As the emergence of various highbandwidth services and the requirements to support 5G/Wi-Fi 6 wireless networks,the next generation fixed networks,i.e.F5G,are expected to be realized in the 5G era.F5G is endowed with ...As the emergence of various highbandwidth services and the requirements to support 5G/Wi-Fi 6 wireless networks,the next generation fixed networks,i.e.F5G,are expected to be realized in the 5G era.F5G is endowed with new characteristics,including ultra-high bandwidth,all-optical connections and optimal service experience.With the prospect of optical-to-everywhere,optical technologies are used for mobile front-haul,mid-haul,and back-haul.Optical access networks would play an important role in F5G to support radio access network and fixed access network.Low-latency PON is a key for cost effective-haul traffic aggregation.In terms of signal transmission,intensity modulation directdetection(IM-DD)is a promising scheme due to its simple architecture.The fundamental challenge associated with direct-detection is the disappearance of the transmitted signal’s phase.In access network,the flexibility and low latency are the two key factors affecting service experience.In this article,we review the evolution of PONs and the challenges of current PONs in detail.We analyze key enabling digital signal processing(DSP)techniques,including detection linearization for direct-detection and simplified coherent detection,adaptive equalizers,digital filer enabled flexible access network and low-latency inter-ONU communications.Finally,we discuss the developing trends of future optical access networks.展开更多
Dear Editor,Gastric cancer(GC)is among the most prevalent gastrointestinal malignancies.The occurrence of local deep infiltration or distant metastasis in GC is commonly associated with weak treatment and poor prognos...Dear Editor,Gastric cancer(GC)is among the most prevalent gastrointestinal malignancies.The occurrence of local deep infiltration or distant metastasis in GC is commonly associated with weak treatment and poor prognosis.1 Although,N4-Acetylcytidine(ac4C)represents one of the extensive chemical modifications in mRNAs that plays a pivotal role in modulating mRNA stability and the mRNA translation process(Fig.1b).展开更多
Intermittent dynamics switching on the route to chaos in a discrete-mode laser with long time-delayed feedback is experimentally and numerically studied by analyzing the time series,power spectra,and phase portraits. ...Intermittent dynamics switching on the route to chaos in a discrete-mode laser with long time-delayed feedback is experimentally and numerically studied by analyzing the time series,power spectra,and phase portraits. The results show two types of dynamics switching:one or multiple times regular intermittent dynamics switching between stable state and square-wave envelope period-one oscillation within one feedback round time,and the irregular intermittent dynamics switching between stable state and quasi-periodic or multi-states or chaos with higher feedback ratio and bias currents. The relationship between the duty cycle of period-one oscillation and the feedback ratio has been analyzed. The map of the dynamics distribution in the parameter space of feedback ratio and bias current is plotted for a better understanding of dynamics evolution in long external cavity discrete-mode lasers.展开更多
基金National Science Foundation of China(NSFC)(61871082 and 62111530150)Fundamental Research Funds for the Central Universities(ZYGX2020ZB043 and ZYGX2019J008).
文摘As the emergence of various highbandwidth services and the requirements to support 5G/Wi-Fi 6 wireless networks,the next generation fixed networks,i.e.F5G,are expected to be realized in the 5G era.F5G is endowed with new characteristics,including ultra-high bandwidth,all-optical connections and optimal service experience.With the prospect of optical-to-everywhere,optical technologies are used for mobile front-haul,mid-haul,and back-haul.Optical access networks would play an important role in F5G to support radio access network and fixed access network.Low-latency PON is a key for cost effective-haul traffic aggregation.In terms of signal transmission,intensity modulation directdetection(IM-DD)is a promising scheme due to its simple architecture.The fundamental challenge associated with direct-detection is the disappearance of the transmitted signal’s phase.In access network,the flexibility and low latency are the two key factors affecting service experience.In this article,we review the evolution of PONs and the challenges of current PONs in detail.We analyze key enabling digital signal processing(DSP)techniques,including detection linearization for direct-detection and simplified coherent detection,adaptive equalizers,digital filer enabled flexible access network and low-latency inter-ONU communications.Finally,we discuss the developing trends of future optical access networks.
基金the National Natural Science Foundation of China(Grant no.81960273)Gansu Natural Science Foundation(No.18JR3RA343)+4 种基金Gansu Fund project for Distinguished Young Scholars(No.18JR3RA262)the Key Projects of Department of Science and Technology in Gansu Province,China(No.1602FKDA001)the Science and Technology Innovation and Development Special Funding of Gansu province,China(G.F.R[2018]No.32)the Science and Technology Bureau 2018 Fund of the Chengguan District(2018KJGG0037)National Key Research and Development Program of China(No.2017FYA0205302).
文摘Dear Editor,Gastric cancer(GC)is among the most prevalent gastrointestinal malignancies.The occurrence of local deep infiltration or distant metastasis in GC is commonly associated with weak treatment and poor prognosis.1 Although,N4-Acetylcytidine(ac4C)represents one of the extensive chemical modifications in mRNAs that plays a pivotal role in modulating mRNA stability and the mRNA translation process(Fig.1b).
基金European Regional Development Fund (2017/COL/007,82085)。
文摘Intermittent dynamics switching on the route to chaos in a discrete-mode laser with long time-delayed feedback is experimentally and numerically studied by analyzing the time series,power spectra,and phase portraits. The results show two types of dynamics switching:one or multiple times regular intermittent dynamics switching between stable state and square-wave envelope period-one oscillation within one feedback round time,and the irregular intermittent dynamics switching between stable state and quasi-periodic or multi-states or chaos with higher feedback ratio and bias currents. The relationship between the duty cycle of period-one oscillation and the feedback ratio has been analyzed. The map of the dynamics distribution in the parameter space of feedback ratio and bias current is plotted for a better understanding of dynamics evolution in long external cavity discrete-mode lasers.