Groupcast for sidelink communication

An apparatus comprising:

• at least one processor;
• and
• at least one memory including computer program code,
• the at least one memory and the computer program code configured to, with the at least one processor, cause the apparatus at least to:
• select, at a leader device in a group of devices, an orthogonal sequence and cover code from a first set of orthogonal sequences and a first set of orthogonal cover codes, the first set of orthogonal sequences and the first set of orthogonal cover codes used for acknowledgement feedback in the group;
• and
• send an indication of the selected orthogonal sequence and cover code to a first member device of a plurality of member devices in the group.

An apparatus comprising:

• at least one processor;
• and
• at least one memory including computer program code,
• the at least one memory and the computer program code configured to, with the at least one processor, cause the apparatus at least to:
• receive, at a member device from a leader device in a group of devices, an indication of an orthogonal sequence and cover code from a first set of orthogonal sequences and a first set of orthogonal cover codes, the first set of orthogonal sequences and the first set of orthogonal cover codes used for acknowledgement feedback in the group;
• and
• in response to detecting a packet groupcast in the group, send a positive acknowledgement for the packet using the orthogonal sequence and cover code.