The ad-hoc vehicular network is a sub stream of an ad-hoc mobile network where the nodes can converse and know each other by their periodic control packet dissemination. In vehicular network communication, the available bandwidth is limited. The parallel and multi-vehicle channel access will create an unwanted delay during the packet dissemination. The node may compete with each other to access the channel during parallel communication. The simultaneous channel access will increase network overload. The proposed approach will minimize the channel access collision through the variable time slots. Before any data dissemination, the node will send a Channel Booking Request (CBR) message to a correspondent node. The spectrum allocation is based on the type of vehicle and message_code. The concept has experimented with traditional routing protocols for overtaking assistance. The proposed approach is compared with the packet delivery rate, jitter, and packet loss rate.