[clue-tech] WAP performance.

[Maxwell Spangler]

On Thu, 2010-05-20 at 20:42 -0600, David L. Anselmi wrote:
> It's just over a week until installfest.  I'm bringing a wireless access point.  Is there anything 
> to look for to improve performance for multiple users?
> 
> At home I run a Debian repository on my laptop and download to my desktop, both over wireless (G, 
> though the WAP might be set for B or G).  The d/l speed seems about the same as DSL, ~160kB/s or ~1Mbps.
> 
> That seems too slow and I'm pretty sure that I got better rates when the desktop was on wired.  Do 
> the laptop uploading and the desktop downloading compete for bandwidth?

So your setup is:

laptop <--wireless----> wireless router <--wireless----> desktop
or
laptop <--wireless----> wireless router <===wired===> desktop

I would presume communication to work like this in the first case:

1. laptop sends a packet from laptop-> router
2. router passes packet from router -> desktop
3. desktop acknowledges packet via desktop-> router
4. router passes acknowledgement via router -> laptop

I am going to assume that a single wireless channel acts like an
ethernet hub (specifically, a hub, not a switch) and that when multiple
devices attempt to use the single wireless channel, there is contention
and they are slowed down because of this.

Therefore, giving a laptop a dedicated wireless connection to the router
and giving a desktop a dedicated wired connection to the router could
make things slightly faster.  It would all have to do with how well the
router monitors its respective communications links and slips traffic to
& fro.

If my hub idea is correct, then a possible way to improve speed in an
installfest environment would be multiple wireless routers each on a
different channel connecting to a wired high speed network.  My thinking
is four routers (four channels) with 5 users each would be faster than
one router with 20 users.

I've got a linksys running DD-WRT that I could bring to the installfest
and bridge up (as long as I'm in town that weekend.)  I'll bet others
might be able to do similar.. 

-- 
Maxwell Spangler
========================================================================
        Linux, Unix and Database Administration
        Currently: Boulder, Colorado
        LinkedIn: http://www.linkedin.com/in/maxwellspangler