Research And Design Of Digital Front-end Technology Based On SDR Platform

In wireless communication, for different communication systems employ a variety of architectures, standards and functions, there are problems when they communicate with each other, such as poor compatibility, poor interoperability and resource waste. The software-defined radio(SDR) technology developed on the basis of digital communications uses rigid-flex technology to construct a common platform with standardized and modular set of hardware unit which greatly improves the qualities of seamless links among the networks. In software-defined radio systems, the digital front-end(DFE), as a bridge between RF module and baseband processing module, is of great significance for the coordination between previous and following modules. The RF front-end for software-defined radio requires a very high sampling rate for wide IF sampling because its working band covers a greatly wide range. Limited by the current level of the device, the data processing capacity of baseband processing module can not keep up such requirements. Therefore, the research for high-efficiency digital front-end based on multi-rate signal processing theory has significant importance to the performance improvement of software-defined radio system.This paper presents a design of digital front-end for the application of wide IF short-wave software-defined radio station using wide IF sampling and digital mixing technologies with the standardized and modular thinking of software-defined radio and multi-rate signal processing theory. This thesis employs the top-down modular design to divide the digital front-end into basic module units according to required system functions, using QuartusⅡ、Modelsim、Matlab and Altera’s CycloneⅡseries EP2C20 as design platform to design and run simulation validation for all modules, such as digital NCO, CIC filter with compensation function, HB filter, FIR LPF and so on. Then the paper combines all modules organically to realize the design of digital front-end according to system’s requirements. Finally this paper introduces the tests and analysis to the digital front-end system in the ASIC platform and the FPGA platform separately. Test results show that the design of digital front-end module using CIC filter with compensation function meets the system requirements and has a certain theoretical value and engineering application reference.