Fundamental Limits of Coded Caching: The Memory Rate Pair (K - 1 - 1/K, 1/(K-1))

Maddah-Ali and Niesen, in a seminal paper, introduced the notion of coded caching. The exact nature of the fundamental limits in this context has remained elusive even as several approximate characterizations have been found. A new optimal scheme for the (3, 3) cache network, operating at the memory rate pair (5/3, 1/2) for the demand where all the users request for distinct files, was introduced recently to partially address this issue. In this paper, an extension of this scheme to the general (K, K) cache network, operating at the memory rate pair ((K
²
-K -1)/K, 1/(K -1), is proposed. A new lower bound is also derived which demonstrates the optimality of the proposed scheme for the demand where all the users request for distinct files.