Reconfigurable Filter Banks for Software Defined Radio Receivers – An Alternative Low Complexity Design to Conventional DFT Filter Banks

A new approach to implement computationally efficient reconfigurable filter banks for software defined radio receivers is presented in this paper. If the coefficients of a finite impulse response (FIR) filter are decimated by M, i.e., if every M-th coefficient of the filter is kept unchanged and remaining coefficients are replaced by zeros, a multi-band frequency response will be obtained. The frequency response of the decimated filter will have bands at centre frequencies at 2πk/M, where k is an integer ranging from 0 to M-1. If these multi-band frequency responses are subtracted from each other or selectively masked using inherently low complex wide transition-band masking filters, we can obtain different low-pass, high-pass, bandpass, and bandstop frequency bands. The resulting filter bank, whose bands’ centre frequencies are located at integer multiples of 2π/M, is a low complexity alternative to the well known uniform Discrete Fourier Transform (DFT) filter banks. We also show that the proposed filter bank is more flexible and easily reconfigurable than the DFT filter bank. Furthermore, the proposed filter bank is able to receive channels of multiple standards simultaneously, where as separate filter banks would be required for simultaneous reception of multi-standard channels in a DFT filter bank based receiver.