Floor, Wall and Ceiling Penetration

Discussion in 'Cisco/Linksys Wireless Routers' started by Helpdesk, May 4, 2005.

  1. Helpdesk

    Helpdesk Network Guru Member

    Ok boys here's a challenge. I want to take my WRT54G router and penetrate the furthest through walls, ceilings and floors in my apartment building. To do so I know I should up my power and buy new antennas. Which are the best? I am looking to get a 1mbps signal to as many people as I can from the fourth floor of a 10 storey apartment building.
  2. Guyfromhe

    Guyfromhe Network Guru Member

    i don't think your going to get any decent coverage with a single wrt for that large of an area unless you switch to all directional antennas and even then your going to have a hard time without LOS, best shot would be new antennas and crank up the power, but it's not going to buy you a whole lot...
  3. littlewhoo

    littlewhoo Network Guru Member

    This won't work. You cannot cover a single 10 storey building with just one AP. No matter how good your antennas are or how much raise the output power. Well, except the whole building is made of wood or cardboard. :)

    I have set up quite a few wireless WDS networks in multi-storey buildings and usually you'll need an AP on every second or third floor. Of course this depends on the material the building is made of. Especially reinforced concrete, which is used excessively in many new buildings is *really bad* for wlan signals.

    Get a bunch of WRT54G or WRT54GS routers, replace the standard antennas with 7dB omni-antennas and configure them to work as a WDS chain.

    Increasing the transmission power of the routers will also help a little bit. Be sure not to raise the power too much above 100 mW, as this will increase the noise and distortion in the signal and result in reduced range, bandwidth and signal quality.

    Just keep in mind, that in WDS mode with every additional hop the bandwith for this and the following nodes is cut in half. But if you just want to share a normal 1-3 MBit/s internet connection, that's not such a big problem.
  4. Helpdesk

    Helpdesk Network Guru Member

    Sorry if it sounds like I expected to cover the entire building with one access point. I wanted to start from location and then build from there going to every other floor or every third floor if I could.

    Here is the actual apartment building that I would be using it at.

    Are you also saying that it might be possible to relay the wan signal between them and not have to run cat 5 to each one?
  5. Guyfromhe

    Guyfromhe Network Guru Member

    it may be possible with many APs another thing you could do is use powerline networking to "hardwire" the APs between floors if the signal won't reach.
  6. littlewhoo

    littlewhoo Network Guru Member

    Sure, that's what WDS is for. The topology of a WDS network usually looks like this:


    The single nodes/APs of a WDS network are linked via wireless connections and to each node clients can be connected either through wired or wireless connections.
    As each AP has to serve several wireless connections at the same time (at least two connections - one to the previous AP and one to the next AP), bandwidth in a WDS network will decrease, with the number of nodes you add to the network.
    Usually it's not recommended to build WDS chains of more than 3 or 4 APs. If you need more then 4 APs to cover the whole building, perhaps the best thing would be to use two WDS chains on different channels. Both starting in the middle of the building, with one chain going downwards and the other chain goind upwards.

    Btw, don't you think that a 1 MBit/s internet connection is a little bit slow for a 10 storey building?
  7. Toxic

    Toxic Administrator Staff Member

  8. Helpdesk

    Helpdesk Network Guru Member

    Nope I don't. Not for internet and email services. I just plan to resell a internet for $10-20/Month. With the added functionality of this firmware, there should be no problem load balancing between each person connected.

    I am also saying that 1Mbit/s isn't the maximum that I want. It is just the minimum. If only 2 people are using the connection, then they should all share it equally.

    Thanks for pointing out WDS. It makes sense, I didn't realize that was incorporated into 802.11 devices. I thought that it would be more of a hack.

    Thanks for the info. "Knowing is half the battle!!!!" ;)
  9. Toxic

    Toxic Administrator Staff Member

    dont forget though each WDS unit cuts the bandwidth by half.
  10. Guyfromhe

    Guyfromhe Network Guru Member

    thats why I recomended using powerline between floors, it's not that expensive and will be more reliable.
  11. gotamd

    gotamd Network Guru Member

    Yeah, WDS will definitely cut down your bandwidth substantially with a large number of units. This table gives an interesting comparison though I don't know what the environment for those tests was like.

    EDIT: Judging from that table, you'd be best served by not allowing 802.11B connections. However, this might cut down on the number of people who could use it without upgrading their wireless cards (assuming they already have B cards).
  12. Helpdesk

    Helpdesk Network Guru Member

    The benefit of this roll-out is that it is going to be slow, and relatively cheap. It will have to pay for itself as routers are added.

    Perhaps for the furthest router, I can use HomePlug.

    btw Has anybody heard more about HomePlug AV? I have heard that there will be products out in 3-6 months. I was wondering if the number of devices on the same network was lifted from 16 to something much greater.
  13. Helpdesk

    Helpdesk Network Guru Member

    So which 7dB omni-antennas should I be looking at?
  14. Guyfromhe

    Guyfromhe Network Guru Member

    my friend is doing a homeplug rollout at a hotel i believe you can have several "channels" so you can have mroe than 16 devices i'll find out for sure for you though
  15. Helpdesk

    Helpdesk Network Guru Member

    That would be ideal. The more information you can give me, the more I like you ;)
    If you can find out which hardware he is using, I would be able to find out even more!
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