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These two planes can be seen in the diagram below. The time comes from a Primary Reference Time Clock, which is most implementations is a GNSS-based time receiver, often containing an integrated PTP GM function. The GM encodes the time reference into packet streams using PTP, and sends it over the packet network to the PTP Slave clock. To deliver time, a bi-directional transfer of packets is required between the GM and the slave. In addition, every switch and/or router contains a BC or TC function to help remove the PDV generated by the network. The stability of each of these functions is further enhanced by the frequency plane based on SyncE.
| Concepts / Overview | CX6001 | Testing a T-BC to ITU-T G.8273.2 |
|---|---|---|
| CX6002 | Measuring Time Error Transfer of G.8273.2 T-BCs | |
| General Information | G.8260 | Definitions and Terminology for Synchronisation in Packet Networks |
| G.8275 | Architecture and requirements for packet-based time and phase distribution | |
| Clock Specifications | G.811 | Primary Reference Clock (PRC) Specification |
| G.8262 | Ethernet Equipment Clock (EEC) Specification | |
| G.8272 | Primary Reference Time Clock (PRTC) Specification (Class A) | |
| G.8273.1 | PTP Telecom Grandmaster (T-GM) Specification (under development) | |
| G.8273.2 | PTP Telecom Boundary Clock (T-BC) and Time Slave Clock (T-TSC) Specification (Class A, B) | |
| G.8273.3 | PTP Telecom Transparent Clock (T-TC) Specification (Class A, B) | |
| Network Specifications | G.8261 | SyncE Network Limits (clause 9.2.1) |
| G.8271.1 | PTP Network Limits | |
| Protocol Specifications | G.8264 | Ethernet Synchronisation Messaging Channel (ESMC) (clause 11) |
| G.8275.1 | PTP Telecom Profile for Time (Full Timing Support) | |
| IEEE1588 | Precision Time Protocol | |
| Test Guide | CX5008 | T-BC Time Error - Testing Boundary Clocks to ITU-T G.8273.2 using Paragon-X |
| CX3003 | PTP Time Error for T-BC: Testing Boundary Clocks to ITU-T G.8273.2 using Paragon-100G | |
| CX5020 | T-TSC Time Error: Testing Time Slave Clocks to ITU-T G.8273.2 using Paragon-X | |
| CX5021 | T-TC Time Error: Testing Transparent Clocks to ITU-T G.8273.2 using Paragon-X |
Method 2b: GNSS Receivers with PTP as a backup
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| Concepts / Overview | ||
|---|---|---|
| General Information | G.8260 | Definitions and Terminology for Synchronisation in Packet Networks |
| G.8275 | Architecture and requirements for packet-based time and phase distribution | |
| Clock Specifications | G.8272 | Primary Reference Time Clock (PRTC) Specification (Class A) |
| G.8273.1 | PTP Telecom Grandmaster (T-GM) Specification (under development) | |
| G.8273.4 | Assisted Partial Timing Support Clock (T-TSC-A) Specification (under development) | |
| Network Specifications | G.8271.2 | Network Limits |
| Protocol Specifications | G.8275.2 | PTP Telecom Profile for Time (Partial Timing Support) |
| IEEE1588 | Precision Time Protocol | |
| Test Guide | CX4005 | Sentinel Field Test Plan for TDD-LTE/LTE-A Synchronisation in Systems using Assisted Partial Timing Support and Partial Timing Support |
Method 2c: PTP
The third method is to use the packet-based protocol, PTP, as the sole method to distribute time and phase out to the basestations. This will work over small existing networks of switches and routers without having to upgrade them to support PTP and SyncE. For many mobile operators, this is required as they have to use third-party access networks that haven’t necessarily deployed SyncE. This is known as “partial timing support” (PTS), indicating that not all of the switches and routers may have PTP or SyncE support.
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| Concepts / Overview | ||
|---|---|---|
| General Information | G.8260 | Definitions and Terminology for Synchronisation in Packet Networks |
| G.8275 | Architecture and requirements for packet-based time and phase distribution | |
| Clock Specifications | G.8272 | Primary Reference Time Clock (PRTC) Specification (Class A) |
| G.8273.1 | PTP Telecom Grandmaster (T-GM) Specification (under development) | |
| G.8273.4 | Assisted Partial Timing Support Clock (T-TSC-A) Specification (under development) | |
| Network Specifications | G.8271.2 | Network Limits |
| Protocol Specifications | G.8275.2 | PTP Telecom Profile for Time (Partial Timing Support) |
| IEEE1588 | Precision Time Protocol | |
| Test Guide | CX4005 | Sentinel Field Test Plan for TDD-LTE/LTE-A Synchronisation in Systems using Assisted Partial Timing Support and Partial Timing Support |