FPGA Implementation And Frequency Sensing Function Researching Of Cognitive Radio

Cognitive radio is an intelligent wireless communications system that can be perceived around the wireless environment, by analysing the wireless environment, it could make changes to the corresponding parameters to adapt to the environment in real time in order to enhance utilization of the spectrum and to ease the tension of spectrum resources. The key technology and hardware implementation of frequency sensing used in Cognitive Radio(CR) System are presented in this paper.Firstly,a brief background and cognitive radio technologies are introduced, as well as related key cognitive radio technology content. And then this article also describes the tructure of the system,the programme for the realizing and main functionalities for each module.Finally,the hardware implementation and werification processes based on FPGA are presented in detail.Digital signal processing module aims to obtain the Short-Time Fourier Transform (STFT) of broad-band signals. The time-and-spectrum relationship of the signal is displayed via Fast Fourier Transform (FFT) analysis.Then,the data is delivered to DSP to manage. The whole system is composed of 4096-point pipelining FFT module, data buffers selected module, square adder module and so forth.This design is build on Virtex-4 XC5VSX35T FPGA of the Xilnx Corp using hardware descriptive language called Verilog HDL. The synchronous method is adopted in the whole system, so that the system can run steadily under 102.4MHz clock. Its analysis frequency band is up to 5MHz, which is proved of the high value in practical applications.