Research Of WDM-PON Based On Optical Orthogonal Frequency Division Multiplexing

Nowadays, the access network is facing the unprecedented challenge of the increasingdemands for high speed access, the growing access capacity and the interpenetration ofmulti-services etc.. The existing optical fiber access network has shown a solidifyingcharacter which can only offer fixed link speed and is difficult to meet the requirements of theemerging network technologies and broad band multimedia services.Optical Orthogonal Frequency Division Multiplexing (O-OFDM) access technology hasthe characteristics of high spectral efficiency, large capacity access, etc.. All those can meetthe requirements of different quality service parameters and bandwidth. There are a lot ofadvantages of Optical Orthogonal Frequency Division Multiple Access technology, such asallowing seamless integration of wireless and wired access method, compatible with existingoptical access network, making it an attractive means of access. This article is based on thetopic of the State Key Laboratory of Advanced Optical Communication Systems&Networks(2011GZKF031109) and the Project supported by the Natural Science Foundation ofShandong Province (ZR2010FM043). We made some research and innovation to the passiveoptical networks based on the key technology of OFDM. Some major research contents andachievements are summarized as follow:(1) We analyzed the generation of the OFDM signal, the suppression principle of OFDMcyclic prefix to the inter-symbol interference and inter-carrier interference. At the same time,we researched the principle of coherent detection that to suppress noise and the generation ofcarrier frequency offset as well as the compensation methods of it.(2) For the carrier frequency offset, we use the correlation of the cyclic prefix tocompensate for the decimal part of carrier frequency offset. By inserting virtual subcarrier tocompensate the integer part frequency offset. For the phase noise, we use pilot symbols to dochannel estimation and equalization. As ONU is sensitive to the implementation costs, weutilize the reflective semiconductor optical amplifier (RSOA) to achieve the "colorless" ofONU, which is part of the downlink optical carriers recovery as uplink optical carriers by using the gain saturation characteristics of RSOA.(3) In this paper, we build a direct detection optical OFDM system. In this system, byinserting time domain block pilot, dressing pilot and rectangular pilot, we compared thetransmission performance improved by the three ways. We build a coherent detection opticalOFDM system. In this system, we used LS and MMSE algorithms to improve thetransmission performance. Based on Matlab and Optisystem simulation software, weconstructed a OFDM-based WDM-PON simulation platform. In this platform, the downlinkrate is20Gb/s, uplink rate is5Gb/s. We also analyzed the influence of different parameters ofit. In the uplink of ONU to OLT, we compared the influence of different modulation formatfor transmission performance, such as BPSK, QPSK and DQPSK. This paper investigated therelationship between the distance and the transmission error rate at different injection opticalpower of RSOA. To the different optical power of this system, we analyzed the effect of biascurrent to the bit error rate. Based on the researches above, we can provide some practicalreference to OFDM-based passive optical access network.(4) We introduced the FPGA design flow, the Quartus II12.0simulation software and theVerilog HDL hardware programming language. At the end of this paper, we modeled somepart of the digital processing.