1,278 research outputs found
An Efficient Coded Multicasting Scheme Preserving the Multiplicative Caching Gain
Coded multicasting has been shown to be a promis- ing approach to
significantly improve the caching performance of content delivery networks with
multiple caches downstream of a common multicast link. However, achievable
schemes proposed to date have been shown to achieve the proved order-optimal
performance only in the asymptotic regime in which the number of packets per
requested item goes to infinity. In this paper, we first extend the asymptotic
analysis of the achievable scheme in [1], [2] to the case of heterogeneous
cache sizes and demand distributions, providing the best known upper bound on
the fundamental limiting performance when the number of packets goes to
infinity. We then show that the scheme achieving this upper bound quickly loses
its multiplicative caching gain for finite content packetization. To overcome
this limitation, we design a novel polynomial-time algorithm based on random
greedy graph- coloring that, while keeping the same finite content
packetization, recovers a significant part of the multiplicative caching gain.
Our results show that the order-optimal coded multicasting schemes proposed to
date, while useful in quantifying the fundamental limiting performance, must be
properly designed for practical regimes of finite packetization.Comment: 6 pages, 7 figures, Published in Infocom CNTCV 201
Dynamic Edge Caching with Popularity Drifting
Caching at the network edge devices such as wireless caching stations (WCS)
is a key technology in the 5G network. The spatial-temporal diversity of
content popularity requires different content to be cached in different WCSs
and periodically updated to adapt to temporal changes. In this paper, we study
how the popularity drifting speed affects the number of required broadcast
transmissions by the MBS and then design coded transmission schemes by
leveraging the broadcast advantage under the index coding framework. The key
idea is that files already cached in WCSs, which although may be currently
unpopular, can serve as side information to facilitate coded broadcast
transmission for cache updating. Our algorithm extends existing index
coding-based schemes from a single-request scenario to a multiple-request
scenario via a "dynamic coloring" approach. Simulation results indicate that a
significant bandwidth saving can be achieved by adopting our scheme
Cache-Aided Coded Multicast for Correlated Sources
The combination of edge caching and coded multicasting is a promising
approach to improve the efficiency of content delivery over cache-aided
networks. The global caching gain resulting from content overlap distributed
across the network in current solutions is limited due to the increasingly
personalized nature of the content consumed by users. In this paper, the
cache-aided coded multicast problem is generalized to account for the
correlation among the network content by formulating a source compression
problem with distributed side information. A correlation-aware achievable
scheme is proposed and an upper bound on its performance is derived. It is
shown that considerable load reductions can be achieved, compared to state of
the art correlation-unaware schemes, when caching and delivery phases
specifically account for the correlation among the content files.Comment: In proceeding of IEEE International Symposium on Turbo Codes and
Iterative Information Processing (ISTC), 201
Finite Length Analysis of Caching-Aided Coded Multicasting
In this work, we study a noiseless broadcast link serving users whose
requests arise from a library of files. Every user is equipped with a cache
of size files each. It has been shown that by splitting all the files into
packets and placing individual packets in a random independent manner across
all the caches, it requires at most file transmissions for any set of
demands from the library. The achievable delivery scheme involves linearly
combining packets of different files following a greedy clique cover solution
to the underlying index coding problem. This remarkable multiplicative gain of
random placement and coded delivery has been established in the asymptotic
regime when the number of packets per file scales to infinity.
In this work, we initiate the finite-length analysis of random caching
schemes when the number of packets is a function of the system parameters
. Specifically, we show that existing random placement and clique cover
delivery schemes that achieve optimality in the asymptotic regime can have at
most a multiplicative gain of if the number of packets is sub-exponential.
Further, for any clique cover based coded delivery and a large class of random
caching schemes, that includes the existing ones, we show that the number of
packets required to get a multiplicative gain of is at least
. We exhibit a random placement and an efficient clique cover based
coded delivery scheme that approximately achieves this lower bound. We also
provide tight concentration results that show that the average (over the random
caching involved) number of transmissions concentrates very well requiring only
polynomial number of packets in the rest of the parameters.Comment: A shorter version appeared in the 52nd Annual Allerton Conference on
Communication, Control, and Computing (Allerton), 201
Speeding up Future Video Distribution via Channel-Aware Caching-Aided Coded Multicast
Future Internet usage will be dominated by the consumption of a rich variety
of online multimedia services accessed from an exponentially growing number of
multimedia capable mobile devices. As such, future Internet designs will be
challenged to provide solutions that can deliver bandwidth-intensive,
delay-sensitive, on-demand video-based services over increasingly crowded,
bandwidth-limited wireless access networks. One of the main reasons for the
bandwidth stress facing wireless network operators is the difficulty to exploit
the multicast nature of the wireless medium when wireless users or access
points rarely experience the same channel conditions or access the same content
at the same time. In this paper, we present and analyze a novel wireless video
delivery paradigm based on the combined use of channel-aware caching and coded
multicasting that allows simultaneously serving multiple cache-enabled
receivers that may be requesting different content and experiencing different
channel conditions. To this end, we reformulate the caching-aided coded
multicast problem as a joint source-channel coding problem and design an
achievable scheme that preserves the cache-enabled multiplicative throughput
gains of the error-free scenario,by guaranteeing per-receiver rates unaffected
by the presence of receivers with worse channel conditions.Comment: 11 pages,6 figures,to appear in IEEE JSAC Special Issue on Video
Distribution over Future Interne
Distortion-Memory Tradeoffs in Cache-Aided Wireless Video Delivery
Mobile network operators are considering caching as one of the strategies to
keep up with the increasing demand for high-definition wireless video
streaming. By prefetching popular content into memory at wireless access points
or end user devices, requests can be served locally, relieving strain on
expensive backhaul. In addition, using network coding allows the simultaneous
serving of distinct cache misses via common coded multicast transmissions,
resulting in significantly larger load reductions compared to those achieved
with conventional delivery schemes. However, prior work does not exploit the
properties of video and simply treats content as fixed-size files that users
would like to fully download. Our work is motivated by the fact that video can
be coded in a scalable fashion and that the decoded video quality depends on
the number of layers a user is able to receive. Using a Gaussian source model,
caching and coded delivery methods are designed to minimize the squared error
distortion at end user devices. Our work is general enough to consider
heterogeneous cache sizes and video popularity distributions.Comment: To appear in Allerton 2015 Proceedings of the 53rd annual Allerton
conference on Communication, control, and computin
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