AdHoc_VANET_Presentation UG Student level

Vanet

1. Ad Hoc and VANET Networks Overview and Technical Insights CHAPTER 1 INTRODUCTION ADHOC NETWORK A wireless ad hoc network is a decentralized type of wireless network. The network is ad hoc because it does not rely on a pre existing infrastructure, routers in wired networks or access point in managed wireless networks. Each node participates in routing by forwarding data for other nodes. In addition to the classic routing, ad hoc networks can use flooding for forwarding data. An ad hoc network typically refers to any set of networks devices have equal status on a network and are free to associate with any other ad hoc network device in link range. Ad hoc network often refers to a mode of operation of IEEE 802.11 wireless networks figure1.1 Figure 1.1 Models of Adhoc Networks 1.2 APPLICATIONS The decentralized nature of wireless ad hoc networks makes them suitable for a variety of applications central nodes can't be relied on and may improve the scalability of networks compared to wireless managed networks, though theoretical and practical limits to the overall capacity of networks have been identified. Minimal configuration and quick deployment make ad hoc networks suitable for emergency situations like natural disasters or military conflicts. The presence of dynamic and adaptive routing protocols enables ad hoc networks to be formed quickly. Technical Requirements: An ad hoc network is made up of multiple nodes connected by links. Links are influenced by the node's resources as transmitter power, computing power and memory and behavioral properties as well as link properties length of link and signal loss, interference and noise. Since links can be connected or disconnected at any time, a functioning network must be able to cope with this dynamic restructuring, preferably in a way that is timely, efficient, reliable, robust, and scalable. Mathematical models : In recent years mathematical models have been proposed to study various types of wireless ad hoc networks. One class of models involves using stochastic processes to represent the placement of the nodes in the ad hoc network. More specifically, stochastic geometry models of wireless networks have been proposed and studied. 1.3 VANET Vehicular ad hoc networks are a special form of wireless networks made by vehicles communicating among themselves on roads. As communication links break more frequently in VANET than in MANET, the routing reliability of highly dynamic networks needs to be paid special attention. The extended evolving graph helps capture the evolving characteristics of the vehicular network topology and determines the reliable routes preemptive figure 1.2. Figure 1.2: Architecture of vehicular ad hoc network Vehicular Sensor Nodes: Vehicular sensor nodes are carried by the vehicles. These nodes are supposed to sense the real phenomena e.g. the velocity of the vehicle. The sensor readings are to be sent to the base stations via RSS nodes. These nodes can communicate with each other or the roadside sensor via short-range communication. Road Side Sensors (RSS): Road Side Sensors are deployed in a fixed distance beside the road. RSSs act as cluster heads for vehicular nodes. RSS nodes receive the data from mobile nodes and retransmit towards the BSs. These nodes are equipped with two kinds of antenna, unidirectional and bidirectional. Base Station (BS): Base stations are Police Traffic Control Check-Post, Rescue Team Buildings or Fire Fighting Stations in some fixed point trough the roads. Mobile BS like, Traffic Police patrolling team, Firefighting Truck, or ambulance. On Board Unit (OBU) : Wireless sensor nodes complement other sensors installed in a car as radar. Once a vehicle has processed the sensor data, it may interpret the data as a dangerous situation and trigger a safety warning message. The vehicle determines a geographical region defined by a geometric shape and broadcasts the message to its neighbor vehicles. The communication system of the vehicles ensures that the data packet is reliably distributed to all vehicles located within a region. Emergency Vehicle Awareness: This will alert vehicles that are in the path of an emergency vehicle are able to get out of the way even before a siren or lights are noticed. It will make the driving experience safer as the driver will not have to look around to see the emergency vehicle is approaching. Roadwork Awareness: Road crews will be able to place roadside units around their worksites so that the driver is alerted about the upcoming driving hazard. This will make traffic flow more effectively and provide a safer working environment for road crews. Collision Prevention: This will alert the driver of vehicles that may not be seen because of obstructions at intersections. It will also alert the driver if approaching a vehicle at speed. Driving Conditions: The driver will be made aware of the weather conditions that will affect the road as snow, rain and ice. It will also notify the driver of upcoming accidents and traffic jams. The navigation system to recalculate the fastest route to the driver desired destination. Driving Services: VANET will also make services pay-as-you-drive and fleet management more easily manageable. Internet Connectivity: Vehicles will also be connected to the Internet, which will provide limitless opportunities for vehicle Internet applications to make the driving experience more enjoyable. 