MATLAB Simulation Of CO-OFGA And FPGA Design Of Baseband Function

Orthogonal frequcncy division multiplexing(OFDM) recently has been widely appliedin broadband wired and wireless communication system. With its high spectrum efficiency,effective resistance of ISI, and easy to realized by hardware, OFDM is also significant inoptical commucation field, and has been a very promising technique for Ultra-high speed，Ultra-high capacity，Ultra-long haul optical communication.This thesis, with the reference of wireless protocol802.11a，implemented OFDMbaseband tranceiver function with FPGA, line rate up to100Mbps, and proposed totransplant relevant technique to optical communication field, that is, using powerfulprocessing capacity of FPGA and MZM high speed optical IQ modulation, to completesignal handling in electrical field, and transmitting in optical field.Then used MATLAB tosimulate the system. The result shows that BER keeps lower than10-2when SNR is higherthan1dB; while BER falls near zero when SNR is high than5dB. The following areimplemented by FPGA:(1) Scrambler/Descrambler, to avoid long sequence of0or1in data.(2) Convolutional encoding/Viterbi decoding，used for error correction.(3) Interweave/Deinterweave, transforming burst error to random error, which makesthe performance of error correction decoding better.(4) QAM mapping/demapping, modulates data with vector method, and prepares thedata for IFFT/FFT module.(5) IFFT/FFT, using FFT algorithm to complete OFDM modulation of data.(6) Time/frequency domain synchronization, with reference of802.11a protocol，implementing frame sync, carrier frequency sync, symbol sync, channel estimation andequalization, sampling frequency sync, phase track.