Multi-hop Precaching scheme with Relaying in Intermittently Connected Vehicular Networks

Due to the rapid development of smart vehicles such as self-driving cars, the mobile data traffic for vehicle users increases to the extent that a base station cannot handle, and it causes delays in content provision. The burden of the base station can be alleviated through roadside units (RSUs) to distribute the demands, but still, the outage zone, which the communication range of RSUs cannot cover, exists due to their high deployment cost. However, since the existing schemes for covering the outage zone only considered single-hop relaying vehicles to provide the precached content, the outage zone cannot be minimized by an insufficient number of candidate vehicles. Therefore, we propose a scheme for minimizing the outage zone by maximizing the precached content through multi-hop relaying vehicles. The proposed scheme optimally selects relaying vehicles through our numerical model to calculate the amount of the precached content and progresses the process of multi-hop relaying through comparing the connection time of vehicles with the dark area time in the outage zone. To prevent much overhead due to frequent precaching vehicle handover, the proposed scheme limits vehicles with a short communication time compared with a precaching restriction indicator in the multi-hop relaying vehicle selection process. Simulation results show that our scheme is superior to the representative scheme based on single-hop relaying.