In this paper,we investigate the performance of commensal ambient backscatter communications(AmBC)that ride on a non-ortho go nal multiple access(NOMA)downlink transmission,in which a backscatter device(BD)splits part...In this paper,we investigate the performance of commensal ambient backscatter communications(AmBC)that ride on a non-ortho go nal multiple access(NOMA)downlink transmission,in which a backscatter device(BD)splits part of its received signals from the base station(BS)for energy harvesting,and backscatters the remaining received signals to transmit information to a cellular user.Specifically,under the power consumption constraint at BD and the peak transmit power constraint at BS,we derive the optimal reflection coefficient at BD,the optimal total transmit power at BS,and the optimal power allocation at BS for each transmission block to maximize the ergodic capacity of the ambient backscatter transmission on the premise of preserving the outage performance of the NOMA downlink transmission.Furthermore,we consider a scenario where the BS is restricted by a maximum allowed average transmit power and the reflection coefficient at BD is fixed due to BD’s low-complexity nature.An algorithm is developed to determine the optimal total transmit power and power allocation at BS for this scenario.Also,a low-complexity algorithm is proposed for this scenario to reduce the computational complexity and the signaling overheads.Finally,the performance of the derived solutions are studied and compared via numerical simulations.展开更多
We demonstrate high-speed blue 4 ×4 micro-light-emitting-diode （LED） arrays with 14 light-emitting units （two light-emitting units are used as the positive and negative electrodes for power supply, respectivel...We demonstrate high-speed blue 4 ×4 micro-light-emitting-diode （LED） arrays with 14 light-emitting units （two light-emitting units are used as the positive and negative electrodes for power supply, respectively） comprising multiple quantum wells formed of GaN epitaxial layers grown on a sapphire substrate, and experimentally test their applicability for being used as VLC transmitters and illuminations. The micro-LED arrays provide a maximum -3-dB frequency response of 60.5 MHz with a smooth frequency curve from 1 MHz to 500 MHz for an optical output power of 165 mW at an injection current of 30 mA, which, to our knowledge, is the highest response frequency ever reported for blue GaN-based LEDs operating at that level of optical output power. The relationship between the frequency and size of the device single pixel diameter reveals the relationship between the response frequency and diffusion capacitance of the device.展开更多
There is a contradiction between high processing complexity and limited processing resources when turbo codes are used on the on-board processing(OBP)satellite platform.To solve this problem,this paper proposes a part...There is a contradiction between high processing complexity and limited processing resources when turbo codes are used on the on-board processing(OBP)satellite platform.To solve this problem,this paper proposes a partial iterative decode method for on-board application,in which satellite only carries out limited number of iteration according to the on-board processing resource limitation and the throughput capacity requirements.In this method,the soft information of parity bits,which is not obtained individually in conventional turbo decoder,is encoded and forwarded along with those of information bits.To save downlink transmit power,the soft information is limited and normalized before forwarding.The iteration number and limiter parameters are optimized with the help of EXIT chart and numerical analysis,respectively.Simulation results show that the proposed method can effectively decrease the complexity of onboard processing while achieve most of the decoding gain..展开更多
A mixture of polydimethylsiloxane (PDMS) doped with phosphor particles can be found across diverse industries having different applications. This mixture plays a particularly important role in the field of lighting, w...A mixture of polydimethylsiloxane (PDMS) doped with phosphor particles can be found across diverse industries having different applications. This mixture plays a particularly important role in the field of lighting, white light-emitting diodes (LED's), flexible display devices, anti-counterfeiting (AC) solutions, luminescence thermometers and many types of sensors. The field of mechanoluminescence and biomedical are booming and there is also potential for visible light communication (VLC). In this comprehensive review, the basic characteristics of PDMS and a list of selected phosphors suitable for creating a mixture of PDMS and phosphor are presented. The summary and a detailed overview of the implemented applications of this perspective mixture over the last decade is presented as well.展开更多
This paper proposes and simulates a novel all-optical error-bit amplitude monitor based on cross-gain modulation and four-wave mixing in cascaded semiconductor optical amplifiers （SOAs）, which function as logic NOT ...This paper proposes and simulates a novel all-optical error-bit amplitude monitor based on cross-gain modulation and four-wave mixing in cascaded semiconductor optical amplifiers （SOAs）, which function as logic NOT and logic AND, respectively. The proposed scheme is successfully simulated for 40 Gb/s return-to-zero （RZ） signal with different duty cycles. In the first stage, the SOA is followed by a detuning filter to accelerate the gain recovery as well as improve the extinction ratio. A clock probe signal is used to avoid the edge pulse-pairs in the output waveform. Among these RZ formats, 33% RZ format is preferred to obtain the largest eye opening. The normalized error amplitude, defined as error bit amplitude over the standard mark amplitude, has a dynamic range from 0.1 to 0.65 for all RZ formats. The simulations show small input power dynamic range because of the nonlinear gain variation in the first stage. This scheme is competent for nonreturn-to-zero format at 10Gb/s as well.展开更多
