Design of Digital Up-Down Converter for LTE-RRH in Digital Radio System

This paper describes the evolution of Macro BTS to Distributed BTS and the most fundamental blocks of digital radio system which includes Digital Up and Down Converter for Long Term Evolution Remote Radio Head. A DUC forms part of the transmit path of digital radio front end signal process system and perform the function of filtering and up converting the baseband signal to a higher sampling rate. A DDC forms part of the receiver path of a digital radio frontend signal processing system, and it make possible to extract information of interest by decimating to a lower sampling rate. Remote Radio Head is the new technology which is employed in distributed BTS architecture. MATLAB tool is used for interfacing each blocks of DUC and DDC is designed for LTE signals with a Bandwidth of 20 MHz and sampling frequency of 30.72 MSPS. The key component of DUC and DDC blocks contains a cascaded integrator-comb filter (CIC) interpolator and CIC decimator, CIC compensator filter, a FIR interpolator filter and FIR decimator filter, a mixer and Numerical control oscillator (NCO).