Geneva, 28 May 2010 Q13 Activities on Time Synchronization Jean-Loup Ferrant, Calnex, Q13 Rapporteur Stefano Ruffini Ericsson, Q13 Associated Rapporteur Joint ITU-T/IEEE Workshop on The Future of Ethernet Transport (Geneva, 28 May 2010)

Transport of frequency in Q13/15 In 2004, Q13 started working on transport of timing on PSN Interworking with TDM was required FDD was the mostly deployed mobile technology (only frequency sync required) Focus on Frequency synchronization 1- Transport of frequency in CES applications 2- Transport of frequency via SyncE First series of recommendations: G.8261, G.8262, G.8264 Initial discussion on time synchronization Transport of time on SyncE was also proposed, but 1588 was preferred 2

Transport of time in Q13/15 Transport of time became important with TDD and new applications (e.g. MBSFN) Q13 has chosen to focus on for the transport of time and frequency (NTP also briefly mentioned) Q13 worked on a first « telecom profile » (consent planned next week) Q13 workplan has been rearranged to align frequency and time recommendations 3

Structure of documents in Q13/15 4

5 Time-Phase Requirements ApplicationTime/Phase synchronization accuracy CDMA2000 (3GPP2 C.S0010-B, 3GPP2 C.S0002-C ) +/- 3 s with respect to UTC (during normal conditions) +/- 10 s of UTC (when the time sync reference is disconnected) W-CDMA (TDD mode) (3GPP TS ) 2.5 s phase difference between Base Stations. TD-SCDMA (TDD mode) (3GPP TR ) 3 s phase difference between Base Stations. LTE (TDD) (3GPP TS ) 3 s time difference between Base Stations (small cell). 10 s time difference between Base Stations (large cell). MBSFN (e.g. over LTE) < +/- 1 s with respect to a common time reference (continuous timescale) WiMAX (TDD mode) (IEEE ) Depend on several parameters. As an example +/-0.5 s and +/-5 s have been mentioned for a couple of typical cases. IP Network delay Monitoring Depends on the level of quality that shall be monitored. As an example +/- 100 s with respect to a common time reference (e.g. UTC) may be required. +/- 1 ms has also been mentioned. Billing and Alarms+/- 100 ms with respect to a common time reference (e.g. UTC)

Example in Wireless Application Phase Sync needed to Synchronize transmission from different base stations To optimize bandwidth usage and enhance network capacity In TDD mode uplink and downlink are separated in time LTE-TDD: 3 s time difference between Base Stations (small cell) phase synchronization requirement of 1.5 s between the master and the slave, according to ITU-T definitions (see G.8260) eNodeB +/- 3 s +/- 1.5 s 6

7 G.8271 The G.8271, Time and Phase synchronization aspects in packet networks First Q13 recommendation in the G.827x series; Draft already available Scope Overall performance objectives (see applications in previous slide) Methods to distribute phase synchronization and/or time synchronization (GNSS, Packet-based) Network Model Initial focus: Ethernet physical layer Detailed Network Limits are proposed to be included in a separate document (to be defined, e.g. G )

8 IEEE defines a profile as The set of allowed precision time Protocol (PTP) features applicable to a device The first purpose of a profile is to allow interworking between PTP master and slaves ITU-T Q13/15 agreed to define telecom profiles based on IEEE First profiles will address the transport of frequency Next profiles will address the transport of phase, time and frequency IEEE1588 Telecom Profiles

Frequency telecom profile First profile for end to end application, no support from intermediate nodes Frequency synchronization only PDV is not controlled in intermediate nodes Absolute delay is not an issue for frequency No asymmetry issue Network architecture as per G

Frequency distribution without timing support from the network (Unicast mode) Selected options Unicast is the selected mode Mix unicast and multicast mode is for further study and may be specified in future profiles Mapping:IEEE-2008 annexD (UDP over IPV4) One-way vs two ways Masters must support both Slaves may select one One-step vs two-steps Both allowed BMCA (best master clock algorithm) Definition of a specific BMCA by ITU-T 10

IEEE1588 Time Profile The distribution of accurate time/phase (e.g. < 1 microsecond) can be challenging without timing support from the network PDV impacting accurate frequency distribution Asymmetry due to different traffic load on forward and reverse direction Asymmetry due to particular transport technologies A network with timing support is generally required E.g. Boundary Clock in every node 11

Related Aspects Several aspects need to be addressed by Q13 Telecom Profile (e.g. PTP mapping, Unicast vs. Multicast, packet rate, BMC, etc.) Is the Transparent Clock allowed in Telecom ? Performance aspects (e.g. Clock characteristics, Holdover, etc.) Architecture (e.g. Sync Reference chain), redundancy Combination with SyncE Interworking with the access technologies 12

Additional Slides

Phase and Time Relevant Terms are defined in G.8260 Phase: significant events occur at the same instant Time: nodes get information about time and share a common timescale and related epoch Time Phase 14