# Smart Waste Collection System with Low Consumption LoRaWAN Nodes and Route Optimization
## 1 Introduction  
Nowadays, more and more cities are implementing new systems based on the Internet of Things (IoT) to obtain new data about the city, offer new services and optimize the energetic efficiency. These cities use a Smart Cities model [1] which aims to achieve more sustainable cities and make cities better places to live in. Applications developed for Smart Cities include applications for citizen security and control of people flow in cities [2], vehicle parking [3], getting information about accessible places [4], managing energy of houses [5] and public lighting [6] together with the use of smart grids, water management, waste management, health services, logistics, and a long list of other domains. These applications can be used in medium and big cities as well as in rural and suburban areas, where this and other kinds of applications based on the IoT are more commonly found. Other applications related to smart farming [7] and the cattle industry [8] have been developed in this domain. New smart sensors have emerged to develop this kind of projects, allowing the use of the concept \"IoT\" and the connection between daily used objects and the digital world. These sensors or nodes are commonly grouped into the well-known Wireless Sensors Networks (WSN) [9]. In the IoT and Ambient Intelligence (AmI) contexts [10], these objects currently equipped with sensors and actuators must naturally interact with the user. In addition, the use of wireless communication technologies makes the deployment of these elements easier in both internal and external spaces. WSN deployed in cities can equally be employed in suburban and rural places, but the economic capacities of these places are not enough to allow their implementation. This is the reason why it is essential to equip rural areas with WSN based on low-cost, little maintenance and energy-efficient technologies--for sensors as well as infrastructure--to perform the investment. Among the previously-proposed diverse applications for Smart Cities, the use of an intelligent system of waste management is especially useful in rural areas. Intelligent management comprises monitoring of the filling volume, weight and temperature of waste containers, management of the fleet of collecting vehicles, estimations of the best routes to collect waste and management of alerts in case of an incident in a container. Waste collection in towns is usually delegated to municipality groupings or is directly managed by the regional administration. The routes currently performed in the large majority of the regions are static so that the collection trucks cover predefined routes whether the containers are filled or not. Efficiently managing routes and trucks required for collecting all waste in a region allows savings in fuel, workforce and maintenance of the vehicle fleet. Journeys from one town in a region to another may sometimes be several kilometers long and skipping some towns may mean important savings on fuel and time over a year. This work presents an intelligent platform to manage waste. It consists of a network of low-cost, low energy consumption and wireless intelligent sensors, a platform with a fleet management system, a system to optimize collection routes, a monitoring web application and a mobile application to guide and track the employees of the enterprise in charge of collecting waste. This paper is structured as follows: Section 2 presents the state of the art of sensors currently employed in the literature for smart waste collection, analyses the sensor networks that can be used to design these platforms, and describes Vehicle Routing Problems (VRP) related to collection route optimization. Section 3 presents the general architecture of the system and explains its most important components: the developed node, the analysis of the employed sensor network as well as the system and the process of route optimization. Section 4 exposes a case study performed in the region of Salamanca, Spain.