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首页> 外文期刊>IEEE transactions on wireless communications >Utilization of Multiple-Antenna Multicarrier Systems and NLOS Mitigation for Accurate Wireless Indoor Positioning
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Utilization of Multiple-Antenna Multicarrier Systems and NLOS Mitigation for Accurate Wireless Indoor Positioning

机译：利用多天线多载波系统和NLOS缓解技术来进行精确的室内无线定位

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In this paper, we investigate the performance of wideband orthogonal multicarrier signals in conjunction with multiple antenna systems for wireless indoor positioning. The multiple output orthogonal frequency division multiplexing (OFDM) scheme is used to estimate the propagation time delay and the relative direction of arrival (DOA) of multipath signals. Besides the frequency diversity attributed to OFDM, the antenna array elements can be used in two scenarios: 1) for time delay estimation with spatial diversity and 2) for joint time delay and DOA estimation. To measure the effect of the characteristic parameters of wireless positioning system, the Cramér-Rao lower bound for both scenarios have been derived. In indoor environments, the mobile unit (MU) is often in a non-line-of-sight (NLOS) situation and the direct path could be completely blocked. This degrades the performance significantly. Therefore, we introduce properly weighted least square (WLS) and hybrid WLS estimators to mitigate the effect of undetected direct path channel profiles. An adaptive method is also presented to select the reference base station (BS) and extract certain weights to scale the observations based on the estimated channel profiles. Our experimental results using the emerging IEEE 802.11ac standard reveal that the hybrid time difference of arrival (TDOA) and DOA outperform in non-perfectly synchronized BSs and NLOS environments. However, the achieved accuracy is not improved beyond that obtained by using TDOA with spatial diversity if the BSs are perfectly synchronized. The NLOS mitigation method has been tested using different obstacles with different positions between the MU and the BS. The achieved performance is nearly similar to that of using LOS BSs.
机译：在本文中，我们研究了宽带正交多载波信号与多天线系统一起用于无线室内定位的性能。多输出正交频分复用（OFDM）方案用于估计多路径信号的传播时间延迟和相对到达方向（DOA）。除了归因于OFDM的频率分集以外，天线阵列元件还可以用于两种情况：1）用于具有空间分集的时间延迟估计，以及2）用于联合时间延迟和DOA估计。为了测量无线定位系统的特征参数的影响，已经得出了两种情况的Cramér-Rao下界。在室内环境中，移动单元（MU）通常处于非视线（NLOS）的情况下，直接路径可能会被完全阻塞。这会大大降低性能。因此，我们引入适当加权的最小二乘（WLS）和混合WLS估计器，以减轻未检测到的直接路径信道配置文件的影响。还提出了一种自适应方法，用于选择参考基站（BS）并提取某些权重，以根据估计的信道配置文件缩放观察值。我们使用新兴的IEEE 802.11ac标准进行的实验结果表明，在非完全同步的BS和NLOS环境中，到达时间的混合时差（TDOA）和DOA的性能优于其他。但是，如果BS完全同步，则所获得的精度不会超过使用具有空间分集的TDOA所获得的精度。已使用MU和BS之间不同位置的不同障碍物测试了NLOS缓解方法。所达到的性能几乎与使用LOS BS相似。

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