a homogeneous network

Journal article IEEE Transactions on Information Theory · August 1, 2011 Two distinct, but overlapping, networks that operate at the same time, space, and frequency is considered. The first network consists of n randomly distributed primary users, which form an ad hoc network. The second network again consists of m randomly dis ... Full text Cite

Improved capacity scaling in wireless networks with infrastructure

Journal article IEEE Transactions on Information Theory · August 1, 2011 This paper analyzes the impact and benefits of infrastructure support in improving the throughput scaling in networks of n randomly located wireless nodes. The infrastructure uses multiantenna base stations (BSs), in which the number of BSs and the number ... Full text Cite

Spectral distribution of random matrices from binary linear block codes

Journal article IEEE Transactions on Information Theory · June 1, 2011 Let C be a binary linear block code of length n, dimension k and minimum Hamming distance d over GF(2)n. Let d⊥ denote the minimum Hamming distance of the dual code of C over GF(2)n. Let εGF(2)n {-1,1}n Full text Cite

On effects of antenna pointing accuracy for on-the-move satellite networks

Journal article IEEE Transactions on Vehicular Technology · May 1, 2011 In this paper, we study the adjacent geostationary satellite interference to/from on-the-move platforms with motion-induced antenna pointing errors. First, using satellite geometry, we derive tight upper and lower bounds for the average uplink and downlink ... Full text Cite

Compressed sensing with wavelet domain dependencies for coronary MRI: a retrospective study.

Journal article IEEE transactions on medical imaging · May 2011 Coronary magnetic resonance imaging (MRI) is a noninvasive imaging modality for diagnosis of coronary artery disease. One of the limitations of coronary MRI is its long acquisition time due to the need of imaging with high spatial resolution and constraint ... Full text Cite

Accelerated noncontrast-enhanced pulmonary vein MRA with distributed compressed sensing.

Journal article Journal of magnetic resonance imaging : JMRI · May 2011 PurposeTo investigate the efficacy of distributed compressed sensing (CS) to accelerate free-breathing, electrocardiogram (ECG)-triggered noncontrast pulmonary vein (PV) magnetic resonance angiography (MRA).Materials and methodsFully samp ... Full text Cite

On the Order Optimality of Large-scale Underwater Networks

Journal article · March 1, 2011 Capacity scaling laws are analyzed in an underwater acoustic network with $n$ regularly located nodes on a square, in which both bandwidth and received signal power can be limited significantly. A narrow-band model is assumed where the carrier frequency is ... Link to item Cite

Capacity- and Bayesian-based cognitive sensing with location side information

Journal article IEEE Journal on Selected Areas in Communications · February 1, 2011 We investigate spectrum sensing by energy detection based on two different objective functions: a Bayesian sensing cost or the network weighted sum capacity. The Bayesian cost is a traditional detection measure which aims at minimizing a combination of the ... Full text Cite

Analysis of interference in air-to-ground CDMA cellular systems under idealized assumptions

Journal article IEEE Transactions on Communications · January 1, 2011 In this paper, we study the air-to-ground cellular systems with no frequency reuse. We provide an analysis of the inter-cell interference under idealized assumptions: 3D hexagonal cell planning, a line of sight channel model with no shadowing and idealized ... Full text Cite

GADIA: A greedy asynchronous distributed interference avoidance algorithm

Journal article IEEE Transactions on Information Theory · December 1, 2010 In this paper, the problem of distributed dynamic frequency allocation is considered for a canonical communication network, which spans several networks such as cognitive radio networks and digital subscriber lines (DSLs). A greedy asynchronous distributed ... Full text Cite

SPARLS: The Sparse RLS Algorithm

Journal article IEEE TRANSACTIONS ON SIGNAL PROCESSING · August 1, 2010 Full text Link to item Cite

SPARLS: The sparse RLS algorithm

Journal article IEEE Transactions on Signal Processing · August 1, 2010 We develop a recursive L1-regularized least squares (SPARLS) algorithm for the estimation of a sparse tap-weight vector in the adaptive filtering setting. The SPARLS algorithm exploits noisy observations of the tap-weight vector output stream an ... Full text Cite

An adaptive greedy algorithm with application to nonlinear communications

Journal article IEEE Transactions on Signal Processing · June 1, 2010 Greedy algorithms form an essential tool for compressed sensing. However, their inherent batch mode discourages their use in time-varying environments due to significant complexity and storage requirements. In this paper two existing powerful greedy scheme ... Full text Cite

