Changes between Version 27 and Version 28 of 802.11/MAC/Lower/Retransmissions


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Timestamp:
May 6, 2015, 10:52:08 AM (9 years ago)
Author:
chunter
Comment:

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  • 802.11/MAC/Lower/Retransmissions

    v27 v28  
    196196
    197197In this example, we see the error introduced in [#ExampleL.3 Example L.3] taken to its limit when the maximum retransmission limit is reached. Since RTS transmissions count as "short" frames, this example is actually equivalent to [#ExampleS.3 Example S.3].
     198
     199== Example L.6 ==
     200
     201{{{
     202#!div style="overflow-x:scroll; border:1pt solid"
     203[[Image(ex_l_6.png)]]
     204}}}
     205
     206This example mixes the long and short failures introduced respectively in [#ExampleL.2 Example L.2] and [#ExampleL.3 Example L.3], respectively. In this example, an RTS transmission fails 6 times. On the 7th attempt, however, a CTS is received. According to '''''Excerpt F from 9.3.3 of 802.11-2012''''' from [#ExampleL.3 Example L.3], the SSRC is reset to 0 at this time. Neither that SRC nor the CW are reset at this time. The successful reception of the CTS then causes then MPDU to be transmitted. Failure to receive an ACK for this MPDU causes the LRC and SLRC to increment. The CW would have also increased had it not already been at its maximum value. From this point forward, the behavior of the example matches [#ExampleL.2 Example L.2].
     207
     208Notice that having a ''dot11ShortRetryLimit'' of 7 and a ''dot11LongRetryLimit'' of 4 actually allows for a total of 10 "attempts" to transmit (6 RTS-only transmissions followed by 4 RTS and MPDU transmissions).