R1-2508725
discussion
Overview of 6GR air interface
From OPPO
Summary
OPPO's Tdoc R1-2508725 presents a comprehensive vision for 6G Radio (6GR) air interface design, containing 53 numbered proposals and 13 observations across 15 sections. The document advocates for a modular, scalable 6GR design centered on a 'Mandatory baseline functionality set' derived from low-tier 6G IoT, spanning diverse device types, coverage targets, spectrum sharing, initial access, and AI-native services.
Position
OPPO proposes a modular 6GR air interface built on a 'lean' Mandatory baseline functionality set templated from lowest-tier 6G IoT capabilities, with device-type-specific functionality sets (eMBB, IoT, FWA, sensing) growing upward from this common foundation. They require intra-device-type scalability and inter-device-type scalability to be treated via distinct approaches, and that purely device type-specific attributes such as mobility/speed and UE power class are not necessarily included in the Mandatory baseline functionality set. OPPO proposes studying a smaller SSB bandwidth of 2.16 MHz at 15kHz SCS while maintaining NR PSS/SSS sequence lengths, and requires 6GR common signals/channels for initial access to be applicable to any spectrum allocations to avoid the significant performance loss caused by puncturing used in 5G. They propose specific coverage target values (MCL=146dB eMBB/153dB IoT, MIL=155dB eMBB/162dB IoT, MPL=126dB eMBB/133dB IoT) based on extrapolations from Rel-17 NR coverage enhancement schemes. They present a technical case for SCMC framework requiring lower complexity than CA framework for multi-carrier handling, arguing that SCMC maintains per-cell HARQ entity concept, BWP within one cell concept, and does not impact PDCCH blind detection or cell (re)selection procedures. OPPO proposes studying 2-stage DCI to reduce PDCCH blind detection, enhance forward compatibility for new DCI formats, and offload large DCI payload exceeding 140 bits. They propose that 6G core design may shift from 'bit stream quality-centric' to 'service quality-centric,' leveraging token-level error tolerance in AI services.
Key proposals
- Proposal 1 (Sec 2): The design principle for modular 6GR air interface can be scalable for diverse device types, by designing a Mandatory baseline functionality set for all device types (at least for eMBB and 6G IoT), supporting low-data rate operation with basic coverage enhancement and energy-efficient operation.
- Proposal 2 (Sec 3): In 6GR, both intra-device-type scalability and inter-device-type scalability should be supported via different approaches: intra-device-type via scalable design over device-type-specific mandatory and optional functionalities, inter-device-type via scalable design from 'mandatory baseline functionality set' to different device-type-specific functionality sets.
- Proposal 10 (Sec 4): Support 3MHz as minimum spectrum allocation (with 15kHz SCS) of 6GR for FR1 FDD, and consider designing 6GR common signals/channels applicable to the 3MHz channel BW.
- Proposal 12 (Sec 5): For coverage target determination, MCL of 146dB for 6G eMBB and 153dB for 6G IoT, MIL of 155dB for eMBB and 162dB for IoT, MPL of 126dB for eMBB and 133dB for IoT, with exact data rates FFS.
- Proposal 21 (Sec 6): High-level aspects for NR-6GR MRSS include UE/NW implementation complexity, resource allocation coordination between NR-6GR (including whether co-located), radio resource utilization, signaling overhead, operating bands at least existing FR1, alignment in time/frequency resource, and reliance on availability of specific NR NW and UE functionalities in existing NR deployments.
- Proposal 29 (Sec 7): Study an SSB structure with smaller BW than NR, e.g., 2.16 MHz @ 15KHz SCS, for 6GR, striving to maintain same PSS/SSS sequence length and considering more compact MIB or more OFDM symbols to guarantee PBCH performance.
- Proposal 30 (Sec 8): Requirements for 6GR random access include increased capacity of PRACH channels, enhanced coverage, and faster and resource efficient random access, e.g., PRACH-less random access.
- Proposal 35 (Sec 9): 2-stage DCI can be studied in 6G.
- Proposal 39 (Sec 10): The functionality of BWP, if still defined in 6GR, is to define a UE-side bandwidth at least after RRC connection and to support bandwidth adaptation; study improving definition of BWP, e.g., decoupling definition of BWP and numerology, supporting non-continuous frequency resource configuration.
- Proposal 42 (Sec 11): 6GR should study framework for multi-carrier handling mechanisms including CA, SCMC and carrier switching.
- Proposal 43 (Sec 12): For 6GR NTN specific feature design, strive for reusing the basic framework agreed for 6GR TN: waveform, numerology, frame structure, channel coding, modulation, basic channel structure for initial access, and basic control/transmission.
- Proposal 45 (Sec 13): 6G MIMO design shall be commercial needs oriented and only supports the necessary configuration/option.
- Proposal 50 (Sec 14): For 6G sensing study, consider the need of sharing common hardware for 6G communication and 6G sensing; reuse 6G communication HW for 6G sensing is preferred.
- Proposal 53 (Sec 15): To efficiently support AI services and token communications, studies are needed in RAN1 on Service Awareness in RAN1, Spec Impact on Token Error Identification, Scheduling and HARQ, and Framework for Token Communication Evaluation.