Grouping Technique for Cooperative Spectrum Sensing in Cognitive Radios




Rizwan Akhtar, Adnan Rashdi and Abdul Ghafoor
Electrical Engineering Department, College of Signals, National University of Science & Technology, Pakistan


Abstract—

Cognitive networks can potentially solve the
problems of spectrum scarcity by accommodating unlicensed
(secondary) users in under-utilized segments of the spectrum.
Spectrum sensing serves as the primary stimulus for a cognitive
radio an ....etc

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ABSTRACT

A novel data-hiding methodology, denoted as digital invisible ink (DII), is proposed to implement secure steganography systems. Like the real-world invisible ink, secret messages will be correctly revealed only after the marked works undergo certain prenegotiated manipulations, such as lossy compression and processing. Different from conventional data-hiding schemes where content processing or compression operations are undesirable, distortions caused by prenegotiated manipulations in DII-based schemes are indispensable steps for ....etc

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Indian Telecom Scene- CDMA-vs-GSM or Spectrum technology

presented by:
b.b anand
president
Reliance Infocomm Ltd.
Vijaya Building, 13th Floor,17, Barakhamba Road,
New Delhi


Indian telecoms at current value

-India – a dynamic & vibrant economy - about 7 to 8 % GDP growth
-Tele density : Risen from less than 2% in 2000 to 8.80 %by Jan’2005
-Total subscribers base in India 94.92 million by the end of Jan’05.
-Wireless subscribers at the end of Jan’05 is ....etc

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1. Abstract
In recent time watermarking technique becomes a potential solution for copyright protection, authentication and integrity verification of digital media. Among the widely used watermarking techniques, spread spectrum modulation based method becomes appealing due to its inherent advantage of greater robustness and is used widely for various applications. Some watermarking applications, for example, digital television broadcasting, internet protocol television (IP-TV), etc. essentially demand development of ....etc

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Zoom-FFT Spectrum Analyzer
Presented By:
Ling Feng
s020983
Jinxu Huang
s021102

1. Introduction
Nowadays we contact with various signals everyday. We need to analysis and utilize these signals. In many situations there ....etc

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A PIPELINE FAST FOURIER TRANSFORM FOR DIGITAL SPECTRUM ANALYSIS

Abstract:- This paper describes a novel structure for a hardwired fast Fourier transform (FFT) signal processor that promises to permit digital spectrum analysis to achieve throughput rates consistent with extremely wide-band radars. The technique is based on the use of serial storage for data and intermediate results and multiple arithmetic units each of which carries out a sparse Fourier transform. Details of the system are described for data sample sizes that are binary multi ....etc

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Abstract:
Spread spectrum is a form of wireless communications in which the frequency of the transmitted signal is deliberately varied. This result in a much greater bandwidth than the signal would have if its frequency were not varied.A conventional wireless signal has a frequency, and are methods by which electromagnetic energy generated in a particular bandwidth is deliberately spread in the frequency domain, resulting in a signal with a wider bandwidth usually specified in megahertz (MHz) or gigahertz gigahertz), that doe ....etc

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Abstract
There are new system implementation challenges involved in the design of cognitive radios, which have both the ability to sense the spectral environment and the flexibility to adapt transmission parameters to maximize system capacity while co-existing with legacy wireless networks. The critical design problem is the need to process multi-gigahertz wide bandwidth and reliably detect presence of primary users. This places severe requirements on sensitivity, linearity, and dynamic range of the circuitry in the RF front-e ....etc

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1.1WHAT IS SPREAD SPECTRUM?
Spread-spectrum techniques are methods by which a signal (e.g. an electrical,electromagnetic, or acoustic signal) generated in a particular bandwidth is deliberately spread in the frequency domain, resulting in a signal with a wider bandwidth. These techniques are used for a variety of reasons, including the establishment of securecommunications, increasing resistance to natural interference and jamming, topreventdetection, and to limit power flux density (e.g. in satellite downlinks).
S ....etc

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1. INTRODUCTION
Code Division Spread Spectrum is one form of CDMA communication technique optimized for the cost conscious, high volume and short cycle consumer electronics market. Its primary application is in digital cordless telephony today. Meanwhile, it is being applied to wireless devices for the last 100-meter connection to the Internet, and in the wireless local loop to provide sub-$20 handset cost, tariff free mobile voice services in some third world countries.
Why is CD/SS technology suitable for consumer e ....etc

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