WF on CB-group based retransmission 3GPP TSG RAN1#88bis Spokane, USA, 3rd – 7th, April, 2017 Agenda Item: 8.1.3.3.2 R1-17xxxxx WF on CB-group based retransmission Samsung, [Ericsson, KT, ZTE, ZTE Microelectronics, SEQUANS], …

Background In RAN1#88, the following working assumption was made. CBG-based transmission with single/multi-bit HARQ-ACK feedback is supported in Rel-15, which shall have the following characteristics: Only allow CBG based (re)-transmission for the same TB of a HARQ process CBG can include all CB of a TB regardless of the size of the TB – In the such case, UE reports single HARQ ACK bits for the TB CBG can include one CB CBG granularity is configurable

Proposal Confirm the working assumption as below. CBG-based transmission with single/multi-bit HARQ-ACK feedback is supported in Rel-15, which shall have the following characteristics: Only allow CBG based (re)-transmission for the same TB of a HARQ process CBG can include all CB of a TB regardless of the size of the TB – In the such case, UE reports single HARQ ACK bits for the TB CBG can include one CB CBG granularity is configurable

Proposal The UE is semi-statically configured by RRC signaling to enable CBG-based retransmission. The above configuration to enable CBG-based retransmission is separate for DL and UL. For initial transmission of a PDSCH or PUSCH, the CBs of the PDSCH or PUSCH transmission are grouped into the configured number of CBGs based on a rule on how to group CBs. The rule on how to group CBs is described in the L1 specs. FFS how to operate CBG-based retransmission when the number of CBs is smaller than the configured number of CBGs. FFS how to group CBs for retransmission of the PDSCH and PUSCH