A Study on Delay Assessment for Heterogenous Traffic in VANET

Vehicular Ad hoc Networks (VANETs) comprise of multi-priority hetero-genous nodes, both stationary and/or mobile. The data generated by these nodes may include messages relating to information, safety, entertainment, traffic management and emergency alerts. The data in the network needs dif-ferentiated service based on the priority/urgency. Media Access Control (MAC) protocols hold a significant value for managing the data priority. This paper studies a comparison of 802.11p which is a standard PHY and MAC protocol for VANET with a fragmentation-based protocol, FROG-MAC. The major design principle of 802.11-p is to allow direct Vehicle-to-Vehicle (V2V) and Vehicle-to-Infrastructure (V2I) communication without associa-tion, using Enhanced Distributed Channel Access (EDCA) to prioritize safety-critical messages. However, if non-critical messages already start to transmit, the nodes with critical data have to wait. FROG-MAC reduces this delay by transmitting normal packets in fragments with short pauses between them, al-lowing urgent packets to access the channel during these intervals. Simula-tions have been performed to assess the delay and throughput for high and low priority data. We report that FROG-MAC improves both the performance parameters due to offering an early channel access to the emergency traffic.