DSRCMAC Protocolsin Connected Vehicles - A Review

Abstract

The evolution of Internet of Things (IoT) has fueled the Transportation system in to Smart Transportation system called Internet of Vehicles (IoV) where each vehicle is treated as things connected to the internet. Internet of Vehicles is a consolidation of IoT. The building blocks of IoV are Vehicular Ad hoc Networks (VANETS), Autonomous vehicles and connected vehicles. Connected vehicles plays an important role in transportation system, ensuring road safety and improving transportation efficiency. In connected vehicles, vehicles are connected in several ways-one is using wireless LAN (WLAN) sharing internet with other vehicles with in a coverage area of 1 kilometer, second is using Dedicated Short Range Communication(DSRC) and some others such as cellular communications. Dedicated Short Range Communication is a wireless technology used in connected vehicles. Dedicated Short Range Communication operates at 5.9 GHz with very low latency approximately 0.02 seconds. Dedicated Short Range Communication is used for Vehicle-to-Vehicle (V2V)system, for broadcasting information to neighboring vehicles about speed, position, velocity and road safety messages. In DSRC, the messages were used to broadcast in one hop communication to alert surrounding vehicles with in the pre-defined range about road dangers. The IEEE standard has adapted DSRC as a wireless technology to enable safety and non-safety applications. Bandwidth of DSRC is divided in to seven channels. One Control Channel (CCH) and six Service Channels (SCH). Safety applications use control channel whereas non-safety applications use service channel. The time interval assigned for safety and non-safety applications is 50ms each with 4ms guard band. It is of paramount importance that the vehicles should transmit messages to its neighboring vehicles reliably and within the bounded delay which is considered as a very crucial parameter in dynamic and mobile vehicular environments.Various research work have been proposed algorithmic means to optimize control channel, to avoid hidden terminal problem in MAC layer, and to reduce transmission collisions. However, the existing methods suffer from overhead problems and the methods suggested for hidden terminal problem might not be suitable for DSRC safety applications. The proposed work through this paper summarizes the findings. Also, a detailed comparative analysis is done to discuss challenges and issues concerningMedia Access Control(MAC) protocols for connected vehicles.