In one embodiment, a multicast communication is received at a particular node of a plurality of nodes receiving the multicast communication in a network. The particular node selects a subset of subcarriers using a probabilistic data structure, such that each of the plurality of nodes selects a respective subset of subcarriers using the probabilistic data structure. The particular node transmits an acknowledgement of receipt of the multicast communication on the subset of subcarriers selected by the particular node. The transmission occurs simultaneously with transmissions of acknowledgements from the other of the plurality of nodes.