共查询到18条相似文献,搜索用时 187 毫秒
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针对无线传感器网络节点低成本、低运算能力的特点,基于脉冲超宽带技术的无线传感器网络提出了一种基于能量检测的两步测距法.这种方法针对DP(direct path)分量进行TOA(time of arrival)估计,具体包含对DP所在能量块的广义似然比检验和能量块内对DP精确位置的极大似然估计两部分.给出了DP能量块检测概率和估计结果的闭合表达式,通过理论和数值分析了积分长度等系统参数对于TOA估计性能的影响,并建立了估计误差的数学模型.最后通过仿真结果进行了性能比较,并验证了分析结论.与传统方法比较的结果表明,该算法可以在复杂度较低的条件下取得一定的性能提升. 相似文献
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密集多径信道下,较为实际的超宽带测距系统一般采用基于TOA信息的能量检测器(energy detector, ED)接收机。TOA的估计精度决定着测距精度。在ED中多采用阈值比较的方法来估计TOA,阈值的设计对TOA估计的精度有着非常重要的影响。本文将最大概率检测(maximum probability of detection, MPD)算法应用于基于ED的TOA估计器中,并对样本检测概率计算方法进行改进,在搜索阈值的基础上计算出每次正确检测到直达路径(direct path, DP)的概率,提出一种阈值确定和DP检测新准则,即把相邻两个DP检测概率差值最大时对应的路径作为DP,则该次搜索所对应的阈值即为最佳阈值。文中给出了这种准则的理论分析及TOA估计算法流程。最后通过仿真比较考察了不同信噪比下不同TOA估计方法的估计误差。仿真结果表明了该算法相比于传统的TOA估计方法具有更高的精度,论证了该算法的有效性。 相似文献
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由于无线传感器网络(WSN)中传感器的传输功率有限,同时可能与基站(BS)传输距离较远,造成无法及时交付数据,数据新鲜度过低,影响时延敏感型业务决策质量。因此,采用无人机(UAV)辅助收集传感器数据,成为提升无线传感器网络数据新鲜度的有效手段。该文通过信息年龄(AoI)性能指标评估无线传感器网络数据新鲜度,并基于集中式训练分布式执行框架的多智能体近端策略优化(MAPPO)方法研究了无人机轨迹优化算法。通过联合优化所有无人机的飞行轨迹,实现地面节点平均加权信息年龄的最小化。仿真结果验证了所提多无人机路径规划算法在降低无线传感器网络信息年龄方面的有效性。 相似文献
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针对传感器节点的电池容量限制导致无线传感网络寿命低的问题,基于容量最大化(CMAX)、线上最大化寿命(OML)两种启发式方法以及高效路由能量管理技术(ERPMT),提出了基于ERPMT改进启发式方法的无线传感网络寿命最大化算法。首先,通过启发式方法初始化每个传感器节点,将节点能量划分为传感器节点起源数据和其它节点数据延迟;然后利用加入的一种优先度量延迟一跳节点的能量消耗;最后,根据路径平均能量为每个路由分配一个优先级,并通过ERPMT实现最终的无线传感网络优化。针对不同分布类型网络寿命的实验验证了本文算法的有效性及可靠性,实验结果表明,相比较为先进的启发式方法CMAX及OML,本文算法明显增大了无线传感网络的覆盖范围,并且大大地延长了网络的寿命。 相似文献
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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. 相似文献
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For ultra-wideband (UWB) ranging, TOA estimation with the energy detection (ED) receiver is to detect the energy sample that contains the first path (FP) signal in dense multipath. Threshold crossing (TC) is used frequently. However, it is difficult to determine the threshold. Some threshold setting methods are based on constant false alarm rate (CFAR) and the chi-squared distribution. However, the distribution is complicated. Moreover, it depends on the degree of freedom (DOF). If the DOF used is wrong, it will degrade the detection performance. The study bypasses the distribution. We first examine the distribution of the output of the ED receiver after power transformation. Based on the new characteristics of the transformed data and approximate distributions, we propose some practical TOA estimation methods. Similarly, the moments of the output of the ED receiver, such as the second or one-third order moments, are also analysed and used. The proposed methods are easy to implement and can achieve about the same ranging performance with methods based on the chi-squared distribution. We provide both theoretical and simulation results to prove their effectiveness. 相似文献
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IR-UWB能量检测接收机中基于门限的TOA估计 总被引:1,自引:0,他引:1
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。 相似文献
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This paper deals with the estimation of the time of arrival (TOA) of ultra‐wideband signals under IEEE 802.15.4a channel models. The proposed approach is based on a randomness test and consists of determining whether an autoregressive (AR) process modeling an energy frame is random or not by using a distance to measure the randomness. The proposed method uses a threshold that is derived analytically according to a preset false alarm probability. To highlight the effectiveness of the developed approach, simulation setups as well as real data experiments are conducted to assess the performance of the new TOA estimation algorithm. Thereby, the proposed method is compared with the cell averaging constant false alarm rate technique, the threshold comparison algorithm, and the technique based on maximum energy selection with search back. The obtained results are promising, considering both simulations and collected real‐life data. 相似文献
