On Sat, Aug 22, 2015 at 1:32 PM, Guy Harris <[email protected]> wrote: > > On Aug 22, 2015, at 1:09 PM, Richard Sharpe <[email protected]> > wrote: > >> Also, I now see that sections 9.7.5a.4 and 9.7.5a.5 imply that MCS >> headers are appropriate for an 802.11ad capture, > > I'm not so sure about that. > > 802.11ad-2012 has Clause 21, which says: > > The DMG PHY supports three modulation methods: > > -- A control modulation using MCS 0 (the control PHY; see 21.4) > > -- A single carrier (SC) modulation using MCS 1 to MCS 12 (the SC > PHY; see 21.6) and MCS 25 to MCS 31 (the low-power SC PHY; see 21.7) > > -- An OFDM modulation using MCS 13 to MCS 24 (the OFDM PHY; see 21.5) > > so it has its own MCS values, independent of 11n and 11ac, so there should > probably be a DMG field with, among other items, an MCS subfield, containing > a value between 0 and 24. > > Don't be confused by the name of the "MCS" field; it really *should* have > been called the "HT" field, as it has subfields for more than just the MCS, > and as its MCS values are specific to the High Throughput PHY - i.e., the 11n > PHY. The page for it on the radiotap site says: > > The mcs field indicates the MCS rate index as in IEEE_802.11n-2009. > > which, if we update it to say "as in Clause 20 of IEEE 802.11-2012", says it > has values from 0 to 76, with modulations different from the ones in Clause > 21, i.e. the MCS field is *not* appropriate for 11ad. > >> so the radiotap >> dissector will need to change to use the frequency set the PHY type. > > No, I'd add a DMG field to radiotap, containing, among other values, an mcs > subfield, with a Clause 21 MCS value in it.
Yes, in an ideal world. However, there will likely be captures out there for a while yet that do not have such a DMG field because it is not yet defined. However, I agree with the below. > I'm a software engineer, not an electrical engineer, so I'm not even remotely > close to an authority on what radio-layer information would be useful, but a > quick look at Clause 21 suggests that it might want to include a flag to > indicate whether "Static Tone Pairing" or "Dynamic Tone Pairing" was used. Can you make that suggestion on the radiotap mailing list? I can then communicate it to the appropriate parties and perhaps get them to join that mailing list as well. -- Regards, Richard Sharpe (何以解憂？唯有杜康。--曹操) ___________________________________________________________________________ Sent via: Wireshark-dev mailing list <[email protected]> Archives: https://www.wireshark.org/lists/wireshark-dev Unsubscribe: https://wireshark.org/mailman/options/wireshark-dev mailto:[email protected]?subject=unsubscribe
