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0809.4101
On Gaussian MIMO BC-MAC Duality With Multiple Transmit Covariance Constraints
cs.IT math.IT
Owing to the structure of the Gaussian multiple-input multiple-output (MIMO) broadcast channel (BC), associated optimization problems such as capacity region computation and beamforming optimization are typically non-convex, and cannot be solved directly. One feasible approach to these problems is to transform them i...
0809.4149
Block Network Error Control Codes and Syndrome-based Complete Maximum Likelihood Decoding
cs.IT math.IT
In this paper, network error control coding is studied for robust and efficient multicast in a directed acyclic network with imperfect links. The block network error control coding framework, BNEC, is presented and the capability of the scheme to correct a mixture of symbol errors and packet erasures and to detect sy...
0809.4183
An Asymptotically Optimal RFID Authentication Protocol Against Relay Attacks
cs.CR cs.IT math.IT
Relay attacks are a major concern for RFID systems: during an authentication process an adversary transparently relays messages between a verifier and a remote legitimate prover. We present an authentication protocol suited for RFID systems. Our solution is the first that prevents relay attacks without degrading th...
0809.4296
State dependent computation using coupled recurrent networks
q-bio.NC cs.NE
Although conditional branching between possible behavioural states is a hallmark of intelligent behavior, very little is known about the neuronal mechanisms that support this processing. In a step toward solving this problem we demonstrate by theoretical analysis and simulation how networks of richly inter-connected ...
0809.4316
A Layered Lattice Coding Scheme for a Class of Three User Gaussian Interference Channels
cs.IT math.IT
The paper studies a class of three user Gaussian interference channels. A new layered lattice coding scheme is introduced as a transmission strategy. The use of lattice codes allows for an "alignment" of the interference observed at each receiver. The layered lattice coding is shown to achieve more than one degree of...
0809.4325
On the Unicast Capacity of Stationary Multi-channel Multi-radio Wireless Networks: Separability and Multi-channel Routing
cs.IT math.IT
The first result is on the separability of the unicast capacity of stationary multi-channel multi-radio wireless networks, i.e., whether the capacity of such a network is equal to the sum of the capacities of the corresponding single-channel single-radio wireless networks. For both the Arbitrary Network model and the...
0809.4484
Llull and Copeland Voting Computationally Resist Bribery and Control
cs.GT cs.CC cs.MA
The only systems previously known to be resistant to all the standard control types were highly artificial election systems created by hybridization. We study a parameterized version of Copeland voting, denoted by Copeland^\alpha, where the parameter \alpha is a rational number between 0 and 1 that specifies how ties...
0809.4501
Audio Classification from Time-Frequency Texture
cs.CV cs.SD
Time-frequency representations of audio signals often resemble texture images. This paper derives a simple audio classification algorithm based on treating sound spectrograms as texture images. The algorithm is inspired by an earlier visual classification scheme particularly efficient at classifying textures. While s...
0809.4529
The Equivalence of Semidefinite Relaxation MIMO Detectors for Higher-Order QAM
cs.IT math.IT math.OC
In multi-input-multi-output (MIMO) detection, semidefinite relaxation (SDR) has been shown to be an efficient high-performance approach. Developed initially for BPSK and QPSK, SDR has been found to be capable of providing near-optimal performance (for those constellations). This has stimulated a number of recent rese...
0809.4530
Mining Meaning from Wikipedia
cs.AI cs.CL cs.IR
Wikipedia is a goldmine of information; not just for its many readers, but also for the growing community of researchers who recognize it as a resource of exceptional scale and utility. It represents a vast investment of manual effort and judgment: a huge, constantly evolving tapestry of concepts and relations that i...
0809.4577
A Generic Top-Down Dynamic-Programming Approach to Prefix-Free Coding
cs.DS cs.IT math.IT
Given a probability distribution over a set of n words to be transmitted, the Huffman Coding problem is to find a minimal-cost prefix free code for transmitting those words. The basic Huffman coding problem can be solved in O(n log n) time but variations are more difficult. One of the standard techniques for solving ...
0809.4582
Achieving compositionality of the stable model semantics for Smodels programs
cs.AI
In this paper, a Gaifman-Shapiro-style module architecture is tailored to the case of Smodels programs under the stable model semantics. The composition of Smodels program modules is suitably limited by module conditions which ensure the compatibility of the module system with stable models. Hence the semantics of an...
