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I Am So Close (Probe Response Threshold +)

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  • 1.  I Am So Close (Probe Response Threshold +)

    Posted May 21, 2014 10:24 AM
    Over the weekend I had the opportunity to conduct a passive site survey on an older building. Over the last ten years as a real estate investor, I have taken a liking to older buildings. Back in the day buildings were built to last. Studs are actually two inches by four inches. When the wind blows I cannot hear it from inside the building.
    However, over the past three years as a wireless engineer, older buildings have posed a challenge to me. Because of the layout of older buildings and the materials used, conducting a passive site survey and generating a heat map is always interesting. (For that matter, deployments can be challenging as well.)  Trying to present signal propagation based on signal attenuation due certain building materials is difficult. In comparison to the heat map generated by an active site survey, I know that it will never be a perfect representation. But if the heat map from my passive site is not in the ball park, many customers will be reluctant to have an active site survey conducted or the customer will be disappointed to eventually discover that considerably more access points are required. 
    For this building, the customer wants a wireless enterprise network for static devices (limited wireless coverage) with the potential for a guest network (full wireless coverage). Fortunately, along with some industry standards (i.e. -65 dBm) I can use the guidance regarding enterprise networks, probe response threshold, and switch stacking provided by the community. When I completed the heat maps I realized that the with -65 dBm and concrete set as restrictions, the signal strength of -70 dBm and below bleeds through the building. I can adjust the probe response threshold setting to address users attempting to connect to the SSID from outside the building. However, it is my understanding that once a user device recognizes the network, connects, and authenticates, it will not disconnect when the signal strength is -70 dBm (according to a probe response threshold) and below. If a user gets smart, connects from within the building, and goes outside he can use the network from the parking lot. In addition, within AirWave I have noticed that devices that eventually disconnect maintain connection to the SSID long after leaving a building. Connections like the one I mention skew the average signal strength results. Are there any additional tools or devices that, once a device reaches a configurable lower signal strength, can disconnect a device from the SSID? In addition to some standard practices, deep packet inspection, a probe response threshold, and  the ability to disconnect devices based on signal strength I would like to limit those that can negatively impact a wireless network and the devices connected to it.
     
    @keepitmobile


  • 2.  RE: I Am So Close (Probe Response Threshold +)

    EMPLOYEE
    Posted May 21, 2014 06:38 PM

    Make sure the AP power is between 12 and 18.

    Turn off Local Probe Threshold response.



  • 3.  RE: I Am So Close (Probe Response Threshold +)

    Posted May 21, 2014 09:58 PM
    I like that idea. At least the signal is not bleeding through the building, But how would I get devices to disconnect at, for example, -70? My goal is to deploy a network in which -65 dBm is the worst signal within the building. So in the corners of the area that I am required to cover -65 dBm is the signal strength. Would the power setting cause the signal strength to dissipate to something so poor that a user will not be able to connect?


  • 4.  RE: I Am So Close (Probe Response Threshold +)

    EMPLOYEE
    Posted May 21, 2014 09:59 PM

    survey with the AP at a power of 12.  Deploy with AP at min power of 12 and max of 18.  rinse and repeat.



  • 5.  RE: I Am So Close (Probe Response Threshold +)

    Posted May 21, 2014 10:06 PM
    Thanks. I'll give that a shot.