ppxscal/embedding_network huggingface dataset:
Fixing convergence of Gaussian belief propagation
Authors: Jason K. Johnson, Danny Bickson, Danny Dolev
Venue: Proceedings of the 2009 IEEE international conference on Symposium on Information Theory - Volume 3 (2009)

Gaussian belief propagation (GaBP) is an iterative message-passing algorithm for inference in Gaussian graphical models. It is known that when GaBP converges it converges to the correct MAP estimate of the Gaussian random vector and simple sufficient conditions for its convergence have been established. In this paper we develop a double-loop algorithm for forcing convergence of GaBP. Our method computes the correct MAP estimate even in cases where standard GaBP would not have converged. We further extend this construction to compute least-squares solutions of over-constrained linear systems. We believe that our construction has numerous applications, since the GaBP algorithm is linked to solution of linear systems of equations, which is a fundamental problem in computer science and engineering. As a case study, we discuss the linear detection problem. We show that using our new construction, we are able to force convergence of Montanari's linear detection algorithm, in cases where it would originally fail. As a consequence, we are able to increase significantly the number of users that can transmit concurrently.
Image quality based comparative evaluation of wavelet filters in ultrasound speckle reduction
Authors: Ashish Thakur, R. S. Anand
Venue: Digital Signal Processing (2005)

This paper presents the comparative study of various wavelet filter based denoising methods according to different thresholding values applied to ultrasound images. An original image is transformed into a multi scale wavelet domain and the wavelet coefficients are processed by a soft thresholding method. The denoised image is the output image obtained from the inverse wavelet transform of the threshold coefficients using Donoho's method. It has been observed that such denoising methods are effective in the sense that they preserve the edge details besides suppressing the noise. The comparative evaluation of the denoising performance is shown using statistical significance tests for different wavelet filters. Image quality parameters such as peak signal-to-noise ratio, normalized mean square error, and correlation coefficient have been used to evaluate the performance of wavelet filters. The performance has also been compared with the adaptive weighted median filtering method.
Infinite-layer codes for single-user slowly fading MIMO channels
Authors: Vahid Pourahmadi, Abolfazl S. Motahari, Amir K. Khandani
Venue: Proceedings of the 2009 IEEE international conference on Symposium on Information Theory - Volume 3 (2009)

Given a slowly fading channel, the performance of multi-layer coding is studied for single-user scenarios. Both the source and destination are equipped with multiple antennas. The channel state information is perfectly known at the destination but not at the source. The objective is to maximize the average data rate received at the destination when the destination is able to perform successive decoding. This paper, first, proposes a design rule for constructing an infinite-layer code for Multiple Input Multiple Output (MIMO) channels. Furthermore, we present a procedure describing how the introduced design rule is applied to optimally determine the multi-layer code parameters. The achievable rate of the multi-layer coding and successive decoding for the Rayleigh fading 2xtimes;2 MIMO channel is also evaluated.
On multiple access random medium access control
Authors: Tao Cui, Tracey Ho
Venue: Proceedings of the 2009 IEEE international conference on Symposium on Information Theory - Volume 3 (2009)

In this paper, we develop a new class of medium access control protocol, which allows each user to transmit at different data rates chosen randomly from an appropriately determined set of rates. By using successive interference cancellation, multiple packets can be received simultaneously. In slotted Aloha type Gaussian networks, we show that the achievable total throughput of the proposed protocol is at least a constant fraction of the mac sum rate when the number of transmission rates at each node is equal to the number of users in the network. We also study the case when only a limited number of transmission rates is available at each node. Extension to rate splitting is discussed. Simulation results show that the proposed protocol can achieve a significant throughput gain over the conventional Aloha.
Optimum filter design for quantized multidimensional subband filter bank
Authors: Kyusik Park, Jaehyun Park
Venue: Digital Signal Processing (2005)

