Roaming issue with 802.11g

Discussion in 'Wireless Networking' started by, Jan 2, 2005.

  1. Guest

    I am looking for any help and any experiences of any 802.11g roaming
    issues; that is any device equipped with a 802.11g card communicating
    with Access Points with 802.11g cards. Take in mind that this is in a
    facility. The issue with the roaming is that when a device that is
    communicating with an Access Point and it is moved down the hall right
    under another Access Point the device is still associated with the AP
    (Access Point) from where it left and will not associate the other APs
    until two minutes have past or until the device is rebooted. This is
    not what we want.

    Access Points have 802.11g cards from Proxim (I believe originally
    Lucent then Orinoco) with latest firmware. The devices using 802.11g
    cards are IBM ThinkPad R50 (Model: 18306FU) with XP Pro SP1 using the
    IBM 11a/b/g Wireless LAN Mini PCI Adapter with latest driver (no
    firmware available), IBM ThinkPad R51 (Model: 288868U) with XP Pro SP1
    using the Intel PRO/Wireless 2200BG adapter with latest driver (no
    firmware available) and Motion Computing M1400 Tablet PC with XP Tablet
    Edition SP1 using the Intel PRO/Wireless 2200BG adapter. Also an IBM
    ThinkPad T41 or T42 with XP Pro SP2 using the Intel PRO/Wireless 2200BG

    Our network engineer had spoke with someone from Proxim and after some
    amount of time emailed a possible solution which was a
    registry string value named: ScanTimeValid

    Proxim default value for ScanTimeValid is: 120000 ms (milliseconds)
    which should equate to 120 seconds (2 minutes)

    Proxim suggestion was to make the value at 30000 ms which would be 30

    This registry string value is to be put where the wireless adapter is
    located in the registry:


    expand the Class folder then arrow down the folders that have keys that
    look like this example:

    and in the right pane you will see at very top in the Name column
    things like Windows CE USB Devices, Universal Serial Bus controllers,
    etc...until you arrow down and see Network adapters in the right pane.
    Expand the key that references the Network adapters and you will see
    keys that are numbered 0000, 0002, 0003 and so on. One of these will
    list the wireless adapter. You can see string values like DriverDate,
    DriverDesc, NameProvider, etc. This is where Proxim says to add the
    string value ScanTimeValid and to put the value at 30000.

    This helps the roaming issue on the IBM ThinkPad R50 (Model: 18306FU)
    using the IBM 11a/b/g Wireless LAN Mini PCI Adapter and I noticed that
    more recent drivers actually put the ScanTimeValid string in the
    registry but I do not recall the default value (I believe it was 45
    seconds). The adapter now switches over to the other Access Points
    with no problem.

    Adding the ScanTimeValid string value to the devices (IBM ThinkPad R51,
    IBM ThinkPad T41 or T42 and Motion Computing 1400 Tablet PC) that use
    the Intel PRO/Wireless 2200BG Adapter does not solve the roaming issue.
    Our engineer has open tickets to IBM and Intel; IBM has nothing now
    and Intel said try their latest driver (Version and not to use
    their client software but it has not solved the roaming issue.

    Does anyone have this problem, know of it, solved it and can anyone
    , Jan 2, 2005
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