The problem of channel estimation for multiple an- tenna orthogonal frequency division multiplexing （OFDM） systems subject to unknown carrier frequency offset （CFO） is addressed. Multiple signal classification （M...The problem of channel estimation for multiple an- tenna orthogonal frequency division multiplexing （OFDM） systems subject to unknown carrier frequency offset （CFO） is addressed. Multiple signal classification （MUSIC）-Iike algorithm, which generally has been used for direction estimation or frequency estimation, is used for channel estimation in multiple antenna OFDM systems. A reduced dimensional （RD）-MUSIC based algorithm for channel estimation is proposed in multiple antenna OFDM systems with unknown CFO. The Cramer-Rao bound （CRB） of channel estimation in multiple antenna OFDM systems with unknown CFO is derived. The proposed algorithm has a superior performance of channel estimation compared with the Capon method and the least squares method.展开更多
For multiple-input multiple-output （MIMO） orthogonal frequency division multiplexing （OFDM） systems, a joint timing synchronization and frequency offset acquisition algorithm based on fractional Fourier transform ...For multiple-input multiple-output （MIMO） orthogonal frequency division multiplexing （OFDM） systems, a joint timing synchronization and frequency offset acquisition algorithm based on fractional Fourier transform （FRFT） is proposed. The linear frequency modulation signals superimposed on the data signals are used as the training signals. By performing FRFT on the received signals and searching the peak value of the FRFT results, the receiver can realize timing synchronization and frequency offset acquisition simultaneously. Compared with the existing methods, the proposed algorithm can provide better timing synchronization performance and larger frequency offset acquisition range even under multi-path channels with low signal to noise ratio. Theoretical analysis and simulation results prove this point.展开更多
How to obtain accurate channel state information(CSI)at the transmitter with less pilot overhead for frequency division duplexing(FDD) massive multiple-input multiple-output(MIMO)system is a challenging issue due to t...How to obtain accurate channel state information(CSI)at the transmitter with less pilot overhead for frequency division duplexing(FDD) massive multiple-input multiple-output(MIMO)system is a challenging issue due to the large number of antennas. To reduce the overwhelming pilot overhead, a hybrid orthogonal and non-orthogonal pilot distribution at the base station(BS),which is a generalization of the existing pilot distribution scheme,is proposed by exploiting the common sparsity of channel due to the compact antenna arrangement. Then the block sparsity for antennas with hybrid pilot distribution is derived respectively and can be used to obtain channel impulse response. By employing the theoretical analysis of block sparse recovery, the total coherence criterion is proposed to optimize the sensing matrix composed by orthogonal pilots. Due to the huge complexity of optimal pilot acquisition, a genetic algorithm based pilot allocation(GAPA) algorithm is proposed to acquire optimal pilot distribution locations with fast convergence. Furthermore, the Cramer Rao lower bound is derived for non-orthogonal pilot-based channel estimation and can be asymptotically approached by the prior support set, especially when the optimized pilot is employed.展开更多
Carrier frequency offset （CFO） in MIMO-OFDM systems can be decoupled into two parts： fraction frequency offset （FFO） and integer frequency offset （IFO）. The problem of IFO estimation is addressed and a new IFO ...Carrier frequency offset （CFO） in MIMO-OFDM systems can be decoupled into two parts： fraction frequency offset （FFO） and integer frequency offset （IFO）. The problem of IFO estimation is addressed and a new IFO estimator based on the Bayesian philosophy is proposed. Also, it is shown that the Bayesian IFO estimator is optimal among all the IFO estimators. Furthermore, the Bayesian estimator can take advantage of oversampling so that better performance can be obtained. Finally, numerical results show the optimality of the Bayesian estimator and validate the theoretical analysis.展开更多
