The low power WAN (LPWAN) field has become a major wireless communications sector on the back of the IoT, especially for field applications such as smart metering and environmental monitoring. But it has been shrouded in confusion over terminology and protocols, especially as we enter the 5G era, as we have seen from various recent forecasts for the sector.
Confusion is caused by LPWAN being portrayed as an alternative or even competitor to cellular when two of the four main wireless communication protocols in the sector are under the 5G stable. Those protocols are NB-IoT and LTE-M, both 4G-based and operating in licensed spectrum. The two primary non-cellular LPWAN protocols are LoRaWAN and Sigfox, operating in unlicensed spectrum.
One recent survey from Strategy Analytics forecast that the proportion of global IoT connections accounted for by 5G would soar from less than 1% in 2020 to 40% by 2030. That may even understate the growth, but in any case the headline is confusing to those unfamiliar with LPWAN terminology who might assume this was talking about mainstream 5G, rather than the aggregate of NB-IoT and LTE-M.
These are distinct protocols and very much geared to the IoT. In fact, NB-IoT does not even support mobility and so is confined to fixed IoT services for devices such as parking meters or sensors. LTE-M, by contrast, is more in the traditional cellular mode in supporting mobility and indeed voice if required, as well as higher capacity and latency low enough for real time applications.
Another recent survey, from Global Market Insights (GMI), focused on the LPWAN market as a whole, estimating that globally it would be worth $80bn by 2027. This survey was primarily about the four main protocols, so incorporating both cellular and non-cellular. There was some synergy between the two studies in that GMI also attributed much of the growth to surging deployment of the two cellular options, LTE-M and NB-IoT.
Yet that survey also singled out Sigfox for significant growth worldwide at a CAGR of 40% between 2021 and 2027. This is curious, as the significant Sigfox user base is largely confined to Europe and the protocol has singularly failed to penetrate North America.
Founded in 2010 and headquartered near Toulouse in France, Sigfox pioneered the LPWAN movement with its eponymous wireless protocol, building up a strong and loyal following across Europe radiating from its French base.
It applied the concepts of software-defined radio executed over a cellular network in the cloud, to home in on very weak signals using ultra-narrowband (UNB) modulation in just 200 kHz of spectrum with each message a mere 100 Hz wide. These messages are transferred at either 100 or 600bps, depending on the region, so suitable only for low bit-rate applications such as metering. But this met a growing unfulfilled need at the time for low power and low cost IoT connectivity where the cost of full cellular could not be justified or afforded. It also scored by having a long range, up to 10 kilometers in urban areas or 40km in rural, with ability to penetrate many walls and reach some underground locations.
On the back of European growth, Sigfox sought to enter the USA in 2017, but failed to gain much traction beyond the odd campus, for a combination of technical and commercial reasons. A primary handicap was that Sigfox relied on mobile networks for its cloud connectivity and while operators were supportive in the early days had come to see the company, as well as the LoRaWAN protocol, as competitors as they started promoting the two cellular alternatives that slotted into their own spectrum.
Then the technical problem was that, while Sigfox operated in the 868 MHz band in Europe, as it still does, in the USA it had to move into part of the unlicensed 900 MHz band, where it had to compete with numerous sources of signals, such as smart meters and various domestic IoT appliances, which caused interference. This noise reduced range, compounded by regulatory constraints on airtime for each transmission.
Being essentially a one-way simplex technology – a design goal to establish and maintain network connections while avoiding the overhead of acknowledgements- also came to be seen as a limitation. Partly as a result, LoRAWAN gained momentum as the preferred non-cellular unlicensed option in the USA, sweeping Sigfox aside.
Sigfox did have rather more success in various countries across the other regions, but this was still patchy. In Japan, Nippon Gas Company has been using the protocol for 850,000 smart gas meters rolled across the country during 2020, while UK-based Wireless Network Development (WND) is promoting Sigfox across much of Latin America. However, it looks as though, apart from isolated successes and scattered pockets of deployment elsewhere, Sigfox will continue to be largely confined to Europe, leaving the other three main contenders vying for LPWAN share elsewhere.