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基于移动通信环境中非视距(NLOS)传播时延服从指数分布的特性,提出了一种改善移动台定位精度的波达时间(TOA)数据处理方法.NLOS传播时延是TOA测量误差的一部分,是基站与移动台距离的指数函数,具有正偏置的特性,因此TOA测量值越大其误差越大.对所有的TOA测量数据进行分析,仅保留误差最小的3个,然后再采用最小二乘(LS)法估计移动台的坐标.仿真结果表明,该TOA数据处理方法能够明显改善NLOS传播环境下的定位精度,在系统测量误差较小时对LOS传播条件下的定位精度几乎没有影响. 相似文献
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本文基于移动通信环境中非视距(NLOS)传播时延服从指数分布的特性,提出了一种有效减小NLOS影响的定位方法.该方法首先利用测量的波达时间(TOA)和NLOS传播时延的统计特性估计由NLOS引起的附加时延;然后从测量的波达时间中减去附加时延,得到对LOS传播时间的估计,进而估计移动台的位置;最后,对不同时刻估计的移动台位置进行平滑处理,进一步减小NLOS的影响.采用该方法对移动台的位置进行的估计是一种无偏估计,不需要增加系统成本,计算简单,是一种非常实用的定位方法.仿真结果证明了该方法的有效性. 相似文献
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为抑制非视距传播造成的定位误差,提出一种基于对各基站TOA测量结果进行NLOS判别的误差抑制算法。与传统基于TOA统计信息的NLOS抑制不同,算法直接利用移动台多天线接收数据判别基站视距状态,然后融合LOS和NLOS基站测量结果解算移动台位置。NLOS判别机制采用多天线接收数据估计信道莱斯K因子,利用K因子在LOS/NLOS下服从的不同概率分布在信号处理层面对NLOS基站进行判别。算法最后采用约束最优化方法融合识别后的LOS和NLOS基站的TOA测量结果解算移动台位置。仿真结果表明,所提融合NLOS基站TOA解算算法可有效提高NLOS存在时的定位精度。 相似文献
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In urban environment with serious blocking of direct paths, the non-line-of-sight (NLOS) propagation influences the location estimation accuracy. In this article, a novel algorithm is developed, which can mitigate the NLOS errors in location estimation significantly. Utilizing multiantenna array, the information of scatterers that cause the NLOS propagation is obtained. Then, we combine the information with TOA/TDOA based location algorithm to estimate the location of mobile station (MS). The simulation results show that our method can mitigate NLOS errors and enhance the location accuracy greatly. 相似文献
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适用于NLOS传播环境的几何定位方法 总被引:3,自引:0,他引:3
基于非视距传播(NLOS)的影响,移动通信环境中波达时间(TOA)的测量误差具有正偏置的特性,本文提出了一种简单的几何定位方法。该方法根据基站分布和TOA测量数据确定出若干个定位点,对这些点的坐标取平均值即得到移动台的位置估计。仿真结果表明,该方法能够有效提高NLOS传播环境下的定位精度,对LOS传播条件下的定位精度影响小。 相似文献
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减轻TOA和AOA定位系统非视距影响的方法 总被引:4,自引:0,他引:4
结合圆位置线误差、直线位置线误差与参数误差的关系,该文提出了一种利用所有基站测量的波达时间与最近一个基站测量的所有多径的到达角进行混合定位的方法.在该方法中,对波达时间用测量的波达时间总是大于等于视距传播时间进行约束,对到达角用GBSBCM确定的最大角度扩展进行约束,以有效减小非视距传播的影响,提高定位精度.仿真结果证明了该方法的有效性。 相似文献
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The problem of locating a mobile terminal has received significant attention in the field of wireless communications. The wireless location problem is made difficult by nonsymmetric contamination of measured Time of Arrival (TOA) data caused by Non-Line-Of-Sight (NLOS) propagation. In this paper, a novel robust NLOS error mitigation algorithm based on minimum entropy estimation is proposed without prior statistics knowledge of NLOS propagation error.We compare the proposed algorithm with two additional ones, the Normal Least-Squares estimator and the Huber estimator, through MATLAB simulation in different COST 259 channel environment. Results reveal that the proposed algorithm is more robust to NLOS error than the other two, although it is not always superior to the other two on location accuracy. 相似文献
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针对室内定位,当信号受到非视距(non-line-of-sight, NLOS)和多径传播的影响时,本文提出一种接收信号强度(Received Signal Strength, RSS)协助的Ray-tracing室内定位算法,改进已经提出的基于虚拟基站方法的信号到达时间 (Time of Arrival, TOA)和信号到达角度(Direction of Arrival, DOA)室内无线信号Ray-tracing模型,利用信号RSS测量值优化算法,实现TOA、DOA和RSS协同定位,提高室内多径及非视距环境下,无线定位的精度,降低算法复杂度,提高算法处理信号多重散射的能力并降低了对基站的依赖性适用环境更为广泛。首先通过RSS得到信号源可能存在的位置,随后利用Ray-tracing原理并使用虚拟基站,将非视距路径定位问题转化为视距路径定位问题,利用TOA和DOA对直射、透射、反射和绕射情况进行分析建模,最后使用最小二乘法对可能的位置进行筛选,得到信号源的最终位置。仿真结果表明,本算法较改进前拥有更高的定位精度。 相似文献
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Santiago Mazuelas Francisco A. Lago Patricia Fernandez Alfonso Bahillo Juan Blas Ruben M. Lorenzo Evaristo J. Abril 《Wireless Personal Communications》2010,53(1):35-52
The presence of non-line-of-sight (NLOS) propagation is a key issue that limits the accuracy of wireless location systems.
