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some problems about the 802.11a transmition?????????? RRS feed

  • Question

  • The problem has been confusing us for a long time, and we have no idea about the reason. So we resort to this forum to see if anyone can offer some help.


    Our environment : 802.11a, radio daughter board is USRP, when we compiled the code, we define the sample rate 44M, two antennas are 1.5m high, 3m apart, and use iperf test, with the parameters: channel 3(2.422), txgain 0x1f80, rxpa 0x1000, rxgain 0x2000, data rates: 6M, 12M, 24M .  iperf is udp broadcasting. Computer A is broadcasting, Computer B is receiving. Any else needed?

    Our phenomenon: when we set the data rate 6M(exactly set the mapping BPSK), From the iperf console, we can see A sending rate is 4M/s, and B packet lost ratio is nearly 0%. It is always OK. Then when we set the rate 12 or 24M, the result depends. Sometimes, the result is very OK, we can see A sending rate is 7 or 13M, and the B packet lost ratio is nearly 0%. but sometimes the result is very bad, the B packet lost ratio is nearly 50% in 12M rate, and 99% in 24M rate. Firstly we assume it depends the channel situations. But there is some time , if we set A send, and B receive, the result is very OK, then if we set B send, and A receive , the result is very bad. Is this asymmery also resulted from channel???

    Is anyone has the same problem? or anyone offer some advise? Thanks.

     

    Friday, March 25, 2011 9:13 AM

Answers

  • It might be caused by hardware. We are trying to fix it.

    You can restart the device as workaround.


    Sen Xiang (项森)
    • Marked as answer by Sen Xiang Thursday, March 31, 2011 8:45 AM
    Tuesday, March 29, 2011 9:00 AM

All replies

  • It might be caused by hardware. We are trying to fix it.

    You can restart the device as workaround.


    Sen Xiang (项森)
    • Marked as answer by Sen Xiang Thursday, March 31, 2011 8:45 AM
    Tuesday, March 29, 2011 9:00 AM
  • thanks!

    We disable the driver and enable the driver several times , and the results are the same.

    We are trying to change the working frequency to 5.8G, to see if the result can be better.

    Wednesday, March 30, 2011 2:12 PM