[NEBULA] multiple APs using same channel in close proximity

HealthByRo
HealthByRo Posts: 28  Freshman Member
First Comment
edited April 2021 in Nebula
Why are multiple APs on the same controller using the same WiFi channels (2.4GHz and/or 5GHz) when they are physically in close proximity to each other?  Isn't DCS suppose to avoid this?   I can understand that this can happen on 2.4GHz but it really shouldn't happen on the 5GHz band since there are a lot more channels than I have APs in this location.

All Replies

  • WebberIT
    WebberIT Posts: 53  Ally Member
    Ideas master First Comment Friend Collector Second Anniversary
    Did you happen to see the channels displaying the same set but in different seqences?
    eg. 48*/36/40/44 vs 36*/40/44/48
  • HealthByRo
    HealthByRo Posts: 28  Freshman Member
    First Comment
    Example:  
    40/36/44/48
    and
    48/44/36/40

    But sometimes they are exactly the same.
  • Zyxel_Dean
    Zyxel_Dean Posts: 237  Zyxel Employee
    25 Answers First Comment Friend Collector Fourth Anniversary
    edited November 2018
    Hi @HealthByRo
    The different sequence @WebberIT is mentioning about is main channel or primary channel.The star character  ' * ' on one of the channels in the set, that means it is using that channel as primary channel and other ones are secondaries for building up the 80Mhz bandwidth.

    DCS measures channel utilization and calculates the primary channel it's going to skip to, so it is likely to see same sets but different ones having * on it. In some occasions it could be the same if no other channel is better. 
    The channels available to skip to is determined by the country code in which it's allowed and whether DFS should avoid.

    Are there performance issues if the channels are the same? In my experience 5Ghz should be more capable of withstanding co-channel interference, it wouldn't be as dragging performance as 2.4Ghz. 
  • HealthByRo
    HealthByRo Posts: 28  Freshman Member
    First Comment
    Our throughput on the 5GHz channel has not surpassed 50Mbps, even with nobody else in the office and only 1 device on the AP.
  • WebberIT
    WebberIT Posts: 53  Ally Member
    Ideas master First Comment Friend Collector Second Anniversary
    That sounds like the channels are flooded with traffic, are you in a wifi dense area?
    Try with different channels and check the linkspeed/datarate on your test kit before you start testing, it reflects the realtime speed of transmission. 

  • Zyxel_Dean
    Zyxel_Dean Posts: 237  Zyxel Employee
    25 Answers First Comment Friend Collector Fourth Anniversary
    edited November 2018
    @HealthByRo
    May I know on what channel and the RSSI of your client device(or how far the distance) was when you've performed the test? And if the SSID you're using is using captive portal?

    There is a slight possibility that it was a performance bug, which is fixed in the latest patch. Suggested that you upgrade to the latest firmeware before trying out different combinations.

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