in this article, zno and zno:mn nanoparticles prepared by reverse micelle method. the various crystalline properties of these nanoparticles such as size, d-spacing, strain, stress, dislocation density and texture coefficient have been calculated with the help of xrd spectrum. the xrd results indicated that the synthesized zno and zno:mn nanoparticles have a pure wurtzite (hexagonal phase) struc...

A method to achieve high data rate transmission in a wireless military communications system is proposed. The scheme operates by periodically measuring energy over the span of the transmission band, and identifying spectral areas with low jammer and/or interference energy. A probabilistic algorithm is then used to adaptively define spectral regions in which a frequency-hopped spread-spectrum (F...

We examine numerically vortex families near band edges of the Bloch wave spectrum for the Gross-Pitaevskii equation with two-dimensional periodic potentials and for the discrete nonlinear Schrödinger equation. We show that besides vortex families that terminate at a small distance from the band edges via fold bifurcations, there exist vortex families that are continued all the way to the band e...

Chaotic signals must have specific characteristics in order to be used in certain applications. One of them is band-limited power spectrum. An approach to design of chaotic sources with band-limited feature is proposed. Realization of the approach in microwave band is demonstrated.

In this paper, the gain spectrum of EDFA has been broadened by implementing HTE configuration for S and C band. On using this configuration an amplification bandwidth of 76nm ranging from 1479nm to 1555nm with a peak gain of 26dB has been obtained. Keywords—C band, DWDM system, EDFA, Gain, HTE, Hybrid Fiber Amplifier, S band.

There has been considerable discussion surrounding the barriers to spectrum sharing in the literature. Among those is the `trust gap' that exists, according to the PCAST report. Trust is a complex human construct that signi cantly includes risk. In this paper, we examine the risks faced by the di erent user classes proposed by the FCC for sharing in the 3.5 GHz band. We argue that the invisible...

Cognitive radio technology enables improving the utilization efficiency of the precious and scarce radio spectrum. How to maximize the overall spectrum efficiency while minimizing the conflicts with primary users is vital to cognitive radio. The key is to make the right decisions of accessing the spectrum. Spectrum prediction can be employed to predict the future states of a spectrum band using...

Spectrum handover is a significant topic in the cognitive radio networks to assure an efficient data transmission in the cognitive radio user’s communications. This paper proposes a comparison between three spectrum handover models: VIKOR, SAW and MEW. Four evaluation metrics are used. These metrics are, accumulative average of failed handover, accumulative average of handover performed, accumu...

Spectrum handover is a significant topic in the cognitive radio networks to assure an efficient data transmission in the cognitive radio user’s communications. This paper proposes a comparison between three spectrum handover models: VIKOR, SAW and MEW. Four evaluation metrics are used. These metrics are, accumulative average of failed handover, accumulative average of handover performed, accumu...

The growing demand in mobile Internet access calls for high capacity and energy efficient cellular access with better cell coverage. The in-band relaying solution, proposed in LTE-Advanced, improves coverage without requiring additional spectrum for backhauling, making its deployment more economical and practical. However, in-band relay without careful management incurs low spectrum utilization...