# IoT-Enabled Smart Sustainable Cities: Challenges and Approaches
## 3 Improving the Sustainability of a Smart City
### An Illustrative Smart City: Parma
* Radio-Frequency IDentification (RFID) access management: In 2019, the city of Parma decided to introduce IoT-based technological advancements to the existing mobility services, in order to provide a better experience to users. The city of Parma dematerialized the permits to access the city center of cars and logistics operators. The traditional paper permit has been replaced with a new, technologically-advanced pass, equipped with a microchip with RFID technology, which represents a sort of digital identity of the vehicle, that in the future will be used also for different purposes. The pass will be indeed enriched with new services related to the world of mobility, such as easy parking, \"alert system\" communications, and much more. The new electronic pass, created with the aim of simplifying, speeding up and facilitating the procedures for issuing and renewing permits, has allowed the complete dematerialization and automation of transit and parking permits in use. Moreover, the municipality of Parma recently planned various deployments in different areas of the city, in order to actuate several IoT-aided actions for monitoring different aspects of the daily life of its citizenship. In detail, the city is providing with a LoRaWAN coverage through six 868 MHz LoRaWAN-powered GateWays (GWs), able to potentially manage 10k+ LoRaWAN-equipped devices, thus enabling the use of this kind of wireless network onto the city limits (in free space, these GWs will be able to cover an area with a radius of approximately 10 km). Thanks to this ongoing network coverage activity, provided by the company BT Enia, the municipality of Parma, in collaboration with other research and industrial entities of the territory, deployed the following IoT-oriented kind of devices. * Magnetic parking sensor (drowned in parking stalls): this sensing node is able to detect the parking lot's status change (free-to-busy, busy-to-free). * Vehicle passage counting sensor: this sensing node returns the amount of vehicles transited bidirectionally, on a predefined time interval, along the road in which it has been mounted. * Sensor for waste bins status monitoring: this sensing node is able to collect information about the bins filling level (based on 4 thresholds) together with a timestamp of the event, thus providing various additional estimations (e.g., time percentage in which the waste bin has been filled on a certain level, as well as full, average filling level in a certain city zone, and emptying frequency and last emptying). * Sensor for counting the passage of people: this sensing has been used to estimate the average statistical amount of people passed in front of the sensor itself, on a predefined time interval, thus returning a statistical analysis on pedestrian traffic, and in case of unpredicted events (e.g., in case of crowed events), properly reroute people masses on less crowded areas. * Environmental sensor (temperature, humidity, and pressure measurement): this sensor node is able to return the current environmental situation, while its data can be used as support to other sensing nodes, fusing together these estimations. * Smart parking sensor based on optical technology: this sensing node is able to retrieve the status of different parking stalls in a monitored parking area with a timestamp. * Sensor for measuring the environmental acoustic pressure: this sensing node is able to retrieve the average acoustic pressure level (dimension: [dB]) on a predefined time interval, thus providing an alert in case certain unpredicted events happen (e.g., intense traffic, road construction sites, etc.).