Three novel designs of adaptively modulated optical orthogonal frequency division multiplexing modems using subcarrier modulation （AMOOFDM-SCM） are proposed, for the first time, each of which requires a single inver...Three novel designs of adaptively modulated optical orthogonal frequency division multiplexing modems using subcarrier modulation （AMOOFDM-SCM） are proposed, for the first time, each of which requires a single inverse fast Fourier transform/fast Fourier transform （IFFT/FFT） operation. These designs not only significantly simplify the AMOOFDM-SCM modem configurations, but also offer extra unique network features such as input/ output reconfigurability. Investigations show that these three modems are capable of supporting more than 60 Gb/s AMOOFDM-SCM signal transmission over 20, 40 and 60 km single mode fibre （SMF）-based intensity modulation and direct detection （IMDD） transmission links without optical amplification and chromatic dispersion compensation.展开更多
Subcarrier intensity modulation with direet detection is a modulatiou/detection technique tbr optical wireless communication systems, where a pre-modulated and properly biased radio frequency signal is modulated on th...Subcarrier intensity modulation with direet detection is a modulatiou/detection technique tbr optical wireless communication systems, where a pre-modulated and properly biased radio frequency signal is modulated on the intensity of the optical carrier. The most important benefits of subcarrier intensity modulation are as follows： 1） it does not provide irreducible error floor like the conventional on-off keying intensity modulation with a fixed detection threshold; 2） it provides improved spectral efficiency and supports higher order modulation schemes; and 3） it has much less implementation complexity compared to coherent optical wireless communications with heterodyne or homodyne detection. In this paper, we present an up-to-date review of subcarrier intensity modulated optical wireless communication systems. We survey the error rate and outage performance of subcarrier intensity modulations in the atmospheric turbulence channels considering different modulation and coding schemes. We also explore different contemporary atmospheric turbulence fading mitigation solutions that can be employed for subcarrier intensity modulation. These solutions include diversity combining, adaptive transmission, relay assisted transmission, multiple-subcarrier intensity modulations, and optical orthogonal frequency division multiplexing. Moreover, we review the performance of subcarrier intensity modulations due to the pointing error and synchronization error.展开更多
The scientific monitoring and reliable telecommunications(SMART)initiative,led by a joint task force including ITU,aims to integrate electronic sensors into undersea telecommunications cables for real-time and high-se...The scientific monitoring and reliable telecommunications(SMART)initiative,led by a joint task force including ITU,aims to integrate electronic sensors into undersea telecommunications cables for real-time and high-sensitivity subsea monitoring.The current integrated sensing and communication(ISAC)solution to the SMART application still relies on wavelength band multiplexing of sensing information via Ethernet switches,leading to optical communication bandwidth waste.To achieve the dense and low-interference ISAC for SMART network applications,we demonstrate the co-transmissions of coherent optical digital subcarrier modulation(DSCM)communication signals and temperature sensing information in the SMART system.Besides the co-transmission capability,the special design of the sensing transmission format is made to enable the compatible DSP with DSCM communications,which shares the same wavelength channel.Moreover,due to the different physical locations of the in-line sensing joints to the communication transceivers in the SMART system,it is hard to align the wavelength of the communication laser and the sensing one,which cannot ensure the precise allocation of sensing information into the frequency blanks of DSCM communication signals.To deal with these two issues,the sensing information at inline joints is proposed to be modulated in the manner of optical single-sideband(SSB)modulation and frequency modulation(FM),and then the precise allocation into the frequency blanks of DSCM communication signals can be realized,along with the full compatibility to demodulate the sensed temperature using the traditional frequency offset estimation in coherent DSP.Experiments on a two-span repeatered single-mode fiber link validate the integration of 20 GBaud optical DP-QAM16 transmissions and real-time temperature sensing at a sensing joint.Advanced communications are enabled by implementing space-time coding on DSCM communication signals,with 0.2 dB�factor improvement.As for the sensing functionality,the temperature sensing resolution at 0.0625°C,which reaches the limitation of the employed electronic thermometer DS18B20,has been obtained by using the communication-compatible DSP.We believe the proposed ISAC scheme along with the corresponding DSP flowchart makes sense for monitoring the subsea via the advanced SMART cables.展开更多
Subcarrier modulated signals are widely used in the new generation of Global Navigation Satellite Systems(GNSS)to improve spectral compatibility and ranging accuracy.The unique structure of subcarrier modulated signal...Subcarrier modulated signals are widely used in the new generation of Global Navigation Satellite Systems(GNSS)to improve spectral compatibility and ranging accuracy.The unique structure of subcarrier modulated signals poses an ambiguity threat to acquisition and tracking,rendering traditional GNSS signal processing algorithms unsuitable.Designing unambiguous acquisition and tracking as well as observation extraction techniques for subcarrier modulated signals that can realize the high ranging accuracy potential while avoiding the ambiguity threat is a topic of common interest in both academia and industry.Numerous studies have addressed the ambiguity elimination problem of subcarrier modulated signals.However,to the best of our knowledge,no updated reviews on this topic reflecting recent advances in the field have been presented in the past few years.On the one hand,the unique composite subcarrier modulated signal structure in the B1 and B2 bands of the BeiDou Navigation Satellite System(BDS)and the E5 band of the Galileo satellite navigation system(Galileo)has been gradually emphasized by academics.On the other hand,unambiguous processing methods for subcarrier modulated signals based on multidimensional tracking loops have flourished,which provides a new way to solve the ambiguity problem.An overview of the most representative subcarrier modulated signal processing techniques,focusing on the achievements made in the last decade,is presented in this article,which can be a starting point for the researchers who start their study in this area.Furthermore,we aim to present a complete review on the recent breakthroughs that have taken place within this research area,providing links to the most interesting and successful advances in this research field.Remaining challenges with prospects are also given.展开更多
文摘Three novel designs of adaptively modulated optical orthogonal frequency division multiplexing modems using subcarrier modulation （AMOOFDM-SCM） are proposed, for the first time, each of which requires a single inverse fast Fourier transform/fast Fourier transform （IFFT/FFT） operation. These designs not only significantly simplify the AMOOFDM-SCM modem configurations, but also offer extra unique network features such as input/ output reconfigurability. Investigations show that these three modems are capable of supporting more than 60 Gb/s AMOOFDM-SCM signal transmission over 20, 40 and 60 km single mode fibre （SMF）-based intensity modulation and direct detection （IMDD） transmission links without optical amplification and chromatic dispersion compensation.
