The existing routing solutions can broadly be classified into two main types: tables driven and on demand routing solutions. Tables driven protocols are considered to be some of the earlier efforts in proposing a separate routing solution for mobile ad-hoc networks. These protocols require all the mobile hosts to be continuously awake by sending topology updates to all other nodes at a regular intervals. That's how they maintain a consistent overview of the entire network. Therefore, whenever a node is required to send information to other nodes, it drives the route information from the routing table and transfers this information to the destination node. The procedure is straight forward, especially in an environment which is highly dynamic. By highly dynamic, we mean nodes change their locations or topology continuously. There is very little doubt about the poor performance of these protocols not as a whole but in terms of power consumption. In my opinion, this approach cannot be regarded as a power aware routing technique.

On-demand protocols establish a routing path only when a transmission is required. In other words, if node A wants to transmit some information for node B, node A initiates a route discovery procedure. Once the route is found, data is transferred from A to B. Clearly, this approach is good, especially in terms of power saving. Moreover, some of these protocols allow nodes to go into sleep mode while they are not in an active transmission.

In summary, power aware routing is an essential aspect in developing efficient routing techniques for mobile ad-hoc network. These types of techniques are required as most of the participating devices generally operate on low battery power. There is much effort has been done to deliver a routing solution which can not only route packet between two hosts in a mobile ad-hoc network but also consume less power. However there is still lot to do before these solutions could be implemented in a real environment, thereafter, can be use to deliver successful future ad-hoc network products.

Dr. Humayun Bakht completed his Ph.D at the School of Computing and Mathematics in Liverpool at John Moores University. Prior to his current course of studies, he has successfully completed his MSc Software Engineering and BSc Electronics Engineering from University of Liverpool UK and Sir Syed University of Engineering and Technology in Karachi, Pakistan. Humayun's research interest is mobile ad-hoc networks, in particular, the development of a new routing algorithm for this type of networking. He can be reached at humayunbakht@yahoo.co.uk and you can visit his Web site at http://www.geocities.com/humayunbakht/.