NB-IoT: How We Evaluate LPWA Technologies

In the world of IoT communications, reliability and stability are key aspects for a successful service. When we at Tele2 IoT launch a new product, we therefore make sure to test it thoroughly before releasing it to the market. Different services offer different challenges in their test cycle, but common for all of them is that we want to be able to simulate real world behavior in a controllable environment. That happens in the Tele2 Radio Test Lab – and it’s what we’ve done with NB-IoT as we prepare it for release.

NB-IoT is an LPWA technology that brings additional value to our connectivity portfolio in terms of power saving features along with extended coverage functionality. To be able to test the NB-IoT service and to optimize the network settings, we have spent quite some time in our internal test lab. The test lab consists of Faraday cages, which shield the test environment from any electromagnetic fields or radio interference coming from the outside world. Within this environment we can simulate and consistently reproduce test cases that would have been difficult to properly evaluate and isolate in the live network.

In addition to verifying the power saving features of PSM (Power Saving Mode) and eDRX (Extended Discontinuous Reception) that are an important part of the LPWA technologies, we also measure throughput and latency for different coverage enhancement (CE) levels. CE is a main feature for NB-IoT that through repetitions on the radio interface improves the coverage for devices residing underground or in areas where other unfavorable conditions apply.

We have previously launched LTE-M in our network. As LTE-M and NB-IoT have been developed in parallel by 3GPP for many years, they share many similarities. One important difference, however, is that low complexity always has been a design goal of NB-IoT, both on the device and on the system side. Thanks to the design simplicity, the technology aims at introducing IoT devices at a low cost, while still being high performing in areas such as reachability, device power efficiency, and network capacity. NB-IoT does lack some features provided by LTE-M, such as voice services, and more advanced transmission modes are not available. On the other hand, NB-IoT introduces a new functionality that enables data to be sent over the control plane on a signaling radio bearer. This primarily targets applications where only a small amount of data is transferred, and a slightly higher latency is allowed.  This optimization reduces the overhead of setting up a data radio bearer to the network. When combined with the traditional power saving features, this feature is very interesting for devices where a long battery life is of high importance. Along with the coverage enhancement functionality, it makes NB-IoT a very capable choice when selecting LPWA technology.

When deciding on which LPWA technology is most suitable for your deployment, you should consider factors such as the required data rate and latency for the application, if the devices need to run on battery for an extended period of time, and if the devices will be located in rural areas or in other locations with unfavorable radio conditions. Both technologies are continuously evolving, and new features are being added. Regardless of which technology that supports your use case in the best way, we at Tele2 IoT will make sure to deliver a reliable and optimized connectivity service.

If you would like to learn more about how NB-IoT and LPWA technologies can enable your IoT solution, please get in touch.

Ingmar Bäckström
IoT Architect
Tele2 IoT