1,807 research outputs found
Iterative Slepian-Wolf Decoding and FEC Decoding for Compress-and-Forward Systems
While many studies have concentrated on providing theoretical analysis for the relay assisted compress-and-forward systems little effort has yet been made to the construction and evaluation of a practical system. In this paper a practical CF system incorporating an error-resilient multilevel Slepian-Wolf decoder is introduced and a novel iterative processing structure which allows information exchanging between the Slepian-Wolf decoder and the forward error correction decoder of the main source message is proposed. In addition, a new quantization scheme is incorporated as well to avoid the complexity of the reconstruction of the relay signal at the final decoder of the destination. The results demonstrate that the iterative structure not only reduces the decoding loss of the Slepian-Wolf decoder, it also improves the decoding performance of the main message from the source
Should {\Delta}{\Sigma} Modulators Used in AC Motor Drives be Adapted to the Mechanical Load of the Motor?
We consider the use of {\Delta}{\Sigma} modulators in ac motor drives,
focusing on the many additional degrees of freedom that this option offers over
Pulse Width Modulation (PWM). Following some recent results, we show that it is
possible to fully adapt the {\Delta}{\Sigma} modulator Noise Transfer Function
(NTF) to the rest of the drive chain and that the approach can be pushed even
to a fine adaptation of the NTF to the specific motor loading condition. We
investigate whether and to what extent the adaptation should be pursued. Using
a representative test case and extensive simulation, we conclude that a mild
adaptation can be beneficial, leading to Signal to Noise Ratio (SNR)
improvements in the order a few dB, while the advantage pushing the adaptation
to the load tracking is likely to be minimal.Comment: Sample code available at http://pydsm.googlecode.co
Effects of interactions in transport through Aharonov-Bohm-Casher interferometers
We study the conductance through a ring described by the Hubbard model (such
as an array of quantum dots), threaded by a magnetic flux and subject to Rashba
spin-orbit coupling (SOC). We develop a formalism that is able to describe the
interference effects as well as the Kondo effect when the number of electrons
in the ring is odd. In the Kondo regime, the SOC reduces the conductance from
the unitary limit, and in combination with the magnetic flux, the device acts
as a spin polarizer.Comment: 5 pages, 5 figure
Data compression for the microgravity experiments
Researchers present the environment and conditions under which data compression is to be performed for the microgravity experiment. Also presented are some coding techniques that would be useful for coding in this environment. It should be emphasized that researchers are currently at the beginning of this program and the toolkit mentioned is far from complete
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