10.1.4 HARQ-ACK Repetition procedure

36.2133GPPEvolved Universal Terrestrial Radio Access (E-UTRA)Physical layer proceduresRelease 17TS

For a non-BL/CE UE, HARQ-ACK repetition is enabled or disabled by a UE specific parameter ackNackRepetition configured by higher layers. Once enabled, the UE shall repeat any HARQ-ACK transmission with a repetition factor , where is provided by higher layers and includes the initial HARQ-ACK transmission, until HARQ-ACK repetition is disabled by higher layers. For a PDSCH transmission without a corresponding PDCCH/EPDCCH detected, the UE shall transmit the corresponding HARQ-ACK response times using PUCCH resource configured by higher layers. For a PDSCH transmission with a corresponding PDCCH/EPDCCH detected, or for a PDCCH/EPDCCH indicating downlink SPS release, the UE shall first transmit the corresponding HARQ-ACK response once using PUCCH resource derived from the corresponding PDCCH CCE index or EPDCCH ECCE index (as described in Clauses 10.1.2 and 10.1.3), and repeat the transmission of the corresponding HARQ-ACK response times always using PUCCH resource , where is configured by higher layers.

HARQ-ACK repetition is only applicable for UEs configured with one serving cell for FDD and TDD. For TDD, HARQ-ACK repetition is only applicable for HARQ-ACK bundling.

HARQ-ACK repetition can be enabled with PUCCH format 1a/1b on two antenna ports. For a UE configured for two antenna port transmission for HARQ-ACK repetition with PUCCH format 1a/1b, a PUCCH resource value maps to two PUCCH resources with the first PUCCH resource for antenna port and the second PUCCH resource for antenna port , otherwise, the PUCCH resource value maps to a single PUCCH resource for antenna port .