What is a Mobile Ad Hoc Network? It is a collection of mobile nodes, such devices as PDAs, mobile phones, laptops etc., that are connected over a wireless medium. Thee is no pre-existing communication infrastructure (no access points, no base stations) and the nodes can freely move and self-organize into a network topology.
Such a network can contain two or more nodes. Every owner of a mobile phone equiped with a bluetooth module can build up a direct connection to the other phone and exchange data. It’s the simpliest form of an ad hoc network, one hop piconet. Only one hop is actually not so exciting. Mobile multi-hop ad hoc networks are much more interesting. There are three classes of such networks.
- MANets – Mobile Ad-hoc Networks. It”s the classical ad hoc network that came from the military sector. These networks were developed to connect planes, tanks, troops at the battlefield. They are completely self-organizing. The other possible areas where they could be applied are disaster recovery, car-to-car communication, home networking. This class of ad hoc networks can be seen as the forefather of the other classes.
- WMN – Wireless Mesh Networks. Like MANets, but there is a set of nodes, stationary mesh routers which form a wireless multi-hop ad hoc backbone. The mesh routers can be connected to the Internet and thus all the participants of the backbone have an access to the Internet. Imagine you are at the airpot where there are only few access points (mesh routers). You have no direct contact to a one, but still you have an Internet access due to the other guests of the airport. The mesh routers make the routing task more simple and the protocols running on them allow the backbone to be easy to set up and self healing.
- WSN – Wireless Sensor Networks. This special class of ad hoc networks is used to monitor some phenomenon in a certain area. The nodes have often only the simple task to deliver the monitoring information such as measured temperature, air polution, median speed of the cars on a highway etc. to the minitoring system. The devices partitipating in a sensor network are just special sensors that differ greatly in their purpose from the user devices. Thus the solutions designed for the general multi-hop ad hoc networks where mobile devices execute such applications as Skype, instant messaging, streaming applications etc., just don’t suite for sensor networks.
The idea of ad hoc networks is not that very innovative. It’s almost as old as the Internet. In the last years the interest to the ad hoc networks has grown very much. Especially in the car and entertainment industry.