UWB Asset Tracking without batteries? Here's How

Over the past thirty years, we have seen the rise of a wirelessly connected world - starting from cell phones in the nineties, moving towards personal computers to all sorts of peripherals and gadgets today. The technologies that support the wireless revolution are also diverse - from long-range cellular networks (5G will soon be knocking our doors) and Low Power Wide Area Networks - LPWANs such as NB-IoT, LoRa or SigFox, to medium-to-low range Wif-Fi, Bluetooth, ZigBee, etc.

Locating objects or people is a big part of a wirelessly connected world. And when it comes to tracking the location of anything around the world, GPS immediately comes to mind. We all love GPS and how it has transformed the way we move in cities and travel around our countries or even the world. Yet, GPS (and other satellite navigation systems) is not without its own limitations.

To start off, there’s the accuracy - most smartphones give you an accuracy <5 meters outdoors. Under good weather/open sky conditions, with a fancy GPS receiver device, accuracy may reach 2 meters - but that’s about where their limit is. And mind you, this is just horizontal accuracy - They fare much worse with vertical accuracy. Secondly, GPS doesn’t work well indoors - They either lose reception completely or their accuracy is down by 50% or worse.

This means that while GPS is excellent for when you’re driving around town trying to find that restaurant you heard about (± 5 meters is hardly a problem), it sucks at finding a book in a library or your keys at home (± 5 meters is hardly a solution!)

For indoor positioning, Bluetooth or Wi-Fi can give a hand, but these aren’t purpose built for  geo-location and are far from ideal - for instance, they don’t do so well with reflections of radio signals bouncing off walls, floors, furniture, or other objects in a room.

Now, that’s where UWB comes into play.

What is UWB?

UWB is a short-range radio frequency technology for wireless communication. It operates with a high bandwidth (>500 MHz) over a very wide frequency spectrum (3.1 to 10.6 GHz). This means that UWB allows for large amounts of data to be transmitted over a short distance, all while consuming little energy. It offers a number of benefits compared to other wireless technologies, in particular accurate ranging (essentially distance measuring) and positioning, superior obstacle penetration, great improvement in multi-path issues, and high resistance to interference. This makes it the ideal choice when it comes to locating devices and objects in challenging indoor environments - where it can offer a staggering accuracy of <10 centimetres!

In spite of the recent hype, UWB is not a brand new thing and can actually be traced back to the early days of radio communication. In fact, the first-ever UWB signals were produced by Heinrich Hertz, in laboratory settings, in the late nineteenth century. However, as communication systems evolved, they seemed to incentivise narrowband technology a lot more and it wasn’t until the 1960s that UWB started getting renewed interest for use in specialized radar and communication systems - particularly from defense organisations. Later, in the 1990s, this expanded into other commercial applications - However, UWB devices and systems have, for the most part, languished in niche domains.

The decision of the US telecom regulator, the Federal Communications Commission, to make the frequency band between 3.1-10.6 GHz available for unlicensed operation of UWB devices in 2002 was a watershed moment in UWB history that significantly whetted the industry’s appetite for the modality. Several others like Japan and the European Union, soon followed with similar rules. In parallel, UWB standards have been developed by the IEEE since the 2000s - up to the latest IEEE 802.15.4 a and z versions.

Sure seems like a great time for some cool new UWB-based gadgets, but first, let’s find out the sort of applications that UWB would be ideal for.

What is UWB good for?

As mentioned above, UWB is our best bet for digital indoor positioning of people, objects, assets, etc. That’s where UWB really shines in comparison to other wireless connectivity solutions. The space of applications is vast and includes all use-cases that require precise location detection - typically indoor location-based services, hands-free access control, and device-to-device (peer-to-peer) applications. These are transversal to several verticals - smart buildings/homes, smart cities, transports, retail/logistics, industry 4.0, healthcare, safety at work, augmented reality, consumer products, etc.

Let’s dig into a couple of examples.

First, think of smart homes. UWB devices smartphones, watches, tags, cards, etc. can be used to unlock doors, locate your belongings (keys, wallet, bags, clothing items, remote controls… you name it), even start your car or open safe deposits - Yes, UWB is fairly secure compared to other wireless technologies.

