26,872 research outputs found
Reliable Download Delivery in a Terrestrial DAB Network
Reliable file transfer is important in broadcast networks. In this paper, we have investigated if it is useful to extend the DAB standard with Fountain codes. To evaluate this, results from measurements in a live Single Frequency Network
(SFN) were used. Our results show that the existing error correction algorithms provide already reliable file delivery, so there is no need to extend the DAB standard
Sub-Microarcsecond Astrometry with SIM-Lite: A Testbed-based Performance Assessment
SIM-Lite is an astrometric interferometer being designed for
sub-microarcsecond astrometry, with a wide range of applications from searches
for Earth-analogs to determining the distribution of dark matter. SIM-Lite
measurements can be limited by random and systematic errors, as well as
astrophysical noise. In this paper we focus on instrument systematic errors and
report results from SIM-Lite's interferometer testbed. We find that, for
narrow-angle astrometry such as used for planet finding, the end-of-mission
noise floor for SIM-Lite is below 0.035 uas.Comment: 5 pages, 5 figure
MIMO System Setup and Parameter Estimation
There is a rat race in wireless communication to
achieve higher spectral efficiency. One technique to achieve this
is the use of multiple antenna systems i.e. MIMO systems. In
this paper we describe a wireless 4x4 Multiple Input Multiple
Output (MIMO) testbed in the 2.2 GHz band including results
from live experiments. MIMO systems have several advantages
compared to SISO (Single Input Single Output) systems. The
most important ones are higher reliability and/or higher throughput
per Herz. In this testbed we used the 802.11a OFDM
Wireless LAN standard as a basis for the MIMO system. The
experiments have been conducted at 2.2 GHz carrier using 5
MHz bandwidth. These can be divided into several subjects:
antenna spacing experiments, effects for increasing antennas,
AD accuracy and performance for different antenna topologies.
Moreover, the performance of the Zero Forcing (ZF), Minimum
Mean Square Error (MMSE) and Vertical Bell labs LAyered
Space Time (VBLAST) have been evaluated
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