From: Johannes Berg <johannes-cdvu00un1VgdHxzADdlk8Q@public.gmane.org>
To: "Rao, Krishna" <kcrao-A+ZNKFmMK5xy9aJCnZT0Uw@public.gmane.org>
Cc: "radiotap-sUITvd46vNxg9hUCZPvPmw@public.gmane.org"
<radiotap-sUITvd46vNxg9hUCZPvPmw@public.gmane.org>
Subject: RE: Regarding A-MPDU status field
Date: Mon, 20 Feb 2012 12:03:29 +0100 [thread overview]
Message-ID: <1329735809.3458.14.camel@jlt3.sipsolutions.net> (raw)
In-Reply-To: <21E1C3B49A18BA428D58607D5EEA5398C3D354-RqevaKtL5OWBP98+muIrrKRtKmQZhJ7pQQ4Iyu8u01E@public.gmane.org>
Hi,
Sorry for the delay in reviewing this.
> >But now imagine a device misses a frame due to decode problem or so ...
> >then which one would you want:
> >1) subframe index skips that one
> >2) subframe index just increases
> >
> >Say
> > [mpdu][pad][pad][----][pad][mpdu]
> >1) 0 1 2 (3) 4 5
> >2) 0 1 2 3 4
> >
> >but then the driver would have to guess at the padding? Not sure. In any case, we need to nail
> >this down, because in the case 2) the driver can number the subframes (but it's less useful),
> >and in the case 1) the device has to provide it (and not all do -- so we need a separate valid bit).
> >In the case 1), even the application (wireshark) could provide the subframe index?
>
> Good you brought this up.
>
> I had basically case 2) in mind. Even the device itself may not always
> be able to provide the index for subframes totally skipped due to
> decode problems.
Yes, good point.
> It may sometimes be able to pass to the driver subframes with bad
> delimiter CRC and these would get indexed by the driver (with flag
> 0x10 set). So the principle is that only whatever subframes the device
> can pass to the driver, good or bad, get indexed.
>
> But I now feel the application itself can provide the subframe
> indexing (as in case 2). It can use the subframe reference number and
> timestamp for this. The burden on the driver would be decreased, and
> we also save space in the Radiotap header by removing this field.
Makes sense to me. I guess that means we just remove the ampdu subframe
index from the proposal, so we have this?
A-MPDU radiotap field
-----------------------
bit index: TBD
alignment: 4 bytes (u32)
* ampdu reference number (u32)
* flags (u16)
- 0x01: driver reports 0-length subframes
- 0x02: is 0-length subframe (valid if 0x01 set)
- 0x04: last subframe known
(should be set for all subframes if driver knows)
- 0x08: is last subframe in ampdu (valid if 0x04 set)
(clear for all but last subframe)
- 0x10: delimiter CRC error
- 0x20: delimiter CRC value known
* delimiter CRC value (u8) (valid if flag 0x20 set)
* u8 (reserved)
(I added the reserved field and changed the flags to u16, it seems
relatively likely that other fields will need u32 alignment so it seems
reasonable to reserve a byte here, maybe for VHT extensions?)
