This week, Apple once again transfixed the tech world with a product announcement event, this time centered on the iPhone 7 and Apple Watch Series 2. One of the headline changes to the iPhone 7 relates to audio. Not surprisingly, the iPhone 7 will not have a 3.5 mm audio jack. Instead, Apple will include a standard set of wired EarPods with a digital audio connection via the Lightning connector. In addition, Apple will offer a new product, AirPods, which are essentially wireless earbuds for streaming music and hands-free phone calls. More interestingly, AirPods are an early entry in the emerging category of wearables some have dubbed “hearables”. That is, they have capabilities beyond mere audio streaming, including access to Siri without pulling your phone out of your pocket. Of course, we’re all familiar with the abilities of digital assistants like Siri, but it’s the context that is revelatory – Air Pods make it possible to have a personal assistant in your ear; whispering directions, answering questions, reminding you of appointments, sending texts, and queuing up the next song.
As usual, pre-announcement leaks had prepared us for all of this. The removal of the audio jack was fait accompli and even the AirPod’s Siri features had been speculated upon by many. IHS predicted this exact scenario in our roundup of New Year’s predictions for 2016, including the use of Siri.
What came as a true surprise to even the most fervent Apple watchers was the apparent abandoning of Bluetooth as the wireless protocol for AirPods. Apple never mentioned Bluetooth during the announcement and AirPods seemingly depart from the standard Bluetooth use case. For example, AirPods do away with standard Bluetooth pairing. The connection is established from the iPhone7 with no apparent physical confirming action from the AirPods, except possibly mere proximity. Once connected, the AirPods are immediately connected to all other Apple devices within the same iCloud account, as long as they run the latest operating system – iOS 10, macOS Sierra, or watchOS 3. Apple claims that connection handoffs from device to device are automatic and seamless.
If AirPods don’t use Bluetooth, what’s going on here? Did Apple create a new proprietary protocol specifically for this application? Yes and no. Over the past two days I’ve spent quite a bit of time parsing the announcement, reading the thoughts of tech journalists, and reaching out to my own industry contacts in an effort to extrapolate a clear picture from the known facts. Here is the result.
It seems most likely that Apple is using a standard Bluetooth Low Energy (BLE) radio with a customized software stack. Apple possesses their own BLE core through their acquisition of Passif Semiconductor in 2013. Passif specialized in low power consumption RF chips and had developed a BLE core prior to the acquisition, so Apple has the hardware intellectual property at their disposal. Combined with Apple’s existing semiconductor expertise, this is the most likely path to Apple’s first wireless chip, the W1. Going this route would also eliminate the need for an additional wireless chip in the iPhone 7, since it could use its standard Bluetooth chip to connect to AirPods. The handset would have a dual-stack capability – a standard Bluetooth stack for Bluetooth peripherals and a custom stack for audio peripherals using the W1. So obviously, Bluetooth is not forsaken in the iPhone 7. In fact, it’s still possible to use Bluetooth wireless ear buds and headphones with the iPhone 7 if you don’t want to buy AirPods or other W1-based audio devices such as the three models of Beats headphones that were also announced. (It should also be stated that noted Apple observer, John Gruber, claims that AirPods use standard Bluetooth and can even pair to non-Apple devices, such as Android phones. While Gruber is usually close the mark when it comes to Apple, his assertion is an outlier – it doesn’t fit with Apple’s statements.)
So the W1 radio appears to be a standard BLE core. This enables Apple to use a reliable and trusted radio capable of ultra-low-power operation while maintaining compatibility with legacy Apple products with only a software update, hence the requirement for the latest OS. That brings us to the custom stack operating on the BLE radio.
Normally, audio can’t be streamed over BLE. There is no standardized way of doing it. The Bluetooth SIG is furiously working to enable this application, but it will likely be another 15-20 months before it is complete. The challenges are significant for an interoperable standard: achieving good audio quality and dynamic range with very limited bandwidth; choosing a baseline, mandatory codec, but enabling optional codecs as well; straddling the vastly different requirements of streaming entertainment quality audio and latency-sensitive voice communications; and maintaining good low-power performance while essentially eliminating sleep states during continuous audio streaming. The technical challenges are daunting, but tackling these challenges in a way that survives a standards approval process - meeting the needs of an entire industry – is a Herculean effort. It is much easier – and faster – to create a new protocol focused on the needs of a single company and a single application. This is what Apple did.
The origin of the new audio protocol can probably be traced back to Apple’s work with hearing aids. Apple created a proprietary BLE audio profile for hearing aids as part of it’s Made for iPhone (Mfi) program. The profile enables a class of BLE hearing aids that can connect to iPhones (or other Apple devices) for streaming music, phone calls, navigation, and many other applications. The problems to be solved for hearing aids are essentially identical to the problems posed by AirPods devices. Apple just took that work and integrated it into a new networking protocol similar to BLE, but with improved pairing, multiple connections, seamless handoffs, and other features.
There appears to be no animosity between Apple and Bluetooth. Apple has always been a major supporter of Bluetooth and has heavily contributed to the SIG’s ongoing work in BLE streaming audio. While Apple probably felt that a few Bluetooth features could be improved upon, that doesn’t seem to be the impetus behind this split on audio. Instead, it appears to be simply a matter of schedule. Apple couldn’t wait for the SIG’s solution.