The cellular network, particularly LTE, is likely to be the connectivity backbone for the Internet of Things. It is already widespread and growing, but using it is not as simple as it might first appear. Within the licensed 3GPP world for LTE that can be used for M2M and IoT applications there are basically four categories – LTE Cat 1, Cat 0, Cat M1 and Cat NB-IoT.
Cat M1 is the most advanced of these with some equipment likely to be available in early 2017 if not before. Cat NB-IoT, which many carriers believe will be the ideal IoT platform, is unlikely to see any deployment traction before 2018. Cat 0 is not universally supported and can probably be ignored, but Cat 1 exists and is being deployed and will continue to be used for IoT applications that also need a voice link.
One of the key differences between M1 and NB-IoT is the data rate, with M1 being at around 375kbit/s normally and peaking at 1Mbit/s using full duplex. NB-IoT, on the other hand, is around the 50kbit/s mark, which is more than enough for most IoT applications, such as, say, sending back meter readings to gas or electricity utilities. Cat 1 because of its ability to handle voice goes well beyond both these with 10Mbit/s uplink and 5Mbit/s downlink.
M1 has the advantage of limited mobility whereas NB-IoT is purely for fixed installations. Cat 1 is more akin to the 2G and 3G standards we have become used to. It has fuller mobility, will thus see applications in automotive, such as with connected cars, as well as in logistics for tracking and tracing. M1 will also have logistics applications as well as remote monitoring and retail, whereas NB-IoT could form the backbone for smart buildings and smart city deployments and fixed installations.
Cat M1 and NB-IoT will also, unlike standard cellular, be able to work deep inside buildings, something that LoRa and Sigfox had regarded as a key advantage for their networks. In fact, LTE scores on most check points when compared with the unlicensed spectrum alternatives. As well as making use of an existing network, it can provide enhanced security for IoT applications as well as guaranteed quality of service.
The USA is the lead market for LTE and has a clear path with Cat 1 available, and M1 and NB-IoT to follow. Europe is more fragmented with Cat 1 is supported by existing LTE networks and some carriers such as Swisscom having committed to M1 and NB-IoT and others such as Vodafone possibly deciding to skip M1 and move straight to NB-IoT.
Until 5G arrives, the IoT will need to rely on the various forms of LTE for communications. Companies such as Sigfox and those in the LoRa Alliance are rolling out dedicated networks in cities around the world. These have the drawback that a new network does need to be deployed and that in most cases the coverage is somewhat limited. In the meantime, LTE Cat 1 is probably the best solution today, with Cat M1 and Cat NB-IoT offering an alternative when they arrive in 2017 and 2018 respectively.