Placement Delivery Array Design for Combination Networks with Edge Caching

摘要

A major practical limitation of the Maddah-Ali-Niesen coded cachingtechniques is their high subpacketization level. For the simple network with asingle server and multiple users, Yan et al. proposed an alternative schemewith the so-called placement delivery arrays (PDA). Such a scheme requiresslightly higher transmission rates but significantly reduces thesubpacketization level. In this paper, we extend the PDA framework and proposethree low-subpacketization schemes for combination networks, i.e., networkswith a single server, multiple relays, and multiple cache-aided users that areconnected to subsets of relays. One of the schemes achieves the cutset lowerbound on the link rate when the cache memories are sufficiently large. Ourother two schemes apply only to resolvable combination networks. For thesenetworks, the new schemes perform closely to the currently best-known codedcaching schemes for a wide range of cache sizes while having significantlyreduced subpacketization levels.