WSEAS CONFERENCES. WSEAS, Unifying the Science

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8, 2009
Print ISSN: 1109-2742
E-ISSN: 2224-2864








Issue 1, Volume 8, January 2009

Title of the Paper: Effect of Strong Linear Polarization Anisotropy on Geometrical Modes Characteristics of Optical Fiber


Authors: Mohammed Yousef Al-Gawagzeh, Mohammed Rasoul Al-Hadidi

Abstract: The geometric polarization in single mode optical fibers is investigated theoretically and experimentally and the measurement results are reported. This paper consider the geometrical measurement method of weights the own modes of poorly directing optical fiber with strong linear anisotropy. This given method is based on definition the geometrical parameters lines with equal intensity in a vicinity of zero radiation image from fiber output. The modes weights have been received as a result of computer processing of experimental images of intensity distribution at displacement of laser spot concerning the center of fiber input. It is found that neglecting the geometrical birefringence, even under the weakly guiding approximation, can lead to significant errors in the calculation of PMD and the zero PMD wavelengths. It is also found that one can obtain zero PMD in the single-mode region even by applying a suitable differential stress along the major axis. This is very attractive since then the geometrical and stress birefringence adds up to give increased total birefringence.

Keywords: Anisotropy, double-refraction, polarization, mode weigh, displacement, intensity distribution

Title of the Paper: Polarized Modes Dispersion in Anisotropic Optical Fiber Communication Lines


Authors: Mohammed Yousef Al-Gawagzeh, Mohammed Rasoul Al-Hadidi, Rami Al-Rzooq

Abstract: Equations are derived for calculation of the propagation constants and of the dispersion of the fundamental modes in anisotropic waveguides .This work shows how to obtain approximate analytic expressions which can be used to calculate with sufficient accuracy for practical applications the waveguide and polarization dispersion of the dominant orthogonally polarized modes in anisotropic optical fiber waveguides and distributions of electric and magnetic fields of these modes are obtained in a transverse cross section of the waveguide. It is shown that the anisotropy of a dielectric in the transverse cross section and the elliptical of the shape of this cross section alter the waveguide dispersion of modes in such waveguides compared with an isotropic waveguide. In the case of waveguides which conserve the state of polarization of the transmitted signal the changes in the waveguide dispersion due to the transverse anisotropy of the refractive index are considerably greater than the changes due to the elliptical of the shape of the transverse cross section of the waveguide. In a waveguide with a transverse anisotropy of the refractive index the maximum waveguide dispersion of two mutually orthogonal modes occurs at different frequencies.

Keywords: Dispession, Anisotropy, isotropic dielectric, polarization, Transverse cross section, Perturbation

Title of the Paper: Dialectial System Approach and Education Supporting Environmental Protection


Authors: Davorin Kralj

Abstract: Most of the environmental challenges we face could be resolved if each individual and organization slightly changed their habits and practices. The key to achieving this is education. The global economic system needs to show a more human and environment friendly face. Companies must ensure that their traditional focus on corporate profits and shareholder value is accompanied by equal concern for the needs of society and the environment. The article focuses on system approach and education as an influence on environmental care and protection. Integrated system approach and education management integrate the requirements of sustainable development and environmental care. Environmental protection and sustainable development are result of education and dialectical system approach.

Keywords: Environmental care, environmental education, system approach, sustainable development

Title of the Paper: The Performances of the SSC Combiner Output Signal in the Presence of Log-Normal Fading


Authors: Dragana Krstic, Petar Nikolic, Marija Matovic, Ana Matovic, Mihajlo Stefanovic

Abstract: Level crossing rate, outage probability and average time of fade duration of the SSC combiner output signal are determined in this paper. Log-normal fading at the input is present. The results are shown graphically for different variance values, decision threshold values and fading parameters values.

Keywords: Diversity reception, Fade Duration, Level Crossing Rate, Log-normal fading, Outage Probability, SSC Combining

Title of the Paper: Matching of Interfirm Network and Organizational Learning: Implications for Technological Innovation


Authors: Xinmin Peng

Abstract: There has been a burgeoning literature about interfirm network and innovative performance. However, in reviewing the extant literature we find different interpretations regarding how firms should be tied to one another in networks. The paper employs case study to explore and explain the relative propositions of interfirm network, different organizational learning and technological innovation. It addresses two critical research questions. First, strong ties or cohesive network are valuable in environments that require exploitation, while weak ties or sparse network would be more appropriate for exploration. Second, the benefits of each type of interfirm network vary across each other such that certain types of interfirm network will matter more or less under different conditions and objectives. Therefore, exploration and exploitation are two essential organizational learning models, under which firms need make a reasonable choice between them according the development stage, environment requirements and innovative targets.

Keywords: Interfirm network, Organizational learning, Exploration, Exploitation, Network Density, Tie strength, Technological innovation

Title of the Paper: Study on Significant Technology of H.264 in Mobile Network


Authors: Yun-Peng Liu, San-Yuan Zhang, Shu-Chang Xu, Yin Zhang

Abstract: The characteristics of the mobile wireless network are limited bandwidth and high error rate, at same time the computing and storage capacity of the mobile devices are limited too. In order to ensure effective video compression and transmission, H.264/AVC standard provides the significant technologies and strategies in error resilience strategies?rate control?mode decision and scalable extension. On the basis of the detailed study in the strategies, a combination method is proposed, and experiment proves the quality of video transmission is improved at the same time the rate is reduced.

Keywords: Video transmission, H.264, Mobile network, Wireless transmission, Rate control, Error resilience, Mode decision, Scalable extension

Title of the Paper: An Algorithm Reliability of Wireless Networks for Sum of Disjoint Poroduct and Topological Structure


Authors: Fei Gao, Chen Zhao, HaoLiang Hu, JiangGang Yang

Abstract: A new formula for computing ST reliability of wireless networks from Source to Terminal t was presented. The formula is a combination of IE and SDP, and the Satyaranayanna’s formula is its special case. The new formula contains terms which correspond one by one to a class Special subnetworks , For a given networks, the terms of the new formula are fewer than those corresponding Satyaranayanna’s formula. An algorithm for computing ST reliability was presented, it computed ST reliability or produced a ST reliability expression by enumerating a class of Special networks of given networks. Because the structure of this class of new networks which need to be enumerated was relativity small, the new algorithm’s performance was better than Satyaranayanna’s algorithm .Finally an example illustrates our conclusion.

Keywords: Reliability, Reliability expression, inclusion exclusion principle, wireless network

Title of the Paper: Research of Utility Prepayment System based on Wireless Communication


Authors: Pan Tie-Jun, Zheng Lei-Na, Zhang Hua-Jun, Fang Chen-Bin

Abstract: This paper seeks to clarify differences and similarities among impressive array of radio access technologies which can be used in utility prepayment, analyzes the requirements of wireless prepayment utility meter system. It present a set of mobile prepayment solution in which the prepayment meter (PM) system is implemented without smart card and user need not go to agency by oneself for prepayment. For the purpose of solving the difficult problem of utility meter prepayment at the specific location in person, mobile payment client (MPC) with graph user interface (GUI) located on mobile device which is responded for business initiation. PM is connected to PS via Zigbee network or WLAN in short range access network and via the 3rd generation wireless communication infrastructure (3G) in long range access network, and utility meter may connect Zigbee node via RS485 bus. By means of identification and mutual authentication which generating different session key with time stamps every time, the cross validation mechanism among PM, MPC and PS improve the security of mobile prepayment system. The security mechanism is given in the end including user identification, mutual authentication, and data integrity and data confidentiality. In the end, ZigBee node hardware design and meter interface design is introduced and a practical application is given. The result of the present work implied that mobile phone is gradually becoming a data access and exchange platform of mobile payment, and WiMax is another competitive technology which will be used in the utility wireless prepayment solution.

Keywords: Mobile payment, OTA, Zigbee, WiMax, 3G, meter, RS485

Title of the Paper: Combining Web Services Toward Innovative Design of Agile Virtual Enterprise Supported by Web 3.0


Authors: Pan Tie-Jun, Zheng Lei-Na, Zhang Hua-Jun, Fang Chen-Bin, Lou Jie, Shao Zhong

Abstract: With the Internet dominating the business world, the need to have an effective web3.0 service has increased among Agile Virtual Enterprise(AVE)emerging out of the context of globalization manufacturing, Innovative design is seen as the core competitiveness of AVE which need the knowledge engineering method urgently. However, the current human readable web can not meet the demands of complexity, flexibility and Real-time for innovation design. Until the emergence of the web 3.0, it is possible for intelligent software agent based on machine accessible SOA services which can be combined to higher level of enterprise web services. We give a new innovative design platform by combining enterprising Web Services based on Web 3.0. This paper gives ontology for innovative design which including design, process, skill, application domain and organization sub ontology and the OWL description of environmental production domain. Then we complete the innovative design service model by Protege tools, setup the design service web platform based on J2EE with Protege-OWL API, and give a practical case in the domain of environmental protection device manufacturing. In the end, we points the performance of knowledge database is important in the future.

Keywords: Knowledge, innovative design, Agile Virtual Enterprise, semantic, ontology, web services

Title of the Paper: Research on the Application of Education Information Service Platform Based on WebGIS


Authors: Zheng Yue-Feng, Ma Wei-Feng, Mao Ke-Ji

Abstract: Along with the development of education, it becomes more and more important to issue and gain the education information day by day. According to the education information’s characteristic, we can change the single attribute query type to a better one which can satisfies the requirement of education information service through the Web Geographic Information System(WebGIS).This paper proposes a new design for education information service platform based on WebGIS, and analyses the key technologies including MapXtreme’s basic work principle, the architecture and so on. At the same time, the paper introduces the function of service platform, data structure and the implementation method of MapXtreme in detail by ASP.

Keywords: Education information service platform, WebGIS, MapXtreme

Title of the Paper: On the Importance of Securing Telephony Systems


Authors: Iosif I. Androulidakis

Abstract: In the following work we present an easy to read essay about the array of threats that modern telephony systems face, that will prove, hopefully, useful for both administrators and simple users. We have taxonomized these threats and we have further provided some useful tips for safeguarding these systems in order to keep enjoying one of the most valuable goods: That of communication.

Keywords: Telephony Threats, Telephony Fraud, Communication Systems Security

Title of the Paper: Generating a Set of Rules to Determine the Gender of a Speaker of a Japanese Sentence


Authors: Kanako Komiya, Chikara Igarashi, Kazutomo Shibahara, Koji Fujimoto, Yasuhiro Tajima, Yoshiyuki Kotani

Abstract: Some work has been reported on the problem of automatically determining the gender of a document’s author as a part of researches to extract features of a document’s author. Japanese language has expressions called masculine/feminine expression, and they can often indicate the gender of a speaker of a conversational sentence. The computer system needs this mechanism in order to make or understand natural Japanese conversational sentences.
The authors made a system that determines the suitable gender of a speaker of a single conversational sentence and named it gender-determining system (GDS). It generates a set of rules to determine the more suitable gender of a speaker of a sentence automatically, by decision tree learning. The authors employed six linguistic features for each of two morphemes at the end of a sentence and presence or absence of morphemes whose part of speech is a miscellaneous pronoun or a particle for ending as features of decision tree learning. The authors calculated the accuracy of GDS using the cross validation method and it was approximately 69.3% when human could answer the same problem with approximately 71.7%. The authors showed decision tree learning is more suitable than multiple regression analysis or Bayesian estimation in order to classify the gender of the speaker of Japanese sentences and generate a set of rules to determine them, and selected the suitable features as the inputs of GDS. The set of rules GDS generated indicates, for example, women speak more politely than men in Japan.

Keywords: Natural language processing, rule generation, decision tree learning, gender-determining, knowledge acquisition, data mining

Title of the Paper: A Cross-Layer Based Joint Algorithm for Power Control and Scheduling in CDMA Wireless Ad-Hoc Networks


Authors: Rekha Patil, A. Damodaram

Abstract: In CDMA wireless ad-hoc networks; an important goal is, permitting the requested calls of different users maintaining the quality of service. Because of interference and power, the CDMA capacity is restricted in general. The interference will increase as soon as the number of users rises by the reason of non-orthogonal factor. Consequently, there is a limit to the maximum number of users. In this paper, a cross-layer based joint scheduling and power control algorithm has been proposed with the objective of minimizing the interference level and call rejection rate. For achieving this, the algorithm determines the optimum set of admissible users with suitable transmitting power level. We introduce the notion of power control as part of a contention-based multiple access protocol that characterizes successful transmissions depending on a set of signal-to-interference-and-noise ratio (SINR) constraints (which directly translates to quality of service (QoS) constraints on the bit-error rate (BER) at individual receivers). The performance of our algorithm in a set of admissible and non-admissible users has been assessed using simulation results. Moreover, it is exposed that power control algorithm converges for a set of admissible users.

Keywords: Ad-hoc networks, CDMA, SINR (signal-to-interference-and-noise ratio), QoS (Quality of service), BER (bit-error rate), Cross layer design

Title of the Paper: The Communication Unit of Measuring Device in Power Engineering


Authors: Petr Mlynek, Martin Koutny, Jiri Misurec

Abstract: Various devices, for example electrometers, can be connected to the Internet by means of the communication unit. Thanks to the communication unit, remote acquisition of power consumption data is enabled. This article focuses on the design of the communication unit for remote data acquisition. The article also deals with the design and implementation of the authentication, secure data transmission, and transmission block integrity. Finally describes the system for testing robustness of the communication unit.

Keywords: Communication unit, remote data acquisition, RCM3700, Internet, measuring device, authentication, transmission block, Dynamic C, attack

Title of the Paper: Flexible Authentication Framework with Bound Authentication and Authorization


Authors: Jan Hajny, Tomas Pelka, Vaclav Zeman

Abstract: User authentication is an important part of computer network cryptography. It becomes more and more essential for security with the latest progress in the field of computer science. We analyze latest trends in the article. Our goal is to answer the question whether these trends reflect current state in computer networks. We are focused on security and from this point of view we find the progress unsatisfactory. The reason is that most of current work is focused on operational parameters more than on security. That’s why we give an example of less known authentication methods which can solve the most important issues of current protocols – security and protocol flexibility. The main advantage of one of these methods is its mathematical model which can prove security. As the flexibility of the method is also vital for modern multi domain networks we provide a modification of this method to improve the process of authentication and authorization.

Keywords: Cryptography, Authentication, Authorization, Security, Zero-Knowledge, Password-based authentication

Title of the Paper: On the Design of an Ohmic RF MEMS Switch for Reconfigurable Microstrip Antenna Applications


Authors: M. Spasos, N. Charalampidis, N. Mallios, D. Kampitaki, K. Tsiakmakis, P. Tsivos Soel, R. Nilavalan

Abstract: This paper presents the analysis, design and simulation of a direct contact (dc) RF MEMS switch specified for reconfigurable microstrip array antennas. The proposed switch is indented to be built on PCB via a monolithic technology together with the antenna patches. The proposed switch will be used to allow antenna beamforming in the operating frequency range between 2GHz and 4GHz. This application requires a great number of these switches to be integrated with an array of microstrip patch elements. The proposed switch fulfills the switching characteristics as concerns the five requirements (loss, linearity, voltage/power handling, small size/power consumption, temperature), following a relatively simple design, which ensures reliability, robustness and high fabrication yield.

