Coded Caching with Area-Based User Combinations

Coded caching is an effective method for alleviating traffic burden in broadcast networks by jointly optimizing caching and transmission strategies. In most previous works, users maintain isolated cache contents even when they are in close proximity. However, real-world scenarios exhibit diverse distributions of user locations, enabling low-cost content sharing among nearby users, which further reduces the network traffic. These scenarios can be modeled as a coded caching problem with area-based user combinations, where users in the same area can share cache contents. In this paper, we focus on scenarios where the number of users in each area is known during the content placement phase, referred to as the user connectivity. With the given user connectivity, we propose a decentralized coded caching transmission scheme and analyze its upper bound on the transmission rate. Additionally, the corresponding lower bound for any achievable scheme is derived. Regardless of the user connectivity, the gap between these two bounds is proved to be within a constant factor of 16. Simulation results demonstrate the superior performance of the proposed scheme.