A source node residing within a wireless mesh network is configured to transmit data packets to downstream nodes also residing within the wireless mesh network. Upon receipt of a data packet, a given downstream node determines a channel on which to transmit an acknowledgement packet and a sub-interval of time during which to transmit the acknowledgement packet based on a short ID assigned by the source node. At the determined sub-interval of time, the downstream node transmits the acknowledgement packet to the source node on the determined channel.