With the ever-growing number of base stations(BSs)and user equipments(UEs)in ultra-dense networks(UDN),reusing the same pilot sequences among the cells is inevitable.With pilot reuse scheme,the channel estimation obta...With the ever-growing number of base stations(BSs)and user equipments(UEs)in ultra-dense networks(UDN),reusing the same pilot sequences among the cells is inevitable.With pilot reuse scheme,the channel estimation obtained at a BS contains not only the desired channel-state information(CSI)but also interference from neighboring cells,which can severely degrade CSI estimation performance and adversely affect communication performance.In this paper we consider a pilot contamination avoidance based on pilot pattern design for UDN where the pilot reuse employed and the interfering users from neighboring cells may be not at lower power levels at the BS compared to the in-cell users.We present a novel statistical interference model of sub-carriers to describe the non-deterministic interference from neighboring cells.Then,we provide a pilot pattern design model with non-uniform pilot distribution.Based on this,a pilot contamination avoidance based on pilot pattern design is proposed where pilot reuse scheme and the non-deterministic interference from neighboring cells are taken into consideration.Unlike existing interference mitigation approaches,the proposed method eliminates interference through the method of interference avoidance and can be applied to different kinds of channel estimation algorithms.Simulation results showed that the proposed approach can effectively avoid the interference and ensure the accuracy of channel estimation.展开更多
From the perspective of compressed sensing（CS） theory, the channel estimation problem in large-scale multiple input multiple output（MIMO）-orthogonal frequency division multiplexing（OFDM） system is investigated. ...From the perspective of compressed sensing（CS） theory, the channel estimation problem in large-scale multiple input multiple output（MIMO）-orthogonal frequency division multiplexing（OFDM） system is investigated. According to the theory, the smaller mutual coherence the reconstruction matrix has, the higher success probability the estimation can obtain. Aiming to design a pilot that can make the system reconstruction matrix having the smallest mutual coherence, this paper proposes a low complexity joint algorithm and obtains a kind of non-orthogonal pilot pattern. Simulation results show that compared with the conventional orthogonal pilot pattern, applying the proposed pattern in the CS channel estimation can obtain the better normalized mean square error performance. Moreover, the bit error rate performance of the large-scale MIMO-OFDM system is also improved.展开更多
To reduce the negative impact of the power amplifier(PA)nonlinear distortion caused by the orthogonal frequency division multiplexing(OFDM)waveform with high peak-to-average power ratio(PAPR)in integrated radar and co...To reduce the negative impact of the power amplifier(PA)nonlinear distortion caused by the orthogonal frequency division multiplexing(OFDM)waveform with high peak-to-average power ratio(PAPR)in integrated radar and communication(RadCom)systems is studied,the channel estimation in passive sensing scenarios.Adaptive channel estimation methods are proposed based on different pilot patterns,considering nonlinear distortion and channel sparsity.The proposed methods achieve sparse channel results by manipulating the least squares(LS)frequency-domain channel estimation results to preserve the most significant taps.The decision-aided method is used to optimize the sparse channel results to reduce the effect of nonlinear distortion.Numerical results show that the channel estimation performance of the proposed methods is better than that of the conventional methods under different pilot patterns.In addition,the bit error rate performance in communication and passive radar detection performance show that the proposed methods have good comprehensive performance.展开更多
Channel estimation in coherent OFDM by inserting pilot-symbols into two-dimensional time- frequency lattice is a promising candidate for improving channel transmission capacity in future wireless communication systems...Channel estimation in coherent OFDM by inserting pilot-symbols into two-dimensional time- frequency lattice is a promising candidate for improving channel transmission capacity in future wireless communication systems. This paper proposes a new Cartesian mathematical concept of the Hexagonal Pilot Pattern, Hexagonal Pilot with Virtual and Rectangular Pilot Pattern. The main focus of this work is to compare between the two pilots and by virtue of simulation conclusion which of the two pilots yields a better performance.展开更多
目的探索使用平视显示器(head up display,HUD)是否更加有助于飞行员探测跑道入侵事件,探索飞行员分别使用HUD和传统主飞行显示器(primary flight display,PFD)探测跑道入侵时眼动模式的差异。方法设计并开展了进近着陆情景下飞行员分...目的探索使用平视显示器(head up display,HUD)是否更加有助于飞行员探测跑道入侵事件,探索飞行员分别使用HUD和传统主飞行显示器(primary flight display,PFD)探测跑道入侵时眼动模式的差异。方法设计并开展了进近着陆情景下飞行员分别使用HUD和PFD探测跑道入侵的实验,采集注视次数、注视时间、注视轨迹和瞳孔直径等数据。结果飞行员分别使用HUD和PFD探测跑道入侵:不会显著影响俯仰姿态、航向、空速、高度、横滚、垂直速度和窗外视景兴趣域的眼动注视次数百分比和眼动注视时间百分比;使用PFD的注视轨迹更有助于探测跑道入侵;显著影响飞行员瞳孔直径。结论相比于PFD,HUD的使用不利于飞行员探测跑道入侵且易导致飞行员疲劳。展开更多
基金This work was supported in part by the Chongqing Research Program of Basic Research and Frontier Technology under Grant cstc2019jcyj-msxmX0233in part by Science and Technology Research Program of Chongqing Education Commission of China under Grant KJQN201901125,Grant KJQN201901103in part by the Scientific Research Foundation of Chongqing University of Technology under Grant 2019ZD42,Grant 2019ZD63.
