OpenRaiser/Intern-Atlas huggingface dataset:
Mobile Anchor Assisted Node Localization for Wireless Sensor Networks
Venue: arXiv cs.IT 2009
Year: 2009

In this paper, a cooperative localization algorithm is proposed that considers the existence of obstacles in mobilityassisted wireless sensor networks (WSNs). In this scheme, a mobile anchor (MA) node cooperates with static sensor nodes and moves actively to refine location performance. The localization accuracy of the proposed algorithm can be improved further by changing the transmission range of mobile anchor node. The algorithm takes advantage of cooperation betweenMAs and static sensors while, at the same time, taking into account the relay node availability to make the best use of beacon signals. For achieving high localization accuracy and coverage, a novel convex position estimation algorithm is proposed, which can effectively solve the localization problem when infeasible points occur because of the effects of radio irregularity and obstacles. This method is the only range-free based convex method to solve the localization problem when the feasible set of localization inequalities is empty. Simulation results demonstrate the effectiveness of this algorithm.
Efficient methodology for implementation of Encrypted File System in User Space
Venue: arXiv cs.CR 2009
Year: 2009

The Encrypted File System (EFS) pushes encryption services into the file system itself. EFS supports secure storage at the system level through a standard UNIX file system interface to encrypted files. User can associate a cryptographic key with the directories they wish to protect. Files in these directories (as well as their pathname components) are transparently encrypted and decrypted with the specified key without further user intervention; clear text is never stored on a disk or sent to a remote file server. EFS can use any available file system for its underlying storage without modifications, including remote file servers such as NFS. System management functions, such as file backup, work in a normal manner and without knowledge of the key. Performance is an important factor to users since encryption can be time consuming. This paper describes the design and implementation of EFS in user space using faster cryptographic algorithms on UNIX Operating system. Implementing EFS in user space makes it portable and flexible; Kernel size will also not increase resulting in more reliable & efficient Operating System. Encryption techniques for file system level encryption are described, and general issues of cryptographic system interfaces to support routine secure computing are discussed.
Understanding Groups' Properties as a Means of Improving Collaborative Search Systems
Venue: arXiv cs.IR 2009
Year: 2009

Understanding the similar properties of people involved in group search sessions has the potential to significantly improve collaborative search systems; such systems could be enhanced by information retrieval algorithms and user interface modifications that take advantage of important properties, for example by re-ordering search results using information from group members' combined user profiles. Understanding what makes group members similar can also assist with the identification of groups, which can be valuable for connecting users with others with whom they might undertake a collaborative search. In this workshop paper, we describe our current research efforts towards studying the properties of a variety of group types. We discuss properties of groups that may be relevant to designers of collaborative search systems, and propose ways in which understanding such properties could influence the design of interfaces and algorithms for collaborative Web search.
Max-Flow Protection using Network Coding
Venue: arXiv cs.NI 2009
Year: 2009

In any communication network, the maximum number of link-disjoint paths between any pair of communicating nodes, S and T, is limited by the S-T minimum link-cut. Multipath routing protocols have been proposed in the literature to make use of these S-T paths in enhancing the survivability of the S-T information flow. This is usually accomplished by using a subset of these paths to forward redundant data units or combinations (if network coding is allowed) from S to T. Therefore, this enhancement in survivability reduces the useful S-T information rate. In this paper we present a new way to enhance the survivability of the S-T information flow without compromising the maximum achievable S-T information rate. To do this, bottleneck links (in the min-cut) should only forward useful information, and not redundant data units. We introduce the idea of extra source or destination connectivity with respect to a certain S-T max-flow, and then we study two problems: namely, pre-cut protection and post-cut protection. Although our objective in both problems is the same, where we aim to maximize the number of protected paths, our analysis shows that the nature of these two problems are very different, and that the pre-cut protection problem is much harder. Specifically, we prove the hardness of the pre-cut protection problem, formulate it as an integer linear program, and propose a heuristic approach to solve it. Simulations show that the performance of the heuristic is acceptable even on relatively large networks. In the post-cut problem we show that all the data units, forwarded by the min-cut edges not incident to T, can be post-cut-protected.
Performance analysis for sparse support recovery
Venue: arXiv cs.IT 2009
Year: 2009

The performance of estimating the common support for jointly sparse signals based on their projections onto lower-dimensional space is analyzed. Support recovery is formulated as a multiple-hypothesis testing problem. Both upper and lower bounds on the probability of error are derived for general measurement matrices, by using the Chernoff bound and Fano's inequality, respectively. The upper bound shows that the performance is determined by a quantity measuring the measurement matrix incoherence, while the lower bound reveals the importance of the total measurement gain. The lower bound is applied to derive the minimal number of samples needed for accurate direction-of-arrival (DOA) estimation for a sparse representation based algorithm. When applied to Gaussian measurement ensembles, these bounds give necessary and sufficient conditions for a vanishing probability of error for majority realizations of the measurement matrix. Our results offer surprising insights into sparse signal recovery. For example, as far as support recovery is concerned, the well-known bound in Compressive Sensing with the Gaussian measurement matrix is generally not sufficient unless the noise level is low. Our study provides an alternative performance measure, one that is natural and important in practice, for signal recovery in Compressive Sensing and other application areas exploiting signal sparsity.
Top-down Paradigm in Engineering Software Integration
Venue: arXiv cs.CE 2009
Year: 2009

