in this article, the effect of cells' radius on the behavior of wavelength switching optical filter andthe effect of the radius of the optical filters' key characteristics such as wavelength resonance onan optical filter based on photonic crystals, have been investigated. currently, the most commonapplied mechanism for designing optical filter based on photonic crystals is using twome...

Abstract— In past few years wireless communication has attracted numerous researchers to make this field more advance day by day. For that the proper utilization of available frequency band is the prime and challenging task. The identification of vacant frequency band i.e. spectrum sensing problem gives the new aspects through cognitive radio with opportunistic spectrum access concepts. In this...

Cognitive radio (CR) is a new paradigm that utilizes the available spectrum band. The key characteristic of CR system is to sense the electromagnetic environment to adapt their operation and dynamically vary its radio operating parameters. The technique of dynamically accessing the unused spectrum band is known as Dynamic Spectrum Access (DSA). The dynamic spectrum access technology helps to mi...

The “shortage” of radio spectrum is usually attributed to the scarcity of spectrum, but it is due to the inefficiency of radio technologies and spectrum management. Regulatory reforms are being proposed to assign exclusive rights to spectrum, but such reforms would be harmful because the spectrum is not a property but a protocol by which information is carried. New packet radio technologies ena...

It is often assumed in system analyses that a partial-band noise jammer against a frequency-hopped M-ary frequency shift keying (FHMFSK) communication system has a rectangular spectrum. The rectangular spectrum is, of course, unrealizable, and so it is of interest to consider more realistic spectrums, such as those where a jammer uses a bandpass filter before amplifying the jamming noise. In th...

in this paper, a new design of optical channel drop filter based on two- dimensional photonic crystal ring resonators with triangular lattice is proposed. the rods of this structure is silicon with the refractive index nsi=3.46 and the surrounding environment is air with the refractive index of nair=1.the widest photonic band gap obtains for the filling ratio of r/a = 0.2. the filter’s transmis...

In the developing world, the usage of Mobile phones and other data communication devices are unavoidable which results in the congestion of Spectrum. Recent studies have showed that nearly 70% of spectrum was unused most of the time. The band width becomes expensive due to shortage of frequencies. Therefore to use the spectrum effectively, we need to identify whether the spectrum is occupied or...

Data traffic demand in cellular networks has been tremendously growing and has led to creating congested RF environments. Accordingly, innovative approaches for spectrum sharing have been proposed and implemented to accommodate several systems within the same frequency band. Spectrum sharing between radar and communications systems is one of the important research and development areas. In this...

The radio frequency spectrum is a scarce natural delivers and its efficient use is a of the utmost importance. The spectrum band is a usually licensed to certain services, such as mobile fixed broadcast, and satellite, to avoid harmful interference between different networks. Most spectrum band is a allocated to certain services but worldwide spectrum occupancy measurements show that only porti...

cadmium oxide (cdo) nanoparticles were prepared by precipitation method using cadmium acetate and ammonia solution. presence of chemical species, were verified by fourier transform infra red (ftir) spectrum. from x-ray diffraction (xrd) spectrum the particle size, d-spacing value and structure of the nanoparticle were analysed. size of the nanoparticles and the elemental composition were detect...