隨著時代的發展，物聯網應用逐漸融入人們的生活，因此有越來越多的場景有應用需求，要管理的裝置也就越來越多，而物聯網閘道器可以有效管理這些裝置。由於應用場景不同、不同需求而重新開發系統的情況並不少見，為了避免重複開發系統，我們為物聯網應用情景開發之基於MQTT通訊協定的通用型閘道器，我們設計了靈活的數據庫架構和模組，使架構可以根據應用場景進行調整，適用於大多數應用場景。考量日後系統擴展，我們設計具延展性的架構，透過善用MQTT通訊協定來達成目標，由於在物聯網中網路不穩定是常態，故我們設計訊息備份以及重傳機制，使用回條來保證訊息送達，讓架構具有可靠的訊息傳遞。最後，我們將此架構實際應用到兩個情景：電力管理以及倉儲管理中，證明其通用性並能適用於大多數物聯網應用情景，並且實測我們架構傳輸時間以及確認重傳機制是否如期運作，實驗結果為我們的架構確實能夠重傳訊息，並且使系統更加靈活和穩定，不僅能因應情景而調整應用功能，還能管控訊息進出、決定是否同步訊息等。

With the development of the times, IoT applications are gradually integrated into people's lives, so there are more and more scenarios with application requirements, more and more devices to be managed, and the transmission protocols used by each device may not be the same. IoT gateways effectively manage these devices and resolve issues between different protocols. Due to different scenarios and different requirements, it is common to re-develop the system. To avoid repeated development of the system, we developed a general MQTT-based gateway for the IoT application scenario, and we designed a flexible database architecture and modules so that the architecture can be adjusted according to the application scenario, which is suitable for most application scenarios. Considering the system expansion in the future, we design a scalable architecture to achieve the goal by making good use of the MQTT communication protocol. Since network instability is the norm in the IoT, we have designed a message backup and retransmission mechanism, which uses an acknowledgment (ACK) to ensure the delivery of the message, allowing the architecture to have reliable message delivery. Finally, we practically apply this architecture to two IoT scenarios: power management and warehouse management, demonstrating its generality and suitability for most IoT application scenarios, and experiment with our architecture transmission time and whether the retransmission mechanism works as expected, the experimental result is that our architecture can indeed retransmit messages, and make the system more flexible and stable, not only can be adjusted application function according to the scene but also can control the sending and receiving of messages, decide whether to synchronize the messages, etc.

[1] J. Kuliu, W. Heinzelman, and H. Balakrishnan, “Negotiation-Based Protocols for Disseminating Information in Wireless Sensor Networks,” Wireless Networks, Volume 2, pages 169-185, 2002.
[2] I. T. U. Strategy, and Policy Unit, “ITU Internet Reports 2005: The Internet of Things. Geneva: International Telecommunication Union (ITU),” Tunisia, November 17, 2005.
[3] Y. Liu, and G. Zhou, “Key Technologies and Applications of Internet of Things.” In 2012 Fifth International Conference on Intelligent Computation Technology and Automation, pages 197-200. Zhangjiajie, China, January 12-14, 2012.
[4] M. Wu, T. J Lu, F. Y. Ling, J. Sun, and H. Y. Du, “Research on The Architecture of Internet of Things.” 2010 3rd International Conference on Advanced Computer Theory and Engineering (ICACTE), Volume 5, pages 484-487. Chengdu, China, August 20-22, 2010.
[5] P. Sethi, and S. R. Sarangi, “Internet of Things: Architectures, Protocols, and Applications,” Journal of Electrical and Computer Engineering, Jan 26, 2017.
[6] B. Kang, D. Kim., and H. Choo, “Internet of Everything: A Large-Scale Autonomic IoT Gateway,” IEEE Transactions on Multi-Scale Computing Systems, Volume 3, Issue 3, pages 206-214, May 18, 2017.
[7] B. Y. Ooi, Z. W. Kong, W. K. Lee, S. Y. Liew, and S. Shirmohammadi, “A Collaborative IoT-Gateway Architecture for Reliable and Cost-Effective Measurements,” IEEE Instrumentation & Measurement Magazine, pages 11-17, November 28, 2019.
[8] H. Chen, X. Jia, and H. Li, “A Brief Introduction to IoT Gateway,” In IET international conference on communication technology and application, pages 610-613, Beijing, October 14-16, 2011.
[9] J. Guth, U. Breitenbücher, M. Falkenthal, F. Leymann, and L. Reinfurt, “Comparison of IoT Platform Architectures: A Field Study Based on a Reference Architecture,” In 2016 Cloudification of the Internet of Things (CIoT), pages 1-6, Paris, France, November 23-25, 2016
[10] J. Guth, U. Breitenbücher, M. Falkenthal, P.Fremantle, O. Kopp, F. Leymann, and L. Reinfurt, “A Detailed Analysis of IoT Platform Architectures: Concepts, Similarities, and Differences,” In Internet of everything, pages 81-101, Springer, Singapore. 2018
[11] M.-C. Tsai, “Design and Implementation of Smart Gateway for Energy Management,” M.S. thesis, National Cheng Kung University, Taiwan, July 2018.