0809.4622
A computational approach to the covert and overt deployment of spatial attention
cs.NE
Popular computational models of visual attention tend to neglect the influence of saccadic eye movements whereas it has been shown that the primates perform on average three of them per seconds and that the neural substrate for the deployment of attention and the execution of an eye movement might considerably overla...
0809.4632
Surrogate Learning - An Approach for Semi-Supervised Classification
cs.LG
We consider the task of learning a classifier from the feature space $\mathcal{X}$ to the set of classes $\mathcal{Y} = \{0, 1\}$, when the features can be partitioned into class-conditionally independent feature sets $\mathcal{X}_1$ and $\mathcal{X}_2$. We show the surprising fact that the class-conditional independ...
0809.4668
Faceted Ranking of Egos in Collaborative Tagging Systems
cs.IR
Multimedia uploaded content is tagged and recommended by users of collaborative systems, resulting in informal classifications also known as folksonomies. Faceted web ranking has been proved a reasonable alternative to a single ranking which does not take into account a personalized context. In this paper we analyze ...
0809.4743
The Imaginary Sliding Window As a New Data Structure for Adaptive Algorithms
cs.IT cs.DS math.IT
The scheme of the sliding window is known in Information Theory, Computer Science, the problem of predicting and in stastistics. Let a source with unknown statistics generate some word $... x_{-1}x_{0}x_{1}x_{2}...$ in some alphabet $A$. For every moment $t, t=... $ $-1, 0, 1, ...$, one stores the word ("window") $ x...
0809.4784
A Computational Study on Emotions and Temperament in Multi-Agent Systems
cs.AI cs.MA cs.RO
Recent advances in neurosciences and psychology have provided evidence that affective phenomena pervade intelligence at many levels, being inseparable from the cognitionaction loop. Perception, attention, memory, learning, decisionmaking, adaptation, communication and social interaction are some of the aspects influe...
0809.4804
On the Secure Degrees of Freedom of Wireless X Networks
cs.IT math.IT
Previous work showed that the X network with M transmitters, N receivers has MN/(M+N-1) degrees of freedom. In this work we study the degrees of freedom of the X network with secrecy constraints, i.e. the X network where some/all messages are confidential. We consider the $M \times N$ network where all messages are s...
0809.4807
Secure Wireless Communications via Cooperation
cs.IT math.IT
The feasibility of physical-layer-based security approaches for wireless communications in the presence of one or more eavesdroppers is hampered by channel conditions. In this paper, cooperation is investigated as an approach to overcome this problem and improve the performance of secure communications. In particular...
0809.4834
Relevance Feedback in Conceptual Image Retrieval: A User Evaluation
cs.IR
The Visual Object Information Retrieval (VOIR) system described in this paper implements an image retrieval approach that combines two layers, the conceptual and the visual layer. It uses terms from a textual thesaurus to represent the conceptual information and also works with image regions, the visual information. ...
0809.4882
Multi-Armed Bandits in Metric Spaces
cs.DS cs.LG
In a multi-armed bandit problem, an online algorithm chooses from a set of strategies in a sequence of trials so as to maximize the total payoff of the chosen strategies. While the performance of bandit algorithms with a small finite strategy set is quite well understood, bandit problems with large strategy sets are ...
0809.4883
Thresholded Basis Pursuit: An LP Algorithm for Achieving Optimal Support Recovery for Sparse and Approximately Sparse Signals from Noisy Random Measurements
cs.IT cs.LG math.IT
In this paper we present a linear programming solution for sign pattern recovery of a sparse signal from noisy random projections of the signal. We consider two types of noise models, input noise, where noise enters before the random projection; and output noise, where noise enters after the random projection. Sign p...
0809.5005
Simulated annealing for weighted polygon packing
cs.CG cs.AI
In this paper we present a new algorithm for a layout optimization problem: this concerns the placement of weighted polygons inside a circular container, the two objectives being to minimize imbalance of mass and to minimize the radius of the container. This problem carries real practical significance in industrial a...
0809.5008
Multi-Antenna Communication in Ad Hoc Networks: Achieving MIMO Gains with SIMO Transmission
cs.IT math.IT
The benefit of multi-antenna receivers is investigated in wireless ad hoc networks, and the main finding is that network throughput can be made to scale linearly with the number of receive antennas nR even if each transmitting node uses only a single antenna. This is in contrast to a large body of prior work in singl...
0809.5009
Delay Constrained Scheduling over Fading Channels: Optimal Policies for Monomial Energy-Cost Functions
cs.IT math.IT
A point-to-point discrete-time scheduling problem of transmitting $B$ information bits within $T$ hard delay deadline slots is considered assuming that the underlying energy-bit cost function is a convex monomial. The scheduling objective is to minimize the expected energy expenditure while satisfying the deadline co...
