Coded Caching Scheme for Two-Dimensional Caching-Aided Ultra-Dense Networks

In this paper, we consider a two-dimensional caching-aided ultra-dense network caching system, which consists of a server containing N files, K1K2 cache nodes that are arranged neatly on the grid with K1 rows and K2 columns, and U cacheless users randomly distributed around cache nodes. The server connects to users through an error-free shared-link, and the users can be served by nearby cache nodes and freely retrieve the cache content from it. Our goal is to minimize the transmission load in the worst case while meeting all possible users’ demands. We propose a coded caching scheme based on Maddah-Ali and Niesen scheme (MN scheme), which uses the placement strategy of MN scheme to the cache nodes and uses the delivery strategy of MN scheme multiple rounds for different types of users according to their geometrical locations. We prove that our scheme is order optimal and can greatly improve the transmission performance compared with conventional uncoded caching schemes.