Adaptive Optical Orthogonal Frequency Division Multiplexing System Simulation And Transmitter Fpga Design

Optical Orthogonal Frequency Division Multiplexing (OOFDM) is a novel optical signal transmission technology. Compared with the existing technology, the spectrum utilization, transmission rate and distance of AMOOFDM are greatly improved, which can update existing fiber link. This technology shows less sensitivity to fiber dispersion, different launch condition and fiber types with good flexibility. This thesis presents research on theoretical models, simulation and FPGA implementation. The main contents are given as following:(1) An analysis of the theoretical model AMOOFDM. First, the key technologies of OFDM are discussed, including sub-carrier modulation, the FFT-based OFDM modulation, cyclic prefix, channel estimation, and so on. Based on OFDM technology, the theoretical model of AMOOFDM is described. Here focused on the transmitter, receiver and DFB lasers, and detailed mathematical expression of each part is given.(2) Based on multimode fiber and long-range single-mode fiber, two simulation platform of AMOOFDM system is given. Firstly, the performance of DFB lasers is simulated by Matlab to prove its performance can meet the requirements of simulation platform. Secondly, a multi-mode fiber AMOOFDM simulation platform is set up by Matlab. Through the simulation of the channel estimation, the adaptive modulation and adaptive cyclic prefix are achieved. This simulation shows that 12.5Gbps over 1000m in typical MMF channel is feasible. Long-range single-mode fiber-based AMOOFDM simulation platform is based on Optisystem and Matlab, 15Gbps transmission over 100km is achieved with fixed modulation and non-balanced.(3) The FPGA design of the OFDM transmitter is achieved by Verilog, and simulated through ModelSim, including the modulation mapping module, FFT module, cyclic prefix insertion module, training symbols insertion module. The FPGA design of 100Mbps OFDM transmitter is achieved.