Design And Implementation Of OFDM Baseband Transmitter Based On FPGA

OFDM is a multi-carries modulating technique which can transmit high-speed datas on wireless channel and it is popular since the 1980s. In frequency domain it splits serial high-speed datas to be transmitted in parallel sub-channels and these carriers are orthogonal by appropriately choosing frequency spaces between them.50% frequency spectrum overlap is allowed so it can improve utilization of spectrum.OFDM can reduce multipath interference effectively and overcome the effect to wireless communication caused by multipath transmitting so OFDM is paid close attention. OFDM technology is used widely in DAB and DVB standard in Europe,IEEE802.11wireless LAN, WiMAX wireless MAN and the next generation communication. This dissertation will introduce the principle,application,design and implementation of OFDM as OFDM is the main technology of WiMAX physical layer. WiMAX is a kind of wireless metropolitan area network broadband access technology and it is developed by the IEEE802.16 Working Group. It has serveal advantages,such as a large coverage area, high data transmission speed, rich businesses,high security and so on, so it gains widespread attention.This introduces the development and application of OFDM, WiMAX and its technical advantages and development status briefly, and then elaborates the principle of OFDM and the key technologies used in OFDM transmitter.Finally,it introduces the design and implementation of OFDM transmitter based on IEEE802.16d. At the transmitter, the binary datas are transmitted after scrambling, coding, interleaving, 16QAM modulation, pilot insertion, IFFT, cp-adding,windowing-adding and digital up frequency. Channel bandwidth, OFDM symbol period, length of cyclic prefix, the carrier spacing and other parameters which involved in OFDM transmitter will be set in accordance with the provisions of IEEE802.16d standard. This dissertation gives a detailed description of the design method,implementation process of the various modules and the results given in ModelSim simulation.Finally, OFDM transmitter will be implemented on Xilinx Inc. Vritex-II Pro FPGA hardware development board and observed the internal FPGA signals in on-line logic analyzer (ChipScope Pro).In summary,this dissertation implements a complete OFDM transmitter system design,simulation and hardware implementation.It is practical and can be widely applied in communication systems.