复杂多径下IR-UWB自适应频偏估计算法研究

Research on Adaptive Clock Frequency Offset Estimation Method for IR-UWB under Complex Multipath

摘要:

在脉冲超宽带定位系统中，时钟频率偏移是影响测距和测角精度的重要因素；针对复杂多径下频偏估计精度低的问题，设计了一种适应复杂多径环境的脉冲超宽带自适应频偏估计算法；首先，借助脉冲超宽带信号的抗多径优势，将实时估计的信道脉冲响应作为自适应匹配滤波模板，以保证复杂多径下相关峰的准确提取；利用相关峰辐角信息得到前导符号的相位序列；再使用贝叶斯估计算法提高频偏估计精度；在IEEE 802.15.4a标准CM1、CM2多径信道下进行仿真，仿真结果表明，低信噪比情况下，频偏估计估计精度保证在0.2 ppm以内；在巷道环境实验结果表明，50 m范围内频偏估计标准差在0.06 ppm以内；实现了复杂多径环境下高精度频偏估计，具有较强的实用性。

Abstract:

In impulse radio-ultra wideband (IR-UWB) positioning system, clock frequency offset is an important factor affecting the accuracy of ranging and angular measurement. Aiming at the problem of low accuracy of frequency offset estimation under complex multipath, an IR-UWB adaptive frequency offset estimation algorithm adapted to complex multipath environment is designed. First, with the advantage of anti-multipath of pulsed ultra-wideband signals, using the real-time estimated channel impulse response as an adaptive matched filtering template. Correct extraction of correlation peaks under complex multipath is guaranteed. Then, the phase sequence of the leading symbols is obtained using the associated peak spoke angle information. Finally, Bayesian estimation algorithm is used to improve the accuracy of frequency offset estimation. Simulations were performed under CM1~CM2 multipath channels in IEEE 802.15.4a standard. The simulation results show that the accuracy of frequency offset estimation can be guaranteed within 0.2 ppm under low SNR. The experimental results in tunnel environment show that the standard deviation of frequency offset estimation is less than 0.06 ppm within the range of 50 m. Highly accurate estimation of frequency offset in complex multipath environments are realized. It has strong practicability in complex multi-path environment.