Nokia · 10.3.2

Nokia proposes that 5G NR equal probability uniform QAM constellations be explicitly adopted as the supported baseline modulation scheme for 6G (not merely 'as basis for study'), while allowing separate discussion of enhancements. They propose supporting uniform 1024QAM in uplink but present a technical case against uniform 4096QAM in downlink, citing prohibitive computation complexity and power consumption of R-ML MIMO detection at the UE and very low required EVM. On constellation shaping, Nokia requires that the specification impact on Rel-18 advanced DL-MU-MIMO receivers be addressed, warning that per-MCS optimized shapes and probabilistic shaping factors would break the co-scheduled UE modulation detection framework. They require decoupling MCS table optimization from geometric/probabilistic shaping decisions, and propose studying spectral efficiency operating points achievable with more than a single modulation order to address MIMO layer imbalance.

Nokia proposes adopting 5G NR uniform QAM schemes as baseline 6G modulation and adding uniform 1024QAM in UL. They oppose uniform 4096QAM in DL due to R-ML MIMO detection complexity and EVM requirements. For geometric constellation shaping, they require down-selection from higher-order uniform QAM with sign symmetry, quantization with limited bits per I/Q, and minimization of shape variants per order. They deprioritize AI two-sided model approaches while allowing AI receiver evaluation. They present a technical case against probabilistic constellation shaping, arguing AWGN gains do not carry over to fading channels and highlighting impacts on HARQ retransmissions, PAPR, and MIMO detector complexity. They propose studying MCS tables that allow multiple modulation-order/code-rate pairs per spectral efficiency point.