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Issue 1, Volume 9, January
2010
Title
of the Paper:
On the Minimum Number of Users for the Generation of H-ss Traffic in a
Simulation Scenario
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Authors:
Candelaria Sansores Perez, Luis Rizo Dominguez, Julio Cesar Ramirez Pacheco
Abstract: Several simulation and measurement studies have reported the
well-known network traffic self-similarity and long-range dependency and the
consequences for network performance. In the context of simulation, however,
the impact of the number of sources has not been sufficiently emphasized for
the generation of synthetic selfsimilar traffic. In this paper we describe a
simulation scenario suitable for the testing of performance issues under
self-similar traffic. Our analysis was centered on the effect of traffic
aggregation over the self-similarity degree, determining the necessary number
of sources to approach the verified relation H = (3 ? min )/2. Besides, we
highlighted the performance of several Hurst parameters estimators for this
type of simulation scenarios, identifying the most suited ones.
Keywords: Self-similar traffic, Heavy-tail distributions, Performance evaluation,
Simulation
Title
of the Paper:
Problem of Assignment Cells to Switches in a Cellular Mobile Network via Beam
Search Method
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Authors:
Cassilda Maria Ribeiro, Anibal Tavares Azevedo, Rodolfo Florence Teixeira Jr.
Abstract: The problem of assigning cells to switches in a cellular mobile
network is an NP-hard optimization problem. So, real size mobile networks
could not be solved by using exact methods. The alternative is the use of the
heuristic methods, because they allow us to find a good quality solution in a
quite satisfactory computational time. This paper proposes a Beam Search
method to solve the problem of assignment cell in cellular mobile networks.
Some modifications in this algorithm are also presented, which allows its
parallel application. Computational results obtained from several tests
confirm the effectiveness of this approach to provide good solutions for
medium- and large-sized cellular mobile network
Keywords: Combinatorial Optimization. Assignment problem. Beam Search Method.
Cellular Network
Title
of the Paper:
The Performance Analysis of MRC Combiner Output Signal in the Presence of
Weibull Fading and Shadowing
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Authors:
Petar Nikolic, Dragana Krstic, Zoran Popovic, Dusan Stefanovic, Mihajlo
Stefanovic
Abstract: The performance of dual diversity systems in the presence of Weibull
and shadowing over two uncorrelated branches will be presented in this paper.
The performance measures of fading communication systems such as probability
density function (PDF) of signal to noise ratio (SNR), Amount of fading (AF),
and Outage probability (Pout) will be calculated and graphically represented
for Maximal Ratio Combining. The results will be shown graphically for
different signal and fading parameters values. They will be compared with
respect to the kind of shadowing which is with log-normal or Gamma
distribution.
Keywords: Weibull fading, Log-normal fading, Gamma fading, Maximal Ratio
Combining, Amount of fading, Outage probabilty
Title
of the Paper:
A Survey on MPEG-4 Standard and Digital Television Deployment
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Authors:
Zoran Bojkovic, Bojan Bakmaz
Abstract: MPEG-4 standard has been developed to support a wide range of
multimedia applications. It provides users a new level of interaction with
visual contents, including techniques to view, access and manipulate objects
rather than pixels with great error robustness at a wide range of bitrates.
The object-based representation paradigm make MPEG-4 a standard that may find
application from low bitrate personal mobile communications to high quality
studio production. One topic common to most applications is the need for
supporting interactivity with different kind of data. A prime example is the
introduction of Digital TV (DTV) instead of analog with obvious direct benefit
such as improved quality and reliability. DTV delivers interference and
distortion free audio and video signals, while achieving much higher spectrum
efficiency than analog television. Agreements for the DTV transition are being
implemented with different emphasis in various countries, depending on network
and station arrangements, government regulations, and market conditions. DTV
increasingly impacts broadcasters, consumers and many related industries. The
DTV systems that are now available worldwide, not only deliver crystal-clear
picture, and high quality sound, but they also provide various innovative new
services and programs, such as electronic program guide, personalized
advertisements, control, IP encapsulation, data broadcasting various
interactive services. High Definition (HD) programming requires installation
of completely new production and distribution equipment and systems. This is a
major capital investment for a broadcaster. This work seeks to provide an
overview of the influence of MPEG-4 standard on DTV from a perspective in
Europe. The first part deals with some practical elements of the MPEG-4
standard. The focuses are on the set of technologies together with visual
bitstream. The second part describes DTV development including Digital Video
Broadcasting (DVB) activities and achievements as well as high definition
system origination for DTV. Finally, the third part describes control and
encoding for DTV including the corresponding services.
Keywords: Coding, DTV, DVB, H.264/AVC, HDTV, MPEG-4 standard
Title
of the Paper:
Optimal Placement of Base Stations in a Two Tiered Wireless Sensor Network
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Authors:
B. Paul, M. A. Matin, M. J. Showkat, Z. Rahman
Abstract: The optimal placement of base stations in a two tiered wireless
sensor network (WSN) can reduce the energy consumption of sensor nodes (SN)
and thus can improve network lifetime. In our paper, we address the base
station location problem and provide a geometrical solution introducing a new
concept called node partitioning technique. An algorithm based on the
geometrical approach is also provided in the paper.
Keywords: Wireless sensor network, Minimum enclosing circle, Node partitioning,
Base station, Cluster, Geometry
Title
of the Paper:
E-learning: Analysis of Online Discussion Forums in Promoting Knowledge
Construction through Collaborative Learning
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Authors:
Nor Fariza Mohd. Nor, Norizan Abdul Razak, Jamaluddin Aziz
Abstract: Extensive discussions and debates about the advantages of using
technology to create a shared space among learning participants have been
presented in studies in the field of e-learning. One of the approaches in
using or adopting technology for learning is through the use of online
discussion forums, which as reported has beneficial impact on the teaching and
learning process. Online discussion forum is also a form of learning through
networking which provide opportunities for students to seek, obtain, and share
information. Therefore, students’ participation and interaction in the forum
can provide some insight into how they learn about a course in a virtual
environment. In addition, it is also essential to consider how online
discussion forums may promote knowledge constructions in students.This study
examines preliminary data of an online discussion forum in a course at Masters
level (MA) in order to investigate if there is evidence of shared construction
of knowledge among students through collaborative learning behaviours. The
findings indicate that the students actively processed and reviewed the
postings in the online discussion forums. They also relate their postings to
what they have learned in the lectures, besides providing links to relevant
websites for further reading. Therefore, there is evidence that the students
worked collaboratively in order to respond to the postings based on the topics
presented during the lecture and tutorial. Finally, analysis of the students’
discourses indicate various phases of knowledge construction (based on the IAM
model), which is a reflection of their cognitive thinking process.
Keywords: E-learning, content analysis, online forum discussion, knowledge
construction, collaborative learning, asynchronous communication
Title
of the Paper:
A Design Rule for Inset-fed Rectangular Microstrip Patch Antenna
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Authors:
M. A. Matin, A. I. Sayeed
Abstract: In our paper, an inset-fed microstrip patch antenna has been
designed and the dependency of resonant frequency on the notch gap and the
feed line geometry has been studied. Our study suggests that a narrower notch
resulted in better impedance matching. A design rule has also been formulated
and presented the performance of the proposed design.
Keywords: Inset-fed, microstrip antenna
Issue 2, Volume 9,
February 2010
Title
of the Paper:
E-Management for Administrative Efficiency in Higher Education through
Participatory Decision-Making
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Authors:
Fatimah Hashim, Gazi Mahabubul Alam, Saedah Siraj
Abstract: Though many organizations have developed their own approaches in
ensuring reliable decision making processes, not many have used technology to
ensure effective participatory based decision making. This paper presents a
model that incorporates reliable participatory based decision making practices
and quality management indicators through strategic use of technology - an
initiative of a faculty in a higher institution of learning. The model, called
QuESt (Quality E-management System), integrates web-based technologies into an
interconnected system to enable decision making by all stakeholders at multi
levels of responsibility. Discussion in this paper is first focused on the
bureaucracy and participatory models of decision making, then moves on to the
research context, description of QuESt and discussion of the features and
functions of the system. The paper concludes with an assessment of the
potentialities of the system in taking an organisation’s internal and external
processes to the next level – using technology to ensure evidence based
decision making, to interconnect staff roles and responsibilities and to use
feedback to take appropriate action. Implications are drawn for knowledge
advancement, policy making and practice.
Keywords: Participatory based decision making; E-management; accountability;
efficiency, internal and external processes
Title
of the Paper:
Developing a Denotation Model from Luminance of Album Cover from 1980 to 1992
in Taiwan
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Authors:
Manlai You, Li-Min Chen
Abstract: Based on the luminance attribute of pop album cover, a diachronic
study was conducted. It was argued that the denotation is significant related
to the luminance attribute. 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 luminance attribute of each sampled album cover
were also identified for statistical test. The relation between luminance and
color was verified by applying regression technique. It was concluded that
luminance could be predict 100 percent by the values of RGB colors. A logit
regression was used to predict denotation of pop album cover from mean value
of luminance and standard deviation of luminance. The C5.0 model was used to
build a rule set and a decision tree for further illustrate the relation
between luminance attribute and denotation.
Keywords: POP album cover, diachronic study, luminance attribute, denotation
Title
of the Paper:
Important Aspects of Using Geographical Information System
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Authors:
Marius-Constantin Popescu, Nikos Mastorakis
Abstract: This first part of the paper presents a short introduction in GIS
technology and its application domains. The second part includes a
classification of the GIS products, future research possibilities and a short
presentation of equipments for data acquisition. Part three contains a list of
the most attractive GIS projects undertaken in the world and in Romania.
Keywords: GIS, Areas to apply, Satellites
Title
of the Paper:
Comparative SAR Assessment in Adults and Children Exposed to Electromagnetic
Fields of Radio Frequency Devices
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Authors:
Mimoza Ibrani, Luan Ahma, Enver Hamiti
Abstract: Exposure to radio frequency electromagnetic fields has raised
scientific and public concern regarding possible adverse effects to people
exposed to such radiation. At cellular mobile communication frequencies, the
most important parameter used to assess human exposure to electromagnetic
fields is SAR (Specific Absorption Rate). This paper will firstly address two
exposure scenarios related to adult exposure to GSM electromagnetic fields :
Human exposure to 900 MHz GSM base station electromagnetic fields, whereby
with EMR-300 is measured field strength on different points located meters
away from base station antenna. Using SAR prediction formula we have
calculated induced SAR values for people located near base station antenna.
