一种基于能量跳跃的脉冲超宽带TOA估计

基于到达时间估计(TOA)的脉冲超宽带(IR-UWB)测距理论上可达到厘米级的精度.当无法估计接收信噪比时,基于门限的TOA估计精度受到门限设置的限制.本文提出了一种基于能量跳跃函数(FEE)的最大能量跳跃(MEL)TOA估计算法.该算法将最大径之前一段时间内FEL取值最大的时刻作为TOA的估计,估计过程中不需要设置门限.本文通过仿真分别在CMl和CM2信道模型中比较了MEL和几种常用算法的绝对平均误差(MAE).仿真结果表明,在多径信道环境尤其是非视距(NLOS)环境中,MEL算法的估计精度比门限比较(TC)算法和最大值回推(MES-SB)算法有较大的提高,而且接收信噪比越高MEL算法的优势越明显,在信噪比高于12dB时估计精度提高约3至4纳秒.     

超宽带系统中基于稀疏恢复的TOA和DOA联合估计方法

针对稀疏表示框架下进行超宽带系统中到达时间(Time of Arrival, TOA)和波达方向(Direction of Arrival, DOA)联合估计的问题,提出了一种基于稀疏恢复的TOA和DOA联合估计方法。采用l范数作为稀疏约束条件,并利用联合正交匹配追踪算法获取TOA估计值,解决了TOA配对问题,最后根据两副天线的时延差与DOA之间的关系获得信号的DOA估计。所提算法考虑了离网格信号参数估计问题,并通过联合稀疏恢复进行补偿。仿真结果表明,所提算法的参数估计性能优于传统的压缩感知算法、传播算子算法、矩阵束算法以及借助旋转不变性的信号参数估计技术(Estimating Signal Parameters via Rotational Invariance Techniques, ESPRIT)算法,同时计算复杂度更低。     

相关噪声中的TOA估计算法研究

实际环境中,常存在信号与噪声相关的情况,因此相关噪声环境中高效准确的信道参数估计算法的研究对于无线通信系统的构建至关重要。本文首先研究了基本MUSIC算法的TOA参数估计算法,仿真表明此种算法在高斯白噪声环境表现良好,但是并不适合相关噪声环境。针对相关噪声环境,本文研究了TOA参数估计中的MUSIC改进算法,并进行了仿真验证。仿真结果表明,改进算法完全可以适合于相关噪声环境中进行高分辨率TOA估计。     

一种基于峰度分析的UWB TOA估计门限选择法

超宽带(UWB)定位技术中对信号到达时间(TOA)的估计有几种方法,其中门限选择法是对接收信号样本的峰度进行分析,是一种复杂度较低的有效方法,本文运用仿真得到峰度系数和最佳门限之间的关系,并用TOA估计误差比较了几种不同的门限选择方法,由仿真得出的结论充分证明此方法的有效性,为设计提供了有用的工程参考。     

基于TOA/TDOA超宽带无线定位算法的改进

在充分研究了超宽带无线传输技术特性的基础上,对超宽带无线定位的原理进行了探讨.首先详细介绍了超宽带测距和定位的原理,对超宽带定位的精度进行了仿真分析.然后,针对超宽带Ad Hoc网络实际应用中节点数目比较多的情况,引入了节点的相关性来提高超宽带的定位精度,并进行了仿真分析.仿真结果显示了此算法在网络节点数比较多的情况下对定位精度有比较好的提高效果.     

基于坐标平移不变性的TOA定位算法

 本文提出了视距条件下利用坐标平移来实现到达时间(TOA)定位的新算法.该算法首先利用基站(BS)与移动台(MS)相对地理位置关系,采用坐标平移方法实现对MS位置的粗略估计;通过对误差分量特性的分析,提出了再次利用坐标平移消除误差分量相关性的方法,使得误差的协方差矩阵变得易于求解,从而实现对MS位置的精确估计.仿真表明,本文算法具有良好的性能.     

一种估计TOA的差分编码MUSIC算法

估计来波的到达时间(TOA)是蜂窝移动通信系统中用户定位的关键技术之一。该文提出了用差分编码的MUSIC算法估计CDMA系统中各用户的TOA,此方法不需使用训练序列,并且很少受载波频移的影响,因此可提高各用户的TOA估计精度。     

实际COSPAS-SARSAT信号TOA估计算法研究

该文针对伽利略搜救系统中TOA高精度估计的需求,考虑了实际接收的COSPAS-SARSAT信号中信息位宽的不确定度和调制不对称度,提出了基于多维联合极大似然估计的TOA估计算法。文章首先介绍了含调制不对称度的COSPAS-SARSAT信号模型,然后推导了算法原理,并给出了具体的实现过程。Monte Carlo仿真结果表明,在34.8 dBHz的处理门限、调制不对称度为5%和-5%的极端条件下该算法得到的TOA估计的均方根误差小于13.5 s,满足15 s的系统指标要求,优于其他算法的估计精度。     

