SG15 Executive Summary

1 - 12 July 2019
ITU-T Study Group 15
Networks, Technologies and Infrastructures for Transport, Access and Home

Study Group 15 held its fourth meeting of the 2017-2020 study period in Geneva from 1-12 July 2019, attended by 281 delegates representing 37 countries. 
The meeting received 376 contributions and 401 TDs, a slight decrease from the previous meeting. The meeting observed the 12-day contribution deadline of revised Recommendation ITU-T A.1, and nearly all of the contributions to this meeting were submitted using Direct Document Posting (DDP).
SG15 approved one revised Recommendation, determined one new Recommendation and one Amendment, consented 35 texts (4 new Recommendations, 8 revised Recommendations, 13 Amendments, and 10 Corrigenda), and agreed one new and one revised Supplement.
SG15 authorized 12 interim face-to-face Rapporteur group meetings to be held prior to or within two months after the fifth SG15 plenary of the 2017-2020 study period, 10 virtual meetings, and generated 29 liaison statements. The fifth plenary meeting of SG15 in the 2017-2020 study period is scheduled 27 January-7 February 2020 in Geneva. This plenary will be preceded by ITU/IEEE 802.3/Nokia hosted interim meetings of the IEEE 802.1 and 802.3 Working Groups to be held the week of 20 January 2020, with a joint IEEE 802.1, 802.3, and ITU-T SG15 workshop on topics of common interest to be held on Saturday, 25 January 2020.
In fulfilling its lead study group responsibilities, SG15 revised the Access Network Transport (ANT) standards overview and work plan, the Home Network Transport (HNT) Standards Overview and Work Plan, and the Smart Grid standards overview and work plan. Due to lack of time, update of the Optical Transport Networks and Technologies (OTNT) standardization work plan was not completed during the meeting: this update will be completed by correspondence prior to the September meeting of TSAG.

Executive reports from WP Chairmen

WP1/15 – Transport aspects of access, home and smart grid networks
WP1 Chairman: Tom Starr; WP1 Vice-Chairman: Ian Horsley

Q1/15 updated the Access Network Transport (ANT) Standards Overview and Work Plan documents. The Home Network Transport (HNT) Standards Overview and Work Plan document was revised. The list of CIT activities related to the WP1/15 Recommendations was updated.

Q2/15 worked on Passive Optical Networks (PON).  A new Recommendation on high speed PON requirements and G.sup66 addressing PON for 5G fronthaul were prepared for Consent and Agreement.  Work was started on a new Recommendation for wavelength multiplexed point-to-multipoint 10-Gigabit-capable PON, and a revision on G.sup49.

Q4/15 worked on access via metallic conductors, focusing on G.fast, and the next-generation MGfast.  The G.fast Recommendation specifying an increased power spectrum was prepared for TAP approval, and the G.mgfast Recommendation specifying a frequency spectrum up to 424 MHz was prepared for Determination.

Q15/15 discussed plans for future standards activities for Smart Grid. 

Q18/15 worked on the G.hn family of Recommendations and Visible Light Communication (G.vlc).  A G.hn Amendment specifying higher frequency spectrum was prepared for Determination and G.hn Amendments and Corrigenda were prepared for Consent.  New projects started on the use of G.hn for IoT and UHDTV.

WP2/15 – Optical technologies and physical infrastructures
WP2 Chairman: Noriyuki Araki; WP2 Vice-Chairman: Pete Anslow

WP2 made good progress on the development of a number of Recommendations and produced one new and one revised Recommendation. WP2 produced two Liaisons and updated its work programme. WP2 also scheduled one interim meeting and a number of correspondence activities to progress the work.

WP2 agreed to prepare updated Question texts for WTSA-2020, including consideration of restructuring of WP2/15 by the next SG15 plenary meeting in January – February 2020. WP2 agreed a text for merging the terms of reference of Q6/15 and Q7/15 as a starting document for correspondence towards the creation of a single terms of reference document for the merged Questions 6 and 7 at the next SG15 plenary meeting.

Q5/15 worked on characteristics and test methods of optical fibres and cables and made progress on the revision of G.654 to specify the attenuation coefficient of G.654.E fibre considering the specification of wavelength bands, value of attenuation, cut-off wavelength and spectral attenuation modelling. Q5 also decided to add information into G.650.1 in order to clarify the wavelength dependence of G.654.E fibre. 

