## 6 LoRaWAN and NB-IoT Implementations
### Design of an NB-IoT Network  
In our recent publication, we demonstrated the design and implementation procedure of the NB-IoT testbed [8]. The NB-IoT testbed specification includes a LimeSDR (LMS7002M) that generates the standard LTE core MME and eNB physical signals from the same CPU that runs Ubuntu Intel Core i7-8550U at 4 GHz, Ubuntu 16.04 xenial OS, 32G RAM, and x86_64-bit kernel. A multiple-input-multiple-output (MIMO) transceiver was based on field-programmable radio frequency (FPRF) for integrated circuit digital signal processing (DSP). The eNB has a 30.72 MHz reference clock, 780.500 MHz DL frequency, 725.500 MHz UL frequency on band 28 (DL EARFCN = 9435), filter order of 4, filter bandwidth of 5 MHz, a real pole first order filter of 2.5 MHz, and a transmit and receive sample rate of 1.92 MSps. The NB-IoT node device is the Fipy and Pysense expansion board programmable in the Visual Studio Code and Atom and supports NB-IoT, LTE-M, SigFox, LoRa, Wifi, and Bluetooth IoT wireless technologies. Figure 7 shows our testbed in operation with illustrations on the functionalities and Table 4 shows the parameters' configurations. With this, sensors could then be strategically positioned in various regions to monitor water quality and air pollution levels and the data collected transmitted to IoT cloud platform for analysis.  
A similar study that routed LoRaWAN traffic through EPC demonstrates that licensed and unlicensed LPWAN technologies can be integrated and served by a single network core [12]. Such integration is very relevant given the emerging theoretical studies on deploying NB-IoT on the Sub-1 GHz unlicensed band that complies with the Federal Communication Commission (FCC) and European Telecommunication Standards Institute (ELTSI) regulatory requirements [75; 76]. The MulteFire Alliance (MFA) specification presents an opportunity to utilise LTE in unlicensed, shared, and large bandwidths in the global unlicensed 5G spectrum bands to lower the cost of deploying private LTE networks. However, in this scenario, our contribution lies in demonstrating the real-world performance of a licensed NB-IoT technology for IoT application using the same end device that was evaluated in the LoRaWAN Things Network platform. An integrated gateway and network core, as shown in Figure 8, then becomes a novel deployment alternative in an environment where cellular network occupies more than 99% of coverage such as the telecommunications services market share of technologies as deployed in Nigeria [35].  
A multi-standard approach can be adopted where, for instance, a cellular IoT device can support more than one cellular network standard. Multi-radio access network (Multi-RAN) technology will allow multiple LPWAN technologies to be integrated and separated based on use case requirements. Hybrids of WiFi and LoRaWAN [77], and LoRaWAN and NB-IoT [23] are a few of the multi-RAN technologies proposed for global IoT connectivity. These will, however, come with increased processing, memory and energy consumption requirements. The increased device complexity means an increase in the cost of building applications and support infrastructure.