Prioritized and on Time Safety Critical Message Transmission in VANET

Vehicular ad-hoc networks (VANETs) provide the communication framework for the dissemination of safety-critical messages such as beacons and emergency messages. Under high-density situations, it leads to a serious scalability problem in VANETs. Congestion in the communication channel results in packet drops, throughput reduction and degradation of channel quality. So, congestion control schemes are necessary to regulate the traffic level at an acceptable level. Proposed Adaptive congestion control can reserve time slots by dynamically partitioning the beacon interval without the expense of beacons. Dynamic time slots ensure fast and reliable propagation of emergency messages by employing a pulse-based reservation mechanism. Each segment will have number of transmission periods and vehicles can transmit their beacon in that transmission period. Problem of congestion and emergency message occurs, the adaptive congestion control can reserve time slots by dynamically partitioning the beacon interval without the expense of beacons. Adaptive beacon broadcast overcomes the problem of periodic beacons broadcast that incurs high overhead and congestion in the network. On time safety message transmission reduces the congestion in the network and emergency messages are easily transmitted without any delay. Performance of the proposed system is evaluated by delay, throughput, packet delivery ratio.