1.4 CHALLENGES ON VANET The design of the transport protocol for VANET is rather at its initial phase. There is no transport protocol tailored for vehicular networks and it is also very complex to either design new protocols or adapt existing protocols by modifications or enhancement. The transport of messages must be completely error free because their will most likely be no time to retransmit the message, especially in emergency situations. Transport messages must be error free because a message will not be able to be retransmitted in the case two cars are passing each other while going in opposite directions. VANET will have to refine its transport layer protocols significantly from current ad hoc network transport technologies. The current challenges that need to be overcome to create a successful transport protocol are the fact that high packet loss rates, long round trip times, short connection durations, high probability of packet reordering are part of the reality of current ad hoc networks. Mobile ad hoc networks add to the complexity due to the fact that the nodes are travelling at high rates of speed. CHAPTER 2 LITERATURE REVIEW A wireless ad hoc network is a decentralized type of wireless network. The network is ad hoc because it does not rely on a pre existing infrastructure, routers in wired networks or access point in managed wireless networks. Vehicular Ad hoc Networks are a special form of wireless networks made by vehicles communicating among themselves on roads. The conventional routing protocols proposed for Mobile Ad hoc Networks poorly in VANETs. As communication links break more frequently in VANET than in MANET, the routing reliability of highly dynamic networks needs to be paid special attention. P. Varaiya (1993) proposed Smart cars on smart roads problems of control. Development of a real time system for monitoring traffic scenes using video information and vision module provides the detection of other vehicle and measurement of their distance and estimation of the flow of lane markers and of road curvature. M. Treiber and A. Hennecke (2000) proposed Congested traffic states in empirical observations and microscopic simulations. The proposed intelligent-driver model (IDM) is simple, has only a few intuitive parameters with realistic values, reproduces a realistic collective dynamics, and also leads to a plausible “microscopic” acceleration and deceleration behavior of single drivers. R. Hall and C. Chin (2005) proposed Vehicle sorting for platoon formation Impacts on highway entry and throughput. Automated Highway System is intended to increase the throughput and safety of roadways through computer control, communication and sensing. In the platoon concept for AHS, vehicle travel on highways in closely spaced groups. Within a platoon, vehicle are separated by very short distances 1m spacing from platoon to platoon can be considerably longer to minimize the platoon collide with each other. B. Van Arem et al (2006) developed the Impact of Cooperative Adaptive Cruise Control on Traffic-Flow Characteristics. Cooperative adaptive cruise control (CACC) is an extension of ACC. The results show an improvement of traffic flow stability and a slight increase in traffic flow efficiency compared with the merging scenario without equipped vehicles. T. Acarman and U. Ozguner (2006a) proposed intelligent cruise control stop and go with and without communication, the GPS navigation system provides guidance input to the ACC. A conventional ACC would sense the car in front was decelerating and it would simply apply brakes accordingly. S. Yousefi, E. Altman and R. El-Azouzi (2007) proposed Study of connectivity in vehicular ad hoc networks Investigate connectivity in ad hoc network formed between vehicles that move in the same direction on a typical highway. Kesting and M. Treiber (2008) proposed How reaction time, update time, and adaptation time influence the stability of traffic flow modeling the acceleration and deceleration of drivers, there are three characteristic time constants that influence the dynamics and stability of traffic flow. V. Sadatpour et al (2009) introduced Scheduling algorithm for beacon safety message dissemination in vehicular ad-hoc networks Beacon safety message dissemination in Vehicular Ad-hoc Networks (VANET) suffers from poor reliability especially in congested road traffics. T. Taleb et al (2010) proposed Toward an Effective Risk-Conscious and Collaborative Vehicular Collision Avoidance System. The Cooperative collision avoidance (CCA) scheme for intelligent transport system and the risk aware medium access control (MAC) protocol to increase the responsiveness of the proposed CCA system. P. Kavathekar (2011) proposed Vehicle platooning A brief survey and categorization Vehicle platooning is an important innovation in the auto-motive industry that aims at improving the safety, mileage, efficiency