0809.5022
Network coding meets TCP
cs.NI cs.IT math.IT
We propose a mechanism that incorporates network coding into TCP with only minor changes to the protocol stack, thereby allowing incremental deployment. In our scheme, the source transmits random linear combinations of packets currently in the congestion window. At the heart of our scheme is a new interpretation of A...
0809.5023
Asymptotic stability region of slotted-Aloha
cs.IT math.IT
We analyze the stability of standard, buffered, slotted-Aloha systems. Specifically, we consider a set of $N$ users, each equipped with an infinite buffer. Packets arrive into user $i$'s buffer according to some stationary ergodic Markovian process of intensity $\lambda_i$. At the beginning of each slot, if user $i$ ...
0809.5087
Hybrid Neural Network Architecture for On-Line Learning
cs.NE
Approaches to machine intelligence based on brain models have stressed the use of neural networks for generalization. Here we propose the use of a hybrid neural network architecture that uses two kind of neural networks simultaneously: (i) a surface learning agent that quickly adapt to new modes of operation; and, (i...
0809.5096
Diversity Analysis of Bit-Interleaved Coded Multiple Beamforming
cs.IT math.IT
In this paper, diversity analysis of bit-interleaved coded multiple beamforming (BICMB) is extended to the case of general spatial interleavers, removing a condition on their previously known design criteria and quantifying the resulting diversity order. The diversity order is determined by a parameter Qmax which is ...
0809.5153
On a new multivariate sampling paradigm and a polyspline Shannon function
math.NA cs.IT math.IT
In the monograph Kounchev, O. I., Multivariate Polysplines. Applications to Numerical and Wavelet Analysis, Academic Press, San Diego-London, 2001, and in the paper Kounchev O., Render, H., Cardinal interpolation with polysplines on annuli, Journal of Approximation Theory 137 (2005) 89--107, we have introduced and st...
0809.5182
Perturbation-based Distributed Beamforming for Wireless Relay Networks
cs.IT math.IT
This paper deals with distributed beamforming techniques for wireless networks with half-duplex amplify-and-forward relays. Existing schemes optimize the beamforming weights based on the assumption that channel state information (CSI) is available at the relays. We propose to use adaptive beamforming based on determi...
0809.5191
A Coded Bit-Loading Linear Precoded Discrete Multitone Solution for Power Line Communication
cs.IT math.IT
Linear precoded discrete multitone modulation (LP-DMT) system has been already proved advantageous with adaptive resource allocation algorithm in a power line communication (PLC) context. In this paper, we investigate the bit and energy allocation algorithm of an adaptive LP-DMT system taking into account the channel...
0809.5204
A Distributed MAC Protocol for Cooperation in Random Access Networks
cs.IT math.IT
WLAN is one of the most successful applications of wireless communications in daily life because of low cost and ease of deployment. The enabling technique for this success is the use of random access schemes for the wireless channel. Random access requires minimal coordination between the nodes, which considerably r...
0809.5212
Secrecy Capacity over Correlated Ergodic Fading Channel
cs.IT math.IT
We investigate the secrecy capacity of an ergodic fading wiretap channel in which the main channel is correlated with the eavesdropper channel. In this study, the full Channel State Information (CSI) is assumed, and thus the transmitter knows the channel gains of the legitimate receiver and the eavesdropper. By analy...
0809.5217
Linear Universal Decoding for Compound Channels: a Local to Global Geometric Approach
cs.IT math.IT math.PR
Over discrete memoryless channels (DMC), linear decoders (maximizing additive metrics) afford several nice properties. In particular, if suitable encoders are employed, the use of decoding algorithm with manageable complexities is permitted. Maximum likelihood is an example of linear decoder. For a compound DMC, deco...
0809.5275
Coded Adaptive Linear Precoded Discrete Multitone Over PLC Channel
cs.IT math.IT
Discrete multitone modulation (DMT) systems exploit the capabilities of orthogonal subcarriers to cope efficiently with narrowband interference, high frequency attenuations and multipath fadings with the help of simple equalization filters. Adaptive linear precoded discrete multitone (LP-DMT) system is based on class...
0810.0068
On the Index Coding Problem and its Relation to Network Coding and Matroid Theory
cs.IT math.IT
The \emph{index coding} problem has recently attracted a significant attention from the research community due to its theoretical significance and applications in wireless ad-hoc networks. An instance of the index coding problem includes a sender that holds a set of information messages $X=\{x_1,...,x_k\}$ and a set ...
