Chapter 1Introduction to Cognitive Radio1
1.1. Joseph Mitola's cognitive radio
In 1995, Joseph Mitola introduced the new concept of software radio (SR) [MIT 95]. Soon after, during his thesis [MIT 00a], he became interested in the efficient use of the spectrum. He noticed that the spectrum was very inefficiently used and a large part of it was underutilized. He concluded that by locally managing the spectrum intelligently, its use could be significantly increased. Mitola realized the need to put intelligence simultaneously into both the network and the equipment, to satisfy both the user needs and resource constraints, ultimately resulting in an increase in spectral efficiency. This is why he proposed the idea of cognitive radio (CR) [MIT 99a]. He demonstrated that CR would be more efficient if combined with SR technology.
Let us illustrate the CR approach by drawing a simple analogy between radio systems carrying information and land transportation of goods. The railroad is a physical link between two stations. The train on which the goods are to be carried must follow the track and it cannot choose other “routes and/or timings”. The analogy then is that a conventional radio communication link on the global system for mobile communication (GSM) standard has no other options but to follow the track (given frequency and modulation) to ensure that the information reaches the receiver. When the same goods are transported by the road network, a whole infrastructure joining the ...