The obtained results are compared with maximum permissible levels and basic
restrictions of international safety standards. Human exposure to mobile phone
GSM electromagnetic fields, whereby with a software (FDTD code) have simulated
human head exposure to mobile phone radiation and have calculated Spatial Peak
SAR over 1 g and 10 g of human body biological tissues. Secondly, in order to
investigate comparison of radio frequency energy absorption by head of
children and adults, the Spatial Peak SAR over 1g and 10g is calculated for:
uniformly down-scaled adult head with increased dielectrical parameters
compared to adult ones and uniformly down-scaled adult head with adult
dielectrial parameters. SAR results are presented graphically and tabulary
while comparative assessment is given in order to emphasize influence of head
size and change of dielectrical parameters on radio frequency energy
absorption by human tissues, and give possible answer whether children should
be treated as special group regarding radio frequency exposure. Even not an
all inclusive approach is considered, obtained results indicate that SAM may
be considered conservative for assessment of children exposure compliance to
radio frequency electromagnetic fields.
Keywords: Radio frequency, GSM, SAR, SAM, base station antenna, field strength,
mobile phone, child, dielectrical properties
Title
of the Paper:
Fast and Secure Handover Schemes Based on Proposed WiMAX over EPON Network
Security Architecture
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Authors:
Wen Gu, Stamatios V. Kartalopoulos, Pramode K. Verma
Abstract: In recent years, the integration of Worldwide Interoperability for
Microwave Access (WiMAX) and Ethernet Passive Optical Network (EPON) has
become one of the most promising broadband access solutions. The EPON network
provides tremendous bandwidth while the WiMAX network can support mobility.
Integration of PON and WiMAX combines the best of both technologies. However,
the integration requires advanced secure mechanisms to overcome
vulnerabilities of wireless mobile protocols. In this paper, we propose an
end-to-end network architecture based on WiMAX over EPON networks, and we
present a security framework that adopts the RSA protocol and the Extensible
Authentication Protocol (EAP). We introduce three handover scenarios in the
integrated network and propose the corresponding handover schemes. In the
proposed handover schemes, we utilize a pre-authentication method for the
authorization key (AK) pre-distribution, and we use the communication
framework of the ranging step to implement mutual authentication between the
subscriber and the mobile network. Through our analysis, we show that the
proposed handover mechanisms can simplify and accelerate the handover process
compared to the standard WiMAX handover scheme while keeping the handover
procedure secure.
Keywords: WiMAX over EPON, Handover Security, Pre-authentication, Ranging
Title
of the Paper:
Imaginary Relativity
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Authors:
Mehran Rezaei
Abstract: The main goal of this paper is to present a theory, named Imaginary
Relativity, which completes Einstein’s Relativity Theory. According to the
recommended theory in this paper, the speed of light is not constant and
absolute in an inertial frame. On the other hand, the speed of a light pulse
in an inertial frame, moving with velocity u, equals to an imaginary value
instead of the constant value c as it is considered in Einstein’s Relativity
Theory.
Keywords: Imaginary relativity, Lorentz transformations, Imaginary energy, Wave
particle duality, Space-time
Title
of the Paper:
Evaluating the Efficiency of Shortcut Span Protection
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Authors:
Sarah Ruepp, Lars Dittmann, Michael Berger, Thomas Stidsen
Abstract: This paper presents a comparison of various recovery methods in
terms of capacity efficiency with the underlying aim of reducing control plane
load. In particular, amethod where recovery requests are bundled towards the
destination (Shortcut Span Protection) is evaluated can compared against
traditional recovery methods. The optimization model is presented and our
simulation results show that Shortcut Span Protection uses more capacity than
the unbundled related methods, but this is compensated by easier control and
management of the recovery actions.
Keywords: Resilience, Linear Programming, Simulation, Networking, Control Plane
Issue 3, Volume 9,
March 2010
Title
of the Paper:
Towards 100 Gigabit Carrier Ethernet Transport Networks
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Authors:
A. Rasmussen, J. Zhang, H. Yu, R. Fu, S. Ruepp, H. Wessing, M. Berger
Abstract: Ethernet as a transport technology has, up to now, lacked the
features such as network layer architecture, customer separation and
manageability that carriers require for wide-scale deployment. However, with
the advent of PBB-TE and TMPLS, it is now possible to use Ethernet as a
transport technology, making the use of Ethernet as a convergence layer for
Next Generation Networks a distinct possibility. Triple Play services, in
particular IPTV, are expected to be a main drivers for carrier Ethernet,
however, a number of challenges must be addressed including QoS enabled
control plane, enhanced OAM functions, survivability and the increased
bandwidth requirements of carrier class systems. This article provides an
overview of PBB-TE and T-MPLS and demonstrates how IPTV services can be
realized in the framework of Carrier Ethernet. In addition we provide a case
study on performing bit error rate (BER) measurements on the aggregated 100G
stream.
Keywords: Carrier Ethernet, IPTV, T-MPLS, PBB-TE, NGN, BERT, 100G
Title
of the Paper:
Efficient Computational Information Geometric Analysis of Physically Allowed
Quantum Cloning Attacks for Quantum Key Distribution Protocols
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Authors:
Laszlo Gyongyosi, Sandor Imre
Abstract: In secret quantum communications the best eavesdropping attacks on
quantum cryptography are based on imperfect cloning machines. The incoherent
attack, based on quantum cloning, is the most common eavesdropping strategy.
Using a probe, the eavesdropper imperfectly clones the sender’s quantum state
which keeps one copy and sends the other. The physically allowed
transformations of Eve’s quantum cloner on Bob’s qubit can be described in
terms of Completely Positive (CP), trace preserving maps. The map of the
quantum cloner compresses the Bloch-ball, as an affine map. This affine map
has to be a complete positive, trace preserving map, which shrinks the Bloch
ball. The effects of a quantum cloner can be given in tetrahedron
representation. In this paper we show a new, quantum information theoretical
representation of eavesdropping detection, focused on the Four-state (BB84)
and Six-state quantum cryptography protocols. We use a fundamentally new
computational geometrical method to analyze the informational theoretical
impacts of cloning activity on the quantum channel. The proposed algorithm
uses Delaunay tessellation and convex hull calculation on the Bloch sphere,
with respect to quantum relative entropy as distance measure. The improved
core-set approach can be used to analyze efficiently the informational
theoretical impacts of physically allowed quantum cloning attacks.
Keywords: Quantum Cryptography, Quantum Cloning, Quantum Informational Distance
Title
of the Paper:
Routing Protocol Extension for Resilient GMPLS Multi-Domain Networks
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Authors:
Anna Manolova, Sarah Ruepp, Ricardo Romeral, Sergio Rodriguez
Abstract: This paper evaluates the performance of multi-domain networks under
the Generalized Multi-Protocol Label Switching control framework in case of a
single inter-domain link failure. We propose and evaluate a routing protocol
extension for the Border Gateway Protocol, which allows domains to obtain two
Autonomous System disjoint paths and use them efficiently under failure
conditions. Three main applications for the protocol extension are
illustrated: reducing traffic loss on existing connections by exploiting
pre-selected backup paths derived with our proposal, applying multi-domain
restoration as survivability mechanism in case of single link failure, and
employing proper failure notification mechanisms for routing of future
connection requests under routing protocol re-convergence. Via simulations we
illustrate the benefits of utilizing the proposed routing protocol extension
for networks employing different resilient mechanisms (both protection and
restoration), as well as for networks which have not employed any resiliency
technique. We show the need for differentiated failure handling for improving
network performance under failure situations. Furthermore, we draw parallel
between different network parameters and the efficiency of the applied
notification and survivability strategies in the network.
Keywords: Multi-domain, GMPLS, BGP, AS-disjoint, performance enhancement
Title
of the Paper:
Cooperative MIMO MAC Protocol using STTC in Wireless Sensor Networks
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Authors:
J. Vidhya, G. Kalpana, P. Dananjayan
Abstract: Sensor networks require robust and energy efficient communication
protocols to maximise the network lifetime. Radio irregularity, channel fading
and interference results in larger energy consumption and latency for packet
transmission over wireless channel. Cooperative transmission of data using
multi-input multi-output (MIMO) scheme is used to combat channel fading and
improve the communication performance of distributed wireless systems.
However, an inefficiently designed medium access control (MAC) protocol may
diminish the performance gains of MIMO operation. Hence this paper develops a
distributed MAC protocol for packet transmissions using fixed group size
cooperative MIMO utilising space time trellis code (STTC) to achieve high
energy savings and lesser delay. Further, to ensure the stability of
transmission queue at the sender, this paper also proposes a threshold based
MAC protocol for MIMO transmission. The protocol uses thresholding scheme that
updates dynamically the cooperative group size based on the queue length at
the sending node. The performance of the fixed group size MIMO MAC protocol
using STTC technique is evaluated for various orders of diversity in terms of
transmission error probability, energy consumption and delay. Simulation
results are also provided to evaluate the performance of threshold based MAC
protocol. Results show that 4X4 cooperative group size is dynamically selected
as the cooperative group size as it provides minimum energy and delay.
Cooperative transmission using STTC technique provides significant performance
improvement than uncoded scheme due to the exploitation of MIMO diversity
gain.