and the time needed to travel. Autonomous capable vehicles in tightly spaced, computer controlled platoons will lead to savings in fuel, increased highway capacity and increased passenger comfort. J. Ploeg et al (2011a) proposed design and experimental evaluation of cooperative adaptive cruise control. In recent years, high way capacity has become a limiting factor, regularly causing traffic jams. Obviously the road capacity can be increased by decreasing the inter vehicle distance while maintaining the same velocity level. ACC automatically adapts the velocity of the vehicle so as to realize a desired distance to the preceding vehicle. The inter vehicle distance and relative velocity are measured by means of a radar or scanning laser. ACC is primarily intended as a comfort system. P. Fernandes (2012) proposed Platooning with IVC-enabled autonomous vehicles: Strategies to mitigate communication delays improve safety and traffic flow Proposed for intraplatoon information management strategies for dealing with safe and stable operation. Inter vehicle communication (IVC) is emerging as a prominent technology for helping in reducing traffic congestion. Recent technological advances on communication, Dedicated Short Range Communication (DSRC) S. Vodopivec et al (2012a) introduced a survey on clustering algorithms for vehicular ad-hoc networks. Clustering is a technique for grouping nodes in geographical vicinity together, making the network more robust and scalable. The clustering algorithm used in vehicular ad hoc network it can be improved cluster life time and vehicle connectivity Tapani (2012b) is proposed Vehicle trajectory impacts of adaptive cruise control Adaptive Cruise Control (ACC) is assumed to have a potential to improve quality of service and safety and to reduce the environmental impact of the road traffic system. The results of ACC equipped vehicle use lower acceleration and deceleration rates than standard non-equipped vehicles. The most difficult challenge in the scenario is to deal with frequent route breakages due to dynamic mobility of vehicles on the road. The frequent route failures result in a significant amount of time needed for repairing existing routes or reconstructing new routes. In spite of the dynamic mobility, the motion of vehicles on highways is quite predictable compared to other mobility patterns for wireless ad hoc networks, with location and velocity information readily available. This can be exploited to predict how long a route will last between a vehicle requiring Internet connectivity and the gateway that provides a route to the Internet. Successful prediction of route lifetimes can significantly reduce the number of route failures. CHAPTER 3 A DISTURBANCE-ADAPTIVE DESIGN FOR VANET-ENABLED VEHICLE PLATOON 3.1 ROUTING RELIABILITY The design of effective vehicular communications poses a series of technical challenges (1993). Guaranteeing a stable and reliable routing mechanism over VANET is an important step towards the realization of effective vehicular communications (2000). In current ad-hoc routing protocols, the control messages in reactive protocols and route update timers in proactive protocols are not used to anticipate link breakage. The route maintenance process at both protocol types is initiated only after a link breakage event takes place (2005). Vehicles are grouped according to their velocity vectors. A vehicle shifts to a different group and a route, involving the vehicle, is to be broken, the proposed protocol searches for a more stable and more durable route that includes vehicles from the same group Velocity Heading Based Routing Protocol (VHBP). The performance of the scheme is evaluated through computer simulations by destination sequence routing protocol. Simulation results indicate that knowledge on the vehicles heading adds major benefits to routing in terms of reducing the number of link breakage events and increasing the end-to-end throughput. 3.1.1 LOCATION-AWARE ROUTING PROTOCOLS Many location-aware routing protocols have been proposed for mobile ad hoc networks. The efficiency of the routing protocols can be improved by considering the location information of the mobile nodes. The mobility characteristics of the MNs have not been taken into account in most of the related work. The velocity-aided routing (VAR) algorithm determines its packet forwarding scheme based on the relative velocity between the intended forwarding node and the destination node. The routing performance can further be improved by the proposed predictive mobility and location-aware routing (PMLAR) algorithm, which incorporates the predictive moving behaviors of MNs in protocol design. The region for packet forwarding is determined by predicting the future trajectory of the destination node (2006). Simulation results show that the PMLAR protocol associated with its derivative schemes outperforms other routing protocols under different network topologies. 