Performance of Vehicle-to-Vehicle Communication using IEEE 802.11a: A Measurement Study Paulo Sandino Department of Computer Engineering State University of Maranhão São Luis, Brazil sandino.coelho@gmail.com Leonardo H. Gonsioroski, Member IEEE Department of Computer Engineering State University of Maranhão São Luis, Brazil gonsioroski@uema.br Rogério Moreira Lima Silva Department of Computer Engineering State University of Maranhão São Luis, Brazil rogeriomls@uema.br Amanda dos Santos Department of Computer Engineering State University of Maranhão São Luis, Brazil amanda.santos@geticom.com Abstract— V2V (Vehicle to Vehicle), V2I (Vehicle to Infrastructure) and ITS (Intelligent Transportation System) is the approach to increasing the safety of the transport system. VANET (Vehicular Ad-Hoc Network) is a version of MANET (Mobile Ad-Hoc Network) in which Vehicles act as active nodes of the network. VANET is a highly mobile system. In this paper, a real-time mobile measurement setup was established to simulate a V2V communication scenario in a suburban region using the IEEE 802.11a communication standard in 5 GHz band to evaluate various Quality of Service (QoS) parameters, such as throughput, delay end-to-end and packet loss in situations where vehicles are moving in opposite directions and in the same direction with different relative speeds between on board units. The main discovery of this paper are that the transfer rate is higher when vehicles are approaching in opposite directions and falls immediately when they cross and start to move away regardless of speed. Keywords—IEEE 802.11a, vehicle networks, throughput I. INTRODUCTION Vehicle traffic is one of the biggest problems in big cities. Getting around has become a daily challenge for thousands of workers in the main metropolitan areas due to congestion caused by various factors such as accidents, construction works or simply the excess of cars on the roads. Congestion reduces the efficiency of transport infrastructure and increases travel time, air pollution and fuel consumption. Intelligent transport systems (ITS) are information and communication technologies that have attracted a lot of attention in recent years. These technologies improve transport safety, reliability and productivity by integrating with other existing technologies. In ITS systems, vehicles are equipped with short- range wireless communication technology (approximately 100 to 300 meters), acting as computer nodes and communicating with each other, vehicle-to-vehicle (V2V), or with a fixed point of any infrastructure, Vehicle-to-infrastructure (V2I). The Veicular Ad Hoc Networks (VANETs), which are networks composed of motor vehicles and infrastructures strategically positioned on the margins of streets and avenues, allow communication in real time [1] and in movement [2] between vehicles and / or infrastructure, enabling a wide variety of applications, improving safety, comfort, optimizing the time spent in traffic and serving as a tool for better management and monitoring of urban traffic, which promotes the development of smart cities [3]. The IEEE Task Force has developed an amendment to the 802.11 standard to improve it to support vehicular networks. The IEEE 802.11p standard, also known as WAVE, indicates the modes of operation and operation of the network, the technique of accessing the medium, the best modulation and encoding, the acceptable data transfer rate, among other specifications. The IEEE 802.11p is based on the 802.11a standard and has the same structure [4]. Both use OFDM transmission with the same carrier structure, however, the IEEE 802.11p standard uses a bandwidth of 10 MHz (half the bandwidth used by the IEEE 802.11a standard), in order to make the signal more robust against fading and the effect of multipath that is very strong in vehicular communications environments. The IEEE 802.11p standard operates in the 5.9 GHz band and uses the vehicle communication known as Dedicated Short Range Communication (DSRC), which is standardized by the IEEE [5]. DSRC standards are based on 802.11a, with adjustments made for low cost operations at 5.9GHz. Wireless 802.11p in-vehicle access (WAVE) is the change that allows wireless devices to communicate with each other in a high-speed vehicle environment. The exchange of data in V2V communication systems is a field that requires solutions, tools and automated methods and the ability to facilitate early detection and even a forecast. For this reason, in recent years there has been a great growth in studies and research to evaluate the performance of VANETs [5], [6]. Some of these studies [8], [9], [10] present a proposal to use other IEEE 802.11 standards for use in vehicular environments. In [7] Tufail et al. investigates the behavior of network connections that are initiated on an IEEE 802.11g channel and discusses the possibility of using the IEEE 802.11g protocol to establish connection between fast-moving vehicles and the impact of vehicle speed. In [8] an extensive study is carried out on Tufail's work reviewing the characteristics of links formed by nodes in vehicles using IEEE 802.11a in ad hoc mode. In [9] VANET performance using DSRC and Wi-Fi Direct are performed and presented. Many studies study data delay due to the high mobility of traffic between vehicles during communication [10], [11] as communication must have a minimum of delay so that systems can receive feedback in time to make assertive decisions. This research work was funded by the Foundation for the Support of Research and Scientific and Technological Development of Maranhão (FAPEMA).