# A Performance Analysis of VANETs Propagation Models and Routing Protocols
###### Abstract  
Vehicular Ad hoc Networks (VANETs) thrive on providing a communication channel between vehicles and infrastructures that facilitate efficient and safe Vehicle-to-Vehicle (V2V) as well as Vehicle-to-Infrastructure (V2I) communications. Reliable and efficient transmission amongst vehicles and Road Side Units (RSUs) is a prime concern of Intelligent Transportation System (ITS). One of the primary challenges involved in vehicular communication is designing an efficient routing mechanism for data dissemination from node to node via a reliable route. The harsh vehicular environment with varied road conditions and obstacles in the signal propagation path induces another challenge. Therefore, this paper presents a comparative analysis of existing routing protocols with propagation models to assist researchers in gaining insight into the existing propagation model and routing protocols. The study also optimizes routing and propagation models for reliable packet dissemination. This work uses a realistic scenario from Open Street Map (OSM), and simulations are performed using SUMO. The trace files generated from SUMO are used for further simulation in NS-3. The simulation results are presented and studied in detail. The results show that the Two-Ray Ground and FRIIS propagation model outperforms the compared models, and the routing protocol OLSR outperforms AODV and DSDV. os 2021 2022 2021  
implements the CSMA/CA protocols for WAVE standards to adjust to dynamic network topology and increased mobility. In addition, many traditional routing protocols such as AODV, DSDV, OLSR are implemented and enhanced for efficient route detection to disseminate messages from the source to destination. MMPR-OLSR in [4] is proposed to optimize data dissemination and better channel utilization with a robust VANETs architecture and multipoint selection of relay. Radio propagation models play a vital part in the performance of a network predicting the propagation behaviour. Figure 1 depicts a V2V and V2I communication scenario with a sender and receiver vehicle where other vehicles, RSUs, and buildings act as reflectors causing path loss. Path loss is computed by considering Line-Of-Sight (LOS) and Non-Line-Of-Sight (NLOS) between vehicles and other units. The difference between LOS and NLOS relates to the cumulative distance between sender and receiver, including intermediate reflectors. Propagation models for the channel in a vehicular environment are related to road traffic density, vehicle speed, and scenarios such as highway or urban. In VANETs, various radio models estimate path loss in different scenarios, including flyovers, buildings, tunnels, and other infrastructures. Based on the above consideration, this work compares topology-based routing protocols with different propagation models and a varied number of nodes (vehicles), changing simulation time to reach the performance levels. Specifically, the simulation was conducted by taking a real-time traffic scenario of Rourkela, India, using SUMO [5] on various existing routing protocols and propagation models. The performance analysis is based on three basic parameters--packet delivery ratio, throughput, and delay. The main contribution of this work includes a generic study of different routing protocols and propagation models for VANETs in a realistic traffic setting. This work analyses the impact of existing propagation models and routing protocols simulated by varying node number (vehicles) and simulation time on network performance. The primary contribution of the paper includes:  
1. A study of implementation and design of an efficient routing mechanism in VANETs;
2. Study and analysis of some basic routing protocols and propagation models on performance evaluation of VANETs;
3. The performance evaluation is based on throughput, packet delivery ratio, delay, goodput, and overhead observed for routing protocols and propagation models.