All Phase Key Technologies OFDM FPGA-based Systems

OFDM technology is the key technologies of wireless communication and the next generation wireless LTE (4G), but it always produces a phase shift in the time-varying incentive environment, causing the carrier signal reduction distortion. Instead, the FFT with all-phase signal pretreatment technology can keep phase invariable, and studies show that using the technology of OFDM system can effectively solve phase error, significantly reducing noise power. FPGA technology is adopted in this project, which has faster speed and better reconstruction, to realize the all-phase FFT processing unit used in signal processing of OFDM systems, exploring the key technology of all-phase OFDM systems in time-varying wireless channels, studying the performance parameters and the advantages Compared to the conventional scheme.This thesis compares some kinds of common all-pahse data pre-procedssing patterns from the errors aroused by the truncated signals, uses the windowsless all-pahse data pre-procedssing pattern to implement the all-pahse processing module of this system. This thesis further studies and analyzes all-pahse FFT in the application of OFDM system, and implements a kind of all-pahse OFDM baseband transmission system. The main modules of APFFT, channel coding and decoding, interleave and deinterleave, constellation mapping and solution mapping, convolutional encoding and viterbi encoding etc. which are implemented by the system conform to the Avalon bus specification for facilitating the connection and control between the modules. The Nios II soft core processor is added to the system to build a intergrated SOPC platform, and relevant drivers and software are implemented to achieve the control of the whole platform. The system benefits from the parallelism and dynamic reconfigurable feature of FPGA, and simulates the OFDM system which is used the technology of all-phase.The design of the system is adopted the integrated development environment of Quartus II, Nios II IDE etc. and the simulation tool-ModelSim, the final verification platform is DE2developement tools which is produced by Altera. It has proved that this system can accomplish the process of the OFDM system baseband signal and runs safely and steadily under the50MHz clock frequency. After the design of the system, this thesis analyzes detail the system from computation complexity, inhibition of spectral leakage, error rate, computational efficiency etc. The result displaies that the APOFDM system has distinct capable advantages when compared with the traditional OFDM system, the system has the characteristics of low power, high degree of integration and good stability, so it has important reference value for further improvement of the OFDM system and it also has some theoretical and practical value.