Re: NEW TOPIC! : What about an AX.25 Bridge?

[Phil Karn <karn@unix.ka9q.ampr.org>]

>Hmmm, I don't understand your qualms with repeaters. How else are we
>going to get a working network at 56kbps with the GRAPES modem? We

I'm not saying "stop building repeaters". With present amateur
technology, I don't see much alternative.

But I like to take a much longer view. The big problem with repeaters
is that they just don't scale. It's easy to put up a single repeater
that covers a big town, but what do you do when it runs out of gas?
You're tying up that chunk of spectrum over quite an area.

I see a network of randomly placed spread spectrum packet radios with
automatic transmitter power control all sharing the same
spectrum. Each radio discovers its neighbors, measures how much RF
power is required to reach each one, and builds routing tables that
minimize the total amount of RF energy -- as opposed to the number of
hops -- used to reach each destination.

Forward error correction coding reduces average transmitter power even
more, improving interference resistance and reducing interference to
others.

As you add more radios, the average inter-node distance goes down.  So
does the average transmitter power, which icreases the total capacity
of the network to help compensate for the extra load. It's a network
that could be grown far beyond what's possible with conventional
repeating.

Phil