RAN Plenary Debrief December 2020
Hans van der Veen, NEC Labs Europe and Member of the 5G-IA Pre-Standardization WG reports on the RAN Plenary in December 2020, including changes that have taken place since the last plenary in September.
Rel-16 Planning (aka 5G Phase 2)
Stage 1: frozen December 2018 without exceptions
Stage 2: frozen June 2019 with exceptions; all remaining Stage 2 work was completed by March 2020
RAN1: frozen December 2019
RAN2 and RAN3: frozen June 2020 with 12 exceptions; all remaining RAN2 and RAN3 work was completed by December 2020
Stage 3: frozen June 2020 with exceptions in CT and SA; by December 2020 still unfinished work in SA3/SA5/CT3 (see below)
ASN.1 and open APIs: frozen June 2020; September 2020 version of RRC specifications is implementable
RAN4: freezing target March 2021
Rel-16 Exceptions (Core part)
An exception means that WGs can continue working on a topic for 3 more months, on specific topics as indicated.
In RAN, all 12 exceptions granted at RAN#88e (June/July) have now been completed.
In addition, in SA and CT the following work is not yet complete:
- Name: Security of URLLC for 5GS. Working Group: SA3. % Complete: 80%
- Name: Security aspects of Enhanced Network Slicing. Working Group: SA3. % Complete: 97%
- Name: Lawful Interception Rel-16. Working Group: SA3-LI. % Complete: 92%.
- Name: Lawful Interception Report Rel-16. Working Group: SA3-LI 0% Complete: 0%.
- Name: Network policy management for 5G mobile networks. Working Group: SA5. 0% Complete: 55%
- Name: CT3 aspects of 5G_eLCS. Working Group: CT3. 0% Complete: 85%
Rel-16 Closed Work Items and Study Items (excluding spectrum-related and conformance testing)
The following Rel-16 work was completed and the corresponding SIs and WIs closed:
- WI core: NR-based access to unlicensed spectrum
- WI perf.: NR 2-step RACH
- WI perf.: NR Mobility Enhancements
- WI perf.: RF requirements for NR frequency range 1 (FR1)
- WI perf.: NR support for high speed train scenario
- WI perf.: Over the air (OTA) base station (BS) testing TR
- WI perf.: Additional MTC enhancements for LTE
- WI perf.: Additional enhancements for NB-IoT
Rel-16 Work Item Summaries (descriptions of features in the release after the work has actually finished)
- RP-202753 NR-based access to unlicensed spectrum
- RP-202803 Enhancements on MIMO for NR
- RP-202842 Over the air (OTA) base station (BS) testing TR
- RP-202581 LTE/NR spectrum sharing in band 48/n48 frequency range
NR: FR2 fallback (Approved CRs: RP-202915/16/17/18, RP-202881/82/83/84)
Rel-15 CRs were approved based on the option "DL only with signalling", finally resolving this long-standing issue.
Rel-17 Planning (the dates below reflect 6 months further delay due to COVID-19)
Stage 1: frozen December 2019 with exceptions; all remaining Stage 1 work was completed by June 2020
RAN "Feature Packaging" ("Content definition") achieved December 2019; definition of "inter-TSG coordination areas" started
Stage 2: freezing target June 2021
RAN1: freezing target December 2021
RAN2 and RAN3: freezing target March 2022
Stage 3: freezing target March 2022
ASN.1 and open APIs: freezing target June 2022
RAN4: freezing target September 2022
Rel-17 Closed Work Items and Study Items (excluding spectrum-related and conformance testing)
The following Rel-17 work was completed and the corresponding SIs and WIs closed:
- SI: Study on NR coverage enhancements
Rel-17 Work Item Summaries (descriptions of features in the release after the work has actually finished)
- RP-202191 LTE/NR spectrum sharing in Band 40/n40
NR: Unlicensed 6GHz Scoping (Approved revised WIDs: unlicensed: RP-202592, licensed: RP-202844)
CEPT ECC decided in November on regulations for 6GHz unlicensed operation. Work on 6GHz unlicensed in Europe can now start.
NR: Secondary DRX (Endorsed proposal: RP-202835)
There is no consensus to include Secondary DRX enhancement in Rel-17.
