Simple iterative method for designing prototype filter for cosine modulated nearly perfect reconstructed transmultiplexer

In this paper, an efficient design method of nearly perfect reconstruction cosine modulated transmultiplexer (CM TMUX) is presented for the prescribed stopband attenuation (A_S), passband attenuation (A_P), and roll off factor (RF). The method employs the weighted constrained least squares (WCLS) technique for the design of a prototype filter for CM TMUX. Here, the cut-off frequency is iteratively varied so that the magnitude response of the prototype filter is optimized to 0.707 at ω=π/2M. The performance of the proposed algorithm is measured in terms of inter-channel interference (ICI), intersymbol interference (ISI) and signal to overall interference (SI) etc. Several examples are presented to illustrate the efficacy of the proposed method over other existing methods and found that ICI and ISI are reduced to satisfactory minimum values for the less interference operation of near perfect reconstruction (NPR) transmultiplexer system.