You've heard of Wi-Fi, Bluetooth and 5G. Now it's time to learn another wireless communications term: ultra wideband, or UWB. Smartphone leaders Apple and Samsung have built it into their high-end models, including the iPhone 11, iPhone 12, Galaxy Note 20 Ultra and now the Galaxy S21 Plus and S21 Ultra. The Apple Watch Series 6 also has UWB built in. The technology lets you pinpoint the exact location of phones, key fobs and tracking tags, helping you find lost dogs or automatically unlock your car.

UWB calculates locations to within less than a half inch by measuring how long it takes super-short radio pulses to travel between devices. It's well suited to Samsung's new SmartTags, which use Bluetooth to start but will get UWB support in the future, and Apple's long-expected AirTag trackers. Carmakers including Audi, BMW and Ford are also hot for UWB.

Right now UWB's uses are limited, but as it matures and spreads to more devices, UWB could lead to a world where just carrying your phone or wearing your watch helps log you into your laptop as you approach it or lock your house when you leave.

"Being able to determine precisely where you are in an environment is increasingly important," said ABI Research analyst Andrew Zignani, who expects shipments of UWB-enabled devices to surge from 150 million in 2020 to 1 billion in 2025  "Once a technology becomes embedded in a smartphone, that opens up very significant opportunities for wireless technology."

Here's a look at UWB and its uses.

What's UWB good for?

Satellite-based GPS is useful for finding yourself on a map but struggles with anything much more precise and indoors. UWB doesn't have those handicaps.

UWB could switch your TV from your child's Netflix profile to yours. Your smart speaker could give calendar alerts only for the people in the room. Your laptop could wake up when you enter the home office.

Imagine this scenario: You leave the office and as you near your car, receivers in its doors recognize your phone and unlock the vehicle for you. When you get out of the car at home, the receivers recognize you're no longer in the vehicle and lock the doors.

With UWB, your home could recognize that you're returning at night and illuminate your walkway. The technology could then automatically unlock your front door and turn on your home sound system, which follows you from room to room. "I'm walking in a sound and light cocoon in my house," said Lars Reger, chief technology officer of NXP Semiconductors, a UWB proponent whose chips are widely used in cars.

Bluetooth-based location sensing takes at least two seconds to get an accurate fix on your location, but UWB is a thousand times faster, Reger said.

UWB will add more than convenience, supporters say. Conventional key fobs have security problems in regard to remotely unlocking cars: criminals can use relay attacks that mimic car and key communications to steal a vehicle. UWB has cryptographic protections against that sort of problem.

This same ability to track your movements has downsides, particularly if you don't like the idea of the government following your movements or coffee shops flooding your phone with coupons as you walk by. But with today's privacy push, it's likely phone makers won't let devices track your phone without your permission.

How is Samsung supporting UWB?

At its Galaxy S21 launch event Thursday, Samsung touted UWB as a wireless technology that'll bring new convenience to your life. That includes unlocking your house or car as you walk up to it.

"With Digital Key, you'll be able to open the door of your house with your mobile device," said Kevin Chung of Samsung's direct-to-consumer center during the launch event. "You'll be able to unlock your car door with your phone. The door will unlock when you reach it -- no sooner, no later."

You'll be able to send digital keys to friends or family members, and Samsung's AR finder app will point the direction to your car in a crowded parking lot. Samsung announced digital key partnerships with BMW, Audi, Ford and Hyundai's Genesis Motor.

Samsung will later offer UWB SmartTags, too.

How is Apple supporting UWB?

iPhones since the iPhone 11 family have Apple's new UWB chip, the U1. It joins a handful of other processors Apple has developed, including the A series that powers iPhones and iPads, the M1 at the heart of new Macs and the T series that handles Touch ID and other security duties on Macs.

"The new Apple-designed U1 chip uses ultra wideband technology for spatial awareness -- allowing iPhone 11 Pro to precisely locate other U1-equipped Apple devices. It's like adding another sense to iPhone," Apple said of the U1 chip when it arrived. "With U1 and iOS 13, you can point your iPhone toward someone else's, and AirDrop will prioritize that device so you can share files faster. And that's just the beginning."

Apple only promises UWB links between its own devices for now. But UWB standardization should open up a world of other connections, and software tweaks should let Apple adapt as UWB standards mature.