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为了解决室内密集多径环境下人员定位精度差这一问题,设计并实现了一种基于脉冲超宽带与能量检测接收机的信号到达时间估计算法。根据在IEEE802.12.4a标准室内家居环境下得到的超宽带信号,深入分析了信号的偏度、翘度与均方差特性。根据信号特性与信噪比之间的关系,算法能够实现高精度的信号传播时间估计。该算法充分考虑了积分周期与信号传播环境如视距与非视距对信号传播时间造成的影响。通过实验分析对比,该算法对信号传播时间估计具有更好的鲁棒性,目标运动速度和形变具有很好的鲁棒性,能够提供更高的精度。相较于阈值估计算法,该算法在低信噪比环境下最优能够提高10 ns的估计精度。 相似文献
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脉冲星导航是一种新型的自主式导航。为提高其精度与实时性,提出一种小波变换与压缩感知结合的脉冲星到达时间(Time of Arrival,TOA)估计的方法。该方法对标准脉冲轮廓使用小波变换构造多级冗余字典,通过信号恢复算法估计出实际脉冲星的TOA。该方法的算法复杂度低于传统的TOA估计方法,并且随着脉冲星信号周期内bin数量的增加,算法的实时性越好。该方法改变了传统的先去噪再估计TOA的思路,其可以嵌入到信号去噪的过程中,还可以和小波去噪的阈值处理并行计算。仿真结果显示文中方法耗时分别为两种传统TOA估计方法的0.87%和21.35%,并且随着数据时长的缩短,文中方法的TOA估计精度的相对优势越发明显。该方法不但可以提高TOA估计精度,而且降低了对数据时长的依赖。 相似文献
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It is well known that non-line-of-sight (NLOS) error has been the major factor impeding the enhancement of accuracy for time of arrival (TOA) estimation and wireless positioning. This article proposes a novel method of TOA estimation effectively reducing the NLOS error by 60%, comparing with the traditional timing and synchronization method. By constructing the orthogonal training sequences, this method converts the traditional TOA estimation to the detection of the first arrival path (FAP) in the NLOS multipath environment, and then estimates the TOA by the round-trip transmission (RTT) technology. Both theoretical analysis and numerical simulations prove that the method proposed in this article achieves better performance than the traditional methods. 相似文献
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Mohsen Pourkhaatoun Seyed A. Zekavat 《International Journal of Wireless Information Networks》2012,19(4):341-351
This paper proposes high-precision, time-of-arrival (TOA) estimation by concatenating non-contiguous and non-equal white spaces in the spectrum. White spaces are identified and allocated by the capabilities of cognitive radios (CR). A simple radio system that enables sequential concatenation of non-contiguous bands is introduced. The paper aims to design signal-processing techniques for the proposed radio that maintain a TOA performance comparable to that of utilizing a bandwidth equivalent to the addition of all white spaces. This work also investigates two potential high resolutions, TOA estimation architectures that are applicable to CR-based systems. The first approach estimates TOA over each sub-band and then optimally fuses the estimated TOAs. In the second technique, channels estimated over sub-bands are concatenated and a TOA-estimation method is applied to the whole available spectrum. The Cramer?CRao bound (CRB) of the TOA estimation for both approaches is computed. Minimum mean square estimation (MMSE) algorithm is applied to evaluate the performance of the proposed system. Simulations are concluded to study the performance in terms of the variance of error. Moreover, the complexity of the proposed concatenation method is evaluated. 相似文献
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This letter proposes a non‐coherent blind time‐of‐arrival (TOA) estimation scheme for impulse radio ultra‐wideband systems. The TOA estimation is performed in two consecutive phases: the Rayleigh‐quotient theorem‐based coarse‐signal acquisition (CSA) and the iterative‐threshold‐test‐based fine time estimation (FTE). The proposed scheme serves in a blind manner without demanding any a priori knowledge of the channel and the noise. Analysis and simulations demonstrate that the proposed scheme significantly increases the signal detection probability in CSA and ameliorates the TOA estimation accuracy in FTE. 相似文献