Volume 5, Issue 2, November 2010

Active-R Dual Input Integrator With Enhanced Time Constant Using a CDBA : Quadrature Oscillator Design [Full Text]

P.Venkateswaran, M. Kar, S.Das and R.Nandi

Abstract—
A new dual-input integrator using a current differencing buffered amplifier (CDBA) element is presented ; the circuit needs a grounded capacitor and the time constant (τ ) has an enlargement factor being tunable by a single resistor. A sinusoid quadrature oscillator is realized thereafter with a double-integrator loop involving two such integrators. The designs are tested satisfactorily in a frequency-range of 1MHz-20MHz by both hardware implementation and PSPICE macromodel simulation.


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Analysis of Sierpinski Gasket Tetrahedron Antennas
[Full Text]

M. Alaydrus

Abstrac
t—Sierpinski gasket fractal antennas are introduced some years ago showing multiband characteristics. Three dimensional Sierpinski gasket antennas are three dimensional extensions of those antennas, so that instead of triangles, we have tetrahedrons, arranged in a certain fashion. The structures are analyzed by surface integral equation method, the results show; they have also multiband characters, however with wider resonant regions. The effects of finite ground to the reflection factor of the antennas are also taken into account. Comparison between the calculation results with measurements shows good agreement.

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Analyze the Performance of Cellular IP Networks
[Full Text]

Mohammad Shahidul Islam

Abstract
— Mobile networks and the Internet are converging. This convergence challenges the QoS provisioning in such mobile IP networks. The future mobile Internet will include many portable devices connected to the global network. In order to achieve higher bandwidth for the users, the cell size will have to be limited. That leads to the creation of microcellular, or even picocellular environments, where the users move frequently among cells. This paper addresses problems that arise from the integration of mobile networks and the Internet, which are mainly due to user mobility. Also analyze the impact of handovers on different traffic types, such as CBR, VBR, as well as best-effort traffic.

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A Comparison of Proactive and Reactive Multi-hop Routing Protocols for Mobile Ad Hoc Networks
[Full Text]

Foez Ahmed, Md. Shariful Islam, and Nayeema Islam

Abstract—
Wireless communication technology is increasing daily; with such growth sooner or later it would not be practical or simply physically possible to have a fixed architecture for this kind of network. Ad hoc wireless network must be capable to selforganize and self-configure due to the fact that the mobile structure is changing all the time. Mobile hosts have a limited range and sending the message to another host, which is not in the sender’s host transmission range, must be forwarded through the network using other hosts which will be operated as routers for delivering the message throughout the network. To accomplish this communication, a routing protocol is used to discover routes between these hosts. This paper presents a variety of
comprehensive simulation results for two popular protocols – Dynamic MANET On-demand (DYMO) and Optimized Link State Routing (OLSR) using NS2. Both two protocols are provided with identical traffic load and mobility patterns. We have considered TCP as transport protocol and FTP as traffic generator. The analysis is significant because we considered near about all the metrics as suggested by RFC 2501 and till to-date there are a few comparisons based on TCP.

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Performance Analysis of an Efficient Wireless Communication System in AWGN and Slow Fading Channel
[Full Text]

M. S Miah, Dr. M. M Rahman, T. K Godder and B. C Singh

Abstract—
In this paper, first build up a wireless communication simulator including Gray coding, modulation, different channel models (AWGN, flat fading and frequency selective fading channels), channel estimation, adaptive equalization, and demodulation. Next, test the effect of different channel models to the data and image in receiver with constellation and BER (bit error rate) plots under QPSK modulation. For Image data source, we also compare the received image quality to original image in different channels. At last, give detail results and analyses of the performance improvement with channel estimation and adaptive equalization in slow Rayleigh fading channel. For frequency selective fading channel, use linear equalization with both
LMS (least mean squares) and RLS (Recursive Least Squares) algorithms to compare the different improvements. We will see that in AWGN channel, the image is degraded by random noise; in flat fading channel, the image is degraded by random noise and block noise; in frequency selective fading channel, the image is degraded by random noise, block noise, and ISI.

