为观察位置不准确的主要原因

代码说明：

The main reason for inaccuracies observed in location estimation, imposed by the propagation conditions of the wireless channel, is the Non Line Of Sight (NLOS) due to transmitted signal blocking. Because of the NLOS, the first TOA, which bears information related to the mobile terminal position, suffers stronger attenuation than later arrivals and therefore wrong timing information is obtained yielding biased position estimation. Several NLOS mitigation algorithms have been presented. One of the most common approaches consists of correcting the TOA measurements exploiting the fact that the variance of the TOA measurements is significantly increased in NLOS scenarios