30 research outputs found
Multicast Beamformer Design for MIMO Coded Caching Systems
Coded caching (CC) techniques have been shown to be conveniently applicable
in multi-input multi-output (MIMO) systems. In a -user network with spatial
multiplexing gains of at the transmitter and at every receiver, if each
user can cache a fraction of the file library, a total number of
data streams can be served in parallel. In this paper, we focus
on improving the finite-SNR performance of MIMO-CC systems. We first consider a
MIMO-CC scheme that relies only on unicasting individual data streams, and
then, introduce a decomposition strategy to design a new scheme that delivers
the same data streams through multicasting of parallel codewords. We
discuss how optimized beamformers could be designed for each scheme and use
numerical simulations to compare their finite-SNR performance. It is shown that
while both schemes serve the same number of streams, multicasting provides
notable performance improvements. This is because, with multicasting,
transmission vectors are built with fewer beamformers, leading to more
efficient usage of available power resources
Optimal Fairness Scheduling for Coded Caching in Multi-AP Wireless Local Area Networks
Coded caching schemes exploit the cumulative cache memory of the users by
using simple linear encoders, outperforming uncoded schemes where cache
contents are only used locally. Considering multi-AP WLANs and video-on-demand
(VoD) applications where users stream videos by sequentially requesting video
``chunks", we apply existing coded caching techniques with reduced
subpacketization order, and obtain a computational method to determine the
theoretical throughput region of the users' content delivery rates, calculated
as the number of chunks delivered per unit of time per user. We then solve the
fairness scheduling problem by maximizing the desired fairness metric over the
throughput region. We also provide two heuristic methods with reduced
complexity, where one of them maximizes the desired fairness metric over a
smaller region than the throughput region, and the other uses a greedy
algorithmic approach to associate users with APs in a fair way