Second, think of retail. How awesome would it be if all the items in a store would have a UWB-tag, allowing you to track the exact location of every single item down to the last centimetre, at any given time? How about extending this across warehousing and transport chains? This could circumvent most inventory and logistics problems - making retail operators all the happier for it!

And consumers too. If you think, for instance, that you could use your smartphone to know for sure whether your shirt of choice is available in your size at the store you’re in and if so immediately take you to it.

You may be wondering about the form and cost of such UWB-tags, and whether it’s really tenable to spread them over all kinds of items - the answer is - absolutely! In high volumes of millions of units, UWB-tags can be designed to be tiny and cheap enough, particularly if developed on top of the latest breakthroughs in self-powered, batteryless technology.

Summing up, UWB-tagged items can be tracked and traced seamlessly all the way from production facilities, to transport, through warehouses, retail stores and finally, right to your home - where you can use UWB to locate your purchased items across your storeroom, closets, wardrobes, drawers, laundry basket, fridge, garage, car, etc. Smart retail and smart home experiences working together to make our life better!

The industry is on the move

So, at this point it’s probably no mystery why tech giants are investing quite so heavily in UWB! Apple included it in their phones starting with the iPhone 11 (released September 2019), and has recently launched the AirTag - an UWB-equipped smart tracker device. About the size of a coin, the AirTag can be attached to any everyday item like keys, bags, backpacks, etc., and be used to locate those items any time you want, using an iOS app.

The AirTag is not the first smart tracker in the market: Tile has been selling this kind of tracker since 2014, although based on Bluetooth low energy (BLE) technology. So Apple was the first to introduce UWB - and with Apple’s brand power, this immediately changed the game. Despite a hefty price tag in the area of $30 per unit, it is estimated that Apple will have sold over 30 million units by the end of 2021, in only 8 months following release - roughly comparable to Tile’s aggregate sales over 6 years in business!

In the meantime, Tile created a UWB equipped version - the Tile Ultra, and other players are busy planning their entries as well -  Samsung has included UWB in the high-end trims of their Galaxy smartphone models. They’ve also launched their own UWB smart tracker - the Galaxy SmartTag+. Google has also included UWB in its latest smartphone, the Pixel 6. Other major players are expected to join the party sooner than later. For instance, Xiaomi has publicized its vision for UWB technology, and rumours are that Xiaomi’s flagship phones will soon be equipped with UWB chipsets.

So it looks like UWB is here to stay!

The core technology behind the scenes

There are several companies developing UWB radio technology, particularly for location tags and other IoT applications. Apple has designed its own UWB chip - the U1, which equips iPhones and AirTags. NXP Semiconductors, with its Trimension chipset family, equips Samsung’s Galaxy SmartTag+ and has been announced to supply Xiaomi as well. Other top suppliers include Qorvo (which recently acquired UWB- specialist company Decawave), STMicroelectronics (which recently acquired UWB- specialist company BeSpoon), CEVA (Riviera Waves UWB) and Ubisense (Dimension4 platform). All of these chipsets are designed to work with power from batteries.

Small coin cell batteries are good enough for the first generation of AirTags and similar devices. Yet, battery life and the pain of frequent replacements are major inconveniences for users. And the small batteries in AirTags have already made for some PR issues, while easy access to the battery by design, in order to make for an easier replacement, prompted serious concerns regarding child safety.

On another note, realizing our vision of a seamless smart retail and smart home experience requires extremely small, thin and cheap UWB-tags to be ubiquitously spread over millions (even billions!) of items - which is simply not possible with batteries! This is also the case for many other IoT applications where UWB tags and labels can make a difference. Last but definitely not least in relevance, as we’ve been tirelessly reiterating, batteries in IoT devices are bad business for the planet!

The future is batteryless

Self-powered, batteryless technology will be the key for widespread use of UWB - spanning a wide range of IoT devices -  tags, product packaging, labels, cars etc. Setting these devices free from the constraints of the battery will make for more original designs and form factors. And equally important, if you are a manufacturer, they make for a significant reduction to the BOM. With batteryless technology, these will be truly always-on, truly deploy-and-forget solutions.

The ONiO.zero microcontroller is nothing short of a perfect match for UWB, making such a vision eminently possible. With the support from the Research Council of Norway, ONiO has been implementing a project focused on the use of UWB technology for advanced asset location systems based on batteryless tags. So, in a nutshell, UWB is going batteryless soon - stay tuned!!