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Coherent Optical Orthogonal Frequency Division Multiplexing (CO-OFDM) technology is a new optical multiplexing, the coherent detection and OFDM technology has the dual advantages of high spectrum efficiency, against the dispersion and nonlinear effect is obvious, but in the present Some network infrastructure can be a good upgrade, easy expansion, so in high-speed, high-capacity and long-distance transmission system has broad application prospects. In this paper, single-mode fiber CO-OFDM system and its synchronization algorithm research, including system works, different modulation transmission performance of the system under analysis, timing synchronization algorithms, and high rates of single-mode fiber CO-OFDM communication system design and Simulation. Specific work as follows: (1) single-mode fiber of CO-OFDM system works in 2PSK, 4QAM, 8QAM, 16QAM modulation mode, four kinds of single-mode fiber 10.7Gb/sCO-OFDM analyze the performance of the transmission system and simulation, draw transmission capacity, transmission distance, and the BER is among conflicting, OSNR increases to a certain extent, improve the system performance. When the system bit error rate remained at 10-3 or less, and take 4QAM modulation, the OSNR is 12 dB, the transmission distance of up to 1600 km, when the OSNR is increased to 19 dB, the system's maximum transmission distance of 1900 km. (2) For the traditional algorithm for dispersion-sensitive paper proposes a new improved algorithm training symbol sequence structure is based on the original symbol, the first one has been added cyclic prefix of the OFDM symbol length of the tail replicate L (i.e. in the structural CP2) placed in front of the symbol, namely the use of a training sequence CP2, L is generally greater than the length of the cyclic prefix, and then use this pseudo-random sequence of phase fluctuation replicating sequence specific structure: [CP2CP OFDM]. In the same simulation conditions, the use of Schmidl Cox algorithm, Minn Letaief algorithm and Park Cheon algorithm and improved algorithm to 1000 time points for the simulation, the improved algorithm error rate averaging is always maintained at 12% or less, more suitable for Fibre Channel. (3) using orthogonal bandwidth multiplexing (OBM) technology and optical structure of 2 × 2 CO-MIMO-OFDM system model, to complete the transfer rate is theoretically 107Gb / s of CO-OFDM system design single-mode fiber. For the design of 2 × 2 CO-MIMO-OFDM system, timing synchronization mode fiber analysis and simulation show that the proposed method of synchronization in the system is feasible.
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