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Re: TDMA - Reading the mail

At 11:36 PM -0600 12/20/00, Jon Ogden wrote:
>on 12/20/00 11:10 PM, Franklin Antonio at antonio@qualcomm.com wrote:
>> You're thinking about only one layer of the cake.
>> The idea is to have a protocol that controls the user terminal
>> behavior.  In a TDMA system, the user's terminal (or radio or whatever you
>> call it) would get assigned a time slot, and these assignments would be
>> made in a such a way that people don't fall on top of one
>> another.  Whatever the multiplexing scheme (CDMA, TDMA, XYZMA, etc), the
>> protocol would be a set of rules governing user terminal behavior designed
>> (among other things) to avoid transmissions which destroy one another.
>I understand what you are saying.  And in a one person to one person or
>point to point QSO this works great.  But in a point to multi-point
>environment where those "multi" points are not necessarily "well behaved",
>how can you do that?  If P51AA (North Korea for those who don't chase DX)
>says, "QRZ this is P51AA", then how will he know what time slot to listen on
>or how will the processor that determines who gets what time slot select who
>gets to make it through to the DX?  It's a far more complicated system than
>a one on one QSO or even a nicely controlled rountable where everyone takes
>their turns.  In a pileup you have hundreds and potentially thousands of
>stations all wanting to talk to the same station at the same time.  So how
>are you going to divvy that up?  What in the protocol will determine how the
>pileup works?

And as for stations not being "well behaved", what happens when people who
want to "get there first" start tweaking the protocol on their own
computers to their own advantage and start stepping on other time slots?

                 --... ...--  -.. .  -. ..... ...- -...
             Bruce Bostwick  N5VB  Austin, TX  Grid EM10DH
    ARRL / UT ARC / Austin ARC / Travis Co. ARES / W5YI Vol. Examiner
   http://ccwf.cc.utexas.edu/~lihan/  mailto:lihan@ccwf.cc.utexas.edu

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