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IEEE GLOBECOM 2008 - 2008 IEEE Global Telecommunications Conference

作者： In Sook Park Joohwan Chun Division of Electrical Engineering Department of Electrical Engineering and Computer Science KAIST Daejeon South Korea

The sphere decoding (SD) is a category of algorithms finding the closest lattice point and known to have the expected complexity approximately cubic in the dimension of the lattice point to be searched for a medium-to-high range of signal-to-noise ratios (SNRs). But the expected complexity depends highly on SNR and the portion of high-ordered terms (higher ordered terms than cubic) of it increases rapidly as SNR decreases for low SNRs. The number of points visited by SD is influenced by the processing done before starting to search a closest point. In this paper the minimum mean square error (MMSE) sorted QR-decomposition (SQRD) is proposed as a preprocessing for SD algorithm. By mathematical investigation of MMSE extended matrix we find out that MMSE extension can be generalized and suggest variations of MMSE-SQRD as candidates of the preprocessing for SD. MMSE-SQRD and its variations reduce considerably the dependency of the complexity of SD on SNR.

关键词： Lattices Maximum likelihood decoding Maximum likelihood detection Mean square error methods Polynomials Silicon carbide Symmetric matrices Propagation losses Vectors detection algorithms

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A Novel Approach for K-Best MIMO detection and its VLSI Implementation

A Novel Approach for K-Best MIMO Detection and its VLSI Impl...

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2008 IEEE International Symposium on Circuits and Systems (ISCAS 2008), vol.3

作者： Sudip Mondal Khaled N Salama Warsame H. Ali Electrical Computer and Systems Engineering Department Rensselaer Polytechnic Institute Troy NY USA Electrical and Computer Engineering Department Prairie View A and M University TX USA

Since the complexity of MIMO detection algorithms is exponential, the K-best algorithm is often chosen for efficient VLSI implementation. This detection problem is often viewed as a tree search problem where the Breadth First Search (BFS) method is adopted and only the K-best branches are kept at each level of the tree. An earlier VLSI implementation of the K-best BFS has been reported, however it has an inherent speed bottleneck due to the calculation of many path metrics and then sorting among them to select the K-best. In this paper an alternative implementation of the BFS is presented, which is suitable for VLSI implementation. To test the performance of this approach it has been applied to a 4X4 MIMO detector with a 64 QAM constellation. The results show less than 1dB degradation from the sphere decoding algorithm. The implementation of a single spiral cell, the basic block behind the system, occupies a 764(mu)m~(2) of area and consumes a 52.58(mu)w of power a 0.13(mu)m CMOS technology.

关键词： MIMO Very large scale integration CMOS technology detection algorithms Search problems Sorting Testing Detectors Quadrature amplitude modulation Degradation

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New feedback detection method for performance evaluation of hearing aids

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JOURNAL OF SOUND AND VIBRATION 2007年第1-2期302卷 350-360页

作者： Shin, Mincheol Wang, Semyung Bentler, Ruth A. He, Shuman Gwangju Inst Sci & Technol Dept Mechatron Kwangju 500712 South Korea Univ Iowa Dept Speech Pathol & Audiol Iowa City IA 52242 USA

New objective and accurate feedback detection method, transfer function variation criterion (TVC), has been developed for evaluating the performance of feedback cancellation techniques. The proposed method is able to classify stable, unstable, and sub-oscillatory stages of feedback in hearing aids. The sub-oscillatory stage is defined as a state where the hearing aid user may perceive distortion of sound quality without the occurrence of oscillation. This detection algorithm focuses on the transfer function variation of hearing aids and the relationship between system stability and feedback oscillation. The transfer functions are obtained using the FIR Wiener filtering algorithm off-line. An anechoic test box is used for the exact and reliable evaluation of different hearing aids. The results are listed and compared with the conventional power concentration ratio (PCR), which has been generally adopted as a feedback detection method for the performance evaluation of hearing aids. The possibility of real-time implementation is discussed in terms of a more convenient and exact performance evaluation of feedback cancellation techniques. (c) 2007 Elsevier Ltd. All rights reserved.

关键词： algorithms Performance Evaluation Feedback algorithms inspection methods detection algorithms TRANSFER FUNCTIONS Hearing Aids test chambers System stability Exact

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Out-of-step detection algorithm using frequency deviation of voltage

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IET GENERATION TRANSMISSION & DISTRIBUTION 2007年第1期1卷 119-126页

作者： So, K. H. Heo, J. Y. Kim, C. H. Aggarwal, R. K. Song, K. B. Sungkyunkwan Univ Dept Chem Dept Elect & Elect Engn Suwon 440746 South Korea Univ Bath Dept Elect & Elect Engn Bath BA2 7AY Avon England Soongil Univ Dept Elect & Elect Engn Seoul 156756 South Korea