基于TOA测距原理的伪卫星定位系统的构建

卫星导航定位技术的不断更新和硬件设备成本不断降低,导航定位技术已经成为每个人生活中触手可及的技术。而GNSS作为发展最为全面的定位技术,随着在轨卫星数目的不断增加,定位精度也越来越高。但是在一些特定的场景下,卫星信号还是会被遮挡,导致可见星数目不足,定位精度和稳定性得不到保障。伪卫星技术的出现很好地弥补了GNSS的一些不足,因此得到了广泛的研究。伪卫星系统也存在一些短板,本文借助TOA测距定位原理,以解决GNSS/伪卫星组合定位中地基伪卫星系统构建的问题。     

一种基于TOA定位的CHAN改进算法

 本文提出了一种基于TOA参数的CHAN改进定位算法.首先利用坐标平移的方法,消除定位方程中的未知参数,得到移动台位置的一次估计;其次通过对一次定位结果误差的分析表明基站的几何位置结构和到达距离对定位误差具有不同的"贡献"度,依据"贡献"度大小的不同,对大"贡献"度采用小权值而对小"贡献"度采用大权值的原则,提出了虚拟基站的方法来减小系统的总体误差,从而提高定位精度.仿真结果验证了本文算法的有效性.     

IR-UWB 系统中基于 root-MUSIC 算法的 TOA 和 DOA 联合估计简

针对二维多重信号分类算法可以估计出系统的到达时间(TOA, time-of-arrival)和波达方向(DOA, direction- of-arrival)参数,但需要复杂度非常高的二维谱峰搜索这一问题,提出了IR-UWB系统中基于求根MUSIC(root-MUSIC)的TOA和DOA联合估计算法,该算法对接收信号的频域形式建模,先估计出TOA,然后由TOA的差值计算出DOA,从而实现TOA和DOA的联合估计。该算法不需谱峰搜索,可直接给出估计参数的闭式解,还可实现参数配对。还推导了参数估计的误差方差。仿真结果表明,该算法的参数估计性能明显优于矩阵束算法、传播算子算法以及基于旋转不变技术估计信号参数算法,并且非常接近于2D-MUSIC算法,但该算法的复杂度却远远低于2D-MUSIC算法。     

一种联合TOA与DPS估计的MIMO OFDM系统信道估计算法

本文提出了一种基于联合TOA(到达时间)与DPS(时延功率谱)估计的MIMO OFDM系统信道估计算法,该算法借助导频设计,通过联合TOA与 DPS估计对各路径时延位置进行精确定位,并在此基础上,对初始时域信道估计进行非线性滤波,从而改善了大时延扩展信道条件下由于导频子载波受限所导致的估计性能恶化现象.此外,文中还进一步分析、推导了该算法所适用的信道多径时延条件.最后,仿真结果也表明该算法可有效对抗大时延扩展信道,而且其MSE、BER性能要优于传统的时域最小二乘信道估计算法.     

Joint estimation of TOA and DOA in IR-UWB system using a successive propagator method

Impulse radio ultra-wideband (IR-UWB) ranging and positioning require accurate estimation of time-of-arrival (TOA) and direction-of-arrival (DOA). With receiver of two antennas, both of the TOA and DOA parameters can be estimated via two-dimensional (2D) propagator method (PM), in which the 2D spectral peak searching, however, renders much higher computational complexity. This paper proposes a successive PM algorithm for joint TOA and DOA estimation in IR-UWB system to avoid 2D spectral peak searching. The proposed algorithm firstly gets the initial TOA estimates in the two antennas from the propagation matrix, then utilises successively one-dimensional (1D) local searches to achieve the estimation of TOAs in the two antennas, and finally obtains the DOA estimates via the difference in the TOAs between the two antennas. The proposed algorithm, which only requires 1D local searches, can avoid the high computational cost in 2D-PM algorithm. Furthermore, the proposed algorithm can obtain automatically paired parameters and has better joint TOA and DOA estimation performance than conventional PM algorithm, estimation of signal parameters via rotational invariance techniques algorithm and matrix pencil algorithm. Meanwhile, it has very close parameter estimation to that of 2D-PM algorithm. We have also derived the mean square error of TOA and DOA estimation of the proposed algorithm and the Cramer-Rao bound of TOA and DOA estimation in this paper. The simulation results verify the usefulness of the proposed algorithm.     

