Smart cities subsist on a large amount of information which is transmitted by people, devices and sensors. A wide range of wireless technologies is used for this purpose, depending on the application in question.
What is Sigfox?
The Sigfox network scores points with its range of 30 to 50 km in rural areas and 3 to 10 km in urban ones. Thanks to its narrow-band transmission in the sub-1-GHz frequency band of 868 MHz in Europe, it achieves high reliability and a longer range indoors. Sigfox is a network that offers global connectivity, including roaming and localisation functions. Low power consumption is yet another advantage of this network.
The extensive use of digital solutions can noticeably increase the quality of life in cities. In a “smart city”, daily commute times, crime rates and waste production are decreased, while air quality is improved. “Many large cities have the same problems: daily traffic jams, tight living spaces and increased pollution. Digital solutions can make an important contribution to solving these issues,” says Gernot Strube, Senior Partner at McKinsey in Munich.
For its study entitled “Smart Cities: Digital solutions for a more liveable future”, the McKinsey Global Institute investigated 60 smart city solutions for security, health, mobility, energy, water and waste, living as well as local engagement. Almost 20,000 residents were also surveyed. In order to develop and expand smart technologies successfully, cities must meet the three requirements set out by the McKinsey analysis:
1. A technical foundation with a critical mass of sensors and smartphones, which are linked over a fast mobile communications and broadband network, and whose data is made available on open platforms (open data) for local administration/authorities, residents and companies – whereby the protection of personal data must always be ensured as a basic principle.
2. A large number of applications which convert the raw data into additional benefits for the residents, e.g. in the form of real-time information, warnings and recommendations for action.
3. Wide-ranging and regular social use of smart city solutions, which leads to an actual change in resident behaviour.
However, this requires a comprehensive network. Wireless data transfer plays a very important role here because it enables the cost-efficient networking of a large number of devices, and can easily handle mobile applications. Wi-Fi hotspots allow residents to use the city’s services with smartphones or notebook computers, and 5G applications allow for the fast exchange of large data volumes, for example for video surveillance at critical transport junctions. In addition, a large number of different sensors provides “background information” for smart city applications. These sensors only transmit low data volumes and do not transfer data continuously. In light of this low data rate, Wi-Fi is not necessary and too expensive for these applications. Since the sensors are battery-operated, this excludes the use of a mobile-communication network as batteries often run out within a few days. This is why low-power wide area networks (LPWAN) are the technology of choice for many smart city applications.
Controlling street lights more intelligently
One such a low-power WAN is being provided in -Schimberg, Thuringia by Alpha-Omega Technology. The long-range wide area network (LoRaWAN) protocol being used for it offers the possibility of transferring measuring and -sensor data using little energy over very long distances – up to 15 kilometres in rural areas.
With its two-stage symmetrical encryption (for which the key is never transmitted wirelessly), the LoRaWAN protocol is a solid and secure foundation for data transfer. As the first step on the way to becoming a smart city, Schimberg converted all of its street lighting to intelligent LED lights.
In this system, integrated sensors recognise defective lights and inform the operator by means of an app. For public festivals, for example, the operating time of the street lights can additionally be set differently to the usual operating hours.
“In addition to the service which we want to offer to our residents and visitors to events, security is of course a main focus for us, in order to avoid accidents,” says Gerhard Stitz, the local mayor.
The use of additional sensors has already been planned for the near future – the aim is to monitor the fill level of the public waste containers in the municipality.
Effective waste management
A waste management solution of the sort mentioned above is already in use in Dún Laoghaire in Ireland. The port city’s waste containers were filling up faster than they could be emptied, so in order to prevent waste disposal costs from increasing even further (e.g. through additional vehicles or more bins), the local authority decided to replace the 530 conventional waste containers with 420 smart waste stations from Bigbelly. These containers have an integrated solar-powered compactor and a sensor which measures the fill level. As soon as the container needs to be emptied, the system sends information to cloud-based management software at the disposal company through a mobile-communication link. The messages are evaluated there and, every morning, a pick-up list of the containers that need to be emptied is generated using this information.
With this system, Dún Laoghaire was able to reduce the number of trucks deployed every day from four to one, save 75 per cent of the operating costs for the fleet, and assign other tasks to 60 per cent of waste collection workers.
More efficient maintenance for public toilets
Coffs Harbour in Australia also uses LPWAN to implement smart city functions. The city decided to use a Sigfox network, over which devices and sensors could reliably and securely transfer data over large distances at very low costs.
For example, Sigfox devices were connected to local monitoring systems for public toilets, which allowed the local authority to open and close doors automatically, control lighting inside and outside, receive alarms for leaks, record water meter readings and keep an eye on the work of cleaning staff.
“The Sigfox coverage lays the foundations so that municipalities can be better maintained, more secure, more sustainable and more innovative. By implementing Internet of Things solutions, the municipalities can lower their costs and serve their communities better,” says Loic Barancourt, the CEO of Thinxtra, the operator of the Sigfox network in Australia.
Synchronised traffic lights for cyclists
However, large networks don’t always need to be installed in order to realise smart city applications. In Aarhus, Denmark, for example, RFID is used as a wireless technology in order to switch traffic lights for cyclists to green. For this purpose, the bicycles are equipped with RFID tags from ID-advice, so that a sensor on the traffic lights can recognise an approaching bicycle and send a signal to the traffic controller in order to provide a green light for the cyclist.
The objective of the system is to achieve smooth-running bicycle traffic so that residents will be motivated to cycle. Having more bicycles and fewer cars improves the flow of traffic and the air quality in the city, whilst the CO2 impact and the particle emissions are reduced.