3.1.2 PREDICTION - BASED ROUTING PROTOCOL FOR VANETS Development in short-range wireless LAN (WLAN) and long-range wireless WAN (WWAN) technologies have motivated recent efforts to integrate the two. This creates new application scenarios that were not possible before. Vehicles with only WLAN radios can use other vehicles that have both WLAN and WWAN radios as mobile gateways and connect to the Internet while on the road. The most difficult challenge in the scenario is to deal with frequent route breakages due to dynamic mobility of vehicles on the road. Existing routing protocols that are widely used for mobile ad hoc networks are reactive in nature and wait until existing routes break before constructing new routes. The frequent route failures result in a significant amount of time needed for repairing existing routes or reconstructing new routes (2007). The motion of vehicles on highways is quite predictable compared to other mobility patterns for wireless ad hoc networks, with location and velocity information readily available. To predict how long a route will last between a vehicle requiring Internet connectivity and the gateway that provides a route to the Internet. Successful prediction of route lifetimes can significantly reduce the number of route failures (2008). The assessment of routing protocols for ad hoc networks is a difficult task, due to the networks highly dynamic behavior and the absence of benchmarks. Recently, a graph theoretic model the evolving graphs was proposed to help capture the network topology changes during time, with predictable dynamics at least. 3.1.3 MOVEMENT PREDICTION-BASED ROUTING (MOPR) ALGORITHM MOPR determines the most stable path from a source to a destination in terms of communication lifetime by selecting the most stable intermediate links, then, the best intermediate vehicles. Network protocol is capable to provide several unicast paths to a destination, one of those paths can result to be more stable with respect to the others. A stable path can increase the probability that link failures will be avoided during the whole communication. MOPR, based on vehicles movement information, guarantees the selection of the best next hop for data forwarding. Using MOPR, each vehicle estimates the Link Stability (LS) for each neighboring vehicle before selecting the next hop for the data forwarding sending. The LS is a relation between the link communication lifetime and a constant value σ which represents in general cases the routing route validity time, and it depends on the used routing protocol. 3.2 VEHICULAR RELIABILITY MODEL Coverage is an important problem in wireless networks. The coverage and access probability of the vehicular networks with roadside infrastructure, the coverage range of base stations, coverage range of vehicles, vehicle density and distance between adjacent base stations, and how these parameters interact with each other to collectively determine the coverage and the access probability (2010). All nodes in the network are connected to at least one base station within a designated number of hops, as a measure of the coverage. 3.2.1 Basis of Vehicular Traffic Flow Models There are two major approaches to describe the spatiotemporal propagation of vehicular traffic flows namely, macroscopic and microscopic traffic flow models. The macroscopic approach pictures the traffic flow as a physical flow of a continuous fluid. It describes the traffic dynamics in terms of aggregated macroscopic quantities are traffic density p(x, t), traffic flow q(x, t), and average velocity v(x, t) as a function of space x and time t corresponding to partial differential equations. These parameters can be related together by their average values using the following relations. dm - average distance between vehicles in meters. ρveh - traffic density on the freeway section considered in vehicles per kilometer lm - average length of vehicles in meters τm - average time gap between vehicles in seconds vm - average velocity of vehicles on the road in kilometers per hour qm - average traffic flow in vehicles per hour. 3.2.2 Link Reliability Model Link reliability is defined as the probability that a direct communication link between two vehicles will stay continuously available over a specified time period. Given a prediction interval Tp for the continuous availability of a specific link l between two vehicles at t, the link reliability value r(l) is defined as equation 3.1 r (l) = To continue to be available until t + T p | available at (3.1) To calculate the link reliability, utilize the vehicle’s velocity parameter. It is assumed that the velocity of vehicles has a normal distribution [13]. 