Theoretical max speed for 802.11g "108" bridge

Discussion in 'Wireless Networking' started by Gregg Hill, Sep 10, 2006.

  1. Gregg Hill

    Gregg Hill Guest


    I need to replace a client's wireless bridge to cover a gap that is roughly
    90 feet between buildings (I am a lousy estimator of distance. I thought it
    was 300', but I paced it off the other day and it's only about 90'). I took
    a close look at their antennas from across the street, and the main
    building's Yagi appears to be pointing about six feet over the top of the
    receiving Yagi. I think the person who initially installed it used the wrong
    antennas for this distance. Since a Yagi has a very narrow beam, I would
    expect them to have to be pointing down each other's throats to work well.

    This theory also fits what is seen at the site. The remote antenna points
    directly at the main one, while the main one shoots over the remote's head.
    The data transfer from remote to main is 20Mbps and the transfer from main
    to remote is 3Mbps. The current bridge is done using Netgear WG102 units
    (two years old) with PoE. The client does not have the password to get into
    them to see the settings, and I cannot down the link to reset the units to
    default for access unless I go there on a Sunday. Therefore, I want to
    replace the equipment with something faster.

    Out of curiosity, and before I go with very expensive Proxim (thank you for
    the link, Jack!) or Ceragon equipment, I asked Netgear which unit would be
    best and they recommended the WAG302, partly because you can use 802.11a to
    eliminate a lot of interference. Since they tout this unit as
    108Mbps-capable, I asked about the maximum theoretical bridge speed, which
    they said would be 54Mbps. I wonder if that is correct. I tried D-Link's
    DWL-2100AP set to use 108 and it only bridged at 23Mbps, according to
    QCheck. I tried two Linksys WAP54G units and they bridged at 25Mbps, even in
    the same room.

    I have tested Netgear's 108-rated stuff used in normal fashion with a WGT624
    wireless router and a WG511T laptop card, and I get about 76Mbps speed,
    better than hard-wired cheap NICs with Realtek chipsets.

    Do you know what the theoretical maximum bridge speed would be for 54G and
    108G equipment?

    Gregg Hill
    Gregg Hill, Sep 10, 2006
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  2. Hi

    The speed that network devices are market under is the speed of the
    electronic circuitry on the device, not the Network's transfer speed.

    This page has some functional info.

    Yagi or not at 90’ you get less then what you get at 20’

    Jack (MVP-Networking).
    Jack \(MVP-Networking\)., Sep 11, 2006
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  3. Gregg Hill

    Gregg Hill Guest


    When I tested with Linksys WAP54G units, they got 26Mbps in the same room
    and 23Mbps bridging across the street 125' away using a 6dbi D-Link internal
    antenna on one end and the built-in antennas on the remote end.

    I understand that marketed speed and real speed will be different. The same
    goes for 100Mbps hard-wired speed marketing vs. real world speed. When using
    the Netgear 108-advertised equipment noted in my last post, I got around
    75-80 between my wireless laptop and a desktop with an Intel NIC hard-wired,
    while a hard-wired Realtek card in another system only got only 38. I popped
    a 3Com NIC into that system and got 85.

    What I am trying to find out is if bridging can **only** be half the speed
    of normal wireless NIC-to-AP speed. Or is it possible to get higher than
    half the rated speed?

    I wish 802.11n were available in APs that will bridge. The ones I have seen
    so far can only be used as an AP, not a bridge.

    Thank you for the link. I'll go take a look at it now.

    Gregg Hill
    Gregg Hill, Sep 11, 2006
  4. Gregg Hill

    Gregg Hill Guest

    I meant to say 6dbi D-Link "indoor" antenna and not 6dbi D-Link "internal"

    Gregg Hill
    Gregg Hill, Sep 13, 2006
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