| As IPTV, HDTV and other high-speed applications are being used in everyday life, the demand of bandwidth grows at a rapid speed. Wavelength division multiplexing passive optical network (WDM-PON) has become one of the mainstream technologies for the new optical access networks to meet the high-speed growth in bandwidth demand and be compatible with the existing kinds of optical fiber access network.As one of the main researchers, the author participated in the National Natural Science Foundation project "Mechanism research and experimental validation of optical RF signal processing based on RSOA" and "Research of all-optical signal processing technology based SO A and MZI". With the access network experimental platform in the laboratory and the tools of VPI, Xilinx ISE and Modelsim6.5, this thesis do the research of forward error correction (FEC) technology and the new modulation technique in lOGbps WDM-PON system. The main research works are as follows:Firstly, three schemes of "colorless" ONU (Optical Network Unit) which are the key technology of the WDM-PON are compared and analyzed. The reflective semiconductor optical amplifier (RSOA)-based colorless ONU is the most low cost potential solution and the adaptivity of wavelength is high with the larger bandwidth range.Secondly, Reed-Solomon (RS)(255,223) as the FEC code applied in lOGbps WDM-PON is designed, which adopts8-parallel algorithm based on improved state space transformation (SST) method for RS(255,223) encoder and9-parallel algorithm based on enhanced degree computation-less modified Euclid’s (EDCME) algorithm to solve the key equation for RS(255,223) decoder. With the RS (255,223) codec to correct the burst errors or random errors in transmission system, it can be transmitted error free (bit error rate (BER) is lower or equal to10"12). The whole encoder and decoder are implemented with Hardware programming language of Verilog HDL in Xilinx FPGA and then have been measured and analyzed. The results show:paraties can be obtained from the parallel RS (255,223) encoder after seven clock time latency and the data throughput can be increased by9times with the9-time parallel RS (255,223) decoder. EDCME algorithm to solve the key equation can reduce the critical path length and then save the latency. The coding gain provided by RS (255,223) can extend the transmission distance, reduce the optical power budget, reduce the BER and then to improve the receiver sensitivity further. RS parallel encoding and decoding schemes are the focus of the thesis.Thirdly, a10Gbps full-duplex WDM-PON system with RSOA-based colorless ONU is simulated and the performance is analyzed. In order to reduce the effect of the Rayleight backscattering (RB) in single fiber, Differential phase shift keying (DPSK) is used in downstream and NRZ-OOK is used in upstream, because DPSK has a lower OSNR tolerance, a greater ability of the anti-fiber nonlinear effects and greater dispersion tolerance. The simulation results show:Mach-Zehnder Interferometers (MZI) applied as a two-tap optical equalizer can improve the performance of uplink and resolve the inadequate response problem of RSOA to high-speed signal. In the back-to-back case,-3dB of the uplink-received sensitivity can be improved with MZI. A better-received sensitivity of-12.68dBm@BER=2.5x10-3can be obtained with MZI after twenty kilometers SMF transmission and the received sensitivity can be improved by5dB with RS (255,223). |
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