The expectations for sensor networks are growing.The performance of wireless sensor networks(WSNs) is greatly influenced by their network topology.In this paper,we consider four patterned topologies that best support ...The expectations for sensor networks are growing.The performance of wireless sensor networks(WSNs) is greatly influenced by their network topology.In this paper,we consider four patterned topologies that best support connectivity among these deployed sensor nodes in two-tiered WSNs.The theoretical and simulation results show that the triangle-based topology has smaller cell number,shorter maximum hop length,less total energy consumption,and better performance than other topologies.The analysis carried out in this paper could provide the guidelines for network deployment and protocol design in the future applications.展开更多
The Khatri-Rao(KR) subspace method is a high resolution method for direction-of-arrival(DOA) estimation.Combined with 2q level nested array,the KR subspace method can detect O(N2q) sources with N sensors.However,the m...The Khatri-Rao(KR) subspace method is a high resolution method for direction-of-arrival(DOA) estimation.Combined with 2q level nested array,the KR subspace method can detect O(N2q) sources with N sensors.However,the method cannot be applicable to Gaussian sources when q is equal to or greater than 2 since it needs to use 2q-th order cumulants.In this work,a novel approach is presented to conduct DOA estimation by constructing a fourth order difference co-array.Unlike the existing DOA estimation method based on the KR product and 2q level nested array,the proposed method only uses second order statistics,so it can be employed to Gaussian sources as well as non-Gaussian sources.By exploiting a four-level nested array with N elements,our method can also identify O(N4) sources.In order to estimate the wideband signals,the proposed method is extended to the wideband scenarios.Simulation results demonstrate that,compared to the state of the art KR subspace based methods,the new method achieves higher resolution.展开更多
In this paper,we optimize the spectrum efficiency(SE)of uplink massive multiple-input multiple-output(MIMO)system with imperfect channel state information(CSI)over Rayleigh fading channel.The SE optimization problem i...In this paper,we optimize the spectrum efficiency(SE)of uplink massive multiple-input multiple-output(MIMO)system with imperfect channel state information(CSI)over Rayleigh fading channel.The SE optimization problem is formulated under the constraints of maximum power and minimum rate of each user.Then,we develop a near-optimal power allocation(PA)scheme by using the successive convex approximation(SCA)method,Lagrange multiplier method,and block coordinate descent(BCD)method,and it can obtain almost the same SE as the benchmark scheme with lower complexity.Since this scheme needs three-layer iteration,a suboptimal PA scheme is developed to further reduce the complexity,where the characteristic of massive MIMO(i.e.,numerous receive antennas)is utilized for convex reformulation,and the rate constraint is converted to linear constraints.This suboptimal scheme only needs single-layer iteration,thus has lower complexity than the near-optimal scheme.Finally,we joint design the pilot power and data power to further improve the performance,and propose an two-stage algorithm to obtain joint PA.Simulation results verify the effectiveness of the proposed schemes,and superior SE performance is achieved.展开更多
遗传因子的施主杂质在方形、塑造 V 、抛物线的量井说的浅水疗院用飞机波浪基础在有效团的信封功能理论的框架被学习。开始的四个杂质精力层次和扎根的状态的有约束力的精力比与变化方法更容易计算。当井宽度是小的时，计算结果显示杂...遗传因子的施主杂质在方形、塑造 V 、抛物线的量井说的浅水疗院用飞机波浪基础在有效团的信封功能理论的框架被学习。开始的四个杂质精力层次和扎根的状态的有约束力的精力比与变化方法更容易计算。当井宽度是小的时，计算结果显示杂质精力快速随井宽度和减少的增加铺平减少。状态增加直到它的地面的有约束力的精力到达最大的值，然后当井宽度增加，减少。结果是有意义的并且能广泛地在各种各样的 optoelectronic 设备的设计被使用。展开更多
This paper addresses the power control problems of Cognitive Radio(CR)under transmission power and interference temperature constraints.First,we propose the interference constraint which ensures that the Quality of Se...This paper addresses the power control problems of Cognitive Radio(CR)under transmission power and interference temperature constraints.First,we propose the interference constraint which ensures that the Quality of Service(QoS)standards for primary users is considered and a non-cooperative game power control model.Based on the proposed model,we developed a logical utility function based on the Signal-to-Interference-Noise Ratio(SINR)and a novel algorithm that is suitable for CR network power control.Then,the existence and uniqueness of the Nash Equilibrium(NE)in our utility function are proved by the principle of game theory and the corresponding optimizations.Compared to traditional algorithms,the proposed one could converge to an NE in 3-5iterative operations by setting an appropriate pricing factor.Finally,simulation results verified the stability and superiority of the novel algorithm in flat-fading channel environments.展开更多
