408 research outputs found
Caching in Combination Networks: Novel Multicast Message Generation and Delivery by Leveraging the Network Topology
Maddah-Ali and Niesen's original coded caching scheme for shared-link
broadcast networks is now known to be optimal to within a factor two, and has
been applied to other types of networks. For practical reasons, this paper
considers that a server communicates to cache-aided users through
intermediate relays. In particular, it focuses on combination networks where
each of the users is connected to a distinct -subsets of
relays. By leveraging the symmetric topology of the network, this paper
proposes a novel method to general multicast messages and to deliver them to
the users. By numerical evaluations, the proposed scheme is shown to reduce the
download time compared to the schemes available in the literature. The idea is
then extended to decentralized combination networks, more general relay
networks, and combination networks with cache-aided relays and users. Also in
these cases the proposed scheme outperforms known ones.Comment: 6 pages, 3 figures, accepted in ICC 2018, correct the typo in (6) of
the previous versio
Generalized Degrees of Freedom of the Symmetric Cache-Aided MISO Broadcast Channel with Partial CSIT
We consider the cache-aided MISO broadcast channel (BC) in which a
multi-antenna transmitter serves single-antenna receivers, each equipped
with a cache memory. The transmitter has access to partial knowledge of the
channel state information. For a symmetric setting, in terms of channel
strength levels, partial channel knowledge levels and cache sizes, we
characterize the generalized degrees of freedom (GDoF) up to a constant
multiplicative factor. The achievability scheme exploits the interplay between
spatial multiplexing gains and coded-multicasting gain. On the other hand, a
cut-set-based argument in conjunction with a GDoF outer bound for a parallel
MISO BC under channel uncertainty are used for the converse. We further show
that the characterized order-optimal GDoF is also attained in a decentralized
setting, where no coordination is required for content placement in the caches.Comment: first revisio
- …