# A Comprehensive Study of the Use of LoRa in the Development of Smart Cities
## 4 Results of the Analysis of the Selected Works
### Analysis of the Application Layer
#### 4.1.3 Traffic Control and Transportation  
IoT applications related to traffic control or transportation are mainly focused on parking systems, traffic, streetlights, congestion monitoring, and real-time public transportation. Generally, traffic in the center of a city is an important issue, not only because it increases the time of transportation for the citizens, but also because it decreases the gross domestic product (GDP) [34]. Smart lights are used to improve power efficiency and to reduce carbon dioxide emissions. Led lights consume approximately 0.49 MWH per led lamp, but the use of IoT allows the development of automatic dimming controls, improving the power efficiency of these light systems by over 85% [36]; dimming controls interact with passive infrared sensors that detect the presence of people and vehicles. Magnetometers allow the detection of objects like cars, motorcycle, and transportation vehicles. On the basis of data recorded from sensors at a traffic intersection, it is possible to design a congestion model to calculate the operating time of traffic lights for different lanes [37]. Finding empty parking spaces is another important issue for many cities, but the use of magnetic sensors is prone to deliver false positives. Three main challenges in the design of parking solutions based on magnetic sensors are (i) environmental changes; (ii) special characteristics of parking slots; and (iii) time-varying factors due to geomagnetic fields or dwindling battery lives [38]. Some researchers indicate that alternatives to sensing technologies such as RFID, ultrasonic sensors, or video-image processing require excessive overhead for installation and maintenance, while solutions that involve the detection of signals reflected from vehicles like microwave radars or ultrasonic sensors increase the power consumption and are extremely susceptible to environment interference. iBeacons and RFID are also used to determinate the available number of park slots [39].  
Information about buses is an aspect considered relevant in the transportation domain because it delivers data for citizens about when a bus will arrive to a bus station. Bus information is sometimes difficult to collect in a precise manner due factors like weather and congestion. One solution of this issue is the usage of GPS for tracking bus location. However, it requires expensive communication charges, and the user needs a mobile network to access such information. An cheaper alternative could be LoRa [40]. A bus location information acquired by GPS would be broadcasted to bus stations using the LoRa network. This solution would reduce communication charges [41]. Other solutions that could be introduced using LoRa are air pollution and road surface condition monitoring [42].  
The use of bikes for transportation in cities is growing as an alternative to reduce air pollution. In this sense, citizens can borrow a bike and return it to any bike station around a city. Sensors are installed in bikes for collecting real-time information about the routes where a bike was used. Additionally, the system could tell the user where a nearby bike station is. In contrast to traffic models developed for buses in which some movement patterns are expected, bikes networks are more unpredictable and complex to define, since each user will move in a different way. The integration of weather information could add new services for the user, allowing him/her to know if the weather conditions are comfortable for riding a bike [43].