3.3 EVOLVING GRAPH RELIABLE AD HOC ON-DEMAND DSDV PROTOCOL The Ad hoc On Demand Distance Vector Algorithm Our basic proposal can be called a pure on demand route acquisition system nodes do not lay on active paths neither maintain any routing information nor participate in any periodic routing table exchanges. A node does not have to discover and maintain a route to another node until the two need to communicate unless the former node is offering its services as an intermediate forwarding station to maintain connectivity between two other nodes, the local connectivity of the mobile node is of interest of each mobile node can become aware of the other nodes in its neighborhood by the use of several techniques including local no system wide broadcasts known as hello messages. The routing tables of the nodes within the neighborhood are organized to optimize response time to local movements and provide quick response time for requests for establishment of new routes the algorithms primary objectives are to broadcast discovery packets only necessary to distinguish between local connectivity management neighborhood detection and general topology maintenance. To disseminate information about changes in local connectivity to those neighboring mobile nodes that are likely to need the information AODV uses a broadcast route discovery mechanism as is also used with modifications in the Dynamic Source Routing DSR algorithm Instead of source routing AODV relies on dynamically establishing route table entries at intermediate nodes. To maintain the most recent routing information between nodes borrow the concept of destination sequence numbers from DSDV. Path Discovery The Path Discovery process is initiated, a source node needs to communicate with another node for which it has no routing information in its table. Every node maintains two separate counters a node sequence number and a broadcast id. The source node initiates path discovery by broadcasting a route request RREQ packet to its neighbors. Destination IP address Source IP address Broadcast id Expiration time for reverse path route entry Source nodes sequence number In highway, the density of vehicles may be lowering than that in urban. Traffic may become serious during the rush hours, while a sparse vehicles scenario are expected to appear at night or other idle daytime. In a high density environment, a large number of vehicles with wireless transceivers are co-exist in a communication zone, and the channel access contention problem is a crucial challenge for reliable transmissions with low delay. If the distance is greater than 1000m the source should find the frontrunner in the direction of the destination, frontrunner is the farthest vehicle within the coverage area of source vehicle. Now routing can be performed through the frontrunner. 3.4 EG-DIJKSTRA ALGORTHIM VARIABLES Distrel: Direction based Distance between two nodes FR: Frontrunner node T: ACK timer Tth: Timer threshold INPUT S: Source D: Destination BEGIN Step 1. Calculate Distrel between S and D Step 2. If Distrel <=1000 Step 3. Forward the packet to D Reset T=0. Start T waits for ACK. Step 4. While (T<Tth) Step 5: If ACK received goto step 4 else goto step 3 Step 6: else If Distrel>1000 Step 7: Find the FR Step 8: Forward packet to FR Reset T=0. Start T waits for ACK. Step 9: While (T==Tth) Step 10: If ACK not received goto step 8 Step 11: Set FR as S goto step 1 Step 13: If ACK received from D Step 14: Terminate CHAPTER 4 COOPERATIVE VEHICLE SAFETY SYSTEM FOR VANET 4.1 PROBLEM DEFINITION The routing protocol is proposed that determines its packet-forwarding scheme based on the relative velocity between the forwarding node and the destination node (2000). The region for packet forwarding is determined by predicting the future trajectory of the destination node based on its location information and velocity (2006). Cooperative vehicle safety system can be used to communicate between vehicles and Road side unit (2007). The DSDV protocol is designed to be comprehensive, simple and efficient for more reliable operation and it transmit the messages with in the short time, compared to existing one. The project adopts an IEEE 802.11 standard for wireless access and aim at implementing a reference system. To reduce the topology maintenance overhead and support more reliable routing, an option is to make use of evolving graph-based reliable routing scheme for VANET. That vehicles travel at high speeds on highways, the data delivery service could have many disruptions due to frequent link breakages. It is very important to ensure that the most reliable links are chosen a route (2008). The position information is used to guide the Cooperative vehicle safety system, efficiently reduces the overhead for route searching and maintenance (2009). Making use of the position information to design a VANET consist of Road side unit and On board unit for reliable communication figure 4.1 Figure 4.1 Cooperative vehicle safety systems CVSS mechanism describes three types of communication. 1. Inter vehicle communication. 2. Intra vehicle communication. 