Study On Software Radio In 3G Digital Font-End Transceivers

Software radio (SR) has been proposed to be applied to wireless communication system, aiming at constructing a hardware platform with characteristics of openness, standardization and modularization to utilize the software to perform diverse functions, such as work frequency, modulation or demodulation type, data format and communication protocol. Moreover, it is applied to make wideband A/D and D/A approach to antenna as much as possible to develop a new generation of wireless communication system with characteristics of high agility and openness.SR can provide feasible technique in realizing the 3G. The SR system can be applied to reduce problems that come forth in configuring the wireless communication system in accordance with different standard for aerial interfaces. The analog function of different wireless communication system is realized mostly by the software-reprogrammable hardware in the digital section. However, it will significantly increase the required computations for a great discrepancy between computation precision of the digital front-end and function of filtering waves within different systems. The thesis aims at advancing the extent of precision in the digital front-end and improving the function of filtering waves in SR, in order to reduce the costs of computation and to increase the performance of SRC. In order to achieve the above mentioned goals, the thesis studies from two aspects, one is structure of CIC; the other is method of SRC.The thesis proposes a modified CIC filter, which can increase computation validity of SRC; the comb stage of this modified CIC filter adopts different delay to provide better side-lobe suppression and image frequencies attenuation. Most of studies have not further analyzed what data should be chosen in SRC and delay list. This paper analyzes the structure of conventional CIC filter and existing modified method. By controlling the delay of CIC filter comb stage, the thesis analyses how to choose data of SRC and delay list. It can provide better side-lobe suppression and image frequencies attenuation using reasonable plan of choosing data by way of computation can show it.In addition, the thesis studies the SRC system that efficiently increases the sample rate of wideband signals, by applying Lagrange interpolation to evaluate output samples. The paper also discusses the computations of this SRC system. This system can significantly reduce not only the average number of computations per sample for some SRC stages, but also the computations for the whole SRC process.