Uncoded Caching and Cross-Level Coded Delivery for Non-Uniform File Popularity

Proactive content caching at user devices and coded delivery is studied considering a non-uniform file popularity distribution. A novel centralized uncoded caching and coded delivery scheme, which can be applied to large file libraries, is proposed. The proposed cross-level coded delivery (CLCD) scheme is shown to achieve a lower average delivery rate than the state of art. In the proposed CLCD scheme, the same subpacketization is used for all the files in the library in order to prevent additional zero-padding in the delivery phase, and unlike the existing schemes in the literature, two users requesting files from different popularity groups can be served by the same multicast message in order to reduce the delivery rate. Simulation results indicate significant reduction in the average delivery rate for typical Zipf distribution parameter values.