9,180 research outputs found
A Novel Interleaving Scheme for Polar Codes
It's known that the bit errors of polar codes with successive cancellation
(SC) decoding are coupled. We call the coupled information bits the correlated
bits. In this paper, concatenation schemes are studied for polar codes (as
inner codes) and LDPC codes (as outer codes). In a conventional concatenation
scheme, to achieve a better BER performance, one can divide all bits in a
LDPC block into polar blocks to completely de-correlate the possible
coupled errors. In this paper, we propose a novel interleaving scheme between a
LDPC code and a polar code which breaks the correlation of the errors among the
correlated bits. This interleaving scheme still keeps the simple SC decoding of
polar codes while achieves a comparable BER performance at a much smaller delay
compared with a -block delay scheme
Near-optimal adjacency labeling scheme for power-law graphs
An adjacency labeling scheme is a method that assigns labels to the vertices
of a graph such that adjacency between vertices can be inferred directly from
the assigned label, without using a centralized data structure. We devise
adjacency labeling schemes for the family of power-law graphs. This family that
has been used to model many types of networks, e.g. the Internet AS-level
graph. Furthermore, we prove an almost matching lower bound for this family. We
also provide an asymptotically near- optimal labeling scheme for sparse graphs.
Finally, we validate the efficiency of our labeling scheme by an experimental
evaluation using both synthetic data and real-world networks of up to hundreds
of thousands of vertices
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