Introduction to flexible cognitive wireless link

This chapter presents some algorithms and technology that are used in the Physical (PHY) layer entity of a flexible or cognitive radio. In the context of this chapter, cognitive radio refers to a wireless air interface that implements the cognitive cycle introduced by Mitola in his Ph.D. thesis [20]. This cycle is illustrated on Figure 25.1 and is composed of four main steps: the “Sense” acquires relevant information from the radio environment, the “Analyse” and “Decide” steps represent all that implies some intelligence, “Analyse” for interpreting the observation of the “Sense” step, “Decide” for learning, planning, and decision making, and finally the “Act” step reconfigures the transceiver’s communication parameters, with the transceivers designed with software defined radio (SDR) principles in order to be as flexible as possible.

Mitola underlines the strong need for defining a novel wireless air interface (i.e., Media Access Control MAC and PHY layers) based on cognitive radio. This air interface should support the new functionalities described in Figure 25.1; the MAC layer (or the cognitive manager) operating the “Analyse” and “Decide” steps and the PHY layer operating the “Sense” and “Act” steps.