[12] R. -S. Sinha, Y. Wei, and S. -H. Hwang,” A Survey on LPWA Technology: LoRa and NB-IoT,” ICT Express, Volume 3, Issue 1, pages 14-21, March 2017.
[13] S. Popli, R. -K. Jha, and S. Jain, “A Survey on Energy Efficient Narrowband Internet of Things (NB-IoT): Architecture, Application, and challenges,” IEEE Access 7, pages 16739-16776, November 15, 2018.
[14] Y. Li, X. Cheng, Y. Cao, D. Wang, and L. Yang, “Smart Choice for the Smart Grid: Narrowband Internet of Things (NB-IoT),” IEEE Internet of Things Journal, Volume 5, Issue 3, pages 1505-1515, December 8, 2017.
[15] T. Yokotani, and Y. Sasaki, “Comparison with HTTP and MQTT on Required Network Resources for IoT,” International Conference on control, electronics, renewable energy and communications, pages 1-6, Bandung, Indonesia, September 13-15, 2016.
[16] S. -M. Kim, H. -S. Choi, and W. -S. Rhee, “IoT Home Gateway for Auto-Configuration and Management of MQTT devices,” IEEE Conference on Wireless Sensors, pages 12-17, Melaka, Malaysia, August 24-26, 2015.
[17] N. Naik, “Choice of Effective Messaging Protocols for IoT Systems: MQTT, CoAP, AMQP and HTTP,” In 2017 IEEE international systems engineering symposium (ISSE) pages. 1-7, October 30, 2017.
[18] I. Makhdoom, M. Abolhasan, H. Abbas, and W. Ni, “Blockchain's Adoption in IoT: The Challenges, and a way Forward,” Journal of Network and Computer Applications, Volume 125, pages 251-279, January 1, 2019.
[19] E. B. Sanjuan, I. A. Cardiel, J. A. Cerrada, and C. Cerrada, “Message Queuing Telemetry Transport (MQTT) Security: A Cryptographic Smart Card Approach,” IEEE Access, Volume 8, pages 115051-115062, Jane 22, 2020.
[20] P. Bull, R. Austin, E. Popov, M. Sharma, and R. Watson, “Flow Based Security for IoT Devices Using an SDN Gateway,” In 2016 IEEE 4th international conference on future internet of things and cloud (FiCloud), pages 157-163, August 22-24, 2016.
[21] C. M. D. Morais, D. Sadok, and J. Kelner, “An IoT Sensor and Scenario Survey for Data Researchers,” Journal of the Brazilian Computer Society, 25(1), pages 1-17, February 27, 2019.
[22] D. -Z. Zhuang, S. -J Huang, H. -H Chang, and W. -G. Teng, “A Gateway Architecture for Web-based Energy Management Services”, 2020 International Computer Symposium (ICS 2020), Tainan, Taiwan, December 17-19, 2020.
[23] C. -H. Lee, and Y. -H. Lai, “Design and Implementation of a Universal Smart Energy Management Gateway Based on the Internet of Things Platform,” IEEE International Conference on Consumer Electronics, pages 67-68, Las Vegas, NV, USA, January 7-11, 2016.
[24] B. S. S. Tejesh, and S. J. A. E. J. Neeraja, “Warehouse Inventory Management System using IoT and open-source framework,” Alexandria engineering journal 57 (4), pages 3817-3823, February 19, 2018
[25] H. -C. Hwang, J. Park, and J. G. Shon, “Design and Implementation of A Reliable Message Transmission System Based on MQTT Protocol in IoT,” Wireless Personal Communications 91, pages 1765-1777, June 9, 2016.
[26] Z. Lin, and L. Zhang, “Data Synchronization Algorithm for IoT Gateway and Platform,” In 2016 2nd IEEE International Conference on Computer and Communications, pages 114-119, Chengdu, China, October 14-17, 2016.
[27] S. Gao, X. Zhang, C. Du, and Q. Ji, “A Multichannel Low-Power Wide-Area Network with High-Accuracy Synchronization Ability for Machine Vibration Monitoring,” IEEE Internet of Things Journal, Volume 6, Issue 3, pages 5040-5047, January 24, 2019.
[28] S. Lee, H.Kim, D. K. Hong, and H. Ju, “Correlation Analysis of MQTT Loss and Delay According to QoS Level,” In The International Conference on Information Networking 2013 (ICOIN) , pages 714-717, January 28-30, 2013.