This paper presents a novel in-plane photonic crystal channel drop filter. The device is composed of a resonant cavity sandwiched by two parallel waveguides. The cavity has two resonant modes with opposite symmetries....This paper presents a novel in-plane photonic crystal channel drop filter. The device is composed of a resonant cavity sandwiched by two parallel waveguides. The cavity has two resonant modes with opposite symmetries. Tuning these two modes into degeneracy causes destructive interference in bus waveguide, which results in high forward drop efficiency at the resonant wavelength. From the result of numerical analysis by using two-dimensional finite-difference time-domain method, the channel drop filter has a drop efficiency of 96% and a Q value of over 3000, which can be used in dense wavelength division multiplexing systems.展开更多
All-optical digital logic elementary circuits are the building blocks of many important computational operations in future high-speed all-optical networks and computing systems. Multifunetional and reconfigurable logi...All-optical digital logic elementary circuits are the building blocks of many important computational operations in future high-speed all-optical networks and computing systems. Multifunetional and reconfigurable logic units are essential in this respect. Employing the demodulation properties of delay interferometers for input differential phase shift keying signals and the gain saturation effect in two parallel semiconductor optical amplifiers, a novel design of 40 Cbit/s reconfigurable all-optical dual-directional half-subtractor is proposed and demonstrated. All output logic results show that the scheme achieves over 11=dB extinction ratio, clear and wide open eye diagram, as well as low polarization dependence （〈 1 dB）, without using any additional input light beam. The scheme may provide a promising candidate for future ultrafast all-optical signal processing applications.展开更多
Wireless devicetodevice （D2D） communications sharing the spectrum of cellular networks is important for improving spec trum efficiency. Furthermore, introducing multicast and multi hop communications to D2D networks...Wireless devicetodevice （D2D） communications sharing the spectrum of cellular networks is important for improving spec trum efficiency. Furthermore, introducing multicast and multi hop communications to D2D networks can expand D2D ser vice functions. In this paper, we propose an anglebased inter ferenceaware routing algorithm for D2D multicast communica tions. This algorithm reuses the uplink cellular spectrum. Our proposed algorithm aims to reduce the outage probability and minimize the average hop count over all multicast destina tions （i.e., multicast receivers）, while limiting interference to cellular users to a tolerable level. In particular, our algorithm integrates two design principles for hopbyhop route selec tion. First, we minimize the distance ratio of the candidateto destination link to the candidatetobasestation link, such that the selected route advances closer to a subset of multi cast receivers. Second, we design the anglethreshold based merging strategy to divide multicast receivers into subsets with geographically close destinations. By applying the two principles for selection of each hop and further deriving an adaptive powerallocation strategy, the message can be more effieiently delivered to destinations with fewer branches when constructing the multicast tree. This means fewer duplicated data transmissions. Analyses and simulations are presented to show the impact of system parameters on the routing perfor mances. Simulation results also demonstrate the superiority of our algorithm over baseline schemes in terms of outage proba bility and average hop count.展开更多
基金supported in part by the National Key R&D Program of China under Grant 2018YFE0100500the National Natural Science Foundation of China under Grant 61871387,Grant 61861041,and Grant 61871471+2 种基金the Natural Science Basic Research Program of Shaanxi under Grant 2019JM-019Academy of Finland via:(a)ee-Io T project n.319009,(b)FIREMAN consortium CHIST-ERA/n.326270,and(c)Energy Net Research Fellowship n.321265/n.328869the NUDT Research Fund under Grant ZK17-03-08。
文摘In this paper,we investigate the performance of commensal ambient backscatter communications(AmBC)that ride on a non-ortho go nal multiple access(NOMA)downlink transmission,in which a backscatter device(BD)splits part of its received signals from the base station(BS)for energy harvesting,and backscatters the remaining received signals to transmit information to a cellular user.Specifically,under the power consumption constraint at BD and the peak transmit power constraint at BS,we derive the optimal reflection coefficient at BD,the optimal total transmit power at BS,and the optimal power allocation at BS for each transmission block to maximize the ergodic capacity of the ambient backscatter transmission on the premise of preserving the outage performance of the NOMA downlink transmission.Furthermore,we consider a scenario where the BS is restricted by a maximum allowed average transmit power and the reflection coefficient at BD is fixed due to BD’s low-complexity nature.An algorithm is developed to determine the optimal total transmit power and power allocation at BS for this scenario.Also,a low-complexity algorithm is proposed for this scenario to reduce the computational complexity and the signaling overheads.Finally,the performance of the derived solutions are studied and compared via numerical simulations.
