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Asia-Pacific Conference on Applied Electromagnetics, APACE

作者： B. Sujak D.K. Ghodgaonkar B.M. Ali S. Khatun Acces Infrastructure System Telekom Malaysia Berhad Brickfields K.L. Malaysia Department of Computer and Communication UPM Serdang Selangor Malaysia Faculty of Electrical Engineering UiTM Microwave Technology Center Shah Alam Selangor Malaysia Department of Computer and Communication UPM Serdang Selangor

For planning of indoor wireless LAN systems working in the 2.4 GHz ISM band, the signal propagation prediction is needed. Empirical and semi-empirical models represent an efficient approach as opposed to deterministic models due to its simplicity and superiority in calculation time. For these models, suitable empirical parameters to characterize propagation channel must be provided. In this paper, an in building linear, one-slope (OS) empirical and semi-empirical multi-wall (MW) models are studied. Different types of MW models in the office and classroom like environment have been reported. OS purely account for attenuation of power law equation with distance while MW with additional attenuation due to obstacles such as wall, partition etc. The results and accuracy of those models are compared and discussed. The developed optimal indoor OS, MWC and MWE is then tuned to slope and MW model available in wireless simulation tool namely ICS Telecom

关键词： Wireless LAN Attenuation Floors Technology planning Equations Telecommunications Costs Spine computer networks Performance evaluation

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Prioritized scheduling for bufferless slotted WDM optical packet switch via wavelength conversion

Prioritized scheduling for bufferless slotted WDM optical pa...

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International Conference on Advanced communication Technology (ICACT)

作者： G.Y. Il M.K. Abdullah S. Khatun B.M. Ali Photonics and Fiber Optics system Laboratory Universiti Putra Malaysia Serdang Selangor Malaysia Photonics and Fiber Optics system Laboratory Universiti Putra Malaysia Serdang Selangor Darul Ehsan Malaysia Department of Computer and Communication System Engineering Universiti Putra Malaysia Serdang Selangor Darul Ehsan Malaysia

This paper proposes a prioritized scheduling in associated with contention resolution schemes for bufferless, single stage, non-blocking fully connected optical packet switch in synchronous optical packet switching network. We introduce a technique that integrates prioritized scheduling with wavelength conversion that can be realized by tunable optical wavelength converter (TOWC). It comprises a set of preemptive selective policies for contention resolution. This proposed scheme ensures packet loss probability below 10- 10 that supports traffic load up to 50%, without suffering from conventional buffering delay. It guarantees real-time delivery for high priority packet with elimination of unnecessary wavelength conversion

关键词： Optical buffering Wavelength division multiplexing Optical packet switching Optical wavelength conversion Optical switches High speed optical techniques Optical sensors Optical losses communication switching Optical fiber communication

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Gain-control Raman fiber amplifier incorporating ring cavity

Gain-control Raman fiber amplifier incorporating ring cavity

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IEEE International Conference on Networks

作者： A. Ahmad M.I.M. Ali A.K. Zamzuri M.A. Mahdi TM Research & Development Sdn. Bhd. UPM-MTDC Serdang Selangor Darul Ehsan Malaysia The Photonics and Fiber Optic System Department of Computer and Communication Systems Engineering Universiti Putra Malaysia Serdang Selangor Darul Ehsan Malaysia

All-optical gain-control Raman fiber amplifier (RFA) based on ring cavity technique using a pair of circulators is investigated experimentally. A pair of 1465 nm laser diodes are used as the pump source to the RFA which provides a gain peak at around 1565 nm. The analyses of gain and noise figure are carried out using lasing wavelengths of 1550 and 1565 nm. Gain and noise figure variations are 0.4 and 0.5 dB respectively. We observed strong influence of pump-signal relative intensity noise transfer that results in noise figure penalty.

关键词： Stimulated emission Optical attenuators Circulators Optical filters Optical fiber networks Wavelength division multiplexing Optical fiber amplifiers Noise figure Optical feedback Optical pumping

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Performance analysis on the controllable Slotted DS-CDMA with an allocating buffer for collided traffic

Performance analysis on the controllable Slotted DS-CDMA wit...

