[160880] in North American Network Operators' Group
Re: 10 Mbit/s problem in your network
daemon@ATHENA.MIT.EDU (Owen DeLong)
Sun Feb 17 19:35:32 2013
From: Owen DeLong <owen@delong.com>
In-Reply-To: <51217324.4010509@bogus.com>
Date: Sun, 17 Feb 2013 16:32:13 -0800
To: joel jaeggli <joelja@bogus.com>
Cc: NANOG <nanog@nanog.org>
Errors-To: nanog-bounces+nanog.discuss=bloom-picayune.mit.edu@nanog.org
On Feb 17, 2013, at 4:17 PM, joel jaeggli <joelja@bogus.com> wrote:
> On 2/17/13 12:18 PM, Jay Ashworth wrote:
>> ----- Original Message -----
>>> From: "Owen DeLong" <owen@delong.com>
>>> I think by A you actually mean 5Ghz N. A doesn't do much better than =
G, though
>>> you still have the advantage of wider channels and less frequency =
congestion
>>> with other uses.
>> No, my ThinkPad doesn't *do* N, 5GHz or otherwise. Neither does my =
Sprint
>> EVO, nor, as near as I can tell, the Galaxy S4 I'm going to replace =
it
>> with this year (though on that one, I'm a tad less certain).
>>=20
>> I'd forgotten that N was dual band, though, yes. I can't say I've =
ever
>> needed the extra bandwidth N provides, personally, though certainly =
the
>> hotels we've been discussing might need more to share around.
> entirely orthonal to the frequency band used spatial division =
multipluxing as used by 802.11n is generally going to increase the SNR.
>=20
> so what you get out of A/N is:
>=20
> * more non-overlapping bands and therefore a much easier map coloring =
problem)
> * greater attenuation, which implies more limited range, but also less =
interferance.
Greater attenuation is an oversimplification. 5Ghz penetrates things =
like stucco and concrete better than 2.4. OTOH, 2.4 gets through trees =
and moist air better. In dry air and/or a vacuum, they're similar. =
Neither penetrates humans particularly well, though 5 tends to do =
slightly better.=20
> * with N-mimo higher SNR if you have >=3D 2 antennas
>=20
> All of those things make the 5Ghz band a more attractive alternative =
for lots of applications. given that it's 5Ghz it also requires more =
power, which is a problem for cellphones, but not so much for tablets =
and laptops.
OTOH, with 5Ghz, a high-gain antenna is =C2=BD - =E2=85=9B the size =
(depending on the type of antenna) the size of a 2.4Ghz which also has =
advantages in portable applications.
Owen