The top-down approach of engineering software integration is considered in this parer. A set of advantages of this approach are presented, by examples. All examples are supplied by open source code.
An Exploratory Analysis of the Impact of Named Ranges on the Debugging Performance of Novice Users
Venue: arXiv cs.HC 2009
Year: 2009

This paper describes an exploratory empirical study of the effect of named ranges on spreadsheet debugging performance. Named ranges are advocated in both academia and industry, yet no experimental evidence has been cited to back up these recommendations. This paper describes an exploratory experiment involving 21 participants that assesses the performance of novices debugging a spreadsheet containing named ranges. The results are compared with the performance of a different set of novices debugging the same spreadsheet without named ranges. The findings suggest that novice users debug on average significantly fewer errors if the spreadsheet contains named ranges. The purpose of the investigative study is to derive a detailed and coherent set of research questions regarding the impact of range names on the debugging performance and behaviour of spreadsheet users. These will be answered through future controlled experiments.
Clustering for Improved Learning in Maze Traversal Problem
Venue: arXiv cs.LG 2009
Year: 2009

The maze traversal problem (finding the shortest distance to the goal from any position in a maze) has been an interesting challenge in computational intelligence. Recent work has shown that the cellular simultaneous recurrent neural network (CSRN) can solve this problem for simple mazes. This thesis focuses on exploiting relevant information about the maze to improve learning and decrease the training time for the CSRN to solve mazes. Appropriate variables are identified to create useful clusters using relevant information. The CSRN was next modified to allow for an additional external input. With this additional input, several methods were tested and results show that clustering the mazes improves the overall learning of the traversal problem for the CSRN.
A Secure Multi-Party Computation Protocol for Malicious Computation Prevention for preserving privacy during Data Mining
Venue: arXiv cs.CR 2009
Year: 2009

Secure Multi-Party Computation (SMC) allows parties with similar background to compute results upon their private data, minimizing the threat of disclosure. The exponential increase in sensitive data that needs to be passed upon networked computers and the stupendous growth of internet has precipitated vast opportunities for cooperative computation, where parties come together to facilitate computations and draw out conclusions that are mutually beneficial; at the same time aspiring to keep their private data secure. These computations are generally required to be done between competitors, who are obviously weary of each-others intentions. SMC caters not only to the needs of such parties but also provides plausible solutions to individual organizations for problems like privacy-preserving database query, privacy-preserving scientific computations, privacy-preserving intrusion detection and privacy-preserving data mining. This paper is an extension to a previously proposed protocol Encrytpo_Random, which presented a plain sailing yet effective approach to SMC and also put forward an aptly crafted architecture, whereby such an efficient protocol, involving the parties that have come forward for joint-computations and the third party who undertakes such computations, can be developed. Through this extended work an attempt has been made to further strengthen the existing protocol thus paving the way for a more secure multi-party computational process.
Transmission Performance Analysis of Digital Wire and Wireless Optical Links in Local and Wide Areas Optical Networks
Venue: arXiv cs.PF 2009
Year: 2009

In the present paper, the transmission performance analysis of digital wire and wireless optical links in local and wide areas optical networks have been modeled and parametrically investigated over wide range of the affecting parameters. Moreover, we have analyzed the basic equations of the comparative study of the performance of digital fiber optic links with wire and wireless optical links. The development of optical wireless communication systems is accelerating as a high cost effective to wire fiber optic links. The optical wireless technology is used mostly in wide bandwidth data transmission applications. Finally, we have investigated the maximum transmission distance and data transmission bit rates that can be achieved within digital wire and wireless optical links for local and wide areas optical network applications.
Trellis Coded Modulation for Two-User Unequal-Rate Gaussian MAC
Venue: arXiv cs.IT 2009
Year: 2009

In this paper, code pairs based on trellis coded modulation are proposed over PSK signal sets for a two-user Gaussian multiple access channel. In order to provide unique decodability property to the receiver and to maximally enlarge the constellation constrained (CC) capacity region, a relative angle of rotation is introduced between the signal sets. Subsequently, the structure of the \textit{sum alphabet} of two PSK signal sets is exploited to prove that Ungerboeck labelling on the trellis of each user maximizes the guaranteed minimum squared Euclidean distance, $d^{2}_{g, min}$ in the \textit{sum trellis}. Hence, such a labelling scheme can be used systematically to construct trellis code pairs for a two-user GMAC to approach \emph{any rate pair} within the capacity region.
Side-channel attack on labeling CAPTCHAs
Venue: arXiv cs.CR 2009
Year: 2009

