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WiLink8 Reception Problems

Rolf Schmidt
Intellectual 310 points

Hi,

please find below a WLAN capture file of a ~10 Mbps TCP downlink traffic from AP to Android device using WL8.   The WLAN connection between AP and the Android device is wired (WLAN antenna of Android device has been removed and RF cable has been connected to RF port, WLAN sniffer has been connected via directional coupler). Despite this ideal RF connection the Android device is once and then not able to receive WLAN packets. Please find below an example and the complete WLAN capture file. Do you have any explanation for these reception gaps?

Capture 2-2017-01-13T11.33.52.154.zip

  • 0
    Intellectual 310 points
    Hi,
    I would like to add this this is a 5G HT40 SISO connection
  • 0 in reply to Rolf Schmidt
    TI__Mastermind 35795 points
    hi , i did not understand your question completely . Can you please explain it in more detail with exact h/w s/w WL8 module being used ?
    Saurabh
  • 0 in reply to S
    Intellectual 310 points

    Hi,

    we are using WL1873Q, driver R8.7 SP1 and firmware: 8.9.0.0.70 (8.2.0.0.237), operating system is Android, processor Tegra4.

    As said we are observing that WL8 is once and then (serveral times in one minute) not acknowledging incoming packets although there is neither RF interference nor RF fading.

    BR Rolf

  • 0 in reply to Rolf Schmidt
    TI__Mastermind 35795 points
    Hi , WiLink8 is capable of ~100Mbps TP on 5GHz/40MHz band. You shouldn't see this issue at 10Mbps TP unless there is an issue with test setup / RF . Can you pls let me know the signal strength on DUT with WiLink8
    Saurabh
  • 0 in reply to S
    Intellectual 310 points
    Hi Saurabh,

    the problem is not the average t'put, we also see about 95 Mbps on HT40. The problem is that our application has very though latency requirements. TCP re-transmissions which take more than 80 msec are already causing problems in our application.

    TCP retransmission are occurring when WLAN is discarding max WLAN retry limit of transmitter. When WL8 is not responding to 7-10 incoming packets which can take only 2-3 msec packet is already discarded. Thus I would like to know whether WL8 has such very short time periods at which is cannot receive any packets. I know one event: WL8 self calibration which however is communicated to transmitter by setting the power save flag. Thus my question is: is WL8 able to receive packets permanently? What could be potential reasons that this is not the case?

    BR Rolf



    Rx RSSI is about -50 dBm. We also see 100 Mbps, the problems is that even several msec