[robocup-humanoid] Summary of rule discussions in Mexico/Regarding WiFi

[Daniel Seifert]

On Mon, Sep 3, 2012 at 8:09 PM, Alejandro Malo Tamayo <
alexmalo at ctrl.cinvestav.mx> wrote:

> Dear humanoid teams
> Regarding the WiFi limitations and restrictions please see the respective
> sections of the wikipedia WiFi entry. That might give more insight into the
> problem.
>
> As a user I realize that WiFi is an evolving standard. If I understand
> correctly the number of channles is geographically dependent. It has
> between 11 and 14 channels (Link Layer), *but they are overlapping
> channels*, non overlapping channels must differ by five or more. So
> really there are only three independent channels.
>

For 2,4GHz we assume 11 channels to not exclude any teams. For practical
purposes you usually go for a difference of less channels to minimize
interference, but either way it is obvious that considering the amount of
leagues and fields we will never get a "clean" setup. But this is not
necessary if everything is harmonized or improved. One option, for example,
would be to go to 5 GHz as this offers additional channels to chose from
and this band should be less crowded (but suffers other problems). Other
options include limiting audience interference (their phones may connect to
our open and visible APs automatically) by using hidden ESSIDs or employing
WEP, and of course making sure that only few APs are actually running
(that's why we do not allow teams to have their own AP).

We will have a survey later this month which in part covers this topic in
order to collect feedback from the teams.

In Mexico, if I remember correctly each team had a subnet (Internet layer).
> 36  humanoid teams, not considering other categories.  They had to share
> channels. You might also consider restricting the use of channels.
>

Subnets are in OSI layer 3, whereas the 802.11b channels are on OSI layer
1. They have nothing to do with each other. The humanoid league had a total
of 6 APs running (one for each field), which channels were set to maximum
difference possible based on location and in coordination with the
neighboring SPL league (which had 4 APs).

Best regards

Daniel

On Sep 2, 2012, at 4:31 AM, Daniel Seifert <dseifert at fumanoids.de> wrote:
>
> Dear humanoid teams,
>
> on behalf of the Technical Committee, please find below a short
> summary on the rule discussions and votes held in the team leader
> meetings at RoboCup 2012 in Mexico City.
>
> -----------------------
>
> Considering the usual WiFi problems at the venue, discussions were
> held regarding how to minimize this issue in the next year(s).
>
> Possible approaches:
> - reduction of bandwidth/team to 500kbit/s
> - using 5 GHz band
> - hidden ESSID
> - using a WEP-Key so visitors can not accidentially connect to AP
> (majority of teams indicated that their robots support WEP)
> - using a WEP-Key per game to minimize interference with other teams
> still connected to this field
>
>
> -----------------------
>
> dseifert at fumanoids.de
> Phone +49 30 838 75-117 (Office), -125 (Lab)
>
> Freie Universität Berlin
> Institut für Informatik
> AG Intelligente Systeme und Robotik
> Arnimallee 7
> 14195 Berlin
> Germany
> _______________________________________________
> robocup-humanoid mailing list
> robocup-humanoid at cc.gatech.edu
> https://mailman.cc.gatech.edu/mailman/listinfo/robocup-humanoid
>
>
>
>
>  Alejandro J. Malo Tamayo
> Control Automático/Cinvestav
> Av IPN 2508
> Mexico 07300
> http://www.ctrl.cinvestav.mx
> alexmalo at ctrl.cinvestav.mx
>
>
>


-- 
dseifert at fumanoids.de
Phone +49 30 838 75-117 (Office), -125 (Lab)

Freie Universität Berlin
Institut für Informatik
AG Intelligente Systeme und Robotik
Arnimallee 7
14195 Berlin
Germany
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