A wireless communication device generates physical layer (PHY) protocol service data units (PSDUs), and, in response to determining that the PHY data unit is to be transmitted according to a HARQ process, generates HARQ coding units of a common length, each of the HARQ coding units including a respective set of one or more PSDUs, and individually encodes the HARQ coding units. The wireless communication device also generates a HARQ signal field to the included in a PHY preamble of the PHY data unit. The HARQ signal field includes i) a common information subfield to indicate one or more parameters that commonly apply to each of at least some of the one or more HARQ coding units and ii) a respective HARQ coding unit information subfield for each of the HARQ coding units to indicate one or more parameters that apply to only the corresponding HARQ coding unit.