ppxscal/embedding_network huggingface dataset:
Decay of correlations in low density parity check codes: low noise regime
Authors: Shrinivas Kudekar, Nicolas Macris
Venue: Proceedings of the 2009 IEEE international conference on Symposium on Information Theory - Volume 4 (2009)

Consider transmission over a binary additive white gaussian noise channel using a fixed low-density parity check code. We consider the posterior measure over the code bits and the corresponding correlation between two codebits, averaged over the noise realizations. We show that for low enough noise variance this average correlation decays exponentially fast with the graph distance between the code bits. One consequence of this result is that for low enough noise variance the GEXIT functions (further averaged over a standard code ensemble) of the belief propagation and optimal decoders are the same.
SLINCS: a social link based evaluation system for network coordinate systems
Authors: Xiaoxiao Song, Xiaohan Zhao, Eng Keong Lua, Zengbin Zhang, Beixing Deng, Xing Li
Venue: Proceedings of the 6th IEEE Conference on Consumer Communications and Networking Conference (2009)

In recent research work of securing Network Coordinate (NC) system, they concentrate on the passive security defense mechanisms. In this paper we propose SLINCS, a social link based evaluation security system that utilizes information from existing social relationship networks to implement proactive security mechanisms for NC systems. The key idea is to eliminate suspicious nodes before they launch potential attacks.
A distributed differential space-time coding scheme for two-way wireless relay networks
Authors: Zoran Utkovski, Gilbert Yammine, Juergen Lindner
Venue: Proceedings of the 2009 IEEE international conference on Symposium on Information Theory - Volume 2 (2009)

We propose a distributed differential space-time coding scheme for two-way relaying over unknown block Rayleigh fading channels. The accent is on a two-time slots scheme, where in the first stage both terminals transmit their signals to the relays and in the second stage the relays broadcast to the terminals. Although we do not assume channel knowledge neither at the relays nor at the terminals, we show that it is possible for the terminals to subtract their contribution from the broadcasted signal and decide on the desired signal from the other terminal. The performance analysis reveals that the two-time slots differential scheme offers advantage over the traditional four-time slots differential scheme.
Transformations of Markov processes in fault tolerant interconnected systems
Authors: Jorge R. Chávez-Fuentes, Oscar R. González, W. Steven Gray
Venue: Proceedings of the 2009 conference on American Control Conference (2009)

Safety-critical control systems use fault tolerant interconnections of components to minimize the effect of randomly triggered faults. The system availability process indicates whether or not the interconnection is operating correctly at each time instant. It is a 2- state process that results from the transformation of the stochastic processes characterizing the availability processes of the interconnected components. To analyze closed-loop systems controlled by these fault tolerant interconnected components, it is important to determine the characteristics of the system availability process. When the availability processes of the interconnected components are independent homogeneous Markov chains, the statistical nature of the system availability process is characterized. In particular, it is shown that the system availability process is not necessarily Markov, but has a well-defined one-step transition probability matrix that approaches a constant stochastic matrix at steady-state. Since it is simpler to analyze switched closed-loop systems when the switching process is Markov, conditions for the system availability process to be a Markov chain for all initial distributions are determined. A sufficient stability condition is given when the system availability process is a non-homogeneous Markov chain for a class of initial distributions.
Area-efficient nonrestoring radix-2k division
Authors: A. E. Bashagha
Venue: Digital Signal Processing (2005)

