The Hardware System Design Based On DSP & FPGA And The Study On Modulation & Demodulation Technology Of OFDM

Nowadays, among the various wireless technologies, OFDM as a high-speed transmission technology can effectively fight against wave signal interference, has attracted wide attention. From WLAN to WiMAX, from the LTE to B3G, to ultra-wideband wireless communication technology UWB, OFDM has become almost a logo of modern wireless communication technologies. Researching OFDM has become a basic work to promote the development of the future mobile communication technology.Firstly, the trend of the future mobile communication technology and the origin and current situation of OFDM are presented in the paper. Based on mathematical model of OFDM, the principle of OFDM is discussed, the application in OFDM system of IFFT/FFT, guard interval & cyclic prefix and parameter selection are introduced, meanwhile, an OFDM system model is given. Secondly, the design and debug of the hardware platform based on DSP and FPGA ,which mainly includes power module,DSP module,FPGA module,ethernet port (DM9000E), serial port (ST16C550) and external memories (SDRAM and Flash), is discussed in detail, at the same time, some debugging result and notes are presented. Finally, based on 802.11a frame structure and parameters, an OFDM system parameters and frame structure are proposed, the relationship of system parameters and control words of digital upconverter (AD9957) and digital downconverter (AD6654) is analyzed, then, this paper finishes the system code in DSP and realizes the algorithm of channel estimation (LS) and demodulation (DQPSK) in FPGA, after joint debugging, the OFDM IF Transceiver is realized, and a better test result is got.