Recent increases in demand for cognitive radio technology have driven researchers and technologists to rethink the implications of the traditional engineering designs and approaches to communications and networking. One issue is that the traditional thinking is that one should try to have more bandwidth, more resources, and more of everything, while we have come to the realization that the problem is not that we do not have enough bandwidth or resources. It is rather that the bandwidth/resource utilization rates in many cases are too low. For example, the TV bandwidth utilization nowadays in the USA is less than 6%, which is quite similar to that in most developed countries. So why continue wanting to obtain more new bandwidth when it is indeed a scarce commodity already? Why not just utilize the wasted resource in a more effective way?
Another reconsideration is that often one can find the optimization tools and solutions employed in engineering problems being too rigid, without offering much flexibility, adaptation, and learning. The super highway is a typical example in that, during traffic hours, one direction is completely jammed with bumper-to-bumper cars, while the other direction has few cars with mostly empty four-lane way. That is almost the case for networking as well. Rigid, inflexible protocols and strategies often leave wasted resources that could otherwise be efficiently utilized by others. It was recognized that traditional communication and networking paradigms have taken little or no situational information into consideration by offering cognitive processing, reasoning, learning, and adaptation. Along the same lines, such awareness also drives us to seek an optimization tool to better enhance cooperation and resolve conflict with learning capability.
In the past decade we have witnessed that the concept of cognitive networking and communications has offered a revolutionary perspective in the design of modern communication infrastructure. By cognitive communications and networking we mean that a communication system is composed of elements that can dynamically adapt themselves to the varying conditions, resources, environments, and users through interacting, learning, and reasoning to evolve and reach better operating points or a better set of system parameters to enhance cooperation and resolve conflict, if any. Those factors can include awareness of channel conditions, energy efficiency, bandwidth availability, locations, spectrum usage, and the connectivity of a network, to name just a few. Such design with awareness of situations, resources, environments, and users forms the core concept of the emerging field of cognitive communications and networking. Many new ideas have thus been inspired and have blossomed.