نتایج جستجو برای: antennas
تعداد نتایج: 14619 فیلتر نتایج به سال:
We consider a user-centric co-operative cellular network, where base stations close to a mobile co-operate to detect its signal using a (joint) linear minimum-mean-square-error receiver. The base stations, which have multiple antennas, and mobiles are modeled as independent Poisson Point Processes to avoid dependence on specific node locations. Combining stochastic geometry and infinite random ...
Recent advancements in the ubiquitous sensor network field have brought considerable feasibility to the realization of a ubiquitous society. A ubiquitous sensor network will enable the cooperative gathering of environmental information or the detection of special events through a large number of spatially distributed sensor nodes. Thus far, radio frequency identification (RFID) as an applicatio...
COOJA is a network simulator developed for wireless sensor networks. It can be used for high-level algorithm development as well as low-level device driver implementations for accurate simulation of wireless sensor networks before deployment. However, in a simulation Cooja assumes that the nodes are only equipped with omnidirectional antennas. There is currently no support for directional anten...
Abstract—In this paper, two radiation pattern-reconfigurable antennas are designed to operate near the frequency of 1.8 GHz. The geometry of the proposed antennas is symmetric with respect to the vertical center line. The electrical shapes of the antennas are composed of a monopole-loaded loop and an open wire. The open wire functions as either a director or reflector for the two antennas. Depe...
In this paper, a practical antenna selection (AS) scheme is investigated for downlink multiuser massive multiple input multiple output (MIMO) networks where a base station (BS) is equipped with many antennas (N) and communicates with K mobile stations (MSs) simultaneously. In the proposed antenna selection technique, S antennas (S ≤ N) are selected for transmission based on the knowledge of cha...
Linear precoding techniques can achieve nearoptimal capacity due to the special channel property in downlink massive MIMO systems, but involve high complexity since complicated matrix inversion of large size is required. In this paper, we propose a low-complexity linear precoding scheme based on the Gauss-Seidel (GS) method. The proposed scheme can achieve the capacity-approaching performance o...
This paper investigates the performance of two candidates for software radio WLAN, reconfigurable OFDM modulation and antenna diversity, in an indoor environment. The scenario considered is a 20m× 10m × 3m room with two base units and one mobile unit. The two base units use omnidirectional antennas to transmit and the mobile unit uses either a single antenna with equalizer, a fixed beamformer w...
In this paper, we have investigated printed monopole antennas, which is basically printed microstrip antenna with etched ground plane for UWB applications. In particular, we have simulated two types of UWB printed monopole antennas: circular and modified circular disk monopole antennas. Simple rectangular microstrip lines are used for feeding the printed monopole antennas. This UWB monopole ant...
Coplanar-strip horn antennas are switched photoconductively to generate picosecond bursts of freely propagating electromagnetic energy with bandwidth covering 15-75 GHz. The antennas are fabricated on GaAs grown by molecular beam epitaxy at low substrate temperatures. These antennas are used to perform transient scattering measurements from slit-coupled circular and coaxial cavities; Prony’s me...
We investigate the light emission from dipolar emitters located within nanoparticle antennas. It is found that the enormous emission enhancement can reach nearly a million fold. For multinanoparticle antennas, the polarization of the emissions strongly depends on the geometry of the antennas, the emitted wavelengths, and the dielectric functions of surrounding media. It is shown that a polariza...
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