Design Of IF And Baseband Signal Process System For OFDM

Because of the signal attenuation and muti-path effection and time-varying characteristic of the wireless channel, the quality and efficiency of broadband wireless communication are badly affected. On the other hand, Orthogonal Frequency Division Multiplexing (OFDM) have been a very important technology which is introduced into radio communication field to get such advantages as bandwidth efficiency, resistance to multipath fading and high data rate transmission etc. Therefore, it is a wonderful research direction to introduce high performance OFDM technology into broadband wireless communication systems.Taking account of the requirements of applying OFDM technology into broadband wireless communication practices, this thesis introduces a design of intermediate frequency and baseband signal process system for OFDM. This system can not only used to research the algorithms of OFDM technology, enhance the data transmission rate and anti-interference ability of wireless communication, but also be a verification platform for other modulation technology.The scheme of DSP+FPGA is used in this design. In which DSP works as the center of the system to modulate and demodulate OFDM signals, and shakes hand with the control set of wireless communication platform. FPGA is used to realize the functions as digital down converter (DDC), digital up converter (DUC), and UART transceivers etc. This system of which the parameters can be configed via RS232 works on full duplex mode. The OFDM signal bandwidth and transmission rate for user data that this syetem can deal with are up to 12 kHz and 19.2 kbps.The primary endeavor of this thesis includes conceptual design and function module design of the system. Conceptual design includes the framework design and the IC selecting. Function module design includes signal conversion, digital frequency conversion, OFDM modulating and demodulating, peripheral interface and system boot loader design. Specifically, the work of this thesis includes hardware schematic diagram designing, PCB designing, hardware platform debugging, FPGA program designing and debugging, and system function testing. The final testing shows that the design of this system is successful on the whole.