Centralized caching and delivery of correlated contents over a Gaussian broadcast channel

Abstract

Content delivery in a multi-user cache-aided broadcast network is studied, where a server holding a database of correlated contents communicates with the users over a Gaussian broadcast channel (BC). The minimum transmission power required to satisfy all possible demand combinations is studied, when the users are equipped with caches of equal size. A lower bound on the required transmit power is derived, assuming uncoded cache placement, as a function of the cache capacity. A centralized joint cache and channel coding scheme is proposed, which not only utilizes the user's local caches, but also exploits the correlation among the contents in the database. This scheme provides an upper bound on the minimum required transmit power for a given cache capacity. Our results indicate that exploiting the correlations among the contents in a cache-aided Gaussian BC can provide significant energy savings.

Benefits of Cache Assignment on Degraded Broadcast Channels

“…Joint cache-channel coding schemes 1 have also been employed for transmission over noisy BCs with caching receivers when the files to be sent are correlated [31], [32] or when receivers have different fidelity constraints [24], [25], [33]. In these applications, improvements are possible even when users have perfectly symmetric channels and cache sizes.…”