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
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
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.