3. Vehicle to Road Side communication. Vehicle can communicate with other vehicle via wireless medium. Sensor used to detect the positions of all the vehicles and send it to the On Board Unit and transmit the messages to the Road side unit. 4.2 MODULE DESCRIPTION The proposed system includes two modules, VANET Framework Setup. Proposed Protocol Implementation. VANET FRAMEWORK SETUP Routing in a communication network is the process of forwarding a message from a source vehicle to a destination via wireless medium. A wireless ad hoc network consists of mobile nodes with wireless communication capabilities for specific sensing tasks. A very important category is driver assistance and car safety. This includes many different things mostly based on sensor data from other cars (2010). The warning sent from preceding car, tailgate and collision warning, information about road condition and maintenance, detailed regional weather forecast, premonition of traffic jams, caution to an accident behind the next bend, detailed information about an accident for the rescue team and many other things. The local updates of the cars navigation systems or an assistant that helps to follow a neighbor car (2012). PACKET SENDING FROM THE SOURCE VEHICLE The data transmission is interaction between an event as it unfolds in the transportation simulator and its dissemination to the vehicles using the network as embedded within the vehicles in its vicinity and the feedback to the transportation simulator the change in velocities and positions of the vehicles react in real-time to the information conveyed to them by the communication network. DSDV Routing Protocol DSDV is a proactive routing protocol. It uses bellman ford algorithm to find the best route. It uses a routing table to update with other routers sends the update messages. Time of sending update messages is depended either on topology changes or not. Without any topology changes this protocol sends the update messages to its neighbors every 15 seconds. Upon topology changes, it sends the message update regardless of time period. The update message in DSDV is classified based on its content. There are two types of update to aware nodes of the network that topology was changed. The first type is sent if topology is changed with few nodes, in this type the incremental update will be sent to the neighbors that includes the change of the routing table. The second type is full-table update which shows significant change in topology was occurred figure 4.2 Figure 4.2 Scenario In AODV, before a sender send a packet to destination, the source sends a RREQ packet to its neighbors and maintained the sender address and broadcast the RREQ till it reaches either to destination or an intermediate node that has a valid route to destination, then a RREP packet is unicasted to the source through the routing table that has been stored route back to the originator. The nodes add the next hop address to their routing table for destination during transferring the RREP. In AODV, link breakage occurs, a broken node would send a RERR packet includes all the nodes which are not accessible anymore to the sender and all intermediate nodes would be informed about the broken link and sender will generate a new RREQ to find a new route. Vehicles are required to be continuously aware of their neighborhood of few hundred meters and monitor possible threats. This task may be achieved by frequent real time communication between vehicles over Dedicated Short Range Communication (DSRC) channels. Inter-vehicle communication, roadside devices may also assist vehicles in learning about their environment by delivering traffic signal or pedestrian related information at intersections. The main requirement of these active safety systems is the possibility of delivering real-time acquired information to and between vehicles at latencies of lower than few hundred milliseconds. Prototypes of systems are being developed by many automotive manufacturers. In situational awareness safety applications, a vehicle is presented with information about possible hazards at locations that may be 30-60 seconds ahead of the vehicle. In DSRC based safety systems, the cyber components are selected and meet the requirements of active safety. The existing designs fall short of supporting a full-fledged CVS in which a large number of vehicles communicate and cooperate with each other. The main reason behind the issues with the current designs is the level of separation in the design of different components. CVS systems use two types of safety messages. 1. Even driven emergency messages. 2. Frequent vehicle tracking and collision avoidance messages. Event driven messages are only sent if a sudden change of state happens for a vehicle, for example as a result of a hard braking, or a crash. These messages are high priority, but are a small fraction of the messages that need to be sent. Periodic vehicle tracking messages make up the bulk of safety messages that are transmitted over the shared DSRC channel in a vehicle’s neighborhood. These messages are designed to include vehicle location and speed information, amongst other possible measures. Vehicles that receive these messages will parse them and form a map of their neighborhood to track their neighboring cars. The embedded CVS system in each car continuously analyzes the neighboring cars positions and predicts possible collisions. If an imminent threat is detected the driver is warned. The collision warning messages are only useful if delivered within a few hundred milliseconds. Therefore, the objective of vehicle tracking is to accurately track neighboring vehicles in real-time. In this architecture, a communication subcomponent is responsible for sending and receiving safety messages, a computing subcomponent is responsible for tracking neighboring vehicles, generating safety messages and managing communication time, transmission Control