3. Standards aimed at delivering time and phase to better than 130ns
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Main use case: 5G cellular mobile radio using co-operative processing techniques
In 5G networks the number of distributed small cells and remote radio heads is expected to be much higher to deliver the traffic capacity and density forecast. It is expected that co-operative radio techniques will be deployed to deliver the high data rates required, such as Co-ordinated Multipoint (CoMP) and inter-site Carrier Aggregation (CA). These techniques require the participating small cells and radio units to be synchronised very accurately. Depending on the technique, this could require an accuracy of better than 130ns.
Method 3a: PTP and SyncE, with a BC or TC at every node in the network
In order to deliver this very high accuracy, the full timing support method is used, with PTP and SyncE support in every switch and/or router along the synchronisation path (method 2a). A range of new clock specifications has been developed to improve the synchronisation accuracy at the end node.
For example, class C and class D boundary clocks have been added to G.8273.2, along with an enhanced EEC specification (G.8262.1). Similarly, there is a new enhanced PRTC specification (G.8272.1), and Class B PRTC specification (G.8272) has also been defined. The network limits associated with these enhanced clock specifications are still under development.
| 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.811.1 | Enhanced Primary Reference Clock (ePRC) Specification |
| G.8262.1 | Enhanced Ethernet Equipment Clock (eEEC) Specification | |
| G.8272 | Primary Reference Time Clock (PRTC) Specification (Class B) | |
| G.8272.1 | Enhanced Primary Reference Time Clock (ePRTC) Specification | |
| 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 C, D) | |
| G.8273.3 | PTP Telecom Transparent Clock (T-TC) Specification (Class C, D - under development) | |
| Network Specifications | G.8261 | Enhanced SyncE Network Limits (under development) |
| G.8271.1 | Enhanced PTP Network Limits (under development) | |
| 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 |