Protection against transient instability and a consequent out-of-step condition is a major concern for the utility industry. An unstable system may cause serious damage to system elements such as generators and transmission lines, therefore out-of-step detection is essential to operate a system safely. The traditional out-of-step relays detect out-of-step conditions by using distance relays and timers. However, such a relay monitors only apparent impedance which is an indirect function of generator angle, and the relay cannot cope with the out-of-step situation for the more severe instability situation of very fast power swings which can also cause damage to transmission lines if not detected fast enough, as is the case with conventional detection techniques. Digital filters based on discrete Fourier transforms are used to calculate the frequency of a sinusoidal voltage, and then the generator angle is estimated using the deviation of the calculated frequency component of the voltage. The proposed out-of-step detection algorithm is based on the assessment of transient stability using the equal-area criterion. It is verified and tested by using ATP/EMTP MODELS, and the simulation results show that the out-of-step conditions are detected accurately employing the proposed algorithm.

关键词： Simulation results conditional synchronization relay out of step transient stability Fasting Transmission Lines detection algorithms inspection technique Frequency deviation sinusoidal voltage

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Radiometric correction for linear change-detection techniques: analysis in bi-temporal space

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INTERNATIONAL JOURNAL OF REMOTE SENSING 2007年第22期28卷 5143-5157页

作者： Liu, Y. Yano, T. Nishiyama, S. Kimura, R. Nagoya Univ Grad Sch Environm Studies Chikusa Ku Nagoya Aichi 4648601 Japan Chinese Acad Sci Nanjing Inst Geog & Limnol Nanjing 210008 Peoples R China Tottori Univ Arid Land Res Ctr Tottori 6800001 Japan Yamaguchi Univ Fac Agr Yamaguchi 7538515 Japan

Radiometric corrections can remove or reduce inconsistencies induced by temporal factors in multi-temporal images, but their effectiveness for change detection is still unclear. This study applied a physics-based model to pseudo-invariant features (PIFs) and showed that absolute correction is in principle equivalent to relative correction in change-detection studies if the spatial heterogeneity of the atmosphere is not rigorously considered. Bi-temporal space analysis revealed that the performance of a linear change-detection algorithm depends on whether the determined slope of the no-change zone coincides with that of the PIF line, offering insight into the effectiveness of radiometric correction. A case examination showed that either absolute or relative correction adjusted the paired image bands to a common standard. However, the corrections did not necessarily reduce the bias in the zone slope determined by the change-detection algorithm, illustrating the futility of performing either absolute or relative corrections for linear change-detection techniques, except for image differencing.

关键词： Spatial heterogeneity ABSOLUTE detection algorithms medical futility RADIOMETRIC CORRECTION

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Morphological detection algorithms for the automatic implantable cardioverter/defibrillator (AICD)

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BIOMEDIZINISCHE TECHNIK 2004年第11期49卷 306-310页

作者： Kaup, HJ Hexamer, M Werner, J Ruhr Univ Bochum Inst Biomed Tech Dept Biomed Engn Fac Med D-44780 Bochum Germany Ruhr Univ Bochum Univ Ctr Med Engn D-44780 Bochum Germany

To prevent sudden cardiac death of patients who are at risk from long standing tachyarrhythmia the implantable cardioverter defibrillator (ICD) is the first choice therapy. ICDs use a range of electrostimuli up to defibrillation, which is a non synchronous high energy shock, whereas cardioversion is synchronous with the ECG. In order to know when and how to react, a detection algorithm, which analyses an intracardial electrocardiogram (ECG) and classifies the heart rhythm, is implemented in every ICD. All detection algorithms use the heart rate to classify the different heart rhythms roughly. If a tachycardia is detected, it is important to discriminate between a ventricular tachycardia, which is life threatening and a supraventricular tachycardia, which is much less threatening. To be able to make this distinction the detection algorithms analyse the behaviour of the heart cycle intervals, the ECG-morphology or in addition to the ventricular ECG, an atrial ECG. In this paper morphological algorithms will be evaluated and newly developed algorithms will be presented. Recent algorithms use the mathematical wavelet theory. The evaluation shows that these get better results than all but one of the simpler classical morphological algorithms. A new wavelet based algorithm, developed by the authors, exhibits the best detection results.

关键词： ACID detection algorithms morphological algorithms wavelets

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Direct radar positioning using strongly coupled ultra-wideband arrays

Direct radar positioning using strongly coupled ultra-wideba...