Q6/15 made progress on a revision of G.698.2 that considers extensions for 200 and 400Gbit/s application codes. Q6 also agreed to create new work items to add 25 Gbit/s optical interface specifications operating in the C-band over 20 km distances and a maximum of 20 channels to Recommendations G.698.1, G.698.2 and G.698.4 to address the needs for optical interface technologies for mobile optimized transport.

Q7/15 consented draft revised G.671 "Transmission characteristics of optical components and subsystems", which included a definition and some parameters for the specification of group delay.

Q8/15 made progress on the draft new Recommendation G.977.1 “Longitudinally compatible DWDM applications for repeatered optical fibre submarine cable systems" and its relevant Recommendations G.971 and G.972 that deal with general features and definitions of terms of optical submarine cable systems. Q8 also discussed the issues related to open cable characterization and commissioning.

Q16/15 consented new Recommendation L.208 (ex L.fdb) "Requirements for passive optical nodes: Fibre distribution boxes". Progress was also made on new Recommendations L.oha regarding optical fibre cables for in-home application. Q16 also agreed to start three new work items on revision of optical fibre cable Recommendations.

Q17/15 worked on maintenance and operation of optical fibre cable networks and made good progress on draft new Recommendation L.tifm, which deals with telecommunication infrastructure facility management. Also, Q17 considered a future new work item for optical cable identification for network maintenance.

WP3/15 – Transport network characteristics
WP3 Chairman: Malcolm Betts; WP3 Vice-Chairman: Glenn Parsons

·         In support of IMT‑2020/5G transport WP3/15 agreed a new supplement G.Sup.5gotn “Application of OTN to 5G transport". Four new work items on MTN equipment, protection, architecture and management were initiated.

·         Q13 continued its work on network synchronization to support the requirements of IMT‑2020/5G.

·         Q14/15 is continuing to work in cooperation with IEEE 802.1, IEEE 802.3, ONF, MEF, BBF, and IETF to provide consistent information models and YANG data models for Ethernet.

Q10/15 consented four documents: new G.8133 “Dual-Homing Protection for MPLS-TP Pseudowires", a G.8013/Y.1731 Corrigendum and a G.8021 Corrigendum both addressing alignment issues in the specification of the Ethernet Bandwidth Notification Message mechanism, as well as a G.8132 Corrigendum aligning the specification of MPLS-TP Shared Ring Protection with the latest in G.808.2. Work started on simplifying G.8021 via direct referencing of relevant mechanisms in IEEE Std 802.1Q and 802.1AX. To continue the repatriation of definitions from G.8001 and G.8101, Q10/15 agreed to revise G.8032 in February 2020 and G.8012, G.8012.1, G.8112, G.8113.1, and G.8113.2 in September 2020. Future work is also planned to revise G.8011 and G.8021 in September 2020.

Q11/15 focused much of the meeting on topics related to IMT2020/5G Transport networks, and approved two new work items related to IMT-2020/5G Transport targeted at metro networks, including transport of RAN traffic.  They are G.mtn-eqpt “Characteristics of MTN equipment functional blocks," and G.mtn-prot “MTN linear protection." A new supplement G.Sup.5gotn “Application of OTN to 5G transport" was agreed. This documents the use of existing OTN standards in IMT2020/5G transport network applications.  Q11/15 consented two amendments, one revision and one corrigendum, and agreed one new supplement.  The new work item, G.Sup.otnsec "OTN Security" will identify, which fields, in the existing OTN frame structure, may be encrypted or used to carry encryption control information. The method of encryption and control will not the addressed in this work. The corrigendum to G.709 “Interfaces for the optical transport network" (OTN) contains various corrections, including adding the missing payload type code for 50GBASE-R client signals, and terminology updates. 
The amendment to G.798 “Characteristics of optical transport network hierarchy equipment functional blocks" contains updates on various topics and minor editorial corrections, and the amendment to G.7041 “Generic Framing Procedure" provides clarifying updates associated with client mappings into GFP.  The revision to G.808.2 “Generic ring protection" includes updates that extend the document to cover generic aspects of MPLS-TP ring protection. Q11/15 plans two interim meetings in September 2019 and October 2019 to progress work on IMT2020/5G transport and other work items.

