Communicating between stations over a shared medium comprises: receiving, at a destination station, a first waveform that includes one or more segments of a payload that originated from an origin station with a sequence of multiple segments, the one or more segments included in the first waveform having been transmitted over the shared medium by the origin station and by each of one or more repeater stations, and the first waveform indicating which of the sequence of multiple segments were not correctly decoded by at least one of the repeater stations; generating, based on the first waveform, acknowledgement information that specifies which of the sequence of multiple segments have been correctly decoded by the destination station; and transmitting a second waveform from the destination station over the shared medium, the second waveform including the acknowledgement information.