针对多输入多输出正交时频空间(multiple-input multiple-output orthogonal time frequency space,MIMO-OTFS)系统由最大时延、多普勒扩展、天线数量增加带来信道估计计算开销大、准确率下降的问题,提出了一种基于感知辅助和原子选择...针对多输入多输出正交时频空间(multiple-input multiple-output orthogonal time frequency space,MIMO-OTFS)系统由最大时延、多普勒扩展、天线数量增加带来信道估计计算开销大、准确率下降的问题,提出了一种基于感知辅助和原子选择门限的广义正交匹配追踪(sensing aided generalized orthogonal matching pursuit algorithm based on atomic threshold,SA-TGOMP)信道估计算法。该算法首先将雷达探测的用户和周围环境信息转化为OTFS信道的初始索引集,然后引入以固定值选取相关性原子进行迭代的策略和原子选择门限进行支撑集更新。实验结果表明,本文算法能够有效提高信道估计精度的同时减少导频开销。展开更多
针对基于定向传输的飞行器自组织网络(flying ad-hoc network,FANET)中拓扑变化频繁、链路质量波动以及初始建网困难等问题,提出了一种基于多输入多输出(multiple-input multipleoutput,MIMO)正交时频空(orthogonal time frequency spac...针对基于定向传输的飞行器自组织网络(flying ad-hoc network,FANET)中拓扑变化频繁、链路质量波动以及初始建网困难等问题,提出了一种基于多输入多输出(multiple-input multipleoutput,MIMO)正交时频空(orthogonal time frequency space,OTFS)通感一体化波形的感知辅助快速邻居发现方法,借助感知机制实时获取邻节点信息以加速建网效率,并采用新型的通感一体波形OTFS以对抗快变信道中的多普勒效应,提升链路质量。针对FANET场景研究物理层基于MIMOOTFS通感一体化波形的多目标检测技术;将物理层感知方案映射到上层网络中,设计感知辅助的高效邻居发现算法;最后提出一种多点通感协同机制,通过邻节点间交互感知信息和邻居发现表以间接感知及发现潜在目标,提升FANET初始建网的效率。仿真结果表明,所提方案相比传统通信组网协议可以极大降低FANET的初始建网耗时,增加目标感知精度,提升组网的整体性能。展开更多
该文研究了基于正交时频空间(orthogonal time frequency space, OTFS)调制的去蜂窝大规模多输入多输出(massive multiple-input multiple-output, mMIMO)系统上行链路通信中的和速率优化问题,提出一种蚁群递归搜索机制。该机制首先采...该文研究了基于正交时频空间(orthogonal time frequency space, OTFS)调制的去蜂窝大规模多输入多输出(massive multiple-input multiple-output, mMIMO)系统上行链路通信中的和速率优化问题,提出一种蚁群递归搜索机制。该机制首先采用最小割分组算法实现用户分组,然后使用蚁群算法进行递归优化求解。仿真结果表明,通过运用该机制进行功率控制,其性能相比于未分组的m MIMO-OTFS系统和m MIMO-正交频分复用(orthogonal frequency division multiplexing, OFDM)系统更好。此外,移动速度对系统用户上行可达速率性能的影响研究结果表明,mMIMO-OTFS系统与mMIMO-OFDM系统的和速率性能差距随移动速度增长呈递增状态。展开更多
针对传统室内定位方法在准确性及稳定性上的不足,本文提出了一种基于信道状态信息(channel state information,CSI)的无源室内定位方法。该方法采用普通设备搭建了实验平台,离线阶段采集CSI数据建立位置指纹库,在线阶段则利用机器学习...针对传统室内定位方法在准确性及稳定性上的不足,本文提出了一种基于信道状态信息(channel state information,CSI)的无源室内定位方法。该方法采用普通设备搭建了实验平台,离线阶段采集CSI数据建立位置指纹库,在线阶段则利用机器学习的朴素贝叶斯算法进行位置分类。为进一步提高分类准确度,本文还提出了置信度方法,通过综合多条天线对的结果来减少位置误判。实验结果表明,本文所提出方法能有效实现对室内人员的无源定位,可以达到90%以上的准确度。展开更多
基金supported by the National Natural Science Foundation of China(6137116961301108+1 种基金61071164)the Fundamental Research Funds for the Central Universities(NS2013024)
文摘The problem of channel estimation for multiple an- tenna orthogonal frequency division multiplexing （OFDM） systems subject to unknown carrier frequency offset （CFO） is addressed. Multiple signal classification （MUSIC）-Iike algorithm, which generally has been used for direction estimation or frequency estimation, is used for channel estimation in multiple antenna OFDM systems. A reduced dimensional （RD）-MUSIC based algorithm for channel estimation is proposed in multiple antenna OFDM systems with unknown CFO. The Cramer-Rao bound （CRB） of channel estimation in multiple antenna OFDM systems with unknown CFO is derived. The proposed algorithm has a superior performance of channel estimation compared with the Capon method and the least squares method.
基金supported by the National Natural Science Foundation of China(60672047).
文摘For multiple-input multiple-output （MIMO） orthogonal frequency division multiplexing （OFDM） systems, a joint timing synchronization and frequency offset acquisition algorithm based on fractional Fourier transform （FRFT） is proposed. The linear frequency modulation signals superimposed on the data signals are used as the training signals. By performing FRFT on the received signals and searching the peak value of the FRFT results, the receiver can realize timing synchronization and frequency offset acquisition simultaneously. Compared with the existing methods, the proposed algorithm can provide better timing synchronization performance and larger frequency offset acquisition range even under multi-path channels with low signal to noise ratio. Theoretical analysis and simulation results prove this point.
