Since its introduction, SDR has been defined as a radio platform of which the functionality is at least partially controlled or implemented in software. Consequently, any waveform defined in the memory of the SDR platform can be employed on any frequency. Although initially constrained by the conversion process between the analog and digital signaling domains, the emergence of cheap high speed digital-to-analog converters (DACs) and analog-to-digital converters (ADCs) has brought the ideal SDR concept of an entirely software communication system implementation (including radio frequency functionality) closer to a reality.
Given the ease and speed of programming baseband operations in an SDR platform, this technology is considered to be a prime candidate for numerous advanced networking applications and architectures that were unrealizable only several years ago. An SDR platform that can rapidly reconfigure operating parameters based on changing requirements and conditions and through a process of cognition is known as cognitive radio.
CR technology is the “intersection of personal wireless technology and computational intelligence,” where CR is defined as “a really smart radio that would be self-aware, RF-aware, user-aware, and that would include language technology and machine vision along with a lot of high-fidelity knowledge of the radio environment”. Cognitive radio clearly goes hand in hand with SDR; together, they can achieve functionality considered impossible only a decade ago.
