 regula- language. Tool sets are available for building policy tory authority. definitions and for machine interpretation of the defini- tions [34]. 4. The spectrum access privileges of the radio may change in response to a change in radio user. Al Techniques As a result, the number of different policy sets that apply to various modes and environments grows in a combinatorial The field of AI has received a great deal of attention for fashion. It is impractical to hard-code discrete policy sets decades. In 1950, Alan Turing proposed the Turing test, toradios to cover every case of interest. The accreditation regarding interacting with an entity and not being able to of each discrete policy set is a major challenge. SDRs, for tell if it is human or machine. The AI techniques that work example, would require the maintenance of downloadable are plentiful, but most are not widely applicable to a wide copies of software implementations of each policy set for range of problems. The powerful techniques may even every radio platform of interest. This is a configuration require customization to work on a particular problem. management problem. An agent is an entity that perceives and acts. A smart A scalable expression and enforcement of policy is agent model is appropriate for CR. Figure 2.4b-4 explains required. The complexity of policy conformance ac- four models of smart agents-simple reflex agents, creditation for CRs and the desire for dynamic policy model-based reflex agents, goal-based agents, and utility- lead to the conclusion that CRs must be able to read and based agents-defined as follows: interpret policy. Therefore, a well-defined, accepted 1. A simple reflex agent is a simple mapping from (meaning endorsed by an international standards body) current sensor inputs to actuator settings. This is CHAPTER 2.4b Cognitive radio: The technologies required Simple Reflex Agent Reflex Agent with State Agent selects its action as a function of the aka Model-Based Reflex Agents current percept Agent maintains internal s