LTE in the 5 GHz Wi-Fi band: The threat is taking shape

Founder and Managing Partner of LANCOM Systems, Ralf Koenzen has been blogging for two years about political topics and developments concerning the Wi-Fi and network industry. His German blog “Auf ein Wort – Ralf Koenzen bloggt” has grown steadily and enjoys a high reputation among experts, colleagues and journalists. In his latest blog he focuses on the more and more imminent threat to the unlicensed spectrum through LTE-LAA and LTE-U. The following text has been adapted from the German original.

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Ralf Koenzen – Founder and Managing Partner of LANCOM Systems

When I first mentioned the looming conflict about the all-important 5 GHz frequencies on this blog last April, the “threat” was still relatively abstract. At the Mobile World Congress 2015 in Barcelona, Ericsson and Qualcomm presented their plans to exploit the unlicensed spectrum for LTE. Although the media in the United States soon started to report critically on this, here in Europe this all seemed very remote.

Specifically, the plans intend to supplement the licensed bands currently used by LTE with additional frequencies in the unlicensed 5 GHz band, in order to transport data. The reason why? Frequencies used by mobile operators are overcrowded. An ever increasing number of smartphones are streaming more and more media and transferring more and more photos, causing data volumes to increase rapidly.

LTE-U and LTE-LAA: The difference is in the suffix

The technical terms describing the exploitation of free spectrum are LTE-U (unlicensed) and LTE-LAA (license assisted access).

Here in Europe, LTE-U is of little interest: It does not meet European regulatory requirements (e.g. the highly important “listen before talking” principle, LbT), so it is unsuitable for operation here. Things are different with LTE-LAA. On paper at least, the technology appears to comply with European regulations. Allegedly, 5 GHz Wi-Fi networks will not suffer from interference because LTE-LAA only transmits if the frequencies are unused. Appropriately, mobile providers constantly emphasize that “fair sharing”, i.e. a peaceful coexistence of Wi-Fi and LTE-LAA, is at the top of their agenda.

Fair sharing? Single-handedly, an impossibility

LTE threatening the 5GHz Wi-Fi band

But it is much too early to sound the all-clear. The 5 GHz band offers only a limited amount of bandwidth, and the capacities of Wi-Fi networks operating on the other frequencies are often exhausted, particularly in urban areas. Every additional user represents a tangible threat to the viability of existing and future Wi-Fi networks in private households and for companies in particular.

Making matters worse, we have to assume that mobile operators will outsource as much traffic as they possibly can to the 5 GHz band. The result at peak times would be a non-stop broadcast that completely swamps these frequencies as soon as enough smartphones of this type appear on the market. For companies in particular, it will be practically impossible to operate 5 GHz Wi-Fi reliably and without interference.

The risk will be all the greater if the shared use of the 5 GHz band is pushed through without gathering practical experience and conducting technical analyses first. But that is exactly what is happening right now! In early February it was announced that LTE-LAA had been tested for the first time in Germany. At no time during the development of LTE-LAA was the Wi-Fi industry actively involved, and these tests were no exception. This is all the more surprising as Wi-Fi users stand to lose the most. By the way, tests in the Netherlands in November 2015 were carried out in a similar manner.

No rollouts without transparent testing

Are we really expected to believe that there was no interference at all to Wi-Fi networks in the 5GHz band, as reported after the test? Assuming that was indeed the case: Why weren’t test setups and protocols made public or at least provided to the Wi-Fi industry? How come neither we, nor any other Wi-Fi manufacturer, were invited to take part in the tests?

There are so many questions that need to be answered. And time is short! Because according to the mobile industry, their joint standardization body, the 3GPP (3rd Generation Partnership Project), is expected to adopt the LTE-LAA standard as a part of the 3GPP Release 13, due this year. Qualcomm plans to ship their first products in 2017.

Spectral Scan 5 GHz

Example of a Spectral Scan of the 5 GHz band – not very crowded these days

Under no circumstances should there be a commercial rollout of LTE-LAA without first carrying out transparent tests with the active involvement of the Wi-Fi industry! It is vital for existing 5 GHz wireless technologies to operate without interference. The main reason for this is that devices operating in the ISM (Industrial, Scientific, Medical) bands, i.e. parts of the 2.4 GHz Wi-Fi band and significant portions of the 5 GHz band, are permitted to operate without separate application and allocation procedures. In other words, the manufacturer’s Declaration of Conformity is sufficient; no further checks for possible side effects are required.

We can only hope that Germany’s Federal Network Agency sees this the same way and keeps an eye on further developments. Or, better still, if the subject were to be monitored at the European level by the Telecommunications Conformity Assessment and Market Surveillance Committee (TCAM), the regulatory body within the EU.

There is much at stake!

PS: In the United States, the FCC approval authority actively intervened after the 3GPP initially chose to go it alone with their LTE-U standardization process. The FCC has since made comprehensive consultations due to their concerns. We would be very pleased if European authorities were to see this the same way.

 

For further information on LTE-LAA and LTE-U see the following links:

http://www.rethinkresearch.biz/articles/qualcomm-lines-laa-lte-u-trials-sides-pond/

http://www.cablelabs.com/can-lte-u-forum-specification-provide-fair-coexistence/

http://www.mobileworldlive.com/mwc15posts/wi-fi-alliance-outlines-opportunities-risks-lte-u/

http://www.microwavejournal.com/articles/25397-expanding-mobile-capacity-the-evolution-to-lte-u-and-laa

https://www.fcc.gov/news-events/blog/2016/01/29/next-step-lte-u-conducting-limited-lte-u-performance-tests

http://apps.fcc.gov/ecfs/document/view;NEWECFSSESSION=0pJgVKnJBmkrNZM70KTjLVpG2B7mXv3rr1Lm7164ynQ1wpPtTGDb!-90173428!-668154738?id=60001078141 (Link to PDF)

 

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