0810.0139
Determining the Unithood of Word Sequences using a Probabilistic Approach
cs.AI
Most research related to unithood were conducted as part of a larger effort for the determination of termhood. Consequently, novelties are rare in this small sub-field of term extraction. In addition, existing work were mostly empirically motivated and derived. We propose a new probabilistically-derived measure, inde...
0810.0154
Optimization of sequences in CDMA systems: a statistical-mechanics approach
cs.IT math.IT
Statistical mechanics approach is useful not only in analyzing macroscopic system performance of wireless communication systems, but also in discussing design problems of wireless communication systems. In this paper, we discuss a design problem of spreading sequences in code-division multiple-access (CDMA) systems, ...
0810.0156
Determining the Unithood of Word Sequences using Mutual Information and Independence Measure
cs.AI
Most works related to unithood were conducted as part of a larger effort for the determination of termhood. Consequently, the number of independent research that study the notion of unithood and produce dedicated techniques for measuring unithood is extremely small. We propose a new approach, independent of any influ...
0810.0200
Distribution of complexities in the Vai script
cs.CL
In the paper, we analyze the distribution of complexities in the Vai script, an indigenous syllabic writing system from Liberia. It is found that the uniformity hypothesis for complexities fails for this script. The models using Poisson distribution for the number of components and hyper-Poisson distribution for conn...
0810.0326
Collision Resolution by Exploiting Symbol Misalignment
cs.NI cs.IT math.IT
This paper presents CRESM, a novel collision resolution method for decoding collided packets in random-access wireless networks. In a collision, overlapping signals from several sources are received simultaneously at a receiver. CRESM exploits symbol misalignment among the overlapping signals to recover the individua...
0810.0332
Enhanced Integrated Scoring for Cleaning Dirty Texts
cs.AI
An increasing number of approaches for ontology engineering from text are gearing towards the use of online sources such as company intranet and the World Wide Web. Despite such rise, not much work can be found in aspects of preprocessing and cleaning dirty texts from online sources. This paper presents an enhancemen...
0810.0503
On the Capacity of One-sided Two user Gaussian Fading Broadcast Channels
cs.IT math.IT
In this paper, we investigate upper and lower bounds on the capacity of two-user fading broadcast channels where one of the users has a constant (non-fading) channel. We use the Costa entropy power inequality (EPI) along with an optimization framework to derive upper bounds on the sum-capacity and superposition codin...
0810.0532
Three New Complexity Results for Resource Allocation Problems
cs.MA cs.AI cs.CC cs.GT
We prove the following results for task allocation of indivisible resources: - The problem of finding a leximin-maximal resource allocation is in P if the agents have max-utility functions and atomic demands. - Deciding whether a resource allocation is Pareto-optimal is coNP-complete for agents with (1-)additive ...
0810.0567
Reed-Solomon Subcodes with Nontrivial Traces: Distance Properties and Soft-Decision Decoding
cs.IT math.IT
Reed-Solomon (RS) codes over GF$(2^m)$ have traditionally been the most popular non-binary codes in almost all practical applications. The distance properties of RS codes result in excellent performance under hard-decision bounded-distance decoding. However, efficient and implementable soft decoding for high-rate (ab...
0810.0747
A New Upper Bound on the Capacity of a Class of Primitive Relay Channels
cs.IT cs.AI math.IT
We obtain a new upper bound on the capacity of a class of discrete memoryless relay channels. For this class of relay channels, the relay observes an i.i.d. sequence $T$, which is independent of the channel input $X$. The channel is described by a set of probability transition functions $p(y|x,t)$ for all $(x,t,y)\in...
0810.0763
Errorless Codes for Over-loaded CDMA with Active User Detection
cs.IT math.IT
In this paper we introduce a new class of codes for over-loaded synchronous wireless CDMA systems which increases the number of users for a fixed number of chips without introducing any errors. In addition these codes support active user detection. We derive an upper bound on the number of users with a fixed spreadin...
0810.0764
A New Method for Constructing Large Size WBE Codes with Low Complexity ML Decoder
cs.IT math.IT
In this paper we wish to introduce a method to reconstruct large size Welch Bound Equality (WBE) codes from small size WBE codes. The advantage of these codes is that the implementation of ML decoder for the large size codes is reduced to implementation of ML decoder for the core codes. This leads to a drastic reduct...
