Physical layer of a novel broadband low-level fieldbus with discrete multitone

Packet-based time-critical medium access for a process-oriented deterministic bus system

“…additional error correction using 20 symbols per up-or downlink slot [3]. This 20-bit-word can be understood as the basic data unit for the MAC-layer.…”

“…As described in [3], the properties of the physical medium, typically an arbitrary network of unshielded 2-wire-cables, are frequency-selective and dependent on the location in the network. It can be assumed that not all carriers in a given frequency range are usable for communication between the master and certain slaves because of the frequency selectivity and additional disturbances from external interferers.…”

“…For a new generation of a successful, well-established field bus system a novel, packetbased concept with parallel access to many participants was examined. The approach uses a point-to-multipoint concept with a dedicated discrete multitone (DMT) modulation scheme and defined down-and upstream cycles [3]. To satisfy the demanding timing requirements of real-time systems, the sensor-/actuator nodes use different carrier frequencies to communicate in parallel with the system master.…”

“…To satisfy the demanding timing requirements of real-time systems, the sensor-/actuator nodes use different carrier frequencies to communicate in parallel with the system master. Of course, the modulation effort is higher than in serial systems, but on the other side we reach a new degree of scalability, flexibility and disturbance immunity in arbitrary network topologies [3].…”