1588v2 modules of time synchronization with frequency layer support draftsutictoc1588v2timesyncmodul

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1588v2 modules of time synchronization with
frequency layer supportdraft-su-tictoc-1588v2-ti
me-sync-modules-00

• IETF 75th, Stockholm
• TICTOC WG
• su.fei_at_zte.com.cn

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Motivation

• 1588v2 has being deployed in TD-SCDMA backhaul
  network for decreasing the use of GPS
• Profiles of 1588v2 system in this application
  should be outlined in appropriate document
• ITU-T Q13/15 also has intension to specify the
  1588v2 telecom profiles for time/phase sync with
  frequency sync support (architecture
  preliminarily )

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Structure of document

• Introduction
• Scenario of 1588v2 time/phase sync for TD-SCDMA
  backhaul
• Time/phase server
• PTP client
• Timestamping process

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Introduction

• Time/phase requirement of TD-SCDMA has been
  recognized both in IETF TICTOC (draft-ietf-tictoc-
  requirements-00.txt) and ITU-T Q13/15 (G.8266)
• To endure stringent time/phase alignment between
  NodeB and RNC (/-1.5 us) over a long span metro
  network (e.g. 30 nodes maximum between some
  NodeBs and RNC), the time/phase sync is primarily
  considered to be coupled with frequency sync by
  operators

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Scenario of 1588v2 time/phase sync for TD-SCDMA
backhaul

• The time/phase server synchronized by GPS and/or
  Compass is placed near RNC
• PTP client is implemented in NodeB or NEs
  connected to NodeB
• PTP client and all NEs on the time/phase
  distribution path has the same frequency
  traceability to PTP server or higher frequency
  reference through SyncE links

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Time/phase server

• Synchronized by other external time/phase source
  using varied time/phase interface (e.g. 1PPSToD,
  PTP, DCLS, IRIG). Support input antenna/cable
  delay compensation
• Provide multiple time/phase output interfaces
  (inter/intra office) and capacity of dealing with
  certain amount of PTP clients
• Frequency input for time/phase holdover and
  frequency output interfaces (e.g. 2Mbits and/or
  SyncE)
• Sync performance monitoring and management

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PTP Client

• Frequency reference selection and locking for
  measurement of local time/phase
• Time/phase calibration based on offset
  calculation carried out by PTP protocol

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Timestamping process

• Distributed timestamping scheme can be used to
  minimize the system delay of PTP event messages
• PTP event message is timestamped by edge
  timestamping unit close to physical interface
• The transient delay of PTP message directly
  forwarded (without being processed by PTP
  protocol unit) can be accurately measured and
  compensated

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Timestamping process

• Example of timestamping operations using delay
  request-response mode
• Ingress PHY interface

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Timestamping process

• Egress PHY interface

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Whats next

• Improve contents of the document based on
  discussions or comments from those who have
  interests
• Consider other aspects of the application e.g.
  sync protection, management, security etc.
• Merged with existing I-D draft-su-tictoc-time-syn
  c-mode-01 which has the consistency with this
  one