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T-Mobile’s plans for 4G in Wi-Fi bands: Has John Legere gone too far?

By Claus Hetting   /     Dec 20, 2014  /     Uncategorized  /  

The mobile industry is long overdue for a shakeup and new ways of keeping consumers happy.

Flamboyant T-Mobile CEO John ‘Un-carrier’ Legere is precisely the kind of leader the mobile industry needs. I’m a fan. But here’s where T-Mobile may be going too far:

Fierce Wireless now reports that T-Mobile plans to use the 5 GHz unlicensed bands mostly used for Wi-Fi for 4G/LTE (the ‘unlicensed’ version of 4G/LTE is called LTE-U by most). You don’t need to be a technical guru to understand what can (and probably will) go wrong here.

For LTE/4G and Wi-Fi to coexist peacefully and NOT battle for the same airwaves, the 3GPP (LTE/4G) and IEEE (Wi-Fi) standards people would need to sit down and figure out how to do this together. Both technologies are evolving. So without this kind of cooperation, the battle is on. And sorry for the acronym soup :)

Frankly, it’s hard to find a single reason why the Wi-Fi industry would want to align standards to suit the preferences of mobile carriers. The disaster scenario is that both unlicensed 4G/LTE (mobile) AND Wi-Fi will end up working badly.

Here’s what set off alarm bells in my head: Wi-Fi uses something called ‘exponential backoff’. This means that when airwaves are too busy, Wi-Fi will stand down for a longer and longer time after each unsuccessful attempt to transmit. In other words: Wi-Fi is very polite and tries not to disturb whatever is out there. Right now, LTE-U doesn’t do that (as far as we know).

One of the founding principles of Wi-Fi is to ensure that anyone can use it, hence the polite backoff scheme. LTE is based on exactly the opposite principle: Taking total ownership of whatever band it occupies. That’s not to say that LTE-U couldn’t adopt ‘politeness rules’. It’s just hard to believe that that’s what the mobile industry really wants to do.

So here’s my pitch to T-Mobile: Why would you want to risk making your customers unhappy Wi-Fi users? With 80+% of traffic on 4G/LTE mobile devices running over Wi-Fi, it seems to me that that’s a huge risk to take.

And why would you want to adopt a technology without an ecosystem that is so much more expensive when carrier Wi-Fi technology is available NOW at a fraction of the cost? Add to this that Wi-Fi is supported by 2 billion devices and supports speeds that are much higher than LTE.

T-Mobile’s CellSpot and Wi-Fi calling are very much ‘un-carrier’. But LTE-U is the least ‘un-carrier’ of all technologies. C’mon, John. Join us on the Wi-Fi side. And if you’re still in doubt – you can read all about why we’re in the Wi-Fi Age right here.

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