[aprssig] Tools for Reliability Improvements
tkomljan at yahoo.co.uk
Sat Nov 29 14:20:28 CST 2008
What is the groups thoughts/ideas on imbedded intelligent algorithms in digipeaters and iGates to reduce the QRM? The intent is to limit congestion... a traffic cop at the digi.
We already have "path correction" to downsize the number of hops automatically. A step in the right direction.
Ignore packets passing from user selected iGates or wide coverage digi's assuming that the packed is already successfully in APRS_IS? The digi operator could preset a list of other iGates or digi's that can be passed to APRS-IS, but not digipeated, or ignored altogether to avoid placing redundant packets back on-the-air if they have already been dealt with by others.
A fill-in digi with "polite" channel access dumps packets that are repeated by a wide-area digi? Some conditions about the wide area coverage must be applied.
Since position is usually sent by APRS mobiles, the smart digi or iGate could remain fully engaged with close in mobiles similar to how "# filter m/15" works? It can keep a stack of mobiles known to be in the area and exclude others.
Presently APRS has timers (like 30 seconds) to avoid circulating or duplicate packets. A more complex approach would involve dynamically identifying abusive paths, beacon rates, etc... allow them at first and if they continue over time, start to throttle them. A method of self healing to protect the channel loading? We do this in alarm systems to protect from a "chattering" contact closure among other fault conditions so we don't create SNMP "storms". In this way, a new station with frequent beacons or posits (for instance) would be OK while moving, but if it continued to beacon at 1 minute intervals while parked, the intelligent digi or iGate would start ignoring it in a ramped rate. Worded differently... smart-beacon traffic control implemented at the digi.
This sort of autonomous decision making could reduce the "polution" on a simplex channel. Alas, I'm not a programmer, just a very capable RF guy. I'd be happier with a better channel access method to avoid collisions in the first place.
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