Abstract
From a physical standpoint, the distinguishing feature of a cognitive radio (CR) is the spectrum sensing unit (SSU). The SSU must be designed in such a way that it can scan the entire frequency spectrum and locate unused channels. The location of unused channels is not a trivial task for two main reasons. First, the frequency spectrum band may be large and hence sensing the entire spectrum may be impractically time consuming. Second, the detection of weak signals must be distinguished from noise generated by an unlicensed interferer. The second point indicates that a simple energy metric is not sufficient. In this chapter, sensing requirements for CR are listed. This is followed by a set of techniques that can enhance the performance of the SSU.
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Summary
In this chapter, spectrum sensing techniques and implementations have been presented. The main challenge of spectrum sensing lies in the very low SNR detection levels that are required in order to prevent collision with a weak transmitter that is outside the reception range of the cognitive user, but not that of the primary receiver. Different spectrum sensing techniques have been reviewed. The sensitivity of energy-based detection has been found to be insufficient and must be supplemented with other techniques. Lastly, cooperative spectrum sensing techniques have been explored as a method of improving the performance and energy efficiency of the spectrum sensors.
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Fahim, A. (2015). Wideband Spectrum Sensing Techniques. In: Radio Frequency Integrated Circuit Design for Cognitive Radio Systems. Springer, Cham. https://doi.org/10.1007/978-3-319-11011-0_4
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DOI: https://doi.org/10.1007/978-3-319-11011-0_4
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