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Brain Chip Implants: Controlling Movements with Thought Alone: The Impossible Becomes Reality
[Full Text]

Ahmed Elmorshidy

Abstract –
This paper defines and discusses the break-through technology of brain implants. Brain implants, often referred to as neural are technological devices that connect directly to a biological subject's brain. The paper explains how the link between the computer chip and the human brain is established, and how things that used to be in the science fiction movies has now become reality such as controlling movements through thought only and giving orders to the computer through the brain directly without any other interference from the human body. The paper also discusses the vital implication of this technology in the healthcare industry and the hope that this technology gives to paralyzed patients interact with their environments and perhaps, ultimately, to bypass damaged spinal cords and restore movement to lifeless limbs.

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Future Prospects of MIMO in Wireless Communication
[Full Text]

Nirmalendu Bikas Sinha, Kaustav Chowdhury and Deepak Kumar

Abstract—
The so-called diversity-multiplexing trade-off characterizes the fundamental interaction between the robustness and capacity gains obtainable from multiple-input and multiple-output (MIMO) systems in fading environments. This paper develops practical schemes for approaching the optimal trade-off in various delay and complexity regimes. We focus on a two-transmitter and two-receiver antenna system, in which the receiver has channel knowledge, but the transmitter does not. We present a geometric view of the signal design problem. This view reveals how training based approaches can achieve the optimal (non-coherent) diversity-multiplexing tradeoffs. In this paper, the authors analyses the system parameters (types of the channel, modulation, channel diversity and suitable coding scheme) which play a pivotal role in 4G communication system. Simulation results demonstrate that MIMO system can provide better performance when efficient coding, modulation and proper selection of antenna diversity order is used. In contrast with traditional communication, the superiority of MIMO in next generation signal processing is established.

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Pattern Steering Double Square Loop Antenna
[Full Text]

Arun Raaza , K. Anbudurai, S. Ravi and S. P. Rajagopalan

Abstract
A novel method of producing and switching multiple beams using double square loop (DSL) antenna is proposed. By switching either the eight active outer or inner feed points, the pattern can be steered at a coarse step of 45° throughout the 360° of space and the associated beam can be directed in eight directions, thus offering a wide range of options for modern wireless devices to focus the beam at a desired target direction. Furthermore, with varying permittivity value of dielectric substrate, the DSL produces axial and tilted beams of fine varying degree of elevation. The variation in the permittivity can be achieved electronically by using substrates made up of materials such as liquid crystals or ferro-electric materials (Barium Titanate, Barium Strontium Titanate or Lead Titanate) which may be constituted in a fine grained random polycrystalline or a ceramic form. The average gain of antenna beams is 8.3dBi. The beam steerable DSL antenna is designed to operate in the frequency band of 2.5 GHz to 5.8 GHz and is very likely to have direct applications in high data rate systems such as UWB, WIMAX and 4G networks.

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Optimized LNA Structure for Pulse-Radar Receiver Applications [Full Text]

Mohammad Reza Salehi, Ebrahim Abiri, Ali Shourvarzi, Mohammad Bagher Jowkar, and Seyed Mehdi Oladali

Abstract—
Analysis of different structures for LNAs is described. First, the voltage gain for common-source and cascode structure LNAs will be studied. Then, using CGD neutralization technique by center-tapped inductor, the detrimental effect of the gate-drain internal capacitor, in the common-source structure will be counteracted. A novel structure with the combination of this technique and cascode structure is inroduced. The result shows the voltage gain, in the 6.5-10-GHz radar band, is increased. The effect of this neutralization on noise and reverse isolation is discussed.


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Moving Target Identification for Coherent MIMO Radar [Full Text]

Nirmalendu Bikas Sinha, Priyabrata Ray and Abhishek Mitra

Abstract—
Motivated by the success of MIMO concept in communication, in this paper the authors deal with the prediction of moving target for coherent spatial diversity MIMO based pulse radar. MIMO radars have better detection performance and can extract target information more precisely than other known pulse radars. Based on coherent processing one decision rule is utilised for detection of target with unknown amplitude embedded in Additive White Gaussian Noise (AWGN) with known power using the Generalized Likelihood Ratio Test(GLRT) and then performance of these detectors have been evaluated analytically using swerling model 1 for moving target identification. We also analyze the diversity gain which we define as the rate that the probability of mis-detecting a target decays with the increasing SNR and show that for a MIMO radar system, with the increase in the number of pulses, the detection performance of Swerling I target are both improved. Simulation results demonstrate that MIMO radar can get better detection performance when more coherent pulses is used. In contrast with conventional radar the detection superiority of the MIMO radars for moving target with temporal coherent processing is established.