R1-2600031
discussion
Overall aspects of the 6GR multi-antenna system
From Nokia
Summary
This Tdoc from Nokia presents 24 proposals and 12 observations on 6GR physical layer design aspects including SCS selection, CP length, 400MHz UE bandwidth support, frame structure, duplexing, spectrum aggregation, and coverage, with a focus on system simplification and unified framework design.
Position
Nokia proposes ruling out 60 kHz SCS from the Around 15 GHz scenario and postponing final SCS selection between 30 kHz and 120 kHz until end of 2026. They require supporting only normal CP length for TN communication, and for NTN only normal CP in DL with any UL pre-compensation solutions maintaining alignment with NCP symbol structure. For 400MHz UE support with 30 kHz SCS, they require a single RF chain per antenna port with unified processing framework, proposing consideration of asymmetric CBW (200MHz UL / 400MHz DL). They propose studying three frame structure configuration options (symbol-based, layer-based, 2D resource) and require removing UE-specific TDD configuration while supporting flexible symbols as a resource type. They require semi-static TDD as the primary duplexing scheme, propose deprioritizing dynamic SBFD, UE SBFD, and gNB FD, and support dynamic TDD based on predefined TDD patterns rather than NR's symbol-level SFI. For spectrum aggregation, they propose building 6G CA upon a single unified framework with decoupled serving cell scheduling and propose studying semi-static UL TX switching patterns instead of NR's dynamic triggering approach.
Key proposals
- Proposal 2.1 (Sec 2.1): Rule out the 60 kHz SCS option from Around 15 GHz scenario.
- Proposal 2.3 (Sec 2.2): Support only normal CP length with 6GR in the terrestrial network (TN) communication scenario.
- Proposal 3.1 (Sec 3): The 400MHz UE support for 30 kHz SCS should follow a unified processing and operational framework to avoid multiple implementations, thereby reducing specification and operational complexity for 6GR gNBs.
- Proposal 4.2 (Sec 4.2): For the 6GR frame structure configuration, RAN1 to further study the following three options: Symbol-based, Layer-based, and 2D resource configuration.
- Proposal 4.6 (Sec 4.3): Support only cell-specific TDD configuration based on the cell-specific SCS (i.e. remove the support of UE-specific TDD configuration / TDD-UL-DL-ConfigurationDedicated).
- Proposal 5.1 (Sec 5): For MRSS compatibility purposes, semi-static TDD is considered the primary duplexing scheme also for 6G. The support of advanced duplexing schemes in 6G should not come at the cost of increased complexity for basic TDD operation.
- Proposal 5.3 (Sec 5.1): 6GR to support dynamic TDD operation based on UL, DL and flexible resources. Consider TDD operation based on set of TDD patterns instead of fully flexibly configurable slot format combinations.
- Proposal 5.5 (Sec 5.4): RAN1 to deprioritize dynamic SBFD from the current Rel-20 Study item scope. If dynamic SBFD is to be supported, the feature should be limited to allowing the network to turn on and off the SBFD symbols without need for RRC reconfiguration.
- Proposal 5.6 (Sec 5.4): Deprioritize UE side SBFD and Full duplex gNB from the current Rel-20 6GR study item scope.
- Proposal 6.1 (Sec 6.1): Adopt the NR TB processing principle per carrier as baseline for 6GR CA design allowing for modular and scalable network and UE implementations.
- Proposal 6.2 (Sec 6.1): Support for PHY control signaling without low-latency coordination among serving cells is the cornerstone for the 6G CA design. This should include the support for HARQ-ACK reporting with decoupled serving cell scheduling.
- Proposal 6.3 (Sec 6.2): Support a single framework for 6G spectrum aggregation built upon the Carrier Aggregation (CA) framework, integrating flexible uplink/downlink pairing and uplink Tx switching with CA.
- Proposal 6.7 (Sec 6.6): Study the support of 6GR UL TX switching based on semi-static patterns (instead of dynamic triggering) enabling the UL TX switching to be applicable to all UL physical channels and signals.
- Proposal 7.1 (Sec 7): Candidate 1 link budget table is used as part of the analysis of the coverage of 6GR data channels around 7 GHz when re-using same site grid as for 5G mid-band (~3.5 GHz).