Keywords: Cooperative MIMO, diversity gain, energy efficiency, MAC, STTC,
thresholding scheme, wireless sensor network
Title
of the Paper:
An Advance Wireless Multimedia Communication Application: Mobile Telemedicine
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Authors:
Chin-Feng Lin
Abstract: In this paper, we describe mobile telemedicine, which is an
application in advanced wireless multimedia communication. Mobile telemedicine
is one of the advanced technologies of the 21st century. It can be used to
provide auxiliary medical service and has accordingly been used in emergency
situations, mobile hospitals, personal healthcare, and in rapidly alerting
doctors to patients’ disease, rehabilitation, etc. By exploiting the
advantages of wireless multimedia communication, such as current high utility,
convenience, high data transmission rates, high reliability, and wide
coverage, we have developed a range mobile telemedicine systems. Mobile
telemedicine technology is a wireless remote medical technology that
incorporates a combination of biomedical engineering, electrical engineering,
and computer science; the technology also includes various advanced medical
services. It is a technology unconstrained by the limitations of time and
space. Using this technology, family doctors can be more actively involved in
the daily lives of their patients. There is no doubt that in the future, we
will witness an era of ‘ubiquitous mobile telemedicine’. This technology is
expected to bring about revolutionary changes in the fields of medicine and
engineering. Such changes will be accompanied by ample opportunities for
business, scope for the early diagnosis of diseases, and improvements in
medical services. Moreover, manufacturers of clinical equipment are expected
to respond favourably to these developments. Advanced technologies of the 20th
century, such as the internet and mobile communication, have made human lives
considerably easier. The combination of these two technologies has given rise
to wireless multimedia networks, an extension of which is the mobile
telemedicine systems. We would like to emphasize that the R&D process of these
mobile telemedicine systems is similar to that of pharmaceuticals.
Keywords: Ubiquitous mobile telemedicine, advanced wireless multimedia
communication, emergency situations, mobile hospitals, personal healthcare,
patients’ disease, rehabilitation.
Title
of the Paper:
Secured Reactive Routing Protocol for Mobile Nodes in Sensor Networks
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Authors:
P. Samundiswary, P. Dananjayan
Abstract: Wireless sensor networks have drawn a lot of attention recently due
to their broad applications in both military and civilian operations. Sensor
nodes in the network are characterized by severely constrained energy
resources and communicational capabilities. Since, these nodes are frequently
established in a physically insecure environment, they are vulnerable to
different types of active attacks. These attacks can inject malicious packets
by compromising the node. Routing protocols are common target of these
compromised nodes. Secured reactive routing protocols have recently been
developed by using cryptographic algorithms against these attacks. However
these routing protocols entail a number of prerequisites during both network
establishment and operation phases .In contrast, trust based routing protocols
locate trusted routes rather secure routes in the network. In this paper, a
secure routing protocol named secured dynamic source routing protocol (S-DSR)
is implemented for mobile sensor networks by incorporating trust based
mechanism in the existing dynamic source routing protocol (DSR). Simulation
results prove that S-DSR outperforms the DSR by reducing the routing overhead
and improving the delivery ratio of the network.
Keywords: Wireless sensor networks, Malicious nodes, DSR protocol, Secured
dynamic source routing protocol, Trust Model, Sinkhole attack
Title
of the Paper:
An Implementation of Designing Media Streaming System for Live Broadcast
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Authors:
Hsieh-Hua Yang, Jui-Chen Yu, Yeong-Diann Wang, Hung-Jen Yang, Hsueh-Chih Lin,
Wei-Yuan Dzan
Abstract: In this study, we designed and constructed a live media streaming
system to broadcast important activities such as: graduation ceremonies, sport
games, and banquets. There are many different streaming systems and coding
formats. In this study, the selecting procedure would be conducted to find
suitable and stable technology for implementing live broadcast service, and
evaluate the feasibility of system. This article had three parts, including of
introductory the streaming technologies, designing and constructing the
streaming system and implemented the streaming system.
Keywords: Design, broadcast, live, streaming system, feasibility
Issue 4, Volume 9,
April 2010
Title
of the Paper:
Investigation of Foliage Effects via Remote Data Logging at 5.8 GHz
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Authors:
Pon Lai Ly, Phoon Lai Ly, Tharek Abd. Rahman, Mohammed Khomeini Abu
Abstract: This paper presents an unconventional methodology in examining the
extent of vegetation blockage effects imposed on near line-of-sight (NLOS)
fixed wireless links based on Institute of Electrical and Electronics
Engineers (IEEE) 802.11a Wireless Local Area Network (WLAN) standard operating
at frequency 5.8 GHz of Unlicensed National Information Infrastructure (UNII)
band. By employing the concept of remote data logging, power received
measurements were acquired constantly via a remote server for 24 hours and
seven days a week from three dissimilar NLOS links within the campus of
Universiti Teknologi Malaysia (UTM) in which it can best be described as
suburban environment. These point-to-point links deployed in conjunction with
wireless campus are impeded directly or indirectly by vegetation. The
behaviour of these site-specific links performance is studied. The average
excess path loss inclusive of foliage loss which is relevant to the climate of
a tropical country is derived. Comparison of tabulated results between these
divergent fixed wireless links besides exploratory data analysis is presented.
Keywords: Foliage, Path loss, Propagation, Fixed, Wireless, Near Line-of-sight
Title
of the Paper:
An Effective Cancellation Technique of Cochannel Interference Based on
Multiuser Detection Scheme for MFSK/FH-SSMA Systems
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Authors:
Jyh-Horng Wen, Chuan-Wang Chang, Sheng-Fong Lin
Abstract: The performance of a multilevel frequency shift keying/frequency
hopping-spread spectrum multiple access (MFSK/FH-SSMA) system over a cochannel
interference scenario is dependent on multiuser detection schemes. Many
investigations have demonstrated huge potential capacity and performance
improvement by using multiuser detection schemes. However, their schemes are
extremely complex while the total number of users is increased because the
multiuser interference becomes larger. In this paper, we propose a novel
multiuser detection scheme to reduce the complexity of decoding process. The
performance of the system with the proposed scheme over a nonfading channel is
simulated and compared with that of conventional and other multiuser
interference cancellers. Simulation results show that the proposed scheme
reduces the system complexity and improves the bit error rate (BER).
Keywords: Multilevel Frequency Shift Keying (MFSK), Frequency Hopping-Spread
Spectrum Multiple Access (FH-SSMA)
Title
of the Paper:
Design of a Free Electron Maser without Wiggler
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Authors:
Fareq Malek, James Lucas, Yi Huang
Abstract: We are developing prototype free electron maser (FEM) that is
compact, powerful and efficient for potential industrial applications. The
design, set-up and results of a novel X-band rectangular waveguide pre-bunched
free electron maser (PFEM) are presented in this paper. Our initial device
operates at 10 GHz, without wiggler and employs two rectangular waveguide
cavities (one for velocity modulation and the other for energy extraction).
The electron beam used in this experiment is produced by thermionic electron
gun which operates at 3 kV and up to 50 μA. The nominal beam diameter is 1mm
passing across the X-band cavity resonators. The resonant cavity consists of a
thin gap section of height 1.5mm which reduces the beam energy required for
beam wave interaction. The results, progress so far and the scope of work for
the next couple of months are reported.
Keywords: Pre-bunching, X-Band, Velocity modulation, Free Electron Maser,
Rectangular waveguide
Title
of the Paper:
A Carrier Fragmentation Aware CSMA/ID MAC Protocol for IP over WDM Ring
Networks
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Authors:
Jih-Hsin Ho
Abstract: In this paper, a packet pre-classification MAC protocol based on
Carrier Sense Multiple Access with Idle Detection (CSMA/ID) with carrier
fragmentation aware scheme has been investigated for completely transporting
IP packets over the all-optical WDM ring networks. In order to improve the
utilization of the network, the packets are first pre-classified into various
class queues of access point (AP) according their length. The downstream
access point recognizes the incomplete IP packet by the presence of the
sub-carrier signal and pulls it off the ring. The carrier-sense can check the
available channel length (ACL) to notify the transmission queues transmit the
packet. This protocol avoids packet collision and uses carrier fragmentation
when finding no appropriate ACL. An analytical model has had been developed to
evaluate the performance of the protocol, and the simulation results show good
network efficiency.
Keywords: CSMA/ID, Carrier fragmentation, Available channel length, Analytical
model and simulation
Title
of the Paper:
Study on Power and Rate Control Algorithm for Cognitive Wireless Networks
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Authors:
Qian Hu, Zhenzhou Tang
Abstract: Rate control and power control are two important issues in cognitive
radio networks. In this paper, three rate control strategies are first
introduced, namely Dirty Paper Coding (DPC) strategy, Noise strategy, and
Opportunistic Interference Cancellation (OIC) strategy. The achievable rates
of the three strategies are also compared. Then, optimal power control
algorithms are proposed, each corresponding to one rate control strategy. The
algorithms achieve the maximum transmit rate for the cognitive user by
appropriately controlling the transmit power on each subchannel under the
interference temperature constraint of the primary user. Simulation results
show that the proposed algorithms can dramatically improve the transmit rate
of cognitive user.
Keywords: Cognitive radio, Interference temperature, Power control, Rate control
Issue 5, Volume 9,
May 2010
Title
of the Paper:
A Secure and Efficient Protocol of Multiple Session Keys Generation
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Authors:
Chang-Kuo Yeh
Abstract: To negotiate a session key can benefit from the technique of the
public-key cryptography such as key exchange and digital signature. This key
cannot be used until the session is finished. In current model such as SSL, if
the sender desires to re-establish another new session with the same receiver,
the both sides, for security consideration, should repeat the same key
exchange and digital signature processes to generate a new session key.
Apparently, the two processes must lower the communication system efficiency.
Therefore, a new session key generation protocol is proposed to overcome this
demerit. In our new model, the key exchange and digital signature process only
perform once, and the subsequent session keys can be computed in both sides
without the two processes. Because the two processes can be eliminated, our
protocol can promote more performance than the current-used model.
Keywords: Public-key cryptography, SSL, Authentication, Key Agreement
Title
of the Paper:
Implementation of WIMAX IEEE802.16d Baseband Transceiver on Multi-Core
Software-Defined Radio Platform
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Authors:
Mohammed Aboud Kadhim, Widad Ismail
Abstract: IEEE 802.16d was developed for WIMAX wireless communication, which
is based on orthogonal frequency division multiplexing (OFDM) technology, to
enable advancement towards 4G The last decade have seen growing importance
place on research in wireless communication system. A recent surge of research
on WIMAX has given us opportunities and challenges. In this paper, we describe
the implementation of WIMAX baseband transceiver on multi-core
Software-defined radio (SDR) platform. This work presents a new approach to
the adaptation of WIMAX technology on the basis of SFF SDR development
platform. The proposed WIMAX system was modelled-tested, and its performance
was found to comply with Stanford University Interim (SUI) Channel Models that
have been elected for the wireless channel in the simulation process. The
performance results of the simulated on different modulation systems were also
compared among themselves.