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2008 IEEE Antennas and Propagation Society International Symposium (APSURSI 2008), vol.8

作者： Christophe Craeye Anatoliy Boryssenko Laboratory TELE Université catholique de Louvain Louvain-la-Neuve Belgium Antenna Laboratory University of Massachusetts Amherst USA

ISBN: (纸本)9781424420414

Microwave circuits [1] under development for short-range impulse radio open the way for cheap radar devices, that can be used for civilian security systems. Such systems involve many different aspects that need to be mastered jointly: pulse generator, high-speed receiving system, antenna arrays and detection algorithms. While transmit and receive systems are being improved, antennas and algorithms can be evalulated independently with the help of network analyser experiments. In previous communications [2]-[5], we showed results obtained for positioning of wideband transmitters, as well as radar positioning obtained with one transmitting and two receiving antennas. The present paper is devoted to a system involving a larger array, with five antennas;a method is proposed to exploit the redundancy in the array, in order to mitigate the effects of mutual coupling. The latter can be expressed in terms of variability of the (amplitude and phase) embedded element patterns within the array. The new positioning algorithm consists of adding up ambiguity functions obtained with different triplets of elements (one transmitting and two receiving elements). It is shown that this procedure tends to reduce the variablity in the estimated target position. In Section 1, the experimental setup is shown. In Section 2, the "direct positioning" approach for a 3-antenna system is recalled and in Section 3, we show how the method is extended to larger arrays and how it may help to mitigate the effects of array truncation. Experimental results are shown in Sectin 4 and conclusions are drawn in Section 5.

关键词： Patient Positioning TRANSMITTING ambiguity function arrays Microwave circuits Accidents,emergencies and safety radar detection algorithms pulse generator Ultra wideband technologies redundancy

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Neighbor Discovery in Wireless Ad Hoc Networks Based on Group Testing

Neighbor Discovery in Wireless Ad Hoc Networks Based on Grou...

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Annual Allerton Conference on Communication, Control, and Computing

作者： Jun Luo Dongning Guo Department of Electrical Engineering & Computer Science Northwestern University

ISBN: (纸本)9781424429257

Fast and efficient discovery of all neighboring nodes by a node new to a neighborhood is critical to the deployment of wireless ad hoc networks. Different than the conventional ALOHA-type random access discovery schemes, this paper assumes that all nodes in the neighborhood simultaneously send their unique on-off signatures known to the receive node. In particular, a transmitter does not transmit any energy during an "off" mini-slot in its signature sequence. The received signal can be viewed as the outcome of a sequence of tests over the mini-slots, where the outcome of a test is positive if there is energy at the corresponding mini-slot from at least one neighbor, and negative if none of the neighboring nodes transmits energy during the mini-slot. The neighbor discovery problem is thus equivalent to a classical group testing problem. Two practical and scalable detection algorithms are developed from the group testing viewpoint. Unlike some previous neighbor discovery schemes using coherent multiuser detection, which are difficult to implement due to lack of training, the proposed scheme requires only non-coherent energy detection. The proposed algorithms are shown to achieve faster and more reliable discovery than existing random access schemes.

关键词： Group Testing Neighbor Mobile ad hoc networks wireless Energy sources received signal Ganglia detection algorithms signatures Multiuser detection Fasting RANDOM ACCESS Neighborhood

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Overcoming SNR walls through macroscale features

Overcoming SNR walls through macroscale features

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Annual Allerton Conference on Communication, Control, and Computing

作者： Rahul Tandra Anant Sahai Department of Electrical Engineering and Computer Sciences University of California

ISBN: (纸本)9781424429257

We consider the problem of robustly detecting the presence/absence of signals in low signal to noise ratio (SNR) environments. Our previous results have shown the existence of thresholds called SNR walls, below which robust detection becomes impossible due to uncertainties in the environment. These thresholds were shown to exist for many signals used in practice. This paper introduces the idea of macroscale features and shows that they can be used to construct signals that evade SNR walls. In particular, we examine a Gaussian mixture example and a noise-calibration based detection algorithm to show that this signal can be robustly detected in the presence of arbitrarily-varying noise and arbitrarily-varying finite-tap fading processes. Finally, we argue that there is tension between the primary user's capacity and the sensing delay experienced by the secondary users. We call this the capacity-delay tradeoff. We derive the capacity-delay tradeoff for the Gaussian example.

关键词： signal to noise ratios Supernova remnants low SNR macroscale wall signals detection algorithms tradeoffs

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Finding event-relevant content from the web using a near-duplicate detection approach 07

Finding event-relevant content from the web using a near-dup...

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IEEE/WIC/ACM International Conference on Web Intelligence

作者： Chang, Hung-Chi Wang, Jenq-Haur Chiu, Chih-Yi Institute of Information Science Academia Sinica Taiwan Department of Computer Science and Information Engineering National Taipei University of Technology Taiwan

ISBN: (纸本)9780769530260

In online resources, such as news and weblogs, authors often extract articles, embed content, and comment on existing articles related to a popular event. Therefore, it is useful if authors can check whether two or more articles share common parts for further analysis, such as co-citation analysis and search result improvement. If articles do have parts in common, we say the content of such articles is event-relevant. Conventional text classification methods classify a complete document into categories, but they cannot represent the semantics precisely or extract meaningful event-relevant content. To resolve these problems, we propose a near-duplicate defection approach for finding event-relevant content in Web documents. The efficiency of the approach and the proposed duplicate set generation algorithms make it suitable for identifying event-relevant content. The experiment results demonstrate the potential of the proposed approach for use in weblogs.

关键词： Blogs Event detection Information science Computer science Data mining Text categorization Citation analysis detection algorithms Clustering algorithms Motion pictures

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