English abstract
ABSTRACT
Vehicular Ad-Hoc Network (VANET) is a technology that uses moving cars as nodes in a wireless mobile network. VANET turns every participating car into a wireless router or an end node, allowing cars approximately 100 to 300 meters away from each other to connect and, in turn, create a network with a wide range. As cars fall out of the signal range and drop out of the network, other cars can join in, connecting vehicles to one another such that a mobile network is created. There are different classes of VANET applications with different Quality-of-Service (QoS) requirements. Safety applications received most attention since they can significantly decrease the number of road accidents and seem quite promising at reducing the number of fatal roadway accidents by providing early warnings. In this thesis, three VANET simulation tools are reviewed. These simulation tools are NCTUns, GrooveNet and NS2. There is a large number of simulators used to study the behavior of VANETS, the selection of these tools was made based on a study recommendation for NCTUns and GrooveNet as the most suitable tools to simulate VANETs safety applications from the simulation requirements point of view. In terms of popularity, NS2 remains the most popular simulator used by VANET researchers world-wide. Hence it was selected for theoretical review. In this hnical comparison was made between these simulators after a thorough review. Also, limitation in simulating multi-channel operations was highlighted in NS2 simulator and a patch was used to overcome this limitation. Vehicular Ad-hoc Networks implement a wireless technology called Dedicated Short Range Communications (DSRC) at spectrum of 5.9 GHz, as allocated by the Federal Communications Commission (FCC). The IEEE 1609.4 Standard for Wireless Access in Vehicular Environments (WAVE) has been proposed to enhance the performance of vehicular networks by dividing this allocated spectrum into 6 Service CHannels (SCH) and 1 Control CHannel (CCH) of 10 MHz each. An overview of this protocol is presented. Exchange of vehicle movement information is essential for large class of safety applications. This information is included in periodic broadcast (HELLO) messages transmitted during Control Channel intervals. However, the protocol tight channel synchronization produces issues that have a dramatic impact on the performance of safety-related applications with strict delivery ratio and delay requirements.
A study was performed in [2] to investigate the impact of IEEE 1609.4 channel switching and strict synchronization on the performance of safety applications in VANET. In this thesis, a highway VANET scenario is simulated to further investigate the impact of the IEEE 1609.4 channel scheduler on the performance of delay constrained vehicular applications. Simulation results are analyzed and compared with the aforementioned study. In addition, more scenarios are simulated and studied in order to find out the effect of topographical changes on these applications performance. Also, the impact of the multi-channel operations protocol on the performance of safety applications were highlighted in these set of simulations,