Keywords: WIMAX, SFF SDR, OFDM, RS, Coding, SUI, AWGN
Title
of the Paper:
Capability-Aware Object Management based on Skip List in Large-Scale
Heterogeneous P2P Networks
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Authors:
Takashi Tomimoto, Takuji Tachibana, Kenji Sugimoto
Abstract: In this paper, we propose an object management method in large-scale
heterogeneous P2P networks. In the proposed method, objects can be stored in
and searched from nodes by considering node's capabilities. The proposed
system is based on skip list, and two identifications are utilized; TypeID and
HashID. The TypeID is used to specify each node's capabilities, on the other
hand, HashID is used for providing load balancing among nodes with similar
capabilities. According to the two identifications, message routing for
storing and searching objects is performed. We evaluate the performance of the
proposed method by simulation, and we investigate the effectiveness of the
method. Numerical examples show that the proposed method can manage objects
based on node's capabilities and can provide the scalability when the number
of nodes is large and the difference in node's capabilities is large.
Keywords: Peer-to-Peer networks, Skip list, DHT, Heterogeneous networks, Object
management
Title
of the Paper:
Evaluation of Restoration Mechanisms for Future Services using Carrier
Ethernet
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Authors:
H. Wessing, M. Berger, H. M. Gestsson, H. Yu, A. Rasmussen, L. Brewka, S.
Ruepp
Abstract: In this paper, we evaluate and classify future service according to
their requirements for delay, loss and bandwidth. The most demanding services
include IPTV in different forms, hence IPTV is used as a representative for
future services. Carrier Ethernet technologies are introduced with special
focus on its OAMfunctionalities, and it is evaluated how IPTV performs in case
of link failures on a Carrier Ethernet implementation. It is concluded that
OAM update times of 10 ms is required to provide acceptable restoration
performance in case of errors.
Keywords: Carrier Ethernet, IPTV, MDI, PBT, MPLS-TE
Title
of the Paper:
On Performance of TCP and VoIP Traffic in Mobile WiMAX Networks
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Authors:
Dragorad Milovanovic, Zoran Bojkovic
Abstract: The major performance objectives of the next-generation wireless
communication systems are high link capacity and increase application/service
performance from the user perspective. An attractive technology for providing
broadband access is WiMAX network. For the network and application-level
capacity and performance analysis, we first provide an overview of WiMAX
network architecture and system performance. Afterward we discuss the benefits
and challenges of flat architecture for mobile networks. In this kind of
architecture the access service network gateway and base stations are
consolidated into a single channel. All-IP flat architecture is a promising
option. However, performance goals of the WiMAX system are conflicting:
maintenance VoIP quality vs. completely utilization of the remaining capacity
for TCP. We investigate the approaches in performance optimization based on
TCP modification schemes. The solution is to control TCP traffic before
entering WiMAX network in conjunction with methods to dynamically estimate
available bandwidth in real time.
Keywords: Wireless networking, TCP performance, Traffic control
Issue 6, Volume 9,
June 2010
Title
of the Paper:
A Mobile Disaster Management System Using the Android Technology
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Authors:
Jovilyn Therese B. Fajardo, Carlos M. Oppus
Abstract: The Philippines is one of the countries in the world vulnerable to
natural hazards because of its geographic location. It also lacks an efficient
disaster management system that will help in times of need. One common
scenario during disasters is that the activity of rescue and relief is not
well-coordinated. For this reason, there is a need for a system that will help
in the efficient provision of rescue and relief to disaster-affected areas.
Since the use of smart phones is gaining interest in people, the disaster
management system was implemented as a smart phone application using Google’s
Android operating system. The disaster management system Android application
known as MyDisasterDroid determines the optimum route along different
geographical locations that the volunteers and rescuers need to take in order
to serve the most number of people and provide maximum coverage of the area in
the shortest possible time. Genetic algorithm was applied for optimization and
different parameters were varied to determine the most optimum route.
Keywords: Android, Disaster management, Genetic algorithm, Travelling salesman
problem, Smart phone application, Wireless mobile technology
Title
of the Paper:
An Optimum Design of 3x3 Optical Switch based on Integrated MZI, Including the
Influence of Electro Optic
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Authors:
Mohammad Syuhaimi Ab. Rahman, Khaled Mohamed Shaktur, Rahmah Mohammad
Abstract: The influence of waveguide thickness on the output power according
to the voltage applied to the electrodes based on Integrated Mach-Zehnder
interferometer is investigated. Simulation result which are performed using
BPM software, stress that there is an optimum value of 3x3 switching optical
waveguide thickness at which the switch process and in turn the output power
at 1300nm wavelength can be achieved. This is because the thickness affect
significantly the coupling region between the waveguide, and also the effect
of the Pockels and Kerr coefficients.
Keywords: MZI (Mach-Zehnder interferometer), Electro-optics, Directional
couplers, Kerr and Pockles coefficients, All-optical switch
Title
of the Paper:
High Level Tele-Operating Speech Communication System for Controlling a Colony
of Robots
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Authors:
Al-Dahoud Ali, Mohamed Fezari, Attoui Hamza
Abstract: The purpose of this article is to presents the implementation and
design of a high level communication interface based on multi agents model for
a set of autonomous robots. Classical techniques, used in speech recognition
which are zero crossing and extremes, dynamic time warping and different
features such as Mel frequency Cepstral coefficients, delta MFCC , Energy and
LPC are merged in order to increase the rate of recognition, followed by a
decision system based on independent methods test results, are used as a
speech recognition agent. Two consecutive agents; namely syntactic and
semantic agents, are added to improve the recognition rate and improve the
human-machine communication language. To implement the approach for
tele-operating a set of robots on a real time, a Personal Computer interface
was designed based on Bluetooth wireless communication modules to control the
movement of a set of robots using high level language. The voice command
system for four autonomous robots is designed however the robot navigation
techniques are not discussed in this work. The main parts of the robots are
based on a microcontroller from Microchip PIC18F2450, a set of sensors modules
and a Bluetooth module.
Keywords: Speech recognition, HLL (High Level Language, Hybrid methods, human
-robot interaction, DTW, Robots, Microcontroller, wireless communication
Title
of the Paper:
Curved Strip Dipole Antenna on EBG Reflector Plane for RFID Applications
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Authors:
N. Fhafhiem, P. Krachodnok, R. Wongsan
Abstract: This paper presented the study and design the curved strip dipole on
Electromagnetic Band Gap (EBG) reflector plane that can be affected the
performance of the proposed antenna for RFID application. The proposed antenna
consists of a strip dipole that constructed of a metallic sheet and it was
bended to be a half of annular with feed point at the center for yielding
wider beamwidth. Normally, a curved strip dipole antenna without the reflector
provides low gain of 1.5 dB, due to its features of radiation patterns, both
in azimuth and elevation planes. In our case, the resonant EBG technology has
been used to be a reflector for directive gain increment by utilizing the good
performances of EBG structure, which is capable of providing a constructive
image current within a certain frequency band. Therefore, when this curved
dipole is appropriated located horizontally on a resonant EBG reflector, the
low profile antenna that provides good performance such as large beamwidth,
wide bandwidth, and high directive gain can be obtained, consequently. The
first curved strip dipole antenna with 3?3 elements and the second one with
5?5 elements of EBG reflectors, respectively, have been fabricated and their
RF performances have been measured. For 3?3 elements of EBG reflector, the
measured beamwidth in E- and H-planes are 100° and 110°, respectively,
frequency bandwidth is 2.06-2.59 GHz and directive gain is 7.45 dBi at 2.45
GHz. In case of 5?5 elements of EBG reflector, the measured beamwidth in E-
and H-planes are 65° and 120°, respectively, frequency bandwidth is 2.06-2.62
GHz and directive gain is 7.65 dBi at 2.45 GHz. From simulation and
experimental results, it's obvious that many applications can be conceived for
a curved strip dipole on EBG reflector plane due to its geometrical and
electromagnetic features.
Keywords: Curved Strip Dipole Antenna, Electromagnetic Band Gap (EBG), RFID
Technology
Title
of the Paper:
Performance Analysis of 1x2 Optical Power Splitter
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Authors:
Mohammad Syuhaimi Ab-Rahman, Foze Saleh Ater, Kasmiran Jumari, Rahmah Mohammad
Abstract: In this paper, the influence of the width of waveguide and the
branching angle of the output arms on the output power of 1?2 optical splitter
has been investigated in details. We showed that the output power is improved
when the width increases for single mode transmission. In addition, at
specified values the core and cladding refractive indices, approximately 50%
input-to output power ratio is achieved at the output. Moreover, the output
power can be controlled by adjusting the branching angle of the device.
Keywords: Banching angle, optical power, optical splitter, waveguide width
Issue 7, Volume 9,
July 2010
Title
of the Paper:
Implementation of Zigbee-based and ISM-based Wireless Sensor and Actuator
Network with Throughput, Power and Cost Comparisons
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Authors:
Rosula S. J. Reyes, Jose Claro Monje, Marc Ericson C. Santos, Lorlynn A.
Mateo, Roma Lynne G. Espiritu, John Vianney Isiderio, Carlos Miguel M. Lacson,
Ray Edwin T. Ocfemia
Abstract: Wireless sensor and actuator networks have expanding applications
which requires better throughput, power efficiency and cost effectiveness.
This study intends to contribute to the growing pool of knowledge on WSAN
especially in the design for novel applications such as image or video over
WSANs, and solar energy and RF energy harvesting for the WSAN nodes. Two basic
scalable wireless sensor and actuator networks were implemented and
characterized in terms of throughput and power consumption. The two WSANs are
the Zigbee-based WSAN which is based on the IEEE 802.15.4 protocol, and the
ISM-based Zigbee which makes use of the industrial, scientific and medical
(ISM) radio bands. The star topology was used for both WSAN implementations.
