A SCMA ACO-OFDM downlink visible light communication(VLC)system is proposed.Six users share four spectrum resources,four of which are 4 primary color LED lights.ACO-OFDM technology is used to convert the user’s spars...A SCMA ACO-OFDM downlink visible light communication(VLC)system is proposed.Six users share four spectrum resources,four of which are 4 primary color LED lights.ACO-OFDM technology is used to convert the user’s sparse codebook mapped signal into a positive real value signal that can be carried on the light wave,which can realize high-speed parallel communication.Simulation verifies the feasibility of the system.At the same time,the channel model of visible light communication is constructed,and the signal-to-noise ratio(SNR)and channel gain of the visible light channel are systematically analyzed.Finally,the theoretical bit error rate formula using MPA decoding algorithm under different codebook constellation mapping points is given.Through simulation,it is verified that the theoretical bit error rate formula is basically consistent with the simulation bit error rate formula.展开更多
针对非对称限幅光正交频分复用(ACO-OFDM)的可见光通信系统中发光二极管引起的非线性失真问题,提出了一种选择性判决反馈均衡(s DFE)方法.该法设计了一个具有选择反馈均衡功能的模块,用线性信号来补偿非线性信号解决了ACO-OFDM的非线性...针对非对称限幅光正交频分复用(ACO-OFDM)的可见光通信系统中发光二极管引起的非线性失真问题,提出了一种选择性判决反馈均衡(s DFE)方法.该法设计了一个具有选择反馈均衡功能的模块,用线性信号来补偿非线性信号解决了ACO-OFDM的非线性失真,所产生的线性补偿信号可根据限幅边界范围进行选择性判决反馈,实现补偿ACO-OFDM信号频谱.仿真结果表明:在不同光功率条件下,该方法能够有效改善误码率性能,比特误码率可以达到1.37×10^(-4),恢复信号的频谱幅度可达38 d Bm.展开更多
Optical Wireless Communication(OWC)is a new trend in communication systems to achieve large bandwidth,high bit rate,high security,fast deployment,and low cost.The basic idea of the OWC is to transmit data on unguided ...Optical Wireless Communication(OWC)is a new trend in communication systems to achieve large bandwidth,high bit rate,high security,fast deployment,and low cost.The basic idea of the OWC is to transmit data on unguided media with light.This system requires multi-carrier modulation such as Orthogonal Frequency Division Multiplexing(OFDM).This paper studies optical OFDM performance based on Intensity Modulation with Direct Detection(IM/DD)system.This system requires a non-negativity constraint.The paper presents a framework for wireless optical OFDM system that comprises(IM/DD)with different forms,Direct Current biased Optical OFDM(DCO-OFDM),Asymmetrically Clipped Optical OFDM(ACO-OFDM),Asymmetrically DC-biased Optical OFDM(ADO-OFDM),and Flip-OFDM.It also considers channel coding as a tool for error control,channel equalization for reducing deterioration due to channel effects,and investigation of the turbulence effects.The evaluation results of the proposed framework reveal enhancement of performance.The performance of the IM/DD-OFDM system is investigated over different channel models such as AWGN,log-normal turbulence channel model,and ceiling bounce channel model.The simulation results show that the BER performance of the IM/DD-OFDM communication system is enhanced while the fading strength is decreased.The results reveal also that Hamming codes,BCH codes,and convolutional codes achieve better BER performance.Also,two algorithms of channel estimation and equalization are considered and compared.These algorithms include the Least Squares(LS)and the Minimum Mean Square Error(MMSE).The simulation results show that the MMSE algorithm gives better BER performance than the LS algorithm.展开更多
With the rapid developments of commercial demands,a majority of advanced researches have been investigated for the applications of underwater wireless sensor(WSN)networks.Recently optical communication has...With the rapid developments of commercial demands,a majority of advanced researches have been investigated for the applications of underwater wireless sensor(WSN)networks.Recently optical communication has been considered for underwater wireless sensor network.An experimental set-up for testing optical communication underwater has been provided and designed in present papers to maximize the energy coupled from these displacements to the transduction mechanism that converts the mechanical energy into electrical.The true case has been considered by measuring diffuse attenuation coefficients in different seas.One stand out potential optical communication method,Visible Light Communication(VLC)has been talked and several communication methods are compared from many points of view,for example attenuation in salt water.The evaluation of modulation techniques for underwater wireless optical communications has been displayed,and further how the data collection and storage with an underwater WSN is introduced.In this paper current researches for an(UWSN)based on optical communication are studied,in particular the potential VLC method and comparisons of VLC with other optical communication approaches.Underwater challenges would be analyzed by comparing a sort of communication methods,applied in underwater.Future work will be developed at last.展开更多
A PE-ACO-OFDM(Position-Encoded Asymmetrically Clipped Optical Orthogonal Frequency Division Multiplexing)signaling scheme for intensity modulation and direct detection is introduced in this paper,where the anti-asymme...A PE-ACO-OFDM(Position-Encoded Asymmetrically Clipped Optical Orthogonal Frequency Division Multiplexing)signaling scheme for intensity modulation and direct detection is introduced in this paper,where the anti-asymmetry characteristics of ACO-OFDM are exploited to improve the rate of data transmission.This is achieved by reducing the symbol duration of the ACO-OFDM signal,where only the first half of ACO-OFDM is used to transmit the ACO-OFDM data symbol after inverting its negative samples to positive ones.In addition,encoded ACO-OFDM samples are combined with every ACO-OFDM symbol to allow the receiver to identify the position of the inverted samples.Simulation results are introduced,and it is shown that the data rates of PE-ACO-OFDM improve by 33%compared with ACO-OFDM,when a 256-quadrature amplitude modulation scheme is considered as the encoded constellation order.It is also shown that the signal to noise ratio of the proposed PE-ACO-OFDM is higher by almost 1 dB compared with the traditional ACO-OFDM.展开更多
文摘A SCMA ACO-OFDM downlink visible light communication(VLC)system is proposed.Six users share four spectrum resources,four of which are 4 primary color LED lights.ACO-OFDM technology is used to convert the user’s sparse codebook mapped signal into a positive real value signal that can be carried on the light wave,which can realize high-speed parallel communication.Simulation verifies the feasibility of the system.At the same time,the channel model of visible light communication is constructed,and the signal-to-noise ratio(SNR)and channel gain of the visible light channel are systematically analyzed.Finally,the theoretical bit error rate formula using MPA decoding algorithm under different codebook constellation mapping points is given.Through simulation,it is verified that the theoretical bit error rate formula is basically consistent with the simulation bit error rate formula.
