5,307 research outputs found
Disjoint LDPC Coding for Gaussian Broadcast Channels
Low-density parity-check (LDPC) codes have been used for communication over a
two-user Gaussian broadcast channel. It has been shown in the literature that
the optimal decoding of such system requires joint decoding of both user
messages at each user. Also, a joint code design procedure should be performed.
We propose a method which uses a novel labeling strategy and is based on the
idea behind the bit-interleaved coded modulation. This method does not require
joint decoding and/or joint code optimization. Thus, it reduces the overall
complexity of near-capacity coding in broadcast channels. For different rate
pairs on the boundary of the capacity region, pairs of LDPC codes are designed
to demonstrate the success of this technique.Comment: 5 pages, 1 figure, 3 tables, To appear in Proc. IEEE International
Symposium on Information Theory (ISIT 2009), Seoul, Korea, June-July 200
Graphs Cospectral with Kneser Graphs
AMS Subject Classification: 05C50Kneser graph;Johnson scheme;Spectral characterization
Fermi coordinates and modified Franklin transformation : A comparative study on rotational phenomena
Employing a relativistic rotational transformation to study and analyze
rotational phenomena, instead of the rotational transformations based on
consecutive Lorentz transformations and Fermi coordinates, leads to different
predictions. In this article, after a comparative study between Fermi metric of
a uniformly rotating eccentric observer and the spacetime metric in the same
observer's frame obtained through the modified Franklin transformation, we
consider rotational phenomena including transverse Doppler effect and Sagnac
effect in both formalisms and compare their predictions. We also discuss length
measurements in the two formalisms.Comment: 21 pages, 2 figures, replaced with the published versio
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