Qualcomm’s XPAN tech is pretty interesting

Summit 2023: Well hidden in their new sound chips

Qualcomm Snapdragon logoAt their Hawaii Summit in October, Qualcomm announced a new line of wireless audio chips. The company did there best to hide the interesting parts but SemiAccurate found out a few neat details anyway.

The chips in question are called Qualcomm S7 Gen 1 with a Pro version for those with delusions of grandeur. There is also an S5 Gen 2 without the Pro tag with the main difference between the lines being basically everything. Take a look at the chart below for the feature set, it is the closest to real data we have.

Qualcomm S5 S7 product table

Note the similarities and differences

The S7 line is clearly a new architecture with the S5 being an iteration on the older one and the S7 non-Pro having a few features fused off. And AI, can’t forget AI on your earbuds, society would collapse without AI in earbuds you know. Can you tell I am a bit jaded by the AI BS pervading everything now, not just Qualcomm but everyone? How did we ever make toast without AI? OK enough, back to the story.

Of those features most are irrelevant, essentially expected features on any higher end sound silicon. There is one interesting bit, the XPAN ‘tech’ that is in the S7 Pro. After sitting through literally hours of briefs on these three chips, when I couldn’t tell the difference between them, I asked. Still confused I asked a technical person who expounded on the XPAN bit and praised their ‘micro-power Wi-Fi’. This got me interested because the person who told me about it knows his stuff and if he was actually excited… That said going over the slides I found the deep tech I craved as you can see below.

Qualcomm XPAN diagram

Explains everything right?

Just kidding, there was nothing useful until I found an engineer doing the demos of the devices at which point I got the details and there is actually interesting tech under the hood. As we started out with, it is really well hidden though. The idea is that your phone and earbuds communicate through Bluetooth which has a limited range. If you live in a large old house like I do, you will lose signal long before you go from the office to the bathroom for example and the basement is right out.

XPAN basically augments BT with Wi-Fi so when you walk out of range you (hopefully) seamlessly swap over to Wi-Fi before the signal drops or degrades to the point where you notice. Sure you pay a much higher power penalty to get that signal but you don’t lose your music. And AI. Damn, OK, I’ll stop now, sorry. When you walk back into BT range, it swaps back over. This is kind of an obvious thing when you think about it but how you do it is the tricky bit.

The idea is simple enough and if you understand how 4G and Wi-Fi can cooperate, you get the XPAN tech. Assuming you aren’t in the weeds on radio minutia, the short version is that the earbuds maintain a signal over the Wi-Fi channel for control and signaling but the bulk of the data moves across the low power BT link. Every so often the buds will check the Wi-Fi channel for quality and basically keep the connection alive. In essence the longest range or most reliable channel is the anchor and the data goes over what is the ‘best’ route from there.

The so called Micro-Power Wi-Fi is used here but there were absolutely no details available on why it is lower power or how low is low. You could also ask about the range with vastly reduced power but that is another topic entirely, we will just assume it is much lower than normal Wi-Fi on both counts. And it is proprietary but more on that later. Just realize that the anchor link is a proprietary Qualcomm tech with a potential tie in to Wi-Fi which is an open standard.

So these buds operate as normal BT earbuds but require Qualcomm silicon on both ends to do basically any of the features listed above. If one bit isn’t the correct version of Qualcomm silicon, these parts do have backward comparability to open standards but you lose the wizz-bang features. Every so often they ping the Wi-Fi router to keep the channel up and all is good there.

Oh yeah, you also need a Qualcomm chip in your router that is aware of this scheme because, well, that is how proprietary works. The take home message is that if you have current QC silicon in all your devices, you can use this scheme. As with previous proprietary Qualcomm sound techs, I have literally never had all the pieces to try it out and adding a router to the mix doesn’t give me hope for this generation. That said in theory it is a good idea.

All of this hinges on a few things. First is how much power the Micro-Power stuff uses. While you are in BT range and given the spacing of the pings, the answer is probably almost zero energy used. Then the range comes into question, when you are out of BT range, and maybe there are a few walls in the way, what is the power use then? And what is the range of these low power modes? In the most direct sense it is basically irrelevant because you would drop the signal without it so as long as you probably consider working more important than battery life, so all good there. That said this is a technical article and we are not more or less directly paid for YouTubers so we care. And we don’t know the answers there, sorry.

In the end the result is pretty simple, a Wi-Fi anchor that facilitates a low latency swap over from BT sound to Wi-Fi when the signal degrades. Both channels are live at once but the proprietary versions of the technologies allow the idle channel to consume almost no energy. It looks to be a good idea, we just wish Qualcomm didn’t hide it so effectively.S|A

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Charlie Demerjian

Roving engine of chaos and snide remarks at SemiAccurate
Charlie Demerjian is the founder of Stone Arch Networking Services and SemiAccurate.com. SemiAccurate.com is a technology news site; addressing hardware design, software selection, customization, securing and maintenance, with over one million views per month. He is a technologist and analyst specializing in semiconductors, system and network architecture. As head writer of SemiAccurate.com, he regularly advises writers, analysts, and industry executives on technical matters and long lead industry trends. Charlie is also available through Guidepoint and Mosaic. FullyAccurate