ppxscal/embedding_network huggingface dataset:
Effect of MMSE channel estimation on BER performance of orthogonal space-time block codes in rayleigh fading channels
Authors: Lennert Jacobs, Marc Moeneclaey
Venue: IEEE Transactions on Communications (2009)

We present a simple closed-form expression for the BER of orthogonal space-time block codes (OSTBCs) with MMSE channel estimation, assuming PAM and QAM constellations and flat Rayleigh block fading. The BER expression is exact for a certain class of OSTBCs, and provides a very accurate approximation for other OSTBCs.
VoIP capacity analysis in cognitive radio system
Authors: Howon Lee, Dong-Ho Cho
Venue: IEEE Communications Letters (2009)

In this letter, we analyze a voice over IP (VoIP) capacity in a cognitive radio system. We formulate the system as a two-dimensional discrete time Markov chain (DTMC). The VoIP traffic and wireless channel in the cognitive radio system are described as a Markov modulated Poisson process (MMPP) model and a Markov channel model, respectively. We demonstrate various numerical and simulation results, such as packet dropping probability and VoIP capacity.
Some Strong Limit Theorems Relative to the Geometric Average of Random Transition Probabilities of Nonhomogenemous Markov Chains Indexed by a Tree
Authors: Huashan Wang, Weiguo Yang, Zhiyan Shi
Venue: Proceedings of the 2009 Second International Workshop on Computer Science and Engineering - Volume 02 (2009)

In this paper, we study some strong limit theorems relative to the geometric average of random transition probabilities of nonhomogeneous Markov chains indexed by a tree. This result is an extension of some strong limit theorems relative to the geometric average of random transition probabilities of arbitrary finite nonhomogeneous Markov chains.
Joint application of STBC and RAKE receivers in multipath Rayleigh fading channels
Authors: Szu-Chi Wang, Wei-Sen Lin, Hsiao-Hwa Chen
Venue: IEEE Communications Letters (2009)

This letter investigates the issues on joint application of STBC systems and RAKE receivers in a CDMA system. We show the advantages of using STBC-RAKE receivers in multipath Rayleigh fading channels via error probability analysis and extensive computer simulations. Specifically, this study leads to a better understanding of the interplay between spatial diversity by STBC and multipath diversity via RAKE receivers.
Chaos theory based detection against network mimicking DDoS attacks
Authors: Ashley Chonka, Jaipal Singh, Wanlei Zhou
Venue: IEEE Communications Letters (2009)

DDoS attack traffic is difficult to differentiate from legitimate network traffic during transit from the attacker, or zombies, to the victim. In this paper, we use the theory of network self-similarity to differentiate DDoS flooding attack traffic from legitimate self-similar traffic in the network. We observed that DDoS traffic causes a strange attractor to develop in the pattern of network traffic. From this observation, we developed a neural network detector trained by our DDoS prediction algorithm. Our preliminary experiments and analysis indicate that our proposed chaotic model can accurately and effectively detect DDoS attack traffic. Our approach has the potential to not only detect attack traffic during transit, but to also filter it.
An Optimistic Differentiated Service Job Scheduling System for Cloud Computing Service Users and Providers
Authors: Luqun Li
Venue: Proceedings of the 2009 Third International Conference on Multimedia and Ubiquitous Engineering (2009)

Job scheduling system problem is a core and challenging issue in Cloud Computing. How to use Cloud computing resources efficiently and gain the maximum profits with job scheduling system is one of the Cloud computing service providers’ ultimate goals. In this paper, firstly, by analysis the differentiated QoS requirements of Cloud computing resources users’ jobs, we build the corresponding non-preemptive priority M/G/1 queuing model for the jobs. Then, considering Cloud computing service providers’ destination which is to gain the maximum profits by offering Cloud computing resources, webuilt the system cost function for this queuing model. After that, based on the queuing model and system cost function, considering the goals of both the Cloud Computing service users and providers, we gave the corresponding strategy and algorithm to get the approximate optimistic value of service for each job in the corresponding no-preemptive priority M/G/1 queuing model. Finally, we also provide corresponding simulations and numeral results. Analysis and number results show that our approach for job scheduling system can not only guarantee the QoS requirements of the users’ jobs, but also can make the maximum profits for the Cloud computing service providers.
A parametric correlation framework for the statistical evaluation and estimation of biometric-based classification performance in a single environment
Authors: Michael E. Schuckers
Venue: IEEE Transactions on Information Forensics and Security (2009)