This paper presents an area-efficient twos complement high radix division algorithm and its architecture. The advantage of using high radix division is to generate more quotient bits per iteration while binary division results in one bit per iteration. In the conventional restoring radix-2^k division, the selection of the quotient digit requires the use of all the multiples of the divisor. As a result, the area increases exponentially (area of radix 2^k divider is about 2^k times the area of binary divider) while the speed increases linearly (speed of radix 2^k divider is approximately k times that of binary divider). In this paper, a new algorithm that makes use only of the even multiples of the divisor is proposed. The area is nearly halved since the number of multiples is reduced from 2^k to 2^k^-^1. We use the even multiples rather than the odd ones because the even multiples are easier to generate and some of them are produced by simply shifting the divisor. For example, the even multiples 2D and 4D are generated by shifting D one and two bits to the left, respectively, while the odd multiples 3D and 5D require an addition of D to 2D and D to 4D, respectively.
Performance of polar codes for channel and source coding
Authors: Nadine Hussami, Satish Babu Korada, Rüdiger Urbanke
Venue: Proceedings of the 2009 IEEE international conference on Symposium on Information Theory - Volume 3 (2009)

Polar codes, introduced recently by Arikan, are the first family of codes known to achieve capacity of symmetric channels using a low complexity successive cancellation decoder. Although these codes, com bined with successive cancellation, are optimal in this respect, their finite-length performance is not record breaking. We discuss several techniques through which their finite-length performance can be improved. We also study the performance of these codes in the context of source coding, both loss less and lossy, in the single-user context as well as for distributed applications.
On the fundamental system of cycles in the bipartite graphs of LDPC code ensembles
Authors: Igal Sason
Venue: Proceedings of the 2009 IEEE international conference on Symposium on Information Theory - Volume 1 (2009)

This work introduces an information-theoretic lower bound on the number of fundamental cycles for bipartite graphs of low-density parity-check (LDPC) code ensembles. This information-theoretic bound is expressed in terms of the achievable gap to capacity when the transmission of the code ensemble takes place over a memoryless binary-input output-symmetric (MBIOS) channel. The bound shows quantitatively the necessity of cycles in bipartite graphs which represent good LDPC code ensembles. More explicitly, it shows that the number of fundamental cycles should grow at least like log 1/Ɛ where Ɛ designates the gap in rate to capacity, hence, it is unbounded as the gap to capacity vanishes. For the derivation of this bound, a new information-theoretic lower bound on the average right degree, which also behaves like log 1/Ɛ, is derived. The interested reader is referred to the full paper version [9].
Methods for improving medium reuse in IEEE 802.11 networks
Authors: Simone Merlin, Santosh Abraham
Venue: Proceedings of the 6th IEEE Conference on Consumer Communications and Networking Conference (2009)

In this paper we identify the mechanisms in the IEEE 802.11 standard which limit medium reuse by not allowing concurrent transmissions even when they are actually possible. To improve medium reuse we propose an interference management protocol, PCONAV, which cognitively enables and disables the virtual (NAV) and physical carrier sensing (CCA) according to the interference environment. We combine this mechanisms with address filtering and capture and demonstrate improved medium reuse. The proposed cognitive mechanisms are further enhanced with a tuning mechanism that adapts the carrier sensing threshold (CST) at each node. Simulations are used to show the improved performance obtained with each of the proposed mechanisms.
Robust access based on speaker identification for optical communications security
Authors: L. Zão, A. Alcaim, R. Coelho
Venue: Proceedings of the 16th international conference on Digital Signal Processing (2009)

A robust biometric access system for optical communications based on a speaker identification authentication is proposed in this paper. The solution also enables optical access with remote speaker identification. A set of speech features and classifiers were defined to achieve the best recognition rates. The experiments demonstrated the feasibility and importance of using the biometric technology for the optical communications security.
Renal tumor quantification and classification in triple-phase contrast-enhanced abdominal CT
Authors: Marius George Linguraru, Rabindra Gautam, James Peterson, Jianhua Yao, W. Marston Linehan, Ronald M. Summers
Venue: Proceedings of the Sixth IEEE international conference on Symposium on Biomedical Imaging: From Nano to Macro (2009)

