A hybrid prefetch policy for the retrieval of link-associated information on vehicular networks

This paper proposes and measures the performance of a hybrid prefetch scheme for the gateway cache in the vehicular telematics network. Aiming at improving response time and instant reply ratio, the proposed scheme combines the advantage of LRU and FAR to best exploit temporal and spatial locality. For the advanced path recommendation service, links are categorized into two groups, namely, one referenced during the given interval, and the other not referenced. Each group orders the links according to the distance from the gateway, finalizing the prefetch order. Simulation results, based on the real-life trajectory data obtained from a real-time tracking system, show that the hybrid prefetch can improve instant reply ratio by up to 5.3% and response time by up to 12.5%, compared with FAR in spite of low link-level hit ratio.