Here’s How Apple Could Put An LTE Radio Into Its Watch Without Killing The Battery

How do you reconcile cellular’s power-draining tendencies with the need for all-day battery life? You carefully manage the data connection.

Here’s How Apple Could Put An LTE Radio Into Its Watch Without Killing The Battery
[Photo: Flickr user Maurizio Pesce]

The surprise in Bloomberg‘s Friday scoop about an LTE Apple Watch was not that Apple has been working on adding cellular connectivity to the device. It’s that the company is reportedly ready to bring it to the market as soon as this fall.


Apple had already added a GPS radio to last fall’s Apple Watch Series 2, which left only one more major radio to add in a future watch–a cellular one. The company would likely have done so a long time ago except for the fact that cellular radios require a lot of battery power to operate.

Even before the factor of LTE connectivity, putting a battery inside the Watch that provided enough power for a full day of use and was small enough not to ruin the device’s svelte looks was quite an engineering challenge. Knowing Apple, the company probably isn’t excited about making a fatter or wider Watch.

Bloomberg‘s Mark Gurman, Scott Moritz, and Ian King suggest that adding the new radio became possible this year because Apple has figured out some new ways of making an internet-connected Watch more power efficient. But several analysts and developers I spoke to on Monday remain skeptical of the Bloomberg report’s contention that Apple is going to release an LTE Watch this year. (Even the story’s authors hedged a bit with a disclaimer: “The new device could still be delayed beyond 2017–indeed, the company had already postponed a cellular-capable smartwatch last year.”)

Creative Strategies president and long-time Apple analyst Tim Bajarin says he still has his doubts about an LTE Apple Watch arriving this fall. However, “it’s inevitable that at some point this will happen and I believe Apple’s goal would be more focused on untethered access to data and possibly music,” he adds.  “An LTE radio in the watch would allow . . . untethered flexibility, especially if one is running, swimming, or doing other sports-related activities . . . or in places where carrying the iPhone is not feasible.”

If Apple truly does release an LTE Watch this fall, it will almost certainly have to place restrictions on some of the battery-hogging services that cellular connectivity would make possible. “I expect various capabilities will be limited at first, and that even when functioning sans phone, the radio won’t always be on,” says Ari Roisman, CEO of the video messaging app developer Glide.

Video and music-streaming services–whether via Apple’s own or those of third-party app developers–are at the top of the list of likely suspects for sapping the LTE Watch’s battery. High-quality audio and video streaming at high frame rates would be especially draining.


As Roisman suggests, the best thing Apple can do to conserve the Watch’s battery is to avoid using the LTE radio whenever possible. That could involve it still depending on the iPhone for assistance when possible—which would mean that the Watch wouldn’t be entirely autonomous, and still wouldn’t be an option for people who own Android phones.

Even when the Watch is far away from the iPhone or Wi-Fi, it still might not have to run the LTE radio all the time to play music or video. Apple would likely use “smart buffering” techniques to push music down from the cloud onto the Watch in advance of when the user wants to hear it. The company may be able to anticipate the music the user will want preloaded based on listening histories and favorites. The music could be preloaded to the Watch when the iPhone is nearby or when a Wi-Fi connection is available (perhaps during overnight charging). So the Watch’s LTE might be used to stream part, but not all, of the desired content.

One Day At Minimum

Apple already weathered the initial storm of criticism over the Watch’s battery life being merely a day, and has established a day of usage as the minimum acceptable benchmark. It is very unlikely that the company would try to convince consumers that less than a day of life is acceptable for the LTE Watch.

Hitting that one-day benchmark starts to sound a little more doable when you drill down on how people might use the LTE Watch. The Watch would be on the user’s wrist all day, but the LTE radio would be off most of the day.

The LTE Watch’s compelling use cases happen during times when carrying the iPhone just isn’t practical. The user may rely on the Watch’s LTE radio during runs or other workouts (when lugging the phone along is a hassle) to continue getting texts, calls, app notifications, or emails as usual. There may also be times when the iPhone runs out of battery and the Watch will to step in to keep the user fully connected.

But there are still lots of situations where having the iPhone along isn’t really a hardship, like when you’re driving around town doing errands. It’s during those times that the Watch’s LTE radio can stay off, conserving the battery.


Intel Modems

The Bloomberg report says Intel will provide the modem chips in the LTE Watch; and it’s in the Watch’s integration of those chips, says Above Avalon analyst Neil Cybart, that Apple may find its best battery-saving innovations.

“While we will have to wait and see just what is found in a cellular Apple Watch, my suspicion is some of Apple’s ongoing work with LTE modem chips is at play here,” Cybart says in a note to Fast Company. “A more customized solution could lead to significant power efficiencies.”

While Apple’s relationship with modem maker Qualcomm has gotten decidedly rockier (more litigious) over the years, its relationship with Intel has grown warmer and more collaborative. Intel for years had zero chips in the iPhone, but won a contract to supply part of the modems in the iPhone 7 series and is expected to supply the majority of the modems in the new iPhone 7s, 7s Plus, and iPhone 8 phones coming this fall, a source with knowledge tells me.

LTE Flavors

Moorhead Insights & Strategy analyst Patrick Moorhead points out that the battery life may depend on what type of LTE the Watch runs. The type that requires the most power is traditional LTE, like that used in Samsung’s Gear S3 LTE smartwatch. This might require a bigger battery in the Watch, but Moorhead sees a bright side: “With it would come likely a larger battery and therefore larger Watch,” says Moorhead. “A larger Watch would be welcomed by many as it would have a larger display.”

Or Apple could use LTE-M (Long Term Evolution for Machines), a low-bandwidth standard which transmits data between 100-200 bits per second. “AT&T and Verizon support this and battery life would not be impacted at all,” says Moorhead. (But that slow speed would noticeably limit the performance of some services on the Watch.) A third option is using LTE-CAT 1, which Moorhead says falls somewhere between LTE and LTE-M in performance and battery life (Verizon supports this variant).

If and when an LTE-connected Apple Watch appears, it will likely change the way we use both the Watch and the iPhone. Right now, the smartphone is our only real can’t-leave-home-without device. The LTE radio might push the Watch toward that status. We may slowly get used to doing a wider set of tasks on the wrist, and gradually reduce our dependence on our phones. Does that mean we’ll be less fixated on our tech gadgets in general? Or just that we’ll have shifted some of that fixation to another device? That’s TBD.


Asked Monday if Apple will indeed introduce an LTE Apple Watch this year a company spokeswoman told me: “Apple doesn’t comment on rumors.”

About the author

Fast Company Senior Writer Mark Sullivan covers emerging technology, politics, artificial intelligence, large tech companies, and misinformation. An award-winning San Francisco-based journalist, Sullivan's work has appeared in Wired, Al Jazeera, CNN, ABC News, CNET, and many others.