The disclosed subject matter is directed towards highly reliable Hybrid Automatic Repeat Request (HARQ) retransmission procedures, including to provide different levels of reliability for Sidelink transmissions. A scheduler node schedule a data transmission by a transmitter node, and can receive (and store) the data packet transmission. If the scheduler node receives a negative acknowledgement (NAK) from the receiver node, the scheduler node can allocate resources to the transmitter node to perform a retransmission of the data packet, and/or retransmit a copy of the data packet from the scheduler node to the receiver node. The scheduler node can inform the receiver node that a retransmission is being sent by the transmitter node and the scheduler node.