Table of Contents - G.8271.1/Y.1366.1 (2022) Amd. 3 (05/2025) -

1	Scope
2	References
3	Definitions
	3.1	Terms defined elsewhere
	3.2	Terms defined in this Recommendation
4	Abbreviations and acronyms
5	Conventions
6	Network reference model
7	Network limits
	7.1	Network limits at reference point A
	7.2	Network limits at reference point B
	7.3	Network limits at reference point C
	7.4	Network limit at reference point D
8	High-accuracy time transfer
	8.1	Introduction
	8.2	Performance requirements
Appendix I – Clock models for noise accumulation simulations
	I.1	T-BC models for noise accumulation simulations
	I.2	End-to-end TC models for noise accumulation simulations
Appendix II – Hypothetical reference models used to derive the network limits
	II.1	HRM composed of T-BCs
	II.2	HRM composed of T-BCs and T-TCs
Appendix III – Network limits considerations
	III.1	Measurement of network limits in deployment case 1
Appendix IV – Constant and dynamic time error and error accumulation
	IV.1	Introduction
	IV.2	Components of time error
	IV.3	Accumulation of time error in a chain of clocks
Appendix V – Example of design options
	V.1	Network limits
	V.2	Components of time error budgets
	V.3	Failure scenarios
	V.4	Time error budget allocation
	V.5	Operator options
	V.6	Further details
Appendix VI – Mitigation of time error due to synchronous Ethernet transients
Appendix VII – Maximum relative time error
	Page
Appendix VIII – Models for budgeting in a chain of microwave devices
Appendix IX – Models for budgeting in a chain of xPON or xDSL devices
Appendix X – Time error and transients due to PTP rearrangement
Appendix XI – Measurement of maximum relative time error limits
	XI.1	Measurement of maximum relative time error limits
	XI.2	Estimation of maximum absolute relative time error
Appendix XII – Examples of design options for fronthaul and clusters of base stations
	XII.1	Requirements
	XII.2	Fronthaul architectures for packet-based time/phase distribution
	XII.3	Failure scenarios
	XII.4	Synchronization options
	XII.5	Relative time error budget allocation
	XII.6	Network design guidelines and measurement of the network limits
Appendix XIII – High-accuracy time transfer
	XIII.1	Use cases
	XIII.2	Optical components and compensation
	XIII.3	External interfaces at HA-TT-Source and HA-TT-Sink:
	XIII.4	Reference chain:
Appendix XIV – Budgeting examples for applications connected via the IMT-2020/5G System
Bibliography