First of all let’s give a definition of what a Mobile Ad Hoc Network is. It is a collection of mobile nodes, such devices as PDAs, mobile phones, laptops etc., that are connected over a wireless medium. There 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 from the point of view of research and application. There are several classes of such networks. Below you can find three the most largest of them.

• 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. They should be the networks of the 4-th generation (4G). But I should say that there are still no services or software solutions for the ad hoc networks so far. All the efforts of the science are concentrated on the research of the routing that is a great challenge at the moment. The other problem is that there are no suitabe divices on the markt. So all the research results that were made so far are mostly of the theoretic nature and base on simulation. So I guess that it will take two or three years till the first serious software solutions for the ad hoc networks will be ready to appear on the markt.

Another point is the politics of the markt. Do you still know how expensive were the licenses for UMTS? It will take several years yet till the mobile providers get their money back and be able to look for new technologies. In the near futre there will appear a set of online services for mobile phones based on geo informations. Maybe there appears something else, but the fact is that the place for the ad hoc network will appear on the markt not that soon. In any case I’m persuade that mobile ad hoc networks are our future and much interesting things will happen in this sector.

Next time I’m going to tell a little bit about routing, classification of routing protocols and the main problems connecting with routing.

July 8th, 2007 at 6:41 pm | category: Ad Hoc Networks