On Capacity Scaling of Underwater Networks: An Information-Theoretic Perspective

Journal article · May 5, 2010 Capacity scaling laws are analyzed in an underwater acoustic network with $n$ regularly located nodes on a square. A narrow-band model is assumed where the carrier frequency is allowed to scale as a function of $n$. In the network, we characterize an atten ... Link to item Cite

A survey of error-correcting codes for channels with symbol synchronization errors

Journal article IEEE Communications Surveys and Tutorials · March 1, 2010 We present a comprehensive survey of errorcorrecting codes for channels corrupted by synchronization errors. We discuss potential applications as well as the obstacles that need to be overcome before such codes can be used in practical systems. © 2010 IEEE ... Full text Cite

On the equivalence of interleavers for turbo codes using quadratic permutation polynomials over integer rings

Journal article IEEE Communications Letters · March 1, 2010 It is known that the equivalence of interleavers for turbo codes using quadratic permutation polynomials (QPPs) over integer rings can be exactly determined by the so-called quadratic null polynomials (QNPs) over integer rings. For generating QNPs or highe ... Full text Cite

Shannon-theoretic limits on noisy compressive sampling

Journal article IEEE Transactions on Information Theory · January 1, 2010 In this paper, we study the number of measurements required to recover a sparse signal in ℤM with L nonzero coefficients from compressed samples in the presence of noise. We consider a number of different recovery criteria, including the exact r ... Full text Cite

Interference and noise reduction by beamforming in cognitive networks

Journal article IEEE Transactions on Communications · November 6, 2009 We consider beamforming in a cognitive network with multiple primary users and a secondary user sharing the same spectrum. Each primary and secondary user consists of a transmitter and a receiver. In particular, we assume that the secondary transmitter has ... Full text Cite

Rate of channel hardening of antenna selection diversity schemes and its implication on scheduling

Journal article IEEE Transactions on Information Theory · October 8, 2009 For a multiple-antenna system, we find a simple and accurate expression for the asymptotic distribution of the antenna selection gain when the transmitter selects the transmit antenna with the strongest channel. We use this to estimate the underlying chann ... Full text Cite

Frequency-domain bit-flipping equalizer for wideband MIMO channels

Journal article IEEE Transactions on Wireless Communications · October 1, 2009 We propose a low-complexity equalizer whose performance approaches that of the optimal maximum-likelihood estimators in wideband multiple-input multiple-output (MIMO) channels. The proposed algorithm makes use of a bit-flipping refinement procedure precede ... Full text Cite

A new construction of signature waveforms for multi-rate multi-cell QS-CDMA systems

Journal article Wireless Personal Communications · September 1, 2009 In this paper, we propose a new construction of signature waveform sets based on Generalized Loosely Synchronization (GLS) sets and different chip waveforms. The new signature sets are applied into the multi-rate multi-cell quasi-synchronous CDMA (QS-CDMA) ... Full text Cite

Dual antenna selection algorithms and feedback strategies with reduced complexity for multiple-input multiple-output systems

Journal article Iet Microwaves Antennas and Propagation · August 24, 2009 A simple antenna selection strategy for multiple-input multiple-output wireless systems with partial feedback is presented. In the proposed scheme, both transmit and receive antenna selection are done at the receiver, significantly reducing feedback inform ... Full text Cite

Peak power reduction of OFDM signals with sign adjustment

Journal article IEEE Transactions on Communications · August 12, 2009 It has recently been shown that significant reduction in the peak to mean envelope power (PMEPR) can be obtained by altering the sign of each subcarrier in a multicarrier system with n subcarriers. However, finding the best sign not only requires a search ... Full text Cite

Scaling laws of single-hop cognitive networks

Journal article IEEE Transactions on Wireless Communications · August 1, 2009 We consider a cognitive network consisting of n cognitive users uniformly distributed with constant density among primary users. Each user has a single transmitter and a single receiver, and the primary and cognitive users transmit concurrently. The cognit ... Full text Cite

On the primary exclusive region of cognitive networks

Journal article IEEE Transactions on Wireless Communications · July 1, 2009 We study a cognitive network consisting of a single primary transmitter and multiple secondary, or cognitive, users. The primary transmitter, located at the center of the network, communicates with primary receivers within a disc called the primary exclusi ... Full text Cite

Optimized constellations for two-way wireless relaying with physical network coding

Journal article IEEE Journal on Selected Areas in Communications · June 1, 2009 We investigate modulation schemes optimized for two-way wireless relaying systems, for which network coding is employed at the physical layer. We consider network coding based on denoise-and-forward (DNF) protocol, which consists of two stages: multiple ac ... Full text Cite

