FPGA implementation of a multimodal sample rate converter and synchronizer

This paper deals with the implementation of the sample rate conversion subsystems of the digital front-end, at intermediate frequency (IF), and of a synchronization subsystem in the framework of a software radio receiving terminal. A perviously proposed architecture is adopted and optimized for the realization of a multimodal terminal, the main operational mode of which is UMTS, but also capable to interface with GSM or IS-95. In particular, a class of multiplierless filters in conjunction with reduced complexity FIR filters is chosen for the rate conversion. The selected approach for synchronization is a modified MAX/TC algorithm that exploits dedicated sync channels, for the UMTS case. Its performance in terms of acquisition probability has been studied either in a classic AWGN channel or in a multipath environment. The algorithms have been optimized considering an FPGA based implementation, where power consumption and occupied area strongly constrain designer choices.