# A Systematic Literature Review of LoRaWAN: Sensors and Applications
## 3 Results
### Other Works Analyzing Different Aspects of LoRaWAN
#### 3.3.3 Performance Improvement  
Node lifetime extension is very important in LoRaWAN, and various methods can be used to achieve this end. For example, one way to improve performance is by improving supplies as well as using sleep mode to lower power consumption. In this area of study, there are several works that have been executed. In [36], the LTC3588 energy harvesting module was used together with a solar panel and a supercapacitor to provide power to a microcontroller and a wireless sensor without the need for them to be connected to a battery; with this, it was achieved that the devices can have a sustainable operation. In [39], a class A end node was used to apply two methods for extending its working life period: the first was energy harvesting (EH) using a solar panel, and the second was the use of a deep sleep method. In [44], simulations of networks with backscatter communication were carried out, which had Backcom devices; these devices collected energy and transmitted data without the need for a battery, thus prolonging their lifetime. However, these devices generated a high rate of collisions when transmitting data. On the other hand, in [45], an algorithm called APRA was used, which varies the transmission priorities and signal processing dynamically to maximize the quality of service, avoid signal collisions, and improve the useful lifetime of the batteries. Also, in [34], the Wake-Up Radios technique was used, so that with the help of an automaton, the main node changes dynamically; it is important to indicate that the main node is chosen depending on the frequency with which it sends or receives signals, causing the rest of the nodes to enter a standby state, thus improving battery life. In addition, there are works that with an improvement in the methods of sending information seek to increase the data-collection ratio without increasing energy consumption and thus improve the level of communication and scalability of LoRaWAN networks. Among these works, we can mention the following. In [49], the study of a LoRaWAN network with different sensors is carried out, which generates asymmetric network traffic. In this work, it is demonstrated that the usage of Slotted ALOHA in the MAC layer helps to improve network performance; the simulations for this demonstration were carried out with asymmetric traffic of small, medium, and large volume. Additionally, in [56], a simulation is carried out to create a network of wireless sensors that have a higher data collection rate than that established in the LoRaWAN standard and at the same time have an efficient use of energy. To achieve this, in this paper, the authorsuse a recursive linear prediction algorithm on the server side and a prediction error control algorithm on the end-device side. On the other hand, in another work, a modification of the LoRaWAN communication protocol is presented in which the payload data is encoded in custom frames to improve data transmission speeds [57]. On the other hand, in [59], the combination of LoRaWAN, SigFox, and GSM in a hybrid device is proposed; the information collected by the communication technologies is sent to a cloud platform and synchronized by an open platform communications (OPC) server to increase the reliability of the collected data. In [63], the scalability and reliability of LoRaWAN in long-range communications are evaluated through a simulation model carried out in an NS-3 network simulator, with the result that multiple gateways considerably improve the reliability of the network. In addition, in [52], the performance of different adaptive data rate (ADR) schemes is evaluated. For this, in this work, several schemes are used in order to optimize the sending of data, for example, the use of a machine learning model to predict the metric that is being monitored. In [55], an approach is proposed that allows modeling and calculating the behavior of the LoRaWAN network taking into account the availability of independent radio frequency channels.