Method and apparatus for transmitting HARQ-ACK feedback on unlicensed spectrum

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

• transmitting a first plurality of downlink transmissions, wherein a first hybrid automatic repeat request acknowledgement (HARQ-ACK) codebook corresponding to the first plurality of downlink transmissions is to be received in a first slot;
• transmitting a second plurality of downlink transmissions, wherein a second HARQ-ACK codebook corresponding to the second plurality of downlink transmissions is to be received in the first slot;
• receiving the first HARQ-ACK codebook on an uplink channel in the first slot;
• and
• receiving information indicating the second HARQ-ACK:
• in one or more demodulation reference signal REs of the uplink channel;
• based on multiplying an orthogonal sequence on a demodulation reference signal of the uplink channel;
• or
• in a sequence in the first slot.

A user equipment (UE), 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 a first plurality of downlink transmissions;
• generate a first hybrid automatic repeat request acknowledgement (HARQ-ACK) codebook corresponding to the first plurality of downlink transmissions, wherein the first HARQ-ACK codebook is to be transmitted in a first slot;
• receive a second plurality of downlink transmissions;
• generate a second hybrid HARQ-ACK codebook corresponding to the second plurality of downlink transmissions, wherein the second HARQ-ACK codebook is to be transmitted in the first slot;
• transmit the first HARQ-ACK codebook on an uplink channel in the first slot;
• and
• transmit information indicating the second HARQ-ACK:
• in one or more demodulation reference signal REs of the uplink channel;
• based on multiplying an orthogonal sequence on a demodulation reference signal of the uplink channel;
• or
• in a sequence in the first slot.

A base station, 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 a first plurality of downlink transmissions, wherein a first hybrid automatic repeat request acknowledgement (HARQ-ACK) codebook corresponding to the first plurality of downlink transmissions is to be received in a first slot;
• transmit a second plurality of downlink transmissions, wherein a second HARQ-ACK codebook corresponding to the second plurality of downlink transmissions is to be received in the first slot;
• receive the first HARQ-ACK codebook on an uplink channel in the first slot;
• and
• receive information indicating the second HARQ-ACK:
• in one or more demodulation reference signal REs of the uplink channel;
• based on multiplying an orthogonal sequence on a demodulation reference signal of the uplink channel;
• or
• in a sequence in the first slot.