# Suitability of NB-IoT for Indoor Industrial Environment: A Survey and Insights
## 2 Technical Background of NB-IoT
### The Internet of Things (IoT) and Industrial Internet of Things (IIoT) Technologies
#### 2.2.3. IIoT Challenges  
Some of the challenges faced by Industrial IoT are the requirements needed for their deployment in various settings. Although different fields of application have their requirements [21], most of these requirements are expected or provided by the network layer of the IoT architecture. For example, in [66], the scalability, throughput, latency, energy consumption, topology, and security of data were explained. More so, the interoperability of devices to support the heterogeneous nature of IoT is presented as a future requirement for IoT in [67]. Standardization, architecture, and the need for an increase in storage are some other challenges that IIoT faces [68]. This research paper presents the challenges that are related to the network layer. ScalabilityThe capacity provided by the global information infrastructure to connect a large number of common objects describes the scalability. This challenge can present itself on different levels [69]. The addressing and identification of devices pose a challenge; however, this issue is mitigated by the use of IPv6 and 6 LoWPAN protocols [70]. Due to the large size of these connected objects, a high volume of data communication (big data) and networking capabilities are issues to be tackled. The application layer also contributes to the challenge posed by scalability as a result of the numerous services and service execution options that are generated by heterogeneous connected IoT devices. Therefore, one of the challenges in scalability is the ease of adding new devices to the network without major interruption. LatencySince the industrial application of IoT is time-critical and usually deployed in environments that are noisy and hard on the wireless communications, the Quality of Service (QoS) provided by IIoT is often characterized by the real-time achievement of the deadline set by an end-to-end communication task, from sensing to control execution in the system [71]. In industries, various communication traffic is generated, and depending on the type, the latency and reliability provided by IIoT can either be least critical or most critical. These types of traffic are explained in [72]. Table 4 presents a summary of the latency and reliability levels needed for the communication traffic. Industrial traffic (data) that requires fractions of seconds in latency in IIoT communications includes the emergency, critical control, and remote control traffics. This traffic is used for safety purposes, such as the leakage of radiation or poisonous gases in industries [72], continual flow of industrial processes such as automation processes, which require 1 ms latency rate [73], and control of unmanned vehicles, which require 50 ms latency and 1-10\({}^{-8}\) reliability [74]. Energy consumptionThe primary energy supply to IoT is batteries. The replacement of these batteries becomes difficult when they are fully drained. However, energy harvesting techniques are becoming promising in resolving this challenge. Ideas and research are already moving toward techniques where solar panels or piezoelectric material will be used to relieve IoT devices from the shackles of battery operations [69]. Meanwhile, efforts have been made to optimize the network protocols in the wireless communication systems. These protocols are optimized to help in reducing the amount of energy consumed by these devices. Examples are the implementation of idle time of the devices when transmission or reception of data is not taking place. \begin{table}
\begin{tabular}{c c c c c c c c c} \hline \hline
**Type** & **Latency** & **Bandwidth** & **Data Rate** & **Coverage Range** & **Energy** & **Security** & **Scalability** & **Ref. ** \\ \hline NB-IoT & 1–10 s & 200 KHz & 200 kbps & 1 km/10 km & 10 years battery life & Yes & 52,000 & [5,6,9,57,58,59] \\ LoRaWAN & 600 ms & 250 KHz and & 50 kbps & 5 km/20 km & \textgreater{}10 years battery life & Yes & Approx.