Difficulties in providing certification and assurance for software defined radios

Certification and assurance processes have historically exhibited difficulties when there exists the potential for significant non-functional attributes. We define a non-functional attribute as a condition where the cause-effect behavior cannot readily be specified. Complex systems commonly exhibit such non-functional attributes due to the exceedingly large potential state space. In such systems, analysis based on formal methods becomes very difficult and emergent behaviors (or malicious behaviors that exploit non-functional attributes) can lead to a variety of unintended consequences - some benign and others harmful. Simply put, it is difficult to assure the behavior of a complex system. The shift towards highly flexible and adaptive software defined radios creates a potential complex system problem, and thereby exposes certain assurance and certification challenges for the present regulatory processes. We use certification experiences from the security community to motivate and highlight potential difficulties that may arise within the Software Defined Radio (SDR) space. We then recommend some steps that limit or account for these difficulties.