Improvements to Enhance The Security and Reliability of Crowdsourced Spectrum Access Systems and Cognitive Radio Networks

This dissertation addresses key challenges in dynamic spectrum sharing within Cognitive Radio Networks (CRNs) and Spectrum Access Systems (SASs), focusing on the U.S. 3.5 GHz Citizens Broadband Radio Service (CBRS) band. A structured survey of existing regulatory frameworks, coordination methods, and interference mitigation strategies provides context for the research contributions that follow. To enhance trust in user-reported data, the Whisper Key Location Verification method is introduced. It validates the physical location of crowdsourced nodes by combining radio and internet-based checks, filtering out falsified reports and improving Primary User (PU) protection. The Enhanced Heartbeat Protocol (EHP) enhances SAS–Secondary User (SU) communication through asynchronous messaging and an expanded message format, enabling faster spectrum reassignments and supporting mobile scenarios, such as UAV networks. To detect Spectrum Sensing Data Falsification (SSDF) attacks, a real-time framework using lightweight similarity metrics identifies duplicated or manipulated sensing data, increasing system resilience. Finally, the Radio Frequency Obstructed Observation Area Identification (RF-OOAI) method distinguishes environmental signal loss from intentional misreporting, preserving the reputation of honest users. These contributions collectively improve the accuracy, efficiency, and robustness of shared spectrum systems, advancing the design and reliability of CRNs and SASs in complex real-world settings.