Orthogonalization of OFDM/OQAM pulse shaping filters using the discrete Zak transform

We introduce a computationally efficient FFT-based algorithm for the design of OFDM/ OQAM pulse shaping filters of arbitrary length and with arbitrary overlapping factors. The basic idea of our approach is to start from an arbitrary initial (nonorthogonal) filter and to perform an orthogonalization which yields an ISIand ICI-free pulse shaping filter. The orthogonalization is performed in the discrete Zak transform domain and can be implemented using the FFT. We design filters for OFDM/OQAM systems with up to 1024 channels and overlapping factor 32. Finally, we present simulation examples assessing the performance of the designed pulse shaping filters in the presence of Doppler spread.