The Improving Design of Near Perfect Reconstruction Cosine Modulated Filter Banks for Wideband Reception

In this article, a kind of near perfect reconstruction cosine modulated filter banks which could be used to receive wideband signal is raised. First, the design of filter banks is transformed to the design of prototype filter. Cost function is used to make passband stable and stopband attenuation. Considering the problem of amplitude distortion among existing algorithms, this article adopts cost function to make transition band has square root cosine roll-off. In order to avoid the error brought by the strengthened objective function’s constraint, cut-off frequency of passband is adjusted to ensure that the cut-off frequency of prototype filter’s 3dB passband is equal to that of ideal filter. In this article, close form solution expression of a cost function whose variable is filter factor is derived as well. To solve the problem of the high complexity of filter, a way based on iteration to solve prototype filter is adopted. The result of the simulation shows that modulated filter banks derived in this way perform better than those designed by existing method.