用於穿戴式裝置之低功耗藍芽傳輸方法的比較與評估

Abstract

隨著越來越多的裝置連到網際網路，物聯網(IoT)有著大幅度的成長。根據Gartner所作的市場調查報告，在2020年時物聯網裝置的數量將達到250億個。在這些聯網裝置裡有一項新興的產品稱為穿戴式裝置。”穿戴式裝置”指的是可以配戴在人體上的電子配件。某些穿戴式裝置的運算能力像智慧型手機一樣強大，如智慧手錶，而另一些是配備著微控制器較單純的裝置。本論文專注後者那類型的穿戴式裝置及其應用。 應用在穿戴式裝置上的無線通訊技術需要考量較持久的電池續航時間。因此有低耗電特性的低功耗藍芽(BLE)已成為應用於穿戴式裝置上最常用的無線通訊技術。在本研究中我們專注探討用在穿戴式裝置與oneM2M聯網平台之間BLE的通訊技術。 我們評估了三種不同用在穿戴式裝置與oneM2M聯網平台的BLE通訊設計  第一種設計是源自於oneM2M的標準，它描述了傳統設備如何與現有的oneM2M聯網平台作整合與互通。使用BLE的穿戴式裝置被視為傳統設備因此需要使用IPE (Inter-working Proxy Application Entity) 作為中介層去進行不同應用層協定之間的轉換例如BLE-HTTP或BLE-CoAP。  第二種設計利用了BLE可編程的功能。它在BLE裝置的Generic Attribute Profile (GATT) 下創建一個新的服務與oneM2M聯網平台互通。在oneM2M聯網平台裡也需要增加負責BLE傳輸的功能。在該設計中不再需要使用IPE且穿戴式裝置可以與oneM2M聯網平台直接通信。  第三種設計是基於Internet Engineering Task Force(IETF)的RFC 7668和BLE Special Interest Group (SIG)的 Internet Protocol Support Profile (IPSP) 這兩份標準文件，它定義了6LoWPAN (IPv6 over Low-power Wireless Personal Area Network) over BLE。因此CoAP/6LoWPAN現在可以被用來作為終端裝置與oneM2M聯網平台之間的通訊協定。

上述三種設計使得BLE穿戴式裝置能夠與oneM2M聯網平台互通。我們的研究去比較和評估了這三種設計的主要特性與行為同時探討了其關鍵指標如：電能消耗、系統效能、傳輸效率和設計的複雜度。我們的研究可以決定哪一項特定的設計對於穿戴式裝置在不同的系統設計需求下是最適用的。

The Internet of Thing (IoT) is growing significantly with more devices connected to the Internet. According to the market report of Gartner, the number of connected IoT devices will reach 25 billion in 2020. One emerging group of these is called wearable devices. The term “wearable devices” refers to electronic accessories, which can be worn on the human body. Some wearable devices are as powerful as a smart phone in their capability such as smart watch, while others are more primitive and only equipped with a microcontroller. In this thesis we focus on wearable devices of the latter category and their applications. The wireless technologies used by wearable devices need to consider the long lasting of battery life. Consequently, Bluetooth Low Energy (BLE) has emerged as the wireless technologies for wearable devices due to its features of low power consumption. In this research we focus on enabling technologies that will facilitate seamless communications between the wearable devices and the M2M platform based on BLE. In our research we evaluate three different designs to enable communications between the wearable devices and the oneM2M platform.  The first design is from oneM2M standard, which describes how the legacy devices can be integrated and interwork with the oneM2M platform. The BLE wearable devices are regarded as legacy devices and require an IPE (Inter-working Proxy Application Entity) as an intermediary for protocol translation between BLE and an application-layer protocol such as HTTP or CoAP.  The second design utilizes the programmable feature of BLE. It creates a new service under the Generic Attribute Profile (GATT) in the BLE device to interwork with the oneM2M platform. It also requires the addition of the BLE transport capability in the oneM2M platform. In this design the IPE is thus no longer needed and the wearable devices can directly communication with the oneM2M platform.  The third design is based on Internet Engineering Task Force (IETF) RFC 7668 and BLE Special Interest Group (SIG) Internet Protocol Support Profile (IPSP) that defined 6LoWPAN (IPv6 over Low-power Wireless Personal Area Network) over BLE. As a result, CoAP/6LoWPAN can now be supported on both the end devices and the oneM2M platform.

The three designs described above enable BLE wearable devices to interwork with the oneM2M platform. Our research compares and evaluates the main features and behaviors of these three designs and investigates key performance indicators of each such as power consumption, system performance, transmission efficiency, and design complexity. With our research we are able to determine which specific design is most suitable for wearable devices under different system design requirements.