29,721 research outputs found
Laboratory measurement campaign of DVB-T signal with transmit delay diversity
The requirements for future DVB-T/H networks demand that broadcasters design and deploy networks that provide ubiquitous reception in challenging indoors and other obstructed situations. It is essential that such networks are designed cost-effectively and with minimized environmental impact. The EC funded project PLUTO has since its start in 2006 explored the use of diversity to improve coverage in these difficult situations. The purpose of this paper is to investigate the performance of Transmit Delay Diversity (DD) with two antennas to improve the reception of DVB-T/H systems operating in different realistic propagation conditions through a series of tests using a SPIRENT SR5500 dual channel emulator. The relationship between correlation coefficient between channels, receiver velocity and diversity gain is nvestigated. It is shown that transmit delay diversity significantly improves the quality of reception particularly in simulated fast fading mobile broadcasting applications. This paper documents research conducted by Brunel University and Broadreach Systems
Signal and System Design for Wireless Power Transfer : Prototype, Experiment and Validation
A new line of research on communications and signals design for Wireless
Power Transfer (WPT) has recently emerged in the communication literature.
Promising signal strategies to maximize the power transfer efficiency of WPT
rely on (energy) beamforming, waveform, modulation and transmit diversity, and
a combination thereof. To a great extent, the study of those strategies has so
far been limited to theoretical performance analysis. In this paper, we study
the real over-the-air performance of all the aforementioned signal strategies
for WPT. To that end, we have designed, prototyped and experimented an
innovative radiative WPT architecture based on Software-Defined Radio (SDR)
that can operate in open-loop and closed-loop (with channel acquisition at the
transmitter) modes. The prototype consists of three important blocks, namely
the channel estimator, the signal generator, and the energy harvester. The
experiments have been conducted in a variety of deployments, including
frequency flat and frequency selective channels, under static and mobility
conditions. Experiments highlight that a channeladaptive WPT architecture based
on joint beamforming and waveform design offers significant performance
improvements in harvested DC power over conventional
single-antenna/multiantenna continuous wave systems. The experimental results
fully validate the observations predicted from the theoretical signal designs
and confirm the crucial and beneficial role played by the energy harvester
nonlinearity.Comment: Accepted to IEEE Transactions on Wireless Communication
73 GHz Wideband Millimeter-Wave Foliage and Ground Reflection Measurements and Models
This paper presents 73 GHz wideband outdoor foliage and ground reflection
measurements. Propagation measurements were made with a 400 Megachip-per-second
sliding correlator channel sounder, with rotatable 27 dBi (7 degrees half-
power beamwidth) horn antennas at both the transmitter and receiver, to study
foliage-induced scattering and de-polarization effects, to assist in developing
future wireless systems that will use adaptive array antennas. Signal
attenuation through foliage was measured to be 0.4 dB/m for both co- and
cross-polarized antenna configurations. Measured ground reflection coefficients
for dirt and gravel ranged from 0.02 to 0.34, for incident angles ranging from
60 degrees to 81 degrees (with respect to the normal incidence of the surface).
These data are useful for link budget design and site-specific (ray-tracing)
models for future millimeter-wave communication systems.Comment: 6 pages, 4 figures, 2015 IEEE International Conference on
Communications (ICC), ICC Workshop
- …