BES Journal

Journal
2011
A Rigorous Taxonomy Based Survey of Location Systems for Ubiquitous Computing
Md. Tarek Habib , Abdul Halim Miah and Farruk Ahmed
Emerging ubiquitous computing applications must know where things are physically located. To meet this must, many different location systems and technologies have been developed. In this work, we discuss the basic techniques used for location detection, describe taxonomy of location system features, present a survey of research and commercial location systems, and finally, compare these location systems using the identified features. It is our hope that this paper is a useful reference for a newcomer to the area of location detection for understanding and evaluating the many options in this domain.
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Design & Development of a Microcontroller Based High-Efficient Smart Solar Charge Controller for Standalone Solar Photovoltaic Systems
Galib Hashmi, Manjurul Alam Dipon and Md. Habibiur Rahman
In this work a 120A, 24V charge controller has been designed and developed. As the solar energy is costly, measured has been taken to minimize the loss of the controller. PIC16F72 microcontroller has been used as the main controlling unit of the system. To minimize the loss, four 60A relays have been used. The battery status has been sensed by the ADC unit of the microcontroller. The high voltage regulation point and the PV reconnect point can be set any voltage level by adjusting two presets. Hence, the hysteresis can be controlled. The system is capable of displaying the battery voltage status on LED level meter or on LCD display. The controlling program of the system has been developed using FlowCode software. The controller is being tested in a solar PV system and it is found that the total loss of the controller is only 3Watt while it can control a system of 2880Watt.
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Design and Implementation of an Interfacing Technique Between The Microcomputer and A Three-Phase Induction Motor Control System
Md. Aziz Ul Huq and Farruk Ahmed
The speed of a three-phase induction motor can be varied within a wide range other than its rated value if its input parameters are varied properly. For industrial and some other sophisticated use of three-phase induction motor, precise and accurate control of the speed of the motor is necessary. Introduction of microcomputer and associate of software programs in three-phase induction motor control system as proposed is accurate and reliable in terms of accurate and complex speed control of the motor. In the present work an interfacing circuit, and associated software program is designed, developed and implemented through which microcomputer can read motor speed and can write codes to the control circuit to set the motor speed. Interfacing circuit is connected to the IBM microcomputer through I/O slot and program is written in C language. Transistorized infrared opto coupler is used to sense the motor speed in the place of conventional techo generator yielding faster and more accurate speed sensing capability. During the write action accurate input voltage is set for Voltege Controlled Oscillator(VCO ) through D/A converter and motor input voltage is set via digitally controlled AVR.
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A Simulation Based Performance Evaluation of VoIP
Nazmul Hossain, Md.Liakat Ali , Belayet Hossain Md. Abu Saleh and Md.Mirza Golam Rashed
All the Communication Technologies of the modern age are going through a change which is termed as “Convergence” and IP is playing the role of the backbone of this trend. VoIP is one of blessings of this IP based communication trend though it has still so many demerits in terms of QoS degradation including Codec Compression, Packet Loss, Discarded Packets, Bit Errors, Frame Erasures and various compression schemes. This paper delivers an experimental study which evaluates the performance of VoIP by monitoring the different QoS parameters. The parameters which are aimed to take into consideration in this experiment are Delay, Jitter, Packet Loss and MOS observed by the end user.
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A Higher Level Technique for Secured Message Transactions
Anisur Rahman , M. Ismail Jabiullah and M. Lutfar Rahman
A higher level secured message transaction technique has been designed, developed, analyzed and implemented for vulnerable communication channels. For this, a plaintext message is converted by using asymmetric key algorithm RSA and one-time pad as symmetric key algorithm to the ciphertext message. Three levels of encryption processes are imposed to produce the ciphertext that is to be sent to the destination. First, the original message is encrypted by the private key of RSA algorithm of the sender and then the output of the first encryption is again encrypted with the public key RSA algorithm of the targeted receiver and finally the output of the second encryption is further encrypted by using a shared secret key using one-time pad algorithm. After the above three encryptions a final ciphertext is generated that is to be sent to the receiver through the communication channels. In the receiving end, the receiver first decrypts the ciphertext by the shared secret key using one-time pad algorithm. Later, the receiver again decrypts the output of the first decrypted message with receiver’s private key and RSA algorithm. Finally, the receiver decrypts the output of the second decryption process with the public key of the sender produced by RSA algorithm; and hence retrieves the original plaintext message successfully. In this process, shared secret-key and private-public key of the communicants establish the confidentiality, authentication, authorization and non-repudiation in the message transactions that ensures the stronger security of the message transactions between the sender and receiver. It can be applied where a stronger security service of the communicating messages are needed.