0810.0785
Novel Bounds on the Capacity of the Binary Deletion Channel
cs.IT math.IT
We present novel bounds on the capacity of the independent and identically distributed binary deletion channel. Four upper bounds are obtained by providing the transmitter and the receiver with genie-aided information on suitably-defined random processes. Since some of the proposed bounds involve infinite series, we ...
0810.0830
Stiffness Analysis Of Multi-Chain Parallel Robotic Systems
cs.RO physics.class-ph
The paper presents a new stiffness modelling method for multi-chain parallel robotic manipulators with flexible links and compliant actuating joints. In contrast to other works, the method involves a FEA-based link stiffness evaluation and employs a new solution strategy of the kinetostatic equations, which allows co...
0810.0852
Evaluation of Authors and Journals
math.HO cs.IR physics.soc-ph
A method is presented for evaluating authors on the basis of citations. It assigns to each author a citation score which depends upon the number of times he is cited, and upon the scores of the citers. The scores are found to be the components of an eigenvector of a normalized citation matrix. The same method can be ...
0810.0870
Cognitive Radio with Partial Channel State Information at the Transmitter
cs.IT math.IT
In this paper, we present the cognitive radio system design with partial channel state information known at the transmitter (CSIT).We replace the dirty paper coding (DPC) used in the cognitive radio with full CSIT by the linear assignment Gel'fand-Pinsker coding (LA-GPC), which can utilize the limited knowledge of th...
0810.0877
Bias-Variance Techniques for Monte Carlo Optimization: Cross-validation for the CE Method
cs.NA cs.LG
In this paper, we examine the CE method in the broad context of Monte Carlo Optimization (MCO) and Parametric Learning (PL), a type of machine learning. A well-known overarching principle used to improve the performance of many PL algorithms is the bias-variance tradeoff. This tradeoff has been used to improve PL alg...
0810.0882
Asymptotic Eigenvalue Moments of Wishart-Type Random Matrix Without Ergodicity in One Channel Realization
cs.IT math.IT
Consider a random matrix whose variance profile is random. This random matrix is ergodic in one channel realization if, for each column and row, the empirical distribution of the squared magnitudes of elements therein converges to a nonrandom distribution. In this paper, noncrossing partition theory is employed to de...
0810.0883
Asymptotic Performance of Linear Receivers in MIMO Fading Channels
cs.IT math.IT
Linear receivers are an attractive low-complexity alternative to optimal processing for multi-antenna MIMO communications. In this paper we characterize the information-theoretic performance of MIMO linear receivers in two different asymptotic regimes. For fixed number of antennas, we investigate the limit of error p...
0810.1103
Channel and Multiuser Diversities in Wireless Systems: Delay-Energy Tradeoff
cs.IT math.IT
We consider a communication system with multi-access fading channel. Each user in the system requires certain rate guarantee. Our main contribution is to devise a scheduling scheme called "Opportunistic Super-position Coding" that satisfies the users' rate requirements. Using mean-field analysis, i.e., when the numbe...
0810.1105
Low-Density Parity-Check Codes Which Can Correct Three Errors Under Iterative Decoding
cs.IT math.IT
In this paper, we give necessary and sufficient conditions for low-density parity-check (LDPC) codes with column-weight three to correct three errors when decoded using hard-decision message-passing decoding. Additionally, we give necessary and sufficient conditions for column-weight-four codes to correct three error...
0810.1119
Gaussian Belief Propagation for Solving Systems of Linear Equations: Theory and Application
cs.IT math.IT
The canonical problem of solving a system of linear equations arises in numerous contexts in information theory, communication theory, and related fields. In this contribution, we develop a solution based upon Gaussian belief propagation (GaBP) that does not involve direct matrix inversion. The iterative nature of ou...
0810.1186
On-the-fly Macros
cs.AI
We present a domain-independent algorithm that computes macros in a novel way. Our algorithm computes macros "on-the-fly" for a given set of states and does not require previously learned or inferred information, nor prior domain knowledge. The algorithm is used to define new domain-independent tractable classes of c...
0810.1187
Interference Alignment for Secrecy
cs.IT math.IT
This paper studies the frequency/time selective $K$-user Gaussian interference channel with secrecy constraints. Two distinct models, namely the interference channel with confidential messages and the one with an external eavesdropper, are analyzed. The key difference between the two models is the lack of channel sta...
0810.1197
Construction of Near-Optimum Burst Erasure Correcting Low-Density Parity-Check Codes
cs.IT math.IT
In this paper, a simple, general-purpose and effective tool for the design of low-density parity-check (LDPC) codes for iterative correction of bursts of erasures is presented. The design method consists in starting from the parity-check matrix of an LDPC code and developing an optimized parity-check matrix, with the...