Keywords: Ohmic, resistive, direct contact, switch, RF MEMS, PCB, reconfigurable, microstrip antenna array

Title of the Paper: Methodological Issues in Cross-Cultural and Interdisciplinary Research on Sustainable Development


Authors: Anita Trnavcevic, Davorin Kralj

Abstract: One of the perspectives is to understand and place sustainable development within broader picture of globalization and paradigm shift. As long as we ‘neatly’ divide education, sustainable development and politics we can discuss them as separate ‘fields’ of work. Globalization is associated with processes, such as internationalization, international relationships, unification and diversity, local and global and similar. It ‘occurs’ in all areas of social life and from some points of view in all scientific disciplines.
The purpose of this article is to present methodological issues related to interdisciplinary and cross-cultural research and sustainable development. We can observe cross-cultural research in management, education, and in other disciplines of social sciences. Cross-cultural research, however, requires translation. If research is understood as a form of communication then cultural dimension play role in data collection stage as well as in other stages of research design. When questionnaires, tests and other instruments of data collection are used in different cultural and linguistic groups a question of equivalence becomes essential. Our consideration is that questionnaires like ours are subjected to double translations: from one field or discipline to other and from one language to other. In these double translations cultural equivalence basically cannot be ensured. Qualitative studies, however, can embrace cultural dimension.

Keywords: Cultural equivalence, cross-cultural research, education, interdisciplinary research

Title of the Paper: An Efficient Partition and Matching Algorithm for Query-Set-based Broadcasting in Multiple Channel Mobile Environment


Authors: Jing-Feng Lin, Guang-Ming Wu, Derchian Tsaih

Abstract: Broadcast is an efficient and scalable method for resolving the bandwidth limitation in a wireless environment. In many applications, mobile clients might need more than one data item. However, most previous researches on query-set-based broadcasting are restricted to a single broadcast channel environment. The results are limited applicability to the upcoming mobile environments. In this paper, we relax this restriction and explore the problem of query-set-based broadcasting in multiple broadcast channels. In multi-channel query-set-based broadcasting, we discover data collision (two data items in the same query set are arranged on two channels at the same time slot) is an important factor to affect users’ access time. In this paper, we introduce the new data collision problem motivated by multi-channel query-set-based broadcasting environment. We then present a two-stage scheme of data partitioning and data matching to solve the new data collision problem. Experiments are performed to justify the benefit of our approach.

Keywords: Access time, data broadcast, mobile environment, multi-channel, query-set-based broadcasting

Title of the Paper: An Investigation on User Communication Behavior in an Interactive Whiteboard Technology Environment


Authors: Chia-Cheng Shen, Huan-Ming Chuang

Abstract: Interactivity is the key characteristic in interactive whiteboard technology (IWT). This study aims to provide a better understanding of communication behavior in IWT. This research’s objective is to investigate the effects of the interactivity level on a user’s attitude and intention toward the use of IWT. As a result, we cite the technology acceptance model (TAM) to support this research. Specifically speaking, our test consisted of system characteristics (interactivity) and extrinsic motivation (TAM), in an integrated theoretical framework of IWT behavior. A survey of 340 elementary school students found strong support for the model. We used the confirmatory factor analysis (CFA) to examine the measurement model, and applied structure equation modeling to access the empirical strength of the relationships in the proposed framework. Overall, the conclusions were placed into two categories: methodological and theoretical. On the methodological front, we demonstrate the development of a reliable and valid measure that captures a critical construct to understand IWT behaviors. On the theoretical front, the results reveal that attitude and behavioral intention are directly/indirectly affected by interactivity, perceived ease of use, and perceived usefulness.

Keywords: Interactive whiteboard technology (IWT), Interactivity, Technology Acceptance Model (TAM)

Title of the Paper: Adaptive MMSE Rake-Equalizer Receiver Design with Channel Estimation for DS-UWB System


Authors: Yi-Jen Chiu

Abstract: In this paper, a robust adaptive MMSE Rake-equalizer receiver scheme is presented with channel estimation that has been transmitted in Direct Sequence-Ultra Wideband (DS-UWB) system. The DS-UWB has a fine path resolution by transmitting information with ultra short pulses. The Rake receiver is known as a technique that can effectively combine paths with different delays and obtain the path diversity gain. Due to sub-nano seconds narrow pulse and the large transmission bandwidth in the systems, we therefore use equalizer to overcome the resulting ISI and a long delay spread in the characterization of the UWB channel. The proposed receiver structure reduces intense multi-path destruction and severe inter-symbol interference (ISI) by using a combined adaptive Rake and equalizer structure referred to as the MMSE (minimum mean square error) algorithm. Channel information is obtained through the use of a least mean square (LMS) adaptive algorithm on the training sequence of a preamble. The indoor environment is represented by dense multipath channel models proposed by IEEE 802.15.3a. Simulation results show that the new scheme employing the energy of a few paths to obtain better performance than the traditional maximum ratio combining (MRC) Rake receiver.

Keywords: Least mean squares (LMS), minimum mean square error (MMSE), adaptive receiver, direct sequence ultra wideband (DS-UWB)

Issue 2, Volume 8, February 2009

Title of the Paper: A Wide-Beam Array Antenna Using Shorted-End Curved Dipoles on a Reflector Plane


Authors: Rangsan Wongsan

Abstract: This paper presents a wide-beam array antenna for broadcasting station by using two curved dipoles, which its both ends of each dipole are electrically shorted on the surface of a square conducting reflector and connected to the ground system and the feed point is excited at the center of each one. Advantage of this antenna should possess physically strong structure, easy fabrication, and cost effectiveness. Because of the elements of array are made of the straight dipoles, which their arms are curved for enlarging the beamwidth and shorted on a metallic reflector for increasing total directive gain and robusting the structure. The Method of Moment (MoM) is utilized to solve numerically the electrical currents that distribute along the curved dipole, which are used to determine the impedance characteristics and the radiation patterns of this antenna. The beamwidth of azimuth pattern of the proposed antenna is around 12, which is suitable for achieving omnidirectional pattern for TV broadcasting station by placing them around the tower at least three panels. Having confirmed the validity of this approach, the UHF-band antenna prototype is fabricated, tested experimentally and shows good performance.

Keywords: Curved dipole, array antenna, wide-beam antenna, broadcasting antenna, method of moment

Title of the Paper: Constructing a New Communication System by Integrating the GSM to the Satellites Infrastructure


Authors: Muzhir Sh. Al-Ani, Basil M. Al-Kasasbeh, Rafa E. Al-Qutaish, Mohammad I. Muhairat

Abstract: The current researches and industries are looking forward to integrate different technologies to get a global technology that offers all of the intended services in a simple way. In this paper, a new communications system is proposed to integrate the use of GSM over the available satellites infrastructures. The proposed communications system could be used to facilitates and get benefits of both systems (the GSM and Satellites) to achieve competitive services over the world. The proposed system is concentrated on a global communications system that served all over the world and gives some specialization and privacy for each country. Furthermore, this paper shows an algorithm on how to implement the GSM over satellite systems in an efficient, flexible, and cost-effective manner.

Keywords: GSM, GSM over Satellite, Mobile Communications, Satellite Communications

Title of the Paper: Enhancing DSR Protocol Performance in Mobile Ad Hoc Network Using ACK Reply


Authors: Abdullah Gani, Qi Han, Nor Badrul Anuar, Omar Zakaria

Abstract: This paper presents a new method to improve performance of DSR in Ad Hoc Network. We present an analysis of DSR protocol and propose our algorithm to improve the performance of DSR protocol by using ACK reply path as a backup route when an original route fails in Mobile Ad Hoc networks. In the traditional DSR protocol, a backup route will be initiated to transfer data in route cache when a route is broken. However, if the backup route is also failed, it will affect the overall network performance. We modify the DSR so-called Modified DSR protocol (MDSR) with the aim that the source node can still receive the ACK reply from destination node when an original route is broken, which means data packets can be transferred along with the ACK path. MDSR deploys the idea of TCP-BuS to solve unnecessary resending of lost data packets. We simulate our proposed model in NS2, compare the MDSR with DSR in the performance of end-to-end delay and packet delivery ratio. The result shows that the performance of MDSR is better than the traditional DSR protocol.

Keywords: Ad Hoc, Wireless Network, DSR protocol, ACK, Performance

Title of the Paper: Functioning the Intelligent Programming to find Minimum Dispersion Wavelengths


Authors: Maan M. Shaker, Mahmood Sh. Majeed, Raid W. Daoud

Abstract: A new method based on genetic concepts is suggested to analyze and determine the transmission (propagation and dispersion) characteristics for conventional fibers as well as photonic crystal fibers. The power and the advantage of this work, lie in the fact that it could be applied to any optical fibers type with any refractive index profile and the method computes its proper and accurate propagation constant which leads to investigate the desired dispersion and minimizes it to the least possible value.

Keywords: Optical fibers, PCF, dispersion and genetic algorithm

Title of the Paper: Theoretical Optimum Designation of Distributed Raman Amplifiers in Different Media


Authors: Farzin Emami, Amir H. Jafari

Abstract: Raman Amplifiers (RAs) are a group of amplifiers which have various applications in optical communications. Data transmission media utilized for RAs are optical fibers operating in nonlinear regime. We present the performances and characteristics of RAs by utilizing a set of coupled differential equations and numerical simulations. Two types of fibers with different gain characteristics, germanium-doped and silica fibers are used in our numerical simulations. So, the optimum initial values of the pump powers for a system with 10 pumps are recalculated and optimized again. We did our simulation to have a flat gain and low noise characteristics. Another aspect of the fiber media is their effective areas and we studied the effects of this parameter on the net gain of the RAs. Finally, the noise figure computations are discussed for our 10 pumps bidirectional amplifier which is optimized.

Keywords: Raman amplifiers, Noise figure, Nonlinear gain, Numerical simulation, Optimization

Title of the Paper: Behavioral Modeling and Simulation of Underwater Channel


Authors: Nejah Nasri, Laurent Andrieux, Abdennaceur Kachouri, Mounir Samet

Abstract: The Ocean is a dynamic and complex environment; it is a very complicated transmission channel that can change rapidly with the environmental conditions. Hence, to avoid failure of underwater monitoring missions, it’s crucial to predict the behavior of underwater acoustic channel. In this paper, several fundamental key aspects of underwater acoustic channel are investigated. A model characterizing the underwater acoustic channel is introduced, and how underwater channel can be simulated is discussed. In addition, this paper describes a methodology for top-down design, modeling, and simulation of underwater channel using hardware description language VHDL-AMS. The following analysis may provide precious guidelines for the design of underwater communication systems.

Keywords: Underwater communication, underwater channel model, behavior modeling acoustic signal, VHDL-AMS language

Title of the Paper: A Distributed Adaptive Scheme for Detecting Faults inWireless Sensor Networks


Authors: Jae-Young Choi, Sung-Jib Yim, Yoon Jae Huh, Yoon-Hwa Choi

Abstract: This paper presents a distributed adaptive scheme for detecting faults in wireless sensor networks. Each sensor nodes makes a local decision based on the comparisons of its own readings with those of neighbors, along with the dissemination of the decision to them, if necessary. At the end of each fault detection cycle, each node dynamically adjusts critical parameters in the distributed fault detection algorithm, such as node degree and thresholds, resulting in high performance for a wide range of fault probabilities. By extensive computer simulation the scheme is shown to be scalable with the number of faulty sensor nodes except for sparse networks where the average node degree is extremely low.

Keywords: Sensor networks, distributed, adaptive, fault detection, fault diagnosis

Title of the Paper: Wide-Band Beamformer with Integrated Antennas


Authors: Amirhossein Fereidountabar

Abstract: As part of the development of a new international radio-telescope SKA (Square Kilometer Array), three phased-array prototypes with increasing complexity have been developed. The final SKA telescope will consist of more than one million receiving antenna elements and will operate in the frequency range of 200 to 2000 MHz. One of the challenges of the next generation radio telescopes for astronomy is its capacity to cope with the increasing problem of Radio Frequency Interference (RFI). The application of phased-array beamforming techniques opens the possibility to spatially null RFI in the digital domain prior to correlation. This paper presents results from the third phased-array experimental demonstrator that is being developed at NFRA, the THousand Element Array (THEA), on the RF Beamformer boards with integrated antenna array.

Keywords: Beamforming, Antenna arrays, Wideband beamformer, Sensitivity, Integrated antennas, Dual beam, Measurement, Testing

Title of the Paper: Energy Level and Link State Aware AODV Route Request Forwarding Mechanism Research


Authors: Hao Jutao, Zhao Jingjing, Li Minglu

Abstract: Ad-hoc On-demand Distance Vector (AODV) provides scalable and effective solution for packet routing in mobile wireless ad hoc networks, however, the path generated by this protocol may derivate far from optimal because of inconsideration of node power ,load unbalance and link state,resulting in energy consumption of each nods is imbalanced and reduce the lifetime of whole networks. Based on the basic AODV protocols, an improved protocol is presented in this paper. When the protocol is selecting a route, node power, load status and link state between nodes are all considered. The proposed protocol can improve the network performance. Through the simulation on NS2, it is confirmed that the improved AODV protocol has higher package delivery ratio, lower end to end delay and lower routing overhead than basic AODV protocol.

Keywords: On demand distance vector routing,Mobile Ad hoc networks , Link state, Energy aware routing

Title of the Paper: The Implementation of Satellite Images and Associated Digital Image Processing in Addition to GIS Modelling for Urban Mapping in Amman area, Jordan


Authors: Eyad H. R. Fadda, Maher Kakish, Tariq A. Al Azab

Abstract: Thematic maps and geo-spatial database are important tools that can be used for many purposes, such as mapping urban features, agricultural area and road network; they are also useful in urban planning and city planning. Many urban features were depicted from topographic maps and satellite digital images covering west of Amman area. GIS, remote sensing and associated digital image processing techniques have been applied on the satellite digital images in order to enhance the images. On screen digitizing techniques for both topographic and satellite images were applied to delineate Urban areas, agricultural areas, road networks. Several new maps for the western part of Amman area were produced from the topographic maps and satellite images (IKONOS 2002 and 2006). The resultant maps are: urban areas, road networks and agricultural area. The produced layers and their attributes were stored as geo-spatial database for west of Amman area using GIS technology by Arc GIS software. The produced maps and layers can be used for urban planning.

Keywords: Digital image processing techniques, Digital mapping, GIS modelling, Spatial domain filters, Geospatial database and Urban mapping

Issue 3, Volume 8, March 2009

Title of the Paper: Parallel Tabu Search for Optimizing the OSPF Weight Setting Problem


Authors: Sadiq M. Sait, Mohammed H. Sqalli, Syed Asadullah

Abstract: The problem of setting the Open Shortest Path First (OSPF) weights on links such that congestion can be avoided is proved to be NP-hard. Many iterative heuristics have been applied to solve the OSPF weight setting (OSPFWS) problem. As the size of any combinatorial optimization problem increases, it becomes more difficult to find an optimum solution using sequential algorithms. Parallelization of modern iterative heuristics has been proven to produce improved solution precision and timing. In this paper, we investigate the parallelization of Tabu Search and apply two variants of a Parallel Tabu Search (PTS) heuristic on the OSPFWS problem. It is shown through experimental results that both PTS approaches produced better solutions quality compared to the sequential heuristics; specifically for larger topologies. In one approach, we propose a new design for our parallel cooperative search algorithm, which performs better than the conventional parallel heuristic. The purpose of this new design is to induce diversification into the search to explore a larger search space. We also show that the new approach performs better than the conventional parallel heuristic.