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Multi-Envelop Polarization Shift Keying Modulation for Digital Optical Communications
Md. Shariful islam and Pallab Kanti Podder
In this paper, a multi-envelop polarization shift keying (POLSK) modulation scheme for digital optical communications is proposed newly. Two multi-envelop 16-ary constellation structures are showed and applied to the digital optical communication systems. In this transmission scheme, a multiple state of polarization (SOP) is used as the carrier of information. The performance of bit error rate (BER) of the proposed systems are also computed and analyzed in the additive white Gaussian noise (AWGN) environment. Two kinds of receivers, containing the conventional coherent detection (CD) based on Stokes parameters and the direct detection (DD) using maximum likelihood (ML) rule, are exploited to demodulate the polarized optical signals. The theoretical values and experimental values are compared. Computer simulation results indicate that the experimental results of the proposed system are very similar to the theoretical values. And the system performance using DD receiver is better than the CD receiver for the multi-envelop POLSK modulation scheme if a special constellation structure is adopted.
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Design and Development of a Cost Effective Laser Ray Touch Screen Technology
Md. Ariful Islam, A. K. M Fazlul Haque , M. Shahjahan Ali and Moheuddin Ahmed
This paper presents the new laser ray cost effective touch screen technology is to create a touch screen that is easily operated by the users without training the touch screen can be portable and movable without display system. A touch screen technology has been developed which is used to operate a computer for opening all folder by only a single touch on the screen. This work is divided into two main sections. One is hardware section which consists of a personal computer, voltage divider circuit, LDR, and Laser light source. And the other is the program control unit. This program has been written with visual basic language. Laser light has been used as the light source and LDR has been use as sensor. In its inactive mode laser light falls directly on the LDR which intern produces low voltage (logic 0) and when some obstacles (egg, human finger or stick etc) are in front of the light source , no light or very small light falls on the LDR which then produces high voltage (logic 1). In other words, this circuit gives a Low voltage when the LDR is in the light and a high voltage when the LDR is in the shade. The voltage divider circuit gives an output voltage which changes with illumination. In this way, eight LDRs produced an 8 bit signal such as 10001111, 11001111 etc. The voltage across LDRs is directly connected to the printer port (10, 11, 12, 13and 15) of the CPU. Finally, it is found that the proposed technology is better than the other existing technique.
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Locating Mobile Station Using Received Signal Parameters
Ahmed Lutful Kabir , Rajeeb Saha , Md. Arman Khan , Munawwar M Sohul and Farruk Ahmed
The importance of tracking a Mobile Station (MS) came into account after the act by Federal Communication Commission (FCC) on 1999. Emergency mobile phone services and Location Based Services (LBS) are the results where the MS has to be identified within a standard range. There are several approaches for tracking MS. The main aim of this paper is to find the position of a MS in a particular cell, by the distance calculation between Base Station (BS) and MS, also the mitigation of this with the angle of arrival (AOA).
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Approximate BER Performance Comparison of Frequency and Time Domain DQPSK/OFDM Systems Over Fading Environment
Mohammed Hossam-E-Haider and Waziha Kabir
The transmission quality in mobile wireless communications is affected not only by additive white Gaussian noise, but also by multipath fading, which drastically changes the amplitudes and phases of wireless signals. This paper proposes the derivation method of the BER in DQPSK/OFDM systems over frequency selective fading channels. In this study the approximate equation of BER with differential coding/differential detection in time domain and frequency domain with delayed waves have been derived. Simulation results confirmed that the proposed approach is applicable to a variety of parameters, such as Doppler frequency shift, delay spread, Rician factor and so on.
