近年來，物聯網（IoT）設備的數量顯著增加，這造成了電池更換時間及成本的挑戰。無電池（Battery-Free）物聯網設備使用電容和能量擷取器（Energy Harvester）來收集環境能量，例如太陽能或射頻（Radio Frequency）。一般來說，這些物聯網設備的日常任務，尤其是資料傳輸，通常會消耗大量能源。這可能會導致無電池系統耗盡電容中的能量。背向散射通訊（Backscatter Communication）是一種新穎的無線通訊方法，其使用環境中的載波訊號 (Carrier Signal）來實現物聯網設備之間的低功耗通訊。但背向散射通訊下的傳輸仍然存在一些限制。一個明顯的限制是背向散射通訊的傳輸僅能在載波訊號可用時才能工作。在設備由能量擷取器供電的無電池背向散射通訊系統中，由於環境能量不穩定，所有設備都可能發生斷電。最壞的情況下，由於載波訊號不活動，加上環境能量不可用，設備最終將耗盡能量，資料將面臨丟失。本論文透過使用另一篇論文中提出的射頻檢測器（RF Detector）來演示硬體設計的不同策略，這種電路設計可以幫助背向散射標籤識別載波是否可用。本論文考量載波可用性的到達率和環境能量擷取效率等不同情況下，提出解決策略 — TagDN，其旨在減輕背向散射標籤能量耗盡時發生的資料丟失問題。本論文同時分析了不同設置下所接收的封包數量和接收產率（Data Yield）。實驗結果表明，如果沒有射頻檢測器以及非揮發性記憶體（Non-Volatile Memory）等額外硬體支持，無論是封包接收數量還是接收產率，表現都是最差的。總結來說，若背向散射標籤包含額外的硬體支援，則封包接收數量和接收產率可以有顯著地提昇。

In recent years, there has been a significant increase in the number of Internet-of-Things
(IoT) devices, which has led to challenges related to the time and cost associated with
battery replacement. Battery-free IoT devices use capacitors and energy harvesters to
capture the ambient energy such as solar power and radio frequency. In general, some
routine tasks of those devices, especially data transmission, often cost high energy con-
sumption. This might lead to a situation where the battery-free system runs out its
energy in the capacitor. Backscatter communication, a novel wireless communication
method, uses the ambient carrier signal to enable low-power communication between
IoT devices. But the transmission under backscatter communication still has some limi-
tations. One significant limitation is that the transmission of backscatter communication
can only work while the carrier signal is available. In a battery-free backscatter commu-
nication system where devices are powered by energy harvesters, all devices may suffer
power failure since the ambient energy is unreliable. In the worst case, the data will lose
and the device will run out of energy because the carrier signal is inactive and ambi-
ent energy is unavailable. This thesis demonstrates the different strategies in usage of
hardware design by using as RF detector proposed in another paper. This circuit design
can help backscatter tag to identify whether the carrier is active or not. Experiment
result shows the different arrival rate of carrier availability and harvesting environment.
The proposed strategy TagDN aims to mitigate the issue of data loss that occurs when the backscatter tag runs out of energy. This thesis also analyzed the total number of
received packets and the data yield under these different setups of our experiments. The
experiment results confirm that if there is no additional hardware support such as RF de-
tector and non-volatile memory, both the number of received packets and the data yield
are in the worst performance. In summary, a backscatter tag includes both additional
hardwares support, the number of received packets and the data yield can be improved
significantly.

K. Kaur, “A survey on internet of things – architecture, applications, and future trends,” in 2018 First International Conference on Secure Cyber Computing and Communication (ICSCCC), 2018, pp. 581–583.
M. H. M. Saad, N. M. Hamdan, and M. R. Sarker, “State of the art of urban smart vertical farming automation system: advanced topologies, issues and recommendations,” Electronics, vol. 10, no. 12, p. 1422, 2021.
K. Takahashi, K. Kitamura, Y. Nishida, and H. Mizoguchi, “Battery-less shoe-type wearable location sensor system for monitoring people with dementia,” in 2019 13th International Conference on Sensing Technology (ICST), 2019, pp. 1–4.
P. Lukowicz, U. Anliker, J. Ward, G. Troster, E. Hirt, and C. Neufelt, “Amon: a wearable medical computer for high risk patients,” in Proceedings. Sixth International Symposium on Wearable Computers,, 2002, pp. 133–134.
T. S. Muratkar, A. Bhurane, and A. Kothari, “Battery-less internet of things–a survey,” Computer Networks, vol. 180, p. 107385, 2020.
Z. Cai, Q. Chen, T. Shi, T. Zhu, K. Chen, and Y. Li, “Battery-free wireless sensor networks: A comprehensive survey,” IEEE Internet of Things Journal, pp. 1–1, 2022.
M. Alioto, “From less batteries to battery-less alert systems with wide power adaptation down to nws—toward a smarter, greener world,” IEEE Design Test, vol. 38, no. 5, pp. 90–133, 2021.