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作者： Asavaruk, Seri Sittichivapak, Suvepon Varakulsiripunth, Ruttikorn Kato, Yasushi Shiratori, Norio Faculty of Engineering Research Center for Communications and Information Technology King Mongkut's Institute of Technology Ladkrabang Bangkok 10520 Thailand Faculty of Engineering King Mongkut's Institute of Technology Ladkrabang Bangkok 10520 Thailand Sendai National College of Technology Sendai-shi 989-3128 Japan Research Institute of Electrical Communication Tohoku University Sendai-shi 980-8577 Japan Information System and Quality Assurance Division Computer Research and Service Center KMITI Thailand Department of Electronics Faculty of Engineering King Mongkut's Institute of Technology Ladkrabang Bangkok Thailand Department of Information Engineering Sendai National College of Technology Japan Miyagi Fukushima and Iwate Prefectural Institute of Technologies Japan

This paper presents an analysis of the Slotted DS-CDMA system with modified node components in order to construct a load control structure in which the service rates of each node can be dynamically adapted without using feedback information. In contrast to the traditional Slotted DS-CDMA which is widely represented with single queue, prior emphasis of the approach is laid on the usage of an additional queue which is applied to manage the collided packet traffic while its queue size is also used as a load control parameter. Semi-Markov process is applied to describe the statistic behavior of the system in steady state. Trade-offs between two major performance parameters, i.e., delay and throughput, are presented and compared with those of the traditional system. Results obtained from the simulation and numerical analysis using queuing concept are compared. With these results, an advantage performance for group packets is shown, and we finally extend the concept based on the obtained results to describe a simple algorithm using one way control message as the tool to alleviate the stability problem. Copyright © 2005 The Institute of Electronics, Information and communication Engineers.

关键词： Code division multiple access

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HGBS: a hardware-oriented grid BLAST system 05

HGBS: a hardware-oriented grid BLAST system

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IEEE/ACM International Symposium on Cluster Computing and the Grid (CCGRID)

作者： Tae-Kyung Kim Sang-Keun Oh Kyung-Hee Lee Dong-Hyun Roh Wan-Sup Cho Department of Industrial Information Engineering Chungbuk National University Cheongju South Korea Hansol Network Consulting Cooperation Cheongju South Korea School of Computer Information & Communication Engineering Seowon University Cheongju South Korea Division of Life Sciences Chungbuk National University Cheongju South Korea Department of Management Information System Chungbuk National University Cheongju South Korea

ISBN: (纸本)9780780390744

BLAST is one of the most widely used tools in bio informatics to find biologically similar sequences from the genome databases for a given query sequence. Although elaborate dynamic programming and heuristic search in the BLAST rapidly identify significant similar sequences, performance is still an important issue as the size of genome databases and sequences to be compared increases. We propose HGBS (hardware-oriented grid BLAST system) that significantly improves the BLAST performance by applying the grid computing technique. HGBS utilizes a PC-based grid environment constructed by a specialized hardware chip, not a grid middleware such as the Globus toolkit, to provide enhanced performance, good extensibility, and lower implementation cost. Performance analysis shows that there is a significant performance advantage in HGBS; for huge number of BLAST operations in 89-prokaryote genomes comparison, HGBS connecting 27 PCs needs just a week to complete the comparisons, but a single server system takes about 33 weeks.

关键词： Genomics Bioinformatics Databases Informatics Dynamic programming Grid computing Hardware Middleware Costs Performance analysis

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Innovation or imitation?: Benchmarking: A knowledge-management process to innovate services

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Benchmarking 2004年第6期11卷 610-620页

作者： Massa, Silvia Testa, Stefania DIST Department of Communication Computer and System Science University of Genoa Genoa Italy DIP Department of Industrial Engineering University of Genoa Genoa Italy

Traditionally, benchmarking has been described as a practice that promotes imitation. However, according to a more recent approach, this paper suggests that benchmarking, looking outside the firm boundaries and enabling comparison with others, in terms of both practices and performances, enable the process of acquiring external explicit and tacit knowledge. Such newly acquired knowledge, once integrated with previous internal knowledge of the firm, creates new knowledge that may give rise to improvements and innovations. In order to study the innovative power of benchmarking, this paper presents a three-year research undertaken in the maintenance-services sector that is becoming more and more global and competitive. A model that integrates benchmarking, knowledge management and innovation is presented as the main result of the research. © Emerald Group Publishing Limited.

关键词： Benchmarking Innovation Knowledge management

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Fiber optical web for object localization by geometric space coding

Fiber optical web for object localization by geometric space...

