Progressive decimation filter banks for variable resolution spectrum sensing in cognitive radios

Conventional uniform discrete Fourier transform filter bank (DFTFB) used in energy detection based spectrum sensors provides only fixed sensing resolution. In this paper, we propose a progressive decimation filter bank (PDFB) that can provide variable sensing resolution and adapt to different detection bandwidths for wideband spectrum sensing in cognitive radios. From an initial fixed-coefficient modal filter, a filter bank that has multiple passbands of different passband widths can be obtained using coefficient decimation. Changing the number of subbands in proposed method does not involve hardware reimplementation. Design examples show that the detection performance of proposed variable resolution PDFB is comparable to that of conventional fixed resolution DFTFB based spectrum sensor.