128-port MIMO codebooks split vendors over how much of the old design survives

Nokia and Samsung want the 128-port Type-II codebook restriction to be a clean, group-based replacement for the old two-level scheme; Huawei, ZTE and Fraunhofer insist it should only modify the second level of what already exists. The moderator sided with Nokia's camp — 'Understanding 1 is correct and Understanding 2 is incorrect' — but no consensus followed, and the moderator warned the whole restriction feature for Release 19 could be dropped if the deadlock continues.

Phones with three transmit antennas got eight competing technical proposals on precoding, reference-signal linking and power scaling, backed by Samsung, OPPO, ZTE, vivo and Huawei among others; Google and CATT questioned whether the changes are needed at all. None were adopted, so chipset vendors building 3TX uplink still lack a finalized rulebook covering four separate specification documents (TS 38.211, 38.212, 38.213, 38.214).

Coordinated multi-cell transmission (CJT) saw a rerun of a familiar fight: ZTE and Qualcomm wanted delay-offset reporting refined to 0.1–0.2 cyclic-prefix steps for tighter timing alignment across base stations, while Nokia argued the resulting resolution would be under 1 nanosecond — finer than a phone can distinguish from ordinary timing error. The chair had already flagged this proposal for rejection if positions didn't shift, and they didn't.

Low-band carrier switching — where a phone alternates between a primary FDD carrier and a downlink-only SDL carrier instead of true aggregation — got firmer footing: a 40ms bitmap pattern and a fixed switching gap when returning from SDL to FDD, with gap duration configurable per direction based on a phone's reported retuning time (35µs or 140µs). But the opposite direction, FDD to SDL, still has three rival proposals from MediaTek/Nokia/Ericsson (gap always at the end of FDD), vivo/OPPO/Huawei (network-configured location), and Samsung/CATT (gap always on SDL) — meaning base station vendors can't yet build a single, predictable retuning procedure.

RAN1#121 in Malta is where several of these threads converge: companies must decide whether phones measuring candidate-cell channel quality for fast Layer-1 mobility can be configured with more active CSI-RS resources than their declared capability — Fujitsu, Nokia, Qualcomm, Ericsson and DOCOMO want phones to pick which signals to measure themselves, while ZTE, vivo, Lenovo and LG want any over-configuration treated as an error. The outcome decides whether operators can broadcast a rich, one-size-fits-all measurement configuration or must tailor it precisely to each device.