higher N rates

higher N rates

[James]

$ iw dev wlan0 scan

printed this for my N (only) router:

Supported rates: 1.0* 2.0* 5.5* 11.0* 18.0 24.0 36.0 54.0
Extended supported rates: 6.0 9.0 12.0 48.0

Why doesn't it print the higher N rates?

higher N rates

[James]

$ iw dev wlan0 scan

printed this for my N (only) router:

Supported rates: 1.0* 2.0* 5.5* 11.0* 18.0 24.0 36.0 54.0
Extended supported rates: 6.0 9.0 12.0 48.0

Why doesn't it print the higher N rates?

Re: higher N rates

[Pat Erley]

On 09/23/2011 11:30 PM, James wrote:
> $ iw dev wlan0 scan
> 
> printed this for my N (only) router:
> 
> Supported rates: 1.0* 2.0* 5.5* 11.0* 18.0 24.0 36.0 54.0
> Extended supported rates: 6.0 9.0 12.0 48.0
> 
> Why doesn't it print the higher N rates?

I may be WAY off base here, but I believe iw dev wlan0 scan reports 
what's shown in the beacons, and not what rates are actually negotiable.  
Beacons only directly advertise 'pre-n' rates (the basic 802.11abg rates).

If you look at more of the scan results, you should see something like:

	HT capabilities:
		Capabilities: 0x11ce
			HT20/HT40
			SM Power Save disabled
			RX HT40 SGI
			TX STBC
			RX STBC 1-stream
			Max AMSDU length: 3839 bytes
			DSSS/CCK HT40
		Maximum RX AMPDU length 65535 bytes (exponent: 0x003)
		Minimum RX AMPDU time spacing: 8 usec (0x06)
		HT TX/RX MCS rate indexes supported: 0-15
	HT operation:
		 * primary channel: 36
		 * secondary channel offset: above
		 * STA channel width: any
		 * RIFS: 0
		 * HT protection: no
		 * non-GF present: 0
		 * OBSS non-GF present: 0
		 * dual beacon: 0
		 * dual CTS protection: 0
		 * STBC beacon: 0
		 * L-SIG TXOP Prot: 0
		 * PCO active: 0
		 * PCO phase: 0

Which outlines the 802.11n parameters that your device and the AP can use
to negotiate 802.11n operation.  Perhaps there is something more that should
be reported, but you'll see throughputs in the 802.11n range WHEN it's 
warranted.  With my DSL connection, I rarely see rates above 9mbit in use (my 
DSL is 1.5mbit down).

Pat

RE: higher N rates

[Arend Van Spriel]

> From: linux-wireless-owner@vger.kernel.org [mailto:linux-wireless-
> owner@vger.kernel.org] On Behalf Of Pat Erley
> Sent: zaterdag 24 september 2011 17:35
> 
> On 09/23/2011 11:30 PM, James wrote:
> > $ iw dev wlan0 scan
> >
> > printed this for my N (only) router:
> >
> > Supported rates: 1.0* 2.0* 5.5* 11.0* 18.0 24.0 36.0 54.0
> > Extended supported rates: 6.0 9.0 12.0 48.0
> >
> > Why doesn't it print the higher N rates?
> 
> I may be WAY off base here, but I believe iw dev wlan0 scan reports
> what's shown in the beacons, and not what rates are actually
> negotiable.
> Beacons only directly advertise 'pre-n' rates (the basic 802.11abg
> rates).

I think you pretty close to base here ;-)

> If you look at more of the scan results, you should see something like:
> 
> 	HT capabilities:
> 		Capabilities: 0x11ce
> 			HT20/HT40
> 			SM Power Save disabled
> 			RX HT40 SGI
> 			TX STBC
> 			RX STBC 1-stream
> 			Max AMSDU length: 3839 bytes
> 			DSSS/CCK HT40
> 		Maximum RX AMPDU length 65535 bytes (exponent: 0x003)
> 		Minimum RX AMPDU time spacing: 8 usec (0x06)
> 		HT TX/RX MCS rate indexes supported: 0-15

The 11n rates are expressed in MCS (Modulation and Coding Scheme) rate
indexes, which translate to a bitrate. So it also advertises 11n rates
albeit in a slightly different format.

Gr. AvS