# Suitability of NB-IoT for Indoor Industrial Environment: A Survey and Insights
## 1 Introduction  
The development of ad hoc Wireless Sensor Networks (WSN) contributes to the paradigm of the Internet of Things (IoT). Many wireless technologies have emerged with this paradigm; among these are the Low Power Wide Area Network (LPWAN) such as Narrow-Band IoT (NB-IoT), Long Term Evolution for Machines (LTE-M), Long Range Wide Area Network (LoRaWAN), SigFox, etc. Since IoT involves the connectivity of massive objects to the internet for information or data gathering, monitoring, and control, a highly reliable platform is required. As such, the focus has been on the requirements that will establish this reliable connectivity. Wireless technologies are therefore geared towards meeting these requirements among which include: low power consumption, to enable longer duration of connectivity and energy savings; coverage range, for extended object reachability; reliability, for error-free data transmission and network availability; security, for data confidentiality, integrity, and availability; latency, for real-time data delivery. The standardization of NB-IoT technology by the Third Generation Partnership Project (3 GPP) in 2016 [1] has empowered NB-IoT with features that have enabled it to be suitable for wireless data communication. The expanded Discontinuous Reception (eDRx) and Power Saving Mode (PSM) techniques allow NB-IoT to implement its low power consumption scheme. For a more extended coverage range, the technology employs the re-transmission and low-frequency modulation mechanisms. For a low latency sensitivity level, 3 GPP has prescribed a tolerable latency level of 10s. The superimposition of NB-IoT on Long Term Evolution (LTE) provides the support and reliability needed for its network availability. These 3 GPP standardization features have increased the presence of NB-IoT modules in the forecast of the IoT device market share by 2030 [2]. Many wireless vendors haveentered into the business of IoT manufacturing. Since NB-IoT is integrated into the LTE infrastructure, this has resulted in its application in numerous industrial sectors, such as agriculture, transportation, automobile factories, logistics and manufacturing, while increasing the data transmission over LTE infrastructure. However, the structural settings of these industries differ and are comparatively unique. The uniqueness of these industries is characterized by heavy machinery and in some cases with metals that are highly reflective to wireless signals. These forms of settings present a harsh condition for wireless communications [3]. The deployment of NB-IoT in indoor industrial environments is faced with these harsh channel conditions, and as such, a more appropriate wireless propagation model is needed to describe the wireless system of NB-IoT communication in an indoor industrial environment. Attempts have been made to characterize the wireless propagation of narrowband in industrial settings [3; 4]. Reference [3] performed physical measurements of wood and metal processing factories for large-scale and temporal fading at frequencies of 900, 2400, and 5200 MHz. The authors identified and classified the features of the industrial environments that affect the large-scale and temporal fading. Of interest is the presentation made by [4] on its comparative analysis of indoor industrial environment propagation models with a generic representation of path-loss for 900 MHz. This paper presents a survey on NB-IoT, and as a future direction, some research areas are discussed in a bid to bring forth an appropriate representation of the NB-IoT network. This is to aid in designing suitable wireless communication systems that can be used in developing a reliable scheme for the measurement of an acceptable threshold for NB-IoT wireless performance in industries, measuring the tolerable latency sensitivity level as described in 3 GPP, and analyzing the effect of the propagation model on power consumption rates in NB-IoT.