We propose a new scheme of attack on the Microsoft's ASIRRA CAPTCHA which represents a significant shortcut to the intended attacking path, as it is not based in any advance in the state of the art on the field of image recognition. After studying the ASIRRA Public Corpus, we conclude that the security margin as stated by their authors seems to be quite optimistic. Then, we analyze which of the studied parameters for the image files seems to disclose the most valuable information for helping in correct classification, arriving at a surprising discovery. This represents a completely new approach to breaking CAPTCHAs that can be applied to many of the currently proposed image-labeling algorithms, and to prove this point we show how to use the very same approach against the HumanAuth CAPTCHA. Lastly, we investigate some measures that could be used to secure the ASIRRA and HumanAuth schemes, but conclude no easy solutions are at hand.
Real Interference Alignment with Real Numbers
Venue: arXiv cs.IT 2009
Year: 2009

A novel coding scheme applicable in networks with single antenna nodes is proposed. This scheme converts a single antenna system to an equivalent Multiple Input Multiple Output (MIMO) system with fractional dimensions. Interference can be aligned along these dimensions and higher Multiplexing gains can be achieved. Tools from the field of Diophantine approximation in number theory are used to show that the proposed coding scheme in fact mimics the traditional schemes used in MIMO systems where each data stream is sent along a direction and alignment happens when several streams arrive at the same direction. Two types of constellation are proposed for the encoding part, namely the single layer constellation and the multi-layer constellation. Using the single layer constellation, the coding scheme is applied to the two-user $X$ channel and the three-user Gaussian Interference Channel (GIC). In case of the two-user $X$ channel, it is proved that the total Degrees-of-Freedom (DOF), i.e. 4/3, of the channel is achievable almost surely. This is the first example in which it is shown that a time invariant single antenna system does not fall short of achieving its total DOF. Using the multi-layer constellation, the coding scheme is applied to the symmetric three-user GIC. Achievable DOFs are derived for all channel gains. As a function of the channel gain, it is observed that the DOF is everywhere discontinuous.
Exposing Pseudoweight Layers in Regular LDPC Code Ensembles
Venue: arXiv cs.IT 2009
Year: 2009

A solution is presented for the asymptotic growth rate of the AWGN-pseudoweight distribution of regular low-density parity-check (LDPC) code ensembles for a selected graph cover degree M >= 1. The evaluation of the growth rate requires solution of a system of 2M+1 nonlinear equations in 2M+1 unknowns. Simulation results for the pseudoweight distribution of two regular LDPC code ensembles are presented for graph covers of low degree.
Segmentation for radar images based on active contour
Venue: arXiv cs.CV 2009
Year: 2009

We exam various geometric active contour methods for radar image segmentation. Due to special properties of radar images, we propose our new model based on modified Chan-Vese functional. Our method is efficient in separating non-meteorological noises from meteorological images.
Planar Drawings of Higher-Genus Graphs
Venue: arXiv cs.CG 2009
Year: 2009

In this paper, we give polynomial-time algorithms that can take a graph G with a given combinatorial embedding on an orientable surface S of genus g and produce a planar drawing of G in R^2, with a bounding face defined by a polygonal schema P for S. Our drawings are planar, but they allow for multiple copies of vertices and edges on P's boundary, which is a common way of visualizing higher-genus graphs in the plane. Our drawings can be defined with respect to either a canonical polygonal schema or a polygonal cutset schema, which provides an interesting tradeoff, since canonical schemas have fewer sides, and have a nice topological structure, but they can have many more repeated vertices and edges than general polygonal cutsets. As a side note, we show that it is NP-complete to determine whether a given graph embedded in a genus-g surface has a set of 2g fundamental cycles with vertex-disjoint interiors, which would be desirable from a graph-drawing perspective.
Problems in application of LDPC codes to information reconciliation in quantum key distribution protocols
Venue: arXiv cs.IT 2009
Year: 2009

The information reconciliation in a quantum key distribution protocol can be studied separately from other steps in the protocol. The problem of information reconciliation can be reduced to that of distributed source coding. Its solution by LDPC codes is reviewed. We list some obstacles preventing the LDPC-based distributed source coding from becoming a more favorable alternative to the Cascade protocol for information reconciliation in quantum key distribution protocols. This exposition does not require knowledge of the quantum theory.
Distributed Source Coding with One Distortion Criterion and Correlated Messages
Venue: arXiv cs.IT 2009
Year: 2009

