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[WL1271] How to disable periodic scan?

Hao Han
Prodigy 30 points
Other Parts Discussed in Thread: WL1271

Hi all,

I find that the driver wl1271 will send a couple of "probe requests" every 20 sec when connected to an ap. I am just wondering if it is able to disable the scanning or find some way to control it manually. I have tried to (1) set power mode to short_doze or long_doze, (2) disable "roaminG", and (3) stop "scAn" by wlan_cu. No one works. Hope someone can help me out.

My platform is Amazon Kindle Fire.

MCP version:   MCP-WL_2.5.4.1
WLAN Driver:   MCP-WiLink_Driver_2.5.5.1.19_NOCCX
WLAN Firmware: Rev 6.1.5.239.69
BTIPS:  BTIPS 2.24.0.6
FM:     L2.00.4
BSP:    Android L25.inc.3.4.p2_2.5.0.9 Froyo

Thanks!

Hao

  • 0
    Expert 1585 points

    Hi Hao,

    Can you please check if the probe-request has the connected AP "ssid"?

    If So, it's a FW generated probe due to miss beacons.

    - Elad.

  • 0 in reply to Elad Raz92038
    Prodigy 30 points

    Appreciate your help, Elad. The probe request has the connected AP's ssid.

    Then, do you know how many missed beacons will trigger such a probe reuqest? Thank you!

     

    - Hao

    Elad Raz92038 said:

    Hi Hao,

    Can you please check if the probe-request has the connected AP "ssid"?

    If So, it's a FW generated probe due to miss beacons.

    - Elad.

  • 0 in reply to Hao Han
    Expert 1585 points

    After 3 beacon miss.

    Can you please send me WLAN sniffer log? I'm afraid your network RF has some issues, I would like to check whether it's something in the TX (And then only calibration is require) or RX.

    Also which module are you using?

  • 0 in reply to Elad Raz92038
    Prodigy 30 points

    Thanks, Elad. In my research project, I turned off the AP's Wi-Fi interface periodically for purpose of saving power. I guess that is why the client lost 3 consecutive (right?) beacons and sent probe requests.

    Another relevent question. Suppose in a network with heavy traffic load, the AP may not have chance to send beacons on each TBTT due to channel contention. That also may cause probe requests, right?

  • 0 in reply to Hao Han
    Expert 1585 points

    1. Probably

    2. Usually if the channel is over*over*overload there will be beacon loss, but it's not happen often.

  • 0 in reply to Elad Raz92038
    TI__Genius 9240 points

    Hi Hao,

    Per your fist question,  the Station will send probe request in case it does not receive the beacon from the AP it is connected to (default 3 beacons). It could be because of crowded environment, also due to miss calculation of the next beacon time period.

    Basically in case there is no traffic the station goes to sleep and wakes up to receive the beacon in the right time, however in case of wrong timing (can also happens if the clock is not accurate enough) the Station will not wake at the right time and miss the AP beacon. For that reason the Station will send probe request and synchronize its calculation based on the Probe response frame.

    Regards,

    Eyal