The rapidly expanding technology of portable personalized computing devices and wireless data networks has recently given mobile users the capability of accessing multimedia data. The common problems encountered with these systems are network connectivity bandwidth, and latency. Meanwhile, Auto PC by Microsoft Corp., Connected Car PC by Intel Corp., and so on, have become as platfonns of in-vehicle computer systems. We propose a Spatio-Temporal Resource Allocation Protocol (STRAP), to address the network problems with information managed by in-vehicle computer systems for Intelligent Transportation Systems (ITS) communication networks. This protocol is to allocate resources on some of the base stations or networks for a specific period of time, according to mobility specification: A schedule that a mobile host is assumed to travel. Wealso evaluate the protocol using simulation on the model close to the traj% road environment in comparison with conventional protocols: the broadcast method and the geographic multicast method. The simulation experiments show that the STRAP is effective in the case of congested trafic conditions.