## 4 The Proposed Adaptive Channel Coding Technique
### The Outer Loop Link Adaptation Approach
In the case of the simulation, in this study an average block size of 44 bytes is used. First, the reliability performance of the proposed approach is assessed in comparison to the traditional repetition approach as well as the NBLA approach. This assessment is performed by varying the transmission power of the different NB-IoT nodes and for the same number of transmissions, the average BLER value is computed for each of the three approaches. The obtained results as illustrated in Figure 4 clearly demonstrate that the Block Error rate (BLER) of the traditional repetition approach, the NBLA approach as well as the one of our proposed EEACC approach are all seen to reduce as the Signal-to-Noise Ratio (SNR) increases. This is an expected behaviour which materializes and confirms the emitted hypothesis that the higher the transmission power, the higher the amount of energy as encoded in a bit through modulation and channel coding, the higher the resilience to noise and other channel impairments. However, our focus is on observing the performance of the proposed approach in comparison to the other two approaches in terms of the extra contribution in terms of network reliability. In terms of further analysis, it can be observed that the slope of the EEACC decreases much faster than that of the others after an SNR of \(-14\) dB. This is justified by the contribution of the repeated transmission capability of the EEACC coupled with its channel-aware MCS selection which demonstrates fewer transmission failures and therefore, further enhances the overall reliability performance of the network. These previous two justification factors are further emphasized by the increase in transmission power \(P_{Tx}\) which enhances the SNR within a single transmission period \(T\) where the channel conditions remain more or less the same. The increase in the transmission power for the same noise floor level translates in a higher Signal-to-Noise Ratio (SNR). This is because the increase in SNR is directly proportional to the increase in the transmission power in terms of the SNR ratio value definition which translates in additional dB offset value. It is also important to observe that while for SNR values that range from \(-18\) dB to \(-14\) dB, all the BLER values are quite the same for the three approaches. Overall, the BLER values of the NBLA as well as the traditional repetition approaches are higher compared to the proposed EEACC approach for the various SNR values. This means that the EEACC exhibits better network reliability performance as compared to the NBLA and the traditional repetition approaches. Finally, it can be noticed that the BLER performance of the NBLA as well as the one of the traditional repetition approach, remains closer as transmission power is increased. Considering the EEACC approach, the BLER performance significantly drops faster as low as \(0.18\%\) for an SNR of \(-4\) dB. Secondly, the average energy consumption of the NB-IoT network was also computed as the number of NB-IoT nodes is varied with each of the three approaches, namely the traditional repetition, the NBLA as well as the proposed EEACC approach. The obtained results are depicted in Figure 5. Various simulations were conducted with various NB-IoT nodes as a mechanism to assess the impact of the network's scalability on its energy efficiency performance for the different approaches. This is very important as it assesses the compatibility of the proposed EEACC approach with the nowadays massive IoT deployments in terms of maintaining an acceptable level of network performance. It can be observed from Figure 5 that the EEACC approach is more energy-efficient than the NBLA and the traditional repetition approaches. In addition, the average energy consumption of all three approaches increases as the number of NB-IoT nodes is increased in the network.