Content for TR 22.878 Word version: 18.2.0

6.1 Potential security considerations 6.2 Potential charging considerations 7.1 Consolidated potential requirements 7.2 Consolidated potential KPIs

6 Considerations p. 20

6.1 Potential security considerations p. 20

[CPR 6.1-1]

The 5G system shall support a mechanism to verify authorization of a 3rd party application to use 5G timing resiliency.

[CPR 6.1-2]

The 5G system shall support a mechanism to monitor and verify authenticity of the timing source, where supported by the time source.

[CPR 6.1-3]

The 5G system should verify the availability of the external time sources.

6.2 Potential charging considerations p. 20

[CPR 6.2-1]

The 5G system shall be able to collect charging information based on the timing source (e.g., the source in use, start and stop of source usage).

[CPR 6.2-2]

The 5G system shall be able to collect charging information per UE for use of a timing source (e.g., start/stop time and source used by a UE, timing source used by UE, holdover capability).

[CPR 6.2-3]

The 5G system shall be able to collect charging information on 5G system timing resiliency (e.g., resiliency KPIs, holdover capability, number of UEs using a certain timing source).

[CPR 6.2-4]

The 5G system shall be able to collect charging information per application, including 3rd party application (e.g., timing resiliency KPIs, holdover capability, number of UEs using a certain timing source).

7 Consolidated potential requirements and KPIs p. 21

7.1 Consolidated potential requirements p. 21

7.1.1 General p. 21

Table 7.1.1-1: General Consolidated Requirements

CPR #	Consolidated Potential Requirement	Original PR #	Comment
CPR 7.1.1-1	The 5G system shall be able to receive accurate timing signals from one or more independent timing source(s), which can offer a timing alternative to GNSS, e.g. TBS/MBS [7] [8]], Sync over Fiber [7].	[PR 5.1.6-1]
CPR 7.1.1-2	The 5G system shall be able to maintain accurate time synchronization as appropriate for the supported applications in the event of degradation or loss of GNSS timing signals.	[PR 5.1.6-3]

7.1.2 Monitoring and Reporting p. 22

Table 7.1.2-1: Monitoring and Reporting Consolidated Requirements

CPR #	Consolidated Potential Requirement	Original PR #
CPR 7.1.2-1	The 5G system shall monitor for timing source failure.	[PR 5.2.6.1-1]
CPR 7.1.2-2	The 5G system shall be able to detect when reference timing signals (e.g., from GNSS or other timing source) are no longer viable for network time synchronization.	[PR 5.1.6-2]
CPR 7.1.2-3	The 5G system shall support a mechanism to determine the time uncertainty of the 5G time synchronization.	[PR 5.4.6.1-1]
CPR 7.1.2-4	The 5G system shall be able to indicate to devices (e.g., UEs, applications) that they need to use an alternate time source (e.g., to 5G system internal holdover capability, atomic clock, Sync over Fiber, TBS, GNSS), taking into account the holdover capability of the devices.	[PR 5.2.6.1-2]
CPR 7.1.2-5	The 5G system shall be able to detect when a timing source fails or is restored for network time synchronization.	[PR 5.2.6.1-4]
CPR 7.1.2-6	The 5G system shall support mechanisms to monitor different time sources and adopt the most appropriate.	[PR 5.4.6.1-2]
CPR 7.1.2-7	The 5G system shall support a mechanism to report timing resiliency information (e.g., divergence from UTC, time uncertainty) to 3rd party applications.	[PR 5.4.6.1-3]

7.1.3 Service Exposure p. 22

Table 7.1.3-1: Service Exposure Consolidated Requirements

CPR #	Consolidated Potential Requirement	Original PR #	Comment
CPR 7.1.3-1	The 5G system shall support a mechanism for a 3rd party application to request resilient timing with specific KPIs (e.g., accuracy, interval, coverage area).	[PR 5.3.6-3]

7.1.4 Void

7.2 Consolidated potential KPIs p. 22

The 5G system shall be able to support a holdover capability with timing resiliency performance requirements defined in Table 7.2-1.

Table 7.2-1: Timing resiliency performance requirements for 5G System

Use-case	Holdover Time (note 3)	Sync Target	Sync accuracy	Service area	Mobility	Remarks
Power grid (5G network)	Up to 24 hour	UTC (note 1)	<250ns-1000ns [3], [9] (note2)	< 20 km2	low	When 5G System provides direct PTP Grandmaster capability to sub-stations
Power grid (time synchronization device)	>5 s	UTC (note 1)	< 250ns-1000ns [3], [9] (note2)	< 20 km2	Low	When 5G sync modem is integrated into PTP grandmaster solution (with 24h holdover capability) at sub-stations)
NOTE 1: A different synchronization target is acceptable as long as the offset is preconfigured when an alternatively sourced time differs from GNSS. In this case, a 5G end device shall provide PPS output which can be used for measuring the difference. NOTE 2: Use case [New] in [9] illustrates the different accuracy measurements based on different configurations needed to support the underlying requirements from IEC [3]. The range is between 250 ns and 1000 ns. The actual requirement depends on the specific deployment. NOTE 3: This requirement will vary based on deployment options.

Table 7.2-2: Level of accuracy for members or participants of a trading venue [13, 14]

Type of trading activity	Maximum divergence from UTC	Granularity of the timestamp (note 1)
Activity using high frequency algorithmic trading technique	100μs	≤ 1μs
Activity on voice trading systems	1s	≤ 1s
Activity on request for quote systems where the response requires human intervention or where the system does not allow algorithmic trading	1s	≤ 1s
Activity of concluding negotiated transactions	1s	≤ 1s
Any other trading activity	1ms	≤ 1ms
NOTE 1: Only relevant for the case where the time synchronization assists in configuring the required granularity for the timestamp (for direct use), otherwise it will be configured separately as part of the financial transaction timestamp process.

8 Conclusion and recommendations p. 23

The study has analysed a number of use cases supporting 5G timing resiliency for various vertical uses. The use cases demonstrate the anticipated enhancements in the 5G system in order to

use the 5G system in concert with other timing technologies as a resilient timing source in complement/back-up/alternate to GNSS, and
to enable time synchronization resiliency is available if GNSS or other timing sources are compromised.

The resulting considerations on security and charging have been consolidated in clause 6 and the potential requirements and KPIs have been consolidated in clause 7 of the TR. The content of clause 6 and clause 7 should be considered as the basis of normative Rel-18 requirements to support 5G timing resiliency.