Predictive Time Division Transmission Algorithm for Segmented Caching in Vehicular Networks

With the increasing number of different types of applications for road safety and entertainment, it demands more flexible solutions for caching and transmitting large files in vehicular networks. In order to decrease the transmission delay and raise the hit ratio of cached files, there is already a lot of research on caching technology, including segmented caching technology. But the problem of long transmission delay and low successful transmission ratio caused by the high dynamic of vehicles still needs to be solved. In this paper, we proposed an algorithm named Predictive Time Division Transmission (PTDT) to reduce transmission delay and raise the ratio of successful transmission for segmented cached file in vehicular networks. Our algorithm predicts the link duration between requesting vehicle and neighboring vehicles according to the relative inter-vehicle distances and velocities. By predicting the transmit rate of each vehicle on different time point, we divide the link duration into slices for subsequent transmitter selections. And finally we compare those time points and select the vehicles that make the transmitting delay the lowest. In the mean time, we arrange the transmitting order of those vehicles to guarantee the success of full file transmission process. The simulation results show that after applying our algorithm, transmission delay has reduced and successful transmission rate has increased substantially.