# Analysis of Bidirectional ADR-Enabled Class B LoRaWAN Networks in Industrial Scenarios
## 7 Conclusions and Future Work  
LoRaWAN networks have proven to be an interesting technological solution for industrial use cases that require wireless communications that are robust to interference (especially where using  
Figure 14: Total energy consumed by packet reception by EDs in the network for 24 h with downlink periodicity of 1950 s.  
Figure 15: Total energy consumed by receptions by EDs in the network for 24 h with downlink periodicity of 1950 s.  
unlicensed bands is a requirement), have low energy consumption, and may need to reach long distances. When selecting this technology, it is important is to know in advance how it will perform in each scenario so unexpected behavior can be avoided before carrying out a costly network deployment. This article overviewed proposed network simulators and LoRaWAN implementations and improved the ns-3 simulator modules to include missing features, such as class B support and ADR support, that were previously only tested independently, and it also proposed the application of ADR for downlink traffic. Enabling the ADR for downlink traffic, in packets that are by definition sent with SF9, allows devices to lower the SF and therefore spend less time with their radios active. This can significantly lower the amount of energy consumed without affecting the PDR, as the mechanism ensures the selection of an optimal SF. Then, the proposed implementation (which can be found in [16] after requesting access) was simulated and tested over a carefully selected scenario which complied with a real industrial use case under study. The results are promising in terms of robustness and energy optimization. Although the comparison with some fixed SF values shows similar network performance, with around 2% better PDR in troublesome areas for ADR implementation, the study was successful in that the mechanism worked as expected. The usage of ADR for downlink in class B devices in this scenario only had an impact on energy consumption, which was expected as downlink packets were scheduled and thus avoided collisions naturally. Nevertheless, the energy consumption was improved, network-wise, by between 31 and 43% (depending on SNR\({}_{\text{sc}}\) used) in the downlink stage. In real-world deployments, the ADR mechanism allows us to adapt better to changes in the environment and to cases where EDs change their positions at given times. The use of ADR can be even more relevant when the number of devices increases, i.e., in more densely populated scenarios, or when there are greater interference and noise levels due to the specific characteristics of other environments. Therefore, there are two main results for consideration: (1) the enhanced simulation tools to conduct new experiments for realistic LoRaWAN network deployments and (2) the optimization of downlink traffic by enabling ADR which has a great impact on energy savings. This is a first step where some configuration assumptions have been made, allowing for future work that would characterize even more realistic operation and configuration for LoRaWAN networks. The implementation of features for the network simulator allows new experiments to be conducted with other channel models that may introduce more variability. Moreover, the proposals, even if they involve a particular configuration, are still compliant enough with the standard to allow validation of results using commercial off-the-shelf (COTS) devices in the near future. Methodology, J.S.-B. and V.S.-P.; software, D.T.-F. and A.P.-M.; validation, J.S.-B., V.S.-P., and D.T.-F.; formal analysis, D.T.-F.; writing--original draft preparation, D.T.-F. and [PERSON]-M.; writing--review and editing, [PERSON]-[PERSON], [PERSON]-[PERSON], and [PERSON]-[PERSON]; supervision, [PERSON] and [PERSON]. All authors have read and agreed to the published version of the manuscript. The research leading to these results received funding from the Horizon 2020 Programme of the European Commission under Grant Agreement No. 825631 \"Zero Defect Manufacturing Platform (ZDMP)\".