人体通信信道相位特性研究

Phase Characterization of RF Signal Coupling with Human Body

采用实验统计方法研究人体信道在1 ～200 MHz频段下的传播延时和相位特性.实验采用13名志愿者分别进行4个传播路径的群延时测量,并将测试频段划分为1～100 MHz和100～200 MHz两个子频段进行研究,探讨4个传播路径和两个子频段下的延时特性.统计分析表明：信号在人体通信信道的传播延时和传播路径无关;100 ～ 200 MHz频段内的传播延时均比1～100 MHz内的传播延时大.1～200 MHz频段内相位归一化曲线表明：在20～40 MHz频段信号畸变较大.根据最大似然估计算法（Maximum Likelihood Estimation,MLE）和Akaike信息量准则（Akaike Information Criterion,AIC）,信号相位归一化偏差值符合Lognormal分布.

To continuously monitor health information using wireless sensors placed on a person is a promising application. Human body communication （HBC） is proposed as a low power, security and light-weight communication technology that could be applied in aforementioned applications. In this pa- per, the characteristic of HBC propagation delay and phase deviation are investigated for the first time in the frequency bands： 1 -200 MHz. In order to investigate the propagation delay in different transmit paths and different frequency bands, the 1 -200 MHz frequency band is divided into two sub- bands ： 1 -100 MHz and 100 - 200 MHz and the four measurement paths are set on every volunteer. The statistical analysis of measurement date show that the propagation delay is independent on transmit path. However, from 1 MHz to 100 MHz the delay is generally longer than that in the frequency band 100 - 200 MHz. The normalized phase deviation curve indicates that the phase deviation is larger in frequency band 20- 40 MHz compared with other measured frequency band. Lognormal model is found to be the best fitting dislribution for the normalized phase deviation according the Maximum Likeli- hood Estimation （MLE） and Akaike Information Criterion （AIC）.