It is estimated that a quarter of a million people in the USA are living with kidney cancer. In clinical practice, the response to treatment is monitored by manual measurements of tumor size, which are time consuming and show high intra- and inter-operator variability. We propose a computer-assisted radiology tool to assess renal tumors in contrast-enhanced CT for the management of tumor diagnoses and treatments. The algorithm employs anisotropic diffusion, a combination of fast-marching and geodesic level-sets, and a novel statistical refinement step to adapt to the shape of the lesions. It also quantifies the 3D size, volume and enhancement of the lesion and allows serial management of tumors. The comparison between manual and semi-automated quantifications shows disparity within the limits of inter-observer variability. The automated tumor classification shows great separation between cysts, von Hippel-Lindau syndrome (VHL) lesions and hereditary papillary renal carcinomas (HPRC) (p < 0.004).
On the achievable diversity-multiplexing tradeoff in interference channels
Authors: Cemal Akcaba, Helmut Bölcskei
Venue: Proceedings of the 2009 IEEE international conference on Symposium on Information Theory - Volume 3 (2009)

We analyze two-user single-antenna fading interference channels with perfect receive channel state information (CSI) and no transmit CSI. For the case of very strong interference, we prove that decoding interference while treating the intended signal as noise, subtracting the result out, and then decoding the desired signal, a process known as "stripping", achieves the diversity multiplexing tradeoff (DMT) outer bound derived in Akuiyibo and Lévêque, Int. Zurich Seminar on Commun., 2008. The proof is constructive in the sense that it provides corresponding code design criteria for DMT optimality. For general interference levels, we compute the DMT of a fixed-power-split Han and Kobayashi type superposition coding scheme, provide design criteria for the corresponding superposition codes, and find that this scheme is DMT-optimal for certain multiplexing rates.
Energy-efficient video transmission scheduling for wireless peer-to-peer live streaming
Authors: Ying Li, Zhu Li, Mung Chiang, A. Robert Calderbank
Venue: Proceedings of the 6th IEEE Conference on Consumer Communications and Networking Conference (2009)

The Peer-to-Peer (P2P) streaming has shown as an effective solution for wireline video applications, while for the wireless video streaming applications, the limited radio resource and battery energy are the main constraints on the way of P2P applications. An important issue in live video streaming quality of service is to avoid playback buffer underflow, and a challenge from wireless applications is the desire of energy efficiency. The problem we try to solve is how to utilize P2P schemes in video streaming and schedule the video transmission among peers to minimize the "freeze-ups" in playback caused by buffer underflow. In this work, we propose energy-efficient algorithm for the video transmission scheduling in wireless P2P live streaming system, to minimize the playback freeze-ups among peers. Further the algorithm is extended to two scenarios: peers' reluctance of consuming battery energy and allowing overhearing, with alternative energy-efficient algorithms proposed for the second scenario. Numerical results show the effectiveness of the proposed algorithms. The results also demonstrate that peers' selfishness may reduce the energy efficiency, but allowing overhearing could increase energy efficiency.
Theoretical foundations for conceptual modelling in information systems development
Authors: Yair Wand, David E. Monarchi, Jeffrey Parsons, Carson C. Woo
Venue: Decision Support Systems (1995)

Conceptual modelling in information systems development is the creation of an enterprise model for the purpose of designing the information system. It is an important aspect of systems analysis. The value of a conceptual modelling language (CML) lies in its ability to capture the relevant knowledge about a domain. To determine which constructs should be included in a CML it would be beneficial to use some theoretical guidelines. However, this is usually not done. The purpose of this paper is to promote the idea that theories related to human knowledge can be used as foundations for conceptual modelling in systems development. We suggest the use of ontology, concept theory, and speech act theory. These approaches were chosen because: (1) they deal with important and different aspects relevant to conceptual modelling and (2) they have already been used in the context of systems analysis. For each approach we discuss: the rationale for its use, its principles, its application to conceptual modelling, and its limitations. We also demonstrate the concepts of the three approaches by analysing an example. The analysis also serves to show how each approach deals with different aspects of modelling.
Efficient linear filtering of encrypted signals via composite representation
Authors: Tiziano Bianchi, Alessandro Piva, Mauro Barni
Venue: Proceedings of the 16th international conference on Digital Signal Processing (2009)

