# River Water Quality Monitoring Using LoRa-Based IoT
## 2 State of the Art  
IoT refers to a big network of interconnected physical devices containing sensors, microcontrollers and other circuitry meant for data movement (from one place to another) to and from other devices and the Internet. These devices consist of simple home units and more sophisticated complex industrial structures [6].  
In recent years, IoT has become one of the most important technologies of the century. Now that we can connect everyday devices (home appliances, cars, sensors, watches, phones, etc.) to the internet, communication between people, processes and \"things\" is possible. With the use of low-cost processing systems (computers, embedded systems), the \"cloud\", data analysis tools and mobile technologies, physical devices can share data with minimal human intervention. In this ultra interconnected world, these systems can record, monitor and adjust each interaction between them. The physical world meets the digital world, and they cooperate [5].  
The applications of IoT are huge and varied, and its effect is noted across multiple areas, including manufacturing, transportation, healthcare, and farming.  
To provide great support to IoT, WSN plays a very important role, due to the advancement of sensor and microcontroller systems, as well as to ensure high-quality wireless communication rules of conduct [7].  
In Portugal, in the residential segment, 38% of personal equipment and 22% of household appliances are already connected to the Internet. In the business segment, 23% of equipment is connected to the Internet, with the main uses being facility security, energy consumption management, logistics management and production processes [6].  
As the number of Internet-connected devices continues to grow, IoT is likely to play a more and more important role in shaping our world, changing the way we live, work and interact with each other and machines.  
In the article \"Water Quality Monitoring System Based on the Internet of Things\" [7], the authors develop a very simple system composed of sensors (temperature, turbidity, pH and total dissolved solids), a microcontroller with Wi-Fi and a Global System for Mobile Communications (GSM) module. The data are sent to a \"cloud\" via WIFI connection, or in the case of need (alarm), an SMS is sent to the user. Note the presence in this system of an Analog-to-Digital Converter (ADC) to interface between the sensors and the microcontroller (NodeMCU ESP8266), as it does not have analog inputs. Due to the use of a WIFI network, this system is very limited in terms of monitoring coverage.  
In the system described in the article \"IoT Based Water Quality Monitoring System Using Solar Powered and LoRaWAN\" [8], a water quality monitoring system is also developed, but the data acquired are sent via LoRa to the LoRaWAN network, and there must be a LoRaWAN Gateway close to the site under study. In this system, the microcontroller used is the Arduino Nano, but as it does not have analog inputs for the sensors (temperature, turbidity, conductivity and pH), the authors used a module (CAT S/67S) that communicates with the Arduino via Inter-Integrated Circuit (I2C). This module, in addition to having analog inputs, also includes the LoRa module. As the system is mobile (floating), a GPS module was also incorporated to send the location of the measurements.