Hierarchical Coded Caching for Multiscale Content Sharing in Heterogeneous Vehicular Networks

The coexistence of multiple types of users in vehicular networks results in diversified service requirements and multiscale content differences, which poses new challenges to reliable content transmission. This paper proposes a hierarchical coded caching framework coupled with coded caching, vehicle-to-everything communications, and non-orthogonal multiple access techniques. We quantify the user request hit ratio under different communication modes and study the hit ratio maximization problem under the constraint of limited communication and caching resources. We propose a two-layer matching based optimization algorithm, including a user association layer in distributed content sharing and a user grouping layer in centralized content requesting. Simulation results verify that the proposed scheme can achieve a balance between hit ratio and transmission time, and meet the requirements of the content sharing scenario with multiscale content files and scalable user density.