TABLE OF CONTENTS A Cognitive Radio is a Software Radio (SWR) or Software-Defined Radio (SDR) with flexible formal semantics based entity to entity formal messaging via RXML and integrated machine learning of the self, the user, the environment, and the situation. This section reviews SWR, SDR, and the Software Communications Architecture (SCA) or Software Radio Architecture (SRA) for those who may be unfamiliar with these concepts. While it is not necessary for an iCR to use the SCA/SRA as its internal model of itself, it certainly must have some model, or it will be incapable of reasoning about its own internal structure and adapting or modifying its radio functionality.
Hardware-defined radios such as the typical AM/FM broadcast receiver convert radio to audio using radio hardware, such as antennas, filters, analog de-modulators, and the like. SWR is the ideal radio in which the Analog to Digital Converter (ADC) and Digital to Analog Converter (DAC) convert digital signals to and from radio frequencies (RF) directly, and all RF channel modulation, demodulation, frequency translation and filtering are accomplished digitally. For example, modulation may be accomplished digitally by multiplying sine and cosine components of a digitally sampled audio signal (called the baseband signal, e.g. to be transmitted) by the sampled digital values of a higher frequency sine wave to up-convert it, ultimately to RF.
Figure 3.10 shows how SDR principles apply to a cellular radio base station. In the ideal SWR,...