Apple's years of UWB work are evident in several patents. That includes patents for shaping UWB pulses for more accuracy in distance measurements, using a phone, watch or key fob location to enter and start a car, calculating your path toward a car so your car can send your phone a request for biometric authentication, and letting Bluetooth and UWB cooperate to grant you access to your car.

Who else is interested in UWB?

Other companies involved with UWB include consumer electronics giants Samsung and Sony; chipmakers Decawave, Qualcomm, NXP and STMicroelectronics; carmakers Volkswagen, Hyundai, and Jaguar Land Rover; and car electronics powerhouse Bosch. Another notable player is Tile, which has sold tracking tags for years to help you find things like keychains and wallets.

Confusingly, those companies have banded together into two industry groups, the UWB Alliance formed in December 2018 and the FiRa Consortium (short for "fine ranging") that formed in August. Samsung joined FiRa, Apple isn't listed as a member of either.

On top of that, there's the Car Connectivity Consortium that's working on digital key technology. The three groups have figured out who's doing what now to avoid stepping on each other's toes, Harrington said.

FiRa is working on standards to ensure UWB devices work together properly, while the UWB Alliance is trying to minimize UWB problems from the expansion of Wi-Fi into the 6GHz radio band that UWB also uses. For example, there are brief pauses in Wi-Fi signals sent in the 6GHz band, and UWB transmissions could sneak into those gaps, said UWB Alliance executive director Tim Harrington. 

How does UWB work?

The idea behind UWB has been around for decades -- indeed, the University of Southern California established an ultra wideband laboratory called UltRa in 1996. Some of the concepts date back to radio pioneer Guglielmo Marconi, Harrington says.

UWB devices send lots of very short, low-power pulses of energy across an unusually wide spectrum of radio airwaves. UWB's frequency range spans at least 500MHz, compared with Wi-Fi channels about a tenth as wide. UWB's low-power signals cause little interference with other radio transmissions.

UWB sends up to 1 billion pulses per second -- that's 1 per nanosecond. By sending pulses in patterns, UWB encodes information. It takes between 32 and 128 pulses to encode a single bit of data, Harrington said, but given how fast the bits arrive, that enables data rates of 7 to 27 megabits per second.

The IEEE (Institute of Electrical and Electronic Engineers) developed a UWB standard called 802.15.4 more than 15 years ago, but it didn't catch on for its original intended use, sending data fast.

But location sensing made UWB a hot topic again?

Companies like Spark Microsystems use UWB for data transfer, but most tech giants like it for measuring location precisely. Even though 802.15.4 flopped when first created years ago,  UWB's renaissance is occurring because its super-short radio pulses let computers calculate distances very precisely.

Now UWB development is active again, for example with the 802.15.4z standard that bolsters security for key fobs and payments and improves location accuracy to less than a centimeter. Fixing today's relay attack problems, where someone with radio technology essentially copies and pastes radio communications of key fobs or smartphone unlocking systems, was a top priority for 802.15.4z. "With the precise timing you get off UWB and the ability to know exactly where you are, you can cut the man in the middle [relay] attack completely," Harrington said.

Another area of active development is improving how you can use your phone to make payments at a payment terminal.

Radio waves travel about 30 centimeters (1 foot) in a billionth of a second, but with short pulses, devices can calculate distances very exactly by measuring the "time of flight" of a radio signal to another device that responds with its own signal. With multiple antennas positioned in different spots, UWB radios can calculate the direction to another device, not just the distance.

UWB dovetails nicely with the internet of things, the networking of doorbells, speakers, lightbulbs and other devices.

It's already used for location sensing. NFL players have UWB transmitters in each shoulder pad, part of broadcast technology used for instant replay animations. A football's location is updated 2,000 times per second, according to Harrington.

Boeing uses UWB tags to track more than 10,000 tools, carts and other items on its vast factory floors.

UWB uses very little power. A sensor that sends a pulse once every second is expected to work for seven years off a single coin battery. 

Verizon has something called 5G Ultra Wideband. Is that the same thing?

No. Verizon uses the same words, but it's merely a branding label.

"5G Ultra Wideband is our brand name for our 5G service," said spokesman Kevin King. "It's not a technology."