Downlink transmission rate-control strategies for closed-loop multiple-input multiple-output systems

Journal article Iet Communications · April 20, 2009 A novel downlink transmission rate-control and feedback reduction strategy for closed-loop multiple-input multiple-output (MIMO) multiple-input multiple-output wireless systems is presented. Unlike conventional systems that use signal to interference plus ... Full text Cite

Compressive Sensing Using Low Density Frames

Journal article · March 3, 2009 We consider the compressive sensing of a sparse or compressible signal ${\bf x} \in {\mathbb R}^M$. We explicitly construct a class of measurement matrices, referred to as the low density frames, and develop decoding algorithms that produce an accurate est ... Link to item Cite

SPARLS: A Low Complexity Recursive $\mathcal{L}_1$-Regularized Least Squares Algorithm

Journal article · January 6, 2009 We develop a Recursive $\mathcal{L}_1$-Regularized Least Squares (SPARLS) algorithm for the estimation of a sparse tap-weight vector in the adaptive filtering setting. The SPARLS algorithm exploits noisy observations of the tap-weight vector output stream ... Link to item Cite

Asymptotic achievability of the Cramér-Rao bound for noisy compressive sampling

Journal article IEEE Transactions on Signal Processing · January 1, 2009 We consider a model of the form =Ax + n, where x ε CM is sparse with at most L nonzero coefficients in unknown locations, y ε CN is the observation vector, A CN×M is the measurement matrix and n ε CN is the Gauss ... Full text Cite

Beam Selection Gain Versus Antenna Selection Gain

Journal article CoRR · 2009 Cite

Bi-directional half-duplex relaying protocols

Journal article Journal of Communications and Networks · January 1, 2009 The bi-directional relay channel is the natural extension of a three-terminal relay channel where node a transmits to node b with the help of a relay r to allow for two-way communication between nodes a and b. That is, in a bi-directional relay channel, a ... Full text Cite

Performance bounds for bidirectional coded cooperation protocols

Journal article IEEE Transactions on Information Theory · November 10, 2008 In coded bidirectional cooperation, two nodes wish to exchange messages over a shared half-duplex channel with the help of a relay. In this correspondence, we derive performance bounds for this problem for each of three decode-and-forward protocols. The fi ... Full text Cite

Bi-directional half-duplex protocols with multiple relays

Journal article · October 7, 2008 In a bi-directional relay channel, two nodes wish to exchange independent messages over a shared wireless half-duplex channel with the help of relays. Recent work has considered information theoretic limits of the bi-directional relay channel with a single ... Link to item Cite

Achievable rate regions for bi-directional relaying

Journal article · August 7, 2008 In a bi-directional relay channel, two nodes wish to exchange independent messages over a shared wireless half-duplex channel with the help of a relay. In this paper, we derive achievable rate regions for four new half-duplex protocols and compare these to ... Link to item Cite

On bounds and algorithms for frequency synchronization for collaborative communication systems

Journal article IEEE Transactions on Signal Processing · August 1, 2008 Cooperative diversity systems are wireless communication systems designed to exploit cooperation among users to mitigate the effects of multipath fading. In fairly general conditions, it has been shown that these systems can achieve the diversity order of ... Full text Cite

A frame construction and a universal distortion bound for sparse representations

Journal article IEEE Transactions on Signal Processing · June 1, 2008 We consider approximations of signals by the elements of a frame in a complex vector space of dimension N and formulate both the noiseless and the noisy sparse representation problems. The noiseless representation problem is to find sparse representations ... Full text Cite

An overview of scaling laws in ad hoc and cognitive radio networks

Journal article Wireless Personal Communications · May 1, 2008 Currently, wireless communications are changing along the lines of three main thrusts. The first is the introduction of secondary spectrum licensing (SSL). Regulations on the usage of licensed spectra are being loosened, encouraging unused primary spectrum ... Full text Cite

Achievable rates and scaling laws for cognitive radio channels

Journal article Eurasip Journal on Wireless Communications and Networking · February 5, 2008 Cognitive radios have the potential to vastly improve communication over wireless channels. We outline recent information theoretic results on the limits of primary and cognitive user communication in single and multiple cognitive user scenarios. We first ... Full text Cite

Introduction to the issue on signal processing and networking for dynamic spectrum access

Journal article IEEE Journal on Selected Topics in Signal Processing · February 1, 2008 Full text Cite

Construction of block orthogonal Golay sequences and application to channel estimation of mimo-ofdm systems

