Adaptive threshold enhanced filter banks for wireless microphone detection in IEEE 802.22 WRAN

IEEE 802.22 is the first worldwide Wireless Regional Area Networks (WRAN) standard based on cognitive radios (CR). In IEEE 802.22 WRAN, if a wireless microphone appears in any TV channel, the whole channel should be cleaned. 802.22 WRAN devices probably need to fractionally use the first adjacent channel for improving spectrum efficiency while ensuring no harmful interference is caused to the wireless microphone nearby. To determine the appropriate portion of the TV channel that WRAN can utilize, we firstly need to know the frequency location of wireless microphone. In this paper, we propose a two step DFT filter bank (TS-DFTFB) enhanced with an adaptive threshold method to detect the wireless microphone (WM). Comparing with conventional single step DFTFB, the TS-DFTFB method has low complexity while the detection precision is equal to single step DFTFB under the same condition. And with an adaptive method, the threshold can be kept very close to the noise power, which can increase the detection probability especially in the condition of low SNR.