# Building Fire Evacuation: An IoT-Aided Perspective in the 5G Era
## 5 Opportunities in the 5G Era
### Massive Machine Type Communications  
From the proposed IoT-aided building fire evacuation control system, it is obvious that the major communication in the fire evacuation control system is Machine to Machine (M2M) communication. M2M transmits a small volume of data but connects a great number of devices, so it is mainly used for automated data transmission and measurement between mechanical or electronic devices, such as temperature measurement, state monitoring, infrared people counting, etc. In the 5G era, with the connection of various building systems and components to implement smart buildings, traditional IoT-enabled communication technologies, such as Zigbee, Bluetooth, GSM, etc., may become insufficient to support massive M2M communications in buildings because of their limitations in coverage and connected devices. Therefore, the low-power wide-area networks (LPWAN) are worth using. Currently, the most commonly used LPWAN in IoT is Narrow Band Internet of Things (NB-IoT).  
The NB-IoT is a cellular-based LPWAN proposed in 2016, supporting a high volume of low complexity connected devices intended to transmit small data packages. Thus, it fits the need of M2M communications in IoT applications by transmitting tiny amounts of information in a long-range [18]. Due to the fact that NB-IoT meets most 5G mMTC requirements, NB-IoT will continue to play an important role in communication in the 5G era and eventually evolve into a part of 5G technologies [81]. The benefits of using the NB-IoT in fire evacuation control is summarized as follows:  
1. Extensive indoor and outdoor coverage.  
NB-IoT provides improved indoor and outdoor coverage--approximately 1 km in urban areas and 10 km for rural areas [82]. Therefore, it is convenient to install the IoT sensors wirelessly in any place in a large complex building, not only the deep underground spaces but also floor gardens on top of the building.
2. Available for massive connection.  
NB-IoT allows for deployments of up to 200,000 devices in theory per cell [83]. With such great multiplexing, more sensors and devices in buildings are available to connect to the network and send their states to the building managers and/or fire services. This promotes the situational awareness abilities and management of resources on the fire-ground.
3. Low device power consumption.  
Devices with NB-IoT usually consume less power than other enabling technologies. The battery life of NB-IoT-based devices is over 10 years. This is highly valued for IoT applications because a large number of sensor nodes spread everywhere. Frequent battery replacement not only consumes a large amount of power but also increases the cost of labor.
4. High reliability and security.  
NB-IoT uses a licensed spectrum as other cellular technologies do, so the quality of service (QoS) and security can be guaranteed. Communicating in a licensed spectrum, NB-IoT avoids interference from other users located nearby. Furthermore, carefully specified by standards body 3 GPP, NB-IoT also benefits from the security features of cellular networks.
5. Low cost.  
The NB-IoT scores with low module costs as well as low operation and service prices. At present, the cost of NB-IoT modules is as little as USD 6-12 each [84]. The services charge is around USD 3-6 per year per device for China Mobile in China. In addition, the extensive coverage of NB-IoT eliminates the use of nodes and gateways in buildings, so the cost of deploying the network is also reduced.