Wi-SUN (Smart Ubiquitous Networks) has been rather an also-ran in the low power WAN field so far, but is showing signs of picking up some momentum in smart lighting and metering.
Although pushed most strongly by US companies, notably Cisco and Silicon Labs, the UK has proved the happiest hunting ground so far. Indeed, the City of London is cited repeatedly as a happy Wi-SUN customer for LED street lighting, although this also highlights the protocol’s dearth of other reference sites so far.
However, according to Phil Beecher, president of the Wi-SUN Alliance, which promotes the technology, other UK local authorities, including Glasgow City Council and Surrey County Council, are either in the throes of adopting the technology or are planning to do so.
At least the Alliance can boast expanding membership and growing interest from the vendor community, reflecting its fitness for those sizeable sectors in smart metering and cities. Its membership has risen by 20% over the last year to reach over 300 spanning 46 countries, with interest reaching the Far East. Indeed, the most significant recruit at the highest level of membership, called Promoter, was Hexing, one of China’s biggest smart meter companies, joining ARM, Silicon Labs, Cisco, Itron, Landis + Gyr, NICT, Omron, Renesas, Toshiba and Trilliant at this exalted level.
The protocol now therefore has truly global representation and support in these two target sectors.
It was approved as the IEEE 802.15.4g standard in March 2012 with the aim of establishing a robust protocol relying on mesh for resiliency to cater for applications requiring substantial range and intermittent but frequent communications. It was also geared towards IPv6, the latest version if the IP protocol with the address space and other features conducive for massive numbers of IoT devices.
It has taken time to gather momentum and it is only quite recently that the underlying silicon has come on stream. The recent announcement by Austin-based Silicon Labs of a new system-on-chip (SoC) family with support for Wi-SUN represents a significant step on that count. This EFR32xG12 platform is targeted primarily at smart city opportunities for Wi-SUN, combining a IPv6 mesh stack with development tools.
This is a 32-bit ARM Cortex-M4 platform with up to 1MB of flash and 256kB of RAM, as well as an integrated +20 dBm power amplifier for the sub-GHz frequencies. Landis+Gyr and Pelion are in fact cited as lead customers for the platform ahead of general availability towards mid-2021.
As Matt Johnson, general manager of IoT products at Silicon Labs, put it: “Wi-SUN is a comprehensive solution optimized for large scale, long-range LPWAN networks. Our Wi-SUN technology enables a non-proprietary approach to industrial and smart city applications, making deployments more scalable, resilient and safer.”
The current version of Wi-SUN is marketed under the heading of field area networks (FANs), designated for areas of some density where mesh networking can play a significant role. LoRa and the cellular Narrowband IoT (NB-IoT) are the two major competitors, along with Sigfox to an extent. These protocols are also targeting longer range low-power scenarios where more frequent communication or polling are required, including smart metering. This suggests that although Wi-SUN has enjoyed greatest success in the UK so far it may well gain wider interest and traction in the US where certainly Sigfox and LoRa have made smaller inroads than in Europe. In China on the other hand, with the momentum behind 5G and cellular, NB-IoT may offer stiffest resistance.