# Low Power Wide Area Network, Cognitive Radio and the Internet of Things: Potentials for Integration
## 2 Related Works  
In this section, we highlight the uniqueness of the present article by presenting evidence before this study of existing survey and literature review papers considered to be related to IoT and the role of CR and LPWAN systems in IoT-related applications. We found a number of survey articles pertaining to IoT and LPWAN, general overview of LPWAN, CR in specific IoT use-cases, and software-defined radio (SDR) in IoT applications. However, to the best of our knowledge, we found no survey article that synthesizes comprehensively information at the PHY, network, and protocol levels in order to interrelate the concept of LPWAN, IoT, and CR in view of their benefits, challenges, and future research directions. Other notable survey articles are discussed, for example, the survey on 5G networks for IoT in [12] discusses extensively about some IoT associated communication technologies. This survey provides insights into the 3 rd Generation Partnership Project (3 GPP)-based LPWAN technologies with focus on supporting massive to critical IoT use-cases. In particular, authors provided relevant state-of-the-art information pertaining to LPWAN technologies, such as the enhanced machine-type communication (eMTC), extended coverage Global System for Mobile communication (GSM) IoT (EC-GSM-IoT), Narrowband IoT (NB-IoT), and other non-cellular LPWAN technologies including LoRa, Sigfox, and Ingenu-RPMA, to name but a few. They noted that there are several open research challenges needed to be resolved towards realizing effective IoT systems, such as developing effective control and management systems for IoT networks. In [10], the authors provided an overview of LPWAN technologies with focus on LoRa and LoRaWAN testbeds. Essentially, they discussed the flaws and strengths of works published with regards to LoRa technology. This was achieved by comparing existing testbeds designed to simulate and test different LPWAN technologies and protocols. They noted that the network performance of LPWANs could be affected by interference from other networks, in addition to the logical and geographical layout of LPWAN networks. Similarly, authors in [13] reviewed the opportunities, challenges and future directions in LPWANs. Notably, they mentioned challenges related to the development of LPWAN technologies, including spectrum limitation, coexistence issues, mobility management and scalability. [PERSON] et al., in [4], provided an extensive overview of LPWANs with focus on the design goals and techniques exploited in different LPWAN technologies. They surveyed different LPWAN technologies and standards noting that these LPWAN technologies share similar approaches, thus experiencing similar limitations and challenges. It was noted in [4] that most LPWAN standards focus on the physical (PHY) and medium access control (MAC) layers with little attention to the upper layers, thereby stimulating the need for additional research solutions to upper-layer challenges. Many other survey articles have been identified in [14; 15; 16; 17], which focus on describing enabling technologies for LPWANs, including specific technologies such as LoRa, Sigfox, and NB-IoT. Most of these articles have identified a number of challenges and future research directions towards improving LPWAN technologies. The use of CR to improve the performance of IoT systems was examined in some other survey articles. For example, the use of CR in smart grid communication networks (SGCN) was surveyed in [18]. Specifically, a detailed comparison was provided between wired and wireless communication technologies with focus on the use of modern concepts such as CR, smart utility networks (SUNs) and the use of TV white spaces (TVWS) within different smart grid (SG) environments. [PERSON] et al., in [19], surveyed the use of CR in IoT with focus on applications, architectures, spectrum related issues and future research directions.