Fundamental Limits of Coded Caching: Improved Delivery Rate-Cache Capacity Tradeoff

Mohammad Mohammadi Amiri, Deniz Gunduz
2017 IEEE Transactions on Communications  
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
more » ... 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.
doi:10.1109/tcomm.2016.2638841 fatcat:7gohsp5edvcd3ggrlxa2jborzu