On 4/15/07, Larry Finger <larry.finger@xxxxxxxxxxxx> wrote:
Tomas Winkler wrote:
> Those are really bad names.
> __signal__ is not meaning a value __signal level__ or __signal
> strength__ means value
> __level__ is too general to describes anything
> RSSI on other hand is well defined. Maybe it's too hw/vendor dependent
> to use in stack
> but at least its names says what it is.
> Quality should be a relative number depends on maxim
> I don't think this renaming make things clearer
> Tomas
Perhaps my names are bad; however, the existing system is broken. With it, passing the rssi value
and the signal strength from bcm43xx-mac80211 results the following output from iwconfig: "Link
Quality=216/146 Signal level=-197 dBm Noise level=-63 dBm". In bcm43xx-softmac, the code in the
driver is identical and results in "Link Quality=90/100 Signal level=-36 dBm Noise level=-69 dBm".
When I proposed a patch to fix mac80211, Michael Wu NACKed it and requested the name changes I
propose here. I don't care what names things get, but it needs to be fixed!
Larry
Yeah, I wasn't much constructive in my critique
So here is my humble suggestion. I suggesting not to kill rssi.
u8 rssi (signal is already in rSsi)
s8 signal_level (always in dBm)
s8 signal_noise
u8 link_qual
rssi should stay rssi and its range is from 0 to 255 i.e. one byte. 0
means no signal
and maximal value should be set by underlying driver.
signal_level is in dBm.
There should not be mixing between signal_level and rssi as it is now in wext.
'man iwconfig'
rssi - Received signal strength (RSSI - how strong the received
signal is). May be arbitrary units or dBm,
The confusion comes from fact that
signal_level (dBm) is usually computed by some magic equation from
RSSI but they are not the same.
In general wext should be interested only in dBm values for 'Signal Level'
Link quality computation should be left to underlying driver as it is
totally hw dependent and may includes different parameters that are
hard to generalize in subsystem level.
It should be equal neither to rssi nor to signal level.
The only reason to keep also rssi is that it's necessary for the
underlying driver and it's easier and to compute with.
As you can see the in the code it self the intention of wext was just that.
/*
* Quality of the link
*/
struct iw_quality
{
__u8 qual; /* link quality (%retries, SNR,
%missed beacons or better...) */
__u8 level; /* signal level (dBm) */
__u8 noise; /* noise level (dBm) */
__u8 updated; /* Flags to know if updated */
};
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