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power detection on 802.11a RRS feed

  • Question

  • Hello!! I look into SORA code, especially on carrier sensing part.

    According to what I understand, threshold-based power detection is used for 802.11b carrier sensing while correlation-based carrier sensing

    is used for 802.11a carrie sensing. Is there any reason to use different mechanism between 802.11b and 802.11a?

    In addition, if I want to implement threshold-based power detection algorithm in 802.11a carrier sensing, which threshold value should I use?

    May I just use threshold value which is used in 802.11b mechanism? Thanks


    Tuesday, August 23, 2011 11:20 PM

Answers

  • hey jaeims,

    The choice of the cs algorithm largely depends on the preamble design of the signal. 802.11a has a repeat pattern in the (short) preamble. So it is good to use an auto-correlation based detection algorithm.

    We picked the energy detection algorithm in 11b just for simplicity. You can extend it to any sophiscated detection algorithms.

    Thanks,

    - Kun

     

    Thursday, September 8, 2011 6:10 AM

All replies

  • There's no specific reason for this, we just randomly picked an algorithm for implementation.

    Basically, with correlation based CS, it's possible to detect weaker signal and with energy based CS, the signal SNR should be higher. The threshold for either correlation or energy based algorithm can be determined by your experiments.

    Another reason for correlation based CS in 802.11a is that we need to determine symbol boundary via short preamble, which can only be realized by correlation.

    -Jiansong

    Thursday, August 25, 2011 12:59 AM
  • hey jaeims,

    The choice of the cs algorithm largely depends on the preamble design of the signal. 802.11a has a repeat pattern in the (short) preamble. So it is good to use an auto-correlation based detection algorithm.

    We picked the energy detection algorithm in 11b just for simplicity. You can extend it to any sophiscated detection algorithms.

    Thanks,

    - Kun

     

    Thursday, September 8, 2011 6:10 AM