Abstract: Cognitive radios by dynamically detecting available channels and changing their transmission or reception parameters allow increased concurrent wireless communications within a given spectrum band. It would be beneficial for such cognitive radios to exploit orthogonal frequency division multiplexing (OFDM) and accordingly establishing a spectrum monitoring technique suitable for OFDM-based cognitive radios an essential element for this. The inventors have established a technique allowing for the detection of the reappearance of the primary user within a reception period within an OFDM-based cognitive radio network and beneficially does so quickly without requiring received bit decoding and allows for different signal chain impairments to be considered. Further, the technique is applicable to address other important OFDM challenges for cognitive radios such as power leakage as well as extending the embodiments of the invention to multiple antenna systems.

Abstract: Cognitive radios by dynamically detecting available channels and changing their transmission or reception parameters allow increased concurrent wireless communications within a given spectrum band. It would be beneficial for such cognitive radios to exploit orthogonal frequency division multiplexing (OFDM) and accordingly establishing a spectrum monitoring technique suitable for OFDM-based cognitive radios an essential element for this. The inventors have established a technique allowing for the detection of the reappearance of the primary user within a reception period within an OFDM-based cognitive radio network and beneficially does so quickly without requiring received bit decoding and allows for different signal chain impairments to be considered. Further, the technique is applicable to address other important OFDM challenges for cognitive radios such as power leakage as well as extending the embodiments of the invention to multiple antenna systems.