# Combined Use of LoRaWAN Medium Access Control Protocols for IoT Applications
## 7 Conclusions  
This paper proposed a simulative performance assessment in different scenarios and configurations of a LoRaWAN network that combines the use of the two MAC protocols supported by LoRaWAN, Pure ALOHA and LBT AFA, working in compliance with the ETSI regulations. Summarizing, the results obtained show that in the assessed scenarios, LBT AFA obtains lower PLR values than Pure ALOHA. In particular, the benefits offered by LBT AFA become more evident as the workload increases. \begin{table}
\begin{tabular}{c c c c c} \hline \hline \multirow{2}{*}{**MAC Protocol**} & **Type of** & **Case L—** & **Case M—** & **Case H—** \\  & **End-Devices** & **Avg e2 eDelay (s)** & **Avg e2 eDelay (s)** & **Avg e2 eDelay (s)** \\ \hline \multirow{2}{*}{Pure ALOHA} & Stationary (80\%) & 0.38 & 0.40 & 0.41 \\  & Mobile (20\%) & 0.28 & 0.39 & 0.40 \\  & Stationary (80\%) & 0.89 & 1.20 & 1.43 \\  & Mobile (20\%) & 0.72 & 1.23 & 1.51 \\ \hline \multirow{2}{*}{Pure ALOHA} & Stationary (50\%) & 0.39 & 0.40 & 0.41 \\  & Mobile (50\%) & 0.28 & 0.31 & 0.35 \\  & Stationary (50\%) & 0.93 & 1.22 & 1.45 \\  & Mobile (50\%) & 0.85 & 1.16 & 1.60 \\ \hline \multirow{2}{*}{Pure ALOHA} & Stationary (20\%) & 0.39 & 0.39 & 0.41 \\  & Mobile (80\%) & 0.28 & 0.30 & 0.35 \\  & Stationary (20\%) & 0.90 & 1.24 & 1.44 \\  & Mobile (80\%) & 0.87 & 1.22 & 1.51 \\ \hline \hline \end{tabular}
\end{table} 
Table 13: Average e2 eDelay with varying percentages of stationary and mobile end-devices. However, end-devices that adopt LBT AFA experience a PDR that increases with the traffic load. This value represents the number of messages that are discarded because the maximum number of backoffs is reached. To reduce the number of messages discarded, it is possible to increase the \(LBT_{backoffs}^{max}\) parameter. In this way, the probability of a message being sent increases, as a higher number of transmission attempts will be run before discarding it. However, on average, as each end-device will run a higher number of CCAs, the energy consumption will also increase. As the \(ECR^{xx}\) results show, in the scenarios assessed, Pure ALOHA consumes slightly less energy per transmission than LBT AFA because it does not perform any CCA. Furthermore, pure ALOHA experiences lower e2 eDelays than LBT AFA because message transmissions are not delayed. Based on the findings of this assessment, the network designer can determine which MAC protocol to use on each end-device depending on the desired performance target (i.e., PLR, PDR, e2 eDelay, or energy consumption). In particular, to achieve low PLR values, the LBT AFA MAC protocol is the preferred choice and setting a high \(LBT_{backoffs}^{max}\) value can be an option to obtain low PDR values. On the contrary, if the primary target is to reduce the maximum message e2 eDelay, the network designer can adopt Pure ALOHA, which is also able to offer low PLR under low and medium workloads. Future work will deal with a priority-based traffic classification algorithm that runs on the LoRaWAN end-devices and allows the network designer to choose, for each traffic flow, the MAC protocol that best matches the flow requirements. Furthermore, we will also explore the use of the SDN paradigm to dynamically select LoRa parameters in mobile end-devices. Conceptualization, L.L. ; methodology, L.L., L.L.B. and G.P. ; investigation, L.L., L.L.B., G.P., A.P. and M.P. ; software, L.L., A.P. and M.P., writing--original draft preparation, L.L., L.L.B. and G.P. All authors have read and agreed to the published version of the manuscript. This research was partially funded by the Project \"Soluzioni innovative per la connetivita wired e wireless nell'industria 4.0 a supporto dell'efficienza e resilienza della fabbrica\", within the action IV.4--\"Dottorati e contratti di ricerca su tematiche dell'innovazione del nuovo Asse IV del PON Ricerca e Innovazione 2014-2020 Istruzione e ricerca per il recupero--REACT-EU\". Not applicable. The data underlying this article will be shared on reasonable request from the corresponding author.