Antenna functionalities in a cognitive radio environment

Summary form only given. It is well known that a cognitive radio is based on software defined radio with cognition ability. For a cognitive radio device to function properly, it should follow a closed loop cycle. This cycle is based on (1) observing the channel activity, (2) deciding which part of the spectrum is suitable for communication, (3) acting appropriately to achieve the required mode of communication, and (4) learning from previous channel activity. A cognitive radio device operates in either “interweave” or “underlay” mode. In both types of operation, the unoccupied parts of the spectrum also called “white spaces” are always inspected. The primary and secondary users, once identified, are allocated dynamically to the different parts of the spectrum.