室内信道环境下UWB精确测距研究

Research on accurate ranging of UWB under indoor environments

研究了IEEE 802.15.4a室内信道环境下UWB(ultra wideband)信号的精确测距能力。提出了一种改进的基于区间搜索和门限比较的TOA(time of arrival)估计算法。基于对CM1和CM2信道实现的部分参数的统计分析,建立了TOA估计误差的概率模型,并由此给出了通过将误差概率控制到最低的算法门限设置方案。通过仿真考察了不同信噪比下测距结果的平均绝对误差。结果表明,UWB在室内信道条件下要获得厘米级的测距精度,接收信号须保证足够高的信噪比,但信噪比提高到一定程度后测距性能并不会进一步提升,此结论对于设计满足一定精度需求的定位算法以及实际测距中控制信号的传输功率具有一定的指导意义。

The accurate ranging ability of ultra wideband （UWB） signal under IEEE 802.15.4a indoor channel model was studied. An improved time-of-arrival （TOA） estimation algorithm which utilizes region search and threshold comparison was proposed. By statistical analysis on certain characteristics of the CM1 and CM2 channel profiles, the probability model of TOA estimation error was deduced. The thresholds of the proposed TOA estimation algorithm were then set by limiting the error probability to the lowest level. The mean absolute ranging errors under different SNR were simulated. Results show that high enough SNR should be guaranteed in order to obtain centimeter-level ranging precision under in- door environments, while extremely high SNR would not help to improve the ranging precision any more but lead to a performance floor. The results have instructional significance on designing localization algorithms and transmission power control in practical ranging.