Keywords: Open Shortest Path First (OSPF), OSPF Weight Setting Problem, NP-hard, Iterative Heuristics, Parallel Tabu Search

Title of the Paper: Processing Data for Colored Noise Using a Dynamic State Estimator


Authors: Marius-Constantin Popescu, Onisifor Olaru, Nikos Mastorakis

Abstract: This paper treats data reduction in array processing for the spatially colored noise case. The purpose is to reduce the computational complexity of the applied signal processing algorithms by mapping the data into a space of lower dimension by means of a linear transformation. We discuss ways to implement the transformation and show that it suffices to estimate the array covariance matrix instead of the noise covariance matrix in the design process of the optimal transformation. Computer simulations are given that illustrate the problem of interference from out-of-band-sources that result when a beamspace transformation is designed to focus on a particular sector. The presents an dynamic state estimator. The method uses ANN based bus load prediction for the prediction step in the DSE.

Keywords: Adaptive data reduction, Colored noise, Dynamic state estimation, Load prediction

Title of the Paper: Sustainable Business and Environmental Indicators


Authors: Uros Ogrin, Davorin Kralj

Abstract: This article focuses primarily on the research in Sustainable Business and Environmental Indicators of 120 Slovenian companies, in view of a general environmental management model. The research for this paper is based on the collection and analysis of quantitative and qualitative data. From research results, we can conclude that at a declarative level, environmental care is reflected in leadership and policy, strategy and organizational culture in the area of environmental management, where as the actual care is implemented in the processes related to this area. System thinking and multi view approaches, which are a must for a successful establishment of a sustainable business and environmental indicators, are of great importance. It is essential for the real effectiveness of environmental management to have appropriate leadership and keep well-regulated interpersonal relations in an enterprise. Congenial and stimulating atmosphere, promoting relaxed free and unimpeded activities, work satisfaction and satisfaction with co-operation with others, are all elements distinguishing excellent performance. When implementing changes, employees should be motivated adequately. Environmental indicators are powerful tools that serve many purposes, useful as tools for performance evaluation and public information. The development of indicators is a dynamic process that is constantly subject to updating and improvement.

Keywords: Environment, environmental indicator, management, sustainable business, sustainable development

Title of the Paper: An OFDM-based Transmission Scheme for Underwater Acoustic Multimedia


Authors: Chin-Feng Lin, Chen-Hsiang Shih, Cheng-Pin Chen, Shao-Wei Leu, Jiing-Kae Wu, Ching-Hsiang Tseng, Hsien-Sen Hung, Fu-Sheng Lu, Ivan A. Parinov, Shun-Hsyung Chang

Abstract: In this paper, we propose an orthogonal frequency division multiplexing–based (OFDM-based) underwater acoustic multimedia system. An essential feature of this system is that it offers greater power and schemes with significant error protection for the transmission of sensor data information requiring a higher quality of service (QoS). To realize maximum resource utilization or minimum total transmission power, we also include an adaptive modulation strategy into the system. The proposed underwater acoustic multimedia system employs high power, low speed modulation, and schemes providing significant error protection for the transmission of sensor data messages requiring a stringent bit-error rate (BER). In contrast, low power, high speed modulation, and less capable error protection schemes are provided for messages that can tolerate a high BER. A simulation was carried out to verify the functionality of the proposed system in a practical underwater acoustic multimedia scenario.

Keywords: Underwater multimedia, acoustic, OFDM, QoS, power assignment, unequal error protection, adaptive modulation

Title of the Paper: Analysis of a Fixed-Complexity Sphere Decoding Method for Spatial Multiplexing MIMO


Authors: M. Haridim, H. Matzner, V. Neder, D. Ezri

Abstract: A new detection algorithm for decoding multiple-input multiple-output (MIMO) transmission is proposed and analyzed. The method is based on combining sphere decoding (SD) and zero forcing (ZF) techniques. The proposed method performs a fixed number of operations to detect the signal, independent of the noise level, and hence provides a fixed complexity near optimal performance. The algorithm is especially suited for systems with a large number of transmit antennas and allows efficient implementation in hardware. The high efficiency of this algorithm is obtained by limiting the number of overall SD iterations. Moreover, in the proposed method matrices with high condition number are more likely to undergo SD.

Keywords: MIMO, detection complexity, spatial multiplexing, sphere decoding, zero forcing, maximumlikelihood

Title of the Paper: Communication and Processing Consideration for Alerting Systems Implemented through Mobile Sensor Networks


Authors: Dan Popescu, Radu Dobrescu, Maximilian Nicolae, Alexandru Iordan

Abstract: At the beginning of the paper it is presented an alerting system architecture based on mobile sensor network. Then it is analyzed the current available radio communication infrastructure which can be used for implementation of alerting systems in conjunction with the alerting systems requirements. Further we shown how the digital signal processor (DSPs) are the best fit for the processing level. We propose some ideas of selection criterion based on this analyze and an implementation of a mobile sensor network with applicability in alerting systems. Built with the purpose of surveillance, data gathering and warning, alert systems could benefit from the increase flexibility offered by a mobile sensor network. In order to ensure a low cost and an extended battery life, for communication between nodes the ZigBee standard was chosen. For the prompt response of the system we design a software kernel with real time operation and implement on DSP architecture.

Keywords: Mobile sensor networks, Alert system, Communication protocols, Digital signal processing, Power consumption, Software structure

Issue 4, Volume 8, April 2009

Title of the Paper: Practical Horizon Plane and Communication Duration for Low Earth Orbiting (LEO) Satellite Ground Stations


Authors: Shkelzen Cakaj

Abstract: Communication via satellite begins when the satellite is positioned in the desired orbital position. Ground stations can communicate with LEO (Low Earth Orbiting) satellites only when the satellite is in their visibility region. The visibility region is in fact the horizon plane. Because of natural barriers or too high buildings in urban areas, practical horizon plane differs from the ideal one. The duration of the visibility and so the communication duration varies for each satellite pass at the ground station, specifically for LEO satellites which do move too fast over the Earth. This paper discusses the satellites motion detection, the difference in between ideal and practical horizon and further the variations of the communication duration between the ground station and LEO satellites. Main objective is determination of practical horizon plane and critical maximal elevation angle related to communication duration. For this paper, data recorded at the Vienna satellite ground station within the Canadian space observation project “MOST” (Micro variability and Oscillations of Stars) are applied. Vienna ground station system was set up at the Institute for Astronomy of the University of Vienna in cooperation with the Institute of Communications and Radio- Frequency Engineering of the University of Technology in Vienna.

Keywords: LEO, satellite, ground station, elevation, azimuth, horizon plane, communication duration

Title of the Paper: Computer Network Routing Based on Imprecise Routing Tables


Authors: Milan Tuba

Abstract: This paper examines problems that arise from the fact that dynamic routing never relies on the precise, current information about the network state. It is a normal expectation that dynamic routing has to give better results than a static one. However, it takes some time to collect information about the network current state, and optimization is always done with that imprecise information. This situation is examined by a complete mathematical analysis of a simple network. We show that dynamic routing gives better results than static, as expected, but that the margin is much smaller then intuitively expected. Further analysis shows that that minor advantage can easily be lost if there is even a small error in the dynamic routing tables, and actually dynamic routing can easily become worse than static. Quantitative analysis shows that delays in building routing tables can affect dynamic routing performance unexpectedly strongly. The conclusion is that dynamic routing should not try to adapt to traffic changes very fast.

Keywords: Computer network routing, Static optimization, Dynamic optimization, Modeling

Title of the Paper: On-line PBL System Flows and User's Motivation


Authors: Hsieh-Hua Yang, Lung-Hsing Kuo, Hung-Jen Yang, Jui-Chen Yu, Li-Min Chen

Abstract: Problem-based learning is the bridge to connect learners with real world and is the trigger setting for high level thinking skill. On-line technology is supporting our learning in many ways. There is a need to understand not only what framework could help conduct on-line problem-based learning but also the learner’s motivation. The purpose of this study was to draw up a framework of on-line problem-based learning. Based on literature review, a theoretical framework was identified. An implementation of this framework was conducted to verify the feasibility based upon the learner’s motivation. Motivation survey was conducted to explore the learner’s response. Concerning the framework of on-line PBL, the results of the evaluation conducted in this study implied that the feasibility existed. Pertaining to motivation, learners suggested that their motivations were from both the on-line social network and real world problem.

Keywords: Problem-based learning, On-line system flow, Motivation

Title of the Paper: Creating a Virtual Information Center for Industrial Design


Authors: Manlai You, Li-Min Chen, Lung-Hsing Kuo, Hung-Jen Yang, Hsieh-Hua Yang, Jui-Chen Yu

Abstract: The purpose of this study was to propose a layout of an on-line information center for industrial design. Based upon literature review, the major component was revealed. The design information center should be a multimedia database which was designed to support the activities of industrial product designers globally. In this study, user data services were created. The multimedia data types, user interface issues, database construction, and intended audience were discussed. This paper provides a general outline of designing an on-line information center for industrial design. Its aims and objectives, the innovative application of technology, and the underlying network structures were also proposed.

Keywords: On-line information center, industrial design

Title of the Paper: Assessing and Managing Mobile Technostress


Authors: Jui-Chen Yu, Lung-Hsing Kuo, Li-Min Chen, Hung-Jen Yang, Hsieh-Hua Yang, Wen-Chen Hu

Abstract: From time to time, new technology brings people impacts. Mobile information system provides new way for manipulating information in both directions, sending out and bringing in. Anywhere and anytime are both the characteristics of mobile technology that people could get rid of. The purpose of this study was to explore mobile technostress and bring up the discussion of assessing and managing. A balance theory was concluded and how to cope with mobile technostress was also discussed.

Keywords: Mobile technostress, characteristics of mobile technology, balance scale

Issue 5, Volume 8, May 2009

Title of the Paper: Equalization of Energy Consumption at Cluster Head for Prolonging Lifetime in Cluster-based Wireless Sensor Networks


Authors: Yung-Fa Huang, Neng-Chung Wang, Chin-Ling Chen, Jong-Shin Chen, Zong-Min Guo

Abstract: In cluster-based wireless sensor networks (WSN), the most of energy is consumed in cluster head which performs data aggregations and relaying. The lifetime in cluster-based WSN is subjected by the lifetime of cluster heads. Therefore, in this paper, we equalize the energy consumption of the cluster heads to prolong the lifetime of WSN. After equalization, we obtain the length of sides of cluster area. Numerical results show that the length of far site cluster is shorter than the nearest cluster to perform equalization for all three routing schemes. Moreover, simulation results show that the three-hop scheme can obtain the most energy efficiency than other two schemes.

Keywords: Wireless sensor network, Clustering, energy efficiency, Cluster head, Energy consumption equalization, Network lifetime

Title of the Paper: Remote Control Technique with OFDMA Based Approach for Biologically Inspired Robots in a Mobile Ad hoc Network (MANET)


Authors: R. P. Chatterjee, B. Sutradhar, Uma Dutta

Abstract: Wireless communication is adding improvements in remote controlling techniques of vehicles or mobile robots day by day. From mission based AGVs to biologically inspired robots each area of robotic research is being enriched from time to time with the advent of Wi-Fi technologies like 1G, 2G, and 3G etc. This paper reflects a novel approach to control a mobile ad hoc network built with a number of snake robots to monitor an area like coal mines. Each agent of this network is having DSP based controller for processing files and instructions from remote computer through a wireless network structured in orthogonal frequency division access approach. DSP controllers redirect the segments of the robot to exhibit snake-like locomotion. Desired transfer function for lateral undulation is derived using two controller design approach such as, graphical domain approach and frequency response approach and the impulse response of each controller are loaded segment-wise in each agent. Length and segment-wise distinction for every robot is considered for wireless file transfer and instruction from remote station within a limited bandwidth. Problems due to inter-symbol interference (ISI), multipath fading and limitation of ISM band have also been overcome.

Keywords: Biologically inspired robot, snake robot, OFDMA, MANET

Title of the Paper: Perceptual Evaluation of Speech Quality for iLBC Vocoder with Uneven Level Protection over Narrow Band MSK Radio


Authors: Shih-Kai Lee, Lu-Ping Keng

Abstract: Narrow band MSK(Minimum Shift Keying) radio is applied for high receiving sensitive wireless communications like “walky-talky”. iLBC (internet Low Bit-rate Codec) is widely used in VoIP (Voice over IP) applications like “Skype”. This paper is concerned with the speech quality by using iLBC in narrow band MSK wireless communication. Several ULP (Uneven Level Protection) strategies to protect different part of iLBC coded payloads are evaluated under AWGN (Additive White Gaussian Noise). We utilize PESQ (Perceptual Evaluation of Speech Quality) to evaluate the perceptual speech quality. Simulation results show that significant improvement of PESQ scores are obtained by using appropriate ULP strategies so that our proposed MSK radio system can also achieve high receiving sensitivity.

Keywords: MSK, iLBC, VoIP, ULP, PESQ

Title of the Paper: Multi-carrier Transmission Techniques for Wireless Communication Systems: A Survey


Authors: Haitham J. Taha, M. F. M. Salleh

Abstract: The next generation wireless communications systems require higher data rates transmission in order to meet the higher demand of quality services. Research in wireless digital communications techniques have been expending very rapidly in the last few decades, resulting more reliable wireless communication systems that operate at higher spectral efficiency. Since there have been an increased in demand for higher data rate transmission, the systems are incorporating the multi-carrier transmission techniques. Therefore, Orthogonal Frequency Division Multiplexing (OFDM) is one of the leading candidates for future wireless systems. The objective of the paper is to provide a survey on multi-carrier transmission techniques i.e. OFDM and the combination of OFDM with Code Division Multiple Access (CDMA). The review on this rapidly expending area of wireless communication field is carried out on research works for the past 15 years. And in this survey also we Trying to explain how to use Discrete Wavelet Transform based OFDM (DWT-OFDM) Instead of using Fast Fourier Transform based OFDM Fast Fourier Transform based OFDM (FFT-OFDM). This study outlines the state-of-the art of OFDM novel technique as well as the methods of multi-carrier - Code Division Multiple Access (MC-CDMA) and MC- Direct Sequence-CDMA (MC-DS-CDMA).

Keywords: Multi-carrier-CDMA (MC-CDMA), Multi-carrier - Direct Sequence-CDMA (MC-DS-CDMA)

Title of the Paper: Large-scale Communication Network Behavior Analysis and Feature Extraction Using Multiple Motif Pattern Association Rule Mining


Authors: Weisong He, Guangmin Hu, Xingmiao Yao

Abstract: Minimize false positive and false negative is one of the difficult problems of network behavior analysis. This paper propose a large-scale communications network behavior feature analysis method using multiple motif pattern association rule mining, analyze multiple behavior feature time series as a whole, produce valid association rules of abnormal network behavior feature, characterize the entire communication network security situation accurately. Experiment with Abilene network data verifies this method.

Keywords: Network behavior analysis, principal components analysis, time frequency analysis, multiple motif pattern association rule mining

Title of the Paper: Fast Detection of Specific Information in Voice Signal over Internet Protocol


Authors: Hazem M. El-Bakry, Nikos Mastorakis

Abstract: The world Telecommunications industry caters to both Wireline and Wireless business. In the present Fourth Generation (4G) wireless world rapid change is the only constant factor. The biggest paradigm change being the move from Circuit Switched to Packet Switched technologies. Voice over Packet (VoP) is transforming telephony by rapidly replacing the legacy circuit-switched technology. The VoP technology unites the telephony and data worlds allowing voice, facsimile, and video traffics to be relayed over managed IP networks or corporate intranets around the world. In this paper, various aspects of Voice over Internet Protocol (VoIP) are discussed, including the architecture for the NGMN, challenges, standards and the application areas. In addition a new approach for fast detecting certain information in VOIP is presented. The entire data are collected together in a long vector and then tested as a one input pattern. Proposed fast time delay neural networks (FTDNNs) use cross correlation in the frequency domain between the tested data and the input weights of neural networks. It is proved mathematically and practically that the number of computation steps required for the presented time delay neural networks is less than that needed by conventional time delay neural networks (CTDNNs). Simulation results using MATLAB confirm the theoretical computations.

