At 09:36 AM 1/18/01 -0800, [EMAIL PROTECTED] wrote:
>Jaap-Henk Hoepman, <[EMAIL PROTECTED]>, writes:
>> In the `traditional' DC Net, how is absence of a message detected?
>> If this is a seperately distinguishable outcome of a round, each round may
>> return three outcomes: `0', `1' and `none'. To represent these quantum
>> mechanically, you need at least a 3-state quantum system (to make the
>> perfectly distinguishable).
>Much of the work on higher level protocols would apply to the SC Net as
>well as to the DC Net so a two state system should be adequate.  However
>if the two state system can be established to be secure, perhaps a three
>state system could be developed and could avoid the need for higher level
>protocols to some degree.

No need for a three-state system.  
You need at least a link-layer protocol anyway, so you can maintain
framing on your bytes, just like you do with any bit serial device.
You could recycle HDLC or SDLC or some async protocol.
The usual versions are either to use a flag byte indicating the start
of a transmission, or else to use start&stop bits,
e.g. transmit all 0s when there's no data, then a 1 bit to indicate
that there's data following.  It doesn't take much overhead.
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