A Novel Protocol for Safety Messaging and Secure Communication for VANET System : DSRC

DSRC is a one-to-many way powerful, efficient, and robust novel protocol using wireless technology which provides high data transmission capability from source node to target node in VANET system environment. In VANET, it is intended as highly data secure protocol in communication, highspeed wireless communication technology among users and infrastructure of VANET. And it is considered by many researchers and scientists as a traditional protocol for VANETs and the most viable approach to low latency short range vehicular networks. One approach to increase the safety is alerting the drivers in emergency conditions before they attain the destination. In this paper, we discuss DSRC technology in possible dimensions. Keywords— DSRC; ITS; VANET; CEN 278; Wireless Technology; ETC; Viable; OFDM.

According to some surveys reports given on VANET environment, probably 80% commuters use road as primary mode of transportation service. In order to collect toll amount at toll gates the ATTSII (Association of Toll and Traffic Systems Integrators of India) has issued suitable guidelines for ETC [5] (Electronic Toll Collection) service by road safety and traffic management ministry, ministry of surface transport and highways, and electronic toll collection systems. Electronic toll collection means while driver of a vehicle is far away from toll gate, toll operator collects his credit card number or any other required details for transaction and complete that transaction so that driver will go directly without stopping at toll plaza. This feature tremendously saves the time and controls the traffic flow [6]. So, to implement ETC service for VANET, the association proposes a standard based on DSRC microwave technology called as CEN 278 which makes the VANET environment as more reliable, viable, and efficient. CEN DSRC technology was developed to serve multiple applications to facilitate best services in ETC. In this standard, smart tags concept has been introduced based on microwave technology. It saves not only fuel in VANET environment but also reduces waiting time significantly [7].

A. DSRC Functions, Operating and Benefits
The rudimentary functions of DSRC in safety messaging and secure communication are: • Efficient use of spectrum • Security oriented and prioritized delivery of messages • Minimization of packet delay as well as authentication.
In DSRC standard the main target is sending safety messages among vehicular nodes in VANET with high reliability and full efficiency in order to provide better services to roadside users. DSRC [8] protocol is licensed at 5.9 GHz band with 75 MHz spectrum and divided into seven channels (10 MHz each) as 1 CCH (control channel), remaining as 6 SCH (Service channels) and a 5 MHz guardband. The CCH will be used for safety applications and other six SCHs will be used for infotainment or commercial applications. Increasing the CCH interval will increase the reliability of the safety applications and challenge the coexistence of both safety and non-safety applications on DSRC protocol in VANET environment. In this microwave technology, public transportation vehicular nodes broadcasts using wireless channels and control traffic signals changes that traffic signals according to desired respond in order to give quick respond in emergency and dangerous conditions. In DSRC [9] technology, the appropriate integration of sensors along with GPS positioning system provide tremendous communication capabilities to obtain better services in VANET but raises formidable research challenges. The communication type will be one-to-many, many-to-one, geo significant, and local. Whenever offered traffic is large then; latency, reliability, and channel efficiency will be decreased. In V2V messaging when DSRC involves, all protocols we will be designed are classified into either synchronous or asynchronous messages as: APRCS(APR with Carrier Sensing) DSRC was particularly developed for the fulfillment of the requirements of the VANET system environment. It works on physical and MAC layer of IEEE 802.11 standard. It operates on 75 MHz spectrum in 5.9 GHz frequency band at 27 MBPS data rate in US. In Europe, Japan countries it operates on 30 MHz spectrum in 5.8 GHz band. It provides high level data rate transfers of communication with low latency in small zones. The control channel is also used to announce the services that are available. Implementation details are communication range is 300 meters, data rate 6 mbps and broadcast period is 300ns. It means it serves safety applications. In opposite, service channels serve for nonsafety applications [10].

B. Current working of IEEE standards on DSRC
Furthermore, IEEE task group is currently working on IEEE 802.11p for both PHY and MAC layers of DSRC. The IEEE 802.11p standard (second generation DSRC) rectifies all problems which are existed in first generation DSRC [9]. II. LITERATURE SURVEY A number of unique applications are developed for DSRC technology. Many analytical models have been proposed to study the DSRC using IEEE 802.11 and EDCA (Enhanced Distributed Channel Access) for broadcast messages among vehicular nodes. Torrent -Moreno et al. [11] and Vaneenennaam et al. [12] introduced an algorithm to control the load of periodic messages. The channel delay of the DSRC has been analyzed by K. Bilstrup [13] and compared with a self organizing TDMA (Time Division Multiple Access) which has been proven more suitable for VANET real time applications. Wang and Hassan [14] proposed a framework for sharing the DSRC between vehicular safety and non-safety applications. By assuming uniformdistribution of vehicular nodes on the road show that their simulation results of non safety applications are not compromised, especially in high density networks. S. Eichler [15] analyzed the DSRC based on average delay in distributing a safety message to destination in VANET system. Frachcchia and M. Meo [16] analyzed a model for delivering safety messages using IVC. They assume perfect channel for deliver of message which was derived from IVC based on vehicular node mobility. Fallah et al. [17] analyzed the effect of different sets of data rates and communication ranges on the performance of the DSRC safety applications. Here, they introduced a power control algorithm based on the average channel occupancy which has been used only changed communication range. In this algorithm if channel occupancy increases they decrease the communication range and vice-versa to maintain the acceptable channel capacity. Venkatamangarao Nampally and Dr. Raghavender Sharma have achieved safety transmission of a message by using NTBS protocol in VANET thus to increase communication flow in VANET [18].

