n the network that has access to the system. This Application (Auto-Generated) aspect of the deployment of the waveforms allows the concept of a CR within the SCA to easily extend to a cognitive network, where a single cognitive engine can control multiple flexible radios, as seen in Figure 2.4a-21. Assembly With SDR and an astute selection of processing and Controller RF hardware on the part of a developer, it is possible to create highly sophisticated systems that can operate well at a variety of scales, from simple single-chip mobile devices all the way up to multitiered cognitive networks. Cognitive Engine 2.4a.8 Summary Figure 2.4a-19 Cognitive engine waveform. The waveform per- forms only cognitive functionality. It assumes communications Although an SDR is not a necessary building block of functionality is performed by other waveforms. a CR, the use of SDR in CR can provide significant capabilities to the final system. An SDR implementation a different structure altogether) from the Applica- is a system decision, in which the selection of both tionFactory. This structure is seen in Figure 2.4a-20. the underlying hardware composition and the software An aspect of Figure 2.4a-20 that is apparent is that the architecture are critical design aspects. Port structure evident at the waveform level, as seen in The selection of hardware composition for an SDR Figure 2.4a-19, scales up to interwaveform communica- implementation requires an evaluation of a variety of tions. Another aspect of this approach is that the cogni- tive waveform does not have to be collocated with the communications waveform. As long as timing constraints are met, the cognitive waveform can be placed anywhere Flexible Cognitive Radio Waveform ApplicationFactory Network Cognitive Communications Flexible Waveform Waveform Radio Flexible Radio Figure 2.4a-20 Multi-waveform cognitive support. The stand-alone cognitive waveform requests new waveforms from Figure 2.4a-21 SCA-enabled cognitive network composed of the SCA ApplicationFactory. multipl