Research Of FEC And Equalization Technologies For10GB/S WDM-PON System

With the rapid development of Internet, a variety of new rising business emerging, people’s requirement for transmission bandwidth is becoming higher and higher, optical access technology is facing unprecedented challenges. As a new type of optical access network, wavelength division multiplexing passive optical network (WDM-PON), which can meet the demand of the high-speed growth bandwidth, compatible with other optical access technology effectively. The colorless optical network unit (ONU) based on reflective semiconductor optical amplifier (RSOA) has been considered as a technology which can promote the flexible allocation of wavelength resources, improve the bandwidth utilization effectively and reduce the deployment cost, thus has become one of research hotspots. Because of the limited modulation bandwidth of RSOA, it is hard to achieve the10Gb/s rate symmetrical system.Through adding redundancy error correcting code after the information code, under certain conditions, forward error correction (FEC) technology can automatically correct the transmission error to reduce the bit error rate (BER) of the received signal. Therefore, FEC technology can be used in WDM-PON system based on RSOA to compensate the insufficient modulation bandwidth of RSOA, and then the rate symmetrical system can be realized. In addition, the equalization technology can also be used to compensate the damage of transmission channel, reduce the intersymbol interference, and improve the system transmission performance.With the experimental platform of access network in the laboratory and the tools of Altera QuartusII, VPI, Modelsim10.0and matlab, this thesis studied the FEC and blind equalization technology in WDM-PON system. The main research works are as follows:Firstly, the developing situation and key technologies of WDM-PON are elaborated, typical FEC schemes and blind equalization schemes are compared and analyzed. Participate in the proposition of a multi-wavelength10G-EPON system based on RSOA.Secondly, FEC parallel codec schemes with the rate of lOGb/s are designed, and implentated by FPGA. The FEC type is RS (255,223), its codec adopts eight-time parallel encoding algorithm based on recursive formula and nine-time parallel decoding algorithm based on EDCME.Thirdly, both the transimiiter and receiver of multi-wavelength10G-EPON Physical coding sublayer (PCS) are designed and realized by FPGA, the function simulation and timing verification have been passed.Fourthly, aimed at the problem of serious patten effect of high-level modulation signal in WDM-PON system, a dual-mode blind equalization algorithm that combined Constant Modulus Algorithm (CMA) and Decision Directed (DD) is proposed and simulated under three different channels. The results show that the constellation diagram become more converged after blind equalization, bit-error-rate was decreased, and the phase shift caused by two wavelength hybrid transmission can also be corrected.