cognitive radio (CR)
Cognitive Radio(CR) is an approach to spectrum economics. It is a concept for the optimal use of unused, irregularly used, little or unoccupied frequency ranges, such as white spaces. Cognitive Radio aims to ensure that the available frequency bands are occupied more intelligently, flexibly and economically.
Optimal use of frequency bands
Since the available frequency spectrum cannot be increased, but the demand and need for additional frequency bands continues to grow unabated, research is being conducted into radio technologies that activate unused frequency bands as a spectrum resource. Cognitive Radio (CR) is such a flexible, intelligent mobile radio concept that searches for unused frequency bands in existing frequency bands and uses them as a frequency resource. The basic concept for Cognitive Radio was developed by Joseph Mitola of DARPA, which is why CR radio is sometimes referred to as Mitola radio.
Provision of frequency bands
Generally speaking, the available frequency bands are reserved exclusively for broadcast and radio services. There are the broadcast bands, the frequency bands for television, mobile radio, radar, directional radio, government radio, etc. To avoid interference, there are often safety frequency bands between the frequency bands and frequency channels. These unused frequency bands are also included in the considerations for optimal frequency utilization, as are frequencies that are not or rarely used.
Cognitive radio is an intelligent concept that adapts its operating parameters in real time to current frequency occupancy and environmental conditions. This adaptability concerns the carrier frequency, the transmit power and the modulation method. For this purpose, Cognitive Radio detects the radio-occupied and free frequencies in the UHF range. This is the frequency range that is approved for this application in the USA. Configuration and reconfiguration are handled by a Software Defined Radio( SDR), which forms the hardware platform. The readjustment mechanism itself continuously adapts its parameters to changing transmission conditions by constantly monitoring the frequency range.
One application area for Cognitive Radio is Cognitive Radio Networks( CRN), in which Cognitive Radios, which are cognitive radios, act as autonomous network nodes or cellular stations and increase the efficiency of spectrum economics. To do this, the node scans the spectrum, analyzes the free frequencies for its application, and aligns transmission parameters to avoid interference with licensed and unlicensed users. Thanks to the high mobility, a fast frequency change to another free frequency can be carried out.