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limiting wireless coverage (adjust transmit power, move access points)

Discussion in 'General Wireless Discussion' started by Potrito, Nov 6, 2019.

  1. Potrito

    Potrito New Around Here

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    Nov 6, 2019
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    Hi all:
    I'm a novice when it comes to networking (but as a chemist, I believe that I could learn enough to implement recommendations). Time spent on the broader internet has led me to the conclusion that most manufacturers and users only want stronger coverage. I want to move in the opposite direction. This forum has had a few posts about people looking to reduce broadcast power, so I think you all may have some good ideas. (This discussion, about "Wireless "Mesh" with adjustable TX Power" is quite close to my goal, for example).

    The situation:
    To keep the family happy, I need to *limit* wireless coverage, controlling when and where wifi signals are present.

    The background:
    We are not heavy wifi users, but we have devices that need wifi. Some are fixed (e.g., doorbell, thermostat), and some mobile (e.g., tablet). We are definitely open to using wired solutions where possible (e.g., for laptops).

    The questions:
    My hope is that this post will generate some interesting thoughts from a variety of perspectives. I've tried to state the following questions as goals, rather than fixed rules, so please interpret as you see fit. Is there a system I could set up that would meet the following?
    a) Ability to adjust broadcast (transmit) power at each broadcast point (So that if one user is on wifi in a room, I can adjust power so that the adjacent room won't necessarily receive a good signal.)
    b) Ability to turn off wifi in certain areas when needed (So that the bedroom doesn't have much of a wifi signal at night, but that the wireless doorbell has some signal 24/7.)
    c) Minimize the confusion to users (So that family members don't have to pay attention to switching SSIDs as they move around the house. But it's okay if family members have to (un)plug devices as needed.)
    d) Have a guest network.

    The mea culpa:
    I sincerely apologize if I missed a post addressing these themes. If you'd be so kind to point me in the right direction, I'd be most grateful.

    Thanks so much!
     
  2. coxhaus

    coxhaus Part of the Furniture

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    It sounds like to me you want a 5GHz wireless network only for family users so you can have control. 2.4 GHz penetrates and covers too large of area to control very well. You can use 2.4 GHZ for IoT devices. I would think you will want separate wireless devices through out the house with several SSIDs so you can schedule them. Maybe one 5GHz SSID for the kids which can be scheduled and another the adults and maybe one for guests. Then you will need one for IoT devices.

    I use Cisco small business routers, switches and wireless APs. The ones I use now are Cisco WAP581 wireless APs. You can turn down the power to 12% which is fairly low. Multiple Cisco APs work as one large wireless AP across the whole house. They have scheduling built-in but I don't use it so I am not an expert on it. You can read about it on Cisco's web site. There are other solutions but this is what I use. I install my Cisco stuff and it runs like an appliance 24/7 in the back ground with no reboots. You need to install firmware about once a year which is pretty simple.

    How big of area do you need to cover with wireless and what are the walls made of?
     
    Last edited: Nov 7, 2019
  3. thiggins

    thiggins Mr. Easy Staff Member

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    Even with 5 GHz, you won't be able to adjust transmit power enough to prevent signals going from room-to-room.

    What's the reason for wanting such granular control of AP signal? If it is to control internet access for parental control reasons, you would be better off pursuing conventional, account-based access control.
     
    Greg72 likes this.
  4. Potrito

    Potrito New Around Here

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    @coxhaus: Thanks for your ideas and the explanation. I'm looking into that Cisco system. Sounds promising.
    The house is 2 story, each story about 1200 square feet, with standard framing/sheetrock on the interior and a mixture of brick and paneling on the exterior.

    @thiggins: This is a good point you raise. How much attenuation might one expect with 5GHz between rooms (with sheetrock walls)? The motivation is a longer story, but one of the immovable forces in the conversation is a live-in in-law with some Luddite tendencies. Thus, this project is a peace-making, compromise effort.

    Thinking more 'creatively', could I introduce barriers that might help? (e.g., some sort of enclosures, possibly aesthetically pleasing, for the APs?)
     
  5. MichaelCG

    MichaelCG Very Senior Member

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    Do NOT try to impose content filtering via Layer1 (WiFi) controls. That should be controlled at Layer2 or higher.

    - Ban their MAC on the WiFi
    - Get a FW that has more detailed content filtering
    - banish said in-law to the guest WiFi

    Trying to restrict access purely on RF models will be nothing more than a cat and mouse game. As someone moves a piece of furniture, the RF model just changed. The moment someone walks into a room, the RF model just changed. Tune your WiFi to provide proper coverage of the property. There is no way you will be able to easily tune WiFi to behave in a supportable and sustainable manner in a room by room type setup. Deal with bad users and devices at the access and firewall layers instead.
     
    Greg72 likes this.
  6. thiggins

    thiggins Mr. Easy Staff Member

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    As @MichaelCG said, trying to control the RF environment precisely enough to prevent use is unlikely to be successful. I don't have precise figures, but even concrete walls will let enough 5 GHz signal through to provide a useable signal.
     
    Greg72 likes this.
  7. PolarBear

    PolarBear Regular Contributor

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    Is the problem that the person concerned believes they are very sensitive to electro-magnetic radiation, and does not wish to be subjected to it ?

    This is an entirely different issue to allowing or prohibiting access to your WiFi.
     
  8. coxhaus

    coxhaus Part of the Furniture

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    In an average house and building you are going to have 700 sqft coverage for 5GHz and 1500 sqft for 2.4GHz. If you turn the power down to 12% then 700 x 12% = 84 sqft. On paper your idea seems to work. I have never tried it so it is up to you.
     
  9. degrub

    degrub Very Senior Member

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    " This is a good point you raise. How much attenuation might one expect with 5GHz between rooms (with sheetrock walls)? The motivation is a longer story, but one of the immovable forces in the conversation is a live-in in-law with some Luddite tendencies. Thus, this project is a peace-making, compromise effort.

    Thinking more 'creatively', could I introduce barriers that might help? (e.g., some sort of enclosures, possibly aesthetically pleasing, for the APs?)"



    Maybe it is easier to provide a separate, shielded cabin for the person ?

    Otherwise, you may have to wire everything that might be in their path and only have APs with limited range in specific half of the house.

    How do they feel about cell phones or FM/AM radio or TV ? Are those out of bounds ?
     
  10. Potrito

    Potrito New Around Here

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    I appreciate everyone's comments. As several of you have pointed out, there is more than just an engineering question here (@PolarBear: yes. @degrub: radio and TV are acceptable only by force of habit!). The goal of the post was to generate some ideas, and you all have helped tremendously in that respect.

    It will take me a few weeks (or more, with holidays) to begin experimenting, but I will report back to this thread. Thanks!