5,684 research outputs found
Sub-Nyquist Channel Estimation over IEEE 802.11ad Link
Nowadays, millimeter-wave communication centered at the 60 GHz radio
frequency band is increasingly the preferred technology for near-field
communication since it provides transmission bandwidth that is several GHz
wide. The IEEE 802.11ad standard has been developed for commercial wireless
local area networks in the 60 GHz transmission environment. Receivers designed
to process IEEE 802.11ad waveforms employ very high rate analog-to-digital
converters, and therefore, reducing the receiver sampling rate can be useful.
In this work, we study the problem of low-rate channel estimation over the IEEE
802.11ad 60 GHz communication link by harnessing sparsity in the channel
impulse response. In particular, we focus on single carrier modulation and
exploit the special structure of the 802.11ad waveform embedded in the channel
estimation field of its single carrier physical layer frame. We examine various
sub-Nyquist sampling methods for this problem and recover the channel using
compressed sensing techniques. Our numerical experiments show feasibility of
our procedures up to one-seventh of the Nyquist rates with minimal performance
deterioration.Comment: 5 pages, 5 figures, SampTA 2017 conferenc
The Edge of the Galactic Disc
As part of a stellar population sampling program, a series of photometric
probes at various field sizes and depths have been obtained in a low extinction
window in the galactic anticentre direction. Such data set strong constraints
on the radial structure of the disc. At the forefront of this "drilling"
program, very deep CCD frames probe the most external parts of the disc. Over
the whole effective magnitude range (18 to 25), all contributions in the
statistics which should be expected from old disc stars beyond 6 kpc vanish,
although such stars dominate by far at distances less than 5 kpc. This is the
signature of a sharp cut-off in the star density: the edge of the galactic disc
between 5.5 and 6 kpc. As a consequence, the galactic radius does not exceed 14
kpc (assuming =8.5). Colours of elliptical galaxies measured in
the field rule out the risk of being misled by undetected extinction.Comment: 8 pages, Besancon Observatory preprint n.
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