| Summary: | 碩士 === 國立交通大學 === 電信工程研究所 === 99 === Spectrum sensing in next-generation wireless cognitive systems, such as overlay femtocell net-works, performed at secondary users is indispensable. In a random access ad hoc network, the performance of spectrum sensing is further limited by interference. Thus, in the thesis we first investigate the performances of two interference-resistant detection schemes, namely, the oblique-projection based detector and matched-subspace detector, assuming that the interference subspace is complex-valued. The exact formulas for the detection and false-alarm probabilities are derived and corroborated via numerical simulations. In addition, we propose a minimal-output-power (MOP) based detection scheme. The performances of the three detectors are discussed. We also propose an MOP based detector with unstructured interference subspace. Computer simulation confirms the effectiveness of MOP based detector when compared with the traditional ED.
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