Multiple quantum well(MQW) Ⅲ-nitride diodes that can simultaneously emit and detect light feature an overlapping region between their electroluminescence and responsivity spectra, which allows them to be simultaneous...Multiple quantum well(MQW) Ⅲ-nitride diodes that can simultaneously emit and detect light feature an overlapping region between their electroluminescence and responsivity spectra, which allows them to be simultaneously used as both a transmitter and a receiver in a wireless light communication system. Here, we demonstrate a mobile light communication system using a time-division multiplexing(TDM) scheme to achieve bidirectional data transmission via the same optical channel.Two identical blue MQW diodes are defined by software as a transmitter or a receiver. To address the light alignment issue, an image identification module integrated with a gimbal stabilizer is used to automatically detect the locations of moving targets;thus, underwater audio communication is realized via a mobile blue-light TDM communication mode. This approach not only uses a single link but also integrates mobile nodes in a practical network.展开更多
Overlapped time domain multiplexing(OvTDM)is an innovative encoding scheme that can obtain high spectral efficiency.However,the intentional inter-symbol interference(ISI)caused by OvTDM will make the decoding process ...Overlapped time domain multiplexing(OvTDM)is an innovative encoding scheme that can obtain high spectral efficiency.However,the intentional inter-symbol interference(ISI)caused by OvTDM will make the decoding process more complex.The computational complexity of maximum likelihood sequence detection increases exponentially with the growth of spectral efficiency in OvTDM.As a consequence of high complexity,the decoding effort for a given spectral efficiency may occasionally exceed the physical limitations of the decoder,leading inevitably to buffer overflows and information erasures.In this paper,we propose a bidirectional Viterbi algorithm(BVA)based on the bidirectional sequence decoding for OvTDM.With the BVA,the decoding operation starts simultaneously from the both ends of the corresponding trellis and stops at the middle of trellis.The simulation results show that compared with Viterbi algorithm(VA),the decoding time of BVA can be reduced by about half.And the memory space of two decoders in BVA are about half of that in VA,which means that the BVA has lower memory requirements for decoder.And the decoding performance of BVA is almost the same as VA.展开更多
In an experiment on the round-trip fiber transfer of joint frequency and time signals based on wavelengthdivision multiplexing technology, a specific bidirectional erbium-doped fiber amplifier(Bi-EDFA) with low noise ...In an experiment on the round-trip fiber transfer of joint frequency and time signals based on wavelengthdivision multiplexing technology, a specific bidirectional erbium-doped fiber amplifier(Bi-EDFA) with low noise and high symmetry simultaneously is designed and applied to compensate for the loss of the link. The Allan deviation(ADEV) deterioration of the 1 GHz frequency signal induced by the Bi-EDFA is only 8 × 10-15 at 1 s and 9 × 10-18 at 104s in the forward direction, and is 1.7 × 10-14 at 1 s and 1.2 × 10-17 at 104s in the backward direction. The degraded time deviation(TDEV) caused by the asymmetry of the Bi-EDFA is only 0.8 ps at an average time of 103 s. With the proposed Bi-EDFA, in the field experiment on the 110 km fiber transfer of joint frequency and time signals, the ADEV of the 1 GHz frequency signal is 7.3 × 10-14at1 s and 2.5 × 10-17 at 104s. The TDEV of the 1 pulse per second time signal is 6.8 ps with an average time of 103 s.展开更多
Emerging applications widely use field-programmable gate array(FPGA)prototypes as a tool to verify modern very-large-scale integration(VLSI)circuits,imposing many problems,including routing failure caused by the limit...Emerging applications widely use field-programmable gate array(FPGA)prototypes as a tool to verify modern very-large-scale integration(VLSI)circuits,imposing many problems,including routing failure caused by the limited number of connections among blocks of FPGAs therein.Such a shortage of connections can be alleviated through time-division multiplexing(TDM),by which multiple signals sharing an identical routing channel can be transmitted.In this context,the routing quality dominantly decides the performance of such systems,proposing the requirement of minimizing the signal delay between FPGA pairs.This paper proposes algorithms for the routing problem in a multi-FPGA system with TDM support,aiming to minimize the maximum TDM ratio.The algorithm consists of two major stages:(1)A method is proposed to set the weight of an edge according to how many times it is shared by the routing requirements and consequently to compute a set of approximate minimum Steiner trees.(2)A ratio assignment method based on the edge-demand framework is devised for assigning ratios to the edges respecting the TDM ratio constraints.Experiments were conducted against the public benchmarks to evaluate our proposed approach as compared with all published works,and the results manifest that our method achieves a better TDM ratio in comparison.展开更多