Keywords: Voice over IP, Next Generation Mobile Networks, Fast Information Detection, Cross Correlation, Frequency Domain

Issue 6, Volume 8, June 2009

Title of the Paper: An Adaptive Coded Modulation with Multi-Levels QoS Analysis in Multimedia Environment


Authors: Lamia Chaari, Mohamed Fourati, Nouri Masmoudi, Lotfi Kamoun

Abstract: This article proposes an adaptive coded modulation (ACM) with multi-levels qualities of service analysis, which can be used to perform physical layer functions in software radio receivers for beyond third generation systems. ACM approche employs multiple coding and modulation schemes in order to adapt instantaneously spectral efficiency to the signal-to-noise ratio variations SNR. The idea is to study transmission schemes performance which allow dynamic bandwidth sharing among various services in multimedia mobile and wireless networks in different channel environments. The aim is to select the appropriate modulation and channel coding modes based on signal quality measurement via a decision feedback block (DFB). Decision taken by the DFB block is based on different QoS parameters that depend in class and type of multimedia traffic. The DBF block is introduced in order to mitigate the channel quality fluctuations. The channel coded adaptive modulation schemes can be viewed as a lower complexity alternative of mitigating the channel quality fluctuations in comparison to multiple-transmitter and multiple-receiver. Implementing DFB necessitate to simulate and analyze different combinations between modulation and channel coding blocs for different data types.

Keywords: Channel coding, adaptive modulation, Signaling, image, Multimedia, SDR

Title of the Paper: Selection Combining Receiver in the Presence of Ricean Fading


Authors: Petar Spalevic, Mihajlo Stefanovic, Dusan Stefanovic, Stefan Panic

Abstract: This paper focuses on comparing performances of the selection combining (SC) diversity system in the presence of independent and correlated Ricean fading. For the case of correlated fading, we have presented closed form expressions for probability density function (PDF), and cumulative density function (CDF), at the output of dual branch SC. Also we have presented closed form expressions for system performances such as: average bit error-rate (ABER), outage probability (OP) and average output moments, which is the main contribution of our work. For the case of independent fading between the diversity branches, we have analyzed performances of SC diversity system which consists of two and four input branches. All obtained results are graphically presented.

Keywords: Ricean fading, Selection combining, System performances

Title of the Paper: Multiple Selection Diversity over Exponentially Correlated Nakagami-m Fading Channels in the Presence of Cochannel Interference


Authors: Dragana Krstic, Stefan Panic, Aleksandar Mosic, Mihajlo Stefanovic

Abstract: The system performances of selection combining over exponentially correlated Nakagami-m channels are analyzed in this paper. Selection diversity based on the signal to interference ratio (SIR) is very efficient technique that reduces fading and cochannel interference influence. Fading between diversity branches and between interferers is correlated and Nakagami-m distributed with exponential correlation model. Very useful closed-form expressions for the output SIR’s probability density function (PDF), cumulative distribution function (CDF), and outage probability are obtained, which are the main contributions of this paper. Also, the conclusions about influence of fading severity and correlations between received desired signals and interferences on the system performances, such as outage probability, average-output SIR and amount of fading (AoF), are presented.

Keywords: Cochannel Interference; Signal to Interference Ratio (SIR); Exponential Correlated Nakagami-m fading; Selection Combinig

Title of the Paper: Adaptive Estimation/Compensation Scheme of IQ Imbalance with Frequency Offset in Communication Receivers


Authors: Yi-Jen Chiu, Chien-Sheng Chen, Shao-Ping Hung

Abstract: IQ signal processing is widely utilized in today’s communication system. However, it usually faces a common problem of front-end distortion such as IQ imbalance and frequency offset. Effective algorithms exist for estimating and compensating for IQ imbalance as well as frequency offset, when the two problems are treated separately. With both effects present, such algorithms do not lead to useful estimates of the related parameters. In this paper, we propose a robust technique to estimate and compensate for the IQ imbalance in the presence of carry frequency offset (CFO) by using a known preamble of repeated training sequence. In addition, to solve the problem of performance degradation when CFO is small we developed an adaptive scheme with small residual degradations. The performance of such a scheme has been validated by computer simulations on IEEE 802.11a signals. And it is shown that the proposed method is more robust and renders better performance than existing algorithm.

Keywords: IQ imbalance, carrier frequency offset (CFO), IEEE 802.11a

Title of the Paper: Using Concepts of Control Charts to Establish the Index of Evaluation for Test Quality


Authors: Chiu-Yao Ting, Chwen-Tzeng Su

Abstract: The purpose of this research employs concepts of control charts to establish a new evaluation standard for a test quality index. First, this study establishes criteria for assessing test quality by exploring the item discrimination index (D) in the general test areas. Further, data of this one index are normalized, and standard deviation is applied for the control limit of the control chart. Thus, the zone rules for the standardized D (SD) control chart proposed in this study are found to be an excellent evaluation method for test quality from the perspective of control charts.

Keywords: Test quality, control charts, item discrimination, standard deviation, control limit, zone rules

Issue 7, Volume 8, July 2009

Title of the Paper: An Adaptive Cross-layer Bandwidth Scheduling Strategy for the Speed-Sensitive Strategy in Hierarchical Cellular Networks


Authors: Jong-Shin Chen, Mei-Wen Li, Neng-Chung Wang, Yung-Fa Huang

Abstract: Efficient bandwidth scheduling of wireless bandwidth is critical to cellular system performance. Bandwidth scheduling methods can be divided into cell-layer channel allocation and call-layer channel assignment. Previous studies are focused on the latter type of method. Some problems, such as traffic-load variations among base stations (BSs) and BSs failed to provide wireless communication service, are the cell-layer problems and are difficult to handle using the call-layer methods. Therefore, this study presents an adaptive cross-layer bandwidth scheduling strategy for hierarchical cellular networks. This strategy is implemented to solve the traffic-adaptation and the fault tolerance problem according to the speed-sensitive call-layer method.

Keywords: Cross-layer, speed sensing, traffic adaptation, and fault tolerance

Title of the Paper: Cross-Layer Design and Performance Analysis of TDMA-based Backhaul Network


Authors: Rashid A. Saeed, Zulkalnain Mohd Yusof, Anuar Bin Musa

Abstract: The needs for bridging of digital divide in rural communities and the economics of currently available broadband access technologies motivate for innovate and deploy new system designs and applications. The widely available and flexible WiFi technique meets the cost and suitability targets for rural broadband applications. To cope with the special requirements of rural communication, amendments of 802.11 standards at the MAC protocol level has been introduced. These amendments were important due to the shortcomings of WiFi over long distances under the power constraints. This paper proposes a new 802.11 point-to-multipoint (PMP) technique based on TDD/TDMA technique, this by using one of the access points in the system as centralized/gateway point to the others APs. The discussion includes the TDMA design, architecture on top of the conventional 802.11 MAC. The protocol convergence at the gateway between the access network and the backhaul is also presented. The simulation results present the performance analysis and validate the efficiency of the proposed scheme.

Keywords: Point-to-multipoint (PMP), TDMA, MAC, 802.11 WiFi, rural communications, Cross-Layer Design, WiMAX, network allocation vector

Title of the Paper: Performance Improvement of Double-Layer Networks with Holographic Optical Switches


Authors: Chi-Ping Lee, Chien-Ping Chang, Jiun-Shiou Deng, Ming-Feng Lu, Yang-Tung Huang

Abstract: In our previous research, combining the unique features of the double-layer network and holographic optical switches not only reduces the volume of the whole system and eliminates all interconnection lines and crossovers significantly, but also reduces the number of drivers from N2/4+2Nlog2N-2N to 2Nlog2N. In this paper, modifying the structures of the holographic optical switches to satisfy the characteristics of the double-layer network, the system insertion loss can be minimized significantly from (2log2N-1)(LPBS+2LEOHWP) to (2log2N-2)LPBS+2(log2N)LEOHWP (dB). After rearranging the channels, the number of electro-optic halfwave plates can be decreased significantly from 2N2-2N to 2Nlog2N.

Keywords: Holographic optical switch, polarization beam splitter, double-layer network, optical interconnection network, system insertion loss, signal-to-noise ratio

Title of the Paper: Hopfield Neural Network for UWB Multiuser Detection


Authors: Chia-Hsin Cheng, Guo-Jun Wen, Yung-Fa Huang

Abstract: The Hopfield neural network (HNN) is introduced in the paper and is proposed as an effective multiuser detection in direct sequence-ultra-wideband (DS-UWB) systems. It can approximate to maximum likelihood (ML) detector by mathematical analysis. According to the HNN-based technique, the computer simulation results show that they have good performances and much lower computational complexity in a multiuser environment.

Keywords: Maximum likelihood, Neural network, Hopfield

Title of the Paper: An Adaptive Load Balance Allocation Strategy for Small Antenna Based Wireless Networks


Authors: Jong-Shin Chen, Neng-Chung Wang, Zeng-Wen Hong, Young-Wei Chang

Abstract: Technological advances and rapid development in handheld wireless terminals have facilitated the rapid growth of wireless communications. Since this tremendous growth of wireless communication requirements is expected under the constraint of limited bandwidth. The small antenna frameworks that can provide more flexible to handle the limited bandwidth will be the mainstream for wireless networks. The antenna divided a cell into several sections. Each section contains a part of the system codes used to provide wireless communications. Therefore, the system codes allocated to each section will effect the system capacity and a reasonable allocation should provide more codes to a section with heavy traffic than a section with light traffic. However, the large number of sections increases the difficult to allocate system codes to sections. Especially, when there are variations in the traffic loads among sections will lessen the traffic-carrying capacity. This study proposes an adaptive load balance allocation strategy for small antenna based wireless networks. This strategy is implemented to solve traffic-adaptation problem that can enhance the traffic-carrying capacity for variations in traffic. Furthermore, the simulation results are presented to confirm the efficiency of the proposed strategy.

Keywords: Small antenna, wireless network, load balance, and traffic-adaptation

Title of the Paper: Fast Convergence Algorithm for Decoding of Low Density Parity Check Codes


Authors: Jin Xie, Liuguo Yin, Ning Ge, Jianhua Lu

Abstract: In this paper, a fast-convergence algorithm is proposed for the decoding of low-density parity-check (LDPC) codes. By putting more weight on the message update from check node to variable node in current iteration, the proposed method speeds up the decoding significantly. Simulation results show that compared with the standard layered min-sum decoding algorithm, the proposed scheme may reduce about 1/6 iteration numbers for LDPC codes used in DVB-S2, with hardware complexity overhead less than 2%.

Keywords: LDPC code, fast convergence decoding algorithm, layered decoding, min-sum algorithm, hardware implementation

Title of the Paper: New Code Construction Method and High-Speed VLSI Codec Architecture for Repeat-Accumulate Codes


Authors: Kaibin Zhang, Liuguo Yin, Jianhua Lu

Abstract: Repeat-Accumulate code has been widely used in various practical communication systems due to its special structure that can be encoded with a low complexity turbo-like encoder and decoded with a high-speed parallel algorithm. However, the construction of RA codes with large girth is still a challenging problem. In this paper, the girth upper bound of RA codes is analyzed and a novel RA code construction scheme is proposed. This scheme generates the parity-check matrix with superimposed structured interleavers, guaranteeing the resulting matrix to be globally optimized. Compared with the RA codes constructed with traditional structured interleavers such as ?-rotation interleavers, pseudo-random interleavers, combinatorial interleavers, and modified L-type interleavers, the codes constructed with the proposed method exhibit better error-correcting performance. Moreover, a parallel VLSI codec architecture is proposed for the RA codes generated with the proposed method in this paper. Modifying the conventional RA encoder architecture, the codec for RA codes from our proposed method may have the same hardware implementation complexity as that for traditional RA codes, while the data throughput of our codec may achieve up to 450Mbps, which may be of great value for practical applications.

Keywords: Repeat-Accumulate (RA) codes, low-density parity-check (LDPC) codes, superimposed structured interleaver (SSI), hardware implementation

Title of the Paper: A New Method for Indoor Location Base on Radio Frequency Identification


Authors: Rung-Ching Chen, Sheng-Ling Huang

Abstract: In recent years, there has dramatic proliferation of research concerned with Radio Frequency Identification (RFID). The RFID technologies are getting considerable attentions not only academic research but also the applications of enterprise. One of most important issues of applications is the indoor position location. Many researchers have used varied technologies to perform the tracking of indoor position location. In this paper, we will purpose a new method using RFID tags to perform indoor position location tracking, too. This method uses Received Signal Strength (RSS) to collect signal strength from reference tags beforehand. Next, signal strength is used to set up Power Level areas of ranges by reference tags. And then, using signal strength from reference tags to match signal strength by track tags. Finally, when track tags is set up into indoor environments, it will find out the position of neighboring reference tags, and using arithmetic mean to calculate the location values. A preliminary experiment proves that our method provides a better precision than LANDMRC system.

Keywords: RFID, indoor position location, RSS, Powel Level, location identification, LANDMRC

Title of the Paper: Design and Analysis of New Digital Modulation Classification Method


Authors: Anna Kubankova

Abstract: In this paper, a new method of digital modulation classification is described. The method was applied to signals with FSK, BPSK, MSK, QAM-16 and QPSK modulations. The spectrogram analysis was used for the modulation type recognition. This classification method was examined on signals corrupted by Gaussian noise, phase noise and on signals after their transmission through multipath Rayleigh fading channel. The Matlab program is used for the analysis.

Keywords: Digital modulation, Classification, Spectrogram, Modulation recognition, noise, interference

Title of the Paper: Using Simulated Annealing Algorithm for Maximizing Social Utility in Dynamic Spectrum Management


Authors: Yu-Cheng Lin, Ming-Hua Lin, Hsin-Hsiung Huang, Lu-Yao Lee

Abstract: Thousands of equipments of the wireless local access network and the mobile devices are widely used and the demand of dynamic spectrum resources is significantly growing. How to maximize the social utility in modern technique becomes an important issue. In this paper, the simulated annealing based approach which dynamically allocates the power spectrum is proposed to enhance the system efficiency. The objective is to maximize the sum of individual Shannon utilities in a multi-user communication system. Experimental result shows that our approach obtains the acceptable result within an acceptable amount of run time for the larger test cases.

Keywords: Simulated annealing, Social utility maximization, Shannon utility, Dynamic spectrum management, Multi-user communication system, Power spectrum

Title of the Paper: Study on the Technology of Tracking Noise Jamming with Monopulse Radar and Analysis on its Tracking Errors


Authors: Yanhua Zhang, Zhongjie Zhang, Jian Wang

Abstract: Under self-protecting noise jamming, mono-pulse radar can track the target by tracking noise jamming because noise jamming comes from the same direction as echo of target. In order to reduce angular tracking error, a method of introducing pulse modulation circuit and adjusting the bandwidth of intermediate frequency amplifier and video amplifier is proposed based on the main causes of angular error. Simulation studies verifies its effectiveness. In order to solve the problem of arranging stations in direction-finding cross-location technology, a method of station distribution arrangement is put forward based on the principle analysis of direction finding location with two stations. The receiving angle range to achieve higher location accuracy and the distance between two stations to meet the range of receiving angle are chosen. At last the easier calculation method of location accuracy in passive tracking is given. The studies show that the proposed methods can effectively improve tracking accuracy in tracking noise jamming with mono-pulse.