0810.1199
Une grammaire formelle du cr\'eole martiniquais pour la g\'en\'eration automatique
cs.CL
In this article, some first elements of a computational modelling of the grammar of the Martiniquese French Creole dialect are presented. The sources of inspiration for the modelling is the functional description given by Damoiseau (1984), and Pinalie's & Bernabe's (1999) grammar manual. Based on earlier works in tex...
0810.1207
A Layered Grammar Model: Using Tree-Adjoining Grammars to Build a Common Syntactic Kernel for Related Dialects
cs.CL
This article describes the design of a common syntactic description for the core grammar of a group of related dialects. The common description does not rely on an abstract sub-linguistic structure like a metagrammar: it consists in a single FS-LTAG where the actual specific language is included as one of the attribu...
0810.1212
Analyse spectrale des textes: d\'etection automatique des fronti\`eres de langue et de discours
cs.CL cs.IR
We propose a theoretical framework within which information on the vocabulary of a given corpus can be inferred on the basis of statistical information gathered on that corpus. Inferences can be made on the categories of the words in the vocabulary, and on their syntactical properties within particular languages. Bas...
0810.1234
On Resource Allocation in Fading Multiple Access Channels - An Efficient Approximate Projection Approach
cs.IT cs.NI math.IT math.OC
We consider the problem of rate and power allocation in a multiple-access channel. Our objective is to obtain rate and power allocation policies that maximize a general concave utility function of average transmission rates on the information theoretic capacity region of the multiple-access channel. Our policies does...
0810.1248
Resource Allocation in Multiple Access Channels
cs.IT cs.NI math.IT math.OC
We consider the problem of rate allocation in a Gaussian multiple-access channel, with the goal of maximizing a utility function over transmission rates. In contrast to the literature which focuses on linear utility functions, we study general concave utility functions. We present a gradient projection algorithm for ...
0810.1253
Dynamic Rate Allocation in Fading Multiple-access Channels
cs.IT cs.NI math.IT math.OC
We consider the problem of rate allocation in a fading Gaussian multiple-access channel (MAC) with fixed transmission powers. Our goal is to maximize a general concave utility function of transmission rates over the throughput capacity region. In contrast to earlier works in this context that propose solutions where ...
0810.1260
Rate and Power Allocation in Fading Multiple Access Channels
cs.IT cs.NI math.IT math.OC
We consider the problem of rate and power allocation in a fading multiple-access channel. Our objective is to obtain rate and power allocation policies that maximize a utility function defined over average transmission rates. In contrast with the literature, which focuses on the linear case, we present results for ge...
0810.1261
Soft Uncoupling of Markov Chains for Permeable Language Distinction: A New Algorithm
cs.CL cs.IR
Without prior knowledge, distinguishing different languages may be a hard task, especially when their borders are permeable. We develop an extension of spectral clustering -- a powerful unsupervised classification toolbox -- that is shown to resolve accurately the task of soft language distinction. At the heart of ou...
0810.1267
Information Theory vs. Queueing Theory for Resource Allocation in Multiple Access Channels
cs.IT cs.NI math.IT math.OC
We consider the problem of rate allocation in a fading Gaussian multiple-access channel with fixed transmission powers. The goal is to maximize a general concave utility function of the expected achieved rates of the users. There are different approaches to this problem in the literature. From an information theoreti...
0810.1268
Bi-directional half-duplex protocols with multiple relays
cs.IT math.IT
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 relay. In this work we consider bi-directional relaying with ...
0810.1319
ARQ-Based Secret Key Sharing
cs.IT cs.CR math.IT
This paper develops a novel framework for sharing secret keys using existing Automatic Repeat reQuest (ARQ) protocols. Our approach exploits the multi-path nature of the wireless environment to hide the key from passive eavesdroppers. The proposed framework does not assume the availability of any prior channel state ...
0810.1424
"Real" Slepian-Wolf Codes
cs.IT math.IT
We provide a novel achievability proof of the Slepian-Wolf theorem for i.i.d. sources over finite alphabets. We demonstrate that random codes that are linear over the real field achieve the classical Slepian-Wolf rate-region. For finite alphabets we show that typicality decoding is equivalent to solving an integer pr...