Logic and issuing warning indicators to the user-interface subcomponent, collision detection module. Traditional designs would follow a separate design process for each subcomponent. The acceptable performance requires that the design of computing subcomponent be tied to the design of the communication module. The service requested from the communication process is the transmission of packet and the time or frequency of packets sent at rate R packets/sec and length in bytes. In the CVS application, the size and format of packets and the channels over packets are sent are predetermined according to the safety standards. The controllable parameters are restricted to the rate of packet transmission and DSRC settings as power level. The design of safety systems from a Cyber Physical System (CPS) standpoint, and provide a new view into how interaction between different components of a CPS can be modeled and used in designing different components of the CPS of interest. Traditional methods of building cooperative safety systems relied on separate design of the cyber and physical components. Even in the design of cyber components, there is a tendency towards separation of concerns, thus designs, of different elements of computation and communication. Separation is indeed one of the reasons behind successful and quick development of many technologies and solutions, the success of designs is quickly overturned if resources are limited to a level that tight coupling between cyber and physical components and sub-components leads to significant performance degradation (2012). 4.3 AODV IN CVSS The requesting vehicle broadcasts an RREQ to all vehicles within range. The receiving vehicle first checks whether the current RREQ is not a duplicate packet. If it is, it will drop the packet. It will then check if the RREQ is from the same group by checking the group ID of the RREQ. If it is, it will then check whether it can provide the requested data or whether it has knowledge of a path that can provide this requested data. If it does, it will produce an RREP, else it will add its own address to the request packet and rebroadcast the packet. The RREP is reached at the source the most suitable path is chosen to obtain the data from it. A new route discovery is always initiated prior to the link being expired. This happens at a time t before the estimated LET. In addition to the group ID, the lifetime of the packet ensures that rebroadcasting of packets ceases after either certain number of rebroadcasts by different vehicles with the lifetime of a packet is reached. The Required Data field defines the requested data. The Required Time field defines the time needed for the data to be transmitted. The Group ID field identifies the group to which the requesting vehicle belongs. Hence, this mechanism avoids rebroadcasting the RREQ packet over vehicles which may usually provide unstable links belong to different velocity groups and also reduces the flooding of control messages in the network the scenario of five vehicles at an intersection vehicle B is turning onto a new street and the other four vehicles are continuing straight on the same road. Communication is possible the scenario of five vehicles at an intersection vehicle B is turning onto a new street and the other four vehicles are continuing straight on the same road. A connection is established between vehicles A and F. Communication is possible vehicle X receives a control message from another vehicle Y, it compares its group ID with that of the originating vehicle Y. Algorithm 1 Send Hello message Step 1: while Vehicle running! =stop do Step 2: Read current speed from the vehicle Step 3: if change in speed OR change in direction then Step 4: Generate hello message Step 5: Read destination coordinates and encapsulate in hello message packet Step 6: Broadcast () Step 7: end if Step 8: end while Algorithm 2 Receive Hello Message Step 1: nodeid: Unique vehicular identification Step 2: dx: destination x-coordinates Step 3: dy: destination y-coordinates Step 4: Read the nodeid,dx,dy,speed from the hello packet Step 5: Temporarily store the neighbouring vehicle information Step 6: Calculate the intervehicular distance Step 7: if nodeid exists in neighbouring table then Step 8: Update the neighbouring table with new values Step 9: Save the updated entry in the table Step 10: else create new row in neighbouring table Step 11: The row is named with vehicle nodeid Step 12: Insert the new vehicle information in it Step 13: end if. Algorithm 3 Send Data Packet Step 1: Generate data to send Step 2: Decide the destination vehicle Step 3: if nodeid is exists in the table then Step 4: Set destination vehicle as nodeid Step 5: Send packet Step 6: else if nodeid exists in packet information table then Step 7: Search the next hop in the packet table Step 8: Set the next hop with nodeid Step 9: Send packet Step 10: else set destination with Broadcastid Step 11: Send packet Step 13: end if Algorithm 4 Receive Data Packet Step 1: nodeid: Vehicle identification Step 2: Read destination nodeid Step 3: if nodeid is received vehicle id then Step 4: Read the data packet Step 5: else send data