Keywords: Noise jamming, Mono-pulse radar, Angular error, Cross-location, Arrangement, Tracking error

Title of the Paper: A Forwarding Station Integrated the Low Energy Adaptive Clustering Hierarchy in Ad-hoc Wireless Sensor Networks


Authors: Chao-Shui Lin, Ching-Mu Chen, Tung-Jung Chan, Tsair-Rong Chen

Abstract: An ad-hoc wireless sensor network is also called self-organized networking that wireless sensor nodes can automatically communicate for each other. Therefore, each sensor node is no need for the information such as location of each sensor. Similarly, it consumes much energy on the information exchanged of each sensor node in order to maintain the entire ad-hoc wireless sensor network alive. Therefore, there are totally three phases in this paper. First, the setup phase is that all sensor nodes are randomly deployed and the ad-hoc wireless sensor network is divided into many clusters in each round. Therefore, every cluster has only one cluster head. Second, each sensor node transmits its message to the cluster head where it belongs to and then the cluster head transmits the messages coming from sensor nodes and deliver it to forwarding station. Finally, the forwarding station forwards the integrated messages from all cluster heads back to the base station. However, it consumes less energy for all cluster heads to transmit directly back to the base station. Hence, the far away location of the base station usually consumes the cluster head much energy to transmit the message to the base station. With the proposed three-phase scheme, the ad-hoc wireless network lifetime can be extended very well. Also, the simulation results show the entire ad-hoc wireless network lifetime can be extended very well.

Keywords: Ad-hoc Wireless sensor networks, Network lifetime, Three-phase scheme, Forwarding station, Self-organized, Cluster

Title of the Paper: Successive Interference Cancellation for Optical CDMA Systems: Fundamental Principles


Authors: Tawfig Eltaif, Hossam M. H. Shalaby, Sahbudin Shaari, Mohammad M. N. Hamarsheh

Abstract: In this paper successive interference cancellation (SIC) based on optical code division multiple access (O-CDMA) systems has been investigated. SIC scheme refers to a family of low complexity multi-user detection (MUD) methods for direct sequence CDMA systems. Performance of optical CDMA system is influenced by multiple access interference (MAI) resulted from the overlapping between the users. This kind of noise is became a primary concern in optical CDMA systems. To overcome this problem, we applied successive interference cancellation technique to a spectral amplitude coding (SAC) system that uses modified quadratic congruence (MQC) codes as signature sequence codes, taking into account the effect of all major noise sources, such as phase-induced intensity noise (PIIN), shot noise, and thermal noises. Furthermore, in SIC scheme we have taken into account the impact of imperfect interference cancellation. The system is analyzed for two cases: same effective power for all the users and different effective power from each user. We have successfully shown that under ideal effective power the SIC/SAC optical CDMA systems have potential to suppress the intensity noise and mitigate multiple access interference. Hence, using SIC/SAC cancellation scheme, the system can accommodate much more number of users as compared to the one without cancellation. Further, under ideal power the system using SIC scheme with direct sequence encoding (SIC/DS) shows much lower BER performance as compared to the one without cancellation (i.e. conventional receiver) or to SIC/SAC cancellation scheme. Hence, much more number of users can be accommodated by SIC/DS receiver system. Furthermore, SIC/DS scheme still shows much lower BER performance as compared with SIC/SAC scheme under different effective power.

Keywords: Optical code division multiple access (O-CDMA); successive interference cancellation (SIC); spectral amplitude coding (SAC); multiple access interference (MAI); modified quadratic congruence (MQC)

Title of the Paper: Simulation and Applications of Nonlinear Fiber Bragg Gratings


Authors: Farzin Emami, Amir H. Jafari

Abstract: We have simulated the behaviors of nonlinear fiber Bragg gratings (FBGs). The generalized nonlinear equations governing these structures are solved by a method which uses a Fourier series procedure and a simple iterative method. All of the nonlinear effects are considered. Bragg soliton generation in intrinsic media and birefringence effects in FBGs are studied. We found that the first order dispersion can causes time shifting in the input pulse peak. It is shown that FBGs are proper for optical switching too. They can use in filters, nonlinear fiber optical applications, soliton propagations etc.

Keywords: Nonlinear Fiber Bragg gratings, Modulation intensity, Solitons, Birefringence, Optical switches, Simulation

Title of the Paper: The First Millimeter-wave Point-to-Point Wireless Gigabit Ethernet Communication System at TMR&D


Authors: Azzemi Ariffin, Young Chul Lee, Mohd. Fadzil Amiruddin, Suhandi Bujang, Salizul Jaafar, Noor Aisyah Mohd. Akib

Abstract: In this paper, a millimeter-wave point-to-point (PTP) Wireless Gigabit Ethernet Communication System is presented and the first been developed by TMR&D. A 60 GHz Low Temperature Co-Fired Ceramics (LTCC) System-On-Package (SoP) Transceiver capable of gigabit data rate has been built and demonstrated with a size of 17.76 x 17.89 mm2. A direct Amplitude-Shift Keying (ASK) modulation and demodulation scheme is adopted for the 60GHz-band transceiver. A BER of 1?10-12 for data rate of 1.25 gigabit-per-second (Gbps) on 2.2 GHz bandwidth at 1.4 km was demonstrated. This paper reports a new PTP link that has been installed at TMR&D site to demonstrate wireless gigabit operation and performance of its key components. The link will operate at the 57.65-63.35 GHz band incorporating TMR&D’s designed millimeter-wave LTCC SoP RF Transceiver module. This LTCC SoP RF Transceiver is suitable for short-range wireless networking systems, security camera TV, video conferencing, streaming video like HDTV (high definition television) and wireless downloading systems for small power application. Outdoor wireless link test shows that the transmission range of PTP system using the SoP Transceiver is 1.4 km.

Keywords: PTP link, Wireless gigabit, LTCC, SoP, RF Transceiver

Title of the Paper: Social Networks and Job Satisfaction of Nurses


Authors: Hsieh-Hua Yang, Yi-Horng Lai, Wan-Ching Chao, Shu-Fen Chen, Mei-Hua Wang

Abstract: The research examines the relationship between propensity to connect with others, social networks and job satisfaction. Social networks serve as a social resource which affects job satisfaction through the provision of supportiveness. The characteristics of nursing are life-related and emotion-consumed job. It is argued that both advice and friendship networks are important in a work setting. The research team developed a questionnaire and administered during an on-job training of the nurses. To derive the participants’ advice and friendship networks, they were asked to list the names whom they consulted when they needed to know something about work and whom they considered to be their friends. Job satisfaction and the propensity to connect with others were also measured. The results showed that propensity to make acquaintance and outdegree were correlated with job satisfaction. Most of all, the advice and friendship networks were partially overlapped. It was concluded that the human resource professional shoud care about both formal and informal relationships.

Keywords: Social networks, nurses, propensity to connect with others, job satisfaction, advice network, friendship network

Title of the Paper: WiMAX Integration in NGN Network, Architecture, Protocols and Services


Authors: Arianit Maraj, Ilir Imeri

Abstract: With growing demands for fast provision of new and complex services, imposed by life and business dynamic in general, service providers are forced to adopt open technologies and advanced business models in their solutions. These enable a fast response to market demands and maximum utilization of the network. A big challenge for operators today is how to deliver broadband services in rural areas. Today, the broadband services in urban areas are served by DSL and cable modems. However, it is too difficult and very expensive for operators to deploy wired network in rural areas. BWA technology can overcome this problem. Today, the most popular BWA technology is WiMAX (commonly referred as IEEE 802.16), which supports fixed, nomadic, portable, and mobile operations. WiMAX is based on IP network. As a result, many operators around the world are interested to integrate WiMAX in existing networks to facilitate the move to an all IP.

Keywords: Integration, WiMAX technology, NGN network, protocols, security

Title of the Paper: Optimal Combining, Partial Cancellation, and Channel Estimation and Correlation in DS-CDMA Systems Employing the Generalized Detector


Authors: Vyacheslav Tuzlukov

Abstract: The symbol-error rate (SER) of a quadrature subbranch hybrid selection/maximal-ratio combining scheme for 1-D modulations in Rayleigh fading under employment of the generalized detector (GD), which is constructed based on the generalized approach to signal processing in noise, is investigated. At the GD, N dive-rsity branches are split into 2N in-phase and quadrature subbranches. Traditional hybrid selection/maximal-ratio combining is then applied over 2N subbranches. M-ary pulse amplitude modulation, including coherent bi-nary phase-shift keying (BPSK), with quadrature subbranch hybrid selection/maximal-ratio combining is investigat-ed. The SER performance of the GD under quadrature subbranch hybrid selection/maximal-ratio combining and hybrid selection/maximal-ratio combining schemes are investigated and compared with the conventional hybrid selection/maximal-ratio combining receivers. The obtained results show that the GD with quadrature su-bbranch hybrid selection/maximal-ratio combining and hybrid selection/maximal-ratio combining schemes out-perform the traditional hybrid selection/maximal-ratio combining receiver. Procedure of selecting the partial cancellation factor for the first stage of a hard-decision partial parallel interference cancellation of the GD emp-loying in direct-sequence code-division multiple access (DS-CDMA) systems is proposed. A range of the opti-mal partial cancellation factor, where the lower and upper boundary values can be explicitly calculated from the processing gain and the number of users of the DS-CDMA system, is derived based on the Price’s theorem. Co-mputer simulation results confirmed that, using the average of these two boundary values as the partial cancell-ation factor for the first stage, we are able to reach the bit error rate (BER) performance that is very close to the potentially achieved BER performance using the GD and surpasses the BER performance of the real partial ca-ncellation factor for DS-CDMA systems discussed in literature. Channel estimation errors have to be taken into account under analysis of receiver in order to the system performance will be not degraded under practical cha-nnel estimation. In this paper, we propose the GD, which takes the estimation error of maximum likelihood (ML) multiple-input multiple-output (MIMO) channel estimation and receiver spatially correlation into account in computation of the minimum mean square error (MMSE) GD and log-likelihood ratio (LLR) of each coded bit. Comparative analysis and simulation results show that the proposed MMSE GD can obtain sizable perform-ance gain and outperforms the existing soft-output MMSE vertical Bell Lab Space Time (V-BLAST) detector and its modification versions.

Keywords: Generalized detector, Diversity combining, Symbol error rate, Fading channel, Hybrid selection/ maximal-ratio combining, Partial cancellation factor

Title of the Paper: RFID Encryption/Decryption Technology Aided Multimedia and Data Intellectual Property Protection


Authors: Ming-Shen Jian, Ta-Yuan Chou, Shu Hui Hsu

Abstract: In this paper, a RFID Encryption/Decryption Technology Aided Multimedia and Data Intellectual Property Protection is proposed. The encryption code for each multimedia or data is embedded in the existing encryption algorithm. Furthermore, the unique ID of RFID tag can guarantee the legality of each RFID tag. Two types of RFID tag is implemented for multimedia/digital content and normal user. The encryption code is recorded and locked in the data slot of RFID tag which embedded in the digital content storage hardware. Only normal user provides the corect RFID tag with legal key for unlocking thedata slot, he encryption code can be gained. The verification shows the proposed technology is realistic and only users who have the legal RFID tag can gain the digital multimedia content.

Keywords: RFID, Multimedia, Intellectual Property, Digital Label, System Integration

Issue 8, Volume 8, August 2009

Title of the Paper: Extended Kalman Filtering and Phase Detector Modeling for a Digital Phase-Locked Loop


Authors: Tsai-Sheng Kao, Sheng-Chih Chen, Yuan-Chang Chang, Sheng-Yun Hou, Chang-Jung Juan

Abstract: The realization of a digital phase-locked loop (DPLL) requires to choose a suitable phase detector and to design an appropriate loop filter; these tasks are commonly nontrivial in most applications. In this paper, the phase detector is examined, and a simple model is given to describe the characteristics of the timing function. The DPLL system is then formulated as a state estimation problem; then an extended Kalman filter (EKF) is applied to realize this DPLL for estimating the sampling phase. Therefore, the phase detector and loop filter are simply realized by the EKF. The proposed DPLL has a simple structure and low realization complexity. Computer simulations for a conventional DPLL system are given to compare with those for the proposed timing recovery system. Simulation results indicate that the proposed realization can estimate the input phase rapidly without causing a large jittering.

Keywords: Digital phase-locked loop (DPLL), phase detector, state estimation, extended Kalman filter (EKF)

Title of the Paper: Multiband Antenna for Low-Frequency Radio Telescope


Authors: Radial Anwar, Norbahiah Misran, Mohammad Tariqul Islam, Geri Gopir

Abstract: Radio astronomical instrumentation has become a fascinating field of research in astronomy. In this paper, a design of multiband novel antenna for low-frequency radio telescope is proposed. The multiband has been achieved by combining V-shape half-wavelength dipole, traps and parasitic elements. The low return loss, multiband and maximum gain within the zenith direction is provided by V-shape half-wavelength dipole, traps and parasitic elements respectively. The study showed return loss of about -20 dB, -17 dB and -13.6 dB for three different frequencies with maximum achievable gain of about 10.28 dBi. Measurement result shows that the proposed antenna can work properly and meet well to be used in a transient radio telescope which is operated in the urban centers.

Keywords: Radio Telescope, V-shape Antenna, Trap, Parasitic Element

Title of the Paper: Inter-Channel Interference Cancellation in Wireless Mesh Network


Authors: Wadhah Al-Mandhari, Nobuo Nakajima

Abstract: Interference is one of the challenges that limit the performance of Wireless Mesh Networks (WMN). It became a major issue with new devises being equipped with more than one radio interface. This research emphasizes on impact of interference in multi-hop/ multi-radio WMN’s throughput as a result of utilizing dual radios in WMN’s station. Various laboratory experiments in this research indicates that the IEEE802.11 noninterfering channels for the 2.4GHz band still exhibit some level of interference. Furthermore, we proposed an interference cancellation circuit that showed a noticeable throughput enhancement in our experiments. This validates the proposed solution for interference suppression and throughput enhancement.

Keywords: Wireless Mesh Network (WMN), Access point (AP), Netperf, Signal to Interference Ratio (SIR), Non-overlapping channels, UDP throughput

Title of the Paper: GIS Supporting the Plan of BTS (Base Transceiver Stations) for Mobile Network in Urban Context


Authors: Vincenzo Barrile, Giuseppe Armocida, Giuliana Bilotta

Abstract: In recent years the technological development in general and the spread on the territory of antennas for mobile phones urged a state of widespread public concern repeatedly verging the social alarm. The need for a greater territorial coverage of mobile telephone service, due to the continuous request of users and to the presence of more operators in the market, led an intensification of the installations that not only made to a progressive decrease the power radiated from individual installations, it also required that they be placed closer to homes with consequent concern of the population for their own health. It is known that for assessing the levels of electromagnetic field in a particular place or around a given source (thus assessing the potential risk for the population nearby living) should be campaigns to measure or apply the theoretical methods (analytical or numerical). The Municipality of Reggio Calabria in 2006 started a project having as its main purpose the development of a GIS (Geographic Information System), capable of "storing" the results of measurement campaigns and also to apply a theoretical model for developing scenarios of exposure to electromagnetic field. The aim is to assess whether the presence of fixed installations for cellular phone is compatible with the health of citizens, or if the values of exposure to electromagnetic fields produced by them are within the limits set by law. This was achieved through the implementation of a Geographical Information System able to manage, store, process all data (both alphanumeric that geographical) relating to devices GSM, GPRS, UMTS with also the possibility to update the database (Technical data characteristics antennas) and insert new installations. In addition to the management, GIS is able to calculate the electromagnetic field produced by the antennas. The SIT is therefore the final collector, performing in a single "container" the stacking phase and the monitoring of electromagnetic radiation (in operational band of GSM, GPRS, UMTS), and finally support the phases related to the remediation of areas with anomalous values of the electromagnetic field, thus supporting the planning phase of the distribution of antennas in urban context.

