[Cerowrt-devel] treating 2.4ghz as -legacy?

[David Lang]

On Tue, 17 Dec 2013, Theodore Ts'o wrote:

> On Tue, Dec 17, 2013 at 03:43:45PM -0800, Stephen Hemminger wrote:
>> I concur with Jim.
>>
>> My observation is that in our house, upstairs the 5Ghz AP has low
>> signal strength reported by the devices, and poor bandwidth.
>>
>> Could it be that the radiation pattern of the antenna in WDR3800
>> laying horizontally is different for each band. Maybe the 5Ghz band
>> is more of a squashed donut?
>
> I haven't done a careful study with the WNDR3800 running CeroWRT, but
> with my previous dual-band AP's, where my AP is located in the attic
> of my house, 5GHz works great on the 2nd floor, but on the first
> floor, it's very spotty; it tends to depend on the quality of the
> antenna (or WiFI chipset; that's not entirely clear) of the laptop or
> mobile handset involved.  Some models show low signal strength on the
> 5GHz band; other models simply don't work at all on 5GHz.
>
> So it may be an "urban legend" that 5GHz penetrates residential
> housing materials more poorly than 2.4GHz radio waves, but all I can
> tell you is that 5GHz is definitely much works much more poorly in my
> house.  I don't know if it has to do with the antenna quality, or the
> radio quality, at either the AP or the client, but it's definitely an
> observable phenomena.  I'll have to program in the 5GHz SSID into some
> of my devices that historically have completely failed to function on
> 5GHz when on the first floor of my house (but which work just fine on
> the 2nd floor) to see if things are any better with CeroWRT running on
> the WNDR3800.

the power tends to be a little lower on 5GHz and the antennas are tuned for 
2.4GHz so they aren't quite as efficient. Both of these tend to result in worse 
5G performance

> I don't mind using multiple routers, if at some point CeroWRT were to
> gain the advanced feature of talking to other routers and forcing a
> disassociation when the signal strength talking to a particular client
> gets significantly weaker than compared to the signal strength from
> another AP.  Is there any special hardware support needed to do this
> kind of AP-to-AP handoff, or is it just really complicated and no one
> has bothered to do it in an open source implementation?

As far as I have been able to tell this is purely a software thing. I'm not sure 
that it's even that it's so complicated as it is that there are no standards for 
APs to talk to each other to do this sort of thing so nobody has tackled it as 
an opensource project.

The commercial versions all seem to have a central server that makes these 
decisions rather than the peer-to-peer model I would expect for an open 
implemnetation.

David Lang