Introduction to Ad-Hoc Network
According to Oxfords advanced learners dictionary an ad-hoc is defined as “Arranged or happening when necessary and not planned in advanced”. This explains what ad hoc networks are, to say networks set up on the fly for a special purpose. Furthermore ad-hoc networks are usually such networks that are set up for one time occurrences (temporary purpose) such as conferences or military operations.
In wireless computer networks, an ad-hoc mode is a method for wireless devices to directly communicate with each other. Performing in an ad-hoc mode allows all wireless devices within range of each other to discover, communicate and data share in peer-to-peer pattern without involving any centralized access points.
To set up an ad-hoc wireless network, each wireless adapter must be configured for ad-hoc mode versus the alternative infrastructure mode. In addition, all wireless adapters on the ad-hoc network must use the same SSID and the same channel number.
An ad-hoc network tends to feature a small group of devices all in very close proximity to each other. Performance suffers as the number of devices increases, and a large ad-hoc network quickly becomes difficult to manage. Ad-hoc networks cannot bridge to wired LANs or to the internet without installing a special-purpose gateway.
“An ad-hoc network is a collection of mobile nodes, which forms a
temporary network dynamically without used of any existing fixed
network infrastructure or centralized administer”.
Due to limited communication range among mobile nodes, several other network nodes (which act as a router) may be needed to deliver a packet from one node to another node in the wireless network. In such a network each mobile node may acts as an end node as well as a relay node (router).
Ad hoc network is self organized network whose nodes are free to move randomly while being able to communicate with each other without the help of an existing network infrastructure.
The ad-hoc network generally refers as the networks in which all device nodes has equal status in a network and which can freely associate with any other ad-hoc network device node in link range. A wireless networks provide the ad hoc network which refers to a mode of operation of IEEE 802.11.
Networks are formed on-the-fly, devices can leave and join the network during its lifetime, devices can be mobile within the network, the network as a whole may be mobile and the network can be deformed on-the-fly. Devices in mobile ad hoc networks should be able to detect the presence of other devices and perform the necessary set-up to facilitate communications and the sharing of data and services.
According to the different application of ad-hoc network, there are mainly three classified types of an ad-hoc network formed.
1) MANET (Mobile Ad-hoc Network):
The temporary network of more than one mobile devices for the communication.
2) VANET (Vehicular Ad-hoc Network):
The temporary network of more than one moving vehicles on the road for communication.There may be communication in between vehicle to vehicle (V2V) or vehicle to any fixed infrastructure road side unit (V2I).
3) FANET (Flying Ad-hoc Network):
The temporary network of more than one flying planes (Unmanned Aerial Vehicle - UAV) for communication. There is communication in between UAV to UAV or UAV to infrastructure at ground base station.