This paper provides a rigorous theory for analysis of quantization effects and optimum filter bank design in quantized multidimensional subband filter banks. Each pdf-optimized quantizer is modeled by a nonlinear gain-plus-additive uncorrelated noise and embedded into the subband structure. Using polyphase decomposition of the analysis/synthesis filter banks, we derive the exact expression for the output mean square quantization error. Based on the minimization of the output mean square error, the technique for optimal filter design methodology is developed. Numerical design examples for optimum nonseparable paraunitary and biorthogonal filter banks are presented with a quincunx subsampling lattice.
A distributed algorithm for interference aware routing in wireless networks
Authors: Aravind Mohanoor, Sridhar Radhakrishnan, Venkatesh Sarangan
Venue: Proceedings of the 6th IEEE Conference on Consumer Communications and Networking Conference (2009)

We can improve the end-to-end throughput between a sender and receiver in a wireless network using multiple paths which do not interfere with each other. Given finding such paths is computationally hard, we present a heuristic that is amenable to distributed implementation. This heuristic allows for the possibility of interfering links but schedules the transmission in ways to achieve the maximum possible throughput. One can characterize interfering links as either destructive or non-destructive, the latter of which does not affect the throughput, if transmission is properly scheduled. We present a distributed algorithm which exploits this knowledge to find multiple s-t paths such that high throughputs could be achieved despite the interference. On a wireless network with n nodes, our distributed algorithm has a time and message complexity of O(n2).
A session-based management architecture for QoS assurance to VoIP applications on wireless access networks
Authors: Badis Tebbani, Kamel Haddadou, Guy Pujolle
Venue: Proceedings of the 6th IEEE Conference on Consumer Communications and Networking Conference (2009)

The increasing popularity of WLANs -due to the use of license-free radio spectrum with low-cost, easily deployable and high-data-rate wireless services- has encouraged service providers to consider deploying them in high density usage areas, such as public hotspots, to provide complementary broadband access to their networks and services. This article proposes a Session Initiation Protocol based QoS management architecture that aims to provide consistent QoS control for multimedia applications (VoIP, VoD, . . . ) over wireless access networks. In particular, we will present a generic QoS based management architecture for decentralized management of multimedia applications over wireless access networks, such as WLAN. We will apply our architecture to the management of the WLAN in order to assure QoS (throughput and delay) for the delivered multi-media applications according to users' priorities and providers' objectives. Performance evaluations are discussed to illustrate the feasibility and the efficiency of the proposed architecture through the implementation of a real-world testbed.
Simple channel coding bounds
Authors: Ligong Wang, Roger Colbeck, Renato Renner
Venue: Proceedings of the 2009 IEEE international conference on Symposium on Information Theory - Volume 3 (2009)

New channel coding converse and achievability bounds are derived for a single use of an arbitrary channel. Both bounds are expressed using a quantity called the "smooth 0-divergence", which is a generalization of Rényi's divergence of order 0. The bounds are also studied in the limit of large blocklengths. In particular, they combine to give a general capacity formula which is equivalent to the one derived by Verdú and Han.
On the throughput allocation for proportional fairness in multirate IEEE 802.11 DCF
Authors: F. Daneshgaran, M. Laddomada, F. Mesiti, M. Mondin
Venue: Proceedings of the 6th IEEE Conference on Consumer Communications and Networking Conference (2009)

This paper presents a modified proportional fairness (PF) criterion suitable for mitigating the rate anomaly problem of multirate IEEE 802.11 Wireless LANs employing the mandatory Distributed Coordination Function (DCF) option. Compared to the widely adopted assumption of saturated network, the proposed criterion can be applied to general networks whereby the contending stations are characterized by specific packet arrival rates, λs, and transmission rates Rds. The throughput allocation resulting from the proposed algorithm is able to greatly increase the aggregate throughput of the DCF while ensuring fairness levels among the stations of the same order of the ones available with the classical PF criterion. Put simply, each station is allocated a throughput that depends on a suitable normalization of its packet rate, which, to some extent, measures the frequency by which the station tries to gain access to the channel. Simulation results are presented for some sample scenarios, confirming the effectiveness of the proposed criterion.
Key dependent operation and algorithm specific complexity of statistical side channel attacks
Authors: Jens Rüdinger, Adolf Finger
Venue: Proceedings of the 16th international conference on Telecommunications (2009)

