DEVELOPMENT OF DYNAMIC CONGESTION CONTROL AND PRIORITY-BASED SCHEDULING SCHEME FOR VEHICULAR ADHOC NETWORK COMMUNICATION

Abstract

Vehicular adhoc network (VANET) is a self-organized, multi-purpose, service oriented network which enables communication between vehicle-vehicle and vehicle-roadside infrastructures for the purpose of exchanging messages. These messages are sent and received by nodes that share a limited number of wireless channels each with limited bandwidth. Due to the unpredictable nature of the network and increase in number of nodes, the message traffic may generate a load higher than the available capacity of the transmission medium leading to channel congestion problem. Due to the contentious nature of the wireless channel, the communication standard ensures that messages of higher priorities (event-driven) are transmitted before those of lower priorities (beacons). However, with a huge number of emergency messages, the contention mechanism may lead to starvation problem for non-emergency. This work, therefore, introduces a congestion control and scheduling scheme. The scheme employs a feedback control mechanism to mitigate channel congestion and a priority-based scheduling technique to eliminate the starvation problem of non-emergency applications in VANET communication. The implementation of the scheme was carried out using network simulator 3, C++ programming language and MATLAB R2018b; while the performance of the congestion control and scheduling mechanism was evaluated using these standard metrics: throughput, end-to-end delay, packet delivery ratio and packet loss ratio. On evaluation, the scheme achieved a higher packet delivery ratio of 15% higher than other existing schemes. It also ensures messages are delivered 10ms faster compared with related work in terms end-to-end delay.