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Design and Implementation of a Smart Energy Meter with Data Sending Ability
Fatima Binte Zia and Khosru M Salim
In this paper the authors proposed and implemented a smart energy meter with data sending ability. At first a brief review about the definitions and procedure to measure the energy consumed from a single phase line. Whole model is developed starting from the proper measurement of current and voltage and their fluctuating behavior is taken into account. . Then a design of experiment that allows testing the energy meter. The design ensures exact calibration and display of the measured values with a software implemented by a microcontroller. A cell-phone using cellular network sends data of energy consumption. Finally, the complete hardware and software system that allows sending the data is presented in this document.
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Distance Dependent Service Differentiation of the IEEE 802.11e EDCA on Single Access Point Based WLAN Systems
N. M. Shafiul Kabir Chowdhury, Md. Shahriar Hussain, Afroza Sultana and Farruk Ahmed
The IEEE 802.11e Enhanced Distributed Channel Access (EDCA) protocol allows class based differentiated Quality of service (QoS) in a wireless local area network (WLAN). Different fixed values of two certain parameters; contention window (CW) and arbitration inter frame space number (AIFSN), ensure higher or lower priority among this traffic classes, administrating different QoS in terms of throughput, delay, jitter etc. Previous simulation study illustrated, superior throughput and delay performance achieved by the highest priority voice traffic, compared to whatever achieved by the lowest priority background traffic; according to the deliberate design of the IEEE 802.11e EDCA protocol. In this paper, we present our simulation study of the EDCA mechanism; augmented with the International Telecommunication Union (ITU) indoor propagation model, solidifying the outcome by ensuring an indoor or semi-indoor setup like todays real world WLAN system’s deployment scenarios. Simulation study shows that a node accessing highest priority traffic through an AP from a high distance at high data rate not only suffers performance drops itself but also severely bottlenecks the performance of other client nodes accessing traffics with comparatively lower priority, even if those nodes are at close proximity from the AP. However, the negative impact over other traffic accessing nodes are much lower but not fully negligible, when a client node through the AP, tries to access lower priority traffic from a large distance. Hence, the intended service differentiation over different traffic classes closely depends on whether all the client nodes are at a close proximity from the AP.
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Study of the Structural and Magnetic Properties of CuFe2O4 Nano Particle Prepared by Chemical Co-precipitation Method
Sakia Shabnam Kader, Shaikh Manjura Hoque, Deba Prasad Paul, A. K. M Fazlul Hoque and Faizus Salehin
The properties of the CuFe2O4 nano particle prepared by chemical co-precipitation have been studied. The XRD result of the as dried and samples calcined at different sintering temperature has shown that the single phase has been observed in the as dried condition and there is no observation of extra peak. The grain size has been obtained from Scherrer’s formula and found as 4nm to 56nm for the CuFe2O4 nano particle sample with the systematic variation of sintering temperature. The variation of lattice parameter with sintering temperature has been presented. The general increase in lattice parameter throughout the entire range of sintering temperature is due to the deviation in cation distribution in the spinel structure of CuFe2O4. Nano particle has been characterized to understand the magnetic properties from the observation of hysteresis loops.The initial permeability varies with sintering temperature due to the variation in kinetics of diffusion which depends on the particle size of the starting material. The Curie temperature has been measured from the result of temperature dependent initial permeability.
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Characterisation of PIXE facilities at the 3 MV VDG Accelerator Laboratory of Atomic Energy Centre Dhaka
Md. Joynal Abedin , Shirin Akter , Asad Shariff , A. K. M. Fazlul Hoque, S M Azharul Islam and Dilder Hossain
A new beam line and ion beam analysis (IBA) facility has been designed and constructed at the left beam line of the 3 MV Van de Graaff accelerator facility of BAEC. The goal is to perform standard ion beam techniques such as Proton Induced X-ray Emission (PIXE), Proton Induced Gamma Emission (PIGE), Rutherford Back Scattering (RBS) spectrometry, Nuclear Reaction Analysis (NRA), etc. with a millimeter size beam. A full calibration of the PIXE set-up in this chamber has been done with different thin and thick standards following the H-value method devised by GUPIX, where H is the solid angle plus the correction factor needed for the set-up to produce accurate concentration value. The energy dependant H-values were stored in the GUPIX library, to be used for PIXE analysis. The PIGE and RBS set-up has been also calibrated with known gamma and alpha sources and are ready for experiment.
