FFT and filter bank based spectrum sensing and spectrum utilization for cogntive radios

Wireless Local Area Networks (WLAN) such as the OFDM based 802.11g system is designed to operate in 2.4 GHz ISM band. IEEE 802.11 devices are used at the same frequency band with various other applications, which causes interference between different users and leads to significant performance degradation. Hence, Cognitive Radio (CR) technology has been considered for coordinating the spectrum usage in a better way in this band. Spectrum sensing is one of the most important functions in a CR. In this study, filter bank based wideband spectrum sensing techniques are applied for detecting WLAN signals and spectral holes. Also filter bank based multicarrier techniques, together with a water-filling based subcarrier loading algorithm, are considered for effective exploitation of the detected holes. Clear benefit is demonstrated for using spectrally well-contained subband processing instead of basic FFT approaches.