We present a measurement campaign to characterize an indoor massive multiple-input multiple-output (MIMO) channel system, using a 64-element virtual linear array, a 64-element virtual planar array, and a 128-element v...We present a measurement campaign to characterize an indoor massive multiple-input multiple-output (MIMO) channel system, using a 64-element virtual linear array, a 64-element virtual planar array, and a 128-element virtual planar array. The array topologies are generated using a 3D mechanical turntable. The measurements are conducted at 2, 4, 6, 11, 15, and 22 GHz, with a large bandwidth of 200 MHz. Both line-of-sight (LOS) and non-LOS (NLOS) propagation scenarios are considered. The typical channel parameters are extracted, including path loss,shadow fading, power delay profile, and root mean square (RMS) delay spread. The frequency dependence of these channel parameters is analyzed. The correlation between shadow fading and RMS delay spread is discussed. In addition, the performance of the standard linear precoder—the matched filter, which can be used for intersymbol interference (ISI) mitigation by shortening the RMS delay spread, is investigated. Other performance measures,such as entropy capacity, Demmel condition number, and channel ellipticity, are analyzed. The measured channels,which are in a rich-scattering indoor environment, are found to achieve a performance close to that in independent and identically distributed Rayleigh channels even in an LOS scenario.展开更多
基金supported by the Shanghai Leading Academic Discipline Project (Grant Nos.S30108,08DZ2231100)the Science Foundation of Shanghai Municipal Education Commission (Grant No.09YZ33)the Science Foundation of Shanghai Municipal Commission of Science and Technology (Grant No.08220510900)
文摘The expectations for sensor networks are growing.The performance of wireless sensor networks(WSNs) is greatly influenced by their network topology.In this paper,we consider four patterned topologies that best support connectivity among these deployed sensor nodes in two-tiered WSNs.The theoretical and simulation results show that the triangle-based topology has smaller cell number,shorter maximum hop length,less total energy consumption,and better performance than other topologies.The analysis carried out in this paper could provide the guidelines for network deployment and protocol design in the future applications.
基金Project(2010ZX03006-004) supported by the National Science and Technology Major Program of ChinaProject(YYYJ-1113) supported by the Knowledge Innovation Program of the Chinese Academy of SciencesProject(2011CB302901) supported by the National Basic Research Program of China
文摘The Khatri-Rao(KR) subspace method is a high resolution method for direction-of-arrival(DOA) estimation.Combined with 2q level nested array,the KR subspace method can detect O(N2q) sources with N sensors.However,the method cannot be applicable to Gaussian sources when q is equal to or greater than 2 since it needs to use 2q-th order cumulants.In this work,a novel approach is presented to conduct DOA estimation by constructing a fourth order difference co-array.Unlike the existing DOA estimation method based on the KR product and 2q level nested array,the proposed method only uses second order statistics,so it can be employed to Gaussian sources as well as non-Gaussian sources.By exploiting a four-level nested array with N elements,our method can also identify O(N4) sources.In order to estimate the wideband signals,the proposed method is extended to the wideband scenarios.Simulation results demonstrate that,compared to the state of the art KR subspace based methods,the new method achieves higher resolution.
基金supported by the Fundamental Research Funds for the Central Universities of NUAA(No.kfjj20200414)Natural Science Foundation of Jiangsu Province in China(No.BK20181289).
