Radio Resource Allocation and Dynamic Spectrum Access

2

Cognitive Radio

2.1. Introduction

In this chapter, we consider the various aspects of cognitive radio (CR): principles, structure, functions and the different fields of application, etc.

Today, it is widely acknowledged that digital wireless communication systems do not use the entire available frequency band. Wireless systems of future generations will therefore be designed to capitalize on these unoccupied frequency bands because of their ability to respond and adapt to their environment.

The development of new technologies has always been dictated by current requirements and the availability of the technology. This is how we evolved from analog to digital radio and made subsequent progress, particularly in the quality, speed and reliability of transfer of information, and also in the network’s capacity.

Over the years, demand grew and new solutions appeared. This led to the idea of a software radio, which was purposed initially for military applications, but became progressively oriented toward the civilian domain. CR was the next step and the emergence of this concept is directly linked with the requirement to manage this new complex idea in terms of the radio terminal environment.

Certain bands and networks (GSM, Wi-Fi) are active and already overcrowded during peak times. However, the use of the spectrum is not consistent in terms of the hours in the day and the geographical location; one frequency band can be overcrowded while another is unused. This is why the idea of ...