• What do you think of ACC, Advanced Cellular Coexistence?  I have seen references to this in both Cisco and Aruba documents.  It exists but what are the details of how it works?  Is it marketing fluff or something more?:

  • By Howard - edited: September 7, 2017


    Thanks for starting this topic.    I had never heard of ACC before you mentioned it.

    I don't know any of the internal mechanisms or hardware that either Cisco or Aruba are using, but I can guess about what they are trying to mitigate.

    While trying to find some Cisco or Aruba information on ACC, I only found a few spec. sheets for some of their products that supported it, and a list or two with multiple products that used it.  Like you said, there seemed to be no explanation of the solution.   I did find documentation from both companies that also listed ACC outdoor antennas,and a little blurb from Dell.  

    The WFA has a certification program called Wi-Fi and Cellular Radio Coexistence, which has over 1,600 devices in it.    It is sometimes referred to as CWG-RF Test, and was created in cooperation with the CTIA (previously known as the Cellular Telecommunications Industry Association).  They started work on the program eight or nine years ago.  

    Testing for this certification takes measurements of radiated and conducted power levels, receive sensitivities, signal degradations, and others over a proscribed list of frequencies and channels.

    As you would expect, most of the certified devices are phones, but there are also tablets, cameras, and at least one AC-router from Netgear (2016).    What is perhaps more interesting than the devices, or the programs, was the impetus for starting the program.   

    It turns out that cell phone system frequencies, create an enormous number of harmonics, and these harmonics are known to interfere with Wi-Fi devices.      Especially when Wi-Fi radios and cellular radio systems are co-located within a small area - like they are inside a cell phone.    

    As you know even without the harmonics, having multiple transmitters in this close of proximity can overload or desensitize the other's receiver.   This interference can be complex and very difficult to mitigate.   Adding in GPS receivers makes the problems even worse (for the GPS).  These issues arise in both the 2.4 and 5 GHz bands.      

    The harmonics from GSM, CDMA, UMTS-FDD (3GPP?), and iDen phones can affect the 2.4 GHz band.   The iDen (800 MHz) phone harmonics can affect channels 1 through 11, whereas the others affect channels 11 through 14.

    In the 5 GHz band, GSM 1800 phone harmonics can interfere with channels 36-64, and GSM 1900 systems with Channels 112-140.  In the UK and Korea, they can have difficulties with CDMA-2000 (900 & 1700 MHz) phones on channels 44-100.   In the US, UMTS-FDD bands I-IV can affect all of the 5 GHz channels.    UMTS-TDD harmonics can affect channels 112-165.  Asia has problems with PHS (?) phones on channels 136 and 140.   The harmonics from iDen (800 MHz) phones appear to be so low as to not cause any problems in this band.

    There appears to be several solutions to these problems, most of which involve adding some kind of SAW or FBAR coexistence filter to either the transmitter or the receiver.     Improvements in Power Amplifiers (PA's) are helping too.

    I could imagine that some solutions might only require passive filters, but it appears that several companies are making integrated circuits that address the problem.

    Obviously, cell towers are likely to cause their own share of problems due to their greater power levels.  (Tom:  Maybe we need a similar solution for USB 3.0 Hubs  )

    Some of the company names I came across while looking for ACC included Avago Technologies, Oberon Inc., and Rysavy Research.    I'm sure there are lots more.

    It looks like that DAS systems were the first to worry about the issue - which seems obvious now in retrospect.   

    If you should come up with more details of the actual solutions, I for one would be interested in hearing about them.

    PS: I have a list with the exact frequencies if anyone is interested.

  • Howard, DavidCA:

    I would be interested in the reference for the frequencies you mentioned.  You are correct but it gets worse for outdoor environments, especially when WAP is located within less than 6 feet of the utility transformer of standard high voltage transmission pole.  Actually part of my presentation on Oct. 13.  Harmonics from the step-down transformer are all over the place.

    Indoors, GSM and DECT phones (5 GHz) actually have harmonics that may interfere, especially if parked right next to the WAP.

    Also may interfere with link between tabllet/smartphone.

    --- Seeker

  • By Howard - edited: October 5, 2017


    I am afraid the specific document that I got the frequencies from is an proprietary WFA document that I cannot disclose due to an NDA.   

    But the CTIA  has almost the same reference and it's publicly available at:

    I'm sure the 12 new 5 GHz channels that the FCC is contemplating will complicate the ACC tests and mitigation.

  • By Seeker - edited: October 5, 2017

    DavidCA, Howard:

    NP.  I will post IEEE references that have the various frequencies and the specific bands.

    You may want to consider consolidating ACC and LTE-U vs 5 GHz.

    From IEEE's viewpoint, LTE-U is just another subcategory of ACC.

    Here is a link of yet another ACC technology that will cause havoc (in all probability) with WiFi in the unlicensed 5 GHz band.

    --- Seeker

  • By Howard - edited: October 5, 2017

    That's one way to look at it.

    However, the ACC and 5-GHz post were intentionally separated to make searching easier.

    Personally I think it makes some posts more likely to be read and responded to.    Often times posts can go far afield from the original post topic, and then the replies never get read.

    Even though the IEEE is the root of 802.11, it is often overlooked (and unfortunately ignored).     The FCC can jail you for ignoring their pronouncements.    The IEEE cannot.    And that is what drives a lot of manufacturing "bigwigs". 

  • Howard good point.  Other regulatory bodies in other parts of the world also function like FCC; IEEE is not a regulatory body.

    At least (based on what I see in discussion) you don't have to deal with US DoD who believes they can stomp on unlicensed WiFi throughout the world.

  • It is good the discussion thread was separated.  Too many times at work people hit reply to an email then discuss things completely unrelated to the original topic.

    Any insight on regulatory bodies that can address this would be good.   We discussed the FCC, but they did not seem to be a good bet.  Perhaps others?

  • Had I known about this forum and the interest, I would have made a presentation on this topic at the CWNP conference.

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