Ofdm - Pon System Architecture And Performance Improvement

With the vigorous development of the Internet and the rise of multimedia services,there is an increasing requirement on the large capacity and high rate communicationsystem. However, the current optical fiber access networks which lack of flexiblebandwidth allocation ability for the users have become the "bottleneck" of the wholenetwork. OFDM-PON which has high spectrum efficiency, strong tolerance to fiberdispersion and flexible bandwidth allocation, has been recognized as a promisingcandidate for the future access network.In this thesis, the OFDM-PON developing history, recent research status and itsbasic principle and related technology have been introduced. This thesis focuses on thearchitecture of OFDM-PON system and the improvement of system performance.In this thesis, the author tried to find a kind of OFDM-PON system architecturewith simple structure, good performance and low cost. The source-free ONU structurein OFDM-PON has been studied. And a scheme which enables all-optical VPN andall-optical ONU inter-communications in OFDM-PON has been proposed anddemonstrated. One of the advantages of the OFDM-PON system is the bandwidthdynamic allocation (DBA). A scheme of DBA in OFDM-PON, in which the length oftime slot is tunable has been proposed.In addition, the high PAPR of OFDM signal deteriorates the performance of thesystem, which is a key problem in OFDM-PON. This thesis analysed how the highPAPR comes and introduced several conventional methods of reducing the PAPR. Andproposed a scheme which utilizes the combination technique of data clipping andadditional phases (APs) to lower the PAPR and improve the performance ofOFDM-PON system. Finally, system simulations were performed by MATLAB and VPIin order to demonstrate the feasibility and the performance of the proposed scheme.