The throughput is quantified with varied factors including distance from node
to node, obstructions in between nodes and co-channel interference. As
distance and obstructions between nodes are increased, the throughput for both
networks decreases with varying degrees. Co-channel interference is also
considered. The ISM-based WSAN network is weak in dealing with co-channel
interference and error rate as compared to the Zigbee-based WSAN, thus
requiring it to have a better data encryption. Power consumption is generally
larger for the ISM-based WSAN as compared to its Zigbee-based counterpart.
However, the ISM-based nodes consume the same power even up to a few hundreds
of meters distance and are thus practical for covering large distances.
Therefore, the Zigbee-based WSAN system is more appropriate for closed
environment, such as in room automation and home automation applications where
distance from node to node is relatively shorter. The ISM-based WSAN
prototype, on the other hand, can be developed further for applications in
larger areas such as deployment in fields and cities, since transmission is
not generally limited by distance and obstructions.
Keywords: Sensor, actuator, WSAN, Wireless Sensor and Actuator Network, power
consumption, throughput
Title
of the Paper:
Quantifying Cryptographic Techniques in Radio Frequency Identification
Protocols and Ways of Remedying the Security Threats
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Authors:
Cristina Hurjui, Stefan Holban, Adrian Graur
Abstract: Critical examinations concerning the Radio Frequency Identification
security and privacy have determined wide analysis over the time. RFID
applications have always assumed two important hierarchies: structures aiming
to offer security to RFID systems and structures aiming to offer
functionality, with no security issues. A way of creating radio frequency
identification systems more secure relies on cryptography. Nine RFID protocols
of identification and authentication are examined in this paper, so as to
analyze the strong points and to find solutions for the weak or jeopardizing
points that threaten the security and privacy of RFID systems. By reaching the
best security and privacy solutions, using of RFID systems will bring
visibility within developing business strategies or logistics processes, in
thoroughly transparency. In many situations, the threatening over RFID
structures is the result of designing weak protocols. Presumable attacks on
RFID structures are evaluated; important ways of comparison and analysis
amongst nine existing protocols are utlined. At the end of each description,
solutions of treating the weak points are emphasized.
Keywords: Radio frequency identification, protocol of identification, protocol
of authentication, security, privacy
Title
of the Paper:
Blind Signal Processing based on Information Theoretic Learning with
Kernel-size Modification for Impulsive Noise Channel Equalization
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Authors:
Namyong Kim
Abstract: This paper presents a new performance enhancement method of
information-theoretic learning (ITL) based blind equalizer algorithms for ISI
communication channel environments with a mixture of AWGN and impulsive noise.
The Gaussian kernel of Euclidian distance (ED) minimizing blind algorithm
using a set of evenly generated symbols has the net effect of reducing the
contribution of samples that are far away from the mean value of the error
distribution. The process of ED minimization between desired probability
density function (PDF) and output PDF is considered as a harmonious force
interaction on PDF shaping between concentrating force and spreading force.
The spreading force is composed of the difference between output sample values
themselves, and is directly related with the output information potential and
the output entropy that leads to the output distribution spreading out. The
proposed kernel-size modification scheme is to impose loose discipline on the
spreading force by employing larger kernel-size so that the long distance
between two outputs which are correct symbol-related and far-located is less
likely to be treated as impulsive noise. From the simulation results, the
proposed kernel-size modified blind algorithm not only outperforms correntropy
blind algorithm, but also significantly enhance robustness against impulsive
noise.
Keywords: Impulsive noise, blind equalization, kernel-size modification, source
symbol assignment, information-theoretic learning, PDF, correntropy, CMA
Title
of the Paper:
A Solution for Secure SIP Conferencing over IMS and SAE
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Authors:
Cristina-Elena Vintila
Abstract: Over the latest few years, most of the major telephony and services
providers have got their attention on the LTE/SAE solution, in the attempt of
getting the most bandwidth and features at the least implementation and
operating price. One of the major challenges that 3GPP, the creator of LTE/SAE
architecture, has faced is the IMS integration with SAE. The latest standard
version available at this moment on IMS integration and its security
challenges is TS 33.203, which is focused on 3G security aspects. When talking
about IMSSIP security, there are several studies that propose end-to-end
security for a SIP conversation over EPS infrastructure. This paper reviews
the security issues that resides in the SAE-IMS interaction and, looking at
the specificities of the SIP conferencing, proposes a security model that uses
GDOI management to secure the SIP conference data over IMS and SAE. One
important aspect of conferencing in the mobile world is to realize the user is
never stationary. One chapter of this paper describes the most complicated
type of mobility scenario and also introduces the role of the Diameter server
into this architecture.
Keywords: SAE, LTE, EPS, EPC, IMS, security, SIP, conference, GDOI, GCKS, IPsec,
key management
Title
of the Paper:
Analysis of Routing Metrics for Offering IPTV over WiMAX Using Fuzzy Logic
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Authors:
Arianit Maraj, Skender Rugova
Abstract: The quality of delivering IPTV services depends on the network QoS
and bandwidth of broadband service providers. The possibility to offer high
bandwidth capacity of WiMAX technology is attractive to offer IPTV services.
There is an increasing trend to deploy WiMAX technology for offering those
services. Network QoS for offering IPTV services depends on network
efficiency. To satisfy QoS requirements for offering IPTV over WiMAX
technology we should take into consideration routing metrics that affect
directly to the QoS. Here we will consider three metrics: bandwidth, losses
and delays. For transmitting multimedia (in this case IPTV) services over
WiMAX it is desired to design some controlling mechanisms for solving
different problems in a network in case of packet delays, losses etc. Because
of complex nature of controlling mechanisms it is desired to design
intelligent controlling techniques. One of the intelligent techniques that
would be present in this paper is fuzzy logic controller. In this paper we
will design FLC using Matlab software. As input parameters will be three
routing metrics mentioned above, whereas as output parameter will be network
efficiency. The aim is to obtain better values of network efficiency using
different rules from Rule Editor and using appropriate defuzzification method.
Keywords: Routing Metrics, Quality of Service, WiMAX, IPTV, Fuzzy Logic,
Defuzzification Method
Issue 8, Volume 9,
August 2010
Title
of the Paper:
Performance Comparison of Wavelet Packet Transform (WPT) and FFT-OFDM System
Based on QAM Modulation Parameters in Fading Channels
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Authors:
Haitham J. Taha, M. F. M. Salleh
Abstract: Orthogonal Frequency Division Multiplexing (OFDM) has been widely
adopted in many applications due to its good spectral performance and low
sensitivity to impulse noise and multipath channels. It has been widely
adopted and standardized in many applications today. It is well known in OFDM
that a cyclic prefix (CP) is appended to each symbol in order to mitigate the
effect of Inter-Symbol-Interference (ISI). However, this reduces the spectral
efficiency. A perfect reconstruction using wavelet packet transmultiplexer in
OFDM transceiver counters the degrading effect of ISI, and also conserves
bandwidth. In comparison to FFT-OFDM, Wavelet Packet Modulation (WPM) offers
much lower side lobes in the transmitted signal, which reduces inter carrier
interference (ICI) and narrowband interference (NBI). WPM improves spectral
efficiency due to the exclusion of CP. Nevertheless, it requires an efficient
equalization technique to counter the ISI and ICI. Wavelet based OFDM has been
suggested to improve BER performance of transceiver in wireless communication.
In this paper, a study of wavelet packet transform modulation WPT-OFDM scheme
is conducted, and the performance comparison is made against the traditional
FFT-OFDM over various fading channels. The analysis is done using various
number of modulation QAM constellation points. Specifically, the analysis is
on the effect of QAM constellation points in AWGN channel, flat fading channel
and frequency selective fading channels. Simulation results using QAM
Modulation points (8 to 64 Point), and the BER best performance of WPT- OFDM
system is when the QAM Modulation parameter (QAM = 8) in all channels.
Keywords: FFT-OFDM, Wavelet Packet, WPT-OFDM
Title
of the Paper:
Selection Based Successive Interference Cancellation for Multicode
Multicarrier CDMA Transceiver
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Authors:
S. Praveen Chakkravarthy, N. Nagarajan, V. Arthi
Abstract: A Selection based Interference algorithm for efficient decoding of
MC-MC-DS-CDMA Transceiver with Multipath Rayleigh fading is presented in this
paper.The Interference Cancellation algorithm is capable of increasing signal
strength and reducing probability of error using two stages of decoding namely
, Selection phase and Threshold decoding phase .The numerical results have
shown that effective decoding with respect to frequency increases SNR levels.
Keywords: MC –MC DS CDMA (Multicode Multicarrier Direct Sequence
CDMA),SIC(Succesive Interference Cancellation) SNR(Signal to Noise Ratio)
Title
of the Paper:
Dissolving Active Networks Privacy Threats and Vulnerabilities
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Authors:
Tai-Hoon Kim
Abstract: This paper proposes an efficient dual authentication key exchanged
in an active network scenario. The scheme protects personal privacy of
identity information. It also provides an effective method to protect against
DOS attacks with the scope information of initiator’s random number table sent
by the responder.
Keywords: Active Networks, Security, Identity Management System
Title
of the Paper:
Accounting Professional Education Schemes: Case of Czech Republic and Estonia
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Authors:
Jiri Strouhal, Kaidi Kallaste
Abstract: The knowledge level of professional accountants is emerging issue in
each economy. Change of economic environment in Central and Eastern Europe in
90s of 20th century brought new requirements on professional accountants. This
paper provides the comparative analysis between accounting certification
schemes in the Czech Republic and Estonia (two emergent countries from the
area of CEE), which are applied on professional accountants. Those schemes are
also compared to international referential (qualifications ACCA, CPA Australia
and AIA). The results show very high level of convergence between Czech model
and international qualification schemes.
