The battle between WiFi and LTE camps over access to public spectrum via License Assisted Access (LAA), just got a little noisier with the publication of a document circulated at a recent 3GPP working group meeting in Serbia.

For those who suspect the real motivation behind the development of so-called LTE-Unlicensed and Licensed Assisted Access LAA/LTE-U - two very similar approaches attempting to define a way for LTE networks to use ‘public’ spectrum in the 5GHz band - the document’s provocative title is enough to have suspicions confirmed. “Precluding standalone access of LTE on unlicensed carriers”, it says, which seems to point to at least one member of the working group (which includes China Mobile, Telefonica, Orange and AT&T) seeing LTE as a potential licensed carrier land-grab for public spectrum.  

According to Dave Burstein, an editor at DSL Prime, and the man who unearthed the document, it proposes that 3GPP should revise its existing rule on ensuring that LTE-U  could be used by any carrier, not just licensed carriers, and that it should go further and prohibit non-LTE carriers from using it. See Dave’s report here

Dave’s reading of the contents boils down to it referencing mobile operators’ fears of "Possible disintermediation of cellular operators due to standalone operation [of LAA]," which he says would mean that competitors could bypass licensed operators (as WiFi operators do now) and that therefore carriers wanted to take "standalone access to unlicensed spectrum" out of the standard.

But to me the assumptions in the document seem to have jumped ahead, just a little. There may be no burning desire on the part of WiFi operators to use LAA anyway.

Despite all the talk there is still some way to go before the powers that be, including the FCC, are even going to allow LTE-U/LAA loose in the public band. The FCC just last week put out a notice seeking information on LTE-U and LAA with a view to determining the possibility of peaceful co-existence between the technologies.

In particular, there are still unresolved questions over protocol ‘fairness’ in what looks like becoming an increasingly crowded chunk of spectrum.

Will an LTE-U ‘behave itself’ when contending for spectrum with WiFi or will it tend to grab and hold onto bandwidth? After all, the protocols are engineered in very different ways.

But then, once this fairness has been vouched safe (assuming it is) there comes perhaps an even weightier question around competitive equity.

As Caroline Gabriel, Research Director at Rethink Technology points out, the objective here is for licensed carriers to co-opt public bandwidth as one part in a carrier aggregation scheme, so public spectrum capacity (available in the right spot, say indoors at a user’s workplace) can be combined when required with licensed spectrum. The licensed carrier would then be able to direct what spectrum and channels to use to get a particular data exchange done at least cost and at maximum efficiency. In all likelihood, LTE-U when available could do the heavy file transfers and video streams.

This might be viewed as inherently unfair since the WiFi operator has no way of ‘fighting back’,  says Caroline.

“The thing is that if the LTE-U approach works its way through, there won’t be a level playing field since it is just a downlink designed to be used by carriers as one part of an aggregation,” says Caroline. “That means only a carrier could ever make use of it which sounds inherently unfair.”

It may be slightly less unfair, though, if there was some sort of  reciprocal right for a ‘WiFi first’ or any other species of operator without licensed spectrum to have the ability to use  LTE protocols?

“Yes, but remember the power is in the aggregation and controlling performance from the core of the LTE network, and of course the WiFi network operator isn’t in a position to do that.”

“What I do think might fly, however, is to have a third party build and maintain ‘in-building’ LTE using LTE-U and then working with a carrier who would provide the anchor network for it.”

But all these arguments assume that, once LAA and WiFi  protocols are proved able to coexist in a fair and even manner, there will still be an advantage for an operator or user to plug into LTE at 5Gz. Not at all decided yet,

Caroline  thinks the claims of protocol efficiency are also over-worked by the industry which is naturally keen to keep its operators as LTE customers rather than have the risk of them wandering off the beaten track to hook up with IEEE 802-oriented vendors to institute carrier WiFi.

Meanwhile, technologies which allow WiFi hotspots to be managed from operators’ mobile cores address some of the issues of bringing non-3GPP technologies into the mix,” she says.  

So would a WiFi operator actually want to use LTE as a radio access option?  “I can’t see it myself,” says Caroline. “Using LTE in any guise is usually a more expensive option for any operator.”