A. Berrueta, A. Urs ́ua, I. S. Mart ́ın, A. Eftekhari, and P. Sanchis, “Supercapacitors: Electrical characteristics, modeling, applications, and future trends,” IEEE Access, vol. 7, pp. 50 869–50 896, 2019.
A. S. Spanias, “Solar energy management as an internet of things (iot) application,” in 2017 8th International Conference on Information, Intelligence, Systems Applications (IISA), 2017, pp. 1–4.
M. Gopal, T. C. Prakash, N. V. Ramakrishna, and B. P. Yadav, “Iot based solar power monitoring system,” in IOP Conference Series: Materials Science and Engineering, vol. 981, no. 3. IOP Publishing, 2020, p. 032037.
S. Yoon, S. Carreon-Bautista, and E. S ́anchez-Sinencio, “An area efficient thermal energy harvester with reconfigurable capacitor charge pump for iot applications,” IEEE Transactions on Circuits and Systems II: Express Briefs, vol. 65, no. 12, pp. 1974–1978, 2018.
A. Bakytbekov, T. Q. Nguyen, W. Li, A. Lee Cottrill, G. Zhang, M. S. Strano, K. N. Salama, and A. Shamim, “Multi-source ambient energy harvester based on rf and thermal energy: Design, testing, and iot application,” Energy Science & Engineering, vol. 8, no. 11, pp. 3883–3897, 2020.
Q. Ju, H. Li, and Y. Zhang, “Power management for kinetic energy harvesting iot,” IEEE Sensors Journal, vol. 18, no. 10, pp. 4336–4345, 2018.
M. Magno, L. Spadaro, J. Singh, and L. Benini, “Kinetic energy harvesting: Toward autonomous wearable sensing for internet of things,” in 2016 International Symposium on Power Electronics, Electrical Drives, Automation and Motion (SPEEDAM), 2016, pp. 248–254.
W. Liu, K. Huang, X. Zhou, and S. Durrani, “Next generation backscatter communication: systems, techniques, and applications,” EURASIP Journal on Wireless Communications and Networking, vol. 2019, no. 1, pp. 1–11, 2019.
N. Van Huynh, D. T. Hoang, X. Lu, D. Niyato, P. Wang, and D. I. Kim, “Ambient backscatter communications: A contemporary survey,” IEEE Communications Surveys Tutorials, vol. 20, no. 4, pp. 2889–2922, 2018.
J.-P. Niu and G. Y. Li, “An overview on backscatter communications,” Journal of Communications and Information Networks, vol. 4, no. 2, pp. 1–14, 2019.
T. Jiang, Y. Zhang, W. Ma, M. Peng, Y. Peng, M. Feng, and G. Liu, “Backscatter communication meets practical battery-free internet of things: A survey and outlook,” IEEE Communications Surveys & Tutorials, 2023.
J. R. Smith, A. P. Sample, P. S. Powledge, S. Roy, and A. Mamishev, “A wirelessly-powered platform for sensing and computation,” in UbiComp 2006: Ubiquitous Computing: 8th International Conference, UbiComp 2006 Orange County, CA, USA, September 17-21, 2006 Proceedings 8. Springer, 2006, pp. 495–506.
H. Zhang, J. Gummeson, B. Ransford, and K. Fu, “Moo: A batteryless computational rfid and sensing platform,” University of Massachusetts Computer Science Technical Report UM-CS-2011-020, 2011.
A. Varshney, O. Harms, C. P ́erez-Penichet, C. Rohner, F. Hermans, and T. Voigt, “Lorea: A backscatter architecture that achieves a long communication range,” in Proceedings of the 15th ACM Conference on Embedded Network Sensor Systems, 2017, pp. 1–14.
C. P ́erez-Penichet, D. Piumwardane, C. Rohner, and T. Voigt, “Tagalong: Efficient integration of battery-free sensor tags in standard wireless networks,” in 2020 19th ACM/IEEE International Conference on Information Processing in Sensor Networks (IPSN), 2020, pp. 169–180.
D. Piumwardane, M. Padmal, V. Ranganathan, C. Rohner, and T. Voigt, “Harmonicid: An identification system for low-power analog backscatter tags,” in 2022 IEEE International Conference on RFID (RFID), 2022, pp. 1–6
P. Zhang, D. Bharadia, K. Joshi, and S. Katti, “Hitchhike: Practical backscatter using commodity wifi,” in Proceedings of the 14th ACM Conference on Embedded Network Sensor Systems CD-ROM, 2016, pp. 259–271.
P. Zhang, C. Josephson, D. Bharadia, and S. Katti, “Freerider: Backscatter communication using commodity radios,” in Proceedings of the 13th International Conference on emerging Networking EXperiments and Technologies, 2017, pp. 389–401.
D. Spirjakin, A. Baranov, and S. Akbari, “Wearable wireless sensor system with rf remote activation for gas monitoring applications,” IEEE Sensors Journal, vol. 18, no. 7, pp. 2976–2982, 2018.
K. Geissdoerfer and M. Zimmerling, “Learning to communicate effectively between battery-free devices,” in 19th USENIX Symposium on Networked Systems Design and Implementation (NSDI 22), 2022, pp. 419–435.