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There is a portion of code dealing with unexpected reception in wlan_mac_dcf.c line 307. (802.11 reference design v0.92)
if(!WLAN_IS_CTRL_FRAME(rx_header) && (mpdu_info->length < sizeof(mac_header_80211))){
pass_up = 0;
}
Since "frame_receive" is called after a good SIGNAL field is detected by either PHY (OFDM or DSSS)
Is this situation possible to happen?
That is, WARP might receive something that have a good SIGNAL field but the length is smaller than mac_header_80211 and is not a control packet?
If it is not possible to happen, is it fine to remove these code?
Thanks~
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That code is designed to catch a very rare, *very* hard to find bug in the Rx PHY. In long tests we will occasionally observe a reception flagged as FCS=good but with bogus length (too short) and header values (not meaningful addresses, types, etc.). This only occurs when DSSS Rx is enabled, but the errant receptions are marked as OFDM receptions. We have been looking for an experiment that can reliably trigger this behavior, so far unsuccessfully. The code above is only used to catch and reject these receptions before they can be passed up to CPU High. I would recommend leaving this code in place until we finally squash the PHY bug.
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I see. Thank you for the reply.
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I see. Thank you very much.
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Just to follow up on this- the PHY bug that caused this has been fixed, as of v0.95 of the 802.11 Reference Design.
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