Re: [Starlink] SatNetLab: A call to arms for the next global> Internet testbed

[David Lang <david@lang.hm>]

On Tue, 13 Jul 2021, Rodney W. Grimes wrote:

> It wasnt suggested "lowering the bit rate", it was suggested to make the
> packets smaller, which actually does address the hidden transmitter problem
> to some degree as it *would* reduce your air time occupancy, but the damn
> wifi LL aggregation gets in your way cause it blows them back up.  When I
> am having to deal/use wifi in a hidden transmitter prone situation I always
> crank down the Fragmentation Threshold setting from the default of 2346 bytes
> to the often the minimum of 256 with good results.

The problem is that with wifi at modern data rates, you have a header at a low 
data rate and then data at a much higher data rate (in extreme cases, a >50x 
difference), so the amount of data that you send has a pretty minor difference 
in the airtime used. So you really do want to send a large amount of data per 
transmission to minimize the overhead

IT's not quite as bad if you have disabled 802.11b speeds on the entire network 
as that raises the header/housekeeping transmissions from 1Mb/s to 11Mb/s

David Lang