A. DSRC Channel Allocation
The FCC allocated 5.9 GHz band as new DSRC. In order to provide best service facilities in VANET system environment, first generation DSRC divided into two channels. Whereas second generation DSRC divided into seven channels each at 10 MHz. In these channels one is control channel and remaining six are service channels. 915 MHz DSRC supports a data rate of 0.5 Mb/s but 5.9 GHz DSRC supports 6 to 27 Mb/s. Thus two channels, the data can reach at maximum 54 Mb/s when two channels are combined to form one MHz channel..It is composed of seven channels as shown above figure each channel at 10 MHz (1 CCH and 6 SCH). The modulation scheme used by DSRC is OFDM (Orthogonal Frequency Division Multiplexing. Above figure provides channel layout of DSRC. The list of channel applications supported by that channel is: • Channel 172 is reserved for medium power safety applications. • Channel 182 is reserved for low power configurations and provides little interference when vehicular units are separated by 50 ft or more. • Channel 184 is reserved for a high power service channel that is used to co-ordinate intersection applications. The current wireless technology is only able to listen to only one transceiver. To overcome this problem, to equip an OBU or a RSU with multiple transceivers allow them access to multiple channels simultaneously. The drawback of having multiple radios is it increases the cost and complexity [19].

B. First and Second Generation DSRCs
The first generation of DSRC operates at 915 MHz at transmission rate 0.5 Mb/s. it is very scalable and efficient offers low cost facilities to its users. It has only one or two channels in order to provide service. One of examples for first generation DSRC application is EZpass which is used for electronic toll collection. But this project achieved limited success rate and is primarily used for electronic toll collection for commercial vehicles in VANET. In first generation bandwidth of DSRC protocol is not sufficient in all situations. So FCC allocated additional 75 MHz bandwidth in 5.9 GHz band. This new tremendous amendment is called second generation DSRC. The second generation DSRC system started in 1997 and it is operated at 75 MHz of bandwidth in the 5. have become possible by transferring safety messages via communication capabilities of integrated GPS and on-board sensors when IVC has been taken into consideration. In IVC each vehicular node equipped with communication receiving and sending capability devices with appropriate sensors, GPS to collect information about their speed, acceleration, position and direction to be broadcasted to all vehicular nodes with their radio signals coverage. Generally, where communication zones which have relatively small in geographic area, they require high data transfer rate. In these areas, first generation DSRC is not sufficient to make vehicular nodes proper communication in VANET system. So, FCC allocated 5.9 GHz band at 75 MHz spectrum. Second generation DSRC provides data transfer rate at 6 Mb/s to 27 Mb/s per channel [21]. So merging of four channels provide approximately 100 Mb/s data transfer rate. According a particular zone requirement, we use channels as data transfer rate requirement. SAE J2735 is a standard in DSRC for defining messages in VANET.  ▪ Probe/Data/ Traffic Information Besides these four the DSRC applications further categorized as safety and non-safety applications. The function of the public safety application is the improvement of the overall safety transportation infrastructure. The public safety applications allow protection to the safety of life, and health of users. These public safety services are provided by either governmental or non-governmental agencies under the control of authorized governmental body. As a survey DSRC provides approximately 34 possible safety services to users through DSRC. And the function of the non-safety applications increase the comfort of the user by adding value added services. It is clear that public safety applications are always given priority than non-safety applications. The message of DSRC is either event or periodic. Event-driven message means it is delivered only some event occurred while periodic messages transmitted at a special interval. In order to gain widespread adoption and to provide interoperability feature DSRC supports number of different protocols. On the basis of evaluated criteria, the VSC project determined the safety applications as the highest priority based applications to implement in VANET system environment to save the lives of its users.   Reason behind huge use of wireless technology in VANET is its cost must be low than both cellular and satellite technologies. And also wireless technology is based on ad hoc networks and infrastructure of wireless costs us very cheap than cellular and satellite technologies. Below table compares wireless with cellular and satellite technologies. IV. CONCLUSION The DSRC technology can be helpful in future generation transportation systems without any doubt. The main function of DSRC microwave technology is highly dependent on cooperative standards for interoperability. In this paper, we have discussed DSRC in possible dimensions. The DSRC technology will facilitate connected autonomous vehicle environment in VANET with safety enable feature. It means in this state, the vehicle provides all advanced and modern technology features autonomously. DSRC standard is tremendous powerful protocol for VANET communication.

International
We also discussed MAC protocols used for providing best service properly broadcast a safety message among vehicles and infrastructure. There are many other protocols to address the various problems in VANET system communication. The standards of DSRC are being updated day-to-day. Currently, we are controlling 70%-80% accidents using DSRC technology throughout the globe. DSRC has unique characteristics to enable intelligent transportation system safely. Currently, groups such as VSCC (Vehicle Safety Communication Consortium) are working to invent new protocols for DSRC. And another group CAMP (Crash Avoidance Metrics Partnership) is an automobile manufacturer including GM and ford, which is working on the realization of the collision avoidance components for DSRC. The CAMP IVI (CAMP Intelligent Vehicle Initiative) is a research program that brings together a number of automobile manufacturers and supplies the work cooperatively with US DOT (US Department of Transportation). In this connection, there are some concerns in widespread deployment but progress in technology. The technologies invented now, may not implement in this generation because VANET provides unlimited opportunities but may implement in future. And future VANET system, definitely offers tremendous opportunities and best services to its users through tremendous protocols to increase the transportation facility by reducing traffic fatalities and vehicles collisions. US DOT wants 100% free accident zone by 2050 using this tremendous technology involving new powerful protocols.