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
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