Online Expert-Based Prediction for Cognitive Radio Secondary Markets

Cognitive Radio System for Dynamic Allocation of Uhf Band Channels Based on 802.11AF and Using the Energy Detection Algorithm

“…• Spectrum monitoring In this phase, SU or cognitive users carry out monitoring activities on the spectrum channels to be used, in order to detect the presence or absence of PU activity and thus determining free channels and allocating them for transmission [37].…”

“…• Spectrum management It consists of selecting the most appropriate channel for communication from among all available channels. It refers to the technique selection to use spectrum more efficient, always keeping in mind PU have priority to use channels and establish communication in their own frequencies [37]. Initially, cognitive networks only focused on allocation and use of frequencies during the time slots were unused by PU, identified by spectrum monitoring.…”

“…It is necessary to explain certain concepts about the transmission channel in order to better understand spectrum sharing techniques. Basically, techniques mentioned above consider the channel as the minimum unit of spectrum necessary for operation and expect all channels to provide the same characteristics, therefore, same capacity [37]. Channel features to be consider are: power, frequency, time, directionality, polarity, coding and modulation.…”

“…On the other hand, when making a spectrum decision, it is necessary to select the pertinent operating parameters for transmission based on channel characteristics and the quality of service (QoS) demanded by the users [37].…”

“…The last phase of the cognitive cycle is responsible for changing features and transmission parameters when a PU starts using of the spectrum portion that was being used by a SU. This action implies SU migrates to another free frequency band, preserving communication [37].…”