基金supported by the Science and Technology Program Project for the Innovation of Forefront and Key Technology of Guangdong Province,China(Grant Nos.2014B010119004,2014B010121001,and 2013B010204065)the Institute of Science and Technology Collaborative Innovation Major Project of Guangzhou City,Guangdong Province,China(Grant No.201604010047)+1 种基金the Special Project for Key Science and Technology of Zhongshan City,Guangdong Province,China(Grant No.2014A2FC204)the Fund from the Huadu Science and Technology Bureau of Guangdong Province,China(Grant No.HD15PT003)
文摘We demonstrate high-speed blue 4 ×4 micro-light-emitting-diode （LED） arrays with 14 light-emitting units （two light-emitting units are used as the positive and negative electrodes for power supply, respectively） comprising multiple quantum wells formed of GaN epitaxial layers grown on a sapphire substrate, and experimentally test their applicability for being used as VLC transmitters and illuminations. The micro-LED arrays provide a maximum -3-dB frequency response of 60.5 MHz with a smooth frequency curve from 1 MHz to 500 MHz for an optical output power of 165 mW at an injection current of 30 mA, which, to our knowledge, is the highest response frequency ever reported for blue GaN-based LEDs operating at that level of optical output power. The relationship between the frequency and size of the device single pixel diameter reveals the relationship between the response frequency and diffusion capacitance of the device.
基金supported by National High Technology Research and Development Program(863 Program,2012AA01A502)National Natural Science Foundation of China (41206031)National Basic Research Program(2012CB316000)
文摘There is a contradiction between high processing complexity and limited processing resources when turbo codes are used on the on-board processing(OBP)satellite platform.To solve this problem,this paper proposes a partial iterative decode method for on-board application,in which satellite only carries out limited number of iteration according to the on-board processing resource limitation and the throughput capacity requirements.In this method,the soft information of parity bits,which is not obtained individually in conventional turbo decoder,is encoded and forwarded along with those of information bits.To save downlink transmit power,the soft information is limited and normalized before forwarding.The iteration number and limiter parameters are optimized with the help of EXIT chart and numerical analysis,respectively.Simulation results show that the proposed method can effectively decrease the complexity of onboard processing while achieve most of the decoding gain..
基金European Union under the REFRESH-Research Excellence For REgion Sustainability and High-tech Industries project number CZ.10.03.01/00/22003/0000048 via the Operational Programme Just TransitionMinistry of Education,Youth,and Sports of the Czech Republic con-ducted by the VSB-Technical University of Ostrava,under grant no.SP2024/081+1 种基金projects CI-CECO(LA/P/0006/2020,UIDB/50011/2020&UIDP/50011/2020)and Di-giAqua(PTDC/EEI-EEE/0415/2021)financed by national funds through the(Portuguese Science and Technology Foundation/MCTES(FCT I.P.)).
文摘A mixture of polydimethylsiloxane (PDMS) doped with phosphor particles can be found across diverse industries having different applications. This mixture plays a particularly important role in the field of lighting, white light-emitting diodes (LED's), flexible display devices, anti-counterfeiting (AC) solutions, luminescence thermometers and many types of sensors. The field of mechanoluminescence and biomedical are booming and there is also potential for visible light communication (VLC). In this comprehensive review, the basic characteristics of PDMS and a list of selected phosphors suitable for creating a mixture of PDMS and phosphor are presented. The summary and a detailed overview of the implemented applications of this perspective mixture over the last decade is presented as well.