In this paper, we propose parametric correlation models for the assessment of biometric classification error rates. Correctly specified correlations are integral to variance estimation and the corresponding inferential quantities which depend upon these estimates. We present methodology here for false match and false nonmatch error rates for a single environment. This paper generalizes other work that has previously appeared in the bioauthentication literature. Since symmetric- and asymmetric-matching algorithms are used in practice, we present a general correlation structure for both types of algorithms. Along with the correlation structure, we describe estimators for the parameters in these models. The correlation structure described here for binary decision data is then used to derive explicit confidence intervals and sample-size calculations for the estimation of false match and false nonmatch error rates. We then apply the correlation structure described herein to two match scores databases to illustrate our approach. A discussion of the utility and consequences of this correlation structure are also provided.
A single-PLL UWB frequency synthesizer using multiphase coupled ring oscillator and current-reused multiplier
Authors: Jung-Yu Chang, Che-Wei Fan, Che-Fu Liang, Shen-Iuan Liu
Venue: IEEE Transactions on Circuits and Systems II: Express Briefs (2009)

A single phase-locked loop (PLL) frequency synthesizer for a Mode-1 multiband orthogonal frequency-division multiplexing (MB-OFDM) ultrawideband (UWB) system is realized in 0.13-µm CMOS. A current-reused multiply-by-1.5 circuit and a multiphase coupled ring oscillator are adopted to reduce the power consumption. For a 4.488-GHz signal, the measured image sideband is - 40 dBc. The measured switching time from 3.342 to 4.488 GHz is 1.5 ns. The area is 0.85 × 0.9 mm2 and the power is 31.2 mW for a 1.2-V supply voltage.
On the symbol error rates for signal space diversity schemes over a Rician fading channel
Authors: Jihoon Kim, Wonjun Lee, Jong-Kook Kim, Inkyu Lee
Venue: IEEE Transactions on Communications (2009)

A signal space diversity (SSD) scheme is one of techniques to achieve diversity gain in fading channels. This method consists of two key operations: constellation rotation and component-wise interleaving. Because of these operations, the decision boundaries for the SSD are no longer perpendicular, and thus, different coordination approaches are required for the analysis of error rates compared to conventional rectangular coordinates. In this letter, we derive an exact expression of the symbol error rate for the SSD scheme in Rician fading channels with M-QAM and M-PSK. By defining the ratio of the standard deviation of the inphase and quadrature components, we introduce a new signal model for the SSD. Based on this signal model, we can compute the exact symbol error rate using polar coordinates. The computer simulation results confirm the accuracy of our analysis for fading channels.
A unified approach to computing error probabilities of diversity combining schemes over correlated fading channels
Authors: Pavel Loskot, Norman C. Beaulieu
Venue: IEEE Transactions on Communications (2009)

The average bit-error rate performance of one-stage and two-stage diversity combining schemes operating over correlated fading channels is investigated. Two channel models that can significantly simplify the performance analysis are considered. In particular, a linear correlation channel model having equal branch variances can be decorrelated at the receiver, so that the branches become independent. It is shown that, in general, employing diversity combining schemes for decorrelated or orthogonalized branches can recover some of the diversity gain lost due to the branch correlations. This is observed, for example, for the case of hybrid selection/maximum ratio combining operating over decorrelated and orthogonalized non-zero mean Gaussian fading channels. Furthermore, a fading amplitude channel model is proposed assuming vector norm superposition of the impinging plane waves. This channel model is well-suited for the performance analysis of maximum ratio and equal gain combining schemes operating over correlated fading channels. Finally, the average bit error rates of several diversity combining schemes are evaluated analytically using the Prony approximation method as well as using computer simulation.
Analytical upper bounds for convolutional coded CPM over rings
Authors: Zihuai Lin, Branka Vucetic
Venue: IEEE Communications Letters (2009)

