• By DavidCA - edited: March 21, 2017


    I originally posted this to my blog  but  do not expect a lot of attention there so am cross-posting this in the CWNP forum as well.

    LTE has an unlicensed version called LTE-U that uses the 5 GHz U-NII-1 and U-NII-3 bands used Wi-Fi.  The FCC has authorized the first of the LTE-U devices     What are the implications of this standard?  Will Wi-Fi start having problems on the patio of your favorite coffee shop forcing you to go inside to get a reliable signal?   There is a coexistence standard  but of course, there is the standard and the actual performance as implemented by device drivers.

    By the way it appears that Wi-Fi vendors such as Aruba, Broadcom, Cisco, Ruckus have been involved but I do not know how much of a conclusion to draw from that.    There has been testing against 802.11n I have not yet found a reference for testing against 802.11ac that has useful information.  I hope someone can give a better more recent reference that is more reassuring. 

    An Aruba networks document also gives me pause, “Because it is a duty-cycle based solution, an LTE-U base station effectively takes control over its channel by force under control of a licensed operator, leaving it up to Wi-Fi to sense when the duty cycle is off.”

    The IEEE may have some interesting material on the topic, but I will have to see what it is possible to get without a lot in the way of fees.  Does anybody have interesting technical references on the topic?

  • It's not my imagination.   My replies to this post are disappearing.

    Let's see if this reply does the same.

  • I see this reply at least Howard. Sorry if there was a problem.


  • Hi Howard, at the moment all I see is a reply saying another reply disappeared.  What was your original reply?

  • David,

    My original reply was fairly long, but this will have to do for now.

    I too am very concerned about LTE-U.     Part of this is based on my experience with carriers, and partly from reading the documentation, both pro and con on the subject.

    First, I have seen what telco's can do to monopolize a market, and despite their reports, I am skeptical of their performance predictions. It is well known that they have been losing $ to Wi-Fi, and I think they will do just about anything to get those dollars back.

    On the pro side for LTE-U, I think it has great potential, but only if it does not interfere with Wi-Fi. ,    

    Just about any manufacturer can generate test cases that show off their own technology, but ignore reality.    Several of the test scenarios presented by LTE-U advocates seem very narrow and artificial.  I very well understand the concept of controlled experiments, but the number of test cases is impossibly low.

    Even if the initial installations work well, I can imagine a day where LTE-U (as currently planned) obliterates the Wi-Fi - at least in some environments.

    The biggest concern by the WLAN industry is the lack of a decent "listen-before-talk" mechanism.    I agree with this completely.   LTE-U needs to have something better, including stricter energy detect levels - which they will be loathe to accept.

    One might even advocate restricting their channel choices - say every other channel ! (hah) 

    CWNP has a webinar coming up on  the 20th of this month, that among other things, will be talking about LTE-U's impact on Wi-Fi performance.   It should be interesting..

    I am looking forward to it.

  • Hi Howard,

    Thanks for posting the new reply.  That is mysterious about the first one disappearing.  The timing if the webinar is good,  



  • I missed the first part of todays (4/20/17 ) Webcast by iBwave, and I did not hear any mention on LTE-U,

    But the Webinar was GREAT.    I really liked the 3-D prediction (including CCI) capabilities.

    If anyone heard anything on LTE-U, on the webinar, would you please relate it here.

    Thanks very much,


  • By Tom Carpenter - edited: April 20, 2017

    The only mention was that it is coming and will be a factor to consider in the future (possibly not to distant).


  • At first blush, it would seem like the new European RED (Radio Equipment Directive) standards, if applied to LTE-U would fix many of the potential problems with LTE-U.

    These new requirements, which go into effect June 2017, specifies transmitter AND receiver (listen before talk - Energy Detect) requirements.   The Regulatory Domains have never specified some of these parameters before.

    Granted the RED does not directly affect US radios, but for once it seems like the Europeans might have done something right.

    US manufacturers selling into Europe are already working on this, and have been for some time.

  • That is encouraging.  I started to go down the rabbit hole but do not see anything too specific yet.  Could you send some links or other references for the transmit and receive energy detect requirements?  

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