Journal article IEEE Transactions on Communications · January 1, 2008 In this paper, we construct a family of block orthogonal Golay sequences that have low peak-to-mean envelope power ratio (PMEPR) as well as blockwise orthogonal properties. We then present an application of the sequences to channel estimation of multiple-i ... Full text Cite

Cognitive radio networks: Highlights of information theoretic limits, models, and design

Journal article IEEE Signal Processing Magazine · January 1, 2008 In recent years, the development of intelligent, adaptive wireless devices called cognitive radios, together with the introduction of secondary spectrum licensing, has led to a new paradigm in communications: cognitive networks. Cognitive networks are wire ... Full text Cite

A broadcast scheme for MIMO systems with channel state information at the transmitter

Journal article IEICE Transactions on Communications · January 1, 2008 We propose a new broadcast strategy for a multiple-input multiple-output (MIMO) system with N transmit antennas at the transmitter and M≤N single antenna receivers. The proposed method, based on dirtypaper coding (DPC), spatially separates the M users but ... Full text Cite

Scaling laws of cognitive networks

Journal article Proceedings of the 2nd International Conference on Cognitive Radio Oriented Wireless Networks and Communications Crowncom · December 1, 2007 Opportunistic secondary spectrum usage has the potential to dramatically increase spectral efficiency and rates of a network of secondary cognitive users. In this work we consider a cognitive network: n pairs of cognitive transmitter and receiver wish to c ... Full text Cite

A Distributed Dynamic Frequency Allocation Algorithm

Journal article · November 20, 2007 We consider a network model where the nodes are grouped into a number of clusters and propose a distributed dynamic frequency allocation algorithm that achieves performance close to that of a centralized optimal algorithm. Each cluster chooses its transmis ... Link to item Cite

Performance of sparse representation algorithms using randomly generated frames

Journal article IEEE Signal Processing Letters · November 1, 2007 We consider sparse representations of signals with at most L nonzero coefficients using a frame F of size M in CN. For any F, we establish a universal numerical lower bound on the average distortion of the representation as a function of the spa ... Full text Cite

On the Degrees of Freedom in Cognitive Radio Channels

Journal article · July 12, 2007 After receiving useful peer comments, we would like to withdraw this paper. ... Link to item Cite

Design of an OFDM cooperative space-time diversity system

Journal article IEEE Transactions on Vehicular Technology · July 1, 2007 In this paper, we propose a wireless system that realizes theoretical benefits of space-time cooperation. Specifically, we design a space-time cooperative system based on orthogonal frequency division multiplexing (OFDM), which we refer to as a cooperative ... Full text Cite

Reverse-link rate control algorithms with fairness guarantees for CDMA systems

Journal article IEEE Transactions on Wireless Communications · April 1, 2007 We propose a set of distributed rate control algorithms for the reverse-link of CDMA systems using a pricing mechanism. In the derivation, we assume that the base station broadcasts a real-valued feedback in order to control the reverse activity level. In ... Full text Cite

Performance Bounds on Sparse Representations Using Redundant Frames

Journal article · March 9, 2007 We consider approximations of signals by the elements of a frame in a complex vector space of dimension $N$ and formulate both the noiseless and the noisy sparse representation problems. The noiseless representation problem is to find sparse representation ... Link to item Cite

A Distributed Dynamic Frequency Allocation Algorithm For Ad Hoc Networks

Journal article CoRR · 2007 Cite

Comparison study of UWB indoor channel models

Journal article IEEE Transactions on Wireless Communications · January 1, 2007 We compare three approaches for modeling the ultra-wideband (UWB) indoor channel delay profile, including the one adopted by the IEEE 802.15.3a Task Group. We do this using a large database we collected (and have reported on previously) spanning numerous i ... Full text Cite

MIMO-OFDM and its application

Journal article Journal of Communications and Networks · January 1, 2007 Full text Cite

Performance bounds for Bi-directional coded cooperation protocols

Journal article Proceedings International Conference on Distributed Computing Systems · January 1, 2007 In coded bi-directional cooperation, two nodes wish to exchange messages over a shared half-duplex channel with the help of a relay. In this paper, we derive performance bounds for this problem for each of three protocols. The first protocol is a two phase ... Full text Cite

Rate of Channel Hardening of Antenna Selection Diversity Schemes and Its Implication on Scheduling

Journal article CoRR · 2007 Cite

Approximating fluid schedules in crossbar packet-switches and Banyan networks

Journal article IEEE ACM Transactions on Networking · December 1, 2006 We consider a problem motivated by the desire to provide flexible, rate-based, quality of service guarantees for packets sent over input queued switches and switch networks. Our focus is solving a type of online traffic scheduling problem, whose input at e ... Full text Cite

