This paper has proposed an experimental system for non-orthogonal multiple access(NOMA)wireless optical communication in challenging underwater turbulent environments,employing the gallium nitride(GaN)-based micro-LED...This paper has proposed an experimental system for non-orthogonal multiple access(NOMA)wireless optical communication in challenging underwater turbulent environments,employing the gallium nitride(GaN)-based micro-LED array.This design of the GaN-based micro-LED array enables the independent transmission of signals from distinct data streams within the NOMA framework,facilitating direct optical power-domain superposition of NOMA signals.The experimental setup involves emulating oceanic turbulence channels,characterized by varying the level of scintillation intensity,to thoroughly investigate the bit error rate(BER)performance.The outcomes unequivocally demonstrate the superiority of our proposed NOMA scheme,as compared to conventional circuit-driven optical NOMA systems utilizing fixed LED array grouping,particularly in the presence of turbulent underwater channels.The proposed NOMA scheme exhibits consistently superior BER performance and maintains excellent linearity at the lower frequencies while effectively mitigating signal distortion at the higher frequencies.展开更多
Channel assignment has emerged as an essential study subject in Cognitive Radio-basedWireless Mesh Networks(CR-WMN).In an era of alarming increase in Multi-Radio Multi-Channel(MRMC)network expansion interference is de...Channel assignment has emerged as an essential study subject in Cognitive Radio-basedWireless Mesh Networks(CR-WMN).In an era of alarming increase in Multi-Radio Multi-Channel(MRMC)network expansion interference is decreased and network throughput is significantly increased when non-overlapping or partially overlapping channels are correctly integrated.Because of its ad hoc behavior,dynamic channel assignment outperforms static channel assignment.Interference reduces network throughput in the CR-WMN.As a result,there is an extensive research gap for an algorithm that dynamically distributes channels while accounting for all types of interference.This work presents a method for dynamic channel allocations using unsupervisedMachine Learning(ML)that considers both coordinated and uncoordinated interference.Unsupervised machine learning uses coordinated and non-coordinated interference for dynamic channel allocation.To determine the applicability of the proposed strategy in reducing channel interference while increasingWMNthroughput,a comparison analysis was performed.When the simulation results of our proposed algorithm are compared to those of the Routing Channel Assignment(RCA)algorithm,the throughput of our proposed algorithm has increased by 34%compared to both coordinated and non-coordinated interferences.展开更多
We address the problem of adaptive modulation and coding scheme(AMCS) for a multi-input multioutput(MIMO) system in presence of time-varying transmitting correlation.Antenna subset selection and quasiorthogonal space-...We address the problem of adaptive modulation and coding scheme(AMCS) for a multi-input multioutput(MIMO) system in presence of time-varying transmitting correlation.Antenna subset selection and quasiorthogonal space-time block code(QOSTBC) have different error performances with different signal-to-noise ratios(SNRs) and in different spatial correlation scenarios.The error performance can be improved by selecting an appropriate transmission scheme to adapt to various channel conditions.The maximum distance criterion is the simplest and very effective algorithm for the antenna subset selection without needs of complex calculation and channel state information at transmitter(CSIT).The minimum error performance criteria and the simplified linear decision strategy are developed for constant transmission rate traffic to select the optimal transmission scheme.It can dramatically decrease algorithm complexity for obtaining error probability according to the known quantities comparing with using instant CSIT.Simulation results show that,remarkable performances including low SNR and weak spatial correlation at the expense of simple calculation and almost no bandwidth loss by adopting AMCS can be achieved.The proposed AMCS improves robustness of slowly varying spatial correlated channels.展开更多
A new blind frequency offset estimation method based on cyclic prefix and virtual subcarriers in coherent optical orthogonal frequency division multiplexing （CO-OFDM） system is presented. It is able to estimate the ...A new blind frequency offset estimation method based on cyclic prefix and virtual subcarriers in coherent optical orthogonal frequency division multiplexing （CO-OFDM） system is presented. It is able to estimate the fractional part and integral part of frequency offset at the same time. Its estimation range is about [-3.5 GHz, 3.5 GHz]. The influence of the integral frequency offset is comprehensively analyzed in COOFDM system. Its performances in the additive white Gaussian noise （AWGN） channel and the dispersive channel are investigated, respectively. Simulation results indicate that even in the dispersive channel, when the optical signal-to-noise ratio （OSNR） is low, it can still work very well.展开更多
This paper presents a theoretical comparison of a single carrier system and a multi-carrier system through an analysis of the achievable rate under frequency selective fading with channel state information at the rece...This paper presents a theoretical comparison of a single carrier system and a multi-carrier system through an analysis of the achievable rate under frequency selective fading with channel state information at the receiver. A scheme was designed to compare the achievable rates of a single carrier system and an Or- thogonal Frequency Division Multiplexing （OFDM） system. A thorough theoretical analysis of the two-path channel was conducted, and simulations were also used to analyze practical stochastic channels. Analysis and simulation results show that the achievable rates of the two approaches are comparable when the channel is flat fading. However, when the channel is frequency selective fading, the single carrier system outperforms the OFDM system. The achievable rate of the OFDM system is about 10% lower than that of the single carrier system at higher SNRs.展开更多
基金supported by the National Natural Science Foundation of China(NSFC)(No.61871418)。
文摘This paper has proposed an experimental system for non-orthogonal multiple access(NOMA)wireless optical communication in challenging underwater turbulent environments,employing the gallium nitride(GaN)-based micro-LED array.This design of the GaN-based micro-LED array enables the independent transmission of signals from distinct data streams within the NOMA framework,facilitating direct optical power-domain superposition of NOMA signals.The experimental setup involves emulating oceanic turbulence channels,characterized by varying the level of scintillation intensity,to thoroughly investigate the bit error rate(BER)performance.The outcomes unequivocally demonstrate the superiority of our proposed NOMA scheme,as compared to conventional circuit-driven optical NOMA systems utilizing fixed LED array grouping,particularly in the presence of turbulent underwater channels.The proposed NOMA scheme exhibits consistently superior BER performance and maintains excellent linearity at the lower frequencies while effectively mitigating signal distortion at the higher frequencies.
