Cache-Enabled Erasure Broadcast Channels with Feedback -Asymmetric User Memory Case

Abstract : We consider a cache-enabled K-user erasure broadcast channel in which a server with a library of N files wishes to deliver a requested file to each user k who is equipped with a cache of a finite memory M k. Assuming that the transmitter has state feedback and user caches can be filled during off-peak hours reliably by decentralized cache placement, we characterize the achievable rate region as a function of the memory sizes and the erasure probabilities. The proposed delivery scheme, based on the broadcasting scheme proposed by Wang and Gatzianas et al., exploits the receiver side information established during the placement phase. A two-user toy example shows that the cache network with asymmet-ric memory sizes might achieve better sum rate performance than the network with symmetric memory sizes.