Volume 11, Issue 2, December 2011

Lab Interoperability and Carrier Acceptance Testing: Making the Case for Growing Importance and Emerging Strategic Role [Full Text]

Dominic B. Boamah and Erasmus Addae


Abstract—Wireless ecosystems continue to get complex with different network elements and connected devices manufactured by different companies. Navigating through such complex ecosystems is, and will continue to pose challenges to business professionals, and organiza-tions around the World that want to seize the opportunities provided by both legacy and state-of-the-art wireless technologies to engage their employees regardless of their location, or individuals who want to stay connected to their jobs, friends, and families whilst on the road. This paper discusses these challenges and the growing importance and strategic role of lab interoperability and carrier acceptance testing in deal-ing with these challenges by vendors and carries around the world.


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Analysis and Deployment of Virtual Honeypots to Tract Down Intrusions
[Full Text]

Armoogum V., Armoogum Sheeba, Sunhaloo S. and Jeewooth K.


Abstract—Security issue is the most important thing about a networking environment and computer systems. To know how secure a computer or a network is, systems need to be designed that can capture and log malicious attack. The log gives precious information on the sources of attacks and based on them, appropriate security measures can be taken. In order to achieve this, a system needs to be devised that purposely attract the bad guy to perform attack. This paper introduces the honeypot concept, which can be realized using an interesting tool like Honeyd that has the ability to set up multiple virtual honeypots on a single machine, each with different characteristics and services. A comparative study is made with other types of honeypots on different levels of interactivity. The system is implemented and demonstrated along with tests and analysis, which are performed using networking tools to verify its functionality.

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Performance of OFDM system Modified SLM Technique with DQPSK [Full Text]

Sonali A Bhagwatkar, B P Patil, and Prabha Kasliwal


Abstract— Orthogonal Frequency Division Multiplexing (OFDM) is one of the popular multicarrier modulation technique in
modern communication systems. Despite the benefits of the OFDM system one of the major drawback is that it exhibits very high Peak-to-Average Power Ratio (PAPR). At present many techniques are proposed to overcome the drawback of high PAPR. Out of which probabilistic techniques are the most popular due to their better performance. One of the popular
probabilistic algorithms to reduce PAPR of OFDM signal is Modified selected mapping technique, this paper focus on
comparative study and implementation of Modified selected mapping technique with DQPSK and QPSK scheme under AWGN channel. Simulation results of PAPR reduction and Bit Error Rate (BER) are shown and compared.

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Nmos Based Variable Phase Shifter for Phased Array Antenna Application [Full Text]

Tapas Mondal, Milan Mazumdar, Rowdra Ghatak and Sekhar Ranjan Bhadra Chaudhuri


Abstract— In this paper, we propose the design of a NMOS based reflective type variable phase shifter for phased array antenna systems pertaining to Dedicated Short Range Communication Services applications in the field of Intelligent Transport System at 5.88GHz. In this reflective type variable phase shifter, a quadrature microstrip hybrid coupler is used to avoid the undesirable impact of mismatch between the input and output impedances. To achieve the reflections, two symmetrical NMOS based circuits are connected at both the secondary and coupled arms of the branch-line hybrid coupler. The phase shift can be varied by controlling the capacitance value of the NMOS circuits. The phase shift can be controlled by changing the bias voltage up to 190° in the proposed circuit and up to 300° with additional complex circuitry. In either case, the DC power consumption is very less as well as the transmission loss is -7dB ±0.75dB. Hence the proposed circuit is well suited to construct the phased array antenna for Intelligent Transport System applications.

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Adaptive Kurtosis Detector for Impulse Radio Ultra Wideband OOK Scheme
[Full Text]

Javad Taghipour and Vahid Tabataba Vakili


Abstract—
On-off keying (OOK) is one of the modulation schemes for non-coherent impulse radio Ultra-wideband systems. In OOK signaling the threshold value for detection depends on SNR value and channel impulse response. In this paper, the utilization of the kurtosis detector (KD) receiver for OOK signaling is introduced. An approximation of threshold value is obtained by using Gumbel distribution function for KD receiver. Adaptive OOK is proposed by transmitting pilot data in data frames, and threshold value is updated in each frame by estimating SNR value and parameters of Gumbel distribution.

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New Turbo Decoding of Product Codes Based on Cyclic Codes [Full Text]

Idriss Chana, Hamid Allouch and Mostafa Belkasmi

Abstract—In this work, we present an improvement of a SIHO (soft In Hard out) algorithm for decoding cyclic codes changing two key parameters, the first parameter is the number of permutations where the second is the number of test sequences contributing in decoding process. The main purpose is to reduce the computational complexity by decreasing the number of mentioned parameters. Hence the resultant decoding algorithm will be considered as a component decoder to realise a turbo decoding of product codes based on cyclic codes. According to the computer simulations, three interesting results are obtained; the first one is that the performances, in terms of BER (Bit Error Rate) of the modified version are relatively similar to the original one. The second result is that the turbo decoding of several product codes outperform some other turbo deceder of linear block codes such as Chase-Pyndiah’s and Lucas’ alogorithm. The last one is that the proposed iterative SISO (Soft in Soft out) decoding algorithm provides a performance near the Shannon limit.