Variable-rate two-phase collaborative communication protocols for wireless networks

Journal article IEEE Transactions on Information Theory · September 1, 2006 The performance of two-phase collaborative communication protocols is studied for wireless networks. All the communication nodes in the cluster are assumed to share the same channel and transmit or receive collaboratively in a quasi-static Rayleigh flat-fa ... Full text Cite

Limits on communications in a cognitive radio channel

Journal article IEEE Communications Magazine · June 1, 2006 In this article we review FCC secondary markets initiatives and how smart wireless devices could be used to increase spectral efficiency. We survey the current proposals for cognitive radio deployment, and present a new, potentially more spectrally efficie ... Full text Cite

Achievable rates in cognitive radio channels

Journal article IEEE Transactions on Information Theory · May 1, 2006 Cognitive radio promises a low-cost, highly flexible alternative to the classic single-frequency band, single-protocol wireless device. By sensing and adapting to its environment, such a device is able to fill voids in the wireless spectrum and can dramati ... Full text Cite

On compound channels with side information at the transmitter

Journal article IEEE Transactions on Information Theory · April 1, 2006 Costa has proved that for noncausally known Gaussian interference at a power constrained transmitter communicating over an additive white Gaussian noise channel there is no capacity loss when compared to a scenario where interference is not present. For th ... Full text Cite

Optimized nonuniform PSK for multiclass traffic and its application to space-time block codes

Journal article IEEE Transactions on Communications · February 1, 2006 We construct nonuniform phase-shift keying (PSK) constellations that provide unequal error protection for multiclass traffic such as compressed voice and video data. Then closed-form expressions expression for the exact bit-error rate (BER) of the nonunifo ... Full text Cite

Complementary beamforming: New approaches

Journal article IEEE Transactions on Communications · January 1, 2006 Smart antenna technology can greatly improve the coverage radius of wireless systems by focusing the transmitted signal (beam) toward desired users. However, beamforming has an important side effect as it creates a region, herein referred to as the complem ... Full text Cite

Approximating fluid schedules in crossbar packet-switches and Banyan networks.

Journal article IEEE/ACM Trans. Netw. · 2006 Full text Cite

Opportunistic beamforming based on multiple weighting vectors

Journal article IEEE Transactions on Wireless Communications · November 1, 2005 In order to improve the throughput of the opportunistic beamforming, the authors generalize the opportunistic beamforming by using multiple random weighting vectors at each time slot. The base station chooses the best weighting vector and performs the oppo ... Full text Cite

Collaborative beamforming for distributed wireless ad hoc sensor networks

Journal article IEEE Transactions on Signal Processing · November 1, 2005 The performance of collaborative beamforming is analyzed using the theory of random arrays. The statistical average and distribution of the beampattern of randomly generated phased arrays is derived in the framework of wireless ad hoc sensor networks. Each ... Full text Cite

UWB delay profile models for residential and commercial indoor environments

Journal article IEEE Transactions on Vehicular Technology · July 1, 2005 We present models for the ultrawideband (UWB) channel delay profile in indoor environments, based on the processing of two large sets of measured data. Both measurement sets are for a center frequency of 5 GHz, but the bandwidths are very different - 1.25 ... Full text Cite

Space-time diversity enhancements using collaborative communications

Journal article IEEE Transactions on Information Theory · June 1, 2005 The use of the spatial dimension is known to greatly increase the reliability of quasi-static (i.e., nonergodic) wireless channels. In this paper, it is demonstrated that most of this gain can also be achieved through collaborative communications with sing ... Full text Cite

Measurement and modeling of an ultra-wide bandwidth indoor channel

Journal article IEEE Transactions on Communications · October 1, 2004 This paper describes the results of frequency-domain channel sounding in residential environments. It consists of detailed characterization of complex frequency responses of ultra-wideband (UWB) signals having a nominal center frequency of 5 GHz. A path lo ... Full text Cite

Multiple-antenna channel hardening and its implications for rate feedback and scheduling

Journal article IEEE Transactions on Information Theory · September 1, 2004 Wireless data traffic is expected to grow over the next few years and the technologies that will provide data services are still being debated. One possibility is to use multiple antennas at base stations and terminals to get very high spectral efficiencie ... Full text Cite

Erratum: A new construction of 16-QAM Golay complementary sequences (IEEE Trans. Informa. Theory (2003) 49, (2953-2959))

Journal article IEEE Transactions on Information Theory · June 1, 2004 Full text Cite

