The Application Of Adaptive Modulation Technology On OFDM-PON System Dynamic Balance Bandwidth Allocation

With the development of the Passive Optical Network(PON)system,OFDM-PON has become one of the main research contents of the next generation access network for its high efficiency and flexibility.How to effectively allocate the system bandwidth among the huge number of optical network units(ONUs)is one of the key problems before OFDM-PON can be practical deployed.At first,this paper introduces the network structure of the passive optical network,discusses the basic principle of OFDM technology,and summarizes the key technologies of OFDM-PON.Secondly,this paper studies the dynamic bandwidth allocation algorithm based on OFDN-PON system and the development history of adaptive modulation algorithm and basic principle.On the basis of traditional time,wavelength and power of 3d dynamic bandwidth allocation model,combining adaptive modulation technology,proposed a dynamic allocation based on the four dimensions of adaptive modulation algorithm,and the single ONU transmission performance optimization.Bit loading is used to allocate the total transmission capacity.In the case of a certain bandwidth,the ONU with higher contrast ratio is realized by a higher order modulation mode,and the system capacity can be flexibly allocated.Power loading is used to guarantee the ONUs have balanced transmission performance even if they operate at different bitrate.In the coexist length of the distance OFDM-PON,due to the difference between each user location,the time delay caused by different distance is inevitable.Based on MG-DBA algorithm to ONU grouped according to different distance,this paper combined with the adaptive modulation algorithm to optimize the OSNR of the long-distance ONU,which has realized the long-distance OFDM-PON system bandwidth of dynamic equilibrium.Finally,this paper design an experimental OFDM-PON bandwidth allocation model on OptiSystem 14 software.