# Adaptive Parameters for LoRa-Based Networks Physical-Layer
## 3 Proposal
### Network and System Model  
The most frequently used LoRa communication architecture is the LoRaWAN ([[https://lora-alliance.org/about-lorawan/](https://lora-alliance.org/about-lorawan/)]([https://lora-alliance.org/about-lorawan/](https://lora-alliance.org/about-lorawan/)), accessed on 10 December 2022) [13]. LoRaWAN specification considers LoRa radio as the physical layer, it defines the upper layers and the long-range wide area network architecture. Figure 1 depicts the main elements of a LoRaWAN architecture: nodes (or end nodes, or even end devices), gateways (or concentrators), network servers, and application server. Specifically, the application server aims to mediate communication between geographically distant devices. The network server works as a broker for the LoRa application, mediating the communication between the gateways and the application servers. Then, the gateways have the functionality of acting as access points or as device communication coordinators, providing them with connectivity. Finally, there are the end devices (e.g., sensors, smart devices, etc. ), which are the nodes that send and receive packets from the Internet (and from the application servers) through the gateways. Versions 1.0.4 and 1.1 of the architecture introduced a Join Server, which is responsible for receiving and processing the join requests that arrive from end devices and authenticating them. \begin{table}
\begin{tabular}{l c c c c} \hline \hline
**LoRa Improvement Proposal** & **Year** & **Optimization Goal** & **Cognitive** & **LoRa Modulation Parameters** \\ \hline \hline  & & **Real-Time Settings** & **SF** & **BW** \\ \hline [PERSON] et al. [19] & 2016 & Maximize the transmission range and energy-saving & & X & X \\ [PERSON] et al. [5] & 2018 & Address the unfair LoRaWAN characteristic & & X & \\ [PERSON] and [PERSON] [20] & 2019 & Reduce collisions & & \\ [PERSON] et al. [11] & 2017 & Reduce collisions & & \\ [PERSON] et al. [23] & 2019 & Maximize QoS & & X & \\ [PERSON] et al. [21] & 2018 & PDR and throughput & & X & \\ [PERSON] et al. [7] & 2018 & Improve LoRaWAN capacity and reduce collisions & & X & X \\ [PERSON] and [PERSON] [25] & 2020 & Maximize the channel utilization and reduce collisions & & X & \\ [PERSON] et al. [8] & 2020 & Improve the noise resilience and PDR & & X & \\ [PERSON] et al. [24] & 2018 & SNR smoothing & & X & \\ [PERSON] et al. [25] & 2021 & Improve packet-delivered & & X & \\ [PERSON] et al. [26] & 2020 & Improve scalability, maximize SNR & & X & \\ [PERSON] and [PERSON] [14] & 2020 & Improve scalability, maximize SNR and BER & & X & X \\
**Proposed mechanism** & **2023** & **Improve scalability, maximize SNR and BER** & X & X & X \\ \hline \hline \end{tabular}
\end{table} 
Table 1: Summary of related work and its mechanisms. The LoRaTM modulation is related to a proprietary digital spread spectrum designed by _Sentech Corporation_. LoRa is built upon CSS modulation to provide a medium for communication [30]. This scheme takes into account the signal detection sensitivity, which comes with the limitation of the transmission bandwidth. The lower bandwidth has a direct relation with how the modulation works and with the adjustable communication parameters. The designer or engineer of the communication system has to take care of those parameters accordingly with the required network performance [30]. Some advantages that can be observed while using the LoRa modulation are the immunity regarding the multi-path and Doppler effects, the long transmission range, and its low power requirement [30]. Some important configuration parameters are SF, Bandwidth (BW), and Coding Rate (CR). Moreover, it is important to highlight that LoRa-enabled devices are able to execute on ISM (Industrial, Scientific, and Medical) frequency bands of 433 MHz, 868 MHz, and 915 MHz [31]. LoRa has a digital modulation scheme based on the CSS spectral spreading technique to transmit messages, giving high communication rates for range, and reducing power consumption.