Keywords: Accounting Certification; International Education Standards;
Association Coefficients; Professional Accountants; Czech Republic; Estonia
Title
of the Paper:
Linear Model of Adapting Frame Size in DFSA of Passive GEN2 RFID Systems
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Authors:
Petar Solic, Josko Radic, Nikola Rozic, Mladen Russo
Abstract: Low costs of passive UHF RFID tags, as well as their simplicity
makes them appropriate for the localization and tracking services in today’s
fast-moving, information rich trading networks. However, a few disadvantages
of passive RFID technology performances, as a reading range of passive tags
and high collision rate during RFID reader-tag communication, still needs
quality of service improvements. In order to maintain passive technology
cheap, but to improve the disadvantages, it is important for tags not to
include any additional electronic circuitry, and to maximize the efficiency of
the actual hardware. So, it is necessary to develop the optimal algorithms in
order to maximize the communication efficiency. In this paper we provide the
analysis on MAC layer protocol of passive UHF-Gen 2 RFID standard. In the
accordance with the standard, we provide the improvement for the frame size
adaptation, which increases the throughput of RFID system and thus minimizes
the time for tags identification. The algorithm for the improvement includes
the estimate of the number of tags through the linear behavior model of number
of Collisions (C), and Successful (S) slots within the frame. Estimated number
of tags is used for adaptation of the frame size. For comparison, simulation
results show that our approach provides better efficiency than Q-Selection
algorithm from UHF-Class1-Gen 2 standard.
Keywords: Framed Slotted ALOHA, transmission control strategy, Q-selection
Algorithm, RFID identification, Number of tags estimation
Title
of the Paper:
Semantic Concordance in the South-East European Languages
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Authors:
Ancuta Negrea, Agnes Erich, Zlate Stefania
Abstract: The common terms of the south-east European languages that present
semantic convergences [1], belong to a less explored domain, that of
comparative linguistics. “The reason why the words have certain significations
and not others is not found in the linguistic system or in the human
biological or mental structures … it is the societies that, through their
diverse history, determine the significations, and the semantics is found at
the crossroads between the historical complexity of the reality it studies and
the historical complexity of the culture reflecting on this reality… its
object is the result and the condition of the historical character, thanks to
the relations of mutual conditioning that relate the signification to the
historic events of each human community.”[2] In the south-east European
languages, several onomasiological lexical fields have been delimited, in
which we can discover tendencies of parallel semantic development for several
terms of different origin. The terminology of the wedding can be analyzed from
this perspective. In the case of the south-east European languages, the
parallel semantic tendencies are present as: development of identical meanings
by different words in different languages, naming the same reality; borrowings
in several languages of the same meanings of a polysemantic word. In classical
Latin, there was a strict opposition according to gender for the verbs
denominating marriage, homo uxorem ducit being the counterpart of femina nubet
. During the postclassical period, in a sermon of Saint Augustine, instead of
these verbs appear uxorati viri and maritare feminae. This old opposition
according to gender has been kept in Romanian, in the southern Italian
dialects, in Provencal, Catalan and certainly in Dalmatian. In other areas of
the Roman Empire, this opposition according to gender has been lost because of
the influence of the German languages, so that the same verb is used for both
genders. In this sense, it would be interesting to follow the evolution of the
French verb marier, attested for the first time in 1155 with the meaning “to
marry one’s daughter”, After 1170, the reflexive construction se marier avec
“to take for wife” emerges, instead of the transitive verb marier (attested
for the first time in 1176), a construction still encountered in some
provinces. Se marier, with a subject in the plural, is attested in the year
1220 (DILF 2, 1192; NDEI, 446; Paris, 1971). Yet, in other Romance languages,
for instance in Italian, though there is the construction maritarsi – in which
the opposition according to gender is neutralized, there is also the verb
ammogliarsi “to take a wife”, which is used only from the man’s point of view,
including the form moglie “woman, wife”.
Keywords: Balkan linguistics, terminology of the word “house”: Bg. kasta, Srb.,
Cr. kuca, Maced. kuk’a, slov. koca, Rom. casa; Ngr. σπητη; Alb. shtepi ; the
terminology of “wedding”: wedding, sister-in-law, brother-in-law
Title
of the Paper:
Robot Vision and Video Transmission
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Authors:
A. Ritchie, J. Conradi, A. Prevot, E. A. Yfantis
Abstract: In this research paper we examine the problem of distance resolution
using four cameras and a noninvasive laser light for robot vision. The cameras
are placed in a cross configuration and the noninvasive laser is in the center
of the cross. The system constitutes the vision part of a robot used for
remote patient visits by physicians. The system enables physicians to perform
between visit comparisons in order to assess health patient improvements.
During the patient’s hospital robot visits made with the help of a nurse, the
cameras take the relevant patient images and transmit them wirelessly to a
file server housed in the hospital where they are stored and from where they
are also being transmitted to the Phycisian’s office for real time
examination, and comparison with the images of the previous visit. The ROY is
compressed lossless and the remaining part of the image is compressed lossy.
Each time the robot visits a patient positions itself on a fixed distance from
the center of the ROY. Therefore distance resolution and distance tolerance
interval estimation is very important. In this research paper we model the
distance with a Gamma probability distribution and we compute the tolerance
interval of the distance. Our system is part of a sophisticated system that
includes personal patient networks, and radiological image – video management,
and secure network transmission.
Keywords: Network programming, De-Interlacing, Compression, RAID Arrays, Client,
Server, Real-Time
Issue 9, Volume 9,
September 2010
Title
of the Paper:
VHDL Modules and Circuits for Underwater Optical Wireless Communication
Systems
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Authors:
Davide Anguita, Davide Brizzolara, Giancarlo Parodi
Abstract: Underwater wireless optical communication has been used for
establish a link between mobile vehicles and/or fixed nodes because light,
especially in the blue/green region, allows to achieve higher data-rate than
acoustical or electromagnetic waves for moderate distances. The here proposed
work has the aim to pave the way for diffuse optical communication allowing to
support optical communication in an Underwater Wireless Sensor Network of
dense-deployed fixed nodes for specific application, such as monitoring and
surveillance, for shallow, coastal and inland water in the case of
moderate/limited area. In particular, taking into account already developed
protocols for optical wireless communication, the focus is on the hardware
implementation of different flexible modules to support both point-to-point
and directional communication targeting the use of these technologies in the
field of UnderwaterWireless Sensor Network and the integration with current
terrestrial technologies forWireless Sensor Network. After a careful analysis
of benefits and problems related to optical transmission underwater, design
considerations are proposed with the description of the implemented modules.
The use of light impulse for communication is motivated by the possibility of
targeting high data-rate, low-cost and small dimension components. This paper
describes an overall vision of the system: a HDL implementation of flexible
modules for the management of optical communication (based on IEEE 802.15.4
and IEEE 802.11 standard) which target the interface with current terrestrial
technology forWireless Sensor Networks; the design and implementation of
circuits for underwater optical point-to-point and planar communication. The
preliminary results and design consideration are reported considering also
future possible developments.
Keywords: Underwater Wireless Communication, Optical Communication, Physical
(PHY) Layer, Medium Access Control (MAC) Layer, Wireless Sensor Networks
Title
of the Paper:
Integration of Real Network Components into OPNET Modeler Co-simulation
Process
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Authors:
Milan Bartl, Jiri Hosek, Tomas Matocha, Karol Molnar, Lukas Rucka
Abstract: The OPNET Modeler is a simulation environment enables modeling of
large-scale networks with in detail defined parameters. This paper is focused
on the possibility to communicate with external systems and applications that
this environment offers. Due to this we are able to interconnect simulation
environment with real network system and gain the simulation results more
accurate and in accordance with the reality. We created communication model
composed from network scenario created in the OPNET Modeler, C/C++ external
application and Cisco router. For this purpose we implemented the SNMP
protocol into the OPNET Modeler. This model enables data exchange between
external network component and work station in OPNET Modeler scenario. This
model is very useful especially in the situation when you need to include a
real network device into simulation process, because the pure simulation
environment is not quite sufficient.
Keywords: BER, Esys interface, MIB, OPNET Modeler, SNMP
Title
of the Paper:
Algorithms of Digital Modulation Classification and their Verification
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Authors:
Anna Kubankova, David Kubanek
Abstract: Two methods of the classification of digital modulations ASK, FSK2,
FSK4, MSK, BPSK, QPSK, 8PSK and QAM-16 are presented. The first algorithm is
based on module and phase spectrogram analysis. Here it is very important to
estimate the symbol length of the received signal and thus we introduce two
methods for this purpose. They are based on the wavelet transform and cepstrum
analysis. The second algorithm of modulation classification uses instantaneous
values of signal (instantaneous amplitude, phase and frequency). A method of
the practical verification of classification algorithms in laboratory
environment is described.
Keywords: Classification of modulations, examination, modulation, symbol length
estimation
Title
of the Paper:
QoS Parametric Correlation for Network Management, a Link between
Application's Requests and Network's Capabilities
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Authors:
Emanuel Puschita, Tudor Palade, Mihai Sarlea, Ancuta Moldovan, Rebeca Colda,
Irina Vermesan
Abstract: Optimal resources management between application’s requests and
network’s capability is determined by a human-device interaction, completing
in this way the future architectural concept of developing inherent /
integrated resource management capabilities inside the network elements. By
aggregating and setting up QoS parametric dependencies between user’s needs
and network’s context, resource management represents the guarantee for high
performance network. Performing an analysis of application inter-frame delay
and frame-size parameters – as the application’s requested parameters – upon
the received signal level, retries rate, channel throughput, and loss rate of
the RF network – as the network’s capabilities – the paper demonstrates that
QoS parametric correlation can prove crucial on network resource management.
Keywords: QoS parameters, network management, frame-size, inter-frame delay,
received signal level, retry rate, channel throughput, loss rate
Title
of the Paper:
Identifying the Course Role of In-service Learning via the Social Network
Structure
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Authors:
Lung-Hsing Kuo, Hsieh-Hua Yang, Jui-Chen Yu, Hung-Jen Yang, Lydia Lin
Abstract: The purpose of this study focused on the social network structure of
in-service development for the English literature expertise teachers in Taiwan
High school. Social network analysis methods include the core measures,
identification of groups to analyze the role, figure based on the statistical
analysis and so on. In this study we use 2009 National Teacher in-service
Education Information Network (http://inservice.edu.tw/) database to obtain
4,317 sample resources. The expected result should be able to understand
English literature teacher in-service refresher training expertise in the
overall network of centricity, teachers participate in studies course subject
categories and countries connected, education seminar for subgroups generated
number, subgroups on overall network impact, etc.
