Re: 10 Mbit/s problem in your network

[Owen DeLong <owen () delong com>]

On Feb 17, 2013, at 21:12 , Mikael Abrahamsson <swmike () swm pp se> wrote:

> On Sun, 17 Feb 2013, Owen DeLong wrote:
>
> > Greater attenuation is an oversimplification.  5Ghz penetrates things like stucco and concrete better than 2.4. 
> > OTOH, 2.4 gets through trees
>
> My empirical experience with 5GHz says it penetrates concrete a lot less than 2.4. For instance, in one building I 
> was in, 5GHz didn't penetrate the floor so it was only available on the same floor as the AP, but 2.4 GHz worked well 
> both on the floor above and below the AP. This was in a building with quite thick concrete floor, a 3 story town 
> house with the AP placed on the middle.

The floor isn't just concrete. Many industrial floors include solid steel plating in the floor. 5 Ghz will not 
penetrate that and neither will 2.4 (at least not very well).

A town house is also likely to have some form of metal plating (or at least a very high concentration of rebar) in the 
concrete between floors as well, so, I suspect your issue was the metal, not the concrete.

2.4Ghz probably found a path around the outside of the building and back in. 5Ghz once it starts in a direction tends 
to continue in that direction. It doesn't bounce or curve well at all. 2.4Ghz tends to do better at that, creating the 
illusion of lesser attenuation.

As I said, attenuation is an oversimplification. RF path identification and multipath can get very complex very quickly.


> In my current apartment, I moved my AP out of the clothes closet (fairly thin "light concrete" (don't know what it's 
> called) and put it on the wall in my hallway, this increased performance on 5GHz substantially.
>
> So I'd like to know where you got your information from because I'd like to read up more because my experience says 
> exactly the opposite.

Without knowing the details of the makeup of the walls in your closet, I have to say that seems a bit odd to me. 
Perhaps there is another explanation.

The reason 5Ghz penetrates stucco better, for example is that the 23cm wavelength is more than 4x the size of the 
openings in most of the chicken wire used to adhere stucco to walls. The 12cm wavelength of 5Ghz, OTOH, goes through 
quite nicely.

Owen