Vehicular Ad Hoc Networks (VANets) is becoming an emerging trend to meet the various demands in real time application. In these networks, vehicles communicate with each other and possibly with a roadside infrastructure to provide a long list of applications varying from transit safety to drive assistance and Internet access Most of the concerns of interest to mobile ad hoc networks (MANETs) are of interest in VANETs, but the details differ. Rather than moving at random, vehicles tend to move in an organized fashion. The interactions with roadside equipment can likewise be characterized fairly accurately.
Most vehicles are restricted in their range of motion. Such a network might poses safety concerns for example, one cannot safely type an email while driving. GPS and navigation systems might benefit, as they could be integrated with traffic reports to provide the fastest route to work. It was also promoted for free, VoIP services such as Google Talk or Skype between employees, lowering telecommunications costs. The future features of vehicular adhoc networks are taken into consideration by S-LOGIX with an angle to emphasize on emerging domains for real time applications.
Developing a new Protocol for VANET using NS2
Extension to the existing protocols or modeling a new Protocol in NS2 for VANET can be done in the following aspects. The protocols are developed as C++ files, and the dependent files are modified in the NS-allinone package. The directory structure of the newly added files is mentioned in Makefile. Then NS is rebuilt using Linux utility tool make. Simulation is carried out by mentioning the newly developed protocol in the TCL configuration file. Implementation aspects of NS2 for the VANET protocols are as follows.
Implementation Solutions for VANET configuration using NS2
- Vehicles and RSUs are required to configure with different communication range as low and high respectively.
- IEEE 802.11p is the appropriate protocol to be used in VANET in MAC layer which can be done through configuring Mac/802_11Ext and Phy/WirelessPhyExt objects and with some changes in physical layer files.
- Nakagami with parameter specification is required to be used as a signal propagation model.
Implementation Solutions for Mobility Model in VANET using NS2
- Simulation of Urban MObility (SUMO) tool can be used to create real world vehicular network model on the road.
- MOVE which is built on the SUMO can be used to generate mobility model trace file that can be executed by NS2. In MVOE, the roadmap can be created either manually or imported from real world maps.
- More realistic mobility model OSM can be generated using Open Street Map project, and the resultant osm file can be imported in SUMO to generate the TCL file that can be executed in NS2.
Implementation Solutions for Safety Message Dissemination in VANET using NS2
- As the safety messages need broadcast, routing protocols are modified to either unicast or broadcast the data based on the packet type non-safety or safety respectively that is mentioned in the application layer.
Implementation Solutions for Geographic Routing Issues in VANET using NS2
- Since the geographic routing protocol is more suitable in VANET, the corresponding GPSR routing protocol files can be patched to NS package, and its advancement such as opportunistic routing can be done by exploiting overhearing functionality and data cache maintenance at the node by modifying GPSR files.
- Adaptive Beaconing for congestion control related issues can be implemented through the adjustment of beacon interval dynamically.
Implementation Solutions based on bio-inspired algorithms in VANET using NS2
- Bio-inspired algorithms such as ACO, PSO, Genetic, cuckoo search and dragonfly algorithms can be integrated to the protocols as per their functionality requirement in different layers.
Implementation Solutions for Security Issues in VANET using NS2
- Various attacks such as Sybil, false event generation, black hole, gray hole, wormhole, flooding, misrouting, modification, jellyfish, and other attacks can be modeled by modifying the behavior of the attacker nodes in corresponding protocol files.
- Attack detection techniques such as location identification from beacons can be integrated into protocol functionality in the respective files.
- Intrusion detection system based on trust measurement techniques can be accomplished with MAC and routing protocol modifications.
- Cryptography algorithms such as RSA, ECC, HMAC can be integrated with security related solutions such as privacy,authentication,data confidentiality and integrity.
Implementation Solutions for transport layer protocols in VANET using NS2
- Protocols in the transport layer, such as TCP and UDP can be modified for performance improvement solutions related to data flow control.
Implementation Solutions for cross-layer issues in VANET using NS2
- Parameters such as signal strength, energy, queue size, packet priority can be attached either to beacon or data packets so that it can be accessed in protocols of other layers to develop the cross-layer solutions.
Performance Analysis of VANET using NS2
Network Performance of VANET varies depends on various network characteristics
Impacts on Network Performance
Impact on mobility of vehicles
– Pause time
– Type of mobility model (OSM)
Impact of Network traffic
– Number of communication flows
– Data rate of each flow subject to the constraints of the number of channels and interfaces, and bandwidth of the channel
Impact of node density
– Number of nodes in the network,
– Area of the network
– Distance between source and destination
– Number of RSUs
– Distance between RSUs
Impact on physical layer properties of the vehicle
– Communication range of vehicle and RSUs
– Transmission power of the vehicle and RSUs
Impact in Attack scenarios
– Number of attackers
– Percentage of malicious behavior
Impact on selection of the protocol at each layer
- The impact can also be observed with the selection of the protocol at each layer. One example of this is with the same scenario, the choice of signal propagation types such as Two Ray Ground or Nakagami in physical layer can make the difference in results.
Impact on protocol specific feature
- One such kind of variation is evaluating the performance for various beacon periods of the routing protocol.
Performance Metrics in VANET Using NS2
- Packet Delivery Ratio (PDR)
- Average End to End Delay
- Routing Overhead
- Control Overhead
- Storage overhead
- Packet drop rate
- Hop count
- Attack detection accuracy
- Attack detection time
- False Alarm
There are numerous metrics depends on the proposed approach and the network scenarios apart from the above. AWK script for these metrics can be applied to process the trace file that consists of the information such as event time, event type, node ID, packet sequence number, type and size of the packet, the layer at which the event occurs, the reason for packet drop, and TTL. The results from the execution of AWK script can be plotted as Xgraph in NS2 for the purpose of self or comparative protocol analysis.