This paper is focused on the multiuser implementation of fusion of radar and communication(RadCom)in internet-of-vehicles(IoV)scenarios.Traditional time-division multiple access(TDMA)technology degrades the velocity d...This paper is focused on the multiuser implementation of fusion of radar and communication(RadCom)in internet-of-vehicles(IoV)scenarios.Traditional time-division multiple access(TDMA)technology degrades the velocity detection performance of orthogonal frequency-division multiplexing(OFDM)-based RadCom systems.We propose a new TDMA approach for OFDM-based RadCom systems,where multiuser communication and radar detection are completed synchronously.We consider a continuous-wave TDMA OFDM structure in which random user data or Zadoff-Chu(ZC)sequences are transmitted in one symbol duration to ensure detection performance.As an application of interference cancellation method,user data demodulation and environment sensing can be simultaneously accomplished by our proposed approach.We carry out numerical evaluation and show wireless communication and radar detection performance over the continuous-wave TDMA OFDM-based RadCom approach.展开更多
A time division multiplexing of 106 weak fibers Bragg gratings （FBGs） based on a ring resonant-cavity is demonstrated. A semiconductor optical amplifier is connected in the cavity to function as an amplifier as well...A time division multiplexing of 106 weak fibers Bragg gratings （FBGs） based on a ring resonant-cavity is demonstrated. A semiconductor optical amplifier is connected in the cavity to function as an amplifier as well as a switch. The 106 weak FBGs are written along a SMF-28 fiber in serial with peak reflectivity of about -30 dB and equal separations of 5 m. The crosstalk and spectral distortion are investigated through both theoretical analysis and experiments.展开更多
A 10 Gbit/s 16-km-long reconfigurable wavelength-division-multiplexing passive optical network(WDM-PON) is presented empowered by a low-cost multi-channel directly modulated laser(DML) module. Compared with the case u...A 10 Gbit/s 16-km-long reconfigurable wavelength-division-multiplexing passive optical network(WDM-PON) is presented empowered by a low-cost multi-channel directly modulated laser(DML) module. Compared with the case using discrete devices in conventional scheme, the proposed DML module provides a cost-effective solution with reduced complexity. The clear eye diagram and the bit error rate(BER) of less than 2×10^(-7) with a sensitivity of-7 dB m are obtained. Due to the special packaging design, the crosstalk between channels under condition of simultaneous operation can be negligible.展开更多
Traditional intensity modulated two-level electrical time-division multiplexing （ETDM） transmission systems working at 100 -112 Gbit/s were investigated. The complete ETDM systems based on monolithically integrated ...Traditional intensity modulated two-level electrical time-division multiplexing （ETDM） transmission systems working at 100 -112 Gbit/s were investigated. The complete ETDM systems based on monolithically integrated transmitter and receiver modules were demonstrated with biterror-rate （BER） performance of 10-s at 107 Gbit/s, and near error-free standard forward error correction （FEC） threshold （2 × 10 -3） at 112 Gbit/s. The experiment results showed that directly modulated high-speed ETDM transmission systems with the symbol rates at 100 Gbaud and beyond were promising candidate for cost-effective 100 GbE applications and might be a preform of the next generation of Terabit/s Ethernet.展开更多
基金jointly supported by the National Natural Science Foundation of China (U21A20495)Natural Science Foundation of Jiangsu Province (BG2024023)+1 种基金National Key Research and Development Program of China (2022YFE0112000)111 Project (D17018)。
文摘Multiple quantum well(MQW) Ⅲ-nitride diodes that can simultaneously emit and detect light feature an overlapping region between their electroluminescence and responsivity spectra, which allows them to be simultaneously used as both a transmitter and a receiver in a wireless light communication system. Here, we demonstrate a mobile light communication system using a time-division multiplexing(TDM) scheme to achieve bidirectional data transmission via the same optical channel.Two identical blue MQW diodes are defined by software as a transmitter or a receiver. To address the light alignment issue, an image identification module integrated with a gimbal stabilizer is used to automatically detect the locations of moving targets;thus, underwater audio communication is realized via a mobile blue-light TDM communication mode. This approach not only uses a single link but also integrates mobile nodes in a practical network.
文摘Overlapped time domain multiplexing(OvTDM)is an innovative encoding scheme that can obtain high spectral efficiency.However,the intentional inter-symbol interference(ISI)caused by OvTDM will make the decoding process more complex.The computational complexity of maximum likelihood sequence detection increases exponentially with the growth of spectral efficiency in OvTDM.As a consequence of high complexity,the decoding effort for a given spectral efficiency may occasionally exceed the physical limitations of the decoder,leading inevitably to buffer overflows and information erasures.In this paper,we propose a bidirectional Viterbi algorithm(BVA)based on the bidirectional sequence decoding for OvTDM.With the BVA,the decoding operation starts simultaneously from the both ends of the corresponding trellis and stops at the middle of trellis.The simulation results show that compared with Viterbi algorithm(VA),the decoding time of BVA can be reduced by about half.And the memory space of two decoders in BVA are about half of that in VA,which means that the BVA has lower memory requirements for decoder.And the decoding performance of BVA is almost the same as VA.
