Abstract: Concerning ranging difficulties with 60GHz signals in Non Line of Sight (NLOS) conditions, a new positioning algorithm based on beamforming in Wireless Local Area Network (WLAN) was proposed. Firstly, the beamforming technology was applied to search the strongest path by adjusting receiving antennas along the channel path with the maximum power.The searching robustness was enhanced and the location coverage was expanded. Secondly, the time delay bias in NLOS conditions was modeled as a Gaussian random variable to reconstruct the NLOS measurements. Finally, to further improve the positioning accuracy, the outlier detection mechanism was introduced by setting a reasonable detection threshold. The localization simulation experiments were conducted on Matlab using STAs-STAs (STAtions-STAtions) channel model, the Time of Arrival (TOA) localization algorithm based on traditional coherent estimation method achieved the average positioning error at about 2m, and the probability of 1m localization accuracy was just 0.5% under NLOS conditions, while the proposed algorithm achieved the average positioning error at 1.02cm, and the probability of 1m localization accuracy reached 94%. Simulation results show that the beamforming technology is an effective solution to 60GHz localization in NLOS conditions, and the localization accuracy and the probability of successful localization are effectively improved.

Key words: GHz signal, Non Line of Sight (NLOS)positioning algorithm, beamforming, strongest path search, outlier detection

摘要： 针对60GHz信号在非视距（NLOS）环境下测距困难的问题，提出一种基于波束成形的60GHz无线局域网络（WLAN）定位算法。首先，通过借助波束成形技术进行最强路径搜索，波束成形算法将天线的最大增益方向指向接收最强多径信号的方向，在增强搜索鲁棒性的同时扩大了定位覆盖范围；然后，对NLOS条件下的时延偏差进行建模，重构NLOS测量数据；最后，为进一步提高定位精度，设置检测阈值，引入异常值检测机制。采用Matlab仿真平台在STAs-STAs信道模型进行仿真，结果表明，NLOS环境下基于传统相干估计的到达时间（TOA）定位算法的定位误差约为2m，定位成功率仅为0.5%，而采用基于波束成形的60GHz定位算法后，定位误差降低至1.02cm，定位成功率高达94%。因此，波束成形技术为NLOS环境下的60GHz定位提供了解决思路，有效地提高了60GHz室内定位精度和定位成功率。

关键词: GHz信号, 非视距定位算法, 波束成形, 最强路径搜索, 异常值检测