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A Method For Theoretical Estimation of Maximum Achievable Throughput For The IEEE802.11e EDCA Mechanism
Md. Shahriar Hussain , N. M. Shafiul Kabir Chowdhury and Farruk Ahmed
The IEEE 802.11e Enhanced Distributed Channel Access (EDCA) is the distributed channel access mechanism introduced by an amendment to the original IEEE 802.11 standard. Edca provides a class-based differentiated quality of service (QOS) to ieee 802.11 wlans. This paper presents a formula to find out the maximum achievable throughput theoretically for ieee802.11e edca mechanism. To avoid complexity, some assumptions are made. For simulation purpose, different packet sizes for different access categories (ACS) are observed. We find that, deviation between theoretically achieved values and observed values from simulations are very close.
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Throughput Analysis of IEEE802.11b Wireless LAN System
Sheikh Md. Rabiul Islam
Wireless Local Area Networks (WLAN) has proliferated in the last few years. This was possible due to the low cost of the Access points (AP) and PC cards and also due to the ease of installation of the network. However utilizing the capabilities of the system in providing a better service to the end user has been a huge concern. Improper network planning, security concerns, higher bandwidth requirements are some of the areas that are being worked on in both the academia and the industry. The goal of this work is to show the Access point configuration and performance analysis of 802.11b using NCB Access Point (AP) in laboratory. Using wireless Access Point (AP) connecting with Server, used WLAN facilities with satisfactory performance. The performance analysis of data transmission with UDP protocol and use Iperf for the analysis in the Linux operating system. This paper concern how does the set-up of the AP, server and the clients and to simulate over the client to access point and compare the theoretical throughput and practical throughput of IEEE802.11b from the simulation result.
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Estimation of Timing Offset Error in OFDM System and Selecion of Modulation Technique for Best Performance
Md. Amir Ali Hasan , Amith Khandakar , Faiza Nabita , Sayeed Islam , Imtiaz Ahmed , Imran Ahmed , Farruk Ahmed and Md. Abdullah Al Zobaiba
This paper proposes an idea of developing a model of estimating timing offset error of OFDM (Orthogonal Frequency Division Multiplexing) system without the use of additional pilots relying on inherent characteristics of the OFDM signal. An analytical expression has been derived and formulated to analyze the effect of bit error rate (BER) due to timing offset introduced by the transmission channel. This will help in determining the exact length of cyclic prefix to be added to each OFDM symbol to avoid misinterpretation by the receiver. The performances have also been evaluated under coded (convolution) and uncoded systems. The introduction of channel coding decreases this basic impairment of OFDM systems significantly. Simulated results show that the symbol error rate (SER) linearly depends on timing offset. Finally, using Matlab simulation a comparison among the three modulation techniques is done and found that BPSK gives the best bit error rate performance at the present of timing offset error. It is expected that further works on the proposed estimated method will lead to a standard model so that at the receiving end the effect of timing offset can be eliminated totally.
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Analysis of 802.11 Frames using Wireshark
Sheikh Md. Rabiul Islam
IEEE Standard 802.11 defines a medium access control and physical layer specifications for wireless local area networks (WLANs). The aim of the experiment is to Packet analysis, often referred to as packet sniffing or protocol analysis, to describe the process of capturing and interpreting live data as it flows across a network in order to better understand the network condition. For analyzing the 802.11 packet, we choose 802.11b which is a supplement of standard 802.11 introducing a higher-speed physical layer extension. Packet analysis is typically performed by a packet sniffer, a tool used to capture raw network data going across the wire. For the experiment in wireless laboratory we have used Wireshark, a sophisticated wireless protocol analysis support to help administrators troubleshoot wireless networks. With the appropriate driver support, Wireshark can capture traffic “from the air” and decode it into a format that helps administrators track down issues that are causing poor performance, intermittent connectivity, and other common problems.
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