In this paper, a simplified optical millimeter-wave generated by two optical sidebands beating together in a 60 GHz radio over fiber (RoF) system with 10 Gbit/s 4-pulse amplitude modulation (4 PAM) transmission signal...In this paper, a simplified optical millimeter-wave generated by two optical sidebands beating together in a 60 GHz radio over fiber (RoF) system with 10 Gbit/s 4-pulse amplitude modulation (4 PAM) transmission signal is proposed and simulated. 10 Gbit/s electrical 4 PAM signals modulated are conveyed over the length of 40 km standard single mode fiber (SMF) and recovered via the self-mixing technique after detecting directly at the receiver. Graphs of time-domain wave, frequency-domain and optical spectrum are measured out in different period, and the comparison of error vector magnitude curves of NRZ and 4 PAM signals under the different length of fiber is accomplished. The capacity of 4 PAM modulation is higher, though NRZ performs better than 4 PAM selected in RoF system within 80 km of fiber length as shown in the simulation results.展开更多
4-ary pulse amplitude modulation(4PAM) signals with 33% and 50% return-to-zero(RZ) clocks are generated for passive optical network(PON). We demonstrate that RZ-4PAM signals with duty cycles of 33% and 50% after trans...4-ary pulse amplitude modulation(4PAM) signals with 33% and 50% return-to-zero(RZ) clocks are generated for passive optical network(PON). We demonstrate that RZ-4PAM signals with duty cycles of 33% and 50% after transmission over 20-km-long single mode fiber(SMF) at 10 Gbit/s can be directly detected by using one photo detector,and the original data can also be restored by one M-ary threshold detector and one 4PAM sequence decoder. The optical spectra of 33% and 50% RZ-4PAM signals are measured,and their eye-diagrams before and after transmission are also analyzed. Simulation results show that 33% and 50% RZ-4PAM downlink signals can be received effectively,and the received power values are-15.1 d Bm and-13.8 d Bm when the bit error rate(BER) is 10^(-6). Moreover,33% RZ-4PAM optical signals have better reception performance than 50% RZ-4PAM optical signals.展开更多
提出了一种适用于超短距离(Very Short Reach,VSR)信道、面向112 Gb/s PAM4(Pulse Amplitude Modulation 4)接收机的自适应均衡设计方案。在该方案中,接收机前端利用3个连续时间线性均衡器(Continuous Time Linear Equalizer,CTLE)对信...提出了一种适用于超短距离(Very Short Reach,VSR)信道、面向112 Gb/s PAM4(Pulse Amplitude Modulation 4)接收机的自适应均衡设计方案。在该方案中,接收机前端利用3个连续时间线性均衡器(Continuous Time Linear Equalizer,CTLE)对信号分别在高频、中频和低频进行补偿,可变增益放大器(Variable Gain Amplifier,VGA)和饱和放大器(Saturation Amplifier,SatAmp)则用于对信号幅值的缩放。除了3个数据采样器外,引入4个辅助采样器用于进一步改善阈值自适应算法性能。同时,采用符号最小均方算法,利用接收端数据采样器和辅助采样器之间的偏移推动辅助参考电压收敛到信号星座电平,从而确保PAM4接收信号的眼图在垂直方向上3个眼睛具有相等的间隔和恒定的信噪比(Signal-to-Noise Ratio,SNR)。仿真结果表明,所提出的112 Gb/s PAM4接收机能够在损耗为15 dB的信道上实现小于10~(-12)的误码率,并且具有良好的眼图性能,其最差眼高为75 mV,眼宽为0.34 UI(Unit Interval),与传统方案相比具有显著的性能提升。展开更多
This paper aimed to propose two algorithms,DA-M and RF-M,of reducing the impact of multipath interference(MPI)on intensity modulation direct detection(IM-DD)systems,particularly for four-level pulse amplitude modulati...This paper aimed to propose two algorithms,DA-M and RF-M,of reducing the impact of multipath interference(MPI)on intensity modulation direct detection(IM-DD)systems,particularly for four-level pulse amplitude modulation(PAM4)systems.DA-M reduced the fluctuation by averaging the signal in blocks,RF-M estimated MPI by subtracting the decision value of the corresponding block from the mean value of a signal block,and then generated interference-reduced samples by subtracting the interference signal from the product of the corresponding MPI estimate and then weighting factor.This paper firstly proposed to separate the signal before decision-making into multiple blocks,which significantly reduced the complexity of DA-M and RF-M.Simulation results showed that the MPI noise of 28 GBaud IMDD system under the linewidths of 1e5 Hz,1e6 Hz and 10e6 Hz can be effectively alleviated.展开更多