基金Project partially supported by the National High Technology Developing Program of China (Grant No 2006AA03Z0414)the National Basic Research Program of China (Grant No 2006CB302805)+1 种基金the Science Fund for Distinguished Young Scholars of Hubei Province, China (Grant No 2006ABB017)the Program for New Century Excellent Talents in Ministry of Education of China (Grant No NCET-04-0715)
文摘This paper proposes and simulates a novel all-optical error-bit amplitude monitor based on cross-gain modulation and four-wave mixing in cascaded semiconductor optical amplifiers （SOAs）, which function as logic NOT and logic AND, respectively. The proposed scheme is successfully simulated for 40 Gb/s return-to-zero （RZ） signal with different duty cycles. In the first stage, the SOA is followed by a detuning filter to accelerate the gain recovery as well as improve the extinction ratio. A clock probe signal is used to avoid the edge pulse-pairs in the output waveform. Among these RZ formats, 33% RZ format is preferred to obtain the largest eye opening. The normalized error amplitude, defined as error bit amplitude over the standard mark amplitude, has a dynamic range from 0.1 to 0.65 for all RZ formats. The simulations show small input power dynamic range because of the nonlinear gain variation in the first stage. This scheme is competent for nonreturn-to-zero format at 10Gb/s as well.
基金Project supported by the National Natural Science Foundation of China (Grant Nos.10774195,U0834001,and 10974263)the Ministry of Education,China (Grant No.309024)+1 种基金the Program for New Century Excellent Talents in University,Chinathe National Basic Research Program of China (Grant No.2010CB923201)
文摘This paper presents a novel in-plane photonic crystal channel drop filter. The device is composed of a resonant cavity sandwiched by two parallel waveguides. The cavity has two resonant modes with opposite symmetries. Tuning these two modes into degeneracy causes destructive interference in bus waveguide, which results in high forward drop efficiency at the resonant wavelength. From the result of numerical analysis by using two-dimensional finite-difference time-domain method, the channel drop filter has a drop efficiency of 96% and a Q value of over 3000, which can be used in dense wavelength division multiplexing systems.
基金supported by the National Natural Science Foundation of China (Grant No.60877056)the National Basic Research Program of China (Grant No.2011CB301704)
文摘All-optical digital logic elementary circuits are the building blocks of many important computational operations in future high-speed all-optical networks and computing systems. Multifunetional and reconfigurable logic units are essential in this respect. Employing the demodulation properties of delay interferometers for input differential phase shift keying signals and the gain saturation effect in two parallel semiconductor optical amplifiers, a novel design of 40 Cbit/s reconfigurable all-optical dual-directional half-subtractor is proposed and demonstrated. All output logic results show that the scheme achieves over 11=dB extinction ratio, clear and wide open eye diagram, as well as low polarization dependence （〈 1 dB）, without using any additional input light beam. The scheme may provide a promising candidate for future ultrafast all-optical signal processing applications.
基金supported by National Natural Science Foundation of China under Grant No.61102078ZTE Industry-Academic-Research Cooperation Fundsthe Fundamental Research Funds for the Central Universities
文摘Wireless devicetodevice （D2D） communications sharing the spectrum of cellular networks is important for improving spec trum efficiency. Furthermore, introducing multicast and multi hop communications to D2D networks can expand D2D ser vice functions. In this paper, we propose an anglebased inter ferenceaware routing algorithm for D2D multicast communica tions. This algorithm reuses the uplink cellular spectrum. Our proposed algorithm aims to reduce the outage probability and minimize the average hop count over all multicast destina tions （i.e., multicast receivers）, while limiting interference to cellular users to a tolerable level. In particular, our algorithm integrates two design principles for hopbyhop route selec tion. First, we minimize the distance ratio of the candidateto destination link to the candidatetobasestation link, such that the selected route advances closer to a subset of multi cast receivers. Second, we design the anglethreshold based merging strategy to divide multicast receivers into subsets with geographically close destinations. By applying the two principles for selection of each hop and further deriving an adaptive powerallocation strategy, the message can be more effieiently delivered to destinations with fewer branches when constructing the multicast tree. This means fewer duplicated data transmissions. Analyses and simulations are presented to show the impact of system parameters on the routing perfor mances. Simulation results also demonstrate the superiority of our algorithm over baseline schemes in terms of outage proba bility and average hop count.