Analytical upper bounds on symbol error probability for ring convolutional coded Continuous Phase Modulation (CPM) with Maximum Likelihood Sequence Detection (MLSD) are presented. The constructed bounds for the investigated systems are shown to be asymptotically tight for increasing channel Signal-to-Noise Ratio (SNR) values. This work provides an analysis tool for the investigated systems. The analysis method is very general. It may be applied to any trellis based coding schemes.
Low-cost 14-bit current-steering DAC with a randomized thermometer-coding method
Authors: Da-Huei Lee, Tai-Haur Kuo, Kow-Liang Wen
Venue: IEEE Transactions on Circuits and Systems II: Express Briefs (2009)

A dynamic element-matching (DEM) method, i.e., randomized thermometer coding (RTC), for low-cost current-steering digital-to-analog converter (DAC) design is proposed. The proposed RTC method exhibits randomized starting-element selection, consecutive-element selection, and low-element switching activity. It can be used to significantly suppress the harmonic distortion caused by a large mismatch of small-area transistors, and, thus, very low cost DACs can be realized. With the proposed RTC, a 14-bit current-steering DAC is implemented in a IP6M 0.18-µm 1.8-V CMOS process. The measured spurious-free dynamic range (SFDR) exceeds 80 dB. The measurement results showed that RTC improves the SFDR by more than 16 dB. The DAC has an active area of less than 0.28 mm2. The proposed DAC achieves a smaller active area than state-of-the-art 12- to 14-bit DACs.
A procedure for modelling the differences between the gravimetric geoid model and GPS/levelling data with an example in the north part of Algeria
Authors: S. A. Benahmed Daho, S. Kahlouche, J. D. Fairhead
Venue: Computers Geosciences (2006)

Local gravimetric geoid models from a combination of a global geopotential model and local gravity data generally contain errors of dm-level on the long wavelengths and sometimes they may be significantly higher in areas lacking accurate gravity information like Algeria where only few gravity data from Bureau Gravimetrique International (BGI) have been included in the development of the recent geopotential models. Consequently, these models do not have the required accuracy to transform the GPS ellipsoidal heights to orthometric heights. One of the main causes for this is the limited precision of the global and detailed DTM models. On the other hand, we can now measure by means of the space techniques, on land through a combination of GPS positioning and precise levelling and at sea through satellite altimetry, the geoid on some points on the earth's surface with very high absolute accuracy. These points can be used to correct the systematic effects, the medium and longer wavelength errors in the gravimetric geoid. The main goal of this study is to propose a procedure, for combination of available gravimetric geoid and external data from GPS and levelling in an optimal way and for estimating the gravimetric geoid accuracy using the collocation approach. So, the question is to find what is the adequate functional representation of the correction that should be applied to the gravimetric geoid? Several functions have been tested and the most suitable will be selected in test area from a statistical testing procedure. For this purpose, the improved Algerian gravimetric geoid computed by the Geodetic Laboratory of the National Center of Space Techniques from the gravity data supplied by the Geophysical Exploration Technology Ltd. (GETECH), and the precise GPS data collected from the international TYRhenian GEOdynamical NETwork (TYRGEONET), ALGerian GEOdynamical NETwork (ALGEONET) projects with baseline length ranging from about 1 to 1000km have been used. The comparisons based on different GPS campaigns provide after fitting a RMS of the differences +/-1.9cm and prove that a good fit in experimental area between the gravimetric geoid and GPS/levelling data using the seven-parameter model transformation has been reached. Moreover, the analysis of statistics shows that the residuals in benchmarks are due principally to gravimetric geoid errors. The main outlines of the Algerian geoid computation, the available GPS/levelling data, the developed procedure and the obtained results will be presented.
Content analysis schemes to analyze transcripts of online asynchronous discussion groups: A review
Authors: B. De Wever, T. Schellens, M. Valcke, H. Van Keer
Venue: Computers Education (2006)