文摘Subcarrier intensity modulation with direet detection is a modulatiou/detection technique tbr optical wireless communication systems, where a pre-modulated and properly biased radio frequency signal is modulated on the intensity of the optical carrier. The most important benefits of subcarrier intensity modulation are as follows： 1） it does not provide irreducible error floor like the conventional on-off keying intensity modulation with a fixed detection threshold; 2） it provides improved spectral efficiency and supports higher order modulation schemes; and 3） it has much less implementation complexity compared to coherent optical wireless communications with heterodyne or homodyne detection. In this paper, we present an up-to-date review of subcarrier intensity modulated optical wireless communication systems. We survey the error rate and outage performance of subcarrier intensity modulations in the atmospheric turbulence channels considering different modulation and coding schemes. We also explore different contemporary atmospheric turbulence fading mitigation solutions that can be employed for subcarrier intensity modulation. These solutions include diversity combining, adaptive transmission, relay assisted transmission, multiple-subcarrier intensity modulations, and optical orthogonal frequency division multiplexing. Moreover, we review the performance of subcarrier intensity modulations due to the pointing error and synchronization error.
基金National Natural Science Foundation of China(62475178)Yangtze River Delta Region Integration Project(2024CSJGG2600).
文摘The scientific monitoring and reliable telecommunications(SMART)initiative,led by a joint task force including ITU,aims to integrate electronic sensors into undersea telecommunications cables for real-time and high-sensitivity subsea monitoring.The current integrated sensing and communication(ISAC)solution to the SMART application still relies on wavelength band multiplexing of sensing information via Ethernet switches,leading to optical communication bandwidth waste.To achieve the dense and low-interference ISAC for SMART network applications,we demonstrate the co-transmissions of coherent optical digital subcarrier modulation(DSCM)communication signals and temperature sensing information in the SMART system.Besides the co-transmission capability,the special design of the sensing transmission format is made to enable the compatible DSP with DSCM communications,which shares the same wavelength channel.Moreover,due to the different physical locations of the in-line sensing joints to the communication transceivers in the SMART system,it is hard to align the wavelength of the communication laser and the sensing one,which cannot ensure the precise allocation of sensing information into the frequency blanks of DSCM communication signals.To deal with these two issues,the sensing information at inline joints is proposed to be modulated in the manner of optical single-sideband(SSB)modulation and frequency modulation(FM),and then the precise allocation into the frequency blanks of DSCM communication signals can be realized,along with the full compatibility to demodulate the sensed temperature using the traditional frequency offset estimation in coherent DSP.Experiments on a two-span repeatered single-mode fiber link validate the integration of 20 GBaud optical DP-QAM16 transmissions and real-time temperature sensing at a sensing joint.Advanced communications are enabled by implementing space-time coding on DSCM communication signals,with 0.2 dB�factor improvement.As for the sensing functionality,the temperature sensing resolution at 0.0625°C,which reaches the limitation of the employed electronic thermometer DS18B20,has been obtained by using the communication-compatible DSP.We believe the proposed ISAC scheme along with the corresponding DSP flowchart makes sense for monitoring the subsea via the advanced SMART cables.
基金supported by National Natural Science Foundation of China,under Grant No.42274018,and National Key Research and Development Program of China under Grant 2021YFA0716600。
文摘Subcarrier modulated signals are widely used in the new generation of Global Navigation Satellite Systems(GNSS)to improve spectral compatibility and ranging accuracy.The unique structure of subcarrier modulated signals poses an ambiguity threat to acquisition and tracking,rendering traditional GNSS signal processing algorithms unsuitable.Designing unambiguous acquisition and tracking as well as observation extraction techniques for subcarrier modulated signals that can realize the high ranging accuracy potential while avoiding the ambiguity threat is a topic of common interest in both academia and industry.Numerous studies have addressed the ambiguity elimination problem of subcarrier modulated signals.However,to the best of our knowledge,no updated reviews on this topic reflecting recent advances in the field have been presented in the past few years.On the one hand,the unique composite subcarrier modulated signal structure in the B1 and B2 bands of the BeiDou Navigation Satellite System(BDS)and the E5 band of the Galileo satellite navigation system(Galileo)has been gradually emphasized by academics.On the other hand,unambiguous processing methods for subcarrier modulated signals based on multidimensional tracking loops have flourished,which provides a new way to solve the ambiguity problem.An overview of the most representative subcarrier modulated signal processing techniques,focusing on the achievements made in the last decade,is presented in this article,which can be a starting point for the researchers who start their study in this area.Furthermore,we aim to present a complete review on the recent breakthroughs that have taken place within this research area,providing links to the most interesting and successful advances in this research field.Remaining challenges with prospects are also given.
