1,827 research outputs found
Coded caching in a multi-server system with random topology
Cache-aided content delivery is studied in a multi-server system with P servers and K users, each equipped with a local cache memory. In the delivery phase, each user connects randomly to any ρ out of P servers. Thanks to the availability of multiple servers, which model small-cell base stations (SBSs), demands can be satisfied with reduced storage capacity at each server and reduced delivery rate per server; however, this also leads to reduced multicasting opportunities compared to the single-server scenario. A joint storage and proactive caching scheme is proposed, which exploits coded storage across the servers, uncoded cache placement at the users, and coded delivery. The delivery latency is studied for both successive and parallel transmissions from the servers. It is shown that, with successive transmissions the achievable average delivery latency is comparable to the one achieved in the single-server scenario, while the gap between the two depends on ρ, the available redundancy across the servers, and can be reduced by increasing the storage capacity at the SBSs. The optimality of the proposed scheme with uncoded cache placement and MDS-coded server storage is also proved for successive transmissions
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
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