299 research outputs found
Uncoded Caching and Cross-level Coded Delivery for Non-uniform File Popularity
Proactive content caching at user devices and coded delivery is studied
considering a non-uniform file popularity distribution. A novel centralized
uncoded caching and coded delivery scheme, which can be applied to large file
libraries, is proposed. The proposed cross-level coded delivery (CLCD) scheme
is shown to achieve a lower average delivery rate than the state of art. In the
proposed CLCD scheme, the same subpacketization is used for all the files in
the library in order to prevent additional zero-padding in the delivery phase,
and unlike the existing schemes in the literature, two users requesting files
from different popularity groups can be served by the same multicast message in
order to reduce the delivery rate. Simulation results indicate significant
reduction in the average delivery rate for typical Zipf distribution parameter
values.Comment: A shorter version of this paper has been presented at IEEE
International Conference on Communications (ICC) 201
Cache-Enabled Broadcast Packet Erasure Channels with State Feedback
We consider a cache-enabled K-user broadcast erasure packet channel in which
a server with a library of N files wishes to deliver a requested file to each
user who is equipped with a cache of a finite memory M. Assuming that the
transmitter has state feedback and user caches can be filled during off-peak
hours reliably by decentralized cache placement, we characterize the optimal
rate region as a function of the memory size, the erasure probability. The
proposed delivery scheme, based on the scheme proposed by Gatzianas et al.,
exploits the receiver side information established during the placement phase.
Our results enable us to quantify the net benefits of decentralized coded
caching in the presence of erasure. The role of state feedback is found useful
especially when the erasure probability is large and/or the normalized memory
size is small.Comment: 8 pages, 4 figures, to be presented at the 53rd Annual Allerton
Conference on Communication, Control, and Computing, IL, US
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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