Signal processing tools working on encrypted data provide an efficient solution when sensitive signals must be protected from an untrusted processing device. In this paper, we investigate an issue usually neglected in the proposed solutions for secure signal processing, that is the huge size augmentation from the plaintext to the sample-wise encrypted representation of signals, due to the use of cryptosystems operating on very large algebraic structures. A composite signal representation is proposed that allows to speed up linear filtering on encrypted signals via parallel processing and to reduce the size of encrypted signals. A case study is proposed and discussed.
A centralized spectrum sharing scheme for access points in IEEE 802.11 networks
Authors: Bongkyoung Kwon, John A. Copeland
Venue: Proceedings of the 6th IEEE Conference on Consumer Communications and Networking Conference (2009)

we apply the concept of the common spectrum coordination channel (CSCC) etiquette protocol to form a spectrum sharing protocol among access points in 802.11 networks. It efficiently allocates operating frequencies among access points. As a result, it reduces interference from wireless devices using the 802.11 MAC/PHY protocol. This is motivated by the lack of intelligent spectrum sharing among Wi-Fi access points. We show that the CSCC protocol is not suitable for point to multipoint (PMP) networks. Through simulation, our proposed spectrum sharing protocol improves throughput and reduces media access delay in Wi-Fi networks.
Estimation of the distribution of randomly deployed wireless sensors
Authors: Babar H. Khan, Mérouane Debbah, Øyvind Ryan, Tareq Y. AI-Naffouri
Venue: Proceedings of the 2009 IEEE international conference on Symposium on Information Theory - Volume 4 (2009)

The distribution of randomly deployed wireless sensors plays an important role in the quality of the methods used for data acquisition and signal reconstruction. Mathematically speaking, the estimation of the distribution of randomly deployed sensors can be related to computing the spectrum of Vandermonde matrices with non-uniform entries. In this paper, we use the recent free deconvolution framework to recover, in noisy environments, the asymptotic moments of the structured random Vandermonde matrices and relate these moments to the distribution of the randomly deployed sensors. Remarkably, the results are valid in the finite case using only a limited number of sensors and samples.
Robust incorporation of anatomical priors into limited view tomography using multiple cluster modelling of the joint histogram
Authors: Dominique Van De Sompel, Sir Michael Brady
Venue: Proceedings of the Sixth IEEE international conference on Symposium on Biomedical Imaging: From Nano to Macro (2009)

We apply the joint entropy prior to limited view transmission tomography and demonstrate its sensitivity to local optima. We propose to increase robustness by modelling the joint histogram as the sum of a limited number of bivariate clusters. The method is illustrated for the case of Gaussian distributions. This approximation increases robustness by reducing the possible number of local optima in the cost function. The resulting reconstruction prior mimicks the behaviour of the joint entropy prior in that it narrows clusters in the joint histogram, and yields promisingly accurate reconstruction results despite the null space problem.
On the sum capacity of a class of cyclically symmetric deterministic interference channels
Authors: Bernd Bandemer, Gonzalo Vazquez-Vilar, Abbas El Gamal
Venue: Proceedings of the 2009 IEEE international conference on Symposium on Information Theory - Volume 4 (2009)

Certain deterministic interference channels have been shown to accurately model Gaussian interference channels in the asymptotic low-noise regime. Motivated by this correspondence, we investigate a K user-pair, cyclically symmetric, deterministic interference channel in which each receiver experiences interference only from its neighboring transmitters (Wyner model). We establish the sum capacity for a large set of channel parameters, thus generalizing previous results for the 2-pair case.
Multicasting in large random wireless networks: bounds on the minimum energy per bit
Authors: Arnan Jain, Sanjeev R. Kulkarni, Sergio Verdú
Venue: Proceedings of the 2009 IEEE international conference on Symposium on Information Theory - Volume 4 (2009)

