透過低耗能藍芽及oneM2M達成穿戴式裝置的空中下載更新

Abstract

物聯網(IoT)目前正隨著越來越多的連網裝置而大幅度的成長中。根據Gartner的市場調查報告指出，2017年將會有高達84億的裝置連至網路，比2016年高出31%。在這些連網裝置中有一項產品稱為「穿戴式裝置」，是一種可以配戴在使用者身上的電子配件。然而，大多數的穿戴式產品都無法於上架後，由使用者進行服務更新或更改，例如：一旦穿戴式裝置做為計步器上架，便很難做為其他服務使用如姿勢矯正器，即使這兩種服務使用相同的感測器。 Over-The-Air (OTA) 空中下載更新是一項很重要的技術，能夠透過無線網路變更或更新無線裝置上的應用程式。利用這項技術，我們能夠更新穿戴式裝置的韌體或是安裝新的應用程式在穿戴式裝置上，因此，使用者可以在購買一項產品之後，透過此技術享有多種服務，而不需要為了不同應用買很多不同的穿戴式產品。 為了達成OTA 空中下載更新的功能，穿戴式裝置所使用的無線連線技術必須要考量有限的計算能力、記憶體大小及電池容量等。近幾年來，由於低耗能藍芽(BLE)具有低耗能的特性，此項技術已被應用在智慧型手機及各種穿戴式裝置上。根據先前的研究，在oneM2M物聯網平台與穿戴式裝置之間，有三種不同的低耗能藍芽連線方法，而在此研究中，我們選擇了其中兩種用於開發透過物聯網平台及低耗能藍芽達成OTA穿戴式裝置更新的技術： 1. 第一種方法為Inter-working Proxy Application Entity (IPE)，此方法源自於oneM2M的標準，主要負責低耗能藍芽與oneM2M標準間通訊協定及資料格式的轉換。 2. 第二種設計為6LoWPAN over BLE，此方法是基於IETF的RFC 7668 IPv6 over BLE標準，讓6LoWPAN(IPv6 over Low-power Wireless Personal Area Network)可以在低耗能藍芽的L2CAP (Logical Link Control and Adaptation)層上執行及允許CoAP協定可以執行於6LoWPAN上。 我們的研究主要在於分析及評估基於兩種不同低耗能藍芽連線方式所設計出的OTA穿戴式裝置更新架構，並探討各方面的效能包含：穿戴式裝置的耗能、傳輸過程中的傳輸效率、物聯網平台的系統效能及設計與實作的複雜度，除此之外，亦探討欲更新之應用程式的大小是否會影響上述各項效能指標。透過此研究，我們可以決定哪一種設計與連線方式較為適合用做OTA穿戴式裝置更新這項功能上。

The Internet of Things (IoT) is growing rapidly with more and more devices connected to the Internet. According to the report of Gartner, it forecasts that 8.4 billion things will be connected to the network in 2017, up 31 percent from 2016. One kind of these devices is called wearable devices which can be worn on the human body. However, most of the wearable products are not programmable; it is difficult for them to be upgraded or changed to a different service once they are delivered. For example, if the wearable device is sold as a pedometer, it cannot be used to serve other purpose such as gesture corrector even these two services all utilize the same sensors. Over-The-Air (OTA) provisioning is an important technology which describes the ability to change or update the applications in the devices over the wireless networks. It can be used to update firmware or install new applications for wearable devices. Thus, instead of buying multiple devices, the customer can purchase and enjoy multiple services with only one device. To enable the OTA provisioning, the wireless technologies used by the wearable devices need to take their limited computing/storage/battery capabilities into consideration. In recent years, Bluetooth Low Energy (BLE) has emerged as the protocol choice for many wearable devices and mobile handsets due to its features of low power consumption and low storage requirement. According to our previous research, there are three different BLE communication methods between the oneM2M-based platform and the wearable devices. In this research, we develop technologies that enable the OTA provisioning for the wearable devices via BLE and oneM2M. We choose two of BLE communication methods developed before: 1. The first method is the Inter-working Proxy Application Entity (IPE) based on oneM2M standard. IPE is used to translate protocols between BLE and oneM2M standard protocol and exchange the data models between the BLE device and the oneM2M platform. 2. The second method, 6LowPAN over BLE, is based on IETF RFC 7668 IPv6 over BLE that allows the 6LoWPAN (IPv6 over Low-power Wireless Personal Area Network) protocol on top of the BLE L2CAP (Logical Link Control and Adaptation) protocol and the CoAP application protocol on top of the 6LoWPAN. Our research focuses on comparing and evaluating these two BLE communication methods for the OTA provisioning by investigating the performance metrics of each including power consumption of the device, transmission efficiency during the provisioning procedure, system performance of the oneM2M-based platform, and the design and implementation complexity. Our research objective is to determine which method is the most suitable design for the BLE OTA provisioning. In addition, we also investigate whether the sizes of applications will have an impact on the performance.