RAN1 #126-bis agrees to study ways to change PDCCH receive-antenna count

RAN1 is the radio layer 1 working group, and its chair notes concern studying dynamic receive-antenna adaptation for PDCCH monitoring. Option 1 uses "explicit indication from the network". Option 2 uses implicit rules known to the network and user equipment (UE), with the network able to configure them. Our reading: this study agreement does not itself specify which method will be implemented.

Source: R1-2607288, Ad-Hoc Chair (NTT DOCOMO, INC.), 3GPP TSG RAN WG1 #126-bis, chair notes, agenda item 10.5.4.1.

The chair notes do not preclude combining the options. They also do not preclude using one option to reduce antenna count and the other to increase it. How the network learns the UE's receive-antenna count, if needed, remains for further study.

UNISOC warned that antenna-count changes bring "large impacts on coverage/PDCCH performance". UNISOC also said they save less energy than adapting when PDCCH monitoring happens. China Mobile proposed evaluating spatial PDCCH adaptation, meaning antenna-related changes, for network overhead, switching delay and throughput. ETRI said energy savings at each level come with other costs, which should be reported alongside the savings. Google proposed studying frequency-domain adaptation, changing the monitored frequency range rather than the receive-antenna count. All four company contributions were registered as not treated at RAN1 #126-bis, with no decision recorded for them.

Source: R1-2607121, UNISOC, 3GPP TSG RAN WG1 #126-bis. © UNISOC.