CLUSTER-BASED MAC PROTOCOLS FOR VANETS

Abstract

Vehicular ad hoc networks (VANETs) have become crucial in the Intelligent Transportation System. The major challenges in VANETs are maintaining high throughput and low delay in packet delivery with less package dropping rate (PDR) while providing services in advertisement and security. In VANETs, topology constantly changes due to relative mobility and frequent link breaking. Clustering into small groups reduces channel contention, and improves network topology control. A cluster-based medium access control (CB-MAC) protocol for VANETs is presented in this thesis. The process of cluster formation has been defined. Furthermore, mechanisms for selecting the head of the cluster and merging different clusters are outlined for effective and reliable communication both within and outside the cluster. In addition to the CB-MAC protocol, a authentic and systematic cooperative medium access control (RECV-MAC) protocol is presented. For effective cooperative communication, control messages are implemented. A mechanism is designed to find the optimal mode of transmission as well as the optimum helper. Both the MAC protocols are studied, and compared with the conventional MAC protocol. Simulations with NS2 and SUMO are conducted to demonstrate the optimized performance of VANETs using CB-MAC and RECV-MAC protocols. The comparison shows that these two aforementioned protocols improve throughput and communication reliability by reducing PDR as well as delay, satisfying the 150 ms delay requirement for safety messages.