0810.1430
Blind Cognitive MAC Protocols
cs.NI cs.LG
We consider the design of cognitive Medium Access Control (MAC) protocols enabling an unlicensed (secondary) transmitter-receiver pair to communicate over the idle periods of a set of licensed channels, i.e., the primary network. The objective is to maximize data throughput while maintaining the synchronization betwe...
0810.1571
An Analytical Model of Information Dissemination for a Gossip-based Protocol
cs.DC cs.DM cs.IT cs.PF math.IT
We develop an analytical model of information dissemination for a gossiping protocol that combines both pull and push approaches. With this model we analyse how fast an item is replicated through a network, and how fast the item spreads in the network, and how fast the item covers the network. We also determine the o...
0810.1628
Distributed Kalman Filter via Gaussian Belief Propagation
cs.IT math.IT
Recent result shows how to compute distributively and efficiently the linear MMSE for the multiuser detection problem, using the Gaussian BP algorithm. In the current work, we extend this construction, and show that operating this algorithm twice on the matching inputs, has several interesting interpretations. First,...
0810.1631
Polynomial Linear Programming with Gaussian Belief Propagation
cs.IT math.IT
Interior-point methods are state-of-the-art algorithms for solving linear programming (LP) problems with polynomial complexity. Specifically, the Karmarkar algorithm typically solves LP problems in time O(n^{3.5}), where $n$ is the number of unknown variables. Karmarkar's celebrated algorithm is known to be an instan...
0810.1648
A Gaussian Belief Propagation Solver for Large Scale Support Vector Machines
cs.LG cs.IT math.IT
Support vector machines (SVMs) are an extremely successful type of classification and regression algorithms. Building an SVM entails solving a constrained convex quadratic programming problem, which is quadratic in the number of training samples. We introduce an efficient parallel implementation of an support vector ...
0810.1729
Gaussian Belief Propagation Based Multiuser Detection
cs.IT math.IT
In this work, we present a novel construction for solving the linear multiuser detection problem using the Gaussian Belief Propagation algorithm. Our algorithm yields an efficient, iterative and distributed implementation of the MMSE detector. We compare our algorithm's performance to a recent result and show an impr...
0810.1732
Introduction to Searching with Regular Expressions
cs.IR
The explosive rate of information growth and availability often makes it increasingly difficult to locate information pertinent to your needs. These problems are often compounded when keyword based search methodologies are not adequate for describing the information you seek. In many instances, information such as We...
0810.1735
Network Coding in a Multicast Switch
cs.NI cs.IT math.IT
The problem of serving multicast flows in a crossbar switch is considered. Intra-flow linear network coding is shown to achieve a larger rate region than the case without coding. A traffic pattern is presented which is achievable with coding but requires a switch speedup when coding is not allowed. The rate region wi...
0810.1736
Gaussian Belief Propagation Solver for Systems of Linear Equations
cs.IT math.IT
The canonical problem of solving a system of linear equations arises in numerous contexts in information theory, communication theory, and related fields. In this contribution, we develop a solution based upon Gaussian belief propagation (GaBP) that does not involve direct matrix inversion. The iterative nature of ou...
0810.1773
Finite Word Length Effects on Transmission Rate in Zero Forcing Linear Precoding for Multichannel DSL
cs.IT math.IT
Crosstalk interference is the limiting factor in transmission over copper lines. Crosstalk cancelation techniques show great potential for enabling the next leap in DSL transmission rates. An important issue when implementing crosstalk cancelation techniques in hardware is the effect of finite world length on perform...
0810.1808
A Central Limit Theorem for the SINR at the LMMSE Estimator Output for Large Dimensional Signals
cs.IT math.IT
This paper is devoted to the performance study of the Linear Minimum Mean Squared Error estimator for multidimensional signals in the large dimension regime. Such an estimator is frequently encountered in wireless communications and in array processing, and the Signal to Interference and Noise Ratio (SINR) at its out...
0810.1973
Alphabet Sizes of Auxiliary Variables in Canonical Inner Bounds
cs.IT math.IT
Alphabet size of auxiliary random variables in our canonical description is derived. Our analysis improves upon estimates known in special cases, and generalizes to an arbitrary multiterminal setup. The salient steps include decomposition of constituent rate polytopes into orthants, translation of a hyperplane till i...
0810.1980
Error Exponents of Optimum Decoding for the Interference Channel
cs.IT math.IT
Exponential error bounds for the finite-alphabet interference channel (IFC) with two transmitter-receiver pairs, are investigated under the random coding regime. Our focus is on optimum decoding, as opposed to heuristic decoding rules that have been used in previous works, like joint typicality decoding, decoding bas...