Q12/15 consented new Recommendation G.807 “Generic functional architecture of the optical media network" and a revision of G.872 “Architecture of the optical transport network (OTN)". This completes its work on the architecture for optical media networks that describe constructs used for propagating optical signals. Management aspects of media networks continued in joint sessions with Q14/15. Work on the update of G.8080 “Architecture for the automatically switched optical network" continued and this will result in a new Recommendation G.7703 that will supersede G.8080. This work will align the control components with the with control components in G.7701 and the SDN architectural approach in Recommendation G.7702. These Recommendations provide the foundation for SG15 to define the interface from the Transport Network to the 3GPP management system and, in particular, support 5G network slicing. This work will be progressed at a joint interim meeting with Q14 to be held in Seoul in October 2019.
A new work item was initiated to develop a new Recommendation G.mtn-arch “Functional architecture for metro transport network" to support the new IMT-2020/5G Transport-related work items targeted at metro networks, including transport of RAN traffic. This work will be progressed at a joint interim meeting with Q11 to be held in September 2019. The Optical Transport Networks & Technologies Standardization Work Plan (OTNT SWP) will be completed in a correspondence activity that will complete its work 6^th September, 2019.

Q13/15 continued the work on new requirements and solutions for time and frequency synchronization. Several Revisions and Amendments to the Q13 Recommendations have been consented at this meeting. G.8273.2 (Timing characteristics of telecom boundary clocks and telecom time slave clocks) has been revised to restructure the document and to include further specifications on the new time sync clocks.
G.8261 (Timing and synchronization aspects in packet networks) has been revised with the new specification for the network limits of a chain of enhanced synchronous equipment clocks. This performance would be more suitable to support the tighter synchronization requirements of the new generation of mobile networks. Amendment to G.8275 (Amd2) provides further details on the PTP profiles interworking function.
Q13/15 is also continuing the analysis of the synchronization for the fronthaul networks. The initial results have been included in Amd2 to G.8271.1. Further work is planned at the next meetings where inputs from liaisons from related groups (IEEE802.1 and CPRI Cooperation) is expected on this topic. Other documents that have been consented at this meeting are: G.8262.1 Amd1 (“Timing characteristics of an enhanced synchronous equipment slave clock"), G.8265.1 Amd1 (“Precision time protocol telecom profile for frequency synchronization"), G.8275.2 Amd3 (“Precision time protocol telecom profile for phase/time synchronization with partial timing support from the network") , G.8275.1 Amd3 (Precision time protocol telecom profile for phase/time synchronization with full timing support from the network) and G.8272.1 Amd2 (Timing characteristics of enhanced primary reference time clocks). Overall, 9 documents were consented. Significant progress has been made on the clock for partial timing support, G.8273.4. This was planned for consent at this meeting, but due to the significant updates made at this meeting it was agreed to postpone the consent at the next SG15 plenary. Amd1 to G.781 (Synchronization Function layer) was also planned for consent at this meeting, but further work is required to complete the analysis of the Quality Levels and extended TLV related to the new clocks. The plan is to consent it at the next SG15 Plenary. A Correspondence activity will be held before the next meeting in order to progress with this item. As related to G.8271, Important discussion was held on the need to mitigate interference in TDD networks operated by different operators. Liaison was sent to 3GPP on this topic. A joint meeting was held with Q2 on the topic of distribution of accurate time synchronization over PON to support the location services by means of the OTDOA method. Synchronization for G.mtn started to be discussed at this meeting and a new work item may be created in the future on this topic. Q13/15 plans to hold an interim meeting in October 2019.

Q14/15 consented two revised Recommendations, namely G.7710 on common management requirements for transport equipment and G.7712 on the architecture and specification of data communication network. Progress was made on the other fourteen active work items, including MCC component/function management requirements (G.7718) and information model (G.7719), equipment management for OTN (G.874 & G.875), Media (G.876), Ethernet (G.8051 & G.8052 series), and MPLS-TP (G.8151 & G.8152 series). Q14/15 also initiated two new work items, one on MTN management (G.mtn-mgmt) and the other one on data model of synchronization management (G.7721.1). Q14/15 plans to hold two interim meetings to progress the work. One on September 17-20, 2019 in Gothenburg, Sweden, hosted by Ericsson and another one jointly with Q12 on October 21-25, 2019 in Seoul, South Korea, hosted by ETRI. Q14/15 also plans to have bi-monthly virtual meetings on information and data modelling coordination with IEEE 802.1, IEEE 802.3, ONF, MEF, IETF, and BBF experts being invited. 

Decisions (ITU-T SG15, July 2019)
Approval

 WP1/15 – TAP Approval

Determination

WP1/15 - Determination

Consent

WP1/15 - Consent

WP2/15 - Consent

WP3/15 - Consent

Agreement

WP1/15 - Agreement

WP3/15 - Agreement

Recommendations proposed for deletion

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