Changes between Version 2 and Version 3 of PTVS_Tech

Jan 14, 2010, 9:44:02 AM (14 years ago)



  • PTVS_Tech

    v2 v3  
    1515For a more accurate network model, the node’s protocol stack is taken into account and thus the simulator can have the packet encapsulation process by adding the corresponding headers to the message. The transport layer is UDP, and the IP network layer is replaced by a geographical routing and addressing scheme. The MAC layer is the one in 802.11b.
     19The events queue can hold three types of events: send, receive or GPS. A send event for a specified node triggers the calling of the node’s procedure responsible for preparing a message. It also schedules the corresponding receive event(s) for the receiver(s) the simulator decides to deliver the message to, according to the network module. The receive event is associated either with a node, or with a group of nodes (broadcast) and it calls the appropriate handler in each of the receiving nodes. The GPS event is scheduled at a regular time interval for each node, in order to simulate the way a real VANET application collects GPS data periodically.
     20Besides these three types of events, the mobility module updates periodically the position of each node that is a vehicle, according to the vehicular mobility model. This model takes into account vehicle interactions (passing by, car following patterns etc), traffic rules and various driver behavior.
     22The main advantage of this architecture is that the simulator can execute (or emulate) the real application’s code without significant changes. Practically, we have succeeded to simulate the TrafficView application [1] on each node, by calling the appropriate methods of the application when the corresponding events occur. Some minor changes were in order, because the original application was multithreaded which would be a serious limitation for the simulator. Figure 1 shows the top-down view of this simulation environment.