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Content for  TR 22.878  Word version:  18.2.0

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6  ConsiderationsWord‑p. 20

6.1  Potential security considerationsWord‑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 considerationsWord‑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).
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7  Consolidated potential requirements and KPIsWord‑p. 21

7.1  Consolidated potential requirementsWord‑p. 21

7.1.1  GeneralWord‑p. 21

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 7.1.1-2The 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]
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7.1.2  Monitoring and ReportingWord‑p. 22

CPR # Consolidated Potential Requirement Original PR # Comment
CPR 7.1.2-1The 5G system shall monitor for timing source failure.[PR 5.2.6.1-1]
CPR 7.1.2-2The 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 7.1.2-3The 5G system shall support a mechanism to determine the time uncertainty of the 5G time synchronization.[PR 5.4.6.1-1]
CPR 7.1.2-4The 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 7.1.2-5The 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 7.1.2-6The 5G system shall support mechanisms to monitor different time sources and adopt the most appropriate.[PR 5.4.6.1-2]
CPR 7.1.2-7The 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]
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7.1.3  Service ExposureWord‑p. 22

CPR # Consolidated Potential Requirement Original PR # Comment
CPR 7.1.3-1The 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]
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7.1.4Void

7.2  Consolidated potential KPIsWord‑p. 22

The 5G system shall be able to support a holdover capability with timing resiliency performance requirements defined in Table 7.2-1.
Use-case Holdover Time (note 3) Sync Target Sync accuracy Service area Mobility Remarks
Power grid (5G network)Up to 24 hourUTC (note 1)<250ns-1000ns [3], [9] (note2)< 20 km2lowWhen 5G System provides direct PTP Grandmaster capability to sub-stations
Power grid (time synchronization device)>5 sUTC (note 1)< 250ns-1000ns [3], [9] (note2)< 20 km2LowWhen 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.
 
Type of trading activity Maximum divergence from UTC Granularity of the timestamp (note 1)
Activity using high frequency algorithmic trading technique100μs≤ 1μs
Activity on voice trading systems1s≤ 1s
Activity on request for quote systems where the response requires human intervention or where the system does not allow algorithmic trading1s≤ 1s
Activity of concluding negotiated transactions1s≤ 1s
Any other trading activity1ms≤ 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.
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8  Conclusion and recommendationsWord‑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.
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$  Change historyWord‑p. 24


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