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how does wireshark calculate phi and psi angle decode values for beamforming Report

asked 2018-03-24 08:33:32 +0000

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how does wireshark calculate phi and psi angle decode values for the beamforming Report,

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answered 2018-03-25 16:33:42 +0000

Jasper gravatar image

Chances are that whoever coded that feature isn't reading this question, so my best advice would be to get the Wireshark sources and check the code for the part where the angles are calculated. Or the other way would be to look at the comment section at the top of the code telling you who wrote it, so you might be able to make contact directly that way.

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The routine in question is add_ff_vht_compressed_beamforming_report() in epan/dissectors/packet-ieee80211.c. The comments for a tables used in that calculation mention Table 8-53d in the 802.11ac-2013 amendment. That's Table 9-57 in the 802.11-2016 spec (which incorporates the 802.11ac-2013 amendment), so look at section "Compressed Beamforming Report field" in 802.11-2016 to see how a program that processes beamforming reports - whether it's a protocol analyzer like Wireshark or some other type of program - should calculate the angles.

(No, I am not the person who wrote that code, so don't send me e-mail about it. The code doesn't have a comment saying who wrote it, so you'd have to look at the code in the Git repository to figure out who added it.)

Guy Harris gravatar imageGuy Harris ( 2018-03-25 18:26:50 +0000 )edit

Hi, @Jasper : Thanks for the suggestion, seems to me as the only possible solution.

@Guy Harris : The spec has it, just wanted to reconfirm the same, saw through the code in the GIT, definitely of great help. the function- add_ff_vht_compressed_beamforming_report() points to the decompressed CBF packet,

Thanks, Amit

amitpandit gravatar imageamitpandit ( 2018-03-26 04:49:17 +0000 )edit

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Asked: 2018-03-24 08:33:32 +0000

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Last updated: Mar 25 '18