This paper analyzes the design of cryptograpbic algorithm and the effect of their vulnerability towards statistical side channel attacks. On the example of the DPA attack by Kocher the complexity of the statistical side channel attacks and their dependency on algorithmic parameters is shown. In particular key dependent operation are considered and their effect is illustrated on the example of the block cipher algorithm AES and Twofish. It is shown that the careful selection or design of algorithms can increase the security of implementations of algorithms in addition to and independent from conventional DPA attack countenneasures.
Embedding maximum entropy models in algebraic varieties by Gröbner bases methods
Authors: Ambedkar Dukkipati
Venue: Proceedings of the 2009 IEEE international conference on Symposium on Information Theory - Volume 3 (2009)

The main aim of this paper is to present some notions on how results from commutative algebra and algebraic geometry could be used in representation and computation of maximum entropy (ME) models in the cases, where an integer valued sufficient statistic exists. We give an implicit description of ME-models by embedding them in algebraic varieties for which we use Gröbner bases methods. We prove that in the case of ME, both the model and the data can be represented by algebraic varieties.
Views on personal networks and business opportunities
Authors: Rune Roswall, Iwona Windekilde
Venue: Proceedings of the 6th IEEE Conference on Consumer Communications and Networking Conference (2009)

The EU project MAGNET-Beyond has examined the business opportunities regarding Personal Networks (PN) for the typical value network stakeholders. In the current communication markets, companies deliver services to customers in cooperation with other market players profiting on different business opportunities. The aim has been to examine new business opportunities PNs. This work consists of three main elements: a) classification and categorisation of different business opportunity areas, b) an overview of relevant Industry trends, c) explanation of stakeholder opportunities and the strategies that they could develop for the commercialisation of the PN technology.
Delay-optimal power control and performance analysis in SDMA system with limited buffer size via stochastic decomposition
Authors: Liangzhong Ruan, Vincent K. N. Lau
Venue: Proceedings of the 2009 IEEE international conference on Symposium on Information Theory - Volume 2 (2009)

In previous study on multi-user delay optimal problem, the exponentially increasing state space become one of the main obstacle. Moreover, packet drop due to finite buffer size is not taken into account. In this paper, we exploit the birth-death dynamics of the buffered SDMA systems and proposed a new approach, namely stochastic decomposition, to derive the delay optimal power adaptation scheme in a SDMA system. Unlike the conventional CSI-only power control solution, the delay-optimal power control has the multi-level water-filling structure in which the QSI determines the water-level and the CSI determines the power allocation across the SDMA users. This new approach overcomes the complexity issue mentioned above and allow us to obtain closed-form performance expressions so as to obtain the following first-order insights: 1) The water-filling levels {1/αk,qNk} under different QSIs q ∈ {1, 2, ...L} is an increasing geometric series. 2) The optimal average delay Uk* achieved by the multilevel water filling algorithm is τ/O(log Pk) + O(log log Pk)-λk while that achieved by traditional CSI-only scheme is (τ/O(log Pk)-λk ċ 3) Minimum average power required to satisfy a packet drop rate constraint ơd (due to finite buffer) is given by: log log (Pk,min) α -log ơd/L + log(λ>k) + log(Nk).
Robust initial LLRs for iterative decoders in presence of non-Gaussian noise
Authors: Arun Ayyar, Michael Lentmaier, K. Giridhar, Gerhard Fettweis
Venue: Proceedings of the 2009 IEEE international conference on Symposium on Information Theory - Volume 2 (2009)

