R1-2600143
discussion
Discussion on general aspects and framework
From Huawei
Summary
Huawei's Tdoc R1-2600143 provides a comprehensive framework proposal for 6G RAN1 physical layer studies, containing 24 proposals and 14 observations across six major areas: coverage enhancements for co-site deployment with 5G mid-band, efficient spectrum utilization via a new 'virtual cell' concept, numerologies for ~7 GHz and FR2-1, duplex modes including simplified dynamic TDD and SBFD, multi-RAT spectrum sharing (MRSS) lessons from DSS, and UE bandwidth scalability for IoT devices.
Position
Huawei demands 6G coverage evaluation use specific 2.5/3.3 GHz 5G references versus 7.125/8.4 GHz 6G with Candidate 1 link budget template and MPL metric, identifying gaps of 10.6 dB (PUSCH), 7.6 dB (PDSCH), 13.6 dB (common DL), and 16.6 dB (common UL). They propose a new 'virtual cell' spectrum aggregation mechanism with strict synchronization requirements, single SSB/DCI/HARQ/RRM, and common handover, limited to cases where aggregated PRBs don't exceed single-carrier maximum and frequency span stays within a sub-range. They require supporting simplified dynamic TDD only in scenarios where adjacent channel CLI can be avoided (macro without adjacent operator, or micro cell deployments), mandate BS semi-static SBFD with subband adaptation, and demand N_TA-offset alignment between NR and 6GR. They argue against IoT bandwidth below 20 MHz, claiming only ~10% additional complexity reduction from 20 MHz to 5 MHz while requiring 8-10x more repetitions for coverage, and propose mandating 120 kHz SCS for FR2-1 sync signals.
Key proposals
- Proposal 1 (Sec 1): Identifies six framework topics (coverage, spectrum aggregation, duplexing, MRSS, scalability, bandwidth/numerology) requiring overall agreements in agenda item 10.5.0 to guide other sub-agenda studies.
- Proposal 2 (Sec 2.1): Specifies two carrier frequency pairs for coverage target evaluation: Pair#1 (3.3 GHz 5G vs 8.4 GHz 6G) and Pair#2 (2.5 GHz 5G vs 7.1 GHz 6G) to ensure scalable system design.
- Proposal 8 (Sec 2.1): Recommends using coverage gap evaluation results (Tables 3-6) to guide 6GR physical channel/signal design during initial access and random access, with additional margins for further discussion.
- Proposal 9 (Sec 2.2): Proposes studying a 'virtual cell' mechanism where multiple physical carriers are aggregated with single SSB, single DCI scheduling, single HARQ entity, and common handover across carriers.
- Proposal 12 (Sec 2.2): Proposes studying flexible DL/UL pairing applicable for initial access and after, allowing multiple UL/DL CCs from same/different bands to pair across co-located or non-co-located sites.
- Proposal 16 (Sec 2.3): Assumes same SCS between 6GR sync signals and other channels/signals (except PRACH) in FR2-1, specifically only 120 kHz.
- Proposal 17 (Sec 2.4): Supports TDD, FDD, simplified dynamic TDD (for scenarios with minimized adjacent channel CLI), and BS semi-static SBFD with subband adaptation as duplex modes for 6G.
- Proposal 20 (Sec 2.4): Proposes studying a simplified SFI indication framework for transmission direction in TDD, considering realistic DL/UL traffic variation.
- Proposal 21 (Sec 2.4): Proposes studying time-frequency domain configuration for TDD including SBFD support, covering how to configure DL slots, UL slots, and SBFD subbands.
- Proposal 22 (Sec 2.5): Requires N_TA-offset alignment between NR and 6GR to avoid interference caused by misaligned frames.
- Proposal 23 (Sec 2.5): Proposes studying rate-matching patterns of PDSCH and rate matching of CSI-RS for NR-6GR MRSS.
- Proposal 24 (Sec 2.6): Requires 6G to support 20 MHz as the smallest maximum supported RF and baseband UE bandwidth without spectrum aggregation for at least one low-tier device type.
- Proposal 13 (Sec 2.2): Proposes studying uplink Tx switching for UEs with various Tx chain capabilities (1Tx/2Tx/4Tx) and switching cases (e.g., 4Tx-4Tx/2Tx/1Tx).
- Proposal 7 (Sec 2.1): Recommends RAN1 summarize coverage gap analysis between ~7 GHz and 5G NR mid-band reference for initial access channels/signals and provide enhancement target recommendations to RAN plenary.
- Proposal 15 (Sec 2.2): Proposes studying fast SCell activation including information reporting while considering impact on UE power consumption.