A New Construction of 16-QAM Golay Complementary Sequences

Journal article IEEE Transactions on Information Theory · November 1, 2003 We present a new construction of 16-QAM Golay sequences of length n = 2m, The number of constructed sequences is (14 + 12m) (m!/2)4 m+1. When employed as a code in an orthogonal frequency-division multiplexing (OFDM) system; this set ... Full text Cite

Differential space time block codes using nonconstant modulus constellations

Journal article IEEE Transactions on Signal Processing · November 1, 2003 We propose differential space time block codes (STBC) using nonconstant modulus constellations, e.g., quadrature amplitude modulation (QAM), which cannot be utilized in the conventional differential STBC. Since QAM constellations have a larger minimum dist ... Full text Cite

Special issue on coding and signal processing for MIMO system

Journal article Journal of Communications and Networks · June 2003 Full text Cite

Variable-rate space-time block codes in M-ary PSK systems

Journal article IEEE Journal on Selected Areas in Communications · April 1, 2003 We consider a multiple antenna system when combined array processing with space-time coding is used. We present variable rate space-time block codes for two, three, and four transmit antennas and optimize the transmit power so that the average bit-error ra ... Full text Cite

Energy reduction in VLSI computation modules: An information-theoretic approach

Journal article IEEE Transactions on Information Theory · April 1, 2003 We consider the problem of reduction of computation cost by introducing redundancy in the number of ports as well as in the input and output sequences of computation modules. Using our formulation, the classical "communication scenario" is the case when a ... Full text Cite

An empirical indoor path loss model for ultra-wideband channels

Journal article Journal of Communications and Networks · January 1, 2003 We present a statistical model for the path loss of ultra-wideband (UWB) channels in indoor environments. In contrast to our previously reported measurements, the data reported here are for a bandwidth of 6GHz rather than 1.25GHz; they encompass commercial ... Full text Cite

Erratum: Space-time codes for high data rate wireless communications: Performance criteria in the presence of channel estimation errors, mobility, and multiple paths (IEEE Trans. Commun. (1999) 47, (199-207))

Journal article IEEE Transactions on Communications · January 1, 2003 Full text Cite

Existence and construction of noncoherent unitary space-time codes

Journal article IEEE Transactions on Information Theory · December 1, 2002 We consider transmission using N transmit and reception using M receive antennas in a wireless environment assuming that neither the transmitter nor the receiver knows the channel coefficients. For the scenario that the transmission employs noncoherent T × ... Full text Cite

Editorial

Journal article Eurasip Journal on Applied Signal Processing · May 1, 2002 Full text Cite

Editorial

Journal article EURASIP Journal on Advances in Signal Processing · March 18, 2002 Full text Cite

Applied Signal Processing: Editorial

Journal article Eurasip Journal on Applied Signal Processing · March 1, 2002 Cite

Space-time codes for wireless optical communications

Journal article Eurasip Journal on Applied Signal Processing · January 1, 2002 A space-time channel coding technique is presented for overcoming turbulence-induced fading in an atmospheric optical heterodyne communication system that uses multiple transmit and receive apertures. In particular, a design criterion for minimizing the pa ... Full text Cite

A simple encodable/decodable OFDM QPSK code with low peak-to-mean envelope power ratio

Journal article IEEE Transactions on Information Theory · November 1, 2001 We present a quadrature phase-shift keying (QPSK) coding scheme for multicarrier communications. The scheme supports simple encoding and extremely simple maximum-likelihood (ML) decoding algorithms for orthogonal frequency-division multiplexing (OFDM). Mor ... Full text Cite

Multiple transmit antenna differential detection from generalized orthogonal designs

Journal article IEEE Transactions on Information Theory · September 1, 2001 We explicitly construct multiple transmit antenna differential encoding/decoding schemes based on generalized orthogonal designs. These constructions generalize the two transmit antenna differential detection scheme that we proposed before. ... Full text Cite

A construction of OFDM 16-QAM sequences having low peak powers

Journal article IEEE Transactions on Information Theory · January 1, 2001 Using a realization of 16-QAM as set addition of two scaled versions of the 4-PSK constellation, we construct 16-QAM sequences having low peak-to-mean envelope power ratios (PMEPR) from 4-PSK Golay sequences. Various upper bounds on the peak envelope power ... Full text Cite

Space-time codes for wireless optical channels

Journal article IEEE International Symposium on Information Theory Proceedings · January 1, 2001 A space-time channel coding technique is presented for overcoming turbulence-induced fading in an atmospheric optical communication system that uses multiple transmit and receive apertures. In particular, a design criterion for minimizing the pairwise prob ... Full text Cite

