R1-2601806
discussion
Discussion on 6GR general aspects and frameworks
From Spreadtrum
Spreadtrum's prior position on
10.5.0
at
RAN1#124
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Proposes studying SBFD symbol as a new native symbol type in 6GR frame structure while opposing gNB dynamic SBFD, UE SBFD, and gNB full duplex in Release day1. Requires separate discussion of NW-side and UE-side maximum CBW, and separate DL versus UL max CBW at UE side, supporting only Option 2 (dual 200MHz RF + single 400MHz BB) or Option 3 (dual 200MHz RF + dual 200MHz BB) for UE to achieve 400MHz around 7GHz. Proposes studying Single Cell Multi-Carrier (SCMC) mechanism for non-contiguous intra-band carriers and DL/UL decoupling, while identifying NTN techniques applicable to TN in day1. Adopts 20MHz as the smallest maximum supported UE bandwidth for low-tier devices, closing high-level scalable design discussions, and requires bottleneck channel identification across all RRC states to avoid piecemeal coverage enhancements.
Summary
This Spreadtrum/UNISOC contribution to the 3GPP RAN1 #124bis meeting presents 21 proposals and 2 observations covering 6G Radio (6GR) general aspects, including maximum bandwidth, scalability, spectrum aggregation via 'Gothia cell', duplexing, and MRSS. The document aims to establish a practical framework for 6GR physical layer design, emphasizing single-cell solutions for wideband operation and native support for advanced duplex schemes.
Position
Spreadtrum/UNISOC requires a 20MHz smallest maximum UE bandwidth (Alt 1) for lower-tier 6GR devices, arguing that 20MHz offers an optimal balance between complexity reduction (35-70%) and system performance compared to 5MHz. They propose Option 2 (double 200MHz RF with single 400MHz BB) as the preferred starting point for enabling UE support of 400MHz downlink CBW, balancing performance and implementation complexity over the more stringent Option 1 or CA-limited Option 3. The company introduces the 'Gothia cell' concept for aggregating multiple physical carriers into a single virtual cell to simplify cell management and reduce latency compared to traditional CA, and proposes studying three DCI scheduling options for cross-carrier data transmission within this cell. They oppose support for gNB dynamic SBFD, UE SBFD, and gNB full duplex in 6GR Day 1, citing unproven gains and interference challenges, but propose studying a native SBFD symbol type within the 6GR frame structure alongside reserved resources for forward compatibility. Additionally, they address NR-6GR MRSS by proposing a unified design with co-located TRPs as a baseline, aligned numerology and waveform, and a requirement for no impact on legacy NR UE behavior.
Key proposals
- Proposal 1 (Sec Scalability related aspects): For the 6GR smallest maximum UE bandwidth for at least one lower-tier device, Alt 1 (20MHz) should be supported.
- Proposal 3 (Sec Maximum bandwidth): To enable UE to support downlink max.CBW 400MHz, option2 (Double 200MHz RF & single 400MHz BB) can be a starting point, and further investigation on option 1 and option 3 in terms of implementation complexity and performance.
- Proposal 10 (Sec Spectrum aggregation): For single 'Gothia cell' aggregated by multiple physical carriers, at least study aspects including intra-band carriers with same SCS, same UL/DL allocation, one SSB/SIB1 in one carrier, scheduling mechanism, RRM, carrier selection, and activation/deactivation.
- Proposal 12 (Sec Spectrum aggregation): Both single 'Gothia cell' mechanism and CA are supported.
- Proposal 14 (Sec Spectrum utilization and aggregation): For flexible DL and UL decoupling, at least study applicable deployment scenarios, applicable frameworks, DL/UL timing acquisition, UL power control, and Tx/Rx switching.
- Proposal 16 (Sec Numerology and frame structure): Support of cell specific RRC configuration for 6GR frame structure.
- Proposal 17 (Sec Duplexing): Not support of gNB dynamic SBFD, UE SBFD and gNB FD in 6GR day1.
- Proposal 18 (Sec Duplexing): For 6GR symbol/slot types, support at least DL, UL and Flexible; study SBFD symbol as a new symbol type; study Reserved symbols/slots type.
- Proposal 20 (Sec Duplexing): Study SBFD schemes for downlink CBW 400MHz and uplink CBW 200MHz.
- Proposal 21 (Sec MRSS): High-level aspects to consider for NR-6GR MRSS include UE/NW implementation complexity, resource allocation coordination, co-located TRP as baseline, unified MRSS technique, aligned numerology/waveform, and no impact to legacy NR UE behavior.
- Proposal 6 (Sec Maximum bandwidth): For downlink max.CBW 400MHz case, study the necessity and feasibility of adopting the transmission of SSBs (including CD-SSB or NCD-SSB) in upper 200MHz and lower 200MHz, respectively.
- Proposal 7 (Sec Maximum bandwidth): For sub-6GHz, support 100MHz as the max CBW for both downlink and uplink from both NW side and UE side.
- Proposal 9 (Sec Maximum bandwidth): For FR2-1 band (between 24.25GHz - 52.6GHz), support 400MHz as the max CBW from UE side.
- Proposal 13 (Sec Spectrum aggregation): For non-collocated deployment scenarios for FR1-FR2 CA, at least study PUCCH group configuration, frame/slot boundary alignment, cross carrier scheduling, and MRTD requirement relaxation.