Research in the field of Computer Supported Collaborative Learning (CSCL) is based on a wide variety of methodologies. In this paper, we focus upon content analysis, which is a technique often used to analyze transcripts of asynchronous, computer mediated discussion groups in formal educational settings. Although this research technique is often used, standards are not yet established. The applied instruments reflect a wide variety of approaches and differ in their level of detail and the type of analysis categories used. Further differences are related to a diversity in their theoretical base, the amount of information about validity and reliability, and the choice for the unit of analysis. This article presents an overview of different content analysis instruments, building on a sample of models commonly used in the CSCL-literature. The discussion of 15 instruments results in a number of critical conclusions. There are questions about the coherence between the theoretical base and the operational translation of the theory in the instruments. Instruments are hardly compared or contrasted with one another. As a consequence the empirical base of the validity of the instruments is limited. The analysis is rather critical when it comes to the issue of reliability. The authors put forward the need to improve the theoretical and empirical base of the existing instruments in order to promote the overall quality of CSCL-research.
Symbol error rate of the DM-MPSK under the influence of jamming signals
Authors: Youngpo Lee, Taeung Yoon, Iickho Song, Yun Hee Kim, Tae Hee Han, Seokho Yoon
Venue: IEEE Communications Letters (2009)

Focusing on the performance of the chirp spread spectrum (CSS) communication system under the influence of jamming, we analytically derive the symbol error rate (SER) for the direct modulation CSS system with M-ary phase shift keying in the presence of broadband and tone jamming signals. From numerical results, it is confirmed that the analytic result agrees closely with the empirical SER.
Data quality through model quality: a quality model for measuring and improving the understandability of conceptual models
Authors: Kashif Mehmood, Samira Si-Said Cherfi, Isabelle Comyn-Wattiau
Venue: Proceeding of the first international workshop on Model driven service engineering and data quality and security (2009)

Data quality has emerged as an important and challenging topic in recent years. This article addresses the conceptual model quality as it has been widely accepted that better conceptual models produce better information systems and thus implicitly improve the data quality. Conceptual Models are designed as part of the analysis phase and serve as a communicating mediator between the users and the development team. Consequently, their understandability is a real challenge to avoid the propagation of inaccurate interpretation of the user requirements to the underlying system design and implementation. In this paper, we propose an adaptive quality model. We illustrate its usefulness by describing how it can be used to model and evaluate the understandability of conceptual models. Our quality evaluation is enriched with corrective actions provided to the designer, leading to a guidance modeling process. A first validation based on a survey is proposed.
Cardinality estimation in ETL processes
Authors: Maik Thiele, Tim Kiefer, Wolfgang Lehner
Venue: Proceeding of the ACM twelfth international workshop on Data warehousing and OLAP (2009)

The cardinality estimation in ETL processes is particularly difficult. Aside from the well-known SQL operators, which are also used in ETL processes, there are a variety of operators without exact counterparts in the relational world. In addition to those, we find operators that support very specific data integration aspects. For such operators, there are no well-examined statistic approaches for cardinality estimations. Therefore, we propose a black-box approach and estimate the cardinality using a set of statistic models for each operator. We discuss different model granularities and develop an adaptive cardinality estimation framework for ETL processes. We map the abstract model operators to specific statistic learning approaches (regression, decision trees, support vector machines, etc.) and evaluate our cardinality estimations in an extensive experimental study.
OGC Catalog Services: a key element for the development of Spatial Data Infrastructures
Authors: J. Nogueras-Iso, F. J. Zarazaga-Soria, R. Béjar, P. J. Álvarez, P. R. Muro-Medrano
Venue: Computers Geosciences (2005)

One of the essential components for the construction of a geographic spatial data infrastructure at a regional, national or global level is the geographic information catalog server. But, for the catalog to be a useful component, it must enable access to geographic information metadata independently of the nature of search client applications, in other words, client applications do not need to be developed by the same company or same technology that implemented the server. In this sense, the contribution of the OpenGIS Consortium, an organization which promotes the standardization mechanisms for catalog services, is to provide the tool that makes possible this enterprise and technological independence. The objective of this paper is to review current approaches, provide some inside on the software implementation of catalogs, and show the applicability of these catalogs in real world scenarios.
Measure of similarity between geological sections accounting for subjective criteria
Authors: P. Kaltwasser, F. Boschetti, P. Hornby
Venue: Computers Geosciences (2005)

