Research On Time-domain Non-orthogonal Pulse-overlapping Technology

Since 5G has been commercialized,artificial intelligence,big data,Internet and other emerging technologies has been promoting rapid growth in network traffic,which makes bandwidth resources more strained.The main way to improve transmission capacity and spectral efficiency focus on improve the modulation order of quadrature amplitude modulation format and compress spectral bandwidth,for the former,the number of constellation points of the high-order modulation signal increases exponentially with the modulation order,while the number of constellation points of the non-orthogonal time-domain pulse-overlapping signal increases linearly with the increase of aliasing number,in contrast,non-orthogonal time-domain aliasing signals have lower requirements on OSNR.For the latter,the spectral efficiency of simply compressing the bandwidth is limited.In order to transmit more data in limited spectral bandwidth,we proposed the non-orthogonal time-domain pulse-overlapping technology,whose spectral efficiency is improved by reducing the time interval among the time domain pulses.1.Firstly,based on the time domain orthogonal multiplexing technology and non-orthogonal multiplexing technology,the paper compared and analyzed the time domain orthogonal multiplexing transmission and non-orthogonal multiplexing transmission model,meanwhile derive the channel capacity formula of them.The results showed that the channel capacity of the time domain non-orthogonal multiplexing system can be larger than that of the time domain orthogonal multiplexing system.2.Secondly,a 10Gbaud IM/DD optical communication system based on non-orthogonal time-domain aliasing multiplexing technology was built.The transmission performance of PAM4 and Pol2-OOK,PAM8 and Pol3-OOK,and PAM 16 and Pol4-OOK were compared under rectangular forming condition.The results showed that the receiving power of Pol2-OOK,Pol3-OOK and Pol4-OOK was 2.5dB,4.5dB and 8.5dB less than that of PAM4,PAM8 and PAM16,respectively,when the bit error rate hard decision threshold(0.0038)was reached.3.Thirdly,a coherent optical transmission system based on non-orthogonal time-domain mixing multiplexing technology was built and the signal processing algorithm of the receiver of the system was analyzed.The simulation results show that the bit error rate of 28Gbaud PDM-Pol2-QPSK is lower than that of PDM-16QAM when the 3dB bandwidth of the transmitting and receiving filter is greater than or equal to 33.6GHz under the condition of rectangular forming.And the minimum transmission power required for PDM-Pol2-QPSK transmission in 1000km single-mode fiber is less than or equal to the PDM-16QAM system with the same rate.Under the condition of Square Root Raised Cosine(SRRC)forming,when the 3dB bandwidth of the transmitting and receiving filter is greater than 33.6GHz,The bit error rate of PDM-POL2-QPSK-SRRC with roll-down factor of 1.0 is lower than that of PDM-16QAM-SRRC.