On the existence and construction of good codes with low peak-to-average power ratios

Journal article IEEE Transactions on Information Theory · September 1, 2000 The first lower bound on the peak-to-average power ratio (PAPR) of a constant energy code of a given length n, minimum Euclidean distance and rate is established. Conversely, using a nonconstructive Varshamov-Gilbert style argument yields a lower bound on ... Full text Cite

Differential detection scheme for transmit diversity

Journal article IEEE Journal on Selected Areas in Communications · July 1, 2000 We present a transmission scheme for exploiting diversity given by two transmit antennas when neither the transmitter nor the receiver has access to channel state information. The new detection scheme can use equal energy constellations and encoding is sim ... Full text Cite

Correction to "Space-time block codes from orthogonal designs"

Journal article IEEE Transactions on Information Theory · January 2000 Full text Cite

On the computation and reduction of the peak-to-average power ratio in multicarrier communications

Journal article IEEE Transactions on Communications · January 1, 2000 For any code C defined over an equal energy constellation, it is first shown that at any time instance, the problem of determining codewords of C with high peak-to-average power ratios (PAPR) in a multicarrier communication system is intimately related to ... Full text Cite

Design of successively refinable trellis-coded quantizers

Journal article IEEE Transactions on Information Theory · December 1, 1999 We propose successively refinable trellis-coded quantizers for progressive transmission. (Progressive transmission is an essential component of image and multimedia browsing systems.) A new trellis structure which is scalable is used in the design of our t ... Full text Cite

Universal bound on the performance of lattice codes

Journal article IEEE Transactions on Information Theory · December 1, 1999 We present a lower bound on the probability of symbol error for maximum-likelihood decoding of lattices and lattice codes on a Gaussian channel. The bound is tight for error probabilities and signal-to-noise ratios of practical interest, as opposed to most ... Full text Cite

Multiple description trellis-coded quantization

Journal article IEEE Transactions on Communications · December 1, 1999 We present a construction of multiple description trellis-coded quantizers. We use the tensor product of trellises to build a trellis which is applicable to multiple description coding. The problems of index assignment and set partitioning for the resultin ... Full text Cite

On the existence and construction of good codes with low peak-to-average power ratios

Journal article HP Laboratories Technical Report · April 1, 1999 The first lower bound on the peak-to-average power ratio (PAPR) of a constant energy code of a given length n, minimum Euclidean distance and rate is established. Conversely, using a non-constructive Varshamov-Gilbert style argument yields a lower bound on ... Cite

Space-time block coding for wireless communications: Performance results

Journal article IEEE Journal on Selected Areas in Communications · March 1, 1999 We document the performance of space-time block codes [13], [14], which provide a new paradigm for transmission over Rayleigh fading channels using multiple transmit antennas. Data is encoded using a space-time block code, and the encoded data is split int ... Full text Cite

Space-time codes for high data rate wireless communication: performance criteria in the presence of channel estimation errors, mobility, and multiple paths

Journal article IEEE Transactions on Communications · January 1, 1999 Space-time coding is a bandwidth and power efficient method of communication over fading channels that realizes the benefits of multiple transmit antennas. Specific codes have been constructed using design criteria derived for quasi-static flat Rayleigh or ... Full text Cite

Combined array processing and space-time coding

Journal article IEEE Transactions on Information Theory · January 1, 1999 The information capacity of wireless communication systems may be increased by employing multiple transmit and receiver antennas. The goal of the system design is to exploit this capacity in a practical way. To increase data rate over wireless channels, sp ... Full text Cite

Space-time block codes from orthogonal designs

Journal article IEEE Transactions on Information Theory · January 1, 1999 The theory of space-time block coding is presented as a simple and elegant method for transmission using multiple transmit antennas in a wireless Rayleigh/Rician environment. These codes have a very simple maximum-likelihood decoding algorithm which is onl ... Full text Cite

A space-time coding modem for high-data-rate wireless communications

Journal article IEEE Journal on Selected Areas in Communications · October 1, 1998 This paper presents the theory and practice of a new advanced modem technology suitable for high-data-rate wireless communications and presents its performance over a frequency-flat Rayleigh fading channel. The new technology is based on space-time coded m ... Full text Cite

Principal ratio combining for fixed wireles applications when transmitter diversity is employed

Journal article IEEE Communications Letters · August 1, 1998 We present a near-optimal detection method for decoding codes appropriate to transmission using multiple transmit antennas in a fixed wireless environment. The method is a nontrivial generalization of maximum ratio combining. This reduces the decoding comp ... Full text Cite

