288 research outputs found
Coded Caching via Line Graphs of Bipartite Graphs
We present a coded caching framework using line graphs of bipartite graphs. A
clique cover of the line graph describes the uncached subfiles at users. A
clique cover of the complement of the square of the line graph gives a
transmission scheme that satisfies user demands. We then define a specific
class of such caching line graphs, for which the subpacketization, rate, and
uncached fraction of the coded caching problem can be captured via its graph
theoretic parameters. We present a construction of such caching line graphs
using projective geometry. The presented scheme has a rate bounded from above
by a constant with subpacketization level and uncached
fraction , where is the number of users and
is a prime power. We also present a subpacketization-dependent lower bound on
the rate of coded caching schemes for a given broadcast setup.Comment: Keywords: coded caching based on projective geometry over finite
field
Coded Caching based on Combinatorial Designs
We consider the standard broadcast setup with a single server broadcasting
information to a number of clients, each of which contains local storage
(called \textit{cache}) of some size, which can store some parts of the
available files at the server. The centralized coded caching framework,
consists of a caching phase and a delivery phase, both of which are carefully
designed in order to use the cache and the channel together optimally. In prior
literature, various combinatorial structures have been used to construct coded
caching schemes. In this work, we propose a binary matrix model to construct
the coded caching scheme. The ones in such a \textit{caching matrix} indicate
uncached subfiles at the users. Identity submatrices of the caching matrix
represent transmissions in the delivery phase. Using this model, we then
propose several novel constructions for coded caching based on the various
types of combinatorial designs. While most of the schemes constructed in this
work (based on existing designs) have a high cache requirement (uncached
fraction being or , being
the number of users), they provide a rate that is either constant or decreasing
() with increasing , and moreover require competitively
small levels of subpacketization (being ), which is an
extremely important parameter in practical applications of coded caching. We
mark this work as another attempt to exploit the well-developed theory of
combinatorial designs for the problem of constructing caching schemes,
utilizing the binary caching model we develop.Comment: 10 pages, Appeared in Proceedings of IEEE ISIT 201
Simplifying Wireless Social Caching
Social groups give the opportunity for a new form of caching. In this paper,
we investigate how a social group of users can jointly optimize bandwidth
usage, by each caching parts of the data demand, and then opportunistically
share these parts among themselves upon meeting. We formulate this problem as a
Linear Program (LP) with exponential complexity. Based on the optimal solution,
we propose a simple heuristic inspired by the bipartite set-cover problem that
operates in polynomial time. Furthermore, we prove a worst case gap between the
heuristic and the LP solutions. Finally, we assess the performance of our
algorithm using real-world mobility traces from the MIT Reality Mining project
dataset and two mobility traces that were synthesized using the SWIM model. Our
heuristic performs closely to the optimal in most cases, showing a better
performance with respect to alternative solutions.Comment: Parts of this work were accepted for publication in ISIT 2016. A
complete version is submitted to Transactions on Mobile Computin
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