为了降低直流偏置光正交频分复用(DC-biased Optical OFDM,DCO-OFDM)系统中高峰均功率比(Peak to Average Power Ratio,PAPR)对无线光通信系统性能的影响,本文提出一种导频辅助峰均比抑制方案。方案中将多个离散频域信号划分为多个子块...为了降低直流偏置光正交频分复用(DC-biased Optical OFDM,DCO-OFDM)系统中高峰均功率比(Peak to Average Power Ratio,PAPR)对无线光通信系统性能的影响,本文提出一种导频辅助峰均比抑制方案。方案中将多个离散频域信号划分为多个子块,然后各子块独立进行选择性映射(Selected Mappin,SLM),并将多个最佳相位序列的边带信息以纠错码的方式存放在一个块状导频之中,接收端使用最大似然准则来估计导频信号,解决了SLM边带信息传输和恢复问题,提高了频带利用率,并进行了仿真验证。互补累积概率为10-3时,导频辅助16QAM DCO-OFDM系统比原始DCO-OFDM提升了3 dB;误码率为10-4时,信噪比优2 dB。理论推导的PAPR互补累积分布函数表达式和仿真结果表明,本文所提方案的PAPR抑制性能提升,降低了限幅噪声对系统误码率的影响,纠错码提高了边带信息恢复的准确度,提高了系统的误码性能。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
直流偏置光正交频分复用(DC-biased optical orthogonal frequency division multiplexing,DCO-OFDM)可见光通信(visible light communication,VLC)系统具有较高的峰均功率比(peak-to-average power ratio,PAPR)。为解决此问题,提出一...直流偏置光正交频分复用(DC-biased optical orthogonal frequency division multiplexing,DCO-OFDM)可见光通信(visible light communication,VLC)系统具有较高的峰均功率比(peak-to-average power ratio,PAPR)。为解决此问题,提出一种联合限幅和归一化μ律压扩算法抑制DCO-OFDM系统的PAPR。首先,该联合算法利用限幅操作对时域信号中的大峰值信号进行削波来降低信号的幅值;其次,对限幅后的信号再进行压扩变换。通过这种联合算法,DCO-OFDM系统的PAPR可以显著降低。实验仿真结果表明,当采用16QAM调制方式,互补累计函数的值为10^(-3)时,相比较于联合限幅和传统μ律压扩算法,此联合算法的PAPR下降了约2.206 dB。展开更多
文摘为了降低直流偏置光正交频分复用(DC-biased Optical OFDM,DCO-OFDM)系统中高峰均功率比(Peak to Average Power Ratio,PAPR)对无线光通信系统性能的影响,本文提出一种导频辅助峰均比抑制方案。方案中将多个离散频域信号划分为多个子块,然后各子块独立进行选择性映射(Selected Mappin,SLM),并将多个最佳相位序列的边带信息以纠错码的方式存放在一个块状导频之中,接收端使用最大似然准则来估计导频信号,解决了SLM边带信息传输和恢复问题,提高了频带利用率,并进行了仿真验证。互补累积概率为10-3时,导频辅助16QAM DCO-OFDM系统比原始DCO-OFDM提升了3 dB;误码率为10-4时,信噪比优2 dB。理论推导的PAPR互补累积分布函数表达式和仿真结果表明,本文所提方案的PAPR抑制性能提升,降低了限幅噪声对系统误码率的影响,纠错码提高了边带信息恢复的准确度,提高了系统的误码性能。
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.
