Spreadtrum · 10.3.2

Spreadtrum proposes parallel and independent evaluations between RAN1 and RAN4 for DL 4096QAM and UL 1024QAM, with RAN1 focusing only on ideal baseband performance without RF impairment modeling, and requires alignment with RAN4's existing prioritization of UL 1024QAM. They present a technical case against probabilistic shaping (PS) adoption in 6GR, arguing that the fundamental principle of PS causes structural conflicts with legacy NR payload-independent processing including scrambling, interleaving, and CB segmentation, and inevitably requires LDPC redesign due to incompatibility with legacy filler bits. They support geometric shaping (GS) as it remains completely transparent to all other Tx/Rx chain functionality blocks except mapper and modulation blocks, requiring only LUT updates for constellation and bit mapping rules, and propose down-selection between 1D-NUC and 2D-NUC during the RAN1/RAN4 Malta joint session. They require quantifiable PAPR increase values to be provided alongside performance gains and jointly evaluated with performance-complexity trade-offs to determine shaping feasibility. They support legacy 5G NR equal probability uniform QPSK for the 6GR control channel, citing mandatory robustness requirements due to the absence of HARQ retransmission for DCI/UCI payload.

Spreadtrum/UNISOC opposes the adoption of Probabilistic Shaping (PS) for 6G, arguing that its serial and block-based Distribution Matcher/De-matcher (DM/DDM) processing fundamentally conflicts with the TS 38.214 PDSCH processing time (N1) constraint, leading to prohibitive chip area and buffer costs. They present a technical case against supporting joint channel coding and modulation in 6G Release, though they do not preclude discussing its use case in 6G AI contexts. They question the statistical significance of DL 4096QAM and UL 1024QAM, citing system-level simulations showing that less than 3% of sub-7GHz UMa UEs and only 10-23% of mmWave UEs achieve the required SIR/SINR thresholds. They require that any evaluation of shaping gains be based on a 'Net Gain' methodology that subtracts PAPR-induced PA backoff penalties and non-ideal implementation losses from theoretical AWGN gains.