Supplement 65 to ITU-T G-series Recommendations (10/2018)  Simulations of transport of time over packet networks
Summary
History
FOREWORD
Table of Contents
1 Scope
2 References
3 Definitions
     3.1 Terms defined elsewhere
     3.2 Terms defined in this Supplement
4 Abbreviations and acronyms
5 Conventions
6 Introduction
7 Description of scenarios
8 Mathematical description of a synchronous Ethernet reference chain and simulation models
     8.1 Time-domain mathematical model, simulator, and simulation results
          8.1.1 Introduction
          8.1.2 Initial EEC/SEC, SSU, and PRC wander generation models
               8.1.2.1 EEC/SEC wander generation models
               8.1.2.2 SSU wander generation models
               8.1.2.3 PRC wander generation models
          8.1.3 Wander accumulation model and initial simulation results
               8.1.3.1 Simulation model
               8.1.3.2 Simulation cases and inputs
               8.1.3.3 Simulation results
          8.1.4 ETSI Option 1 wander generation models and corresponding wander accumulation simulations and results
               8.1.4.1 ETSI Option 1 wander generation models
               8.1.4.2 Option 1 wander accumulation over the synchronization reference chain using ETSI Option 1 wander generation models
     8.2 Frequency-domain mathematical model, simulator, and simulation results
          8.2.1 Introduction
          8.2.2 Model for TDEV of wander accumulation
               8.2.2.1 The premise
               8.2.2.2 The analytical modelling approach
               8.2.2.3 Relationship between TVAR and power spectrum
               8.2.2.4 Recursion relationship for power spectrum and TVAR of clock noise
          8.2.3 Filter frequency response
          8.2.4 Model for MTIE of wander accumulation
               8.2.4.1 Relation between TIErms and MTIE upper limit
               8.2.4.2 Relationship between TDEV and MTIE upper limit
               8.2.4.3 Verification of MTIE upper limit by computer simulation
               8.2.4.4 Conclusions
          8.2.5 Wander accumulation results for frequency domain model
               8.2.5.1 Wander accumulation TDEV results for frequency domain model
               8.2.5.2 Wander accumulation MTIE results for frequency domain model
9 Time-domain mathematical description of a telecom boundary clock (T-BC) and a telecom time slave clock (T-TSC) with SyncE assist for frequency transport, and associated transfer functions and frequency responses
     9.1 Introduction
          9.1.1 High-level model for a telecom boundary clock
          9.1.2 Effect of delay request/response or peer delay turnaround time on delay measurement and boundary clock performance
               9.1.2.1 Description of delay request/response and peer-to-peer delay mechanisms
               9.1.2.2 Description of errors in the measurement of mean propagation delay
                    9.1.2.2.1 Type A errors
                    9.1.2.2.2 Type B errors
          9.1.3 Effect of sojourn time on boundary clock performance
               9.1.3.1 Description of processing performed by a T-BC in transporting time
               9.1.3.2 Description of the errors in the measurement of sojourn time
                    9.1.3.2.1 Type A errors
                    9.1.3.2.2 Type B errors
          9.1.4 Use of interpolation when sampling noise in simulations
     9.2 T-BC and T-TSC model that neglects SyncE noise generation
          9.2.1 Model A, time-stamping relative to the corrected time
          9.2.2 Model B, time-stamping relative to the uncorrected time
          9.2.3 Comparison of model A and model B transfer functions
          9.2.4 Frequency response examples
               9.2.4.1 Example 1 – model B with no filtering in the 'Time Measurement, possibly with filtering' and 'Counter and Time offset correction' blocks (GB = KB = MB = 1)
               9.2.4.2 Example 2 – model A with no filtering in the 'Time Measurement, possibly with filtering' and 'Counter and Time offset correction' blocks (GA = KA = 1)
               9.2.4.3 Example 3 – model B frequency response for case of approximate second-order signal transfer function with 20 dB/decade roll-off
     9.3 T-BC and T-TSC model that includes SyncE noise generation
          9.3.1 Special case of model A – second-order PLL example
          9.3.2 Noise generation in KA(s) in model A
          9.3.3 Noise generation in model B
          9.3.4 Special case of model B where MB(s) = GB(s) = 1 and KB(s) is a second-order PLL
          9.3.5 Comparison of models A and B for the case where MB(s) = 1 in model B and noise generation is included in both Models
10 Frequency domain mathematical description of a T-BC and a T-TSC
     10.1 Introduction
     10.2 Model for a T-BC or T-TSC with no filtering
          10.2.1 Time-stamping granularity noise
          10.2.2 Slave side errors
          10.2.2 Master side errors
          10.2.3 Modified Figure II.1 of [ITU-T G.8271] (no filtering)
     10.3 Model for a T-BC or T-TSC with filtering
     10.4 Modelling of time error accumulation in a T-BC and T-TSC and a chain of clocks
          10.4.1 The model
          10.4.2 Effective maximum value of time error
          10.4.3 Effective mean value of time error
          10.4.4 Effective variance of time error
          10.4.5 Contribution of time-stamping granularity to the time error
11 Description of time-domain simulator and implementation of models
     11.1 Introduction
     11.2 Overall description of simulator
          11.2.1 Simulator (ideal) time corresponding to local clock time
     11.3 Modelling of noise generation in the simulator PLL filter
     11.4 Modelling of timestamping relative to the corrected clock, and the delay request/response mechanism, in the simulator
12 Steady-state time domain simulation cases and results
     12.1 Simulation results for HRM3 cases based on single replications of simulations
          12.1.1 Description of simulation cases
          12.1.2 Simulation results
               12.1.2.1 Results for cases without T-BC filtering
               12.1.2.2 Results for cases with T-BC filtering
               12.1.2.3 Comparison of results for 0.1 dB and 0.2 dB gain peaking
               12.1.2.4 Summary and conclusions for HRM3 single-replication simulation cases
     12.2 Simulation results for HRM3 cases based on single replications of simulations
          12.2.1 Description of simulation cases
          12.2.2 Simulation results
          12.2.3 Summary and conclusions for HRM3 multiple-replication simulation cases
     12.3 Simulation results for HRM3 cases with timestamping relative to the corrected or uncorrected clock in PTP, based on single replications of simulations
          12.3.1 Introduction
          12.3.2 Description of simulation cases
          12.3.3 Simulation results
               12.3.3.1 Results for time history of time error at selected BCs for selected cases/sub-cases
                    12.3.3.1.1 Results for case 1
                    12.3.3.1.2 Results for case 2
                    12.3.3.1.3 Results for case 3
          12.3.4 Summary and conclusions for HRM3 cases with timestamping relative to the corrected or uncorrected clock in PTP
     12.4 Simulation results for HRM2 cases based on single and multiple replications of simulations
          12.4.1 Review of HRM2
          12.4.2 Description of simulation cases
          12.4.3 Simulation results for single replications of cases
               12.4.3.1 Results for cases without T-BC filtering
               12.4.3.2 Results for cases with T-BC filtering
               12.4.3.3 Simulation results for multiple replications of selected cases of clause 12.4.3.2
                    12.4.3.3.1 Comparison of sub-cases with no T-BC filtering and no endpoint filtering
                    12.4.3.3.2 Results for simulation cases corresponding to cases (a) to (h) of clause 12.1
                    12.4.3.3.3 Summary and conclusions for HRM2 simulation cases
Appendix I  Sub-Nyquist artefacts and sampling moiré effects when measuring  PTP to PTP and PTP to 1 PPS noise transfer
     I.1 Introduction
     I.2 Description of sub-Nyquist artefacts and examples
     I.3 Discussion
Bibliography