This paper aimed to propose two algorithms,DA-M and RF-M,of reducing the impact of multipath interference(MPI)on intensity modulation direct detection(IM-DD)systems,particularly for four-level pulse amplitude modulati...This paper aimed to propose two algorithms,DA-M and RF-M,of reducing the impact of multipath interference(MPI)on intensity modulation direct detection(IM-DD)systems,particularly for four-level pulse amplitude modulation(PAM4)systems.DA-M reduced the fluctuation by averaging the signal in blocks,RF-M estimated MPI by subtracting the decision value of the corresponding block from the mean value of a signal block,and then generated interference-reduced samples by subtracting the interference signal from the product of the corresponding MPI estimate and then weighting factor.This paper firstly proposed to separate the signal before decision-making into multiple blocks,which significantly reduced the complexity of DA-M and RF-M.Simulation results showed that the MPI noise of 28 GBaud IMDD system under the linewidths of 1e5 Hz,1e6 Hz and 10e6 Hz can be effectively alleviated.展开更多
Dear Editor,As the Internet of things(IoT)and autonomous driving continue to evolve,positioning technology faces increasing demands for higher accuracy and reliability.Traditional positioning methods often struggle in...Dear Editor,As the Internet of things(IoT)and autonomous driving continue to evolve,positioning technology faces increasing demands for higher accuracy and reliability.Traditional positioning methods often struggle in complex signal environments with multipath interference and non-line-of-sight(NLOS)conditions.Reconfigurable intelligent surfaces(RIS),an innovative technology that can flexibly control signal propagation,offer new possibilities for positioning systems.展开更多
To solve the problem that the conventional detections in DS-CDMA suffer from high complexity and poor robustness for the time-hopping pulse signals, the received pulse signals were remodeled, and a mulfipath-free dete...To solve the problem that the conventional detections in DS-CDMA suffer from high complexity and poor robustness for the time-hopping pulse signals, the received pulse signals were remodeled, and a mulfipath-free detection scheme, which provides a simple approach to select samples of received signals, was introduced. By this scheme, the subsequent multiuser detection （MUD） would get rid of the mis- match due to the correlative multipath signal in IR-UWB. In addition, a computationally efficient recur-sive least squares （RLS） type algorithm based on least mean fourth （LMF） criterion is derived to suppress multi-access interference. The proposed multiuser detection algorithm performs well at low complexity, even in dense muhipath environment.展开更多
Multipath interference poses substantial challenges to global navigation satellite system(GNSS)receivers,leading to inaccuracies in the time of arrival(TOA)measurement of the line of sight(LOS)signal.Therefore,to miti...Multipath interference poses substantial challenges to global navigation satellite system(GNSS)receivers,leading to inaccuracies in the time of arrival(TOA)measurement of the line of sight(LOS)signal.Therefore,to mitigate the impact of multipath on receivers,the problem has been approached at several system development stages—signal design,reception,and processing.While efforts and advancements have been achieved over the years at each stage seeking navigation robustness,this article focuses on the signal processing stage by presenting a review of advanced multipath mitigation techniques using adaptive channel parameter estimation at the correlation level.The multipath mitigation literature often resorts to optimistic assumptions—high signal-to-noise ratio(SNR),static multipath channel,single fading channel distribution,and so on—while in real-world scenarios noise is prominent,the number of paths and their states vary at different rates,channels are nonstationary,along with other nonideal conditions.Moreover,it is important to directly compare different techniques to characterize their applicability and limitations.An analysis of adaptive algorithms is conducted for multipath mitigation applications.展开更多
基金supported by the National Key Research and Development Program of China 2021YFB2900801the Young Elite Scientists Sponsorship Program of CIC 2021QNRC001+1 种基金National Natural Science Foundation of China NSFC,62201033,U22A2005the Foundation of the Beijing Engineering and Technology Center for Convergence Networks and Ubiquitous Services.
文摘This paper aimed to propose two algorithms,DA-M and RF-M,of reducing the impact of multipath interference(MPI)on intensity modulation direct detection(IM-DD)systems,particularly for four-level pulse amplitude modulation(PAM4)systems.DA-M reduced the fluctuation by averaging the signal in blocks,RF-M estimated MPI by subtracting the decision value of the corresponding block from the mean value of a signal block,and then generated interference-reduced samples by subtracting the interference signal from the product of the corresponding MPI estimate and then weighting factor.This paper firstly proposed to separate the signal before decision-making into multiple blocks,which significantly reduced the complexity of DA-M and RF-M.Simulation results showed that the MPI noise of 28 GBaud IMDD system under the linewidths of 1e5 Hz,1e6 Hz and 10e6 Hz can be effectively alleviated.
基金supported by the Open Fund Project of Key Laboratory of Ocean Observation Technology,MNR(2023klootA01).
文摘Dear Editor,As the Internet of things(IoT)and autonomous driving continue to evolve,positioning technology faces increasing demands for higher accuracy and reliability.Traditional positioning methods often struggle in complex signal environments with multipath interference and non-line-of-sight(NLOS)conditions.Reconfigurable intelligent surfaces(RIS),an innovative technology that can flexibly control signal propagation,offer new possibilities for positioning systems.
基金the National Natural Science Foundation of China(No60432040)the Guangxi Key Laboratory Foundation(No,063006-5G)
文摘To solve the problem that the conventional detections in DS-CDMA suffer from high complexity and poor robustness for the time-hopping pulse signals, the received pulse signals were remodeled, and a mulfipath-free detection scheme, which provides a simple approach to select samples of received signals, was introduced. By this scheme, the subsequent multiuser detection （MUD） would get rid of the mis- match due to the correlative multipath signal in IR-UWB. In addition, a computationally efficient recur-sive least squares （RLS） type algorithm based on least mean fourth （LMF） criterion is derived to suppress multi-access interference. The proposed multiuser detection algorithm performs well at low complexity, even in dense muhipath environment.
基金supported by national funds,through the Operational Competitiveness and Internationalization Programme(COMPETE 2020)(project no.179491,funding reference:SIFN-01-9999-FN-179491).
文摘Multipath interference poses substantial challenges to global navigation satellite system(GNSS)receivers,leading to inaccuracies in the time of arrival(TOA)measurement of the line of sight(LOS)signal.Therefore,to mitigate the impact of multipath on receivers,the problem has been approached at several system development stages—signal design,reception,and processing.While efforts and advancements have been achieved over the years at each stage seeking navigation robustness,this article focuses on the signal processing stage by presenting a review of advanced multipath mitigation techniques using adaptive channel parameter estimation at the correlation level.The multipath mitigation literature often resorts to optimistic assumptions—high signal-to-noise ratio(SNR),static multipath channel,single fading channel distribution,and so on—while in real-world scenarios noise is prominent,the number of paths and their states vary at different rates,channels are nonstationary,along with other nonideal conditions.Moreover,it is important to directly compare different techniques to characterize their applicability and limitations.An analysis of adaptive algorithms is conducted for multipath mitigation applications.