Keywords: Electromagnetic fields – Base Transceiver Stations – Mobile Communications – Model for calculating EF – Geographical Information Systems

Title of the Paper: Study Cases on eLearning Technologies Used by Universities in Romania and Worldwide


Authors: Iasmina Ermalai, Diana Andone, Radu Vasiu

Abstract: eLearning is a term broadly used to describe the process of learning with the use of informational technologies and tools, usually through a web page. Nowadays it is hard to speak about eLearning without implicitly including an eLearning management system and new informational technologies. A learning management system (LMS or LCMS) is used to deliver educational material and manage interaction between students and tutors. LMSs can be open source, commercial or developed in-house by the universities. Tools like audio/ video conferencing, streaming, podcasting, social software, RSS feeds, can be incorporated into the LMS or can be subsequently added to the learning system as individual modules. This present paper seeks to establish the current state of eLearning technologies, both worldwide as well as in Romania.

Keywords: LMS, CMS, LCMS, VLE, eLearning, informational technologies, podcasting, RSS

Title of the Paper: A Local Information Based Protocol for Networks Data Exchange with Application to Mobile Sensor Networks


Authors: Paolo Di Giamberardino, Ivano Bergamaschi, Andrea Usai

Abstract: The paper presents a new protocol for multi hop data transmission between nodes in a mobile sensor network. The only requirement for the network is to be connected. The routing is handled locally on the basis of informations contained in the data transmitted. Global (time dependent) routing table as well as knowledge on the position of the nodes are not required, since the protocol itself contains an Hand-Shake phase for the neighbour detection. This allow to have high mobility for the nodes and, moreover, it is dynamically reconfigurable once the number of the nodes varies. A innovative data structure called “the Postman Bag” is introduced to spread data collected by sensor quickly and simply. Some considerations about the computational complexity and the performances of the proposed approach are reported on the basis of some simulations and some initial tests on small dimension networks.

Keywords: Mobile sensor network, Data transmission, Protocol, Wireless communications, Local management, Dynamic reconfiguration

Title of the Paper: A Compositional Technique for Hand Posture Recognition: New Results


Authors: Georgiana Simion, Vasile Gui, Marius Otesteanu

Abstract: New results obtain with the compositional technique for hand posture recognition is presented. Compositional methods are a powerful approach in image understanding. Most papers using this concept address image categorization problems. We recently propose a hand pose recognition method using the compositional approach. In this paper we present further development of our method and new results.

Keywords: Compositional technique, hand posture recognition, sparse, clustering

Title of the Paper: Dimensioning Rules Regarding Radio Resources in GSM/GPRS Networks


Authors: Cornel Balint, Georgeta Budura, Adrian Budura, Eugen Marza

Abstract: Many works have studied traffic modeling in GSM/GPRS networks trying to establish different performance parameters needed for dimensioning purposes. An important element of these networks is the radio resources. Sharing resources between different users and different services is a key concept of radio resources dimensioning in GSM/GPRS networks. In this paper we focus on the problem of performance evaluation in GSM/GPRS networks. We consider different resources allocation strategies such as: CP (Complete Partitioning) and PP (Partial Partitioning) and we study the influence of different operational details concerning TS (time-slots) assignment: FR (full rate), HR (half rate) and packing. Finally, we establish dimensioning rules based on traffic evaluation and quality of service level for GSM/GPRS users. For voice users the quality of service is given by the blocking probability calculated according to the proposed packing rule and for GPRS users the individual throughput and the blocking probability represent the performance parameters. We consider also the preemption probability of voice over data users.

Keywords: GSM/GPRS, modeling, Erlang-B law, packing, blocking probability, Engset law, throughput

Title of the Paper: Traffic Models and Associated Parameters in GSM/(E)GPRS Networks


Authors: Georgeta Budura, Cornel Balint, Adrian Budura, Eugen Marza

Abstract: GSM/(E)GPRS networks support a mixture of traffic consisting of voice and data. A key concept of dimensioning radio resources in such networks is represented by sharing resources between different users and different services. In this paper we address the problem of voice and data traffic models according to different resources allocations strategies: CP (Complete Partitioning) and PP( Partial Partitioning) and define specific parameters in each case. The proposed traffic model depend in each case on the resources allocation strategy: for voice traffic it is based on both cases, CP and PP, on Erlang law meanwhile for data traffic we build different models depending the scheme used for resources allocation. For CP scheme we propose two models: the model based on Erlang law and those based on modified Engset law. For PP scheme we also proposed two models: one is based on the bi-dimensional Markov chain and the other on the modified Engset law. Both consider voice-data interaction according to the PP scheme. In all cases we define specific performance parameters. We also implement the studied models and evaluate the proposed performance parameters. Finally we compare the results in order to find the adequate model to use for dimensioning purposes.

Keywords: GSM/(E)GPRS, blocking and preemption probability, Erlang-B law, Engset law, average throughput, cell utilization

Title of the Paper: Design of Switched Multiband Filters for IEEE 802.11a/b/g WLANs


Authors: S. Raghavan, Sion. P

Abstract: Switched Multiband Microstrip bandpass filters for IEEE 802.11a/b/g WLANs are presented. Cross coupled square open loop resonator type of filter is used as the basic design. These filters were selected since there was a tuning parameter available in the structure which changed the center frequency without change in performance. Two MEMS reconfigurable filter structures are proposed. Static simulations for each position of the MEMS switches were performed for S11 and S12 to observe the bandwidth and insertion loss of the filter. The simulations were performed on IE3D 10.06.

Keywords: WLAN, MEMS, ISM, UNII, Microstrip Filter

Title of the Paper: Microstrip Patch Antenna for a Retinal Prosthesis and RF MEMS Technology


Authors: S. Raghavan, G. Anantha Kumar

Abstract: This paper is about the investigation of a novel approach for establishing a data telemetry link in a dual-unit retinal prosthesis at microwave frequencies (1.4GHz and 2.35GHz) using a pair of Microstrip patch antennas. Approximately sized extraocular (25 mm x 25 mm) and intraocular (6 mm x 6 mm) antennas are simulated using IE3D and compared with reference experimental results which was designed and fabricated using the Finite Difference Time Domain Method. Simulation results show frequency shift in the resonant frequency by changing the capacitor height from 2 μm to 1 μm. However, the major drawback of this configuration is as Microstrip antenna is loaded with radial stub, which makes the structure is not suitable for loading with large number of capacitors. Because the dimensions of the radial stub determine the separation between the MEMS capacitors. Hence, the overall dimensions of the structure grow as more MEMS capacitors are used for loading, which is a problematic issue in terms of fabrication.

Keywords: Epiretinal, Subretinal, Telemetry link, Retinal Prosthesis

Title of the Paper: Design of Planar Inverted -F Antenna for Wireless Applications


Authors: S. Raghavan, N. Jayanthi

Abstract: The design of single feed dual band PIFA operating at 2.25and 3.546 GHz is presented. Two dimensional method of moments (MOM) electromagnetic simulator, IE3D version: 12, is used in the design simulation of this dual band antenna. The results exhibit a proper operation of the antenna in terms of return loss, bandwidth, efficiency, gain at both bands.ISM,Bluetooth,Wi-max, IEEE 802.11b, 802.11g, 802.11n, 802.16e, WiFi, Wi-max are the most important applications within the above mentioned frequency bands. Simulation tool, based on the method of moments (ZELAND IE3D version 12.0) has been used to analyze and optimize the antenna. The measured and simulated results are presented and all are acceptable to the standard antennas.

Keywords: ISM, Bluetooth, Wi-max, PIFA, Method of Moments, NLOS, WiFi

Title of the Paper: Fusion of Technology in Analysis, Design and Comparison of Numerical Techniques for Rectangular Microstrip Patch Antenna


Authors: S. Raghavan, T. Shanmuganantham

Abstract: In today’s scenario higher integration and smaller layout size are the two major trends in RF and Microwave industry, lead to more prominent role in electromagnetic high order effects. Recent years the important in the development of numerical techniques has been the versatility of the method. In this paper, we have present the various numerical techniques to compute such effects in Microwave Integrated Circuit based designs, highlighting their specific features with comparison of numerical techniques for design of rectangular Microstrip Patch Antenna. Here we are compared few numerical techniques, in this Finite Element Method is a more powerful and versatile, more storage requirement, less CPU time. Numerical characterizations and modelings of guided wave passive components have been an important research topic in the recent years. This is due to increased research and development in millimeter-wave integrated circuits and monolithic integrated circuits. Another aspect important in the development of numerical techniques has been the versatility of the method. Higher integration and smaller layout size, two major trends in today’s RF/microwave industry, lead to more prominent electromagnetic high order effects. In this paper, the authors present a survey of existing Numerical techniques to compute such effects in microwave integrated circuits, highlighting their specific advantages/disadvantages and comparison for a circuit designers and simulation results also compared.

Keywords: Microwave Integrated Circuits, Numerical Techniques, Artificial Neural Networks

Title of the Paper: Study on MIMO Schemes for 3G-LTE Downlink


Authors: Guocai Li, Yaohuan Gong

Abstract: The combination of MIMO and OFDM becomes a key standardization work for the downlink channel in 3G Long-Term Evolution (3G-LTE). This paper studies one of the core techniques of 3G-LTE downlink: the coding and decoding schemes in a time-variable multipath environment. It discusses the MIMO schemes for 3G-LTE downlink, the STBC/SFBC, SFTC/STTC and Group layered SFC coding-decoding schemes. This paper also discusses channel estimation scheme based on pilot symbol assistance (PSA), including the pilot pattern and the channel tracking algorithms. The computation complexity, frequency efficiency, BER performance and the effects of channel estimation are analyzed under multi-path fading channel environments. Then we give computer simulation results for the coding-decoding schemes. We believe that results will provide beneficial information to design the 3G-LTE downlink channels.

Keywords: 3G long-term Evolution(3G-LTE), MIMO-OFDM- STBC/SFBC, SFTC/STTC, Group layered SFC

Title of the Paper: A Burst Assembly Method to Reduce End-To-End Delay in Optical Burst Switching Networks


Authors: Yukinobu Fukushima, Wenjie Chen, Yasuyuki Fujiwara, Tokumi Yokohira

Abstract: Although the offset-time-based scheme can differentiate loss rates of packets according to their QoS levels in optical burst switching networks, it also increases end-to-end delay of packets with higher QoS level. This is because it increases offset time of bursts in proportional to QoS levels of packets which are included in the bursts. In this paper, we propose a burst assembly method that reduces end-to-end delay. Our proposed method includes packets that arrive during the offset time into the currently assembled bursts while the conventional method includes them into the burst assembled next time. Simulation results show that our method offers 12–23% delay reduction for packets with the highest QoS level.

Keywords: Optical Burst Switching (OBS), Offset-time-based scheme, end-to-end delay, burst assembly method

Title of the Paper: The Role of Branch-Correlation for an MC-CDMA System Combining with Coherent Diversity over Frequency Selective Channels


Authors: Ta-Sheng Lan, Joy Iong-Zong Chen, Chieh Wen Liou, I. Mai Huang

Abstract: The diversity schemes include EGC (equal gain combining) and MRC (maximal ratio combining) diversity combining with an MC-CDMA (multi-carrier coded-division multiple-access) system operating in the cases of either correlated or uncorrelated frequency selective fading channels are invested in this paper. The sum of Nakagami-m variates (envelope intensity) is applied for deriving the closed-form solution with arbitrarily correlated channels which is for the purpose of avoiding the difficulty of explicitly calculating the pdf (probability density function), for example, looking for the CF (characteristic function), for the SNR (signal-to-noise ratio) at the output of MRC or EGC scheme . Moreover, an alternative method utilized to obtain the jpdf (joint pdf) with arbitrary correlation coefficient in terms of the generalized Laguerre polynomial is adopted for the derivative. The analytical results of the new derived BER (bit error rate) formulas are validated by an example of the intensive Monte Carlo computer work in which consider a dual correlated branch MC-CDMA system with several assumed system parameters. It obviously shows that the well consideration and elimination the impact of correlation between fading channels for MRC or EGC diversity scheme will obtain the better system performance for an MC-CDMA system working in the environment with frequency selective fading.

Keywords: Correlated frequency selective channels, EGC diversity, Nakagami-m fading, MC-CDMA system, MRC diversity

Title of the Paper: The Performance Analysis of an Multi-carrier System with Correlated-and Uncorrelated-Nakagami-m Statistics


Authors: Joy Iong-Zong Chen, Kai-Chih Chuang, Ta-Sheng Lan

Abstract: In this letter the system performance of error rate probability closed-form for an multi-carrier spread-spectrum, e. g., coded-division multiple-access (MC-CDMA) system with linear diversity operating in frequency selective fading channels are evaluated. The sum of correlated-Nakagami-m and uncorrelated-Nakagami-m variates are adopted to derive the closed-form solution with arbitrarily correlated channels which is for the purpose of avoiding the difficulty of explicitly calculating the probability density function (pdf), for instance, to search the characteristic functions (CF) of the signal-to-noise ratio (SNR) at the MRC or EGC output. The analytical results of the new derived bit error rate (BER) formulas are validated by an example of the intensive Monte Carlo computer work in which consider a dual correlated branch MC-CDMA system with some of assumed system parameters.

Keywords: Characteristic functions, frequency selective fading, MC-CDMA system, linear diversity, correlated-Nakagami-m fading

Title of the Paper: Design and Analysis of a Novel Dielectric Loaded Helical Antenna


Authors: A. A. M Ezanuddin, P. J. Soh, A. A. H Azremi, R. B. Ahmad

Abstract: Helical antennas have been a popular antenna configuration for various applications for its simple structure. This work describes the study on a novel, custom-shaped dielectric loaded helical antenna incorporated on an advanced material, which is Barium Strontium Titanate (BST). This material, which presents the researcher with an advantage in size reduction due to its high relative permittivity, is most suitably used when desiring a miniaturized antenna compared to its conventional design of the same type. In the process of designing, a parametric study was carried out by varying the antenna geometrical parameters and the dielectric loading using the transient solver. The detailed understanding of the sensitive parameters of the proposed antenna will allow for ease of design reuse. Finally, an extended exploration was also carried out in order to determine the design’s suitability for operation with two of the WLAN Access Points (APs) already available in the market. Observation from this investigation found out that the three most sensitive parameters in the design are dielectric load’s height, radius of ground plane and the helical height, with the dielectric load’s height as the main design criteria. On the other hand, examination on the APs’ integration found out that several factors influencing the radiation performance of the design are the material used, internal spacing available and overall shape of the APs. While both APs are proven to work with the designed antenna in the desired frequency range, a degradation of up to 1 dB in gain have been observed, when applying the antenna to the less suitable AP.

