## 4 The Proposed Adaptive Channel Coding Technique
### The Outer Loop Link Adaptation Approach
The proposed novel 2-D adaptive channel coding and link adaptation technique proves to minimize the overall energy consumption of the NB-IoT system and demonstrates the ability to sustain network scalability without

Figure 7: Uplink and Downlink Average full transmission delay with increased scalability. significant increases in network latency. The observed performance of the proposed EEACC in terms of network scalability, latency, energy efficiency, and reliability metrics, in comparison with the existing traditional repetition approach as well as the NBLA approach is the key contribution of this research work. Future work plans to implement and assess the performance of the proposed EEACC algorithm on an NB-IoT embedded test-bed platform for a smart water consumption monitoring application. ## 7 Future Work

The proposed energy efficiency approach (EEACC) has been demonstrated to be an energy efficiency approach as compared to the traditional repetition and the NBLA approaches. Therefore, our proposed future research work consists of firstly implementing and assessing the proposed energy-efficient approach on-chip by using an application scenario such as smart water metering or environmental monitoring sensor network to further practically validate the proposed approach. Secondly, we propose to theoretically assess the solution of the problem using an optimization approach. Conceptualization, K.D., E.M.; methodology, E.M., K.D. ; software, E.M.; validation, E.M., K.D. and A.K. ; formal analysis, E.M., K.D. ; investigation, E.M.; resources, E.M.; data curation, E.M.; writing--original draft preparation, E.M.; writing--review and editing, K.D. and A.K. ; visualization, E.M.; supervision, K.D. and A.K. ; project administration, E.M., A.K. and K.D. ; funding acquisition, K.D. and A.K. All authors have read and agreed to the published version of the manuscript. This research was funded in part by the National Research Foundation of South Africa (Grant Number: 90604). Opinions, findings, and conclusions or recommendations expressed in any publication generated by the NRF supported research are those of the author(s) alone, and the NRF accepts no liability whatsoever in this regard. The authors would like to also thank the Telkom Centre of Excellence (CoE) for their support. The authors declare no conflict of interest. The funders had no role in the design of the study; in the collection, analyses, or interpretation of data; in the writing of the manuscript, or in the decision to publish the results. ## Abbreviations

The following key abbreviations are used in this manuscript: \begin{tabular}{l l} NB-IoT & Narrowband Internet of Things \\ NB-IoT node & Device equipped with a processor and an NB-IoT modem such as a sensor node, a smart water meter, etc. \\ NBLA & Narrowband Internet Link Adaptation \\ EEACC & Energy-Efficient Adaptive Channel Coding \\ LTE & Long Term Evolution \\
3 GPP & Third Generation Partnership Project \\ SNR & Signal to Noise Ratio \\ NPUSCH & Narrowband Physical Uplink Shared Channel \\ BS & Base Station \\ RU & Resource Unit \\ MCS & Modulation Coding Scheme \\ BLER & Block Error Ratio \\ LPWAN & Low Power Wide Area Networks \\ ARQ & Automatic Repeat Request \\ FEC & Forward Error Correction \\ TBS & Transport Block Size \\ \end{tabular} 

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