packet Step 6: end if Step 7: The sent packet information is maintained in packet. Equation Energy consumption= Average energy consumed on ideal, sleep, transmit, receiver/total energy consumed. Throughput = number of packet received/ time in second. Packet drop = Total number of packet received – total number of packet send. Delay = inter arrival of first packet time and second packet/ total data packet delivered time. Delivery ratio = number of packet received/number of packet send*100. CHAPTER 5 RESULTS AND DISCUSSION CVSS Cooperative Vehicle Safety System is evaluated with vehicular ad hoc network that a vehicle can communicates with the other vehicle via wireless communication. Cooperative vehicle safety system can communicates with the Road Side Unit (RSU) and On Board Unit (OBU) in the dynamic network, through simulations. The performance evaluation metrics and the comparison of the Cooperative vehicle safety system result are described through the NS2 Simulator. Five metrics to evaluate the performance of the proposed mechanism are given. The route life time is defined as the link between the transmitting and receiving vehicles in the dynamic network. The data delivery ratio is the ratio of the number of successfully received data packets reached to destination vehicle through wireless medium. The key features of NS2 simulator are: One of the most popular simulators among researchers. Simulation both wired and wireless network. Network protocol stack within C++. TCL (Tool Command Language) used for specifying scenario and events. TCL script simulates simple network topology and traffic Patten. Evaluate the performance of the networking protocol and operation. INPUT DESGIN Bandwidth for both channel 2Mb Beacon interval 1.0s Vehicle velocity 0-30m/s Number of nodes 100 TTL 32 Packet size 512bytes CBR data rate 128bytes/s Transmission range 120m Routing protocol AODV Mac Type 802.11 Source code for Cooperative vehicle safety system set num_nodes 93 set MESSAGE_PORT 42 set BROADCAST_ADDR -1 Define options set val(chan) Channel/WirelessChannel # channel type set val(prop) Propagation/TwoRayGround # radio-propagation model set val(ant) Antenna/OmniAntenna # Antenna type set val(ll) LL # Link layer type set val(ifq) Queue/DropTail/PriQueue # Interface queue type set val(ifqlen) 250 # max packet in ifq set val(netif) Phy/WirelessPhy # network interface type set val(mac) Mac/802_11 # MAC type set val(nn) 93 # number of mobilenodes set val(rp) AODV # routing protocol set val(x) 3500 # X dimension of the topography set val(y) 2000 # Y dimension of the topography set val(energymodel) EnergyModel # Energy Model set val(initialenergy) 1000 # value Phy/WirelessPhy set CPThresh_ 10.0 Phy/WirelessPhy set CSThresh_ 1.559e-11 Phy/WirelessPhy set bandwidth_ 2e6 # for 2Mbit Phy/WirelessPhy set Pt_ 0.2818 # for 250.0 Transmission Range set f6 [open n12-pdr.tr w] set f7 [open n11-pdr.tr w] set f8 [open n14-pdr.tr w] # *** Delay Trace *** set f15 [open n5-delay.tr w] set f16 [open n12-delay.tr w] set f17 [open n11-delay.tr w] Result Energy consumption Average energy consumed on ideal, sleep, transmit, and receive by the total energy consumed in figure 5.1 Figure 5.1 Energy Consumption X axis = time in second and Y axis = energy Throughput Throughput is usually measured in bits per second in figure 5.2 Figure 5.2 Throughput X axis = time in second and Y axis = throughput x 10^3 PACKET DROP Total number of packet received from the total number of packet send in figure 5.3 Figure 5.3 Packet drop X axis = time in second and Y axis = packet drop Delay The average time elapsed for delivering a data packet in figure 5.4 Figure 5.4 Average end to end delay X axis = time in second and Y axis = delay Packet Delivery Ratio Ratio of the number of received data packets to the number of total data packets sent by the source in figure 5.5 Figure 5.5 Packet delivery ratio X axis = time in second and Y axis = packet delivery ratio CHAPTER 6 CONCLUSION AND FUTURE ENHANCEMENT The development of intelligent vehicle safety systems is rapidly moving from autonomous systems relying on vehicle's own sensors towards cooperative systems utilizing Communications between vehicles or between infrastructure and vehicles. Cooperative vehicle safety system was developed for vehicles safety purpose. Ad-Hoc On demand Distance Vector (AODV) is one of the reactive routing protocols in wireless ad-hoc networks. The source vehicle sends a RREQ packet to its neighbors and maintained the sender address and broadcast the RREQ till it reaches either to destination or an intermediate node that has a valid route to destination, then a RREP packet is deliver to the source through the routing table that has been stored route back to the originator. The nodes add the next hop address to their routing table for destination during transferring the RREP. In AODV, link breakage occurs, a broken node would send a RERR message to a source node and again generate a new RREQ to find a new route. Vehicles travel at high speeds on highways, the data delivery service could have many disruptions due to frequent link breakages. 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