Keywords: Helical antenna, dielectric resonator, wireless local area network, advanced material, Barium Strontium Titanate (BST)

Title of the Paper: LMS Algorithm with an Adaptive Neural Network Cost Function


Authors: Jeng-Kuang Hwang, Yuan-Ping Li

Abstract: We propose a new LMS algorithm with an adaptive neural network cost function (ANNCFLMS) for application to unknown channel estimation or system identification. The algorithm employs the weighted average of a neural network with two input signals—the squared errors at adjacent time intervals—to modify the cost function and update the respective weight according to a gradient descent algorithm designed to track the minimum mean squared error (MSE). For fast convergence, the step-size updates recursively until the modified cost function attains its minimum value. Simulation results demonstrate that the proposed algorithm converges faster and is especially robust in low-SNR or colored input environments.

Keywords: Adaptive filters, neural network, least mean square (LMS), variable step-size, channel estimation

Title of the Paper: An Efficient MIMO Detection Algorithm Employed in Imperfect Noise Estimation


Authors: Chien-Hung Pan

Abstract: An efficient multiple-input multiple-output (MIMO) detection (MD) algorithm includes novel, low-complexity, near-optimal and robust scheme is proposed in wireless communications when imperfect noise estimation is considered. By using MIMO technique, capacity increases proportionally as the number of antennas is increased, but the introduced inter-antenna interference (IAI) degrades system performance. To better mitigate IAI, we propose a two-stage procedure to achieve maximum likelihood (ML) performance while keeping at acceptable level of computational complexity. A novel two-stage procedure is proposed as follows that is suitable for either in an overdetermined or an underdetermined MIMO system. In an overdetermined system, interference cancellation is first processed at Stage-1 using sorted QR decomposition (SQRD) followed by Stage-2 that performs a genetic algorithm (GA). In terms of computational complexity, this procedure provides three significant advantages: 1) The SQRD scheme provides excellent interference cancellation so as to largely improve initial setting of GA. 2) By using QRD, fitness value evaluation of GA involves less complexity due to reducing the matrix multiplication. 3) In aspect of diversity knowledge, lately decoded sub-streams expect to have lower error probabilities by using SQRD. In this paper, each mutated gene is decoded from the various diversity gains, termed as a diversity mutation (DM) scheme. To achieve the fore-mentioned three significant advantages in an underdetermined system, on the other hand, we propose zero forcing (ZF) assisted SQRD GA-MD (ZF-SQRD GA-MD) to achieve ML performance. Beside, the proposed two-stage detection procedure is quite robust as it does not rely on noise information. Simulation results show that the proposed two-stage detection procedure can achieve a near-ML performance, but at a low-complexity level.

Keywords: Multiple-input multiple-output, inter-antenna interference, maximum likelihood detector, sorted QR decomposition, genetic algorithm, underdetermined

Title of the Paper: Complexity Reduction by Using Triangular Matrix Multiplication in Computing Capacity for an Optimal Transmission


Authors: Chien-Hung Pan

Abstract: Multiple-input-multiple-output (MIMO) technique is often employed to increase capacity in comparing to systems with single antenna. However, the computational complexity in evaluating channel capacity or transmission rate (data rate) grows proportionally to the number of employed antennas at both ends of the wireless link. Recently, the QR decomposition (QRD) based detection schemes have emerged as a low-complexity solution. After conducting QRD on a full channel matrix that results in a triangular matrix, we claim that computational complexity can be simplified by the following ways. First, to simplify channel capacity calculation, we prove that eigenvalues of the full channel matrix multiplication equals eigenvalues of the triangular channel matrix multiplication. Second, to simply evaluate optimal transmission rate constrained constellation, we propose a simplified multiplication of the resulted simple triangular matrix and a transmitted signal vector. Then, we also propose a modified mutual information calculation (MMIC) to reduce the multiplication complexity in combinational multiplication processes via the divided calculation. This divided calculation is employed in the parallel architecture for the field-programmable gate array (FPGA) implementation. That is, the number of multiplications can be reduced via increasing the number of additions in the FPGA implementation. By using the computer and FPGA implementation, simulation results show that the proposed QRD-based schemes are capable of achieving conventional performance, but at a low-complexity level.

Keywords: Multiple-input multiple-output, channel capacity, QR decomposition, eigenvalues, mutual information, field-programmable gate array

Title of the Paper: An Improved Location-Aided Routing Protocol for Mobile Ad Hoc Networks with Greedy Approach


Authors: Neng-Chung Wang, Yung-Fa Huang, Jong-Shin Chen, Si-Ming Wang, Chin-Ling Chen

Abstract: A mobile ad hoc network (MANET) is a dynamically reconfigurable wireless network that does not have a fixed infrastructure. Due to the high mobility of nodes, the network topology of MANETs always changes. This makes it more difficult to find the routes that message packets use when they are routed. In this paper, we propose an efficient greedy location-aided routing (GLAR) scheme to improve the efficiency of location-aided routing (LAR) scheme for MANETs. In this scheme, we first decide a baseline, which is the line between the source node and the destination node, for route discovery. The request packet is broadcasted in a request zone based on the baseline to determine the next broadcasting node. The neighboring node with the shortest distance to the baseline is chosen as the next broadcasting node. We also propose a partial reconstruction process that maintains a routing path. When a node on a routing path finds that a link is broken, the node starts the process of routing maintenance. Simulation results show that the proposed GLAR can reduce the control overhead and increase the route lifetime than LAR.

Keywords: Expected zone, Global positioning system, Location-aided routing, Mobile ad hoc networks, Request zone

Issue 9, Volume 8, September 2009

Title of the Paper: Energy-Aware Secure Routing for Large Wireless Sensor Networks


Authors: Theodore Zahariadis, Helen C. Leligou, Stamatis Voliotis, Sotiris Maniatis, Panagiotis Trakadas, Panagiotis Karkazis

Abstract: Wireless Sensor Networks (WSN) are vulnerable to a wide set of attacks which threaten the network operation. Although communication and security technologies for computer networks have reached a mature stage, their applicability in WSNs is disputable due to their infrastructure-less operation and the limited node and network resources. Focusing on the routing procedure, this relies in the cooperation among neighboring nodes and a long list of attacks that can cause serious damage have already been identified. The situation is futher aggravated as the next generation wireless sensor network will be larger and larger. To face this problem, we propose a secure routing protocol (Ambient Trust Sensor Routing, ATSR) which adopts the geographical routing principle to cope with the network dimensions and part of the routing attacks, while it relies on a distributed trust model for the detection of another part of the routing attacks. Both direct and indirect trust information is taken into account to evaluate the trustworthiness of each neighbour. An important feature of the proposed routing solution is that it takes into account the remaining energy of each neighbour, thus allowing for better load balancing and network lifetime extension. Based on computer simulation results we evaluate the additional energy consumption caused by the exchange of indirect trust information and the benefits stemming from the adoption of our algorithm.

Keywords: Wireless Sensor Networks, routing, security, trust model, energy awareness

Title of the Paper: The Performance of Macrodiversity System in the Presence of Long-Term and Short-Term Fading


Authors: Caslav Stefanovic, Dragana Krstic, Ana Pesic, Mihajlo Stefanovic, Dejan Petkovic

Abstract: Probability density function (PDF), moments of signal and amount of fading (AF) at the output of macrodiversity system in closed form are obtained. Moreover, level crossing rate (LCR) of signal at output of macro diversity system is analytically derived and used to study average fade duration (AFD) of the proposed system. Dual maximal-ratio combining (MRC) is implemented at the micro level (single base station) and selection combining (SC) with two base stations (dual diversity) is implemented at the macro level. This model assumes a Nakagami-m density function for the envelope of the received signal and a gamma distribution to model the average power to account for the shadowing. The results are shown graphically for different signal and fading parameters values.

Keywords: Shadowing, Nakagami-m Fading, Microdiversity, Macrodiversity, Probability Density Function, Amount of Fading

Title of the Paper: Analyze of the MPEG-4 Compressed Streams


Authors: Iulian Udroiu, Ioan Tache, Corneliu Salisteanu, Ion Caciula

Abstract: In this paper, an analysis of video quality of compressed MPEG-4 stream is performed. The video quality is performed using a test system composed by two metering devices: TEKTRONIX PQA500 Picture Quality Analyzer and TEKTRONIX MTS4EA Elementary Stream Analyzer. The measured parameters of compressed MPEG-4 signal are: macro block measurements and PSNR.

Keywords: Video quality signal, macro block measurements, MPEG-4, PSNR, DMOS

Title of the Paper: QoS Management in Experimental Environment


Authors: Drago Zagar, Goran Martinovic, Slavko Rupcic

Abstract: New applications usually combine interactivity and multimedia resulting in a huge diversity of possible services. The negotiated quality of service should be result of application/user requirements and network possibilities. The most important topic in QoS provision is how to efficiently manage network resources. This paper describes an experimental implementation of the QoS network management for serving the users by some defined QoS characteristics. The applications developed for negotiation and maintenance of the desired quality of service between the server and clients are analyzed. The main classes of developed applications as well as the connections between applications/ objects are described. Finally, some results describing functionality of QoS management in experimental environment are shown.

Keywords: Quality of Service, negotiation, network resources, IP networks, QoS Management, QoS Parameters

Title of the Paper: An Image Encryption using Pseudo Random Bit Generator based on a Non-Linear Dynamic Chaotic System


Authors: Algimantas Citavicius, Audrius Jonavicius

Abstract: This paper deals with the image encryption scheme based on non-linear dynamic chaotic system in stream cipher architecture. The narrowing of the numbers domain interval to [0.2, 0.8] and a double precision floating point format to encode float numbers to binary format were used for pseudo random stream generator. The results of the NIST statistical test suite and security analysis are given. The results show very good cryptographic properties and high security.

Keywords: Image encryption, Non-linear chaotic dynamic system, Stream generator, Security analysis, Cryptography

Title of the Paper: Analysis and Design of Applicator System for Regional Induction Heating 2.45 GHz


Authors: Chumpon Patummakasorn, Chanchai Thongsopa

Abstract: In this paper, the design of applicator system for regional induction heating at 2.45 GHz and using noninvasive method. The distribution of the lossy medium was analyzed using the finite difference time domain method(FDTD). The objective is to determine the area which the heat is uniformly distributed. The result from this paper was believed to be effectively when it was applied to the cancer treatment. The applicator utilized was the inducting spiral coils which were sets of two coils and four coils, and each coil has its own power-supply unit. It was fabricated by using magnetron sources operating at frequency of 2.45 GHz. The energy supplied to the induction coil was timely controlled. The results from the simulation and experimental of heating area from lossy medium were compared. Both simulation and experimental results showed good no conflict. The activation of supply units one at a time generated more heating wide area than the one when all units were activated at the same time. The results showed that the applicator with four coils generates more heating wide area than the one with two coils. Another interesting point is that the activation each power supply unit was turned on one by one generates more heating wide area than the activation all power supply units were turned on. In this study, both two coils and four coils were capable of producing a temperature rise of 7 Celsius degrees for 10 min. Moreover, the results from this investigation can be applied to various designs of heating wide area applicator and another advantage is its cost effectiveness.

Keywords: Applicator, Hyperthermia, Induction heating, lossy medium, finite difference time domain, agar phantom

Title of the Paper: Analytical Description of a Parameter-based Optimization of the Quality of Service for VoIP Communications


Authors: Leopoldo Estrada, Deni Torres, Homero Toral

Abstract: In this work, the perceived quality of VoIP communications is studied. The distributions of the number of consecutive received and lost packets, respectively named gap and burst, of a VoIP communication are modeled with discrete two-state and four-state Markov chains. Algorithms for estimating the transition probabilities between states and from these, the packet loss rate and the respective gap and burst length distributions, are described. Through a study of monitored VoIP calls, it is shown that these models can adequately represent the geometric-type decay of these distributions and that although two-state model performs well for homogeneous losses, for non-homogeneous losses the four-state model fits better. An analysis of the performance of a packet-level FEC scheme, based on ??-packet redundancy, is presented. The perceived packet loss rate that results of applying this correction scheme is quantified. For the studied measurements, 1-packet redundancy is sufficient to decrease the perceived loss rate below 1%. Also, the impairments of the perceived quality of voice after the FEC technique and a de-jitter buffer is quantified. The resulting equations can be used to optimize the adjust parameters of the VoIP call, e.g., level of redundancy, type of codec used and de-jitter buffer size. The proposed methodology can be extended if other types of improvements are included.

Keywords: VoIP, Packet loss distribution, Packet reception distribution, ??-packet FEC, QoS

Issue 10, Volume 8, October 2009

Title of the Paper: Simulation and Modeling of Packet Loss on VoIP Traffic: A Power-Law Model


Authors: Homero Toral, Deni Torres, Leopoldo Estrada

Abstract: In this paper, through an extensive analysis it is shown that VoIP traffic jitter exhibits self-similar and heavy-tail characteristics. From this analysis, we observed that α-stable distribution particularly gives the best goodness of fit; this fact has implications on the design of de-jitter buffer size. On the other hand, we investigate the packet loss effects on the VoIP jitter, and present a methodology for simulating packet loss on VoIP jitter traces. In order to represent the packet loss process, the two state Markov model or Gilbert model is used. We proposed two new models for VoIP traffic; these models are based on voice traffic measurements, and allow relating the Hurst parameter and α parameter with the packet loss rate. We found that the relationship between these parameters and packet loss rate obeys a power-law function with three fitted parameters.

Keywords: VoIP, QoS, Packet Loss Rate, Jitter, Heavy-Tail Distributions, Self-Similar, α Parameter, Hurst Parameter, De-Jitter Buffer, Two-State Markov Model

Title of the Paper: A Diachronic Study of POP Album Cover from 1980 to 1992 in Taiwan


Authors: Manlai You, Li-Min Chen

Abstract: Based on the color attributes of pop album cover, a diachronic study was conducted. It was argued that the denotation is significant related to the color attributes and the connotation is not necessary significant related to the color attributes. The population of this study was those pop albums published from 1980 to 1989. In those years, this country was gradual opening up of political and economic stability. The sampled representative pop album covers were collected and put on the computer screen for conducting content analysis. The denotation and color attributes of each sampled album cover were also identified for statistical test. A logit regression was used to predict denotation of pop album cover from mean value of color channel Red, Green, and Black. The C5.0 model was used to build a rule set and a decision tree for further illustrate the relation between color attribute and denotation.

Keywords: POP album cover, diachronic study, color attribute, denotation

Title of the Paper: An Efficient Direct Anonymous Attestation Scheme with Forward Security


Authors: Deng-Guo Feng, Jing Xu, Xiao-Feng Chen

Abstract: Direct Anonymous Attestation (DAA) is a cryptographic mechanism adopted by the Trusted Computing Group in its specifications for trusted computing platforms (TCP). In this paper, we propose a new DAA scheme and prove it is secure under the strong RSA assumption and the decisional Diffie-Hellman assumption. While satisfying all the security properties proposed in previous DAA schemes, our scheme provides a new desired security property, forward security: compromise of the current private key of TPM does not enable an adversary to forge signatures pertaining to the past. Such forward security is important to mitigate the damage caused by private key exposure.

Keywords: Trusted computing platform, Direct anonymous attestation, Forward security, Trusted platform module

Title of the Paper: M-MENTOR: A Design Algorithm for IP Networks with Mixed Traffic


Authors: Annop Monsakul, Pisit Charnkeitkong

Abstract: The design of IP networks to support traffic engineering for both unicast and multicast traffic is a very difficult problem. This paper proposes a heuristic design algorithm called M-MENTOR that concern routing of both types of traffic. However, since multicast traffic model could be employed in many situations and could be managed by various kinds of multicast routing protocols, this paper consider only the design process of the IP networks with following features: (1) network of within the same Autonomous System (AS), (2) routing protocol support multiple weight on each link, (3) the multicast traffic from different sources share the same multicast tree. The efficiency of M-MENTOR is evaluated for various traffic demands and networks of 10, 30 and 50 node and compared with MENTOR-II. The experimental results show that, in almost all cases, M-MENTOR give better performance in term of installation cost.