Keywords: In-service development, Social network structure, High school, UCINET,
English literature teacher
Title
of the Paper:
Perceived Organizational Culture, Professional Commitment, Advice Network and
Job Satisfaction of Novice Nurses
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Authors:
Hsieh-Hua Yang, Fen Fen Huang, Yi-Horng Lai, Chi-Jen Hsieh, Yu-Sheng Liao,
Wan-Ching Chao, Shu-Fen Chen
Abstract: Nurses’ job satisfaction is an important issue and it receives a lot
of attention in the international nursing literature. But research about the
influencing factors of novice nurses’ job satisfaction is yet insufficient,
especially a newcomer’s advice network. This study explored the influence of
network outdegree in the same division and across divisions on job
satisfaction, as professional commitment, and perceived organizational culture
were included as control variables. A total population of nurses recruited
within 3 months in a medical center was surveyed. The results showed that
perceived organizational culture was the strongest predictor of job
satisfaction; and support the different effects of advice network outdegree in
the same division and across divisions on job satisfaction.
Keywords: Social network; advice network, outdegree across divisions; job
satisfaction; novice nurse
Title
of the Paper:
Investigating the Impacts of Digital Elements in Web Information for
Socio-Informatics
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Authors:
Siti Z.Z. Abidin, Nasiroh Omar, Hani F. A. Rahman, Marshima M. Rosli
Abstract: The Web offers enormous amount of digital information for
communication and socializing. The fact that Web has been able to provide
users with instant and global access to shared information, this platform
gives a powerful medium of communication. When people are free to send and
receive information, there is a potential to influent other people or be
influenced by others through the use of digital element for its effective
presentation. In today’s world, there are many cases where people take
advantage of these social media to involve in activities that lead to crime
cases. Information can be manipulated. Therefore, it is crucial to identify
the impact of digital element within the Web information that affects users’
minds. In web-based socio-informatics, the conversation of these people take
place without any support of physical movement like in face-to-face
environment, hence, the strength of digital elements appear to be effective in
influencing people’s perception. In this paper, we discuss our study on
investigating the impacts of digital elements that include text, two
dimensional (2-D) and three dimensional (3-D) graphics, audio and video, which
are embedded in Web information. For finding such factors, each type of
digital elements is examined in terms of its attributes and usage.
Investigations are performed to look into the strength of such digital
elements by understanding the existing guidelines, psychological or mental
models and theories. It is important to look into such models and theories to
justify how digital presentation can relate to the human perception. By
identifying the impact factors, information can be constructed using the
effective digital elements so that the social media are used in a proper
manner with good impacts in strategic communication.
Keywords: Web information, impact factors, digital elements, socio-informatics,
strategic communication, perception
Issue 10, Volume 9,
October 2010
Title
of the Paper:
System Performance Evaluation of the IEEE 802.16e Pico-Base Station in
Multihop-Relay and Mesh Networks
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Authors:
Kemal Alic, Ales Svigelj, Tomaz Javornik
Abstract: Paper proposes a new design and a simulation model for the pico base
station based on IEEE 802.16e standard and evaluates its performance in a
mutihop-relay and mesh networks. The proposed base station design allows
multihoprelay communications and thus opens a possibility for the proposed
base station to be an element of mesh networks. The conventional IEEE 802.16e
base stations interconnected vie router or Ethernet switch are applied for
point to point links and broadband wireless access. The design has been
evaluated using proposed simulation model and the simulation tool OPNET
Modeler for different scenarios that present real case deployment options for
mesh networks thus allowing the multihop relaying that is to be supported only
in the upcoming 802.16j standard, while the design is based on existing and
well tested building blocks for conventional IEEE 802.16e base station.
Keywords: WiMAX, IEEE 802.16j, IEEE 802.16e, Pico base station, Simulation
model, OPNET
Title
of the Paper:
Operating Room Information Systems Adoption by Portuguese Clinical Users
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Authors:
M. F. Santos, L. Gomes
Abstract: This research aims to assess the impact of the adoption of
Information Systems by clinical users in the Operating Room. This is an
empirical and qualitative research, to find a complete and comprehensive
understanding of the phenomenon under study. A sample of Portuguese
Anesthesiologist have been invited from public and private hospitals. Through
the application of the Delphi method, with surveys online it is expected an
interactive and systematical approach to estimate the impact of the adoption
of these systems, based on the experience of several independent clinical
users (experts).
Keywords: Clinical Information Systems, Delphi Methodology, Operating Room,
Technology Acceptance
Title
of the Paper:
Services for Advanced Communication Networks
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Authors:
Vladislav Skorpil, David Novak
Abstract: Services for Advanced Communication Networks are described in this
paper. An Artificial Neural Network will be used for the control of Network
Elements, in our case a Switch. Classical sequence data processing is
substituted by parallel processing. The classical switch and the switch
controlled by a Kohenen Artificial Neural Network are compared. The switch has
four ports and its own Quality of Service (QoS) control. Services such as FTP,
HTTP, VoIP and QoS mechanisms without QoS, Best Effort QoS, FIFO QoS,
Integrated Services (IntServ) and Differentiated Services (DiffServ) are
simulated and compared. The level of priority contains the overhead of IP
packet as the Type of Service (ToS) or also as Differentiated Services Code
Point (DSCP). The Opnet Modeler programme is used for the simulation.
Keywords: Artificial Neural Network, ANN, Network Element, NE, Converged
Network, Delay, Jitter
Title
of the Paper:
Radio Coverage Calculations of Terrestrial Wireless Networks using an
Open-Source GRASS System
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Authors:
Andrej Hrovat, Igor Ozimek, Andrej Vilhar, Tine Celcer, Iztok Saje, Tomaz
Javornik
Abstract: Radio network planning and dimensioning have significant impact on
the overall system capacity of the cellular communication systems. Various
commercial network planning and dimensioning tools with different radio signal
propagation models implemented are available on the market. Their price and
especially inflexibility led us to look for an open-source solution. The
present paper describes usage of the open-source Geographical Resources
Analysis Support System (GRASS) for the radio signal coverage calculation.
GRASS modules calculating radio coverage prediction for a number of different
radio channel models were developed which, together with module considering
antenna radiation pattern influence, compute radio signal coverage for a
defined cell. The complete network coverage is computed with modules for
generating a data base table (e.g. MySQL, PostgreSQL), arranging the values in
increasing order and determining maximal received power at each receive
location. Additional modules for adapting input data and analyzing simulation
results were also developed. The radio coverage tool accuracy was evaluated by
comparing with results obtained from a dedicated professional prediction tool
as well as with measurement results.
Keywords: Ntwork planning tool, open-source, GRASS GIS, path loss, raster,
clutter, radio signal coverage
Title
of the Paper:
Knowledge Services in Business Process Management: A New Way for Increasing of
Productivity?
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Authors:
Zuzana Tuckova, David Tucek
Abstract: This paper represent the appropriate software support for Process
Management, and those tools which are used in a whole range of Czech and
world-class manufacturing production and non-manufacturing enterprises as well
as in organizations and other public sector administration institutions. The
innovation in the tuition process lies in the fact that this software is not
used for modelling the processes within the university (the organization
itself) – but rather, that the students themselves model and analyze processes
drawn from realworld praxis (working practices) in manufacturing production
and non-manufacturing enterprises.
Keywords: ARIS (Architecture of Integrated Information Systems), Business
Process Management, Education, FTE, Knowledge, Management
Title
of the Paper:
Ant Colony Inspired Self-Optimized Routing Protocol based on Cross Layer
Architecture for Wireless Sensor Networks
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Authors:
Kashif Saleem, Norsheila Fisal, M. Ariff Baharudin, Adel Ali Ahmed, Sharifah
Hafizah, Sharifah Kamilah
Abstract: Nowadays, wireless sensor networks (WSNs) are becoming increasingly
beneficial, worthwhile and a challenging research area. The advancements in
WSN enable a wide range of environmental monitoring and object tracking
applications. Moreover, multihop (node by node) routing in WSN is affected by
new devices constantly entering or leaving the network. Therefore, nature
inspired self-maintained protocols are required to tackle the problems arising
in WSN. We proposed ant colony stimulated routing, which shows an outstanding
performance for WSNs. In this manuscript, a cross layer design based
self-optimized (ACO) routing protocol for WSN and the results are presented.
Link quality, energy level and velocity parameters are used to discover an
optimal route. The signal strength, remaining power and timestamp metrics are
trade in from physical layer to network layer. The emitted decision through
the WSN discovery will establish the optimal route from source to destination.
The adopted cross layer architecture helps ACO in improving the overall data
delivery ratio; especially in the case of real time traffic.
Keywords: Ant Colony Optimization, Cross Layer, Energy, Multihop, Packet
Reception Rate, Routing, Velocity, Wireless sensor Network
Title
of the Paper:
Advanced Implementation of IP Telephony at Czech Universities
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Authors:
Miroslav Voznak
Abstract: IP telephony is convenient way of communication and brings number of
benefits. One of them is the fact that many services can be implemented in a
original way and it opens new field of research and is a challenge for
designers of communication solutions especially based on open-source platform.
This article describes proposal and advanced implementation of IP telephony
which have been arisen in Czech academical environment, concretely in a group
of IP telephony acting under Czech Education and Scientific Network
association. Author is a senior researcher in this group and he decided to
describe the most considerable voice over IP implementations at Czech
universities and share knowledge with other experts interesting in IP
telephony.