We consider the decoding of LDPC codes in presence of non-Gaussian noise, especially a set of ơ-mixture models. For each of these models, the optimal LLRs are presented. We study the performance degradation due to the use of incorrect LLR in presence of a given noise model. Without modifying the existing LDPC decoder, we propose robust initial LLR which require minimum knowledge about the underlying noise model and are computationally less complex. Since BER simulations are computationally heavy, we use density evolution to compare the thresholds of different LLRs.
Evaluation of image sequence additive decomposition algorithms for membrane analysis in fluorescence video-microscopy
Authors: A. Chessel, T. Pécot, S. Bardin, C. Kervrann, J. Salamero
Venue: Proceedings of the Sixth IEEE international conference on Symposium on Biomedical Imaging: From Nano to Macro (2009)

A wide range of proteins viewed using xFP probes in fluorescence video-microscopy shows a cytosolic state diffusing slowly and a membrane state eventually moving as vesicles or small tubules along the cell cytoskeleton network. Due to the property of fluorescence, the measured intensity is the sum of the contributions of these two components. In this study we perform an evaluation of different methods for the automatic decomposition of the two additive components/ states. Four algorithms are studied: i) gray-scale opening (a.k.a. "rolling ball"); ii) wavelet-based detection combined with image interpolation; iii) Conditional Random Field-based detection; iv) computational geometry for temporal signal analysis. The evaluation protocol, related to the actual use of image sequence decomposition, includes a qualitative evaluation on real image sequences by experts and a quantitative evaluation on simulated sequences that mimic real images.
Stopping set analysis of repeat multiple-accumulate codes
Authors: Alexandre Graell i Amat, Eirik Rosnes
Venue: Proceedings of the 2009 IEEE international conference on Symposium on Information Theory - Volume 3 (2009)

In this work, we consider a stopping set analysis of repeat multiple-accumulate (RMA) code ensembles formed by the serial concatenation of a repetition code with multiple accumulators. The RMA codes are assumed to be iteratively decoded in a constituent code oriented fashion using maximum a posteriori erasure correction in the constituent codes. We give stopping set enumerators for RMA code ensembles and show that their stopping distance hmin, defined as the size of the smallest nonempty stopping set, asymptotically grows linearly with the block length. Thus, the RMA code ensembles are good for the binary erasure channel. Furthermore, it is shown that, contrary to the asymptotic minimum distance dmin, whose growth rate coefficient increases with the number of accumulate codes, the hmin growth rate coefficient diminishes with the number of accumulators. We also consider random puncturing and show that for sufficiently high code rates, the asymptotic hmin does not grow linearly with the block length, contrary to the asymptotic dmin, whose growth rate coefficient approaches the Gilbert-Varshamov bound as the rate increases. Finally, we give iterative decoding thresholds to show the convergence properties.
New sum-rate upper bound for the two-user Gaussian interference channel
Authors: Raul Etkin
Venue: Proceedings of the 2009 IEEE international conference on Symposium on Information Theory - Volume 4 (2009)

A new upper bound for the sum-capacity of the two-user complex Gaussian interference channel is derived. The bound is based on genies that provide side information signals to the receivers. Various parameters are introduced to control the side information, which can be optimized to get the tightest possible bound. The new bound improves the performance of the best known bounds for sufficiently small cross-gains.
Acquiarium: free software for the acquisition and analysis of 3D images of cells in fluorescence microscopy
Authors: Pavel Matula, Martin Maška, Ondřej Danek, Petr Matula, Michal Kozubek
Venue: Proceedings of the Sixth IEEE international conference on Symposium on Biomedical Imaging: From Nano to Macro (2009)

This paper describes free software (called Acquiarium, http://cbia.fi.muni.cz/acquiarium.html) for carrying out the common pipeline of many spatial cell studies using fluorescence microscopy. It addresses image capture, raw image correction, image segmentation, the quantification and spatial arrangement of segmented objects, volume rendering, and statistical evaluation. The software is designed for the easy processing of a collection of many 3D images. It can be used for the analysis of a collection of 2D images or time lapse series of 2D or 3D images as well. It has a modular design and is extensible via plug-ins. The paper gives an overview of the software and its key design ideas.
Raptor packets: a packet-centric approach to distributed raptor code design
Authors: Dejan Vukobratovic, Čedomir Stefanovic, Miloš Stojakovic, Vladimir Stankovic
Venue: Proceedings of the 2009 IEEE international conference on Symposium on Information Theory - Volume 4 (2009)

