信道質量和服務質量（QoS）是無線體域網的兩個重要挑戰。本文旨在研究信道特性和在保證高吞吐率和低數據弛豫時間前提下探索低功耗WBAN系統策略。本論文的貢獻在於三個方面。首先研究人體信道（HBC）特性。作為IEEE標準802.15.6定義的三種PHY層之一，HBC已經作為體表傳感器通信媒介被廣泛研究。但是，HBC的詳細機理至今仍然不夠明朗，特別是對於那些采用了體內傳感器的應用更少人涉足。因此，我們為此專門預設四種應用場景，並在場景中測量實際信道特性。依據測量結果，我們觀測到數個影響信道質量的因素。其次，我們提出了一種專門針對WBAN的信道建模方法。該方法依賴於對人體組織的直接測量結果，並且此建模方法在建模過程中兼顧體表通信和體內通信。該建模方法包括兩個階段，第一階段是構建人體各部分的子模型，在第二階段調用先前構建之子模型並依賴信號衰減特性來構造上層模型。最終得到的模型包含兩個自變量：頻率和信道長度，從而可應用此模型同時預測不同頻率和不同長度條件下的信道特性。在設計的實驗中，結果表明該模型具有良好的精度，在10 kHz到60 MHz的頻率範圍內，最差的誤差為2.5 dB。除此之外，我們還在一個演示系統中對信道進行了測試，尤其是誤碼率（BER）和信號衰減情形。該測試結果也顯示出該模型所具有的良好預測性。第三，我們提出了一種關註QoS的WBAN系統優化方法。在IEEE標準中定義了數種不同存取模式（Access mode）和存取方式（Access method）。為了提高功率效率，我們著重研究了數據壓縮對系統總功率的影響，另外還對系統吞吐率建立了分析模型。仿真結果顯示，在一定條件下，數據壓縮對功耗降低具有良好功效，另外采用較高數據傳輸速率會對功耗存在改進作用。當數據壓縮模塊的壓縮率超過2倍，而功耗低於收發器的40%時，插入數據壓縮模塊可以確保整個系統消耗更低能源。 / Channel loss and maintaining the Quality of Service (QoS) are two of the major challenges in realizing an effective Wireless Body Area Network (WBAN). This thesis studies the body channel characteristics and proposes a methodology to improve energy efficiency for an entire WBAN system to achieve high throughput and low data latency. Three main contributions are made in this thesis. Firstly, we focus on human body channel (HBC). HBC, as a possible PHY layer for IEEE standards 802.15.6, has been found useful in networking on-body sensors. However, the HBC channel dynamics is not well understood and this is particularly the case when transceivers implanted inside a human body are involved. To this end, channel measurements were performed on real subjects under four different scenarios so that factors affecting channel quality could be identified. Secondly, a channel modelling methodology is proposed for body area network that takes into account the body structure and the dielectric properties of human tissues; this represents the first modelling effort to cover both in-body and on-body communications in vivo. The proposed modelling method composes of two phases: sub-model construction and top-level model construction. The constructed model is a function of two variables, frequency and channel length, enabling channel impedance prediction with respect to either frequency or channel length. Meanwhile, experimental results show that good model accuracy, a maximum error of 2.5 dB, can be achieved in frequencies range from 10 kHz to 60 MHz. In this endeavor, a modified HBC development system was used to measure bit error rate (BER) and signal attenuation during transmission. The measurements show a good match against simulation results and the channel model. Thirdly, a power optimization technique is proposed for the WBAN. The latest IEEE standard 802.15.6 defines several access modes and access methods together with new power management schemes and frame structures. To improve the power efficiency of a body area network, the merit of having data compression was investigated. For this purpose, an analytical model was developed to evaluate the power efficiency of a BAN system. Simulation results show that good power efficiency can be achieved by employing data compression. It is evident that higher data rate can also help improve energy efficiency. When the compression factor is larger than 2, better energy efficiency can be guaranteed by introducing a data processing unit in a sensor node as long as its power consumption is limited to 40% of that of the transceiver unit. / Detailed summary in vernacular field only. / Ai, Yanqing. / Thesis (Ph.D.) Chinese University of Hong Kong, 2014. / Includes bibliographical references (leaves 126-135). / Abstracts also in Chinese.
| Identifer | oai:union.ndltd.org:cuhk.edu.hk/oai:cuhk-dr:cuhk_1077671 |
| Date | January 2014 |
| Contributors | Ai, Yanqing (author.), Choy, Oliver C. S (thesis advisor.), Chinese University of Hong Kong Graduate School. Division of Electronic Engineering, (degree granting institution.) |
| Source Sets | The Chinese University of Hong Kong |
| Language | English, Chinese |
| Detected Language | English |
| Type | Text, bibliography, text |
| Format | electronic resource, electronic resource, remote, 1 online resource (3 unnumbered leaves, xiv, 145 leaves) : illustrations (some color), computer, online resource |
| Rights | Use of this resource is governed by the terms and conditions of the Creative Commons “Attribution-NonCommercial-NoDerivatives 4.0 International” License (http://creativecommons.org/licenses/by-nc-nd/4.0/) |
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