基金supported in part by the National Natural Science Foundation of China under Grant No.61405227
文摘In an experiment on the round-trip fiber transfer of joint frequency and time signals based on wavelengthdivision multiplexing technology, a specific bidirectional erbium-doped fiber amplifier(Bi-EDFA) with low noise and high symmetry simultaneously is designed and applied to compensate for the loss of the link. The Allan deviation(ADEV) deterioration of the 1 GHz frequency signal induced by the Bi-EDFA is only 8 × 10-15 at 1 s and 9 × 10-18 at 104s in the forward direction, and is 1.7 × 10-14 at 1 s and 1.2 × 10-17 at 104s in the backward direction. The degraded time deviation(TDEV) caused by the asymmetry of the Bi-EDFA is only 0.8 ps at an average time of 103 s. With the proposed Bi-EDFA, in the field experiment on the 110 km fiber transfer of joint frequency and time signals, the ADEV of the 1 GHz frequency signal is 7.3 × 10-14at1 s and 2.5 × 10-17 at 104s. The TDEV of the 1 pulse per second time signal is 6.8 ps with an average time of 103 s.
基金supported by the Natural Science Foundation of Fujian Province(No.2020J01845)the National Natural Science Foundation of China(Nos.61772005 and 11871280)+1 种基金the Outstanding Youth Innovation Team Project for Universities of Shandong Province(No.2020KJN008)Qinglan Project.
文摘Emerging applications widely use field-programmable gate array(FPGA)prototypes as a tool to verify modern very-large-scale integration(VLSI)circuits,imposing many problems,including routing failure caused by the limited number of connections among blocks of FPGAs therein.Such a shortage of connections can be alleviated through time-division multiplexing(TDM),by which multiple signals sharing an identical routing channel can be transmitted.In this context,the routing quality dominantly decides the performance of such systems,proposing the requirement of minimizing the signal delay between FPGA pairs.This paper proposes algorithms for the routing problem in a multi-FPGA system with TDM support,aiming to minimize the maximum TDM ratio.The algorithm consists of two major stages:(1)A method is proposed to set the weight of an edge according to how many times it is shared by the routing requirements and consequently to compute a set of approximate minimum Steiner trees.(2)A ratio assignment method based on the edge-demand framework is devised for assigning ratios to the edges respecting the TDM ratio constraints.Experiments were conducted against the public benchmarks to evaluate our proposed approach as compared with all published works,and the results manifest that our method achieves a better TDM ratio in comparison.
基金supported in part by the National Natural Science Foundation of China(No.61971092,No.62222121)in part by the Sichuan Province Foundation for Distinguished Young Scholars(2020JDJQ0023)in part by the Fundamental Research Funds for the Central Universities(ZYGX2020ZB045,ZYGX2019J123).
文摘This paper is focused on the multiuser implementation of fusion of radar and communication(RadCom)in internet-of-vehicles(IoV)scenarios.Traditional time-division multiple access(TDMA)technology degrades the velocity detection performance of orthogonal frequency-division multiplexing(OFDM)-based RadCom systems.We propose a new TDMA approach for OFDM-based RadCom systems,where multiuser communication and radar detection are completed synchronously.We consider a continuous-wave TDMA OFDM structure in which random user data or Zadoff-Chu(ZC)sequences are transmitted in one symbol duration to ensure detection performance.As an application of interference cancellation method,user data demodulation and environment sensing can be simultaneously accomplished by our proposed approach.We carry out numerical evaluation and show wireless communication and radar detection performance over the continuous-wave TDMA OFDM-based RadCom approach.
基金This work was supported in part by the National Science Foundation of China, NSFC （Grant No. 61205070）, and the Key Technology R＆D Program of Hubei Province of China （Grant No. 2014BEC059）.
文摘A time division multiplexing of 106 weak fibers Bragg gratings （FBGs） based on a ring resonant-cavity is demonstrated. A semiconductor optical amplifier is connected in the cavity to function as an amplifier as well as a switch. The 106 weak FBGs are written along a SMF-28 fiber in serial with peak reflectivity of about -30 dB and equal separations of 5 m. The crosstalk and spectral distortion are investigated through both theoretical analysis and experiments.
基金supported by the National High-Tech Research and Development Program of China(No.2013AA014201)the National Natural Science Foundation of China(Nos.61575186 and 61635001)
文摘A 10 Gbit/s 16-km-long reconfigurable wavelength-division-multiplexing passive optical network(WDM-PON) is presented empowered by a low-cost multi-channel directly modulated laser(DML) module. Compared with the case using discrete devices in conventional scheme, the proposed DML module provides a cost-effective solution with reduced complexity. The clear eye diagram and the bit error rate(BER) of less than 2×10^(-7) with a sensitivity of-7 dB m are obtained. Due to the special packaging design, the crosstalk between channels under condition of simultaneous operation can be negligible.
基金Supported by the European Committee6th Research Framework Program in the Project HECTO
文摘Traditional intensity modulated two-level electrical time-division multiplexing （ETDM） transmission systems working at 100 -112 Gbit/s were investigated. The complete ETDM systems based on monolithically integrated transmitter and receiver modules were demonstrated with biterror-rate （BER） performance of 10-s at 107 Gbit/s, and near error-free standard forward error correction （FEC） threshold （2 × 10 -3） at 112 Gbit/s. The experiment results showed that directly modulated high-speed ETDM transmission systems with the symbol rates at 100 Gbaud and beyond were promising candidate for cost-effective 100 GbE applications and might be a preform of the next generation of Terabit/s Ethernet.
