Introduction

Nowadays, there are many routing protocols available for mobile ad-hoc networks. They mainly use instantaneous parameters rather than the predicted parameters to perform the routing functions. They are not aware of the parameter history. For example, AODV, DSDV, and DSR use the hop counts as the metric to construct the network topology. The value of hop counts is measured by the route control packets. Current physical topology is used to construct the network topology. If the future physical topology is predicted, a better network topology might be constructed by avoiding the potential link failure or finding a data path with high transmission data rate.

Most traditional routing protocols do not consider the channel conditions and link load. In this case, it is assumed that the channel conditions for all links are the same and the load levels for all links are the same. Unlike the wired networks, the channel conditions and the link load in a wireless network tend to vary significantly because of the node mobility or environment changes. Therefore, the nodes in a wireless network should be able to differentiate the links with different channel conditions or load levels to have a general view of the network. In this way, the routing functions can be better performed. Further, the network performance might be increased.

In recent years, cognitive techniques are increasingly common in wireless networks. Most research focuses on the solutions that modify the PHY layer and MAC layer.