We consider scaling laws for maximal energy efficiency of communicating a message to all the nodes in a random wireless network, as the number of nodes in the network becomes large. Two cases of large wireless networks are studied -- dense random networks and constant density (extended) random networks. We first establish an information-theoretic lower bound on the minimum energy per bit for multicasting that holds for arbitrary wireless networks when the channel state information is not available at the transmitters. These lower bounds are then evaluated for two cases of random networks. Upper bounds are also obtained by constructing a simple flooding scheme that requires no information at the receivers about the channel states or the locations and identities of the nodes. The gap between the upper and lower bounds is only a constant factor for dense random networks and differs by a poly-logarithmic factor for extended random networks. Furthermore, the proposed upper and lower bounds hold almost surely in the node locations as the number of nodes approaches infinity.
A load balanced aware routing protocol for wireless ad hoc networks
Authors: Vahid Nazari Talooki, Jonathan Rodriguez, Rasool Sadeghi
Venue: Proceedings of the 16th international conference on Telecommunications (2009)

Nodes in ad hoc networks can be unfairly burdened to support many packet-relaying functions, resulting in excessive loads on these hot spots. This load on nodes appears in two major aspects: traffic and power consumption. Unbalanced traffic may lead to more delay, packet dropping, and decreasing packet delivery ratio (PDR). Unbalanced energy consumption leads to node failure, network partitioning and decreases network lifetime and route reliability. Existing approaches try to improve the performance of routing protocols with respect to traffic balancing or energy consumption balancing, but most lead to drawbacks such as more delay, blocking, or dependence on global information from all nodes. In this paper we improve the well known Dynamic Source Routing (DSR) protocol to the so called Load Balanced DSR (LBDSR) protocol. We modify the RREQ (Route Request) and RREP (Route Reply) messages in DSR in order to maintain the remaining energy of intermediate nodes which forward RREQ and RREP. Route structure, available in the nodes cache, is modified so that the remaining energy of nodes can be calculated. LBDSR shows better traffic balancing and energy consumption balancing, end-ta-end delay and route reliability metrics than DSR. Furthermore, LBDSR can also be customized to achieve better performance with respect to each of these metrics instead of being a trade-off between them.
Structured variational methods for distributed inference: convergence analysis and performance-complexity tradeoff
Authors: Yanbing Zhang, Huaiyu Dai
Venue: Proceedings of the 2009 IEEE international conference on Symposium on Information Theory - Volume 2 (2009)

In this paper, the asymptotic performance of a recently proposed distributed inference framework, structured variational methods, is investigated. We first distinguish the intra- and inter-cluster inference algorithms as vertex and edge processes respectively. Their difference is illustrated, and convergence rate is derived for the intra-cluster inference procedure which is based on an edge process. Then, viewed as a mixed vertex-edge process, the overall performance of structured variational methods is characterized via the coupling approach. Tradeoff between complexity and performance of this algorithm is also addressed, which provides insights for network design and analysis.
Upper bounds to error probability with feedback
Authors: Baris Nakiboǧlu, Lizhong Zheng
Venue: Proceedings of the 2009 IEEE international conference on Symposium on Information Theory - Volume 3 (2009)

A new technique is proposed for upper bounding the error probability of fixed length block codes with feedback. Error analysis is inspired by Gallager's error analysis for block codes without feedback. Zigangirov-D'yachkov (Z-D) encoding scheme is analyzed with the technique on binary input channels and k-ary symmetric channels. A strict improvement is obtained for k-ary symmetric channels.
A framework for mobile, context-aware applications
Authors: Suparna De, Klaus Moessner
Venue: Proceedings of the 16th international conference on Telecommunications (2009)

The heterogeneous, dynamic nature of current mobile environments necessitates that all system components that form part of a personalization framework should be context aware. This necessitates the development of a framework of distributed context handlers to derive meaning from context and combine it with application logic. Towards this aim, this paper presents a Service Context Manager (SCM) framework that handles all the stages of context gathering, processing and reasoning to enable personalized service presentation. The validation of the approach is sbown through application use cases.