0810.1991
A global physician-oriented medical information system
cs.CY cs.AI cs.DB
We propose to improve medical decision making and reduce global health care costs by employing a free Internet-based medical information system with two main target groups: practicing physicians and medical researchers. After acquiring patients' consent, physicians enter medical histories, physiological data and symp...
0810.1997
Characterizing 1-Dof Henneberg-I graphs with efficient configuration spaces
cs.CG cs.RO cs.SC
We define and study exact, efficient representations of realization spaces of a natural class of underconstrained 2D Euclidean Distance Constraint Systems(EDCS) or Frameworks based on 1-dof Henneberg-I graphs. Each representation corresponds to a choice of parameters and yields a different parametrized configuration ...
0810.2021
Visualization Optimization : Application to the RoboCup Rescue Domain
cs.GR cs.AI
In this paper we demonstrate the use of intelligent optimization methodologies on the visualization optimization of virtual / simulated environments. The problem of automatic selection of an optimized set of views, which better describes an on-going simulation over a virtual environment is addressed in the context of...
0810.2046
Modeling of Social Transitions Using Intelligent Systems
cs.AI
In this study, we reproduce two new hybrid intelligent systems, involve three prominent intelligent computing and approximate reasoning methods: Self Organizing feature Map (SOM), Neruo-Fuzzy Inference System and Rough Set Theory (RST),called SONFIS and SORST. We show how our algorithms can be construed as a linkage ...
0810.2133
Diversity-Multiplexing Tradeoff of the Half-Duplex Relay Channel
cs.IT math.IT
We show that the diversity-multiplexing tradeoff of a half-duplex single-relay channel with identically distributed Rayleigh fading channel gains meets the 2 by 1 MISO bound. We generalize the result to the case when there are N non-interfering relays and show that the diversity-multiplexing tradeoff is equal to the ...
0810.2144
Asymptotics of Entropy Rate in Special Families of Hidden Markov Chains
cs.IT math.IT
We derive an asymptotic formula for entropy rate of a hidden Markov chain around a "weak Black Hole". We also discuss applications of the asymptotic formula to the asymptotic behaviors of certain channels.
0810.2164
Joint source-channel coding via statistical mechanics: thermal equilibrium between the source and the channel
cs.IT math.IT
We examine the classical joint source--channel coding problem from the viewpoint of statistical physics and demonstrate that in the random coding regime, the posterior probability distribution of the source given the channel output is dominated by source sequences, which exhibit a behavior that is highly parallel to ...
0810.2208
Multipath Channels of Unbounded Capacity
cs.IT math.IT
The capacity of discrete-time, noncoherent, multipath fading channels is considered. It is shown that if the variances of the path gains decay faster than exponentially, then capacity is unbounded in the transmit power.
0810.2311
Non-Negative Matrix Factorization, Convexity and Isometry
cs.AI cs.CV
In this paper we explore avenues for improving the reliability of dimensionality reduction methods such as Non-Negative Matrix Factorization (NMF) as interpretive exploratory data analysis tools. We first explore the difficulties of the optimization problem underlying NMF, showing for the first time that non-trivial ...
0810.2323
On Outage and Error Rate Analysis of the Ordered V-BLAST
cs.IT math.IT
Outage and error rate performance of the ordered BLAST with more than 2 transmit antennas is evaluated for i.i.d. Rayleigh fading channels. A number of lower and upper bounds on the 1st step outage probability at any SNR are derived, which are further used to obtain accurate approximations to average block and total ...
0810.2336
A Mordell Inequality for Lattices over Maximal Orders
math.MG cs.IT math.IT math.NT
In this paper we prove an analogue of Mordell's inequality for lattices in finite-dimensional complex or quaternionic Hermitian space that are modules over a maximal order in an imaginary quadratic number field or a totally definite rational quaternion algebra. This inequality implies that the 16-dimensional Barnes-W...
0810.2352
Interference Channels with Correlated Receiver Side Information
cs.IT math.IT
The problem of joint source-channel coding in transmitting independent sources over interference channels with correlated receiver side information is studied. When each receiver has side information correlated with its own desired source, it is shown that source-channel code separation is optimal. When each receiver...
0810.2390
Efficient Pattern Matching on Binary Strings
cs.DS cs.IR
The binary string matching problem consists in finding all the occurrences of a pattern in a text where both strings are built on a binary alphabet. This is an interesting problem in computer science, since binary data are omnipresent in telecom and computer network applications. Moreover the problem finds applicatio...