【作者】 马力；

【导师】 孙玲玲； 沈海斌；

【作者基本信息】 浙江大学 ， 电路与系统， 2013， 博士

【摘要】 人体通信是一种依托人体作为信号传输通道的新型近场通信方式,其作为实现普适计算的关键技术之一,因低功耗、结构简单和安全性好的优势将在众多领域中得到广泛应用。而表面波导人体通信凭借其在高速通信方面的优势,迅速成为了人体通信研究领域中的热点。但是当前的表面波导人体通信研究存在两个问题：首先是研究中对人体的建模并不精确,因而人体通信信号内在的传输机制尚不明确。同时研究中通常使用基于经验的人工参数调节方法来对通信装置进行优化,未将建模研究的成果应用于优化问题中。以上问题限制了人体通信系统性能的提升。为了解决这些的问题,本文利用电磁场正问题和逆问题的分析方法,从理论与应用两方面对表面波导人体通信建模问题进行了深入的研究,主要包括以下四个方面：1)表面波导人体通信电磁场求解方法分析(建模理论研究)为了有效分析表面波导人体通信的建模问题,本文首先建立了一套系统的人体通信信号传输机制的求解方法。其中圆柱坐标系下的分层介质表面波导理论被选择为本文中的电磁场解析求解方法,而四面体棱边有限元法和基于Helmholtz方程弱形式的Galerkin加权余量法被选择为本文中的电磁场数值求解方法。这些求解方法构成了对人体通信建模问题进行研究的理论基础和分析手段,这也是在人体通信研究领域对电磁场求解方法首次系统性地总结。2)表面波导人体通信模型研究(建模理论研究)为了解决现有人体通信理论模型存在的建模不精确和通信机理不明确的问题,本文根据人体的实际情况,使用电磁场的解析求解方法提出了一种基于分层介质圆柱表面波导理论新型的人体通信理论模型。同时,与理论模型对应的人体数值模型的计算结果被用来佐证理论模型计算结果的正确性。通过计算结果可知,本文提出的新型人体通信理论模型无论从预测变化趋势方面还是计算精度方面均明显优于现有理论模型。该模型是目前表面波导人体通信研究领域最为精确的理论模型,能够完整的刻画电磁波在人体表面的传输机制,可为优化表面波导人体人体通信信号分布和提高系统性能提供理论依据。3)人体通信模型简化问题研究(建模理论研究)人体通信装置的逆优化问题需要大规模的人体模型计算,而前一部分提出的人体通信理论模型和数值模型的计算复杂度较大,这成为了将模型研究的结论应用于人体通信装置优化问题的瓶颈之一。为了解决这一问题,本文对人体通信模型的简化问题进行了详细的研究,提出了一种简化人体通信数值模型。相比于标准的表面波导人体通信数值模型,该简化人体数值模型可在保持88%的计算精度的前提下将计算时间减少2/3,非常适合用于对人体通信信号的传输特性进行快速估计。模型简化研究的结论将被应用于对人体通信信号发射器的优化中,使得计算时间从原来的62.5天,减少到20.8天,大大提高了计算效率。4)人体通信发射器设计与逆优化研究(建模应用研究)现有的表面波导人体通信信号发射器一般是通过基于经验的人工参数调整方法来实现性能优化,因而存在集成性差和信号强度低、发射效率差两方面的缺陷。为了解决以上问题,本文首次将电磁场逆优化问题和人体数值模型引入人体通信装置设计与优化研究中,首先提出了一种基于印制电路板工艺的集成式人体通信信号发射器,然后使用电磁场逆优化方法对前文中提出的集成式信号发射器的信号强度和信号发射效率两方面的性能指标进行了优化。经过优化,集成式信号发射器在有效通信距离内的信号幅值是现有发射器的7.4倍以上,而其信号发射效率约是现有发射器的3.3倍。电磁场逆优化方法大大提高人体通信系统的整体性能,也将促进人体通信硬件和装置研究领域的发展。更多还原

【Abstract】 Human Body Communication (HBC) is an emerging communication technology that uses human body as transmission channel. As an inevitable part of Pervasive Computing technology, HBC will be used widely in many application fields. In high speed communication application, surface waveguide HBC have extremely high performance and is becoming hot spot rapidly in relative research domains. But in the domain of surface waveguide research, there are also fundamental flaws like imprecise theoretical model and unclear transmission mechanism of signal. Also the achievements of HBC modeling research have not been used in the design and optimization of HBC equipment. To solve such problems, we take in-depth study on modeling theory and modeling application of HBC by direct and inverse analysis of electromagnetic problem.1) Analysis System of Surface Waveguide HBCTo analyze the modeling of Surface Waveguide HBC effectively, we propose an analysis system based on analytical method and numerical method of electromagnetic fields. The theory of waveguide on stratified media is chosen as analytical method, and the edge-based FEM and Galerkin weighted residual method are used as numerical method. The analysis system is the theory foundation and analysis method of this paper.2) Model of Surface Waveguide HBCTo solve the problem of imprecise theoretical model and unclear signal transmission mechanism in existing Surface Waveguide HBC research, a theoretical model based on stratified media cylinder is presented. A numerical model analyzed by Finite Element Method (FEM) is used for comparison and validating the theoretical model. Results of theoretical and numerical models shows that the new theoretical model proposed in this paper is superior to existing theoretical models in both calculation accuracy and prediction of trend, and is able to characterize accurate propagation mechanism of HBC signal. The propagation mechanism derived from the theoretical model is useful to provide design information for the transmitter and the modeling of the propagation channel in HBC.3) Research on the Simplification of HBC ModelIn the optimization of HBC equipment, theoretical and numerical model proposed in last part cost too much time and calculation resource. To solve this problem, we take a in-depth study in the calculation efficiency and simplification of HBC model, and propose a simplified numerical model of HBC. The calculation time of the simplified numerical model is just1/3of the complete numerical model, which keeps88%accuracy. The simplified numerical is very useful for fast evaluation of transmission mechanism of HBC signal and will be used for optimization of signal transmitter.4) Design and Inverse Optimization of Signal TransmitterThe existing signal transmitter of HBC is badly in integration of transmitter structure and efficiency and intensity of HBC signal. In prior studies, researchers often used direct analysis method of electromagnetic field, which did not achieve a good result. To solve those problems above, we introduce the inverse analysis into research of Surface Waveguide HBC. A new structure of signal transmitter is proposed to enhance the integration of transmitter, and the inverse optimization method based on NSGA-II algorithm is used to optimize the new structure of transmitter for efficiency and intensity. After optimization, the intensity and efficiency of new transmitter is much better than the existing transmitter.更多还原