10 Mbit/s problem in your network

Owen DeLong owen at delong.com
Mon Feb 18 00:33:02 UTC 2013


On Feb 17, 2013, at 4:32 PM, Owen DeLong <owen at delong.com> wrote:

> 
> On Feb 17, 2013, at 4:17 PM, joel jaeggli <joelja at bogus.com> wrote:
> 
>> On 2/17/13 12:18 PM, Jay Ashworth wrote:
>>> ----- Original Message -----
>>>> From: "Owen DeLong" <owen at 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).
>>> 
>>> 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.
>> 
>> so what you get out of A/N is:
>> 
>> * 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. 
> 
>> * with N-mimo higher SNR if you have >= 2 antennas
>> 
>> 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 ½ - ⅛ the size (depending on the type of antenna) the size of a 2.4Ghz which also has advantages in portable applications.
> 

Sorry… Hit send prematurely…

An important consideration: A good high-gain antenna helps you with transmit _AND_ receive. More power helps you with transmit.

> Owen
> 





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