It’s shaping up to be the heavyweight fight of the decade. In the blue corner, Qualcomm and LTE-U; in the red corner, everyone else. Or at least, that’s how it looks at face value. Qualcomm’s latest under-the-radar announcement of yet another technology, MuLTEfire, that permits LTE-like operation in unlicensed or license-exempt spectrum will only add to the frenzy.
Having been a moderator (referee?) at a preliminary warm-up bout at the WiFi Global Congress last month, I can assure you that emotions are running high. On my panel we had Qualcomm lined up against CableLabs, Cisco and Sky’s The Cloud, and it was a pretty brutal encounter.
Quick bit of background here. There’s increasing talk about how services can coexist and operate between licensed and license-exempt spectrum, and how owners of licensed cellular spectrum can also use the unlicensed spectrum more commonly reserved for WiFi use. The idea is to tether cellular services to WiFi spectrum and use carrier aggregation to give cellular operators access to more spectrum at traffic-heavy locations, easing network congestion issues and ensuring a high quality of service for their customers. The WiFi service providers, on the other hand, are somewhat dubious about the whole concept.
The technology being mooted to enable this is licence assisted access (LAA) or LTE-U (LTE unlicensed) – different names, slightly different approaches to the same problem. LTE-U is proving rather controversial, and is being pushed – heavily – by wireless technology firm Qualcomm. Last month, the US FCC issued a public notice, seeking comment on the use of LTE-U and LAA technologies in its 3.5GHz band, and others, and how they will coexist with other technologies, including WiFi.
There are plenty of unanswered questions about whether cellular will overwhelm other unlicensed use of spectrum – if the cellular operators are talking 40 and 80MHz channels for LAA, then with 2-4 operators they be claiming 50% or more of the Wi-Fi spectrum. There’s also the question about anti-competitive practices, which is perhaps even more contentious than the technical issue.
The WiFi operators dislike LTE-U, mainly because they feel they are being left out of the discussion. LTE-U is based on a 3GPP Release specification and is being debated in cellular for a, not WiFi ones. From my discussions with WiFi providers, they are not totally against the idea of sharing in principal, but expect to be involved in technical discussions and want access to far more data than they are currently getting.
Qualcomm likes to cite the 1000x increase in mobile data traffic that we are apparently about to face, and how this is a problem that needs to be solved. One way to do this, if you believe the premise that is, is for cellular operators to use unlicensed spectrum. Cue LTE-U and now MuLTEfire.
Qualcomm unveils MuLTEfire
Last week, Qualcomm Research announced a new technology called MuLTEfire (excuse the crazy use of capitals, but they are obviously stressing the LTE characteristics. Qualcom describes MuLTEfire as offering “LTE-like performance with Wi-Fi-like simplicity”. Interestingly, the announcement was very low key, on a company blog rather than a press release.
Where MuLTEfire differs from LTE-U is that it doesn’t require an anchor in licensed spectrum. This means, in theory, that the new LTE derivative technologies can also be used by service providers who may not own licensed spectrum – in other words WiFi operators. Whether or not this is enough to silence the critics of LAA/LTE-U remains to be seen, but perhaps we should have gone down this route in the first place?
“MuLTEfire will use the signals and channelization of the robust LTE radio link, while also leveraging evolving LTE technologies for self-organizing small cells suited for hyper-dense deployments,” explained Matt Branda, staff manager, technical marketing at Qualcomm, on the company’s blog. “MuLTEfire will deliver these LTE-like performance benefits to more deployment scenarios with Wi-Fi-like simplicity – a leaner, self-contained network architecture that is suitable for neutral deployments where any deployment can service any device.”
Qualcomm says it has extensively tested coexistence to ensure LTE-U will play nicely with Wi-Fi, and even claims that: “in many cases, WiFi performance will actually be improved by LTE-U.”
It adds that MuLTEfire will create expanded opportunities for small cell deployments, especially in hyper-dense environments, and can provide nomadic wireless access services to any end user: “no subscription or SIM required”, says Qualcomm. That opens up a number of interesting service possibilities, not least the ability of easier roaming for WiFi.
Google warns of coexistence danger
Meanwhile, Google is warning of the dangers of LTE-U and says that cellular “presents new challenges for coexistence with other unlicensed technologies”. A new white paper by Google engineers, since filed with the FCC, summarises its initial investigation into coexistence.
“The paper shows that in many circumstances, LTE over unlicensed coexists poorly with Wi-Fi,” wrote Nihar Jindal, hardware engineer for access and energy at Google on the company blog. “LTE over unlicensed has the potential to crowd out unlicensed services.”
Google argues that holders of licensed spectrum shouldn’t be able to convert the unlicensed 5GHz band into a de-facto licensed spectrum band, and certainly shouldn’t have the ability to push out other unlicensed users.
Instead, Google wants cellular operators in the US to use the newly available spectrum in the 3.5GHz band for additional capacity – a solution for the US, but not so useful for the rest of the world. “The entire wireless ecosystem should be concerned about allowing one innovation to block others,” said Jindal.
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