Investigation On MQAM Modulation Format And DSP Algorithms Toward Elastic Optical Network

In order to improve the utilization of resources in networks,elastic optical network has become the future development trend for supporting large capacity,flexibly allocating of spectrum and optimizing network resource allocation.For the purpose of supporting flexible configuration of optical transmission length,bit rate and spectrum efficiency,elastic optical network architecture should possess a variable modulation format,a variable symbol rate,universal transmitter structures and DSP algorithms as its essential attributes.In this paper,we studied the modulation formats which are flexible switching between the spectrum efficiency and power efficiency.And we also studied the general structure of the transmitter and the receiver DSP algorithms.The main research work is constructed as follows.1.Considering the requirement of the dynamic optical link connection of the flexible optical network and spectrum efficiency and power efficiency,a four-dimensional modulation format 128-SP-QAM ementation scheme is designed.In the 5 wavelength WDM transmission simulation,at the same symbol rate(30GBaud),the OSNR requirement of 128-SP-QAM relative to PM-16QAM in the error rate of 1e-3 reduces 2.1dB,but at the same time it sacrifices the 1/8 spectrum efficiency.Compared to the PM-16QAM,128-SP-QAM improves the power efficiency at the expense of spectral efficiency cost,making both in the spectrum efficiency and power efficiency to meet the requirements of elastic optical network node.2.Further more,in order to improve the change of particle size of spectrum efficiency and power efficiency,we propose a scheme of an eight-dimensional modulation format 8D-16QAM(Eight-dimensional modulation format based on polarization multiplexed 16-QAM).In the 5 wavelength WDM transmission simulation,at the same symbol rate(30GBaud),the OSNR requirement of 8D-16QAM relative to PM-16QAM in the error rate of 1e-3 reduces 1.5dB,but relative to 8D-16QAM,the OSNR of 128-SP-QAM has 0.4dB gain.The "mutual compromise" of the three modulation formats between the spectrum efficiency and power efficiency can be used in the adaptive allocation of the elastic optical network node equipment.3.We would like to make the transmitter and DSP algorithm more versatile so as to support the mutual compromise and flexible configuration of transmission length,bit rate and spectrum efficiency.Therefore,in this paper we proposed an universal transmitter architecture to.support QPSK and 16QAM modulation formats by adopting a universal DSP algorithm at the receiving end.We conducted overall performance test for PM-QPSK and PM-16QAM for further verification.Through the simulation,we verified the generality of the transmitter structure and DSP algorithms.