Communication engineers are envisioning a wireless device that is smart enough to analyze the radio environment and decide for itself the best spectral band and protocol to reach whatever base station it needs to communicate with, at the lowest level of power consumption. Such a concept is named cognitive radio. Such a concept will have to first pass to software-defined radio which can easily switch among multiple wireless protocols or move to different frequencies, waveforms, protocols or applications. Cognitive radio not only senses the spectrum and determine how best to interface with one another, they also decide which radio network is best to use. A software-defined radio uses an analog-to-digital converter capable of capturing waveforms from a much wider range of spectrum. Such radios will figure out which bands are underused, rendezvous with one another there and start communicating. However, the challenge of true software-defined cellular systems includes processing signals at high frequencies and the task of finding which frequencies two radios will end up with in order to communicate and in addition taking into account registered frequencies to avoid interruption.
