Cellular is the best connectivity technology for smart street-lighting in cities, reckons Netherlands based lighting company Signify. The rise of ultra narrowband (UNB) for outdoor smart lighting in cities, popularized by UK rival Telensa, will not cut it, the company has said.
Proprietary UNB-based technologies, also deployed by utility companies for smart metering, work fine for connected lighting, but only if the lighting network is not designed to support a wider array of smart-city applications. And in these circumstances, narrowband radio-frequency (RF) mesh networks also serve, and are cheaper to deploy, the company has said.
“Ultra-narrowband is appropriate for smart and connected lighting, yes; but it will be your achilles heel if you ever want to add the sensors,” said Jacques Letzelter, senior vice president of Signify’s commercial public business segment, in interview with Enterprise IoT Insights.
“It is inappropriate for smart-city use cases. Because more sensors requires more bandwidth. If you have a ultra-narrowband network, well, you can say [everything] is possible, but the customer experience will be poor – they won’t get the frequency of updates they need.
He explained: “Some connectivity technologies are very good for lighting. They are cheap, and fast enough. They support for remote monitoring, occasional changes in the lighting, and upgrades on the firmware. But these technologies don’t offer much more, and [smart] lighting needs more.”
Ultra-narrowband technologies are constrained technically, in terms of bandwidth, and also by their usage of unlicensed frequency bands, which impose limits on payloads and delivery schedules, Letzelter noted. The addition of new sensors, beyond straight lighting controls, will push these networks too hard, he said.
“Take a camera-based sensor monitoring the presence of cars in parking spots; that has to be able to communicate on the spot, on an event basis, as often as a car enters and leaves the parking space. With that, the bandwidth might not be so big, necessarily, but the application needs to access the network frequently, to deliver a payload of a certain size.
“That shuts down the possibility to use an unlicensed network, just because there are rules about how many bytes you can send per day. It might be that wireless at a certain frequency – 868MHz in Europe, for instance – could do the job, but the rules around unlicensed bands forbid you to do it if you are going to remain professional.”
Signify is backing cellular for smart city deployments that leverage the lighting network for connectivity, as well as power and grid-like layout and positioning. Specifically, it recommends LTE-M as the starter solution for smart city networks, but is bundling modular hardware with its luminaires to ensure radios can be upgraded, just as sensors can be plugged in.
Letzelter said: “You have to start with the use case. Municipalities talk to us because of connected lighting, and they want it future-proofed – they use these kinds of terms. But they don’t actually know what they want yet. They can’t define the level of smartness they want. It’s nascent, still. So our recommendation is LTE-M, which gives you access to quality of service, and scalable bandwidth.”
Where cities only want to deploy connected lighting, without a plan or vision to layer in additional sensors onto their connectivity network, RF mesh is a better solution than ultra-narrowband, according to Letzelter. Specifically, Signify is pushing mesh networking using Zigbee (IEEE 802.15.4) in such cases, the same as it recommends for indoor smart-building deployments.
“If a customer closes the door on future-proofing, or on sensors requiring higher bandwidth, then we recommend to stay in RF mesh. Because lighting alone does not need LTE-M,” he said.
Signify claims to lead the market for connected lighting. It manages 56 million connected light points, across sundry indoor and outdoor venues, according to its own figures; it installed 12 million in 2019. Seventy-eight per cent are LEDs; the rest are conventional lamps.
But these figures represent an early showcase for connected lighting. In total, the company claims In total, it has around 309 million luminaires in the outdoor lighting market, covering also non-connected light-points. The number is projected to grow to 345 million luminaires by 2028, and the share of LED-based bulbs will go from 39 to 85 per cent in the period, and the percentage of connected bulbs will go from six to 24 per cent, it calculates.
The market for outdoor smart lighting in cities is being driven by twin drives for sustainability and security, with the first shifting orders for LED swap-outs and the second making the case to spring cameras and other sensing tools off the lighting network.
“The outdoor space will get LED-ified very fast, now. It has been a big thing in the UK, and big in mainland Europe; it has been a little slower moving in the US, but it will accelerate everywhere… [And] security and safety are keywords. That is very clear, and will happen big-time. That is why we are seeing so many cameras, and lighting helps as well both by lighting up spaces and hosting these other sensors.”
But where the energy savings from LEDs make lighting upgrades attractive for cities, and easier to negotiate for lighting companies, the business case for smart applications in cities is less clear, acknowledged Letzelter, even despite his company’s own projections on uptake of connected infrastructure.
“The trend to switch to LEDs is very clear in outdoor lighting; the trend around smartness is less so – in terms of the percentage of purchase orders also specifying connectivity,” he said.
