The Study On Architecture And Transmission Performance Of OFDM-PON

The most important advantage of optical access technology based on orthogonalfrequency division multiplexing passive optical network (OFDM-PON) is that it caneffectively improve the ability of resisting the effects such as chromatic dispersion,thereby improving the performance of the optical access network. The OFDM-PONtechnology can convert the one-serial high speed data stream into sub-parallel lowspeed data streams, and could effectively reduce the inter symbol interference (ISI)and inter code interference (ICI), can offer a flexible resource scheduling at frequencyand time domain，has become a very attractive technology for next generation opticalaccess network.In order to meet the demands of next generation access network, this paper mainlyfocuses on OFDM-PON scheme designments. Three innovative schemes aboutOFDM-PON have been proposed and the feasibility of the proposed architectures isanalyzed. The main contents and the innovation are as follows:1) Focusing on the cost-effectiveness of the (optical network unit) ONU, wepresent a novel colorless OFDM-PON system. For design of colorless ONU,we mainly compare the colorless ONU based on reflective semiconductoroptical amplifier (RSOA) and fabry-perot laser diode (FP-LD). For the systemdesign, two separated wavelength bands are employed as optical sources forboth the downstream and upstream transmission. The cross-modulationtechnology is employed in ONU, so the upstream and downstream signals areat different bands. This can alleviate the effect of the Rayleigh noise andcrosstalk for the upstream and downstream signals are at the same band.Finally, from analysis and simulation the proposed system, validate that thesystem has good performance.2) We proposed novel a OFDM-PON system based on Optical CarrierSuppression and Separation(OCSS)technique and focused on reducingexpenses of the proposed system. Sub-carriers are used for2NONUs, butonly N lasers are employed through using OCSS technique. This can greatlyreduce the system cost. In this paper, we describe the working principle of theproposed OFDM-PON system, and also analyse the simulation results.3) For network survivability issues, a new self-protected architecture forOFDM-PON is proposed. And whether the fiber between the OLT and the RN or that between the RN and the ONU is failed, the proposed OFDM-PONsystem can be switched automatically to the protection state to restore networkcommunication at both OLT and ONU, the optical switch is under controlledby power monitor. In order to decrease peak to average power ratio (PAPR), wecan properly reduce the number of OFDM subcarriers. The SER ofdownstream and BER of upstream are analyzed under normal and protectedmode respectively.