is uniquely identified by the net- work devices. End devices: These are the source and destination of the time-sensitive networking flows. The end devices are running an application that requires deterministic communication. Bridges: Also referred as Ethernet switches, these are special bridges capable of transmitting the Ethernet frames of a time-sensitive networking flow on schedule and receiving Ethernet frames of a time-sensitive networking flow according to a schedule. Central network controller: A proxy for the network comprising the time-sensitive networking bridges and their interconnections, and the control applications that require deterministic communication. The central network controller defines the schedule based on which all time-sensitive networking frames are transmitted. Centralized user configuration: An application that communicates with the central network controller and the end devices and represents the control applications and the end devices. The central- ized user configuration makes requests to the central network controller for deterministic communication with specific requirements for the flows. 66 Chapter 1 I/Q and C&M data can be transported independently. The round-trip delay for I/Q is limited to 200 us and maximum frame error rate is 10-7. The C&M data has more relaxed time budgets. Synchronization signals represent an interesting aspect, with a wide range of requirements driven by wireless standards such as 3GPP LTE/NR. Four classes have been defined [75]: 1. Class A + : Strictest class with time error budget of 12.5 ns (one way) for applications such as MIMO and transmit diversity. Class A: Time error budget up to 45 ns for applications including contiguous intra- cell CA. Class B: Budgets up to 110 ns for non-contiguous intra-cell CA. 4. Class C: The least strict class delivers a budget up to 1.5 us from the primary reference time clock40 to the end application clock recovery output. The above synchronization requirements, which continue to become more stringent with the new r