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Investigation On The Key Technologies Of Improvement Of System Capacity And Power Budget In Direct Detection OFDM-PON

Posted on:2017-09-23Degree:MasterType:Thesis
Country:ChinaCandidate:T TongFull Text:PDF
GTID:2348330518496327Subject:Electronic Science and Technology
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With gradual development of various data traffics,especially video traffic,users' demands for network bandwidth further increase?Passive optical network(PON)is faced with key issues of improving system capacity to support more access users and supporting longer transmission distance.Belonging to multi-carrier modulation technology,Orthogonal Frequency Division Multiplexing(OFDM)technology,with advantages of high spectrum efficiency and strong ability to resist dispersion,can meet the need of larger capacity of PON.By means of the mature digital signal processor(DSP)technology,OFDM can realize flexible access network bandwidth management control.Direct detection(DD)can greatly reduce the complexity of receiver devices and the DSP algorithm.Therefore,the OFDM technology combined with DD method with lower cost in PON has received widespread attention.Polarization multiplexing(PM)technology can transmit two independent signals on two polarizations,respectively,so that system capacity and information rate can be multiplied.However,how to improve efficiency of electronic spectrum and reduce the cost and complexity in optical network unit(ONU)are problems needed to be solved.Besides,performance of linear-field modulated PM-DD-OFDM-PON system is limited by the subcarrier-to-subcarrier beating interference(SSBI)injury,so how to find the right solution to suppress SSBI and improve system power budget is another issue.In addition,how to realize polarization demultiplexing in PM-DD-OFDM-PON system based on sub-rate ONU is also need to be solved.This paper mainly studys the above problems.The main work and innovative contributions are listed as follows.1.In view of PM-DD-OFDM-PON system with large capacity and GB decreasing efficiency of electronic spectrum,the paper puts forward a PM-DD-OFDM-PON system scheme with less GB to improve electronic spectrum efficiency.The simulation results of 100Gbps-PM-DD-OFDM-PON system show that a 5.5dB receiver sensitivity penalty can double the system capacity and increase spectrum efficiency to 4/3 compared with the DD-OFDM-PON system when GB is set to 1/2.2.In view of SSBI injury in PM-DD-OFDM-PON system without GB,we design a SSBI suppression algorithm based on iteration in ONU.According to SSBI principle,the scheme considers the dispersion,polarization crosstalk,and square law of DD.Firstly,we reconstruct OFDM signal of two polarizations after polarization rotation during fiber transmission.Then,we reconstruct SSBI of each polarization after direct detection to reduce SSBI of useful signal.The simulation results of 100Gbps-PM-DD-OFDM-PON system show that the improvement of system receiver sensitivity of the scheme is about 5.4dB,increasing the power budget of the system effectively.3.To reduce high cost and requirements of ONU in current PON system which has the same rate in OLT and ONU,we design a sub-line rate scheme which is suitable for large capacity polarization multiplexing system.In this scheme,with reasonable design of polarization multiplexing sub-bands and sub-line rate signals bands,sub-line rate ONU receiver and polarization multiplexing can cooperate effectively,decreasing the cost of the devices in ONU.The simulation results show that PM-DD-OFDM-PON system based on sub-line rate ONU can significantly lower the device cost of ONUs compared with the line rate scheme.
Keywords/Search Tags:Passive Optical Network, Orthogonal Frequency Division Multiplexing, Polarization Multiplexing, Direct Detection, Subcarrier-to-subcarrier Beating Interference
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