An ad hoc network is a decentralized wireless network formed spontaneously by wireless devices without a preexisting infrastructure. Ad hoc networks are wireless local area networks where devices communicate directly instead of through an access point. Each device participates in routing by determining routes using a routing algorithm and forwarding data. There are different types of ad hoc networks including self-organizing, mobile, vehicular, and smartphone networks. Vehicular ad hoc networks use vehicles as mobile nodes and differ from other networks due to their high dynamic topology and predictable mobility. Some challenges of ad hoc networks include quality of service, limited resources, scalability, and security such as denial of service attacks.

1. ADHOC NETWORK
BY AB

2. ADHOC NETWORK
• An AD Hoc network is one that is spontaneously formed when devices connect
and communicate with each other. the term ad hoc is a latin word that literally
means "for this " implying improvised or impromptu.
• Ad hoc networks are mostly wireless local area networks (lans). The devices
communicate with each other directly instead of relying on a base station or
access points as in wireless lans for data transfer co-ordination. Each device
participates in routing activity, by determining the route using the routing
algorithm and forwarding data to other devices via this route.

3. TYPES OF ADHOC NETWORK
• SELF ORGANIZING AD HOC NETWORK
• MOBILE AD HOC NETWORK (MANET)
• VEHICULAR AD HOC NETWORK
• SMARTPHONE AD HOC NETWORK

4. SELF ORGANIZATION IN AD HOC NETWORK
• Self organization is used for building scalable systems consisting of huge
numbers of subsystems.
• The primary objectives are coordination and collaboration on a global goal.
• The communication between nodes of an ad hoc network is organized in a local
manner, this means there is no centralized coordinator that controls the nodes.
• The primary objectives are improved scalability and dynamic adaptation to
changing environmental conditions.

5. PROPERTIES OF SELF ORGANIZING ADHOC
NETWORK
1. SELF-HEALING
2. SELF-CONFIGURATION
3. SELF-MANAGEMENT
4. SELF-OPTIMIZATION
5. ADAPTATION

6. PROBLEM FACED IN SELF ORGANIZING AD
HOC
• Where to run which (part of the) application and how to
distribute data and activity over the network?

7. VEHICULAR AD HOC NETWORKS
• VANET uses vehicles as mobile nodes are a sub class of mobile ad hoc networks
(manets) to provide communications among nearby vehicles and between
vehicles and nearby roadside equipment but apparently differ from other
networks by their own characteristics
• VANET posses a unique characteristics such as high dynamic topology and
predictable mobility.
• Due to the characteristics of vanets such as high dynamic topology and
intermittent connectivity, the existing routing algorithms in manets are not
available for most application scenarios in vanets.

8. PROBLEM FACED IN VANETS
• DESIGNING A VANET THAT MEETS ALL THE IEEE 802.11 STANDARD
REQUIREMENTS WITH THE HELP OF OPTIMAL ROUTING PROTOCOL THAT
IMPROVES CONNECTIVITY AMONG AD HOC NETWORKS

9. DOS ATTACKS IN MOBILE AD-HOC
NETWORKS
• MOBILE AD HOC NETWORKS ARE CALLED MANETS.
• NOWADAYS IT IS OFTEN THAT AN DOS ATTACK IS HELD ON SOME AD HOC
NETWORKS.
• EACH NODE IN A MANET IS CAPABLE OF ACTING AS A ROUTER.

10. TYPES OF DOS ATTACK
• WORMHOLE ATTACK
• BLACKHOLE ATTACK
• GRAYHOLE ATTACK

11. ADVANTAGE OF AD HOC NETWORK
• SEPARATION FROM CENTRAL NETWORK ADMINISTRATION.
• SELF-CONFIGURING NODES ARE ALSO ROUTERS.
• SCALABILITY INCORPORATES THE ADDITION OF MORE NODES.
• FLEXIBLE AD HOC CAN BE TEMPORARILY SETUP AT ANYTIME, IN ANY PLACE.

12. CHALLENGES OF ADHOC NETWORK
• QOS (QUALITY OF SERVICE)
• LIMITED RESOURCES
• SCALABILITY
• SECURITY

13. REFERENCES
1. “Self-organization in ad hoc networks: overview and classification” by Falko
Dressler.
2. “Vehicular ad hoc networks: architectures, research issues, methodologies,
challenges, and trends” by Wenshuang Liang, Zhuorong Li, Hongyang Zhang,
Shenling Wang, and Rongfang Bie.
3. “Dos attacks in mobile ad-hoc networks” by Rutvij h. Jhaveri, Sankita J. Patel
and Devesh C. Jinwala.
4. “Managing ad hoc networks of smartphones” by Tiancheng Zhuang, Paul
Baskett, and Yi Shang
5. “Applications, advantages and challenges of ad hoc networks” by D. Helen and
D. Arivazhagan