Editorial
Board
Prof. P.Ekel (Brazil),
Prof. Y.Li (Taiwan),
Prof. V.Mladenov (Bulgaria),
Prof. G.Bognar (Hyngary),
Prof. A.Zemliak (Mexico),
Prof. Lotfi A. Zadeh (USA),
Prof. Leonid Kazovsky (USA),
Prof. Nikos Mastorakis (GR),
Prof. S. Kartalopoulos (USA),
Prof. Z.Bojkovic (Serbia),
Prof. Ana Madureira (Portugal),
Prof. M.Sugeno (Japan),
Prof. J.C.Quadrado (Portugal),
Prof. A.Caballero (USA),
Prof. Lin Feng (Singapore),
Prof. M.Garcia-Planas
(Spain)
Topics
All aspects of contemporary computers and communications and their
applications are covered including technology, multimedia systems, hardware and
software systems, networking, wireless communications, microwaves, antennas,
radar, propagation, scaterring, in general applied electromagnetics, signal
processing, microcomputer applications such as engineering, science, business,
management, robotics, manufacturing, medicine, bioinformatics, systems biology
and personal computers. It appears quarterly.
Special Issues are specially encouraged.
Format
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Issue 1, Volume 2, 2008
On the Level-Crossing Probability in a Queue with
Autcorrelated Arrivals
by Andrzej Chydzinski, Lukasz Chrost
Abstract:
In this paper the probability that the queue size is kept below some threshold
in time interval of a given length is studied. In particular, a formula for this
probability is shown in terms of generating functions. In addition to analytical
results, a set of numerical results is presented. These numerical results reveal
a surprising phenomenon. Namely, when the arrival process is strongly
autocorrelated, the level-crossing probability may depend very little on the
system load. As IP traffic is often strongly autocorrelated, it is likely that
this phenomenon may be observed in queues of packets in Internet routers.
Keywords:
Level-crossing probability, single-server queue
Full Paper, pp. 1-9
A Source Code Generator Based on UML Specification
by Kresimir Fertalj, Mario Brcic
Abstract: This paper presents a application generator based on UML specification. The tool is capable of generating the source code in various programming languages from the same specification. The main characteristics of the existent tools are explained in brief. Main generator capabilities and merits are presented as well as an example of usage based on a relatively simple scenario. The tool extensibility is described as a mean of making the tool to suit a wide range of needs.
Keywords:
Application generator, CASE, source code templates, UML, XML/XSL transformations
Full Paper, pp. 10-19
A Novel Method to Modify VAD used in ITU-T G.729B for Low
SNRs
by H. Farsi, M. A. Mozaffarian, H.
Rahmani
Abstract:
Voice Activity Detection (VAD) Systems have various standards. One of the famous
and practical standards is ITU-U G.729B. In G.729B, VAD decision, compare with
other standards and new methods, has poor performance for voice frames
especially in low Signal-to-Noise Ratios (SNRs). However, since this standard
has good properties that we try to modify its low performance in adverse
environments. One point that we focus on this standard is trying to have minimum
changes. Therefore we use some new methods without major modification on basic
structure. In this methodology we use some parameters in the first part and
connect it to the main block.
We compare the proposed method, using objective parameters, with basic version
of G.729B standard and ETSI AMR option 1 and 2. This comparison study in various
types of noises like Gaussian, Vehicle and Babble noise.
Keywords:
Geometrically Adaptive Energy Threshold, LPFing method, Periodicity Estimation,
True Envelope LPC, Voice Activity Detection
Full Paper, pp. 20-29
Performance Analysis of TCP Congestion Control Algorithms
by Habibullah Jamal, Kiran Sultan
Abstract: The demand for fast transfer of large volumes of data, and the deployment of the network infrastructures is ever increasing. However, the dominant transport protocol of today, TCP, does not meet this demand because it favors reliability over timeliness and fails to fully utilize the network capacity due to limitations of its conservative congestion control algorithm. The slow response of TCP in fast long distance networks leaves sizeable unused bandwidth in such networks. A large variety of TCP variants have been proposed to improve the connection’s throughput by adopting more aggressive congestion control algorithms. Some of the flavors of TCP congestion control are loss-based, high-speed TCP congestion control algorithms that uses packet losses as an indication of congestion; delay-based TCP congestion control that emphasizes packet delay rather than packet loss as a signal to determine the rate at which to send packets. Some efforts combine the features of loss-based and delay-based algorithms to achieve fair bandwidth allocation and fairness among flows. A comparative analysis between different flavors of TCP congestion control namely Standard TCP congestion control (TCP Reno), loss-based TCP congestion control (HighSpeed TCP, Scalable TCP, CUBIC TCP), delay-based TCP congestion control (TCP Vegas) and mixed loss-delay based TCP congestion control (Compound TCP) is presented here in terns of congestion window verses elapsed time after the connection is established.
Keywords:
Congestion control, High-speed networks, TCP
Full Paper, pp. 30-38