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  • By (Deleted User)

    I lost the first attempt at posting this so here goes nothing.

    I was trying to keep it just a simple question regarding RTS/CTS, but since you twisted my arm, sure I'll share. :)

    We are having a myriad of problems, but most prominent is with our VoWiFi clients. We're having trouble with some of them dropping offline at seemingly random times. It never seems to be while a call is going on, so current open connections seem to persist through the issue, but as we all know user level information for troubleshooting can often be a hard thing to come by.

    We are specifically focused on the design at this point. After doing a full site survey of our "test floor," we found that though the design was for 60 foot cells, we are seeing cells of 100-110 feet. I am not in front of the data at this time, but I believe we found that we are transmitting at 8.5 mW from the APs.

    From the documenation provided by the manufacturer we are directed that the clients see an idle channel at -76dB. For almost the whole floor the client will see 3 or more APs at a signal strength of at least -76dB on the same channel. Quite often they will see 3 within the normal operating range of -67 or greater, so we know that we have a co-channel interference problem.

    The RTS/CTS question came in because our main data network is a b/g network. We were wondering if the RTS/CTS protection mechanism would work on a BSSID (or AP level in this case) to (in layman) clear the medium, or if it worked on an SSID level and could in essence be causing more trouble than the protection mechanism was worth.

    We understand that the wireless network is a shared medium, so any additional talking especially with the overlap that we are seeing could be causing further issues on the network. We are in a live hospital environment, so any changes we make from here to improve things we have to get right the first time.

    After reading the explaination of RTS/CTS posted earlier I understand that it is the least of our worries at this point, but it was something that came up in our brainstorming earlier and I figured what better place to ask than here.

    We're figuring that co-channel interference combined with a possible hidden node type issue could quite litterally be taking up the whole floor with only a few user clients. Our biggest trouble areas are of course the hallways, but I believe that to be partly a design issue as well as most of the signal in the hallways is on the same channel, 6 for our north hallway, with some 11 thrown in, and vice versa for our south hallway.

    When looking at speed to coverage maps from the wireless controller it looks as if we could easily cover the entire floor with just our channel 6 at 18 Mbps+.

    Anyway I hope I got enough information in there. As always I am happy to listen to other ideas. We're looking at a complete redesign. Changing positions, channels, power, the works. Thanks in advance for any help anyone can provide.

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