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Title: | 低工作週期機器對機器網路中時間嚴格之信息傳輸 Transmission of Time-critical Messages in Low Duty-cycle Machine-to-machine networks |
Authors: | I-Wu Lu 盧奕吾 |
Advisor: | 周俊廷(Chun-Ting Chou) |
Keyword: | 節電,機器對機器網路,非同步,時間嚴格的訊息傳輸, Asynchronous network,low duty cycle,M2M network,power saving protocol,time-critical messages, |
Publication Year : | 2014 |
Degree: | 碩士 |
Abstract: | M2M communication is an enabling solution for many applications, including industrial control and smart buildings.
Take the temperature monitoring system for machinery in a factory as an example. The temperature sensors send back the readings to a central controller. The controller will shut down the system if the readings are over a predefined threshold. In smart buildings, lighting control systems consist of different sensors such as light sensors and motion sensors. These sensors detect the behaviors of human beings and turn on/off the lights accordingly. A common problem among the above applications is that many machines, especially the sensors, are usually battery-powered. Therefore, they have extremely limited energy budget. Given that it is also very inconvenient to replace or recharge the battery, how to maintain an M2M network in an energy-saving manner becomes a critical issue in the design of M2M networks. Turning the radio off whenever possible (i.e., duty cycling the machines) is one of the most common methods for energy management. Duty-cycle control, however, results in a longer latency of message dissemination. Although longer latency is not a serious problem for non-time critical messages such as regular temperature readings, it will lead to devastating results for time-critical messages such as fire alarms. Most of the existing researches focused on minimizing the latency of non-time critical messages or time-critical messages seperatedly. A joint design to make tradeoff between the latency of these two types of messages is still missing. In this thesis, a set of specially designed sequences that control the duty cycle of machines is developed to make a better tradeoff. Our simulation results show that the end-to-end latency of time-critical messages is shortened by 13% to 42% depending on the duty cycle, while that of non-time critical message is only increased by less than 7%. The proposed solution is also implemented in an IEEE 802.15.4 network. The result shows that our sequences can prolong the lifetime of machines by 22% to 333% and reduce the end-to-end delay by 26%. |
URI: | http://tdr.lib.ntu.edu.tw/jspui/handle/123456789/55522 |
Fulltext Rights: | 有償授權 |
Appears in Collections: | 電信工程學研究所 |
Files in This Item:
File | Size | Format | |
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ntu-103-1.pdf Restricted Access | 9.6 MB | Adobe PDF |
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