[aprssig] IS-to-RF gating... A proposal

Bob Bruninga bruninga at usna.edu
Wed Dec 28 10:28:31 EST 2011

To avoid a lot of misplaced debate on apples and oranges and confusion, the
following is a collection of -a- proposal so we can all be sure we are
debating the same thing.  I am not saying we agree to implement this.  I'm
just making sure we are all looking at the same limited idea and debating
only its merits, and not all the possible other bugaboos...

PURPOSE:  To give IGate operators a local tool to allow local selective
IS-to-RF gating while giving him the means to control it based on his local
environment (his IGate coverage range and channel loading).  For
identification, lets call this process an RGATE.  Only IS packets
specifically identified by the IS originator as potential for RF gating are
considered by the RGATE and then only the rules of the local RGATE owner
permit transmission.

IS CLIENT REQUIREMENTS:  Authors of mobile phone or other IS applications
that inject such RF gating request packets into the APRS-IS would adhere to
a specific set of "rules".  Here are some specifics to limit rates:

1) Packets intended for consideration for RF must be flagged.  Flag could
consist of RGATEx-X inserted in the IS path.  Such as:

2) Packets flagged for RGATEs should be no more often than normal APRS
packet rates.  Every 30 Minutes for benign fixed stations, every 10 minutes
for operator-present stations, and a maximum for mobiles of 1 per minute,
but must also be Decayed and Proportional-Pathed.

2) Such packets must use the APRS decaying algorithm.  Meaning, if the
position or data is unchanging, then the period to the next packet is
doubled down to the final rate of one per 30 minutes (same as all other APRS

3) Such packets must use Proportional Pathing to add a sliding "weight"
potential to each packet.  This weight can be selectively used by RGATES to
best match his local loading.  The IS source would send every other packet
to RGATE0-0. The alternating packets would be sent half the time via
RGATE1-1 and the other half the time via RGATE2-2.  This in effect
implements a 1, 2 or 4 minute rate selection potential while maintaining a 1
minute rate on the APRS-IS.

IGATE RGATING REQUIREMENTS:  The IGATE sysop can choose among a variety of

RGATE0-0 RANGE - sets the heard-range where these are gated
RGATE1-1 RANGE - Sets the heard-range where these are gated
RGATE2-2 RANGE - sets the heard-range where these are gated
DIRECT = 0-0, 1-1, 2-2 will gate these RGATEn-N packets direct only
ONEHOP = 1-1, 2-2  ... will gate these RGATEn-N packets only 1 hop
TWOHOP = 2-2  ...  ... will gate these RGATEn-N packets only 2 hops

RGATE0-0 LIMIT - Sets the number of such packets allowed per minute
RGATE1-1 LIMIT - Sets the number of such packets allowed per minute
RGATE2-2 LIMIT - Sets the number of such packets allowed per minute

For example, a typical home IGate that (ideally) only uses a 1 hop RF path
via the nearest local digipeaters might set his 1-1 RANGE to only include
the reliable coverage area of his local digis and then set ONEHOP = 2-2.
The result would be only one packet from any IS-mobile once every 4 minutes.
Or he could set ONEHOP = 1-1,2-2 and then have these mobiles appear once
every 2 minutes.  ETC.

He sets the LIMITS as a failsafe mechanism.  There is also a BLOCK list
where any abusers callsigns can be blocked if they try to induce spam.

Something like that.

Just an idea to consider.  What would need to be changed to allow this?


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