NR: 1024QAM scope (Approved revised WID: RP-202886)
The discussion point was 5-bit or 6-bit MCS table. Based on majority support it will be 5-bit.
NR: Reduced Capability UEs (Approved RAN1 WI: RP-202933)
This highly controversial Work Item caused the longest discussions. One company almost put in a sustained objection because no reference to 40MHz bandwidth was made in the final scope. One 'camp' of companies strongly oppose any bandwidth for FR1 RedCap UEs wider than 20MHz. Another 'camp' of companies believes the WI is useless if it cannot cover more than 20MHz.
NR: Repeater (Approved RAN4 WI: RP-202927)
Many operators supported to have a WI to specify NR repeaters (in earlier discussions this was called 'smart' repeater). The intention is to reuse previous work on LTE repeater and IAB and keep it 'simple'
Approved Work Items and Study Items (excluding spectrum-related and conformance testing)
- RP-202928 WI: NR coverage enhancements
Keywords: (1) Specify PUSCH enhancements (enhance PUSCH repetition type A; support TB processing over multi-slot PUSCH; enable joint channel estimation); (2) Specify PUCCH enhancements (specify signalling to support dynamic PUCCH repetition factor indication; support DMRS bundling across PUCCH repetitions); (3) Specify mechanism(s) to support Type A PUSCH repetitions for Msg3.
- RP-202900 WI: NR Positioning Enhancements
Keywords: RAN1 centric objectives: (1) Specify methods, measurements, signalling, and procedures for improving positioning accuracy of Rel-16 NR positioning methods by mitigating UE Rx/Tx and/or gNB Rx/Tx timing delays, including (a) DL, UL and DL+UL positioning methods; (b) UE-based and UE-assisted positioning solutions; (2) Specify procedure, measurements, reporting, and signalling for improving the accuracy of (a) UL AoA for NW-based positioning solutions; (b) DL-AoD for UE-based and NW-based (including UE-assisted) positioning solutions.
- RP-202933 WI: Support of reduced capability NR devices
Keywords: (1) Specify support for following UE complexity reduction features (a) Reduced maximum UE bandwidth (max BW of FR1 RedCap UE during and after initial access of 20 MHz is supported; max BW of FR2 RedCap UE during and after initial access is 100 MHz); (b) Reduced minimum number of Rx branches (if legacy NR UE is required minimum of 2 Rx, min number of branches for RedCap UE is 1, but 2 Rx branches also supported; if legacy NR is required minimum of 4 Rx, min number of branches is tbd.); (c) Maximum number of DL MIMO layers (RedCap 1Rx UE: 1 DL MIMO layer; RedCap 2Rx UE: 2 DL MIMO layers); (d) Relaxed maximum modulation order (support of 256QAM in DL optional for FR1 RedCap UE; no other relaxations of maximum modulation order); (e) Duplex operation (HD-FDD type A with minimum specification impact (Note that FD-FDD and TDD are also supported)); (2) Specify higher layer support of enhancements listed above (L1 capabilities for RedCap UE identification, restraining capabilities, preventing RedCap UEs from capabilities such as CA, DC and wider bandwidths; allow operators to restrict access); (3) Specify RAN4 core requirements for the above.
Notes: WI is controversial, therefore lots of restrictions; in addition to the above also: Rel-15 SSB bandwidth reused, L1 changes minimized; no overlap with LPWA use cases; ensure coexistence with non-RedCap UEs; focus on SA. single connectivity with operation in single band at a time.
- RP-202927 WI: NR Repeaters
Keywords: Specify RF and EMC requirements for NR repeaters for FR1 (FDD and TDD) and FR2 (TDD) bands; leverage RF specifications for LTE repeater and IAB; Assumptions: no adaptive beamforming towards the UE; TDD repeater meets both BS and UE emission requirements (or the more stringent absolute level in dBm) in all slots; if needed for workload, for TDD repeaters constraint may be that TX EIRP/TRP/power does not exceed any UE power class defined in the band; FR1 FDD repeaters testing is assumed to be conducted.
Stage 1: freezing target December 2021 (TSG#94) (with 80% completion at TSG#93)
RAN: Workshop on Rel-18 content expected to be held in summer 2021 (probably late June).