Searchback Algorithms for TOA Estimation in Non-coherent Low-rate IR-UWB Systems

Non-coherent ultra-wideband (UWB) receivers offer an attractive low-complexity solution to ranging with UWB radios. They use a simple receiver architecture that can operate at very low sampling rates compared to the Nyquist rate. In this paper, time-of-arrival (TOA) estimation performances of two different searchback algorithms for non-coherent impulse radio UWB systems are analyzed: jump back and search forward (JBSF) and serial backward search (SBS). Average ranging errors for both algorithms are formulated using noise-based ranging thresholds and at sub-Nyquist sampling rates. For JBSF, a lower bound on the average ranging error is obtained using an error-minimizing threshold. Also, a semi-analytic technique for the selection of the searchback window length is presented. For SBS, noise-based threshold selection for both single-cluster and multi-cluster channels are introduced. Computer simulations in IEEE 802.15.4a channels provide insights on the selection of some of the critical parameters for accurate ranging. The simulation results show that JBSF typically performs better than SBS if the inter-cluster delay parameter (K) is not selected appropriately for SBS. In both cases, it is shown that even at sampling rates much smaller than the Nyquist rate, ranging accuracies on the order of 33 cm can be obtained using a non-coherent UWB receiver.

IR-UWB能量检测接收机中基于门限的TOA估计

为提高能量检测模式下脉冲超宽带(IR-UWB)测距的精度和可行性,该文提出基于最优门限和次优门限的两种到达时间(TOA)估计算法。最优门限算法以接收机信号统计特性与UWB小尺度衰减特性关系式为基础推导出门限选择的闭合表达式,并在最小均方误差(MMSE)指标下求解TOA估计值;次优门限算法以最优门限分析为基础,在虚警概率约束下使用牛顿迭代给出求解门限的递推算法。仿真表明,与同类算法相比,最优门限算法测距精度有较大提升;次优门限算法易于实现,且性能无明显下降。     

Energy detector based TOA estimation for MMW systems using machine learning

60 GHz millimeter wave signals can provide precise time and multipath resolution and so have great potential for accurate time of arrival (TOA) and range estimation. To improve TOA estimation, a new energy detector based threshold selection algorithm which employs a neural network is proposed. The minimum slope, kurtosis, and skewness of the received energy block values are used to determine the normalized thresholds for different signal-to-noise ratios (SNRs). The effects of the channel and integration period are evaluated. Performance results are presented which show that the proposed approach provides better precision and is more robust than other solutions over a wide range of SNRs for the CM1.1 and CM2.1 channel models in the IEEE 802.15.3c standard.     

SFBC-OFDM系统中联合迭代信道估计与空频解码算法

提出了一种基于SFBC-OFDM系统的联合迭代信道估计与空频解码算法。首先为提高初始信道估计器的性能,提出了一种基于时频变换(TFT)的信道估计算法;其次提出了利用信道估计值与解码符号进行联合迭代信道估计与空频解码算法。分析与仿真结果显示,在准静态、快时变以及相关信道条件下,新的联合迭代信道估计与空频解码算法都有效地提高了系统性能。     

Low-power IR-UWB coherent TOA estimators with suboptimal sinusoidal templates for UWB-based body area networks

In this article, we propose and study the performance of low-power impulse radio ultra-wideband correlation-based time-of-arrival (TOA) estimators for body area networks. In particular, we study and compare the signal-to-noise-ratio degradation of TOA correlator-based estimators assuming optimal, real and complex suboptimal sinusoidal templates. Moreover, we study the improved Ziv-Zakai lower bound for complex suboptimal-template based TOA estimators. Then, we study and compare the performance of practical correlator-based TOA estimators using optimal, real and complex suboptimal sinusoidal templates via simulations in the IEEE 802.15.6a UWB on-body channel model as well as actual on-body measurements. The performance of real suboptimal template-based estimators approaches the performance of optimal TOA estimators based on simulations and actual measurements. We show that low-power is traded for a minimal performance loss.     

IR-UWB系统中采用锯齿波匹配的低复杂度TOA估计

采用非相干能量检测,提出了一种负斜率锯齿波相关搜索的算法,其结合接收多径脉冲信号的包络特征,获得了次优的估计性能。另外,通过对于锯齿波斜率(锯齿波宽度)的分析给出了在非视距条件下无偏估计的条件,理论分析了TOA估计平均绝对误差,推导出其性能解。仿真结果验证了算法的性能,并通过对结果的分析给出了在视距和非视距环境、不同信噪比下锯齿波斜率的最优取值范围。该方法解决了估计复杂度、抗多径和非视距环境下的顽健性问题。