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Re: Re: New baseline for GEO (rev-1)




For something completely different, how about a transponder for
digital traffic (either store-and-forward, bent-pipe or "strong-uplink"
FM to SSB to many receivers broadcast) using something like Phil Karn's FEC
to get more than a few dB of coding gain?  I'd imagine that you
could layer the FEC over a PSK31 transport for sending blocks, but
then people would probably complain about not being able to
"read the mail" like when we did IP over AX.25.

If you combined FEC codes for individual blocks with a multicast
file distribution protocol using erasure codes, you might have
a new and improved version of the Microsats broadcast file 
capability.

There's been some work in the IETF on a framework and protocols
for this sort of thing and a few RFCs (protocol documents) have
been published:

3450 Asynchronous Layered Coding (ALC) Protocol Instantiation. M.
     Luby, J. Gemmell, L. Vicisano, L. Rizzo, J. Crowcroft. December 2002.
     (Format: TXT=86022 bytes) (Status: EXPERIMENTAL)

3451 Layered Coding Transport (LCT) Building Block. M. Luby, J.
     Gemmell, L. Vicisano, L. Rizzo, M. Handley, J. Crowcroft. December
     2002. (Format: TXT=72594 bytes) (Status: EXPERIMENTAL)

3452 Forward Error Correction (FEC) Building Block. M. Luby, L.
     Vicisano, J. Gemmell, L. Rizzo, M. Handley, J. Crowcroft. December
     2002. (Format: TXT=38368 bytes) (Status: EXPERIMENTAL)

3453 The Use of Forward Error Correction (FEC) in Reliable Multicast.
     M. Luby, L. Vicisano, J. Gemmell, L. Rizzo, M. Handley, J. Crowcroft.
     December 2002. (Format: TXT=46853 bytes) (Status: INFORMATIONAL)

You can get these documents as:

http://www.ietf.org/rfc/rfc3450.txt
http://www.ietf.org/rfc/rfc3451.txt
http://www.ietf.org/rfc/rfc3452.txt
http://www.ietf.org/rfc/rfc3453.txt

Just a thought,

louie
wa3ymh

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