Towards the Exact Rate Memory Tradeoff in Coded Caching

Caching plays an important role in improving internet performance by keeping a fraction of the files closer to the end user. The peak data traffic in the network can be significantly reduced by proper utilization of caching. Recent studies have shown that coded caching does help in further reducing the data traffic over uncoded caching. In this paper, we consider the problem of the exact rate memory tradeoff in coded caching. For the (3, 3) canonical cache network, a new caching scheme to achieve the memory rate pair (5/3,1/2) is introduced. This scheme is further extended to the (4, 4) canonical cache network, to achieve the memory rate pair (11/4,1/3). We prove the optimality of both the proposed schemes by deriving new lower bounds and thus partially characterizing the exact rate memory tradeoff in coded caching.