废墟环境2.4GHz无线信道测量与时延扩展研究

利用手机WiFi信号对震后被困人员进行定位是灾后搜救的重要手段之一，但定位精度依赖废墟环境无线信道模型的精确性，目前国内尚缺乏废墟环境下WiFi信号传播的信道模型。相对于典型通信环境，震后废墟中信号传播环境更为复杂，多径效应更为明显，将会严重影响信道的时延扩展。在对北川灾后废墟环境下2.4 GHz WiFi通信频段信道进行频域测量的基础上，对数据进行预处理，并计算平均附加时延和RMS时延扩展参数。基于概率密度函数分析了均方根(root mean square,RMS)时延扩展的分布规律，并根据Kolmogorov-Smirnov,Chi-square和Anderson-Darling 3种法则进行拟合优度检验，得出RMS时延扩展服从正态分布。进一步分析得出平均附加时延和RMS时延扩展呈线性关系，实测得到的信道时延扩展参数可为基于手机WiFi定位的灾后人员搜救系统的设计提供有效参考。

Channel measurement and delay spread for 2.4 GHz radio channel in ruins environment

Locating the trapped people using mobile phone WiFi is an important means of emergency search and rescue, however, the positioning precision depends on the accuracy of the radio channel model of the ruins environment. Unfortunately, there is a lack of channel model for WiFi signal propagation in ruins. Compared with the typical communication environment, the signal propagation environment in ruins is more complex, and the multipath effect is more obvious, which will seriously affect the channel delay spread. Based on the measurement campaign in frequency domain conducted in 2.4 GHz band in ruins scenarios of Beichuang city, data preprocessing was conducted to obtain the mean delay spread and RMS delay spread. The distribution of RMS delay spread was studied by using probability density function. According to the evaluation results of the Kolmogorov-Smirnov , Chi-square and Anderson-Darling tests, RMS delay spread follows normal distribution well. Moreover, the mean delay spread and RMS delay spread has been investigated and they behaved significant linear dependency, and the delay spread parameters is reliable, which can provide effective reference for the design of rescue system based on mobile WiFi positioning.