1,120 research outputs found
Centralized Coded Caching with User Cooperation
In this paper, we consider the coded-caching broadcast network with user
cooperation, where a server connects with multiple users and the users can
cooperate with each other through a cooperation network. We propose a
centralized coded caching scheme based on a new deterministic placement
strategy and a parallel delivery strategy. It is shown that the new scheme
optimally allocate the communication loads on the server and users, obtaining
cooperation gain and parallel gain that greatly reduces the transmission delay.
Furthermore, we show that the number of users who parallelly send information
should decrease when the users' caching size increases. In other words, letting
more users parallelly send information could be harmful. Finally, we derive a
constant multiplicative gap between the lower bound and upper bound on the
transmission delay, which proves that our scheme is order optimal.Comment: 9 pages, submitted to ITW201
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
Decentralized Coded Caching Attains Order-Optimal Memory-Rate Tradeoff
Replicating or caching popular content in memories distributed across the
network is a technique to reduce peak network loads. Conventionally, the main
performance gain of this caching was thought to result from making part of the
requested data available closer to end users. Instead, we recently showed that
a much more significant gain can be achieved by using caches to create
coded-multicasting opportunities, even for users with different demands,
through coding across data streams. These coded-multicasting opportunities are
enabled by careful content overlap at the various caches in the network,
created by a central coordinating server.
In many scenarios, such a central coordinating server may not be available,
raising the question if this multicasting gain can still be achieved in a more
decentralized setting. In this paper, we propose an efficient caching scheme,
in which the content placement is performed in a decentralized manner. In other
words, no coordination is required for the content placement. Despite this lack
of coordination, the proposed scheme is nevertheless able to create
coded-multicasting opportunities and achieves a rate close to the optimal
centralized scheme.Comment: To appear in IEEE/ACM Transactions on Networkin
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