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Contested proposalRAN1 #126

RAN1 meeting 126 finds no consensus on constellation shaping for 6G radio

Published 2026-10-16Updated 2026-10-163GPP TSG RAN WG1 #126

At a glance

At meeting 126, RAN1, the radio access network working group one, found no consensus to support constellation shaping.

Who proposed what

The discussion concerned modulation for 6GR, the 6G radio interface. Plenary guidance quoted in the chair notes asked RAN1 to decide on constellation shaping by the third quarter of 2026. The candidates were geometric shaping, using one-dimensional non-uniform constellations, and probabilistic shaping. RAN1 concluded, as recorded in the chair notes, that no scheme had consensus for downlink or uplink. If there was no consensus in that quarter, the quoted plenary guidance said "the study on constellation shaping will be stopped".

Source: R1-2606762, Ad-Hoc Chair (Ericsson), 3GPP TSG RAN WG1 #126, chair notes, agenda item 10.3.2.

Qualcomm proposed probabilistic shaping as optional for user equipment and optionally configurable by the network. UNISOC proposed that probabilistic shaping not be supported in 6GR. The meeting's contribution register lists both proposals as not treated.

Huawei (with HiSilicon) said probabilistic shaping "requires significant specification and implementation changes" in the transmitter and receiver chain. MediaTek proposed that the technical report record applicability in two regimes using the existing radio frequency and encoding chain. MediaTek described one shaping parameter for refarmed fourth-generation frequency division duplex bands, and per-layer shaping in the 6GR band around 7 gigahertz. Our reading: MediaTek's existing-chain argument contrasts with Huawei (with HiSilicon)'s concern about transmitter and receiver changes.

Source: R1-2605289, Huawei (with HiSilicon), 3GPP TSG RAN WG1 #126. © Huawei, HiSilicon.

Sources

  1. R1-2606762, Ad-Hoc Chair (Ericsson), 3GPP TSG RAN WG1 #126, chair notes, agenda item 10.3.2.
  2. R1-2606911, Qualcomm, 3GPP TSG RAN WG1 #126. © Qualcomm.
  3. R1-2605252, UNISOC, 3GPP TSG RAN WG1 #126. © UNISOC.
  4. R1-2606839, MediaTek, 3GPP TSG RAN WG1 #126. © MediaTek.
  5. R1-2605289, Huawei (with HiSilicon), 3GPP TSG RAN WG1 #126. © Huawei, HiSilicon.

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