Spreadtrum · 10.5.3.1
Aspects of downlink-based CSI acquisition ·
RAN1#124bis · Source verification
the AI's delta
strengthened
vs RAN1#124
Spreadtrum hardened their opposition to expanding CSI-RS ports beyond 128, now explicitly opposing 256 ports with cited reasoning (UE measurement complexity), where previously they simply supported up to 128 ports without explicit rejection of higher counts. They added a new explicit opposition to L2-based (MAC-CE) CSI reporting as a Day-1 6G priority absent from the prior meeting, presenting a detailed technical case citing MAC PDU construction latency, HARQ retransmission delay, and overhead from MAC sub-headers and CRC compared to L1 UCI. Their unified CSI framework position expanded to explicitly name sTRP, mTRP, and mTRP calibration scenarios, and they hardened their early CSI position from supporting early CSI for candidate cells to preferring to study inclusion of candidate cell early CSI rather than creating separate frameworks.' Their PN sequence with UE-specific seed proposal was dropped from the current position. On AI/ML, their JSCC/JSCM postponement argument shifted from until NR standardization completes to the more specific until NR two-side model work completes, citing unresolved inter-vendor issues,' and the spatial domain generalization concern with ~28% SGCS loss was dropped. Their low-overhead CSI-RS reconstruction results (<5% SGCS loss with 87% frequency and 75% spatial RS overhead reduction) are preserved with identical quantitative claims.
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Contributions at RAN1#124bis · 1 doc
Discussion on aspects of downlink-based CSI acquisition for 6GR
Position extracted by AI
Spreadtrum proposes a unified CSI acquisition framework spanning sTRP, mTRP, mTRP calibration, and early CSI scenarios, preferring to study inclusion of candidate cell early CSI rather than creating separate frameworks. They oppose L2-based (MAC-CE) CSI reporting as a Day-1 6G priority, arguing it introduces substantial latency from MAC PDU construction and HARQ retransmission, and incurs significant overhead from MAC sub-headers and CRC compared to L1 UCI. For CSI-RS design, Spreadtrum supports up to 128 ports as a starting point (opposing 256 ports due to UE measurement complexity), requires using a single CSI-RS resource to contain all ports rather than resource aggregation, and proposes sparse frequency/spatial domain density combined with component RE pattern aggregation for overhead reduction. On AI/ML, Spreadtrum presents a case for postponing JSCC/JSCM standardization until NR two-side model work completes, citing unresolved inter-vendor issues, while prioritizing low-overhead CSI-RS reconstruction as the Day-1 6G AI use case based on simulation results showing less than 5% SGCS loss with 87% frequency domain and 75% spatial domain RS overhead reduction.
Summary
Spreadtrum's R1-2601814 presents 21 proposals and 12 observations on 6G downlink CSI acquisition, covering a unified CSI framework, basic CSI-RS design supporting up to 128 ports, and AI/ML-based CSI compression and low-overhead CSI-RS. The document recommends postponing two-side AI/ML models (JSCC/JSCM) until NR work completes while prioritizing low-overhead CSI-RS as a Day-1 6G AI use case.
Prior contributions at RAN1#124 · 1 doc · Feb 09, 2026
Discussion on aspects of downlink-based CSI acquisition for 6GR
Position extracted by AI
Spreadtrum proposes a unified CSI acquisition framework design that associates a CSI report configuration with a channel measurement configuration and/or an interference measurement configuration, supporting multiple scenarios including early CSI for candidate cells. They propose studying both NW-controlled and UE-initiated CSI reporting, and consider PUSCH-only based CSI reporting for all time domain behaviors in 6GR. For CSI-RS design, they support up to 128 ports per single CSI-RS resource and propose PN sequence with UE-specific seed with component RE pattern aggregation. On AI/ML, they present technical case showing JSCC/JSCM performance gains over SSCC especially at low SNR but propose postponing two-side model work until NR standardization completes. They prioritize low overhead CSI-RS for 6GR Day 1 AI use case, presenting evaluation results showing less than 5% SGCS loss with 87% frequency domain and 75% spatial domain RS overhead reduction, while noting spatial domain generalization across deployment scenarios needs further study due to approximately 28% SGCS loss.
Summary
This document from Spreadtrum provides 18 proposals and 12 observations on downlink CSI acquisition for 6G Radio, covering a unified CSI framework, CSI-RS design with up to 128 ports, and AI/ML-based CSI solutions including compression/feedback (JSCC/JSCM) and low-overhead CSI-RS with model generalization analysis.
How this was derived
The AI extracted the "position extracted" field above directly from each Tdoc during summarization.
For the delta summary at the top, the AI compared Spreadtrum's consolidated stance at RAN1#124bis
against their stance at RAN1#124 and classified the change as
strengthened.
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