21 posts by 9 authors in: Forums > CWNA - Enterprise Wi-Fi Admin
Last Post: July 25, 2009:
  • Hello guys,

    So, if I wanted to implement VoWLAN, what would be the way to go? Single channel model or a multichannel model.

    What do you guys suggest?


  • This is too vague to answer.

    How big is the reuqired coverage area? What other services must the WLAN support concurrently to voice?

  • The area I was considering is 400ft by 400ft, a convention center. The network should be able to handle VoWLAN and data/internet access.

    I know this question is vague, but both models have pros and cons. I would love to hear yout thoughts.


  • I think Xirrus owns that area. So I would say Multichannel Architecture, offloading as much of the Data Clients to the 5 Ghz spectrum and allowing the WiFi Phones to use the 2.4 Ghz.

    You can use 8 radio Arrays with directional antennas. One Array alone can give you 7 or 8 (depending on how you configure it) 24 Mbps "slices" yielding 192 Mbps of throughput from that one cable drop. Of course if you use the 11N product it scales up.

    I have never seen a Single Channel Architecture that could provide the throughput necessary to support voice and data with a density of users.

  • Great input. Thank you.

    Just to add to your response, if the throughput is over 100Mbps, then you would need gigabit Ethernet 1000Base-T.

    Again, thanks.

  • As far as I know all Xirrus products come with 1000Mb ethernet some with dual 1000Mb ethernet. The rest of your network might need a slight upgrade though.

    Yes Xirrus has very good products for density and range.

  • SCA is better than MCA since you plan to implement VoWLAN. Keep in mind that only in a SCA all APs appear as one virtual AP - taking away from VoWiFi clients any need to roam(and reauthenticate) from one AP to another AP.
    This considerable saving on contention overhead and latency is what VoWLAN applications need.
    By the way, SCA is what Meru and Extricom have implemented by default in their controllers.
    That being said, remember your site survey.

  • How many data users? How many voice users? Are the VoIP phones that you are using under your control? Have you purchased them yet?

    The right answer as to which product is right for you takes quite a lot more information. If you can answer these questions (and then some) we'll see what we can come up with. Thanks!


  • GT,

    Thank you for your response. The number of users is not defined, yet. This would be for a large area, a convention center- 400ft by 400ft

    I just wanted to hear your thoughts regarding SCA vs. MCA. It made sense to me using a SCA model since one could design a more dense coverage and roaming issues are mitigated. However, several individuals recommended using MCA, before posting this question here.

    I've read about Xirrus, but I could not identify which model they use.

    For now I solid recommendation on which model would be the best-practice model to use, will do.

    Again, thank you.

  • Not knowing how many users is like you telling me you want me to build you a house, but you can't tell me how many people are going to live there. :)

    I've been in situations where the customer didn't know how many users there would be. Let's start here: What is the fire code capacity of the room?

    Are you purchasing and issuing the VoIP phones? What I'm getting at is versus people bringing in their own phones and attaching to your network. This is a very important distinction!

    Budget is going to be another concern. Let me throw this out at you. You don't have to choose between MCA or SCA. Depending on your answers on the VoIP phone thing, you could deploy both.

    MCA will win the data throughput war and SCA is much better with mobile clients because mobile client are very unpredictable at roaming, which is solved with an SCA architecture.

    If you don't mind sharing, where are you located?


Page 1 of 3