1,090 research outputs found
Adaptive Delivery in Caching Networks
The problem of content delivery in caching networks is investigated for
scenarios where multiple users request identical files. Redundant user demands
are likely when the file popularity distribution is highly non-uniform or the
user demands are positively correlated. An adaptive method is proposed for the
delivery of redundant demands in caching networks. Based on the redundancy
pattern in the current demand vector, the proposed method decides between the
transmission of uncoded messages or the coded messages of [1] for delivery.
Moreover, a lower bound on the delivery rate of redundant requests is derived
based on a cutset bound argument. The performance of the adaptive method is
investigated through numerical examples of the delivery rate of several
specific demand vectors as well as the average delivery rate of a caching
network with correlated requests. The adaptive method is shown to considerably
reduce the gap between the non-adaptive delivery rate and the lower bound. In
some specific cases, using the adaptive method, this gap shrinks by almost 50%
for the average rate.Comment: 8 pages,8 figures. Submitted to IEEE transaction on Communications in
2015. A short version of this article was published as an IEEE Communications
Letter with DOI: 10.1109/LCOMM.2016.255814
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
Capacity of Cellular Networks with Femtocache
The capacity of next generation of cellular networks using femtocaches is
studied when multihop communications and decentralized cache placement are
considered. We show that the storage capability of future network User
Terminals (UT) can be effectively used to increase the capacity in random
decentralized uncoded caching. We further propose a random decentralized coded
caching scheme which achieves higher capacity results than the random
decentralized uncoded caching. The result shows that coded caching which is
suitable for systems with limited storage capabilities can improve the capacity
of cellular networks by a factor of log(n) where n is the number of nodes
served by the femtocache.Comment: 6 pages, 2 figures, presented at Infocom Workshops on 5G and beyond,
San Francisco, CA, April 201
Multi-access Coded Caching with Decentralized Prefetching
An extension of coded caching referred to as multi-access coded caching where
each user can access multiple caches and each cache can serve multiple users is
considered in this paper. Most of the literature in multi-access coded caching
focuses on cyclic wrap-around cache access where each user is allowed to access
an exclusive set of consecutive caches only. In this paper, a more general
framework of multi-access caching problem is considered in which each user is
allowed to randomly connect to a specific number of caches and multiple users
can access the same set of caches. For the proposed system model considering
decentralized prefetching, a new delivery scheme is proposed and an expression
for per user delivery rate is obtained. A lower bound on the delivery rate is
derived using techniques from index coding. The proposed scheme is shown to be
optimal among all the linear schemes under certain conditions. An improved
delivery rate and a lower bound for the decentralized multi-access coded
caching scheme with cyclic wrap-around cache access can be obtained as a
special case. By giving specific values to certain parameters, the results of
decentralized shared caching scheme and of conventional decentralized caching
scheme can be recovered.Comment: 26 pages, 6 figures, 6 tables, Submitted to IEEE Transactions on
Communication
Hybrid Coded-Uncoded Caching in Multi-Access Networks with Non-uniform Demands
To address the massive growth of data traffic over cellular networks,
increasing spatial reuse of the frequency spectrum by the deployment of small
base stations (SBSs) has been considered. For rapid deployment of SBSs in the
networks, caching popular content along with new coded caching schemes are
proposed. To maximize the cellular network's capacity, densifying it with small
base stations is inevitable. In ultra-dense cellular networks, coverage of SBSs
may overlap. To this aim, the multi-access caching system, where users
potentially can access multiple cache nodes simultaneously, has attracted more
attention in recent years. Most previous works on multi-access coded caching,
only consider specific conditions such as cyclic wrap-around network
topologies. In this paper, we investigate caching in ultra-dense cellular
networks, where different users can access different numbers of caches under
non-uniform content popularity distribution, and propose Multi-Access Hybrid
coded-uncoded Caching (MAHC). We formulate the optimization problem of the
proposed scheme for general network topologies and evaluate it for 2-SBS
network scenarios. The numerical and simulation results show that the proposed
MAHC scheme outperforms optimal conventional uncoded and previous multi-access
coded caching (MACC) schemes.Comment: 10 page
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