Wi-Fi industry is worried about mobile invading its airwaves

There’s a new technology buzzing around mobile carrier circles called License Assisted Access that promises to make our 4G networks faster by dipping into unlicensed airwaves. Most people have never heard of it, but the Wi-Fi industry sure has and it’s raising some red flags.

LAA, also known as LTE-Unlicensed, would tap are the same frequencies Wi-Fi relies on for to deliver its wireless connections, and Wi-Fi advocates are scared the new 4G will muscle out wireless LANs when pitted head to head. The rules of the unlicensed band dictate all users follow some basic rules to prevent devices from interfering with one another. What it all boils down to is if you detect someone using one frequency channel then you move to another channel.

LAA would act much like a Wi-Fi network, but instead of transmitting a Wi-Fi signal in the 5 GHz band it uses LTE. Carriers then combine these LAA signals with their regular 4G transmissions, creating much fatter data connections for smartphones and tablets. Carriers, however, face the same rules as other unlicensed band users in the band. They have to transmit at low power so LAA is really only good for indoor scenarios, and they also have to play nice with other users – i.e. they can’t drown out your home router. Consequently the same interference detection and channel selection technology built into Wi-Fi access points are built into LAA.

So what’s the problem then? The wireless LAN industry’s big trade group, the Wi-Fi Alliance, worries that that carriers will have an edge in the unlicensed bands because their networks are centrally managed. Wi-Fi networks, on the other had, tend to be a patchwork of access points and routers all operating independently but miraculously managing to cooperate. Introducing a centrally controlled and scheduled LAA network into that mix could mess up that mojo. Says the Alliance:

There is a risk that LAA, and especially pre-standard systems deployed ahead of coexistence work being done in the industry, will negatively impact billions of Wi-Fi users who rely on 5 GHz today for networking and device connectivity. It is generally agreed in principle that fair sharing is required, but there needs to be further work from all parties to address this risk in practice.

Driving metaphors are overused when talking about networking, but here the analogy of a racetrack applies. All race cars might be following the rules, but a group of cars acting as a team could gain an advantage by drafting off one another or forcing competitors into different lanes. The Wi-Fi Alliance says that if the mobile carriers took that capability to the fullest extreme they could effectively turn the unlicensed airwaves into a kind de facto licensed band to the determent of all Wi-Fi users.

We’re still in the early days of LAA testing so there is still time to sort the issue out. And the Wi-Fi Alliance isn’t calling for any drastic measures such as banning LTE from the unlicensed band (it would be a bit hypocritical for it do so). But the trade group does want the mobile industry to slow down commercialization work on the technology until it can get these co-existence issues worked out.

[company]Ericsson[/company], already has a LAA small cell in its product pipeline and is testing the technology with [company]Verizon[/company], [company]SK Telecom[/company] and [company]T-Mobile[/company]. Meanwhile T-Mobile CTO Neville Ray has already committed to using LAA in his networks once the technology matures.

SK Telecom and Nokia make big cells and small cells play nice

SK Telecom has just incorporated a tongue-twister of a technology into its Nokia-built LTE network in Gwangju, South Korea. It’s called Enchanced Inter-Cell Interference Coordination, or eICIC for short, and its aim to make networks packed with all different sizes and shapes of cells work in harmony.

What [company]SK Telecom[/company] and [company]Nokia[/company] Networks claim to have done is produce the first commercial cellular heterogeneous network, or hetnet, in which a bunch of tiny little cells mounted on utility poles or on building walls transmit under the umbrella of a big tower-mounted macro-cell. Normally in that type of situation you’d get a murky soup of cross-interference, as the big cell’s signals would overwhelm the signals of the smaller cells or vice versa.

With eICIC, though, the network can coordinate how and when those cells transmit in order to prevent much of that interference from occurring. eICIC is a key component of that grab bag of technologies we’ve come to know as LTE-Advanced and it will be critical in building super-dense networks of the future with loads of broadband capacity.

A diagram from Qualcomm showing small cells under the umbrella of a macro-cell

A diagram from Qualcomm showing small cells under the umbrella of a macro-cell

SK has actually been tinkering with the technology for some time – I first spoke to the carrier’s engineers about their lab eICIC lab test back in 2011 – but it’s proven a very difficult LTE-Advanced technology to master. Interference has always been the bane of RF engineers’ existence because the more transmission points you put in the network, the more places you create overlap between those transmissions. And everywhere you get that overlap you get interference, bad signals and crappy data connections.

Instead of trying to avoid that overlap, the hetnet takes the problem head on, depending on technologies like eICIC to get them out of its interference bind. SK says it’s now ready to start spreading its hetnet across South Korea with the help of eICIC. Hopefully that means the rest of the mobile industry is ready to follow in its footsteps. If carriers can eliminate – or at least mitigate – the interference problem of small cells, we could start seeing networks that don’t get overloaded in crowded places and pack tremendous amounts of capacity.

FCC signs off on AT&T’s massive 4G spectrum buy

By taking in a huge WCS spectrum haul from NextWave, Comcast and others, AT&T has nearly all the components in place to create a nationwide 4G band for its own exclusive use. Now AT&T just has to build it.

Dish gets its 4G approval; Sprint gets its 4G auction

Dish finally has permission to become a full-fledged cellular network operator, though it remains to be seen whether it will actually become one. The FCC also set the wheels rolling for an auction next year of new 4G licenses that Sprint has been eyeing.

AT&T shoots for 2015 launch of new LTE network

AT&T aims in three years to have a new LTE network up in the airwaves the FCC just approved for 4G use. In the rather plodding world of telecom, three years is a quick timeline. But AT&T has political and strategic reasons for moving soon.

FCC chair grants AT&T’s wish for a nationwide 4G band

AT&T wants to rejigger a useless hunk of airwaves for LTE use, but to do so it needs special dispensation from the FCC. Today chairman Julius Genachowski signed off its plan and officially set the ball rolling toward opening the WCS band for 4G.