文摘In this paper,we optimize the spectrum efficiency(SE)of uplink massive multiple-input multiple-output(MIMO)system with imperfect channel state information(CSI)over Rayleigh fading channel.The SE optimization problem is formulated under the constraints of maximum power and minimum rate of each user.Then,we develop a near-optimal power allocation(PA)scheme by using the successive convex approximation(SCA)method,Lagrange multiplier method,and block coordinate descent(BCD)method,and it can obtain almost the same SE as the benchmark scheme with lower complexity.Since this scheme needs three-layer iteration,a suboptimal PA scheme is developed to further reduce the complexity,where the characteristic of massive MIMO(i.e.,numerous receive antennas)is utilized for convex reformulation,and the rate constraint is converted to linear constraints.This suboptimal scheme only needs single-layer iteration,thus has lower complexity than the near-optimal scheme.Finally,we joint design the pilot power and data power to further improve the performance,and propose an two-stage algorithm to obtain joint PA.Simulation results verify the effectiveness of the proposed schemes,and superior SE performance is achieved.
基金Supported by the Scientific Research Foundation for the Returned Overseas Chinese Scholars, State Education Ministry (PRC)Foundation of Qufu Normal University under Grant No. XJ0622
文摘遗传因子的施主杂质在方形、塑造 V 、抛物线的量井说的浅水疗院用飞机波浪基础在有效团的信封功能理论的框架被学习。开始的四个杂质精力层次和扎根的状态的有约束力的精力比与变化方法更容易计算。当井宽度是小的时，计算结果显示杂质精力快速随井宽度和减少的增加铺平减少。状态增加直到它的地面的有约束力的精力到达最大的值，然后当井宽度增加，减少。结果是有意义的并且能广泛地在各种各样的 optoelectronic 设备的设计被使用。
基金partially supported by the National Natural Science Foundation of China under Grant No.61172073the Open Research Fund of National Mobile Communications Research Laboratory,Southeast University under Grant No.2012D19+1 种基金the Fundamental Research Funds for the Central Universities,Beijing Jiaotong University under Grant No.2013JBZ01the Program for New Century Excellent Talents in University of Ministry of Education of China under Grant No.NCET-12-0766
文摘This paper addresses the power control problems of Cognitive Radio(CR)under transmission power and interference temperature constraints.First,we propose the interference constraint which ensures that the Quality of Service(QoS)standards for primary users is considered and a non-cooperative game power control model.Based on the proposed model,we developed a logical utility function based on the Signal-to-Interference-Noise Ratio(SINR)and a novel algorithm that is suitable for CR network power control.Then,the existence and uniqueness of the Nash Equilibrium(NE)in our utility function are proved by the principle of game theory and the corresponding optimizations.Compared to traditional algorithms,the proposed one could converge to an NE in 3-5iterative operations by setting an appropriate pricing factor.Finally,simulation results verified the stability and superiority of the novel algorithm in flat-fading channel environments.
基金supported by the National Natural Science Foundation of China(Nos.61501020 and U1334202)the State Key Laboratory of Rail Traffic Control and Safety(No.RCS2016ZJ005)+5 种基金the National Key Research and Development Program(No.2016YFB1200102-04)the China Postdoctoral Science Foundation(No.2016M591355)the Fundamental Research Funds for the Central Universities(No.2016JBZ006)the National HighTech R&D Program(863)of China(No.2014AA01A706)the National S&T Major Project(No.2016ZX03001021-003)the Key Laboratory of Wireless Sensor Network and Communication,Chinese Academy of Sciences(No.2013005)
文摘We present a measurement campaign to characterize an indoor massive multiple-input multiple-output (MIMO) channel system, using a 64-element virtual linear array, a 64-element virtual planar array, and a 128-element virtual planar array. The array topologies are generated using a 3D mechanical turntable. The measurements are conducted at 2, 4, 6, 11, 15, and 22 GHz, with a large bandwidth of 200 MHz. Both line-of-sight (LOS) and non-LOS (NLOS) propagation scenarios are considered. The typical channel parameters are extracted, including path loss,shadow fading, power delay profile, and root mean square (RMS) delay spread. The frequency dependence of these channel parameters is analyzed. The correlation between shadow fading and RMS delay spread is discussed. In addition, the performance of the standard linear precoder—the matched filter, which can be used for intersymbol interference (ISI) mitigation by shortening the RMS delay spread, is investigated. Other performance measures,such as entropy capacity, Demmel condition number, and channel ellipticity, are analyzed. The measured channels,which are in a rich-scattering indoor environment, are found to achieve a performance close to that in independent and identically distributed Rayleigh channels even in an LOS scenario.
