Abstract

Abstract — The selection and design of performance metrics and utility functions is an important, but inadequately addressed issue in the design of cognitive radio networks. Unlike traditional radios, a cognitive radio may change its objectives as radio scenarios vary. Because of the dynamic pairing of objectives and contexts, it is imperative for cognitive radio network designers to have a firm understanding of the inter-relationships between goals, performance metrics, utility functions, link/network per-formance, and operating environments. In this paper, we first overview the hierarchical metrics for evaluating the performance of cognitive radios from the node, network, and application levels. From a game-theoretic viewpoint, we then show that the performance evaluation of cognitive radio networks exhibits the interdependent nature of actions, goals, decisions, observations, and context. We discuss the inter-relationships between met-rics, utility functions, cognitive engine algorithms and achieved performance. Various testing scenarios need to be employed to comprehensively evaluate the cognitive functionality of cognitive radios. We propose the radio environment map-based scenario-driven testing (REM-SDT) for thorough performance evaluation of cognitive radios. An IEEE 802.22 WRAN cognitive engine testbed is presented to provide further insights into this important problem area. Index Terms — Cognitive radio, cognitive wireless network, game theory, performance evaluation, performance metric, utility function. I.