johannes
next prev parent reply other threads:[~2012-02-20 11:03 UTC|newest]
Thread overview: 24+ messages / expand[flat|nested] mbox.gz Atom feed top
2011-10-31 9:13 Regarding A-MPDU status field Rao, Krishna
[not found] ` <21E1C3B49A18BA428D58607D5EEA5398BB2E90-RqevaKtL5OWBP98+muIrrKRtKmQZhJ7pQQ4Iyu8u01E@public.gmane.org>
2011-11-02 8:42 ` Johannes Berg
[not found] ` <1320223343.3950.29.camel-8upI4CBIZJIJvtFkdXX2HixXY32XiHfO@public.gmane.org>
2011-11-03 15:02 ` Rao, Krishna
[not found] ` <21E1C3B49A18BA428D58607D5EEA5398BB67FA-RqevaKtL5OWBP98+muIrrKRtKmQZhJ7pQQ4Iyu8u01E@public.gmane.org>
2011-11-09 14:02 ` Johannes Berg
[not found] ` <1320847366.3845.72.camel-8upI4CBIZJIJvtFkdXX2HixXY32XiHfO@public.gmane.org>
2011-11-09 20:45 ` David Young
2011-11-13 16:49 ` Rao, Krishna
[not found] ` <21E1C3B49A18BA428D58607D5EEA5398BBBD18-RqevaKtL5OWBP98+muIrrKRtKmQZhJ7pQQ4Iyu8u01E@public.gmane.org>
2011-11-14 8:26 ` Johannes Berg
[not found] ` <1321259214.4472.16.camel-8upI4CBIZJIJvtFkdXX2HixXY32XiHfO@public.gmane.org>
2011-11-20 16:37 ` Rao, Krishna
[not found] ` <21E1C3B49A18BA428D58607D5EEA5398BC8C00-RqevaKtL5OWBP98+muIrrKRtKmQZhJ7pQQ4Iyu8u01E@public.gmane.org>
2011-11-21 9:27 ` Johannes Berg
[not found] ` <1321867620.3999.7.camel-8upI4CBIZJIJvtFkdXX2HixXY32XiHfO@public.gmane.org>
2011-11-22 14:27 ` Rao, Krishna
[not found] ` <21E1C3B49A18BA428D58607D5EEA5398BC971A-RqevaKtL5OWBP98+muIrrKRtKmQZhJ7pQQ4Iyu8u01E@public.gmane.org>
2011-11-22 17:06 ` David Young
2011-11-22 14:33 ` Rao, Krishna
2011-11-23 15:23 ` Rao, Krishna
2012-01-03 17:25 ` Rao, Krishna
[not found] ` <21E1C3B49A18BA428D58607D5EEA5398C1F289-RqevaKtL5OWBP98+muIrrKRtKmQZhJ7pQQ4Iyu8u01E@public.gmane.org>
2012-01-04 10:42 ` Johannes Berg
[not found] ` <1325673736.3339.27.camel-8upI4CBIZJIJvtFkdXX2HixXY32XiHfO@public.gmane.org>
2012-01-08 13:43 ` Rao, Krishna
[not found] ` <21E1C3B49A18BA428D58607D5EEA5398C20149-RqevaKtL5OWBP98+muIrrKRtKmQZhJ7pQQ4Iyu8u01E@public.gmane.org>
2012-01-09 10:16 ` Johannes Berg
[not found] ` <1326104166.3451.21.camel-8upI4CBIZJIJvtFkdXX2HixXY32XiHfO@public.gmane.org>
2012-01-15 19:14 ` Rao, Krishna
[not found] ` <21E1C3B49A18BA428D58607D5EEA5398C36652-RqevaKtL5OWBP98+muIrrKRtKmQZhJ7pQQ4Iyu8u01E@public.gmane.org>
2012-01-16 13:46 ` Johannes Berg
[not found] ` <1326721599.3510.18.camel-8upI4CBIZJIJvtFkdXX2HixXY32XiHfO@public.gmane.org>
2012-01-23 16:16 ` Rao, Krishna
[not found] ` <21E1C3B49A18BA428D58607D5EEA5398C3D354-RqevaKtL5OWBP98+muIrrKRtKmQZhJ7pQQ4Iyu8u01E@public.gmane.org>
2012-02-20 11:03 ` Johannes Berg [this message]
[not found] ` <1329735809.3458.14.camel-8upI4CBIZJIJvtFkdXX2HixXY32XiHfO@public.gmane.org>
2012-02-22 1:14 ` Rao, Krishna
[not found] ` <21E1C3B49A18BA428D58607D5EEA5398C55E21-RqevaKtL5OWBP98+muIrrKRtKmQZhJ7pQQ4Iyu8u01E@public.gmane.org>
2012-02-23 15:48 ` Johannes Berg
2012-07-05 9:49 ` Johannes Berg
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