Wednesday, December 1, 2004

Concept and operation requirements of mobile ad-hoc networks


By Humayun Bakht

Wireless communication networks have been in use since the 1980's. Their quality of service is improving with the evolution of wireless networks from the first to the second to the third generation of wireless systems. However, with all the recent advancement and development in the wireless industry, the basic design of wireless communication networks has remain unchanged.

Present wireless systems still rely on the same structure of central management operated by an administrator or an operator. One of the main challenges for future wireless systems is the support of independent mobile users. This type of wireless communication is not possible within the existing framework of wireless networks. This is one of the main reasons why mobile ad-hoc or peer-to-peer networks are growing research topics in the wireless research community.

The concept of the wireless ad-hoc or packet radio network goes back to the 1970's, when packet switching had proven itself. Effort was made to switch packets in mobile devices, mainly in use by different army units. Later on, a packet radio funded program was launched by the Defense Advanced Research Projects Agency.

The main objective of this program was to provide a bandwidth-sharing mechanism for operation in a dynamic environment. The program was successful in transmitting data over a multi-hop mobile network by using broadcast radios. This old frame of ad-hoc networks was modified in the 1980's with the emergence of second-generation ad-hoc networks. One of the main achievements during that time was the invention of low cost power radios to support sophisticated packet radio protocols.

Ad-hoc networking introduces a completely new flavor of network formation. In the mid-nineties, interest in mobile ad-hoc networks had started growing due to the availability of license-free wireless communication devices that mobile users can use to communicate with each other. The concept has been successful in delivering technologies like Bluetooth and mobile ad-hoc sensors.

These recent inventions have brought a dramatic change in wireless communication technology. Developers are looking into the possibility of extending the existing model of ad-hoc networks to support mobile users anywhere and at any time.

The term ad-hoc means, in this instance, a type instantaneous network connecting various mobile devices without the intervention of fixed infrastructure. The routers and hosts are free to move randomly and organize themselves in an arbitrary fashion; thus the network topology changes rapidly and unpredictably. Absence of a supporting structure in mobile ad-hoc networks, to a certain extent, invalidates almost all of the existing techniques developed for routine network controls in the existing wireless networks.