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Frontiers in Optics, FiO-2004

作者： Zheng, Yunhui Brady, David J. Guenther, B.D. Pitsianis, Nikos P. Fitzpatrick Center for Photonics and Communication System Department of Electrical and Computer Engineering Duke University DurhamNC27707 United States

ISBN: (纸本)1557527792

A fiber web was used for object(s) localization. The fiber web used binary codes to segment and encode the object space. We employed 2D gray code to localize an extended object and superimposed code to localize multiple objects simultaneously. Experimental human localization systems with both coding scheme were demonstrated. © 2004 OSA/FIO 2004

关键词： Object recognition

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A study of antenna array based multipath propagation phenomenon in LAS-CDMA standard

A study of antenna array based multipath propagation phenome...

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2004 RF and Microwave Conference, RFM 2004

作者： Ng, Chee Kyun Khatun, Sabira Ali, Borhanuddin Mohd Jamuar, Sudhanshu Shekhar Ismail, Mahamod Department of Computer and Communication Systems Engineering Faculty of Engineering Universiti Putra Malaysia Malaysia Department of Electrical and Electronic Engineering Faculty of Engineering Universiti Putra Malaysia Malaysia Department of Electrical Electronic and System Engineering Faculty of Engineering Universiti Kebangsaan Malaysia Malaysia

ISBN: (纸本)078038671X

Throughout the history of wireless communications, spatially diversity's antenna array system has being important in improving the radio link between wireless users. Moreover, this system are proposed to reduce the multipath fading through its directivity narrowly radiation beam. The introduction of interference free window in delay domain from newly LAS-CDMA standard has received many attentions for furthering research on multipath delay spread. In this paper, we studied the effect of angular spread on maximum excess delay in multipath propagation environments. Then, we examined the application of antenna array in LAS-CDMA standard to overcome this multipath phenomenon. First of all, the multipath propagation literatures are reviewed, followed by the explanation of maximum angular spread in a simple discrete ring of scatterers model. Comparison analyses are made between conventional omnidirectional antenna and narrow beam antenna array. Finally, the analytical performances in term of power delay profile are presented. © 2004 IEEE.

关键词： Code division multiple access

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Smart antenna system with orthogonal codes

Smart antenna system with orthogonal codes

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Proceedings of the IEEE 6th Circuits and systems Symposium on Emerging Technologies: Frontiers of Mobile and Wireless communication

作者： Ng, Chee Kyun Mohd Ali, Borhanuddin Jamuar, Sudhanshu Shekhar Ismail, Mahamod Department of Computer and Communication Systems Engineering Faculty of Engineering Universiti Putra Malaysia Malaysia Department of Electrical and Electronic Engineering Faculty of Engineering Universiti Putra Malaysia Malaysia Department of Electrical Electronic and System Engineering Faculty of Engineering Universiti Kebangsaan Malaysia Malaysia

ISBN: (纸本)0780379381

Smart antenna, which improves the performance of wireless systems, suppress all interfering signals, and increase the system capacity. The objective of this paper is to provide an analysis of system capacity when using smart antenna with the orthogonal code. A new technique which use orthogonal codes in multiple beams to distinguish multi-user is introduced. The properties of LinkAir communications' large area synchronous (LAS) or smart codes, which are claimed to be fully orthogonal code and are used to combat major interferences, are studied. The effect of spatial multiple beams in an area where density of users is very condense in a cell is also examined. Finally, the system performance in term of system capacity is presented.

关键词： Mobile telecommunication systems

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Photorefractive bi-directional connection module with mutual-pumped phase conjugate mirror

Photorefractive bi-directional connection module with mutual...

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Photonics Asia 2004:Information Processing and Data Storage

作者： Kazumasa Kori Atsushi Okamoto Yoshihisa Takayama Masatoshi Bunsen Hisatoshi Funakoshi Terumasa Ito Research Group of Computer and Communication System Graduate School of Engineering Hokkaido University Research Group of Computer and Communication System Graduate School of Engineering Hokkaido University Wireless Communications Department National Institute of Information and Communications Technology Research Group of Computer and Communication System Graduate School of Engineering Hokkaido University Research Group of Computer and Communication System Graduate School of Engineering Hokkaido University Research Group of Computer and Communication System Graduate School of Engineering Hokkaido University

The purpose of this study is to apply a free-space optical interconnection to a reconfigurable board-to-board connection where the wiring patterns connecting boards are optically formed without electr

关键词： Photorefractive effect, Free-space optical interconnection, Mutually pumped phase conjugate mirror

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