[robocup-small] Rule changes in SSL

[The BitShifter]

>Change 4: ban bluetooth communication
>
>Why this? I think that the teams with Wireless LAN had much more problems! 
>So
>why do you only want to ban the communication-system with the least 
>radiation
>power in comparison to WLAN????
>My opinion is to ban all communications on 2.4 GHz (bluetooth & WLAN) or 
>keep
>everything on air!
>Just a thought: Limit the number of used frequencies! There were some teams
>(e.g. Cornell), who used 3 frequencies (433MHz, 869MHz & 912 MHz).

This issue is not, to my mind, an issue of radiated power. Bluetooth and 
WLAN are two very different systems in terms of band useage.  WLAN (802.11x) 
is a "nice" protocol that has narrow frequency utilization that is 
selectable.  Before WLAN transmits, it does a carrier detect to see if its 
frequency is in use.  This prevents it from transmitting over another 
stations broadcast.

In comparison, Bluetooth is a very greedy protocol.  Bluetooth does not do a 
carrier sense and hops across the entire 2.4GHz band very fast introducing 
what appears to be random radio interference accross the entire 11 channels 
that exist in 802.11[b|g].  In addition, if a bluetooth station hops onto a 
frequency that a WLAN, WLAN will detect a carrier and wait until the 
frequency is clear.  Since bluetooth hops so frequently WLAN stands a good 
chance of detecting a "carrier"  all the time when a large number of 
bluetooth devices are present.

To Bluetooth's credit, it does have a low radiated power preventing it from 
interfering with the 2.4GHz band over a distance greater than about 10 
meters.  Robocup matches, however, take place over a much shorter distance.

In a normal environment, such as a wireless network in an office, there are 
not often 8 or more bluetooth devices all trying to transmit data 
continuously, so any negative effects are temporary and widely separated.

A final note, The Aibo league uses WLAN (exclusively, to my knowledge).  We 
will not always be able to have a venue where SSL and the Aibo league are 
separated enough to prevent interference with their league.  I think that we 
should try to play nice.

Mark Goldman
Ohio University, RoboCats

As always, the views and opinions expressed are my own and not necissarily 
that of my team.