文摘In this paper, a simplified optical millimeter-wave generated by two optical sidebands beating together in a 60 GHz radio over fiber (RoF) system with 10 Gbit/s 4-pulse amplitude modulation (4 PAM) transmission signal is proposed and simulated. 10 Gbit/s electrical 4 PAM signals modulated are conveyed over the length of 40 km standard single mode fiber (SMF) and recovered via the self-mixing technique after detecting directly at the receiver. Graphs of time-domain wave, frequency-domain and optical spectrum are measured out in different period, and the comparison of error vector magnitude curves of NRZ and 4 PAM signals under the different length of fiber is accomplished. The capacity of 4 PAM modulation is higher, though NRZ performs better than 4 PAM selected in RoF system within 80 km of fiber length as shown in the simulation results.
基金supported by the National Natural Science Foundation of China(No.61107064)the Chongqing University Innovation Team Founding(No.KJTD201320)+3 种基金the Natural Science Foundation of Chongqing Science & Technology Commission(Nos.cstc2014jcyj A40046 and cstc2016jcyj A1233)the Science and Technology Special Funds of Wanzhou District in Chongqing Citythe Chongqing Graduate Student Research Innovation Project(No.CYS15225)the Chongqing Three Gorges University Graduate Scientific Research Innovation Project
文摘4-ary pulse amplitude modulation(4PAM) signals with 33% and 50% return-to-zero(RZ) clocks are generated for passive optical network(PON). We demonstrate that RZ-4PAM signals with duty cycles of 33% and 50% after transmission over 20-km-long single mode fiber(SMF) at 10 Gbit/s can be directly detected by using one photo detector,and the original data can also be restored by one M-ary threshold detector and one 4PAM sequence decoder. The optical spectra of 33% and 50% RZ-4PAM signals are measured,and their eye-diagrams before and after transmission are also analyzed. Simulation results show that 33% and 50% RZ-4PAM downlink signals can be received effectively,and the received power values are-15.1 d Bm and-13.8 d Bm when the bit error rate(BER) is 10^(-6). Moreover,33% RZ-4PAM optical signals have better reception performance than 50% RZ-4PAM optical signals.
基金supported by the National Key Research and Development Program of China 2021YFB2900801the Young Elite Scientists Sponsorship Program of CIC 2021QNRC001+1 种基金National Natural Science Foundation of China NSFC,62201033,U22A2005the Foundation of the Beijing Engineering and Technology Center for Convergence Networks and Ubiquitous Services.
文摘This paper aimed to propose two algorithms,DA-M and RF-M,of reducing the impact of multipath interference(MPI)on intensity modulation direct detection(IM-DD)systems,particularly for four-level pulse amplitude modulation(PAM4)systems.DA-M reduced the fluctuation by averaging the signal in blocks,RF-M estimated MPI by subtracting the decision value of the corresponding block from the mean value of a signal block,and then generated interference-reduced samples by subtracting the interference signal from the product of the corresponding MPI estimate and then weighting factor.This paper firstly proposed to separate the signal before decision-making into multiple blocks,which significantly reduced the complexity of DA-M and RF-M.Simulation results showed that the MPI noise of 28 GBaud IMDD system under the linewidths of 1e5 Hz,1e6 Hz and 10e6 Hz can be effectively alleviated.