基金supported by the National Natural Science Foundation of China(61671176 61671173)the Fundamental Research Funds for the Center Universities(HIT.MKSTISP.2016 13)
文摘How to obtain accurate channel state information(CSI)at the transmitter with less pilot overhead for frequency division duplexing(FDD) massive multiple-input multiple-output(MIMO)system is a challenging issue due to the large number of antennas. To reduce the overwhelming pilot overhead, a hybrid orthogonal and non-orthogonal pilot distribution at the base station(BS),which is a generalization of the existing pilot distribution scheme,is proposed by exploiting the common sparsity of channel due to the compact antenna arrangement. Then the block sparsity for antennas with hybrid pilot distribution is derived respectively and can be used to obtain channel impulse response. By employing the theoretical analysis of block sparse recovery, the total coherence criterion is proposed to optimize the sensing matrix composed by orthogonal pilots. Due to the huge complexity of optimal pilot acquisition, a genetic algorithm based pilot allocation(GAPA) algorithm is proposed to acquire optimal pilot distribution locations with fast convergence. Furthermore, the Cramer Rao lower bound is derived for non-orthogonal pilot-based channel estimation and can be asymptotically approached by the prior support set, especially when the optimized pilot is employed.
基金supported by the National Science Fund for Distinguished Young Scholars (60725105)National"863"Program of China (2007AA01Z288)+1 种基金the sixth project of the Key Project of National Nature Science Foundation of China (60496316)Teaching Research Award Program for Outstanding Young Teachers in Higher Education Institutions of MOE,the 111 Project (B08038).
文摘Carrier frequency offset （CFO） in MIMO-OFDM systems can be decoupled into two parts： fraction frequency offset （FFO） and integer frequency offset （IFO）. The problem of IFO estimation is addressed and a new IFO estimator based on the Bayesian philosophy is proposed. Also, it is shown that the Bayesian IFO estimator is optimal among all the IFO estimators. Furthermore, the Bayesian estimator can take advantage of oversampling so that better performance can be obtained. Finally, numerical results show the optimality of the Bayesian estimator and validate the theoretical analysis.
文摘针对多输入多输出正交时频空间(multiple-input multiple-output orthogonal time frequency space,MIMO-OTFS)系统由最大时延、多普勒扩展、天线数量增加带来信道估计计算开销大、准确率下降的问题,提出了一种基于感知辅助和原子选择门限的广义正交匹配追踪(sensing aided generalized orthogonal matching pursuit algorithm based on atomic threshold,SA-TGOMP)信道估计算法。该算法首先将雷达探测的用户和周围环境信息转化为OTFS信道的初始索引集,然后引入以固定值选取相关性原子进行迭代的策略和原子选择门限进行支撑集更新。实验结果表明,本文算法能够有效提高信道估计精度的同时减少导频开销。
文摘针对基于定向传输的飞行器自组织网络(flying ad-hoc network,FANET)中拓扑变化频繁、链路质量波动以及初始建网困难等问题,提出了一种基于多输入多输出(multiple-input multipleoutput,MIMO)正交时频空(orthogonal time frequency space,OTFS)通感一体化波形的感知辅助快速邻居发现方法,借助感知机制实时获取邻节点信息以加速建网效率,并采用新型的通感一体波形OTFS以对抗快变信道中的多普勒效应,提升链路质量。针对FANET场景研究物理层基于MIMOOTFS通感一体化波形的多目标检测技术;将物理层感知方案映射到上层网络中,设计感知辅助的高效邻居发现算法;最后提出一种多点通感协同机制,通过邻节点间交互感知信息和邻居发现表以间接感知及发现潜在目标,提升FANET初始建网的效率。仿真结果表明,所提方案相比传统通信组网协议可以极大降低FANET的初始建网耗时,增加目标感知精度,提升组网的整体性能。
文摘该文研究了基于正交时频空间(orthogonal time frequency space, OTFS)调制的去蜂窝大规模多输入多输出(massive multiple-input multiple-output, mMIMO)系统上行链路通信中的和速率优化问题,提出一种蚁群递归搜索机制。该机制首先采用最小割分组算法实现用户分组,然后使用蚁群算法进行递归优化求解。仿真结果表明,通过运用该机制进行功率控制,其性能相比于未分组的m MIMO-OTFS系统和m MIMO-正交频分复用(orthogonal frequency division multiplexing, OFDM)系统更好。此外,移动速度对系统用户上行可达速率性能的影响研究结果表明,mMIMO-OTFS系统与mMIMO-OFDM系统的和速率性能差距随移动速度增长呈递增状态。
文摘针对传统室内定位方法在准确性及稳定性上的不足,本文提出了一种基于信道状态信息(channel state information,CSI)的无源室内定位方法。该方法采用普通设备搭建了实验平台,离线阶段采集CSI数据建立位置指纹库,在线阶段则利用机器学习的朴素贝叶斯算法进行位置分类。为进一步提高分类准确度,本文还提出了置信度方法,通过综合多条天线对的结果来减少位置误判。实验结果表明,本文所提出方法能有效实现对室内人员的无源定位,可以达到90%以上的准确度。
