Re: RFC Patch v2: Add signal strength to nl80211station info

[Henning Rogge <hrogge@googlemail.com>]

[-- Attachment #1: Type: text/plain, Size: 892 bytes --]

On Saturday 06 December 2008 10:15:20 Johannes Berg wrote:
> Yes, well, depending on which values you used you might have run into
> the fact that the values from the tables were already rounded.
Both  errors happen for 20 Mhz channels... one of them is definitely a typo in 
the wiki.

I get 144.4 MBit/s (wiki says 144.0) for MCS 15 (long GI)
and 115.6 MBit/s (wiki says 173.3, which is a typo !) for MCS 27(short GI).

in pseudocode:
-----------------

int modulation = mcs & 7;
int streams = mcs / 8;

int bitrate = (flags & 40MHZ) ? 13500000 : 6500000;

if (modulation < 4)
    bitrate *= (modulation + 1);
else if (modulation == 4)
    bitrate *= (modulation + 2);
else
    bitrate *= (modulation + 3);

bitrate *= streams;

if (flags & SHORT_GI)
    bitrate = (bitrate * 10) / 9;

return (bitrate + 50000) / 100000; // do NOT just round down

Henning


[-- Attachment #2: This is a digitally signed message part. --]
[-- Type: application/pgp-signature, Size: 197 bytes --]