Broadband Ofdm Systems, And Fpga Implementation

OFDM (Orthogonal Frequency Division Multiplexing) is one of the most important technologies of broadband wireless communication system. To meet the demand of real-time high rate datum service such as photo and video grown with days, and at the same time to support datum transmission in mobile environment, OFDM is applied widely, for the sake of good immunities to frequency selective, multi-path wireless channel and high ratio of information to bandwidth.According to the demand of the project, deep research on the key technology of the physical layer of OFDM system in done, include the simulation of the system and the hardware achievement of base band modulation and demodulation based on FPGA. OFDM System via Carrier Interferometer Spreading Codes and difference modulation OFDM system are also deeply researched. At the same time, this dissertation also develops a series of innovations, such as improved SCA arithmetic of synchronization of symbol, a method of synchronization of sample and carrier frequency featuring simple achieved by hardware;the design and implementation of high-speed float-point pipeline FFT Processor in FPGA based on cordic arithmetic;the design and implementation of carrier frequency offset estimation and compensation in FPGA based on cordic arithmetic;the design of high-speed array division and the circuit design for many functions such as carrier frequency offset estimation and frame arrive-detected.Chapter 1 introduces the demand and key technology of wideband wireless communication system firstly, and then, the advantage and disadvantage of OFDM, the main idea of software radio, finally gives the main work of the dissertation.Chapter 2 analyze the feature of wireless mobile communication channel firstly, introduce the element of OFDM, and finally studies the infection of the time space of cycle prefix and the number of carriers to the system.Chapter 3 as a key part of theory research of the dissertation mainly focuses on the synchronization of receiver and the methods of channel estimation of OFDM system. Firstly, influences of synchronization errors are analyzed in theory, and then the synchronization algorithms are deduced analytically. Also the simulation figures are given. Finally several methods of channel estimation are deduced analytically.Chapter 4 is about the combination of OFDM with Carrier Interferometry Spreading Codes, difference modulation and multi-access. The performance of which are deeply research andsimulated.Chapter 5 as the end of the dissertation, firstly describes the structure of OFDM base band system, gives the parameter of the system. Then fully discussed the design and implementation of all the symbols in the system.