[OZAPRS] Analysis of VK1 APRS traffic.

[Damien Gardner Jnr]

----- Original Message ----- 
From: "Carl Makin" <carl at stagecraft.cx>
.. snip some really cool stats :) ..
> Min channel utilisation: 0
> Max channel utilisation: 65%
> Average channel utilisation: 18.88%
> Median channel utilisation: 18.64%
> then I rounded all the individual utilisation figures to whole
> numbers to get the mode, which was 19.
>
> Hunting on the net it looks like 50% to 65% is a reasonable maximum
> utilisation rate for a p-persistence CSMA network like our APRS
> network however other sites indicate you should divide the maximum
> throughput for the channel by the number of users. If that's the case
> then our channel utilisation averages 39% which would certainly make
> it hard for mobile stations to get into Mt Ginini from outside the
> ACT (ie weaker signals) especially as both Peter, VK1NPW and I are
> quite strong into Mt Ginini.

I've gotta say I never realised utilisation was that high!  It's certainly

quieter than Melbourne!  On a normal Ethernet (or other network link for 
that matter), 70% utilisation is where you go 'crap I need a bigger link',

because latency just started to exponentially increase on a switched (with

store&forward) network, and collisions are starting to go through the roof

with a non-switched (hub or ye olde coax) network.. I'd probably guess
that 
point would be somewhat lower on RF where the txdelay is somewhat longer 
than it would be on a standard network?

Was that 65% including packets coming through from the Sydney igate during

the evening?

Cheers,

Damien 


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