Recent progress in space-time block and trellis coding

Journal article IEEE International Symposium on Information Theory Proceedings · January 1, 1998 Techniques for transmission and reception over wireless channels using multiple transmit antennas are presented. © 1998 IEEE. ... Full text Cite

Space-time codes for high data rate wireless communication: Performance criterion and code construction

Journal article IEEE Transactions on Information Theory · January 1, 1998 We consider the design of channel codes for improving the data rate and/or the reliability of communications over fading channels using multiple transmit antennas. Data is encoded by a channel code and the encoded data is split into n streams that are simu ... Full text Cite

Existence of optimal prefix codes for infinite source alphabets

Journal article IEEE Transactions on Information Theory · December 1, 1997 It is proven that for every random variable with a countably infinite set of outcomes and finite entropy there exists an optimal prefix code which can be constructed from Huffman codes for truncated versions of the random variable, and that the average len ... Full text Cite

Upper bounds on trellis complexity of lattices

Journal article IEEE Transactions on Information Theory · December 1, 1997 Unlike block codes, n-dimensional lattices can have minimal trellis diagrams with an arbitrarily large number of states, branches, and paths. In particular, we show by a counterexample that there is no f(n), a function of n, such that all rational lattices ... Full text Cite

Low-rate multi-dimensional space-time codes for both slow and rapid fading channels

Journal article IEEE International Symposium on Personal Indoor and Mobile Radio Communications PIMRC · December 1, 1997 We consider the design of channel codes for improving the data rate and/or the reliability of communications using multiple transmit antennas over a fading channel. It is assumed that the transmitter does not know the channel but seeks to choose a codebook ... Cite

Space-time codes for high data rate wireless communication: Performance criteria

Journal article IEEE International Conference on Communications · January 1, 1997 We consider the design of channel codes for improving the data rate and/or the reliability of communications over fading channels using multiple transmit antennas. Here, data is encoded by a channel code and the encoded data is split into n streams that ar ... Cite

Space-time codes for wireless communication

Journal article IEEE International Symposium on Information Theory Proceedings · January 1, 1997 The design of channel codes for improving the data rate and/or the reliability of communications over fading channels using multiple transmit antennas is considered. A design criterion is provided and is then used to design space-time codes for high data r ... Full text Cite

Space-time codes for high data rate wireless communication: Mismatch analysis

Journal article IEEE International Conference on Communications · January 1, 1997 We revisit Space-Time Codes for a mobile communication system that employs multiple antennas at the base and optional antenna diversity at the mobile station. The realistic case when the channel state is not completely known is considered. It is assumed th ... Cite

Space-time codes for wireless communication: Code construction

Journal article IEEE Vehicular Technology Conference · January 1, 1997 We consider the design of channel codes for improving the data rate and/or the reliability of communications over fading channels using multiple transmit antennas. Here, data is encoded by a channel code and the encoded data is split into n streams that ar ... Cite

Trellis complexity versus the coding gain of lattices I

Journal article IEEE Transactions on Information Theory · December 1, 1996 The best possible tradeoff between the coding gain and trellis complexity for lattices is studied. Three trellis complexity functions are defined for lattices as a measure of minimum trellis decoding complexity per dimension required for achieving a coding ... Full text Cite

Trellis complexity versus the coding gain of lattices II

Journal article IEEE Transactions on Information Theory · December 1, 1996 For an arbitrary rational lattice L with gain γ, the average number of states (respectively, branches) in any given trellis diagram of L is bounded below by a function of γ. It is proved that this function grows exponentially in γ. In the reverse direction ... Full text Cite

On the trellis complexity of the densest lattice packings in ℝn

Journal article SIAM Journal on Discrete Mathematics · January 1, 1996 An inequality relating the trellis complexity of lattices to their dimension and Hermite parameter is established. Using this inequality, a conjecture of Forney is proved indicating that the trellis complexity of the densest lattice packings in ℝn Full text Cite

A Constraint on the Existence of Simple Torsion-Free Lie Modules

Journal article Proceedings of the American Mathematical Society · August 1995 Full text Cite

A constraint on the existence of simple torsion-free lie modules

Journal article Proceedings of the American Mathematical Society · January 1, 1995 For any simple Lie algebra L with Cartan subalgebra H the classification of all simple H-diagonalizable. H-modules having a finite-dimensional weight space is known to depend on determining the simple torsion-free Lmodules of finite degree. It is further k ... Full text Cite