Improved factorization for sample rate conversion in software defined radios

A modified architecture for rational sample rate conversion, in the digital IF stage of multi-standard wireless transceivers, has been developed. An iterative factorization method is introduced that assigns decimation (interpolation) ratios to multi-rate filtering stages performing arbitrary sample rate changes in this architecture. The factorization algorithm operates on standard-specific parameters to generate new rate-change factors such that the hardware resource sharing is maximized. A computationally efficient sample rate conversion structure comprising of Cascaded Integrator Comb filters and Farrow Interpolator has been derived and shown to outperform existing solutions. The proposed factorization method and ensuing architecture has been tested through simulations on GSM, IS-95 and UMTS wireless communication standards.