复杂室内环境下基于CSI的定位方法

信道状态信息(CSI, channel state information)可以提供更详细具体的子载波信息,在室内定位技术领域引起研究人员的关注和重视。针对传统室内定位方法在复杂室内环境下准确性及稳定性方面的不足,提出了一种可以用于复杂室内环境的定位方法,命名为Com Loc。主要解决了复杂环境中无线信号多径效应和噪声干扰对定位精度的影响,并讨论了CSI信号存在的误差,分析CSI相位信息对室内环境的敏感性,提出可信载波链路的思想,通过相位差选取可靠、稳定的链路信号来减少对位置的误判,同时对CSI的相位误差进行校准,提取信号变化的特征。实验结果分析表明,Com Loc在室内复杂环境下的定位结果具有高效性和有效性。

Sensor array calibration for uniform rectangular array in presence of mutual coupling and sensor gain-and-phase errors

The sensor array calibration methods tailored to uniform rectangular array(URA)in the presence of mutual coupling and sensor gain-and-phase errors were addressed.First,the mutual coupling model of the URA was studied,and then a set of steering vectors corresponding to distinct locations were numerically computed with the help of several time-disjoint auxiliary sources with known directions.Then,the optimization modeling with respect to the array error matrix(defined by the product of mutual coupling matrix and sensor gain-and-phase errors matrix)was constructed.Two preferable algorithms(called algorithm I and algorithm II)were developed to minimize the cost function.In algorithm I,the array error matrix was regarded as a whole parameter to be estimated,and the exact solution was available.Compared to some existing algorithms with the similar computation framework,algorithm I can make full use of the potentially linear characteristics of URA's error matrix,thus,the calibration precision was obviously enhanced.In algorithm II,the array error matrix was decomposed into two matrix parameters to be optimized.Compared to algorithm I,it can further decrease the number of unknowns and,thereby,yield better estimation accuracy.However,algorithm II was incapable of producing the closed-form solution and the iteration operation was unavoidable.Simulation results validate the excellent performances of the two novel algorithms compared to some existing calibration algorithms.

A NOVEL ADAPTIVE ALGORITHM OF CPE CORRECTION FOR OFDM SYSTEMS

On the basis of the analysis of the effect of PHase Noise (PHN) and Common Phase Error (CPE) on Orthogonal Frequency Division Multiplexing (OFDM) systems, a cost function is constructed. By the cost function and the idea of Least-Mean-Square (LMS) adaptive algorithm, the adaptive algorithm for the correction of CPE is presented. The simulations have been performed to investigate the performance for tracking PHN and estimating CPE, the results show that the algorithm performs soundly.