Keywords: IP telephony, ENUM, SIP, H.323, Asterisk, OpenSER
Issue 11, Volume 9,
November 2010
Title
of the Paper:
Decoding Shortened Reed Solomon Codes at Bit Level
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Authors:
Ta-Hsiang Hu, Ming-Hua Chang
Abstract: This study presents a novel means of shortening a Reed Solomon (RS)
code at the bit level, yielding only shortened BCH subcodes. With the use of a
certain basis, an RS codes over is mapped onto a binary image[4], which
contains m concatenated BCH sub-codewords and some glue-vector codewords. With
the proposed approach, there only exist some shortened BCH subcode generators
in the diagonal entries of the corresponding binary image generator matrix of
an RS code. Hence, only binary codewords of shortened BCH subcodes exist in
concatenation. When such a codeword is transmitted, BCH decoders or an RS
decoder can be adopted at the receiver. In simulations of a BPSK coherent
system over AWGN channels, the error performance of BCH algebraic decoding is
better than that of RS algebraic decoding. The coding gain between both
decoding algorithms becomes obvious as the code rate reduces or the error
correcting capability of an RS code increases. At the word error rate 10-5,
the code gain can reach as much as 1.5 dB at the code date 0.747.
Additionally, with the proposed method for shortening RS codes over GF(28),
such a shortened RS code can be decoded by two or three BCH decoders in
parallel, which greatly reducing the decoding times and computational
complexity.
Keywords: RS decoding, shorten RS codes, shorten BCH codes, binary images
Title
of the Paper:
Distributed Position Localization and Tracking (DPLT) of Malicious Nodes in
Cluster Based Mobile Ad Hoc Networks (MANET)
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Authors:
Shakhakarmi Niraj, Dhadesugoor R. Vaman
Abstract: In this paper, a robust distributed malicious node detection and
precise localization and tracking method is proposed for Cluster based Mobile
Ad hoc Network (MANET). Certificate Authority (CA) node is selected as the
most stable node among trusted nodes, surrounded by Registration Authority
nodes (RAs) in each cluster to generate the Dynamic Demilitarized Zone (DDMZ)
to defend CA from probable attackers and mitigate the authentication overhead.
The RAs also co-operate with member nodes to detect a target node and
determine whether it is malicious or not, by providing the public key
certificate and trust value. In addition, Internet Protocol (IP) based
Triangulation and multi-lateration method are deployed based on using the
average time difference of Time of Arrival (ToA) and Time of Departure (ToD)
of the management packets. Triangulation uses three reference nodes which are
elected within each cluster based on Best Criterion Function (BCF) to localize
each member node inside the cluster in 2D. Multi-lateration is employed to
localize the malicious target node in 2D using four neighbor nodes. After
localization of two consecutive positions, the target node is continuously
localized and tracked by a particular node using the modified real time
Position Localization and Tracking (PL&T) algorithm by adaptive beam forming
and mapping the energy contours of tracking zone into coverage radii distance.
The performance of the proposed scheme demonstrates the significant accuracy
in the detection of malicious nodes within each cluster.
Keywords: Koay - Distributed Position, Localization, Tracking (PL&T), Malicious
node, Mobile Ad hoc Networks
Title
of the Paper:
Null Steering of Dolph-Chebychev Arrays using Taguchi Method
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Authors:
Abelmadjid Recioui, Hamid Bentarzi
Abstract: Dolph-Chebychev arrays are known to exhibit the best compromise
between sidelobe level and directivity. However, they place a constraint on
the null locations. Any attempt to impose nulls or get them deeper will impact
the directivity/sidelobe level trade-off. In this work, null placement in
Dolph-Chebychev arrays through element position perturbation is carried out
based on Taguchi method all while preserving the array aperture. Several
examples are considered for single, double, multiple and broad null placement
to demonstrate the ability of the Taguchi method to explore the search space
and reach the global optimum.
Keywords: Pattern Nulling, Dolph-Chebychev arrays, Taguchi method, Element
position perturbation
Title
of the Paper:
Capacity of MIMO System in the Presence of Directional Interferences
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Authors:
Jie Wang, Zhonghao Zhang, Yuehuan Gong
Abstract: Capacity of Multiple Input Multiple Output (MIMO) system degrades
significantly in the presence of interferences, especially in the presence of
strong directional interferences in military communication scenario. In this
paper, the capacity of a MIMO system with directional interferences is
investigated. The focus is on the case where the channel state information
(CSI) is known to the receiver but unknown to the transmitter. Further,
attention is restricted to narrowband MIMO system. The capacity of a MIMO
system with directional interferences is derived respectively for
deterministic and random fading MIMO channels. And the asymptotic lower limit
in high interference-to-noise ratio (INR) is also analyzed. It is indicated
that the relationship between the numbers of receive antennas and
interferences is critical to the capacity in high INR. The number of receive
antennas should be greater than that of interferences in order to ensure the
system work normally in high INR, and the corresponding capacity limit
approaches the capacity of another MIMO system using same number of transmit
antennas and fewer receive antennas without interference. Moreover, the
impacts of the correlation and directions of the interferences on capacity are
discussed respectively. It is indicated that higher correlation and closer
directions of the interferences both yields higher capacity. Monte Carlo
simulation results are given and well coincide with our theoretical analysis
results.
Keywords: MIMO, capacity, directional interference
Title
of the Paper:
An Uncapacitated Facility Location Based Cluster Hierarchy Scheme on Wireless
Sensor Networks
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Authors:
I-Hui Li, I-En Liao, Feng-Nien Wu
Abstract: Cluster-Head (CH) nodes function as gateways between the sensors and
the Base Station, in Wireless Sensor Networks with a cluster hierarchy. The
total energy dissipation of the sensors can be reduced by optimizing the load
balance within the cluster hierarchy. This paper proposes an uncapacitated
facility location based cluster scheme in which the system lifetime is
extended by adding an additional layer of Super- Cluster-Head (SCH) nodes, in
order to ease the transmission load of the CHs and to balance the load
distribution within the network. The SCH layer is configured using an
uncapacitated facility location algorithm in which the facility and service
costs are defined in terms of both the energy and the transmission distance.
The simulation results confirm that the proposed method yields a better load
balance in the SCH layer than that obtained using either a random
configuration or a round-robin scheme. Finally, it is shown that irrespective
of the size of the sensor field, the proposed scheme outperforms the
conventional LEACH-C two-layer scheme in terms of the average energy
dissipation of the nodes, the average survival times of the nodes, and the
overall system lifetime.
Keywords: Wireless Sensor Network, Gateway Node, Cluster hierarchy,
Uncapacitated Facility Location Problem
Issue 12, Volume 9,
December 2010
Title
of the Paper:
Transmission through Single and Multiple Layers in the 3-10 GHz Band and the
Implications for Communications of Frequency Varying Material Dielectric
Constants
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Authors:
A. Yahalom, Y. Pinhasi, E. Shifman, S. Petnev
Abstract: In this work we describe a model taking into account transmission
through single and multiple layers which are a consequence of the
inhomogeneity of the building materials our indoor environment is made of. Our
model enables the analysis of a communication channel for both the narrow and
wide band cases between adjacent rooms. We compare our analysis with real
world measurements performed in our laboratory and obtain an adequate
correspondence between our model results and the measurement. Our results
indicate that the dielectric constant of the materials is frequency dependent.
Keywords: Communications, RF, Propagation Models
Title
of the Paper:
Ultra Wideband Wireless Comunications in the 60 GHz Band
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Authors:
Y. Pinhasi, A. Yahalom, G. A. Pinhasi, M. Lutvak
Abstract: The growing demand for broadband wireless communication links and
the lack of wide frequency bands within the conventional spectrum causes us to
seek bandwidth in the higher microwave and millimeter-wave spectrum at
Extremely High Frequencies (EHF) above 30GHz. One of the principal challenges
in realizing modern wireless communication links in the EHF band is phenomenon
occurring during electromagnetic wave propagation through the atmosphere.
Space-frequency theory of the propagation of an ultra-wide band radiation in
dielectric media is presented. Characterization of the atmospheric medium is
via its refractivity leading to a transfer function, which describes the
response of the medium in the frequency domain. This description enables the
consideration of broadband signals taking into account inhomogeneous
absorptive and dispersive effects of the medium. Analytical expressions are
derived when a pulse-modulated signal is propagating in a general dielectric
material. We demonstrate the approach by studying propagation of ultra-wide
band signals, while transmitted in the vicinity of the 60GHz absorption peak
of the atmospheric medium at millimeter wavelengths.
Keywords: Ultra-wide Band, Extremely high frequencies, Broadband wireless
communications, Atmosphere
Title
of the Paper:
Performance Evaluation of Automatic Switched-Beam Antennas for Indoor WLAN
Systems
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Authors:
Monthippa Uthansakul, Peerapong Uthansakul, Paleerat Wongchompa
Abstract: In this paper, the design of a compact low cost switched-beam
antenna for users in Wireless Local Area Networks (WLAN) is introduced. Four
antenna elements are arranged in 2?2 lattice. The modification of beamforming
network based on Butler matrix is originally proposed for 2?2 planar array.
The design is verified through computer simulations and also the prototype of
automatic switched-beam antenna is constructed to confirm its performance.
Moreover, the validation of performance enhancement is investigated through
the signal strength measurements at the users operating in existing WLAN
infrastructure. The results confirm the advantage of switched-beam antenna
employing modified Butler matrix by improving signal strength with average
power of 4.37 dB over the use of omni-directional antenna.
Keywords: Antenna arrays, Beamforming, Butler matrix, Measurement, Signal
strength, WLAN
Title
of the Paper:
Implementation of Beam Formation for WMNs
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Authors:
M. Uthansakul, S. Pradittara, P. Uthansakul
Abstract: A low-cost beamformer capable of main beam and null locating is
proposed in this paper. This beamformer is suitable for WMNs as the positions
of mesh router are fixed. The beamformer consists of 2?2 rectangular array
spaced by λ/4 accompanied with a simple beamforming network. With multiplying
constant values to output signals from beamforming network, null locating can
be accomplished. Firstly, its beamforming capability is tested through
computer simulation. Then, a prototype of the beamformer is constructed and
tested to confirm its performance in term of signal strength, throughput and
delay. Also, the impact of position shift which mesh router is not located on
the expected beam direction has also been investigated.
Keywords: Antenna array, Beamforming, Null steering, WMNs
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