نتایج جستجو برای: jamming
تعداد نتایج: 3897 فیلتر نتایج به سال:
This paper is concerned with the relay and jammers selection in two-way cooperative networks to improve their physical layer security. Three different categories of selection schemes are proposed which are; selection schemes without jamming, selection schemes with conventional jamming and selection schemes with controlled jamming. The selection process is analyzed for two different network mode...
We investigate the existence of random close and random loose packing limits in twodimensional packings of monodisperse hard disks. A statistical mechanics approach— based on several approximations to predict the probability distribution of volumes— suggests the existence of the limiting densities of the jammed packings according to their coordination number and compactivity. This result has im...
From coffee beans flowing in a chute to cells remodelling in a living tissue, a wide variety of close-packed collective systems-both inert and living-have the potential to jam. The collective can sometimes flow like a fluid or jam and rigidify like a solid. The unjammed-to-jammed transition remains poorly understood, however, and structural properties characterizing these phases remain unknown....
We explore numerically the shear rheology of soft repulsive particles at large volume fraction. The interplay between viscous dissipation and thermal motion results in multiple rheological regimes encompassing Newtonian, shear-thinning, and yield stress regimes near the "colloidal" glass transition when thermal fluctuations are important, crossing over to qualitatively similar regimes near the ...
Due to its anti-jamming capability, chirp spread spectrum (CSS) technique has attracted much attention in the area of wireless communications. However, there has been little rigorous analysis for the anti-jamming performance of CSS-based communication systems. In this paper, we present analytic results on the anti-jamming performance of a CSS-based system: BER expressions are derived for a CSS-...
We study the flow of model hard-sphere colloidal suspensions at high volume fraction Phi driven through a constriction by a pressure gradient. Above a particle-size dependent limit Phi(0), direct microscopic observations demonstrate jamming and unjamming-conversion of fluid to solid and vice versa-during flow. We show that such a jamming flow produces a reduction in colloid concentration Phi(x)...
We answer the questions raised by Donev, Torquato, Stillinger, and Connelly (DTSC) in their preceding Comment on “Jamming at zero temperature and zero applied stress: The epitome of disorder” [Phys. Rev. E 70, 043301 (2004)] We emphasize that we follow a fundamentally different approach than they have done to reinterpret random close packing in terms of the “maximally random jammed” framework. ...
In this lecture we consider direct-sequence spread-spectrum systems. Unlike frequency-hopping, a direct-sequence signal occupies the entire bandwidth continuously. The signal is obtained by starting with a narrowband signal and directly modulating a high bandwidth signal. As with frequency hopping direct-sequence has advantages when the channel contains a jamming like signal. The jamming could ...
Jamming attack in wireless networks is a severe problem and is easily accomplished by emitting a continuous radio signal. Although the perfect solution to avoid jamming attack does not exist due to the nature of the wireless shared medium, a channel-hopping scheme is considered one of the most effective ways to mitigate jamming attacks. In this paper, I consider various channel-hopping schemes ...
This letter proposes a novel UAV-enabled mobile jamming scheme to improve the secrecy rate of ground wiretap channel. Specifically, a UAV is employed to transmit jamming signals to combat against eavesdropping. Such a mobile jamming scheme is particularly appealing since the UAV-enabled jammer can fly close to the eavesdropper and opportunistically jam it by leveraging the UAV’s mobility. We ai...
نمودار تعداد نتایج جستجو در هر سال
با کلیک روی نمودار نتایج را به سال انتشار فیلتر کنید