A centralized coded caching system, consisting of a server delivering N popular files, each of size F bits, to K users through an error-free shared link, is considered. It is assumed that each user is equipped with a local cache memory with capacity M F bits, and contents can be proactively cached into these caches over a low traffic period, however, without the knowledge of the user demands. During the peak traffic period, each user requests a single file from the server. The goal is to minimize the number of bits delivered by the server over the shared link, known as the delivery rate, over all user demand combinations. A novel coded caching scheme for the cache capacity of M = (N −1)/K is proposed. It is shown that the proposed scheme achieves a smaller delivery rate than the existing coded caching schemes in the literature, when K > N ≥ 3. Furthermore, we argue that the delivery rate of the proposed scheme is within a constant multiplicative factor of 2 of the optimal delivery rate for cache capacities 1/K ≤ M ≤ (N −1)/K , when K > N ≥ 3.
REF proposed a novel coded caching scheme subject to a storage size constraint, and showed the improvement of the required transmission rate compared with the existing approaches when the number of users satisfied some conditions.
Fundamental Limits of Coded Caching: Improved Delivery Rate-Cache Capacity Tradeoff
IEEE Transactions on Communications
IEEE Transactions on Communications
Computer Science