文摘With the ever-growing number of base stations(BSs)and user equipments(UEs)in ultra-dense networks(UDN),reusing the same pilot sequences among the cells is inevitable.With pilot reuse scheme,the channel estimation obtained at a BS contains not only the desired channel-state information(CSI)but also interference from neighboring cells,which can severely degrade CSI estimation performance and adversely affect communication performance.In this paper we consider a pilot contamination avoidance based on pilot pattern design for UDN where the pilot reuse employed and the interfering users from neighboring cells may be not at lower power levels at the BS compared to the in-cell users.We present a novel statistical interference model of sub-carriers to describe the non-deterministic interference from neighboring cells.Then,we provide a pilot pattern design model with non-uniform pilot distribution.Based on this,a pilot contamination avoidance based on pilot pattern design is proposed where pilot reuse scheme and the non-deterministic interference from neighboring cells are taken into consideration.Unlike existing interference mitigation approaches,the proposed method eliminates interference through the method of interference avoidance and can be applied to different kinds of channel estimation algorithms.Simulation results showed that the proposed approach can effectively avoid the interference and ensure the accuracy of channel estimation.
基金supported by the National Science and Technology Major Project of the Ministry of Science and Technology(2014ZX03003011-004)the National Key Technology Research and Development Program of the Ministry of Science and Technology of China(2012BAF14B01)+2 种基金the National NaturalScience Foundation of China(61322110)the Hi-Tech Research and Development Program of China(2014AA01A705)the Doctoral Fund of Ministry of Education(201300051100013)
文摘From the perspective of compressed sensing（CS） theory, the channel estimation problem in large-scale multiple input multiple output（MIMO）-orthogonal frequency division multiplexing（OFDM） system is investigated. According to the theory, the smaller mutual coherence the reconstruction matrix has, the higher success probability the estimation can obtain. Aiming to design a pilot that can make the system reconstruction matrix having the smallest mutual coherence, this paper proposes a low complexity joint algorithm and obtains a kind of non-orthogonal pilot pattern. Simulation results show that compared with the conventional orthogonal pilot pattern, applying the proposed pattern in the CS channel estimation can obtain the better normalized mean square error performance. Moreover, the bit error rate performance of the large-scale MIMO-OFDM system is also improved.
基金supported by the National Natural Science Foundation of China(61931015,62071335,62250024)the Natural Science Foundation of Hubei Province of China(2021CFA002)+1 种基金the Fundamental Research Funds for the Central Universities of China(2042022dx0001)the Science and Technology Program of Shenzhen(JCYJ20170818112037398).
文摘To reduce the negative impact of the power amplifier(PA)nonlinear distortion caused by the orthogonal frequency division multiplexing(OFDM)waveform with high peak-to-average power ratio(PAPR)in integrated radar and communication(RadCom)systems is studied,the channel estimation in passive sensing scenarios.Adaptive channel estimation methods are proposed based on different pilot patterns,considering nonlinear distortion and channel sparsity.The proposed methods achieve sparse channel results by manipulating the least squares(LS)frequency-domain channel estimation results to preserve the most significant taps.The decision-aided method is used to optimize the sparse channel results to reduce the effect of nonlinear distortion.Numerical results show that the channel estimation performance of the proposed methods is better than that of the conventional methods under different pilot patterns.In addition,the bit error rate performance in communication and passive radar detection performance show that the proposed methods have good comprehensive performance.
文摘Channel estimation in coherent OFDM by inserting pilot-symbols into two-dimensional time- frequency lattice is a promising candidate for improving channel transmission capacity in future wireless communication systems. This paper proposes a new Cartesian mathematical concept of the Hexagonal Pilot Pattern, Hexagonal Pilot with Virtual and Rectangular Pilot Pattern. The main focus of this work is to compare between the two pilots and by virtue of simulation conclusion which of the two pilots yields a better performance.
文摘目的探索使用平视显示器(head up display,HUD)是否更加有助于飞行员探测跑道入侵事件,探索飞行员分别使用HUD和传统主飞行显示器(primary flight display,PFD)探测跑道入侵时眼动模式的差异。方法设计并开展了进近着陆情景下飞行员分别使用HUD和PFD探测跑道入侵的实验,采集注视次数、注视时间、注视轨迹和瞳孔直径等数据。结果飞行员分别使用HUD和PFD探测跑道入侵:不会显著影响俯仰姿态、航向、空速、高度、横滚、垂直速度和窗外视景兴趣域的眼动注视次数百分比和眼动注视时间百分比;使用PFD的注视轨迹更有助于探测跑道入侵;显著影响飞行员瞳孔直径。结论相比于PFD,HUD的使用不利于飞行员探测跑道入侵且易导致飞行员疲劳。
