Maximum likelihood TOA and OTDOA estimation with first arriving path detection for 3GPP LTE system
Maximum likelihood TOA and OTDOA estimation with first arriving path detection for 3GPP LTE system
复制标题
3GPP LTE 系统的最大似然 TOA 和 OTDOA 估计以及首达路径检测
DOI：
10.1002/ett.2871
复制
发表时间：
2016
影响因子：
3.6
通讯作者：
A. Dammann
中科院分区：
文献类型：
--
作者：
Wen Xu;Ming;Chen Zhu;A. Dammann
美国联邦通信委员会(FCC)已要求无线网络运营商和移动设备为E-911提供准确的位置信息。3GPP LTE版本规定了对到达时间(TOA)和到达时间差(TDOA)测量的要求。9以确保用户设备(UE)的准确定位，即使在恶劣条件下(例如，信道快速变化且信噪比低至−13分贝)。为了满足这些要求，准确估计第一个信号到达路径是至关重要的。在这项工作中，我们首先在没有任何近似的情况下推导出基于不同导频的LTE TOA和TDOA测量的Cramér-Rao下界，当信噪比=−13db时，该下限低至几米。将LTE系统的可实现性能与FCC和3GPP的要求进行了比较，并分析了移动多径信道对测量的影响。然后，我们描述了具有增强的首到达路径检测的LTE TOA和TDOA测量的实用的低复杂度方法。使用基于最大似然的相关轮廓作为检测度量。在通过移动窗口粗略确定信号区域后，采用峰值检测、基于信噪比的阈值和基于噪声底限和度量峰值的自适应阈值三种方法来估计第一到达路径。仿真结果表明，所提出的基于自适应门限的方法能够满足各种现实移动信道下的所有3GPP要求，并且在某些情况下可以获得接近CRLB的性能。版权所有©2014 John Wiley&Sons，Ltd.
The US Federal Communications Commission (FCC) has mandated wireless network operators and mobile devices to provide accurate location information for E‐911. Requirements for time of arrival (TOA) and time difference of arrival (TDOA) measurements have been specified in 3GPP LTE Rel. 9 to ensure accurate user equipment (UE) positioning even under bad conditions (e.g. with channel quickly varying and SNR being as low as −13 dB). To fulfil these requirements, it is vital to accurately estimate the first signal arriving path. In this work, we first derive ‐ without any approximation ‐ the Cramér–Rao lower bound (CRLB) of the LTE TOA and TDOA measurements based on the different pilots, which is shown to be as low as a few metres for SNR = −13 dB. The achievable performance of the LTE system is compared with the FCC and 3GPP requirements, and the impact of mobile multipath channels on the measurements is analysed. Then, we describe practical low‐complexity methods for LTE TOA and TDOA measurements with enhanced first arriving path detection. The maximum likelihood based correlation profile is used as detection metric. After grossly determining the signal region by a moving window, three methods, namely, peak detection, SNR‐based threshold and adaptive threshold based on noise floor and metric peak value are employed to estimate the first arriving path. Simulation results show that the proposed adaptive threshold‐based method can meet all 3GPP requirements under various realistic mobile channels, and can in some cases achieve a performance close to the CRLB. Copyright © 2014 John Wiley & Sons, Ltd.