In this thesis, the problem of spectrum sensing in cognitive radio communication networks is considered. This thesis has developed a robust decision fusion scheme that can perform well when the interference caused by other PUs is present. Specifically, the proposed detection scheme is based on fusing the local decisions from energy detectors (EDs) and cyclostationarity- based detectors (CDs). Our proposed fusion scheme is different from other power spectrum sensing technology being developed so far in that other fusion technology are based on fusing the local decisions from the same type of detectors. Our proposed fusion scheme can take the advantage of both EDs and CDs. We compare the proposed scheme with the schemes fusing the same type of detectors, and the results confirm that the proposed scheme is more robust against the possible interference.

Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Nuclear Engineering, 1989. / "DOE/ET-51013-271." / Includes bibliographical references. / Supported by the U.S. Department of Energy. DE-ACO2-78ET51013 / Clinton Craig Petty. / Ph.D.

The National Network of Fusion Centers (Network) represents one of the post-9/11 era organizational efforts to strengthen the security of the homeland through collaboration, analysis, and information sharing. These entities have been subjected to criticisms and have been noted in studies as being deficient in certain areas suggesting that the Network has been experiencing problems with integrating the U.S. national security strategy. Using the multiple streams framework, the purpose of this phenomenological study was to identify and understand elements that have been impacting the Network's integration with broader national security efforts as well as identify items contributing to negative perceptions of fusion centers. Data for this qualitative study were collected through interviews with 13 individuals working within the Network. Collected data elements were inductively coded and then analyzed, demonstrating the relevance of framework to this topic area. Research findings indicated that there were challenges with Network integration that were influenced by perceptions of problems/threats, views concerning a fusion center's primary stakeholder, and constraints related to existing organizational policy and mandates. Barriers to integration stemmed from differing priorities, ineffective marketing, policy requirements, relationships, and limited resources. Study recommendations included the development of a strategic engagement plan, alignment of priorities, and increases in federal funding and representation. The implications for positive social change of this study are associated with proving transparency on the Network, informing national security agencies and decision makers on issues impacting integration, and promoting operational efficiencies.

Organized cybercrime has no borders in cyberspace. This paper suggests a state-of-the-art architected solution for a global Automated cross-border mutual legal assistance system within Digital Forensic (AUTOMLA). The Enterprise framework with technical viewpoint enables international collaboration between sovereign countries Fusion Centers. The evaluation concludes a user interface built in React, middleware Apollo with schema support linked to graph database Neo4j. GraphQL is the preferred application protocol over REST. Fusion Centers API is deployed as federated gateways, and business functions are implemented as PaaS serverless services.  Its intuitive modeling Forensics in graphs, semantic networks enables causality and inference. All suggested elements in AUTOMLA are forming an internationally agreed collaborative platform; the solution for fast cross-border crime investigations. AUTOMLA deployed on the Internet is a subject for threats. Risks are mitigated in design guided by security frameworks. The recommended development method is agile, distributed in between autonomous teams.

The September 11 terrorist attacks pointed out the lack of information sharing between law enforcement agencies as a potential threat to sound law enforcement in the United States. Therefore, many law enforcement agencies as well as the federal government have been initiating information sharing systems among law enforcement agencies to eradicate the information sharing problem. One of the systems established by Homeland Security is the North Central Texas Fusion Center (NCTFC). This study evaluates the NCTFC by utilizing user acceptance methodology. The unified theory of acceptance and the use of technology is used as a theoretical framework for this study. Within the study, user acceptance literature is examined and various models and theories are discussed. Furthermore, a brief information regarding the intelligence work done by law enforcement agencies are explained. In addition to the NCTFC, several major law enforcement information systems are introduced. The data for this study comes from the users of the NCTFC across the north central Texas region. Surveys and interviews are used to triangulate data. It is found in this study that performance expectancy and effort expectancy are important indicators of system use. Furthermore, outreach and needs assessment are important factors in establishing systems. The results of the study offer valuable input for NCTFC administrators, law enforcement officials, and future researchers.