By Wanshi Chen, 3GPP TSG RAN Chair
TSG RAN#95-e was a hectic and critical meeting, held electronically from March 17th to March 23rd, with 5 working days spread across two weeks and a 48-hour quiet period imposed during the weekend.
Besides the usual Plenary business of RAN WG issues, ITU related issues, meeting planning, etc., RAN#95-e notched up some major achievements:
- The successful functional freeze for RAN Rel-17,
- Approval of RAN4-led Rel-18 package,
- Note: RAN1/2/3-led Rel-18 package was approved in December during RAN#94-e.
- Successful completion of the 5Gi merger (from RAN perspective), and
- Endorsed RAN meeting planning for 2022
What follows is a detailed RAN#95-e summary of the key areas covered by the meeting.
RAN#95-e addressed the following administrative aspects:
Inclusive language: In 3GPP, using inclusive language for specifications is taken seriously. A large amount of effort was spent in previous RAN plenary meetings. Such effort continued in RAN#95-e, resulting in the approval of a set of Rel-17 CRs, including RP-220313 on the removal of the "black List" term and those derived from that term (CR to TS 44.318), RP-220314 to change “white list” to ‘allowed list’ (CR to TS 45.008), RP-220238 to take out “master, slave” (CRs for NR from RAN3), RP-220239 to change “black cells” to “excluded cells” (CR for E-UTRAN from RAN3), and RP-220506 for a variety of those terms (CRs for E-UTRAN and NR from RAN2). The detailed email discussion summary can be found in RP-220878.
WID names and acronyms: In response to ETSI MCC contribution RP-220065 titled “Guidelines on WIDs names and acronyms”, RAN#95-e discussed and endorsed feedback as summarized in RP-220882. RAN plans to work with the guidelines, taking into account several aspects summarized in Section 5 of RP-220882.
UTRAN Specs in Rel-17: One involved discussion in RAN#95-e was whether and how to automatically upgrade UTRAN specs (25 and some 34 specification series) from Rel-16 to Rel-17. After lengthy discussion, RAN#95-e concluded the following (see more details in RP-220906):
- 25 series : Do not upgrade any 25-series specifications to Rel-17.
- 34 series : Do not upgrade RAN4 specs TS 34.124 & 34.926, and RAN2 spec TS 34.109.
However, since such an issue requires coordination across TSGs, a Liaison Statement (LS) was sent to TSG SA and TSG CT (see RP-221015). The LS was carefully discussed in a subsequent joint TSG session, which resulted in the following conclusion:
- All 25 and 34 series specs should be upgraded to Rel-17 and that until the end of Rel-18 there should be a cross-TSG effort to find out if and how the related functionality could not be upgraded to Rel-18. This discussion should also be on whether to update the 2G specifications.
RAN Meeting Planning
Since the start of the pandemic in early 2020, 3GPP meetings have been completely converted into electronic ones.
Recently, a decision was made by the 3GPP’s specially convened meeting hosting decision group to host TSG#96 as a face-to-face (F2F) meeting. Decisions for other potential F2F meetings in 2022 are still pending.
For RAN, it is necessary to plan the RAN plenary and its WG meetings by considering the output from the decision group, while having a back-up plan in case of changes. The endorsed RAN meeting planning shown in the figure below reflects the target plan and the back-up plan, and also the need for a series of inactive periods during the meeting schedule, to attempt to ensure a better work/life balance for everyone.
Endorsed RAN meeting planning for the remaining 2022 (see RP-220857)
RAN Rel-17 Project Update
RAN#95-e brought about the planned Rel-17 functional freeze.
All RAN Rel-17 projects have been under close scrutiny, checking the respective completion level and required exception sheets, if any. Dedicated email threads were allocated to numerous Rel-17 projects, such as: sidelink enhancement, support of reduced capability NR devices, extending current NR operation to 71GHz, further enhancements on MIMO for NR, NR NTN, IoT NTN, UE power saving enhancements for NR, enhancements to IAB for NR, enhancement of RAN slicing for NR, RF requirements enhancement for NR FR1, Further enhancements of NR RF requirements for FR2, etc.
Conference call sessions were also organized to address the more controversial issues.