The lack of direct sight causes the measurements obtained by location systems to be so unpredictable that they can produce
high inaccuracies in the estimation of the mobile station location. In this paper we propose a novel technique to improve
location reliability and accuracy in cases where NLOS propagation is present. For that, in registers of time of arrival (TOA)
measurements taken from each base station (BS) in view, we detect the presence of NLOS propagation and estimate the ratio
of the measurements coming from NLOS propagation. With this estimate we can assess how much is NLOS propagation affecting
the measurements taken from each BS and then we can identify the best measurements and BSs to achieve the highest accuracies
in location. 相似文献
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In this paper, a modified time‐of‐arrival (TOA) estimation error test and a hybrid time‐of‐arrival/angle‐of‐arrival (TOA/AOA) estimation error test for identification of line of sight (LOS) base stations (BSs) are proposed. The proposed schemes aim to improve the location accuracy of wireless location systems suffering from the non‐line of sight (NLOS) propagation errors. The modified TOA‐based estimation error test is considered a straightforward approach in identifying the LOS‐BS set when the number of LOS BSs is greater than or equal to three. When both TOA and AOA metrics are available, hybrid TOA/AOA squares of normalized estimation errors are formulated by adopting the approximate maximum likelihood (AML) estimation. The proposed hybrid estimation error test scheme is capable of identifying the LOS/NLOS status of each BS, and performing location estimation in the situation where only two LOS BSs exist. Simulation results show that the proposed schemes are capable of correctly identifying the LOS BSs and improving the overall location accuracy. Copyright © 2009 John Wiley & Sons, Ltd. 相似文献
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一种改进的NLOS环境下的TDOA/AOA混合定位算法 总被引:3,自引:1,他引:2
在蜂窝移动通信系统中,利用基站测量的到达时间差(TDOA)和电波到达角(AOA)的混合定位方法能够比传统的TDOA方法提供更高的定位精度。但是在非视距(NLOS)条件下,当AOA的测量误差超过一定值时,定位的误差仍然很大。该文根据NLOS传播环境下附加传播时延服从指数分布的特性,估计附加时延的均值和方差,对TDOA测量值进行重构,再以AOA方法进行辅助定位。仿真结果表明,该算法能显著提高传统的TDOA和TDOA/AOA方法在NLOS传播环境下的定位精度。 相似文献
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Non-line-of-sight(NLOS)propagation is a major source of error for accurate time-of-arrival(TOA)location estimation.The two-step least square(LS)method,which does not need any information about the distribution of the NLOS error,has been studied in related researches to provide efficient location estimation of the mobile terminal(MT).By observing the estimation of the error covariance matrix in the two-step LS method,this paper finds that the measured distances are more suitable than the initial estimated distances by maximum likelihood(ML)algorithm in NLOS environments.Moreover,by making use of the geometry relations among fixed terminals(FTs),some measured distances which are corrupted by big NLOS errors may be reduced.Further,an iteration method can be adopted to further improve the performance of the algorithm.Accordingly,an improved algorithm based on the two-step LS method is proposed.Simulation results demonstrate that the improved algorithm has better performance than the two-step LS method and converges more quickly.Meanwhile,it is robust in different NLOS environments. 相似文献
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Guo-Lin Sun Wei Guo 《Communications Letters, IEEE》2004,8(8):509-510
Mobile positioning is made difficult by nonsymmetric contamination of measured time-of-arrival (TOA) data caused by non-line-of-sight (NLOS) propagation. In this letter, a robust NLOS error mitigation algorithm based on Bootstrapping M-estimation is proposed without prior NLOS error distribution. A simulation comparison is performed in different channel environments between the proposed algorithm and two additional ones (least-square and Huber estimator). The proposed algorithm clearly outperforms the other two. 相似文献
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Improved TOA‐Based Localization Method with BS Selection Scheme for Wireless Sensor Networks 下载免费PDF全文
The purpose of a localization system is to estimate the coordinates of the geographic location of a mobile device. The accuracy of wireless localization is influenced by non‐line‐of‐sight (NLOS) errors in wireless sensor networks. In this paper, we present an improved time of arrival (TOA)–based localization method for wireless sensor networks. TOA‐based localization estimates the geographic location of a mobile device using the distances between a mobile station (MS) and three or more base stations (BSs). However, each of the NLOS errors along a distance measured from an MS (device) to a BS (device) is different because of dissimilar obstacles in the direct signal path between the two devices. To accurately estimate the geographic location of a mobile device in TOA‐based localization, we propose an optimized localization method with a BS selection scheme that selects three measured distances that contain a relatively small number of NLOS errors, in this paper. Performance evaluations are presented, and the experimental results are validated through comparisons of various localization methods with the proposed method. 相似文献