# Evolution and Testing of NB-IoT Solutions
## 5 End-to-End NB-IoT Testing
### Triangle NB-IoT Capabilities  
As explained, NB-IoT is a technology that seeks to adapt mobile networks to the connectivity requirements of low cost devices such as sensors. The key point is that NB-IoT provides direct connectivity, without intermediaries, which opens a new and wide range of scenarios and opportunities for the services and devices that will appear in the future and have not been yet imagined today. This technological revolution will not only bring great advantages, but it will present important challenges, at very different levels, to the all actors involved in the Internet of Things. From the point of view of new device manufacturers or of the operators that have to provide connectivity of these new NB-IoT, there is a need to verify the radio frequency performance, check baseband processing, ensure correct interoperability of the NB-IoT protocols, verify the stability of the devices, and measure power consumption and longevity of the batteries. For researchers looking to provide a better understanding of the applicability of NB-IoT and propose future improvements, it is important to understand the dependencies between the different parameters and be able to adjust the models characterizing the impact of the network configuration on the services that make use of NB-IoT networks. To that end, NB-IoT technology is one of the technologies integrated into the TRIANGLE testbed [3]. TRIANGLE testbed is an end-to-end testing platform for the benchmarking of applications and devices which provides communication equipments for emulating multiple mobile technologies and realistic radio conditions, mechanisms for conducting repeatable experiments, measurement probes, and instruments for measuring energy consumption. As we will show later in this section, the actual consumption of NB-IoT devices will vary greatly depending on the network configuration. Figure 6 shows how a NB-IoT device is connected via radiated or conducted RF links to a multi-technology base station emulator and a power analyzer to measure power consumption during end to end data connections. The NB-IoT network emulator enables IP data exchange between an external data server and a NB-IoT device through either radiated or conducted RF connections using real mobile logical and physical protocols. The figure illustrates both the logical control from the test framework as well as the protocol stacks involved in the data path. A full description of the testbed and its usage is provided in [1,3]. In this paper, we focus on NB-IoT testing and the extension of the TRIANGLE testbed to support it. The eNodeB emulator is equipment from Keysight Technologies which has been upgraded to support NB-IoT and eMTC CAT-M radio technologies. This equipment is able to reproduce different network configurations including configurations with multiple NB-IoT cells, and radio propagation impairments such fading and interferences. Figure 7 shows how the transmitted signal from each cell can pass through a channel emulation module and then can be additionally impaired with White Gaussian Noise signals. There is accurate control on the power and timing of the signals received by the device being tested, which makes this ideal for repeatable testing. The Antenna Configuration (MIMO scheme) and port mapping can be also defined to adapt to the device connectivity scheme. Signaling messages (see Figure 8) are used to establish connections between the device and the network, configure low level protocol parameters, and receive the power measurements reported by the device. Additionally, it is also possible to perform numerous RF and baseband measurements with the network emulator. Figure 9 shows an example of modulation analysis of the NPUSCH (NB-IoT Narrowband Physical Uplink Shared Channel) signal transmitted by an NB-IoT device. In addition to the IQ constellation, it is possible to observe the power spectrum and check multiple quality indicators, as well as to verify the transmitted power in the channel.