Digital Signal Processing Reference
In-Depth Information
Fig. 1.4
The Cognitive Radio is an adaptive feedback-based layer to control the increasing flexi-
bility, of which prime examples are the SDR (at the hardware side) and OR (at the spectrum side)
For instance, IEEE 802.22 was marketed as the first CR standard, while it actu-
ally carries few of the key elements present of the CR as defined by Mitola or
Haykin.
Mitola and Haykin actually saw the CR as an answer to the following questions:
•
“What can we do with the increasing HW flexibility provided by the SDR?” (Mi-
tola, 1999).
•
“What can we do with the increasing policy flexibility provided by regulators?”
(Haykin, 2004).
The common denominator of these two visions is to define a CR as an
intelligent
control framework to handle the increased flexibility
.
To avoid ambiguity, throughout this topic, the spectrum-oriented view on CR
(OSA) is denoted as Opportunistic Radio (OR). CR denotes an adaptive feedback-
based layer to control the increasing flexibility, of which prime examples are the
SDR (at the hardware side) and OR (at the spectrum side). This can be seen in
Fig.
1.4
. An adaptive radio that exploits flexibility to improve on QoS or energy cost,
but does not learn the optimal configuration based on feedback, will be denoted as
a smart radio.
