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In this paper, we introduce a joint channel and noise variance estimation, and primary user (PU) signal detection scheme using the expectation-maximization (EM) algorithm for cognitive radios. In our investigation, we consider two scenarios: In the first scenario, the channel and noise variance are assumed to be perfectly known by the secondary user (SU).(More)
—Spectrum sensing is an important functionality of cognitive radio as a means to detect the presence or absence of an existing user (EU), including the primary user or other secondary users, in a certain spectrum band. Energy detector (ED) is a widely used spectrum sensing technique based on the assumption that the EU is either present or absent during the(More)
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