Vehicular Ad-hoc Networks

My publications in this field are (link) - 

• Biplav Choudhury, Vijay K. Shah, Avik Dayal, Jeffrey H. Reed, Joint Age of Information and Self Risk Assessment of 802.11p based V2V Networks, IEEE Conference on Computer Communications (IEEE INFOCOM), 2021. (Acceptance Rate = 252/1266 = 19.9%). 

• B. Choudhury, V. K. Shah, A. Dayal and J. H. Reed, "Experimental Analysis of Safety Application Reliability in V2V Networks," 2020 IEEE 91st Vehicular Technology Conference (VTC2020-Spring), Antwerp, Belgium, 2020, pp. 1-5, doi: 10.1109/VTC2020-Spring.

• G. Naik, B. Choudhury and J. Park, "IEEE 802.11bd & 5G NR V2X: Evolution of Radio Access Technologies for V2X Communications," in IEEE Access, vol. 7, pp. 70169-70184, 2019.

The Vehicular Ad-Hoc Network, or VANET, is a technology that uses moves cars as nodes in a network to create a mobile network. VANET turns every participating car into a wireless router or node, allowing cars approximately 100 to 300 metres of each other to connect and, in turn, create a network with a wide range. As cars fall out of the signal range and drop out of the network, other cars can join in, connecting vehicles to one another so that a mobile Internet is created.

Its applications are:

• Collision Avoidance: According to some studies, 60% accidents can be avoided if drivers were provided a warning half a second before collision. If a driver get a warning message on time collision can be avoided. 

• Cooperative Driving: Drivers can get signals for traffic related warnings like curve speed warning, lane change warning etc. These signals can co-operate the driver for an uninterrupted and safe driving. 

• Traffic optimization: Traffic can optimized by the use of sending signals like jam, accidents etc. to the vehicles so that they can choose their alternate path and can save time. 

Characteristics of VANET:

• High Mobility: The nodes in VANETs usually are moving at high speed. This makes harder to predict a node’s position and making protection of node privacy.

• Rapidly changing network topology: Due to high node mobility and random speed     of vehicles, the position of node changes frequently. As a result of this, network topology in VANETs tends to change frequently.

• Unbounded network size: VANET can be implemented for one city, several cities or for countries. This means that network size in VANET is geographically unbounded.

• Frequent exchange of information: The ad hoc nature of VANET motivates the    nodes to gather information from the other vehicles and road side units. Hence the   information exchange among node becomes frequent.

•  Wireless Communication: VANET is designed for the wireless environment. Nodes are connected and exchange their information via wireless. Therefore some security measure must be considered in communication.

• Time Critical: The information in VANET must be delivered to the nodes with in time limit so that a decision can be made by the node and perform action accordingly.

• Sufficient Energy: The VANET nodes have no issue of energy and computation resources. This allows VANET usage of demanding techniques such as RSA, ECDSA implementation and also provides unlimited transmission power.

• Better Physical Protection: The VANET nodes are physically better protected. Thus,VANET nodes are more difficult to compromise physically and reduce the effect of infrastructure attack.

CHALLENGING ISSUES IN VANET 

• Network Management: Due to high mobility, the network topology and channel condition change rapidly. Due to this, we can’t use structures like tree because these structures can’t be set up and maintained as rapidly as the topology changed.

• Congestion and collision Control: The unbounded network size also creates a challenge. The traffic load is low in rural areas and night in even urban areas. Due to this, the network partitions frequently occurs while in rush hours the traffic load is very high and hence network is congested and collision occurs in the network.

• MAC Design: VANET generally use the shared medium to communicate hence the MAC design is the key issue. Many approaches have been given like TDMA, SDMA, and CSMA etc. IEEE 802.11 adopted the CSMA based Mac for VANET.

• Security: As VANET provides the road safety applications which are life critical therefore security of these messages must be satisfied. 

Security Challenges in VANET 

• Real time Constraint: VANET is time critical where safety related message should be delivered with 100 ms transmission delay. So to achieve real time constraint, fast cryptographic algorithm should be used. Message and entity authentication must be done in time.

• Data Consistency Liability: In VANET even authenticate node can perform malicious activities that can cause accidents or disturb the network. Hence a mechanism should be designed to avoid this inconsistency. Correlation among the received data from different node on particular information may avoid this type of inconsistency.

• Low tolerance for error: Some protocols are designed on the basis of probability. VANET uses life critical information on which action is performed in very short time. A small error in probabilistic algorithm may cause harm.

• Key Distribution: All the security mechanisms implemented in VANET dependent on keys. Each message is encrypted and need to decrypt at receiver end either with same key or different key. Also different manufacturer can install keys in different ways and in public key infrastructure trust on CA become major issue. Therefore distribution of keys among vehicles is a major challenge in designing a security protocols.

• Incentives: Manufactures are interested to build applications that consumer likes most. Very few consumers will agree with a vehicle which automatically reports any traffic rule violation. Hence successful deployment of vehicular networks will require incentives for vehicle manufacturers, consumers and the government is a challenge to implement security in VANET.

• High Mobility: The computational capability and energy supply in VANET is same as the wired network node but the high mobility of VANET nodes requires the less execution time of security protocols for same throughput that wired network produces. Hence the design of security protocols must use the approaches to reduce the execution time. Two approaches can be implementing to meet this requirement.

• Low complexity security algorithms: Current security protocols such as SSL/TLS, DTLS, WTLS, generally uses RSA based public key cryptography. RSA algorithm uses the integer factorisation on large prime no. which is NP-Hard. Hence decryption of the message that used RSA algorithm becomes very complex and time consuming. Hence there is need to implement alternate cryptographic algorithm like Elliptic curve cryptosystems and lattice based crypto-systems. For bulk data encryption AES can be used.

• Transport protocol choice: To secure transaction over IP, DTLS should be preferred over TLS as DTLS operates over connection-less transport layer. IPSec which secures IP traffic should be avoided as it requires too many messages to set up. However IPSec and TLS can be used when vehicles are not in motion. 

It is a very interesting topic with a wide variety of techniques used. With the coming of driver-less cars, more and more transport providers will try to work out a VANET model for their services and this can be expected to have a widespread adoption across all countries.