## 6 Future Research Directions and Discussion  
To enable billions of smart devices to interconnect autonomously and support massive MTC services and IoT applications, ubiquitous IoT connectivity is required to serve both urban and remote areas. This ubiquitous IoT connectivity is achieved by integrating the 5G network with LPWAN as discussed earlier. However, this 5G-LPWAN integration for ubiquitous use of IoT applications has introduced new challenges that need to be addressed. For instance, the 5G network is relatively deployed in mid-bands and in millimeter-wave bands, but these bands have medium and low ranges with low penetration rates. Hence, research involving a relative use of the 5G low band (Sub-1 GHz) is needed because the low band has a high penetration rate, long-range, and low data rate. These features are suitable for most IoT applications in cities and remote areas. The research in this sense should involve 5G architecture with mixed bands (low band, mid-band, and millimeter-wave band) according to the use case locations. For example, deployment of 5G low band in remote areas (rural communities) and some urban areas for most smart cities' applications. Deployment of the 5G mid-band in the cities to support some IoT critical applications. Deployment of millimeter-wave in some cities area to support specifically huge bandwidth, ultra-reliable low latency (URLL), and mission-critical applications. The 5G network can serve as a backhaul connectivity solution to the IoT gateways. Another technology with a high penetration rate, long-range, and low data rate that operates at the Sub-1 GHz band is the IEEE 802.11 ah also called the Halow Wi-Fi. It is necessary to exploit the tremendous benefits of the Halow Wi-Fi device because of its varying technical requirements. These technical features include multiple channel bandwidth (CB) such as 1 Mhz, 2 Mhz, 4 Mhz, 8 Mhz, and 16 Mhz; and modulation and coding schemes (MCS) [6]. Hence, researchers can leverage these numerous features to provide varying IoT applications solution. For example, the use of 1 Mhz channel bandwidth will give a longer range, which can be used to support applications that require wider coverage. Likewise, the use of high MCS up to 256 QAM (quadrature amplitude modulation) will yield a very high throughput, which can be used to support high data rate IoT applications. Therefore, research in the Halow Wi-Fi technology is encouraged for improved smart city applications. Overall, the findings and recommendations made with respect to backhaul connectivity solutions in 5G and LPWAN-IoT integration are:  
* The use of 5G low band as backhaul connectivity between LPWAN-IoT gateway for low data rate IoT applications and remote areas' applications;* The use of 5G mid-band, Weightless-N (TVWS band), and Halow Wi-Fi device band as backhaul connectivity between LPWAN-IoT gateway for medium to high data rate IoT applications in a smart city scenario;
* The use of 5G millimeter-wave as backhaul connectivity between LPWAN-IoT gateway in cities area to support very high bandwidth, ultra-reliable low latency (URLL), and mission-critical IoT applications. In addition, research is needed in mixed LPWAN devices to be integrated with 5G architecture for IoT applications. This will involve the deployment of appropriate LPWAN devices based on application types in certain areas. For example, LoRaWAN, Sigfox, NB-IoT, etc., for low-rate applications like smart meters; and Cat M1 and LTE-M for high bandwidth applications. Further, 5G-based IoT devices are recommended for smart cities' applications. This will enable IoT applications to leverage the enormous benefits of the 5G network such as network slicing, AI/ML supported applications, mobile edge computing (MEC), enhanced security, and support for massive MTC including D2D communication. Hence, research in 5G IoT devices such as 5G eMTC, 5G NB2-IoT, and NR RedCap devices, including citizen broadband radio service (CBRS) as well as its devices (CBSD) is encouraged.