Keywords: IP Network Design, MENTOR Algorithm, Unicast/Multicast Traffic, Traffic Engineering

Title of the Paper: Performance Evaluation Model of Optimization Methods for Wireless Sensor Networks


Authors: Goran Martinovic, Josip Balen, Drago Zagar

Abstract: Wireless sensor networks are often composed of large number of wireless sensor nodes that are mostly using battery supplies. Nodes are small and equipped with sensors that cooperatively monitor physical world. Communication, sensing and computing have the most influence on performance and power consumption of wireless sensor networks. Various optimization methods are used to decrease power consumption and improve performance of wireless sensor networks. One of the novel methods is cross-layer approach. In this paper, first we present the advantages of cross-layer approach. The articles that are using a cross-layer approach for improving performance and energy preservation in wireless sensor networks are reviewed and state of the art is presented. In their work, scientists propose various optimization methods that are improving performance and decreasing power consumption. One of the fundamental problems is how to systematically make the performance evaluation and get the real contribution of these proposed optimization methods. In this paper, we develop benchmark methodology and performance evaluation model of various optimization methods for wireless sensor networks. Furthermore, we present the benchmark application for collecting and comparing performance measurement results of various optimization methods.

Keywords: Benchmark Application, Benchmark Methodology, Cross-Layer, Metrics, Performance Evaluation Model, Wireless Sensor Networks

Title of the Paper: Efficient Key Management Scheme for Hierarchical Access Control in Mobile Agents


Authors: Hsing-Bai Chena, Chun-Wei Liaob, Chang-Kuo Yehc

Abstract: Mobile agents have great potential for increasing the realized benefit for a variety of e-commerce applications. However, enabling the mobile agent to safely travel over the open and uncontrollable Internet is necessary to protect the contents of a mobile agent. Recently, many agent structures that manage the keys needed to provide the access control mechanism for mobile agents have been developed. Nevertheless, these structures require either large amount of mobile codes or heavy computation loads. In this paper, a lightweight key management method for hierarchical access control in mobile agent environments is proposed. This method not only provides access control for mobile agents but also reduces the agent size as well as cuts down the computations cost.

Keywords: Access control, Information security, Key management, Mobile agent

Title of the Paper: Modern Communications used New Formulation to the Proporation of Laplace Transforms


Authors: Igried Dib Al-Khawaldeh

Abstract: Laplace transforms was introduced long time ago, it had explained better afterward, and had many Engineering applications like (control, signals, circuits, etc.), unfortunately it still has a lot of ambiguity and is difficult to be understood by the beginners. In this paper the transformation laws are re-formulated in a brief and unforgettable form, and then a conclusion has been reached for the first time that the transformation laws are symmetric.

Keywords: Congestion Control, Signals, Transformation

Issue 11, Volume 8, November 2009

Title of the Paper: High Range Resolution Synthesized by Non-linear Stepped-Frequency Chirp Pulse Train


Authors: Yingrui Hu, Xuegang Wang

Abstract: Traditional stepped frequency chirp pulse train methods suffer from high sidelobes and ambiguous peaks, known as grating lobes and difficulty in compensating Doppler effect caused by target motion. This paper investigates a class of non-linear stepped frequency chirp pulse train with low sidelobes and capability to cancel clutter and to compensate motion. We present analytic expression for its autocorrelation function (ACF) and propose an improved method to produce the non-linear stepped frequency chirp pulse train with small grating lobes and small overlap ratio for sub-pulse of large time bandwidth product. A method for estimation a target’s radial velocity is developed, which avoids multiple bursts required by other methods. The high signal-to-noise (SNR) ratio as a result of sub-pulse compression assures the accuracy of estimation. The Cramer-Rao bound for lower limit on the velocity estimation of the pulse train is derived to demonstrate its performance.

Keywords: Non-linear stepped-frequency chirp pulse train, Autocorrelation function, Grating lobes suppression, Motion compensation, Cramer-Rao bound, One-dimensional range profile

Title of the Paper: An Efficient Zone-Based Multicast Routing Protocol for Ad Hoc Network


Authors: Tain-Sao Chang, Jyh-Horng Wen, Tzu-Ting Wu

Abstract: This study presents a forwarding nodes selection scheme for zone-based multicast routing protocols to reduce transmission routing control overhead. The feasibility of the proposed scheme is demonstrated over mobile ad hoc networks (MANETs), and compared with the multicast zone routing protocol (MZR) in terms of the routing control overhead and packet delivery ratio. In this work, the proposed scheme represents a good reduction of forwarding packets. Furthermore, simulation results show that the proposed scheme presents effective forwarding nodes selection for reduction routing control overhead and increasing packet delivery ratio.

Keywords: Forwarding node selection, multicast routing, mobile ad hoc network, multicast zone routing protocol, routing control overhead, packet delivery ratio

Title of the Paper: Certificateless Authenticated Group Key Agreement Protocol for Unbalanced Wireless Mobile Networks


Authors: Chung-Fu Lu, Tzong-Chen Wu, Chien-Lung Hsu

Abstract: In 2004, Bresson et al. proposed a mutual authentication and group key agreement protocol for unbalanced wireless networks. Tseng recently proposed a novel secure protocol to improve Bresson et al.’s protocol. However, both protocols are based on certificate-based public key systems and insecure against the so-called impersonation attacks. They might be unsuitable for unbalanced wireless mobile networks from the viewpoints of security, computational complexities, and communication overheads. This paper proposes a certificateless authenticated group key agreement (cAGKA) protocol based on elliptic curve discrete logarithms. The proposed cAGKA protocol is more secure and efficient than previously proposed protocols for unbalanced wireless mobile networks due to the following facts: (i) The entity authentication and the authenticity of the intended public keys can be simultaneously verified in a logically single step without requiring any public key certificates. (ii) Bit sizes of the keys and the related messages are relatively smaller than those of the previously proposed protocols for the same security level. (iii) It saves the required communication overheads, and computational complexities. (iv) It achieves mutual authentication, impersonation attack resistance, explicit key confirmation, forward secrecy, contributory key agreement, and group key updating.

Keywords: Group key agreement, Certificateless, Elliptic curve, Unbalanced wireless networks, implicitly-certified

Title of the Paper: QPPS : Qos Provision Packet Scheduling Algorithm in High Speed Downlink Packet Access


Authors: Ying-Hong Wang, Kuo-Feng Huang

Abstract: The 3rd Generation WCDMA standard has been enhanced to offer significantly increased performance for packet data. But coming application such as multimedia on desiring data rates will urge the UMTS support. To support such high data rates, High Speed Downlink Packet Access (HSDPA) labeled as 3.5G wireless system, has been published in UMTS Release 5. Under the HSDPA system, it will have to support high speed transmission and promises a peak data rate of up to 10Mb/s. To achieve such high speed rate, system provides the information of Channel Quality Indicator (CQI) information to detect the air interface condition. Then, there are many channel condition related scheduling schemes have been proposed to attend achievement of high system performance and guarantee the quality-of-service (QoS) requirements. However, there is no solution of packet scheduling algorithm can consider differences of data-types priority management under the hybrid automatic repeat (HARQ) scenario. In this paper, we propose the weight combination packet scheduling algorithm to target to enhance the system efficiency and balance QoS requirements. The proposed schemes is simulated with OPNET simulator and compared with the Max CIR and PF algorithms in fast fading channel. Simulation result shows that the proposed algorithm can both increase the cell throughput effectively and meet user’s satisfaction base on QoS requirements.

Keywords: HSDPA, UMTS, Scheduling, QOS

Title of the Paper: An Interference Suppression Scheme for MIMO-OSTBC System


Authors: Jie Wang, Zhonghao Zhang, Yuehuan Gong, Tao Liu

Abstract: Multiple Input Multiple Output (MIMO) technique is considered as a cost-effective and promising technique for the next generation wireless system. Orthogonal Space-Time Block Codes (OSTBC) scheme is one of the most important coding schemes for MIMO system. The performance of an MIMO system using OSTBC (MIMO-OSTBC), however, degrades significantly in presence of strong interferences. In this paper, an interference suppression scheme for MIMO-OSTBC system in strong interference scenario is presented. The proposed scheme is based on simplified Maximum Likelihood (ML) decoding and noise subspace projection. The scheme has the following advantages: realizing ML decoding of the OSTBC and greatly reducing searching calculations by simple linear processing; avoiding matrix-inversion computation needed in ordinary suppression schemes through noise subspace projection. The paper also discusses the method of obtaining the efficient channel state information (CSI) needed in the proposed scheme in strong interference scenario. Simulation results are given to verify the interference suppression ability of the proposed scheme and our theoretical analysis. Compared with other suppression scheme, the proposed scheme has better SER performance and is more flexible in practical applications.

Keywords: MIMO, OSTBC, ML Decoding, Interference Suppression, Noise Subspace Projection

Issue 12, Volume 8, December 2009

Title of the Paper: Network Coding: An Excellent Approach for Overloaded Communication Era


Authors: Marium Jalal Chaudhry, Farhat Saleemi, Fatima Jalal Chaudhry

Abstract: Data flow in graphs is one of the most principle challenges faced by computer scientists and mathematicians. The problem of data flow in a graph has many practical applications e.g. routing in internet and wireless networks, where major purpose is to provide quality of service guarantees improved throughput, delay reduction etc. we will be using novel technique of network coding to device strategy to achieve theoretically maximum possible data flow in a network. Network is a new paradigm which in contrast to traditional routing allows mixing of data elements. This paper will present the developed algorithms of network coding, their performance analysis, simulation results and gains in terms of quality of service. Our results will particularly focus on improving throughput and reducing number of retransmissions, better network management by using network coding approach, we also show our experimental setup and experimental results which naturally graph up the network coding in this overloaded era.

Keywords: Wired Network Coding, Routing, Gain

Title of the Paper: Performance of Blind Successive Interference Canceller for Multi-Carrier CDMA Systems


Authors: P. A. Haris, E. Gopinathan, C. K. Ali

Abstract: An efficient multiple user access over the wireless channel necessitates a communication system design that can overcome the adverse impact of multipath propagation such as Inter Symbol Interference (ISI) and Multiple Access Interference (MAI). This being the objective, a Multi Carrier Code Division Multiple Access (MC-CDMA) communication system is considered in this paper. MC-CDMA, being a combination of DS-CDMA and OFDM converts a frequency selective fading channel into multiple flat fading channels thereby mitigating ISI. To overcome the effect of MAI, Multi User Detection (MUD) based receiver is addressed. The performances of Blind successive Interference Cancellation (BIC) techniques are compared with Matched filter receiver and BMMSE receiver by simulating the entire system. The BIC is a multi-user detection technique that uses knowledge of only the desired user's signature sequence and his timing to estimate his information. This is done by executing interference cancellation in a successive manner, starting from the most dominant component and successively canceling the weaker ones. Simulation results show that BIC scheme outperforms conventional MF receiver and BMMSE receiver.

Keywords: Inter symbol interference, Multiple Access interference, Multi user detection, Single user lower bound, Maximum mean energy

Title of the Paper: The Effect of an Enhanced Channel Assignment Algorithm on an IEEE 802.11 WLAN


Authors: Mohamad Haidar, Hussain Al-Rizzo, Robert Akl, Zouhair El-Bazzal

Abstract: In this paper, a channel-assignment algorithm at the Access Points (APs) of a Wireless Local Area Network (WLAN) is proposed in order to maximize Signal-to-Interference Ratio (SIR) at the user level. We start with an initial channel assignment based on minimizing the total interference between APs. Based on this assignment, we calculate the SIR for each user. Then, another channel assignment is performed based on maximizing the SIR at the users. The algorithm can be applied to any WLAN, irrespective of the users’ and load distributions. Simulation results showed that the proposed algorithm is capable of significantly increasing the SIR over the WLAN, which in turn improves throughput. Finally, several scenarios were constructed using OPNET simulation tool to validate our results.

Keywords: Signal-to-Interference Ratio, WLAN, Channel Assignment, Access Points, OPNET

Title of the Paper: Tag Anti-Collision Algorithms in RFID Systems - A New Trend


Authors: Majid Alotaibi, Adam Postula, Marius Portmann

Abstract: RFID is a wireless communication technology that provides automatic identification or tracking and data collection from any tagged object. Due to the shared communication channel between the reader and the tags during the identification process in RFID systems, many tags may communicate with the reader at the same time, which causes collisions. The problem of tag collision has to be addressed to have fast multiple tag identification process. There are two main approaches to the tag collision problem: ALOHA based algorithms and tree based algorithms. Although these methods reduce the collision and solve the problem to some extent, they are not fast and efficient enough in real applications. A new trend emerged recently which takes the advantages of both ALOHA and tree based approaches. This paper describes the process and performance of the tag anti-collision algorithms of the tree-ALOHA trend.

Keywords: RFID, Collision, Frame, Algorithm, Aloha, Tree, Tag

Title of the Paper: Characterization of Advanced Round Robin Scheduler


Authors: Tamas Marosits, Sandor Molnar

Abstract: In this paper we show that Advanced Round Robin (ARR) scheduler is in the class of Latency Rate servers and it also belongs to the class of Guaranteed Rate servers. We present the latency parameter and the error term of ARR. Next, we evaluate the fairness characteristic. Finally, we describe the relationship between ARR and Generalized Processor Sharing. All of these results can make the comparison of ARR easily to other known schedulers and help designers to apply ARR.

Keywords: Round Robin scheduling, Latency Rate servers, GPS, fairness

Title of the Paper: Software Defined Adaptive Codec for Cognitive Radio


Authors: Rajeshree D. Raut, Kishore D. Kulat

Abstract: Recently, Cognitive Radio has been proposed as a promising technology to improve spectrum utilization. A highly flexible SDR (Software defined Radio) system needs to configure each of its blocks to give optimum performance over the available bandwidth. Present work discusses an approach for software defined adaptive coder yielding minimum BER (Bit error rate) for emergency services over cognitive radio. The results verify the efficiency of the algorithm which configures the convolution encoder to produce a lower BER for increased Bandwidth available. This can be readily implemented in the SDR library functions. This has been tested by FPGA implementation of the convolution encoder using Matlab HDL coder. The coder output of the FPGA implemented VHDL code has also been presented. Various WiMax Systems to be included in the SDR Library are puttforth. SDR adapts to the best suitable design, yielding lower BER in available channel conditions.

Keywords: Cognitive Radio, SDR library, Rate Adaptive Coder, BER, FPGA implementation

Title of the Paper: Performance Measurement and Queueing Analysis at Medium-High Blocking Probability of Parallel Connection Servers with Identical Service Rates


Authors: Chung-Ping Chen, Ying-Wen Bai

Abstract: In this paper we propose a performance measurement and queueing analysis for medium-high blocking probability where the service rate is less than equal to the arrival rate of parallel connection servers, and for which we can estimate the system response time. First, we calculate the system response time of the parallel network. Second, we simulate the queueing model of the parallel network and calculate the system response time. Third, we measure the system response time by using different numbers of ASP multiplication loops to represent the different service rates of the parallel network. Fourth, we take 30,000 data for imitation as the foundation and use linear regression to compare the measurements of both the system response time and the search service rates of the actual system under different service load conditions. Fifth, we compare the system response time of a single server with up to ten parallel connection servers and compute the discrepancy in their efficiency.

Keywords: Parallel Network, Web Servers, Service Rate, Parallel Connection Servers, Queueing Anallysis

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