Towards Mobility-Aware Proactive Caching for Vehicular Ad hoc Networks

Harnessing information about the user mobility pattern and daily demand can enhance the network capability to improve the quality of experience (QoE) at Vehicular Ad- Hoc Networks (VANETs). Proactive caching, as one of the key features offered by 5G networks, has lately received much interest. However, more research is still needed to convey large-sized multimedia content including video, audio and pictures to the high speed moving vehicles. In this paper, we study the gains achieved by proactive caching in Roadside Units (RSUs) where we take into consideration the effect of the vehicle velocity on the optimal caching decision. Information about the user demand and mobility is harnessed to cache some files in RSUs, which will communicate with vehicles traversing along the visited roads before the actual demand. Our main objective is to minimize the total network latency. Towards this objective, we formulate two optimization problems for non-cooperative and cooperative caching schemes to find the optimal caching policy to decide which files to be cached by the RSUs. Due to the complexity of these problems, we propose a sub-optimal caching policy for each scheme. We compare the performance of the optimal caching policy to that of the sub-optimal caching policy. Numerical results show that proactive caching has a significant performance gain when compared to the baseline reactive scenario. Moreover, results reveal that the cooperative caching scheme is more efficient than the non-cooperative scheme.