文摘针对非对称限幅光正交频分复用(ACO-OFDM)的可见光通信系统中发光二极管引起的非线性失真问题,提出了一种选择性判决反馈均衡(s DFE)方法.该法设计了一个具有选择反馈均衡功能的模块,用线性信号来补偿非线性信号解决了ACO-OFDM的非线性失真,所产生的线性补偿信号可根据限幅边界范围进行选择性判决反馈,实现补偿ACO-OFDM信号频谱.仿真结果表明:在不同光功率条件下,该方法能够有效改善误码率性能,比特误码率可以达到1.37×10^(-4),恢复信号的频谱幅度可达38 d Bm.
文摘Optical Wireless Communication(OWC)is a new trend in communication systems to achieve large bandwidth,high bit rate,high security,fast deployment,and low cost.The basic idea of the OWC is to transmit data on unguided media with light.This system requires multi-carrier modulation such as Orthogonal Frequency Division Multiplexing(OFDM).This paper studies optical OFDM performance based on Intensity Modulation with Direct Detection(IM/DD)system.This system requires a non-negativity constraint.The paper presents a framework for wireless optical OFDM system that comprises(IM/DD)with different forms,Direct Current biased Optical OFDM(DCO-OFDM),Asymmetrically Clipped Optical OFDM(ACO-OFDM),Asymmetrically DC-biased Optical OFDM(ADO-OFDM),and Flip-OFDM.It also considers channel coding as a tool for error control,channel equalization for reducing deterioration due to channel effects,and investigation of the turbulence effects.The evaluation results of the proposed framework reveal enhancement of performance.The performance of the IM/DD-OFDM system is investigated over different channel models such as AWGN,log-normal turbulence channel model,and ceiling bounce channel model.The simulation results show that the BER performance of the IM/DD-OFDM communication system is enhanced while the fading strength is decreased.The results reveal also that Hamming codes,BCH codes,and convolutional codes achieve better BER performance.Also,two algorithms of channel estimation and equalization are considered and compared.These algorithms include the Least Squares(LS)and the Minimum Mean Square Error(MMSE).The simulation results show that the MMSE algorithm gives better BER performance than the LS algorithm.
文摘With the rapid developments of commercial demands,a majority of advanced researches have been investigated for the applications of underwater wireless sensor(WSN)networks.Recently optical communication has been considered for underwater wireless sensor network.An experimental set-up for testing optical communication underwater has been provided and designed in present papers to maximize the energy coupled from these displacements to the transduction mechanism that converts the mechanical energy into electrical.The true case has been considered by measuring diffuse attenuation coefficients in different seas.One stand out potential optical communication method,Visible Light Communication(VLC)has been talked and several communication methods are compared from many points of view,for example attenuation in salt water.The evaluation of modulation techniques for underwater wireless optical communications has been displayed,and further how the data collection and storage with an underwater WSN is introduced.In this paper current researches for an(UWSN)based on optical communication are studied,in particular the potential VLC method and comparisons of VLC with other optical communication approaches.Underwater challenges would be analyzed by comparing a sort of communication methods,applied in underwater.Future work will be developed at last.
基金supported by the EPSRC research grant(No.EP/P006299/1)。
文摘A PE-ACO-OFDM(Position-Encoded Asymmetrically Clipped Optical Orthogonal Frequency Division Multiplexing)signaling scheme for intensity modulation and direct detection is introduced in this paper,where the anti-asymmetry characteristics of ACO-OFDM are exploited to improve the rate of data transmission.This is achieved by reducing the symbol duration of the ACO-OFDM signal,where only the first half of ACO-OFDM is used to transmit the ACO-OFDM data symbol after inverting its negative samples to positive ones.In addition,encoded ACO-OFDM samples are combined with every ACO-OFDM symbol to allow the receiver to identify the position of the inverted samples.Simulation results are introduced,and it is shown that the data rates of PE-ACO-OFDM improve by 33%compared with ACO-OFDM,when a 256-quadrature amplitude modulation scheme is considered as the encoded constellation order.It is also shown that the signal to noise ratio of the proposed PE-ACO-OFDM is higher by almost 1 dB compared with the traditional ACO-OFDM.
