There are two fundamental perspectives concerning dependable communication in 5G systems: the end-to-end perspective of the communication services and the network perspective (see Figure 5.1-1).

The Communication Service in Figure 5.1-1 may be implemented as a logical communication link between a UE on one side and a network server on the other side, or between a UE on one side and a UE on the other side. In some cases, a local approach (e.g. network edge) is preferred for the communication service on the network side in order to reduce the latency, to increase communication service availability, or to keep sensitive data in a non-public network on the factory site. The Tables in Clauses 5.2 through 5.5 below provide sets of requirements where periodicity and determinism are critical to meeting cyber-physical control application needs in various vertical scenarios. While many use cases have similar KPI values, the important distinction is that in order to meet the needs of different verticals and different uses, the 5G system will need to be sufficiently flexible to allow deployment configurations that can meet the different sets of KPIs specific to each use. Communication service availability is considered an important service performance requirement for cyber-physical applications, especially for applications with deterministic traffic. The communication service availability depends on the latency and reliability (in the context of network layer packet transmissions, as defined in TS 22.261) of the logical communication link, as well as the survival time of the cyber-physical application (see Annex C.3 for further details on these relations). The communication service reliability requirements also depend on the operation characteristics of the corresponding cyber-physical applications. Typically, the communication services critical for the automation application also come with stringent communication service reliability requirements. Note that the communication service reliability requirement has no direct relationship with the communication service availability requirement. The "# of UEs" in the tables in clauses 5.2 to 5.5 is intended to give an indication of the UE density that would need to be served within a given service area. Clock synchronisation is needed in many "vertical" use cases. The requirements and tables in Clause 5.6 provide specific criteria for managing time sensitive communications in an industrial environment. High accuracy positioning is becoming essential for Factories of the Future. The reason for this is that tracking of mobile devices as well as mobile assets is becoming increasingly important in improving processes and increasing flexibility in industrial environments, Clause 5.7 provides positioning requirements for horizontal and vertical accuracy, availability, heading, latency and UE speed in an industrial use case scenario. An example of the relationship between reliability (in the context of network layer packet transmissions, as defined in TS 22.261), survival time and communication service availability of a logical communication link is illustrated in the following Table 5.1-1. This is done for a special case where packet errors are uncorrelated, which in many cases is an unrealistic assumption.

Periodic deterministic communication is periodic with stringent requirements on timeliness and availability of the communication service. A transmission occurs every transfer interval. A description of periodic deterministic communication can be found in Clause 4.3 and Clause 4.4. Additional information on the underlying use cases of the sets of requirements in Table 5.2-1 can be found in Annex A. Further information on characteristic parameters and influence quantities used in Table 5.2-1 can be found in Annex C. The 5G system shall be able to provide periodic deterministic communication with the service performance requirements for individual logical communication links that realise the communication services reported in Table 5.2-1. Process and asset monitoring using industrial wireless sensors is a special case of periodic deterministic communication with more relaxed requirements on timeliness and availability. These use cases put a slightly different set of requirements on the 5G system due to the specific constraints of industrial wireless sensors. These requirements for individual logical communication links are listed in Table 5.2-2 and additional information on the underlying use cases can be found in Annex A. Smart-Grid use case information can be found in Annex A.