Cooperative Edge Caching for Vehicular Networks in Road Intersections

Cooperative edge caching in vehicular ad hoc net-works is expected to support massive data transmissions with low transmission delays, which is required in various powerful applications brought by the proliferation of smart vehicles and rapid development of B5G/6G communication techniques. How-ever, due to highly dynamic topology of vehicular networks and constrained storage capacities of edge servers, the design of effective caching scheme is challenging, especially in road intersections because of its complexity and flexibility. In this paper, we propose a cooperative edge caching scheme in a four-way intersection of two-lane roads to reduce the average download delay of content, which allows vehicles to fetch contents from road side units (RSUs) or base stations (BSs). To characterize the variation of communication rates between moving vehicles and RSUs, we divide coverage areas of RSUs into different communication zones, based on which we mathematically derived the average download delay of requested contents. Then we formulated an optimization problem of cooperative content placement to minimize the overall download delay, and proposed a dynamic programming (DP)-based algorithm to solve this nonlinear integer programming (NLIP) problem. Simulation results show that the proposed DP-based cooperative caching placement scheme is more efficient for average download delay reduction compared with benchmark schemes such as a popularity-based caching placement scheme and a random caching placement scheme.