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[aprssig] Tracker Smart Pathing

Robert Bruninga bruninga at usna.edu
Tue Mar 21 14:15:32 UTC 2006


New name:  Proportional Pathing:

Allan Pratt suggested that "Smart pathing" was not
really smart, since it is a fixed algorithm.  We came
up with Proportinal Pathing instead.  I have updated
this post:

>>> bruninga at usna.edu 03/20/06 7:59 AM >>>
The real thing we need in trackers is PROPORTIONAL
PATHING.   That is, if the user selected (in the USA) 
PROPORTIONAL PATHING = 2, Here is what he would 
get every minute:

- Except as below, every packet goes DIRECT path (no digi)
- Every 2nd minute it would use the WIDE1-1 path
- Every 4th minute it would use WIDE1-1,WIDE2-1

If he set smart pathing =3 he would get the above plus
- Every 8th minute it would use WIDE1-1,WIDE2-2

If he set SMART PATHING= 4 he would get the
same plus a 4 hop path once every 16 minutes

The result is that for close in work or meeting someone
or local events or whatever,  he gets good smooth 
one-minute tracking and minimum QRM to anyone else.  
For the local area (each digi he can hit), he gets a 
comfortable 2 minute rate.  For the large city and those 
watching out 2 hops, he gets a 4 minute rate.  And for 
people watching from a long distance away, he gets an 
8 minute rate.

This resolves the tradeoff between too high a rate (QRM)
and too low a rate (LATENCY, and LOW TRACK QUALITY)...

PROPORTIONAL PATHING would cut the QRM from each 
mobile by a factor of 16 or more. (Each hop adds 4 more 
copies in dense areas)  And since mobiles are the largest 
load on the network, this would make a HUGE difference.
While still providing good local tracking.

Also, since the WIDE1-1,WIDEn-N should work everywhere
in the USA, this one-size-fits-all appproach would make 
setting up a tracker trivial, and help make the network
immune to user set-up errors.

de WB4APR, Bob






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