119 research outputs found
Broadcast Caching Networks with Two Receivers and Multiple Correlated Sources
The correlation among the content distributed across a cache-aided broadcast
network can be exploited to reduce the delivery load on the shared wireless
link. This paper considers a two-user three-file network with correlated
content, and studies its fundamental limits for the worst-case demand. A class
of achievable schemes based on a two-step source coding approach is proposed.
Library files are first compressed using Gray-Wyner source coding, and then
cached and delivered using a combination of correlation-unaware cache-aided
coded multicast schemes. The second step is interesting in its own right and
considers a multiple-request caching problem, whose solution requires coding in
the placement phase. A lower bound on the optimal peak rate-memory trade-off is
derived, which is used to evaluate the performance of the proposed scheme. It
is shown that for symmetric sources the two-step strategy achieves the lower
bound for large cache capacities, and it is within half of the joint entropy of
two of the sources conditioned on the third source for all other cache sizes.Comment: in Proceedings of Asilomar Conference on Signals, Systems and
Computers, Pacific Grove, California, November 201
A Novel Centralized Strategy for Coded Caching with Non-uniform Demands
Despite significant progress in the caching literature concerning the worst
case and uniform average case regimes, the algorithms for caching with
nonuniform demands are still at a basic stage and mostly rely on simple
grouping and memory-sharing techniques. In this work we introduce a novel
centralized caching strategy for caching with nonuniform file popularities. Our
scheme allows for assigning more cache to the files which are more likely to be
requested, while maintaining the same sub-packetization for all the files. As a
result, in the delivery phase it is possible to perform linear codes across
files with different popularities without resorting to zero-padding or
concatenation techniques. We will describe our placement strategy for arbitrary
range of parameters. The delivery phase will be outlined for a small example
for which we are able to show a noticeable improvement over the state of the
art.Comment: 4 pages, 3 figures, submitted to the 2018 International Zurich
Seminar on Information and Communicatio
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