R1-2508733
discussion
Overview of 6GR air interface
From Huawei
Summary
This Huawei/HiSilicon contribution to the 3GPP RAN1#123 meeting provides a comprehensive overview of the 6GR air interface design, encompassing 13 formal proposals and 6 observations. The document covers key areas including coverage evaluation for ~7GHz, efficient spectrum utilization, bandwidth adaptation, NR-6GR MRSS, and harmonized TN/NTN design.
Position
Huawei argues that 6GR ~7GHz design must aim for continuous coverage using ISDs similar to 5G mid-band, and proposes using MPL (Maximum Path Loss) from TR 38.830, rather than MaxCL from TR 38.913, as the primary coverage evaluation metric to capture frequency-dependent losses like penetration and antenna gain. The company identifies NR Carrier Aggregation's slow SCell activation and fixed DL/UL pairing as key lessons, and proposes studying single-carrier-like spectrum aggregation with flexible DL/UL pairing to address fragmented spectrum utilization. For BWP operation, the company labels NR's parameterization as 'over-flexible' and proposes a simplified BWP framework with a robust switching mechanism to prevent BS-UE misalignment. For IoT, they propose a 20 MHz baseline bandwidth capability, contending that reducing to 5 MHz yields only ~10% additional complexity savings while requiring 8-10 times more repetitions for equivalent coverage, thus impacting system efficiency.
Key proposals
- Proposal 1 (Sec 2.1): For around 7GHz, the study of 6GR design should aim at continuous coverage with an ISD at least similar to that for 5G mid-band.
- Proposal 6 (Sec 2.2): Updates the observation on lessons learned from NR spectrum utilization and aggregation, including critiques of CA activation latency, DL/UL coupling inefficiency, and limited UL TX switching.
- Proposal 9 (Sec 2.3): Study a simplified BWP framework to reduce BWP switching delay and a robust BWP switching mechanism to avoid misalignment of the active BWP between the BS and UE.
- Proposal 10 (Sec 2.4): Updates high-level aspects for NR-6GR MRSS, including UE/NW complexity, resource allocation coordination, and alignment in time/frequency resources.
- Proposal 11 (Sec 2.5): RAN1 studies the 6GR SSB design using 5 MHz at 15 kHz SCS and 10 MHz at 30 kHz SCS as a baseline to ensure coverage for typical allocations, supporting narrower bandwidths (e.g., 3 MHz) via a scalable design.
- Proposal 12 (Sec 2.6.2): 6GR lowest-tier devices should support 20 MHz as the channel bandwidth capability for both RF and baseband.
- Proposal 13 (Sec 2.7): 6GR shall support a harmonized TN/NTN air interface including common designs for basic features and a common framework for other features, with NTN-specific design for K_mac/K_offset timing.
- Proposal 2 (Sec 2.1.1): RAN1 to adopt the Candidate 1 link budget template from TR 38.830 and use MPL as the primary metric to evaluate the coverage gap for ~7 GHz.
- Proposal 3 (Sec 2.1.1): Adopt MPL as defined in TR 38.830 as the metric to determine coverage target(s) in RAN plenary.
- Proposal 4 (Sec 2.1.2): Proposes two options for coverage evaluation: absolute targets assuming a typical ISD (e.g., 500 m) or relative coverage differences compared to a 5G NR mid-band bottleneck channel like Msg3.
- Proposal 5 (Sec 2.1.3): 6GR should study coverage enhancement including DL/UL MIMO enhancement, uplink low PAPR waveform, advanced duplex, and multi-TRP coordination.
- Proposal 7 (Sec 2.2): Study 'single carrier like spectrum aggregation' and flexible DL/UL pairing for efficient spectrum utilization.
- Proposal 8 (Sec 2.3): Updates the observation on lessons learned from NR BWP, citing excessive BWP-specific BB/RF parameters and SCS switching complexity.