## 4 TB-RPL Mechanism
### Detailed Process of TB-RPL
Specifically, TB-RPL utilizes a modified DAO message format and a threshold of the number of route entries to implement a robust mechanism that deals with the normal and weak cases in downward routing. Every node does its best to save route entries; otherwise, it also does its best to transmit the route information to another node. As a result, TB-RPL outperforms the other RPL variants. Besides theoretical design, we implemented TB-RPL in a runnable operating system Contiki-NG. Moreover, based on the implementation, a comparative performance evaluation has been performed using Cooja simulator to compare TB-RPL with the related works. Simulation results verify that the proposed fused mode of TB-RPL is more stable and efficient in almost all cases. Apart from that, the fused hybrid-MOPs are better suited to P2P communications in networks with plenty of memory-constrained nodes. In our design, we do not consider the mobile nodes in LLN. However, it is an attractive issue for us to efficiently interoperate mobile nodes using TB-RPL as some IoT applications require the mobility of certain nodes. Therefore, enabling TB-RPL to work in mobile scenarios will be undertaken in future work. Figure 16: End-to-end evaluation on four metrics with different receive success ratio. **Author Contributions:** Conceptualization, K.Z. ; Methodology, K.Z., K.S.B. and G.C. ; Software, K.Z. ; Validation, K.Z. and K.S.B. ; Formal analysis, K.Z. and K.S.B. ; Writing--original draft preparation, K.Z. ; Writing--review and editing, K.Z. and K.S.B. ; Visualization, K.Z. and K.S.B. ; Supervision, G.C. All authors have read and agreed to the published version of the manuscript. **Funding:** This work was supported by the National Research Foundation of Korea (NRF) grant funded by the Korea government (MSIT) (No. 2021R1F1A1059840). **Data Availability Statement:** Not applicable. **Conflicts of Interest:** The authors declare no conflict of interest. ## References

* [PERSON] et al. (2022) [PERSON]; [PERSON]; [PERSON] [PERSON]; [PERSON] [PERSON]; [PERSON]; [PERSON]; [PERSON]; [PERSON] [PERSON] A review on deep learning techniques for IoT data. _Electronics_**2022**, _11_, 1604. [CrossRef]
* [PERSON] et al. (2022) [PERSON]; [PERSON]; [PERSON] [PERSON]; [PERSON]; [PERSON] A review and state of art of Internet of Things (IoT). _Arch. Comput. Methods Eng._**2022**, _29_, 1395-1413. [CrossRef]
* [PERSON] et al. (2020) [PERSON]; [PERSON]; [PERSON]; [PERSON]; [PERSON] A survey on the internet of things (IoT) forensics: Challenges, approaches, and open issues. _IEEE Commun. Surv. Tutor._**2020**, _22_, 1191-1221. [CrossRef]
* [PERSON] (2019) [PERSON] Current research on Internet of Things (IoT) security: A survey. _Comput. Netw._**2019**, _148_, 283-294. * [PERSON] and [PERSON] (2020) [PERSON]; [PERSON] A lightweight load balancing and route minimizing solution for routing protocol for low-power and lossy networks. _Comput. Netw._**2020**, _179_, 107368. [CrossRef]
* [PERSON] et al. (2019) [PERSON]; [PERSON]; [PERSON]; [PERSON]; [PERSON] Routing protocols for low power and lossy networks in internet of things applications. _Sensors_**2019**, _19_, 2144. [CrossRef]
* [PERSON] et al. (2020) [PERSON]; [PERSON] [PERSON]; [PERSON] [PERSON] Proposing a secure RPL based internet of things routing protocol: A review. _Ad. Hoc. Netw._**2020**, _101_, 102096. [CrossRef]
* [PERSON] et al. (2020) [PERSON]; [PERSON]; [PERSON] Routing protocol for Low-Power and Lossy Networks for heterogeneous traffic network. _EURASIP J. Virol. Commun. Netw._**2020**, _2020_, 1-23. [CrossRef]
* [PERSON] et al. (2019) [PERSON]; [PERSON]; [PERSON]; [PERSON]; [PERSON]; [PERSON] left 6 tisch: A tutorial. _IEEE Commun. Surv. Tutor._**2019**, _22_, 595-615. [CrossRef]
* [PERSON] et al. (2009) [PERSON]; [PERSON] [PERSON]; [PERSON]; [PERSON]; [PERSON] [PERSON] Implementation of Gradient Routing in Wireless Sensor Networks. In _GLOBECOM 2009-2009 IEEE Global Telecommunications Conference, Honolulu, HI, USA, 30 November-4 December 2009_; IEEE: Piscataway Township, NJ, USA, 2009; pp. 1-6.