A Novel Nested Coded Delivery Strategy for Coded Caching Under Nonuniform File Popularity

This letter proposes an efficient nested coded caching scheme (NCCS) under nonuniform file popularity to reduce the average delivery rate. The NCCS uses a nested coded delivery strategy to ensure the subfiles of the files being coded into the same message are of the same size, thereby eliminating zero-padding that is commonly used in coded messages for delivery and, at the same time, maximally exploiting multicasting gain. We further optimize the NCCS by jointly optimizing the cache placement and nested coded delivery strategy to minimize the average delivery rate. Numerical results show that the optimized NCCS outperforms other state-of-the-art coded caching schemes and achieves near-optimal performance.