20.2 Cognitive Radio Architectures 589 radio architectures. To help guide this evolution, QoI is characterized along its sev- eral dimensions in Section 20.5, while Section 20.6 introduces the contributions of cognitive linguistics to policy language evolution and Section 20.7 offers a review of challenges and opportunities before the conclusion in Section 20.8. 20.2 COGNITIVE RADIO ARCHITECTURES Radio architecture is a framework by which evolving families of components may be integrated into an evolving sequence of designs that synthesize specified functions within specified constraints (design rules) [688]. A powerful architecture facilitates rapid, cost-effective product and service evolution. An open architecture is available to the public, while a proprietary architecture is the private intellectual property of an organization, government entity, or nonpublic consortium. Figure 20.1 illus- trates functional components integrated to create an SDR device, which may be wearable, mobile, or a radio access point (RAP) in a larger network. The set of infor- mation sources includes speech, text, Internet access, and multimedia content. Today's commercial radio frequency (RF) channel sets typically have four chipsets (GSM 900, GSM1800, CDMA, and Bluetooth, for example), evolving in the near