IoT technologies like Bluetooth (the most popular choice) are finding their way into smart city projects, from traffic monitoring and control to Internet-enabled trash cans.
Large towns, municipalities and other urban areas are becoming smart cities by taking advantage of the benefits of the Internet of Things. IoT technology offers the advantages of communications, convenience, efficiency and energy savings that can enhance any city. But it requires adding to the infrastructure. IoT has already been deployed in the infrastructure of some progressive cities but there is much more possible. Smart cities help citizens as well as the cities in multiple ways. Some cities are investing for the benefits rather than any expected return on investment (ROI).
Smart cities use IoT and multiple sensors to collect data at many locations, analyze it then, in some instances, take action of some kind. Collecting the data is the easy part but analyzing it and deciding what to do with it is the real challenge. Figure 1 shows how it works.
Here are some of the popular current applications.
- Traffic monitoring and control. Manipulate traffic lights to keep traffic moving thereby minimizing congestion, reducing emissions and lowering fuel consumption.
- Monitoring parking lots and garages to help citizens find parking via a cell phone app.
- Environmental monitoring to signal conditions harmful to the public.
- Use of smart meters to remotely read electric, water and gas utilities for efficiency.
- Adoption of video cameras for traffic and pedestrian safety. Helpful to police in reducing crime but may cause concern for privacy.
- Beacons to alert citizens of relevant news, traffic conditions, nearby events, sales, etc.
- Street light monitoring and control for safety and energy savings.
- Smart trash cans that send a notification when full to be emptied.
- Infrastructure monitoring (bridges, water plants, etc.)
A forthcoming adoption of the DOT/NHTSA vehicle-to-vehicle (V2V) and vehicle-to-infrastructure (V2I) systems, a form of IoT, will bring further benefits. V2V lets vehicles talk to one another for safety while V2I roadside units provide weather, traffic, construction and other data to improve safety and congestion.
Making IoT Happen
One key decision for Smart City IoT is the choice of wireless technology for the sensors and actuators. There are many to choose from. These include Bluetooth, LoRa, Wi-Fi, Weightless, Thread, ZigBee, Sigfox and the cellular- based IoT like LTE-M and NB-IoT. The important factors to consider are the wide versatility of the standard, its scalability that will let the system grow seamlessly, the compatibility and interoperability of products over time, and over the air (OTA) software upgradability, and the security. An example of a solid choice is Bluetooth.
The popular wireless technology Bluetooth (BT) is by far the most widespread short-range wireless standard. Billions have been deployed. Its unique features and benefits make it a good choice for new smart cities infrastructure uses.
Interestingly it all begins earlier than you think. BT’s key modulation and access method is frequency hopping spread spectrum (FHSS), which was invented during World War II (1945) by famous actress Heddy Lamar. Her patent was ignored initially but was eventually used in secure military communications in later conflicts before finally being adopted by Bluetooth in 1998/1999.
Over the years, the BT Special Interest Group (SIG) has fostered the evolution of BT with a continuous stream of improvements, upgrades, and enhancements. Today, its multiple versions and support options allow it to address a wide range of applications.
The primary features of Bluetooth are summarized below.
- Operates in the 2.4 to 2.4835 GHz unlicensed spectrum shared with Wi-Fi, ZigBee, and others
- Uses Gaussian Frequency Shift Keying (GFSK) modulation
- Employs frequency hopping spread spectrum (FHSS) technology for multiple access and security (1600 hops per second over 79 channels)
- Power output: Three classes: 1 mW, 10 mW, 100 mW
- Data rate: Depends on version: 1 Mb/, 2.1 Mb/s, 3 Mb/s, 24 Mb/s
- Range: <10 to 100+ meters
- Networking: Piconet with one master and up to 7 slaves, mesh option
- Authentication and security inherent
- SIG tests and certifies all products to ensure interoperability
The newest version is called Bluetooth Low Energy (BLE). Sensors can operate for years from a coin cell as BLE uses shortened packets and low power techniques that are an excellent fit with smart city requirements.
Bluetooth is an excellent choice but there are other technologies to consider. See Table 1. Multiple standards have emerged to address most IoT needs. Wi-Fi is an option but generally far too complex, costly, power consuming and fast for most smart city IoT use cases, except for video. One good thing about both Bluetooth and Wi-Fi is that both are supported in all smartphones making citizen or city worker interaction possible.
Another good choice is ZigBee, which has already been adopted in some smart cities. But that’s not all. Technologies categorized as low power wide area networks (LPWAN) have been developed to meet the need for greater range between remote node and the gateway. The LPWAN contenders are Sigfox, LoRa, unique Wi-Fi versions, and Weightless. The newer cellular standards like LTE-M and NB-IoT are another option. Even the forthcoming 5G systems are expected to be a factor in smart city IoT. Service contracts are needed but links are reliable and good for up to several miles.