Phase-Only Filter Design with Application in OFDM Systems

Signal processing algorithms are widely used in wireless communication systems where it is used to process natural as well as man-made signals. Among these, filtering is one of such algorithm which is used to either enhance or suppress certain features in the regime of interest. The signal processing research community has not paid due attention to phase-only filtering, which is the focus of this paper. In this paper, we introduce a phase-only filter design formally and highlight its advantage over other conventional techniques through illustrative examples. We propose a novel method to design an optimal phase-only filter using the least squares approach. Additionally, we demonstrate the advantage of this design in an orthogonal frequency division multiplexing (OFDM) receiver for reducing the group delay distortion introduced by analog/digital baseband filters with sharp cut-off frequency responses. In contrast to the conventional methods such as equalization, the phase-only filter achieves this at a lower computational complexity. Monte Carlo simulation results are provided to substantiate the theory.