In this paper, we address the problem of distributed Raptor code design over information packets located across the network nodes. We propose a novel approach to this problem that consists of generating, encoding and dispersing Raptor packets across the network. Unlike recent node-centric proposals, where network nodes are responsible for collecting information packets and performing Raptor encoding, in the proposed packet-centric approach this task is assigned to Raptor packets. In a two-step encoding procedure that corresponds to precoding and LT-coding step of standard Raptor encoding, Raptor packets randomly traverse the network, collect and encode sufficient number of information packets following exactly a given degree distribution, and finish their paths in a random network node. The efficiency of the distributed Raptor coding scheme is confirmed by simulation results, where their performance is demonstrated to approach closely the performance of standard (centralized) Raptor codes.
Adaptive configuration of pervasive computing system with QoS consideration
Authors: Weiyi Zhang, Jun Kong, Kendall Nygard, Ming Li
Venue: Proceedings of the 6th IEEE Conference on Consumer Communications and Networking Conference (2009)

User mobility in pervasive computing makes it fundamentally different from traditional desktop computing. Accordingly, the system configurations, such as resource allocation and routing, are extremely dynamic since available resources and users' needs may change when users are moving around different locations. There have been extensive works on the resource allocation for the users' needs. However, previous works did not consider complex situations, such as conflicting relations between different applications. This paper models a pervasive computing system from three parts: available network resources, available applications, and conflicting relations of the applications. To configure the system according to the dynamical changes, our work focuses on how to find the best set of applications, under the network resource and QoS routing constraints, to achieve the maximum system benefit for the users. We first propose an optimal solution using Integer Linear Programming (ILP) scheme. Then a simple and effective heuristic is presented for better scalability. Extensive simulation results demonstrate that our ILP and heuristic achieve very good performance.
Service oriented wireless sensor network toolbox for consumer applications
Authors: Jongwoo Sung, Taehong Kim, Seonghoon Kim, Kyubaek Kim, Jang Gwan Im, Daeyoung Kim
Venue: Proceedings of the 6th IEEE Conference on Consumer Communications and Networking Conference (2009)

Service-oriented computing which provides flexible composition of various applications using multiple reusable services has getting more attractive. We propose a service oriented wireless sensor networks toolbox, which encapsulates complexities of sensor networks and enables simple service compositions using an intuitive GUI. We utilize sensor networks as a collection of services that are discovered and coordinated by users. Service metadata which are self-describing service capabilities and interfaces are defined and exposed via our service metadata repositories. A service oriented sensor network toolbox consisting of sensor networks, an intuitive GUI application that retrieves metadata for discovered services and helps users to composite various roles are presented.
Invertible extractors and wiretap protocols
Authors: Mahdi Cheraghchi, Frédéric Didier, Amin Shokrollahi
Venue: Proceedings of the 2009 IEEE international conference on Symposium on Information Theory - Volume 3 (2009)

A wiretap protocol is a pair of randomized encoding and decoding functions such that knowledge of a bounded fraction of the encoding of a message reveals essentially no information about the message, while knowledge of the entire encoding reveals the message using the decoder. In this paper we study the notion of efficiently invertible extractors and show that a wiretap protocol can be constructed from such an extractor. We will then construct invertible extractors for symbol-fixing, affine, and general sources and apply them to create wiretap protocols with asymptotically optimal trade-offs between their rate (ratio of the length of the message versus its encoding) and resilience (ratio of the observed positions of the encoding) and the length of the encoding). We will then apply our results to create wiretap protocols for challenging communication problems, such as active intruders who change portions of the encoding, network coding, and intruders observing arbitrary boolean functions of the encoding.