In particular, one working agreement (#44), as declared by RAN2 (which was challenged), was resolved in a very smooth and constructive manner (see the compromise in RP-221003). This is a demonstration of the hard-working and constructive spirit among all the delegates involved.
Through the intensive discussion via emails and conference calls, RAN#95-e successfully declared that RAN Rel-17 is functionally frozen. There are some RAN Rel-17 projects with the approved exception sheets. These will be an important focus for the upcoming RAN WG meetings in 2Q’2022.
The RAN ASN.1 freeze is planned for RAN#96, in June 2022.
5Gi Merger Update
In RAN#94-e, a way forward on merging 5Gi into 5G was approved in RP-213532, with specific milestones set for both 3GPP and the Standards body in India - TSDSI.
In RAN#95-e, an LS (in RP-220028) from TSDSI was received, in which TSDSI confirms their commitment not to further maintain 5Gi as a separate standard for its evolution, as also communicated to PCG, TEC and ITU-R. TSDSI requests RAN#95-e to approve the technically endorsed CRs, as per the agreed way forward.
In response, RAN#95-e approved the 2 pending CRs (RP-220920 and RP-220921), along with a reply liaison to TSDSI (in RP-220950), informing them of the RAN#95-e outcome.
With that, the 5Gi merger is completed from RAN perspective.
RAN Rel-18 Project Update
Release 18 is an important release, marking the start of 5G-Advanced. Discussion on potential RAN Rel-18 projects has been carefully planned and managed, starting from the first RAN Rel-18 workshop in June 2021.
In RAN#94-e, after multiple rounds of email discussion and conference calls, RAN1/2/3-led Rel-18 package was approved (as detailed in RP-213469). In the same package, there was also one RAN4-led Rel-18 WI and the corresponding RAN4 impact analysis for the approved RAN1/2/3-led Rel-18 items. The high-level overview of the corresponding TU budget was endorsed in RP-213697. All the corresponding SIDs/WIDs were also approved in RAN#94-e.
The primary focus in RAN#95-e for RAN Rel-18 were RAN4-led projects. Based on the fruitful email discussion in February 2022 focusing on potential RAN4-led R18 projects, RAN#95-e approved RAN4-led Rel-18 package in RP-220068 in a very smooth manner. The corresponding TU budget was endorsed in RP-220980 and later consolidated in RP-221019. All the corresponding RAN4-led Rel-18 SIDs/WIDs were approved in RAN#95-e as well.
Consequently, combining RAN#94-e and RAN#95-e, the package approval process for RAN Rel-18 is now completed.
As usual, RAN#95-e dedicated some time to handling matters related to ITU. In particular, the following liaisons were agreed by TSG RAN and sent to TSG SA:
- RP-220048: DRAFT reply letter to ITU-R WP5D/TEMP/353-E = RP-211636 on the schedule for updating Recommendation ITU-R M.2150 to Revision ‘After Year 2021’
- RP-220908: DRAFT reply letter to ITU-R WP5D/TEMP/356 = RP-211634 on the schedule for updating Recommendation ITU-R M.2012 to Revision 6
- RP-220911: Draft reply LS to ITU-R WP5D/TEMP/482rev1 = RP-212699 (update to RP-213642) on work towards two new recommendations "Generic unwanted emission characteristics of base / mobile stations using the terrestrial radio interfaces of IMT-2020"
In addition, the following LS was approved by RAN and sent to SA:
- RP-220912: LS related to 5GAA_WG4_S-220014 = RP-220044 on "online ITS communication standards database from ITU"
Despite the extreme challenges due to COVID-19 and the inevitable cancellations of all 3GPP physical meetings since the start of 2020, TSG RAN has successfully managed to deliver RAN Rel-17 (in terms of functional freeze) and approve RAN Rel-18 projects in a completely electronic manner (emails and conference calls). A deep appreciation goes to all delegates who have been extremely hard-working, patient, and constructive during this difficult time.
TSG#96 is upcoming very soon, as a first face-to-face meeting after a long two-and-a-half year break. I am eagerly looking forwarding to the happy re-union!
This article first appeared in Highlights, Issue 4.