Two-Layer Distributed Content Caching for Infotainment Applications in VANETs

For vehicular ad hoc networks (VANETs), edge caching has attracted considerable research attention to maximize the efficiency and reliability of infotainment applications. In this article, we propose a two-layer distributed content caching scheme for VANETs by jointly exploiting the cache at both vehicles and roadside units (RSUs). Specifically, we formulate the content caching problem to minimize the overall transmission delay and cost as a nonlinear integer programming (NLIP) problem and propose an alternate dynamic programming search (ADPS)-based algorithm to solve it. In ADPS, we divide the original problem into three subproblems and then we use the dynamic programming (DP) method to solve each subproblem separately. To reduce the complexity, we further propose a cooperation-based greedy (CBG) algorithm to solve the large-scale original problem. Both numerical simulation results and experiments in the testbed show that the proposed caching scheme outperforms existed caching schemes, and the transmission delay and cost can be reduced by 10% and 24%, respectively, while the hit ratio can be increased by 30% in a practical environment, as compared to the popularity-based caching scheme.

Automated summary

In this article, a two-layer distributed content caching scheme for VANETs is proposed, which utilizes the cache at both vehicles and RSUs to minimize transmission delay and cost. By using an alternate dynamic programming search-based algorithm and cooperation-based greedy algorithm, the large-scale problem can be effectively solved, achieving better performance compared to existing schemes.