[论文解读] BioPhysical Modeling, Characterization and Optimization of Electro-Quasistatic Human Body Communication

Shovan Maity, Mingxuan He+4 more|arXiv (Cornell University)|May 14, 2018

Wireless Body Area Networks参考文献 15被引用 10

一句话总结

本文提出了一种集总参数生物物理模型，用于电准静态人体通信（HBC）以解决先前信道测量中的不一致问题。结果表明，接收端终端阻抗对信道损耗具有关键影响，其中电容性终端可降低低频损耗，并实现从13 kHz起的平坦传输函数，证实当正确终端匹配时，人体可作为可穿戴及植入式设备的宽带通信信道。

ABSTRACT

Human Body Communication (HBC) has emerged as an alternative to radio wave communication for connecting low power, miniaturized wearable and implantable devices in, on and around the human body which uses the human body as the communication channel. Previous studies characterizing the human body channel has reported widely varying channel response much of which has been attributed to the variation in measurement setup. This calls for the development of a unifying bio physical model of HBC supported by in depth analysis and an understanding of the effect of excitation, termination modality on HBC measurements. This paper characterizes the human body channel up to 1MHz frequency to evaluate it as a medium for broadband communication. A lumped bio physical model of HBC is developed, supported by experimental validations that provides insight into some of the key discrepancies found in previous studies. Voltage loss measurements are carried out both with an oscilloscope and a miniaturized wearable prototype to capture the effects of non common ground. Results show that the channel loss is strongly dependent on the termination impedance at the receiver end, with up to 4dB variation in average loss for different termination in an oscilloscope and an additional 9 dB channel loss with wearable prototype compared to an oscilloscope measurement. The measured channel response with capacitive termination reduces low frequency loss and allows flat band transfer function down to 13 KHz, establishing the human body as a broadband communication channel. Analysis of the measured results and the simulation model shows that (1) high impedance (2) capacitive termination should be used at the receiver end for accurate voltage mode loss measurements of the HBC channel at low frequencies.

研究动机与目标

• 解决由于激励和终端设置不同而引起的先前HBC信道测量中的差异。
• 建立人体作为电准静态HBC通信信道的统一生物物理模型。
• 表征HBC性能至1 MHz，并评估其在宽带通信中的潜力。
• 确定最优接收端终端条件，以实现低频电压损耗测量的准确性。
• 通过示波器和微型可穿戴原型实验验证模型。

提出的方法

• 基于生理和电学特性，开发了人体信道的集总元件生物物理模型。
• 使用示波器和自定义微型可穿戴原型进行电压损耗测量，以比较不同终端的影响。
• 在接收端应用电容性终端，分析其对低频信道响应的影响。
• 在不同终端阻抗和测量平台下进行实验验证。
• 利用仿真与测量数据，关联终端条件与信道损耗变化。
• 分析传输函数，评估带宽平坦度和低频性能。

实验结果

研究问题

• RQ1 接收端终端阻抗如何影响低频下测得的HBC信道损耗？
• RQ2 测量设置中的非共地效应如何影响HBC信道表征？
• RQ3 电容性终端能否使HBC传输函数平坦化，并将可用带宽扩展至更低频率？
• RQ4 测量平台（如示波器与可穿戴原型）在多大程度上影响观测到的信道响应？
• RQ5 如何通过统一的生物物理模型解释先前HBC测量中的差异？

主要发现

• 使用示波器时，信道损耗因终端阻抗不同而变化高达4 dB。
• 由于非共地效应，使用可穿戴原型相比示波器测量额外增加了9 dB的信道损耗。
• 电容性终端可降低低频损耗，并实现从13 kHz起的平坦传输函数。
• 在接收端采用高阻抗电容性终端，对于准确测量低频电压模式损耗至关重要。
• 集总生物物理模型通过准确表征终端和激励效应，成功解释了先前HBC研究中的关键差异。
• 当正确终端匹配时，人体可支持高达1 MHz的宽带通信，且在13 kHz以下可实现平坦的频率响应。