We propose a set of criteria based upon spatial relations between geological structures, in order to develop a measure of similarity between geological sections. By giving different weights to the criteria, the technique can be tuned to different geological problems. The weights are determined automatically by a user, who ranks sets of test images, without the need to assign numerical ''a priori'' values. This is a step towards the development of a tool for applications such as numerical inversion, geological image retrieval, geological feature extraction, and image data set browsing.
Optimality of beamforming in fading MIMO multiple access channels
Authors: Alkan Soysal, Sennur Ulukus
Venue: IEEE Transactions on Communications (2009)

We consider the sum capacity of a multi-input multi-output (MIMO) multiple access channel (MAC) where the receiver has the perfect channel state information (CSI), while the transmitters have either no or partial CSI. When the transmitters have partial CSI, it is in the form of either the covariance matrix of the channel or the mean matrix of the channel. For the covariance feedback case, we mainly consider physical models that result in single-sided correlation structures. For the mean feedback case, we consider physical models that result in in-phase received signals. Under these assumptions, we analyze the MIMO-MAC from three different viewpoints. First, we consider a finite-sized system. We show that the optimum transmit directions of each user are the eigenvectors of its own channel covariance and mean feedback matrices, in the covariance and mean feedback models, respectively. Also, we find the conditions under which beamforming is optimal for all users. Second, in the covariance feedback case, we prove that the region where beamforming is optimal for all users gets larger with the addition of new users into the system. In the mean feedback case, we show through simulations that this is not necessarily true. Third, we consider the asymptotic case where the number of users is large. We show that in both no and partial CSI cases, beamforming is asymptotically optimal. In particular, in the case of no CSI, we show that a simple form of beamforming, which may be characterized as an arbitrary antenna selection scheme, achieves the sum capacity. In the case of partial CSI, we show that beamforming in the direction of the strongest eigenvector of the channel feedback matrix achieves the sum capacity. Finally, we generalize our covariance feedback results to double-sided correlation structures in the Appendix.
Designing an ultralow-voltage phase-locked loop using a bulk-driven technique
Authors: Yu-Lung Lo, Wei-Bin Yang, Ting-Sheng Chao, Kuo-Hsing Cheng
Venue: IEEE Transactions on Circuits and Systems II: Express Briefs (2009)

This brief describes an ultralow-voltage phase-locked loop (PLL) using a bulk-driven technique. The architecture of the proposed PLL employs the bulk-input technique to produce a voltage-controlled oscillator (VCO) and the forward-body-bias scheme to produce a divider. This approach effectively reduces the threshold voltage of the MOSFETs, enabling the PLL to be operated at an ultralow voltage. The chip is fabricated in a 0.13-µm standard CMOS process with a 0.5-V power supply voltage. The measurement results demonstrate that this PLL can operate from 360 to 610 MHz with a 0.5-V power supply voltage. At 550 MHz, the measured root-mean-square jitter and peak-to-peak jitter are 8.01 and 56.36 ps, respectively. The total power consumption of the PLL is 1.25mW, and the active die area of the PLL is 0.04 mm2.
Video Processing Real-Time Algorithm Design Verification on Embedded System for HDTV
Authors: Vladimir Zlokolica, Radmila Uzelac, Goran Miljkovic, Tomislav Maruna, Miodrag Temerinac, Nikola Teslic
Venue: Proceedings of the 2009 First IEEE Eastern European Conference on the Engineering of Computer Based Systems (2009)

Embedded systems are considered as favorable frame-work for real-time Consumer Electronics (CE) applications because of well balanced compromise between hardware resources and feature performance. In video processing applications, such as HDTV, the most critical part of data processing chain is real-time processing. In this paper, we address the real-time algorithm design verification for video processing in TV systems in Linux OS running on MIPS processors. Verification of such system is done using demanding applications currently present in the HDTV.