基金funded by the National Natural Science Foundation of China(61971014),Zhang Jianbiao.
文摘Channel assignment has emerged as an essential study subject in Cognitive Radio-basedWireless Mesh Networks(CR-WMN).In an era of alarming increase in Multi-Radio Multi-Channel(MRMC)network expansion interference is decreased and network throughput is significantly increased when non-overlapping or partially overlapping channels are correctly integrated.Because of its ad hoc behavior,dynamic channel assignment outperforms static channel assignment.Interference reduces network throughput in the CR-WMN.As a result,there is an extensive research gap for an algorithm that dynamically distributes channels while accounting for all types of interference.This work presents a method for dynamic channel allocations using unsupervisedMachine Learning(ML)that considers both coordinated and uncoordinated interference.Unsupervised machine learning uses coordinated and non-coordinated interference for dynamic channel allocation.To determine the applicability of the proposed strategy in reducing channel interference while increasingWMNthroughput,a comparison analysis was performed.When the simulation results of our proposed algorithm are compared to those of the Routing Channel Assignment(RCA)algorithm,the throughput of our proposed algorithm has increased by 34%compared to both coordinated and non-coordinated interferences.
基金the Chinese Scholarship Council for the financial support
文摘We address the problem of adaptive modulation and coding scheme(AMCS) for a multi-input multioutput(MIMO) system in presence of time-varying transmitting correlation.Antenna subset selection and quasiorthogonal space-time block code(QOSTBC) have different error performances with different signal-to-noise ratios(SNRs) and in different spatial correlation scenarios.The error performance can be improved by selecting an appropriate transmission scheme to adapt to various channel conditions.The maximum distance criterion is the simplest and very effective algorithm for the antenna subset selection without needs of complex calculation and channel state information at transmitter(CSIT).The minimum error performance criteria and the simplified linear decision strategy are developed for constant transmission rate traffic to select the optimal transmission scheme.It can dramatically decrease algorithm complexity for obtaining error probability according to the known quantities comparing with using instant CSIT.Simulation results show that,remarkable performances including low SNR and weak spatial correlation at the expense of simple calculation and almost no bandwidth loss by adopting AMCS can be achieved.The proposed AMCS improves robustness of slowly varying spatial correlated channels.
基金supported in part by the National Natural Science Foundation of China (No. 60932004)the National "863" Program of China (Nos. 2009AA01Z256,2009AA01Z253, and 2009AA01A345)the National"973" Program of China (No. 2007CB310705).
文摘A new blind frequency offset estimation method based on cyclic prefix and virtual subcarriers in coherent optical orthogonal frequency division multiplexing （CO-OFDM） system is presented. It is able to estimate the fractional part and integral part of frequency offset at the same time. Its estimation range is about [-3.5 GHz, 3.5 GHz]. The influence of the integral frequency offset is comprehensively analyzed in COOFDM system. Its performances in the additive white Gaussian noise （AWGN） channel and the dispersive channel are investigated, respectively. Simulation results indicate that even in the dispersive channel, when the optical signal-to-noise ratio （OSNR） is low, it can still work very well.
基金Supported by the National Key Technology Research and Devel-opment Program (No. 2009ZX03006-007-02)the National Natural Science Foundation of China (Nos. 60972019, 61021001,and 60928001)
文摘This paper presents a theoretical comparison of a single carrier system and a multi-carrier system through an analysis of the achievable rate under frequency selective fading with channel state information at the receiver. A scheme was designed to compare the achievable rates of a single carrier system and an Or- thogonal Frequency Division Multiplexing （OFDM） system. A thorough theoretical analysis of the two-path channel was conducted, and simulations were also used to analyze practical stochastic channels. Analysis and simulation results show that the achievable rates of the two approaches are comparable when the channel is flat fading. However, when the channel is frequency selective fading, the single carrier system outperforms the OFDM system. The achievable rate of the OFDM system is about 10% lower than that of the single carrier system at higher SNRs.
