3 research outputs found
On Combination Networks with Cache-aided Relays and Users
Caching is an efficient way to reduce peak hour network traffic congestion by
storing some contents at the user's cache without knowledge of later demands.
Coded caching strategy was originally proposed by Maddah-Ali and Niesen to give
an additional coded caching gain compared the conventional uncoded scheme.
Under practical consideration, the caching model was recently considered in
relay network, in particular the combination network, where the central server
communicates with users (each is with a cache of files)
through immediate relays, and each user is connected to a different
subsets of relays. Several inner bounds and outer bounds were proposed for
combination networks with end-user-caches. This paper extends the recent work
by the authors on centralized combination networks with end-user caches to a
more general setting, where both relays and users have caches. In contrast to
the existing schemes in which the packets transmitted from the server are
independent of the cached contents of relays, we propose a novel caching scheme
by creating an additional coded caching gain to the transmitted load from the
server with the help of the cached contents in relays. We also show that the
proposed scheme outperforms the state-of-the-art approaches.Comment: 7 pages,2 figures, WSA 201
Placement Delivery Array Design for Combination Networks with Edge Caching
A major practical limitation of the Maddah-Ali-Niesen coded caching
techniques is their high subpacketization level. For the simple network with a
single server and multiple users, Yan \emph{et al.} proposed an alternative
scheme with the so-called placement delivery arrays (PDA). Such a scheme
requires slightly higher transmission rates but significantly reduces the
subpacketization level. In this paper, we extend the PDA framework and propose
three low-subpacketization schemes for combination networks, i.e., networks
with a single server, multiple relays, and multiple cache-aided users that are
connected to subsets of relays. One of the schemes achieves the cutset lower
bound on the link rate when the cache memories are sufficiently large. Our
other two schemes apply only to \emph{resolvable} combination networks. For
these networks and for a wide range of cache sizes, the new schemes perform
closely to the coded caching schemes that directly apply Maddah-Ali-Niesen
scheme while having significantly reduced subpacketization levels.Comment: 5 pages, has been published at IEEE International Symposium on
Information Theory (ISIT), Jun. 2018, Colorado, US
Improved Constructions of Coded Caching Schemes for Combination Networks
In an combination network, a single content library is delivered to
users through deployed relays without cache memories, such
that each user with local cache memories is simultaneously served by a
different subset of relays on orthogonal non-interfering and error-free
channels. The combinatorial placement delivery array (CPDA in short) can be
used to realize a coded caching scheme for combination networks. In this paper,
a new algorithm realizing a coded caching scheme for combination network based
on a CPDA is proposed such that the schemes obtained have smaller
subpacketization levels or are implemented more flexible than the previously
known schemes. Then we focus on directly constructing CPDAs for any positive
integers and with . This is different from the grouping method in
reference (IEEE ISIT, 17-22, 2018) under the constraint that divides .
Consequently two classes of CPDAs are obtained. Finally comparing to the
schemes and the method proposed by Yan et al., (IEEE ISIT, 17-22, 2018) the
schemes realized by our CPDAs have significantly advantages on the
subpacketization levels and the transmission rates.Comment: 11 page