1 research outputs found
An Approximation Algorithm for Optimal Clique Cover Delivery in Coded Caching
Coded caching can significantly reduce the communication bandwidth
requirement for satisfying users' demands by utilizing the multicasting gain
among multiple users. Most existing works assume that the users follow the
prescriptions for content placement made by the system. However, users may
prefer to decide what files to cache. To address this issue, we consider a
network consisting of a file server connected through a shared link to
users, each equipped with a cache which has been already filled arbitrarily.
Given an arbitrary content placement, the goal is to find a delivery strategy
for the server that minimizes the load of the shared link. In this paper, we
focus on a specific class of coded multicasting delivery schemes known as the
"clique cover delivery scheme". We first formulate the optimal clique cover
delivery problem as a combinatorial optimization problem. Using a connection
with the weighted set cover problem, we propose an approximation algorithm and
show that it provides an approximation ratio of , while the
approximation ratio for the existing coded delivery schemes is linear in .
Numerical simulations show that our proposed algorithm provides a considerable
bandwidth reduction over the existing coded delivery schemes for almost all
content placement schemes.Comment: Accepted for publication in IEEE Transactions on Communication