Method and apparatus for error case handling during multicast HARQ retransmission

A user equipment (UE) for wireless communication, comprising:

• at least one memory;
• and
• at least one processor coupled with the at least one memory and configured to cause the UE to:
• receive, from a base station (BS), a first downlink control information (DCI) for scheduling a first transmission using a hybrid automatic repeat request (HARQ) process number, a cyclic redundancy check (CRC) of the first DCI being scrambled by a first radio network temporary identifier (RNTI);
• receive, from the BS, a third DCI for scheduling a third transmission using the HARQ process number, a CRC of the third DCI being scrambled by a third RNTI specific to the UE;
• and
• determine whether the third transmission is a retransmission of the first transmission or a retransmission of a second transmission scheduled by a second DCI, the second DCI scheduling the second transmission using the HARQ process number, a CRC of the second DCI scrambled by a second RNTI being common to a group of UEs including the UE.

A method performed by a base station, the method comprising:

• transmitting, to a user equipment (UE), a first downlink control information (DCI) for scheduling a first transmission using a hybrid automatic repeat request (HARQ) process number, a cyclic redundancy check (CRC) of the first DCI being scrambled by a first radio network temporary identifier (RNTI);
• transmitting, to a group of UEs including the UE, a second DCI for scheduling a second transmission using the HARQ process number, the CRC of the second DCI being scrambled by a second RNTI common to the group of UEs;
• determining that the second transmission is incorrectly decoded by the UE;
• transmitting, to the UE, a third DCI for scheduling a third transmission using the HARQ process number, a CRC of the third DCI being scrambled by a third RNTI specific to the UE, the third transmission carrying a same transport block (TB) as the first transmission or the second transmission;
• and
• transmitting, to the UE, an indication of whether the third transmission is a retransmission of the first transmission or a retransmission of the second transmission.

A base station for wireless communication, comprising:

• at least one memory;
• and
• at least one processor coupled with the at least one memory and configured to cause the base station to:
• transmit, to a user equipment (UE), a first downlink control information (DCI) for scheduling a first transmission using a hybrid automatic repeat request (HARQ) process number, a cyclic redundancy check (CRC) of the first DCI being scrambled by a first radio network temporary identifier (RNTI);
• transmit, to a group of UEs including the UE, a second DCI for scheduling a second transmission using the HARQ process number, the CRC of the second DCI being scrambled by a second RNTI common to the group of UEs;
• determine that the second transmission is incorrectly decoded by the UE;
• transmit, to the UE, a third DCI for scheduling a third transmission using the HARQ process number, a CRC of the third DCI being scrambled by a third RNTI specific to the UE, the third transmission carrying a same transport block (TB) as the first transmission or the second transmission;
• and
• transmit, to the UE, an indication of whether the third transmission is a retransmission of the first transmission or a retransmission of the second transmission.