In this paper, distributed (or multiterminal) source coding with one distortion criterion and correlated messages is considered. This problem can be also called ``Berger-Yeung problem with correlated messages''. It corresponds to the source coding part of the graph-based framework for transmission of a pair of correlated sources over the multiple-access channel (MAC) where one is lossless and the other is lossy. As a result, the achievable rate-distortion region for this problem is provided. It is an information-theoretic characterization of the rate of exponential growth (as a function of the number of source samples) of the size of the bipartite graphs which can represent a pair of correlated sources with satisfying one distortion criterion. A rigorous proof of the achievability and the converse part is given. It is also shown that there exists functional duality between Berger-Yeung problem with correlated messages and semi-deterministic broadcast channel with correlated messages. This means that the optimal encoder-decoder mappings for one problem become the optimal decoder-encoder mappings for the dual problem. In the duality setup, the correlation structure of the messages in the two dual problems, source distortion measure and channel cost measure are also specified.
Transmitting an analog Gaussian source over a Gaussian wiretap channel under SNR mismatch
Venue: arXiv cs.IT 2009
Year: 2009

In this work we study encoding/decoding schemes for the transmission of a discrete time analog Gaussian source over a Gaussian wiretap channel. The intended receiver is assumed to have a certain minimum signal to noise ratio (SNR) and the eavesdropper is assumed to have a strictly lower SNR compared to the intended receiver. For a fixed information leakage to the eavesdropper, we are interested in minimizing the distortion in source reconstruction at the intended receiver, and we propose joint source channel coding (JSCC) schemes for this setup. For a fixed information leakage to the eavesdropper, we also show that the schemes considered give a graceful degradation of distortion with SNR under SNR mismatch, i.e., when the actual channel SNR is observed to be different from the design SNR.
ARQ Secrecy: From Theory to Practice
Venue: arXiv cs.IT 2009
Year: 2009

Inspired by our earlier work on Automatic Repeat reQuest (ARQ) secrecy, we propose a simple, yet efficient, security overlay protocol to existing 802.11 networks. Our work targets networks secured by the Wired Equivalent Privacy (WEP) protocol because of its widespread use and vulnerability to a multitude of security threats. By exploiting the existing ARQ protocol in the 802.11 standard, our proposed opportunistic secrecy scheme is shown to defend against all known passive WEP attacks. Moreover, our implementation on the madwifi-ng driver is used to establish the achievability of a vanishing secrecy outage probability in several realistic scenarios.
MR-BART: Multi-Rate Available Bandwidth Estimation in Real-Time
Venue: arXiv cs.NI 2009
Year: 2009

In this paper, we propose Multi-Rate Bandwidth Available in Real Time (MR-BART) to estimate the end-to-end Available Bandwidth (AB) of a network path. The proposed scheme is an extension of the Bandwidth Available in Real Time (BART) which employs multi-rate (MR) probe packet sequences with Kalman filtering. Comparing to BART, we show that the proposed method is more robust and converges faster than that of BART and achieves a more AB accurate estimation. Furthermore, we analyze the estimation error in MR-BART and obtain analytical formula and empirical expression for the AB estimation error based on the system parameters.
On the Decay of the Determinants of Multiuser MIMO Lattice Codes
Venue: arXiv cs.IT 2009
Year: 2009

In a recent work, Coronel et al. initiated the study of the relation between the diversity-multiplexing tradeoff (DMT) performance of a multiuser multiple-input multiple-output (MU-MIMO) lattice code and the rate of the decay of the determinants of the code matrix as a function of the size of the signal constellation. In this note, we state a simple general upper bound on the decay function and study the promising code proposed by Badr and Belfiore in close detail. We derive a lower bound to its decay function based on a classical theorem due to Liouville. The resulting bound is applicable also to other codes with constructions based on algebraic number theory. Further, we study an example sequence of small determinants within the Badr-Belfiore code and derive a tighter upper bound to its decay function. The upper bound has certain conjectural asymptotic uncertainties, whence we also list the exact bound for several finite data rates.
A Secure and Efficient Protocol for Group Key agreement in Heterogeneous Environment
Venue: arXiv cs.CR 2009
Year: 2009

Secure group communication in heterogeneous environment is gaining popularity due to the advent of wireless and ubiquitous computing. Although a number of protocols for group key agreement have been proposed, most of them are not applicable in heterogeneous environment where a number of computationally limited nodes coexist with one or more computationally efficient nodes. Among the few existing protocols, where some fail to satisfy the key agreement properties, some are unable to handle the agreement for dynamic group. In this work, we propose a constant round group key agreement protocol for heterogeneous environment using polynomial interpolation. The protocol ensures both communication and computation efficiency by shifting the major computation load on powerful users, achieves true contributory key agreement property and dynamic handling of user join and leave. The security of the protocol has been analyzed under formal model. The comparison result shows considerable improvement in protocol efficiency compared to the existing ones.