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FPGA based low power reconfigurable modulator with Digital Up Converter for adhoc networks
[Full Text]

Latha Sahukar and Dr. M. Madhavi Latha


Abstract—Modern communication networks are implemented with Adhoc network based topologies. At present the level of re-configurability in adhoc networks is limited up to TCP and IP layers for forming up networks, building up routing functionality etc. The progress made in communication system design by adapting based on channel conditions can give higher bandwidth wireless links with lower power consumption. Implementing such physical layer for mobile adhoc applications can result in more efficient networks. This work presents the reconfigurable modulator enabled with Digital Up Converter (DUC). The results demonstrate the proper functionality on Spartan 3E FPGA, reporting upto 78 MHz maximum clock operation with 80 mW power consumption.

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Simulation and modeling of a double negative structure by using the combination of Z-transform and TLM
[Full Text]

M. Rajabi and N. Komjani

Abstract— In this paper the transmission and reflection coefficients of a metamaterial structure are calculated using the transmission line matrix method (TLM). The effective electric permittivity and magnetic permeability of a split ring resonator/wire structure are extracted from 3D field simulation data, and then the structure is substituted by a homogenous slab as an equivalent representation of this metamaterial which described using the parameterized dispersive Drude and Lorentz model. Finally a combination of Z-transform and TLM method is exploited for simulating the equivalent dispersive model. The simulation results show a good agreement with the calculated ones from theory.

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Mathematical Modeling of different Photovoltaic Modules
[Full Text]

Mohammed Q. Taha, Qusay H. Eesse and Salih Mohammed Salih


Abstract— This paper presents a mathematical model for solar Photovoltaic (PV) cells and compares their performance to an existing model in renewable energy research center (RERC) at the University of Anbar-Iraq. The model is able to simulate both the I-V characteristics curves and the P-V characteristics curves and it is used to study different parameters variations that can affect on the PV array performance including operating temperature and solar irradiance level. The results of the PV characteristics curves are compared to the curves provided by Kyocera PV and Solara PV model datasheets. The results are extracted and simulated using the Matlab software. One-diode equivalent circuit is employed in order to investigate I-V and P-V characteristics of a typical 54 W and 100W solar modules. The simulation results will be used as a reference to compare the performance of both models under a dusty weather and also for comparing their performances by using the solar module simulator in our future work.

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The  Efficacy of Unused Bandwidth in the Performance of TDMA Networks [Full Text]

Rong Nan Chiou

Abstract—
In order to enhance the performance of TDMA LANs/MANs, this paper explores the efficacy of unused bandwidth in the performance of a TDMA network. MACs of the networks use the tight and loose approaches to control traffic (the TTC and LTC).In the paper, the average waiting time of TDMA nodes (the waiting mean) is analyzed to obtain the upper and lower bounds of the LTC waiting means. The upper bound is the theoretical waiting mean resulting from the TTC. The lower bound is the theoretical waiting mean of the LTC. Both bounds and the simulative LTC waiting means will be contrasted to explore the effect of added bandwidth on network performance. After simulations, two effects are manifested. One is that the efficacy of improving performance is relative to the transmitted traffic of nodes. The other is that the performance improved by added bandwidth can not be enhanced without restrain.

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TDMA FTTH Networks with Bus Topology [Full Text]

Rong Nan Chiou

Abstract—
The considerable concern about the high constructing and maintaining costs is the bottleneck of rapid and worldwide fiber-to-the-home (FTTH) deployment. However, it is also important to maintain high communicative performance of FTTH networks as suppressing the constructing and maintaining costs. In order to reduce the constructing and maintaining costs of FTTH networks, this paper proposed a bus structure with TDMA to constitute FTTH networks. Because the number of fibers used in the structure and the number of central offices required for the FTTH access network are simultaneously reduced, the constructing and maintaining costs of the bus FTTH network can be greatly suppressed. Based on the analysis of the waiting time on optical TDMA networks, traffic-control approaches are exploited to logically distribute medium access among optical network units (ONUs). Putting traffic-control approaches to use on FTTH networks can result in the ideal fair behaviour of networks. Hence, the FTTH networks can satisfy the commercial contracts agreed by customers and network managers. Otherwise, to implement traffic control on the proposed FTTH network can keep high performance from degradation even if the network is with full load.

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A New Dual Band Branch-Line Coupler with Stepped Impedance Transmission Line
[Full Text]

Mohammad Mahdi farahani and Mohammad Khalaj-Amirhosseini

Abstract—
A new dual-band branch-line coupler scheme is proposed based on the using stepped impedance transmission line. The new structure for quarter wavelength transmission line reduces the size of the dual-band branch-line coupler compared with conventional structures by using a special case of design. Also, it offers the possibility of the stubless dual-band operation for some special cases. For verification, a two 3-dB microstrip coupler operating at 1 / 2.35 GHz and 1/5.85 GHz is fabricated and measured. Simulated and measured results are in good agreement.