ITU-T G Suppl. 66 (09/2020)

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 Overview of 5G wireless fronthaul architecture
6.1 Evolution of wireless transport architecture from 4G to 5G
6.2 Functional split architecture
6.2.1 Conventional fronthaul in 4G wireless network
6.2.2 New functional split options in 5G wireless network
6.3 Deployment scenarios
7 Requirements for 5G fronthaul transport
7.1 RAN and service level background
7.2 Transport bandwidth requirements
7.3 Latency requirements
7.4 Synchronization requirements
7.5 OAM functions
7.5.1 OAM requirements from the wireless perspective
7.5.2 OAM requirements from the transport perspective
8 PON architecture for 5G fronthaul transport
9 Practical PON system solutions
9.1 Legacy PON with WDM overlay
9.1.1 Low layer split
9.1.2 High layer split
9.1.3 Mixed high layer and low layer split
9.2 Dedicated PON for wireless services
9.2.1 Low layer split
9.2.2 High layer split
9.2.3 Mixed high layer and low layer split
9.3 PON system implementation examples
9.3.1 TDM-PON with low latency bandwidth assignment
9.3.1.1 Differentiated service classes
9.3.1.2 Optical-mobile cooperative DBA (CO DBA)
9.3.1.2.1 CO DBA mechanism example for mobile fronthaul
9.3.1.2.2 CO DBA architecture examples for mobile fronthaul
9.3.1.2.3 CO DBA functional roles
9.3.1.2.4 CO DBA with O-RAN cooperative transport interface (CTI)
9.3.1.3 Quiet window elimination using a dedicated activation wavelength (DAW)
9.3.2 TWDM-PON for low latency services
9.3.3 WDM-PON for low latency services
10 PON physical layer requirements
10.1 Capacity
10.1.1 Throughput requirements for the F1 interface
10.1.1.1 Dimensioning of aggregate F1 interface data rates – Example 1
10.1.1.2 Dimensioning of aggregate F1 interface data rates – Example 2
10.1.2 Throughput requirements for low layer split
10.2 Fibre reach and split ratio
10.3 Optical spectrum
11 PON system requirements
11.1 Requirements set by the wireless networks
11.2 Requirements to coordinate the PON-wireless interface
11.3 PON internal requirements not visible to the wireless network
11.3.1 Implementations in PON to support OAM functions

Supplement 66 to ITU‑T G-series Recommendations enumerates the various requirements arising from 5G wireless systems, concentrating on the fronthaul portion of the network and considers how they compare with current and future optical access transport systems.

This Supplement considers the requirements for 5G wireless fronthaul specifically in the setting of
optical access networks.