黃寶儀臺灣大學：電機工程學研究所張庭豪Chang, Ting-HaoTing-HaoChang2007-11-262018-07-062007-11-262018-07-062006http://ntur.lib.ntu.edu.tw//handle/246246/53396In this work, we present our experience in constructing and maintaining a mid-size sensor network testbed, called BL-Live, which has transformed the cold concrete BL Hall on the NTU campus into a smart, lively office building. The main objective is to re-examine research and deployment issues involved in operating a long-term sensor network for everyday use. Currently, we implement two everyday services, Elevator Report and Smart Office. The Elevator Report service provides the BL building's residents with the status of the elevators so that they can determine which elevator to take at what time. The Smart Office service, on the other hand, detects the presence of people in an office. The core contribution of this work lies in the design and evaluation of mechanisms to enhance the reachability of data dissemination in BL-Live. We propose and systematically evaluate several data dissemination strategies to achieve our goal. They include re-transmission, priority, random wait, and even a revised routing mechanism to counter problems caused by asymmetric links. The experiment results of the evaluation of the BL-Live testbed show that our methods improve the reliability. With random wait, the reachability is increased by 5%. With re-transmission, we improve the reachability by 8%. Finally we propose two extensions of Magnetic Diffusion. The reachability of each extension is close to Flooding and is more energy efficient.1 Introduction 1 2 Related Work 4 2.1 Applications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 2.2 Testbeds . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5 2.3 Reliable Transmission . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6 2.3.1 Reliable transmission . . . . . . . . . . . . . . . . . . . . . . . . . 7 3 BL-Live 9 3.1 System Hardware . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9 3.2 System Software . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10 3.3 Services . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11 3.3.1 Elevator Report . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11 3.3.2 Smart Office . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13 3.4 Experience and Lessons Learned . . . . . . . . . . . . . . . . . . . . . . . 14 3.4.1 Management of Sensor Nodes . . . . . . . . . . . . . . . . . . . . 14 3.4.2 Node Placement . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14 3.5 Observations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15 3.5.1 Problems Caused by Collisions . . . . . . . . . . . . . . . . . . . . 15 3.5.2 Problems Caused by Asymmetric Links . . . . . . . . . . . . . . . 15 4 Reliable Data Dissemination 17 4.1 Magnetic Diffusion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17 4.1.1 Interest Broadcast . . . . . . . . . . . . . . . . . . . . . . . . . . 17 4.1.2 Data Propagation . . . . . . . . . . . . . . . . . . . . . . . . . . . 19 4.1.3 Problems Caused by Asymmetric Links . . . . . . . . . . . . . . . 20 4.2 Improvement in Reliability and Latency . . . . . . . . . . . . . . . . . . 20 4.2.1 Mechanisms for Solving the Collision Problems . . . . . . . . . . . 21 4.2.2 Mechanisms for Solving the Asymmetric Link Problems . . . . . . 23 5 Evaluation 26 5.1 Setup and Metrics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26 5.2 Impact of Random Wait . . . . . . . . . . . . . . . . . . . . . . . . . . . 27 5.3 Impact of Two-level Priority Forwarding . . . . . . . . . . . . . . . . . . 27 5.4 Impact of Sending Twice . . . . . . . . . . . . . . . . . . . . . . . . . . . 29 5.5 Impact of MDlq and MDfd . . . . . . . . . . . . . . . . . . . . . . . . . . 29 5.6 Summary of Experiment Results . . . . . . . . . . . . . . . . . . . . . . . 31 6 Conclusion 34 Bibliography 361005324 bytesapplication/pdfen-US感測網路可靠傳輸測試平台sensor networksreliable disseminationtestbedthesishttp://ntur.lib.ntu.edu.tw/bitstream/246246/53396/1/ntu-95-R93921093-1.pdf