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Abstract(s)
Broadcast networks that are characterised by having
different physical layers (PhL) demand some kind of
traffic adaptation between segments, in order to
avoid traffic congestion in linking devices. In many
LANs, this problem is solved by the actual linking
devices, which use some kind of flow control
mechanism that either tell transmitting stations to
pause (the transmission) or just discard frames. In
this paper, we address the case of token-passing
fieldbus networks operating in a broadcast fashion
and involving message transactions over
heterogeneous (wired or wireless) physical layers.
For the addressed case, real-time and reliability
requirements demand a different solution to the
traffic adaptation problem. Our approach relies on
the insertion of an appropriate idle time before a
station issuing a request frame. In this way, we
guarantee that the linking devices’ queues do not
increase in a way that the timeliness properties of the
overall system turn out to be unsuitable for the
targeted applications.
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Publisher
Instituto Politécnico do Porto. Instituto Superior de Engenharia do Porto. Universidade do Porto.