| dc.description.abstract | In this thesis, we emphasize on three main topics of concurrent multiple jammer/interceptors evaluations for spread spectrum communication systems, investigations of effective FOJ probability model, and its adaptation to cognitive radio communications, which seem to be different but, in fact, closely related. Before stepping into these main topics, the research motivation, purpose, and previous work survey will be stated first, then some fundamental backgrounds for this thesis, e.g., TRANSEC concept, spread spectrum fundamentals, basic propagation effects model, antenna patterns model, adopted scenarios for analysis and simulations, and etc. will be followed. Hereafter, two countermeasures issues will be examined, which include the countermeasures to jam both DS and FH communication signals and the countermeasures to cover, detect, intercept, or even exploit both DS and FH signals. The three main topics are stated as follows.
The first main topic is the AJ and LPD/I/E evaluations for concurrent single and multiple jammer/interceptors via schemes and metrics available. We develop a systematic method for evaluation of a secure communication system with simultaneous AJ and LPD/I/E capabilities by coordinating with many system-dependent and geometric-dependent parameters. For a typical communications system with FHMA and BFSK modulation, single and multiple concurrent jammer/interceptors are examined based on the proposed operation scenarios for security evaluations and trade-offs.
The second main topic is the analysis of an interesting FOJ model with two different geometric observation models with elliptic and hyperbolic contours, respectively, and both uniform and sequential scanning schemes, to develop an approach for evaluating the FOJ effective probability. A FOJ model with both real-time scanning (detection) and transmission (jamming) capabilities is examined to verify the FH spread spectrum performance of transmission security by estimating effective jamming probability (h).
The last main topic is the adaptation to cognitive radio communication by replacing the collocated jammers/interceptors with “cooperative” cognitive radio units (CRUs), which would be an effective and novel model for evaluating the real time communication resources through cognitive probability ratio (CPR). Fundamental direction finding (DF) and emitter location (EL) techniques are incorporated with proposed cognitive radio unit (CRU) and models for more accurate propagation delay prediction and estimation. The proposed CRU model and CPR is innovative for cognitive radio network evaluations. | en_US |