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  1. #1
    tdawg's Avatar
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    Oct 2006

    Post Having problems with your WIFI , maybe is you or somebodys bluetooth transmission


    The deployment of both Bluetooth and 802.11 networks in the same area is a bit risky, though, because of the potential for interference.
    What's the problem?

    Similar to 802.11b, Bluetooth devices operate within the 2.4 GHz band. The difference is that that Bluetooth uses frequency hopping (at 1,600 hops per second) to hop over the entire 2.4 GHz band. 802.11b, on the other hand, uses direct sequence and only occupies approximately one third of the 2.4 GHz band. As a result, Bluetooth hops all over 802.11b transmissions.
    An 802.11 station (client or access point) is polite and first listens to the medium before transmitting. If the 802.11 station doesn't sense RF energy above a certain threshold (meaning that the medium is idle), the 802.11 station can transmit a frame. While the 802.11 station is sending the frame, other 802.11 stations will hold off their transmissions by following the same protocol. This provides a fairly good method of sharing a common RF channel among devices complying with the 802.11 standard.
    A critical problem is that Bluetooth and 802.11b neither understand each other nor follow the same rules. A Bluetooth radio may haphazardly begin transmitting data while an 802.11 station is sending a frame. This results in a collision, which forces the 802.11 station to retransmit the frame when it realizes that the receiving station is not going to send back an acknowledgement. This lack of coordination is the basis for RF interference between Bluetooth and 802.11.
    Interference impacts vary

    Because of the potential for collisions, 802.11 (and Bluetooth) networks can suffer lower performance. An 802.11 station automatically lowers its data rate and retransmits a frame when collisions occur. Consequently, the 802.11 protocol introduces delays in the presence of Bluetooth interference.
    The full impact of RF interference depends on the utilization and proximity of Bluetooth devices. Interference can only occur when both Bluetooth and 802.11b devices transmit at the same time. Users may have Bluetooth devices in their PDAs or laptops, but no interference will exist if their applications are not using the Bluetooth radio to send data

    What can you do to avoid interference from Bluetooth devices? The following are some tips to consider:
    • Manage the use of RF devices. One way to reduce the potential for interference is to regulate the types of RF devices within your facility. In other words, establish your own private regulatory body for managing unlicensed RF devices. The extreme measure would be to completely ban the use of Bluetooth; however, that is not practical or even possible in all cases. For example, you can't feasibly prohibit the use of Bluetooth in public areas. For private applications, you could set company policies to limit the use of Bluetooth to only specific applications, such as syncing PDAs to desktops.
    • Ensure adequate 802.11 coverage. Strong, healthy 802.11 signals throughout the coverage areas helps reduce the impact of the Bluetooth signals. If wireless LAN transmissions become too weak, then the interfering Bluetooth signals will be more troublesome. As a result, perform a thorough RF site survey, and determine the appropriate location for access points.
    • Move to the 5 GHz band. If none of the above steps solve the problem, then consider using 5 GHz (i.e., 802.11a) NICs and access points At least for the foreseeable future, you can completely avoid RF interference in this band. You'll also receive much higher throughput; however, the limited range could require additional access points and higher costs
    BB8900 is mine!

  2. #2
    xaurav's Avatar
    xaurav no está en línea Stack level 3
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    Jan 2006

    Re: Having problems with your WIFI , maybe is you or somebodys bluetooth transmission

    cool info thx man

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