Global footprint of Cellular Nb-IoT and LTE-M
Cellular LPWAN has been heavily deployed by Mobile network operators. Based on the rollout report by the GSMA Whereas by September 2018 there were only 66 networks in 34 countries using either LTE-M or NB-IoT - as of June 2020 there are now 131 networks in 56 countries that have either or both technologies available. Although the GSMA report gives a good baseline - we have also seen that several operators have activated the technology and then later on announced it over GSMA.
While NB-IoT has a footprint of 93 networks (+43 in 2 years) in 54 countries (+22), LTE M is available in 38 network (+22 in last 2 years) and 28 countries (+15). NB-IoT is more dominant in the eastern hemisphere, whereas LTE_M is more dominat in the western hemisphere.
With the increase of the global footprint of Cellular IoT device manufacturers can now seemingly provision low-cost devices globally - especially when using device that can do both - LTE-M and NB-IoT. But there are some challenges to consider.
Coverage area restricted to region / locations
NB-IoT and LTE-M are deployed on LTE towers. While LTE-M solely uses existing LTE frequencies restricted to 1.4 Mhz Bandwidth, NB-IoT can be deployed either on stand-alone frequencies, LTE guard bands, or LTE in-band. GSMA states that all three deployments are supported, with guard-band and in-band deployments being more cost-efficient.
The problem is that NB-IoT and Cat M1 have not been deployed in all LTE markets by operators yet and LTE coverage alone is still not omnipresent.
Low-cost Narrowband NB-IoT and CAT-M modules usually fall back to GSM to make sure that their service is consistently available. Therefore device manufacturers need to rely on more expensive chips that support also the legacy technologies, which does not only impact their business model due to higher costs but also the predictability of the devices’ battery life.
Only few networks with NB-IoT roaming available
In June 2018, the first European NB-IoT roaming trial between Vodafone and Deutsche Telekom took place. Two years later Deutsche Telekom, Vodafone, Telia and Swisscom have signed roamign agreements but as of today roaming is not implemented in the network. In other continents roaming is still not available due to missing alignment on technology and commercial model.
What does that mean for IoT device manufactures within verticals such as transport, logistics, and cargo tracking – all of which
have provided a substantial business case for cellular IoT? As it stands, they simply cannot use NB-IoT as a viable alternative.
No single choice for connectivity providers
For LTE-M roaming is possible - it is working over traditional LTE roaming agreements. Some network operators have be blocking roaming SIM for IoT use cases.
So IoT device manufacturers face a tough decision. For embedded SIMs, they need to select which Service Provider supplies the connectivity. For non-roaming technology Nb-IoT this means that contract negotiations and agreements need to be made on a country-by-country basis and, additionally, shipping SIMs with different service profiles based on the destination country. Logistics and automated billing becoming increasingly complex in cases where manufacturers receive invoices from multiple clients worldwide. The alternative of using GSM, UMTS and LTE and LTE-M technologies with global SIMs available through a single billing channel streamlines this entire process.
No redundancy coverage per country
There are only a limited number of countries where more than one operator offers Narrowband services. Relying on Narrowband means that the device manufacturer is directly dependent on the coverage and availability of the operator. With legacy access technologies such as GSM, UMTS, and LTE and a multi-network SIM card, service providers have a more reliable network than on Narrowband.
No seamless mobility
NB-IoT, as it is deployed today, does not support seamless mobility and handover. In LTE, Cat M1 handover is supported by the 3GPP specification, but not configured in all live networks due to power-saving reasons. This limits the addressable market of Narrowband technologies to non-real time, stationary applications.
Limited support for SMS over Narrowband
The networks on which cellular narrowband is deployed, do not always support SMS services over NB-IOT or CAT-M1. Several operators have yet not deployed the SMS functionality for Narrowband. Whereas SMS seems old-fashioned, there are still several use cases for SMS in the IoT domain. MT SMS can be delivered with a delay when the devices are not online, and MO SMS can be sent only through signaling channels even under poor radio conditions. Further Over The Air (OTA) updates of SIM profiles, e.g., adding new IMSIs or changing the SIM traffic steering on multi-IMSI applets are done through SMS.
Narrowband is an up-and-coming technology that provides energy and cost advantages over other access technologies. Operators worldwide have seen the advantages and the business case, but Narrowband offerings are only appealing to IoT solution providers that are only targeting a few large markets (e.g., US). Inadequate coverage and nonexistent roaming agreements leave IoT device manufacturers with the burden of making a significant commitment to specific connectivity provider per country. Nevertheless, we believe that with the ongoing deployment of Narrowband functionality on more networks, new roaming agreements as well as improved seamless mobility, Narrowband will become a viable choice for more use cases.